Ink set and inkjet recording method

Abstract

The ink set of the present invention is an ink set comprising an ink and a treatment liquid, wherein the ink comprises a pigment, resin particles, a water-soluble solvent having a boiling point in the range of 150 to 250° C., and a surfactant; the treatment liquid comprises a polyvalent metal salt, a water-soluble solvent having a boiling point in the range of 150 to 250° C., and a surfactant; the static surface tension of the ink at 25° C. is higher than the static surface tension of the treatment liquid by at least 5 mN / m; the dynamic surface tension of the ink at a surface life of 15 ms at 25° C. is higher than the dynamic surface tension of the treatment liquid at a surface life of 15 ms by at least 5 mN / m; the dynamic surface tension of the ink at a surface life of 15 ms is within a range of 35 to 45 mN / m; and the dynamic surface tension of the treatment liquid at a surface life of 15 ms is within a range of 25 to 35 mN / m.

Description

Technical Field

[0001] The present invention relates to an ink set and an inkjet recording method, and more particularly to an ink set which suppresses image defects, has high image quality, and has excellent adhesion to a substrate. Background Art

[0002] Inkjet recording allows for simple and inexpensive image production, making it applicable to a wide range of printing applications, including photographs, various types of printing, signage, and specialty printing such as color filters. In particular, inkjet recording enables digital printing without the use of plates, making it particularly suitable for applications requiring the formation of multiple images in small quantities.

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

[0004] While two-liquid inkjet recording methods can prevent ink bleeding, improperly controlling the time between the treatment liquid and the ink can lead to excessive ink aggregation and reduced image gloss. Therefore, a technique has been disclosed for improving printing stability and recording productivity on non-absorbent substrates by controlling the amount of treatment liquid applied and shortening the time between the treatment liquid and the ink. (For example, see Patent Document 1).

[0005] However, if the static and dynamic surface tensions of the processing liquid and ink are not properly controlled, image defects such as bleeding of hollow text or fine lines, beading, and spots may occur depending on the combination of the processing liquid and ink, making it difficult to achieve high image quality.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 2016-221943 Summary of the Invention

[0009] Technical problem to be solved by the invention

[0010] The present invention has been made in view of the above-mentioned problems and circumstances, and aims to provide an ink set and an inkjet recording set that suppress image defects, have high image quality, and have excellent adhesion to a substrate.

[0011] Means of solving technical problems

[0012] In order to solve the above-mentioned technical problems, the present inventors conducted research on the causes of the above-mentioned problems and discovered that by controlling the static surface tension and dynamic surface tension of the treatment liquid and ink within specific ranges, an ink set and inkjet recording method capable of achieving high image quality can be provided, thereby completing the present invention.

[0013] That is, the above-mentioned problem of the present invention is solved by the following means.

[0014] 1. An ink set comprising ink and a treatment liquid, wherein:

[0015] The ink contains a pigment, resin particles, a water-soluble solvent with a boiling point within the range of 150 to 250° C., and a surfactant.

[0016] The treatment liquid comprises a polyvalent metal salt, a water-soluble solvent with a boiling point in the range of 150 to 250° C., and a surfactant.

[0017] At 25° C., the static surface tension of the ink is higher than the static surface tension of the treatment liquid by more than 5 mN / m,

[0018] At 25° C., the dynamic surface tension of the ink at a surface life of 15 ms is higher than the dynamic surface tension of the treatment liquid at a surface life of 15 ms by more than 5 mN / m.

[0019] The dynamic surface tension of the ink at a surface life of 15 ms is in the range of 35 to 45 mN / m, and

[0020] The dynamic surface tension of the treatment liquid when the surface life is 15 ms is in the range of 25 to 35 mN / m.

[0021] 2. The ink set according to item 1, wherein:

[0022] The pigment is dispersed by an anionic polymer dispersant.

[0023] 3. The ink set according to item 1 or 2, wherein:

[0024] The ink contains the resin fine particles having an agglomeration property of 0.2 or less with a 0.15% by mass aqueous solution of calcium acetate monohydrate in an amount within a range of 3 to 15% by mass.

[0025] 4. The ink set according to any one of items 1 to 3, wherein

[0026] The resin fine particles include a water-dispersible polyester resin having a sulfonic acid group.

[0027] 5. The ink set according to any one of items 1 to 4, wherein

[0028] At 25° C., the dynamic surface tension of the treatment liquid in an undried state at a surface life of 15 ms is defined as A, and the dynamic surface tension of the treatment liquid at a surface life of 15 ms when the drying rate is 30% is defined as B, and the following formula (I) is satisfied:

[0029] Formula (I): (BA)≤5mN / m.

[0030] 6. The ink set according to any one of items 1 to 5, wherein

[0031] The treatment liquid contains a surfactant that is not contained in the ink.

[0032] 7. An inkjet recording method for recording an image using the ink set according to any one of items 1 to 6, wherein:

[0033] After the treatment liquid is applied to the substrate, the ink is applied to the area where the treatment liquid is applied while the substrate is wetted with the treatment liquid without undergoing a heating and drying step.

[0034] 8. The inkjet recording method according to item 7, wherein:

[0035] The ink is applied to the region to which the treatment liquid is applied in a state where the drying rate of the treatment liquid is 30% or less.

[0036] 9. The inkjet recording method according to item 7 or 8, wherein

[0037] After the treatment liquid is applied to the substrate, the ink is applied to the area where the treatment liquid has been applied within 10 seconds.

[0038] 10. The recording method according to any one of items 7 to 9, wherein

[0039] The amount of the ink applied per unit area is in a range of 2 to 25 times the amount of the treatment liquid applied.

[0040] Effects of the Invention

[0041] According to the above means of the present invention, it is possible to provide an ink set and an inkjet recording set that suppress image defects and have excellent adhesion to a substrate.

[0042] The mechanism of expression and action of the effects of the present invention are not clear, but are presumed as follows.

[0043] In the wet-on-wet recording method in which ink is applied while the processing liquid is kept moist, the processing liquid needs to be removed at intervals. However, since the processing liquid needs to be wetted and spread instantly to become uniform while reducing the printing rate, the lower the dynamic surface tension of the processing liquid, the better. On the other hand, if the dynamic surface tension of the ink is too low, the hollow text will collapse, so it is preferably not too low.

[0044] Therefore, in the present invention, first, as a structure capable of recording an image while ensuring adhesion to the substrate, the following structure is adopted: the ink contains a pigment, resin particles, a water-soluble solvent with a boiling point in the range of 150 to 250°C, and a surfactant. In addition, in order to thicken and coagulate the ink to achieve high image quality, the processing liquid contains a polyvalent metal salt, a water-soluble solvent with a boiling point in the range of 150 to 250°C, and a surfactant.

[0045] Furthermore, the relationship between the static and dynamic surface tensions of the treatment liquid and ink is set within the aforementioned range. Specifically, by setting the static and dynamic surface tensions of the treatment liquid lower than those of the ink, the ink appropriately diffuses in the treatment liquid while simultaneously agglomerating and thickening. This prevents bleeding of hollow text and fine lines, and suppresses image defects such as beading and mottling, ultimately achieving high image quality.

[0046] Furthermore, by setting the dynamic surface tensions of the treatment liquid and the ink within the above ranges, high wettability to the substrate can be ensured, and high injection stability and storage stability can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 FIG1 is a schematic diagram showing an example of a recording apparatus preferred according to the present invention.

[0048] Figure 2 It is a cross-sectional view showing a schematic structure of the image recorded material of the present invention.

[0049] Figure 3 This is a cross-sectional view of packaging material for canned food.

[0050] Figure 4 Schematic diagram showing an inkjet head used in Examples.

[0051] Figure 5 This is a graph showing the dynamic surface tension of ink set 1 in Examples.

[0052] Figure 6 This is a graph showing the dynamic surface tension of the ink set 44 in the example. DETAILED DESCRIPTION

[0053] The ink set of the present invention is an ink set comprising an ink and a treatment liquid, wherein the ink comprises a pigment, resin particles, a water-soluble solvent having a boiling point in the range of 150 to 250° C., and a surfactant; the treatment liquid comprises a polyvalent metal salt, a water-soluble solvent having a boiling point in the range of 150 to 250° C., and a surfactant; the static surface tension of the ink at 25° C. is higher than the static surface tension of the treatment liquid by at least 5 mN / m; the dynamic surface tension of the ink at a surface life of 15 ms at 25° C. is higher than the dynamic surface tension of the treatment liquid at a surface life of 15 ms by at least 5 mN / m; the dynamic surface tension of the ink at a surface life of 15 ms is within a range of 35 to 45 mN / m; and the dynamic surface tension of the treatment liquid at a surface life of 15 ms is within a range of 25 to 35 mN / m.

[0054] This feature is a common or corresponding technical feature in the following embodiments.

[0055] As an embodiment of the present invention, the pigment is preferably dispersed in an anionic polymer dispersant from the viewpoint of excellent dispersibility and proper reaction with the treatment liquid to be fixed.

[0056] The ink preferably contains 3 to 15% by mass of the resin fine particles having a cohesiveness of 0.2 or less with a 0.15% by mass aqueous solution of calcium acetate monohydrate. The use of resin fine particles with low cohesiveness ensures high wettability to the substrate while achieving high injection stability, higher image quality, and excellent substrate adhesion.

[0057] From the viewpoint of achieving high adhesion to a substrate, the resin fine particles preferably contain a water-dispersible polyester resin having a sulfonic acid group.

[0058] Furthermore, at 25° C., the dynamic surface tension of the treatment liquid in an undried state at a surface life of 15 ms is defined as A, and the dynamic surface tension of the treatment liquid at a surface life of 15 ms when the treatment liquid is dried and the drying rate of the treatment liquid is 30% is defined as B. It is preferable that the following formula (I) is satisfied:

[0059] Formula (I): (BA)≤5mN / m.

[0060] In the wet-on-wet recording method, even if the processing liquid dries to a certain extent, the dynamic surface tension does not change, thereby improving the robustness with respect to the temperature and humidity conditions during recording.

[0061] The treatment liquid preferably contains a surfactant that is not contained in the ink. In this way, by adding a surfactant that destabilizes the dispersion stability of the ink to the treatment liquid, the cohesion can be further improved.

[0062] The inkjet recording method of the present invention uses the ink set to record an image. After applying the treatment liquid to a substrate, the ink is applied to the area wetted with the treatment liquid without undergoing a heating and drying step. By employing a wet-on-wet recording method, the ink and treatment liquid are mixed, ensuring high wettability to the substrate and achieving high injection stability, resulting in high image quality and excellent substrate adhesion.

[0063] In particular, it is preferable to apply the ink to the region to which the treatment liquid has been applied when the drying rate of the treatment liquid is 30% or less, from the viewpoint of properly mixing the ink and the treatment liquid and more significantly exhibiting the effects of the present invention.

[0064] From the perspective of suppressing the penetration of the treatment liquid into the absorptive substrate and the shrinkage of the treatment liquid in the non-absorbent substrate, thereby achieving higher image quality, it is preferred to apply the ink to the area to which the treatment liquid has been applied within 10 seconds after the treatment liquid has been applied to the substrate.

[0065] From the viewpoint of achieving higher image quality per unit area, the amount of ink applied is preferably within a range of 2 to 25 times the amount of treatment liquid applied.

[0066] Hereinafter, the present invention and its constituent elements, as well as methods and modes for carrying out the present invention will be described in detail. It should be noted that in this application, "to" is used to mean that the numerical values ​​described before and after it are included as the lower limit and the upper limit.

[0067] [Overview of the Ink Set of the Present Invention]

[0068] The ink set of the present invention comprises an ink and a treatment liquid, wherein the ink contains a pigment, resin fine particles, a water-soluble solvent with a boiling point in the range of 150-250°C, and a surfactant, and the treatment liquid contains a polyvalent metal salt, a water-soluble solvent with a boiling point in the range of 150-250°C, and a surfactant. Furthermore, at 25°C, the static surface tension of the ink is at least 5 mN / m higher than the static surface tension of the treatment liquid, and at 25°C, the dynamic surface tension of the ink at a surface life of 15 ms is at least 5 mN / m higher than the dynamic surface tension of the treatment liquid at a surface life of 15 ms. The dynamic surface tension of the ink at a surface life of 15 ms is 35 mN / m to 45 mN / m, and the dynamic surface tension of the treatment liquid at a surface life of 15 ms is 25 mN / m to 35 mN / m.

[0069] The "treatment liquid" and "ink" referred to in the present invention refer to a "treatment liquid" (also referred to as a "pretreatment liquid" or "primer") and an "ink" (also referred to as a "water-based ink" or "water-based ink") that use at least "water" as a solvent. In either case, at least 60% by mass of the solvent used is water.

[0070] <Static Surface Tension>

[0071] In the present invention, "static surface tension" refers to the surface tension when the components of the ink or treatment liquid on the liquid surface diffuse and approach an equilibrium state over the life of the surface.

[0072] The static surface tension of ink or treatment liquid can be measured using an automatic surface tensiometer (manufactured by Kyowa Interface Science Co., Ltd., model "CBVP-Z") using a platinum plate. Unless otherwise specified, the static surface tension in this specification is measured at 25°C.

[0073] The static surface tension of the ink set of the present invention is higher than the static surface tension of the treatment liquid at 25° C. by at least 5 mN / m, preferably by 6 to 12 mN / m.

[0074] Specifically, at 25° C., the static surface tension of the ink is preferably in the range of 25 to 35 mN / m, and the static surface tension of the treatment liquid is preferably in the range of 20 to 30 mN / m.

[0075] In addition, when there are multiple types of inks, the difference in static surface tension between the ink having the lowest static surface tension and the treatment liquid only needs to be within the above range.

[0076] <Dynamic Surface Tension>

[0077] In the present invention, "dynamic surface tension" refers to the surface tension when the liquid surface is in a non-equilibrium state immediately after the formation of the liquid surface (gas-liquid interface), and is a value measured at 25°C by the maximum bubble pressure method.

[0078] In addition, "surface life" refers to the time elapsed from the formation of the liquid surface, that is, the life of the bubbles generated in the maximum bubble pressure method. It is also called bubble life and refers to the time from the moment a new interface is generated within the probe tip of the dynamic surface tensiometer to the time when the maximum bubble pressure is reached.

[0079] The dynamic surface tension of the treatment liquid or ink can be measured using a dynamic surface tensiometer. Examples of the dynamic surface tensiometer include a bubble pressure dynamic surface tensiometer (manufactured by KRUSS, Model "BP100").

[0080] Unless otherwise specified, the dynamic surface tension in this specification is the dynamic surface tension measured at 25° C. and 15 ms using the maximum bubble pressure method.

[0081] The ink set of the present invention has a dynamic surface tension (also referred to as "dynamic surface tension A") at 25°C when the ink has a surface life of 15 ms that is at least 5 mN / m higher than the dynamic surface tension of the treatment liquid when the ink has a surface life of 15 ms. Preferably, the dynamic surface tension is within the range of 7 to 15 mN / m higher.

[0082] When there are multiple inks, the difference in dynamic surface tension between the ink with the lowest dynamic surface tension and the treatment liquid may be within the above range.

[0083] Furthermore, the dynamic surface tension of the treatment liquid at a surface life of 15 ms is in the range of 25 to 35 mN / m, preferably in the range of 27 to 33 mN / m.

[0084] Furthermore, the dynamic surface tension of the ink at a surface life of 15 ms is within a range of 35 to 45 mN / m, preferably within a range of 37 to 43 mN / m.

[0085] In order to adjust the static surface tension and the dynamic surface tension of the treatment liquid to be within the above ranges, the type and content of the surfactant, the type and content of the water-soluble solvent, the type and content of the coagulant, etc. can be controlled.

[0086] Specifically, as the surfactant contained in the treatment liquid, it is preferred to use various polyether-modified polysiloxanes and / or acetylene glycol surfactants, and to make their content within the range of 0.1 to 2.0 mass %. In addition, as the water-soluble solvent, it is preferred to use a surfactant having an SP value of 24 (J / cm 3 ) 1 / 2 The content of the water-soluble solvent having a boiling point in the range of 150° C. to 250° C. is in the range of 5 to 40% by mass.

[0087] In order to make the static surface tension and dynamic surface tension of the ink fall within the above ranges, the type and content of the surfactant, the type and content of the water-soluble solvent, the type and content of the pigment dispersant, the type and content of the resin particles, the type and content of the additives, etc. can be controlled.

[0088] Specifically, as the surfactant contained in the ink, it is preferred to use various polyether-modified polysiloxanes and / or acetylene glycol surfactants, with the content being in the range of 0.1 to 2.0 mass %. As the water-soluble solvent, a surfactant having an SP value of 24 (J / cm 3 ) 1 / 2The content of a water-soluble solvent having a boiling point of 150°C to 250°C is preferably 5 to 40% by mass. Furthermore, various low molecular weight dispersants, nonionic polymer dispersants, anionic polymer dispersants, or resin-coated pigment dispersions are preferably used as pigment dispersants. Furthermore, the type of resin particles is preferably polyester resins, acrylic resins, styrene acrylic resins, urethane resins, etc., with the content being 3 to 15% by mass.

[0089] <Dynamic surface tension after drying to 30%>

[0090] Furthermore, the ink set of the present invention preferably satisfies the following formula (I) at 25° C., where A is the dynamic surface tension of the treatment liquid in an undried state at a surface life of 15 ms, and B is the dynamic surface tension of the treatment liquid at a surface life of 15 ms when the drying rate of the treatment liquid is 30%.

[0091] Formula (I): (BA) ≤ 5mN / m

[0092] By satisfying Formula (I) in this way, in the wet-on-wet recording method, even if the processing liquid dries to a certain extent, the change in dynamic surface tension can be reduced, thereby improving the robustness to the temperature and humidity conditions during recording.

[0093] Here, "dynamic surface tension A" refers to the dynamic surface tension of the treatment liquid before the treatment liquid is dried as described below, that is, in an undried (state) when the surface life at 25°C is 15 ms, and is the value measured at 25°C using the maximum bubble pressure method described above.

[0094] Furthermore, "dynamic surface tension B" refers to the dynamic surface tension of the treatment liquid at a surface life of 15 ms, when the treatment liquid is dried to a 30% drying rate. Specifically, 100 g of the treatment liquid is weighed in a shallow container and dried under reduced pressure at 25°C until the liquid mass reaches 70 g. The dynamic surface tension at this point is measured using the maximum bubble pressure method described above, and this value is referred to as the dynamic surface tension B after 30% drying.

[0095] The difference "(BA)" was calculated from the dynamic surface tension B after 30% drying thus measured and the dynamic surface tension A.

[0096] [Processing liquid]

[0097] When recording an image on a substrate by inkjet printing, the treatment liquid of the present invention can accelerate ink image formation, improve the physical properties of the treatment liquid layer and the ink layer, and enhance image quality by causing the ink to aggregate or thicken.

[0098] The treatment liquid of the present invention contains at least a polyvalent metal salt, a water-soluble solvent having a boiling point within a range of 150 to 250° C., and a surfactant. The treatment liquid may also contain water.

[0099] <Polyvalent Metal Salt>

[0100] The treatment liquid of the present invention contains a material that generates aggregates when in contact with ink, that is, a coagulant that is a polyvalent metal salt. This increases the interaction with the ink and enables further fixing of ink dots.

[0101] The polyvalent metal salt can aggregate anionic components (usually colorants or pigments) in the ink described later by salting out.

[0102] As the polyvalent metal salt, a salt of a metal having a valence of 2 or more can be used. The type of metal (cation) constituting the polyvalent metal salt is not particularly limited, and examples thereof include Ca 2+ 、Cu 2+ 、Ni 2+ Mg 2+ 、Zn 2+ 、Ba 2+ Other divalent metal ions, Al 3+ 、Fe 3+ Cr 3+ 、Y 3+ Other trivalent metal ions, Zr 4+ etc. tetravalent metal ions.

[0103] The type of salt constituting the polyvalent metal salt is not particularly limited, and for example, known salts such as carbonates, sulfates, nitrates, hydrochlorides, organic acid salts, borates, and phosphates can be used. Specific examples of particularly preferred polyvalent metal salts include calcium salts or magnesium salts of carboxylic acids such as calcium chloride, magnesium chloride, calcium nitrate, magnesium nitrate, magnesium acetate, calcium acetate, magnesium lactate, and calcium pantothenate.

[0104] <Organic Acid>

[0105] In addition to the polyvalent metal salt, the treatment liquid of the present invention may further contain an organic acid as a coagulant. The organic acid can cause anionic components in the ink to coagulate by varying the pH. Monocarboxylic acids are preferred as organic acids because they do not weaken the cohesive force of the polyvalent metal salt.

[0106] The organic acid can aggregate a pigment that may be included in the ink described later.

[0107] Examples of the organic acid include formic acid, acetic acid, propionic acid, isobutyric acid, and benzoic acid.

[0108] It is preferred that the organic acid be one that is not completely neutralized by an alkali. Neutralization by an alkali means that the acidic groups of these acids form ionic bonds with other positively charged elements or compounds (e.g., inorganic compounds such as metals). In addition, not being completely neutralized means that the acidic groups of the organic acid contain acidic groups that do not form the ionic bonds.

[0109] In addition, by using an organic acid, the storage stability of the treatment liquid is easily maintained, and sticking is less likely to occur after the treatment liquid is applied and dried. From this viewpoint, preferred organic acids include formic acid, acetic acid, propionic acid, benzoic acid, and the like.

[0110] <Inorganic acid>

[0111] The treatment liquid of the present invention may further contain an inorganic acid as a coagulant in addition to the polyvalent metal salt. The inorganic acid can coagulant the anionic components in the ink by changing the pH.

[0112] The inorganic acid can aggregate the pigment that may be included in the ink described below. Examples of the inorganic acid include hydrochloric acid, nitric acid, sulfuric acid, and aminosulfonic acid.

[0113] The content of the polyvalent metal salt is preferably in the range of 0.5 to 20 mass%, more preferably in the range of 1 to 10 mass%, relative to the total mass (100 mass%) of the treatment liquid. This allows the anionic components in the ink to be effectively aggregated, which is preferable from the perspective of balancing image quality and hot water resistance.

[0114] When an organic acid is contained, the content of the organic acid is preferably in the range of 0.1 to 10 mass %, more preferably in the range of 1 to 3 mass %, relative to 100 mass % of the total mass of the treatment liquid.

[0115] When an inorganic acid is contained, the content of the inorganic acid is preferably in the range of 0.1 to 10 mass %, more preferably in the range of 1 to 3 mass %, relative to 100 mass % of the total mass of the treatment liquid.

[0116] The content of the polyvalent metal salt or organic acid in the aqueous solution can be measured by known methods. For example, in the case of a polyvalent metal salt, the content can be measured by ICP emission analysis, and in the case of an organic acid, the content can be measured by high performance liquid chromatography (HPLC).

[0117] When an organic acid is used, the amount of the organic acid added is preferably such that the pH of the treatment liquid is adjusted to an amount equal to or less than the neutralization equivalent of the anionic components contained in the ink. Furthermore, when the anionic component is a compound having a carboxyl group, the first dissociation constant of the organic acid is preferably 3.5 or less to further reduce image bleeding.

[0118] <Water-soluble solvent>

[0119] The water-soluble solvent contained in the treatment liquid of the present invention is a water-soluble solvent having a boiling point within a range of 150 to 250°C.

[0120] Examples of such water-soluble solvents include alcohols, polyols, amines, amides, glycol ethers, and 1,2-alkanediols having 4 or more carbon atoms.

[0121] In addition, it is preferred to use an SP value of 24 (J / cm 3 ) 1 / 2 The above water-soluble solvents.

[0122] By using an SP value of 24 (J / cm 3 ) 1 / 2 The above water-soluble solvents lower the turbidity point of the treatment liquid, thereby allowing the treatment liquid to be heated above the turbidity point during the ink drying process, thereby achieving an image with good adhesion, particularly to non-absorbent substrates.

[0123] It should be noted that in the present invention, the SP value is called the solubility parameter. The SP value in the present invention is a value calculated by the Fedors method. It is calculated from the molar heat of vaporization of the water-soluble solvent and the molar volume of the water-soluble solvent at 25°C. It should be noted that the unit of the SP value is usually cal. When converted to the SI unit system, (cal / cm 3 ) 1 / 2 =2.046×10 3 (J / m 3 ) 1 / 2 In the following description, the unit of SP value is sometimes omitted. SP value is expressed in (J / cm 3 ) 1 / 2 The value expressed in the unit of .

[0124] The SP value is 24 (J / cm 3 ) 1 / 2 As the water-soluble solvent having the above-mentioned boiling point of 150° C. to 250° C., for example, polyols having 2 to 8 carbon atoms and polyalkylene glycols can be mentioned.

[0125] Examples of the polyols having 2 to 8 carbon atoms include 1,2-ethanediol (SP value: 30.3, boiling point: 197°C), 1,2-propylene glycol (SP value: 28.0, boiling point 188°C), 1,3-propylene glycol (SP value: 32.9, boiling point 213°C), 1,2-butanediol (SP value: 26.1, boiling point 192°C), 1,3-butanediol (SP value: 30.3, boiling point: 207°C), 1,4-butanediol (SP value: 30.7, boiling point 230°C), 2,3-butanediol (SP value: 32.9, boiling point 213°C), value: 29.9, boiling point: 177°C), 2-methyl-1,3-propanediol (SP value: 30.3, boiling point 214°C), 1,2-pentanediol (SP value: 25.0, boiling point: 210°C), 1,5-pentanediol (SP value: 29.0, boiling point: 242°C), 1,2-hexanediol (SP value: 24.1, boiling point: 223°C), 1,6-hexanediol (SP value: 27.7, boiling point: 249°C), 2-methylpentane-2,4-diol (SP value: 26.8, boiling point 197°C), etc.

[0126] Examples of the polyalkylene glycols include diethylene glycol (SP value: 30.6, boiling point 244° C.) and dipropylene glycol (SP value: 27.2, boiling point 230° C.).

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

[0128] The ink may contain at least one of the water-soluble solvents having a boiling point of 150° C. to 250° C., and may also contain alcohols other than the above-mentioned ones, polyols, amines, amides, glycol ethers, and 1,2-alkanediols having 4 or more carbon atoms.

[0129] Examples of solvents other than water-soluble solvents having a boiling point of 150°C to 250°C include glycerin (SP value: 33.5, boiling point 290°C), trimethylolpropane (SP value: 32.5, boiling point: 295°C), triethylene glycol (SP value: 27.8, boiling point 287°C), and tetraethylene glycol (SP value: 26.1, boiling point: 275°C).

[0130] The total content of the water-soluble solvent is preferably in the range of 5 to 40 mass %, more preferably in the range of 10 to 40 mass %, relative to 100 mass % of the total mass of the treatment liquid.

[0131] <Surfactant>

[0132] The surfactant contained in the treatment liquid of the present invention can improve the injection stability of the treatment liquid from the nozzle and control the spread of the droplet landed on the recording medium (enlargement of the spot diameter).

[0133] The surfactant that can be used in the treatment liquid of the present invention is not particularly limited. When anionic compounds are included in other components of the ink, the ionicity of the surfactant is preferably anionic, nonionic, or betaine.

[0134] In the present invention, it is preferred to use fluorine-based or polysiloxane-based surfactants with high static surface tension reducing ability, anionic surfactants such as dioctyl sulfosuccinate with high dynamic surface tension reducing ability, relatively low molecular weight polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, acetylenic diols, Pluronic surfactants (Pluronic is a registered trademark), and nonionic surfactants such as sorbitan derivatives. It is also preferred to use a fluorine-based or polysiloxane-based surfactant in combination with a surfactant with high dynamic surface tension reducing ability.

[0135] By adding polysiloxane or fluorine-based surfactants as surfactants, ink mixing (beading) can be further suppressed for recording media with low ink absorption capacity, such as recording media composed of various hydrophobic resins represented by vinyl chloride sheets, and printing paper, which is preferred for obtaining high-quality printed images.

[0136] The polysiloxane surfactant is preferably a polyether-modified polysiloxane, and examples thereof include siloxanes having an alkylene oxide group in a side chain and / or at both ends of a polydimethylsiloxane chain.

[0137] Specific examples include BYK-331, BYK-333, BYK-345, BYK-3450, BYK-3451, BYK-3455, BYK-346, BYK-347, BYK-348, and BYK-349 manufactured by BYK-Chemie, and TEGOWET KL245, TEGOWET 250, TEGOWET 260, and TEGOWET 270 manufactured by Evonik. TEGOWet280, KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-640, KF-642, KF-643, KF-644, KF-945, KF-6011, KF-6012, KF-6015, KF-6017, KF-6020, KF-6204, X-22-4515, etc. manufactured by Shin-Etsu Chemical Co., Ltd.

[0138] As the polyether-modified polysiloxane, trisiloxane having an alkylene oxide group in the side chain and / or at both ends of the polydimethylsiloxane chain is particularly preferred. By using trisiloxane, the dynamic surface tension of the processing liquid can be effectively reduced, and an image with good adhesion to the substrate can be obtained.

[0139] As trisiloxane, a structure represented by the following general formula (1) is preferred.

[0140] [Chemical Formula 1]

[0141] General formula (1)

[0142]

[0143] In the general formula (1), "EO" represents a repeating unit structure of polyethylene oxide, i.e., a structure formed by ring-opening ethylene oxide, which is a three-membered cyclic ether. Furthermore, "PO" represents a repeating unit structure of polypropylene oxide, i.e., a structure formed by ring-opening propylene oxide, which is a three-membered cyclic ether. The phrase "[EO]m and [PO]n may be in any order" means that, in the compound molecule represented by the general formula (1), the order of the bonding positions relative to the siloxane backbone serving as the parent structure may be appropriately changed.

[0144] In the general formula (1), X is preferably an alkylene group having 3 carbon atoms (ie, a propylene group).

[0145] In the general formula (1), m is preferably an integer of 5 to 20, and n is preferably an integer of 0 to 6.

[0146] Specific examples of the polysiloxane surfactant having a structure represented by the general formula (1) are S-1 to S-8 shown below, but the present invention is not limited to these.

[0147] (S-1): In the general formula (1), R = methyl, X = alkylene with 3 carbon atoms, m = 9, n = 0

[0148] (S-2): In the general formula (1), R = butyl, X = alkylene with 3 carbon atoms, m = 25, n = 6

[0149] (S-3): In the general formula (1), R = hydrogen atom, X = alkylene group with 3 carbon atoms, m = 3, n = 0

[0150] (S-4): In the general formula (1), R = hydrogen atom, X = alkylene group with 3 carbon atoms, m = 33, n = 0

[0151] (S-5): In the general formula (1), R = hydrogen atom, X = alkylene group with 3 carbon atoms, m = 22, n = 16

[0152] (S-6): In the general formula (1), R = hydrogen atom, X = alkylene group with 3 carbon atoms, m = 9, n = 0

[0153] (S-7): In the general formula (1), R = hydrogen atom, X = alkylene group with 3 carbon atoms, m = 12, n = 3

[0154] (S-8): In the general formula (1), R = hydrogen atom, X = alkylene group with 3 carbon atoms, m = 1, n = 0

[0155] 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.

[0156] The content of the polyether-modified polysiloxane is preferably in the range of 0.5 to 2 mass %, more preferably in the range of 0.5 to 1.5 mass %, relative to 100 mass % of the total mass of the treatment liquid.

[0157] The fluorine-based surfactant is a surfactant in which a portion or all of the hydrogen atoms bonded to the carbon atoms of the hydrophobic groups of conventional surfactants are replaced with fluorine atoms. Among these, those having a perfluoroalkyl group in the molecule are preferred.

[0158] Among the fluorine-based surfactants, some are sold under the following trade names: Megafac F manufactured by Dainippon Ink & Chemicals, Surflon manufactured by Asahi Glass, Fluorad FC manufactured by Minnesota Mining and Manufacturing, Monflor manufactured by Imperial Chemical Industrie, Zonyls manufactured by EI du Pont de Nemours & Company, and Licowet VPF manufactured by Farbwerke Hoechst.

[0159] In particular, the treatment liquid of the present invention preferably contains a surfactant that is not contained in the ink described later. The following two modes are exemplified.

[0160] When the surfactant contained in the ink is surfactant S1,

[0161] (i) The surfactant contained in the treatment liquid is preferably a surfactant S2 different from the surfactant S1 contained in the ink.

[0162] (ii) The surfactant contained in the treatment liquid preferably contains the surfactant S2 in addition to the surfactant S1.

[0163] As a specifically preferred combination of surfactants, polyether-modified polysiloxane is preferred as the surfactant contained in the treatment liquid, and acetylene glycol surfactants and polyether-modified polysiloxane are preferred as the surfactant contained in the ink.

[0164] As described above, by adding a surfactant that is not contained in the ink (that is, a surfactant that destabilizes the dispersion stability of the ink) to the treatment liquid, the cohesiveness can be further improved.

[0165] The content of the surfactant in the treatment liquid is not particularly limited, but is preferably within a range of 0.1 to 5.0% by mass of the total mass of the treatment liquid.

[0166] <Water>

[0167] The treatment liquid of the present invention may contain water. The water that can be used is not particularly limited and may be ion-exchanged water, distilled water, or pure water.

[0168] The treatment liquid may contain other components as appropriate, such as a cross-linking agent, a mildew preventer, a fungicide, etc., within a range that does not impair the effects of the present invention.

[0169] In addition, the ultraviolet absorbers described in, for example, Japanese Patent Application Laid-Open Nos. 57-74193, 57-87988, and 62-261476, Japanese Patent Application Laid-Open Nos. 57-74192, 57-87989, 60-72785, 61-146591, 1-95091, and 3-133 Various well-known additives such as anti-fading agents recorded in Japanese Patent Gazette No. 76, various anionic, cationic or nonionic surfactants, fluorescent brighteners recorded in Japanese Patent Gazette No. 59-42993, Japanese Patent Gazette No. 59-52689, Japanese Patent Gazette No. 62-280069, Japanese Patent Gazette No. 61-242871 and Japanese Patent Gazette No. 4-219266, defoaming agents, lubricants such as diethylene glycol, preservatives, thickeners, antistatic agents, etc.

[0170] The treatment liquid layer is preferably prepared by directly applying the treatment liquid of the present invention as a coating liquid onto a substrate and drying the coating liquid. The additives preferably used in the treatment liquid are preferably fully dissolved before use as a coating liquid.

[0171] As a coating method for the treatment liquid, inkjet coating, roll coating, rod coating, air knife coating, spray coating, curtain coating, or extrusion coating using a hopper as described in US Pat. No. 2,681,294 is preferably used, and inkjet coating is particularly preferred.

[0172] [Ink]

[0173] The ink of the present invention contains at least a pigment, resin fine particles, a water-soluble solvent having a boiling point within a range of 150 to 250° C., and a surfactant. It may also contain water.

[0174] <Pigment>

[0175] As the pigment used in the ink of the present invention, anionic dispersible pigments are preferably used, such as self-dispersible pigments having anionic groups on their surfaces, pigments dispersed with anionic polymer dispersants, and pigments dispersed by coating the surface with anionic resins. In particular, pigments dispersed with anionic polymer dispersants are preferred due to their excellent dispersibility and ability to react appropriately with the treatment liquid for fixation.

[0176] As the pigment, any conventionally known pigment 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.

[0177] Note that, in titanium oxide, which is generally difficult to ensure ink ejection stability and adhesion, the present invention can particularly preferably reduce the occurrence of bleeding and improve adhesion.

[0178] Titanium oxide has three crystal forms: anatase, rutile, and brookite. Generally, they can be broadly categorized into anatase and rutile. While not particularly limited, rutile, which has a high refractive index and excellent shielding properties, is preferred. Specific examples include the TR series from Fuji Titanium Industry Co., Ltd., the JR series from TAYCA Co., Ltd., and TIPAQUE from Ishihara Sangyo Co., Ltd.

[0179] The insoluble pigment is not particularly limited, but preferred examples include azo, azomethine, methine, diphenylmethane, triphenylmethane, quinacridone, anthraquinone, perylene, indigo, quinophthalone, isoindolinone, isoindolinline, azine, oxazine, thiazine, dioxazine, thiazole, phthalocyanine, and diketopyrrolopyrrole.

[0180] Specific examples of organic pigments that can be preferably used include the following.

[0181] Examples of the pigment for magenta or red include CI Pigment Red 2, CI Pigment Red 3, CI Pigment Red 5, CI Pigment Red 6, CI Pigment Red 7, CI Pigment Red 15, CI Pigment Red 16, CI Pigment Red 48:1, CI Pigment Red 53:1, CI Pigment Red 57:1, CI Pigment Red 122, CI Pigment Red 123, CI Pigment Red 139, CI Pigment Red 144, CI Pigment Red 149, CI Pigment Red 166, CI Pigment Red 177, CI Pigment Red 178, CI Pigment Red 202, CI Pigment Red 222, and CI Pigment Violet 19.

[0182] Examples of orange or yellow pigments include CI Pigment Orange 31, CI Pigment Orange 43, CI Pigment Yellow 12, CI Pigment Yellow 13, CI Pigment Yellow 14, CI Pigment Yellow 15, CI Pigment Yellow 15:3, CI Pigment Yellow 17, CI Pigment Yellow 74, CI Pigment Yellow 93, CI Pigment Yellow 128, CI Pigment Yellow 94, CI Pigment Yellow 138, and CI Pigment Yellow 155. In particular, CI Pigment Yellow 155 is preferred in terms of the balance between hue and light resistance.

[0183] Examples of the green or cyan pigment include CI Pigment Blue 15, CI Pigment Blue 15:2, CI Pigment Blue 15:3, CI Pigment Blue 16, CI Pigment Blue 60, and CI Pigment Green 7.

[0184] Examples of black pigments include CI Pigment Black 1, CI Pigment Black 6, and CI Pigment Black 7.

[0185] <Pigment Dispersant>

[0186] The ink of the present invention preferably contains a pigment dispersant for dispersing the pigment. The pigment dispersant is not particularly limited, but is preferably a polymer dispersant having an anionic group. Pigment dispersants having a molecular weight within the range of 5,000 to 200,000 can be preferably used.

[0187] Examples of the polymer dispersant include block copolymers, random copolymers, and salts thereof, polyoxyalkylenes, and polyoxyalkylene alkyl ethers having a structure derived from two or more monomers selected from styrene, styrene derivatives, vinylnaphthalene derivatives, acrylic acid, acrylic acid derivatives, maleic acid, maleic acid derivatives, itaconic acid, itaconic acid derivatives, fumaric acid, and fumaric acid derivatives.

[0188] The polymer dispersant preferably has an acryloyl group and is preferably added after being neutralized with a neutralizing base. The neutralizing base is not particularly limited, but is preferably an organic base such as ammonia, monoethanolamine, diethanolamine, triethanolamine, or morpholine. In particular, when the pigment is titanium oxide, the titanium oxide is preferably dispersed with the polymer dispersant having an acryloyl group.

[0189] The amount of the polymer dispersant added is preferably within a range of 10 to 100% by mass, more preferably within a range of 10 to 40% by mass, relative to the pigment.

[0190] The pigment is particularly preferably in the form of a so-called encapsulated pigment, in which the pigment is encapsulated with the polymer dispersant. Various known methods can be used to encapsulate the pigment with the polymer dispersant, with preferred examples including a phase inversion emulsification method, an acid precipitation method, or a method in which the pigment is dispersed using a polymerizable surfactant, a monomer is supplied thereto, and encapsulation is performed during polymerization.

[0191] A particularly preferred method includes dissolving a water-insoluble resin in an organic solvent such as methyl ethyl ketone, partially or completely neutralizing the acidic groups in the resin with an alkali, adding a pigment and ion-exchanged water, and dispersing the mixture. The organic solvent is then removed, and water is added as needed.

[0192] The average particle size of the dispersed pigment in the ink is preferably 50 nm or greater and less than 200 nm. This improves the dispersion stability of the pigment and the storage stability of the ink. The pigment particle size can be determined using commercially available particle size measurement equipment using methods such as dynamic light scattering and electrophoresis. Dynamic light scattering is simple and can accurately measure the particle size range.

[0193] The pigment can be dispersed in a disperser together with a dispersant and other additives as required according to the desired purpose.

[0194] Conventionally known dispersers, such as ball mills, sand mills, wire mills, and high-pressure homogenizers, can be used. A sand mill is preferred because it provides a sharper particle size distribution for dispersing the pigment. The material of the beads used in the sand mill is not particularly limited; however, zirconium oxide or zircon is preferred to prevent bead fragmentation and ionic contamination. The beads preferably have a diameter of 0.3 to 3 mm.

[0195] The content of the pigment in the ink is not particularly limited, but is preferably in the range of 7 to 18% by mass for titanium oxide and in the range of 0.5 to 7% by mass for organic pigments.

[0196] <Resin Microparticles>

[0197] The resin fine particles (hereinafter also simply referred to as "resin") contained in the ink of the present invention are preferably water-insoluble resin fine particles.

[0198] The glass transition temperature (Tg) of the resin fine particles is preferably in the range of 40° C. to 90° C. The glass transition temperature can be determined by reading the Tg from an endothermic peak when the temperature is increased at a rate of 10° C. / min within the temperature range of −30° C. to 200° C. using a DSC (differential scanning calorimeter).

[0199] The water-insoluble resin used in the present invention is a water-insoluble resin that can receive ink and exhibits solubility or affinity for the ink.

[0200] Water-insoluble resin microparticles are inherently water-insoluble but are dispersed in an aqueous medium as tiny particles. These are water-insoluble resins that are forcibly emulsified and dispersed in water using an emulsifier or other agent, or self-emulsifying water-insoluble resins that have hydrophilic functional groups introduced into the molecules to form a stable aqueous dispersion without the use of emulsifiers or dispersion stabilizers. These resins are typically used in an emulsified and dispersed state in water or a water / alcohol mixed solvent.

[0201] In the present invention, "water-insoluble" means that the amount of a resin dissolved in 100 g of water at 25°C after drying at 105°C for 2 hours is 10 g or less, preferably 5 g or less, and more preferably 1 g or less. However, if the resin has salt-forming groups, the solubility refers to the amount of the resin dissolved when the salt-forming groups are 100% neutralized with acetic acid or sodium hydroxide, depending on the type of resin.

[0202] The resin having a glass transition temperature within the range of 40°C to 90°C is preferably any one of acrylic resins, urethane resins, polyester resins, or composite resins of urethane and acrylic resins, and particularly preferably acrylic resins, urethane resins, polyester resins, or composite resins of urethane and acrylic resins. The average particle size of the resin particles of these resins is preferably 200 nm or less. The average particle size is particularly preferably within the range of 100 to 150 nm.

[0203] The polyester resin, urethane resin, acrylic resin, or composite resin fine particles of urethane resin and acrylic resin are preferably anionic or nonionic.

[0204] The resin particles used in inks preferably contain an acid structure. This allows them to disperse in water even with a small amount of surfactant, improving the water resistance of the ink layer. This is called a self-emulsifying type, meaning that the resin can be dispersed and stabilized in water solely through the molecular ionicity, without the use of a surfactant. Examples of acid structures include acid groups such as carboxyl (-COOH) and sulfonic acid (-SO3H). The acid structure can be present in the resin as a side chain or at the end.

[0205] The ink of the present invention particularly preferably contains a water-dispersible polyester resin having a sulfonic acid group, thereby achieving high adhesion to the substrate.

[0206] Preferably, part or all of the acid structure is neutralized. Neutralizing the acid structure can improve the water dispersibility of the resin. Examples of neutralizing agents for neutralizing the acid structure are preferably organic amines, preferably trimethylamine, triethylamine, tripropylamine, tributylamine, N-methyldiethanolamine, triethanolamine, and the like.

[0207] The ink of the present invention also preferably contains 3 to 15% by mass of resin microparticles having a cohesiveness of 0.2 or less with a 0.15% by mass calcium acetate aqueous solution. The use of such low-cohesive resin microparticles ensures high wettability to the substrate while also achieving high injection stability, resulting in higher image quality and excellent substrate adhesion.

[0208] In the present invention, "cohesion" refers to a value calculated by the following formula after measuring the balance according to the following procedure.

[0209] (i) 5 g of an aqueous solution of resin fine particles (solid content: 10% by mass) containing resin fine particles and 5 g of a 0.3% by mass calcium acetate monohydrate aqueous solution were mixed.

[0210] (ii) The mixed solution is centrifuged.

[0211] (iii) 2 g of the supernatant separated by centrifugation was collected.

[0212] (iv) 2 g of the collected supernatant was dried at 150° C. for 30 minutes, and the mass of the solid content (remainder (g)) was measured.

[0213] (V) The cohesiveness value was calculated by the following formula.

[0214] Formula: Cohesion = 1 - [mass of solid content (g) / (mass of collected supernatant (g) × 5%)]

[0215] Examples of the resin fine particles having a cohesiveness of 0.2 or less include VYLONAL MD2000 manufactured by Toyobo Co., Ltd., MOWINYL 6969D manufactured by Japan Coating Resin Co., Ltd., and EVAFANOL HA-560 manufactured by Nikka Chemical Co., Ltd.

[0216] Hereinafter, each resin will be described.

[0217] (Polyester resin)

[0218] The polyester resin having a polyester skeleton as the water-insoluble resin particles can be obtained using a polyol component and a polycarboxylic acid component such as a polycarboxylic acid, a polycarboxylic anhydride, or a polycarboxylic acid ester.

[0219] Examples of the polyol component include diols (glycols), specifically, alkylene glycols having 2 to 36 carbon atoms (ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, etc.), alkylene ether glycols having 4 to 36 carbon atoms (diethylene glycol, triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc.), alicyclic glycols having 6 to 36 carbon atoms (1,4-cyclohexanedimethanol, hydrogenated bisphenol A, etc.), ), alkylene oxides (ethylene oxide (hereinafter referred to as EO), propylene oxide (hereinafter referred to as PO), butylene oxide (hereinafter referred to as BO) adducts having a carbon number of 2 to 4 of the alicyclic diol (the addition mole number is in the range of 1 to 30), or alkylene oxides (EO, PO, BO, etc.) adducts having a carbon number of 2 to 4 of bisphenols (bisphenol A, bisphenol F, bisphenol S, etc.) (the addition mole number is in the range of 2 to 30), etc. These may be used alone or in combination of two or more.

[0220] Examples of the polycarboxylic acid component include divalent carboxylic acids (dicarboxylic acids), specifically, alkane dicarboxylic acids (such as succinic acid, adipic acid, and sebacic acid) having 4 to 36 carbon atoms, alkenyl succinic acids (such as dodecenyl succinic acid), alicyclic dicarboxylic acids (such as dimer acid (dimer linoleic acid)) having 4 to 36 carbon atoms, olefin dicarboxylic acids (such as maleic acid, fumaric acid, citraconic acid, and mesaconic acid) having 4 to 36 carbon atoms, and aromatic dicarboxylic acids (such as phthalic acid, isophthalic acid, terephthalic acid, or derivatives thereof, and naphthalene dicarboxylic acids) having 8 to 36 carbon atoms. These may be used alone or in combination of two or more.

[0221] The polyester resin is preferably a polyester resin having an anionic group in the molecule, and particularly preferably a polyester resin containing a sulfonic acid group. A known synthesis method for obtaining a polyester containing a sulfonic acid group includes, for example, a polycondensation reaction between a dicarboxylic acid containing a sulfonic acid group and a diol, or a polycondensation reaction between a dicarboxylic acid and a diol containing a sulfonic acid salt.

[0222] Examples of the dicarboxylic acid component having a sulfonic acid group include 2-sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfoisophthalic acid-2,7-dicarboxylic acid, 5-(4-sulfophenoxy)isophthalic acid, and alkali metal salts thereof.

[0223] Examples of the diol having a sulfonic acid group include 2-sulfo-1,4-butanediol, 2,5-dimethyl-3-sulfo-2,5-hexanediol, and alkali metal salts thereof.

[0224] 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.

[0225] As the polyester resin, a commercially available product can be used. Examples of commercially available water-dispersible polyester resins having a sulfonic acid group include VYLONAL MD-1100, MD-1200, MD-1245, MD-1480, MD-1500, and MD-2000 manufactured by Toyobo Co., Ltd.; PLASCOAT Z-221, Z-446, Z-561, Z-880, and Z-3310 manufactured by Huying Chemical Co., Ltd.; and PESRESIN A-520, A-613D, A-615GE, A-640, A-645GH, A-647GEX, A-110F, and A-160P manufactured by Takamatsu Oil & Fats Co., Ltd. Among them, resins having a glass transition temperature of 40° C. to 90° C. are particularly preferred, and examples thereof include VYLONAL MD-1100, MD-1200, MD-1245, MD-1500, and MD-2000 manufactured by Toyobo Co., Ltd., PLASCOAT Z-221, Z-446, and Z-561 manufactured by Huying Chemical Co., Ltd., and PESRESIN A-520, A-613D, A-615GE, A-640, A-645GH, and A-647GEX manufactured by Takamatsu Oil & Fats Co., Ltd. These may be used alone or in combination of two or more.

[0226] (urethane resin)

[0227] As the urethane resin of the water-insoluble resin particles, a urethane resin having a hydrophilic group can be used.

[0228] The urethane resin is preferably an aqueous dispersion of a self-emulsifying urethane having water-soluble functional groups dispersed within its molecules, or an aqueous dispersion of a forced-emulsifying urethane emulsified under strong mechanical shear using a surfactant. The urethane resin in the aqueous dispersion can be obtained by reacting a polyol with an organic polyisocyanate and a hydrophilic group-containing compound.

[0229] Examples of the polyol that can be used for preparing the aqueous dispersion of the urethane resin include polyester polyol, polyether polyol, polycarbonate polyol, and polyolefin polyol.

[0230] Examples of the polyester polyol 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-butylene glycol, 3-methylpentanediol, hexamethylene glycol, 1,8-octanediol, 2-methyl-1,3-propanediol, bisphenol A, hydrogenated bisphenol A, trimethylolpropane, and cyclohexanedimethanol; and condensates thereof with polycarboxylic acids such as succinic acid, glutaric acid, adipic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, tetrahydrofuranic acid, endo(end)methinetetrahydrofuranic acid, and hexahydrophthalic acid.

[0231] Examples of the polyether polyol include polyethylene glycol, polypropylene glycol, polyethylene polytetramethylene glycol, polypropylene polytetramethylene glycol, and polytetramethylene glycol.

[0232] Polycarbonate polyols can be obtained, for example, by reacting carbonic acid derivatives such as diphenyl carbonate, dimethyl carbonate, or phosgene with diols. Examples of the diols include ethylene glycol, diethylene glycol, triethylene glycol, 1,2- and 1,3-propylene glycol, neopentyl glycol, 1,3- and 1,4-butylene glycol, 3-methylpentanediol, hexamethylene glycol, 1,8-octanediol, 2-methyl-1,3-propanediol, bisphenol A, hydrogenated bisphenol A, trimethylolpropane, and cyclohexanedimethanol.

[0233] Examples of organic polyisocyanates that can be used in the preparation of aqueous dispersions of urethane resins include aromatic isocyanates such as toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymeric MDI, xylylene diisocyanate (XDI), and tetramethylxylylene diisocyanate (TMXDI); aliphatic isocyanates such as hexamethylene diisocyanate (HMDI); and alicyclic isocyanates such as isophorone diisocyanate (IPDI) and 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI, H12MDI). These can be used alone or in combination of two or more.

[0234] In addition, examples of hydrophilic group-containing compounds that can be used to prepare aqueous dispersions of urethane resins include: carboxylic acid-containing compounds such as 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, 2,2-dimethylolbutanoic acid, 2,2-dimethylolpentanoic acid, and glycine, and their sodium salts, potassium salts, amine salts and other derivatives; sulfonic acid-containing compounds such as taurine (i.e., aminoethylsulfonic acid) and ethoxypolyethylene glycol sulfonic acid, and their sodium salts, potassium salts, amine salts and other derivatives.

[0235] The urethane resin can be obtained by a known method, for example, by mixing the polyol, organic polyisocyanate and hydrophilic group-containing compound and reacting them at 30° C. to 130° C. for 30 minutes to 50 hours to obtain a urethane prepolymer.

[0236] The urethane prepolymer is elongated and polymerized by using 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 a chain extender, it can react with free isocyanate in a short time, effectively extending the isocyanate-terminated prepolymer.

[0237] Examples of chain extender amine compounds include aliphatic polyamines such as ethylenediamine and triethylenediamine; aromatic polyamines such as m-xylenediamine and toluenediamine; and polyhydrazide compounds such as hydrazine and adipic acid dihydrazide. These amine compounds may contain, along with the polyamine, a monovalent amine such as dibutylamine, methyl ethyl ketoxime, or the like as a reaction terminator, to the extent that polymerization is not significantly inhibited.

[0238] It should be noted that, in the synthesis of the urethane prepolymer, a solvent that is inactive with isocyanate and capable of dissolving the urethane prepolymer may be used. Examples of such 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 removed at the end.

[0239] In addition, in the synthesis of the urethane prepolymer, in order to promote the reaction, catalysts such as amine catalysts (such as triethylamine, N-ethylmorpholine, triethylamine, etc.), tin catalysts (such as dibutyltin dilaurate, dioctyltin dilaurate, tin octoate, etc.), and titanium catalysts (such as tetrabutyl titanate, etc.) can be added.

[0240] As for the number average molecular weight of the carbamate resin, it is preferred to introduce a branched structure and an internal cross-linked structure to increase it as much as possible, and the number average molecular weight is preferably 50,000 to 10,000,000. This is because by setting the molecular weight within the above range, the carbamate resin is not easily soluble in the solvent, so a coating film with excellent weather resistance and water resistance can be obtained. It should be noted that the number average molecular weight (Mn) is a value measured by gel permeation chromatography (GPC), for example, "RID-6A" manufactured by Shimadzu Corporation (column: "TSK-GEL" manufactured by Tosoh Corporation, solvent: tetrahydrofuran (THF), column temperature: 40°C), and can be obtained from a calibration curve prepared using a polystyrene standard sample.

[0241] The urethane resin may be a commercially available product. Examples of commercially available urethane resins having a glass transition temperature of 40° C. to 90° C. include Neorez R-967, R-600, and R-9671 manufactured by Kusumoto Chemicals, EVAFANOL HA-560 manufactured by Nikka Chemicals, and SF870 manufactured by Daiichi Kogyo Seiyaku Co., Ltd.

[0242] (Acrylic resin)

[0243] The acrylic resin as the water-insoluble resin particles can be obtained by using a copolymer with an acrylic acid ester component, a methacrylic acid ester component, a styrene component, or the like.

[0244] Examples of the acrylate component and the methacrylate component include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, cyclohexyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, isobornyl (meth)acrylate, benzyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, benzyl (meth)acrylate, glycidyl (meth)acrylate, (meth)acrylic acid, (di)ethylene glycol di(meth)acrylate, 1,4-butylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, glycerol di(meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, and acrylamide.

[0245] Examples of the styrene component include styrene, 4-methylstyrene, 4-hydroxystyrene, 4-acetoxystyrene, 4-acetylstyrene, and styrenesulfonic acid. These components may be used alone or in combination of two or more.

[0246] The number average molecular weight (Mn) of the acrylic resin is preferably 1,000 to 50,000, more preferably 2,000 to 20,000. This is because, if the number average molecular weight (Mn) of the acrylic resin is 1,000 or more, the cohesive force of the coating film becomes stronger and the adhesion is improved. If it is 50,000 or less, the solubility in organic solvents is good, which promotes the miniaturization of the particle size of the emulsified dispersion. It should be noted that the number average molecular weight (Mw) is a value measured by gel permeation chromatography (GPC). For example, it can be obtained from a calibration curve prepared using 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).

[0247] Commercially available products can be used as the acrylic resin. Examples of commercially available products having a glass transition temperature of 40°C to 90°C include acrylic emulsions such as MOWINYL 6899D, 6969D, and 6800 manufactured by JAPAN COATING RESIN CO., LTD., and TOCRYL W-7146, W-7147, W-7148, W-7149, and W-7150 manufactured by TOYO-CHEM CO., LTD.

[0248] (Composite resin particles)

[0249] The composite resin particles that may be included in the ink are preferably composite resin particles formed by emulsifying an acrylic resin in a urethane resin, that is, composite resin particles having an inner layer composed of an acrylic resin and a surface layer composed of a urethane resin.

[0250] Here, the urethane resin is present at the interface between the acrylic resin as the water-insoluble resin particles and water as the continuous phase, and functions as a water-insoluble resin particle layer different from the resin protecting the water-insoluble resin particles.

[0251] By preparing composite resin particles in which an acrylic resin is emulsified with a urethane resin, the physical properties of the image (coating film) can be improved compared to the case where the acrylic resin and the urethane resin are emulsified and mixed separately, and the storage stability of the composite resin particles can also be improved.

[0252] In the composite resin particles formed by emulsifying the acrylic resin in the carbamate resin, the mass ratio (U / A) of the carbamate resin (U) to the acrylic resin (A) is preferably 40 / 60 to 95 / 5. When the presence ratio of the carbamate resin (U) is within the above range, the compatibility with the dispersant is improved and the solvent resistance is also improved. In addition, when the presence ratio of the acrylic resin (A) is within the above range, the adhesion to the acrylic film is excellent. In the above ratio, the mass ratio (U / A) of the carbamate resin (U) to the acrylic resin (A) is preferably 40 / 60 to 80 / 20.

[0253] The total resin concentration of the acrylic resin and the urethane resin in the composite resin particles is not particularly limited, but is preferably 5.0% by mass or more, more preferably 10.0 to 70.0% by mass. When the resin concentration is within this range, the fixing properties between the substrate and the ink are improved.

[0254] Furthermore, in the emulsification of the acrylic resin using the urethane resin, a surfactant that functions as an emulsifier may be used together with the urethane resin. Here, the addition of the emulsifier can improve the storage stability of the composite resin fine particles.

[0255] As the emulsifier, an anionic surfactant or a nonionic surfactant can be used. In the present invention, it is preferred to use either anionic surfactant or nonionic surfactant, and more preferably both. The total amount of the anionic surfactant and nonionic surfactant is preferably 1.0 to 20.0 parts by mass relative to 100 parts by mass of the total resin mass. Furthermore, by setting the total amount of the anionic surfactant and nonionic surfactant to 20.0 parts by mass or less, water resistance and solvent resistance can be improved.

[0256] The mass ratio (X / Y) of the anionic surfactant (X) to the nonionic surfactant (Y) is preferably 100 / 0 to 50 / 50. By adjusting the amount of the anionic surfactant to be added within this range, emulsification and storage stability can be further improved.

[0257] Examples of anionic surfactants that can be used for emulsification include alkyl sulfates, polyoxyethylene alkyl ether sulfates, sulfosuccinates, α-olefin sulfonates, N-acylamino acid salts, carboxylates, and phosphates. Among them, sulfosuccinates and α-olefin sulfonates are preferred.

[0258] Examples of the type of salt are not particularly limited, and include metal salts such as sodium salts, potassium salts, and magnesium salts, and triethanolamine salts.

[0259] Examples of nonionic surfactants that can be used for emulsification include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkylamine ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, and sucrose fatty acid esters. Among them, polyoxyethylene alkyl ethers and polyoxyethylene alkylphenyl ethers are preferred.

[0260] The average particle size of the composite resin microparticles is not particularly limited, but is preferably 10 to 500 nm, more preferably 10 to 300 nm, and even more preferably 10 to 200 nm. The average particle size can be determined using commercially available particle size measurement equipment using dynamic light scattering, electrophoresis, or the like. Dynamic light scattering is simple and can accurately measure the particle size range.

[0261] By using composite resin fine particles obtained by emulsifying an acrylic resin in a urethane resin, it is possible to improve the fixability of an image (coating film) to an absorptive substrate or a non-absorptive substrate.

[0262] <Water-soluble solvent>

[0263] The water-soluble solvent contained in the ink of the present invention has a boiling point within a range of 150 to 250°C.

[0264] Examples of such water-soluble solvents include alcohols, polyols, amines, amides, glycol ethers, and 1,2-alkanediols having 4 or more carbon atoms. Examples of the water-soluble solvents include those exemplified for the treatment liquid.

[0265] The ink may contain one or a combination of two or more selected from the above water-soluble solvents.

[0266] The content of the water-soluble solvent in the ink is not particularly limited, but is preferably within a range of 10 to 60% by mass.

[0267] <Surfactant>

[0268] By including a surfactant in the ink of the present invention, it is possible to improve the ink injection stability and control the spread (dot diameter) of the droplet landed on the recording medium.

[0269] The surfactant that can be used in the ink of the present invention is not particularly limited and includes the surfactants exemplified in the treatment liquid. As described above, the treatment liquid preferably does not contain the same surfactant as that contained in the ink.

[0270] The content of the surfactant in the ink is not particularly limited, but is preferably within a range of 0.1 to 5.0% by mass.

[0271] <Water>

[0272] The water contained in the ink of the present invention is not particularly limited, and may be ion-exchanged water, distilled water, or pure water.

[0273] In addition to the above-mentioned additives, various known additives such as polysaccharides, viscosity modifiers, resistivity modifiers, film-forming agents, ultraviolet absorbers, antioxidants, anti-fading agents, preservatives, and rust inhibitors can be appropriately selected and used in the ink used in the present invention, depending on the need, in order to improve injection stability, print head and ink cartridge compatibility, storage stability, image preservation, and other properties. Examples of such additives include liquid paraffin, dioctyl phthalate, tricresyl phosphate, oil droplets such as silicone oil, and additives such as those in Japanese Unexamined Patent Publication Nos. 57-74193, 57-87988, and 62-261476. The ultraviolet absorbers described in Japanese Patent Application Laid-Open No. 57-74192, Japanese Patent Application Laid-Open No. 57-87989, Japanese Patent Application Laid-Open No. 60-72785, Japanese Patent Application Laid-Open No. 61-146591, Japanese Patent Application Laid-Open No. 1-95091, Japanese Patent Application Laid-Open No. 3-13376, etc., the fluorescent whitening agents described in Japanese Patent Application Laid-Open No. 59-42993, Japanese Patent Application Laid-Open No. 59-52689, Japanese Patent Application Laid-Open No. 62-280069, Japanese Patent Application Laid-Open No. 61-242871, Japanese Patent Application Laid-Open No. 4-219266, etc.

[0274] The ink used in the present invention having the above-mentioned structure preferably has a viscosity of 1 to 40 mPa·s at 25° C., and more preferably 2 to 10 mPa·s.

[0275] [Inkjet Recording Method]

[0276] The inkjet recording method of the present invention records images using an ink set comprising the treatment liquid and ink. Using this ink set, for example, a single inkjet printer can be used to continuously and efficiently apply the treatment liquid comprising the ink set of the present invention and print with the ink on a substrate. Furthermore, high-quality text, patterns, and the like can be printed with minimal dot diameter variation between substrates.

[0277] Specifically, the inkjet recording method of the present invention is an inkjet recording method for recording an image using the ink set of the present invention, wherein after the treatment liquid is applied to the substrate, the ink is applied to the area applied with the treatment liquid in a state wetted with the treatment liquid without undergoing a heating and drying process.

[0278] That is, the present invention comprises: a process of imparting the treatment liquid to the recording area of ​​the substrate (treatment liquid imparting process); and a process of imparting the ink by inkjet recording in a state where the area imparted with the treatment liquid is wetted with the treatment liquid (ink imparting process).

[0279] Furthermore, the inkjet recording method of the present invention preferably further comprises, in addition to the above steps, an ink heating and drying step of heating and drying the treatment liquid and ink applied to the substrate to form a treatment liquid layer and an ink layer after the ink applying step.

[0280] Furthermore, in the ink application step, it is preferred that the ink be applied to the area to which the treatment liquid has been applied while the drying rate of the treatment liquid is 30% or less, and the ink application step be performed preferably within 10 seconds after the treatment liquid application step. It is particularly preferred that the ink application step be performed within 0.1 to 5 seconds after the treatment liquid application step while the drying rate of the treatment liquid is within the range of 1% to 10%.

[0281] <Base Material>

[0282] The substrate (recording medium) that can be used in the inkjet recording method of the present invention is not particularly limited and can be an absorptive substrate composed of an absorptive material or a non-absorptive substrate composed of a non-absorptive material. From the perspective of embodying the effects of the present invention, a non-absorptive substrate is preferred.

[0283] In the present invention, "absorbability" refers to absorbability to water, and "non-absorbability" refers to non-absorbability to water.

[0284] As the non-absorptive substrate, a known plastic film can be used.

[0285] Specific examples of the known plastic films include biodegradable films such as polyester films such as polyethylene terephthalate, polyethylene films, polypropylene films, polyamide films such as nylon, polystyrene films, polyvinyl chloride films, polycarbonate films, polyacrylonitrile films, and polylactic acid films.

[0286] In addition, films coated with polyvinylidene chloride on one or both sides or films deposited with metal oxides can also be preferably used to impart gas barrier properties, moisture resistance, and aroma retention. Non-absorbing films can preferably be unstretched or stretched films.

[0287] In the case of a plastic film, the thickness of the substrate is preferably in the range of 10 μm to 120 μm, more preferably 12 μm to 60 μm.

[0288] Furthermore, non-absorbent substrates such as tinplate for three-piece cans and tin-free steel sheets (TFS sheets, thickness 0.1 μm to 0.6 μm) are also preferably used. These can be suitably used, for example, in packaging materials for canned foods that have a thermosetting resin coating layer. These canned food packaging materials typically use epoxy-phenolic coatings or polyester laminating agents on the food side and polyester or acrylic thermosetting coatings on the outside to block air, moisture, and light, thereby sealing the food inside.

[0289] Hereinafter, each step of the inkjet recording method will be described.

[0290] <Treatment Liquid Application Step>

[0291] In the treatment liquid applying step, the treatment liquid is applied onto a recording medium serving as a substrate.

[0292] The method for applying the treatment liquid to the recording medium is not particularly limited, and preferred examples include roll coating, curtain coating, spray coating, and inkjet coating. Among them, roll coating is preferred because a roll coater or the like can be connected to an inkjet device and can be applied efficiently even when the viscosity is high.

[0293] Furthermore, the step of applying the treatment liquid using an inkjet method is preferred because the flocculant does not need to be applied to the ink non-applied area and thus does not cause the flocculant that has not reacted with the ink to be released and cause white turbidity.

[0294] In this case, as described later, when the substrate used is a metal substrate, etc., it is also preferred to arrange the metal substrate on the conveyor belt, apply the treatment liquid layer while conveying the belt, or use a flatbed printer with a fixed substrate to form the treatment liquid layer.

[0295] <Ink application process>

[0296] The ink application step is a step of applying the inks of the ink set by inkjet printing simultaneously with or immediately after forming the treatment liquid layer on the recording medium serving as the substrate. In particular, it is preferred that the ink be applied to the area to which the treatment liquid has been applied after the treatment liquid application step, while the drying rate of the treatment liquid is 30% or less. Furthermore, it is preferred that the ink be applied to the area to which the treatment liquid has been applied within 10 seconds after the treatment liquid has been applied to the substrate.

[0297] In addition, the drying rate of the processing liquid is defined by the following formula.

[0298] (Drying rate of treatment liquid) = 1 - ((Mass of treatment liquid after drying (g)) / (Mass of treatment liquid before drying (g))

[0299] By applying the ink in a state where the drying rate of the treatment liquid is 30% or less, the ink and the treatment liquid are appropriately mixed, and the effects of the present invention can be more significantly exhibited.

[0300] Furthermore, by applying the ink within 10 seconds after applying the treatment liquid to the substrate, the penetration of the treatment liquid into the absorptive substrate and the shrinkage of the treatment liquid in the non-absorptive substrate can be suppressed, thereby achieving higher image quality.

[0301] In order to set the drying rate of the treatment liquid to 30% or less, as described above, there are methods such as adjusting the time from application of the treatment liquid to application of the ink, and appropriately adjusting the temperature of the recording medium.

[0302] In addition, in the ink application process, from the perspective of achieving higher image quality, it is preferred to adjust the amount of ink droplets in such a manner that the amount of ink applied per unit area is within a range of 2 to 25 times the amount of treatment liquid applied, and the more preferred range of the applied amount is 2.5 to 3.5 times.

[0303] The inkjet method is not particularly limited, and a printer equipped with an inkjet head filled with ink can be used. Specifically, ink droplets are ejected from the nozzles of the inkjet head based on digital signals and landed on the treatment liquid layer on the substrate to perform printing.

[0304] The inkjet head may be either a drop-in inkjet head or a continuous inkjet head. Examples of drop-in inkjet heads include electro-mechanical inkjet heads of single-chamber, dual-chamber, bender, piston, shared-mode, and shared-wall types, and electro-thermal inkjet heads of thermal inkjet and Bubble Jet ("Bubble Jet" is a registered trademark of Canon Inc.).

[0305] Among the inkjet heads, an inkjet head using a piezoelectric element as an electromechanical conversion element for an electromechanical conversion system (also referred to as a piezoelectric type inkjet head) is preferable.

[0306] In addition, in the case of a single-pass type inkjet printer that can use either a scanning type or a single-pass type inkjet head, it is preferable to use a line head type inkjet head.

[0307] A line-head inkjet head is an inkjet head having a length greater than the width of the printing area. A line-head inkjet head may be a single head or a combination of multiple heads.

[0308] In addition, multiple nozzles may be arranged in parallel with their nozzles staggered to improve the overall resolution of the nozzles.

[0309] The conveyance speed of the recording medium serving as the substrate can be set, for example, within a range of 1 to 120 m / min. The faster the conveyance speed, the faster the image formation speed. According to the present invention, even at very high linear speeds of 50 to 120 m / min, which are applicable to single-pass inkjet image formation methods, high-definition images with high ink fixability can be produced.

[0310] <Ink Heating and Drying Process>

[0311] In the ink heating and drying step, the ink applied to the recording medium as a substrate, that is, the area where the ink is applied, is heated, thereby drying the ink and the processing liquid.

[0312] In the ink heating and drying step, the heating temperature of the ink-applied region is preferably within a range of 60° C. to 200° C. The ink heating time is appropriately adjusted depending on the type of recording medium and the amount of ink applied.

[0313] By heating the area where the ink has been applied, water, water-soluble solvents, and other components of the treatment liquid and ink are removed. Furthermore, the polyvalent metal salt in the metal substrate is dried and thermally decomposed at a temperature above its thermal decomposition temperature. Furthermore, the image's abrasion resistance and adhesion to the substrate are improved.

[0314] Heat drying can be performed 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 hot roller.

[0315] The drying temperature can be obtained by measuring any one of the following temperatures during the entire period of drying the treatment liquid: (a) when using a non-contact heating type drying device such as a drying furnace, a hot air blower, etc., the air temperature such as the temperature inside the furnace or the hot air temperature; (b) when using a contact heating type drying device such as a hot plate, a hot roller, etc., the temperature of the contact heating part; or (c) the surface temperature of the surface to be dried. As the measurement location, it is more preferable to measure (c) the surface temperature of the surface to be dried.

[0316] The thickness of the ink layer obtained as described above is preferably within the range of 0.3 μm to 3.0 μm, more preferably within the range of 0.3 μm to 2.0 μm. When the ink layer thickness is 0.3 μm or greater, the adhesion and abrasion resistance of the image are easily improved. When the ink layer thickness is 3.0 μm or less, the deformation stress imparted to the ink layer can be reduced, thereby less likely to impair the adhesion of the image.

[0317] [Recording device]

[0318] Figure 1This is a schematic diagram of a preferred recording device in the present invention. However, the present invention is not limited thereto.

[0319] The recording apparatus 1 mainly includes a treatment liquid applying section 10 and an ink applying section 20. The treatment liquid applying section 10 forms a treatment liquid layer C on a substrate F, and the ink applying section 20 forms an ink layer R.

[0320] The treatment liquid applying unit 10 is not particularly limited as long as it can apply the treatment liquid to the substrate, but in the present invention, it is preferably an inkjet head 21. In addition to the inkjet head 21, for example, a roll coater may be used.

[0321] The ink applying section 20 is an inkjet head 21 that can eject ink.

[0322] In such a recording apparatus 1 , the processing liquid droplets 12 are ejected from the inkjet head 11 onto the substrate F fed from the feed roller 30 , thereby forming the processing liquid layer C.

[0323] Next, ink droplets 22 are ejected from the inkjet head 21 onto the treatment liquid layer C to form an ink layer R. The ink-applied area is heated and dried in the second drying section 23. The substrate F, on which the treatment liquid layer C and ink layer R are formed, is then wound up by a winding roller 40 to obtain an image recorded object.

[0324] It should be noted that in Figure 1 In the figure, the case where the substrate F is a film substrate is shown. In the case of a metal substrate, the metal substrate can be placed on a conveyor belt, and the treatment liquid layer C and the ink layer R can be formed by single-pass coating while the conveyor belt is being conveyed.

[0325] In addition, Figure 1 The apparatus may be configured to apply ink after applying a treatment liquid to the substrate, or may be configured to apply both the treatment liquid and the ink simultaneously. The ink is preferably ejected from the inkjet head when the drying rate of the treatment liquid layer is 30% or less.

[0326] In addition, as Figure 1 In addition to the recording devices shown above, flatbed printers are also preferably used for applying the treatment liquid and ink. Flatbed printers have a fixed substrate, allowing the inkjet head to move in the main scanning direction and a sub-scanning direction intersecting the main scanning direction, enabling printing without transporting the substrate. For metal substrates such as tinplate, roll-to-roll transport is not possible, unlike with resin film substrates. Therefore, a flatbed printer that does not require substrate transport is preferred.

[0327] As such a flatbed printer, there is the one disclosed in Japanese Patent Application Laid-Open No. 2015-74161. Figure 1 、Japanese Patent Application Publication No. 2017-177578 Figure 1 The printer is described as an example.

[0328] [Visual Records]

[0329] The image recorded material of the present invention preferably comprises a substrate, a treatment liquid layer formed on the substrate using the treatment liquid, and an ink layer formed on the treatment liquid layer using the ink.

[0330] like Figure 2 As shown, the image recorded material P is formed by coating the treatment liquid of the present invention on a substrate F using a roll coater or the like, or by ejecting the treatment liquid of the present invention from an inkjet head, thereby forming a treatment liquid layer C. At a position where the treatment liquid layer C is to be fixed, ink is ejected from the inkjet head and fixed to form an image recording layer R.

[0331] The above configuration is a minimum configuration. Other functional layers may be formed between the substrate and the treatment liquid layer. Furthermore, a non-absorbent film substrate may be attached to the upper layer of the ink layer, for example, via a laminate adhesive layer. A configuration in which the treatment liquid layer and the ink layer are in contact with each other is essential.

[0332] As an example of the image recorded article of the present invention, a preferred embodiment is an image recorded article using at least the treatment liquid and ink of the present invention, wherein a first layer containing a thermosetting resin, a second layer containing the treatment liquid, a third layer containing the ink, and a fourth layer containing a thermosetting resin are sequentially stacked on a metal substrate.

[0333] Specific examples of the image recorded object preferably include packaging materials for canned foods, retort foods, beverages, and the like.

[0334] Figure 3 A cross-sectional view of a canned food packaging material as an example of the image recorded material of the present invention is shown.

[0335] A thermosetting resin layer (primer layer) 52 is formed by roller coating a tinplate substrate 51 with a thermosetting resin (e.g., TW-1407 series, manufactured by T&K TOKA). An image is then formed thereon via a treatment liquid layer 53 and an ink layer 54. Subsequently, a thermosetting resin layer (top coat layer) 55 is formed by roller coating a thermosetting resin (e.g., AX-10 series, manufactured by T&K TOKA). This is then cured by heating and dried to obtain a canned food packaging material 50.

[0336] Example

[0337] The present invention is described in detail below with reference to Examples, but the present invention is not limited thereto. It should be noted that, in the following Examples, unless otherwise specified, the operations were performed at room temperature (25°C). Furthermore, unless otherwise specified, "%" and "parts" refer to "mass %" and "mass parts," respectively.

[0338] [Preparation of treatment solution T1]

[0339] To 3% by mass of calcium acetate hydrate as a polyvalent metal salt, 14% by mass of dipropylene glycol, 14% by mass of propylene glycol, 10% by mass of glycerin, 1% by mass of polyether-modified polysiloxane BYK3450, 0.1% by mass of a mildew preventative (PROXELG XL(S)), and ion-exchanged water (the remainder; the total amount is 100% by mass) were added while stirring. The resulting mixed solution was filtered through a 1 μm filter to obtain a treated liquid T1.

[0340] [Preparation of treatment solutions T2 to T6]

[0341] In the preparation of the treatment liquid T1, the treatment liquids T2 to T6 were prepared in the same manner except that the types and addition amounts of the polyvalent metal salt, solvent, surfactant, and addition amount of water were changed as shown in Table I below.

[0342] In addition, the abbreviations in Table 1 are as follows.

[0343] <Solvent>

[0344] "DPG:" diethylene glycol

[0345] "PG:" Propylene glycol

[0346] "1,2-HDO:" 1,2-hexanediol

[0347] "Gly:" glycerol

[0348] <Surfactant>

[0349] "TEGOWET250:" Polyether-modified polysiloxane TEGOWET-250 (manufactured by Evonik)

[0350] BYK3450: Polyether-modified polysiloxane BYK-3450 (manufactured by BYK-Chemie)

[0351] "BYK348:" Polyether-modified polysiloxane BYK-348 (manufactured by BYK-Chemie)

[0352] <Fungicide>

[0353] PROXEL GXL(S): 1,2-Benzisothiazolin-3-one

[0354] [Physical properties]

[0355] The dynamic surface tension, static surface tension, and dynamic surface tension after 30% drying of each of the obtained treatment liquids were measured by the following methods.

[0356] <Dynamic Surface Tension>

[0357] The dynamic surface tension of the treatment liquids T1 to T6 prepared above was measured using a dynamic surface tensiometer (BP-100: manufactured by KRUSS) using the maximum bubble pressure method at a surface life of 10 ms to 1000 ms. The measurement temperature was adjusted to 25°C. The dynamic surface tension (in mN / m) at surface lives of 15 ms, 100 ms, and 1000 ms is shown in Table I below. It should be noted that the dynamic surface tension at a surface life of 15 ms here is referred to as "dynamic surface tension A" described later.

[0358] <Static Surface Tension>

[0359] The static surface tension of the ink treatment liquids T1 to T6 prepared above was measured at 25° C. using a static surface tensiometer (CBVP-Z: manufactured by Kyowa Interface Science Co., Ltd.) using the Wilhelmy method. The measured values ​​(unit: mN / m) are shown in Table I below.

[0360] <30% Dynamic Surface Tension After Drying>

[0361] 100 g of each of the prepared ink treatment liquids T1 to T6 was weighed in a shallow container and dried under reduced pressure at 25°C until the liquid mass reached 70 g. The dynamic surface tension of each treatment liquid was then measured using the aforementioned method, and this was defined as the dynamic surface tension B after 30% drying. Furthermore, the difference (B) between the dynamic surface tension B after 30% drying and the measured dynamic surface tension A at a surface life of 15 ms was calculated. The results are shown in Table I below.

[0362] [evaluate]

[0363] <Injection Stability>

[0364] The prepared treatment solutions T1 to T6 were filled into a Konica Minolta independently driven inkjet head (360 npi, 14 pL discharge volume, 1024 nozzles) and subjected to a 30-minute continuous discharge test using a flash-synchronized droplet observation device. The injection stability was then evaluated according to the following criteria.

[0365] (Benchmark)

[0366] ◯: Of the 256 nozzles evaluated, all 256 nozzles discharged normally.

[0367] Δ: Among the 256 nozzles evaluated, one or more and less than five nozzles were observed to have abnormal discharge.

[0368] ×: Among the 256 nozzles evaluated, 5 or more abnormal discharge nozzles were observed.

[0369] <Processing Liquid Storage Properties>

[0370] The treatment solutions T1 to T6 prepared above were stored at a constant temperature of 60° C. for 2 weeks and then evaluated by visual observation according to the following criteria.

[0371] (Benchmark)

[0372] ○: No abnormalities such as white turbidity or separation were observed with the naked eye in the treated liquid after storage at 60°C for 2 weeks.

[0373] ×: The treated liquid after storage at 60°C for 2 weeks was slightly cloudy or separated.

[0374] ×: The treated liquid after storage at 60°C for 2 weeks was clearly cloudy or separated.

[0375] [Table 1]

[0376] Table I

[0377]

[0378] As shown in the above results, it was confirmed that the treatment liquid of the present invention having a dynamic surface tension in the range of 25 to 35 mN / m at a surface life of 15 ms has excellent injection stability and storage stability.

[0379] [Resin particle dispersions P1 to P5]

[0380] The cohesiveness and glass transition temperature (Tg) of each of the resin fine particles in the commercially available resin fine particle dispersions P1 to P5 listed in Table II below were measured. The measurement results are shown in Table II below.

[0381] <Agglutination>

[0382] The cohesiveness was measured by the following method.

[0383] First, in order to prepare a mixed solution containing 5% by mass of resin fine particles and 0.15% by mass of calcium acetate monohydrate, a calcium acetate aqueous solution was prepared by dissolving calcium acetate monohydrate in ion-exchanged water to obtain 0.30% by mass, and a diluted solution of a resin fine particle dispersion prepared by using each of the resin fine particle dispersions P1 to P5 shown in Table II and using ion-exchanged water to obtain a solid content of 10% by mass was prepared.

[0384] Next, 5 g of the calcium acetate aqueous solution was added to 5 g of the diluted resin fine particle dispersion while stirring to prepare 10 g of each mixed solution having a solid content of 5% by mass and a calcium acetate monohydrate content of 0.15% by mass.

[0385] Then, 10 g of each mixed solution was centrifuged using a centrifuge CF16RX manufactured by Hitachi Koki Co., Ltd. at a centrifugal acceleration of 200 G for 10 minutes, and approximately 2 g of the supernatant was collected from each of the separated solutions.

[0386] Next, each supernatant was heated at 150° C. for 30 minutes to remove water, and the mass of the solid matter remaining after heating was measured. The mass of the obtained solid content was substituted into the following calculation formula to calculate the cohesiveness.

[0387] Formula: Cohesion = 1-(mass of solid content (g) / (mass of collected supernatant (g) × 5%))

[0388] <Glass transition temperature>

[0389] The glass transition temperature (Tg) of the resin particles is determined by reading the endothermic peak when the temperature is increased at a rate of 10°C / min within a temperature range of -30°C to 200°C using a DSC (differential scanning calorimeter).

[0390] [Table 2]

[0391]

[0392] [Preparation of magenta ink]

[0393] <Preparation of Magenta Pigment Dispersion D1>

[0394] A mixed solution of 8% by mass of an anionic polymer dispersant (an acrylic dispersant having a carboxyl group neutralized with dimethylaminoethanol ("JONCRYL 819" manufactured by BASF, acid value 75 mgKOH / g, solid content 20% by mass), 20% by mass of propylene glycol, 0.1% by mass of a mildewproofing agent PROXEL GXL(S), and ion-exchanged water (the balance; the total amount is 100% by mass) was added to 20% by mass of a magenta pigment (a mixed crystal of Pigment Red 122 and Pigment Violet 19) and pre-mixed.

[0395] Then, the pigment was dispersed using a bead mill filled with 50% by volume of 0.3 mm zirconia beads to prepare a pigment dispersion D1 having a pigment content of 20% by mass.

[0396] The average particle size of the pigment particles contained in the pigment dispersion was 140 nm. The average particle size was measured using "Zetasizer Nano S-90" manufactured by Malvern Corporation.

[0397] <Preparation of Magenta Pigment Dispersion D2>

[0398] Magenta pigment dispersion D2 was prepared in the same manner as in magenta pigment dispersion D1, except that the pigment dispersant was changed from the acrylic dispersant "JONCRYL 819" to a nonionic polymer dispersant (BYK "BYK190" manufactured by BYK). The average particle size of the pigment particles contained in this pigment dispersion was 130 nm.

[0399] <Preparation of Magenta Ink M1>

[0400] To 20% by mass (4% by mass in terms of solid content) of magenta pigment dispersion D1, the commercially available resin fine particle dispersion P1 (the amount added was adjusted so that the resin fine particles (solid content) in the ink reached 5% by mass), 21% by mass of propylene glycol, 5% by mass of glycerin, 0.2% by mass of surfactant KF351A (Shin-Etsu Silicone Co., Ltd.), 1% by mass of surfactant E1010 (Nissin Chemical Industry Co., Ltd.), 0.1% by mass of antifungal agent PROXEL GXL(S), and ion-exchanged water (the remainder; the total amount is 100% by mass) were added with stirring. The resulting mixed solution was filtered through a 1 μm filter to obtain magenta ink M1. There was no substantial change in composition before and after filtration.

[0401] <Preparation of Magenta Inks M2 to M15>

[0402] In the preparation of magenta ink M1, M1 to M15 were prepared in the same manner except that the types and blending amounts of the resin fine particle dispersion, water-soluble solvent, and surfactant were changed as shown in Table III below.

[0403] [Preparation of cyan ink]

[0404] <Preparation of Cyan Pigment Dispersion D3>

[0405] To 20% by mass of a cyan pigment (Pigment Blue 15:3) were added 6% by mass of a pigment dispersant (an acrylic dispersant having a carboxyl group neutralized with dimethylaminoethanol ("JONCRYL 819" manufactured by BASF, acid value 75 mgKOH / g, solid content 20% by mass), 20% by mass of propylene glycol, 0.1% by mass of a mildew preventer (PROXEL GXL (S), and ion-exchanged water (the balance; the total amount is 100% by mass), and the resulting mixed solution was premixed.

[0406] Then, the pigment was dispersed using a bead mill filled with 50% by volume of 0.3 mm zirconia beads to prepare a cyan pigment dispersion D1 having a pigment content of 20% by mass. The average particle size of the pigment particles contained in this pigment dispersion was 120 nm.

[0407] <Preparation of Cyan Ink C1>

[0408] To 20% by mass (4% by mass in terms of solid content) of the cyan pigment dispersion D3, the commercially available resin fine particle dispersion P1 (the amount added was adjusted so that the resin fine particles (solid content) in the ink reached 5% by mass), 21% by mass of propylene glycol, 5% by mass of glycerin, 0.2% by mass of the surfactant KF351A (Shin-Etsu Silicone Co., Ltd.), 1% by mass of the surfactant E1010 (Nissin Chemical Industry Co., Ltd.), 0.1% by mass of a mildew preventative, and ion-exchanged water (the remainder; the total amount is 100% by mass) were added with stirring. The resulting mixed solution was filtered through a 1 μm filter to obtain cyan ink C1. There was no substantial change in composition before and after filtration.

[0409] <Preparation of Cyan Inks C2 and C3>

[0410] In the preparation of ink C1, cyan inks C2 and C3 were prepared in the same manner except that the types and amounts of the water-soluble solvent and surfactant, the amount of the antifungal agent, etc. were changed as shown in Table III below.

[0411] In addition, the abbreviations in Table III are as follows.

[0412] <Solvent>

[0413] "EG:" ethylene glycol

[0414] "PG:" Propylene glycol

[0415] "1,2-PDO:" 1,2-pentanediol

[0416] "1,2-HDO:" 1,2-hexanediol

[0417] "2Me-1,3-PDO:" 2-methyl-1,3-propanediol

[0418] GLY: Glycerin

[0419] "DEGBE": diethylene glycol monobutyl ether

[0420] <Surfactant>

[0421] "E1010:" acetylene glycol surfactant OLFINE E1010 (made by Nissin Chemical Industry)

[0422] “KF-351A:” Polysiloxane modified surfactant KF-351A (manufactured by Shin-Etsu Silicone Co., Ltd.)

[0423] "TEGOWET KL245:" Polyether-modified polysiloxane TEGOWET-KL245 (manufactured by Evonik)

[0424] "TEGOWET 250:" Polyether-modified polysiloxane TEGOWET-250 (manufactured by Evonik)

[0425] "TEGOWET 260:" Polyether-modified polysiloxane TEGOWET-260 (manufactured by Evonik)

[0426] BYK3450: Polyether-modified polysiloxane BYK-3450 (manufactured by BYK-Chemie)

[0427] BYK3455: Polyether-modified polysiloxane BYK-3455 (manufactured by BYK-Chemie)

[0428] "BYK348:" Polyether-modified polysiloxane BYK-348 (manufactured by BYK-Chemie)

[0429] "BYK349:" Polyether-modified polysiloxane BYK-349 (manufactured by BYK-Chemie)

[0430] <Fungicide>

[0431] PROXEL GXL(S): 1,2-Benzisothiazolin-3-one

[0432] [Physical properties]

[0433] The dynamic surface tension of each of the obtained inks was measured by the following method.

[0434] <Dynamic Surface Tension>

[0435] The dynamic surface tension of the prepared inks M1 to M15 and C1 to C3 was measured over a surface life of 10 to 1000 ms using a dynamic surface tensiometer (BP-100, manufactured by KRUSS) using the maximum bubble pressure method. The measurement temperature was adjusted to 25°C. The dynamic surface tension (in mN / m) at surface lives of 15, 100, and 1000 ms is shown in Table IV.

[0436] <Static Surface Tension>

[0437] The static surface tensions of the prepared inks M1 to M15 and C1 to C3 at 25° C. were measured using a static surface tensiometer (CBVP-Z, manufactured by Kyowa Interface Science Co., Ltd.) using the Wilhelmy method. The measured values ​​(unit: mN / m) are shown in Table IV.

[0438] [evaluate]

[0439] <Injection Stability>

[0440] The prepared inks M1-M15 and C1-C3 were loaded into a Konica Minolta independently driven inkjet head (360 npi, 6 pL discharge volume, 1024 nozzles). A continuous discharge test was conducted for 30 minutes using a flash-synchronized droplet observation device. The injection stability was then evaluated according to the following criteria.

[0441] (Benchmark)

[0442] ◯: Of the 256 nozzles evaluated, all 256 nozzles discharged normally.

[0443] Δ: Among the 256 nozzles evaluated, one or more and less than five nozzles were observed to have abnormal discharge.

[0444] ×: Among the 256 nozzles evaluated, 5 or more abnormal discharge nozzles were observed.

[0445] <Ink Storage Stability>

[0446] The prepared inks M1 to M15 and C1 to C3 were stored at 60° C. for 2 weeks, and then their average particle sizes were measured using a particle size analyzer (Zetasizer Nano S-90). The storage stability of the inks was then evaluated according to the following criteria.

[0447] (Benchmark)

[0448] ◯: The difference between the average particle size after storage at 60°C for 2 weeks and the average particle size before storage at 60°C for 2 weeks is less than 10 nm.

[0449] Δ: The difference between the average particle size after storage at 60°C for 2 weeks and the average particle size before storage at 60°C for 2 weeks is 10 nm or more and less than 30 nm.

[0450] ×: The difference between the average particle size after storage at 60°C for 2 weeks and the average particle size before storage at 60°C for 2 weeks is 30 nm or more.

[0451] [Table 3]

[0452]

[0453] [Table 4]

[0454]

[0455] As shown in the above results, it was confirmed that the treatment liquid of the present invention having a dynamic surface tension in the range of 35 to 45 mN / m at a surface life of 15 ms is excellent in injection stability and storage stability.

[0456] [Printing test 1]

[0457] Using an ink set having the treatment liquid and ink prepared as described above and having the combinations shown in Tables V to X below, a printing test was carried out by the following method.

[0458] As the recording medium M, a PET film (FE2001, thickness 50 μm, manufactured by Futamura Chemical Co., Ltd.) was prepared.

[0459] Prepare a scanner printer equipped with two Konica Minolta independently driven inkjet heads (360npi, 6pL or 14pL discharge volume, 1024 nozzles) (see Figure 4 ), the first-recording head H1 is filled with each treatment liquid, and the second-recording head H2 is filled with each ink. Then, a 720×720 dpi image is divided into four images (180×180 dpi) in the scanning direction X and the transport direction Y, respectively. In a four-pass mode, where one print area is printed four times, printing is always performed in a single direction, in the direction of the first-recording treatment liquid.

[0460] The transport speed of the carriage C was set to 300 mm / sec, and no drying process was provided between the processing liquid and the ink recording. The printing test was conducted in an environment of 25°C and 50% RH.

[0461] The recording setting for the treatment liquid was 6 pL of liquid and a maximum printing rate of 33%, and the image was applied in accordance with the image area of ​​the ink. Furthermore, the recording setting for the ink was 14 pL of liquid and a maximum printing rate of 100%. It should be noted that in these settings, the amount of treatment liquid applied to the solid area was 1.7 g / m 2 The ink application amount of the solid part is 11.9g / m 2 The ratio of the ink application amount to the treatment liquid application amount in the solid portion (ink application amount / treatment liquid application amount) was 7.0 times.

[0462] [Determination of drying rate of treatment liquid]

[0463] In Printing Test 1, the time from application of the treatment liquid to application of ink was measured and found to be 0.2 seconds. The drying rate of the treatment liquid was measured 0.2 seconds after application of the treatment liquid in the aforementioned 25°C, 50% RH environment and found to be less than 1%. The drying rate of the treatment liquid was calculated by measuring the change in mass of the treatment liquid.

[0464] [Drying of recorded materials]

[0465] In the printing test 1, after the ink was applied, the PET film was placed in a dryer set at 90° C. and heated and dried for 5 minutes to obtain an image recorded material.

[0466] It should be noted that Figure 5The results of measuring the dynamic surface tension of the treatment liquid and the ink in Ink Set 1 at 25°C with a surface lifetime of 10 ms to 1000 ms are shown. In addition, Figure 6 The results of measuring the dynamic surface tension of the treatment liquid and the ink in Ink Set 44 at 25°C with a surface lifetime of 10 ms to 1000 ms are shown.

[0467] [Evaluation]

[0468] <Defect of hollowed-out characters>

[0469] According to the method described above, hollowed-out characters of Chinese characters "口, 四, 日, 回, 因, 困, 固, 国, 目, 図, 國" are printed in MS Mincho font of 5 pt (point) and 7 pt, and the printed character images are observed with the naked eye. The text quality is evaluated according to the following criteria.

[0470] (Criteria)

[0471] ○: All 5-pt hollowed-out characters are clearly recorded down to the details.

[0472] Δ: Only part of the 5-pt hollowed-out characters can be recognized, but all 7-pt hollowed-out characters can be recognized.

[0473] ×: There are characters that cannot be recognized among the 7-pt hollowed-out characters.

[0474] <Exudation of thin lines>

[0475] By the method described above, a thin line with a width of 3 pixels is recorded, and the exudation of the thin line is observed and evaluated with the naked eye according to the following criteria.

[0476] (Criteria)

[0477] ○: The thin line is thin and printed in a straight line.

[0478] Δ: The thin line bulges at various places and is printed in a slightly deformed shape.

[0479] ×: The line is thick, exudes, and is deformed.

[0480] <Spots (mottles) in the solid part> ​​​​​​​​​​Δ: When observing from a distance of 15 cm, density unevenness was observed in a portion of the image, but when observing from a distance of 30 cm, no density unevenness was observed.

[0485] ×: Density unevenness was observed in the image observed from a position 30 cm away.

[0486] <Adhesion>

[0487] A solid image of 5 cm x 5 cm was recorded using the method described above, and the printed surface was rubbed with a fingernail. The adhesion was evaluated based on the following criteria.

[0488] (Benchmark)

[0489] ○: The printed surface does not change or peel even when rubbed with a fingernail.

[0490] Δ: The printed surface was scratched when rubbed with a fingernail, and some parts of the printed surface peeled off.

[0491] ×: The printed surface peels off when rubbed with fingernails.

[0492] [Table 5]

[0493]

[0494] [Table 6]

[0495]

[0496] [Table 7]

[0497]

[0498] [Table 8]

[0499]

[0500] [Table 9]

[0501]

[0502] [Table 10]

[0503]

[0504] As shown in the above results, it was confirmed that the ink set of the present invention suppressed image defects and had excellent adhesion to the substrate, compared with the ink set of the comparative example.

[0505] [Printing Test 2]

[0506] Two independently driven heads of a piezoelectric inkjet head (360 dpi, discharge volume 6 pL) manufactured by Konica Minolta were arranged so that the nozzles were different from each other to prepare a 720 dpi × 720 dpi head module. Figure 1 In the illustrated single-pass printer, the nozzle rows are arranged so as to be perpendicular to the conveyance direction.

[0507] The inkjet head of the head assembly provided in the treatment liquid application section was filled with the treatment liquid T1 obtained above, and the inkjet head of the head assembly provided in the ink application section was filled with the ink M1 obtained above. In this manner, a single-pass inkjet recording apparatus capable of recording ink set 1 described in Table V was constructed.

[0508] Using the inkjet recording apparatus, the same image as in Printing Test 1 was recorded under the recording conditions listed in Table XI, and the results were evaluated using the same indicators as in Printing Test 1. Furthermore, a PET film (FE2001, 50 μm thickness, manufactured by Futamura Chemical Co., Ltd.) was prepared as the recording medium M. The transport speed during recording was set to 300 mm / sec.

[0509] Note that the time from application of the treatment liquid to application of the ink is adjusted by waiting for a predetermined time after the recording medium passes through the treatment liquid application section and then moving the recording medium to the ink application section.

[0510] The drying rate of the treatment liquid was calculated by measuring the rate of change in mass of the treatment liquid applied to the PET film to determine the amount of solvent volatilized from the time the treatment liquid was applied to the ink. The amounts of treatment liquid and ink applied were adjusted by varying the droplet size and printing rate, respectively. The evaluation results are shown in Table XI.

[0511] It should be noted that in Table XI, "≤1" means "less than 1%."

[0512] [Table 11]

[0513]

[0514] Industrial Applicability

[0515] The present invention can be used for an ink set and an inkjet recording method that suppress image defects and have excellent adhesion to a substrate.

[0516] Explanation of symbols

[0517] 1 Recording device

[0518] 10 Treatment liquid applying unit

[0519] 11 inkjet heads

[0520] 12 treatment liquid droplets

[0521] 20Ink application unit

[0522] 21 inkjet heads

[0523] 22 ink droplets

[0524] 23 Second Drying Section

[0525] 30 delivery roller

[0526] 40 winding rollers

[0527] C treatment liquid layer

[0528] FBase material

[0529] P picture record

[0530] R ink layer

[0531] 50 canned food packaging materials

[0532] 51 tinplate base material

[0533] 52 Thermosetting resin layer (primer coating)

[0534] 53 treatment liquid layer

[0535] 54 ink layers

[0536] 55 thermosetting resin layer (top coating)

[0537] C carriage

[0538] H1 nozzle

[0539] H2 nozzle

[0540] X scanning direction

[0541] Y conveying direction

[0542] M recording medium (substrate)

Claims

1. An ink set comprising ink and a treatment liquid, wherein: The ink comprises a pigment, resin particles, a water-soluble solvent with a boiling point in the range of 150-250° C., and a surfactant. The treatment liquid comprises a polyvalent metal salt, a water-soluble solvent with a boiling point in the range of 150-250° C., and a surfactant. At 25° C., the static surface tension of the ink is higher than the static surface tension of the treatment liquid by more than 5 mN / m, At 25° C., the dynamic surface tension of the ink at a surface life of 15 ms is higher than the dynamic surface tension of the treatment liquid at a surface life of 15 ms by more than 5 mN / m. The dynamic surface tension of the ink at a surface life of 15 ms is in the range of 35 to 45 mN / m, and The dynamic surface tension of the treatment liquid when the surface life is 15ms is in the range of 25-35mN / m.

2. The ink set according to claim 1, wherein: The pigment is dispersed by an anionic polymer dispersant.

3. The ink set according to claim 1 or 2, wherein: The ink contains the resin fine particles having an agglomeration property of 0.2 or less with a 0.15% by mass aqueous solution of calcium acetate monohydrate in an amount within a range of 3 to 15% by mass.

4. The ink set according to claim 1 or 2, wherein: The resin fine particles include a water-dispersible polyester resin having a sulfonic acid group.

5. The ink set according to claim 1 or 2, wherein: At 25° C., the dynamic surface tension of the treatment liquid in an undried state at a surface life of 15 ms is defined as A, and the dynamic surface tension of the treatment liquid at a surface life of 15 ms when the drying rate is 30% is defined as B, and the following formula (I) is satisfied: Formula (I): (BA)≤5mN / m.

6. The ink set according to claim 1 or 2, wherein: The treatment liquid contains a surfactant that is not contained in the ink.

7. An inkjet recording method for recording an image using the ink set according to any one of claims 1 to 6, wherein: After the treatment liquid is applied to the substrate, the ink is applied to the area where the treatment liquid is applied while the substrate is wetted with the treatment liquid without undergoing a heating and drying step.

8. The inkjet recording method according to claim 7, wherein The ink is applied to the region to which the treatment liquid is applied in a state where the drying rate of the treatment liquid is 30% or less.

9. The inkjet recording method according to claim 7 or 8, wherein After the treatment liquid is applied to the substrate, the ink is applied to the area where the treatment liquid has been applied within 10 seconds.

10. The recording method according to claim 7 or 8, wherein: The amount of the ink applied per unit area is in a range of 2 to 25 times the amount of the treatment liquid applied.

Images