Ink set and inkjet recording method

Abstract

The ink set of the present invention comprises a treatment liquid and an ink, wherein the treatment liquid contains at least a polyvalent metal salt, a polyether-modified silicone, a water-soluble solvent, and water, and the ink contains a colorant and resin particles having a glass transition temperature within a range of 40 to 90°C. The cloud point of the treatment liquid is within a range of 40 to 90°C, and the dynamic surface tension of the treatment liquid at 25°C at a surface life of 15 ms is within a range of 25 to 35 mN / m.

Description

Technical Field

[0001] The present invention relates to an ink set and an inkjet recording method, and more particularly to an ink set that can achieve excellent adhesion to non-absorbent substrates and image abrasion resistance and has excellent storage stability. Background Art

[0002] Because inkjet recording allows for simple and inexpensive image creation, it is used in a wide range of printing fields, including photographs, various types of printing, logos, color filters, and other specialty printing applications. In particular, inkjet recording allows for digital printing without the use of printing plates, making it particularly suitable for applications requiring the formation of multiple images in small quantities.

[0003] In such inkjet recording methods, a technique is known in which a treatment liquid (also called a "pretreatment liquid" or "primer") containing a coagulant such as an organic acid or a polyvalent metal salt is pre-coated on a substrate, and the organic acid or polyvalent metal salt is used to coagulate and fix the pigment contained in the ink (pinning) to obtain a high-quality image recording.

[0004] On the other hand, the inclusion of a coagulant in the treatment liquid can reduce the abrasion resistance of the resulting image record. Therefore, a technique has been disclosed for obtaining an image record with excellent image quality and abrasion resistance by reducing the amount of treatment liquid deposited compared to the amount of ink deposited (see, for example, Patent Document 1).

[0005] However, when recording an image by applying ink to a non-absorbing substrate, good image quality cannot be obtained using only the technique described in Patent Document 1, and adhesion to the non-absorbing substrate is also insufficient.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 2018-165029 Summary of the Invention

[0009] The present invention has been made in view of the above-mentioned problems and circumstances, and aims to provide an ink set that can achieve excellent adhesion to non-absorbent substrates and image abrasion resistance, and has excellent storage stability. Furthermore, an inkjet recording method using the ink set is provided.

[0010] To solve the above-mentioned problems, the present inventors have conducted research into the causes of the above-mentioned problems and have discovered that by controlling the glass transition temperature of the resin particles contained in the ink to a specific range and regulating the cloud point and surface tension of the processing liquid, it is possible to provide an ink set that can achieve excellent adhesion to non-absorbent substrates and image abrasion resistance, as well as excellent storage stability. This has led to the completion of the present invention.

[0011] That is, the above-mentioned problems of the present invention can be solved by the following means.

[0012] 1. An ink set comprising a treatment liquid and ink,

[0013] The treatment liquid contains at least a polyvalent metal salt, polyether-modified silicone, a water-soluble solvent and water.

[0014] The ink contains a colorant and resin particles having a glass transition temperature in the range of 40 to 90°C.

[0015] The cloud point of the treatment liquid is within a range of 40 to 90° C., and the dynamic surface tension of the treatment liquid at 25° C. when the surface life is 15 ms is within a range of 25 to 35 mN / m.

[0016] 2. The ink set according to item 1, wherein the ink contains the resin fine particles having an agglomerability of 0.2 or less with a 0.15 mass % aqueous solution of calcium acetate monohydrate in an amount within a range of 3 to 15 mass %.

[0017] 3. The ink set according to item 1 or 2, wherein the dynamic surface tension of the ink at a surface life of 15 ms at 25°C is higher than the dynamic surface tension of the treatment liquid at a surface life of 15 ms at 25°C by 5 mN / m or more.

[0018] 4. The ink set according to any one of the first to third items, wherein the treatment liquid contains an SP value of 24 (J / cm 3 ) 1 / 2 The above-mentioned water-soluble solvents.

[0019] 5. The ink set according to any one of items 1 to 4, wherein the treatment liquid contains the polyvalent metal salt in a range of 0.5 to 20% by mass.

[0020] 6. The ink set according to any one of items 1 to 5, wherein the treatment liquid contains the polyether-modified silicone in an amount within a range of 0.1 to 2% by mass.

[0021] 7. An inkjet recording method for recording an image using the ink set according to any one of items 1 to 6, comprising the following steps:

[0022] a step of applying the treatment liquid to the recording area of ​​the non-absorbent substrate,

[0023] a step of applying the ink to the area to which the treatment liquid has been applied by an inkjet recording method, and

[0024] A step of heating the region to which the ink is applied at a heating temperature not lower than the cloud point and not lower than the glass transition temperature.

[0025] 8. The inkjet recording method according to item 7, further comprising applying the ink to the region to which the treatment liquid has been applied by an inkjet recording method in a state where the drying rate of the treatment liquid is 30% or less.

[0026] 9. The inkjet recording method according to item 7 or 8, wherein the amount of the resin fine particles applied is 80 times or less the amount of the polyether-modified silicone applied per unit area.

[0027] According to the above means of the present invention, an ink set can be provided that can achieve excellent adhesion to non-absorbent substrates and image abrasion resistance and has excellent storage stability. In addition, an inkjet recording method using the ink set can be provided.

[0028] The expression mechanism or action mechanism of the effects of the present invention is not clear, but is presumed as follows.

[0029] Since the ink contains a colorant and resin fine particles having a glass transition temperature within a range of 40 to 90° C., the resin fine particles soften during the ink drying process and form a uniform film, thereby achieving excellent image abrasion resistance.

[0030] Furthermore, the treatment liquid contains at least a polyvalent metal salt, a polyether-modified silicone, a water-soluble solvent, and water, and the cloud point of the treatment liquid is above 40°C, thereby achieving sufficient storage stability of the treatment liquid. Furthermore, since the cloud point is below 90°C, during the ink drying process, the polyether-modified silicone contained in the treatment liquid acts as a plasticizer for the resin particles contained in the ink, thereby achieving excellent adhesion to the substrate.

[0031] Furthermore, since the dynamic surface tension of the above-mentioned treatment liquid is in the range of 25 to 35 mN / m when the surface life is 15 ms at 25°C, the treatment liquid easily wets and spreads to the substrate (such as a non-absorbent substrate), and the ink has good adhesion to the non-absorbent substrate.

[0032] As described above, it is possible to produce an ink set that has good image abrasion resistance and adhesion to non-absorbent substrates, and excellent storage stability of the processing liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram showing an example of a recording apparatus preferred in the present invention.

[0034] Figure 2 It is a cross-sectional view showing a schematic structure of the image recorded material of the present invention.

[0035] Figure 3 It is a cross-sectional view of packaging material for canned food.

[0036] Figure 4 Schematic diagram showing an inkjet head used in Examples. DETAILED DESCRIPTION

[0037] The ink set of the present invention comprises a treatment liquid and an ink, wherein the treatment liquid contains at least a polyvalent metal salt, a polyether-modified silicone, a water-soluble solvent, and water, and the ink contains a colorant and resin particles having a glass transition temperature within a range of 40 to 90°C. The cloud point of the treatment liquid is within a range of 40 to 90°C, and the dynamic surface tension of the treatment liquid at a surface life of 15 ms at 25°C is within a range of 25 to 35 mN / m.

[0038] This feature is a common or corresponding technical feature in the following embodiments.

[0039] As an embodiment of the present invention, from the perspective of achieving excellent adhesion to a non-absorbent substrate by using resin fine particles having low cohesion, the ink preferably contains 3 to 15% by mass of the resin fine particles having a cohesion of 0.2 or less with a 0.15% by mass aqueous solution of calcium acetate monohydrate.

[0040] Furthermore, the dynamic surface tension of the ink at a surface life of 15 ms at 25° C. is preferably 5 mN / m or higher than the dynamic surface tension of the treatment liquid at a surface life of 15 ms at 25° C. By using an ink having a higher dynamic surface tension than the treatment liquid, ink bleeding can be prevented.

[0041] In order to suppress the precipitation of the polyvalent metal salt and obtain excellent discharge stability, it is preferred that the treatment liquid contain 5 to 40% by mass of a substance with an SP value of 24 (J / cm 3 ) 1 / 2 The above-mentioned water-soluble solvents.

[0042] Furthermore, from the perspective of preventing image bleeding, the treatment liquid preferably contains the polyvalent metal salt in a range of 0.5 to 20% by mass. Furthermore, a polyvalent metal salt content of 0.5% by mass or greater is preferred, as it improves adhesion to non-absorbent substrates. Furthermore, a polyvalent metal salt content of 20% by mass or less is preferred, as it improves the impact resistance of the image.

[0043] Furthermore, from the perspective of achieving excellent adhesion to non-absorbent substrates, the treatment liquid preferably contains 0.1 to 2 mass % of polyether-modified silicone, which is also preferred from the perspective of solubility of the polyether-modified silicone.

[0044] The inkjet recording method of the present invention is an inkjet recording method for recording an image using the ink set of the present invention. The method comprises the following steps: applying the treatment liquid to a recording area of ​​a non-absorbent substrate; applying the ink to the area applied with the treatment liquid by inkjet recording; and heating the area applied with the ink at a temperature above the cloud point and above the glass transition temperature. This method provides an inkjet recording method having excellent image abrasion resistance and adhesion to the substrate.

[0045] In order to obtain good adhesion to a non-absorbent substrate, it is preferred to include a step of applying the ink to the area to which the treatment liquid has been applied by an inkjet recording method when the drying rate of the treatment liquid is 30% or less.

[0046] Furthermore, in order to obtain excellent adhesion to a non-absorbent substrate, the amount of the resin fine particles applied is preferably 80 times or less of the amount of the polyether-modified silicone applied per unit area.

[0047] Hereinafter, the present invention and its constituent elements and modes and aspects for carrying out the present invention will be described. It should be noted that in this application, "to" is used to include the numerical values ​​described before and after it as the lower limit and the upper limit.

[0048] [Overview of the ink set of the present invention]

[0049] The ink set of the present invention comprises a treatment liquid and an ink, wherein the treatment liquid contains at least a polyvalent metal salt, a polyether-modified silicone, a water-soluble solvent, and water, and the ink contains a colorant and resin particles having a glass transition temperature within a range of 40 to 90°C. The cloud point of the treatment liquid is within a range of 40 to 90°C, and the dynamic surface tension of the treatment liquid at 25°C at a surface life of 15 ms is within a range of 25 to 35 mN / m.

[0050] The "treatment liquid" and "ink" of the present invention refer to a treatment liquid (also referred to as a "pretreatment liquid" or "primer") and an ink (also referred to as a "water-based ink" or "water-based ink") using at least water as a solvent. At least 60% by mass of the solvent used should be water.

[0051] <Cloud Point of Treatment Liquid>

[0052] The cloud point of the treatment liquid contained in the ink set of the present invention is within the range of 40 to 90°C, preferably within the range of 50 to 90°C.

[0053] In the present invention, the "cloud point" of the treatment liquid is the temperature at which 2 mL of the treatment liquid begins to become cloudy when the treatment liquid is placed in a glass container and heated.

[0054] In order to adjust the cloud point of the treatment liquid to be within the above range, the types and contents of the water-soluble solvent, the polyvalent metal salt, and the surfactant contained in the treatment liquid can be controlled, for example.

[0055] Specifically, as a water-soluble solvent, it is preferable to use a solvent having an SP value of 24 (J / cm 3 ) 1 / 2 The above water-soluble solvents are preferably used. In addition, as the polyvalent metal salt, for example, magnesium acetate, calcium acetate, etc. described below are preferably used, and as the surfactant, polyether-modified silicone is used.

[0056] Furthermore, as content in the treatment liquid, the water-soluble solvent is preferably within a range of 5 to 40 mass %, the polyvalent metal salt is preferably within a range of 0.5 to 20 mass %, and the surfactant is preferably within a range of 0.1 to 2 mass %.

[0057] Dynamic surface tension of the treatment fluid

[0058] At 25° C., the dynamic surface tension of the treatment liquid at a surface life of 15 ms is within a range of 25 to 35 mN / m.

[0059] In the present invention, the "dynamic surface tension" refers to the surface tension when the liquid surface is in a non-equilibrium state immediately after the formation of the liquid surface (gas-liquid interface), and is a value measured at 25°C by the maximum bubble pressure method.

[0060] In addition, "surface life" is the time elapsed from the formation of the liquid surface, that is, the life of the bubbles generated under the maximum bubble pressure method. It is also called bubble life and refers to the time from the moment a new interface is generated within the probe tip of the dynamic surface tensiometer to the time when the maximum bubble pressure is reached.

[0061] The dynamic surface tension of the treatment liquid can be measured using a dynamic surface tensiometer. Examples of the dynamic surface tensiometer include a bubble pressure dynamic surface tensiometer (manufactured by KRUSS, model "BP100").

[0062] Unless otherwise specified, the dynamic surface tension in this specification is a dynamic surface tension measured at 25° C. and a surface life of 15 ms using a maximum bubble pressure method.

[0063] In order to make the dynamic surface tension of the above-mentioned treatment liquid within the above-mentioned range, the type and content of the surfactant, the type and content of the water-soluble solvent, the type and content of the coagulant, etc. can be controlled. In particular, it is preferred that the polyether-modified silicone of the surfactant contained in the treatment liquid is within the range of 0.1 to 2 mass %. The polyether-modified silicone preferably contains trisiloxane, thereby reducing the dynamic surface tension of the treatment liquid to within the above-mentioned range. In addition, as a water-soluble solvent, it is preferred to use a solvent with an SP value of 24 (J / cm 3 ) 1 / 2 The above water-soluble solvent having a boiling point in the range of 150° C. to 250° C. is used, and the content thereof is in the range of 5 to 40% by mass.

[0064] Dynamic Surface Tension of Ink

[0065] The dynamic surface tension of the ink at 25°C when the surface life is 15 ms is preferably higher by 5 mN / m or more than the dynamic surface tension of the treatment liquid at 25°C when the surface life is 15 ms.

[0066] The dynamic surface tension of the ink can be measured by the same method as that for the dynamic surface tension of the treatment liquid described above.

[0067] Furthermore, the dynamic surface tension of the ink at 25° C. when the surface life is 15 ms is preferably within a range of 35 to 45 mN / m.

[0068] To adjust the dynamic surface tension of the ink to be within the above range, the type and content of the water-soluble solvent, the type and content of the surfactant, the type and content of the pigment dispersant, and the type and content of the resin fine particles can be controlled.

[0069] Specifically, the water-soluble solvent contained in the ink is preferably a polyol, with the content being in the range of 10 to 60% by mass. Furthermore, the surfactant is preferably a nonionic surfactant or an anionic surfactant, with the content being in the range of 0.1 to 2% by mass.

[0070] In addition, various low molecular weight dispersants, nonionic polymer dispersants, anionic polymer dispersants, or resin-coated pigment dispersions are preferably used as pigment dispersants. Furthermore, as the type of resin particles, polyester resins, acrylic resins, styrene acrylic resins, polyurethane resins, etc. are preferably used, and the content thereof is within the range of 3 to 15% by mass.

[0071] [Processing liquid]

[0072] The treatment liquid of the present invention aggregates or thickens the ink when recording an image on a substrate by inkjet printing, thereby accelerating ink image formation, improving the physical properties of the treatment liquid layer and the ink layer, or enhancing image quality.

[0073] The treatment liquid of the present invention contains at least a multivalent metal salt, polyether-modified silicone, a water-soluble solvent and water.

[0074] <Polyvalent Metal Salt>

[0075] By containing a material that generates aggregates when in contact with ink, that is, a flocculant that is a polyvalent metal salt, in the treatment liquid of the present invention, the interaction with the ink is enhanced, and the ink dots can be further fixed.

[0076] The polyvalent metal salt can aggregate anionic components (usually colorants or pigments) in the ink described later by salting out.

[0077] As the polyvalent metal salt, a salt of a metal having a valence of 2 or more can be used. The type of metal (cation) constituting the polyvalent metal salt is not particularly limited, and examples thereof include Ca 2+ 、Cu 2+ 、Ni 2+ Mg 2+ 、Zn 2+ 、Ba 2+ Other divalent metal ions, Al 3+ 、Fe 3+ Cr 3+ 、Y 3+ Other trivalent metal ions, Zr 4+ etc. tetravalent metal ions.

[0078] The type of salt constituting the polyvalent metal salt is not particularly limited, and for example, known salts such as carbonates, sulfates, nitrates, hydrochlorides, organic acid salts, borates, and phosphates can be used. Specific examples of particularly preferred polyvalent metal salts include calcium or magnesium salts of carboxylic acids such as calcium chloride or magnesium chloride, calcium or magnesium nitrate, magnesium acetate, calcium acetate or magnesium lactate, and calcium pantothenate.

[0079] Organic acids

[0080] In addition to the polyvalent metal salt, the treatment liquid of the present invention may further contain an organic acid as a coagulant. The organic acid can coagulate the anionic components in the ink by varying the pH. Monocarboxylic acids are preferred as organic acids because they do not weaken the cohesive force of the polyvalent metal salt.

[0081] The organic acid can aggregate the pigment contained in the ink described later.

[0082] Examples of the organic acid include formic acid, acetic acid, propionic acid, and benzoic acid.

[0083] It is preferred that the organic acid be one that is not completely neutralized by an alkali. Neutralization by an alkali means that the acidic groups of these acids form ionic bonds with other positively charged elements or compounds (e.g., inorganic compounds such as metals). Furthermore, not being completely neutralized means that the acidic groups of the organic acid contain acidic groups that do not form the aforementioned ionic bonds.

[0084] In addition, by using an organic acid, the storage stability of the treatment liquid is easily maintained, and sticking is less likely to occur after the treatment liquid is applied and dried. From this viewpoint, preferred organic acids include formic acid, acetic acid, propionic acid, benzoic acid, and the like.

[0085] <Inorganic acid>

[0086] The treatment liquid of the present invention may further contain an inorganic acid as a coagulant in addition to the polyvalent metal salt. The inorganic acid can coagulant the anionic components in the ink by varying the pH.

[0087] The inorganic acid can aggregate the pigment contained in the ink described later.

[0088] Examples of the inorganic acid include hydrochloric acid, nitric acid, sulfuric acid, and sulfamic acid.

[0089] The content of the polyvalent metal salt is preferably in the range of 0.5 to 20% by mass, more preferably 1 to 10% by mass, relative to 100% by mass of the total mass of the treatment liquid. This allows the anionic components in the ink to be effectively aggregated, which is preferable from the perspectives of image quality and image abrasion resistance.

[0090] When an organic acid is contained, the content of the organic acid is preferably within a range of 0.1 to 10% by mass, more preferably within a range of 1 to 3% by mass, relative to 100% by mass of the total mass of the treatment liquid.

[0091] When an inorganic acid is contained, the content of the inorganic acid is preferably in the range of 0.1 to 10 mass %, more preferably in the range of 1 to 3 mass %, relative to 100 mass % of the total mass of the treatment liquid.

[0092] The content of the polyvalent metal salt or organic acid in the aqueous solution can be measured by known methods, for example, in the case of a polyvalent metal salt, the content can be measured by ICP emission spectrometry, and in the case of an organic acid, the content can be measured by high performance liquid chromatography (HPLC).

[0093] It should be noted that when an organic acid is used, the amount of the organic acid added is preferably an amount that adjusts the pH of the treatment liquid to a level equal to or less than the neutralization equivalent of the anionic components contained in the ink. Furthermore, when the anionic component is a compound having a carboxyl group, the first dissociation constant of the organic acid is preferably 3.5 or less from the perspective of further reducing image bleeding.

[0094] <Polyether modified silicone>

[0095] The polyether-modified silicone contained in the treatment liquid of the present invention functions as a surfactant, improving the stability of the treatment liquid ejected from the nozzle and controlling the spread of the droplets (increase in ink dot diameter) that land on the recording medium. Examples of such polyether-modified silicone include siloxanes having alkylene oxide groups in the side chains and / or at both ends of the polydimethylsiloxane chain.

[0096] Specific examples include BYK-331, BYK-333, BYK-345, BYK-3450, BYK-3451, BYK-3455, BYK-346, BYK-347, BYK-348, and BYK-349 manufactured by BYK-Chemie, and TEGOWET KL245, TEGOWET 250, TEGOWET 260, TEGOWET 270, and TEGOWET 280 manufactured by Evonik. EGOWet280, KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-640, KF-642, KF-643, KF-644, KF-945, KF-6011, KF-6012, KF-6015, KF-6017, KF-6020, KF-6204, X-22-4515, etc. manufactured by Shin-Etsu Chemical Co., Ltd.

[0097] As polyether-modified silicone, trisiloxane having alkylene oxide groups in the side chains and / or at both ends of the polydimethylsiloxane chain is particularly preferred. The use of trisiloxane can effectively reduce the dynamic surface tension of the treatment liquid, resulting in an image with good adhesion to non-absorbent substrates.

[0098] As trisiloxane, a structure represented by the following general formula (1) is preferred.

[0099] General formula (1)

[0100]

[0101] In the general formula (1), "EO" represents a repeating unit structure of polyoxyethylene, i.e., a structure formed by ring-opening ethylene oxide as a three-membered cyclic ether. Furthermore, "PO" represents a repeating unit structure of polyoxypropylene, i.e., a structure formed by ring-opening propylene oxide as a three-membered cyclic ether. The phrase "[EO]m and [PO]n may be in any order" means that, in the compound molecule represented by the general formula (1), the order of the bonding positions relative to the siloxane backbone serving as the parent structure may be appropriately changed.

[0102] In the above general formula (1), X is preferably an alkylene group having 3 carbon atoms (ie, a propylene group).

[0103] In the general formula (1), m is preferably an integer of 5 to 20, and n is preferably an integer of 0 to 6.

[0104] Specific examples of the silicone surfactant having a structure represented by the general formula (1) are S-1 to S-8 shown below, but the present invention is not limited to these.

[0105] (S-1): In the above general formula (1), R = methyl, X = alkylene with 3 carbon atoms, m = 9, n = 0

[0106] (S-2): In the above general formula (1), R = butyl, X = alkylene with 3 carbon atoms, m = 25, n = 6

[0107] (S-3): In the above general formula (1), R = hydrogen atom, X = alkylene group with 3 carbon atoms, m = 3, n = 0

[0108] (S-4): In the above general formula (1), R = hydrogen atom, X = alkylene group with 3 carbon atoms, m = 33, n = 0

[0109] (S-5): In the above general formula (1), R = hydrogen atom, X = alkylene group having 3 carbon atoms, m = 22, n = 16

[0110] (S-6): In the above general formula (1), R = hydrogen atom, X = alkylene group with 3 carbon atoms, m = 9, n = 0

[0111] (S-7): In the above general formula (1), R = hydrogen atom, X = alkylene group with 3 carbon atoms, m = 12, n = 3

[0112] (S-8): In the above general formula (1), R = hydrogen atom, X = alkylene group having 3 carbon atoms, m = 1, n = 0

[0113] Examples of the trisiloxane include BYK-3450 and BYK-3451 manufactured by BYK-Chemie Japan, and TEGOWET-KL245, TEGOWET-250, and TEGOWET-260 manufactured by Evonik.

[0114] The content of the polyether-modified silicone is preferably within a range of 0.1 to 2 mass %, more preferably 0.5 to 1.5 mass %, relative to 100 mass % of the total mass of the treatment liquid.

[0115] In addition to the polyether-modified silicone described above, the treatment liquid may also contain a known surfactant. Examples of known surfactants include fluorine-based surfactants with high static surface tension reduction capabilities, anionic surfactants such as dioctylsulfosuccinate with high dynamic surface tension reduction capabilities, relatively low molecular weight polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, acetylene glycols, Pluronic surfactants (Pluronic is a registered trademark), and nonionic surfactants such as sorbitan derivatives.

[0116] Water

[0117] The water contained in the treatment liquid of the present invention is not particularly limited, and may be ion-exchanged water, distilled water, or pure water.

[0118] <Water-soluble solvent>

[0119] Examples of the water-soluble solvent contained in the treatment liquid of the present invention include alcohols, polyols, amines, amides, glycol ethers, and 1,2-alkanediols having 4 or more carbon atoms. It is particularly preferred to use a solvent having an SP value of 24 (J / cm 3 ) 1 / 2 The above water-soluble solvents.

[0120] By using an SP value of 24 (J / cm 3 ) 1 / 2 The above water-soluble solvents lower the turbidity point of the treatment liquid. Therefore, during the ink drying process, the treatment liquid can be heated to above the turbidity point, and an image with good adhesion to non-absorbent substrates can be obtained.

[0121] It should be noted that in the present invention, the SP value is called the solubility parameter. The SP value of the present invention is a value calculated by the Fedors method. It is calculated based on the molar heat of vaporization of the water-soluble solvent and the molar volume of the water-soluble solvent at 25°C. It should be noted that the unit of the SP value is usually cal, but when converted to the SI unit system, it is sufficient to use (cal / cm 3 ) 1 / 2=2.046×103(J / m 3 ) 1 / 2 In the following description, the unit of SP value is sometimes omitted, but SP value is (J / cm 3 ) 1 / 2 The value expressed in the unit of .

[0122] The above-mentioned SP value is 24 (J / cm 3 ) 1 / 2 Examples of the above water-soluble solvents include monohydric alcohols having 1 to 4 carbon atoms, polyhydric alcohols having 2 to 8 carbon atoms, polyalkylene glycols, and monoalkylpolyalkylene glycols.

[0123] Examples of the monohydric alcohols having 1 to 4 carbon atoms include methanol (SP value: 28.2), ethanol (SP value: 25.7), and 1-propanol (SP value: 24.2).

[0124] Examples of the polyols having 2 to 8 carbon atoms include ethylene glycol (SP value: 30.3), propylene glycol (SP value: 28.0), 1,3-propanediol (SP value: 32.9), 1,2-butanediol (SP value: 26.1), 1,3-butanediol (SP value: 30.3), 1,4-butanediol (SP value: 30.7), 2,3-butanediol (SP value: 29.9), 2-methyl-1,3-propanediol (SP value: 3 0.3), 1,2-pentanediol (SP value: 25.0), 1,5-pentanediol (SP value: 29.0), 1,2-hexanediol (SP value: 24.1), 1,6-hexanediol (SP value: 27.7), 3-methyl-1,5-pentanediol (SP value: 27.4), 2-methylpentane-2,4-diol (SP value: 26.8), glycerol (SP value: 33.5), trimethylolpropane (SP value: 32.5), etc.

[0125] Examples of the polyalkylene glycols include diethylene glycol (SP value: 30.6), triethylene glycol (SP value: 27.8), tetraethylene glycol (SP value: 26.1), and dipropylene glycol (SP value: 27.2).

[0126] Examples of the monoalkylpolyalkylene glycols include ethylene glycol monomethyl ether (SP value: 24.5).

[0127] The treatment liquid may contain one or more types selected from these water-soluble solvents in combination.

[0128] The total content of the water-soluble solvent is preferably within a range of 5 to 40% by mass, more preferably within a range of 10 to 40% by mass, relative to 100% by mass of the total mass of the treatment liquid.

[0129] The treatment liquid may contain other components such as a cross-linking agent, a mildew preventer, and a fungicide as appropriate within a range that does not impair the effects of the present invention.

[0130] Furthermore, for example, the ultraviolet absorbers described in Japanese Patent Application Laid-Open Nos. 57-74193, 57-87988, and 62-261476, Japanese Patent Application Laid-Open Nos. 57-74192, 57-87989, 60-72785, 61-146591, 1-95091, and 3-133 Various well-known additives such as anti-fading agents recorded in Japanese Patent Gazette No. 76, various anionic, cationic or nonionic surfactants, fluorescent brighteners recorded in Japanese Patent Gazette No. 59-42993, Japanese Patent Gazette No. 59-52689, Japanese Patent Gazette No. 62-280069, Japanese Patent Gazette No. 61-242871 and Japanese Patent Gazette No. 4-219266, defoaming agents, lubricants such as diethylene glycol, preservatives, thickeners, antistatic agents, etc.

[0131] The treatment liquid layer is preferably prepared by directly applying the treatment liquid of the present invention as a coating liquid onto a substrate and drying the coating liquid. The additives used in the treatment liquid are preferably fully dissolved before use as a coating liquid.

[0132] The treatment liquid can be preferably applied by inkjet coating, roll coating, rod coating, air knife coating, spin coating, curtain coating, or extrusion coating using a hopper as described in US Pat. No. 2,681,294. Inkjet coating is particularly preferred.

[0133] [Ink]

[0134] The ink of the present invention contains at least a colorant and resin fine particles having a glass transition temperature within a range of 40 to 90° C. It also preferably contains water and a water-soluble solvent.

[0135] Colorants

[0136] The colorant contained in the ink of the present invention is preferably a pigment.

[0137] As the above-mentioned pigment, anionic dispersible pigments, such as self-dispersible pigments having anionic groups on the surface, pigments dispersed by anionic polymer dispersants, and pigments dispersed by coating the surface with anionic resins are preferably used. Pigments dispersed by anionic polymer dispersants are particularly preferred because they have excellent dispersibility and react appropriately with the treatment liquid to achieve fixation.

[0138] As the pigment, conventionally known pigments can be used without particular limitation. For example, organic pigments such as insoluble pigments and lake pigments, and inorganic pigments such as titanium oxide can be preferably used.

[0139] In addition, with respect to titanium oxide, for which ink ejection stability and adhesion are generally difficult to ensure, the present invention makes it particularly suitable that bleeding does not occur easily and adhesion can be improved.

[0140] Titanium oxide has three crystal forms: anatase, rutile, and brookite. As a general type, it can be roughly divided into anatase and rutile. Although not particularly limited, rutile, which has a large refractive index and high concealment, is preferred. Specifically, the TR series of Fuji Titanium Industry Co., Ltd., the JR series of TAYCA Co., Ltd., and TIPAQUE of Ishihara Industry Co., Ltd. can be cited.

[0141] The insoluble pigment is not particularly limited, but preferably includes azo, azomethine, methine, diphenylmethane, triphenylmethane, quinacridone, anthraquinone, perylene, indigo, quinophthalone, isoindolinone, isoindolinone, azine, Azine, thiazine, di Oxazine, thiazole, phthalocyanine, diketopyrrolopyrrole, etc.

[0142] Specific examples of preferably usable organic pigments include the following.

[0143] Examples of the pigment for magenta or red include CI Pigment Red 2, CI Pigment Red 3, CI Pigment Red 5, CI Pigment Red 6, CI Pigment Red 7, CI Pigment Red 15, CI Pigment Red 16, CI Pigment Red 48:1, CI Pigment Red 53:1, CI Pigment Red 57:1, CI Pigment Red 122, CI Pigment Red 123, CI Pigment Red 139, CI Pigment Red 144, CI Pigment Red 149, CI Pigment Red 166, CI Pigment Red 177, CI Pigment Red 178, CI Pigment Red 202, CI Pigment Red 222, and CI Pigment Violet 19.

[0144] Examples of orange or yellow pigments include CI Pigment Orange 31, CI Pigment Orange 43, CI Pigment Yellow 12, CI Pigment Yellow 13, CI Pigment Yellow 14, CI Pigment Yellow 15, CI Pigment Yellow 15:3, CI Pigment Yellow 17, CI Pigment Yellow 74, CI Pigment Yellow 93, CI Pigment Yellow 128, CI Pigment Yellow 94, CI Pigment Yellow 138, and CI Pigment Yellow 155. In particular, CI Pigment Yellow 155 is preferred from the perspective of a balance between hue and light resistance.

[0145] Examples of the green or cyan pigment include CI Pigment Blue 15, CI Pigment Blue 15:2, CI Pigment Blue 15:3, CI Pigment Blue 16, CI Pigment Blue 60, and CI Pigment Green 7.

[0146] Moreover, as a pigment for black, CI Pigment Black 1, CI Pigment Black 6, CI Pigment Black 7 etc. are mentioned, for example.

[0147] Pigment dispersants

[0148] The treatment liquid of the present invention preferably contains a pigment dispersant for dispersing the above-mentioned pigment.

[0149] The pigment dispersant is not particularly limited, but is preferably a polymer dispersant having an anionic group, and pigment dispersants having a molecular weight within a range of 5,000 to 200,000 can be suitably used.

[0150] Examples of the polymer dispersant include block copolymers, random copolymers, and salts thereof, polyalkylene oxides, and polyalkylene oxide alkyl ethers having a structure derived from two or more monomers selected from styrene, styrene derivatives, vinylnaphthalene derivatives, acrylic acid, acrylic acid derivatives, maleic acid, maleic acid derivatives, itaconic acid, itaconic acid derivatives, fumaric acid, and fumaric acid derivatives.

[0151] The polymer dispersant preferably has an acryloyl group and is preferably neutralized with a neutralizing base before addition. The neutralizing base is not particularly limited, but is preferably an organic base such as ammonia, monoethanolamine, diethanolamine, triethanolamine, or morpholine. In particular, when the pigment is titanium oxide, it is preferably dispersed using a polymer dispersant having an acryloyl group.

[0152] The amount of the polymer dispersant added is preferably within a range of 10 to 100% by mass, more preferably within a range of 10 to 40% by mass, relative to the pigment.

[0153] The pigment is particularly preferably in the form of a so-called encapsulated pigment, in which the pigment is coated with the polymer dispersant. Various known methods can be used to coat the pigment with the polymer dispersant, and preferred examples include a phase inversion emulsification method, an acid precipitation method, or a method in which the pigment is dispersed with a polymerizable surfactant, a monomer is supplied thereto, and the coating is carried out while polymerization is carried out.

[0154] A particularly preferred method includes dissolving a water-insoluble resin in an organic solvent such as methyl ethyl ketone, partially or completely neutralizing the acidic groups in the resin with an alkali, adding a pigment and ion-exchanged water, dispersing the mixture, removing the organic solvent, and optionally adding water.

[0155] The average particle size of the dispersed pigment in the ink is preferably 50 nm or greater and less than 200 nm. This improves the dispersion stability of the pigment and the storage stability of the ink. The pigment particle size can be determined using commercially available particle size measurement equipment such as dynamic light scattering and electrophoresis. Dynamic light scattering is simple and can accurately measure the particle size range.

[0156] The pigment can be dispersed in a disperser together with a dispersant and other necessary additives depending on the desired purpose.

[0157] Conventionally known dispersers, such as ball mills, sand mills, wire mills, and high-pressure homogenizers, can be used. A sand mill is preferred because it provides a sharp particle size distribution for dispersing the pigment. While the material of the beads used in the sand mill is not particularly limited, zirconium oxide or zircon is preferred to prevent the formation of bead fragments and contamination by ionic components. Furthermore, the bead diameter is preferably within the range of 0.3 to 3 mm.

[0158] The content of the pigment in the ink is not particularly limited, but is preferably within a range of 7 to 18% by mass for titanium oxide and 0.5 to 7% by mass for organic pigments.

[0159] <Resin particles>

[0160] The resin fine particles (hereinafter also simply referred to as "resin") contained in the ink of the present invention have a glass transition temperature within the range of 40 to 90°C, and are preferably water-insoluble resin fine particles.

[0161] The glass transition temperature (Tg) can be determined by reading the Tg from an endothermic peak when the temperature is increased at a rate of 10°C / min in the temperature range of -30 to 200°C using a DSC (differential scanning calorimeter).

[0162] The water-insoluble resin used in the present invention is a water-insoluble resin that can accommodate ink and exhibits solubility or affinity for the ink.

[0163] Water-insoluble resin microparticles are originally water-insoluble resins that are dispersed in an aqueous medium as microscopic particles. These include water-insoluble resins that are forcibly emulsified and dispersed in water using an emulsifier or other agent, or water-insoluble resins that have hydrophilic functional groups introduced into the molecules, forming a self-emulsifiable stable aqueous dispersion without the use of emulsifiers or dispersion stabilizers. These resins are typically used in an emulsified and dispersed state in water or a water / alcohol mixture.

[0164] In the present invention, "water-insoluble" means that the amount of a resin dissolved in 100 g of water at 25°C after drying at 105°C for 2 hours is 10 g or less, preferably 5 g or less, and more preferably 1 g or less. If the resin has salt-forming groups, the solubility refers to the amount of the resin dissolved when the salt-forming groups are 100% neutralized with acetic acid or sodium hydroxide, depending on the type of the resin.

[0165] The resin having a glass transition temperature within the range of 40 to 90°C is preferably an acrylic resin, a polyurethane resin, a polyester resin, or a composite resin of a polyurethane resin and an acrylic resin, and particularly preferably an acrylic resin, a polyurethane resin, a polyester resin, or a composite resin of a polyurethane resin and an acrylic resin. The average particle size of the resin microparticles of these resins is preferably 200 nm or less. The average particle size is particularly preferably within the range of 100 to 150 nm.

[0166] The polyester resin, polyurethane resin, acrylic resin, or composite resin fine particles of polyurethane resin and acrylic resin are preferably anionic or nonionic.

[0167] Resin particles used in inks preferably contain an acid structure. This allows them to be dispersed in water even with a small amount of surfactant, improving the water resistance of the ink layer. This type of resin is called self-emulsifying, meaning that the polyurethane resin can be dispersed and stabilized in water solely through its molecular ionicity, without the use of a surfactant. Examples of acid structures include carboxyl groups (-COOH) and sulfonic acid groups (-SO3H). The acid structure can exist in the resin as a side chain or at the end.

[0168] The acid structure is preferably partially or entirely neutralized. Neutralization of the acid structure can improve the water dispersibility of the resin. Examples of neutralizing agents for neutralizing the acid structure are preferably organic amines, with trimethylamine, triethylamine, tripropylamine, tributylamine, N-methyldiethanolamine, triethanolamine, and other organic amines being particularly preferred.

[0169] The ink of the present invention preferably contains 3 to 15% by mass of resin fine particles having a cohesiveness of 0.2 or less with a 0.15% by mass aqueous solution of calcium acetate monohydrate. The use of such low-cohesive resin fine particles ensures high wettability to the substrate while achieving high injection stability, higher image quality, and excellent substrate adhesion.

[0170] In the present invention, "cohesion" is a value calculated from the following formula after measuring the balance according to the following procedure.

[0171] (i) 5 g of an aqueous solution of resin fine particles (solid content: 10% by mass) containing resin fine particles and 5 g of a 0.3% by mass aqueous solution of calcium acetate monohydrate were mixed.

[0172] (ii) The mixed solution is centrifuged.

[0173] (iii) About 2 g of the supernatant separated by centrifugation was collected.

[0174] (iv) About 2 g of the collected supernatant was dried by heating at 150° C. for 30 minutes, and the mass of the solid content (remainder (g)) was measured.

[0175] (V) The cohesiveness value was calculated by the following formula.

[0176] Formula: Cohesion = 1 - (mass of solid content (g) / mass of supernatant (g) × 5%)

[0177] Examples of the resin fine particles having a cohesiveness of 0.2 or less include VYLONAL MD2000 manufactured by Toyobo Co., Ltd., Mowinyl 6969D manufactured by Japan Coating Resin Co., Ltd., and EVAFANOLHA-560 manufactured by Nikka Chemical Co., Ltd.

[0178] Hereinafter, each resin will be described.

[0179] (Polyester resin)

[0180] The polyester resin having a polyester skeleton as the water-insoluble resin fine particles can be obtained using a polyol component and a polycarboxylic acid component such as a polycarboxylic acid, a polycarboxylic anhydride, or a polycarboxylic acid ester.

[0181] Examples of the polyol component include diols, specifically, alkylene glycols having 2 to 36 carbon atoms (ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, 1,6-hexanediol, etc.), alkylene ether glycols having 4 to 36 carbon atoms (diethylene glycol, triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polybutylene glycol, etc.), alicyclic glycols having 6 to 36 carbon atoms (1,4-cyclohexanediol, etc.), and alkylene glycols having 6 to 36 carbon atoms (1,4-cyclohexanediol, etc.). Methanol, hydrogenated bisphenol A, etc.), alkylene oxide adducts (ethylene oxide (hereinafter also abbreviated as EO), propylene oxide (hereinafter also abbreviated as PO), butylene oxide (hereinafter also abbreviated as BO)) having 2 to 4 carbon atoms of the above-mentioned alicyclic diols (addition mole range of 1 to 30), or alkylene oxide adducts (EO, PO, BO, etc.) having 2 to 4 carbon atoms of bisphenols (bisphenol A, bisphenol F, bisphenol S, etc.) having 2 to 4 carbon atoms (addition mole range of 2 to 30), etc. These may be used alone or in combination of two or more.

[0182] Examples of the polycarboxylic acid component include dicarboxylic acids (dicarboxylic acids), specifically, alkane dicarboxylic acids (such as succinic acid, adipic acid, and sebacic acid) having 4 to 36 carbon atoms, alkenyl succinic acids (such as dodecenyl succinic acid), alicyclic dicarboxylic acids (such as dimer acid (dimerized linoleic acid)) having 4 to 36 carbon atoms, olefin dicarboxylic acids (such as maleic acid, fumaric acid, citric acid, and mesaconic acid) having 4 to 36 carbon atoms, and aromatic dicarboxylic acids (such as phthalic acid, isophthalic acid, terephthalic acid, or derivatives thereof, and naphthalene dicarboxylic acids) having 8 to 36 carbon atoms. These may be used alone or in combination of two or more.

[0183] The number average molecular weight of the polyester resin is preferably within a range of 1,000 to 50,000, and more preferably within a range of 2,000 to 20,000.

[0184] As the polyester resin, commercially available products can be used. Examples of commercially available products having a glass transition temperature of 40 to 90° C. include VYLONAL MD-1100, MD-1200, MD-1245, MD-1500, and MD-2000 manufactured by Toyobo Co., Ltd., Pluscoat Z-221, Z-446, and Z-561 manufactured by Huying Chemical Co., Ltd., PESRESIN A-520, A-613D, A-615GE, A-640, A-645GH, A-647GEX, A-684G, A-690, and A-695GE manufactured by Takamatsu Oil & Fats Co., Ltd., and Elitel manufactured by Unitika Co., Ltd. KA-5034, KA-5071S, KA-1449, KA-0134, KA-3556, KA-6137, KZA-6034, KT-8803, KT-9511, etc. These may be used alone or in combination of two or more.

[0185] (Polyurethane resin)

[0186] As the polyurethane resin as the water-insoluble resin fine particles, a polyurethane resin having a hydrophilic group can be used.

[0187] The polyurethane resin is preferably an aqueous dispersion formed by dispersing a self-emulsifying polyurethane having water-soluble functional groups within its molecules, or an aqueous dispersion of a forced-emulsifying polyurethane emulsified under strong mechanical shearing force using a surfactant. The polyurethane resin in the aqueous dispersion can be obtained by reacting a polyol with an organic polyisocyanate and a hydrophilic group-containing compound.

[0188] Examples of the polyol that can be used to prepare the aqueous dispersion of the polyurethane resin include polyester polyol, polyether polyol, polycarbonate polyol, and polyolefin polyol.

[0189] Examples of polyester polyols include condensates of low molecular weight polyols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2- and 1,3-propylene glycol, neopentyl glycol, 1,3- and 1,4-butylene glycol, 3-methylpentanediol, hexamethylene glycol, 1,8-octanediol, 2-methyl-1,3-propanediol, bisphenol A, hydrogenated bisphenol A, trimethylolpropane, and cyclohexanedimethanol with polycarboxylic acids such as succinic acid, glutaric acid, adipic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, tetrahydrofuranic acid, terminal methinetetrahydrofuranic acid, and hexahydrophthalic acid.

[0190] Examples of the polyether polyol include polyethylene glycol, polypropylene glycol, polyethylene polytetramethylene glycol, polypropylene polytetramethylene glycol, and polytetramethylene glycol.

[0191] Examples of polycarbonate polyols can be obtained by reacting carbonic acid derivatives such as diphenyl carbonate, dimethyl carbonate, or phosgene with diols. Examples of these diols include ethylene glycol, diethylene glycol, triethylene glycol, 1,2- and 1,3-propylene glycol, neopentyl glycol, 1,3- and 1,4-butylene glycol, 3-methylpentanediol, hexamethylene glycol, 1,8-octanediol, 2-methyl-1,3-propanediol, bisphenol A, hydrogenated bisphenol A, trimethylolpropane, and cyclohexanedimethanol.

[0192] Examples of organic polyisocyanates that can be used in the preparation of aqueous dispersions of polyurethane resins include aromatic isocyanates such as tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymeric MDI, xylylene diisocyanate (XDI), and tetramethylxylylene diisocyanate (TMXDI); aliphatic isocyanates such as hexamethylene diisocyanate (HMDI); and alicyclic isocyanates such as isophorone diisocyanate (IPDI) and 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI, H12MDI). These can be used alone or in combination of two or more.

[0193] In addition, examples of hydrophilic group-containing compounds that can be used in the preparation of the aqueous dispersion of the polyurethane resin include carboxylic acid-containing compounds such as 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, 2,2-dimethylolbutanoic acid, 2,2-dimethylolvaleric acid, and glycine, and their derivatives such as sodium salts, potassium salts, and amine salts; and sulfonic acid-containing compounds such as taurine (i.e., aminoethylsulfonic acid) and ethoxypolyethylene glycol sulfonic acid, and their derivatives such as sodium salts, potassium salts, and amine salts.

[0194] The polyurethane resin can be obtained by a known method. For example, the polyol, organic polyisocyanate, and hydrophilic group-containing compound are mixed and reacted at 30 to 130° C. for 30 minutes to 50 hours to obtain a polyurethane prepolymer.

[0195] The polyurethane prepolymer is polymerized by being extended using a chain extender to form a polyurethane resin having a hydrophilic group. The chain extender is preferably water and / or an amine compound. By using water or an amine compound as a chain extender, the isocyanate-terminated prepolymer can be efficiently extended by reacting with the free isocyanate in a short time.

[0196] Examples of amine compounds used as chain extenders include aliphatic polyamines such as ethylenediamine and triethylenediamine; aromatic polyamines such as m-xylylenediamine and toluenediamine; and polyhydrazine compounds such as hydrazine and adipic acid dihydrazide. These amine compounds may contain, along with the polyamines, a monoamine such as dibutylamine or methyl ethyl ketoxime as a reaction terminator, to the extent that polymerization is not significantly inhibited.

[0197] It should be noted that in the synthesis of the polyurethane prepolymer, a solvent that is not inert to isocyanate and can dissolve the polyurethane prepolymer can be used. Examples of such solvents include diisocyanates. Alkane, methyl ethyl ketone, dimethylformamide, tetrahydrofuran, N-methyl-2-pyrrolidone, toluene, and propylene glycol monomethyl ether acetate, etc. These hydrophilic organic solvents used in the reaction step are preferably removed in the end.

[0198] In addition, in the synthesis of the polyurethane prepolymer, in order to promote the reaction, catalysts such as amine catalysts (such as triethylamine, N-ethylmorpholine, triethylenediamine, etc.), tin catalysts (such as dibutyltin dilaurate, dioctyltin dilaurate, tin octoate, etc.) and titanium catalysts (such as tetrabutyl titanate, etc.) can be added.

[0199] The number average molecular weight of the polyurethane resin is preferably increased as much as possible by introducing a branched structure and an internal cross-linked structure, and is preferably within a number average molecular weight of 50,000 to 10,000,000. This is because by making the molecular weight within the above range, the polyurethane resin is not easily dissolved in the solvent, so a coating film with excellent durability and water resistance can be obtained. It should be noted that the number average molecular weight (Mn) is a value measured by gel permeation chromatography (GPC), for example, using "RID-6A" manufactured by Shimadzu Corporation (column: "TSK-GEL" manufactured by Tosoh Corporation, solvent: tetrahydrofuran (THF), column temperature: 40°C), and can be obtained based on a calibration curve prepared using a polystyrene standard sample.

[0200] Commercially available polyurethane resins having a glass transition temperature of 40 to 90° C. include Neorez R-967, R-600, and R-9671 manufactured by Kusumoto Chemicals, EVAFANOL HA-560 manufactured by Nikka Chemicals, and SF870 manufactured by Daiichi Kogyo Seiyaku Co., Ltd.

[0201] (Acrylic resin)

[0202] The acrylic resin as the water-insoluble resin fine particles can be obtained by using a copolymer with an acrylic acid ester component, a methacrylic acid ester component, a styrene component, or the like.

[0203] Examples of the acrylate component and the methacrylate component include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, cyclohexyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, isobornyl (meth)acrylate, benzyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, benzyl (meth)acrylate, glycidyl (meth)acrylate, (meth)acrylic acid, (di)ethylene glycol di(meth)acrylate, 1,4-butylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, glyceryl di(meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, and acrylamide.

[0204] Examples of the styrene component include styrene, 4-methylstyrene, 4-hydroxystyrene, 4-acetoxystyrene, 4-acetylstyrene, and styrenesulfonic acid, etc. These components may be used alone or in combination of two or more.

[0205] The number average molecular weight (Mn) of the acrylic resin is preferably 1,000 to 50,000, more preferably 2,000 to 20,000. This is because if the number average molecular weight (Mn) of the acrylic resin is 1,000 or more, the cohesive force of the coating film becomes stronger and the adhesion is improved. If it is 50,000 or less, the solubility in organic solvents is good, and the particle size of the emulsified dispersion is promoted. It should be noted that the number average molecular weight (Mw) is a value measured by gel permeation chromatography (GPC). For example, it can be determined using "RID-6A" manufactured by Shimadzu Corporation (column: "TSK-GEL" manufactured by Tosoh Corporation, solvent: tetrahydrofuran (THF), column temperature: 40°C) based on a calibration curve prepared using a polystyrene standard sample.

[0206] Commercially available products may be used as the acrylic resin. Examples of commercially available products having a glass transition temperature of 40 to 90°C include acrylic emulsions such as Mowinyl 6899D, 6969D, and 6800 manufactured by Japan Coating Resin Co., Ltd. and TOCRYL W-7146, W-7147, W-7148, W-7149, and W-7150 manufactured by Toyochem Co., Ltd.

[0207] (Composite resin particles)

[0208] The composite resin particles that may be contained in the ink are preferably composite resin particles formed by emulsifying an acrylic resin with a polyurethane resin, that is, composite resin particles having an inner layer composed of an acrylic resin and a surface layer composed of a polyurethane resin.

[0209] Here, the polyurethane resin is present at the interface between the acrylic resin as the water-insoluble resin fine particles and water as the continuous phase, and functions as a water-insoluble resin fine particle layer different from the resin protecting the water-insoluble resin fine particles.

[0210] By preparing composite resin particles in which acrylic resin is emulsified with polyurethane resin, the physical properties of the image (coating film) can be improved compared to the case where acrylic resin and polyurethane resin are emulsified separately and then mixed, and the storage stability of the composite resin particles can also be improved.

[0211] In the composite resin particles formed by emulsifying the acrylic resin with the polyurethane resin, the mass ratio (U / A) of the polyurethane resin (U) to the acrylic resin (A) is preferably 40 / 60 to 95 / 5. When the polyurethane resin (U) is present in the above-mentioned range, the physical properties of the image (coating film) can be improved. Furthermore, when the acrylic resin (A) is present in the above-mentioned range, excellent adhesion to the acrylic film is achieved. Within the above-mentioned ratios, the mass ratio (U / A) of the polyurethane resin (U) to the acrylic resin (A) is preferably 40 / 60 to 80 / 20.

[0212] The total resin concentration of the acrylic resin and the polyurethane resin in the composite resin particles is not particularly limited, but is preferably 5.0% by mass or more, more preferably 10.0 to 70.0% by mass. When the resin concentration is within this range, the fixing properties between the substrate and the ink are good.

[0213] In addition, in the emulsification of the acrylic resin with the polyurethane resin, the polyurethane resin and a surfactant functioning as an emulsifier can be used. Here, the storage stability of the composite resin particles can be improved by adding the emulsifier.

[0214] As the emulsifier, anionic surfactants and nonionic surfactants can be used. In the present invention, it is preferred to use either anionic surfactant or nonionic surfactant, and more preferably, both. The combined amount of the anionic surfactant and nonionic surfactant is preferably 1.0 to 20.0 parts by mass per 100 parts by mass of the total resin mass. Furthermore, by setting the combined amount of the anionic surfactant and nonionic surfactant to 20.0 parts by mass or less, water resistance and solvent resistance can be improved.

[0215] The mass ratio (X / Y) of the anionic surfactant (X) to the nonionic surfactant (Y) is preferably 100 / 0 to 50 / 50. By adjusting the amount of the anionic surfactant to be added within the above range, emulsification and storage stability can be further improved.

[0216] Examples of anionic surfactants that can be used for emulsification include alkyl sulfates, polyoxyethylene alkyl ether sulfates, sulfosuccinates, α-olefin sulfonates, N-acylamino acid salts, carboxylates, and phosphates. Among these, sulfosuccinates and α-olefin sulfonates are preferred.

[0217] Examples of the type of salt are not particularly limited, and include metal salts such as sodium salts, potassium salts, and magnesium salts, and triethanolamine salts.

[0218] Examples of nonionic surfactants that can be used for emulsification include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkylamine ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, sucrose fatty acid esters, etc. Among these, polyoxyethylene alkyl ethers and polyoxyethylene alkylphenyl ethers are preferred.

[0219] The average particle size of the composite resin microparticles is not particularly limited, but is preferably 10 to 500 nm, more preferably 10 to 300 nm, and even more preferably 10 to 200 nm. The average particle size can be determined using commercially available particle size measurement equipment such as dynamic light scattering and electrophoresis. However, dynamic light scattering is simple and can accurately measure the particle size range.

[0220] By using composite resin fine particles formed by emulsifying an acrylic resin with a polyurethane resin, it is possible to improve the fixability of an image (coating film) to a low-absorbing substrate or a non-absorbing substrate.

[0221] <Water-soluble solvent>

[0222] Examples of the water-soluble solvent contained in the ink of the present invention include alcohols, polyols, amines, amides, glycol ethers, and 1,2-alkanediols having 4 or more carbon atoms.

[0223] Examples of the alcohols include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, tert-butanol, 3-methoxy-1-butanol, 3-methoxy-3-methylbutanol, 1-octanol, 2-octanol, n-nonanol, tridecanol, n-undecanol, stearyl alcohol, oleyl alcohol, and benzyl alcohol.

[0224] Examples of the polyols include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol having 5 or more ethylene oxide groups, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol having 4 or more propylene oxide groups, butanediol, hexanediol, pentanediol, glycerol, hexanetriol, and thiodiglycol.

[0225] Examples of the amines include ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, pentamethyldiethylenetriamine, and tetramethylpropylenediamine.

[0226] Examples of the amides include formamide, N,N-dimethylformamide, and N,N-dimethylacetamide.

[0227] Examples of the glycol ethers include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, propylene glycol monopropyl ether, dipropylene glycol monomethyl ether, and tripropylene glycol monomethyl ether.

[0228] Examples of the 1,2-alkanediols having 4 or more carbon atoms include 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, and 1,2-heptanediol.

[0229] Particularly preferred water-soluble solvents are polyols, which can appropriately suppress bleeding during high-speed printing. Specifically, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, and tripropylene glycol are preferred.

[0230] The ink may contain one or more selected from these water-soluble solvents in combination.

[0231] The content of the water-soluble solvent in the ink is not particularly limited, but is preferably within a range of 10 to 60% by mass.

[0232] <Water, other additives>

[0233] The water contained in the ink of the present invention is not particularly limited, and may be ion-exchanged water, distilled water, or pure water.

[0234] The ink of the present invention may contain a surfactant as needed, which can improve the ink injection stability and control the spread (dot diameter) of the droplets landed on the recording medium.

[0235] The surfactant used in the ink of the present invention is not particularly limited. However, when other structural components of the ink contain anionic compounds, the surfactant is preferably anionic, nonionic, or betaine-type. In particular, in the present invention, the presence of an alkaline component in anionic surfactants or other surfactants reduces the cohesion of the pigment and also facilitates the cohesion of the resin particles themselves. Therefore, the surfactant is preferably nonionic.

[0236] In the present invention, it is preferred to use fluorine-based or silicone-based surfactants with high static surface tension reduction capabilities, anionic surfactants such as dioctylsulfosuccinate with high dynamic surface tension reduction capabilities, and nonionic surfactants such as relatively low molecular weight polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, acetylene glycols, Pluronic (registered trademark)-type surfactants, and sorbitan derivatives. It is also preferred to use fluorine-based or silicone-based surfactants in combination with surfactants with high dynamic surface tension reduction capabilities.

[0237] The content of the surfactant in the ink is not particularly limited, but is preferably within a range of 0.1 to 5.0% by mass.

[0238] In addition to the above, the ink used in the present invention may contain various known additives, such as polysaccharides, viscosity modifiers, resistivity modifiers, film-forming agents, ultraviolet absorbers, antioxidants, anti-fading agents, mildew inhibitors, and rust inhibitors, as needed, in accordance with the purpose of improving injection stability, print head and ink cartridge compatibility, storage stability, image preservation, and other properties. Examples of these additives include liquid paraffin, dioctyl phthalate, tricresyl phosphate, oil droplets such as silicone oil, and additives such as those disclosed in Japanese Patent Application Laid-Open Nos. 57-74193, 57-87988, and 62-261476. etc., the ultraviolet absorbers described in Japanese Patent Application Laid-Open No. 57-74192, Japanese Patent Application Laid-Open No. 57-87989, Japanese Patent Application Laid-Open No. 60-72785, Japanese Patent Application Laid-Open No. 61-146591, Japanese Patent Application Laid-Open No. 1-95091, Japanese Patent Application Laid-Open No. 3-13376, etc., the fluorescent whitening agents described in Japanese Patent Application Laid-Open No. 59-42993, Japanese Patent Application Laid-Open No. 59-52689, Japanese Patent Application Laid-Open No. 62-280069, Japanese Patent Application Laid-Open No. 61-242871, Japanese Patent Application Laid-Open No. 4-219266, etc.

[0239] The ink used in the present invention having the above-mentioned structure preferably has a viscosity of 1 to 40 mPa·s at 25° C., and more preferably 2 to 10 mPa·s.

[0240] [Inkjet Recording Method]

[0241] The inkjet recording method of the present invention is an inkjet recording method for recording images using an ink set comprising the aforementioned treatment liquid and ink. Using this ink set, for example, a single inkjet printer can be used to efficiently and continuously apply the treatment liquid comprising the ink set of the present invention and print with the ink on the surface of a non-absorbent substrate. Furthermore, high-quality text, graphics, and the like can be printed with minimal variation in dot diameter between substrates.

[0242] Specifically, the inkjet recording method of the present invention comprises the following steps: a step of imparting the above-mentioned treatment liquid to the recording area of ​​the non-absorbent substrate (treatment liquid imparting step); a step of imparting the above-mentioned ink to the area imparted with the above-mentioned treatment liquid by inkjet recording (ink imparting step); and a step of heating the area imparted with the above-mentioned ink at a heating temperature above the above-mentioned turbidity point and above the above-mentioned glass transition temperature (ink heating step).

[0243] Furthermore, the inkjet recording method of the present invention may further include, in addition to the above steps, a step of drying the treatment liquid applied to the substrate to form a treatment liquid layer after the treatment liquid applying step.

[0244] Furthermore, in the inkjet recording process, it is preferred that the ink be applied to the area to which the treatment liquid has been applied while the drying rate of the treatment liquid is 30% or less. The ink application process is preferably performed within 10 seconds after the treatment liquid application process. It is particularly preferred that the ink application process be performed within 0.1 to 5 seconds after the treatment liquid application process while the drying rate of the treatment liquid is within the range of 1 to 10%.

[0245] <Non-absorbent substrate>

[0246] As the non-absorbing substrate that can be used in the inkjet recording method of the present invention, a known plastic film can be used.

[0247] In the present invention, "non-absorbent" means non-absorbent with respect to water.

[0248] Specific examples of the known plastic films include polyester films such as polyethylene terephthalate, polyethylene films, polypropylene films, polyamide films such as nylon, polystyrene films, polyvinyl chloride films, polycarbonate films, polyacrylonitrile films, biodegradable films such as polylactic acid films, and the like.

[0249] In addition, films coated with polyvinylidene chloride on one or both sides or films deposited with metal oxides can also be preferably used to impart gas barrier properties, moisture resistance, and aroma retention. Non-absorbent films can preferably be unstretched or stretched films.

[0250] In the case of a plastic film, the thickness of the substrate is preferably in the range of 10 to 120 μm, more preferably 12 to 60 μm.

[0251] Alternatively, non-absorbent substrates such as tinplate for three-piece cans and tin-free steel sheets (TFS sheets, thickness 0.1 to 0.6 μm) can be preferably used. These can be suitably used, for example, in packaging materials for canned foods that have a thermosetting resin coating layer. These canned food packaging materials, for example, block air, moisture, and light to seal the food inside. Therefore, epoxy-phenolic coatings or polyester-based laminating agents are typically used on the food side, while polyester-based or acrylic-based thermosetting coatings are used on the outside.

[0252] Hereinafter, each step of the inkjet recording method will be described.

[0253] <Treatment liquid application step>

[0254] In the treatment liquid applying step, the treatment liquid is applied onto the recording medium of the non-absorbent substrate.

[0255] The method for applying the treatment liquid to the non-absorbent recording medium is not particularly limited, and preferred examples include roll coating, curtain coating, spray coating, and inkjet coating. Among these, the inkjet method is preferred for applying the treatment liquid because it prevents the application of the coagulant to areas not coated with ink, thereby preventing unreacted coagulant from being released and causing turbidity.

[0256] In this case, as described later, when the substrate used is a metal substrate, etc., it is also preferred to arrange the metal substrate on the conveyor belt, apply the treatment liquid layer while conveying the belt, or use a flatbed printer with a fixed substrate to form the treatment liquid layer.

[0257] <Treatment liquid drying process>

[0258] In the present invention, as described above, the ink application step is preferably performed with the treatment liquid having a drying rate of 30% or less. In particular, the drying rate is more preferably 10% or less. The ink application step (ink application step) is preferably performed immediately and continuously after the treatment liquid application step. When the ink application step is performed continuously or when the ink application step and the treatment liquid application step are performed simultaneously, the treatment liquid and the ink are dried simultaneously. The drying rate of the treatment liquid is defined by the following formula.

[0259] (Drying rate of treatment liquid) = 1 - ((Mass of treatment liquid after drying (g)) / (Mass of treatment liquid before drying (g))

[0260] If the drying rate of the treatment liquid is within the range of 30% or less, the treatment liquid drying step can be performed between the treatment liquid application step and the ink application step. The treatment liquid drying step is a step in which the treatment liquid applied to the non-absorbent recording medium is dried to form a treatment liquid layer. The treatment liquid can be dried under conditions that remove water, a water-soluble solvent, or other solvent components of the treatment liquid. The drying temperature of the treatment liquid is preferably within the range of 40 to 80°C, for example. The drying time of the treatment liquid is preferably within the range of 1 to 30 seconds, for example.

[0261] The drying of the treatment liquid can be carried out by a non-contact heating type drying device such as a drying oven, a hot air blower, etc., or by a contact heating type drying device such as a hot plate, a hot roller, etc. In addition, a non-contact infrared heater can be used to dry the treatment liquid by infrared irradiation.

[0262] As for the drying temperature, (a) when using a non-contact heating type drying device such as a drying furnace or a hot air blower, the drying temperature can be obtained by measuring the ambient temperature such as the temperature inside the furnace or the hot air temperature; (b) when using a contact heating type drying device such as a heating plate or a hot roller, the drying temperature can be obtained by measuring any one temperature selected from the temperature of the contact heating portion or the surface temperature of the dried surface; (c) when using an infrared heater, the drying temperature can be obtained by measuring the surface temperature of the irradiated surface during the entire period of drying the treatment liquid.

[0263] <Ink application process>

[0264] The ink applying step is a step of applying the ink of the above-mentioned ink set by an inkjet method simultaneously with or immediately after forming the treatment liquid layer on the non-absorbent substrate recording medium.

[0265] In the ink application step, the ink is applied so that the amount of the resin fine particles applied relative to the amount of the polyether-modified silicone applied (also referred to as "applied amount") per unit area is preferably 80 times or less, more preferably 5 to 40 times.

[0266] To achieve the above-described application amount, for example, the content of the polyether-modified silicone in the treatment liquid or the content of the resin fine particles in the ink may be adjusted, or the amounts of the treatment liquid and ink droplets applied may be adjusted.

[0267] The inkjet method is not particularly limited, and a printer equipped with an inkjet head filled with ink can be used. Specifically, ink droplets can be ejected from the nozzles of the inkjet head based on digital signals and landed on the treatment liquid layer on the substrate to perform printing.

[0268] The inkjet head may be either a drop-on-demand or continuous inkjet head. Examples of drop-on-demand inkjet heads include single-chamber, dual-chamber, flexure, piston, shared pattern, and shared wall electro-mechanical types, as well as thermal inkjet and bubble jet ("bubble jet" is a registered trademark of Canon Inc.) electro-thermal types.

[0269] Among the above-mentioned inkjet heads, an inkjet head using a piezoelectric element as an electro-mechanical conversion element used in an electro-mechanical conversion system (also referred to as a piezoelectric inkjet head) is preferable.

[0270] The inkjet printer may be a scanning type or a single-pass type inkjet head. In the case of the single-pass type, a line head type inkjet head is preferably used.

[0271] A line head inkjet head is an inkjet head having a length greater than the width of the printing area. A line head inkjet head can be a single head greater than the width of the printing area, or a combination of multiple heads can be used to achieve a length greater than the width of the printing area.

[0272] Alternatively, a plurality of heads may be arranged side by side so that their nozzles are arranged in a staggered pattern, thereby improving the resolution of the heads as a whole.

[0273] The transport speed of the non-absorbent substrate recording medium can be set, for example, within the range of 1 to 120 m / min. The faster the transport speed, the faster the image formation speed. According to the present invention, even at very fast line speeds of 50 to 120 m / min, which are applicable to single-pass inkjet image formation methods, high-definition images with high ink fixability can be produced.

[0274] <Ink Heating Process>

[0275] In the ink heating step, the ink applied to the non-absorbent recording medium, specifically the area where the ink has been applied, is heated. This dries the ink. Even if the treatment liquid drying step is omitted, the treatment liquid can still be dried during the ink heating step.

[0276] The heating temperature of the region to which the ink is applied in the ink heating step is a temperature not less than the cloud point of the treatment liquid and not less than the glass transition temperature of the resin fine particles contained in the ink.

[0277] Specifically, the temperature is preferably within a range of 60 to 200°C.

[0278] By heating the ink-applied area in this manner, water and water-soluble solvents, which are the ink's solvent components, are primarily removed. Furthermore, the polyvalent metal salt in the metal substrate is dried and thermally decomposed at a temperature above its thermal decomposition temperature. This also improves the image's abrasion resistance and adhesion to non-absorbent substrates.

[0279] The ink can be dried (heated) using the same method as the aforementioned drying of the treatment liquid. The ink heating time is preferably adjusted appropriately depending on the type of non-absorbent substrate and the amount of ink applied. However, when using a non-contact heating drying device such as a drying oven or hot air blower, or a contact heating drying device such as a hot plate or heated roller, the heating time is preferably 1 to 10 minutes. When using an infrared heater, the heating time is preferably 1 to 30 seconds.

[0280] The thickness of the ink layer is preferably within the range of 0.3 to 3.0 μm, more preferably within the range of 0.5 to 2.0 μm. When the ink layer thickness is 0.3 μm or greater, the adhesion and abrasion resistance of the image are easily improved. When the ink layer thickness is 3.0 μm or less, the deformation stress applied to the ink layer is reduced, thus minimizing the adhesion of the image.

[0281] [Recording device]

[0282] Figure 1 This is a schematic diagram of a preferred recording device in the present invention. However, the present invention is not limited thereto. For example, Figure 1 In the recording apparatus 1 shown, the first drying section 14 may be omitted.

[0283] The recording apparatus 1 mainly includes a treatment liquid applying section 10 and an ink applying section 20. The treatment liquid applying section 10 forms a treatment liquid layer C on a substrate F, and the ink applying section 20 forms an ink layer R.

[0284] The treatment liquid applying unit 10 is not particularly limited as long as it can apply the treatment liquid to the substrate, but in the present invention, it is preferably an inkjet head 21. In addition to the inkjet head 21, for example, a roll coater may be used.

[0285] The ink applying section 20 is an inkjet head 21 that can eject ink.

[0286] In such a recording apparatus 1 , the inkjet head 11 discharges process liquid droplets 12 onto the substrate F drawn out from the delivery roller 30 to form a process liquid layer C. Next, the process liquid layer C is dried by the first drying unit 14 .

[0287] Next, ink droplets 22 are ejected from the inkjet head 21 onto the treatment liquid layer C, forming an ink layer R. The second drying section 23 heats and dries the ink-applied area at a temperature above the cloud point of the treatment liquid of the present invention and above the glass transition temperature of the resin particles contained in the ink of the present invention. The substrate F, on which the treatment liquid layer C and ink layer R are formed, is then wound up by a winding roller 40 to produce an image recorded object.

[0288] It should be explained that Figure 1 In the figure, the case where the substrate F is a film substrate is shown, but in the case of a metal substrate, the metal substrate can be arranged on a conveyor belt, and the treatment liquid layer C and the ink layer R can be formed by single-pass coating while the conveyor belt is conveyed.

[0289] in addition, Figure 1 In the present invention, a device is used in which the ink is applied after the treatment liquid is applied to the substrate. However, from the viewpoint of ejecting the ink from the inkjet head when the drying rate of the treatment liquid layer is below 30%, a device is more preferably used in which the treatment liquid and the ink are applied simultaneously.

[0290] Furthermore, as Figure 1 In addition to the recording device shown in [ ], a flatbed printer is also preferably used for applying the treatment liquid and ink. Flatbed printers can fix the substrate and move the inkjet head in the main scanning direction and a sub-scanning direction intersecting the main scanning direction, allowing printing without transporting the substrate. Since metal substrates such as tinplate cannot be transported roll-to-roll like resin film materials, a flatbed printer that does not require substrate transport is preferably used.

[0291] As such a flatbed printer, there is the one disclosed in Japanese Patent Application Laid-Open No. 2015-74161. Figure 1 、Japanese Patent Application Publication No. 2017-177578 Figure 1 The printer described in is taken as an example.

[0292] [Visual Records]

[0293] The image recorded material of the present invention preferably comprises a substrate, a treatment liquid layer formed on the substrate using the treatment liquid, and an ink layer formed on the treatment liquid layer using the ink.

[0294] like Figure 2 As shown, the image recorded material P is coated with the treatment liquid of the present invention on a substrate F by coating with a roll coater or ejecting from an inkjet head to form a treatment liquid layer C. Ink is ejected from the inkjet head to a position where the treatment liquid layer C is fixed, and fixing is performed to form an image recording layer R.

[0295] The above configuration represents a minimum configuration. Other functional layers may be formed between the substrate and the treatment liquid layer. Furthermore, a non-absorbent film substrate may be attached to the upper layer of the ink layer via, for example, a laminating adhesive layer. A configuration in which at least the treatment liquid layer and the ink layer are in contact is essential.

[0296] As an example of the image recorded material of the present invention, a preferred embodiment is an image recorded material using at least the treatment liquid and ink of the present invention, wherein a first layer containing a thermosetting resin, a second layer containing the above-mentioned treatment liquid, a third layer containing the above-mentioned ink, and a fourth layer containing a thermosetting resin are sequentially stacked on a metal substrate.

[0297] Specific examples of the image recorded material preferably include packaging materials for canned foods, retort foods, beverages, and the like.

[0298] Figure 3 2 is a cross-sectional view of a canned food packaging material as an example of the image recorded material of the present invention.

[0299] A thermosetting resin layer (primer layer) 52 is formed by roller coating a tinplate substrate 51 with a thermosetting resin (e.g., TW-1407 series, manufactured by T&KTOKA). An image is then formed thereon with a treatment liquid layer 53 and an ink layer 54. Subsequently, a thermosetting resin layer (top coat layer) 55 is formed by roller coating a thermosetting resin (e.g., AX-10 series, manufactured by T&KTOKA). This is then heat-cured and dried to obtain a canned food packaging material 50.

[0300] Example

[0301] The present invention is described in detail below with reference to the following examples, but the present invention is not limited thereto. In the following examples, unless otherwise specified, the operations were performed at room temperature (25°C). Furthermore, unless otherwise specified, "%" and "parts" refer to "mass %" and "mass parts," respectively.

[0302] [Preparation of Treatment Liquid A1]

[0303] To 3% by mass of magnesium acetate tetrahydrate as a polyvalent metal salt, 14% by mass of dipropylene glycol, 14% by mass of propylene glycol, 8% by mass of glycerin, 1% by mass of polyether-modified silicone (BYK3450), 0.1% by mass of a mildew preventative (Proxel GXL (S)) and ion-exchanged water (the remainder; the total amount is 100% by mass) were added while stirring, and the resulting mixed solution was filtered using a 1 μm filter to obtain a treated liquid A1.

[0304] [Preparation of Treatment Liquids A2 to A15]

[0305] In the preparation of the treatment liquid A1, treatment liquids A2 to A15 were prepared in the same manner except that the types and addition amounts of the polyvalent metal salt, polyether-modified silicone, and solvent or the amount of water were changed as shown in Table I below.

[0306] In addition, the materials in Table 1 are as follows.

[0307] <Polyether-modified silicone>

[0308] BYK3450: manufactured by BYKChemie

[0309] "TEGOWET245": Made by Evonik

[0310] "TEGOWET250": Made by Evonik

[0311] "TEGOWET260": Made by Evonik

[0312] "TEGOWET270": Made by Evonik

[0313] "TEGOWET280": Made by Evonik

[0314] BYK348: manufactured by BYKChemie

[0315] Solvents

[0316] "DPG": dipropylene glycol

[0317] "PG": Propylene glycol

[0318] "Gly": glycerol

[0319] "1,2-HDO": 1,2-hexanediol

[0320] <Fungicide>

[0321] "Proxel GXL(S)": 1,2-Benzisothiazoline-3-one

[0322] [Physical properties]

[0323] The cloud point and dynamic surface tension of each of the obtained treatment liquids were measured by the following methods.

[0324] Cloud point

[0325] 2 mL of the treatment solution was placed in a glass container and heated, and the temperature at which the treatment solution began to become cloudy was defined as the cloud point.

[0326] Dynamic surface tension

[0327] As described above, the dynamic surface tension of the treatment liquid at 25° C. when the surface life was 15 ms was measured by the maximum bubble pressure method. The dynamic surface tensiometer used in the measurement was a bubble pressure dynamic surface tensiometer (manufactured by KRUSS, Model “BP100”).

[0328] [evaluate]

[0329] Storage stability

[0330] After heating treatment liquids A1 to A15 at 60°C for 2 weeks, the dynamic surface tension of the treatment liquids at 25°C at a surface life of 15 ms was measured by the maximum bubble pressure method as described above. The dynamic surface tensiometer used in the measurement was a bubble pressure dynamic surface tensiometer (manufactured by KRUSS, Model "BP100").

[0331] Then, the difference between the dynamic surface tension of the treatment liquid before heating and the dynamic surface tension of the treatment liquid after heating was calculated, and the storage stability was evaluated according to the following criteria.

[0332] (Benchmark)

[0333] ○: The difference between the dynamic surface tension of the treatment liquid before heating and the dynamic surface tension of the treatment liquid after heating is 2 mN / m or more

[0334] △: The difference between the dynamic surface tension of the treatment liquid before heating and the dynamic surface tension of the treatment liquid after heating is 1 mN / m or more and less than 2 mN / m

[0335] ×: The difference between the dynamic surface tension of the treatment liquid before heating and the dynamic surface tension of the treatment liquid after heating is less than 1 mN / m

[0336] [Table 1]

[0337]

[0338] As shown in the above results, it was confirmed that the treatment liquid having a cloud point of 40° C. or higher had excellent storage stability, and particularly the treatment liquid having a cloud point of 50° C. or higher had excellent storage stability.

[0339] [Resin fine particle dispersions B1 to B7]

[0340] The cohesiveness and glass transition temperature (Tg) of each of the commercially available resin fine particle dispersions B1 to B7 listed in Table II below were measured, and the measurement results are shown in Table II below.

[0341] <Cohesion>

[0342] The cohesion was measured by the following method.

[0343] First, in order to prepare a mixed solution containing 5% by mass of resin fine particles and 0.15% by mass of calcium acetate monohydrate, a calcium acetate aqueous solution was prepared by dissolving calcium acetate monohydrate in ion-exchanged water to obtain 0.30% by mass, and a diluted solution of a resin fine particle dispersion prepared in ion-exchanged water to obtain 10% by mass of the solid content using each of the resin fine particle dispersions B1 to B7 shown in Table II.

[0344] Next, 5 g of the calcium acetate aqueous solution was added to 5 g of the diluted resin fine particle dispersion while stirring to prepare 10 g of each mixed solution having a solid content of 5% by mass and 0.15% by mass of calcium acetate monohydrate.

[0345] Then, 10 g of each mixed solution was centrifuged using a centrifuge CF16RX manufactured by Hitachi Koki Co., Ltd. at a centrifugal acceleration of 200 G for 10 minutes, and approximately 2 g of the supernatant was collected from each of the separated solutions.

[0346] Next, each supernatant was heated at 150° C. for 30 minutes to remove water, and the mass of the solid matter remaining after heating was measured. The mass of the obtained solid content was substituted into the following calculation formula to calculate the cohesiveness.

[0347] Formula: Cohesion = 1 - (mass of solid content (g) / (mass of supernatant (g) x 5%))

[0348] Glass transition temperature

[0349] The glass transition temperature (Tg) of the resin fine particles is determined by reading the glass transition temperature Tg from an endothermic peak when the temperature is increased at a rate of 10°C / min in the temperature range of -30 to 200°C using a DSC (differential scanning calorimeter).

[0350] [Table 2]

[0351]

[0352] [Preparation of cyan ink]

[0353] <Preparation of cyan pigment dispersion>

[0354] A mixed solution prepared by adding 6% by mass of a pigment dispersant (an acrylic dispersant having a carboxyl group neutralized with dimethylaminoethanol ("Joncryl 819" manufactured by BASF, acid value 75 mgKOH / g, solid content 20% by mass), 22% by mass of propylene glycol, 0.1% by mass of a mildew preventer Proxel GXL (S), and ion-exchanged water (the balance; the total amount is 100% by mass) to 20% by mass of a pigment (CI Pigment Blue 15:3) was pre-mixed.

[0355] Then, dispersion was performed using a bead mill filled with 0.3 mm zirconia beads at a volume ratio of 50%, thereby preparing a cyan pigment dispersion having a pigment content of 20% by mass.

[0356] The average particle size of the pigment particles contained in the cyan pigment dispersion was 120 nm. The average particle size of the pigment particles was measured using a "Zetasizer Nano S90" manufactured by Malvern.

[0357] <Preparation of Cyan Ink C1>

[0358] To the 15% by mass (3% by mass solids) cyan pigment dispersion described above, the commercially available resin fine particle dispersion B1 (the amount added was adjusted to provide 5% by mass of the resin fine particles (solids content) in the ink), 22% by mass of propylene glycol, 5% by mass of glycerin, 0.20% by mass of surfactant KF351A (Shin-Etsu Silicone Co., Ltd.), 1% by mass of surfactant E1010 (Nissin Chemical Industry Co., Ltd.), 0.10% by mass of antifungal agent Proxel GXL(S), and ion-exchanged water (the remainder; the total amount is 100% by mass) were added with stirring. The resulting mixture was filtered through a 1 μm filter to obtain cyan ink C1. There was no substantial change in composition before and after filtration.

[0359] <Preparation of Cyan Inks C2 to C8>

[0360] In the preparation of the cyan ink C1, cyan inks C2 to C8 were prepared in the same manner except that the type and content of the commercially available resin fine particle dispersion were changed as shown in Table III below.

[0361] [Preparation of magenta ink]

[0362] <Preparation of Magenta Pigment Dispersion>

[0363] A mixed solution of 8% by mass of a pigment dispersant (an acrylic dispersant having a carboxyl group neutralized with dimethylaminoethanol ("Joncryl 819" manufactured by BASF, acid value 75 mgKOH / g, solid content 20% by mass), 22% by mass of propylene glycol, 0.1% of a mildewproofing agent Proxel GXL(S), and ion-exchanged water (the balance; the total amount is 100% by mass)) was added to 20% by mass of pigments (Pigment Red 122, Pigment Violet 19) and prepolymerized.

[0364] Then, dispersion was performed using a bead mill filled with 0.3 mm zirconia beads at a volume ratio of 50%, thereby preparing a magenta pigment dispersion having a pigment content of 20% by mass.

[0365] The average particle size of the pigment particles contained in the magenta pigment dispersion was 140 nm. The average particle size of the pigment particles was measured using a "Zetasizer Nano S90" manufactured by Malvern.

[0366] <Preparation of Magenta Ink D1>

[0367] To the 20% by mass (4% by mass solids) magenta pigment dispersion described above, the commercially available resin fine particle dispersion B1 (the amount added was adjusted to provide 5% by mass of the resin fine particles (solids content) in the ink), 21% by mass of propylene glycol, 5% by mass of glycerin, 0.20% by mass of surfactant KF351A (Shin-Etsu Silicone Co., Ltd.), 1% by mass of surfactant E1010 (Nissin Chemical Industry Co., Ltd.), 0.10% by mass of antifungal agent Proxel GXL(S), and ion-exchanged water (the remainder; the total amount is 100% by mass) were added while stirring. The resulting mixture was filtered through a 1 μm filter to obtain magenta ink D1. There was no substantial change in composition before and after filtration.

[0368] <Preparation of Magenta Inks D2 to D8>

[0369] In the preparation of magenta ink D1, magenta inks D2 to D8 were prepared in the same manner except that the type and content of the commercially available resin fine particle dispersion were changed as shown in Table III.

[0370] [Physical properties]

[0371] The dynamic surface tension of each of the obtained inks was measured by the following method.

[0372] Dynamic surface tension

[0373] As described above, the dynamic surface tension of the ink at a surface life of 15 ms at 25° C. was measured by the maximum bubble pressure method. The dynamic surface tensiometer used in the measurement was a bubble pressure dynamic surface tensiometer (manufactured by KRUSS, Model “BP100”).

[0374] [Table 3]

[0375]

[0376] [Preparation of tinplate original]

[0377] A white primer layer (KC White 2, TOYOCHEM) was applied to a tinplate original (SPTE, thickness 300 μm, Standard Text Piece) using a wireless bar coater (OSP-10, OSG System Products).

[0378] [Printing test 1]

[0379] The treatment liquids A1 to A10, inks C1 to C8 and D1 to D8 prepared above were used in the combinations shown in Table IV below to perform printing as follows.

[0380] like Figure 4 An independently driven inkjet head (360 dpi, discharge volume: 15 pL) manufactured by Konica Minolta is set up in this manner, the head unit U is moved in the scanning direction X, and the recording medium (substrate) M is moved in the transport direction Y (not shown), thereby applying a processing liquid and ink to the surface (image forming surface) of the recording medium M, and forming an image as shown below.

[0381] As recording media (non-absorbing substrates), a tinplate original plate (SPTE, 300 μm thick, manufactured by Standard Test Piece Co., Ltd.) coated with the above-mentioned white primer layer and a PET film (FE2001, 50 μm thick, manufactured by Futamura Chemical Co., Ltd.) were prepared.

[0382] From the near side of the scanning direction X, the treatment liquid ( Figure 4 In the symbol Pr), magenta ink ( Figure 4 In the symbol I M ) and cyan ink ( Figure 4 Chinese symbol I C ) are placed into the header module respectively.

[0383] The head unit's travel speed was set at 500 mm / sec. A 720 dpi x 720 dpi image was divided into two in the scanning direction X and the transport direction Y, respectively, to obtain four images (180 dpi x 180 dpi). This image was formed by printing four times on one printing area. When the recording medium was passed through four times, the printing treatment liquid on the recording medium had a printing rate of 28%, i.e., the amount of treatment liquid applied was 3.4 g / m². 2 The printing rate of cyan ink and magenta ink is 100%, that is, the amount of ink applied to the two colors is 24g / m 2 (cyan ink application amount 12g / m 2 , magenta ink 12g / m 2 In the tinplate original plate, a full-surface printed image is printed on the surface coated with the above-mentioned white primer layer.

[0384] Here, inkjet printing was performed using the process liquid with the drying rate shown in Table IV, applying ink to the area where the process liquid had been applied. Specifically, a printing test was conducted in an environment of 25°C and 50% RH, with the time from application of the process liquid to ink application set to 0.2 seconds. The drying rate of the process liquid was measured 0.2 seconds after application of the process liquid in this 25°C and 50% RH environment, and the result was a drying rate of less than 1%. The drying rate of the process liquid was calculated by measuring the change in mass of the process liquid.

[0385] After printing, the printed image was placed in a dryer set to the drying temperature (tinplate, PET) listed in Table IV and dried for 10 minutes to obtain an image recorded material.

[0386] In addition, in Table IV, "≤1" means "1% or less".

[0387] [evaluate]

[0388] <Tinplate Adhesion>

[0389] Among the image records obtained above, the image records printed on the tinplate original plate were subjected to a drop resistance tester (083, Algood Co., Ltd.). A 1000 g weight was dropped from a height of 100 cm onto the back side of the printed surface to deform the tinplate original plate. The image adhesion of the image printed surface in the deformed portion was evaluated according to the following criteria.

[0390] (Benchmark)

[0391] ◎: After the drop test, the printed surface remained unchanged, and the image did not peel off even when rubbed with a fingernail.

[0392] ○: After the drop test, the printed surface remained unchanged, but a portion of the image peeled off when rubbed with a fingernail.

[0393] △: After the drop test, the printed surface remained unchanged, but the entire image peeled off when rubbed with a fingernail.

[0394] ×: Peeling of the image was observed on the printed surface after the drop test.

[0395] PET Adhesion

[0396] In the image recorded article obtained above, an adhesive tape was adhered to the printed surface of the image recorded article printed on PET and then peeled off, and the image adhesion was evaluated according to the following criteria.

[0397] (Benchmark)

[0398] ◎: The image does not peel off even if the tape is peeled off.

[0399] ○: The image peeled off along with the tape over approximately one-quarter of the adhesive surface of the tape.

[0400] Δ: The image peels off along with the tape on about half of the adhesive surface of the tape.

[0401] ×: The image and the tape were completely peeled off on the adhesive surface of the tape.

[0402] [Table 4]

[0403]

[0404] As shown in the above results, in Examples 1 to 19, it was confirmed that excellent adhesion to a non-absorbent substrate and image abrasion resistance were obtained compared to Comparative Examples 1 to 8.

[0405] [Printing Test 2]

[0406] Two independently driven heads of a Konica Minolta piezoelectric inkjet head (360 dpi, discharge volume 15 pL) were configured with nozzles different from each other to produce a 720 dpi × 720 dpi head module. The nozzle rows were arranged orthogonally to the conveying direction. Figure 1 The printer shown is a single-path type.

[0407] The inkjet head 11 of the head assembly provided in the treatment liquid applying section 10 was filled with the treatment liquid A1 or A2 obtained above, and the inkjet head 21 of the head assembly provided in the ink applying section 20 was filled with the inks C1 and D1 obtained above. With this configuration, a single-path inkjet recording apparatus capable of recording the treatment liquids and inks listed in Table V was constructed.

[0408] Using the above-mentioned inkjet recording apparatus, a full-surface printed image of 720 dpi x 720 dpi was recorded under the recording conditions described in Table V, similar to those in Printing Test 1. Evaluation was performed using the same indicators as in Printing Test 1. It should be noted that as substrate F, a tinplate original plate (SPTE, 300 μm thick, manufactured by Standard Test Piece Co., Ltd.) coated with the above-mentioned white primer layer and a PET film (FE2001, 50 μm thick, manufactured by Futamura Chemical Co., Ltd.) were prepared. The transport speed during recording was set to 300 mm / second.

[0409] Here, inkjet printing was performed using the conditions listed in Table V for the drying rate of the treatment liquid to be applied to the area where the treatment liquid had been applied. Specifically, a printing test was conducted in an environment of 25°C and 50% RH. The treatment liquid layer C was dried for 5 seconds at 25°C, 50°C, or 60°C in the first drying section 14 to apply ink. After drying the treatment liquid layer C for 5 seconds at 25°C, 50°C, or 60°C in the first drying section 14, the drying rate of the treatment liquid was measured, resulting in drying rates of 10%, 20%, and 50%, respectively. The drying rate of the treatment liquid was calculated by measuring the change in mass of the treatment liquid.

[0410] After printing, the image recorded material was dried for 10 minutes in the first drying section 23 set to the drying temperature shown in Table V. Here, the temperature of the region to which ink was applied was equal to the drying temperature.

[0411] [Table 5]

[0412]

[0413] As shown in the above results, by setting the drying rate to 30% or less, preferably 10% or less, excellent adhesion to a non-absorbent substrate can be obtained.

[0414] Industrial applicability

[0415] The present invention can achieve excellent adhesion to non-absorbent substrates and image abrasion resistance, and can be used in an ink set and an inkjet recording method that are excellent in storage stability.

[0416] Explanation of symbols

[0417] 1: Recording device

[0418] 10: Treatment liquid applying part

[0419] 11: Inkjet head

[0420] 12: Treatment fluid droplets

[0421] 14: First drying section

[0422] 20: Ink application section

[0423] 21: Inkjet head

[0424] 22: Ink droplets

[0425] 23: Second drying section

[0426] 30: Delivery roller

[0427] 40: Winding roller

[0428] C: Treatment liquid layer

[0429] F: Base material

[0430] P: Image record

[0431] R: Ink layer

[0432] 50: Packaging materials for canned food

[0433] 51: Tinplate substrate

[0434] 52: Thermosetting resin layer (primer layer)

[0435] 53: Treatment liquid layer

[0436] 54: Ink layer

[0437] 55: Thermosetting resin layer (top coat)

[0438] U: Head unit

[0439] X: Scan direction

[0440] M: Recording medium (base material)

Claims

1. An ink set comprising a treatment liquid and ink, The treatment liquid contains at least a multivalent metal salt, polyether-modified silicone, a water-soluble solvent and water. The ink contains a colorant and resin particles having a glass transition temperature within a range of 40 to 90° C. The cloud point of the treatment liquid is within the range of 40 to 90° C., and the dynamic surface tension of the treatment liquid at 25° C. when the surface life is 15 ms is within the range of 25 to 35 mN / m. The ink contains the resin fine particles having an agglomeration property of 0.2 or less with a 0.15% by mass aqueous solution of calcium acetate monohydrate in an amount of 3 to 15% by mass. The treatment liquid contains the polyvalent metal salt in a range of 0.5 to 20 mass %, The treatment liquid contains the polyether-modified silicone in a range of 0.1 to 2 mass %, The resin in the resin fine particles is any one of acrylic resin, polyurethane resin, polyester resin, or a composite resin of polyurethane resin and acrylic resin.

2. The ink set according to claim 1, wherein: The dynamic surface tension of the ink at 25° C. when the surface life is 15 ms is higher than the dynamic surface tension of the treatment liquid at 25° C. when the surface life is 15 ms by 5 mN / m or more.

3. The ink set according to claim 1 or 2, wherein: The treatment liquid contains an SP value of 24 (J / cm 3 ) 1 / 2 The above water-soluble solvent.

4. An inkjet recording method for recording an image using the ink set according to any one of claims 1 to 3, comprising the following steps: a step of applying the treatment liquid to the recording area of ​​the non-absorbent substrate, a step of applying the ink to the area to which the treatment liquid has been applied by an inkjet recording method, and A step of heating the region to which the ink is applied at a heating temperature that is higher than the cloud point and higher than the glass transition temperature.

5. The inkjet recording method according to claim 4, wherein The method includes the step of applying the ink to the region to which the treatment liquid has been applied by an inkjet recording method in a state where the drying rate of the treatment liquid is 30% or less.

6. The inkjet recording method according to claim 4 or 5, wherein The amount of the resin fine particles applied is set to be 80 times or less of the amount of the polyether-modified silicone applied per unit area.

Images