Ink set

Abstract

To provide an ink set which suppresses image defects, has high quality and is excellent in adhesion to a base material.SOLUTION: There is provided an ink set, wherein an ink contains a pigment, resin fine particles, a water-soluble solvent and a surface active agent, and a treatment agent contains a polyvalent metal salt, a water-soluble solvent and a surface active agent. The water-soluble solvents of the ink and the treatment liquid have SP values of 24 (J / cm3)1 / 2 or more and boiling points of 150 to 250°C. The ink and the treatment liquid contain specific surface active agents, and the contents of the surface active agent in the ink and the surface active agent in the treatment liquid are within a specific range. The static surface tension of the ink at 25°C is higher than the static surface tension of the treatment liquid by 5 mN / m or more, the dynamic surface tension at the surface lifetime of 15 ms of the ink is higher than the dynamic surface tension of the treatment liquid by 5 mN / m or more, and the dynamic surface tension of the ink is within the range of 35 to 45 mN / m, and the dynamic surface tension of the treatment liquid is within the range of 25 to 35 mN / m.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an ink set, and more particularly to an ink set that suppresses image defects, provides high image quality, and has excellent adhesion to a substrate. [Background technology]

[0002] The inkjet recording method allows images to be produced simply and inexpensively, and has therefore been applied to various printing fields, including photography, various types of printing, marking, and special printing such as color filters. In particular, the inkjet recording method allows digital printing without using a plate, and is therefore particularly suitable for applications in which a variety of images are formed in small quantities.

[0003] In such inkjet recording methods, a two-liquid inkjet recording method is known in which a treatment liquid (also called a "pretreatment liquid" or "primer") containing an aggregating agent such as an organic acid or a polyvalent metal salt is applied to a substrate in advance, and in a subsequent step, the pigment contained in the ink is aggregated and pinned by the organic acid or the polyvalent metal salt, thereby obtaining a high-quality image recording.

[0004] While two-liquid inkjet recording methods can prevent ink bleeding and the like, they have the problem that if the time between the application of the treatment liquid and the ink is not properly controlled, the ink will aggregate too much, resulting in poor image gloss. For this reason, a technique has been disclosed that improves printing stability and recording productivity on non-absorbent substrates by specifying the amount of treatment liquid applied and shortening the time between the application of the treatment liquid and the ink (see, for example, Patent Document 1). However, unless the static surface tension and dynamic surface tension of the treatment liquid and ink are appropriately controlled, image defects such as bleeding of outline characters and thin lines, beading, and mottle may occur depending on the combination of treatment liquid and ink, making it difficult to achieve high image quality. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-221943 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in view of the above problems and circumstances, and the problem to be solved by the present invention is to provide an ink set that suppresses image defects, produces high image quality, and has excellent adhesion to substrates. [Means for solving the problem]

[0007] In the course of investigating the causes of the above problems in order to solve the above problems, the inventors discovered that it is possible to provide an ink set that can achieve high image quality by controlling the static surface tension and dynamic surface tension of the treatment liquid and ink within specific ranges, and thus arrived at the present invention. That is, the above-mentioned problems of the present invention are solved by the following means.

[0008] 1. An ink set including an ink and a treatment liquid, The ink contains pigment, resin particles, and an SP value of 24 (J / cm 3 ) 1 / 2 or more and containing a water-soluble solvent and a surfactant having a boiling point in the range of 150 to 250°C, The treatment liquid contains a polyvalent metal salt and an SP value of 24 (J / cm 3 ) 1 / 2 or more and containing a water-soluble solvent and a surfactant having a boiling point in the range of 150 to 250°C, the surfactant of the ink is an acetylene glycol surfactant and a polyether-modified silicone surfactant, or a polyether-modified silicone surfactant, the content of the surfactant in the ink is within a range of 0.1 to 2.0% by mass, the surfactant in the treatment liquid is a polyether-modified silicone surfactant, and the content of the surfactant in the treatment liquid is within a range of 0.1 to 2.0 mass %, 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; At 25°C, the dynamic surface tension of the ink after a surface life of 15 ms is higher by 5 mN / m or more than the dynamic surface tension of the treatment liquid after a surface life of 15 ms; The dynamic surface tension of the ink after 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 after a surface life of 15 ms is in the range of 25 to 35 mN / m; An ink set used in an inkjet recording method in which the treatment liquid is applied to a substrate, and then the ink is applied to an area to which the treatment liquid has been applied while the treatment liquid is still wet, without undergoing a heat drying process.

[0009] 2. The content of the water-soluble solvent in the ink is within a range of 5 to 40% by mass, 2. The ink set according to item 1, wherein the content of the water-soluble solvent in the treatment liquid is within a range of 10 to 45% by mass.

[0010] 3. The ink set according to item 1, wherein the pigment is dispersed with an anionic polymer dispersant.

[0011] 4. The ink set according to claim 1, wherein the ink contains 3 to 15% by mass of the resin microparticles having an agglomeration property of 0.2 or less with a 0.15% by mass aqueous solution of calcium acetate monohydrate.

[0012] 5. The ink set according to item 1, wherein the resin fine particles contain a water-dispersible polyester resin having a sulfonic acid group.

[0013] 6. The dynamic surface tension of the treatment liquid in a wet state at 25°C and with a surface life of 15 ms is A, 2. The ink set according to item 1, wherein when the treatment liquid is dried and the dynamic surface tension at a surface life of 15 ms when the drying rate of the treatment liquid is 30% is B, the following formula (I) is satisfied: Formula (I): (BA)≦5 mN / m

[0014] 7. The ink set according to claim 1, wherein the treatment liquid contains a surfactant that is not contained in the ink.

[0015] 8. The area to which the treatment liquid has been applied is treated with the treatment liquid in a state where the drying rate of the treatment liquid is 30% or less. 2. The ink set according to claim 1, wherein the ink is applied.

[0016] 9. The ink set according to claim 1, wherein the ink is applied to the area where the treatment liquid has been applied within 10 seconds after the treatment liquid has been applied to the substrate.

[0017] 10. The ink set according to any one of items 1 to 9, wherein the amount of the ink applied per unit area is within a range of 2 to 25 times the amount of the treatment liquid applied. [Effects of the Invention]

[0018] By the above means of the present invention, it is possible to provide an ink set that suppresses image defects and has excellent adhesion to the substrate. The mechanism by which the effects of the present invention are manifested or the mechanism of action is not clear, but is speculated as follows. In the wet-on-wet recording method, in which ink is applied while the processing liquid is still wet, it is necessary to thin out the processing liquid, but since the processing liquid needs to instantly wet and spread evenly while reducing the printing rate, it is better for the dynamic surface tension of the processing liquid to be low.However, if the dynamic surface tension of the ink is too low, the cut-out characters will be crushed, so it is better not to make it too low. Therefore, in the present invention, first, as a configuration that allows images to be recorded while ensuring substrate adhesion, the ink contains a pigment, resin fine particles, a water-soluble solvent with a boiling point in the range of 150 to 250°C, and a surfactant, and further, in order to thicken and aggregate the ink and achieve high image quality, the treatment 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. Furthermore, the relationship between the static and dynamic surface tensions of the treatment liquid and the ink is specified within the above ranges. That is, by making the static and dynamic surface tensions of the treatment liquid lower than those of the ink, the ink aggregates and thickens while appropriately diffusing into the treatment liquid, which prevents bleeding of outline characters and thin lines and suppresses image defects such as beading and mottle, thereby achieving high image quality. Furthermore, by setting the dynamic surface tension of the treatment liquid and the ink within the above ranges, it is possible to obtain high jetting stability and storage stability while ensuring high wettability to the substrate. [Brief explanation of the drawings]

[0019] [Figure 1] Schematic diagram showing an example of a recording apparatus preferred for the present invention. [Figure 2] 1 is a cross-sectional view showing a schematic configuration of an image recording material according to the present invention; [Figure 3] Cross-section of packaging material for canned food [Figure 4] Schematic diagram showing the inkjet head used in the examples [Figure 5] Graph showing the dynamic surface tension of ink set 1 in the examples [Figure 6] A diagram showing the dynamic surface tension of ink set 44 in the example. DETAILED DESCRIPTION OF THE INVENTION

[0020] The ink set of the present invention is an ink set containing ink and a treatment liquid, wherein the ink contains a pigment, resin fine particles, and an SP value of 24 (J / cm 3 ) 1 / 2 The treatment liquid contains a water-soluble solvent having a boiling point of 150 to 250°C or higher and a surfactant, and the treatment liquid contains a polyvalent metal salt and an SP value of 24 (J / cm 3 ) 1 / 2The ink contains a water-soluble solvent having a boiling point of 150 to 250°C or higher and a surfactant, wherein the surfactant in the ink is an acetylene glycol surfactant and a polyether-modified silicone surfactant, or a polyether-modified silicone surfactant, and the content of the surfactant in the ink is within a range of 0.1 to 2.0 mass %, the surfactant in the treatment liquid is a polyether-modified silicone surfactant, and the content of the surfactant in the treatment liquid is within a range of 0.1 to 2.0 mass %, and the static surface tension of the ink at 25°C is equal to or greater than that of the static surface tension of the treatment liquid. the dynamic surface tension of the ink during a surface life of 15 ms is at least 5 mN / m higher than the dynamic surface tension of the treatment liquid during a surface life of 15 ms at 25°C, the dynamic surface tension of the ink during 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 during a surface life of 15 ms is in the range of 25 to 35 mN / m, and the ink is used in an inkjet recording method in which, after the treatment liquid has been applied to a substrate, the ink is applied in a wet state to an area to which the treatment liquid has been applied without undergoing a heat drying step. This feature is a technical feature common to or corresponding to each of the following embodiments.

[0021] In one embodiment of the present invention, the pigment is preferably dispersed with an anionic polymer dispersant, as this provides excellent dispersibility and allows pinning to occur by appropriately reacting with the treatment liquid.

[0022] It is preferable that the ink contains 3 to 15 mass % of the resin microparticles, which have an aggregation property of 0.2 or less with 0.15 mass % aqueous solution of calcium acetate monohydrate. By using resin microparticles with low aggregation property, high wettability to the substrate is ensured while high ejection stability is obtained, resulting in higher image quality and excellent adhesion to the substrate.

[0023] The resin fine particles preferably contain a water-dispersible polyester resin having a sulfonic acid group, in that high adhesion to the substrate can be obtained.

[0024] Furthermore, when the dynamic surface tension of the treatment liquid in a wet state at 25°C with a surface life of 15 ms is defined as A, and the dynamic surface tension of the treatment liquid after drying with a drying rate of 30% with a surface life of 15 ms is defined as B, it is preferable that the following formula (I) is satisfied: Formula (I): (BA)≦5 mN / m In the wet-on-wet printing method, the dynamic surface tension does not change even when the processing liquid dries to a certain extent, which improves robustness against temperature and humidity conditions during printing.

[0025] It is preferable that the treatment liquid contains a surfactant that is not contained in the ink. By adding a surfactant that destabilizes the dispersion stability of the ink to the treatment liquid in this way, it is possible to further increase the coagulation properties.

[0026] The ink set of the present invention is used in an inkjet recording method in which, after the treatment liquid has been applied to a substrate, the ink is applied to the area to which the treatment liquid has been applied while the treatment liquid is still wet, without undergoing a heat drying step. By using the ink set in this wet-on-wet recording method, the ink and treatment liquid mix together, ensuring high wettability to the substrate while achieving high ejection stability, resulting in high image quality and excellent adhesion to the substrate.

[0027] In particular, it is preferable to apply the ink to the area to which the treatment liquid has been applied when the drying rate of the treatment liquid is 30% or less, as this allows the ink and treatment liquid to mix appropriately and more significantly exhibit the effects of the present invention.

[0028] It is preferable to apply the ink to the area where the treatment liquid has been applied within 10 seconds after the treatment liquid has been applied to the substrate, as this prevents the treatment liquid from penetrating into an absorbent substrate or from repelling on a non-absorbent substrate, thereby achieving higher image quality.

[0029] It is preferable that the amount of ink applied per unit area is within the range of 2 to 25 times the amount of treatment liquid applied, in terms of achieving higher image quality.

[0030] The present invention, its components, and embodiments and modes for carrying out the present invention will be described below. In this application, the symbol "to" is used to mean that the numerical values ​​before and after it are included as lower and upper limits.

[0031] [Outline of the ink set of the present invention] The ink set of the present invention is an ink set containing ink and a treatment liquid, wherein the ink contains a pigment, resin fine particles, and an SP value of 24 (J / cm 3 ) 1 / 2 The treatment liquid contains a water-soluble solvent having a boiling point of 150 to 250°C or higher and a surfactant, and the treatment liquid contains a polyvalent metal salt and an SP value of 24 (J / cm 3 ) 1 / 2 The ink contains a water-soluble solvent having a boiling point of 150 to 250°C or higher and a surfactant, wherein the surfactant in the ink is an acetylene glycol surfactant and a polyether-modified silicone surfactant, or a polyether-modified silicone surfactant, and the content of the surfactant in the ink is within a range of 0.1 to 2.0 mass %, the surfactant in the treatment liquid is a polyether-modified silicone surfactant, and the content of the surfactant in the treatment liquid is within a range of 0.1 to 2.0 mass %, and the static surface tension of the ink at 25°C is equal to or greater than that of the static surface tension of the treatment liquid. the dynamic surface tension of the ink during a surface life of 15 ms is at least 5 mN / m higher than the dynamic surface tension of the treatment liquid during a surface life of 15 ms at 25°C, the dynamic surface tension of the ink during 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 during a surface life of 15 ms is in the range of 25 to 35 mN / m, and the ink is used in an inkjet recording method in which, after the treatment liquid has been applied to a substrate, the ink is applied in a wet state to an area to which the treatment liquid has been applied without undergoing a heat drying step.

[0032] The "treatment liquid" and "ink" referred to in the present invention refer to a "treatment liquid (also called a "pretreatment liquid" or "primer")" and an "ink (also called a "water-based ink" or "aqueous ink")" that use at least water as a solvent. In both cases, 60% by mass or more of the solvent used is water.

[0033] <Static surface tension> In the present invention, the term "static surface tension" refers to the surface tension when the liquid surface approaches an equilibrium state as the components of the ink or treatment liquid diffuse over the course of the surface life. The static surface tension of the ink or treatment liquid can be measured using a platinum plate with an automatic surface tensiometer (model "CBVP-Z" manufactured by Kyowa Interface Science Co., Ltd.) Unless otherwise specified, the static surface tension in this specification is the static surface tension measured at 25°C. In the ink set of the present invention, the static surface tension of the ink is at least 5 mN / m higher than the static surface tension of the treatment liquid at 25° C., and is preferably higher by a range of 6 to 12 mN / m.

[0034] Specifically, at 25° C., the static surface tension of the ink is preferably within the range of 25 to 35 mN / m, and the static surface tension of the treatment liquid is preferably within the range of 20 to 30 mN / m. In the case where there are multiple types of ink, it is sufficient that the difference between the static surface tension of the ink having the lowest static surface tension and the static surface tension of the treatment liquid falls within the above range.

[0035] <Dynamic surface tension> In the present invention, the term "dynamic surface tension" refers to the surface tension immediately after the formation of a liquid surface (gas-liquid interface) when the liquid surface is in a non-equilibrium state, and is a value measured at 25°C by the maximum bubble pressure method. The "surface lifetime" is the time elapsed since the formation of a liquid surface, i.e., the lifetime of a bubble generated in the maximum bubble pressure method. It is also called the bubble lifetime and refers to the time from when a new interface is generated within the tip of the probe of the dynamic surface tensiometer until the maximum bubble pressure is reached. The dynamic surface tension of the treatment liquid or ink can be measured using a dynamic surface tensiometer, such as a bubble pressure dynamic surface tensiometer (manufactured by KRUSS, model "BP100"). Unless otherwise specified, the dynamic surface tension in this specification is the dynamic surface tension measured at 25° C. for 15 ms using the maximum bubble pressure method.

[0036] In the ink set of the present invention, the dynamic surface tension of the ink at 25°C after a surface life of 15 ms (also referred to as "dynamic surface tension A") is at least 5 mN / m higher than the dynamic surface tension of the treatment liquid after a surface life of 15 ms, and is preferably higher by a range of 7 to 15 mN / m. In the case where there are multiple types of ink, it is sufficient that the difference in dynamic surface tension between the ink with the lowest dynamic surface tension and the treatment liquid falls within the above range.

[0037] The dynamic surface tension of the treatment liquid after a surface life of 15 ms is in the range of 25 to 35 mN / m, and preferably in the range of 27 to 33 mN / m. Furthermore, the dynamic surface tension of the ink during a surface life of 15 ms is in the range of 35 to 45 mN / m, and preferably in the range of 37 to 43 mN / m.

[0038] In order to set the static surface tension and dynamic surface tension of the treatment liquid within the above ranges, the type and content of the surfactant, the type and content of the water-soluble solvent, and the type and content of the coagulant can be controlled. Specifically, it is preferable to use various polyether-modified silicones and / or acetylene glycol surfactants as surfactants contained in the treatment liquid, and to set the content within the range of 0.1 to 2.0 mass %. In addition, it is preferable to use a water-soluble solvent having an SP value of 24 (J / cm 3 ) 1 / 2 It is preferable to use a water-soluble solvent having a boiling point in the range of 150°C to 250°C and to set the content thereof in the range of 5 to 40 mass %.

[0039] In order to set the static surface tension and dynamic surface tension of the ink within the above ranges, it is possible to control 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 microparticles, and the type and content of the additives, for example. Specifically, it is preferable to use various polyether-modified silicones and / or acetylene glycol surfactants as surfactants contained in the ink, and to set the content within the range of 0.1 to 2.0 mass %. The water-soluble solvent used should have an SP value of 24 (J / cm 3 ) 1 / 2 It is preferable to use a water-soluble solvent having a boiling point in the range of 150°C to 250°C, with its content in the range of 5 to 40% by mass. Furthermore, it is preferable to use various low-molecular-weight dispersants, nonionic polymer dispersants, anionic polymer dispersants, or resin-coated pigment dispersions as appropriate, as the pigment dispersant. Furthermore, it is preferable to use resin particles such as polyester resin, acrylic resin, styrene-acrylic resin, and urethane resin, with their content in the range of 3 to 15% by mass.

[0040] <Dynamic surface tension after 30% drying> Furthermore, the ink set of the present invention preferably satisfies the following formula (I), where A is the dynamic surface tension of the treatment liquid in a wet state at 25°C with a surface life of 15 ms, and B is the dynamic surface tension of the treatment liquid with a drying rate of 30% with a surface life of 15 ms. Formula (I): (BA)≦5 mN / m By satisfying formula (I) in this way, in a wet-on-wet recording method, the change in dynamic surface tension can be reduced even when the treatment liquid dries to a certain extent, thereby improving robustness against temperature and humidity conditions during recording. Here, "dynamic surface tension A" refers to the dynamic surface tension of the treatment liquid before drying, i.e., in an undried state, at 25°C with a surface life of 15 ms, as described below, and is a value measured at 25°C by the maximum bubble pressure method described above. Furthermore, "dynamic surface tension B" refers to the dynamic surface tension of the treatment liquid after drying and with a surface life of 15 ms when the treatment liquid has been dried to a drying rate of 30%. Specifically, 100 g of treatment liquid is weighed into a shallow container and dried in a reduced-pressure environment at 25°C until the liquid mass is 70 g. The dynamic surface tension of the treatment liquid at this point is measured using the maximum bubble pressure method, and this is defined as the dynamic surface tension B after 30% drying. The difference "(BA)" is calculated from the dynamic surface tension B after 30% drying measured in this way and the dynamic surface tension A.

[0041] [Processing liquid] The treatment liquid according to the present invention can have the function of accelerating ink image formation, improving the physical properties of the treatment liquid layer and the ink layer, and improving image quality by aggregating or thickening the ink when an image is recorded on a substrate by inkjet printing.

[0042] The treatment liquid according to the present invention contains at least a polyvalent metal salt, a water-soluble solvent having a boiling point in the range of 150 to 250° C., and a surfactant. The treatment liquid may also contain water.

[0043] <Polyvalent metal salts> The treatment liquid according to the present invention contains a material that causes agglomerates when it comes into contact with ink, i.e., an aggregating agent that is a polyvalent metal salt, which enhances the interaction with the ink and enables the ink dots to be more firmly fixed.

[0044] The polyvalent metal salt can aggregate anionic components (usually coloring materials or pigments, etc., as described below) in the ink by salting out.

[0045] The polyvalent metal salt may be a salt of a metal having a valence of 2 or more. The type of metal (cation) constituting the polyvalent metal salt is not particularly limited. For example, Ca 2+ , Cu 2+ , Ni 2+ , Mg 2+ , Zn 2+ , Ba 2+ Divalent metal ions such as Al3+ , Fe 3+ , Cr 3+ , Y 3+ Trivalent metal ions such as Zr 4+ and the like. The type of salt constituting the polyvalent metal salt is not particularly limited, and known salts such as carbonates, sulfates, nitrates, hydrochlorides, organic acid salts, borates, phosphates, etc. Particularly preferred examples of the polyvalent metal salt include calcium chloride, magnesium chloride, calcium nitrate, magnesium nitrate, magnesium acetate, calcium acetate, magnesium lactate, and calcium or magnesium salts of carboxylic acids such as calcium pantothenate.

[0046] <Organic acid> In addition to the polyvalent metal salt, the treatment liquid according to the present invention may further contain an organic acid as a flocculating agent. The organic acid can flocculate anionic components in the ink by changing the pH. As the organic acid, a monocarboxylic acid is preferred, as it does not weaken the coagulating force of the polyvalent metal salt.

[0047] The organic acid is capable of aggregating pigments that may be contained in the ink, which will be described later. Examples of the organic acid include formic acid, acetic acid, propionic acid, isobutyric acid, and benzoic acid.

[0048] It is preferable to use an organic acid that is not completely neutralized with a base. Neutralization with a base means that the acidic group of the acid is ionic bonded to another positively charged element or compound (e.g., an inorganic compound such as a metal). Furthermore, not completely neutralized means that among the acidic groups possessed by the organic acid, there are acidic groups that do not form the ionic bond. Furthermore, the use of an organic acid makes it easier to maintain the storage stability of the treatment solution, and makes it less likely that blocking will occur after the treatment solution is applied and dried. From the above perspective, preferred organic acids include formic acid, acetic acid, propionic acid, and benzoic acid.

[0049] <Inorganic acid> In addition to the polyvalent metal salt, the treatment liquid according to the present invention may further contain an inorganic acid as a flocculating agent, which can flocculate the anionic components in the ink by changing the pH.

[0050] The inorganic acid is capable of aggregating pigments that may be contained in the ink, which will be described later. Examples of the inorganic acid include hydrochloric acid, nitric acid, sulfuric acid, and sulfamic acid.

[0051] The content of the polyvalent metal salt is preferably in the range of 0.5 to 20% by mass, and more preferably in the range of 1 to 10% by mass, relative to 100% by mass of the total mass of the treatment liquid, which is preferable from the viewpoint of effectively aggregating the anionic components in the ink and achieving a balance between image quality and hot water resistance. When an organic acid is added, the content of the organic acid is preferably in the range of 0.1 to 10% by mass, and more preferably in the range of 1 to 3% by mass, relative to 100% by mass of the total mass of the treatment liquid. When an inorganic acid is added, the content of the inorganic acid is preferably in the range of 0.1 to 10% by mass, and more preferably in the range of 1 to 3% by mass, relative to 100% by mass of the total mass of the treatment liquid.

[0052] The content of the polyvalent metal salt or organic acid in the aqueous solution can be measured by a known method, for example, by ICP emission spectrometry in the case of the polyvalent metal salt, or by high performance liquid chromatography (HPLC) in the case of the organic acid.

[0053] When an organic acid is used, the amount of the organic acid applied is preferably an amount that adjusts the pH of the treatment liquid to be equal to or less than the neutralization equivalent of the anionic component contained in the ink. Furthermore, when the anionic component is a compound having a carboxy group, the first dissociation constant of the organic acid is preferably 3.5 or less, from the viewpoint of further reducing the occurrence of image bleeding.

[0054] <Water-soluble solvent> The water-soluble solvent contained in the treatment liquid according to the present invention is a water-soluble solvent having a boiling point in the range of 150 to 250°C. Examples of such water-soluble solvents include alcohols, polyhydric alcohols, amines, amides, glycol ethers, and 1,2-alkanediols having 4 or more carbon atoms. In addition, the SP value is 24 (J / cm 3 ) 1 / 2 It is preferable to use the above water-soluble solvents. SP value is 24 (J / cm 3 ) 1 / 2 The use of such a water-soluble solvent lowers the cloud point of the treatment liquid, which allows the treatment liquid to be heated to a temperature equal to or higher than its cloud point during the ink drying process, thereby producing an image with particularly good adhesion to non-absorbent substrates.

[0055] In the present invention, the SP value is referred to as the solubility parameter. The SP value in the present invention is a value calculated by the Fedors method. It is determined from the molar heat of vaporization of the water-soluble solvent and the molar volume of the water-soluble solvent at 25°C. The unit of the SP value is generally cal, but when converting to the SI unit system, it is also possible to use (cal / cm 3 ) 1 / 2 =2.046×10 3 (J / m 3 ) 1 / 2 In the following description, the unit of SP value may be omitted, but the SP value is expressed as (J / cm 3 ) 1 / 2 It is a value expressed in units of .

[0056] The SP value is 24 (J / cm 3 ) 1 / 2 Examples of the water-soluble solvent that satisfies the above conditions and has a boiling point of 150° C. to 250° C. include polyhydric alcohols having 2 to 8 carbon atoms and polyalkylene glycols.

[0057] Examples of polyhydric alcohols having 2 to 8 carbon atoms include 1,2-ethanediol (SP value: 30.3, boiling point: 197°C), 1,2-propanediol (SP value: 28.0, boiling point: 188°C), 1,3-propanediol (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), and 2,3-butanediol (SP value: 2 9.9, 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.

[0058] Examples of polyalkylene glycols include diethylene glycol (SP value: 30.6, boiling point: 244°C) and dipropylene glycol (SP value: 27.2, boiling point: 230°C).

[0059] The treatment liquid may contain one or a combination of two or more selected from these water-soluble solvents.

[0060] The ink may contain at least one water-soluble solvent having a boiling point of 150°C to 250°C, and may also contain alcohols other than those mentioned above, polyhydric alcohols, amines, amides, glycol ethers, and 1,2-alkanediols having 4 or more carbon atoms.

[0061] Examples of solvents other than water-soluble solvents with 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).

[0062] The total content of the water-soluble solvent is preferably in the range of 5 to 40% by mass, and more preferably in the range of 10 to 40% by mass, relative to 100% by mass of the total mass of the treatment liquid.

[0063] <Surfactant> The surfactant contained in the treatment liquid according to the present invention can improve the ejection stability of the treatment liquid from the nozzle and control the spreading of droplets that land on the recording medium (enlargement of the dot diameter).

[0064] The surfactant that can be used in the treatment liquid of the present invention is not particularly limited, but when an anionic compound is contained as another component of the ink, the ionicity of the surfactant is preferably anionic, nonionic, or betaine type.

[0065] In the present invention, fluorine-based or silicone-based surfactants having a high static surface tension reducing ability, anionic surfactants such as dioctyl sulfosuccinate having a high dynamic surface tension reducing ability, and nonionic surfactants such as relatively low molecular weight polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, acetylene glycols, Pluronic surfactants (Pluronic is a registered trademark), and sorbitan derivatives are preferably used. It is also preferable to use a fluorine-based or silicone-based surfactant in combination with a surfactant having a high dynamic surface tension reducing ability.

[0066] Adding a silicone-based or fluorine-based surfactant as the surfactant is preferred in that it can further suppress ink mixing (beading) on ​​recording media made of various hydrophobic resins, including vinyl chloride sheets, and on recording media with low ink absorption capacity, such as printing paper, thereby enabling high-quality printed images to be obtained.

[0067] The silicone surfactant is preferably a polyether-modified silicone, and examples thereof include siloxanes having alkylene oxide groups on the side chains and / or at both ends of a polydimethylsiloxane chain. Specifically, BYK-Chemie's BYK-331, BYK-333, BYK-345, BYK-3450, BYK-3451, BYK-3455, BYK-346, BYK-347, BYK-348, and BYK-349, and Evonik's TEGOWetKL245, TEGOWet250, TEGOWet260, TEGOWet270, and TEGOWet 280, and Shin-Etsu Chemical Co., Ltd.'s 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, and X-22-4515.

[0068] As the polyether-modified silicone, trisiloxane having alkylene oxide groups at the side chain and / or both ends of the polydimethylsiloxane chain is particularly preferred. The use of trisiloxane can effectively reduce the dynamic surface tension of the treatment liquid, resulting in an image with good adhesion to the substrate. The trisiloxane preferably has a structure represented by the following general formula (1).

[0069] [ka]

[0070] In the general formula (1), "EO" represents the repeating unit structure of polyethylene oxide, i.e., a structure in which ethylene oxide, a three-membered cyclic ether, is ring-opened. Furthermore, "PO" represents the repeating unit structure of polypropylene oxide, i.e., a structure in which propylene oxide, a three-membered cyclic ether, is ring-opened. Here, the phrase "the order of [EO]m and [PO]n may be either" means that in the compound molecule represented by general formula (1), the order of the bonding positions to the parent siloxane skeleton may be changed as appropriate.

[0071] In the general formula (1), X is preferably an alkylene group having 3 carbon atoms (that is, a propylene group). In the general formula (1), it is preferable that m is an integer of 5 to 20 and n is an integer of 0 to 6.

[0072] Specific examples of silicone surfactants having a structure represented by the general formula (1) are shown below as S-1 to S-8, but are not limited to these. (S-1): In the general formula (1), R=methyl group, X=alkylene group having 3 carbon atoms, m=9, and n=0 (S-2): In the general formula (1), R=butyl group, X=alkylene group having 3 carbon atoms, m=25, and n=6 (S-3): In the general formula (1), R=hydrogen atom, X=alkylene group having 3 carbon atoms, m=3, and n=0 (S-4): In the general formula (1), R=hydrogen atom, X=alkylene group having 3 carbon atoms, m=33, and n=0 (S-5): In the general formula (1), R=hydrogen atom, X=alkylene group having 3 carbon atoms, m=22, and n=16 (S-6): In the general formula (1), R=hydrogen atom, X=alkylene group having 3 carbon atoms, m=9, and n=0 (S-7): In the general formula (1), R=hydrogen atom, X=alkylene group having 3 carbon atoms, m=12, and n=3 (S-8): In the general formula (1), R=hydrogen atom, X=alkylene group having 3 carbon atoms, m=1, n=0

[0073] Examples of the trisiloxane include BYK-3450 and BYK-3451 manufactured by BYK Japan, and TEGOWET-KL245, TEGOWET-250, and TEGOWET-260 manufactured by Evonik. The content of the polyether-modified silicone is preferably in the range of 0.5 to 2% by mass, and more preferably in the range of 0.5 to 1.5% by mass, relative to 100% by mass of the total mass of the treatment liquid.

[0074] The fluorine-based surfactants refer to surfactants in which part or all of the hydrogen atoms bonded to the carbon atoms of the hydrophobic groups of ordinary surfactants have been substituted with fluorine. Among these, surfactants having a perfluoroalkyl group in the molecule are preferred.

[0075] Some of the above fluorine-based surfactants are commercially available from Dainippon Ink and Chemicals, Inc. under the trade name Megafac F, from Asahi Glass Co., Ltd. under the trade name Surflon, from Minnesota Mining and Manufacturing Company, Inc. under the trade name Fluorad FC, from Imperial Chemical Industries, Inc. under the trade name Monflor, from E.I. duPont Nemelas and Company, Inc. under the trade name Zonyls, and from Falbewerke-Hoechst under the trade name Licowet VPF.

[0076] In particular, it is preferable that the treatment liquid according to the present invention contains a surfactant that is not contained in the ink, which will be described later, in the treatment liquid, and the following two patterns can be given. When the surfactant contained in the ink is defined as surfactant S1, (i) The surfactant contained in the treatment liquid is preferably surfactant S2, which is different from surfactant S1 contained in the ink. (ii) The surfactant contained in the treatment liquid preferably contains the surfactant S2 in addition to the surfactant S1. Specifically, preferred combinations of surfactants include a surfactant contained in the treatment liquid that is preferably a polyether-modified silicone, and a surfactant contained in the ink that is preferably an acetylene glycol-based surfactant and a polyether-modified silicone. As described above, by adding a surfactant that is not contained in the ink (i.e., a surfactant that destabilizes the dispersion stability of the ink) to the treatment liquid, it is possible to further increase the coagulation properties.

[0077] The content of the surfactant in the treatment liquid is not particularly limited, but is preferably within the range of 0.1 to 5.0% by mass of the total mass of the treatment liquid.

[0078] <Water> The treatment liquid according to the present invention may contain water, and the water that can be used is not particularly limited, and may be ion-exchanged water, distilled water, or pure water.

[0079] The treatment liquid may contain other components such as a crosslinking agent, an antifungal agent, a bactericide, etc., as appropriate, within the range that does not impair the effects of the present invention.

[0080] Furthermore, for example, ultraviolet absorbers described in JP-A Nos. 57-74193, 57-87988 and 62-261476, anti-fading agents described in JP-A Nos. 57-74192, 57-87989, 60-72785, 61-146591, JP-A Nos. 1-95091 and 3-13376, anions, It is also possible to contain various known additives such as various cationic or nonionic surfactants, fluorescent brightening agents described in JP-A Nos. 59-42993, 59-52689, 62-280069, 61-242871, and 4-219266, antifoaming agents, lubricants such as diethylene glycol, preservatives, thickeners, antistatic agents, etc.

[0081] It is preferable to prepare a treatment liquid layer by directly applying the treatment liquid according to the present invention as a coating liquid onto a substrate and drying it. Here, it is preferable that additives preferably used in the treatment liquid are sufficiently dissolved before use as a coating liquid.

[0082] Preferred methods for applying the treatment liquid include inkjet coating, roll coating, rod bar coating, air knife coating, spray coating, curtain coating, and the extrusion coating method using a hopper described in U.S. Patent No. 2,681,294, and the inkjet method is particularly preferred.

[0083] [ink] The ink according to the present invention contains at least a pigment, resin particles, a water-soluble solvent having a boiling point in the range of 150 to 250° C., and a surfactant, and may also contain water.

[0084] <Pigments> The pigment contained in the ink according to the present invention and used in the ink according to the present invention is preferably an anionic dispersed pigment, for example, a self-dispersed pigment having anionic groups on its surface, a pigment dispersed with an anionic polymer dispersant, or a pigment dispersed with its surface coated with an anionic resin. In particular, the use of a pigment dispersed with an anionic polymer dispersant is preferred in terms of excellent dispersibility and adequate reaction with the treatment liquid to form pinning.

[0085] As the pigment, any conventionally known pigment can be used without any particular limitation. For example, organic pigments such as insoluble pigments and lake pigments, and inorganic pigments such as titanium oxide can be preferably used.

[0086] In the case of titanium oxide, for which it is generally difficult to ensure ink ejection stability and adhesiveness, the present invention is particularly advantageous in that bleeding is prevented from occurring and adhesiveness can be improved.

[0087] Titanium oxide has three crystalline forms: anatase, rutile, and brookite. The most commonly used titanium oxides can be broadly classified into anatase and rutile. While not particularly limited, rutile is preferred, as it has a high refractive index and high opacity. Specific examples include the TR series from Fuji Titanium Industry Co., Ltd., the JR series from Teika Corporation, and Typepaque from Ishihara Sangyo Kaisha, Ltd.

[0088] The insoluble pigment is not particularly limited, but examples thereof include azo, azomethine, methine, diphenylmethane, triphenylmethane, quinacridone, anthraquinone, perylene, indigo, quinophthalone, isoindolinone, isoindoline, azine, oxazine, thiazine, dioxazine, thiazole, phthalocyanine, and diketopyrrolopyrrole.

[0089] Specific examples of organic pigments that can be preferably used include the following pigments.

[0090] Examples of pigments 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.

[0091] 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 color tone and lightfastness.

[0092] Examples of pigments for green or cyan 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.

[0093] Examples of black pigments include CI Pigment Black 1, CI Pigment Black 6, and CI Pigment Black 7.

[0094] <Pigment dispersant> The ink according to 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, and one having a molecular weight in the range of 5,000 to 200,000 can be suitably used.

[0095] Examples of polymer dispersants include block copolymers and random copolymers having a structure derived from two or more monomers selected from styrene, styrene derivatives, vinylnaphthalene derivatives, acrylic acid, acrylic acid derivatives, maleic acid, maleic acid derivatives, itaconic acid, itaconic acid derivatives, fumaric acid, and fumaric acid derivatives, as well as salts thereof, polyoxyalkylenes, and polyoxyalkylene alkyl ethers.

[0096] The polymer dispersant preferably has an acryloyl group and is preferably neutralized with a neutralizing base before addition. The neutralizing base is not particularly limited, but is preferably an organic base such as ammonia, monoethanolamine, diethanolamine, triethanolamine, or morpholine. In particular, when the pigment is titanium oxide, the titanium oxide is preferably dispersed with a polymer dispersant having an acryloyl group.

[0097] The amount of 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.

[0098] It is particularly preferred that the pigment be in the form of a so-called capsule pigment, which is a pigment coated with the polymer dispersant. As a method for coating a pigment with a polymer dispersant, various known methods can be used, and preferred examples include a phase inversion emulsification method, an acid precipitation method, and a method in which a pigment is dispersed in a polymerizable surfactant, a monomer is supplied thereto, and the monomer is coated while polymerizing.

[0099] A particularly preferred method is to dissolve a water-insoluble resin in an organic solvent such as methyl ethyl ketone, partially or completely neutralize the acidic groups in the resin with a base, add a pigment and ion-exchanged water, disperse the pigment, remove the organic solvent, and add water as needed to prepare the dispersion.

[0100] The average particle size of the pigment dispersed in the ink is preferably 50 nm or more and less than 200 nm. This improves the dispersion stability of the pigment and the storage stability of the ink. The particle size of the pigment can be measured using a commercially available particle size measuring device that uses dynamic light scattering, electrophoresis, or the like, but measurement using dynamic light scattering is simple and can accurately measure the particle size range.

[0101] The pigment can be dispersed in a dispersing machine together with a dispersant and other additives required for various desired purposes.

[0102] As the dispersing machine, conventionally known ball mills, sand mills, line mills, high-pressure homogenizers, etc. can be used. Among them, dispersing the pigment using a sand mill is preferred because it results in a sharp particle size distribution. Furthermore, the material of the beads used for sand mill dispersion is not particularly limited, but zirconia or zircon is preferred from the viewpoint of preventing the generation of bead fragments and contamination of ionic components. Furthermore, the diameter of the beads is preferably within the range of 0.3 to 3 mm.

[0103] The content of the pigment in the ink is not particularly limited, but for titanium oxide, the content is preferably in the range of 7 to 18 mass %, and for organic pigments, the content is preferably in the range of 0.5 to 7 mass %.

[0104] <Resin fine particles> The resin fine particles (hereinafter also simply referred to as "resin") contained in the ink according to the present invention are preferably water-insoluble resin fine particles. The resin fine particles preferably have a glass transition temperature (glass transition point (Tg)) in the range of 40 to 90° C. The glass transition temperature can be determined by reading the glass transition temperature Tg from an endothermic peak when heated at a rate of 10° C. / min in a temperature range of −30 to 200° C. using a DSC (differential scanning calorimeter). The water-insoluble resin used in the present invention is a water-insoluble resin that can accept ink and exhibits solubility or affinity for the ink.

[0105] Water-insoluble resin microparticles are essentially water-insoluble resins that are dispersed in aqueous media as microparticles. They are either water-insoluble resins that are forcibly emulsified using an emulsifier or the like and dispersed in water, or water-insoluble resins that have hydrophilic functional groups introduced into their molecules and are self-emulsifiable to form stable aqueous dispersions without the use of emulsifiers or dispersion stabilizers. These resins are usually used in a state of being emulsified and dispersed in water or a water / alcohol mixed solvent.

[0106] In the present invention, "water-insoluble" refers to a resin that, when dried at 105° C. for 2 hours and then dissolved in 100 g of water at 25° C., dissolution amounts of the resin are 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 dissolution amount refers to the amount dissolved when the salt-forming groups of the resin are 100% neutralized with acetic acid or sodium hydroxide, depending on the type of resin.

[0107] The resin having a glass transition temperature in the range of 40 to 90°C is preferably any one of acrylic resin, urethane resin, polyester resin, or composite resin of urethane resin and acrylic resin, particularly acrylic resin, urethane resin, polyester resin, or composite resin of urethane resin and acrylic resin, and the resin particles of these resins preferably have an average particle size of 200 nm or less, and particularly preferably have an average particle size in the range of 100 to 150 nm.

[0108] The polyester resin, urethane resin, acrylic resin or composite resin particles of urethane resin and acrylic resin are preferably anionic or nonionic.

[0109] In particular, it is preferable that the resin particles used in the ink contain an acid structure, which allows them to be dispersed in water even with a small amount of surfactant added, improving the water resistance of the ink layer. This is called a self-emulsifying type, which means that the resin can be dispersed and stabilized in water using only molecular ionicity without the use of a surfactant. Examples of acid structures include acid groups such as a carboxyl group (-COOH) and a sulfonic acid group (-SO3H). The acid structure may be present in the side chain of the resin or at the terminal. The ink according to the present invention preferably contains a water-dispersible polyester resin having a sulfonic acid group, which provides high adhesion to the substrate.

[0110] It is preferable that the acid structures are partially or entirely neutralized. Neutralizing the acid structures can improve the water dispersibility of the resin. Examples of neutralizing agents for neutralizing the acid structures include organic amines, and it is preferable to use organic amines such as trimethylamine, triethylamine, tripropylamine, tributylamine, N-methyldiethanolamine, and triethanolamine.

[0111] The ink according to the present invention preferably contains 3 to 15% by mass of resin particles having an aggregation property of 0.2 or less with a 0.15% by mass aqueous solution of calcium acetate. By using such resin particles with low aggregation property, high wettability to the substrate is ensured while high ejection stability is obtained, resulting in higher image quality and excellent adhesion to the substrate. In the present invention, the "cohesion" is a value calculated by the following formula after measuring the remaining amount according to the following procedure. (i) 5 g of a resin fine particle aqueous solution (solid content 10% by mass) containing resin fine particles is mixed with 5 g of a 0.3% by mass aqueous solution of calcium acetate monohydrate. (ii) The mixed solution is centrifuged. (iii) Collect 2 g of the supernatant separated by centrifugation. (iV) 2 g of the collected supernatant is dried at 150°C for 30 minutes, and the mass of the solid content (remaining amount (g)) is measured. (V) Calculate the cohesiveness value using the following formula. Formula: Coagulation = 1 - [mass of solids (g) / (mass of collected supernatant (g) × 5%)]

[0112] Examples of resin particles having an agglomeration index of 0.2 or less include Vylonal MD2000 manufactured by Toyobo Co., Ltd., Mowinyl 6969D manufactured by Japan Coating Resins Co., Ltd., and Evaphanol HA-560 manufactured by Nicca Chemical Co., Ltd.

[0113] Each resin will be described below. (polyester resin) The polyester resin having a polyester skeleton as the water-insoluble resin particles can be obtained by using a polyhydric alcohol component and a polycarboxylic acid component such as a polycarboxylic acid, a polycarboxylic acid anhydride, or a polycarboxylic acid ester.

[0114] The polyhydric alcohol component includes dihydric alcohols (diols), specifically alkylene glycols having 2 to 36 carbon atoms (ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, 1,6-hexanediol, etc.), alkylene ether glycols having 4 to 36 carbon atoms (diethylene glycol, triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polybutylene glycol, etc.), alicyclic diols having 6 to 36 carbon atoms (diols), and alkylene ether glycols having 6 to 36 carbon atoms (diols). Examples of suitable alkylene oxides include alicyclic diols (1,4-cyclohexanedimethanol, hydrogenated bisphenol A, etc.), adducts of the above-mentioned alicyclic diols with alkylene oxides (ethylene oxide (hereinafter abbreviated as EO), propylene oxide (hereinafter abbreviated as PO), butylene oxide (hereinafter abbreviated as BO)) having 2 to 4 carbon atoms (number of moles added: 1 to 30), and adducts of bisphenols (bisphenol A, bisphenol F, bisphenol S, etc.) with alkylene oxides (EO, PO, BO, etc.) having 2 to 4 carbon atoms (number of moles added: 2 to 30). These may be used alone or in combination of two or more.

[0115] Examples of the polyvalent carboxylic acid component include dicarboxylic acids (dicarboxylic acids), specifically alkane dicarboxylic acids having 4 to 36 carbon atoms (succinic acid, apidic acid, sebacic acid, etc.), alkenyl succinic acids (dodecenyl succinic acid, etc.), alicyclic dicarboxylic acids having 4 to 36 carbon atoms (dimer acids (dimerized linoleic acid), etc.), alkene dicarboxylic acids having 4 to 36 carbon atoms (maleic acid, fumaric acid, citraconic acid, mesaconic acid, etc.), and aromatic dicarboxylic acids having 8 to 36 carbon atoms (phthalic acid, isophthalic acid, terephthalic acid or derivatives thereof, naphthalenedicarboxylic acid, etc.). These may be used alone or in combination of two or more.

[0116] The polyester resin is preferably a polyester resin having an anionic group in the molecule, and more preferably a polyester resin having a sulfonic acid group. A polyester containing a sulfonic acid group can be obtained by a known synthesis method, for example, a polycondensation reaction between a dicarboxylic acid having a sulfonic acid group and a diol, or a polycondensation reaction between a dicarboxylic acid and a diol having a sulfonate salt. Examples of dicarboxylic acid components having a sulfonic acid group include 2-sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfonaphthaleneisophthalic-2,7-dicarboxylic acid, 5-(4-sulfophenoxy)isophthalic acid, and alkali metal salts thereof. Examples of diols having a sulfonic acid group include 2-sulfo-1,4-butanediol, 2,5-dimethyl-3-sulfo-2,5-hexanediol, and alkali metal salts thereof.

[0117] The number average molecular weight of the polyester resin is preferably within a range of 1,000 to 50,000, and more preferably within a range of 2,000 to 20,000.

[0118] As the polyester resin, commercially available products may be used. Examples of commercially available water-dispersible polyester resins having sulfonic acid groups 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 Goo 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 & Fat Co., Ltd. Among the above, resins having a glass transition temperature of 40 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 Goo Chemical Co., Ltd., and PES Resin A-520, A-613D, A-615GE, A-640, A-645GH, and A-647GEX manufactured by Takamatsu Oil & Fat Co., Ltd. These may be used alone or in combination of two or more.

[0119] (urethane resin) The urethane resin used as the water-insoluble resin particles may have a hydrophilic group.

[0120] The urethane resin is preferably an aqueous dispersion of a self-emulsifying urethane having a water-soluble functional group dispersed in its molecule, or an aqueous dispersion of a forced-emulsifying urethane emulsified under strong mechanical shear force in combination with 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.

[0121] Examples of polyols that can be used to prepare the aqueous dispersion of the urethane resin include polyester polyols, polyether polyols, polycarbonate polyols, and polyolefin polyols.

[0122] Examples of polyester polyols include low molecular weight polyols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2- and 1,3-propylene glycol, neopentyl glycol, 1,3- and 1,4-butanediol, 3-methylpentanediol, hexamethylene glycol, 1,8-octanediol, 2-methyl-1,3-propanediol, bisphenol A, hydrogenated bisphenol A, trimethylolpropane, and cyclohexanedimethanol; and condensates thereof with polycarboxylic acids such as succinic acid, glutaric acid, adipic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, tetrahydrofuran acid, endomethinetetrahydrofuran acid, and hexahydrophthalic acid.

[0123] Examples of polyether polyols include polyethylene glycol, polypropylene glycol, polyethylene polytetramethylene glycol, polypropylene polytetramethylene glycol, and polytetramethylene glycol.

[0124] Examples of polycarbonate polyols include those obtained by reacting a carbonic acid derivative such as diphenyl carbonate, dimethyl carbonate, or phosgene with a diol, such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2- and 1,3-propylene glycol, neopentyl glycol, 1,3- and 1,4-butanediol, 3-methylpentanediol, hexamethylene glycol, 1,8-octanediol, 2-methyl-1,3-propanediol, bisphenol A, hydrogenated bisphenol A, trimethylolpropane, and cyclohexanedimethanol.

[0125] Examples of organic polyisocyanates that can be used to prepare the aqueous dispersion of the urethane resin include aromatic isocyanates such as tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymeric MDI, xylylene diisocyanate (XDI), and tetramethylxylylene diisocyanate (TMXDI); aliphatic isocyanates such as hexamethylene diisocyanate (HMDI); isophorone diisocyanate (IPD), and the like. These include alicyclic isocyanates such as 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI, H12MDI), etc. These may be used alone or in combination of two or more.

[0126] Examples of hydrophilic group-containing compounds that can be used to prepare the aqueous dispersion of the urethane resin include carboxylic acid-containing compounds such as 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, 2,2-dimethylolbutyric acid, 2,2-dimethylolvaleric acid, and glycine, and derivatives thereof such as sodium salts, potassium salts, and amine salts; and sulfonic acid-containing compounds such as taurine (i.e., aminoethylsulfonic acid) and ethoxypolyethylene glycol sulfonic acid, and derivatives thereof such as sodium salts, potassium salts, and amine salts.

[0127] The urethane resin can be obtained by a known method. For example, a urethane prepolymer can be obtained by mixing the above-mentioned polyol, organic polyisocyanate, and hydrophilic group-containing compound and reacting them at 30 to 130°C for 30 minutes to 50 hours.

[0128] The urethane prepolymer is polymerized by extending the chain with a chain extender to form a urethane resin having a hydrophilic group. The chain extender is preferably water and / or an amine compound. By using water or an amine compound as the chain extender, the chain can react with free isocyanate in a short time, efficiently extending the isocyanate-terminated prepolymer.

[0129] Examples of the amine compound as a chain extender include aliphatic polyamines such as ethylenediamine and triethylenediamine, aromatic polyamines such as metaxylenediamine and toluylenediamine, and polyhydrazino compounds such as hydrazine and adipic acid dihydrazide. The amine compound may contain, together with the polyamine, a monovalent amine such as dibutylamine or methyl ethyl ketoxime as a reaction terminator to the extent that the polymerization is not significantly inhibited.

[0130] In addition, in the synthesis of the urethane prepolymer, a solvent that is inert to isocyanates and can dissolve 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 step are preferably finally removed.

[0131] In addition, in the synthesis of the urethane prepolymer, a catalyst such as an amine catalyst (e.g., triethylamine, N-ethylmorpholine, triethyldiamine, etc.), a tin-based catalyst (e.g., dibutyltin dilaurate, dioctyltin dilaurate, tin octoate, etc.), or a titanium-based catalyst (e.g., tetrabutyl titanate, etc.) may be added to promote the reaction.

[0132] The number-average molecular weight of the urethane resin is preferably increased as much as possible by introducing a branched structure or an internal crosslinked structure, and a number-average molecular weight of 50,000 to 10,000,000 is preferable. By keeping the molecular weight within this range, the urethane resin becomes less soluble in solvents, resulting in a coating film with excellent weather resistance and water resistance. The number-average molecular weight (Mn) is a value measured by gel permeation chromatography (GPC) and can be determined, for example, from a calibration curve prepared using a polystyrene standard sample using a Shimadzu Corporation "RID-6A" column (Tosoh Corporation "TSK-GEL" column, tetrahydrofuran (THF) solvent, and a column temperature of 40°C).

[0133] The urethane resin may be a commercially available product. Examples of commercially available urethane resins having a glass transition temperature of 40 to 90°C include Neorez R-967, R-600, and R-9671 manufactured by Kusumoto Chemicals, Ltd., Evaphanol HA-560 manufactured by Nicca Chemical, and SF870 manufactured by Daiichi Kogyo Seiyaku Co., Ltd.

[0134] (acrylic resin) 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, or a styrene component. Examples of the acrylic acid ester component and the methacrylic acid ester component include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, cyclohexyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, isobornyl (meth)acrylate, benzyl (meth)acrylate, and 2-hydroxyethyl (meth)acrylate. -hydroxybutyl, benzyl (meth)acrylate, glycidyl (meth)acrylate, (meth)acrylic acid, (di)ethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, glycerin di(meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, and acrylamide.

[0135] Examples of the styrene component include styrene, 4-methylstyrene, 4-hydroxystyrene, 4-acetoxystyrene, 4-acetylstyrene, and styrene sulfonic acid. These components may be used alone or in combination of two or more.

[0136] The number-average molecular weight (Mn) of the acrylic resin is preferably 1,000 to 50,000, and more preferably 2,000 to 20,000. When the number-average molecular weight (Mn) of the acrylic resin is 1,000 or more, the cohesive strength of the coating film is increased and adhesion is improved, while when it is 50,000 or less, solubility in organic solvents is improved and reduction in particle size of the emulsion dispersion is promoted. The number-average molecular weight (Mw) is a value measured by gel permeation chromatography (GPC) and can be determined, for example, from a calibration curve prepared with polystyrene standard samples using a Shimadzu Corporation "RID-6A" column (column: Tosoh Corporation "TSK-GEL" column, solvent: tetrahydrofuran (THF), column temperature: 40°C).

[0137] Commercially available acrylic resins having a glass transition temperature of 40 to 90°C include acrylic emulsions such as Mowinyl 6899D, 6969D, and 6800 manufactured by Japan Coating Resins Co., Ltd., and TOCRYL W-7146, W-7147, W-7148, W-7149, and W-7150 manufactured by Toyochem Co., Ltd.

[0138] (Composite resin fine particles) The composite resin particles that can be contained in the ink are preferably composite resin particles in which an acrylic resin is emulsified in a urethane resin, i.e., composite resin particles having an inner layer made of an acrylic resin and a surface layer made of a urethane resin.

[0139] Here, the urethane resin is present at the interface between the acrylic resin as water-insoluble resin particles and the water as the continuous phase, and functions as a water-insoluble resin particle layer that is different from the resin that protects the water-insoluble resin particles.

[0140] By emulsifying the acrylic resin with the urethane resin in this way to form composite resin microparticles, the physical properties of the image (coating film) can be improved, and the storage stability of the composite resin microparticles can also be improved, compared to when the acrylic resin and the urethane resin are emulsified separately and mixed.

[0141] In the composite resin microparticles obtained by emulsifying the acrylic resin in the urethane resin, the mass ratio (U / A) of the urethane resin (U) to the acrylic resin (A) is preferably 40 / 60 to 95 / 5. When the proportion of the urethane resin (U) is within the above range, compatibility with dispersants and solvent resistance are improved. Furthermore, when the proportion of the acrylic resin (A) is within the above range, adhesion to acrylic films is excellent. In the above proportions, the mass ratio (U / A) of the urethane resin (U) to the acrylic resin (A) is preferably 40 / 60 to 80 / 20.

[0142] 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, and more preferably 10.0 to 70.0% by mass. When the resin concentration is within the above range, the fixation of the ink to the substrate is good.

[0143] In addition, when emulsifying the acrylic resin with the urethane resin, a surfactant acting as an emulsifier can be used together with the urethane resin. The addition of an emulsifier can improve the storage stability of the composite resin particles.

[0144] Anionic surfactants and nonionic surfactants can be used as the emulsifier. In the present invention, it is preferable to use either the anionic surfactant or the nonionic surfactant, and it is more preferable to use both. Here, the total amount of the anionic surfactant and the nonionic surfactant is preferably 1.0 to 20.0 parts by mass per 100 parts by mass of the total resin. Furthermore, by setting the total amount of the anionic surfactant and the nonionic surfactant to 20.0 parts by mass or less, water resistance and solvent resistance can be improved.

[0145] The blending mass ratio (X / Y) of the anionic surfactant (X) to the nonionic surfactant (Y) is preferably 100 / 0 to 50 / 50. By setting the blending amount of the anionic surfactant within the above range, emulsifiability and storage stability can be further improved.

[0146] Examples of anionic surfactants that can be used for emulsification include alkyl sulfates, polyoxyethylene alkyl ether sulfates, sulfosuccinates, alpha-olefin sulfonates, N-acylamino acid salts, carboxylates, and phosphate esters, etc. Among these, sulfosuccinates and alpha-olefin sulfonates are preferred. Examples of the salts include, but are not limited to, metal salts such as sodium salts, potassium salts, and magnesium salts, and triethanolamine salts.

[0147] Examples of nonionic surfactants that can be used for emulsification include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkylamine ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, sucrose fatty acid esters, etc. Among these, polyoxyethylene alkyl ethers and polyoxyethylene alkylphenyl ethers are preferred. stomach.

[0148] 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 measured using a commercially available particle size measuring device that uses dynamic light scattering, electrophoresis, or the like, but measurement by dynamic light scattering is simple and allows accurate measurement of the particle size range.

[0149] By using composite resin particles in which an acrylic resin is emulsified in a urethane resin, it is possible to improve the fixability of an image (coating film) to an absorbent or non-absorbent substrate.

[0150] <Water-soluble solvent> The water-soluble solvent contained in the ink according to the present invention is a water-soluble solvent having a boiling point in the range of 150 to 250°C. Examples of such water-soluble solvents include alcohols, polyhydric alcohols, amines, amides, glycol ethers, and 1,2-alkanediols having 4 or more carbon atoms, including those exemplified in the treatment liquid.

[0151] The ink may contain one or a combination of two or more selected from the water-soluble solvents described above.

[0152] The content of the water-soluble solvent in the ink is not particularly limited, but is preferably within the range of 10 to 60% by mass.

[0153] <Surfactant> By including a surfactant in the ink according to the present invention, it is possible to improve the ink ejection stability and control the spread (dot diameter) of droplets that land on a recording medium.

[0154] The surfactant that can be used in the ink according to the present invention is not particularly limited, and examples thereof include those exemplified in the treatment liquid. However, as described above, it is preferable that the treatment liquid does not contain the same surfactant as the surfactant contained in the ink.

[0155] The content of the surfactant in the ink is not particularly limited, but is preferably in the range of 0.1 to 5.0% by mass.

[0156] <Water> The water contained in the ink according to the present invention is not particularly limited, and may be ion-exchanged water, distilled water, or pure water.

[0157] In addition to the above, the ink used in the present invention may contain various known additives, such as polysaccharides, viscosity modifiers, resistivity modifiers, film-forming agents, ultraviolet absorbers, antioxidants, anti-fading agents, anti-mold agents, and anti-rust agents, which may be appropriately selected and used for the purpose of improving ejection stability, compatibility with print heads and ink cartridges, storage stability, image storage stability, and other performances. Examples of such additives include oil droplet fine particles such as liquid paraffin, dioctyl phthalate, tricresyl phosphate, and silicone oil; 193, 57-87988, 62-261476, etc.; anti-fading agents described in JP-A-57-74192, 57-87989, 60-72785, 61-146591, 1-95091, 3-13376, etc.; and fluorescent brightening agents described in JP-A-59-42993, 59-52689, 62-280069, 61-242871, 4-219266, etc.

[0158] The ink used in the present invention having the above constitution preferably has a viscosity of 1 to 40 mPa·s at 25°C, more preferably 2 to 10 mPa·s.

[0159] [Inkjet recording method] The inkjet recording method of the present invention is an inkjet recording method that records an image using an ink set containing the treatment liquid and ink described above. The method using this ink set allows, for example, a single inkjet printer to efficiently apply the treatment liquid constituting the ink set of the present invention to the surface of a substrate and print with the ink continuously. This makes it possible to print characters, patterns, and the like with excellent image quality and with little variation in dot diameter between substrates.

[0160] 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 described above, in which after the treatment liquid has been applied to a substrate, the ink is applied to the area to which the treatment liquid has been applied while the treatment liquid is still wet, without undergoing a heat drying step. That is, the method includes a step of applying the treatment liquid to a recording area of ​​a substrate (treatment liquid application step), and a step of applying the ink to the area to which the treatment liquid has been applied using an inkjet recording method while the ink is wet with the treatment liquid (ink application step). In addition to the above steps, the inkjet recording method of the present invention preferably includes an ink heating and drying step of heating and drying the treatment liquid and ink applied to the substrate after the ink application step to form a treatment liquid layer and an ink layer.

[0161] In the ink application step, it is preferable to apply ink to the area to which the treatment liquid has been applied when the drying rate of the treatment liquid is 30% or less, and it is preferable to carry out the ink application step within 10 seconds after the treatment liquid application step. It is particularly preferable to carry out the ink application step within 0.1 to 5 seconds after the treatment liquid application step when the drying rate of the treatment liquid is in the range of 1 to 10%.

[0162] <Base material> The substrate (recording medium) applicable to the inkjet recording method of the present invention is not particularly limited, and may be an absorbent substrate made of an absorbent material or a non-absorbent substrate made of a non-absorbent material, but is preferably a non-absorbent substrate from the viewpoint of realizing the effects of the present invention. In the present invention, "absorbent" refers to the ability to absorb water, and "non-absorbent" refers to the ability not to absorb water. As the non-absorbent substrate, a known plastic film can be used.

[0163] Specific examples of the known plastic films include polyester films such as polyethylene terephthalate, polyethylene films, polypropylene films, polyamide films such as nylon, polystyrene films, polyvinyl chloride films, polycarbonate films, polyacrylonitrile films, and biodegradable films such as polylactic acid films. In addition, films coated with polyvinylidene chloride on one or both sides or films vapor-deposited with metal oxides can also be preferably used to impart gas barrier properties, moisture resistance, aroma retention, etc. The non-absorbent film can be either an unstretched film or a stretched film. In the case of a plastic film, the thickness of the substrate is preferably within a range of 10 to 120 μm, more preferably 12 to 60 μm.

[0164] In addition, metal substrates such as tinplate for three-piece cans and tin-free steel plates (TFS plates, thickness 0.1 to 0.6 μm) are also preferably used as non-absorbent substrates, and can be used suitably as packaging materials for canned foods, for example, with a thermosetting resin coating layer. The packaging materials for canned foods use, for example, epoxy-phenolic paints or polyester laminating agents on the food side to block air, moisture, and light and seal the food inside. On the outside, polyester or acrylic thermosetting paint is generally used.

[0165] Each step of the inkjet recording method will be described below. <Processing liquid application step> In the treatment liquid application step, the treatment liquid is applied onto a recording medium, which is a substrate.

[0166] The method for applying the treatment liquid onto the recording medium is not particularly limited, and preferred examples include roller coating, curtain coating, spray coating, inkjet coating, etc. Among these, the roller coating is preferred from the viewpoints that a roller coating machine or the like can be connected to an inkjet device and that the treatment liquid can be applied efficiently even when the viscosity is relatively high. In addition, using an inkjet method as the process for applying the treatment liquid is preferable because it eliminates the need to apply a coagulant to areas where ink is not applied, and therefore the coagulant that does not react with the ink does not become liberated and turn cloudy. In this case, as will be described later, when the substrate used is a metal substrate or the like, it is also preferable to place the metal substrate on a conveyor belt and apply the treatment liquid layer while conveying the belt, or to use a flatbed type printer to which the substrate is fixed, to form the treatment liquid layer.

[0167] <Ink application process> The ink application step is a step in which the inks of the ink set described above are applied by an inkjet method simultaneously with or immediately after forming a treatment liquid layer on the recording medium, which is the substrate. In particular, it is preferable to apply the ink to the region to which the treatment liquid has been applied after the treatment liquid application step when the drying rate of the treatment liquid is 30% or less, and it is also preferable to apply the ink to the region to which the treatment liquid has been applied within 10 seconds after the treatment liquid has been applied to the substrate. The drying rate of the treatment liquid is defined by the following formula: (Drying rate of processing liquid) = 1 - ((mass of processing liquid after drying (g)) / (mass of processing liquid before drying (g)) By applying ink when the drying rate of the treatment liquid is 30% or less, the ink and treatment liquid are mixed appropriately, and the effects of the present invention can be more significantly exhibited. Furthermore, by applying the ink within 10 seconds after applying the treatment liquid to the substrate, it is possible to suppress the penetration of the treatment liquid into absorbent substrates and the repelling of the treatment liquid on non-absorbent substrates, thereby achieving higher image quality. As described above, in order to keep the drying rate of the treatment liquid at 30% or less, the time between the application of the treatment liquid and the application of the ink can be adjusted, or the temperature of the recording medium can be appropriately adjusted.

[0168] Furthermore, in the ink application process, it is preferable to adjust the amount of ink droplets so that the amount of ink applied (also referred to as the "application amount") per unit area is within a range of 2 to 25 times the amount of treatment liquid applied, in order to achieve higher image quality, and a more preferable range for the application amount is 2.5 to 3.5 times.

[0169] The inkjet method is not particularly limited, and a printer equipped with an inkjet head loaded with ink can be used. Specifically, ink is ejected as droplets from the nozzles of the inkjet head based on a digital signal, and these droplets land on the treatment liquid layer of the substrate to perform printing.

[0170] The inkjet head may be either an on-demand type or a continuous type. Examples of on-demand type inkjet heads include electro-mechanical conversion types, including single-cavity, double-cavity, bender, piston, shear-mode, and shared-wall types, and electro-thermal conversion types, including thermal inkjet and bubble-jet types ("Bubble Jet" is a registered trademark of Canon Inc.).

[0171] Among the above inkjet heads, inkjet heads using a piezoelectric element as the electromechanical conversion element used in the electromechanical conversion system (also called piezo-type inkjet heads) are preferred.

[0172] The inkjet printer may be of either a scan type or a single pass type, but in the case of a single pass type, it is preferable to use a line head type inkjet head.

[0173] A line head type inkjet head is an inkjet head whose length is equal to or greater than the width of the printing range. As a line head type inkjet head, a single head whose length is equal to or greater than the width of the printing range may be used, or multiple heads may be combined to form a head whose length is equal to or greater than the width of the printing range.

[0174] Furthermore, a plurality of heads may be arranged in parallel so that the nozzles are arranged in a staggered pattern, thereby increasing the overall resolution of the heads.

[0175] The conveying speed of the recording medium, which is the substrate, can be set, for example, within the range of 1 to 120 m / min. The faster the conveying speed, the faster the image formation speed. According to the present invention, it is possible to obtain high-resolution images with high ink fixation even at a very high linear speed of 50 to 120 m / min, which is applicable to a single-pass inkjet image formation method.

[0176] <Ink heating and drying process> In the ink heating and drying process, the ink applied to the recording medium as a substrate, i.e., the area where the ink is applied, is heated, thereby drying the ink and the treatment liquid.

[0177] In the ink heating and drying step, the heating temperature of the area where the ink has been applied is preferably within the range of 60 to 200° C. The heating time of the ink is adjusted appropriately according to the type of recording medium and the amount of ink applied.

[0178] By heating the ink-applied area in this manner, the solvent components of the treatment liquid and ink, such as water and water-soluble solvents, are removed, and at the same time, in the case of a metal substrate in particular, the polyvalent metal salt is dried and thermally decomposed at a temperature equal to or higher than its thermal decomposition temperature, thereby improving the abrasion resistance of the image and adhesion to the substrate.

[0179] The heat drying may be carried out using a non-contact heating type drying device such as a drying oven or a hot air blower, or may be carried out using a contact heating type drying device such as a hot plate or a heat roller.

[0180] The drying temperature can be obtained by measuring any one of the following throughout the entire drying period of the treatment liquid: (a) when a non-contact heating drying device such as a drying furnace or a hot air blower is used, the ambient temperature such as the temperature inside the furnace or the hot air temperature; (b) when a contact heating drying device such as a hot plate or a heated roller is used, the temperature of the contact heating part; or (c) the surface temperature of the surface to be dried. It is more preferable to measure the surface temperature of the surface to be dried (c).

[0181] The thickness of the ink layer obtained as described above is preferably in the range of 0.3 to 3.0 μm, and more preferably in the range of 0.3 to 2.0 μm. When the ink layer is 0.3 μm or thicker, the adhesion and abrasion resistance of the image are easily improved. When the ink layer is 3.0 μm or thicker, the deformation stress applied to the ink layer can be reduced, so the adhesion of the image is less likely to be impaired.

[0182] [Recording Device] 1 is a schematic diagram of a recording device that is preferred for the present invention, although the present invention is not limited to this.

[0183] The recording apparatus 1 is mainly composed of a treatment liquid deposition section 10 and an ink deposition section 20. In the treatment liquid deposition section 10, a treatment liquid layer C is formed on a substrate F, and by the ink deposition section 20, an ink layer R is formed. The treatment liquid application unit 10 is not particularly limited as long as it has a configuration that 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 or the like may also be used. The ink applying unit 20 is an inkjet head 21 capable of ejecting ink.

[0184] In this recording apparatus 1, droplets 12 of treatment liquid are ejected from the inkjet head 11 onto the substrate F fed from the feed roller 30, and a treatment liquid layer C is formed.

[0185] Next, ink droplets 22 are ejected from the inkjet head 21 onto the treatment liquid layer C to form an ink layer R, and the area to which the ink has been applied is heated and dried by the second drying section 23. Thereafter, the substrate F on which the treatment liquid layer C and the ink layer R have been formed is wound up by the winding roller 40 to obtain an image recorded matter.

[0186] Although FIG. 1 shows a case where the substrate F is a film substrate, in the case of a metal substrate or the like, the metal substrate can be placed on a conveyor belt, and the treatment liquid layer C and the ink layer R can be coated and formed in one pass while the belt is being conveyed. In addition, in FIG. 1, the device is configured to apply the treatment liquid onto the substrate and then apply the ink, but the device may be configured to apply the treatment liquid and ink simultaneously, but it is preferable to eject the ink from the inkjet head when the drying rate of the treatment liquid layer is 30% or less.

[0187] Furthermore, as an apparatus other than the recording apparatus shown in Figure 1, it is also preferable to use a flatbed type printer to apply the treatment liquid and ink. In a flatbed type printer, the substrate is fixed and the inkjet head can be moved in the main scanning direction and the sub-scanning direction that intersects the main scanning direction, making it possible to print without transporting the substrate. For metal substrates such as tinplate, roll-to-roll transport is not possible as with resin film substrates, so it is preferable to use a flatbed type printer that does not require transporting the substrate. Examples of such flatbed type printers include the printers described in FIG. 1 of JP-A-2015-74161 and FIG. 1 of JP-A-2017-177578.

[0188] [Image Recording] The image recorded matter according to the present invention preferably has a substrate, a treatment liquid layer formed on the substrate using the treatment liquid, and an ink layer formed on the treatment liquid layer using the ink.

[0189] 2, the image recording material P is prepared by applying the treatment liquid according to the present invention onto a substrate F using a roll coater or the like, or by ejecting the treatment liquid from an inkjet head, to form a treatment liquid layer C. At the position where the treatment liquid layer C has been fixed, ink is ejected from an inkjet head and fixed to form an image recording layer R.

[0190] The above configuration indicates the minimum configuration, and another functional layer may be formed between the substrate and the treatment liquid layer, or a non-absorbent film substrate or the like may be attached to the upper layer of the ink layer via, for example, a laminating adhesive layer. At the very least, a configuration in which the treatment liquid layer and the ink layer are in contact with each other is essential.

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

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

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

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

[0195] [Preparation of processing solution T1] 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 silicone BYK3450, 0.1% by mass of a fungicide (Proxel GXL(S)), and ion-exchanged water (balance; amount such that the total amount was 100% by mass) were added with stirring, and the resulting mixture was filtered through a 1 μm filter to obtain treatment liquid T1.

[0196] [Preparation of treatment solutions T2 to T6] Treatment solutions T2 to T6 were prepared in the same manner as in the preparation of treatment solution T1, except that the types and amounts of polyvalent metal salt, solvent, surfactant, and water added were changed as shown in Table I below.

[0197] The abbreviations in Table I are as follows: <Solvent> "DPG": Diethylene glycol "PG": Propylene glycol "1,2-HDO": 1,2-hexanediol "Gly": Glycerin

[0198] <Surfactant> "TEGOWET250": Polyether-modified silicone TEGOWET-250 (manufactured by Evonik) "BYK3450": Polyether-modified silicone BYK-3450 (manufactured by BYK-Chemie) "BYK348": Polyether-modified silicone BYK-348 (manufactured by BYK-Chemie)

[0199] <Anti-mold agent> "Proxel GXL(S)": 1,2-benzisothiazolin-3-one

[0200] [Physical Properties] For each of the resulting treatment liquids, the dynamic surface tension, static surface tension, and dynamic surface tension after 30% drying were measured by the following methods.

[0201] <Dynamic surface tension> The dynamic surface tensions of the treatment solutions T1 to T6 prepared above were measured over a surface life of 10 ms 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 tensions (units: mN / m) over a surface life of 15 ms, 100 ms, and 1000 ms are shown in Table I below. The dynamic surface tension over a surface life of 15 ms here is referred to as "dynamic surface tension A," which will be described later.

[0202] <Static surface tension> The static surface tension of each 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.

[0203] <Dynamic surface tension after 30% drying> 100 g of each of the ink treatment liquids T1 to T6 prepared above was weighed into a shallow container and dried in a reduced pressure environment at 25°C until the liquid mass reached 70 g. The dynamic surface tension of each treatment liquid was then measured using the method described above, and this was designated as dynamic surface tension B after 30% drying. The difference "(BA)" between dynamic surface tension B after 30% drying and the dynamic surface tension A of the treatment liquid measured above after a surface life of 15 ms was calculated. The results are shown in Table I below.

[0204] [evaluation] <Injection stability> The treatment solutions T1 to T6 prepared above were filled into an independently driven inkjet head (360 npi, discharge volume 14 pL, 1024 nozzles) manufactured by Konica Minolta, and a continuous discharge test was carried out for 30 minutes using a strobe-synchronized droplet observation device. After that, the ejection stability was evaluated according to the following criteria. (standard) ◯: Of the 256 nozzles evaluated, all 256 nozzles ejected normally. △: Of the 256 nozzles evaluated, 1 or more but less than 5 nozzles were observed to be abnormally ejecting. ×: Of the 256 nozzles evaluated, 5 or more nozzles were observed to be abnormally ejecting.

[0205] <Storage of processing solution> The treatment solutions T1 to T6 prepared above were stored in a thermostat at 60° C. for two weeks, and then visually evaluated according to the following criteria. (standard) ○: No abnormalities such as cloudiness or separation were visually observed in the treatment solution after storage at 60°C for 2 weeks. ×: The treatment solution was slightly cloudy or separated after storage at 60°C for 2 weeks. ×: The treatment solution was clearly cloudy or separated after storage at 60°C for 2 weeks.

[0206] [Table 1]

[0207] As shown by the above results, the processing liquid of the present invention, which has a dynamic surface tension in the range of 25 to 35 mN / m at a surface life of 15 ms, is found to have excellent ejection stability and storage stability.

[0208] [Resin particle dispersion P1~P5] The coagulation property and glass transition temperature (Tg) of each of the resin particles in the resin particle dispersions P1 to P5, which are commercially available products shown in Table II below, were measured, and the measurement results are shown in Table II below.

[0209] <Cohesiveness> The cohesion was measured by the following method. First, to prepare a mixed solution containing 5% by mass of resin microparticles and 0.15% by mass of calcium acetate monohydrate, an aqueous calcium acetate solution was prepared by dissolving calcium acetate monohydrate in ion-exchanged water to a concentration of 0.30% by mass, and a diluted solution of each of the resin microparticle dispersions P1 to P5 shown in Table II was prepared with ion-exchanged water to a solids content of 10% by mass. Next, 5 g of the calcium acetate aqueous solution was added to 5 g of the diluted resin particle dispersion while stirring to prepare 10 g of each mixed solution with a solid content of 5 mass % and calcium acetate monohydrate of 0.15 mass %. Then, 10 g of each mixture was centrifuged using a Hitachi Koki centrifuge CF16RX at a centrifugal acceleration of 200 G for 10 minutes, and approximately 2 g of supernatant was collected from each separated solution. 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 obtained mass of the solid matter was substituted into the following formula to calculate the cohesion. Formula: Coagulation = 1 - (mass of solids (g) / (mass of collected supernatant (g) × 5%))

[0210] <Glass transition temperature> The glass transition temperature (Tg) of the resin particles was determined by reading the glass transition temperature Tg from the endothermic peak when the temperature was raised at a rate of 10°C / min in the temperature range of -30 to 200°C using a DSC (differential scanning calorimeter).

[0211] [Table 2]

[0212] [Preparation of magenta ink] <Preparation of Magenta Pigment Dispersion D1> A mixture of 20% by mass of magenta pigment (a mixed crystal of Pigment Red 122 and Pigment Violet 19) was premixed with 8% by mass of an anionic polymer dispersant (an acrylic dispersant having a carboxyl group neutralized with dimethylaminoethanol (BASF's "Joncryl 819"; acid value 75 mg KOH / g; solids content 20% by mass), 20% by mass of propylene glycol, 0.1% by mass of the antifungal agent Proxel GXL(S), and ion-exchanged water (the remainder; an amount that would make the total amount 100% by mass). Thereafter, the mixture was dispersed using a bead mill filled with 0.3 mm zirconia beads at a volume ratio of 50%, to prepare pigment dispersion D1 with a pigment content of 20 mass %. The average particle size of the pigment particles contained in this pigment dispersion was 140 nm, and the average particle size was measured using a Zetasizer Nano S-90 manufactured by Marballoon Co., Ltd.

[0213] <Preparation of Magenta Pigment Dispersion D2> Magenta pigment dispersion D2 was prepared in the same manner as in preparation of magenta pigment dispersion D1, except that the pigment dispersant was changed from the acrylic dispersant "Joncryl 819" to a nonionic polymer dispersant ("BYK190" manufactured by BYK). The average particle size of the pigment particles contained in this pigment dispersion was 130 nm.

[0214] <Preparation of Magenta Ink M1> To 20% by weight of magenta pigment dispersion D1 (4% by weight solids), the commercially available resin particle dispersion P1 (addition amount adjusted so that the resin particles (solids) in the ink were 5% by weight), 21% by weight of propylene glycol, 5% by weight of glycerin, 0.2% by weight of surfactant KF351A (Shin-Etsu Silicones), 1% by weight of surfactant E1010 (Nissin Chemical Industry Co., Ltd.), 0.1% by weight of antifungal agent Proxel GXL(S), and ion-exchanged water (the balance; total amount was 100% by weight) were added with stirring, and the resulting mixture was filtered through a 1 μm filter to obtain magenta ink M1. There was no substantial change in composition before and after filtration.

[0215] <Preparation of Magenta Inks M2 to M15> Magenta inks M1 to M15 were prepared in the same manner as in preparation of magenta ink M1, except that the types and amounts of resin particle dispersion, water-soluble solvent, and surfactant were changed as shown in Table III below.

[0216] [Preparation of cyan ink] <Preparation of Cyan Pigment Dispersion D3> A mixture of 20% by mass of cyan pigment (Pigment Blue 15:3) was premixed with 6% by mass of a pigment dispersant (an acrylic dispersant having a carboxyl group neutralized with dimethylaminoethanol (BASF's "Joncryl 819"; acid value 75 mg KOH / g; solids content 20% by mass), 20% by mass of propylene glycol, 0.1% by mass of the antifungal agent Proxel GXL(S), and ion-exchanged water (the remainder; an amount that would make the total amount 100% by mass). The mixture was then dispersed using a bead mill filled with 0.3 mm zirconia beads at a volume ratio of 50% to prepare cyan pigment dispersion D1 with a pigment content of 20% by mass. The average particle size of the pigment particles in this pigment dispersion was 120 nm.

[0217] <Preparation of Cyan Ink C1> To 20% by weight of cyan pigment dispersion D3 (4% by weight solids), the commercially available resin particle dispersion P1 (addition amount adjusted so that the resin particles (solids) in the ink were 5% by weight), 21% by weight of propylene glycol, 5% by weight of glycerin, 0.2% by weight of surfactant KF351A (Shin-Etsu Silicones), 1% by weight of surfactant E1010 (Nissin Chemical Industry Co., Ltd.), 0.1% by weight of antifungal agent, and ion-exchanged water (the balance; total amount: 100% by weight) were added with stirring, and the resulting mixture was filtered through a 1 μm filter to obtain cyan ink C1. There was no substantial change in composition before and after filtration.

[0218] <Adjusting cyan ink C2 and C3> Cyan inks C2 and C3 were prepared in the same manner as ink C1, except that the types and amounts of water-soluble solvents and surfactants, and the amount of antifungal agent were changed as shown in Table III below.

[0219] The abbreviations in Table III are as follows: <Solvent> "EG": Ethylene glycol "PG": Propylene glycol "1,2-PDO": 1,2-pentanediol "1,2-HDO": 1,2-hexanediol "2Me-1,3-PDO": 2-methyl-1,3-propanediol Gly: Glycerin "DEGBE": Diethylene glycol monobutyl ether

[0220] <Surfactant> "E1010": Acetylene glycol surfactant Olfine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.) "KF-351A": Silicone-modified surfactant KF-351A (Shin-Etsu Silicone Co., Ltd.) "TEGOWET KL245": Polyether-modified silicone TEGOWET-KL245 (manufactured by Evonik) "TEGOWET 250": Polyether-modified silicone TEGOWET-250 (manufactured by Evonik) "TEGOWET 260": Polyether-modified silicone TEGOWET-260 (manufactured by Evonik) "BYK3450": Polyether-modified silicone BYK-3450 (manufactured by BYK-Chemie) "BYK3455": Polyether-modified silicone BYK-3455 (manufactured by BYK-Chemie) "BYK348": Polyether-modified silicone BYK-348 (manufactured by BYK-Chemie) "BYK349": Polyether-modified silicone BYK-349 (manufactured by BYK-Chemie)

[0221] <Anti-mold agent> "Proxel GXL(S)": 1,2-benzisothiazolin-3-one

[0222] [Physical Properties] The dynamic surface tension of each of the inks obtained was measured by the following method. <Dynamic surface tension> The dynamic surface tension of the inks M1 to M15 and C1 to C3 prepared above was measured over a surface life of 10 ms to 1,000 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 tensions (unit: mN / m) over a surface life of 15 ms, 100 ms, and 1,000 ms are shown in Table IV.

[0223] <Static surface tension> The static surface tension of the inks M1 to M15 and C1 to C3 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 IV.

[0224] [evaluation] <Injection stability> The inks M1 to M15 and C1 to C3 prepared above were filled into an independently driven inkjet head (360 npi, ejection volume 6 pL, 1024 nozzles) manufactured by Konica Minolta, and a continuous ejection test was carried out for 30 minutes using a strobe-synchronized droplet observation device. After that, the ejection stability was evaluated according to the following criteria. (standard) ◯: Of the 256 nozzles evaluated, all 256 nozzles ejected normally. △: Of the 256 nozzles evaluated, 1 or more but less than 5 nozzles were observed to be abnormally ejecting. ×: Of the 256 nozzles evaluated, 5 or more nozzles were observed to be abnormally ejecting.

[0225] <Ink storage stability> The inks M1 to M15 and C1 to C3 prepared above were stored in a thermostat at 60°C for two weeks, and then the average particle size was measured using a particle size analyzer (Zetasizer Nano S-90).The ink storage stability was then evaluated according to the following criteria. (standard) ◯: 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. △: 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. ×: 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.

[0226] [Table 3]

[0227] [Table 4]

[0228] As shown by the above results, the processing liquid of the present invention, which has a dynamic surface tension in the range of 35 to 45 mN / m at a surface life of 15 ms, is found to have excellent ejection stability and storage stability.

[0229] [Printing test 1] The treatment liquids and inks prepared above were combined as shown in Tables V to X below to form ink sets, and printing tests were carried out in the following manner. As the recording medium M, a PET film (FE2001, thickness 50 μm, manufactured by Futamura Chemical Co., Ltd.) was prepared. A scanning printer (see Figure 4) equipped with two independently driven inkjet heads manufactured by Konica Minolta (360 npi, ejection volume of 6 pL or 14 pL, 1024 nozzles) was prepared, and head H1, which was to be recorded first, was filled with each treatment liquid, and head H2, which was to be recorded later, was filled with each ink. After that, an image with a resolution of 720 x 720 dpi was divided into two in the scanning direction X and the transport direction Y to create four images (180 x 180 dpi), and printing was carried out in one direction, always with the treatment liquid being recorded first, in a four-pass mode in which one printing area is printed four times. The transport speed of carriage C was set to 300 mm / sec, and a drying process was not performed between the printing of the treatment liquid and the ink. The printing test was performed in an environment of 25°C and 50% RH. The recording of the processing liquid was set at a liquid volume of 6 pL and a maximum printing rate of 33%, and was applied in an image-like manner according to the image area of the ink. Also, the recording of the ink was set at a liquid volume of 14 pL and a maximum printing rate of 100%. In the above settings, the amount of the processing liquid applied to the solid part was 1.7 g / m 2 , and the amount of the ink applied to the solid part was 11.9 g / m 2 , and the ratio of the amount of the ink applied to the solid part to the amount of the processing liquid applied (ink application amount / processing liquid application amount) was 7.0 times.

[0230] [Measurement of the drying rate of the processing liquid] In the above printing test 1, when measuring the time from when the processing liquid was applied until the ink was applied, it was calculated to be 0.2 seconds. In the environment of 25°C and 50% RH, when measuring the drying rate of the processing liquid 0.2 seconds after the processing liquid was applied, the drying rate was 1% or less. The drying rate of the processing liquid was calculated by measuring the amount of change in the mass of the processing liquid.

[0231] [Drying of the recording] In the above printing test 1, after applying the ink, the PET film was put into a dryer set at 90°C and heated and dried for 5 minutes to obtain an image recording.

[0232] In addition, Fig. 5 shows the results of measuring the dynamic surface tension of the processing liquid and the ink in Ink Set 1 at 25°C with a surface life of 10 ms to 1000 ms. Also, Fig. 6 shows the results of measuring the dynamic surface tension of the processing liquid and the ink in Ink Set 44 at 25°C with a surface life of 10 ms to 1000 ms.

[0233] [Evaluation] [Crushing of missing characters]< Using the method described above, missing characters of Chinese characters "口, 四, 日, 回, 因, 困, 固, 国, 目, 図, 國" were printed in 5-point and 7-point MS Mincho fonts, and the printed character images were visually observed, and the character quality was evaluated according to the following criteria. (Criteria) ○: All missing characters in 5 points are clearly recorded in detail. △: Only some of the 5-point cut-out characters are legible, but all of the 7-point cut-out characters are legible. ×: Some of the 7-point cut-out characters are illegible.

[0234] <Bleeding of fine lines> A thin line having a width of 3 pixels was recorded by the method described above, and bleeding of the thin line was visually evaluated according to the following criteria. (standard) ○: The thin lines are printed in a straight line. △: The thin lines are bulging in places and printed slightly distorted. ×: The lines are significantly blurred and distorted.

[0235] <Mottled solid areas> A 5 cm x 5 cm solid image was recorded using the method described above, and mottling of the solid image was visually evaluated according to the following criteria. (standard) ◯: No density unevenness is observed in the image when observed from a distance of 15 cm. △: When observed from a distance of 15 cm, density unevenness is observed in part of the image, but from a distance of 30 cm, density unevenness is not observed. ×: When observed from a distance of 30 cm, uneven density was observed in the image.

[0236] <Adhesion> A 5 cm x 5 cm solid image was recorded using the method described above, the printed surface was rubbed with a fingernail, and the adhesion was evaluated according to the following criteria. (standard) ○: The printed surface remains unchanged and cannot be removed even when rubbed with a fingernail. △: Scratches occur when rubbed with a fingernail, and part of the printed surface peels off. ×: The printed surface peels off when rubbed with a fingernail.

[0237] [Table 5]

[0238] [Table 6]

[0239] [Table 7]

[0240] [Table 8]

[0241] [Table 9]

[0242] [Table 10]

[0243] As shown by the above results, it is apparent that the ink set of the present invention suppresses image defects and has excellent adhesion to the substrate, compared to the ink set of the comparative example.

[0244] [Printing test 2] Two independently driven piezo inkjet heads (360 dpi, ejection volume 6 pL) manufactured by Konica Minolta were arranged with their nozzles staggered to create a 720 dpi x 720 dpi head module, which was then installed in the single-pass printer shown in Figure 1 so that the nozzle rows were perpendicular to the transport direction.

[0245] The inkjet head of a head module installed in the treatment liquid application section was filled with the treatment liquid T1 obtained above, and the inkjet head of a head module installed in the ink application section was filled with the ink M1 obtained above. In this way, a single-pass inkjet recording device capable of recording with Ink Set 1 described in Table V was configured.

[0246] Using the inkjet recording device, the same image as in Printing Test 1 was recorded under the recording conditions shown in Table XI, and evaluated using the same indices as in Printing Test 1. A PET film (FE2001, thickness 50 μm, manufactured by Futamura Chemical Co., Ltd.) was prepared as Recording Medium M. The conveying speed during recording was set to 300 mm / sec. The time from application of the treatment liquid to application of the ink was adjusted by allowing the recording medium to wait for a predetermined time after passing through the treatment liquid application section, and then moving it to the ink application section. The drying rate of the treatment liquid was calculated by measuring the mass change rate of the treatment liquid applied to the PET film, which was the amount of solvent that evaporated between the time the treatment liquid was applied and the time the ink was applied. The amounts of treatment liquid and ink applied were adjusted by changing the droplet size and printing rate, respectively. The evaluation results are shown in Table 1. In Table XI, "≦1" means "1% or less."

[0247] [Table 11] [Industrial Applicability]

[0248] The present invention can be used in an ink set and an inkjet recording method that suppress image defects and have excellent adhesion to a substrate. [Explanation of symbols]

[0249] 1. Recording device 10 Processing liquid application section 11 Inkjet head 12 Treatment liquid droplets 20 Ink application unit 21 Inkjet head 22 ink droplets 23 Second drying section 30 Feed roller 40 Winding roller C. Treatment liquid layer F Base material P Image recording R ink layer 50 Canned food packaging materials 51 Tinplate substrate 52 Thermosetting resin layer (base coat) 53 Processing liquid layer 54 Ink Layer 55 Thermosetting resin layer (top coat) C Carriage H1 Head H2 Head X scanning direction Y conveying direction M Recording medium (substrate)

Claims

1. An ink set including an ink and a treatment liquid, The ink contains pigment, resin particles, and an SP value of 24 (J / cm ３ ) 1 / 2 or more and boiling point 1 Contains a water-soluble solvent and a surfactant in the range of 50 to 250°C, The treatment liquid contains a polyvalent metal salt and an SP value of 24 (J / cm ３ ) 1 / 2 or more and boiling point 150 Contains a water-soluble solvent and a surfactant in the range of 250°C, the surfactant of the ink is an acetylene glycol surfactant and a polyether-modified silicone surfactant, or a polyether-modified silicone surfactant, the content of the surfactant in the ink is within a range of 0.1 to 2.0% by mass, the surfactant in the treatment liquid is a polyether-modified silicone surfactant, and the content of the surfactant in the treatment liquid is within a range of 0.1 to 2.0 mass %, 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, At 25°C, the dynamic surface tension of the ink after a surface life of 15 ms is higher by 5 mN / m or more than the dynamic surface tension of the treatment liquid after a surface life of 15 ms; The dynamic surface tension of the ink after 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 after a surface life of 15 ms is in the range of 25 to 35 mN / m; An ink set used in an inkjet recording method in which the treatment liquid is applied to a substrate, and then the ink is applied to an area to which the treatment liquid has been applied while the treatment liquid is still wet, without undergoing a heat drying process.

2. the content of the water-soluble solvent in the ink is within a range of 5 to 40% by mass, 2. The ink set according to claim 1, wherein the content of the water-soluble solvent in the treatment liquid is within a range of 10 to 45% by mass.

3. 2. The ink set according to claim 1, wherein the pigment is dispersed with an anionic polymer dispersant.

4. 2. The ink set according to claim 1, wherein the ink contains 3 to 15% by mass of 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.

5. 2. The ink set according to claim 1, wherein the resin particles contain a water-dispersible polyester resin having a sulfonic acid group.

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

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

8. 2. The ink set according to claim 1, wherein the ink is applied to the area to which the treatment liquid has been applied while the drying rate of the treatment liquid is 30% or less.

9. The ink set according to claim 1 , wherein the ink is applied to the area where the treatment liquid has been applied within 10 seconds after the treatment liquid has been applied to the substrate.

10. 10. The ink set according to claim 1, wherein the amount of the ink applied per unit area is within a range of 2 to 25 times the amount of the treatment liquid applied.

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