Ink jet recording method, method for manufacturing melamine decorative sheet, and melamine decorative sheet

Abstract

The invention provides an ink jet recording method which has high yellow color density of an image and excellent ink ejection performance. The ink jet recording method includes: a step of applying a pretreatment liquid containing water and at least one coagulant 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 permeability resistance of 5-50 seconds according to a Gurley air permeability test method; and a step of applying a yellow ink by an ink jet recording method to the region to which the pretreatment liquid is applied on the permeable substrate, the yellow ink containing water, an organic solvent having a boiling point of 250 DEG C or more, C.I. Pigment yellow 110, and a carboxyl group-containing resin DY, the content of the organic solvent having a boiling point of 250 DEG C or more being 15-40 mass% with respect to the total amount of the yellow ink.

Description

Technical Field

[0001] The present invention relates to an inkjet recording method, a method for manufacturing a melamine decorative board, and the melamine decorative board. Background Art

[0002] Conventionally, various studies have been conducted on image recording using ink jet recording.

[0003] For example, Patent Document 1 describes an ink set for decorative panels, which includes cyan ink, magenta ink, and yellow ink, and is ejected by an inkjet method. In the ink set, each ink composition contains a pigment, and the pigment content C contained in the cyan ink is less than the pigment content M contained in the magenta ink or the pigment content Y contained in the yellow ink.

[0004] Patent Document 2 describes an inkjet recording method comprising the steps of inkjet printing a color pattern on a paper substrate including an ink-receiving layer, and impregnating the paper substrate with a thermosetting resin.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2022-001621

[0008] Patent Document 2: U.S. Patent No. 2016 / 0214395 Summary of the Invention

[0009] Problems to be solved by the invention

[0010] CI Pigment Yellow 110 (PY110) is sometimes used as a yellow pigment. Using PY110 can result in a low yellow density in the resulting image. This is particularly true for permeable substrates such as decorative paper and premium paper, where the ink seeps into the substrate, reducing the yellow density. This can also reduce ink jetting performance when attempting to increase the yellow density of the image.

[0011] An object of one embodiment of the present invention is to provide an inkjet recording method in which the yellow density of an image is high and the ink ejection properties are excellent.

[0012] Another embodiment of the present invention aims to provide a method for producing a melamine decorative board using the above-mentioned inkjet recording method, and a melamine decorative board.

[0013] Means for solving problems

[0014] The present invention includes the following aspects.

[0015] <1> An inkjet recording method comprising:

[0016] A step of applying a pretreatment solution containing at least one coagulant selected from the group consisting of an organic acid having a molecular weight of less than 1000 and a polyvalent metal salt and water to a permeable substrate having an air permeability resistance of 5 to 50 seconds based on the Gurley air permeability test method; and

[0017] A step of applying yellow ink to the area of ​​the permeable substrate to which the pretreatment liquid has been applied by inkjet recording,

[0018] The yellow ink contains water, an organic solvent with a boiling point of 250°C or higher, CI Pigment Yellow 110 and carboxyl resin D Y ,

[0019] The content of the organic solvent having a boiling point of 250° C. or higher is 15% by mass to 40% by mass based on the total amount of the yellow ink.

[0020] <2> The inkjet recording method according to <1>, wherein the amount of the coagulant applied to the permeable substrate is 0.08 g / m 2 ~0.35g / m 2 .

[0021] <3> The inkjet recording method according to <1> or <2>, wherein the yellow ink contains a carboxyl resin D Y The mass ratio Y of the content of CI Pigment Yellow 110 is 0.25 to 0.80.

[0022] <4> The inkjet recording method according to any one of <1> to <3>, wherein the yellow ink contains at least one surfactant selected from acetylene compounds and polyoxyalkylene alkyl ethers.

[0023] <5> The inkjet recording method according to any one of <1> to <4>, wherein the average particle size of CI Pigment Yellow 110 in the yellow ink is 100 nm to 160 nm.

[0024] <6> The inkjet recording method according to any one of <1> to <5>, 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.

[0025] <7> The inkjet recording method according to any one of <1> to <6>, further comprising: applying a coating containing water, CI Pigment Red 254 and carboxyl group-containing resin D to the area on the permeable substrate to which the pretreatment liquid is applied by inkjet recording. M The process of applying magenta ink.

[0026] <8> The inkjet recording method according to any one of <1> to <7>, further comprising: applying a coating comprising water, a black pigment and a carboxyl group-containing resin D to the area on the permeable substrate to which the pretreatment liquid is applied by inkjet recording. K The process of black ink, carboxyl resin D in yellow ink Y The mass ratio Y of the content of CI Pigment Yellow 110 is less than the carboxyl resin D in the black ink. K The mass ratio K of the content of the black pigment relative to the content of the black pigment.

[0027] <9> The inkjet recording method according to any one of <1> to <8>, wherein the carboxyl group-containing resin D Y It is a polymer without a cross-linked structure.

[0028] <10> The inkjet recording method according to <7>, wherein the carboxyl group-containing resin D M It is a polymer with a cross-linked structure.

[0029] <11> The inkjet recording method according to <8>, wherein the carboxyl group-containing resin D K It is a polymer with a cross-linked structure.

[0030] <12> The inkjet recording method according to any one of <1> to <11>, wherein the permeable substrate is decorative paper for a decorative board.

[0031] <13> A method for producing a melamine decorative board, comprising: obtaining decorative paper having an image recorded thereon using the inkjet recording method described in <12>; and impregnating the decorative paper having the image recorded thereon with a melamine resin.

[0032] <14> A melamine decorative board produced by the method for producing a melamine decorative board according to <13>.

[0033] Effects of the Invention

[0034] According to one embodiment of the present invention, there is provided an inkjet recording method in which an image has a high yellow density and excellent ink ejection properties.

[0035] According to another embodiment of the present invention, a method for manufacturing a melamine decorative board using the inkjet recording method and the melamine decorative board are provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a diagram conceptually showing an example of an inkjet recording apparatus used in the inkjet recording method of the present invention. DETAILED DESCRIPTION

[0037] In this specification, the numerical range expressed using "to" means a range including the numerical values ​​described before and after "to" as the minimum value and the maximum value, respectively.

[0038] In the numerical ranges described in this specification, the upper limit or lower limit described in a certain numerical range may be replaced by the upper limit or lower limit of another numerical range described in another stage. In addition, in the numerical ranges described in this specification, the upper limit or lower limit described in a certain numerical range may also be replaced by the values ​​shown in the Examples.

[0039] In this specification, when a plurality of substances corresponding to each component are present in a composition, the amount of each component in the composition refers to the total amount of the plurality of substances present in the composition, unless otherwise specified.

[0040] In this specification, a combination of two or more preferred aspects is a more preferred aspect.

[0041] In this specification, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes as long as the intended purpose of the process can be achieved.

[0042] In this specification, "image" refers to the entire film, and "image recording" refers to the formation of an image (ie, film). Furthermore, the concept of "image" in this specification also includes a solid image.

[0043] In this specification, “(meth)acrylate” is a concept including both acrylate and methacrylate, and “(meth)acrylic acid” is a concept including both acrylic acid and methacrylic acid.

[0044] [Inkjet Recording Method]

[0045] The inkjet recording method of the present invention includes the following steps: applying a pretreatment liquid containing a coagulant and water to a permeable substrate having an air permeability resistance of 5 to 50 seconds based on the Gurley air permeability test method, wherein the coagulant is at least one selected from the group consisting of organic acids with a molecular weight of less than 1000 and polyvalent metal salts (hereinafter referred to as the "pretreatment liquid applying step"); and applying a yellow ink by inkjet recording to the area on the permeable substrate to which the pretreatment liquid has been applied (hereinafter referred to as the "yellow ink applying step"). The yellow ink contains water, an organic solvent with 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 based on the total amount of the yellow ink.

[0046] The inkjet recording method of the present invention may include other steps as needed.

[0047] Generally, when yellow ink is applied to a permeable substrate, the yellow ink permeates into the permeable substrate, and the yellow concentration tends to decrease.

[0048] On the other hand, in the inkjet recording method of the present invention, by providing a pretreatment liquid application step before the yellow ink application step, the carboxyl group-containing resin D contained in the yellow ink is Y The coagulant contained in the pre-treatment liquid causes the PY 110 to aggregate, thereby suppressing its penetration into the permeable substrate. As a result, an image with a higher yellow density than before can be obtained.

[0049] Furthermore, in the inkjet recording method of the present invention, the content of the organic solvent having a boiling point of 250°C or higher is 15% to 40% by mass relative to the total amount of the yellow ink. This suppresses the formation of aggregates near the nozzle due to drying of the yellow ink, resulting in excellent ejection properties.

[0050] Patent Documents 1 and 2 do not describe focusing on the relationship between the step of applying a pretreatment liquid and the yellow concentration.

[0051] Hereinafter, each step of the inkjet recording method of the present invention will be described.

[0052] <Pretreatment liquid application step>

[0053] The inkjet recording method of the present invention includes a pre-treatment liquid application step.

[0054] The pretreatment liquid application step is a step of applying a pretreatment liquid containing a coagulant and water on a permeable substrate having an air permeability resistance of 5 seconds to 50 seconds based on the Gurley air permeability test method, wherein the coagulant is at least one selected from the group consisting of an organic acid with a molecular weight of less than 1000 and a polyvalent metal salt.

[0055] (Permeable substrate)

[0056] The substrate used in the inkjet recording method of the present invention is a permeable substrate having an air permeability resistance of 5 to 50 seconds based on the Gurley air permeability test method.

[0057] The inkjet recording method of the present invention includes a pre-treatment liquid application step when using a predetermined yellow ink. Therefore, even when using a permeable substrate, the yellow density of the image can be increased.

[0058] The air permeability resistance based on the Gurley air permeability test method is measured by the method described in JIS P8117:2009.

[0059] Examples of the permeable substrate include decorative paper, plain paper, premium paper, and recycled paper.

[0060] The permeable substrate preferably does not have an ink receiving layer on the surface.

[0061] Coated papers such as art paper and coated paper commonly available on the market do not belong to the above-mentioned permeable substrates.

[0062] The permeable substrate preferably comprises paper.

[0063] The permeable substrate comprising paper is commercially available.

[0064] Examples of commercially available products include:

[0065] High-quality paper (A) such as "OK PRINCE HIGH GRADE" manufactured by Oji Paper Co., Ltd., "SHIRAOI" manufactured by Nippon Paper Industries Co., Ltd., and "NEW NPI HIGH GRADE" manufactured by Nippon Paper Industries Co., Ltd.

[0066] Nippon Paper Industries Co., Ltd. manufactures form paper such as "NPi Form."

[0067] Furthermore, the permeable substrate is preferably decorative paper for decorative boards.

[0068] Examples of the decorative board include a high-pressure melamine decorative board, a low-pressure melamine decorative board, a polyester decorative board, and a DAP decorative board.

[0069] The decorative paper may be a commercially available product.

[0070] Examples of commercially available products include MPK3007, MPK7299, and MPK9653 manufactured by Felix Schoeller Group; and KCW-801P, KSH-801P, and KW-1001P manufactured by KJ Specialty Paper Co., Ltd.

[0071] According to the inkjet recording method of the present invention, it is possible to record a wood-grain image with a high yellow density.

[0072] (Pretreatment liquid)

[0073] The pretreatment liquid contains at least one coagulant selected from the group consisting of an organic acid having a molecular weight of less than 1000 and a polyvalent metal salt, and water.

[0074] -water-

[0075] The pretreatment liquid contains water.

[0076] The water content is preferably 60% by mass or more, more preferably 70% by mass or more, based on the total amount of the pretreatment liquid.

[0077] The upper limit of the water content also depends on the amounts of other components, but is preferably 90% by mass or less, more preferably 85% by mass or less, based on the total amount of the pretreatment liquid.

[0078] - Coagulant -

[0079] The pretreatment liquid of the present invention contains at least one coagulant selected from the group consisting of organic acids having a molecular weight of less than 1000 and polyvalent metal salts.

[0080] From the viewpoint of increasing the yellowness concentration, the coagulant preferably contains an organic acid having a molecular weight of less than 1,000.

[0081] The molecular weight of an organic acid is calculated based on the types and numbers of atoms constituting the compound.

[0082] Organic acids are organic compounds having acidic groups.

[0083] Examples of the acidic group include a phosphoric acid group, a phosphonic acid group, a phosphinic acid group, a sulfuric acid group, a sulfonic acid group, a sulfonic acid group, and a carboxyl group.

[0084] Among them, from the viewpoint of the aggregation speed of the ink, the acidic group is preferably a phosphoric acid group or a carboxyl group, and more preferably a carboxyl group.

[0085] It is preferred that at least a part of the acidic groups be dissociated in the pretreatment liquid.

[0086] Examples of the organic compound having a carboxyl 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.

[0087] Among these, from the viewpoint of the aggregation speed of the ink, the organic compound having a carboxyl group is preferably a divalent or higher-valent carboxylic acid (hereinafter also referred to as a polyvalent carboxylic acid), and more preferably a dicarboxylic acid.

[0088] 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.

[0089] The organic acid preferably has a low pKa (e.g., 1.0 to 5.0). This reduces the surface charge of particles such as pigments and resin particles in the ink, which are dispersed and stabilized by weakly acidic functional groups such as carboxyl groups, by contact with the organic acid with a lower pKa, thereby reducing dispersion stability.

[0090] The organic acid preferably has a low pKa, high solubility in water, and a valence of 2 or more. Furthermore, the organic acid more preferably has a high buffering capacity in a pH range lower than the pKa of the functional group (e.g., carboxyl group) that stabilizes particle dispersion in the ink.

[0091] Examples of polyvalent metal salts include salts of alkaline earth metals of Group 2 of the periodic table (e.g., magnesium and 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).

[0092] As the polyvalent metal salt, a calcium salt, a magnesium salt or an aluminum salt is preferred, and a calcium salt or a magnesium salt is more preferred.

[0093] It is preferred that at least a portion of the polyvalent metal salt is dissociated into polyvalent metal ions and counter ions in the pretreatment liquid.

[0094] The content of the coagulant in the pretreatment liquid is preferably 1.0 to 30% by mass, more preferably 3.0 to 25% by mass, and even more preferably 5.0 to 20% by mass, relative to the total amount of the pretreatment liquid.

[0095] -Organic solvents-

[0096] The pretreatment liquid may contain at least one organic solvent.

[0097] The type of organic solvent is not limited, and examples thereof include:

[0098] Monoalcohols with 1 to 4 carbon atoms;

[0099] 1,3-propylene glycol, 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, 4-methyl-1,2-pentanediol and other diols;

[0100] Triols such as glycerol, 1,2,6-hexanetriol, and trimethylolpropane;

[0101] Alkylene glycols such as ethylene glycol and propylene glycol;

[0102] Alkylene glycol monoalkyl ethers such as ethylene glycol monoalkyl ether and propylene glycol monoalkyl ether;

[0103] Polyalkylene glycols such as diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, dipropylene glycol, and polyoxyethylene polyoxypropylene glycol;

[0104] Polyalkylene glycol ethers such as diethylene glycol monoalkyl ether, triethylene glycol monoalkyl ether, tripropylene glycol monoalkyl ether, and polyoxypropylene glycerol ether;

[0105] 2-pyrrolidone, N-methyl-2-pyrrolidone;

[0106] wait.

[0107] The content of the organic solvent is preferably 1% by mass to 20% by mass, more preferably 3% by mass to 10% by mass, based on the total amount of the pretreatment liquid.

[0108] -Surfactants-

[0109] The pretreatment liquid may contain at least one surfactant.

[0110] The type of surfactant is not particularly limited and may be any of anionic surfactants, cationic surfactants, betaine-based surfactants and nonionic surfactants. Examples of surfactants include acrylic surfactants, fluorine-based surfactants and silicone-based surfactants.

[0111] Surfactants can function as defoaming agents.

[0112] The content of the surfactant is preferably 0.01% by mass to 6% by mass, more preferably 0.1% by mass to 4% by mass, based on the total amount of the pretreatment liquid.

[0113] -Other ingredients-

[0114] The pretreatment liquid may contain other components in addition to the above-mentioned components as needed.

[0115] Other components that may be contained in the pretreatment liquid include well-known additives such as solid wetting agents, colloidal silica, inorganic salts, anti-fading agents, emulsion stabilizers, penetration enhancers, ultraviolet absorbers, preservatives, mildew inhibitors, 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 Japanese Patent Gazette No. 2013-001854).

[0116] -Physical properties of pretreatment solution-

[0117] 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.

[0118] Here, pH refers to pH at 25°C.

[0119] The pH is measured at 25°C using, for example, a pH meter (for example, a pH meter manufactured by DKK-TOA CORPORATION (model "HM-31")).

[0120] The viscosity of the pretreatment liquid is preferably 0.5 to 20 mPa·s, more preferably 1 to 10 mPa·s. The viscosity is a value measured at 25°C using a viscometer. The viscosity is measured at 25°C using a viscometer, for example, a TV-22 viscometer manufactured by Toki Sangyo Co., Ltd.

[0121] 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 at 25°C using a surface tensiometer, for example, an automatic surface tensiometer manufactured by Kyowa Interface Science Co., Ltd. (product name "CBVP-Z") by a plate method.

[0122] (Applying a pretreatment solution)

[0123] 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.

[0124] Examples of the coating method include known coating methods using a bar coater, an extrusion die coater, an air knife coater, a blade coater, a rod coater, a knife coater, an extrusion coater, a reverse roll coater, and the like.

[0125] The amount of the pretreatment liquid applied is preferably 0.1 g / m 2 ~20g / m 2 , more preferably 0.5g / m 2 ~10g / m 2 , more preferably 1g / m 2 ~5g / m 2 .

[0126] The amount of the coagulant applied to the permeable substrate is preferably 0.08 g / m 2 ~0.35g / m 2 , more preferably 0.10 g / m 2 ~0.31g / m 2 , more preferably 0.12g / m 2 ~0.27g / m 2 .

[0127] The amount of coagulant added is per 1m2 Area mass (g / m 2 ).

[0128] The amount of coagulant applied can be adjusted according to the amount of pretreatment liquid applied (g / m 2 ) and the content (mass %) of the coagulant contained in the pretreatment liquid. The amount of coagulant applied can be adjusted by adjusting at least one of the amount of the pretreatment liquid applied and the content of the coagulant contained in the pretreatment liquid.

[0129] If the amount of coagulant added is 0.08g / m 2 Above, the coagulant and the carboxyl resin D contained in the yellow ink Y The reaction effectively allows PY110 to remain on the surface of the ink film, and effectively inhibits the penetration of PY110 into the permeable substrate, thereby improving the yellow density of the image.

[0130] Furthermore, if the amount of coagulant applied is 0.35 g / m 2 The action of the coagulant prevents excessive aggregation of PY 110, allowing it to be distributed uniformly in the in-plane direction of the ink film. Generally, if PY 110 aggregates and its concentration increases, the resulting image tends to have a reddish hue. By distributing PY 110 uniformly in the in-plane direction of the ink film, color unevenness, such as the presence of a reddish hue within the yellow hue of the image, can be suppressed.

[0131] (Heating and drying of pretreatment liquid)

[0132] The pretreatment liquid application process may include the steps of applying the pretreatment liquid to the permeable substrate and heating and drying the pretreatment liquid applied to the permeable substrate.

[0133] Examples of the mechanism for heating and drying the pretreatment liquid include a known heating mechanism such as a heater, a known air blowing mechanism such as a dryer, and a combination of these.

[0134] Examples of methods for heating and drying the pretreatment liquid include: a method of heating the permeable substrate from the side opposite to the side to which the pretreatment liquid is applied using a heater or the like; a method of blowing warm air or hot air onto the side of the permeable substrate to which the pretreatment liquid is applied; a method of heating the permeable substrate from the side to which the pretreatment liquid is applied or from the side opposite to the side to which the pretreatment liquid is applied using an infrared heater; and a method combining a plurality of these.

[0135] The heating temperature during heat drying of the pretreatment liquid is preferably 40° C. or higher, more preferably 45° C. or higher.

[0136] The upper limit of the heating temperature is not particularly limited, and is, for example, 150°C.

[0137] 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.

[0138] <Yellow ink application process>

[0139] The inkjet recording method of the present invention includes a yellow ink application step.

[0140] The yellow ink application step is a step of applying yellow ink to the area on the permeable substrate to which the pretreatment liquid has been applied by an inkjet recording method.

[0141] In this step, yellow ink is applied to the area on the permeable substrate to which the pretreatment liquid has been applied. Components in the yellow ink (eg, PY110) aggregate on the permeable substrate due to the action of the coagulant, thereby forming an image.

[0142] (Yellow ink)

[0143] The yellow ink contains water, an organic solvent with a boiling point of 250°C or above, PY110 and carboxyl resin D Y .

[0144] -water-

[0145] 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, relative to the total amount of the yellow ink.

[0146] The upper limit of the water content also depends on the amounts of other components. The upper limit of the water content relative to the total amount of the yellow ink is, for example, 90% by mass or 80% by mass.

[0147] -PY110-

[0148] Yellow ink contains PY110. PY110 has excellent light resistance.

[0149] The yellow ink may also contain yellow pigments other than PY110.

[0150] The ratio of PY110 in the yellow pigment is preferably 80% by mass or more, more preferably 90% by mass or more.

[0151] More preferably, the yellow pigment contained in the yellow ink of the present invention is only PY110.

[0152] 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.

[0153] When the average particle size is 100 nm or more, the light resistance is excellent.

[0154] When the average particle size is 160 nm or less, the yellow density increases.

[0155] Furthermore, when the yellow ink reacts with the coagulant contained in the pre-treatment liquid, localized aggregation of PY110 is suppressed. This results in less color unevenness, including reddish hues. Furthermore, coagulants are less likely to form inside the nozzle, resulting in excellent ejection performance.

[0156] The average particle size is a value measured by a particle size distribution analyzer (for example, Microtrac UPA (registered trademark) EX150 manufactured by Nikkiso Co., Ltd.).

[0157] The content of PY110 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, based on the total amount of the yellow ink.

[0158] -Carboxyl resin D Y -

[0159] The yellow ink of the present invention contains carboxyl resin D Y .

[0160] In the present invention, the resin refers to a compound having a weight average molecular weight (Mw) of 1,000 or more.

[0161] In the present invention, the weight average molecular weight (Mw) represents a value obtained by gel permeation chromatography (GPC). When measuring by gel permeation chromatography (GPC), HLC (registered trademark)-8020GPC (manufactured by Tosoh Corporation) is used as a measuring apparatus, three TSKgel (registered trademark) Super Multipore HZ-H (4.6 mm ID × 15 cm, manufactured by Tosoh Corporation) are used as columns, and THF (tetrahydrofuran) is used as an eluent. In addition, an RI detector is used for measurement, wherein the sample concentration is set to 0.45% by mass, the flow rate is set to 0.35 ml / min, the sample injection volume is set to 10 μl, and the measurement temperature is set to 40°C. The 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."

[0162] Carboxyl resin D YThere are no particular limitations on the resin (polymer) as long as it contains a carboxyl group.

[0163] 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 The polymer may have a cross-linked structure or may not have a cross-linked structure.

[0164] Carboxyl resin D Y Preferred are copolymers containing structural units derived from a carboxyl group-containing monomer (hereinafter referred to as "carboxyl group-containing monomer"). The structural units derived from the carboxyl group-containing monomer contained in the copolymer may be of one type or of two or more types.

[0165] Examples of the carboxyl group-containing monomer include (meth)acrylic acid, β-carboxyethyl acrylate, fumaric acid, itaconic acid, maleic acid, and crotonic acid.

[0166] From the viewpoint of dispersion stability, the carboxyl group-containing monomer is preferably (meth)acrylic acid or β-carboxyethyl acrylate, and more preferably (meth)acrylic acid.

[0167] The content of the structural unit derived from the carboxyl group-containing monomer relative to the carboxyl group-containing resin D Y The total amount 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.

[0168] Carboxyl resin D Y In addition to the structural unit derived from the carboxyl group-containing monomer, it is preferable to contain a structural unit derived from a monomer having a hydrophobic group (hereinafter referred to as "hydrophobic monomer"). Y The structural unit derived from the hydrophobic monomer contained therein may be only one kind or two or more kinds.

[0169] Examples of the hydrophobic monomer include (meth)acrylates having an alkyl group having 1 to 20 carbon atoms, (meth)acrylates having an aromatic ring (for example, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, etc.), styrene, and styrene derivatives.

[0170] From the viewpoint of dispersion stability, the carboxyl group-containing resin D Y The acid value is preferably 50 mgKOH / g to 250 mgKOH / g, more preferably 70 mgKOH / g to 240 mgKOH / g, and further preferably 90 mgKOH / g to 230 mgKOH / g.

[0171] In the present invention, the acid value is a value that can be measured by titration with an indicator and is measured by the method described in Japanese Industrial Standards (JIS K0070: 1992).

[0172] Carboxyl resin D Y The weight average molecular weight (Mw) is preferably 1,000 to 100,000, more preferably 5,000 to 80,000, and even more preferably 10,000 to 50,000.

[0173] Carboxyl resin D Y It preferably functions as a dispersant for dispersing PY110 in the yellow ink.

[0174] When carboxyl resin D Y In the case of a polymer without a cross-linked structure, when the yellow ink reacts with the coagulant contained in the pre-treatment liquid, PY110 will not excessively aggregate with each other, and color unevenness including reddish hues can be suppressed.

[0175] From the above viewpoints, the carboxyl group-containing resin D Y A polymer having no cross-linked structure is preferred.

[0176] Carboxyl resin D Y The mass ratio Y of the content of PY110 to the content of PY110 is preferably 0.25 to 0.80, more preferably 0.25 to 0.60.

[0177] If the mass ratio Y is 0.25 or more, PY110 passes through the carboxyl group-containing resin D Y The dispersion is appropriately dispersed and has excellent dispersion stability. As a result, agglomerates are less likely to form inside the nozzle, and the ejection properties are excellent.

[0178] When the mass ratio Y is 0.80 or less, when the yellow ink reacts with the aggregating agent contained in the pre-treatment liquid, the PY 110 will not excessively aggregate with each other, and color unevenness including reddish hue can be suppressed.

[0179] -Organic solvents-

[0180] The yellow ink contains an organic solvent (high-boiling-point solvent) having a boiling point of 250° C. or higher.

[0181] When a high-boiling-point solvent is contained, the ejection properties of the yellow ink are improved.

[0182] In the present invention, the boiling point refers to the boiling point at 1 atmosphere (101,325 Pa).

[0183] Examples of organic solvents having 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).

[0184] From the viewpoint of the ejectability of the yellow ink, the content of the high boiling point solvent is 15 to 40% by mass, more preferably 17 to 35% by mass, and even more preferably 20 to 30% by mass, relative to the total amount of the yellow ink.

[0185] The yellow ink may contain an organic solvent having a boiling point lower than 250° C. (low-boiling-point solvent).

[0186] Examples of the water-soluble organic solvent having a boiling point lower than 250°C include 1,2-propylene glycol (boiling point 188°C), 1,3-propylene glycol (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).

[0187] From the viewpoint of ejectability, 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.

[0188] From the viewpoint of ejectability, 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, more preferably 0.3 to 1.2.

[0189] -Surfactants-

[0190] The yellow ink preferably contains at least one surfactant.

[0191] The type of surfactant is not particularly limited, and may be any of anionic surfactants, cationic surfactants, betaine-based surfactants, and nonionic surfactants.

[0192] Examples of the surfactant include acrylic surfactants, fluorine-based surfactants, and silicone-based surfactants.

[0193] Among them, the yellow ink preferably contains at least one surfactant (hereinafter also referred to as "surfactant W") selected from acetylene compounds and polyoxyalkylene alkyl ethers.

[0194] If 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 coagulant contained in the pre-treatment liquid, thereby suppressing color unevenness including reddish hues.

[0195] Examples of the acetylene compound include acetylene diols 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 diols.

[0196] The acetylene compound can be synthesized by, for example, reacting acetylene with a ketone or aldehyde corresponding to the target acetylene diol.

[0197] The acetylene compound can be obtained by, for example, the method described in "New Surfactant Introduction" (authored by Takehiko Fujimoto, published by Sanyo Chemical Industries, Ltd. in 1992), pp. 94 to 107.

[0198] The acetylene compound may be a commercially available product.

[0199] Examples of commercially available acetylene compounds include Surfynol 104E (HLB value 4), Surfynol 104H (HLB value 4), Surfynol 104A (HLB value 4), Surfynol 104PA (HLB value 4), 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), and Surfynol DF110D (HLB value 3), Dynol 604 (HLB value 8), Dynol 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 AG), ACETYLENOL E00, ACETYLENOL E13T, ACETYLENOL E40, ACETYLENOL E60, ACETYLENOL E100, ACETYLENOL E200 (all manufactured by Kawaken Fine Chemicals Co., Ltd.), etc.

[0200] The polyoxyalkylene alkyl ether is preferably an ethylene oxide adduct of an alcohol or an adduct of ethylene oxide and propylene oxide of an alcohol, and more preferably an ethylene oxide adduct of an alcohol (ie, a polyoxyethylene alkyl ether compound).

[0201] As the polyoxyalkylene alkyl ether, a compound represented by the following formula (1) is more preferred.

[0202] R 1 O-[(EO) m / (PO) n ]-H…Formula (1)

[0203] 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.

[0204] In formula (1), m and n represent the average number of added moles, m is 2 to 100, n is 0 to 50, and the total of m and n is 2 to 120.

[0205] In formula (1), “(EO) m / (PO) n " indicates that the configuration of EO and PO can be a random copolymer configuration or a block copolymer configuration. In the description "(EO) m / (PO) n ", the addition order of EO and PO is irrelevant.

[0206] In formula (1), when n is 2 or greater, 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 having an oxyethylene group on the hydroxyl side, i.e., RO-(PO)(EO)-H.

[0207] Furthermore, when the compound represented by formula (1) is a block copolymer, it may be a triblock copolymer of RO-(EO)(PO)(EO)-H.

[0208] Examples of commercially available polyoxyalkylene alkyl ether compounds, such as ethylene oxide adducts of lauryl alcohol, include EMULGEN 102 (HLB: 6.3, average EO addition mole number: 2), EMULGEN 103 (HLB: 8.1, average EO addition mole number: 3), EMULGEN 103 (HLB: 9.7, average EO addition mole number: 4), EMULGEN 108 (HLB: 12.1, average EO addition mole number: 6), EMULGEN 109P (HLB: 13.6, average EO addition mole number: 8), EMULGEN 120 (HLB: 15.3, average EO addition mole number: 13), and EMULGEN 121 (HLB: 15.7, average EO addition mole number: 13), manufactured by Kao Corporation. Examples of the ethylene oxide adducts of secondary alcohols having 12 carbon atoms include Tergitol TMN-3 (HLB: 8.1, average number of EO added moles: 3), Triton HW-1000 (HLB: 10, average number of EO added moles: 6), Tergitol TMN-6 (HLB: 13.1, average number of EO added moles: 8), Tergitol TMN-100X (HLB: 14.0, average number of EO added moles: 9), and Tergitol TMN-10 (HLB: 14.4, average number of EO added moles: 10) manufactured by The Dow Chemical Company.

[0209] Commercially available polyoxyalkylene alkyl ether compounds include EMULGEN 707 (ethylene oxide adduct of a secondary alcohol having 11 to 15 carbon atoms, HLB: 12.1, average number of EO added moles: 6) and EMULGEN 220 (ethylene oxide adduct of a linear primary alcohol having 16 to 18 carbon atoms, HLB: 14.2, average number of EO added moles: 13) manufactured by Kao Corporation.

[0210] The content of the 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.

[0211] The yellow ink may contain a surfactant other than the surfactant W. From the viewpoint of suppressing color unevenness including reddish hues, the yellow ink preferably contains only the surfactant W as a surfactant.

[0212] -Other ingredients-

[0213] The yellow ink may contain other components in addition to the above-mentioned components as needed.

[0214] Other components that may be contained in the yellow ink include resin particles, water-soluble resins, colloidal silica, solid wetting agents, inorganic salts, anti-fading agents, emulsion stabilizers, penetration enhancers, ultraviolet absorbers, preservatives, mildew inhibitors, pH adjusters, viscosity adjusters, rust inhibitors, chelating agents and other well-known additives.

[0215] The yellow ink preferably 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 performance. Furthermore, "substantially no resin particles" means that the resin particle content is 0.5% by mass or less relative to the total amount of the yellow ink. More preferably, the resin particle content is 0.1% by mass or less.

[0216] -Physical properties of yellow ink-

[0217] 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.

[0218] The pH of the yellow ink was measured in the same manner as the pH of the pretreatment liquid.

[0219] The viscosity (30° C.) of the yellow ink 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.

[0220] The viscosity of the yellow ink was measured in the same manner as the viscosity of the pretreatment liquid.

[0221] 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.

[0222] The surface tension of the yellow ink was measured in the same manner as the surface tension of the pretreatment liquid.

[0223] The absolute value of the difference between the surface tension of the yellow ink and the surface tension of the pre-treatment liquid is preferably 10 mN / m or less, more preferably 5 mN / m or less.

[0224] 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.

[0225] When the value obtained by subtracting the surface tension of the pretreatment liquid from the surface tension of the yellow ink is 0 to 10 mN / m, PY110 can be uniformly present in the in-plane direction of the ink film, and color unevenness including reddish hue can be suppressed.

[0226] (Applying Yellow Ink by Inkjet Recording)

[0227] As the inkjet recording method, a known method can be applied.

[0228] As inkjet recording methods, for example, there are a charge control method that utilizes electrostatic induction force to eject ink, a drop-on-demand inkjet method (pressure pulse method) that utilizes the vibration pressure of a piezoelectric element, an acoustic inkjet method that converts an electrical signal into a sound beam and irradiates the ink to eject the ink using radiation pressure, and a thermal inkjet (Bubble Jet (registered trademark)) method that heats the ink to form bubbles and utilizes the generated pressure.

[0229] Examples of inkjet heads used in inkjet recording methods include a shuttle method that uses a short serial head to scan the head along the width direction of the recording medium and perform recording, and a line method that uses a line head with recording elements arranged in an entire area corresponding to one side of the recording medium.

[0230] In the inline method, patterns can be formed across the entire surface of the recording medium by scanning the recording medium in a direction intersecting the arrangement of the recording elements. This eliminates the need for a transport system such as a carriage that scans a short head. Furthermore, the inline method eliminates the need for carriage movement and complex scanning control of the recording medium, requiring only the recording medium to be moved. This allows for faster recording speeds compared to the shuttle method.

[0231] The ejection amount 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.

[0232] The amount of yellow ink applied is preferably 1 g / m 2 ~20g / m 2 , more preferably 2g / m 2 ~14g / m 2 , more preferably 3g / m 2 ~8g / m 2 .

[0233] The inkjet recording method of the present invention may include a step of heating and drying the yellow ink applied to the permeable substrate after the yellow ink application step.

[0234] Examples of the heating and drying mechanism include a known heating mechanism such as a heater, a known air blowing mechanism such as a dryer, and a combination of these.

[0235] Specifically, methods for heating the permeable substrate include: a method of heating the permeable substrate from the side opposite to the surface to which the yellow ink is applied using a heater, etc.; a method of blowing warm air or hot air toward the surface to which the yellow ink is applied; a method of heating the permeable substrate from the side to which the yellow ink is applied or from the side opposite to the surface using an infrared heater; and a method combining a plurality of these.

[0236] 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.

[0237] The upper limit of the heating temperature is not particularly limited, and is, for example, 150°C.

[0238] 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.

[0239] <Magenta ink application process>

[0240] The inkjet recording method of the present invention includes a magenta ink application step.

[0241] The magenta ink application step is a step of applying magenta ink to the area on the permeable substrate to which the pretreatment liquid has been applied by an inkjet recording method.

[0242] In this step, magenta ink is applied together with yellow ink to the area on the permeable substrate to which the pretreatment liquid is applied, thereby making color unevenness including reddish hue less visible based on PY110.

[0243] (Magenta ink)

[0244] The magenta ink preferably comprises water, magenta pigment and carboxyl-containing resin D M .

[0245] -water-

[0246] 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, relative to the total amount of the magenta ink.

[0247] The upper limit of the water content also depends on the amounts of other components. The upper limit of the water content relative to the total amount of the magenta ink is, for example, 90% by mass or 80% by mass.

[0248] -Magenta pigment-

[0249] The magenta ink of the present invention preferably contains a magenta pigment.

[0250] Examples of the magenta pigment include CI Pigment Red 122, 150, 171, 175, 177, 209, 224, 242, 254, 255, and 264, and CI Pigment Violet 19, 23, and 32.

[0251] Among them, the magenta pigment preferably includes CI Pigment Red 254 (PR254).

[0252] PR254 has a strong red tint. Therefore, by using a magenta ink containing PR254 in combination with a yellow ink, color unevenness including reddish hues based on PY110 becomes less visible.

[0253] The ratio of PR254 in the magenta pigment is preferably 80% by mass or more, more preferably 90% by mass or more.

[0254] The magenta pigment contained in the magenta ink of the present invention is more preferably only PR254.

[0255] 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.

[0256] -Carboxyl resin D M -

[0257] Magenta ink preferably contains carboxyl resin D M .

[0258] Carboxyl resin D M There are no particular limitations on the resin (polymer) as long as it contains a carboxyl group.

[0259] 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 The polymer may have a cross-linked structure or may not have a cross-linked structure.

[0260] Carboxyl resin D M The preferred embodiment and carboxyl resin D Y The preferred method is the same.

[0261] Carboxyl resin D M It preferably functions as a dispersant for dispersing the magenta pigment in the magenta ink.

[0262] In carboxyl resin D M In the case of a polymer having a cross-linked structure, when the magenta ink reacts with the aggregating agent contained in the pre-treatment liquid, the magenta pigments are easily aggregated, and the magenta concentration is increased.

[0263] By combining yellow and magenta inks, color unevenness including reddish hues becomes less noticeable with PY110. Furthermore, the contrast between the yellow and magenta hues is enhanced, improving design, particularly when recording wood-grain images.

[0264] From the viewpoint of suppressing color unevenness including reddish hues and improving design properties, the carboxyl group-containing resin D M A polymer having a cross-linked structure is preferred.

[0265] Carboxyl resin D M The mass ratio M of the content of the magenta pigment to the content of the magenta pigment is preferably 0.20 to 0.80, more preferably 0.25 to 0.70.

[0266] -Organic solvents, surfactants-

[0267] The magenta ink may contain at least one organic solvent.

[0268] The magenta ink may contain at least one surfactant.

[0269] Preferred aspects of the organic solvent and surfactant contained in the magenta ink are the same as those of the organic solvent and surfactant contained in the yellow ink.

[0270] -Other ingredients-

[0271] The magenta ink may contain other components in addition to the above-mentioned components as needed.

[0272] Examples of other components contained in the magenta ink include the same components as those contained in the yellow ink.

[0273] 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.

[0274] Furthermore, the method may include a step of heating and drying the magenta ink applied to the permeable substrate after the magenta ink application step.

[0275] A preferred embodiment of the process of heat-drying the magenta ink is the same as that of the process of heat-drying the yellow ink.

[0276] <Black ink application process>

[0277] The inkjet recording method of the present invention includes a black ink applying step.

[0278] The black ink application step is a step of applying black ink to the area on the permeable substrate to which the pretreatment liquid has been applied by an inkjet recording method.

[0279] In this step, black ink is applied together with yellow ink to the area on the permeable substrate to which the pretreatment liquid has been applied. This enhances the contrast between the yellow and black hues, improving the design, particularly when recording a wood-grain image.

[0280] (Black ink)

[0281] The black ink preferably contains water, black pigment and carboxyl group-containing resin D K .

[0282] -water-

[0283] 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, relative to the total amount of the black ink.

[0284] The upper limit of the water content also depends on the amounts of other components. The upper limit of the water content relative to the total amount of the black ink is, for example, 90% by mass or 80% by mass.

[0285] -Black pigment-

[0286] The black ink of the present invention preferably contains a black pigment.

[0287] Examples of the black pigment include carbon black, indigoamine pigments, and perylene pigments. More specific examples include CI Pigment Black 1, 7, 31, and 32.

[0288] 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, based on the total amount of the black ink.

[0289] -Carboxyl resin D K -

[0290] The black ink preferably contains a carboxyl group-containing resin D K .

[0291] Carboxyl resin D K There are no particular limitations on the resin (polymer) as long as it contains a carboxyl group.

[0292] 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 The polymer may have a cross-linked structure or may not have a cross-linked structure.

[0293] Carboxyl resin D K The preferred embodiment and carboxyl resin D Y The preferred method is the same.

[0294] Carboxyl resin D K It preferably functions as a dispersant for dispersing the black pigment in the black ink.

[0295] In carboxyl resin D K In the case of a polymer having a cross-linked structure, when the black ink reacts with the coagulant contained in the pre-treatment liquid, the black pigments are easily aggregated, thereby improving the black density.

[0296] By using yellow ink and black ink together, the contrast between the yellow hue and the black hue becomes stronger, and the design quality is improved especially when recording a wood-grain image.

[0297] From the above viewpoints, the carboxyl group-containing resin D K A polymer having a cross-linked structure is preferred.

[0298] Carboxyl resin D K The mass ratio K of the content of the black pigment to the content of the black pigment is preferably 0.20 to 0.80, more preferably 0.25 to 0.70.

[0299] Preferred mass ratio Y (carboxyl group-containing resin D Y The mass ratio of the content of PY110 relative to the content of PY110 is less than the mass ratio K.

[0300] When the mass ratio Y is less than the mass ratio K, color unevenness, including reddish hues, is suppressed when the yellow ink reacts with the coagulant contained in the pretreatment liquid. Furthermore, when the black ink reacts with the coagulant contained in the pretreatment liquid, the black pigments tend to aggregate, increasing the black density. This enhances the contrast between the yellow and black hues, improving design quality, particularly when recording wood-grain images.

[0301] -Organic solvents, surfactants-

[0302] The black ink may contain at least one organic solvent.

[0303] The black ink may contain at least one surfactant.

[0304] Preferred aspects of the organic solvent and surfactant contained in the black ink are the same as those of the organic solvent and surfactant contained in the yellow ink.

[0305] -Other ingredients-

[0306] The black ink may contain other components in addition to the above-mentioned components as needed.

[0307] Examples of other components contained in the black ink include the same components as those contained in the yellow ink.

[0308] The method of applying the black ink by the inkjet recording method is the same as the method of applying the yellow ink by the inkjet recording method.

[0309] Furthermore, the method may include a step of heating and drying the black ink applied to the permeable substrate after the black ink application step.

[0310] The preferred embodiment of the step of heating and drying the black ink is the same as the preferred embodiment of the step of heating and drying the yellow ink.

[0311] Hereinafter, an example of an inkjet recording apparatus used in the inkjet recording method of the present invention will be described with reference to the drawings.

[0312] In the drawings and descriptions of the present invention, substantially the same elements (such as components or parts) are denoted by the same reference numerals, and overlapping descriptions may be omitted.

[0313] Figure 1 This is a diagram conceptually showing an inkjet recording apparatus as an example of an inkjet recording apparatus used in the inkjet recording method of the present invention.

[0314] Figure 1The inkjet recording device shown is an example of an inkjet recording device having a conveying mechanism for conveying a permeable substrate in a roll-to-roll manner, and is the following device: a long permeable substrate A1 wound in a roll is unwound by a unwinding device W1, the unwound permeable substrate A1 is conveyed in the direction of the square arrow, passes through the pretreatment liquid applying device P1, the ink applying device IJ1 and the drying area D1 in sequence, and is finally wound up by the winding device W2.

[0315] In the unwinding device W1 for unwinding the permeable substrate A1, a pretreatment liquid applying device P1 and an ink applying device IJ1 are sequentially arranged on the downstream side in the conveyance direction of the permeable substrate A1 (hereinafter also simply referred to as "downstream side").

[0316] In the pre-treatment liquid applying apparatus P1 and the ink applying apparatus IJ1 , a pre-treatment liquid applying step and an ink applying step are performed.

[0317] The details of the pre-treatment liquid applying step and the ink applying step are as described above.

[0318] An area (not shown) for drying the pre-treatment liquid may be provided between the pre-treatment liquid applying device P1 and the ink applying device IJ1.

[0319] The ink applying device IJ1 includes at least one inkjet head.

[0320] The ink applying device 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.

[0321] A drying area D1 is arranged on the downstream side of the ink applying device IJ1.

[0322] In the drying area D1 , an ink drying process is performed.

[0323] [Method for manufacturing melamine decorative board]

[0324] The method for producing a melamine decorative board of the present invention preferably includes a step of obtaining decorative paper having an image recorded thereon using the inkjet recording method of the present invention (hereinafter also referred to as a "decorative paper production step"), and a step of impregnating the decorative paper having an image recorded thereon with a melamine resin (hereinafter also referred to as an "impregnation step").

[0325] Decorative Paper Manufacturing Process

[0326] The details of the decorative paper and the inkjet recording method are as described above.

[0327] In the decorative paper manufacturing process, it is preferable to record a wood-grain image on the decorative paper.

[0328] <Impregnation process>

[0329] As a method for impregnating decorative paper with a melamine resin, for example, a method of impregnating decorative paper with carbinol melamine and then heating the same can be mentioned. Heating the carbinol melamine causes a curing reaction to proceed, thereby obtaining a melamine resin.

[0330] The decorative paper may be impregnated with components other than the melamine resin.

[0331] When manufacturing a low-pressure melamine decorative board, it is preferable to include a step of hot-pressing the decorative paper impregnated with the melamine resin and the wood fiberboard after the impregnation step.

[0332] When manufacturing a high-pressure melamine decorative board, it is preferable to include a step of laminating and thermoforming the decorative paper impregnated with the melamine resin and the core paper impregnated with the phenolic resin after the impregnation step.

[0333] [Melamine decorative board]

[0334] The melamine decorative board of the present invention is produced by the method for producing a melamine decorative board of the present invention.

[0335] By impregnating decorative paper with an image recorded using the inkjet recording method of the present invention with a melamine resin, a melamine decorative board with a high yellow concentration can be obtained. In particular, by recording a wood-grain image on the decorative paper, excellent design properties can be achieved.

[0336] Furthermore, the melamine decorative board of the present invention is produced using decorative paper on which an image is recorded, obtained by the inkjet recording method of the present invention, and its specific structure and physical properties are difficult to determine.

[0337] Example

[0338] Hereinafter, examples of the present invention will be described, but the present invention is not limited to the following examples.

[0339] The viscosity was measured at 25° C. using a TV-22 viscometer manufactured by Toki Sangyo Co., Ltd.

[0340] The surface tension was measured at 25° C. using an automatic surface tensiometer manufactured by Kyowa Interface Science Co., Ltd. (product name: “CBVP-Z”).

[0341] The pH was measured at 25°C using a pH meter (model "HM-31") manufactured by DKK-TOA CORPORATION.

[0342] [Preparation of pretreatment solution]

[0343] <Pretreatment liquid P1>

[0344] -Synthesis of water-soluble polymer P1-

[0345] According to the method described in

[0200] to

[0204] of JP-A-2013-001854, a 20% by mass aqueous solution of the water-soluble polymer P1 was obtained.

[0346] The water-soluble polymer P1 is a random polymer containing a structural unit derived from methyl methacrylate, a structural unit derived from ethyl acrylate, and a structural unit derived from sodium acrylamide-2-methylpropanesulfonate at a mass ratio of 60:13:27.

[0347] The weight average molecular weight Mw of the water-soluble polymer P1 was 45,000.

[0348] -Preparation of pretreatment solution P1-

[0349] The following components were mixed to obtain a pretreatment liquid P1.

[0350] Malonic acid (manufactured by FUJIFILM Wako Pure Chemical Corporation) ... 5.6% by mass

[0351] Malic acid (manufactured by FUJIFILM Wako Pure Chemical Corporation) ... 3.8 mass%

[0352] 85% by mass phosphoric acid aqueous solution (manufactured by FUJIFILM Wako Pure Chemical Corporation) ...the amount of phosphoric acid was 2.9% by mass

[0353] DEGmBE: diethylene glycol monobutyl ether (manufactured by FUJIFILM Wako Pure Chemical Corporation) ... 6% by mass

[0354] · Water-soluble polymer P1 ...the amount of the water-soluble polymer is 0.4% by mass

[0355] Benzotriazole (manufactured by FUJIFILM Wako Pure Chemical Corporation) ... 1% by mass

[0356] Sodium dodecylbenzenesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.) ... 0.4 mass%

[0357] Defoaming agent (product name "TSA-739", manufactured by Momentive Performance Materials Inc., 15% by mass aqueous solution) ... 0.01% by mass as silicone oil

[0358] · Ion exchange water... The remainder of the total of the pretreatment solution to 100% by mass

[0359] <Pretreatment liquid P2 to Pretreatment liquid P7>

[0360] Pretreatment liquids P2 to P7 were obtained in the same manner as for the pretreatment liquid P1, except that the types and contents of the components contained in the pretreatment liquid P1 were changed to the types and contents described in Table 1.

[0361] [Table 1]

[0362] P1 P2 P3 P4 P5 P6 P7 DEGmBE 6 6 6 6 6 6 3 Malonic acid 5.6 - 1.7 3.8 9.5 18 5.6 Malic acid 3.8 - 1.2 2.5 6.3 10 3.8 calcium formate - 9.4 - - - - - phosphoric acid 2.9 - 2.9 2.9 2.9 2.9 2.9 Water-soluble polymer P1 0.4 0.4 0.4 0.4 0.4 0.4 0.4 Benzotriazole 1 1 1 1 1 1 1 Sodium dodecylbenzenesulfonate 0.4 0.4 0.4 0.4 0.4 0.4 - defoaming agent 0.01 0.01 0.01 0.01 0.01 0.01 0.01 Ion exchange water Remaining amount Remaining amount Remaining amount Remaining amount Remaining amount Remaining amount Remaining amount Viscosity (mPa·s) 1.7 1.8 1.3 1.5 2.3 3.4 1.5 Surface tension (mN / m) 32 32 32 32 32 32 40 pH 1.2 6.1 1.6 1.4 0.9 0.3 1.2

[0363] [Preparation of yellow ink]

[0364] Yellow Pigment Dispersion PY1

[0365] As a pigment dispersant, a carboxyl group-containing resin D was mixed as a solid content. Y The mixture was prepared by mixing 15 parts by mass of Solsperse 43000 (product name, 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. 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. The resulting dispersion was centrifuged at 6800 G for 20 minutes to remove coarse particles. Subsequently, ion-exchanged water and 0.3 parts by mass of a preservative (product name, "PROXEL GXL") were added to obtain a yellow pigment dispersion PY1.

[0366] The pigment concentration of the yellow pigment dispersion PY1 was 15% by mass.

[0367] Carboxyl resin D Y The mass ratio Y of the content of PY110 to the content of PY110 is 0.33.

[0368] Solsperse 43000 is a polymer having no cross-linked structure (acid value: 120 mgKOH / g, Mw: 21000). In Table 2, it is described as "Non-cross-linked polymer 1".

[0369] In addition, the mass ratio Y was measured and calculated by the following method.

[0370] 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, and the mass of the dried product was 0.200 part by mass.

[0371] The pigment concentration of the yellow pigment dispersion PY1 was 15% by mass, and therefore the mass of the pigment was 0.150 parts by mass.

[0372] Calculate the carboxyl resin D Y The mass of is 0.050 parts by mass.

[0373] Mass ratio Y = 0.050 ÷ 0.150 ≈ 0.33

[0374] In the yellow pigment dispersions PY2 to PY7 described later, the mass ratio Y is calculated in the same manner as in the yellow pigment dispersion PY1. The mass ratio M and the mass ratio K are also calculated in the same manner as in the mass ratio Y.

[0375] Yellow Pigment Dispersion PY2

[0376] In the yellow pigment dispersion PY1, the pigment dispersant was changed to carboxyl resin D Y (product name: "Joncryl JDX-6180", manufactured by BASF Corporation). Except for this, a yellow pigment dispersion PY2 was obtained in the same manner as the yellow pigment dispersion PY1.

[0377] The pigment concentration of the yellow pigment dispersion PY2 was 15% by mass.

[0378] Carboxyl resin D Y The mass ratio Y of the content of PY110 to the content of PY110 is 0.35.

[0379] Joncryl JDX-6180 is a polymer having no cross-linked structure (acid value: 230 mgKOH / g, Mw: 14000) and is described as "Non-cross-linked polymer 2" in Table 2.

[0380] Yellow Pigment Dispersion PY3

[0381] -Synthesis of water-soluble polymer Q1-

[0382] A monomer supply composition was prepared by mixing methacrylic acid (215 parts by mass), benzyl methacrylate (785 parts by mass), and isopropyl alcohol (375 parts by mass).

[0383] Furthermore, an initiator supply composition was prepared by mixing 2,2-azobis(2-methylbutyronitrile) (22.05 parts by mass) and isopropyl alcohol (187.5 parts by mass).

[0384] Next, isopropyl alcohol (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 over 2 hours. After the addition was completed, the resulting solution was further maintained at 80°C for 4 hours and then cooled to 25°C. After cooling, the reaction solution diluted with isopropyl alcohol and tetrahydrofuran was added dropwise to 10°C water, and the precipitated solid was filtered and dried by reprecipitation to obtain water-soluble polymer Q1.

[0385] The water-soluble polymer Q1 had a weight average molecular weight of approximately 30,000 and an acid value of 140 mgKOH / g.

[0386] -Preparation of yellow pigment dispersion PY3-

[0387] 0.8 equivalents of methacrylic acid in the water-soluble polymer Q1 (150 parts by mass) were neutralized using an aqueous potassium hydroxide solution. Ion-exchanged water was further added to adjust the concentration of the water-soluble polymer to 20% by mass, thereby obtaining an aqueous solution of the water-soluble polymer Q1. An aqueous solution of the water-soluble polymer Q1 (80 parts by mass), PY110 (manufactured by Sun Chemical) (48 parts by mass), water (75 parts by mass) and dipropylene glycol (30 parts by mass) were mixed. The mixed solution was dispersed to the target volume average particle size (less than 130 nm) using a bead mill (bead diameter 0.1 mmφ, zirconia beads). Ion-exchanged water was added to obtain a dispersion (uncrosslinked dispersion) in which PY110 was dispersed through the water-soluble polymer Q1. The concentration of PY110 in the uncrosslinked dispersion was 15% by mass.

[0388] To the uncrosslinked dispersion (136 parts by mass), 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 as a crosslinking agent, and the mixture was reacted at 50°C for 6.5 hours, followed by cooling to 25°C. The water-soluble polymer Q1 was crosslinked by the crosslinking agent.

[0389] Thus, a dispersion liquid (cross-linked dispersion liquid) containing PY110 and the cross-linked water-soluble polymer Q1 was obtained.

[0390] Next, ion-exchanged water was added to the obtained cross-linked dispersion, and ultrafiltration was performed using an ultrafilter (Sartorius, Sartocon Slice 200) and an ultrafiltration filter (Sartorius, Sartocon Slice Casse, molecular weight cutoff 100,000).

[0391] After purification to reduce the dipropylene glycol concentration in the cross-linked dispersion to 0.1% by mass or less, the dispersion was concentrated to a pigment concentration of 15% by mass, and 0.3 parts by mass of a preservative (product name "PROXEL GXL") was added to obtain a yellow pigment dispersion PY3.

[0392] Yellow pigment dispersion PY3 as carboxyl-containing resin D Y A cross-linked water-soluble polymer Q1 (hereinafter also referred to as "cross-linked polymer 1") is included.

[0393] The pigment concentration of the yellow pigment dispersion PY3 was 15% by mass.

[0394] Carboxyl resin D Y The mass ratio Y of the content of PY110 to the content of PY110 is 0.34.

[0395] Yellow Pigment Dispersion PY4

[0396] In the yellow pigment dispersion PY1, carboxyl resin D Y Yellow pigment dispersion PY4 was obtained by the same method as that for yellow pigment dispersion PY1 except that the amount of the compounded compound was changed to 4.5 parts by mass as the solid content.

[0397] The pigment concentration of the yellow pigment dispersion PY4 was 15% by mass.

[0398] Carboxyl resin D Y The mass ratio Y of the content of PY110 to the content of PY110 is 0.11.

[0399] Yellow Pigment Dispersion PY5

[0400] In the yellow pigment dispersion PY1, carboxyl resin D Y Yellow pigment dispersion PY5 was obtained by the same method as that for yellow pigment dispersion PY1 except that the amount of solid content was changed to 30 parts by mass.

[0401] The pigment concentration of the yellow pigment dispersion PY5 was 15% by mass.

[0402] Carboxyl resin D Y The mass ratio Y of the content of PY110 to the content of PY110 is 0.65.

[0403] Yellow Pigment Dispersion PY6

[0404] In the yellow pigment dispersion PY1, carboxyl resin D Y Yellow pigment dispersion PY6 was obtained by the same method as that for yellow pigment dispersion PY1 except that the amount of solid content was changed to 45 parts by mass.

[0405] The pigment concentration of the yellow pigment dispersion PY6 was 15% by mass.

[0406] Carboxyl resin D Y The mass ratio Y of the content of PY110 to the content of PY110 is 0.99.

[0407] Yellow Pigment Dispersion PY7

[0408] Yellow pigment dispersion PY7 was obtained in the same manner as yellow pigment dispersion PY1 except that the mixed liquid was dispersed using a bead mill (bead diameter 0.1 mmφ, zirconia beads) to a desired volume average particle size (190 nm or less).

[0409] The pigment concentration of the yellow pigment dispersion PY7 was 15% by mass.

[0410] Carboxyl resin D Y The mass ratio Y of the content of PY110 to the content of PY110 is 0.34.

[0411] Yellow Ink Y1

[0412] The following components were mixed to obtain a mixed solution. Subsequently, coarse particles were removed from the mixed solution using a 1 μm filter to obtain yellow ink Y1.

[0413] Yellow pigment dispersion PY1 (aqueous dispersion with a pigment concentration of 15% by mass) ... The pigment content in the yellow ink is 3.9% by mass.

[0414] Organic solvent: Glycerin, manufactured by FUJIFILM Wako Pure Chemical Corporation, boiling point 290°C...23.0% by mass

[0415] Organic solvent: PG (propylene glycol), manufactured by ADEKA CORPORATION, boiling point 188°C...15.0% by mass

[0416] Surfactant: Acetylene compound 1 (product name "Surfynol 465", manufactured by Nissin Chemical Industry Co., Ltd.) ... 0.8 mass%

[0417] Defoaming agent (product name "BYK-024", manufactured by BYK) ... 0.01 mass%

[0418] Colloidal silica (product name "ST-XS", manufactured by Nissan Chemical Corporation) ... 0.05% by mass as solid content

[0419] Water... The remaining amount of the yellow ink to make 100% by mass

[0420] Yellow inks Y2 to Y15

[0421] Yellow inks Y2 to Y15 were obtained by the same method as for the yellow ink Y1, except that the types and contents of the components contained in the yellow ink Y1 were changed to the types and contents described in Table 2.

[0422] The details of the components described in Table 2 are as follows.

[0423] Organic solvent: TEGmBE (triethylene glycol monobutyl ether), manufactured by FUJIFILM Wako Pure Chemical Corporation, boiling point 276°C

[0424] Surfactant: Acetylene compound 2 (product name "DINOL 604", manufactured by Nissin Chemical Industry Co., Ltd.)

[0425] Surfactant: Polyoxyethylene lauryl ether (product name "EMULGEN 120", manufactured by Kao Corporation)

[0426] Surfactant: Silicone compound (product name "BYK-347", manufactured by BYK)

[0427]

[0428] [Preparation of magenta ink]

[0429] <Magenta Pigment Dispersion PM1>

[0430] The above-mentioned water-soluble polymer Q1 aqueous solution (80 parts by mass), PR254 (product name "Irgazin Red L3630", manufactured by Sun Chemical Corporation) (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) to the target volume average particle size (130 nm or less). Ion-exchanged water was added to obtain a dispersion (uncrosslinked dispersion) in which PR254 was dispersed in the water-soluble polymer Q1. The concentration of PR254 in the uncrosslinked dispersion was 16% by mass.

[0431] The uncrosslinked dispersion was crosslinked in the same manner as for the yellow pigment dispersion PY3 to obtain a magenta pigment dispersion PM1.

[0432] Magenta pigment dispersion PM1 as carboxyl-containing resin D M Contains cross-linked polymer 1.

[0433] The pigment concentration of the magenta pigment dispersion PM1 was 16% by mass.

[0434] Carboxyl resin D M The mass ratio M of the content of PR254 to the content of PR254 is 0.41.

[0435] <Magenta Pigment Dispersion PM2>

[0436] Magenta pigment dispersion PM2 was obtained by the same method as for magenta pigment dispersion PM1, except that PR254 was replaced with CI Pigment Red 122 (product name “Chromofine Red”, manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd., PR122).

[0437] The pigment concentration of the magenta pigment dispersion PM2 was 16% by mass.

[0438] Carboxyl resin D M The mass ratio M of the content of PR122 to the content of PR122 is 0.39.

[0439] <Magenta Pigment Dispersion PM3>

[0440] Magenta pigment dispersion PM3 was obtained by the same method as that for magenta pigment dispersion PM1, except that PR254 was replaced with CI Pigment Violet (product name “Inkjet Magenta E5B02”, manufactured by Clariant, PV19).

[0441] The pigment concentration of the magenta pigment dispersion PM3 was 16% by mass.

[0442] Carboxyl resin D M The mass ratio M of the content of PV19 to the content of PV19 is 0.40.

[0443] Magenta ink M1

[0444] The following components were mixed to obtain a mixed solution. Subsequently, coarse particles were removed from the mixed solution using a 1 μm filter to obtain magenta ink M1.

[0445] Magenta pigment dispersion PM1 (aqueous dispersion with a pigment concentration of 16% by mass) ... an amount in which the pigment content in the magenta ink is 4% by mass

[0446] Organic solvent: Glycerin, manufactured by FUJIFILM Wako Pure Chemical Corporation), boiling point 290°C...20.0% by mass

[0447] Organic solvent: PG (propylene glycol), manufactured by ADEKA CORPORATION, boiling point 188°C...15.0% by mass

[0448] Surfactant: Acetylene compound (product name "Surfynol 465", manufactured by Nissin Chemical Industry Co., Ltd.) ... 0.9 mass%

[0449] Defoaming agent (product name "BYK-024", manufactured by BYK) ... 0.01 mass%

[0450] Colloidal silica (product name "ST-XS", manufactured by Nissan Chemical Corporation) ... 0.05% by mass as solid content

[0451] Water... The remaining amount of magenta ink to make 100% by mass

[0452] Magenta inks M2 and M3

[0453] Magenta inks M2 and M3 were obtained by the same method as for the magenta ink M1, except that the types and contents of the components contained in the magenta ink M1 were changed to the types and contents described in Table 3.

[0454] [Preparation of black ink]

[0455] <Black Pigment Dispersion PK1>

[0456] The above-mentioned water-soluble polymer Q1 aqueous solution (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 mixed solution was dispersed to the target volume average particle size (130 nm or less) using a bead mill (bead diameter 0.1 mmφ, zirconia beads). Ion-exchanged water was added to obtain a dispersion (uncrosslinked dispersion) in which PB7 was dispersed by the water-soluble polymer Q1. The concentration of PB7 in the uncrosslinked dispersion was 14% by mass.

[0457] The uncrosslinked dispersion was crosslinked in the same manner as for the yellow pigment dispersion PY3 to obtain a black pigment dispersion PK1.

[0458] Black pigment dispersion PK1 as carboxyl-containing resin D K Contains cross-linked polymer 1.

[0459] The pigment concentration of the black pigment dispersion PK1 was 14% by mass.

[0460] Carboxyl resin D K The mass ratio K of the content of PB to the content of PB7 is 0.41.

[0461] <Black Pigment Dispersion PK2>

[0462] In the black pigment dispersion PK1, except that the blending amount of PB7 was changed to 48 parts by mass, a black pigment dispersion PK2 was obtained by the same method as that for the black pigment dispersion PK1.

[0463] The pigment concentration of the black pigment dispersion PK2 was 14% by mass.

[0464] Carboxyl resin D K The mass ratio K of the content of PB to the content of PB7 is 0.33.

[0465] <Black Pigment Dispersion PK3>

[0466] In the black pigment dispersion PK1, except that the blending amount of PB7 was changed to 70 parts by mass, a black pigment dispersion PK3 was obtained by the same method as that for the black pigment dispersion PK1.

[0467] The pigment concentration of the black pigment dispersion PK3 was 14% by mass.

[0468] Carboxyl resin D K The mass ratio K of the content of PB to the content of PB7 is 0.21.

[0469] <Black Ink K1>

[0470] The following components were mixed to obtain a mixed solution. Subsequently, coarse particles were removed from the mixed solution using a 1 μm filter to obtain black ink K1.

[0471] Black pigment dispersion PK1 (aqueous dispersion with a pigment concentration of 14% by mass) ... The content of the pigment in the black ink is 4.4% by mass.

[0472] Organic solvent: Glycerin, manufactured by FUJIFILM Wako Pure Chemical Corporation), boiling point 290°C...18.0% by mass

[0473] Organic solvent: PG (propylene glycol), manufactured by ADEKA CORPORATION, boiling point 188°C...15.0% by mass

[0474] Surfactant: Acetylene compound 1 (product name "Surfynol 465", manufactured by Nissin Chemical Industry Co., Ltd.) ... 1.0 mass%

[0475] Defoaming agent (product name "BYK-024", manufactured by BYK) ... 0.01 mass%

[0476] Colloidal silica (product name "ST-XS", manufactured by Nissan Chemical Corporation) ... 0.05% by mass as solid content

[0477] Water... The remaining amount of the black ink to make 100% by mass

[0478] Black ink K2-K3

[0479] Black inks K2 and K3 were obtained by the same method as for the black ink K1, except that the types and contents of the components contained in the black ink K1 were changed to the types and contents described in Table 3.

[0480] [Preparation of cyan ink]

[0481] <Cyan Pigment Dispersion PC1>

[0482] The above-mentioned water-soluble polymer Q1 aqueous solution (80 parts by mass), CI Pigment Blue 15:3 (product name "TRB2", manufactured by DAINICHISEIKA COLOR & CHEMICALS MFG.CO., LTD., PB15:3) (50 parts by mass), water (75 parts by mass) and dipropylene glycol (30 parts by mass) were mixed. The mixed solution was dispersed to the target volume average particle size (130 nm or less) using a bead mill (bead diameter 0.1 mmφ, zirconia beads). Ion-exchanged water was added to obtain a dispersion (uncrosslinked dispersion) in which PB15:3 was dispersed by the water-soluble polymer Q1. The concentration of PB15:3 in the uncrosslinked dispersion was 14% by mass.

[0483] The uncrosslinked dispersion was crosslinked in the same manner as in the yellow pigment dispersion PY3 to obtain a cyan pigment dispersion PC1.

[0484] Cyan pigment dispersion PC1 as carboxyl-containing resin D C Contains cross-linked polymer 1.

[0485] The pigment concentration of the cyan pigment dispersion PC1 was 14% by mass.

[0486] Carboxyl resin D CThe mass ratio C of the content of PB15:3 to the content of PB15:3 is 0.32.

[0487] Cyan Ink C1

[0488] The following components were mixed to obtain a mixed solution. Subsequently, coarse particles were removed from the mixed solution using a 1 μm filter to obtain black ink K1.

[0489] Cyan pigment dispersion PC1 (aqueous dispersion with a pigment concentration of 14% by mass) ... an amount in which the pigment content in the cyan ink is 3% by mass

[0490] Organic solvent: Glycerin, manufactured by FUJIFILM Wako Pure Chemical Corporation), boiling point 290°C...22.0% by mass

[0491] Organic solvent: PG (propylene glycol), manufactured by ADEKA CORPORATION, boiling point 188°C...15.0% by mass

[0492] Surfactant: Acetylene compound 1 (product name "Surfynol 465", manufactured by Nissin Chemical Industry Co., Ltd.) ... 0.8 mass%

[0493] Defoaming agent (product name "BYK-024", manufactured by BYK) ... 0.01 mass%

[0494] Colloidal silica (product name "ST-XS", manufactured by Nissan Chemical Corporation) ... 0.05% by mass as solid content

[0495] · Water... The remaining amount of cyan ink to make 100% by mass

[0496] [Table 3]

[0497]

[0498] [Examples 1 to 24, Comparative Examples 1 and 2]

[0499] Prepared with Figure 1 An inkjet recording apparatus having the same structure as the inkjet recording apparatus shown in Table 4 was used to obtain image records using the pretreatment liquid, yellow ink, magenta ink, and black ink shown in Table 4.

[0500] [Table 4]

[0501] Pretreatment fluid Yellow ink Magenta ink Black ink Example 1 P1 Y1 M1 K1 Example 2 P2 Y1 M1 K1 Example 3 P3 Y1 M1 K1 Example 4 P4 Y1 M1 K1 Example 5 P5 Y1 M1 K1 Example 6 P6 Y1 M1 K1 Example 7 P1 Y2 M1 K1 Example 8 P1 Y3 M1 K1 Example 9 P1 Y4 M1 K1 Example 10 P1 Y5 M1 K1 Example 11 P1 Y6 M1 K1 Example 12 P1 Y7 M1 K1 Example 13 P1 Y8 M1 K1 Example 14 P1 Y9 M1 K1 Example 15 P1 Y11 M1 K1 Example 16 P1 Y10 M1 K1 Example 17 P7 Y11 M1 K1 Example 18 P1 Y12 M1 K1 Example 19 P1 Y13 M1 K1 Example 20 P1 Y14 M1 K1 Example 21 P1 Y1 M2 K1 Example 22 P1 Y1 M3 K1 Example 23 P1 Y1 M1 K2 Example 24 P1 Y1 M1 K3 Comparative Example 1 - Y1 M1 K1 Comparative Example 2 P1 Y15 M1 K1

[0502] <Pretreatment liquid application step>

[0503] The entire surface of the substrate was coated with a roller coater equipped with an anilox roller (100 to 300 lines / inch) and with a controlled coating amount to give a coating amount of 1.8 g / m 2 The pretreatment liquid is applied in a manner of

[0504] <Pretreatment liquid drying process>

[0505] Next, the substrate coated with the pretreatment liquid was dried by heating it from the back side (opposite to the side on which the image of the substrate was recorded) with a contact type flat heater under the following conditions while blowing air with a drying fan.

[0506] Drying method: air drying

[0507] Wind speed: 10m / s

[0508] Heating temperature: The temperature at which the surface temperature of the substrate on which the image is recorded reaches 50°C

[0509] <Ink application process>

[0510] As the inkjet heads in the inkjet recording apparatus, the inkjet recording line head "Samba PH G3LHF (RJCGen2)" (manufactured by FUJIFILM Dimatix, Inc.) was used. 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 the heads overlapped.

[0511] Next, each ink was ejected onto the substrate coated with the pretreatment liquid using an inkjet recording method under the following conditions to record an image, thereby producing an image record. The ink was allowed to dry while the substrate coated with ink was transported. The detailed conditions for inkjet recording are as follows.

[0512] Base material: Product name "MPK7299", manufactured by Felix Schoeller Group (air permeability resistance based on the Gurley air permeability test method: 12 seconds)

[0513] ·Substrate conveying mechanism: roll to roll

[0514] Inkjet head temperature: 30°C

[0515] Inkjet head resolution: 1200 dpi (dot per inch) × 1200 dpi

[0516] · Droplet volume: 3.0pL

[0517] Conveying speed: 50m / min

[0518] Heating method: Heating roller

[0519] <Ink Drying Process>

[0520] Next, the substrate was conveyed to a drying area, and the substrate with the ink applied thereto was dried under the following conditions while being heated from the back side of the substrate with a contact type flat heater and blown with a drying fan.

[0521] Drying method: air drying

[0522] Wind speed: 15m / s

[0523] Temperature: The surface temperature of the substrate on which the image is recorded reaches 80°C.

[0524] (evaluate)

[0525] Yellow density

[0526] In the above inkjet recording process, a solid yellow image with a duty of 100% was recorded to obtain an image record. The yellow density of the solid image portion of the obtained image record was measured using a spectrophotometer (product name "FD-7", manufactured by Konica Minolta, Inc.). The evaluation criteria are as follows. Grades of 2 and above are within the practically acceptable range.

[0527] 4: Yellow concentration exceeds 0.55.

[0528] 3: Yellow concentration exceeds 0.50 and is 0.55 or less.

[0529] 2: Yellow concentration exceeds 0.45 and is 0.50 or less.

[0530] 1: Yellow concentration is 0.45 or less.

[0531] <Ejection>

[0532] Using yellow ink, a solid image with a 100% duty cycle (nozzle check pattern) was continuously recorded over a 2000m length of substrate. The last 10m of the image-recorded area was cut, and the number of missing nozzles was visually inspected through the nozzle check pattern. Evaluation criteria are as follows.

[0533] 3: The number of missing nozzles is 0 to 1.

[0534] 2: The number of missing nozzles is 2 to 5.

[0535] 1: Six or more nozzles are missing.

[0536] Evaluation of Red Tone Unevenness 1 (Yellow Image)

[0537] Using a pretreatment solution and yellow ink, a yellow grayscale image was recorded in 10 steps, ranging from 10% to 100% duty. The resulting image records were visually observed. The evaluation criteria are as follows: Grade 2 or higher is within the practically acceptable range.

[0538] 4: No unevenness in the red tone is observed throughout the entire image, and the image is uniform.

[0539] 3: In the Duty 80% to 100% area, slight uneven red tones were observed upon closer inspection.

[0540] 2: In the area of ​​Duty 40% to 100%, uneven red tones are observed.

[0541] 1: Obvious uneven red tones are observed throughout the image.

[0542] Evaluation of Red Tone Unevenness 2 (Yellow + Magenta Image)

[0543] Using a pretreatment solution, magenta ink, and yellow ink, magenta ink with a duty ratio of 3% to 30% and yellow ink with a duty ratio of 10% to 100% was overlapped to record a 10-level grayscale image. The resulting image records were visually observed. The evaluation criteria are as follows. Grades 2 and above are considered acceptable for practical use.

[0544] 4: No unevenness in the red tone is observed throughout the entire image, and the image is uniform.

[0545] 3: In the yellow image, in the Duty 80% to 100% area, slight uneven red tones are observed upon closer inspection.

[0546] 2: In the area between Duty 40% and 100% of the yellow image, red unevenness is observed.

[0547] 1: Obvious uneven red tones are observed throughout the image.

[0548] <Contrast (the density of black in a yellow hue)>

[0549] Using a pretreatment solution, black ink, and yellow ink, a solid image was recorded: a black image at a duty of 100%, followed by a yellow image at a duty of 30%. The visual density (V density) of the resulting image record was measured using a spectrophotometer (product name "FD-7," manufactured by Konica Minolta, Inc.). The evaluation criteria are as follows. Grades of 2 and above are within the practically acceptable range.

[0550] 4: Visual concentration exceeds 1.10.

[0551] 3: Visual density exceeds 0.90 and is 1.10 or less.

[0552] 2: Visual density exceeds 0.70 and is 0.90 or less.

[0553] 1: Visual density is 0.70 or less.

[0554] Table 5 shows the details and evaluation results of the pre-treatment liquid, yellow ink, magenta ink, and black ink.

[0555] In Table 5, “mass ratio Y” refers to the mass ratio of carboxyl group-containing resin D Y The mass ratio of the content of carboxyl group-containing resin D to the content of PY110. K The mass ratio of the content of the yellow ink to the content of the black pigment. The "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. The "high boiling point solvent" refers to an organic solvent with a boiling point of 250°C or higher.

[0556]

[0557] As shown in Table 5, it can be seen that in Examples 1 to 24, the pretreatment liquid application step and the yellow ink application step are included, and the content of the organic solvent with 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. Therefore, the yellow density of the image is high and the ejection properties are excellent.

[0558] On the other hand, in Comparative Example 1, the pre-treatment liquid application step was not performed, and the yellow density of the image was extremely low.

[0559] In Comparative Example 2, it was found that the content of the organic solvent having a boiling point of 250° C. or higher was less than 15% by mass, and the ejection properties were poor.

[0560] It can be seen that in Example 1, the amount of coagulant applied to the permeable substrate is 0.08 g / m 2 As described above, compared with Example 3, the yellow density is higher.

[0561] It can be seen that in Example 1, the amount of coagulant applied to the permeable substrate is 0.35 g / m 2 Hereinafter, compared with Example 6, unevenness in red tone was suppressed.

[0562] In Example 1, it is known that the carboxyl-containing resin D Y The mass ratio Y of the content of PY110 to the content of PY110 is 0.25 or more, and compared with Example 10, the yellow density is high and the ejection property is excellent.

[0563] In Example 1, it is known that the carboxyl-containing resin D YThe mass ratio Y of the content of PY110 to the content of PY110 is 0.80 or less, and compared with Example 12, unevenness in red tone can be suppressed.

[0564] It is found that in Examples 1, 13, and 14, the inclusion of at least one surfactant selected from acetylene compounds and polyoxyalkylene alkyl ethers suppresses uneven red tone compared to Example 15.

[0565] It can be seen that in Example 1, the average particle size of PY110 is 160 nm or less, the yellow density is high compared to Example 19, the ejection properties are excellent, and the unevenness of the red tone is suppressed.

[0566] It can be seen that 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 is 10 mN / m or less, and red color unevenness is suppressed compared to Example 18.

[0567] It is known that in Example 1, the present invention further comprises imparting a mixture comprising water, PR254 and carboxyl-containing resin D M The process of adding magenta ink suppresses red tone unevenness compared with Examples 21 and 22.

[0568] In Example 1, it is known that the carboxyl-containing resin D Y The mass ratio Y of the content of PY110 is less than that of the carboxyl resin D K The mass ratio K of the content of the black pigment relative to the content of the black pigment is superior to that of Example 24.

[0569] It can be seen that in Example 1, the carboxyl resin D Y Since the polymer does not have a cross-linked structure, uneven red color tone is suppressed compared to Example 9.

[0570] A decorative board was produced using the pretreatment solution, yellow ink, magenta ink, black ink, and cyan ink C1 described in Example 1. Specifically, a wood grain pattern image was recorded on the decorative paper using the same method as the pretreatment solution application process and ink application process described above. The decorative paper with the image recorded was impregnated with methanol-based melamine and dried. The decorative paper impregnated with melamine resin and the core paper impregnated with phenolic resin were stacked and heated at 150°C and 100 kg / cm 2 , and 10 minutes, and the decorative board was obtained by heating and compressing.

[0571] Explanation of symbols

[0572] A1-permeable substrate, W1-unwinding device, P1-pretreatment liquid applying device, IJ1-ink applying device, D1-drying area, W2-winding device.

Claims

1. An inkjet recording method comprising the following steps: A step of applying a pretreatment liquid to a permeable substrate having an air permeability resistance of 5 to 50 seconds based on the Gurley air permeability test, wherein the pretreatment liquid contains at least one coagulant selected from the group consisting of an organic acid having a molecular weight of less than 1000 and a polyvalent metal salt, and water; and a step of applying yellow ink to the area of ​​the permeable substrate to which the pretreatment liquid has been applied by inkjet recording, The yellow ink contains water, an organic solvent with a boiling point of 250° C. or higher, CI Pigment Yellow 110, and a carboxyl-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 based on the total amount of the yellow ink.

2. The inkjet recording method according to claim 1, wherein The amount of the coagulant applied to the permeable substrate was 0.08 g / m 2 ~0.35g / m 2 .

3. The inkjet recording method according to claim 1 or 2, wherein In the yellow ink, the carboxyl resin D Y The mass ratio Y of the content of PEG-10 to the content of CI Pigment Yellow 110 is 0.25 to 0.

80.

4. The inkjet recording method according to claim 1 or 2, wherein The yellow ink contains at least one surfactant selected from acetylene compounds and polyoxyalkylene alkyl ethers.

5. The inkjet recording method according to claim 1 or 2, wherein In the yellow ink, the average particle size of the CI Pigment Yellow 110 is 100 nm to 160 nm.

6. The inkjet recording method according to claim 1 or 2, wherein The absolute value of the difference between the surface tension of the yellow ink and the surface tension of the pre-treatment liquid is 10 mN / m or less.

7. The inkjet recording method according to claim 1 or 2, further comprising the step of applying a coating containing water, CI Pigment Red 254 and carboxyl group-containing resin D to the area on the permeable substrate to which the pretreatment liquid has been applied by inkjet recording. M of magenta ink.

8. The inkjet recording method according to claim 1 or 2, further comprising the step of applying a coating containing water, black pigment and carboxyl group-containing resin D to the area on the permeable substrate to which the pretreatment liquid has been applied by inkjet recording. K Black ink, The carboxyl group-containing resin D in the yellow ink Y The mass ratio Y of the content of CI Pigment Yellow 110 is less than the carboxyl group-containing resin D in the black ink. K The mass ratio K of the content of the black pigment relative to the content of the black pigment.

9. The inkjet recording method according to claim 1 or 2, wherein The carboxyl-containing resin D Y It is a polymer without a cross-linked structure.

10. The inkjet recording method according to claim 7, wherein The carboxyl-containing resin D M It is a polymer with a cross-linked structure.

11. The inkjet recording method according to claim 8, wherein The carboxyl-containing resin D K It is a polymer with a cross-linked structure.

12. The inkjet recording method according to claim 1 or 2, wherein The permeable substrate is decorative paper for decorative panels.

13. A method for manufacturing a melamine decorative board, comprising the following steps: A step of obtaining decorative paper having an image recorded thereon using the inkjet recording method according to claim 12; and A step of impregnating the decorative paper having an image recorded thereon with a melamine resin. 14 . A melamine decorative board manufactured by the method for manufacturing a melamine decorative board according to claim 13 .

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