Ink set and inkjet recording method

Abstract

This ink set includes a treatment liquid and ink. The treatment liquid contains at least a polyvalent metal salt, polyether-modified silicone, a water-soluble solvent, and water. The ink contains a coloring agent and fine resin particles having a glass transition temperature in the range of 40–90°C. The cloud point of the treatment liquid is in the range of 40–90°C, and the dynamic surface tension of the treatment liquid at 25°C at a surface life of 15 ms is in the range of 25–35 mN / m.

Description

Technical Field

[0001] The present invention relates to an ink set and an inkjet recording method, and particularly to an ink set and the like that exhibit excellent adhesion to a non-absorbent substrate, excellent image rub resistance, and excellent storage stability.

Background Art

[0002] Since the inkjet recording method can produce an image simply and inexpensively, it has been applied to various printing fields including photography, various printing, marking, and special printing such as color filters. In particular, since the inkjet recording method enables digital printing without using a plate, it is particularly suitable for applications where various images are formed little by little.

[0003] In such an inkjet recording method, a treatment liquid (also referred to as a "pretreatment liquid" or a "primer") containing a flocculant such as an organic acid or a polyvalent metal salt is applied to a substrate in advance, and the pigment contained in the ink is flocculated and pinned by the organic acid or the polyvalent metal salt, whereby a technique for obtaining a high-quality image recording material is known. On the other hand, there has been a problem that the rub resistance of the obtained image recording material is reduced by containing a flocculant in the treatment liquid. For this reason, a technique for obtaining an image recording material excellent in image quality and rub resistance by reducing the amount of the treatment liquid adhered compared to the amount of the ink adhered has been disclosed (see, for example, Patent Document 1).

[0004] However, when an ink is applied to a non-absorbent substrate to record an image, good image quality cannot be obtained only by the technique described in Patent Document 1, and the adhesion to the non-absorbent substrate is also insufficient.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The present invention has been made in view of the above problems and situations, and the problem to be solved is to provide an ink set that exhibits excellent adhesion to a non-absorbent substrate and excellent image rub resistance, and also has excellent storage stability. Another object is to provide an inkjet recording method using the ink set.

Means for Solving the Problems

[0007] In order to solve the above problems, the inventor of the present invention has found that by setting the glass transition temperature of the resin fine particles contained in the ink within a specific range and defining the cloud point and surface tension of the treatment liquid in the process of studying the cause of the above problems, it is possible to provide an ink set and the like that exhibit excellent adhesion to a non-absorbent substrate and excellent image rub resistance, and also have excellent storage stability, thus arriving at the present invention. That is, the above problems according to the present invention are solved by the following means.

[0008] 1. An ink set containing 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, The treatment liquid contains the polyvalent metal salt in the range of 0.5 to 20% by mass and contains the polyether-modified silicone in the range of 0.1 to 2% by mass. the ink contains a colorant and resin fine particles having a glass transition temperature in the range of 40 to 90°C, The ink contains the resin fine particles having an aggregability of 0.2 or less with a 0.15% by mass aqueous solution of calcium acetate monohydrate in the range of 3 to 15% by mass. the cloud point of the treatment liquid is in the 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 in the range of 25 to 35 mN / m.

[0010] 2 . The dynamic surface tension of the ink at a surface life of 15 ms at 25°C is 5 mN / m or more higher than the dynamic surface tension of the treatment liquid at a surface life of 15 ms at 25°C. in item The ink set according to item 1.

[0011] 3 . The treatment liquid has an SP value of 24 (J / cm 3 ) 1 / 2 or more of the water-soluble solvent in the range of 5 to 40% by mass according to claim 1 or The in item 2 ink set according to the description.

[0014] 4 . An inkjet recording method using the ink set according to any one of claims 1 to 3 to record an image, comprising: a step of applying the treatment liquid to a recording area of a non-absorbent substrate; a step of applying the ink to the area where the treatment liquid has been applied by an inkjet recording method; a step of heating the area where the ink has been applied at a heating temperature equal to or higher than the cloud point and equal to or higher than the glass transition temperature.

[0015] 5 . The inkjet recording method according to claim 4 including a step of applying the ink to the area where the treatment liquid has been applied in a state where the drying rate of the treatment liquid is 30% or less by an inkjet recording method.

[0016] 6 . The inkjet recording method according to claim 4 or claim 5 wherein the amount of the resin fine particles with respect to the amount of the polyether-modified silicone is 80 times or less per unit area.

Advantages of the Invention

[0017] By the above means of the present invention, an ink set excellent in adhesion to a non-absorbent substrate and image rub resistance, and excellent in storage stability can be provided. Further, an inkjet recording method using the ink set can be provided. Although the mechanism of expression or action of the effects of the present invention is not clear, it is presumed as follows. Since the ink contains a colorant and resin fine particles having a glass transition temperature in the range of 40 to 90°C, in the ink drying process, the resin fine particles soften and form a uniform film, thereby obtaining excellent image rub resistance. In addition, since 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 40°C or higher, sufficient storage stability of the treatment liquid is obtained. Also, since the cloud point is 90°C or lower, in the ink drying process, the polyether-modified silicone contained in the treatment liquid acts as a plasticizer for the resin fine particles contained in the ink, and excellent adhesion to the substrate is obtained. Furthermore, since the dynamic surface tension of the treatment liquid at a surface life of 15 ms at 25°C is in the range of 25 to 35 mN / m, the treatment liquid easily spreads over the substrate (for example, a non-absorbent substrate), and the adhesion of the ink to the non-absorbent substrate becomes good. From the above, it is possible to obtain an ink set having good image rub resistance and adhesion to a non-absorbent substrate, and excellent storage stability of the treatment liquid.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0019] The ink set of the present invention is an ink set containing a treatment liquid and 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 fine particles having a glass transition temperature in the range of 40 to 90 °C, and the cloud point of the treatment liquid is in the range of 40 to 90 °C, and the dynamic surface tension at a surface life of 15 ms of the treatment liquid at 25 °C is in the range of 25 to 35 mN / m. This feature is a technical feature common to or corresponding to each of the following embodiments.

[0020] As an embodiment of the present invention, it is preferable that the ink contains the resin fine particles having an aggregability of 0.2 or less with a 0.15 mass% aqueous solution of calcium acetate monohydrate in the range of 3 to 15 mass%, because excellent adhesion to a non-absorbent substrate can be obtained by using resin fine particles with low aggregability.

[0021] Also, it is preferable that the dynamic surface tension at a surface life of 15 ms of the ink at 25 °C is 5 mN / m or more higher than the dynamic surface tension at a surface life of 15 ms of the treatment liquid at 25 °C. By using an ink having a higher dynamic surface tension than the treatment liquid, bleeding of the ink can be prevented.

[0022] Also, it is preferable that the treatment liquid contains the water-soluble solvent having an SP value of 24 (J / cm 3 ) 1 / 2 in the range of 5 to 40 mass%, because precipitation of the polyvalent metal salt can be suppressed and excellent ejection stability can be obtained.

[0023] Also, it is preferable that the treatment liquid contains the polyvalent metal salt in the range of 0.5 to 20 mass%, because bleeding of the image can be prevented. Also, it is preferable to set the polyvalent metal salt to 0.5 mass% or more in terms of enhancing the adhesion to a non-absorbent substrate. On the other hand, it is preferable to set the polyvalent metal salt to 20 mass% or less in terms of enhancing the impact resistance of the image.

[0024] Furthermore, it is preferable that the treatment liquid contains polyether-modified silicone in the range of 0.1 to 2% by mass, because excellent adhesion to the non-absorbent base material can be obtained, and it is also preferable from the viewpoint of the solubility of the polyether-modified silicone.

[0025] The inkjet recording method of the present invention is an inkjet recording method for recording an image using the above-described ink set of the present invention, comprising a step of applying the treatment liquid to a recording area of a non-absorbent base material, a step of applying the ink to the area where the treatment liquid has been applied by an inkjet recording method, and a step of heating the area where the ink has been applied at a heating temperature equal to or higher than the cloud point and equal to or higher than the glass transition temperature. Thereby, an inkjet recording method with good image abrasion resistance and adhesion to the base material can be provided.

[0026] Moreover, it is preferable to include a step of applying the ink by an inkjet recording method to the area where the treatment liquid has been applied in a state where the drying rate of the treatment liquid is 30% or less, because adhesion to the non-absorbent base material can be obtained.

[0027] Furthermore, it is preferable that the amount of the resin fine particles per unit area with respect to the amount of the polyether-modified silicone is 80 times or less, because excellent adhesion to the non-absorbent base material can be obtained.

[0028] Hereinafter, the present invention, its components, and the forms and embodiments for carrying out the present invention will be described. In the present application, "~" is used in the sense of including the numerical values described before and after it as the lower limit value and the upper limit value.

[0029] [Outline of the Ink Set of the Present Invention] The ink set of the present invention is an ink set containing 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 fine particles having a glass transition temperature in the range of 40 to 90°C. The cloud point of the treatment liquid is in the 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 in the range of 25 to 35 mN / m.

[0030] As used in the present invention, the "treatment liquid" and "ink" refer to a "treatment liquid (also referred to as a "pretreatment liquid" or a "primer") and an "ink (also referred to as an "aqueous ink" or a "water-based ink")" that use at least "water" as a solvent. In both cases, 60% by mass or more of the solvent used is "water".

[0031] <Cloud point of the treatment liquid> The treatment liquid contained in the ink set of the present invention has a cloud point in the range of 40 to 90°C. Preferably, it is in the range of 50 to 90°C. In the present invention, the "cloud point" of the treatment liquid refers to the temperature at which the treatment liquid starts to become turbid when 2 mL of the treatment liquid is placed in a glass container and heated.

[0032] In order to make the cloud point of the treatment liquid within the above range, for example, it can be controlled by the types and contents of the water-soluble solvent, polyvalent metal salt, and surfactant contained in the treatment liquid. Specifically, as the water-soluble solvent, it is preferable to use a water-soluble solvent having an SP value of 24 (J / cm 3 ) 1 / 2 or more as described later. Further, as the polyvalent metal salt, it is preferable to use, for example, magnesium acetate or calcium acetate described later, and as the surfactant, a polyether-modified silicone is used. Furthermore, as the content in the treatment liquid, the water-soluble solvent is preferably in the range of 5 to 40% by mass, the polyvalent metal salt is preferably in the range of 0.5 to 20% by mass, and the surfactant is preferably in the range of 0.1 to 2% by mass.

[0033] <Dynamic surface tension of the treatment liquid> At 25°C, the dynamic surface tension of the treatment liquid at a surface lifetime of 15 ms is within the range of 25 to 35 mN / m.

[0034] In the present invention, the "dynamic surface tension" refers to the surface tension immediately after the liquid surface (gas-liquid interface) is formed and when the liquid surface is in a non-equilibrium state, and is a value measured at 25°C by the maximum bubble pressure method. Also, the "surface lifetime" refers to the elapsed time since the liquid surface was formed, that is, the lifetime of the bubbles generated in the maximum bubble pressure method, also referred to as the bubble lifetime, and refers to the time from when a new interface is generated inside the probe tip of the dynamic surface tensiometer until the maximum bubble pressure is reached. The dynamic surface tension of the treatment liquid can be measured by using a dynamic surface tensiometer. Examples of the dynamic surface tensiometer include a bubble pressure dynamic surface tensiometer (manufactured by KRUSS, model "BP100"), etc. Unless otherwise specified, the dynamic surface tension in this specification is the dynamic surface tension measured at 25°C and a surface lifetime of 15 ms using the maximum bubble pressure method.

[0035] In order to make the dynamic surface tension of the treatment liquid within the above range, controlling the type and content of the surfactant, the type and content of the water-soluble solvent, the type and content of the flocculant, etc. can be mentioned. In particular, it is preferable that the polyether-modified silicone of the surfactant contained in the treatment liquid is within the range of 0.1 to 2% by mass. Among the polyether-modified silicones, it is preferable to contain trisiloxane, whereby the dynamic surface tension of the treatment liquid can be reduced and made within the above range. Also, as the water-soluble solvent, a water-soluble solvent having an SP value of 24 (J / cm 3 ) 1 / 2 or more and a boiling point in the range of 150°C to 250°C is used, and its content is preferably within the range of 5 to 40% by mass.

[0036] <Dynamic surface tension of the ink> At 25°C, it is preferable that the dynamic surface tension of the ink at a surface life of 15 ms is 5 mN / m or more higher than the dynamic surface tension of the treatment liquid at a surface life of 15 ms at 25°C. As a method for measuring the dynamic surface tension of the ink, the same method as that of the dynamic surface tension of the treatment liquid described above can be adopted. Also, at 25°C, the dynamic surface tension of the ink at a surface life of 15 ms is preferably in the range of 35 to 45 mN / m.

[0037] In order to make the dynamic surface tension of the ink within the above range, controlling the type and content of the water-soluble solvent, the type and content of the surfactant, the type and content of the pigment dispersant, the type and content of the resin fine particles, etc. can be mentioned. Specifically, as the water-soluble solvent contained in the ink, a polyhydric alcohol is preferably used, and its content is preferably in the range of 10 to 60% by mass. Also, as the surfactant, a nonionic surfactant or an anionic surfactant is preferably used, and its content is preferably in the range of 0.1 to 2% by mass. Also, as the pigment dispersant, various low molecular weight dispersants, nonionic polymer dispersants, anionic polymer dispersants can be used, or a resin-coated pigment dispersion can be appropriately used. Further, as the type of the resin fine particles, resin fine particles such as polyester resin, acrylic resin, styrene acrylic resin, urethane resin are preferably used, and its content is preferably in the range of 3 to 15% by mass.

[0038] [Treatment liquid] When recording an image on a substrate by an inkjet printing method, the treatment liquid according to the present invention can have a function of accelerating the image formation of the ink, improving the physical properties of the treatment liquid layer and the ink layer, or improving the image quality by aggregating or thickening the ink.

[0039] The treatment liquid according to the present invention contains at least a polyvalent metal salt, a polyether-modified silicone, a water-soluble solvent, and water.

[0040] [Polyvalent metal salt] The treatment liquid according to the present invention contains, as a material that causes aggregates to form when it comes into contact with ink, that is, a flocculant which is a polyvalent metal salt. By doing so, the interaction with the ink is increased, and the ink dots can be fixed more firmly.

[0041] The polyvalent metal salt can aggregate an anionic component (usually a coloring material, pigment, etc.) in the ink described later by salting out.

[0042] 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. For example, Ca 2+ , Cu 2+ , Ni 2+ , Mg 2+ , Zn 2+ , Ba 2+ and other divalent metal ions, Al 3+ , Fe 3+ , Cr 3+ , Y 3+ and other trivalent metal ions, Zr 4+ and other tetravalent metal ions, etc. can be mentioned. The type of salt constituting the polyvalent metal salt is not particularly limited. 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, for example, calcium chloride, magnesium chloride, calcium nitrate, magnesium nitrate, magnesium acetate, calcium acetate, magnesium lactate, calcium salts or magnesium salts of carboxylic acids such as calcium pantothenate.

[0043] <Organic acid> The treatment liquid according to the present invention may further contain an organic acid as a flocculant in addition to the polyvalent metal salt. The organic acid can aggregate the anionic components in the above ink due to pH fluctuations. From the viewpoint of not weakening the flocculation power of the polyvalent metal salt, a monovalent carboxylic acid is preferred as the organic acid.

[0044] The organic acid can aggregate pigments that may be contained in the ink described later. Examples of the organic acid include formic acid, acetic acid, propionic acid, benzoic acid and the like.

[0045] It is preferable to use an organic acid that is not completely neutralized by a base. Neutralization by a base means that the acidic group of these acids and another positively charged element or compound (for example, an inorganic compound such as a metal) are ionically bonded. Further, not being completely neutralized means that among the acidic groups of the organic acid, there are acidic groups that do not form the above ionic bond. In addition, by using an organic acid, it is easy to maintain the storage stability of the treatment liquid, and blocking is less likely to occur after the treatment liquid is applied and dried. Preferred organic acids from the above viewpoints include formic acid, acetic acid, propionic acid, benzoic acid and the like.

[0046] <Inorganic acid> In addition to the polyvalent metal salt, an inorganic acid may be added as a flocculant to the treatment liquid according to the present invention. The inorganic acid can flocculate an anionic component in the ink due to pH fluctuation.

[0047] The inorganic acid can flocculate a pigment that may be contained in the ink described later. Examples of the inorganic acid include hydrochloric acid, nitric acid, sulfuric acid, sulfamic acid and the like.

[0048] The content of the polyvalent metal salt is preferably in the range of 0.5 to 20% by mass, more preferably in the range of 1 to 10% by mass, based on 100% by mass of the total mass of the treatment liquid. Thereby, an anionic component in the ink can be effectively flocculated, which is preferable from the viewpoints of image quality and image rub resistance. When an organic acid is contained, the content of the organic acid is preferably in the range of 0.1 to 10% by mass, more preferably in the range of 1 to 3% by mass, based on 100% by mass of the total mass of the treatment liquid. When an inorganic acid is contained, the content of the inorganic acid is preferably in the range of 0.1 to 10% by mass, more preferably in the range of 1 to 3% by mass, based on 100% by mass of the total mass of the treatment liquid.

[0049] The content of the polyvalent metal salt or organic acid in the aqueous solution can be measured by a known method. For example, in the case of the polyvalent metal salt, the content can be measured by ICP emission spectrometry, and in the case of the organic acid, the content can be measured by high performance liquid chromatography (HPLC).

[0050] When using an organic acid, the addition amount of the organic acid is preferably an amount that adjusts the pH of the treatment liquid to be equal to or less than the neutralization equivalent of the anion component contained in the ink. Further, when the anion component is a compound having a carboxy group, from the viewpoint of making image bleeding less likely to occur, the first dissociation constant of the organic acid is preferably 3.5 or less.

[0051] <Polyether-modified silicone> The polyether-modified silicone contained in the treatment liquid according to the present invention functions as a surfactant, and can improve the ejection stability from the nozzle of the treatment liquid and control the spread of the droplets (expansion of the dot diameter) landing on the recording medium. Examples of the polyether-modified silicone include siloxanes having an alkylene oxide group in the side chain and / or both ends of the polydimethylsiloxane chain. Specifically, BYK-331, BYK-333, BYK-345, BYK-3450, BYK-3451, BYK-3455, BYK-346, BYK-347, BYK-348, BYK-349 manufactured by BYK Chemie GmbH; TEGOWet KL245, TEGOWet 250, TEGOWet 260, TEGOWet 270, TEGOWet 280 manufactured by Evonik Industries AG; 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 manufactured by Shin-Etsu Chemical Co., Ltd. etc. may be mentioned.

[0052] As the polyether-modified silicone, trisiloxane having an alkylene oxide group in the side chain and / or both ends of the polydimethylsiloxane chain is particularly preferable. By using trisiloxane, the dynamic surface tension of the treatment liquid can be effectively reduced, and an image with good adhesion to the non-absorbent substrate can be obtained. The trisiloxane preferably has a structure represented by the following general formula (1).

[0053]

Chemical formula

[0054] In the general formula (1), "EO" represents the repeating unit structure of polyethylene oxide, that is, the structure in which ethylene oxide, a three-membered cyclic ether, is ring-opened. Further, "PO" represents the repeating unit structure of polypropylene oxide, that is, the structure in which propylene oxide, a three-membered cyclic ether, is ring-opened. Here, "the order of [EO]m and [PO]n may be either" means that in the compound molecule represented by the general formula (1), the order of the bonding positions with respect to the siloxane skeleton serving as the parent may be appropriately changed.

[0055] In the general formula (1), X is preferably an alkylene group having 3 carbon atoms (that is, a propylene group). Further, in the general formula (1), m is preferably an integer from 5 to 20, and n is preferably an integer from 0 to 6.

[0056] Specific examples of the silicone surfactant having the structure represented by the general formula (1) are shown below as S-1 to S-8, but are not limited thereto. (S-1): In the general formula (1), R = methyl group, X = alkylene group having 3 carbon atoms, m = 9, n = 0 (S-2): In the general formula (1), R = butyl group, X = alkylene group having 3 carbon atoms, m = 25, n = 6 (S-3): In the general formula (1), R = hydrogen atom, X = alkylene group having 3 carbon atoms, m = 3, n = 0 (S-4): In the general formula (1), R is a hydrogen atom, X is an alkylene group having 3 carbon atoms, m = 33, and n = 0 (S-5): In the general formula (1), R is a hydrogen atom, X is an alkylene group having 3 carbon atoms, m = 22, and n = 16 (S-6): In the general formula (1), R is a hydrogen atom, X is an alkylene group having 3 carbon atoms, m = 9, and n = 0 (S-7): In the general formula (1), R is a hydrogen atom, X is an alkylene group having 3 carbon atoms, m = 12, and n = 3 (S-8): In the general formula (1), R is a hydrogen atom, X is an alkylene group having 3 carbon atoms, m = 1, and n = 0

[0057] 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. In addition, the content of the polyether-modified silicone is preferably in the range of 0.1 to 2% by mass, more preferably in the range of 0.5 to 1.5% by mass, based on 100% by mass of the total mass of the treatment liquid.

[0058] In addition to the polyether-modified silicone, the treatment liquid may contain a known surfactant. Examples of the known surfactant include fluorine-based surfactants having a high ability to reduce static surface tension, anionic surfactants such as dioctyl sulfosuccinate having a high ability to reduce dynamic surface tension, relatively low molecular weight polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, acetylene glycols, Pluronic type surfactants (Pluronic is a registered trademark), and nonionic surfactants such as sorbitan derivatives.

[0059] <Water> The water contained in the treatment liquid according to the present invention is not particularly limited and may be ion-exchanged water, distilled water, or pure water.

[0060] <Water-soluble solvent> Examples of the water-soluble solvent contained in the treatment liquid according to the present invention include alcohols, polyhydric alcohols, amines, amides, glycol ethers, 1,2-alkanediols having 4 or more carbon atoms, and the like. In particular, it is preferable to use a water-soluble solvent having an SP value of 24 (J / cm 3 ) 1 / 2 or more. By using a water-soluble solvent having an SP value of 24 (J / cm 3 ) 1 / 2 or more, the cloud point of the treatment liquid is lowered. As a result, in the ink drying step, the treatment liquid can be heated to a temperature equal to or higher than the cloud point, and an image with good adhesion to the non-absorbent substrate can be obtained.

[0061] In the present invention, the SP value is what is called the solubility parameter. The SP value in the present invention is a value calculated by the Fedors method. It is obtained from the molar heat of vaporization of the water-soluble solvent and the molar volume of the water-soluble solvent at 25°C. Although the unit of the SP value is generally cal, when converting to the SI unit system, the relationship of (cal / cm 3 ) 1 / 2 = 2.046×10 3 (J / m 3 ) 1 / 2 may be used. In the following description, the unit of the SP value may be omitted, but the SP value is a value expressed in the unit of (J / cm 3 ) 1 / 2 .

[0062] Examples of the water-soluble solvent having an SP value of 24 (J / cm 3 ) 1 / 2 or more include monohydric alcohols having 1 to 4 carbon atoms, polyhydric alcohols having 2 to 8 carbon atoms, polyalkylene glycols, monoalkyl polyalkylene glycols, and the like.

[0063] Examples of the monohydric alcohols having 1 to 4 carbon atoms include methanol (SP value: 28.2), ethanol (SP value: 25.7), 1-propanol (SP value: 24.2), and the like.

[0064] Examples of polyhydric alcohols 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: 30.3), 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), glycerin (SP value: 33.5), trimethylolpropane (SP value: 32.5), and the like.

[0065] Examples of polyalkylene glycols include diethylene glycol (SP value: 30.6), triethylene glycol (SP value: 27.8), tetraethylene glycol (SP value: 26.1), dipropylene glycol (SP value: 27.2), and the like.

[0066] Examples of monoalkyl polyalkylene glycols include ethylene glycol monomethyl ether (SP value: 24.5), and the like.

[0067] The treatment liquid can contain one or a combination of two or more selected from these water-soluble solvents.

[0068] The total content of the water-soluble solvent is preferably in the range of 5 to 40% by mass, more preferably in the range of 10 to 40% by mass, based on 100% by mass of the total mass of the treatment liquid.

[0069] The treatment liquid can be appropriately blended with other components such as crosslinking agents, antifungal agents, bactericides, etc., as long as the effects of the present invention are not impaired.

[0070] Furthermore, various known additives such as ultraviolet absorbers described in, for example, JP-A-57-74193, JP-A-57-87988, and JP-A-62-261476, anti-fading agents described in JP-A-57-74192, JP-A-57-87989, JP-A-60-72785, JP-A-61-146591, JP-A-1-95091, and JP-A-3-13376, various anionic, cationic, or nonionic surfactants, fluorescent brightening agents described in JP-A-59-42993, JP-A-59-52689, JP-A-62-280069, JP-A-61-242871, and JP-A-4-219266, defoaming agents, lubricants such as diethylene glycol, preservatives, thickeners, antistatic agents, etc. can also be contained.

[0071] It is preferable to prepare a treatment liquid layer by directly applying and drying the treatment liquid according to the present invention as a coating liquid on a substrate. Here, the additives preferably used in the treatment liquid are preferably used as a coating liquid after being sufficiently dissolved.

[0072] As the coating method of the treatment liquid, an inkjet method, a roll coating method, a rod bar coating method, an air knife coating method, a spray coating method, a curtain coating method, or an extrusion coating method using a hopper described in U.S. Patent 2681294 is preferably used, and particularly the inkjet method is preferable.

[0073] [Ink] The ink according to the present invention contains at least a colorant and resin fine particles having a glass transition temperature in the range of 40 to 90°C. Further, it preferably contains water and a water-soluble solvent.

[0074] [Colorant] The colorant contained in the ink according to the present invention is preferably a pigment. As the pigment, it is preferable to use an anionic dispersed pigment, for example, a self-dispersing pigment having an anionic group on the surface, a pigment dispersed by an anionic polymer dispersant, or a pigment dispersed by coating the surface with an anionic resin. In particular, using a pigment dispersed by an anionic polymer dispersant is preferable in terms of excellent dispersibility and appropriately reacting with the treatment liquid to cause pinning.

[0075] As the pigment, conventionally known ones 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.

[0076] In the case of titanium oxide, in which it is generally difficult to ensure ink ejection stability and adhesion, according to the present invention, bleeding is particularly preferably less likely to occur, and adhesion can be enhanced.

[0077] Titanium oxide has three crystal forms: anatase type, rutile type, and brookite type. Generally, it can be roughly classified into anatase type and rutile type. Although not particularly limited, the rutile type with a large refractive index and high hiding power is preferable. Specifically, examples include the TR series of Fuji Titanium Industry Co., Ltd., the JR series of Tayca Corporation, and Type-Pake of Ishihara Sangyo Co., Ltd.

[0078] As the insoluble pigment, although not particularly limited, for example, azo, azomethine, methine, diphenylmethane, triphenylmethane, quinacridone, anthraquinone, perylene, indigo, quinophthalone, isoindolinone, isoindoline, azine, oxazine, thiazine, dioxazine, thiazole, phthalocyanine, diketopyrrolopyrrole, etc. are preferable.

[0079] Specific organic pigments that can be preferably used include the following pigments.

[0080] Examples of pigments for magenta or red include, for example, C.I. Pigment Red 2, C.I. Pigment Red 3, C.I. Pigment Red 5, C.I. Pigment Red 6, C.I. Pigment Red 7, C.I. Pigment Red 15, C.I. Pigment Red 16, C.I. Pigment Red 48:1, C.I. Pigment Red 53:1, C.I. Pigment Red 57:1, C.I. Pigment Red 122, C.I. Pigment Red 123, C.I. Pigment Red 139, C.I. Pigment Red 144, C.I. Pigment Red 149, C.I. Pigment Red 166, C.I. Pigment Red 177, C.I. Pigment Red 178, C.I. Pigment Red 202, C.I. Pigment Red 222, C.I. Pigment Violet 19, and the like.

[0081] Examples of pigments for orange or yellow include, for example, C.I. Pigment Orange 31, C.I. Pigment Orange 43, C.I. Pigment Yellow 12, C.I. Pigment Yellow 13, C.I. Pigment Yellow 14, C.I. Pigment Yellow 15, C.I. Pigment Yellow 15:3, C.I. Pigment Yellow 17, C.I. Pigment Yellow 74, C.I. Pigment Yellow 93, C.I. Pigment Yellow 128, C.I. Pigment Yellow 94, C.I. Pigment Yellow 138, C.I. Pigment Yellow 155, and the like. Particularly in terms of the balance between color tone and lightfastness, C.I. Pigment Yellow 155 is preferred.

[0082] Examples of pigments for green or cyan include, for example, C.I. Pigment Blue 15, C.I. Pigment Blue 15:2, C.I. Pigment Blue 15:3, C.I. Pigment Blue 16, C.I. Pigment Blue 60, C.I. Pigment Green 7, and the like.

[0083] Examples of pigments for black include, for example, C.I. Pigment Black 1, C.I. Pigment Black 6, C.I. Pigment Black 7, and the like.

[0084] <Pigment dispersant> The treatment liquid according to the present invention preferably contains a pigment dispersant for dispersing the pigment. The pigment dispersant is not particularly limited, but a polymer dispersant having an anionic group is preferable, and those having a molecular weight in the range of 5000 to 200000 can be preferably used.

[0085] Examples of the polymer dispersant include block copolymers, random copolymers 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, and salts thereof, polyoxyalkylene, polyoxyalkylene alkyl ethers, and the like.

[0086] The polymer dispersant preferably has an acryloyl group and is preferably added after being neutralized with a neutralizing base. Here, the neutralizing base is not particularly limited, but an organic base such as ammonia, monoethanolamine, diethanolamine, triethanolamine, morpholine, etc. is preferable. In particular, when the pigment is titanium oxide, it is preferable that the titanium oxide is dispersed with a polymer dispersant having an acryloyl group.

[0087] Also, the addition amount of the polymer dispersant is preferably in the range of 10 to 100% by mass, more preferably in the range of 10 to 40% by mass, based on the pigment.

[0088] The pigment particularly preferably has a form of a so-called capsule pigment in which the pigment is coated with the above polymer dispersant. As a method for coating the pigment with the polymer dispersant, various known methods can be used. For example, 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 performed while polymerization can be preferably exemplified.

[0089] As a particularly preferred method, an insoluble resin is dissolved in an organic solvent such as methyl ethyl ketone, and after the acidic groups in the resin are partially or completely neutralized with a base, a pigment and ion-exchanged water are added. After dispersion, the organic solvent is removed and water is added as necessary for preparation.

[0090] The average particle size of the dispersed state of the pigment in the ink is preferably 50 nm or more and less than 200 nm. Thereby, the dispersion stability of the pigment can be improved and the storage stability of the ink can be improved. The particle size of the pigment can be determined by a commercially available particle size measuring instrument using the dynamic light scattering method, electrophoresis method, etc. However, the measurement by the dynamic light scattering method is simple and can accurately measure the particle size region.

[0091] The pigment can be dispersed and used by a disperser together with a dispersant and other additives necessary according to various desired purposes.

[0092] As the disperser, conventionally known ball mills, sand mills, line mills, high-pressure homogenizers, etc. can be used. Among them, it is preferable to disperse the pigment by a sand mill because the particle size distribution becomes sharp. Further, the material of the beads used for sand mill dispersion is not particularly limited, but from the viewpoint of preventing the generation of bead fragments and the contamination of ionic components, it is preferably zirconia or zircon. Furthermore, the bead diameter is preferably in the range of 0.3 to 3 mm.

[0093] The content of the pigment in the ink is not particularly limited, but for titanium oxide, it is preferably in the range of 7 to 18% by mass, and for organic pigments, it is preferably in the range of 0.5 to 7% by mass.

[0094] <Resin fine particles> The resin fine particles (hereinafter also simply referred to as "resin") contained in the ink according to the present invention are resin fine particles having a glass transition temperature in the range of 40 to 90°C, and are preferably water-insoluble resin fine particles. The glass transition temperature (glass transition point (Tg)) can be specified by reading the glass transition temperature Tg from the endothermic peak when heating is carried out at a rate of 10 °C / min in a temperature range of -30 to 200 °C using a DSC (differential scanning calorimeter). The water-insoluble resin fine particles used in the present invention are water-insoluble resins that can receive ink and exhibit solubility or affinity for the ink.

[0095] Water-insoluble resin fine particles are those that are inherently water-insoluble but have a form in which the resin is dispersed in an aqueous medium as microscopic fine particles, and are either water-insoluble resins that are forced to emulsify using an emulsifier or the like and dispersed in water, or water-insoluble resins that can self-emulsify to form a stable aqueous dispersion by introducing a hydrophilic functional group into the molecule without using an emulsifier or a dispersion stabilizer. These resins are usually used in a state of being emulsified and dispersed in water or a water / alcohol mixed solvent.

[0096] In the present invention, "water-insoluble" means a resin that, after drying the resin at 105 °C for 2 hours and dissolving it in 100 g of water at 25 °C, has a dissolved amount of 10 g or less, preferably 5 g or less, more preferably 1 g or less. However, when the resin has a salt-forming group, the dissolved amount is the dissolved amount when the salt-forming group of the resin is 100% neutralized with acetic acid or sodium hydroxide depending on its type.

[0097] As the resin having a glass transition temperature in the range of 40 to 90 °C, it is preferably any one of an acrylic resin, a urethane resin, a polyester resin, or a composite resin of a urethane resin and an acrylic resin, particularly an acrylic resin, a urethane resin, a polyester resin, or a composite resin of a urethane resin and an acrylic resin, and it is preferable that the average particle diameter of the resin fine particles of these resins is 200 nm or less. In particular, the average particle diameter is preferably in the range of 100 to 150 nm.

[0098] The composite resin fine particles of the above polyester resin, urethane resin, acrylic resin, or composite resin of a urethane resin and an acrylic resin are preferably anionic or nonionic.

[0099] Among them, the resin fine particles used in the ink preferably contain an acid structure. Even when the addition amount of the surfactant is small, they can be dispersed in water, and the water resistance of the ink layer is improved. This is called a self-emulsifying type, which means that the urethane resin can be dispersed and stabilized in water only by molecular ionic properties without using a surfactant. Examples of the acid structure include acid groups such as carboxy group (-COOH) and sulfonic acid group (-SO3H). The acid structure may be present in the side chain or at the end of the resin.

[0100] Preferably, some or all of the above acid structures are neutralized. By neutralizing the acid structure, the water dispersibility of the resin can be improved. Examples of the neutralizing agent for neutralizing the acid structure preferably include organic amines, and it is preferable to use organic amines such as trimethylamine, triethylamine, tripropylamine, tributylamine, N-methyldiethanolamine, and triethanolamine.

[0101] Further, the ink according to the present invention preferably contains resin fine particles having an aggregability of 0.2 or less with a 0.15 mass% aqueous solution of calcium acetate monohydrate in the range of 3 to 15 mass%. By using resin fine particles having such low aggregability, high wettability to the substrate can be ensured while obtaining high ejection stability, and higher image quality and excellent substrate adhesion can be achieved. In the present invention, the "aggregability" is a value calculated by the following formula after measuring the remaining amount by the following procedure. (i) Mix 5 g of an aqueous solution of resin fine particles containing resin fine particles (solid content: 10 mass%) and 5 g of an aqueous solution of 0.3 mass% calcium acetate monohydrate. (ii) Centrifuge the mixed liquid. (iii) Collect about 2 g of the supernatant separated by centrifugation. (iV) Measure the mass of the solid content (remaining amount (g)) after heating and drying about 2 g of the collected supernatant at 150 °C for 30 minutes. (V) Calculate the value of aggregability by the following formula. Formula: Coagulability = 1 - (mass of solid content (g) / mass of collected supernatant (g) × 5%)

[0102] Examples of the resin fine particles having a coagulability of 0.2 or less include, for example, BYRONAL MD2000 manufactured by Toyobo Co., Ltd., MOBINYL 6969D manufactured by Japan Coating Resin Co., Ltd., EVAFANOL HA-560 manufactured by Nikkawa Chemical Co., Ltd., and the like.

[0103] Hereinafter, each resin will be described. (Polyester resin) The polyester resin having a polyester skeleton as water-insoluble resin fine particles can be obtained by using a polyhydric alcohol component and a polyvalent carboxylic acid component such as a polyvalent carboxylic acid, a polyvalent carboxylic anhydride, and a polyvalent carboxylic ester.

[0104] Examples of the polyhydric alcohol component include dihydric alcohols (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 diols having 6 to 36 carbon atoms (1,4-cyclohexanedimethanol, hydrogenated bisphenol A, etc.), adducts of alkylene oxides (ethylene oxide (hereinafter abbreviated as EO), propylene oxide (hereinafter abbreviated as PO), butylene oxide (hereinafter abbreviated as BO)) having 2 to 4 carbon atoms in the alicyclic diol in the range of 1 to 30 moles of addition, or adducts of alkylene oxides (EO, PO, BO, etc.) having 2 to 4 carbon atoms in bisphenols (bisphenol A, bisphenol F, bisphenol S, etc.) in the range of 2 to 30 moles of addition. These may be used alone or in combination of two or more.

[0105] As the polyvalent carboxylic acid component, divalent carboxylic acids (dicarboxylic acids) can be used. Specifically, examples thereof include alkane dicarboxylic acids having 4 to 36 carbon atoms (such as succinic acid, adipic acid, and sebacic acid), alkenyl succinic acids (such as dodecenyl succinic acid), alicyclic dicarboxylic acids having 4 to 36 carbon atoms (such as dimer acid (dimerized linoleic acid)), alkenedicarboxylic acids having 4 to 36 carbon atoms (such as maleic acid, fumaric acid, citraconic acid, and mesaconic acid), or aromatic dicarboxylic acids having 8 to 36 carbon atoms (such as phthalic acid, isophthalic acid, terephthalic acid or derivatives thereof, naphthalenedicarboxylic acid, etc.). These may be used alone or in combination of two or more.

[0106] The number average molecular weight of the polyester resin is preferably in the range of 1,000 to 50,000, and more preferably in the range of 2,000 to 20,000.

[0107] As the polyester resin, commercially available products may be used. Examples of commercially available products having a glass transition temperature of 40 to 90 °C include, for example, Vylon MD-1100, MD-1200, MD-1245, MD-1500, MD-2000 manufactured by Toyobo Co., Ltd., Plaskote Z-221, Z-446, Z-561 manufactured by Gohsei Chemical Industry Co., Ltd., Pesresin A-520, A-613D, A-615GE, A-640, A-645GH, A-647GEX, A-684G, A-690, A-695GE manufactured by Takamatsu Yushi Co., Ltd., Eritel KA-5034, KA-5071S, KA-1449, KA-0134, KA-3556, KA-6137, KZA-6034, KT-8803, KT-9511 manufactured by Unitika Ltd., etc. These may be used alone or in combination of two or more.

[0108] (Urethane resin) As the urethane resin as the water-insoluble resin fine particles, those having a hydrophilic group can be used.

[0109] The above urethane resin is preferably an aqueous dispersion in which a self-emulsifying urethane having a water-soluble functional group in its molecule is dispersed, or an aqueous dispersion of a forced-emulsified urethane emulsified under strong mechanical shearing force using a surfactant in combination. The urethane resin in the above aqueous dispersion can be obtained by the reaction of a polyol, an organic polyisocyanate, and a hydrophilic group-containing compound.

[0110] Examples of polyols that can be used in the preparation of the aqueous dispersion of the above urethane resin include polyester polyols, polyether polyols, polycarbonate polyols, and polyolefin-based polyols.

[0111] Examples of polyester polyols include 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-butanediol, 3-methylpentanediol, hexamethylene glycol, 1,8-octanediol, 2-methyl-1,3-propanediol, bisphenol A, hydrogenated bisphenol A, trimethylolpropane, and cyclohexanedimethanol; condensates with polyvalent carboxylic acids such as succinic acid, glutaric acid, adipic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, tetrahydrofuran acid, endomethylenetetrahydrofuran acid, and hexahydrophthalic acid.

[0112] Examples of polyether polyols include polyethylene glycol, polypropylene glycol, polyethylene polytetramethylene glycol, polypropylene polytetramethylene glycol, and polytetramethylene glycol.

[0113] Examples of polycarbonate polyols can be obtained by the reaction of carbonic acid derivatives such as diphenyl carbonate, dimethyl carbonate or phosgene with diols. Examples of the above diols include ethylene glycol, diethylene glycol, triethylene glycol, 1,2- and 1,3-propylene glycol, neopentyl glycol, 1,3- and 1,4-butanediol, 3-methylpentanediol, hexamethylene glycol, 1,8-octanediol, 2-methyl-1,3-propanediol, bisphenol A, hydrogenated bisphenol A, trimethylolpropane, and cyclohexanedimethanol.

[0114] Examples of organic polyisocyanates that can be used in the preparation of aqueous dispersions of urethane resins include aromatic isocyanates such as tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymeric MDI, xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI); aliphatic isocyanates such as hexamethylene diisocyanate (HMDI); and alicyclic isocyanates such as isophorone diisocyanate (IP DI), 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI, H12MDI). These may be used alone or in combination of two or more.

[0115] Examples of hydrophilic group-containing compounds that can be used in the preparation of aqueous dispersions of urethane resins include carboxylic acid-containing compounds such as 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, 2,2-dimethylolbutyric acid, 2,2-dimethylolvaleric acid, glycine, and their derivatives such as sodium salts, potassium salts, and amine salts; sulfonic acid-containing compounds such as taurine (i.e., aminoethylsulfonic acid), ethoxypolyethylene glycol sulfonic acid, and their derivatives such as sodium salts, potassium salts, and amine salts.

[0116] The urethane resin can be obtained by a known method. For example, by mixing the above-mentioned polyol, organic polyisocyanate, and a hydrophilic group-containing compound, and reacting them at 30 to 130 °C for 30 minutes to 50 hours, a urethane prepolymer can be obtained.

[0117] The above urethane prepolymer is polymerized by chain extension with a chain extender to form a urethane resin having a hydrophilic group. The chain extender is preferably water and / or an amine compound. By using water or an amine compound as the chain extender, it can react with free isocyanate in a short time to efficiently extend the isocyanate-terminated prepolymer.

[0118] Examples of the amine compound as the chain extender include aliphatic polyamines such as ethylenediamine and triethylenediamine; aromatic polyamines such as metaxylenediamine and toluylenediamine; polyhydrazino compounds such as hydrazine and adipic acid dihydrazide. The above amine compound may contain a monovalent amine such as dibutylamine and a reaction terminator such as methyl ethyl ketoxime to the extent that it does not significantly inhibit polymerization together with the above polyamine.

[0119] In the synthesis of the urethane prepolymer, a solvent that is inert to isocyanate and can dissolve the urethane prepolymer may be used. Examples of these solvents include dioxane, methyl ethyl ketone, dimethylformamide, tetrahydrofuran, N-methyl-2-pyrrolidone, toluene, and propylene glycol monomethyl ether acetate. These hydrophilic organic solvents used in the reaction stage are preferably finally removed.

[0120] In the synthesis of the urethane prepolymer, in order to accelerate the reaction, catalysts such as amine catalysts (e.g., triethylamine, N-ethylmorpholine, triethyldiamine, etc.), tin-based catalysts (e.g., dibutyltin dilaurate, dioctyltin dilaurate, tin octylate, etc.), and titanium-based catalysts (e.g., tetrabutyl titanate, etc.) may be added.

[0121] The number average molecular weight of the urethane resin is preferably made as large as possible by introducing a branched structure or an internal crosslinked structure, and it is preferably 50,000 to 10,000,000. By setting the molecular weight within the above range, the urethane resin becomes less soluble in the solvent, so that a coating film excellent in weather resistance and water resistance can be obtained. The number average molecular weight (Mn) is a value measured by gel permeation chromatography (GPC). For example, it can be determined from a calibration curve prepared with a polystyrene standard sample using "RID-6A" manufactured by Shimadzu Corporation (column: "TSK-GEL" manufactured by Tosoh Corporation, solvent: tetrahydrofuran (THF), column temperature: 40°C).

[0122] Moreover, a commercially available product may be used as the above urethane resin. Examples of commercially available products having a glass transition temperature of 40 to 90°C of the above urethane resin include Neorez R-967, R-600, R-9671 manufactured by Kusumoto Chemicals, Ltd., Evafanol HA-560 manufactured by Nippon Kayaku Co., Ltd., SF870 manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., and the like.

[0123] (Acrylic resin) The acrylic resin as water-insoluble resin fine particles can be obtained by using a copolymer of an acrylate ester component, a methacrylate ester component, a styrene component, or the like. Examples of the acrylic ester component and the methacrylic ester 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, diethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, glycerin di(meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, and acrylamide, etc.

[0124] 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 two or more of them may be used in combination.

[0125] The number average molecular weight (Mn) of the above acrylic resin is preferably from 1000 to 50000, more preferably from 2000 to 20000. When the number average molecular weight (Mn) of the above acrylic resin is 1000 or more, the cohesive force of the coating film becomes strong and the adhesion is improved. When it is 50000 or less, the solubility in organic solvents is good and the miniaturization of the particle size of the emulsion dispersion is promoted. The number average molecular weight (Mw) is a value measured by gel permeation chromatography (GPC). For example, it can be determined from a calibration curve prepared with a polystyrene standard sample using "RID-6A" manufactured by Shimadzu Corporation (column: "TSK-GEL" manufactured by Tosoh Corporation, solvent: tetrahydrofuran (THF), column temperature: 40°C).

[0126] Alternatively, commercially available products may be used as the acrylic resin. Examples of commercially available products with a glass transition temperature of 40 to 90 °C for the acrylic resin include acrylic emulsions such as Mobinyl 6899D, 6969D, 6800 manufactured by Japan Coating Resin Co., Ltd., and TOCRYL W-7146, W-7147, W-7148, W-7149, W-7150 manufactured by Toyochem Co., Ltd.

[0127] (Composite resin fine particles) The composite resin fine particles that can be contained in the ink are preferably composite resin fine particles in which the acrylic resin is emulsified in the urethane resin. That is, it is preferably composite resin fine particles having an inner layer composed of an acrylic resin and a surface layer composed of a urethane resin.

[0128] Here, the urethane resin exists at the interface between the acrylic resin as 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 that protects the water-insoluble resin fine particles.

[0129] By using composite resin fine particles obtained by emulsifying the acrylic resin with the urethane resin in this way, the physical properties of the image (coating film) can be improved, and the storage stability of the composite resin fine particles can also be improved, as compared with emulsifying and mixing the acrylic resin and the urethane resin separately.

[0130] In the composite resin fine particles in which the acrylic resin is emulsified in the urethane resin, the mass ratio value (U / A) of the urethane resin (U) to the acrylic resin (A) is preferably 40 / 60 to 95 / 5. When the proportion of the urethane resin (U) is within the above range, the physical properties of the image (coating film) can be improved. Also, when the proportion of the acrylic resin (A) is within the above range, the adhesion to the acrylic film is excellent. In the above proportion, the mass ratio value (U / A) of the urethane resin (U) to the acrylic resin (A) is preferably 40 / 60 to 80 / 20.

[0131] The total resin concentration of the acrylic resin and the urethane resin in the composite resin fine particles is not particularly limited, but is preferably 5.0% by mass or more, and more preferably 10.0 to 70.0% by mass. When the resin concentration is within the above range, the fixing property between the base material and the ink becomes good.

[0132] In addition, in the emulsification of the acrylic resin with the urethane resin, a surfactant that acts as an emulsifier can be used together with the urethane resin. Here, by adding an emulsifier, the storage stability of the composite resin fine particles can be improved.

[0133] As the above emulsifier, an anionic surfactant and a nonionic surfactant can be used. In the present invention, it is preferable to use either one of the anionic surfactant and the nonionic surfactant, and more preferably to use both. Here, the total blending amount of the anionic surfactant and the nonionic surfactant is preferably 1.0 to 20.0 parts by mass with respect to 100 parts by mass of the total resin mass. Further, by setting the total blending amount of the anionic surfactant and the nonionic surfactant to 20.0 parts by mass or less, the water resistance and solvent resistance can be improved.

[0134] In addition, the value of the blending mass ratio (X / Y) of the anionic surfactant (X) and the nonionic surfactant (Y) is preferably 100 / 0 to 50 / 50. By setting the blending amount of the anionic surfactant within the above range, the emulsifying property and storage stability can be further improved.

[0135] Here, examples of the anionic surfactant that can be used for emulsification include alkyl sulfates, polyoxyethylene alkyl ether sulfates, sulfosuccinates, alpha olefin sulfonates, N-acyl amino acid salts, carboxylates, and phosphate esters. Among these, sulfosuccinates and alpha olefin sulfonates are preferable. Examples of the type of salt include, but are not particularly limited to, metal salts such as sodium salts, potassium salts, and magnesium salts, and triethanolamine salts.

[0136] Examples of nonionic surfactants that can be used for emulsification include polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl amine ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, sucrose fatty acid esters, etc. Among these, polyoxyethylene alkyl ethers and polyoxyethylene alkyl phenyl ethers are preferred. Yes.

[0137] The average particle diameter of the above-mentioned composite resin fine particles 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 diameter can be determined by commercially available particle diameter measuring equipment using methods such as dynamic light scattering method and electrophoresis method. However, the measurement by the dynamic light scattering method is simple and can accurately measure the particle diameter region.

[0138] By using composite resin fine particles in which an acrylic resin is emulsified in a urethane resin, the fixing property of an image (coating film) on a low-absorbing substrate or a non-absorbing substrate can be improved.

[0139] <Water-soluble solvent> Examples of the water-soluble solvent contained in the ink according to the present invention include alcohols, polyhydric alcohols, amines, amides, glycol ethers, 1,2-alkanediols having 4 or more carbon atoms, and the like.

[0140] Examples of alcohols include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, t-butanol, 3-methoxy-1-butanol, 3-methoxy-3-methylbutanol, 1-octanol, 2-octanol, n-nonyl alcohol, tridecyl alcohol, n-undecyl alcohol, stearyl alcohol, oleyl alcohol, benzyl alcohol, and the like.

[0141] Examples of polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol with 5 or more ethylene oxide groups, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol with 4 or more propylene oxide groups, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol, and the like.

[0142] Examples of amines include ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, pentamethyldiethylenetriamine, tetramethylpropylenediamine, and the like.

[0143] Examples of amides include formamide, N,N-dimethylformamide, N,N-dimethylacetamide, and the like.

[0144] Examples of 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, tripropylene glycol monomethyl ether, and the like.

[0145] Examples of 1,2-alkanediols having 4 or more carbon atoms include 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-heptanediol, and the like.

[0146] Water-soluble solvents that are particularly preferably used are polyhydric alcohols, which can preferably suppress bleeding during high-speed printing. Specifically, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, and tripropylene glycol are preferred.

[0147] The ink can contain one or a combination of two or more selected from these water-soluble solvents.

[0148] The content of the water-soluble solvent in the ink is not particularly limited, but is preferably in the range of 10 to 60% by mass.

[0149] <Water, other additives> The water contained in the ink according to the present invention is not particularly limited and can be ion-exchanged water, distilled water, or pure water.

[0150] The ink according to the present invention can also contain a surfactant, if necessary. Thereby, the ink ejection stability can be improved, and the spread (dot diameter) of the droplets landing on the recording medium can be controlled.

[0151] The surfactant that can be used in the ink according to the present invention can be used without particular limitation. However, when the other components of the ink contain an anionic compound, the ionic property of the surfactant is preferably anionic, nonionic or betaine type. In particular, in the present invention, when an alkali component is contained in a surfactant such as an anionic surfactant, the aggregability of the pigment is reduced, and the resin fine particles themselves are likely to aggregate. Therefore, a nonionic surfactant is preferable.

[0152] In the present invention, preferably, a fluorine-based or silicone-based surfactant having a high ability to reduce static surface tension, an anionic surfactant such as dioctyl sulfosuccinate having a high ability to reduce dynamic surface tension, a polyoxyethylene alkyl ether having a relatively low molecular weight, a polyoxyethylene alkyl phenyl ether, acetylene glycols, a Pluronic (registered trademark) type surfactant, a nonionic surfactant such as a sorbitan derivative is preferably used. It is also preferable to use a fluorine-based or silicone-based surfactant in combination with a surfactant having a high ability to reduce dynamic surface tension.

[0153] The content of the surfactant in the ink is not particularly limited, but is preferably in the range of 0.1 to 5.0% by mass.

[0154] In the ink used in the present invention, in addition to those described above, various known additives can be appropriately selected and used as needed for the purpose of improving various performances such as emission stability, print head and ink cartridge compatibility, storage stability, image storage property, etc. For example, polysaccharides, viscosity modifiers, specific resistance modifiers, film forming agents, ultraviolet absorbers, antioxidants, anti-fading agents, fungicides, rust preventives, etc. can be used. For example, oil droplet microparticles such as liquid paraffin, dioctyl phthalate, tricresyl phosphate, silicone oil, ultraviolet absorbers described in JP-A-57-74193, JP-A-57-87988, JP-A-62-261476, etc., anti-fading agents described in JP-A-57-74192, JP-A-57-87989, JP-A-60-72785, JP-A-61-146591, JP-A-1-95091, JP-A-3-13376, etc., and fluorescent brightening agents described in JP-A-59-42993, JP-A-59-52689, JP-A-62-280069, JP-A-61-242871, JP-A-4-219266, etc. can be mentioned.

[0155] The ink used in the present invention having the above configuration preferably has a viscosity of 1 to 40 mPa·s at 25°C, more preferably 2 to 10 mPa·s.

[0156] [Inkjet recording method] The inkjet recording method of the present invention is an inkjet recording method for recording an image using an ink set containing the above-described treatment liquid and ink. By using this ink set, for example, with one inkjet printer, it is possible to efficiently and continuously perform the application of the treatment liquid constituting the ink set of the present invention and printing with the ink on the surface of a non-absorbent substrate. And it becomes possible to print characters, patterns, etc. with excellent image quality and little variation in dot diameter between substrates.

[0157] Specifically, the inkjet recording method of the present invention includes a step of applying the treatment liquid to a recording area of a non-absorbent substrate (treatment liquid application step), a step of applying the ink to the area where the treatment liquid has been applied by an inkjet recording method (ink application step), and a step of heating the area where the ink has been applied at a heating temperature equal to or higher than the cloud point and equal to or higher than the glass transition temperature (ink heating step). In addition to the above steps, the inkjet recording method of the present invention may also include a treatment liquid drying step of drying the treatment liquid applied on the substrate after the treatment liquid application step to form a treatment liquid layer.

[0158] In the step of applying the ink by an inkjet recording method, it is preferable to apply the ink to the area where the treatment liquid has been applied in a state where the drying rate of the treatment liquid is 30% or less. It is preferable to perform the ink application step within 10 seconds after the treatment liquid application step. In particular, it is preferable to perform the ink application step within 0.1 to 5 seconds after the treatment liquid application step when the drying rate of the treatment liquid is in the range of 1 to 10%.

[0159] <Non-absorbent substrate> As the non-absorbent substrate that can be used in the inkjet recording method of the present invention, a known plastic film can be used. In the present invention, "non-absorbent" means non-absorbent to water.

[0160] Specific examples of the known plastic film include polyester films such as polyethylene terephthalate, polyethylene films, polypropylene films, polyamide-based films such as nylon, polystyrene films, polyvinyl chloride films, polycarbonate films, polyacrylonitrile films, biodegradable films such as polylactic acid films, and the like. In addition, in order to impart gas barrier properties, moisture-proof properties, fragrance retention properties, etc., a film coated with polyvinylidene chloride on one or both sides of the film, or a film vapor-deposited with a metal oxide can also be preferably used. The non-absorbent film can be preferably used as an unstretched film or a stretched film. In the case of a plastic film, the thickness of the base material is preferably in the range of 10 to 120 μm, more preferably 12 to 60 μm.

[0161] As the non-absorbent base material, metal base materials such as tin plates for three-piece cans and tin-free steel plates (TFS plates, thickness 0.1 to 0.6 μm) are also preferably used. For example, they can be suitably used for packaging materials for canned foods provided with a thermosetting resin as a coating layer. The packaging material for canned foods, for example, blocks air, moisture, and light and seals the internal food. Therefore, epoxy-phenol-based paints or polyester-based laminating agents are used on the food side, and generally, polyester-based or acrylic-based thermosetting paints are used on the outside.

[0162] Hereinafter, each step of the inkjet recording method will be described. <Treatment liquid application step> In the treatment liquid application step, the above-described treatment liquid is applied onto the recording medium of the non-absorbent base material.

[0163] The method for applying the treatment liquid onto the recording medium of the non-absorbent base material is not particularly limited. For example, a roller coating method, a curtain coating method, a spray coating method, an inkjet method, etc. can be preferably mentioned. Among them, as the step of applying the treatment liquid, the step of using the inkjet method is preferable because it is not necessary to apply the aggregating agent to the non-ink-coated area, and thus the situation where the unreacted aggregating agent with the ink is released and becomes turbid does not occur. In that case, as described later, when the base material to be used is a metal base material or the like, it is also preferable to place the metal base material on the conveying belt and form the treatment liquid layer while conveying the belt, or to use a flat-bed type printer for fixing the base material to form the treatment liquid layer.

[0164] <Treatment liquid drying step> In the present invention, as described above, it is preferable to perform the ink application step in a state where the drying rate of the treatment liquid is 30% or less. In particular, the drying rate is more preferably 10% or less, and it is preferable to perform a step of continuously applying an ink liquid immediately after the treatment liquid application step (ink application step). When performing the ink application step continuously in this way, or when performing the ink application step simultaneously with the treatment liquid application step, the drying of the treatment liquid is performed together with the drying of the ink liquid. The drying rate of the treatment liquid is defined by the following formula. (Drying rate of treatment liquid) = 1 - ((mass of treatment liquid after drying (g)) / (mass of treatment liquid before drying (g))

[0165] However, if the drying rate of the treatment liquid is within the range of 30% or less, a treatment liquid drying step may be performed between the treatment liquid application step and the ink application step. Here, the treatment liquid drying step is a step of drying the treatment liquid applied on a recording medium of a non-absorbent base material to form a treatment liquid layer. The drying of the treatment liquid can be performed under conditions that remove water, water-soluble solvents, etc., which are solvent components of the treatment liquid. The drying temperature of the treatment liquid is preferably, for example, within the range of 40 to 80°C. The drying time of the treatment liquid is preferably, for example, within the range of 1 to 30 seconds.

[0166] The drying of the treatment liquid may be performed, for example, using a non-contact heating type drying device such as a drying furnace or a hot air blower, or using a contact heating type drying device such as a hot plate or a heat roller. Also, drying may be performed by infrared irradiation using a non-contact type infrared heater.

[0167] The drying temperature is (a) the ambient temperature such as the furnace temperature or the hot air temperature when using a non-contact heating type drying device such as a drying furnace or a hot air blower, (b) any one temperature selected from the temperature of the contact heating part or the surface temperature of the surface to be dried when using a contact heating type drying device such as a hot plate or a heat roller, (c) when using an infrared heater, it can be obtained by measuring the surface temperature of the irradiated surface during the entire period of drying the treatment liquid.

[0168] <Ink application step> In the ink application step, the ink of the aforementioned ink set is applied by an inkjet method simultaneously with or immediately after forming a treatment liquid layer on a non-absorbent base recording medium.

[0169] In the ink application step, it is preferable to apply an ink such that the amount of the resin fine particles with respect to the amount of the polyether-modified silicone (also referred to as "application amount") is 80 times or less per unit area. More preferably, the amount is in the range of 5 to 40 times. In order to achieve the above-mentioned application amount, examples include adjusting the content of the polyether-modified silicone in the treatment liquid, the content of the resin fine particles in the ink, and also adjusting the amount of the treatment liquid and ink droplets to be applied.

[0170] The inkjet method is not particularly limited, and a printer equipped with an inkjet head filled with ink can be used. Specifically, based on a digital signal, ink is ejected as droplets from the nozzles of the inkjet head, and this is landed on the treatment liquid layer of the base material to perform printing.

[0171] The above inkjet head may be any of an on-demand type and a continuous type inkjet head. Examples of on-demand type inkjet heads include electro-mechanical conversion methods including single cavity type, double cavity type, vender type, piston type, shear mode type and shared wall type, and electro-thermal conversion methods including thermal inkjet type and bubble jet ( "bubble jet" is a registered trademark of Canon Inc.) type, etc.

[0172] Among the above inkjet heads, it is preferable that the inkjet head uses a piezoelectric element as an electro-mechanical conversion element used in the electro-mechanical conversion method (also referred to as a piezo type inkjet head).

[0173] Further, the inkjet printer may use any of an inkjet head of a scanning type and a single-pass type. In the case of the single-pass type, it is preferable to use an inkjet head of a line head type.

[0174] The inkjet head of the line head type refers to an inkjet head having a length equal to or greater than the width of the printing range. As the inkjet head of the line head type, one head having a length equal to or greater than the width of the printing range may be used, or a plurality of heads may be combined to have a length equal to or greater than the width of the printing range.

[0175] Further, a plurality of heads may be arranged side by side such that their nozzles are staggeredly arranged to increase the resolution of the entire heads.

[0176] The conveyance speed of the recording medium of the non-absorbent base material can be set, for example, within the range of 1 to 120 m / min. The higher the conveyance speed, the faster the image forming speed. According to the present invention, it is possible to obtain a high-definition image with high ink fixing property even at a very high linear speed of 50 to 120 m / min applicable to the single-pass type inkjet image forming method.

[0177] <Ink heating step> In the ink heating step, the ink applied on the recording medium of the non-absorbent base material, that is, the area where the ink is applied is heated. Thereby, the ink can be dried. Here, when the treatment liquid drying step is omitted, the treatment liquid can also be dried in the ink heating step.

[0178] In the ink heating step, the heating temperature of the area where the ink is applied is set to be equal to or higher than the cloud point of the treatment liquid and equal to or higher than the glass transition temperature of the resin fine particles contained in the ink. Specifically, it is preferably within the range of 60 to 200°C.

[0179] By heating the area to which the ink has been applied in this way, mainly water, water-soluble solvents, etc., which are the solvent components of the ink, are removed. At the same time, especially in the case of a metal substrate, the polyvalent metal salt is dried at a temperature above its thermal decomposition temperature and thermally decomposed. Also, the image rub resistance and the adhesion to a non-absorbent substrate become good.

[0180] Also, the drying (heating) of the ink can be performed in the same manner as the drying of the treatment liquid described above. The heating time of the ink is preferably adjusted appropriately according to the type of non-absorbent substrate and the amount of ink applied. However, when using a non-contact heating type drying device such as a drying furnace or a hot air blower, or a contact heating type drying device such as a hot plate or a heat roller, it is preferably 1 to 10 minutes, and when using an infrared heater, it is preferably 1 to 30 seconds.

[0181] Also, the thickness of the ink layer is preferably in the range of 0.3 to 3.0 μm, and more preferably in the range of 0.5 to 2.0 μm. When the thickness of the ink layer is 0.3 μm or more, it is easy to enhance the adhesion and rub resistance strength of the image. When the thickness of the ink layer is 3.0 μm or less, the deformation stress applied to the ink layer can be reduced, so the adhesion of the image is less likely to be impaired.

[0182] [Recording device] FIG. 1 is a schematic diagram of a recording device preferable to the present invention. However, the present invention is not limited thereto. For example, in the recording device 1 shown in FIG. 1, the first drying unit 14 can be omitted.

[0183] The recording device 1 mainly includes a treatment liquid application unit 10 and an ink application unit 20. In the treatment liquid application unit 10, a treatment liquid layer C is formed on the substrate F, and an ink layer R is formed by the ink application unit 20. The treatment liquid application unit 10 is not particularly limited as long as it can apply the treatment liquid to the substrate, but in the present invention, an inkjet head 21 is preferably used. In addition to the inkjet head 21, for example, a roll coater or the like may be used. The ink application unit 20 is an inkjet head 21 capable of discharging ink.

[0184] In such a recording apparatus 1, treatment liquid droplets 12 are discharged from the inkjet head 11 onto a substrate F fed out from the feed roller 30, and a treatment liquid layer C is formed. Subsequently, the treatment liquid layer C is dried by the first drying unit 14.

[0185] Next, ink droplets 22 are discharged from the inkjet head 21 onto the treatment liquid layer C, an ink layer R is formed, and the region to which the ink is applied is heated and dried by the second drying unit 23 at a temperature equal to or higher than the cloud point of the treatment liquid according to the present invention and equal to or higher than the glass transition temperature of the resin fine particles contained in the ink according to the present invention. Thereafter, the substrate F on which the treatment liquid layer C and the ink layer R are formed is wound up by the take-up roller 40, and an image recording material is obtained.

[0186] In FIG. 1, the case where the substrate F is a film substrate is shown. However, in the case of a metal substrate or the like, the metal substrate is placed on a conveyor belt, and the treatment liquid layer C and the ink layer R can be applied and formed in one pass while conveying the belt. Also, in FIG. 1, the apparatus has a configuration in which ink is applied after the treatment liquid is applied to the substrate. However, from the viewpoint of discharging ink from the inkjet head in a state where the drying rate of the treatment liquid layer is 30% or less, an apparatus having a configuration in which the treatment liquid and the ink are applied simultaneously is more preferable.

[0187] Furthermore, as an apparatus other than the recording apparatus shown in FIG. 1, it is also preferable to use a flatbed type printer for applying the treatment liquid and the ink. The flatbed type printer has a fixed substrate, and the inkjet head can be moved in the main scanning direction and the sub-scanning direction intersecting the main scanning direction, and printing can be performed without conveying the substrate. In the case of a metal substrate such as tinplate, since roll-to-roll conveyance is not possible like resin film equipment, it is preferable to use a flatbed type printer that does not require conveyance of the substrate. Examples of such flatbed printers include the printers described in FIG. 1 of JP-A-2015-74161 and FIG. 1 of JP-A-2017-177578.

[0188] [Image recording material] The image recording material according to the present invention preferably has 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.

[0189] As shown in FIG. 2, on the substrate F, the treatment liquid according to the present invention is applied by a roll coater or the like, or discharged from an inkjet head and applied to form a treatment liquid layer C. Ink is discharged from an inkjet head and fixed at a position where the treatment liquid layer C is fixed to form an image recording layer R.

[0190] The above configuration shows the minimum configuration, and other functional layers may be formed between the substrate and the treatment liquid layer. Further, a non-absorbent film substrate or the like may be bonded to the upper layer of the ink layer via, for example, a laminate adhesive layer. At least, a configuration in which the treatment liquid layer and the ink layer are in contact is essential.

[0191] As an example of the image recording material of the present invention, an image recording material using at least the treatment liquid and ink according to the present invention, in which a first layer containing a thermosetting resin, a second layer containing the treatment liquid, a third layer containing the ink, and a fourth layer containing a thermosetting resin are laminated in this order on a metal substrate, is a preferred embodiment.

[0192] Specific examples of the image recording material preferably include packaging materials for packaging canned foods, retort foods, beverages, and the like.

[0193] FIG. 3 shows a cross-sectional view of a packaging material for canned foods, which is an example of the image recording material of the present invention. A thermosetting resin (e.g., TW-1407 series manufactured by T&K TOKA) is roller-coated on a tin base material 51 to form a thermosetting resin layer (base coat) 52, and an image is formed thereon by a treatment liquid layer 53 and an ink layer 54. Next, a thermosetting resin (e.g., AX-10 series manufactured by T&K TOKA) is roller-coated to form a thermosetting resin layer (top coat) 55, and then heat-cured and dried to obtain a packaging material 50 for canned foods.

Example

[0194] Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In the following examples, unless otherwise specified, the operations were carried out at room temperature (25 °C). Also, unless otherwise specified, “%” and “parts” mean “mass %” and “parts by mass”, respectively.

[0195] [Preparation of treatment liquid A1] 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% of glycerin, 1% by mass of polyether-modified silicone (BYK3450), 0.1% by mass of a fungicide (Proxel GXL(S)), and ion-exchanged water (the remaining amount; the amount such that the total amount is 100% by mass) were added while stirring, and the resulting mixture was filtered through a 1-μm filter to obtain treatment liquid A1.

[0196] [Preparation of treatment liquids A2 to A15] Treatment liquids A2 to A15 were prepared in the same manner as in the preparation of treatment liquid A1, except that the type and amount of the polyvalent metal salt, polyether-modified silicone, solvent, and the amount of water were changed as shown in Table I below.

[0197] Note that each material in Table I is as follows. <Polyether-modified silicone> “BYK3450”: manufactured by BYK Chemie “TEGOWET245”: manufactured by Evonik “TEGOWET250”: manufactured by Evonik "TEGOWET260": manufactured by Evonik "TEGOWET270": manufactured by Evonik "TEGOWET280": manufactured by Evonik "BYK348": manufactured by BYK-Chemie

[0198] <Solvent> "DPG": Dipropylene glycol "PG": Propylene glycol "Gly": Glycerin "1,2-HDO": 1,2-Hexanediol

[0199] <Mildew preventive> "Proxel GXL(S)": 1,2-Benzisothiazolin-3-one

[0200] [Physical properties] For each of the obtained treatment liquids, the cloud point and the dynamic surface tension were measured by the following method. <Cloud point> 2 mL of the treatment liquid was placed in a glass container and heated, and the temperature at which the treatment liquid began to become turbid was defined as the cloud point.

[0201] <Dynamic surface tension> As described above, the dynamic surface tension at a surface lifetime of 15 ms of the treatment liquid at 25°C was measured by the maximum bubble pressure method. The dynamic surface tensiometer used for the measurement was a bubble pressure dynamic surface tensiometer (manufactured by KRUSS, model "BP100").

[0202] [Evaluation] <Storage stability> After heating treatment liquids A1 to A15 at 60°C for 2 weeks, as described above, the dynamic surface tension at a surface lifetime of 15 ms of the treatment liquid at 25°C was measured by the maximum bubble pressure method. The dynamic surface tensiometer used for the measurement was a bubble pressure dynamic surface tensiometer (manufactured by KRUSS, model "BP100"). 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. (Criteria) 〇: The difference between the dynamic surface tension of the treatment liquid before heating and that after heating is 2 mN / m or more. △: The difference between the dynamic surface tension of the treatment liquid before heating and that after heating is 1 mN / m or more and less than 2 mN / m. ×: The difference between the dynamic surface tension of the treatment liquid before heating and that after heating is less than 1 mN / m.

[0203]

Table 1

[0204] As shown in the above results, the treatment liquid with a cloud point of 40 °C or higher has excellent storage stability. In particular, it is recognized that the treatment liquid within the range of a cloud point of 50 °C or higher has excellent storage stability.

[0205] [Resin fine particle dispersions B1 to B7] Regarding each resin fine particle in the commercially available resin fine particle dispersions B1 to B7 described in Table II below, the aggregability and the glass transition temperature (Tg) were measured, and the measurement results are shown in Table II below.

[0206] <Aggregability> The aggregability was measured by the following method. First, in order to prepare a mixed solution in which the resin fine particles are 5% by mass and calcium acetate monohydrate is 0.15% by mass, a calcium acetate aqueous solution dissolved in ion-exchanged water so that calcium acetate monohydrate is 0.30% by mass and each resin fine particle dispersion B1 to B7 shown in Table II were used to prepare diluted solutions of the resin fine particle dispersions prepared with ion-exchanged water so that the solid content was 10% by mass, respectively. Next, 5 g of the calcium acetate aqueous solution was added to 5 g of the diluted solution of the resin fine particle dispersion while stirring to prepare 10 g of each mixed solution in which the solid content was 5% by mass and calcium acetate monohydrate was 0.15% by mass, respectively. Then, 10 g of each mixed solution was centrifuged at a centrifugal acceleration of 200 G and a centrifugal time of 10 minutes using a centrifuge CF16RX manufactured by Hitachi Koki Co., Ltd., and about 2 g of the supernatant was collected from the separated solution, respectively. Next, water was removed by heating each supernatant at 150 °C for 30 minutes, and the mass of the solid remaining after heating was measured. The mass of the obtained solid content was substituted into the following calculation formula to calculate the cohesiveness respectively. Formula: Cohesiveness = 1 - (mass of solid content (g) / (mass of collected supernatant (g) × 5%))

[0207] <Glass transition temperature> The glass transition temperature (Tg) of the resin fine particles was specified by reading the glass transition temperature Tg from the endothermic peak when the temperature was raised at a rate of 10 °C / min in the temperature range of -30 to 200 °C using a DSC (Differential Scanning Calorimeter).

[0208]

Table 2

[0209] [Preparation of Cyan Ink] <Preparation of Cyan Pigment Dispersion> Pigment (C.I. Pigment Blue 15:3) was added to 20% by mass, a pigment dispersant (an acrylic dispersant having a carboxy group neutralized with dimethylaminoethanol, "Joncryl 819" manufactured by BASF, acid value 75 mgKOH / g, solid content 20% by mass) was added to 6% by mass, propylene glycol was added to 22% by mass, a fungicide Proxel GXL(S) was added to 0.1% by mass, and ion-exchanged water (the remainder; in an amount such that the total amount was 100% by mass) was premixed. Thereafter, it was dispersed using a bead mill filled with 0.3 mm zirconia beads at a volume ratio of 50% to prepare a cyan pigment dispersion having a pigment content of 20% by mass. The average particle size of the pigment particles contained in this cyan pigment dispersion was 120 nm. The measurement of the average particle size of the pigment particles was performed using "Zetasizer Nano S90" manufactured by Malvern.

[0210] <Preparation of Cyan Ink C1>[[]] To 15% by mass of the above cyan pigment dispersion (3% by mass as solid content), the commercially available resin fine particle dispersion liquid B1 (the addition amount is adjusted so that the resin fine particles (solid content) become 5% by mass 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 fungicide Proxel GXL(S), and ion-exchanged water (the balance; in an amount such that the total amount is 100% by mass) were added while stirring, and the resulting mixture was filtered through a 1-μm filter to obtain cyan ink C1. There was no substantial compositional change before and after filtration.

[0211] <Preparation of Magenta Inks C2 to C8> In the preparation of the above 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 liquid were changed as shown in Table III below.

[0212] [Preparation of Magenta Ink] <Preparation of Magenta Pigment Dispersion> To 20% by mass of pigments (Pigment Red 122, Pigment Violet 19), 8% by mass of a pigment dispersant (an acrylic dispersant having a carboxy 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 fungicide Proxel GXL(S), and ion-exchanged water (the balance; in an amount such that the total amount is 100% by mass) were added and premixed. Thereafter, it was dispersed using a bead mill filled with 50% by volume of 0.3-mm zirconia beads to prepare a magenta pigment dispersion with a pigment content of 20% by mass. The average particle size of the pigment particles contained in this magenta pigment dispersion was 140 nm. The measurement of the average particle size of the pigment particles was performed using "Zetasizer Nano S90" manufactured by Malvern.

[0213] <Preparation of Magenta Ink D1> To 20% by mass of the above magenta pigment dispersion (4% by mass as solids), the commercially available resin fine particle dispersion B1 (the addition amount was adjusted so that the resin fine particles (solids) were 5% by mass 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 (Nisshin Chemical Industry Co., Ltd.), 0.10% by mass of fungicide Proxel GXL(S), and ion-exchanged water (the remainder; an amount such that the total amount was 100% by mass) were added while stirring, and the resulting mixture was filtered through a 1-μm filter to obtain magenta ink D1. There was no substantial compositional change before and after filtration.

[0214] <Preparation of Magenta Inks D2 to D8> 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 below.

[0215] [Physical Property Values] For each of the obtained inks, the dynamic surface tension was measured by the following method.

[0216] <Dynamic Surface Tension> As described above, the dynamic surface tension at a surface life of 15 ms of the ink at 25°C was measured by the maximum bubble pressure method. The dynamic surface tensiometer used for the measurement was a bubble pressure dynamic surface tensiometer (manufactured by KRUSS, model "BP100").

[0217]

Table 3

[0218] [Preparation of Tinplate Master] A white base coat (KC White 2, Toyochem Co., Ltd.) was applied to a tinplate master (SPTE, thickness 300 μm, Standard Test Piece Co., Ltd.) using a non-wire bar coater (OSP-10, OSG System Products Co., Ltd.).

[0219] [Printing Test 1] The prepared treatment liquids A1 to A10, inks C1 to C8, and D1 to D8 were printed as follows in the combinations shown in Table IV below. An independently driven inkjet head (360 dpi, discharge volume: 15 pL) manufactured by Konica Minolta was installed as shown in Fig. 4. By moving the head unit U in the scanning direction X and the recording medium (substrate) M in the conveyance direction Y (not shown), the treatment liquid and the ink were applied to the surface (image formation surface) of the recording medium M, and an image was formed as follows.

[0220] As the recording medium (non-absorbent substrate), an aluminum plate original (SPTE, thickness 300 μm, manufactured by Standard Test Piece Co., Ltd.) coated with the white base coat and a PET film (FE2001, thickness 50 μm, manufactured by Futamura Chemical Co., Ltd.) were prepared. From the front side in the scanning direction X, the treatment liquid prepared above (reference sign Pr in Fig. 4), magenta ink (reference sign I M ) and cyan ink (reference sign I C ) were respectively placed into the head module in this order. The moving speed of the head unit was set to 500 mm / sec. An image of 720 dpi × 720 dpi was formed as four images (180 dpi × 180 dpi) each divided into two in the scanning direction X and the conveyance direction Y, and the image was formed by printing one printing area four times. When passing the recording medium four times, the treatment liquid had a printing rate of 28%, that is, the application amount of the treatment liquid was 3.4 g / m 2 , and the cyan ink and the magenta ink were each set to a printing rate of 100%, that is, the application amount of two colors of ink was 24 g / m 2 (application amount of cyan ink 12 g / m 2 , application amount of magenta ink 12 g / m 2 ). A solid full-surface printed image was printed on the recording medium. On the aluminum plate original, the solid full-surface printed image was printed on the surface coated with the white base coat. Here, in the area where the processing liquid was applied, the drying rate of the processing liquid was made to be in the state described in Table IV, and ink was applied by an inkjet recording method. Specifically, a printing test was conducted in an environment of 25°C and 50% RH, and the time from when the processing liquid was applied until the ink was applied was set to 0.2 seconds. When the drying rate of the processing liquid was measured 0.2 seconds after the processing liquid was applied in the above environment of 25°C and 50% RH, the drying rate was 1% or less. Incidentally, the drying rate of the processing liquid was calculated by measuring the mass change amount of the processing liquid. After printing, it was put into a dryer set to the drying temperature (tinplate, PET) described in Table IV and dried for 10 minutes to obtain an image recording material. Here, it is assumed that the temperature of the area where the ink was applied is equal to the drying temperature. Incidentally, in Table IV, "≦1" represents "1% or less".

[0221] [Evaluation] <Tinplate adhesion> Among the image recording materials obtained above, for those printed on the tinplate original plate, using a drop weight impact tester (083, Allgood Co., Ltd.), a weight of 1000 g was dropped from a height of 100 cm onto the back side of the printed surface, deforming the tinplate original plate. The image adhesion of the printed surface of the deformed part was evaluated according to the following criteria. (Criteria) ◎: Even after the drop test, the printed surface shows no change, and the image does not peel off even when rubbed with a fingernail. 〇: Even after the drop test, the printed surface shows no change, but when rubbed with a fingernail, part of the image peels off. △: Even after the drop test, the printed surface shows no change, but when rubbed with a fingernail, the entire image peels off. ×: Image peeling is observed on the printed surface after the drop test.

[0222] <PET adhesion> Among the image recording materials obtained above, for those printed on PET, after sticking an adhesive tape to the printed surface and then peeling it off, the image adhesion was evaluated according to the following criteria. (Criteria) ◎: The image does not peel off even when the tape is peeled off. 〇: The image peels off with the tape by about one-fourth of the tape adhesion surface. △: The image peels off with the tape by about half of the tape adhesion surface. ×: The image peels off with the tape from the entire tape adhesion surface.

[0223]

Table 4

[0224] As shown in the above results, in Examples 1 to 19, it is recognized that excellent adhesion to the non-absorbent substrate and image rub resistance are obtained compared to Comparative Examples 1 to 8.

[0225] [Printing Test 2] Two independent drive heads of a piezo inkjet head (360 dpi, ejection volume 15 pL) manufactured by Konica Minolta were arranged so that the nozzles were staggered, and a head module of 720 dpi × 720 dpi was created and installed in a single-pass type printer illustrated in FIG. 1 so that the nozzle rows were orthogonal to the conveyance direction.

[0226] The inkjet head 11 of the head module installed in the treatment liquid application unit 10 was filled with the treatment liquid A1 or A2 obtained above, and the inkjet head 21 of the head module installed in the ink application unit 20 was filled with the inks C1 and D1 obtained above. In this way, a single-pass type inkjet recording apparatus capable of recording the treatment liquid and ink described in Table V was configured.

[0227] Using the above inkjet recording apparatus, a solid full-surface printed image of 720 dpi × 720 dpi, the same as in Printing Test 1, was recorded under the recording conditions described in Table V and evaluated using the same indexes as in Printing Test 1. As the base material F, an iron plate original plate (SPTE, thickness 300 μm, Standard Test Piece Co., Ltd.) coated with the white base coat and a PET film (FE2001, thickness 50 μm, manufactured by Futamura Chemical Co., Ltd.) were prepared. The conveyance speed during recording was set to 300 mm / sec. Here, in the area where the treatment liquid was applied, the drying rate of the treatment liquid was made to be in the state described in Table V, and ink was applied by an inkjet recording method. Specifically, a printing test was conducted in an environment of 25°C and 50% RH, and the treatment liquid layer C was dried at 25°C, 50°C, or 60°C for 5 seconds by the first drying unit 14, and then the ink was applied. After the treatment liquid layer C was dried at 25°C, 50°C, or 60°C for 5 seconds by the first drying unit 14, the drying rate of the treatment liquid was measured, and the drying rates were 10%, 20%, and 50% respectively. The drying rate of the treatment liquid was calculated by measuring the mass change amount of the treatment liquid. It was dried for 10 minutes by the first drying unit 23 set to the drying temperature described in Table V after printing to obtain an image recording material. Here, it is assumed that the temperature of the area where the ink was applied is equal to the drying temperature.

[0228]

Table 5

[0229] As shown in the above results, by setting the drying rate to 30% or less, preferably 10% or less, excellent adhesion to the non-absorbent base material can be obtained.

Industrial Applicability

[0230] The present invention can be used in an ink set and an inkjet recording method that provide excellent adhesion to a non-absorbent base material, excellent image rubbing resistance, and excellent storage stability.

Explanation of Signs

[0231] 1 Recording device 10 Treatment liquid application unit 11 Inkjet head 12 Treatment liquid droplet 14 First drying unit 20 Ink application unit 21 Inkjet head 22 Ink droplet 23 Second drying unit 30 Feeding roller 40 Take-up roller C Processing liquid layer F Substrate P Image recording material R Ink layer 50 Packaging material for canned foods 51 Tin substrate 52 Thermosetting resin layer (base coat) 53 Processing liquid layer 54 Ink layer 55 Thermosetting resin layer (top coat) U Head unit X Scanning direction M Recording medium (substrate)

Claims

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

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

3. The treatment liquid contains the water-soluble solvent having an SP value of 24 (J / cm ３ ) １／２ in the range of 5 to 40% by mass, and the ink set according to claim 1 or claim 2.

4. An inkjet recording method for recording an image using the ink set according to any one of claims 1 to 3, comprising a step of applying the treatment liquid to a recording area of a 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 area to which the ink has been applied at a heating temperature equal to or higher than the cloud point and equal to or higher than the glass transition temperature.

5. The inkjet recording method according to claim 4, further comprising a step of applying the ink to the area 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 claim 5, wherein the amount of the resin fine particles per unit area is 80 times or less the amount of the polyether-modified silicone.

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