Inkjet recording method, production method of melamine decorative board, melamine decorative board

Abstract

To provide an inkjet recording method high in a yellow concentration of an image, and excellent in discharge properties of ink.SOLUTION: An inkjet recording method includes: a process of applying a pretreatment liquid containing at least one flocculant selected from the group consisting of organic acids having a molecular weight of less than 1,000, and polyvalent metal salts, and water on a permeable substrate having an air infiltration resistivity by a Gurley test machine method of 5 seconds to 50 seconds; and a process of applying a yellow ink on a region applied with the pretreatment liquid on the permeable substrate by an inkjet recording method, wherein the yellow ink includes water, an organic solvent having a boiling point of 250°C or higher, C.I. pigment yellow 110, and a carboxyl group-containing resin DY, and a content of the organic solvent having a boiling point of 250°C or higher is 15 mass% to 40 mass% to a total amount of the yellow ink.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to an inkjet recording method, a method for producing a melamine decorative board, and a melamine decorative board. [Background technology]

[0002] 2. Description of the Related Art Various studies have been conducted on image recording using ink jet recording methods. For example, Patent Document 1 describes an ink set for decorative panels that includes cyan ink, magenta ink, and yellow ink and is ejected by an inkjet method, in which each ink composition contains a pigment, and the pigment content C in the cyan ink is less than the pigment content M in the magenta ink or the pigment content Y in the yellow ink. Patent Document 2 describes an inkjet recording method including a step of inkjet printing a color pattern on a paper substrate including an ink-receiving layer, and a step of impregnating the paper substrate with a thermosetting resin. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-001621 [Patent Document 2] US Patent No. 2016 / 0214395 Summary of the Invention [Problem to be solved by the invention]

[0004] CI Pigment Yellow 110 (PY110) is sometimes used as a yellow pigment. When PY110 is used, the yellow density of the resulting image is low, and in particular, when using permeable substrates such as decorative paper and high-quality paper, the ink tends to penetrate into the substrate, resulting in a low yellow density. When attempting to improve the yellow density of the image, the ink ejection properties may be reduced.

[0005] An object of one embodiment of the present disclosure is to provide an inkjet recording method that produces an image with high yellow density and excellent ink ejection properties. Another object of another embodiment of the present disclosure is to provide a method for producing a melamine decorative board using the above-mentioned inkjet recording method, and a melamine decorative board. [Means for solving the problem]

[0006] The present disclosure includes the following aspects. <1> a step of applying a pretreatment liquid containing water and at least one flocculant selected from the group consisting of organic acids having a molecular weight of less than 1000 and polyvalent metal salts to a permeable substrate having an air resistance of 5 seconds to 50 seconds as measured by a Gurley tester; applying a yellow ink by an inkjet recording method to the area on the permeable substrate to which the pretreatment liquid has been applied; The yellow ink is made of water, an organic solvent with a boiling point of 250°C or higher, CI Pigment Yellow 110, and a carboxyl group-containing resin D. Y and An inkjet recording method, wherein the content of the organic solvent having a boiling point of 250° C. or higher is 15% by mass to 40% by mass relative to the total amount of the yellow ink. <2> The amount of flocculant applied to the permeable substrate is 0.08 g / m 2 ~0.35g / m 2 That is, <1> The inkjet recording method according to claim 1. <3> Carboxy group-containing resin D relative to the content of CI Pigment Yellow 110 in yellow ink Y The mass ratio Y of the content is 0.25 to 0.80. <1> or <2> The inkjet recording method according to claim 1. <4> The yellow ink contains an acetylene compound and at least one surfactant selected from polyoxyalkylene alkyl ethers. <1> ~ <3> 10. The inkjet recording method according to claim 9, wherein the ink is a fluororesin. <5> In the yellow ink, the average particle size of CI Pigment Yellow 110 is 100 nm to 160 nm. <1> ~ <4> 10. The inkjet recording method according to claim 9, wherein the ink is a fluororesin. <6> the absolute value of the difference between the surface tension of the yellow ink and the surface tension of the pretreatment liquid is 10 mN / m or less; <1> ~ <5> 10. The inkjet recording method according to claim 9, wherein the ink is a fluororesin. <7> On the area of ​​the permeable substrate where the pretreatment liquid was applied, water, CI Pigment Red 254, and carboxyl group-containing resin D were applied by inkjet recording. M and applying a magenta ink comprising: <1> ~ <6> 10. The inkjet recording method according to claim 9, wherein the ink is a fluororesin. <8> On the area of ​​the permeable substrate where the pretreatment liquid was applied, water, black pigment, and carboxyl group-containing resin D were applied by inkjet recording. K The method further comprises applying a black ink comprising: Carboxy group-containing resin D relative to the content of CI Pigment Yellow 110 in yellow ink Y The mass ratio Y of the content of the carboxyl group-containing resin D to the content of the black pigment in the black ink is K The mass ratio of the content of K is smaller than <1> ~ <7> 10. The inkjet recording method according to claim 9, wherein the ink is a fluororesin. <9> Carboxy group-containing resin D Y is a polymer having no crosslinked structure; <1> ~ <8> 10. The inkjet recording method according to claim 9, wherein the ink is a fluororesin. <10> Carboxy group-containing resin D M is a polymer having a crosslinked structure, <7> The inkjet recording method according to claim 1. <11> Carboxy group-containing resin DK is a polymer having a crosslinked structure, <8> The inkjet recording method according to claim 1. <12> The permeable substrate is decorative paper for decorative laminates. <1> ~ <11> 10. The inkjet recording method according to claim 9, wherein the ink is a fluororesin. <13> <12> obtaining decorative paper having an image recorded thereon by using the inkjet recording method described in 1. and a step of impregnating the decorative paper on which the image is recorded with melamine resin. <14> <13> A melamine decorative board manufactured by the method for manufacturing a melamine decorative board described in claim 1. [Effects of the Invention]

[0007] According to one embodiment of the present disclosure, an inkjet recording method is provided that produces an image with high yellow density and excellent ink ejection properties. According to another embodiment of the present disclosure, there are provided a method for producing a melamine decorative board using the above-described inkjet recording method, and a melamine decorative board. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram conceptually illustrating an example of an inkjet recording apparatus used in an inkjet recording method of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0009] In this specification, a numerical range indicated using "to" means a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this specification, the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in this specification, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the examples.

[0010] In this specification, the amount of each component in a composition means the total amount of the multiple substances present in the composition, unless otherwise specified, when multiple substances corresponding to each component are present in the composition. As used herein, a combination of two or more preferred embodiments is a more preferred embodiment. In this specification, the term "process" refers not only to an independent process but also to a process clearly connected with other processes. Even if they are indistinguishable, they are included in this term as long as the intended purpose of the process is achieved.

[0011] In this specification, the term "image" refers to a film in general, and "image recording" refers to the formation of an image (i.e., a film). The concept of "image" in this specification also includes a solid image.

[0012] In this specification, the term "(meth)acrylate" encompasses both acrylate and methacrylate, and the term "(meth)acrylic acid" encompasses both acrylic acid and methacrylic acid.

[0013] [Inkjet recording method] The inkjet recording method of the present disclosure includes the steps of: applying a pretreatment liquid containing water and at least one flocculant selected from the group consisting of organic acids with a molecular weight of less than 1,000 and polyvalent metal salts to a permeable substrate having an air resistance of 5 to 50 seconds as measured by a Gurley tester (hereinafter also referred to as the "pretreatment liquid application step"); and applying a yellow ink by inkjet recording to the area of ​​the permeable substrate to which the pretreatment liquid has been applied (hereinafter also referred to as the "yellow ink application step"). The yellow ink contains water, an organic solvent having a boiling point of 250°C or higher, PY110, and a carboxyl group-containing resin D. Y The content of the organic solvent having a boiling point of 250° C. or higher is 15% by mass to 40% by mass relative to the total amount of the yellow ink. The inkjet recording method of the present disclosure may include other steps as necessary.

[0014] Generally, when a yellow ink is applied to a permeable substrate, the yellow ink permeates into the permeable substrate, and the yellow density tends to decrease. In contrast to this, in the inkjet recording method of the present disclosure, a pretreatment liquid application step is provided before the yellow ink application step, so that the carboxyl group-containing resin D contained in the yellow ink Y However, the coagulation of the PY110 particles is suppressed by the coagulation agent contained in the pretreatment liquid, preventing the PY110 from penetrating into the permeable substrate. As a result, images with a higher yellow density than before can be obtained. Furthermore, in the inkjet recording method of the present disclosure, the content of the organic solvent having a boiling point of 250°C or higher is 15% by mass to 40% by mass of the total amount of the yellow ink, which prevents the yellow ink from drying and causing aggregates to form near the nozzles, resulting in excellent ejection properties.

[0015] Patent Documents 1 and 2 do not mention the relationship between the pretreatment liquid application step and the yellow density.

[0016] Each step of the inkjet recording method of the present disclosure will be described below.

[0017] <Pretreatment liquid application step> The inkjet recording method of the present disclosure includes a pretreatment liquid application step. The pretreatment liquid application step is a step of applying a pretreatment liquid containing water and at least one flocculant selected from the group consisting of organic acids having a molecular weight of less than 1000 and polyvalent metal salts to a permeable substrate having an air resistance of 5 to 50 seconds as measured by the Gurley tester.

[0018] (permeable base material) The substrate used in the inkjet recording method of the present disclosure is a permeable substrate having an air resistance of 5 seconds to 50 seconds according to the Gurley tester method. In the inkjet recording method of the present disclosure, a pretreatment liquid application step is provided when a specific yellow ink is used, and therefore the yellow density of the image can be increased even when a permeable substrate is used.

[0019] The air resistance according to the Gurley tester method is measured by the method described in JIS P8117:2009.

[0020] Examples of permeable substrates include decorative paper, plain paper, fine paper, and recycled paper. The permeable substrate preferably does not have an ink-receiving layer on its surface. Coated paper such as art paper and coated paper that are commonly available on the market does not fall under the category of the permeable substrate.

[0021] Preferably, the permeable substrate comprises paper.

[0022] The permeable substrate, including paper, may be commercially available. Commercially available products include, for example, High-quality paper (A) such as "OK Prince High-Quality" manufactured by Oji Paper Co., Ltd., "Shiraoi" manufactured by Nippon Paper Industries Co., Ltd., and "New NPI High-Quality" manufactured by Nippon Paper Industries Co., Ltd.; Form paper such as "NPi Form" manufactured by Nippon Paper Industries Co., Ltd.; Examples include:

[0023] The permeable substrate is preferably decorative paper for decorative panels. Examples of decorative boards include high-pressure melamine decorative boards, low-pressure melamine decorative boards, polyester decorative boards, and DAP decorative boards.

[0024] The decorative paper may be a commercially available product. Commercially available products include, for example, Felix Scherrer MPK3007, MPK7299, MPK9653; KCW-801P, KSH-801P, KW-1001P made by KJ Specialty Paper Examples include:

[0025] According to the inkjet recording method of the present disclosure, it is possible to record an image with a high yellow density and a wood grain pattern.

[0026] (Pretreatment liquid) The pretreatment liquid contains water and at least one flocculant selected from the group consisting of organic acids having a molecular weight of less than 1000 and polyvalent metal salts.

[0027] -water- The pretreatment liquid contains water. The water content is preferably 60% by mass or more, and more preferably 70% by mass or more, based on the total amount of the pretreatment liquid. The upper limit of the water content is preferably 90% by mass or less, and more preferably 85% by mass or less, based on the total amount of the pretreatment liquid, although this depends on the amounts of other components.

[0028] -Flocculant- The pretreatment liquid of the present disclosure contains at least one flocculant selected from the group consisting of an organic acid having a molecular weight of less than 1000 and a polyvalent metal salt.

[0029] From the viewpoint of improving the yellow density, the flocculant preferably contains an organic acid having a molecular weight of less than 1,000. The molecular weight of the organic acid is calculated from the type and number of atoms that constitute the compound.

[0030] An organic acid is an organic compound that contains an acidic group. Acidic groups include phosphate groups, phosphonate groups, phosphinate groups, sulfate groups, sulfonate groups, sulfinate groups, and carboxy groups. Among these, from the viewpoint of the aggregation speed of the ink, the acidic group is preferably a phosphate group or a carboxy group, and more preferably a carboxy group.

[0031] It is preferable that at least a portion of the acidic groups is dissociated in the pretreatment liquid.

[0032] Examples of organic compounds having a carboxy group include (meth)acrylic acid, poly(meth)acrylic acid, acetic acid, formic acid, benzoic acid, glycolic acid, malonic acid, malic acid (preferably DL-malic acid), maleic acid, succinic acid, glutaric acid, pimelic acid, adipic acid, fumaric acid, citric acid, tartaric acid, phthalic acid, 4-methylphthalic acid, lactic acid, pyrrolidonecarboxylic acid, pyronecarboxylic acid, pyrrolecarboxylic acid, furancarboxylic acid, pyridinecarboxylic acid, coumaric acid, thiophenecarboxylic acid, and nicotinic acid.

[0033] Among these, from the viewpoint of the aggregation speed of the ink, the organic compound having a carboxy group is preferably a divalent or higher carboxylic acid (hereinafter also referred to as a polycarboxylic acid), and more preferably a dicarboxylic acid.

[0034] Specifically, the polycarboxylic acid is preferably malonic acid, malic acid, maleic acid, succinic acid, glutaric acid, pimelic acid, adipic acid, fumaric acid, tartaric acid, 4-methylphthalic acid, or citric acid, and more preferably malonic acid, malic acid, tartaric acid, succinic acid, glutaric acid, pimelic acid, adipic acid, or citric acid.

[0035] The organic acid preferably has a low pKa (for example, 1.0 to 5.0), which reduces the surface charge of particles such as pigments and resin particles in the ink, which are stabilized by weakly acidic functional groups such as carboxyl groups, by contacting them with an organic acid having a lower pKa, thereby reducing dispersion stability.

[0036] The organic acid preferably has a low pKa, high solubility in water, and a valence of at least 2. Furthermore, it is more preferable that the organic acid have a high buffering capacity in a pH range lower than the pKa of the functional group (e.g., carboxy group) that stabilizes the dispersion of the particles in the ink.

[0037] Examples of polyvalent metal salts include salts of alkaline earth metals of Group 2 of the periodic table (e.g., magnesium, calcium), salts of transition metals of Group 3 of the periodic table (e.g., lanthanum), salts of metals of Group 13 of the periodic table (e.g., aluminum), and salts of lanthanides (e.g., neodymium). As the polyvalent metal salt, calcium salt, magnesium salt, or aluminum salt is preferred, and calcium salt or magnesium salt is more preferred.

[0038] It is preferred that the polyvalent metal salt is at least partially dissociated into polyvalent metal ions and counter ions in the pretreatment liquid.

[0039] The content of the flocculant in the pretreatment liquid is preferably 1.0 mass % to 30 mass %, more preferably 3.0 mass % to 25 mass %, and even more preferably 5.0 mass % to 20 mass %, relative to the total amount of the pretreatment liquid.

[0040] -Organic solvents- The pretreatment liquid may contain at least one organic solvent. The type of organic solvent is not limited, and examples thereof include: Monoalcohols with 1 to 4 carbon atoms; Diols such as 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 2-butene-1,4-diol, 2-ethyl-1,3-hexanediol, 2-methyl-2,4-pentanediol, 1,2-octanediol, 1,2-hexanediol, 1,2-pentanediol, and 4-methyl-1,2-pentanediol; Triols such as glycerin, 1,2,6-hexanetriol, and trimethylolpropane ; alkylene glycols such as ethylene glycol and propylene glycol; alkylene glycol monoalkyl ethers such as ethylene glycol monoalkyl ether and propylene glycol monoalkyl ether; polyalkylene glycols such as diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, dipropylene glycol, and polyoxyethylene polyoxypropylene glycol; polyalkylene glycol ethers such as diethylene glycol monoalkyl ether, triethylene glycol monoalkyl ether, tripropylene glycol monoalkyl ether, and polyoxypropylene glyceryl ether; 2-pyrrolidone, N-methyl-2-pyrrolidone; etc.

[0041] The content of the organic solvent is preferably 1% by mass to 20% by mass, and more preferably 3% by mass to 10% by mass, based on the total amount of the pretreatment liquid.

[0042] -Surfactants- The pretreatment liquid may contain at least one surfactant. The type of surfactant is not particularly limited, and may be any of anionic surfactants, cationic surfactants, betaine surfactants, and nonionic surfactants. Examples of surfactants include acrylic surfactants, fluorine-based surfactants, and silicone-based surfactants. The surfactant may also function as an anti-foaming agent.

[0043] The content of the surfactant is preferably 0.01% by mass to 6% by mass, and more preferably 0.1% by mass to 4% by mass, relative to the total amount of the pretreatment liquid.

[0044] -Other ingredients- The pretreatment liquid may contain other components in addition to those described above, if necessary. Other components that can be contained in the pretreatment liquid include known additives such as solid wetting agents, colloidal silica, inorganic salts, anti-fading agents, emulsion stabilizers, penetration enhancers, UV absorbers, preservatives, anti-fungal agents, pH adjusters, viscosity adjusters, rust inhibitors, chelating agents, and water-soluble polymer compounds (for example, the water-soluble polymer compounds described in paragraphs 0026 to 0080 of JP 2013-001854 A).

[0045] -Physical properties of pretreatment liquid- The pH of the pretreatment liquid is preferably 0.2 to 7.0, more preferably 0.5 to 6.0, and even more preferably 1.0 to 5.0. Here, pH refers to the pH at 25°C. The pH is measured at 25°C using, for example, a pH meter (for example, a pH meter manufactured by Toa DKK Co., Ltd. (model number "HM-31")).

[0046] The viscosity of the pretreatment liquid is preferably 0.5 mPa·s to 20 mPa·s, and more preferably 1 mPa·s to 10 mPa·s. The viscosity is measured at 25°C using a viscometer, for example, a TV-22 viscometer manufactured by Toki Sangyo Co., Ltd.

[0047] The surface tension of the pretreatment liquid is preferably 60 mN / m or less, more preferably 20 mN / m to 50 mN / m, and even more preferably 30 mN / m to 45 mN / m. The surface tension is a value measured at a temperature of 25°C. The surface tension is measured using a surface tensiometer. The surface tension is measured at 25° C. using, for example, an automatic surface tensiometer (product name "CBVP-Z") manufactured by Kyowa Interface Science Co., Ltd., by the plate method.

[0048] (Application of pre-treatment liquid) The method for applying the pretreatment liquid is not particularly limited, and examples thereof include known methods such as a coating method, a dipping method, and an inkjet recording method.

[0049] Examples of the coating method include known coating methods using a bar coater, extrusion die coater, air doctor coater, blade coater, rod coater, knife coater, squeeze coater, reverse roll coater, and the like.

[0050] The amount of pretreatment liquid applied was 0.1 g / m 2 ~20g / m 2 It is preferable that the density is 0.5 g / m 2 ~10g / m 2 More preferably, it is 1 g / m 2 ~5g / m 2 It is more preferable that:

[0051] The amount of flocculant applied to the permeable substrate is 0.08 g / m 2 ~0.35g / m 2 It is preferable that the 2 ~0.31g / m 2 More preferably, it is 0.12 g / m 2 ~0.27g / m 2 It is more preferable that: The amount of flocculant applied is 1m 2 Mass per unit (g / m 2 ) means The amount of flocculant applied is determined by the amount of pretreatment liquid applied (g / m 2 ) and the content (mass %) of the flocculant contained in the pretreatment liquid. The amount of flocculant to be applied can be adjusted by adjusting at least one of the amount of pretreatment liquid to be applied and the content of the flocculant contained in the pretreatment liquid.

[0052] The amount of flocculant applied was 0.08 g / m 2 In this case, the flocculant is a carboxyl group-containing resin D contained in the yellow ink. Y This reacts with the ink, effectively retaining PY110 on the surface of the ink film. It also effectively inhibits the penetration of PY110 into permeable substrates, improving the yellow density of the image. In addition, the amount of flocculant applied was 0.35 g / m 2When the concentration is below this level, the action of the aggregating agent prevents excessive aggregation of PY110 molecules, allowing them to be uniformly present in the in-plane direction of the ink film. Generally, when PY110 aggregates and its concentration increases, the hue of the resulting image tends to become reddish. By ensuring that PY110 is uniformly present in the in-plane direction of the ink film, it is possible to prevent color unevenness, such as the presence of a reddish hue within a yellow hue in the image.

[0053] (Heat drying of pre-treatment liquid) The pretreatment liquid application step may include applying the pretreatment liquid onto the permeable substrate, and heating and drying the pretreatment liquid applied onto the permeable substrate. Examples of means for heating and drying the pretreatment liquid include known heating means such as a heater, known air blowing means such as a dryer, and a combination of these.

[0054] Examples of methods for heating and drying the pretreatment liquid include a method of applying heat using a heater or the like from the side opposite to the surface of the permeable substrate to which the pretreatment liquid has been applied, a method of applying warm air or hot air to the surface of the permeable substrate to which the pretreatment liquid has been applied, a method of applying heat using an infrared heater from the side of the permeable substrate to which the pretreatment liquid has been applied or the side opposite to the surface to which the pretreatment liquid has been applied, and a combination of these methods.

[0055] The heating temperature during heating and drying of the pretreatment liquid is preferably 40°C or higher, and more preferably 45°C or higher. The upper limit of the heating temperature is not particularly limited, and is, for example, 150°C. The heating time is not particularly limited, but is preferably 0.1 to 30 seconds, more preferably 0.2 to 10 seconds, and particularly preferably 0.5 to 5 seconds.

[0056] <Yellow ink application process> The inkjet recording method of the present disclosure includes a yellow ink application step. The yellow ink application step is a step of applying yellow ink by inkjet recording onto the area on the permeable substrate to which the pretreatment liquid has been applied. In this process, the yellow ink is applied to the area on the permeable substrate to which the pretreatment liquid has been applied, whereby the components in the yellow ink (e.g., PY110) are aggregated on the permeable substrate by the action of the aggregating agent, thereby obtaining an image.

[0057] (yellow ink) The yellow ink is made of water, an organic solvent with a boiling point of 250°C or higher, PY110, and a carboxyl group-containing resin D. Y and,

[0058] -water- The water content is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more, based on the total amount of the yellow ink. The upper limit of the water content depends on the amounts of other components, and is, for example, 90% by mass or 80% by mass relative to the total amount of the yellow ink.

[0059] -PY110- The yellow ink contains PY110, which has excellent lightfastness. The yellow ink may contain a yellow pigment other than PY110. The proportion of PY110 in the yellow pigment is preferably 80% by mass or more, and more preferably 90% by mass or more. More preferably, the yellow pigment contained in the yellow ink of the present disclosure is PY110 alone.

[0060] In the yellow ink, the average particle size of PY110 is preferably 100 nm to 160 nm, more preferably 110 nm to 150 nm, and even more preferably 110 nm to 140 nm.

[0061] When the average particle size is 100 nm or more, the light resistance is excellent. When the average particle size is 160 nm or less, the yellow density is improved. Furthermore, when the yellow ink reacts with the aggregating agent contained in the pretreatment liquid, local aggregation of PY110 is suppressed. As a result, color unevenness, including reddish hues, is suppressed. Furthermore, aggregation is less likely to occur inside the nozzle, resulting in excellent ejection performance.

[0062] The average particle size is a value measured by a particle size distribution measuring device (for example, Microtrac UPA (registered trademark) EX150 manufactured by Nikkiso Co., Ltd.).

[0063] The content of PY110 relative to the total amount of the yellow ink is preferably 2.0% by mass to 8.0% by mass, more preferably 2.5% by mass to 7.0% by mass, and even more preferably 3.5% by mass to 6.0% by mass.

[0064] -Carboxy group-containing resin D Y - The yellow ink of the present disclosure contains carboxyl group-containing resin D Y Contains:

[0065] In the present disclosure, a resin refers to a compound having a weight average molecular weight (Mw) of 1000 or more.

[0066] In this disclosure, the weight-average molecular weight (Mw) refers to a value measured by gel permeation chromatography (GPC). Measurements by gel permeation chromatography (GPC) were performed using an HLC®-8020GPC (manufactured by Tosoh Corporation) as a measuring device, three TSKgel® Super Multipore HZ-H columns (4.6 mm ID x 15 cm, manufactured by Tosoh Corporation), and THF (tetrahydrofuran) as an eluent. Measurements were performed using an RI detector at a sample concentration of 0.45% by mass, a flow rate of 0.35 ml / min, a sample injection volume of 10 μl, and a measurement temperature of 40°C. A calibration curve was prepared using eight samples of "TSK standard, polystyrene" (manufactured by Tosoh Corporation): "F-40," "F-20," "F-4," "F-1," "A-5000," "A-2500," "A-1000," and "n-propylbenzene."

[0067] Carboxy group-containing resin D Y is not particularly limited as long as it is a resin (polymer) containing a carboxy group. The form of the resin is not particularly limited, and may be any of a random polymer, a block polymer, and a graft polymer. Y may be a polymer having a crosslinked structure or a polymer not having a crosslinked structure.

[0068] Carboxy group-containing resin D Y is preferably a copolymer containing a structural unit derived from a monomer containing a carboxy group (hereinafter referred to as a "carboxy group-containing monomer"). The structural unit derived from the carboxy group-containing monomer contained in the copolymer may be of only one type, or may be of two or more types.

[0069] Examples of carboxy group-containing monomers include (meth)acrylic acid, β-carboxyethyl acrylate, fumaric acid, itaconic acid, maleic acid, and crotonic acid.

[0070] From the viewpoint of dispersion stability, the carboxy group-containing monomer is preferably (meth)acrylic acid or β-carboxyethyl acrylate, and more preferably (meth)acrylic acid.

[0071] The content of structural units derived from carboxyl group-containing monomers is 100% of that of carboxyl group-containing resin D. Y The content of the component (A) is preferably 5% by mass to 40% by mass, more preferably 10% by mass to 35% by mass, and even more preferably 10% by mass to 30% by mass, based on the total amount of the component (A).

[0072] Carboxy group-containing resin D Y The Carboxy Group-Containing Resin D preferably contains a structural unit derived from a monomer having a hydrophobic group (hereinafter referred to as a "hydrophobic monomer") in addition to a structural unit derived from a carboxy group-containing monomer. Y The structural unit derived from the hydrophobic monomer contained in may be of only one type, or may be of two or more types.

[0073] Examples of hydrophobic monomers include (meth)acrylates having an alkyl group with 1 to 20 carbon atoms, (meth)acrylates having an aromatic ring (for example, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, etc.), styrene, and styrene derivatives.

[0074] Carboxy group-containing resin D Y From the viewpoint of dispersion stability, the acid value is preferably 50 mgKOH / g to 250 mgKOH / g, more preferably 70 mgKOH / g to 240 mgKOH / g, and even more preferably 90 mgKOH / g to 230 mgKOH / g. In the present disclosure, the acid value can be measured by titration of an indicator, and is a value measured by the method described in Japanese Industrial Standards (JIS K0070:1992).

[0075] Carboxy group-containing resin D YThe weight average molecular weight (Mw) is preferably from 1,000 to 100,000, more preferably from 5,000 to 80,000, and even more preferably from 10,000 to 50,000.

[0076] Carboxy group-containing resin D Y Preferably, the pigment functions as a dispersant to disperse PY110 in the yellow ink.

[0077] Carboxy group-containing resin D Y When the polymer is one that does not have a crosslinked structure, when the yellow ink reacts with the flocculant contained in the pretreatment liquid, the PY110 particles do not aggregate excessively, and color unevenness including a reddish hue can be suppressed. From the above viewpoint, carboxyl group-containing resin D Y is preferably a polymer that does not have a crosslinked structure.

[0078] Carboxy group-containing resin D relative to the content of PY110 Y The mass ratio Y of the content is preferably 0.25 to 0.80, and more preferably 0.25 to 0.60. When the mass ratio Y is 0.25 or more, PY110 is a carboxyl group-containing resin D Y As a result, agglomerates are less likely to form inside the nozzle, resulting in excellent discharge properties. If the mass ratio Y is 0.80 or less, when the yellow ink reacts with the aggregating agent contained in the pretreatment liquid, the PY110 particles do not aggregate excessively, and color unevenness including reddish hues is suppressed.

[0079] -Organic solvents- The yellow ink contains an organic solvent with a boiling point of 250° C. or higher (high boiling point solvent). When a high boiling point solvent is contained, the ejection properties of the yellow ink are improved. In this disclosure, boiling point means the boiling point at 1 atmosphere (101,325 Pa).

[0080] Examples of organic solvents with a boiling point of 250°C or higher include glycerin (boiling point 290°C), triethylene glycol (boiling point 285°C), tripropylene glycol (boiling point 267°C), trimethylolpropane (boiling point 295°C), and triethylene glycol monobutyl ether (boiling point 276°C).

[0081] From the viewpoint of the ejection properties of the yellow ink, the content of the high-boiling point solvent is 15% by mass to 40% by mass, more preferably 17% by mass to 35% by mass, and even more preferably 20% by mass to 30% by mass, relative to the total amount of the yellow ink. The yellow ink may contain an organic solvent with a boiling point of less than 250° C. (low boiling point solvent).

[0082] Examples of water-soluble organic solvents with a boiling point of less than 250°C include 1,2-propanediol (boiling point 188°C), 1,3-propanediol (boiling point 213°C), propylene glycol monomethyl ether (boiling point 121°C), ethylene glycol (boiling point 197°C), ethylene glycol monomethyl ether (boiling point 124°C), propylene glycol monoethyl ether (boiling point 133°C), ethylene glycol monoethyl ether (boiling point 135°C), propylene glycol monopropyl ether (boiling point 149°C), ethylene glycol monopropyl ether (boiling point 151°C), propylene glycol monobutyl ether (boiling point 170°C), and ethylene glycol monobutyl ether (boiling point 171°C). , 2-ethyl-1-hexanol (boiling point 187°C), dipropylene glycol monomethyl ether (boiling point 188°C), diethylene glycol dimethyl ether (boiling point 162°C), diethylene glycol diethyl ether (boiling point 188°C), dipropylene glycol dimethyl ether (boiling point 175°C), 1,2-hexanediol (boiling point 223°C), diethylene glycol (boiling point 245°C), diethylene glycol monobutyl ether (boiling point 230°C), dipropylene glycol (boiling point 232°C), 2-pyrrolidone (boiling point 245°C), tripropylene glycol monomethyl ether (boiling point 243°C), and triethylene glycol monomethyl ether (boiling point 248°C).

[0083] From the viewpoint of ejection performance, the content of the low boiling point solvent is preferably 5% by mass to 25% by mass, and more preferably 10% by mass to 20% by mass, relative to the total amount of the yellow ink.

[0084] From the viewpoint of ejection properties, the mass ratio of the content of the low boiling point solvent to the content of the high boiling point solvent is preferably 0.1 to 1.5, and more preferably 0.3 to 1.2.

[0085] -Surfactants- The yellow ink preferably contains at least one surfactant. The type of surfactant is not particularly limited, and may be any of anionic surfactants, cationic surfactants, betaine surfactants, and nonionic surfactants. Examples of surfactants include acrylic surfactants, fluorine-based surfactants, and silicone-based surfactants.

[0086] In particular, the yellow ink preferably contains at least one surfactant selected from an acetylene compound and a polyoxyalkylene alkyl ether (hereinafter also referred to as "surfactant W"). When the yellow ink contains surfactant W, PY110 can be uniformly distributed in the in-plane direction of the ink film when the yellow ink reacts with the aggregating agent contained in the pretreatment liquid, thereby suppressing color unevenness, including reddish hues.

[0087] Examples of acetylene compounds include: acetylene glycols selected from the group consisting of 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, 2,5,6,11-tetramethyl-6-dodecyne-5,8-diol, 2,5-dimethyl-3-hexyne-2,5-diol, and 2,5,8,11-tetramethyl-6-dodecyne-5,8-diol; and ethylene oxide adducts of the above acetylene glycols.

[0088] The acetylene compound can be synthesized, for example, by reacting acetylene with a ketone or aldehyde corresponding to the target acetylene glycol.

[0089] The acetylene compound can be obtained, for example, by the method described in Takehiko Fujimoto, revised edition, "New Introduction to Surfactants" (published by Sanyo Chemical Industries, Ltd., 1992), pp. 94-107.

[0090] The acetylene compound may be a commercially available product. Commercially available acetylene compounds include, for example: Surfynol 104E (HLB value 4), Surfynol 104H (HLB value 4), Surfynol 104A (HLB value 4), Surfynol 104PA (HLB value 4), Surf Surfynol 104PG-50 (HLB value 4), Surfynol 104S (HLB value 4), Surfynol 420 (HLB value 4), Surfynol 440 (HLB value 8), Surfynol 465 (HLB value 13), Surfynol 485 (HLB value 17), Surfynol SE (HLB value 6), Surfynol SE-F (HLB value 6), Surfynol 61 (HLB value 6), Surfynol 82 (HLB value 4), Surfynol DF110D (HLB value 3), Dynol 604 (HLB value 4) Examples of suitable acrylic acid surfactants include acrylic acid surfactants such as acrylic acid esters (HLB value 8), DINO 607 (HLB value 8), Surfynol 2502 (HLB value 8), Surfynol TG (HLB value 9), Olfine E1004 (HLB value: 7-9), Olfine E1010 (HLB value: 13-14) (all manufactured by Evonik Industries), Acetylenol E00, Acetylenol E13T, Acetylenol E40, Acetylenol E60, Acetylenol E100, and Acetylenol E200 (all manufactured by Kawaken Fine Chemicals Co., Ltd.).

[0091] The polyoxyalkylene alkyl ether is preferably an ethylene oxide adduct of alcohol or an ethylene oxide and propylene oxide adduct of alcohol, more preferably an ethylene oxide adduct of alcohol (that is, a polyoxyethylene alkyl ether compound).

[0092] As the polyoxyalkylene alkyl ether, a compound represented by the following formula (1) is more preferred. R 1 O-[(EO) m / (PO) n ]-H … Formula (1)

[0093] In formula (1), R 1 represents a hydrocarbon group having 6 to 30 carbon atoms, EO represents an ethyleneoxy group, and PO represents a propyleneoxy group.

[0094] In formula (1), m and n represent the average number of moles added, m is 2 to 100, n is 0 to 50, and the sum of m and n is 2 to 120.

[0095] In formula (1), the notation "(EO)m / (PO)n" indicates that the arrangement of EO and PO may be that of a random copolymer or that of a block copolymer. m / (PO) n In the portion indicated as "," the order of addition of EO and PO does not matter.

[0096] In formula (1), when n is 2 or more, the compound represented by formula (1) may be a block copolymer or a random copolymer. When the compound represented by formula (1) is a block copolymer, it is preferably a compound in which an oxyethylene group is located on the hydroxy group side, i.e., RO-(PO)(EO)-H. When the compound represented by formula (1) is a block copolymer, it may be a triblock copolymer of RO-(EO)(PO)(EO)-H.

[0097] Commercially available polyoxyalkylene alkyl ether compounds include: Ethylene oxide adducts of lauryl alcohol include Emulgen 102 (HLB: 6.3, average number of moles of EO added: 2), Emulgen 103 (HLB: 8.1, average number of moles of EO added: 3), Emulgen 103 (HLB: 9.7, average number of moles of EO added: 4), Emulgen 108 (HLB: 12.1, average number of moles of EO added: 6), Emulgen 109P (HLB: 13.6, average number of moles of EO added: 8), Emulgen 120 (HLB: 15.3, average number of moles of EO added: 13), Emulgen 147 (HLB: 16.3, average number of moles of EO added: 17), and Emulgen 148 (HLB: 15.3, average number of moles of EO added: 16), all manufactured by Kao Corporation. Examples of ethylene oxide adducts of secondary alcohols having 12 carbon atoms include Tergitol TMN-3 (HLB: 8.1, average number of moles of EO added: 3), Triton HW-1000 (HLB: 10, average number of moles of EO added: 6), Tergitol TMN-6 (HLB: 13.1, average number of moles of EO added: 8), Tergitol TMN-100X (HLB: 14.0, average number of moles of EO added: 9), and Tergitol TMN-10 (HLB: 14.4, average number of moles of EO added: 10), all manufactured by The Dow Chemical Company. Other commercially available polyoxyalkylene alkyl ether compounds include Emulgen 707 (ethylene oxide adduct of secondary alcohol having 11 to 15 carbon atoms, HLB: 12.1, average number of moles of EO added: 6) and Emulgen 220 (ethylene oxide adduct of linear primary alcohol having 16 to 18 carbon atoms, HLB: 14.2, average number of moles of EO added: 13) manufactured by Kao Corporation.

[0098] The content of surfactant W is preferably 0.1% by mass to 2% by mass, and more preferably 0.3% by mass to 1% by mass, relative to the total amount of the yellow ink.

[0099] The yellow ink may contain a surfactant other than surfactant W. From the viewpoint of suppressing color unevenness including reddish hues, it is preferable that the yellow ink contains only surfactant W as the surfactant.

[0100] -Other ingredients- The yellow ink may contain other components in addition to those described above, as necessary. Other components that can be contained in the yellow ink include known additives such as resin particles, water-soluble resins, colloidal silica, solid wetting agents, inorganic salts, anti-fading agents, emulsion stabilizers, penetration enhancers, ultraviolet absorbers, preservatives, antifungal agents, pH adjusters, viscosity adjusters, rust inhibitors, and chelating agents.

[0101] It is preferable that the yellow ink contains substantially no resin particles. If the yellow ink does not contain resin particles, aggregates are less likely to form inside the nozzle, resulting in excellent ejection properties. Note that "substantially no resin particles" means that the content of resin particles is 0.5% by mass or less relative to the total amount of the yellow ink. The content of resin particles is more preferably 0.1% by mass or less.

[0102] -Physical properties of yellow ink- The pH (25° C.) of the yellow ink is preferably 7.0 to 10.0, more preferably 7.5 to 9.5, and even more preferably 8.0 to 9.0. The pH of the yellow ink is measured in the same manner as the pH of the pretreatment liquid.

[0103] The viscosity of the yellow ink (30° C.) is preferably 2.0 mPa·s to 15.0 mPa·s, more preferably 3.0 mPa·s to 10.0 mPa·s, and even more preferably 3.5 mPa·s to 7.0 mPa·s. The viscosity of the yellow ink is measured in the same manner as the viscosity of the pretreatment liquid.

[0104] The surface tension of the yellow ink is preferably 60 mN / m or less, more preferably 20 mN / m to 55 mN / m, and even more preferably 30 mN / m to 45 mN / m. The surface tension of the yellow ink is measured in the same manner as the surface tension of the pretreatment liquid.

[0105] The absolute value of the difference between the surface tension of the yellow ink and the surface tension of the pretreatment liquid is preferably 10 mN / m or less, and more preferably 5 mN / m or less. When the value obtained by subtracting the surface tension of the yellow ink from the surface tension of the pretreatment liquid is 0 mN / m to 10 mN / m, a decrease in the yellow density is suppressed. When the value obtained by subtracting the surface tension of the pretreatment liquid from the surface tension of the yellow ink is 0 mN / m to 10 mN / m, PY110 can be uniformly distributed in the in-plane direction of the ink film, and color unevenness including reddish hues is suppressed.

[0106] (Application of yellow ink by inkjet recording method) As the ink jet recording method, a known method can be applied. Inkjet recording methods include, for example, a charge control method that uses electrostatic attraction to eject ink, a drop-on-demand method (pressure pulse method) that uses the vibration pressure of a piezoelectric element, an acoustic inkjet method that converts an electric signal into an acoustic beam and irradiates the ink with it, thereby ejecting the ink using radiation pressure, and a thermal inkjet (Bubble Jet (registered trademark)) method that heats the ink to form bubbles and uses the resulting pressure.

[0107] Inkjet heads used in inkjet recording methods include a shuttle method, which uses a short serial head and performs recording by scanning the head in the width direction of the recording medium, and a line method, which uses a line head in which recording elements are arranged to correspond to the entire area of ​​one side of the recording medium.

[0108] In the line method, a pattern can be formed over the entire surface of a recording medium by scanning the recording medium in a direction intersecting the arrangement direction of the recording elements, eliminating the need for a transport system such as a carriage for scanning a short head. Furthermore, the line method does not require complex scanning control of the carriage movement and the recording medium, and only the recording medium moves, making it possible to achieve a faster recording speed than the shuttle method.

[0109] The droplet volume of ink ejected from the inkjet head is preferably 1 pL (picoliter) to 100 pL, more preferably 1.5 pL to 80 pL, and even more preferably 1.8 pL to 50 pL.

[0110] The amount of yellow ink applied is 1 g / m 2 ~20g / m 2 It is preferable that the density is 2 g / m 2 ~14g / m 2 It is preferable that the density is 3 g / m 2 ~8g / m 2 It is more preferable that:

[0111] The inkjet recording method of the present disclosure may include, after the yellow ink application step, a step of heating and drying the yellow ink applied to the permeable substrate. Examples of the heating and drying means include known heating means such as a heater, known air blowing means such as a dryer, and a combination of these.

[0112] Specifically, methods for heating the permeable substrate include a method of applying heat using a heater or the like from the side opposite to the side of the permeable substrate to which the yellow ink has been applied; a method of applying warm or hot air to the side of the permeable substrate to which the yellow ink has been applied; a method of applying heat using an infrared heater from the side of the side of the permeable substrate to which the yellow ink has been applied or from the side opposite to this side; and a method that combines two or more of these methods.

[0113] The heating temperature during heat drying of the yellow ink is preferably 55° C. or higher, more preferably 60° C. or higher, and particularly preferably 65° C. or higher. The upper limit of the heating temperature is not particularly limited, and is, for example, 150°C. The heating time is not particularly limited, but is preferably 0.1 to 60 seconds, more preferably 0.5 to 30 seconds, and particularly preferably 1.0 to 10 seconds.

[0114] <Magenta ink application process> The inkjet recording method of the present disclosure includes a magenta ink application step. The magenta ink application step is a step of applying magenta ink by inkjet recording onto the area on the permeable substrate to which the pretreatment liquid has been applied. In this process, by applying the magenta ink together with the yellow ink onto the area on the permeable substrate where the pretreatment liquid has been applied, color unevenness including the reddish hue based on PY110 becomes less visible.

[0115] (magenta ink) The magenta ink is made of water, magenta pigment, and carboxyl group-containing resin D. M It is preferred that the compound contains:

[0116] -water- The water content is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more, based on the total amount of the magenta ink. The upper limit of the water content depends on the amounts of other components, and is, for example, 90% by mass or 80% by mass relative to the total amount of the magenta ink.

[0117] -Magenta pigment- The magenta ink of the present disclosure preferably contains a magenta pigment. Examples of magenta pigments include CI Pigment Red 122, 150, 171, 175, 177, 209, 224, 242, 254, 255, and 264, and CI Pigment Violet 19, 23, and 32.

[0118] Among these, the magenta pigment preferably contains CI Pigment Red 254 (PR254). PR254 has a strong reddish tint. Therefore, by using magenta ink containing PR254 in combination with yellow ink, color unevenness including the reddish hue based on PY110 becomes less visible.

[0119] The proportion of PR254 in the magenta pigment is preferably 80% by mass or more, and more preferably 90% by mass or more. More preferably, the magenta pigment contained in the magenta ink of the present disclosure is PR254 alone.

[0120] The content of the magenta pigment is preferably 2.0% by mass to 8.0% by mass, and more preferably 3.0% by mass to 6.0% by mass, relative to the total amount of the magenta ink.

[0121] -Carboxy group-containing resin D M - Magenta ink is made from carboxyl group-containing resin D M It is preferred that the compound contains:

[0122] Carboxy group-containing resin D M is not particularly limited as long as it is a resin (polymer) containing a carboxy group. The form of the resin is not particularly limited, and may be any of a random polymer, a block polymer, and a graft polymer. M may be a polymer having a crosslinked structure or a polymer not having a crosslinked structure.

[0123] Carboxy group-containing resin D M A preferred embodiment of the carboxyl group-containing resin D Y This is the same as the preferred embodiment of the above.

[0124] Carboxy group-containing resin D M Preferably, the pigment functions as a dispersant that disperses the magenta pigment in the magenta ink.

[0125] Carboxy group-containing resin D M When the polymer is a polymer having a crosslinked structure, when the magenta ink reacts with the aggregating agent contained in the pretreatment liquid, the magenta pigment particles tend to aggregate together, improving the magenta density. By using yellow ink and magenta ink together, color unevenness, including the reddish hue caused by PY110, becomes less visible. In addition, the contrast between the yellow and magenta hues is strengthened, which enhances the design potential, especially when printing woodgrain images. In order to suppress color unevenness including reddish hues and enhance design, carboxyl group-containing resin D M is preferably a polymer having a crosslinked structure.

[0126] Carboxy group-containing resin D relative to magenta pigment content M The mass ratio M of the content is preferably 0.20 to 0.80, and more preferably 0.25 to 0.70.

[0127] -Organic solvents, surfactants- The magenta ink may contain at least one organic solvent. The magenta ink may contain at least one surfactant. The preferred embodiments of the organic solvent and surfactant contained in the magenta ink are the same as the preferred embodiments of the organic solvent and surfactant contained in the yellow ink.

[0128] -Other ingredients- The magenta ink may contain other components in addition to those described above, as necessary. Other components contained in the magenta ink include the same as the other components contained in the yellow ink.

[0129] The method of applying the magenta ink by the inkjet recording method is the same as the method of applying the yellow ink by the inkjet recording method. Furthermore, after the magenta ink application step, a step of heating and drying the magenta ink applied onto the permeable substrate may be included. A preferred embodiment of the step of heating and drying the magenta ink is the same as a preferred embodiment of the step of heating and drying the yellow ink.

[0130] <Black ink application process> The inkjet recording method of the present disclosure includes a black ink application step. The black ink application step is a step of applying black ink by inkjet recording onto the area on the permeable substrate to which the pretreatment liquid has been applied. In this step, the black ink is applied together with the yellow ink onto the area on the permeable substrate to which the pretreatment liquid has been applied, thereby enhancing the contrast between the yellow hue and the black hue, and improving the design properties, particularly when recording a wood-grain image.

[0131] (black ink) The black ink is made of water, black pigment, and carboxyl group-containing resin D. K It is preferred that the compound contains:

[0132] -water- The water content is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more, based on the total amount of the black ink. The upper limit of the water content depends on the amounts of other components, and is, for example, 90% by mass or 80% by mass relative to the total amount of black ink.

[0133] -Black pigment- The black ink of the present disclosure preferably contains a black pigment. Examples of black pigments include carbon black, indazine pigments, and perylene pigments, and more specifically, CI Pigment Black 1, 7, 31, and 32.

[0134] The content of the black pigment is preferably 2.0% by mass to 8.0% by mass, and more preferably 3.0% by mass to 6.0% by mass, relative to the total amount of the black ink.

[0135] -Carboxy group-containing resin D K - Black ink is made of carboxyl group-containing resin D K It is preferred that the compound contains:

[0136] Carboxy group-containing resin D K is not particularly limited as long as it is a resin (polymer) containing a carboxy group. The form of the resin is not particularly limited, and may be any of a random polymer, a block polymer, and a graft polymer. K may be a polymer having a crosslinked structure or a polymer not having a crosslinked structure.

[0137] Carboxy group-containing resin D K A preferred embodiment of the carboxyl group-containing resin D Y This is the same as the preferred embodiment of the above.

[0138] Carboxy group-containing resin D K Preferably, the black pigment dispersant functions as a dispersant for dispersing the black pigment in the black ink.

[0139] Carboxy group-containing resin D K When the black ink is a polymer having a crosslinked structure, the black pigment particles tend to aggregate together when the black ink reacts with the aggregating agent contained in the pretreatment liquid, thereby improving the black density. By using yellow ink and black ink in combination, the contrast between the yellow hue and the black hue becomes stronger, and the design is enhanced, particularly when recording a woodgrain image. From the above viewpoint, carboxyl group-containing resin D K is preferably a polymer having a crosslinked structure.

[0140] Carboxy group-containing resin D relative to the content of black pigment K The mass ratio K of the content is preferably 0.20 to 0.80, and more preferably 0.25 to 0.70.

[0141] Mass ratio Y (the ratio of carboxyl group-containing resin D to the content of PY110)Y The mass ratio of the content of (I) is preferably smaller than the mass ratio K. When the mass ratio Y is smaller than the mass ratio K, color unevenness including reddish hues is suppressed when the yellow ink reacts with the aggregating agent contained in the pretreatment liquid. Furthermore, when the black ink reacts with the aggregating agent contained in the pretreatment liquid, the black pigments tend to aggregate, improving the black density. This enhances the contrast between the yellow and black hues, enhancing the design potential, particularly when printing woodgrain-like images.

[0142] -Organic solvents, surfactants- The black ink may contain at least one organic solvent. The black ink may contain at least one surfactant. The preferred embodiments of the organic solvent and surfactant contained in the black ink are the same as the preferred embodiments of the organic solvent and surfactant contained in the yellow ink.

[0143] -Other ingredients- The black ink may contain other components in addition to those described above, as necessary. Other components contained in the black ink include the same components as those contained in the yellow ink.

[0144] The method of applying black ink by inkjet recording is the same as the method of applying yellow ink by inkjet recording. Furthermore, after the black ink application step, a step of heating and drying the black ink applied to the permeable substrate may be included. A preferred embodiment of the step of heating and drying the black ink is the same as a preferred embodiment of the step of heating and drying the yellow ink.

[0145] An example of an inkjet recording apparatus used in the inkjet recording method of the present disclosure will be described below with reference to the drawings.

[0146] In the drawings and descriptions thereof in this disclosure, substantially identical elements (for example, parts or portions) are denoted by the same reference numerals, and redundant descriptions may be omitted.

[0147] FIG. 1 is a conceptual diagram of an inkjet recording apparatus, which is an example of an inkjet recording apparatus used in the inkjet recording method of the present disclosure.

[0148] The inkjet recording apparatus shown in FIG. 1 is an example of an inkjet recording apparatus equipped with a transport mechanism that transports a permeable substrate by a roll-to-roll method. In this apparatus, a long permeable substrate A1 that has been wound into a roll is unwound by an unwinding device W1, and the unwound permeable substrate A1 is transported in the direction of the block arrow, passing through a pretreatment liquid application device P1, an ink application device IJ1, and a drying zone D1 in that order, and finally being wound up by a winding device W2.

[0149] A pretreatment liquid application device P1 and an ink application device IJ1 are arranged in this order downstream (hereinafter simply referred to as the "downstream side") of the unwinding device W1 for unwinding the permeable substrate A1 in the transport direction of the permeable substrate A1. The pretreatment liquid applying device P1 and the ink applying device IJ1 perform a pretreatment liquid applying step and an ink applying step.

[0150] The details of the pretreatment liquid application step and the ink application step are as described above.

[0151] A zone (not shown) for drying the pretreatment liquid may be provided between the pretreatment liquid applying device P1 and the ink applying device IJ1.

[0152] The ink applying device IJ1 includes at least one inkjet head. The ink applicator IJ1 preferably includes an inkjet head for black (K) ink, an inkjet head for cyan (C) ink, an inkjet head for magenta (M) ink, and an inkjet head for yellow (Y) ink.

[0153] A drying zone D1 is disposed downstream of the ink applicator IJ1. In the drying zone D1, the ink drying process is carried out.

[0154] [Melanin decorative panel manufacturing method] The method for manufacturing the melamine decorative board of the present disclosure preferably includes a step of obtaining decorative paper having an image recorded thereon using the inkjet recording method of the present disclosure (hereinafter also referred to as the "decorative paper manufacturing step"), and a step of impregnating the decorative paper having the image recorded thereon with melamine resin (hereinafter also referred to as the "impregnation step").

[0155] <Decorative paper manufacturing process> Details of the decorative paper and the inkjet recording method are as described above. In the decorative paper manufacturing process, it is preferable to record a wood grain image on the decorative paper.

[0156] <Impregnation process> One method for impregnating decorative paper with melamine resin is to impregnate the decorative paper with methylol melamine and then heat it. Heating the methylol melamine causes a curing reaction to occur, resulting in the production of melamine resin. The decorative paper may be impregnated with a component other than the melamine resin.

[0157] When producing a low-pressure melamine decorative board, it is preferable to include a step of thermocompression molding the decorative paper impregnated with the melamine resin and a wood fiberboard after the impregnation step.

[0158] When producing a high-pressure melamine decorative board, it is preferable to include a step of laminating the decorative paper impregnated with melamine resin and the core paper impregnated with phenolic resin and molding them under heat and pressure after the impregnation step.

[0159] [Melamine decorative panel] The melamine decorative board of the present disclosure is produced by the method for producing a melamine decorative board of the present disclosure. By impregnating decorative paper with an image recorded using the inkjet recording method of the present disclosure with melamine resin, a melamine decorative board with a high yellow density can be obtained. In particular, by recording a wood grain image on the decorative paper, excellent design properties can be achieved. The melamine decorative board of the present disclosure is manufactured using decorative paper on which an image is recorded, which is obtained using the inkjet recording method of the present disclosure, and it is difficult to identify its specific structure or physical properties. [Example]

[0160] Examples of the present disclosure will be described below, but the present disclosure is not limited to the following examples.

[0161] The viscosity was measured at 25°C using a TV-22 viscometer manufactured by Toki Sangyo Co., Ltd. The surface tension was measured at 25°C using an automatic surface tensiometer (product name "CBVP-Z") manufactured by Kyowa Interface Science Co., Ltd. The pH was measured at 25°C using a pH meter manufactured by Toa DKK Co., Ltd. (model number "HM-31").

[0162] [Preparation of pretreatment solution] <Pretreatment liquid P1> -Synthesis of water-soluble polymer P1- According to the method described in

[0200] to

[0204] of JP 2013-001854 A, a 20% by mass aqueous solution of the water-soluble polymer P1 was obtained. The water-soluble polymer P1 was a random polymer containing structural units derived from methyl methacrylate, structural units derived from ethyl acrylate, and structural units derived from sodium acrylamido-2-methylpropanesulfonate in a mass ratio of 60:13:27. The weight average molecular weight Mw of the water-soluble polymer P1 was 45,000.

[0163] -Preparation of pretreatment solution P1- The following components were mixed to obtain a pretreatment liquid P1. Malonic acid (Fujifilm Wako Pure Chemical Industries, Ltd.)...5.6% by mass Malic acid (Fujifilm Wako Pure Chemical Industries, Ltd.)...3.8% by mass 85% by weight aqueous solution of phosphoric acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)...2.9% by weight of phosphoric acid DEGmBE: Diethylene glycol monobutyl ether (Fujifilm Wako Pure Chemical Industries, Ltd.)...6% by mass Water-soluble polymer P1: 0.4% by mass as the amount of water-soluble polymer Benzotriazole (Fujifilm Wako Pure Chemical Industries, Ltd.)...1% by mass Sodium dodecylbenzenesulfonate (Tokyo Chemical Industry Co., Ltd.)...0.4% by mass Antifoaming agent (product name "TSA-739", manufactured by Momentive Performance Materials, Inc., 15% by weight aqueous solution)...0.01% by weight of silicone oil Ion-exchanged water: The remaining amount that makes the total amount of pretreatment liquid 100% by mass

[0164] <Pretreatment liquids P2 to P7> Pretreatment solutions P2 to P7 were obtained in the same manner as pretreatment solution P1, except that the types and amounts of each component contained in pretreatment solution P1 were changed to those shown in Table 1.

[0165] [Table 1]

[0166] [Preparation of Yellow Ink] <Yellow pigment dispersion PY1> Carboxy group-containing resin D as a pigment dispersant YA mixture of 15 parts by mass of solids of Solsperse 43000 (manufactured by Lubrizol), 45 parts by mass of PY110 (manufactured by Sun Chemical), 75 parts by mass of water, and 18 parts by mass of propylene glycol was used. The mixture was dispersed using a bead mill (bead diameter 0.1 mmφ, zirconia beads) until the desired volume average particle size (130 nm or less) was achieved. The resulting dispersion was centrifuged at 6800 G for 20 minutes in a centrifuge to remove coarse particles. Ion-exchanged water and 0.3 parts by mass of a preservative (product name: Proxel GXL) were then added to obtain yellow pigment dispersion PY1. The pigment concentration of the yellow pigment dispersion PY1 was 15% by mass. Carboxy group-containing resin D relative to the content of PY110 Y The mass ratio Y of the content was 0.33. Solsperse 43000 is a polymer that does not have a crosslinked structure (acid value: 120 mg KOH / g, Mw: 21000). In Table 2, it is shown as "Uncrosslinked Polymer 1."

[0167] The mass ratio Y was measured and calculated by the following method. After 1.0 part by mass of the yellow pigment dispersion PY1 was dried at 180° C. under reduced pressure (0.1 MPa) for 6 hours, the mass of the dried product was 0.200 part by mass. The pigment concentration of the yellow pigment dispersion PY1 is 15% by mass, and therefore the mass of the pigment is 0.150 parts by mass. Carboxy group-containing resin D Y The mass of was calculated to be 0.050 parts by mass. Mass ratio Y=0.050÷0.150≒0.33

[0168] For yellow pigment dispersions PY2 to PY7 described below, the mass ratio Y was calculated in the same manner as for yellow pigment dispersion PY1. Mass ratios M and K were also calculated in the same manner as for mass ratio Y.

[0169] <Yellow pigment dispersion PY2> In the yellow pigment dispersion PY1, the pigment dispersant was a carboxyl group-containing resin DY A yellow pigment dispersion PY2 was obtained in the same manner as in the yellow pigment dispersion PY1, except that the pigment dispersion was changed to a new one (product name "Joncryl JDX-6180" manufactured by BASF). The pigment concentration of the yellow pigment dispersion PY2 was 15% by mass. Carboxy group-containing resin D relative to the content of PY110 Y The mass ratio Y of the content was 0.35. Joncryl JDX-6180 is a polymer that does not have a crosslinked structure (acid value: 230 mg KOH / g, Mw: 14000). In Table 2, it is shown as "uncrosslinked polymer 2."

[0170] <Yellow pigment dispersion PY3> -Synthesis of water-soluble polymer Q1- A monomer feed composition was prepared by combining 215 parts by weight of methacrylic acid, 785 parts by weight of benzyl methacrylate, and 375 parts by weight of isopropanol. An initiator feed composition was prepared by combining 22.05 parts by weight of 2,2-azobis(2-methylbutyronitrile) and 187.5 parts by weight of isopropanol. Next, isopropanol (187.5 parts by mass) was heated to 80°C under a nitrogen atmosphere, and the mixture of the monomer supply composition and the initiator supply composition was added dropwise thereto over 2 hours. After the dropwise addition was completed, the resulting solution was maintained at 80°C for an additional 4 hours and then cooled to 25°C. After cooling, the reaction solution diluted with isopropanol and tetrahydrofuran was added dropwise to water at 10°C, and the precipitated solid was filtered and dried by a reprecipitation method to obtain water-soluble polymer Q1. The water-soluble polymer Q1 had a weight-average molecular weight of about 30,000 and an acid value of 140 mgKOH / g.

[0171] -Preparation of Yellow Pigment Dispersion PY3- 0.8 equivalents of methacrylic acid in water-soluble polymer Q1 (150 parts by mass) was neutralized with aqueous potassium hydroxide solution. Deionized water was further added to adjust the concentration of the water-soluble polymer to 20% by mass, yielding an aqueous solution of water-soluble polymer Q1. The aqueous solution of water-soluble polymer Q1 (80 parts by mass) was mixed with PY110 (manufactured by Sun Chemical Co., Ltd.) (48 parts by mass), water (75 parts by mass), and dipropylene glycol (30 parts by mass). The mixture was dispersed using a bead mill (bead diameter 0.1 mmφ, zirconia beads) until the target volume average particle size (130 nm or less) was achieved. Deionized water was added to obtain a dispersion (uncrosslinked dispersion) in which PY110 was dispersed by water-soluble polymer Q1. The concentration of PY110 in the uncrosslinked dispersion was 15% by mass.

[0172] To the uncrosslinked dispersion (136 parts by mass), a crosslinking agent, trimethylolpropane polyglycidyl ether (product name "Denacol EX-321", manufactured by Nagase ChemteX Corporation) (0.7 parts by mass) and an aqueous boric acid solution (boric acid concentration: 4% by mass) (7.2 parts by mass) were added, and the mixture was reacted at 50°C for 6.5 hours, and then cooled to 25°C, thereby crosslinking the water-soluble polymer Q1 with the crosslinking agent. This resulted in a dispersion containing PY110 and the crosslinked water-soluble polymer Q1 (crosslinked dispersion). Next, ion-exchanged water was added to the obtained crosslinked dispersion, and ultrafiltration was carried out using an ultrafilter (Sartorius, Sartocon Slice 200) and an ultrafiltration filter (Sartorius, Sartocon Slice Casse, molecular weight cutoff 100,000). The crosslinked dispersion was purified so that the dipropylene glycol concentration was 0.1% by mass or less, and then concentrated to a pigment concentration of 15% by mass. 0.3 parts by mass of a preservative (product name: Proxel GXL) was then added to obtain a yellow pigment dispersion PY3. Yellow pigment dispersion PY3 is made of carboxyl group-containing resin D Y The crosslinked water-soluble polymer Q1 (hereinafter also referred to as "crosslinked polymer 1") is included as the crosslinked water-soluble polymer Q1. The pigment concentration of the yellow pigment dispersion PY3 was 15% by mass. Carboxy group-containing resin D relative to the content of PY110 Y The mass ratio Y of the content was 0.34.

[0173] <Yellow pigment dispersion PY4> In yellow pigment dispersion PY1, carboxyl group-containing resin D Y A yellow pigment dispersion PY4 was obtained in the same manner as in the yellow pigment dispersion PY1, except that the blending amount of was changed to 4.5 parts by mass in terms of solid content. The pigment concentration of the yellow pigment dispersion PY4 was 15% by mass. Carboxy group-containing resin D relative to the content of PY110 Y The mass ratio Y of the content was 0.11.

[0174] <Yellow pigment dispersion PY5> In yellow pigment dispersion PY1, carboxyl group-containing resin D Y A yellow pigment dispersion PY5 was obtained in the same manner as in the yellow pigment dispersion PY1, except that the blending amount of was changed to 30 parts by mass in terms of solid content. The pigment concentration of the yellow pigment dispersion PY5 was 15% by mass. Carboxy group-containing resin D relative to the content of PY110 Y The mass ratio Y of the content was 0.65.

[0175] <Yellow pigment dispersion PY6> In yellow pigment dispersion PY1, carboxyl group-containing resin D Y A yellow pigment dispersion PY6 was obtained in the same manner as in the yellow pigment dispersion PY1, except that the blending amount of was changed to 45 parts by mass in terms of solid content. The pigment concentration of the yellow pigment dispersion PY6 was 15% by mass. Carboxy group-containing resin D relative to the content of PY110 Y The mass ratio Y of the content was 0.99.

[0176] <Yellow pigment dispersion PY7> Yellow pigment dispersion PY7 was obtained in the same manner as for yellow pigment dispersion PY1, except that the mixed liquid was dispersed using a bead mill (bead diameter 0.1 mmφ, zirconia beads) until the desired volume average particle size (190 nm or less) was achieved. The pigment concentration of the yellow pigment dispersion PY7 was 15% by mass. Carboxy group-containing resin D relative to the content of PY110 Y The mass ratio Y of the content was 0.34.

[0177] <Yellow ink Y1> The following components were mixed to obtain a mixed liquid: Next, coarse particles were removed from the mixed liquid using a 1 μm filter to obtain yellow ink Y1. Yellow pigment dispersion PY1 (aqueous dispersion with a pigment concentration of 15% by mass)...Amount that results in a pigment content of 3.9% by mass in yellow ink Organic solvent: Glycerin, manufactured by Fujifilm Wako Pure Chemical Industries, boiling point 290°C...23.0% by mass Organic solvent: PG (propylene glycol), manufactured by ADEKA Corporation, boiling point 188°C...15.0% by mass Surfactant: Acetylene compound 1 (product name "Surfynol 465", manufactured by Nissin Chemical Industry Co., Ltd.)...0.8% by mass Antifoaming agent (product name "BYK-024", manufactured by BYK)...0.01% by mass Colloidal silica (product name "ST-XS", manufactured by Nissan Chemical Industries, Ltd.)...0.05% by mass as solid content Water: The remaining amount of yellow ink that makes up 100% by mass

[0178] <Yellow ink Y2~Y15> Yellow inks Y2 to Y15 were obtained in the same manner as for yellow ink Y1, except that the types and contents of the components contained in yellow ink Y1 were changed to those shown in Table 2.

[0179] The details of the ingredients listed in Table 2 are as follows: Organic solvent: TEGmBE (triethylene glycol monobutyl ether), manufactured by Fujifilm Wako Pure Chemical Industries, boiling point 276°C Surfactant: Acetylene compound 2 (product name "Dynol 604", manufactured by Nissin Chemical Industry Co., Ltd.) Surfactant: Polyoxyethylene lauryl ether (product name: Emulgen 120, manufactured by Kao Corporation) Surfactant: Silicone compound (product name "BYK-347", manufactured by BYK)

[0180] [Table 2]

[0181] [Preparation of magenta ink] <Magenta pigment dispersion PM1> The above-mentioned aqueous solution of water-soluble polymer Q1 (80 parts by mass), PR254 (product name "Irgazin Red L3630", manufactured by Sun Chemical Co., Ltd.) (40 parts by mass), water (75 parts by mass), and dipropylene glycol (30 parts by mass) were mixed. The mixture was dispersed using a bead mill (bead diameter 0.1 mmφ, zirconia beads) until the target volume average particle size (130 nm or less) was achieved. Ion-exchange water was added to obtain a dispersion in which PR254 was dispersed by the water-soluble polymer Q1 (uncrosslinked dispersion). The concentration of PR254 in the uncrosslinked dispersion was 16% by mass. The uncrosslinked dispersion was subjected to a crosslinking treatment in the same manner as in the yellow pigment dispersion PY3, to obtain a magenta pigment dispersion PM1. Magenta pigment dispersion PM1 is a carboxyl group-containing resin D M As such, it includes crosslinked polymer 1. The pigment concentration of the magenta pigment dispersion PM1 was 16% by mass. Carboxy group-containing resin D relative to PR254 content M The mass ratio M of the content was 0.41.

[0182] <Magenta pigment dispersion PM2> Magenta pigment dispersion PM2 was obtained in the same manner as for magenta pigment dispersion PM1, except that PR254 in magenta pigment dispersion PM1 was changed to CI Pigment Red 122 (product name "Chromofine Red", manufactured by Dainichi Seikagaku Co., Ltd., PR122). The pigment concentration of the magenta pigment dispersion PM2 was 16% by mass. Carboxy group-containing resin D relative to the content of PR122 M The mass ratio M of the content was 0.39.

[0183] <Magenta pigment dispersion PM3> A magenta pigment dispersion PM3 was obtained in the same manner as in the magenta pigment dispersion PM1, except that PR254 in the magenta pigment dispersion PM1 was changed to CI Pigment Violet (product name "Inkjet Magenta E5B02", manufactured by Clariant, PV19). The pigment concentration of the magenta pigment dispersion PM3 was 16% by mass. Carboxy group-containing resin D relative to the content of PV19 M The mass ratio M of the content was 0.40.

[0184] <Magenta ink M1> The following components were mixed to obtain a mixed liquid: Next, coarse particles were removed from the mixed liquid using a 1 μm filter to obtain magenta ink M1. Magenta pigment dispersion PM1 (aqueous dispersion with a pigment concentration of 16% by mass)...the amount of pigment in the magenta ink that results in a pigment content of 4% by mass Organic solvent: Glycerin (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), boiling point 290°C...20.0% by mass Organic solvent: PG (propylene glycol), manufactured by ADEKA Corporation, boiling point 188°C...15.0% by mass Surfactant: acetylene compound (product name "Surfynol 465", manufactured by Nissin Chemical Industry Co., Ltd.)...0.9% by mass Antifoaming agent (product name "BYK-024", manufactured by BYK)...0.01% by mass Colloidal silica (product name "ST-XS", manufactured by Nissan Chemical Industries, Ltd.)...0.05% by mass as solid content Water: The remaining amount that makes the total amount of magenta ink 100% by mass

[0185] <Magenta ink M2~M3> Magenta inks M2 to M3 were obtained in the same manner as magenta ink M1, except that the types and contents of each component contained in magenta ink M1 were changed to those shown in Table 3.

[0186] [Preparation of black ink] <Black pigment dispersion PK1> The above-mentioned aqueous solution of water-soluble polymer Q1 (80 parts by mass), PI pigment black 7 (product name "Carbon Black NIPEX160-IQ", manufactured by Orion Engineered Carbons, PB7) (40 parts by mass), water (75 parts by mass), and dipropylene glycol (30 parts by mass) were mixed. The mixture was dispersed using a beads mill (bead diameter 0.1 mmφ, zirconia beads) until the target volume average particle size (130 nm or less) was achieved. Ion-exchanged water was added to obtain a dispersion in which PB7 was dispersed by the water-soluble polymer Q1 (uncrosslinked dispersion). The concentration of PB7 in the uncrosslinked dispersion was 14% by mass. The uncrosslinked dispersion was subjected to a crosslinking treatment in the same manner as in the yellow pigment dispersion PY3, to obtain black pigment dispersion PK1. Black pigment dispersion PK1 is a carboxyl group-containing resin D K As such, it includes crosslinked polymer 1. The pigment concentration of the black pigment dispersion PK1 was 14% by mass. Carboxy group-containing resin D relative to the content of PB7 K The mass ratio K of the content was 0.41.

[0187] <Black pigment dispersion PK2> Black pigment dispersion PK2 was obtained in the same manner as for yellow pigment dispersion PY1, except that the blending amount of PB7 in black pigment dispersion PK1 was changed to 48 parts by mass. The pigment concentration of the black pigment dispersion PK2 was 14% by mass. Carboxy group-containing resin D relative to the content of PB7 K The mass ratio K of the content was 0.33.

[0188] <Black pigment dispersion PK3> Black pigment dispersion PK3 was obtained in the same manner as for yellow pigment dispersion PY1, except that the blending amount of PB7 in black pigment dispersion PK1 was changed to 70 parts by mass. The pigment concentration of the black pigment dispersion PK3 was 14% by mass. Carboxy group-containing resin D relative to the content of PB7 K The mass ratio K of the content was 0.21.

[0189] <Black Ink K1> The following components were mixed to obtain a mixed liquid: Next, coarse particles were removed from the mixed liquid using a 1 μm filter to obtain black ink K1. Black pigment dispersion PK1 (aqueous dispersion with a pigment concentration of 14% by mass)...Amount that results in a pigment content of 4.4% by mass in black ink Organic solvent: Glycerin (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), boiling point 290°C...18.0% by mass Organic solvent: PG (propylene glycol), manufactured by ADEKA Corporation, boiling point 188°C...15.0% by mass Surfactant: Acetylene compound 1 (product name "Surfynol 465", manufactured by Nissin Chemical Industry Co., Ltd.)...1.0% by mass Antifoaming agent (product name "BYK-024", manufactured by BYK)...0.01% by mass Colloidal silica (product name "ST-XS", manufactured by Nissan Chemical Industries, Ltd.)...0.05% by mass as solid content Water: The remaining amount of black ink that makes up 100% by mass

[0190] <Black ink K2~K3> Black inks K2 to K3 were obtained in the same manner as black ink K1, except that the types and contents of the components contained in black ink K1 were changed to those shown in Table 3.

[0191] [Preparation of cyan ink] <Cyan pigment dispersion PC1> The above water-soluble polymer Q1 aqueous solution (80 parts by mass), CI Pigment Blue 15:3 (product name "TRB2", Dainichiseika Color & Chemicals Co., Ltd., PB15:3) (50 parts by mass), water (75 parts by mass), and dipropylene glycol (30 parts by mass) were mixed. The mixture was dispersed using a bead mill (bead diameter 0.1 mm, zirconia beads) until the desired volume average particle size (130 nm or less) was achieved. Ion-exchange water was added to obtain a dispersion in which PB15:3 was dispersed by the water-soluble polymer Q1 (uncrosslinked dispersion). The concentration of PB15:3 in the uncrosslinked dispersion was 14% by mass. The uncrosslinked dispersion was subjected to a crosslinking treatment in the same manner as in the yellow pigment dispersion PY3, to obtain a cyan pigment dispersion PC1. Cyan pigment dispersion PC1 is made of carboxyl group-containing resin D C As such, it includes crosslinked polymer 1. The pigment concentration of the cyan pigment dispersion PC1 was 14% by mass. Carboxy group-containing resin D relative to the content of PB15:3 C The mass ratio C of the content was 0.32.

[0192] <Cyan ink C1> The following components were mixed to obtain a mixed liquid: Next, coarse particles were removed from the mixed liquid using a 1 μm filter to obtain black ink K1. Cyan pigment dispersion PC1 (aqueous dispersion with a pigment concentration of 14% by mass)...Amount that results in a pigment content of 3% by mass in cyan ink Organic solvent: Glycerin (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), boiling point 290°C...22.0% by mass Organic solvent: PG (propylene glycol), manufactured by ADEKA Corporation, boiling point 188°C...15.0% by mass Surfactant: Acetylene compound 1 (product name "Surfynol 465", manufactured by Nissin Chemical Industry Co., Ltd.)...0.8% by mass Antifoaming agent (product name "BYK-024", manufactured by BYK)...0.01% by mass Colloidal silica (product name "ST-XS", manufactured by Nissan Chemical Industries, Ltd.)...0.05% by mass as solid content Water: The remaining amount that makes the total amount of cyan ink 100% by mass

[0193] [Table 3]

[0194] [Examples 1 to 24, Comparative Examples 1 and 2] An inkjet recording apparatus having the same configuration as the inkjet recording apparatus shown in Figure 1 was prepared. Using the pretreatment liquid, yellow ink, magenta ink, and black ink shown in Table 4, a recorded image was obtained.

[0195] [Table 4]

[0196] <Pretreatment liquid application step> The entire surface of the substrate is coated with an anilox roller (100-300 lines / inch) and the coating amount is controlled by a roll coater, and the coating amount is 1.8 g / m 2 The pretreatment liquid was applied so that

[0197] <Pretreatment liquid drying process> Next, the substrate coated with the pretreatment liquid was subjected to a drying treatment under the following conditions by heating the back side of the substrate (the side opposite to the surface of the substrate on which an image was to be recorded) with a contact-type flat heater while blowing air with a drying fan. ·Drying method: Ventilation drying ·Wind speed: 10m / s Heating temperature: The temperature at which the surface temperature of the substrate on which the image is to be recorded reaches 50°C.

[0198] <Ink application process> The inkjet recording line head "Samba PH G3L HF (RJC Gen2)" (manufactured by Fujifilm Dimatix) was used as each inkjet head in the inkjet recording device. The prepared black ink, cyan ink, magenta ink, and yellow ink were filled into the first, second, third, and fourth inkjet heads, respectively, and the positions of the heads were adjusted so that the ink droplets ejected from each inkjet head overlapped. Thereafter, each ink was ejected onto the substrate to which the pretreatment liquid had been applied by inkjet recording under the following conditions to record an image, thereby obtaining an image recorded matter. The ink was dried while the substrate to which the ink had been applied was transported. The detailed conditions for inkjet recording are as follows.

[0199] Base material: Product name "MPK7299", manufactured by Felix Scherrer (Air resistance measured by the Gurley tester: 12 seconds) Substrate transport mechanism: Roll to roll Inkjet head temperature: 30℃ Inkjet head resolution: 1200 dpi (dots per inch) x 1200 dpi ·Discharge droplet volume: 3.0pL Conveying speed: 50m / min Heating method: Heating roller

[0200] <Ink drying process> The substrate was then transported to a drying area, where the substrate to which the ink had been applied was heated from the rear side of the substrate by a contact-type flat heater while air was blown onto it by a drying fan, and dried under the following conditions.

[0201] ·Drying method: Ventilation drying ·Wind speed: 15m / s Temperature: The temperature at which the surface temperature of the substrate on which the image is to be recorded reaches 80°C.

[0202] [evaluation] <Yellow Density> In the inkjet recording method described above, a yellow solid image was recorded at a duty of 100% to obtain an image recording. The yellow density of the solid image portion of the obtained image recording was measured using a spectrophotometer (product name "FD-7", manufactured by Konica Minolta, Inc.). The evaluation criteria were as follows: Rank 2 or higher is within the practically acceptable range. 4: Yellow density is greater than 0.55. 3: Yellow density is greater than 0.50 and equal to or less than 0.55. 2: Yellow density is greater than 0.45 and equal to or less than 0.50. 1: Yellow density is 0.45 or less.

[0203] <Dischargeability> Using yellow ink, a nozzle check pattern, a solid image at 100% duty, was continuously recorded over a 2000m length of the substrate. The final 10m of the image-recorded area was cut, and the number of missing nozzles in the nozzle check pattern was visually observed. The evaluation criteria were as follows: 3: The number of missing nozzles was 0 to 1. 2: The number of missing nozzles was 2 to 5. 1: The number of missing nozzles was 6 or more.

[0204] <Evaluation of reddish unevenness 1 (yellow image)> Using the pretreatment liquid and yellow ink, a 10-level yellow gradation image was recorded with a duty of 10% to 100%. The image recorded was visually observed. The evaluation criteria were as follows: Rank 2 or higher is within the practically acceptable range. 4: No reddish irregularities were observed throughout the image and it was uniform. 3: In the duty range from 80% to 100%, slight reddish unevenness can be seen upon closer inspection. 2: Reddish unevenness was observed in the duty range from 40% to 100%. 1: Clear reddish unevenness was observed throughout the image.

[0205] <Evaluation of Reddish Unevenness 2 (Yellow + Magenta Image)> Using a pretreatment liquid, magenta ink, and yellow ink, magenta ink was layered from 3% to 30% duty, and yellow ink was layered from 10% to 100% duty, to record a 10-level gradation image. The resulting image was visually observed. The evaluation criteria were as follows: Rank 2 or higher is within the practically acceptable range. 4: No reddish irregularities were observed throughout the image and it was uniform. 3: In the yellow image, in the duty range from 80% to 100%, slight reddish unevenness can be seen upon closer inspection. 2: Reddish unevenness was observed in the yellow image duty range from 40% to 100%. 1: Clear reddish unevenness was observed throughout the image.

[0206] <Contrast (black density in yellow hue)> A solid image was recorded using the pretreatment liquid, black ink, and yellow ink, with black ink applied at a duty of 100% and then yellow ink applied at a duty of 30%. The visual density (V density) of the image recorded was measured using a spectrophotometer (product name "FD-7", manufactured by Konica Minolta). The evaluation criteria were as follows: Rank 2 or higher is within the practically acceptable range. 4: Visual density is greater than 1.10. 3: Visual density is greater than 0.90 and less than or equal to 1.10. 2: Visual density is greater than 0.70 and less than or equal to 0.90. 1: Visual density is 0.70 or less.

[0207] Table 5 shows details of the pretreatment liquid, yellow ink, magenta ink, and black ink, as well as the evaluation results. In Table 5, "mass ratio Y" is the ratio of carboxyl group-containing resin D to the content of PY110. Y "Mass ratio K" means the mass ratio of the carboxyl group-containing resin D to the black pigment content. K"Surface tension difference" refers to the absolute value of the difference between the surface tension of the yellow ink and the surface tension of the pretreatment liquid. "High boiling point solvent" refers to an organic solvent with a boiling point of 250°C or higher.

[0208] [Table 5]

[0209] As shown in Table 5, Examples 1 to 24 included a pretreatment liquid application step and a yellow ink application step, and the content of the organic solvent having a boiling point of 250°C or higher was 15% by mass to 40% by mass relative to the total amount of the yellow ink, and therefore the yellow density of the image was high and the ejection properties were excellent. On the other hand, in Comparative Example 1, the pretreatment liquid application step was not carried out, and the yellow density of the image was extremely low. In Comparative Example 2, the content of organic solvents having a boiling point of 250° C. or higher was less than 15% by mass, and it was found that the ejection properties were poor.

[0210] In Example 1, the amount of the flocculant applied to the permeable substrate was 0.08 g / m 2 As a result, it was found that the yellow density was higher than in Example 3. In Example 1, the amount of flocculant applied to the permeable substrate was 0.35 g / m 2 It was found that the reddish unevenness was suppressed compared with Example 6.

[0211] In Example 1, the ratio of the carboxyl group-containing resin D to the content of PY110 was Y The mass ratio Y of the content of was 0.25 or more, and it was found that, compared with Example 10, the yellow density was high and the ejection properties were excellent. In Example 1, the ratio of the carboxyl group-containing resin D to the content of PY110 was Y It was found that the mass ratio Y of the content was 0.80 or less, and reddish unevenness was suppressed compared to Example 12.

[0212] Examples 1, 13, and 14 contain an acetylene compound and at least one surfactant selected from polyoxyalkylene alkyl ethers, and it was found that reddish unevenness was suppressed compared to Example 15.

[0213] In Example 1, the average particle size of PY110 was 160 nm or less, and it was found that compared to Example 19, the yellow density was high, the ejection properties were excellent, and reddish unevenness was suppressed.

[0214] In Example 1, the absolute value of the difference between the surface tension of the yellow ink and the surface tension of the pretreatment liquid was 10 mN / m or less, and it was found that reddish unevenness was suppressed compared to Example 18.

[0215] In Example 1, water, PR254, and carboxyl group-containing resin D M It was found that, compared with Examples 21 and 22, reddish unevenness was suppressed.

[0216] In Example 1, the ratio of the carboxyl group-containing resin D to the content of PY110 was Y The mass ratio Y of the content of the carboxyl group-containing resin D to the content of the black pigment is K It was found that the mass ratio K of the content was smaller than that of Example 24, and the contrast was superior to that of Example 24.

[0217] In Example 1, carboxyl group-containing resin D Y is a polymer that does not have a crosslinked structure, and therefore, compared with Example 9, it was found that reddish unevenness was suppressed.

[0218] A decorative board was manufactured using the pretreatment liquid, yellow ink, magenta ink, and black ink described in Example 1, and cyan ink C1. Specifically, a woodgrain pattern image was recorded on decorative paper using the same method as the pretreatment liquid application process and ink application process. The decorative paper with the recorded image was impregnated with methylol melamine and dried. The decorative paper impregnated with melamine resin and a phenolic resin-impregnated core paper were laminated together, and the laminate was heated at 150°C and 100 kg / cm. 2 The laminate was heated and compressed for 10 minutes to obtain a decorative board. [Explanation of symbols]

[0219] A1 Permeable substrate W1 Unwinding device P1 Pre-treatment liquid application device IJ1 ink dispenser D1 Dry Zone W2 Winding device

Claims

1. a step of applying a pretreatment liquid containing water and at least one flocculant selected from the group consisting of organic acids having a molecular weight of less than 1,000 and polyvalent metal salts to a permeable substrate having an air resistance of 5 to 50 seconds as measured by a Gurley tester; applying a yellow ink by an inkjet recording method to the region of the permeable substrate to which the pretreatment liquid has been applied, The yellow ink contains water, an organic solvent having a boiling point of 250° C. or higher, C.I. Pigment Yellow 110, and a carboxyl group-containing resin D. Ｙ and, an inkjet recording method, wherein the content of the organic solvent having a boiling point of 250° C. or higher is 15% by mass to 40% by mass relative to the total amount of the yellow ink;

2. The amount of the flocculant applied to the permeable substrate is 0.08 g / m ２ ~0.35g / m ２ The ink jet recording method according to claim 1, wherein

3. The ratio of the carboxy group-containing resin D to the content of C.I. Pigment Yellow 110 in the yellow ink Ｙ 3. The inkjet recording method according to claim 1, wherein the mass ratio Y of the content of

4. 3. The inkjet recording method according to claim 1, wherein the yellow ink contains at least one surfactant selected from the group consisting of an acetylene compound and a polyoxyalkylene alkyl ether.

5. 3. The inkjet recording method according to claim 1, wherein the average particle size of the C. I. Pigment Yellow 110 in the yellow ink is 100 nm to 160 nm.

6. 3. The inkjet recording method according to claim 1, wherein an absolute value of a difference between the surface tension of the yellow ink and the surface tension of the pretreatment liquid is 10 mN / m or less.

7. On the region of the permeable substrate to which the pretreatment liquid was applied, a mixture of water, C.I. Pigment Red 254, and a carboxyl group-containing resin D was applied by an inkjet recording method. Ｍ The inkjet recording method according to claim 1 or claim 2, further comprising a step of applying a magenta ink containing:

8. Water, a black pigment, and a carboxyl group-containing resin D are applied by an inkjet recording method onto the region of the permeable substrate to which the pretreatment liquid has been applied. Ｋ The method further comprises applying a black ink comprising: The ratio of the carboxy group-containing resin D to the content of C.I. Pigment Yellow 110 in the yellow ink Ｙ The mass ratio Y of the content of the carboxyl group-containing resin D to the content of the black pigment in the black ink is Ｋ The ink jet recording method according to claim 1 or 2, wherein the mass ratio K of the content of

9. Carboxy group-containing resin D Ｙ The inkjet recording method according to claim 1 or 2, wherein the polymer is a polymer having no crosslinked structure.

10. Carboxy group-containing resin D Ｍ The ink jet recording method according to claim 7, wherein is a polymer having a crosslinked structure.

11. Carboxy group-containing resin D Ｋ The ink jet recording method according to claim 8, wherein is a polymer having a crosslinked structure.

12. 3. The inkjet recording method according to claim 1, wherein the permeable substrate is decorative paper for decorative panels.

13. a step of obtaining decorative paper having an image recorded thereon by using the inkjet recording method according to claim 12; and impregnating the decorative paper on which the image is recorded with melamine resin.

14. A melamine decorative board manufactured by the method for manufacturing a melamine decorative board according to claim 13.

Images