Treatment liquid for inkjet recording

Abstract

To provide a treatment liquid for inkjet recording capable of obtaining a high-quality printed matter having both good dot expandability and excellent image homogeneity even when the treatment liquid is applied to a low-permeable recording medium and then subjected to a heating and drying step.SOLUTION: The treatment liquid for ink-jet printing contains an organic compound (A), at least one compound (B) selected from the group consisting of a polyvalent metal salt, a polyvalent amine and an organic acid, and water, wherein the organic compound (A) is a water-soluble organic compound having a boiling point of not lower than 300 °C and an HLB value of not less than 6.0 and not more than 10.0 as calculated by the Davies' method, and a content of the organic compound (A) is not less than 3% by mass.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a treatment liquid for inkjet recording, an ink set for inkjet recording containing the treatment liquid for inkjet recording, a surface-treated recording medium, and an inkjet recording method using the treatment liquid for inkjet recording. [Background technology]

[0002] Inkjet recording methods have many advantages, such as not requiring plate making, being easily adaptable to variable printing, and not contacting the printed material, and therefore are becoming increasingly popular in a wide range of fields, including office and home use. In recent years, attempts have been made to expand the use of inkjet recording methods to commercial printing and industrial printing applications, which require significantly larger print volumes, and there is a demand for inkjet recording methods to print on a variety of recording media. In response to such demands, a method has been proposed in which a treatment liquid is applied to the recording medium in advance, before the ink is applied to the recording medium, to intentionally aggregate solid components contained in the ink, such as coloring materials and resins, thereby forming an ink aggregation layer on the recording medium.

[0003] For example, Patent Document 1 describes a treatment liquid containing 1,4-cyclohexanedimethanol, a polyvalent metal salt, and water, and states that by using this treatment liquid, it is possible to obtain high-quality printed matter that combines good dot expandability and excellent image uniformity when using a low-permeability recording medium.

[0004] Furthermore, Patent Document 2 describes a treatment liquid containing an alkanediol (A) having 9 or more carbon atoms in which two hydroxyl groups are bonded to carbon atoms that are not adjacent to each other, one or more compounds (B) selected from the group consisting of polyvalent metal salts and polyvalent amines, and water, and describes that by using this treatment liquid, high-quality printed matter that combines good dot expandability and excellent image uniformity can be obtained when using a low-permeability recording medium. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2023-164322 [Patent Document 2] Japanese Patent Application Publication No. 2023-164323 Summary of the Invention [Problem to be solved by the invention]

[0006] With the recent increase in printing speed, when forming an image using ink by inkjet recording on a recording medium that has been surface-treated with a treatment liquid for inkjet recording (hereinafter simply referred to as "treatment liquid"), the treatment liquid can reduce the drying speed of the ink, and the ink can stain the transport roller of the printing machine when the image-forming unit transfers the ink to the transport roller. To prevent such ink staining of the transport roller, or in response to demands for improved handling, such as storage, of recording media that have been surface-treated with a treatment liquid when applying the treatment liquid to the recording medium and printing on the printing machine are performed in separate processes, a heat-drying process may be performed after applying the treatment liquid. However, it has been found that the technologies described in Patent Documents 1 and 2 leave room for improvement in performance when applying a treatment liquid to a low-permeability recording medium and then performing a heat-drying process. An object of the present invention is to provide a treatment liquid for inkjet recording, an ink set for inkjet recording containing the treatment liquid for inkjet recording, a surface-treated recording medium, and an inkjet recording method using the treatment liquid for inkjet recording, which are capable of obtaining high-quality printed matter that achieves both good dot expandability and excellent image uniformity, even when a heat drying step is performed after the treatment liquid is applied to a low-permeability recording medium. [Means for solving the problem]

[0007] The present inventors have found that the above-mentioned problems can be solved by a treatment liquid for inkjet recording, which contains an organic compound (A) having a specific boiling point and hydrophilic-lipophilic balance (HLB) value, one or more compounds (B) selected from the group consisting of polyvalent metal salts, polyvalent amines, and organic acids, and water, wherein the content of the organic compound (A) is 3 mass % or more. That is, the present invention provides the following [1] to [4]. [1] Organic compound (A), one or more compounds (B) selected from the group consisting of polyvalent metal salts, polyvalent amines, and organic acids; and Contains water, the organic compound (A) is a water-soluble organic compound having a boiling point of 300°C or higher and an HLB value calculated by the Davis method of 6.0 or higher and 10.0 or lower, The treatment liquid for inkjet recording has a content of the organic compound (A) of 3% by mass or more. [2] An ink set for inkjet recording, comprising the treatment liquid for inkjet recording according to [1] above, and an ink containing a colorant and water. [3] A low-permeability recording medium having, on the surface thereof, an organic compound (A) and one or more compounds (B) selected from the group consisting of polyvalent metal salts, polyvalent amines, and organic acids; The surface-treated recording medium, wherein the organic compound (A) is a water-soluble organic compound having a boiling point of 300° C. or higher and an HLB value calculated by the Davis method of 6.0 or higher and 10.0 or lower. [4] An inkjet recording method comprising the following steps 1 and 2: Step 1: A step of applying the inkjet recording treatment liquid described in [1] above to a recording medium, and then heating and drying the same to obtain a surface-treated recording medium. Step 2: A step of forming an image on the treated surface of the surface-treated recording medium obtained in Step 1 by an inkjet recording method using an ink containing a colorant and water. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a treatment liquid for inkjet recording, an ink set for inkjet recording containing the treatment liquid for inkjet recording, a surface-treated recording medium, and an inkjet recording method using the treatment liquid for inkjet recording, which are capable of obtaining high-quality printed matter that combines good dot expandability and excellent image uniformity, even when a heat drying step is performed after the treatment liquid is applied to a low-permeability recording medium. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Inkjet recording processing liquid] The inkjet recording treatment liquid of the present invention contains an organic compound (A), one or more compounds (B) selected from the group consisting of polyvalent metal salts, polyvalent amines, and organic acids, and water. The organic compound (A) contained in the treatment liquid is a water-soluble organic compound having a boiling point of 300°C or higher and an HLB value of 6.0 or higher and 10.0 or lower, as calculated by the Davis method.

[0042] From the viewpoint of being able to obtain printed matter of high print quality in image formation by an inkjet recording system, the treatment liquid of the present invention is preferably used in the pretreatment of a recording medium to be used in inkjet recording, and more preferably used in the pretreatment of a low-permeability recording medium to be used in inkjet recording. In other words, the treatment liquid for inkjet recording of the present invention is preferably used as a pretreatment liquid for inkjet recording.

[0010] According to the present invention, even when a treatment liquid is applied to a low-permeability recording medium and then a heat drying process is performed, it is possible to obtain high-quality printed matter that combines good dot spreadability and excellent image uniformity. The reason for this is not entirely clear, but is thought to be as follows. The organic compound (A) contained in the treatment liquid of the present invention is a water-soluble organic compound having an HLB value of 6.0 or more and 10.0 or less, as calculated by the Davis method. Therefore, it exhibits a high affinity with the solvent component in the ink for inkjet recording (hereinafter also simply referred to as "ink"). It is thought that when the ink for inkjet recording lands on a recording medium treated with the treatment liquid of the present invention, the wettability of the ink to the recording medium is greatly improved, and the ink dots can be enlarged. Furthermore, the organic compound (A) has an HLB value of 6.0 or more and 10.0 or less, calculated by the Davis method, and exhibits moderate hydrophobicity. Therefore, when the ink contains a resin component, when the ink spreads after landing on a recording medium treated with the treatment liquid of the present invention, the resin component in the ink has the effect of swelling, promoting uniform thickening of the entire ink dot and causing uniform aggregation. As a result, it is possible to suppress fluctuations in dot expansion behavior caused by microscopic unevenness in the surface condition of the recording medium, which is thought to improve image uniformity. Furthermore, since the boiling point of the organic compound (A) is 300°C or higher, even when the treatment liquid is applied to the surface of a low-permeability recording medium and water and other substances are evaporated by heating and drying, the organic compound (A) can remain on the surface of the recording medium, and the above-mentioned effects can be achieved. Furthermore, because the HLB value of the organic compound (A) calculated by the Davis method is 6.0 to 10.0, the organic compound (A) exhibits a high surfactant effect. Therefore, when the treatment liquid is applied to the surface of a low-permeability recording medium and water and other components are evaporated by heating and drying, the one or more compounds (B) dispersed in the treatment liquid are thought to form minute, uniform precipitates on the recording medium. Therefore, when ink is applied to a recording medium treated with the treatment liquid of the present invention using an inkjet recording method, redissolution of compound (B) into the aqueous medium contained in the ink occurs uniformly within the ink dots. As a result, the aggregation effect of compound (B) on the dispersoids present in the ink for inkjet recording is uniformly manifested within the ink dots, and the ink thickens. This suppresses distortion of the ink dots and color mixing due to the mixing of different ink dots, further improving image uniformity. In the present invention, the dispersoids present in the ink for inkjet recording include not only ink components such as pigments and water-insoluble resins that are currently dispersed in the ink in a solid state, but also ink components that are in a dissolved state in the ink but lose their solubility when they come into contact with a recording medium that has been treated with the treatment liquid of the present invention, causing thickening or precipitation. Specific examples of such ink components include dyes, water-soluble resins, etc.

[0011] <Organic compounds (A)> The treatment liquid of the present invention contains an organic compound (A) having a boiling point of 300° C. or higher and an HLB value calculated by the Davis method of 6.0 or higher and 10.0 or lower. In the present invention, the boiling point means the boiling point at normal pressure (101.33 kPa). The organic compound (A) can be used alone or in combination of two or more.

[0012] Examples of the organic compound (A) having a boiling point of 300° C. or higher and an HLB value calculated by the Davis method of 6.0 to 10.0 include polyethylene glycol ether compounds and alkanetriol compounds having an aromatic ring.

[0013] In the present invention, the term "polyethylene glycol ether compound having an aromatic ring" refers to a compound having one or more aromatic rings and two or more ethylene oxide-derived units in one molecule. Examples of the polyethylene glycol ether compound having an aromatic ring include one or more selected from polyethylene glycol monoalkylphenyl ether, polyethylene glycol styrenated phenyl ether, polyethylene glycol aryl ether, polyethylene glycol benzyl phenyl ether, and polyethylene glycol monobenzyl ether. Examples of polyethylene glycol monoalkylphenyl ethers include polyethylene glycol monooctylphenyl ether and polyethylene glycol monododecylphenyl ether. Examples of polyethylene glycol styrenated phenyl ethers include polyethylene glycol monostyrenated phenyl ether, polyethylene glycol distyrenated phenyl ether, and polyethylene glycol tristyrenated phenyl ether. Examples of polyethylene glycol aryl ethers include polyethylene glycol monophenyl ether, polyethylene glycol mononaphthyl ether, polyethylene glycol bisphenol A ether, and polyethylene glycol bisphenol F ether. Examples of polyethylene glycol benzyl phenyl ethers include polyethylene glycol monobenzyl phenyl ether, polyethylene glycol dibenzyl phenyl ether, and polyethylene glycol tribenzyl phenyl ether. Examples of polyethylene glycol monobenzyl ethers include diethylene glycol monobenzyl ether and triethylene glycol monobenzyl ether.

[0014] Examples of the alkanetriol compound include linear or branched alkanetriols, such as 1,2,6-hexanetriol, 1,2,7-heptanetriol, 1,2,8-octanetriol, 1,2,9-nonanetriol, 1,2,10-decanetriol, 1,2,11-undecanetriol, 1,2,12-dodecanetriol, 1,2,13-tridecanetriol, and 1,2,14-tetradecanetriol.

[0015] Among these, from the viewpoint of dot spreadability and image uniformity on a low-permeability recording medium, the organic compound (A) is preferably at least one selected from the group consisting of polyethylene glycol monophenyl ether, polyethylene glycol monobenzyl ether, and alkanetriol, more preferably at least one selected from the group consisting of pentaethylene glycol monophenyl ether, diethylene glycol monobenzyl ether, triethylene glycol monobenzyl ether, tetraethylene glycol monobenzyl ether, tetraethylene glycol monobenzyl ether, 1,2,6-hexanetriol, 1,2,7-heptanetriol, 1,2,8-octanetriol, 1,2,9-nonanetriol, and 1,2,10-decanetriol, and even more preferably at least one selected from the group consisting of pentaethylene glycol phenyl ether, diethylene glycol monobenzyl ether, 1,2,7-heptanetriol, 1,2,9-nonanetriol, and 1,2,10-decanetriol.

[0016] The HLB value of the organic compound (A), calculated by the Davis method, is 10.0 or less, preferably 9.8 or less, more preferably 9.5 or less, from the viewpoint of dot spreadability on a low-permeability recording medium, and is 6.0 or more, preferably 6.2 or more, more preferably 6.5 or more, from the viewpoint of improving the water solubility of the organic compound (A) and image uniformity on a low-permeability recording medium. In the present invention, the HLB value is a value that indicates the affinity of a surfactant to water and oil as a hydrophile-lipophile balance, and can be calculated by the Davis method using the following formula. HLB value = 7 + Σ (number of hydrophilic groups) + Σ (number of lipophilic groups) + Σ (number of derivative groups) In the above formula, Σ (number of hydrophilic groups) is the number obtained by multiplying the number of groups of each hydrophilic group by the number of the hydrophilic groups, Σ (number of lipophilic groups) is the number obtained by multiplying the number of groups of each lipophilic group by the number of the lipophilic groups, and +Σ (number of derivative groups) is the number obtained by multiplying the number of groups of each derivative group by the number of the derivative groups. For example, diethylene glycol monobenzyl ether has one hydrophilic hydroxyl group (OH, group number: 1.9), five lipophilic methine groups (CH, group number: -0.475) and one methylene group (CH, group number: -0.475), for a total of six, and two derivative ethyleneoxy groups (CHCHO, group number: +0.33), so its HLB value is 7 + (1.9 × 1) + (-0.475 × 6) + (0.33 × 2) = 6.71. For the cardinal numbers, reference can be made to the cardinal numbers described in "Davis, JT; Proc. Intern. Congr. Surface Activity, 2nd, London, 1, 426 (1957)".

[0017] From the viewpoint of obtaining high-quality printed matter that combines good dot expandability and excellent image uniformity, the boiling point of the organic compound (A) is 300° C. or higher, preferably 310° C. or higher, and more preferably 325° C. or higher. The upper limit of the boiling point of the organic compound (A) is not particularly limited, but from the viewpoint of availability, it is preferably 500° C. or lower, more preferably 480° C. or lower, and even more preferably 450° C. or lower.

[0018] <Compound (B)> The treatment liquid of the present invention contains one or more compounds (B) selected from the group consisting of polyvalent metal salts, polyvalent amines, and organic acids. Note that the compound (B) does not include the organic compound (A).

[0019] [Polyvalent metal salts] Any polyvalent metal salt can be used as long as it is composed of a divalent or higher polyvalent metal ion and an anion (a counter ion of the polyvalent metal ion). When compound (B) contains a polyvalent metal salt, when the ink comes into contact with a recording medium that has been treated with the treatment liquid of the present invention, a precipitate of the polyvalent metal salt present on the recording medium redissolves in the ink, and the polyvalent metal salt acts to reduce the thickness of the electric double layer that stabilizes the dispersoids present in the ink. As a result, the dispersoids cannot be prevented from approaching each other, which reduces the dispersibility or solubility of the dispersoids present in the ink, and it is thought that this causes the dispersoids present in the ink to aggregate.

[0020] Examples of polyvalent metal ions having a valence of two or more include calcium, magnesium, copper, nickel, zinc, barium, aluminum, titanium, strontium, chromium, cobalt, and iron ions. Among these, the polyvalent metal ions constituting the polyvalent metal salt are preferably divalent or trivalent metal ions, more preferably divalent metal ions, from the viewpoint of obtaining high-quality printed matter that combines good dot expandability and excellent image uniformity. Examples of divalent metal ions include ions of elements belonging to Group 2 of the periodic table of elements, specifically magnesium ions, calcium ions, and iron(II) ions. Examples of trivalent metal ions include aluminum ions and iron(III) ions. Among these, from the viewpoint of obtaining high-quality printed matter that combines good dot expandability and excellent image uniformity, the polyvalent metal ion constituting the polyvalent metal salt is more preferably one or more selected from the group consisting of magnesium ions, calcium ions, and aluminum ions, even more preferably one or more selected from the group consisting of magnesium ions and calcium ions, and even more preferably magnesium ions.

[0021] The anions constituting the polyvalent metal salt include inorganic ions and organic ions. Examples of inorganic ions include monovalent anions such as nitrate ions and halide ions; and divalent anions such as sulfate ions. Examples of organic ions include organic acid ions such as carboxylate ions. Among these, the anion constituting the polyvalent metal salt is preferably an inorganic ion, more preferably one or more selected from the group consisting of nitrate ion and sulfate ion, and even more preferably nitrate ion.

[0022] From the viewpoint of obtaining high-quality printed matter that combines good dot expandability and excellent image uniformity, the polyvalent metal salt is preferably one or more selected from the group consisting of magnesium nitrate, magnesium sulfate, calcium nitrate, and aluminum nitrate, more preferably one or more selected from the group consisting of magnesium nitrate, calcium nitrate, and aluminum nitrate, and even more preferably one or more selected from the group consisting of magnesium nitrate and calcium nitrate. The polyvalent metal salt may have water of hydration in the raw material form. The polyvalent metal salts can be used alone or in combination of two or more.

[0023] [Polyamine] A polyamine is a compound having multiple amino groups in the molecule. When compound (B) contains a polyvalent amine, when the ink comes into contact with a recording medium that has been treated with the treatment liquid of the present invention, the precipitate of the polyvalent amine present on the recording medium redissolves in the ink and exhibits cationicity, and the cationic polyvalent amine bonds with the anionic dispersoids present in the ink and acts to dissipate the charge of the dispersoids. As a result, it is thought that the dispersoids cannot be prevented from approaching each other, which reduces the dispersibility or solubility of the dispersoids present in the ink, causing the dispersoids present in the ink to aggregate. The amino group of the polyamine may be ammonia, a primary amine, or a monovalent functional group (-NH, -NHR, -NRR') formed by removing one hydrogen atom from a secondary amine. Here, R and R' represent hydrocarbon groups. The polyamine may also be in the form of a salt. Examples of the salts of polyvalent amines include inorganic acid salts or organic acid salts of polyvalent amines. Examples of inorganic acid salts of polyvalent amines include hydrochlorides, sulfates, nitrates, and phosphates. Examples of organic acid salts of polyvalent amines include carboxylates and sulfonates. Furthermore, the polyvalent amines may be quaternary ammonium salts in which the amino groups are quaternized with a quaternizing agent.

[0024] The polyvalent amine may be an alkanediamine. From the viewpoint of obtaining high-quality printed matter that combines good dot expandability and excellent image uniformity, the alkanediamine is preferably at least one selected from the group consisting of ethylenediamine (1,2-diaminoethane), 1,2-diaminopropane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-pentamethylenediamine, 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, and 1,8-octamethylenediamine.

[0025] As the polyamine, a polymer having multiple amino groups in the molecule (hereinafter also referred to as "amino group-containing polymer") is preferred from the viewpoint of obtaining high-quality printed matter that combines good dot expandability and excellent image uniformity. The amino group-containing polymer is preferably a polymer containing a structural unit derived from a polymerizable monomer having at least one amino group. The amino group-containing polymer may be in the form of a salt or a quaternary ammonium salt in which the amino group is quaternized with a quaternizing agent.

[0026] Preferred examples of the amino group-containing polymer and salts thereof include one or more selected from the group consisting of polyethyleneimine, polyvinylamine, polyallylamine, polydiallylmethylamine, polydiallylethylamine, dimethylamine / epichlorohydrin copolymer, dimethylamine / ammonia / epichlorohydrin copolymer, and salts thereof. The quaternary ammonium salt of the amino group-containing polymer is preferably a diallyl quaternized ammonium salt polymer, and more preferably at least one selected from the group consisting of polydiallyldimethylammonium chloride, polydiallyldiethylammonium chloride, polydiallylmethylethylammonium ethyl sulfate, diallyldimethylammonium chloride / acrylic acid copolymer, diallyldimethylammonium chloride / acrylamide copolymer, and diallyldimethylammonium chloride / acrylic acid / acrylamide copolymer.

[0027] The polyvalent amine is preferably in the form of a polyvalent amine salt. From the viewpoint of increasing the density of the salt to significantly exhibit the effect of reducing the dispersibility or solubility of dispersoids present in the inkjet recording ink and obtaining high-quality printed matter that combines good dot expandability and excellent image uniformity, the polyvalent amine salt is preferably a salt of an amino group-containing polymer, more preferably one or more selected from the group consisting of polydiallyldimethylammonium chloride, polydiallylmethylethylammonium ethyl sulfate, dimethylamine / epichlorohydrin copolymer, polyethyleneimine hydrochloride, and polyallylamine hydrochloride, and even more preferably one or more selected from the group consisting of polydiallyldimethylammonium chloride and dimethylamine / epichlorohydrin copolymer. The average molecular weight of the amino group-containing polymer salt is preferably 5,000 or more, more preferably 6,000 or more, from the viewpoint of increasing the density of the salt and improving the image uniformity of printed matter when using a low-permeability recording medium. Furthermore, from the viewpoint of suppressing thickening of the treatment liquid, uniformly applying the treatment liquid to the recording medium, and improving the image uniformity of printed matter, the average molecular weight of the amino group-containing polymer salt is preferably 100,000 or less, more preferably 50,000 or less, and even more preferably 30,000 or less. The average molecular weight of the amino group-containing polymer salt can be measured by gel permeation chromatography (GPC). When a commercially available product is used as the amino group-containing polymer salt, the average molecular weight of the amino group-containing polymer salt can be determined by referring to the catalog value of each commercially available product. Suitable examples of commercially available salts of amino group-containing polymers include the "PAS" series manufactured by Nittobo Medical Co., Ltd. and the "Unisense" series manufactured by Senka Corporation. The polyamines can be used alone or in combination of two or more.

[0028] [Organic acid] An organic acid is a compound that has one or more carboxy groups in the molecule. When compound (B) contains an organic acid, when the ink comes into contact with a recording medium that has been treated with the treatment liquid of the present invention, the precipitate of the organic acid present on the recording medium redissolves in the ink, and the organic acid lowers the ink pH, causing the charge of the dispersoids to disappear, making it impossible to suppress the dispersoids from approaching each other. This reduces the dispersibility or solubility of the dispersoids present in the ink, and is thought to cause the dispersoids present in the ink to aggregate.

[0029] Preferred examples of organic acids include poly(meth)acrylic acid, acetic acid, glycolic acid, oxalic acid, malonic acid, malic acid, maleic acid, ascorbic acid, succinic acid, glutaric acid, fumaric acid, citric acid, tartaric acid, lactic acid, pyrrolidonecarboxylic acid, pyronecarboxylic acid, pyrrolecarboxylic acid, furancarboxylic acid, pyridinecarboxylic acid, coumaric acid, thiophenecarboxylic acid, nicotinic acid, and derivatives of these compounds. The organic acid may also be in the form of a salt. When the organic acid is in the form of a salt, the counter cation of the organic acid may be an inorganic ion or an organic ion, with ammonium cation being preferred. However, when the organic acid forms a polyvalent metal salt, it is included in the above-mentioned polyvalent metal salt, and when the organic acid forms a salt with a polyvalent amine, it is included in the above-mentioned polyvalent amine. The organic acids may be used singly or in combination of two or more.

[0030] From the viewpoint of obtaining high-quality printed matter that combines good dot expandability and excellent image uniformity, the treatment liquid of the present invention preferably contains, as organic compound (A), one or more compounds selected from the group consisting of polyethylene glycol ethers and alkanetriols having an aromatic ring, and a polyvalent metal salt as compound (B), and more preferably contains, as organic compound (A), one or more compounds selected from the group consisting of polyethylene glycol ethers and alkanetriols having an aromatic ring, and a polyvalent metal salt as compound (B), and more preferably contains, as organic compound (A), one or more compounds selected from the group consisting of magnesium nitrate, calcium nitrate, and aluminum nitrate, and More preferred is one containing one or more compounds selected from the group consisting of pentaethylene glycol phenyl ether, 1,2,7-heptanetriol, 1,2,9-nonanetriol, and 1,2,10-decanetriol, and containing, as compound (B), one or more polyvalent metal salts selected from the group consisting of magnesium nitrate, calcium nitrate, and aluminum nitrate; and even more preferred is one containing, as organic compound (A), one or more compounds selected from the group consisting of pentaethylene glycol phenyl ether, 1,2,9-nonanetriol, and 1,2,10-decanetriol, and containing, as compound (B), one or more polyvalent metal salts selected from the group consisting of magnesium nitrate and calcium nitrate.

[0031] <Water> The treatment liquid of the present invention contains water. The water used in the treatment solution of the present invention is preferably pure water or ion-exchanged water from the viewpoint of preventing the inclusion of unintended substances.

[0032] The treatment liquid of the present invention may further contain, as necessary, other components besides the organic compound (A) and the compound (B), such as a water-soluble organic solvent, a pH adjuster, a surfactant, a colorant, an antifoaming agent, an antiseptic / fungal agent, and a rust inhibitor.

[0033] (Water-soluble organic solvent) The treatment liquid of the present invention may further contain a water-soluble organic solvent from the viewpoint of ensuring sufficient solubility of the organic compound (A) in the treatment liquid and obtaining high-quality printed matter that combines better dot expandability and excellent image uniformity. In the present invention, the water-soluble organic solvent refers to an organic compound that is liquid at 20°C and dissolves in 100 mL of water at 25°C in an amount of 5 mL or more. Examples of water-soluble organic solvents include polyhydric alcohols; ethers such as polyhydric alcohol alkyl ethers, polyhydric alcohol aryl ethers, and polyhydric alcohol aralkyl ethers; nitrogen-containing heterocyclic compounds; amides; amines; and sulfur-containing compounds. It should be noted that the polyhydric alcohol aryl ethers and polyhydric alcohol aralkyl ethers do not include polyethylene glycol ether compounds having an aromatic ring with a boiling point of 300°C or higher.

[0034] Examples of polyhydric alcohols include ethylene glycol, diethylene glycol, propylene glycol (1,2-propanediol), 1,3-propylene glycol, dipropylene glycol (isomer mixture), 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 3-methyl-1,3-butanediol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,2-pentanediol, 1,3 Examples of diols include 1,4-pentanediol, 2,4-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,3-hexanediol, 2,5-hexanediol, 1,5-hexanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,5-pentanediol, 1,4-cyclohexanediol, 1,7-heptanediol, 1,8-octanediol, and 1,2-octanediol.

[0035] Examples of polyhydric alcohol alkyl ethers include (poly)alkylene glycol monoalkyl ethers such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, and dipropylene glycol monoethyl ether. Examples of polyhydric alcohol aryl ethers include ethylene glycol monophenyl ether and ethylene glycol monotolyl ether. Examples of polyhydric alcohol aralkyl ethers include ethylene glycol monobenzyl ether and ethylene glycol monophenethyl ether. Examples of the nitrogen-containing heterocyclic compound include 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, and ε-caprolactam. Examples of amides include formamide, N-methylformamide, N,N-dimethylformamide, 3-methoxy-N,N-dimethylpropionamide, and 3-butoxy-N,N-dimethylpropionamide. Examples of amines include monoethanolamine, diethanolamine, triethanolamine, and triethylamine. Examples of sulfur-containing compounds include dimethyl sulfoxide, sulfolane, and thiodiethanol. Other examples of water-soluble organic solvents include propylene carbonate and ethylene carbonate.

[0036] Among these, when a water-soluble organic solvent is used, the water-soluble organic solvent is preferably at least one selected from the group consisting of polyhydric alcohols and polyhydric alcohol alkyl ethers, more preferably a polyhydric alcohol, from the viewpoint of obtaining high-quality printed matter that combines good dot expandability and excellent image uniformity. From the same viewpoint as above, the polyhydric alcohol is preferably a diol, more preferably one or more selected from the group consisting of ethylene glycol, diethylene glycol, propylene glycol (1,2-propanediol), 1,3-propylene glycol, dipropylene glycol (mixture of isomers), 1,2-butanediol, 1,3-butanediol, and 1,4-butanediol, and even more preferably one or more selected from the group consisting of diethylene glycol, propylene glycol (1,2-propanediol), and dipropylene glycol (mixture of isomers). From the same viewpoint as above, the polyhydric alcohol alkyl ether is preferably a (poly)alkylene glycol monoalkyl ether, more preferably at least one selected from the group consisting of ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether, and triethylene glycol monobutyl ether, and even more preferably at least one selected from the group consisting of diethylene glycol monobutyl ether and triethylene glycol monobutyl ether. The water-soluble organic solvents can be used alone or in combination of two or more.

[0037] (pH adjuster) The processing liquid of the present invention may contain a pH adjuster. The pH adjuster refers to an agent that suppresses pH fluctuations due to environmental changes and maintains the pH of the treatment solution constant. The pH adjuster can be selected arbitrarily depending on the pH of the treatment liquid of the present invention. Examples of basic compounds used as pH adjusters to basify the processing solution of the present invention include alkanolamines such as dimethylethanolamine, diethanolamine, triethanolamine, and N-methyldiethanolamine; primary amines, secondary amines, tertiary amines, and quaternary ammonium salts; aqueous ammonia; alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; and alkali metal carbonates such as lithium carbonate, sodium carbonate, potassium carbonate, and sodium hydrogencarbonate. When the pH adjuster is an alkanolamine, a primary amine, a secondary amine, a tertiary amine, or a quaternary ammonium salt, it is preferable that the amine or quaternary ammonium salt is monovalent. Examples of acidic compounds used as pH adjusters to acidify the treatment solution of the present invention include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, and boric acid; organic acids such as acetic acid, citric acid, succinic acid, tartaric acid, malic acid, fumaric acid, malonic acid, ascorbic acid, and glutamic acid; and alkali metal acetates such as lithium acetate and sodium acetate. The pH adjusters can be used alone or in combination of two or more.

[0038] (surfactant) The treatment liquid of the present invention may contain a surfactant. The surfactant is preferably a nonionic surfactant. Examples of nonionic surfactants include polyoxyalkylene alkyl ether surfactants, acetylene alcohol surfactants such as acetylene glycol surfactants, polyhydric alcohol surfactants, fatty acid alkanolamides, silicone surfactants, and fluorine surfactants. Among these, the surfactant is preferably an acetylene alcohol surfactant, and more preferably an acetylene glycol surfactant. Examples of acetylene glycol surfactants include 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, and ethylene oxide adducts of these diols. Examples of acetylene alcohol surfactants other than acetylene glycol surfactants include 3,5-dimethyl-1-hexyn-3-ol, 2,4-dimethyl-5-hexyn-3-ol, and ethylene oxide adducts of these monools. The sum (n) of the average number of moles of ethyleneoxy groups (EO) added in the ethylene oxide adduct is preferably 0 or more, and is preferably 20 or less, more preferably 10 or less. Examples of commercially available nonionic surfactants include the "Surfynol" series manufactured by Nissin Chemical Industry Co., Ltd. and Air Products & Chemicals, and the "Acetylenol" series manufactured by Kawaken Fine Chemicals Co., Ltd. The surfactants can be used alone or in combination of two or more.

[0039] The treatment liquid of the present invention may contain a colorant, as described below, to the extent that the effects of the present invention are not impaired. When the treatment liquid of the present invention contains a colorant, the colorant is preferably a pigment or a hydrophobic dye from the viewpoint of water resistance, and is preferably a pigment from the viewpoint of achieving high weather resistance.

[0040] (Composition of Processing Solution) The content of organic compound (A) in the treatment liquid of the present invention is 3% by mass or more, preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, from the viewpoint of obtaining high-quality printed matter that combines good dot expandability and excellent image uniformity, and from the same viewpoint as above and from the viewpoint of economy, it is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 45% by mass or less.

[0041] The content of compound (B) in the treatment liquid of the present invention is preferably 3% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, and still more preferably 13% by mass or more, from the viewpoint of obtaining high-quality printed matter that combines good dot expandability and excellent image uniformity, and from the same viewpoint as above, it is preferably 40% by mass or less, more preferably 35% by mass or less, even more preferably 30% by mass or less, still more preferably 25% by mass or less, and still more preferably 20% by mass or less. When compound (B) is used in the form of a hydrate having water of hydration as the raw material form of the polyvalent metal salt, the content of the polyvalent metal salt in the treatment liquid of the present invention means the content of the anhydrous polyvalent metal salt.

[0042] From the viewpoint of obtaining high-quality printed matter that combines good dot expandability and excellent image uniformity, the water content in the treatment liquid of the present invention is preferably 85% by mass or less, more preferably 80% by mass or less, even more preferably 75% by mass or less, and even more preferably 70% by mass or less; and from the same viewpoint as above and from the viewpoint of economy, the water content is preferably 15% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, even more preferably 35% by mass or more, and even more preferably 40% by mass or more. When the polyvalent metal salt is used in the form of a hydrate having water of hydration as a raw material, the water content in the treatment liquid of the present invention means the amount including the water content from the hydrate of the polyvalent metal salt.

[0043] The mass ratio of the content of compound (B) to the content of organic compound (A) in the treatment liquid of the present invention [compound (B) / organic compound (A)] is preferably 0.1 or more, more preferably 0.2 or more, and even more preferably 0.3 or more, from the viewpoint of obtaining high-quality printed matter that combines good dot expandability and excellent image uniformity, and from the same viewpoint as above, is preferably 8 or less, more preferably 4 or less, even more preferably 2 or less, and even more preferably 1 or less.

[0044] The mass ratio of the content of organic compound (A) to the content of water in the treatment liquid of the present invention [organic compound (A) / water] is preferably 0.04 or more, more preferably 0.07 or more, even more preferably 0.10 or more, still more preferably 0.15 or more, still more preferably 0.20 or more, and still more preferably 0.25 or more, from the same viewpoint as above and from the viewpoint of economy, and is preferably 2.0 or less, more preferably 1.5 or less, and even more preferably 1.0 or less, from the viewpoint of economy as well.

[0045] When the treatment liquid of the present invention further contains a water-soluble organic solvent, the content of the water-soluble organic solvent in the treatment liquid is preferably 30% by mass or less, more preferably 15% by mass or less, even more preferably 5% by mass or less, and still more preferably 2% by mass or less, from the viewpoint of obtaining high-quality printed matter that combines good dot expandability and excellent image uniformity. When two or more water-soluble organic solvents are used in the treatment liquid of the present invention, the content is the total content of the water-soluble organic solvents.

[0046] The content of coloring material in the treatment liquid of the present invention is preferably 1% by mass or less, more preferably 0.1% by mass or less, even more preferably 0.01% by mass or less, and even more preferably 0% by mass, i.e., it is even more preferable that the treatment liquid of the present invention does not contain any coloring material. If the content of the colorant in the treatment liquid of the present invention is within the above range, when the treatment liquid is used together with an ink for ink-jet recording to perform ink-jet recording, an image can be formed without affecting the hue of the ink.

[0047] Although there are no particular restrictions on the viscosity of the treatment liquid of the present invention, from the viewpoint of obtaining high-quality prints that combine good dot expandability and excellent image uniformity, the viscosity of the treatment liquid at 25°C is preferably 1 mPa·s or more, more preferably 3 mPa·s or more, even more preferably 4 mPa·s or more, and preferably 100 mPa·s or less, more preferably 80 mPa·s or less, even more preferably 50 mPa·s or less, still more preferably 30 mPa·s or less, still more preferably 20 mPa·s or less, and still more preferably 10 mPa·s or less. The viscosity of the treatment liquid of the present invention is measured by the method described in the examples. The pH of the processing solution of the present invention at 20°C is preferably 3.5 or higher, more preferably 4.0 or higher, even more preferably 4.5 or higher, and is preferably 11.0 or lower, more preferably 10.5 or lower, even more preferably 10.0 or lower. The pH of the processing solution of the present invention is measured by the method described in the Examples.

[0048] (Preparation of processing solution) The treatment liquid of the present invention is prepared by appropriately blending and mixing the organic compound (A), the compound (B), water, and, if necessary, the other components described above. The pH of the treatment liquid can be appropriately adjusted with the pH adjuster described above. The amount of each component blended when preparing the treatment liquid for inkjet recording of the present invention can be considered as the content of each component in the treatment liquid for inkjet recording of the present invention.

[0049] [Inkjet recording ink set] <Inkjet recording ink> Hereinafter, an ink for ink jet recording that can be applied to a recording medium that has been treated with the treatment liquid of the present invention (hereinafter also referred to as a "surface-treated recording medium") will be described.

[0033] From the viewpoint of obtaining high-quality printed matter that combines good dot spreadability and excellent image uniformity, the ink for inkjet recording preferably contains a colorant and water. That is, in the present invention, the treatment liquid can be used as an inkjet recording ink set together with an ink containing a colorant and water.

[0050] [Coloring material] The colorant used in the inkjet recording ink may be either a dye or a pigment, and among these, it is preferable to use a pigment as the colorant from the viewpoint of water resistance, light resistance, weather resistance, gas resistance, etc. The pigment may be any of known organic pigments and inorganic pigments, and may be used singly or in combination of two or more kinds, or may be a mixed crystal. Examples of inorganic pigments include titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chrome yellow, etc. Carbon black produced by known methods such as a contact method, a furnace method, or a thermal method can also be used as the inorganic pigment. Examples of organic pigments include azo pigments, polycyclic pigments (e.g., phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc.), dye chelates (e.g., basic dye chelates, acid dye chelates, etc.), nitro pigments, nitroso pigments, and aniline black. As the pigment, hollow particles such as hollow resin particles and hollow inorganic particles can be used. Furthermore, glossy color pigments such as gold and silver pigments or metallic pigments can also be used. Specific examples of pigments for black inks include carbon blacks (CI Pigment Black 7) such as furnace black, lamp black, acetylene black, and channel black; metals such as copper, iron (CI Pigment Black 11), and titanium oxide; and organic pigments such as aniline black (CI Pigment Black 1). Specific examples of pigments for chromatic inks include one or more product numbers selected from the group consisting of CI Pigment Yellow, CI Pigment Orange, CI Pigment Red, CI Pigment Violet, CI Pigment Blue, and CI Pigment Green.

[0051] The dye is not particularly limited, and examples thereof include acid dyes, basic dyes, direct dyes, reactive dyes, etc. The dyes may be used alone or in combination of two or more. Examples of dyes include products with product numbers selected from the group consisting of CI Acid Yellow, CI Acid Red, CI Acid Blue, CI Acid Black, CI Food Black, CI Direct Yellow, CI Direct Red, CI Direct Blue, CI Direct Black, CI Reactive Red, and CI Reactive Black.

[0052] When an inkjet recording ink contains a pigment, the pigment is dispersed in a medium in the ink. The form of the pigment in the inkjet recording ink includes a form in which the pigment is dispersed using a resin (hereinafter also referred to as a "pigment dispersion resin") or a surfactant as a dispersant, and a form of a self-dispersed pigment that is dispersed without using a dispersant. Among these, the form in which the pigment is dispersed using a pigment dispersion resin is preferred as the form of the pigment in the inkjet recording ink. The pigment dispersing resin may be either a water-soluble resin or a water-insoluble resin. Here, regarding the "water-soluble" and "water-insoluble" of a resin, when a resin that has been dried at 105°C for 2 hours and has reached a constant weight is dissolved in 100 g of water at 25°C until saturation is reached, if the dissolved amount exceeds 10 g it is judged to be "water-soluble," and if it is 10 g or less it is judged to be "water-insoluble." Furthermore, as will be described later, if the resin has anionic groups that have been neutralized with a neutralizing agent, the resin is judged to be "water-soluble" by the amount of dissolution measured in the presence of a neutralizing agent such that the mass ratio of the resin to the neutralizing agent is the same as that in an inkjet recording ink.

[0053] Specific examples of the form of the pigment in the inkjet recording ink, from the viewpoint of improving the dispersion stability of the pigment, include (a) a form in which a water-soluble resin is adsorbed onto the surface of the pigment, (b) a form in which a water-soluble surfactant or a water-dispersible surfactant is adsorbed onto the surface of the pigment, (c) a form in which a hydrophilic functional group is chemically or physically introduced onto the surface of the pigment and the pigment is dispersed without using a pigment dispersing resin or a surfactant, and (d) a form in which the pigment is coated with a water-insoluble resin.

[0054] The pigments having the above forms (a) to (d) preferably have anionic properties. This allows polyvalent metal ions derived from a polyvalent metal salt contained in the treatment liquid or ammonium cations derived from amino groups of a polyvalent amine to electrostatically interact with the anionic properties of the pigment surface, reducing the dispersibility of the pigment present in the ink and causing it to aggregate. As a result, it is believed that high-quality printed matter that combines good dot spreadability and excellent image uniformity can be obtained when using a low-permeability recording medium. From this perspective, in form (a), the water-soluble resin preferably has an anionic group; in form (b), the water-soluble surfactant or water-dispersible surfactant preferably has an anionic group; in form (c), the hydrophilic functional group introduced onto the pigment surface preferably has an anionic group; and in form (d), the water-insoluble resin preferably has an anionic group. The anionic group may be a group that dissociates to release a hydrogen ion, such as a carboxyl group (-COOM), a sulfonic acid group (-SO3M), or a phosphate group (-OPO3M2), or a group in the form of a dissociated ion thereof (-COO - , -SO3 - , -OPO3 2- , -OPO3 - In the chemical formula, M represents a hydrogen atom, an alkali metal, ammonium, or an organic ammonium.

[0055] Among these, the form of the pigment in the inkjet recording ink is preferably one or more forms selected from the group consisting of form (c) and form (d), and more preferably form (d), from the viewpoint of reducing the dispersibility of dispersoids present in the ink by polyvalent metal ions and / or polyvalent amines, thereby exhibiting a good aggregation effect, and from the viewpoint of obtaining high-quality printed matter that combines good dot expandability and excellent image uniformity when using a low-permeability recording medium. When the form of the pigment in the inkjet recording ink is form (d), the form in which the pigment is coated with the water-insoluble resin includes a form in which the water-insoluble resin encapsulates the pigment, a form in which the pigment is uniformly dispersed in the water-insoluble resin, a form in which the pigment is exposed from the surface of the water-insoluble resin particles, a form in which the water-insoluble resin is adsorbed to the pigment, and the like. When the pigment in the inkjet recording ink has the form (d), the pigment is preferably coated with a water-insoluble resin having a crosslinked structure. In the case of coating the pigment with a water-insoluble resin having a crosslinked structure, the water-insoluble resin preferably has a structure containing a polymer component having a linear two-dimensional structure, which may have branched chains, and a component derived from a crosslinking agent. It is believed that such a crosslinked structure is formed by a polymer having a linear two-dimensional structure, which may have branched chains, being converted into a three-dimensional structure by the component derived from the crosslinking agent.

[0056] As described above, the crosslinking degree of the pigment-containing polymer particles, for which the crosslinking reaction is considered to be completed by measuring the pH of the reaction system, may be calculated by the following formula as the theoretical crosslinking degree of the pigment-containing polymer. Theoretical degree of crosslinking of pigment-containing polymer (mol %) = amount of crosslinker added / {functional group equivalent of crosslinker (g / eq.) × number of moles of carboxylic acid of polymer dispersant contained in pigment-containing polymer}

[0057] When the inkjet recording ink is in the form (d), the type of water-insoluble resin used as the pigment dispersing resin for dispersing the pigment is not particularly limited. Specific examples of water-insoluble resins include (meth)acrylic resins, styrene / (meth)acrylic resins, maleic acid resins, styrene / maleic acid resins, urethane resins, and polyester resins. Among these, the water-insoluble resin is preferably at least one selected from the group consisting of (meth)acrylic resins, styrene / (meth)acrylic resins, urethane resins, and polyester resins, and more preferably at least one selected from the group consisting of (meth)acrylic resins and styrene / (meth)acrylic resins, from the viewpoint of reducing the dispersibility of dispersoids present in the ink by polyvalent metal ions derived from polyvalent metal salts or ammonium cations derived from amino groups of polyvalent amines, thereby easily controlling the aggregation effect, and from the viewpoint of obtaining high-quality printed matter that combines good dot expandability and excellent image uniformity when using a low-permeability recording medium. In this specification, "(meth)acrylic" means acrylic or methacrylic. The water-insoluble resin may be synthesized by a known method or may be a commercially available product. The water-insoluble resin may be used alone or in combination of two or more.

[0058] The number average molecular weight of the pigment dispersing resin is preferably 5,000 or more, more preferably 7,000 or more, even more preferably 10,000 or more, and is preferably 100,000 or less, more preferably 50,000 or less, even more preferably 30,000 or less. The number average molecular weight is measured by the method described in the examples. The acid value of the pigment dispersing resin is preferably 5 mgKOH / g or more, more preferably 50 mgKOH / g or more, even more preferably 100 mgKOH / g or more, still more preferably 150 mgKOH / g or more, even more preferably 200 mgKOH / g or more, and is preferably 800 mgKOH / g or less, more preferably 500 mgKOH / g or less, even more preferably 300 mgKOH / g or less. The acid value of the pigment dispersing resin can be determined by the method described in the examples, but can also be calculated from the mass ratio of the constituent monomers.

[0059] [Fixing resin] The inkjet recording ink may contain a resin that functions as a fixing aid (hereinafter also referred to as a "fixing resin"). The fixing resin in the inkjet recording ink is preferably in the form of a resin that does not coat the pigment, and more preferably in the form of resin particles that do not contain a pigment. The fixing resin is not particularly limited and can be appropriately selected depending on the purpose. Specific examples of the fixing resin include urethane resin, polyester resin, acrylic resin, vinyl acetate resin, styrene resin, butadiene resin, styrene / butadiene resin, vinyl chloride resin, styrene / acrylic resin, and acrylic silicone resin. The ink can be obtained by mixing a particulate fixing resin with a colorant, water, an organic solvent, etc. The fixing resin may be a synthesized resin or a commercially available product. The fixing resin may be used alone or in combination of two or more.

[0060] 〔wax〕 The inkjet recording ink may contain a wax. As used herein, "wax" refers to an organic substance that is solid or semi-solid at room temperature (25°C) and becomes liquid when heated. Here, "semi-solid wax" means that the wax deforms and flows when force is applied to it, but can maintain a certain shape when no force is applied to it. Furthermore, the temperature at which wax becomes liquid when heated, known as the melting point of wax, is in the temperature range of 45°C or higher. The wax may be either a natural wax or a synthetic wax. Examples of natural waxes include petroleum waxes such as paraffin wax and microcrystalline wax; vegetable waxes such as carnauba wax, candelilla wax and rice wax; and animal waxes such as lanolin and beeswax. Examples of synthetic waxes include synthetic hydrocarbon waxes such as polyolefin wax and Fischer-Tropsch wax; silicone wax; and modified waxes such as paraffin wax derivatives, montan wax derivatives, and microcrystalline wax derivatives. Among these, polyolefin waxes containing an olefin monomer as the main component are preferred. The waxes can be used alone or in combination of two or more.

[0061] The inkjet recording ink preferably contains wax as a dispersion (hereinafter also referred to as "wax dispersion"). The wax dispersion is not particularly limited, and examples thereof include those prepared by emulsifying wax with a known surfactant, such as a nonionic surfactant or an anionic surfactant. Examples of nonionic surfactants include ethylene oxide adducts of higher alcohols and ethylene oxide adducts of alkylated phenols. Examples of anionic surfactants include sulfates and phosphates based on ethylene oxide adducts of higher alcohols; and alkylated benzenesulfonates. Among these, from the viewpoint of improving the ink ejection stability and the image fastness of printed matter, a nonionic wax dispersion obtained by emulsifying wax with a nonionic surfactant is preferred, and a nonionic polyolefin wax dispersion is more preferred. Suitable examples of commercially available wax dispersions include the "Hi-Tec E" series manufactured by Toho Chemical Industry Co., Ltd., the "AQUACER" series manufactured by BYK, the "Cellosol" series manufactured by Chukyo Yushi Co., Ltd., and the "Chemipearl" series manufactured by Mitsui Chemicals, Inc.

[0062] 〔water〕 The medium for the inkjet recording ink is preferably an aqueous medium, that is, the inkjet recording ink is preferably an aqueous ink containing water. Here, "water-based" means that water accounts for the largest proportion by mass of the ink-jet recording ink medium. It is believed that, since the medium of the inkjet recording ink is an aqueous medium, the aqueous medium contained in the ink is supplied to a recording medium that has been treated with a treatment liquid, and compound (B) that has precipitated on the recording medium is redissolved, making it possible to obtain high-quality printed matter that combines good dot expandability and excellent image uniformity when using a recording medium with low permeability. The water contained in the inkjet recording ink is preferably ion-exchanged water, deionized water, or distilled water. From the viewpoint of environmental friendliness, the water content in the aqueous medium of the inkjet recording ink is preferably 51% by mass or more, more preferably 55% by mass or more, even more preferably 60% by mass or more, still more preferably 65% ​​by mass or more, and is preferably 95% by mass or less, more preferably 90% by mass or less, even more preferably 85% by mass or less, and still more preferably 80% by mass or less.

[0063] [Water-soluble organic solvent] The inkjet recording ink may further contain a water-soluble organic solvent as an aqueous medium. Examples of the water-soluble organic solvent contained in the ink include polyhydric alcohols exemplified as the water-soluble organic solvents used in the treatment liquid; ethers such as polyhydric alcohol alkyl ethers and polyhydric alcohol aryl ethers; nitrogen-containing heterocyclic compounds; amides; amines; and sulfur-containing compounds. Among these, from the viewpoint of obtaining high-quality printed matter that combines good dot expandability and excellent image uniformity, the water-soluble organic solvent is preferably one or more selected from the group consisting of polyhydric alcohols and polyhydric alcohol alkyl ethers, and more preferably a combination of a polyhydric alcohol and a polyhydric alcohol alkyl ether.

[0064] The inkjet recording ink may contain, as necessary, a surfactant, an antifoaming agent, an antiseptic / fungal agent, an antirust agent, a pH adjuster, etc. Examples of the surfactant and pH adjuster include the surfactants and pH adjusters exemplified above for the treatment liquid.

[0065] (Composition of inkjet recording ink) The content of the colorant in the inkjet recording ink is preferably 2% by mass or more, more preferably 3% by mass or more, and even more preferably 4% by mass or more from the viewpoint of improving the image density of the printed matter, and is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less from the viewpoint of obtaining a high-quality printed matter that combines good dot expandability and excellent image uniformity. When the inkjet recording ink contains a pigment dispersing resin, the content of the pigment dispersing resin in the ink is preferably 2% by mass or more, more preferably 4% by mass or more, and even more preferably 6% by mass or more, from the viewpoint of pigment dispersion stability and obtaining high-quality printed matter that combines good dot expandability and excellent image uniformity, and is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less, from the viewpoint of improving the image density of the printed matter. When the inkjet recording ink contains a pigment dispersion resin, the mass ratio of the pigment content to the pigment dispersion resin content in the ink [pigment / pigment dispersion resin] is preferably 0.30 or more, more preferably 0.50 or more, and even more preferably 0.60 or more, from the viewpoint of improving the image density of the printed matter, and is preferably 1.00 or less, more preferably 0.90 or less, and even more preferably 0.80 or less, from the viewpoint of pigment dispersion stability and obtaining high-quality printed matter that combines good dot expandability and excellent image uniformity. When the inkjet recording ink contains a fixing resin, the content of the fixing resin in the ink is preferably 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 1.5% by mass or more, from the viewpoint of obtaining a high-quality printed matter that combines good dot expandability and excellent image uniformity, and is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less, from the viewpoint of improving the image density of the printed matter. When the inkjet recording ink contains wax, the content of wax in the ink is preferably 0.3% by mass or more, more preferably 0.5% by mass or more, even more preferably 0.8% by mass or more, from the viewpoint of obtaining high-quality printed matter that combines good dot expandability and excellent image uniformity, and is preferably 7% by mass or less, more preferably 5% by mass or less, even more preferably 3% by mass or less. When the inkjet recording ink contains a water-soluble organic solvent, the content of the water-soluble organic solvent in the ink is preferably 15% by mass or more, more preferably 20% by mass or more, even more preferably 25% by mass or more, from the viewpoint of obtaining high-quality printed matter that combines good dot expandability and excellent image uniformity, and is preferably 45% by mass or less, more preferably 40% by mass or less, even more preferably 35% by mass or less. When the inkjet recording ink contains a water-soluble organic solvent and a polyhydric alcohol and a polyhydric alcohol alkyl ether are used in combination as the water-soluble organic solvent, the mass ratio of the content of polyhydric alcohol alkyl ethers to the content of polyhydric alcohols in the ink [polyhydric alcohol alkyl ethers / polyhydric alcohols] is preferably 0.1 or more, more preferably 0.2 or more, even more preferably 0.3 or more, and is preferably 0.9 or less, more preferably 0.7 or less, even more preferably 0.5 or less, from the viewpoint of obtaining high-quality printed matter that combines good dot expandability and excellent image uniformity. From the viewpoint of obtaining high-quality printed matter that combines good dot expandability and excellent image uniformity, the water content in the inkjet recording ink is preferably 40% by mass or more, more preferably 45% by mass or more, even more preferably 50% by mass or more, and still more preferably 55% by mass or more, and is preferably 75% by mass or less, more preferably 70% by mass or less, and even more preferably 65% ​​by mass or less.

[0066] [Inkjet recording method] As an inkjet recording method using the treatment liquid of the present invention, a method of forming an image by an inkjet recording system using an ink for inkjet recording on the treated surface of a surface-treated recording medium that has been treated with the treatment liquid is preferred, and a method including the following steps 1 and 2 is more preferred. Step 1: A step of applying a treatment liquid to a recording medium and then heating and drying the recording medium to obtain a surface-treated recording medium. Step 2: A step of forming an image on the treated surface of the surface-treated recording medium obtained in Step 1 by an inkjet recording method using an ink containing a colorant and water.

[0067] (Process 1) Step 1 is a step in which a treatment liquid is applied to a recording medium, and then the recording medium is heated and dried to obtain a surface-treated recording medium. In the present invention, the recording medium used in step 1 may be either a low-permeability recording medium or a high-permeability recording medium, but from the viewpoint of good dot expansion and excellent image uniformity, it is preferable to use a low-permeability recording medium. In the present invention, whether a recording medium has low or high permeability is determined by the amount of water absorbed by the recording medium when the recording medium is in contact with pure water for 100 ms. The amount of water absorbed can be measured as the amount of water transferred when the recording medium is in contact with pure water for 100 ms using an automatic scanning absorption meter (e.g., KM500win manufactured by Kumagai Riki Kogyo Co., Ltd.) under conditions of 23°C and 50% relative humidity. "Low permeability" is a concept that includes low permeability and non-permeability, and has a water absorption of 0 g / m 2 More than 7g / m 2 "High permeability" means that the water absorption is 7g / m or less. 2 It means to be super.

[0068] Examples of low-permeability recording media include low-water-absorbency coated paper and non-water-absorbency resin film. Examples of coated paper include general-purpose glossy paper and multicolor foam gloss paper. The resin film is preferably at least one selected from the group consisting of polyester film, polyvinyl chloride film, polypropylene film, and polyethylene film. These resin films may be surface-treated, such as by corona treatment. An example of a highly permeable recording medium is highly water-absorbent plain paper.

[0069] There are no particular limitations on the method for applying the treatment liquid to the recording medium. Examples of methods for applying the treatment liquid to the recording medium include immersion, roller application, spray application, brush application, and application by inkjet recording. The treatment liquid may be applied to only one side of the recording medium, or to both sides of the recording medium. In the present invention, the side of the recording medium to which the treatment liquid has been applied is referred to as the treated side. Among these, application by a roller is preferred from the viewpoint of being able to apply the treatment liquid simply and uniformly. The roller application method refers to (i) a method in which a treatment liquid is held in the gap between the recording medium and a member that comes into contact with the recording medium, and one of the recording medium and the member that comes into contact with the recording medium is moved, and the treatment liquid applied to a part of the recording medium is spread over the entire recording medium, thereby obtaining a surface-treated recording medium that has been treated with the treatment liquid; or (ii) a method in which the recording medium and a member that is in contact with the recording medium or is close to the recording medium while holding a small gap are rotated, and the treatment liquid is printed onto the recording medium or the treatment liquid held in the small gap is absorbed into the recording medium. Specific examples of rollers used for roller application include offset gravure coaters, gravure coaters, doctor coaters, bar coaters, blade coaters, flexo coaters, and roll coaters. Among these, one or more types selected from the group consisting of doctor coaters, bar coaters, and roll coaters are preferred. Furthermore, from the viewpoint of being able to carry out steps 1 and 2 continuously, the device used to apply the treatment liquid to the recording medium is preferably one that integrates a means for applying the treatment liquid used in step 1, a heat drying means used in step 1, and a means for applying the ink for inkjet recording used in step 2. In this case, for example, a means for applying the treatment liquid, such as a roller coater, may be incorporated into the inkjet recording device described below.

[0070] The amount of treatment liquid applied to the recording medium is preferably 0.2 g / m from the viewpoint of obtaining a high-quality print that combines good dot expansion and excellent image uniformity. 2 More preferably, 0.5 g / m 2 More preferably, 1 g / m 2 From the same viewpoint as above, it is preferably 5 g / m 2 Less than 3g / m, more preferably 2 More preferably, 2 g / m or less 2 The following is the result.

[0071] In step 1, from the viewpoint of obtaining a high-quality printed matter that combines good dot expandability and excellent image uniformity, after the treatment liquid is applied to the recording medium, the treatment liquid on the recording medium may be dried at room temperature before being dried by heating. Examples of room temperature drying methods in step 1 include static drying, air drying, reduced pressure drying, etc. In the recording method of the present invention, application of active energy rays such as ultraviolet rays and radiation is not included in the drying of the present invention. The temperature during room temperature drying in step 1 is preferably 40°C or less, more preferably 35°C or less, and even more preferably 30°C or less, from the viewpoint of suppressing deformation of the recording medium, and is preferably 20°C or more from the viewpoint of drying in a short time. The time for room temperature drying in step 1 is preferably 0.5 minutes or more, more preferably 1 minute or more, even more preferably 3 minutes or more, still more preferably 5 minutes or more, and preferably 30 minutes or less, more preferably 20 minutes or less, even more preferably 15 minutes or less.

[0072] The paper surface temperature during heat drying in step 1 is preferably 70°C or higher, more preferably 80°C or higher, and even more preferably 90°C or higher, from the viewpoint of drying in a short time, and is preferably 125°C or lower, more preferably 115°C or lower, and even more preferably 105°C or lower, from the viewpoint of suppressing deformation of the recording medium. As the paper surface temperature during heat drying in step 1, it is preferable to use the value obtained by measuring the temperature of the treated surface of the surface-treated recording medium with a non-contact thermometer, and the value obtained by measuring the temperature of the heat drying means may also be used. The heat drying time in step 1 is preferably 10 seconds or more, more preferably 20 seconds or more, and even more preferably 30 seconds or more, and from the viewpoint of suppressing deformation of the recording medium and improving the recording speed, it is preferably 180 seconds or less, more preferably 120 seconds or less, and even more preferably 100 seconds or less. Suitable means for heating and drying the surface-treated recording medium include a method of blowing gas adjusted to the above temperature onto the surface-treated recording medium, a method of holding or passing the surface-treated recording medium through a gas atmosphere adjusted to the above temperature, a method of irradiating the treated surface of the surface-treated recording medium with an infrared heater, and a method of heating with a platen heater.

[0073] (Process 2) Step 2 is a step of forming an image on the treated surface of the surface-treated recording medium obtained in step 1 by inkjet recording using an inkjet recording ink. The ink for inkjet recording is loaded into a known inkjet recording apparatus, and is deposited as ink dots on the treated surface of the surface-treated recording medium obtained in step 1, thereby forming an image. Any type of inkjet recording apparatus, such as a thermal type or a piezo type, can be used.

[0074] [Surface treatment recording media] The surface-treated recording medium of the present invention has, on the surface of a low-permeability recording medium, an organic compound (A) and one or more compounds (B) selected from the group consisting of polyvalent metal salts, polyvalent amines, and organic acids. The organic compound (A) is a water-soluble organic compound having a boiling point of 300°C or higher and an HLB value calculated by the Davis method of 6.0 or higher and 10.0 or lower, and examples thereof include the organic compound (A) shown in the above [Inkjet recording treatment liquid]. Furthermore, examples of the polyvalent metal salt, polyvalent amine, and organic acid as the compound (B) include the compound (B) shown in the above [Inkjet recording treatment liquid]. Furthermore, examples of the low-permeability recording medium include the low-permeability recording mediums described above in [Inkjet recording method].

[0075] The amount of the organic compound (A) present on the treated surface of the surface-treated recording medium is preferably 50 mg / m from the viewpoint of obtaining a high-quality print that combines good dot spreadability and excellent image uniformity. 2 or more, more preferably 55 mg / m 2 More preferably, 60 mg / m 2 From the same viewpoint as above, it is preferably 1000 mg / m 2 Less than or equal to 900 mg / m 2 or less, more preferably 800 mg / m 2 The following is the result. The amount of compound (B) present on the treated surface of the surface-treated recording medium is preferably 160 mg / m from the viewpoint of obtaining a high-quality print that combines good dot expansion and excellent image uniformity. 2 More preferably, 170 mg / m 2 or more, more preferably 180 mg / m 2 More preferably, 190 mg / m 2 From the same viewpoint as above, it is preferably 500 mg / m 2 Less than 400 mg / m 2 or less, more preferably 350 mg / m 2 or less, even more preferably 300 mg / m 2 The following is the result.

[0076] The surface-treated recording medium of the present invention can be obtained by the method described in (Step 1) in the above [Inkjet recording method]. [Example]

[0077] In the following Production Examples, Examples and Comparative Examples, "parts" means "parts by mass" unless otherwise specified. Various physical properties were measured or calculated by the following methods.

[0078] (1) Number average molecular weight of pigment dispersing resin The content was determined by gel permeation chromatography. The measurement sample was prepared by mixing 0.1 g of resin with 10 mL of the eluent described below in a glass vial, stirring with a magnetic stirrer at 25°C for 10 hours, and filtering with a syringe filter "DISMIC-13HP" (PTFE, 0.2 μm, manufactured by Advantec Co., Ltd.). The measurement conditions are shown below. GPC equipment: Tosoh Corporation "HLC-8320GPC" Columns: "TSKgel SuperAWM-H", "TSKgel SuperAW3000", and "TSKgel guardcolumn Super AW-H" manufactured by Tosoh Corporation Eluent: N,N-dimethylformamide dissolved with phosphoric acid and lithium bromide at concentrations of 60mmol / L and 50mmol / L, respectively. Flow rate: 0.5mL / min Standard material: Monodisperse polystyrene kits with known molecular weights manufactured by Tosoh Corporation: "PStQuick b (F-550, F-80, F-10, F-1, a-1000)" and "PStQuick c (F-288, F-40, F-4, A-5000, A-500)"

[0079] (2) Acid value of pigment dispersing resin The pigment dispersion resin was dissolved in a titration solvent (toluene:acetone = 2:1 (volume ratio)) mixed with toluene and acetone in an automatic potentiometric titrator (Kyoto Electronics Manufacturing Co., Ltd., electric burette, model number: APB-610), and titrated with a 0.1 N potassium hydroxide / ethanol solution by potentiometric titration, with the inflection point on the titration curve being the endpoint. The acid value (mg KOH / g) of the pigment dispersion resin was calculated from the titration amount up to the endpoint of the potassium hydroxide solution.

[0080] (3) Solids concentration of pigment dispersion and wax dispersion A 30 mL polypropylene container (φ: 40 mm, height: 30 mm) was precisely weighed, and approximately 10.0 g of sodium sulfate (reagent, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was weighed into the container and kept at a constant weight in a desiccator. The mass of the sodium sulfate was then precisely weighed. Approximately 1 g of pigment dispersion or wax dispersion was added and mixed thereto, and the mass of the pigment dispersion or wax dispersion was then precisely weighed. The container was then maintained at 105°C for 2 hours to remove volatiles, and the container was then left in the desiccator for an additional 15 minutes before the entire container was precisely weighed. The mass of the pigment dispersion or wax dispersion residue after devolatilization was calculated by subtracting the precisely weighed mass of the container and the precisely weighed mass of the sodium sulfate from the precisely weighed mass of the entire container. The mass of the pigment dispersion or wax dispersion residue after devolatilization was divided by the mass of the pigment dispersion or wax dispersion before devolatilization to obtain the solids concentration (% by mass).

[0081] (4) Melting point of wax The melting point of the wax was measured using an apparatus conforming to JIS K 0064. Specifically, the wax dispersion was dried and used as a sample. The sample was heated to 200°C using a differential scanning calorimeter "DSC Q20" (manufactured by TA Instruments) and then cooled to 0°C at a rate of 10°C / min. The sample was then heated at a rate of 10°C / min, and the calorific value was measured up to 200°C. The temperature of the peak with the largest peak area among the observed heat of fusion peaks was determined as the maximum peak temperature of melting, and this peak temperature was taken as the melting point of the wax.

[0082] (5) Average particle size of pigment dispersion Using a laser particle analysis system "ELS-8000" (Otsuka Electronics Co., Ltd.), particle size was measured by dynamic light scattering and calculated by cumulant analysis. The measurement conditions were a temperature of 25°C, an angle between the incident light and the detector of 90°, and 100 integration times. The refractive index of water (1.333) was input as the refractive index of the dispersion solvent. For the measurement sample, a pigment dispersion was weighed into a screw tube (Maruem Co., Ltd., No. 5) and the solids concentration was 2 × 10 -4Water was added to make the concentration 5% by mass, and the mixture was stirred at 25°C for 1 hour using a magnetic stirrer.

[0083] (6) Viscosity of the treatment liquid The viscosity of the treatment liquid at 25° C. was measured using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., model number: TV-25, using a standard cone rotor 1°34′×R24, rotation speed 50 rpm).

[0084] (7) Measurement of pH of treatment solution The pH of the treatment solution at 20° C. was measured using a tabletop pH meter (Horiba Ltd., "F-71") equipped with a pH electrode (Horiba Ltd., "6337-10D").

[0085] Production Example 1 (Production of pigment dispersion resin) A monomer mixture was prepared by mixing 31 parts of acrylic acid (a reagent manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 69 parts of styrene (a reagent manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.). Into a reaction vessel, 10 parts of methyl ethyl ketone (hereinafter also referred to as "MEK") (a reagent manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 0.2 parts of a polymerization chain transfer agent (2-mercaptoethanol) (a reagent manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 10 mass % of the monomer mixture were placed and mixed, and the atmosphere was thoroughly replaced with nitrogen gas. Separately, a mixture of the remaining 90% by mass of the monomer mixture, 0.13 parts of the polymerization chain transfer agent, 30 parts of MEK, and 1.1 parts of a radical polymerization initiator (2,2'-azobis(2,4-dimethylvaleronitrile), manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., product name "V-65") was placed in a dropping funnel. The monomer mixture in the reaction vessel was heated to 65°C with stirring under a nitrogen atmosphere, and the mixture in the dropping funnel was added dropwise over 3 hours. After 2 hours at 65°C from the end of the dropping, a solution of 0.1 parts of the polymerization initiator in 2 parts of MEK was added, and the mixture was further aged at 65°C for 2 hours and then at 70°C for 2 hours, followed by drying under reduced pressure to obtain an acrylic acid / styrene copolymer (number average molecular weight: 19,000, acid value: 240 mgKOH / g) as a pigment dispersion resin.

[0086] Production Example 2-1 (Production of cyan ink I-C1 for inkjet recording) 100 parts of the pigment dispersion resin obtained in Production Example 1-1 and 78.6 parts of MEK were mixed, and 41.2 parts of a 5N aqueous sodium hydroxide solution (volumetric analysis grade, sodium hydroxide content: 16.9% by mass, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as a neutralizer to neutralize (degree of neutralization: 40 mol%). Next, 800 parts of ion-exchanged water was added, followed by 100 parts of a cyan pigment (CI Pigment Blue 15:3, manufactured by DIC Corporation, product name "TGR-SD"), and the mixture was stirred at 20°C for 60 minutes using a Disper (manufactured by Asada Iron Works Co., Ltd., product name "Ultra Disper") with a Disper blade rotating at 7,000 rpm to obtain a pigment mixture. The resulting pigment mixture was subjected to a dispersion treatment using a Microfluidizer (trade name, manufactured by Microfluidics) at a pressure of 200 MPa for 10 passes to obtain a cyan pigment dispersion. To the obtained cyan pigment dispersion, 250 parts of ion-exchanged water was added and the mixture was stirred. After that, the MEK was completely removed at 60°C under reduced pressure. After further removing some of the water, 35.7 parts of trimethylolpropane polyglycidyl ether (manufactured by Nagase ChemteX Corporation, trade name "Denacol EX-321", epoxy equivalent: 140) was added as a crosslinking agent, the mixture was sealed, and heated at 70°C for 5 hours while stirring with a stirrer. The mixture was then cooled to room temperature, and ion-exchanged water was added to adjust the solids concentration to 24% by mass. The mixture was then filtered through a 5 μm pore size filter (acetyl cellulose membrane, outer diameter: 2.5 cm, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) to obtain a cyan pigment dispersion (crosslinking rate 60 mol%, average particle size: 102 nm). 50 parts of the obtained cyan pigment dispersion, 2.9 parts of a polyethylene wax dispersion (manufactured by Toho Chemical Industry Co., Ltd., trade name "Hitec E-6500", ion type: nonionic, wax melting point: 140°C, solid content concentration: 35% by mass), 19 parts of 1,2-propanediol (reagent manufactured by Fujifilm Wako Pure Chemical Industries Co., Ltd.), 8 parts of ethylene glycol monobutyl ether (reagent manufactured by Fujifilm Wako Pure Chemical Industries Co., Ltd.), and 2,4,7,9-tetramethyl-5-decyne-4,7-diol (Air Products and The resulting mixture was mixed with 0.5 parts of a cellulose acetate solution (trade name "Surfynol 104" manufactured by Fujifilm Chemicals Co., Ltd.), ion-exchanged water was added so that the total amount became 100 parts, and the mixture was filtered through a filter with a pore size of 5 μm (acetyl cellulose membrane, outer diameter: 2.5 cm, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) to obtain a cyan ink for inkjet recording I-C1 (solids concentration: 13 mass %, pigment content: 5 mass %, pigment dispersing resin content: 7 mass %, wax content: 1 mass %).

[0087] Production Example 2-2 (Production of cyan ink I-C2 for inkjet recording) A cyan ink for inkjet recording I-C2 was obtained in the same manner as in Production Example 2-1, except that 19 parts of dipropylene glycol (a reagent manufactured by Tokyo Chemical Industry Co., Ltd.) and 8 parts of 1,2-hexanediol (a reagent manufactured by Tokyo Chemical Industry Co., Ltd.) were used instead of 1,2-propanediol and ethylene glycol monobutyl ether.

[0088] Production Example 2-3 (Production of magenta ink I-M1 for inkjet recording) Inkjet recording magenta ink I-M1 was obtained in the same manner as in Production Example 2-1, except that a magenta pigment (CI Pigment Red 122, manufactured by DIC Corporation, trade name "FASTOGEN Super Magenta RGT") was used instead of the cyan pigment.

[0089] Production Example 2-4 (Production of magenta ink I-M2 for inkjet recording) Inkjet recording magenta ink I-M2 was obtained in the same manner as in Production Example 2-2, except that a magenta pigment (CI Pigment Red 122, manufactured by DIC Corporation, trade name "FASTOGEN Super Magenta RGT") was used instead of the cyan pigment.

[0090] Examples 1 to 13 and Comparative Examples 1 to 4 (Preparation of Treatment Solutions 1 to 13 and Treatment Solutions C1 to C4) Each component of the treatment solution was added to a container equipped with a stirrer according to the formulation shown in Table 1, and mixed at 25°C for 1 hour. The mixture was then filtered using a 25 mL needleless syringe (manufactured by Terumo Corporation) fitted with a 5 μm pore size filter (acetyl cellulose membrane, outer diameter: 2.5 cm, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) to obtain a treatment solution. The viscosity of treatment liquid 1 at 25°C was 5.6 mPa·s, and the pH at 20°C was 5.1. The notations in Table 1 have the following meanings: <Organic compounds (A)> Polyethylene glycol phenyl ether (manufactured by Aoki Oil & Fat Industries Co., Ltd., product name "Brownon PH-5", EO moles added: 5, HLB value: 8.2, boiling point: 435°C) 1,2,10-Decanetriol (reagent manufactured by Tokyo Chemical Industry Co., Ltd., HLB value: 8.0, boiling point: 336°C) 1,2,9-nonanetriol (reagent manufactured by Tokyo Chemical Industry Co., Ltd., HLB value: 8.4, boiling point: 327°C) 1,2,7-Heptanetriol (reagent manufactured by Tokyo Chemical Industry Co., Ltd., HLB value: 9.4, boiling point: 324°C) Diethylene glycol monobenzyl ether (manufactured by Nippon Nyukazai Co., Ltd., product name "Benzyl Diglycol", HLB value: 6.7, boiling point: 324°C) <Compound (A')> 1,4-Cyclohexanedimethanol (Eastman Chemical, HLB value: 7.0, boiling point: 285°C) Tricyclodecane dimethanol (tricyclo[5.2.1.0(2,6)]decane dimethanol, manufactured by OQ Chemicals, HLB value: 5.1, boiling point: 335°C) 1,2,4-Butanetriol (reagent manufactured by Tokyo Chemical Industry Co., Ltd., HLB value: 10.8, boiling point: 312°C) <Compound (B)> [Polyvalent metal salts] ·Mg(NO3)2·6H2O (magnesium nitrate hexahydrate, Tokyo Chemical Industry Co., Ltd., reagent) ·Ca(NO3)2·4H2O (calcium nitrate tetrahydrate, Tokyo Chemical Industry Co., Ltd., reagent) ·Al(NO3)3·9H2O (aluminum nitrate nonahydrate, Tokyo Chemical Industry Co., Ltd., reagent) [Polyamine] PAS-H-1L (aqueous solution of polydiallyldimethylammonium chloride, solid content 28% by mass, manufactured by Nittobo Medical Co., Ltd., product name, weight-average molecular weight: 8,500 (catalog value)) Unisense KHE-107L (aqueous solution of dimethylamine / epichlorohydrin copolymer, solid content 52% by mass, Senka Corporation, product name, molecular weight converted to PEG by GPC: less than 20,000 (catalog value)) [Organic acid salt] NH4(C2H4(OH)COO)(40% by mass aq) (ammonium lactate aqueous solution, active ingredient 40% by mass, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) (pH adjuster) Triethanolamine (Nippon Shokubai Co., Ltd., reagent)

[0091] (Step 1: Manufacturing of surface-treated recording medium) A wireless bar coater "A-Bar" (Mitsui Electric Seiki Co., Ltd., model: OSP-1.5, pitch: 0.08 mm, depth: 4 μm, film thickness: 1.5 μm / wet) was used, and coated paper "OK ​​Topcoat+" (Oji Paper Co., Ltd., basis weight: 127.9 g / m) was used as a low-permeability recording medium. 2 , Pure water absorption amount at contact time of 100 msec: 4.9 g / m 2 ) with a treatment solution applied at a rate of 1.6±0.3g / m 2After uniformly applying the coating so that the coating was as shown in the figure, the coating was left to stand in an environment of 25°C and 50% RH for 10 minutes, followed by drying at room temperature, to obtain an undried surface-treated recording medium. The resulting undried surface-treated recording medium was heated and dried for 60 seconds in a thermostatic chamber heated to 100° C. to obtain a surface-treated recording medium.

[0092] (Process 2: Production of printed matter) On the treated surface of the surface-treated recording medium obtained in step 1, an image was formed by inkjet recording using the inks shown in Table 1 according to the methods described below in "(1) Evaluation of dot expandability" and "(2) Evaluation of image uniformity."

[0093] <Evaluation> (1) Evaluation of dot scalability In an environment of 25±1°C temperature and 30±5% relative humidity, a printing evaluation device (manufactured by Tritec Corporation) equipped with an inkjet head "KJ4B-HD06MHG-STDV" (manufactured by Kyocera Corporation, piezo type) was filled with the cyan ink for inkjet recording shown in Table 1. The head voltage was set to 26 V, the frequency to 20 kHz, the ejection liquid volume to 12 pL, the head temperature to 32°C, the resolution to 600 dpi, and the negative pressure to -4.0 kPa. The surface-treated recording medium was fixed to the conveying table under reduced pressure, with the longitudinal direction of the surface-treated recording medium aligned with the conveying direction. A print command was sent to the print evaluation device, and an image was printed at a duty factor of 2%. The ink dot diameter was measured using a handheld image evaluation system "PIAS (registered trademark)-II" (manufactured by Quality Engineering Associates (QEA)) under conditions of a threshold of 50%, a minimum dot diameter of 10 μm, and a maximum dot diameter of 100 μm. The results are shown in Table 1. Larger dot diameters indicate better dot expandability and image quality; a dot diameter of 55 μm or greater is practically acceptable.

[0094] In the evaluation of the dot spreadability, an image was printed in the same manner as above, except that the surface-treated recording medium was replaced with the undried surface-treated recording medium obtained in step 1, and the ink dot diameter was measured under the same conditions. The results are shown in Table 1.

[0095] (2) Evaluation of image uniformity In an environment of a temperature of 25±1°C and a relative humidity of 30±5%, a printing evaluation device (manufactured by Tritec Corporation) equipped with an inkjet head "KJ4B-HD06MHG-STDV" (manufactured by Kyocera Corporation, piezo type) was filled with the cyan ink for inkjet recording and the magenta ink for inkjet recording shown in Table 1. The head voltage was set to 26 V, the frequency to 20 kHz, the amount of ejected liquid to be 12 pL, the head temperature to 32°C, the resolution to 600 dpi, and the negative pressure to -4.0 kPa. The surface-treated recording medium was fixed to the conveying table under reduced pressure so that the longitudinal direction of the surface-treated recording medium was the same as the conveying direction. A print command was transferred to the print evaluation device, and an image was printed using inkjet cyan ink and inkjet magenta ink at a duty of 60% each, for a total duty of 120%, and the L of the printed part of the image was measured using a handheld image evaluation system "PIAS (registered trademark)-II" (manufactured by Quality Engineering Associates (QEA)). * The graininess value was measured and the image uniformity was evaluated according to the following evaluation criteria. The results are shown in Table 1. * The smaller the graininess value, the less color mixing between dots there is, resulting in better image quality. * If the graininess value is less than 3.0, there is no practical problem.

[0096] [Table 1]

[0097] From Table 1, it can be seen that, compared to Comparative Examples 1 to 4, Examples 1 to 13 can produce high-quality prints that combine good dot expansion and image uniformity when printing on a low-permeability recording medium, even when a heat drying process is performed after applying the treatment liquid. In particular, in Comparative Example 2, the dot spreadability on the undried surface-treated recording medium was good, but the dot spreadability on the dried surface-treated recording medium was inferior to that of Examples. This is thought to be because the boiling point of 1,4-cyclohexanedimethanol used in place of organic compound (A) was as low as 285°C, and therefore volatilized during drying. [Industrial Applicability]

[0098] According to the present invention, it is possible to provide a treatment liquid for inkjet recording, an ink set for inkjet recording, a surface-treated recording medium, and an inkjet recording method that are capable of obtaining high-quality printed matter that combines good dot expandability and excellent image uniformity, even when a heat drying step is performed after the treatment liquid is applied to a low-permeability recording medium. Therefore, the inkjet recording treatment liquid of the present invention can be suitably used for treating low-permeability printing substrates in printing using conventional water-based inks for inkjet printing.

Claims

1. organic compound (A), (B) one or more compounds selected from the group consisting of polyvalent metal salts, polyvalent amines, and organic acids; and Contains water, the organic compound (A) is a water-soluble organic compound having a boiling point of 300°C or higher and an HLB value calculated by the Davis method of 6.0 or higher and 10.0 or lower, The compound (B) does not contain the organic compound (A), The treatment liquid for inkjet recording has a content of the organic compound (A) of 3% by mass or more.

2. 2. The inkjet recording treatment liquid according to claim 1, wherein the polyvalent metal ions constituting the polyvalent metal salt are divalent or trivalent metal ions.

3. The inkjet recording treatment liquid according to claim 1, wherein the polyamine is a polymer containing a structural unit derived from a polymerizable monomer having at least one amino group.

4. The treatment liquid for inkjet recording according to any one of claims 1 to 3, wherein the organic compound (A) is at least one compound selected from the group consisting of polyethylene glycol ether compounds having an aromatic ring and alkanetriol compounds.

5. 4. The treatment liquid for inkjet recording according to claim 1, wherein the content of the organic compound (A) is 60% by mass or less.

6. 4. The treatment liquid for inkjet recording according to claim 1, wherein the content of the compound (B) is 3% by mass or more and 40% by mass or less.

7. The inkjet recording treatment liquid according to any one of claims 1 to 3, which is used for pretreatment of a recording medium used in inkjet recording.

8. An ink set for inkjet recording, comprising the inkjet recording treatment liquid according to any one of claims 1 to 3, and an inkjet recording ink containing a colorant and water.

9. A low-permeability recording medium has, on its surface, an organic compound (A) and one or more compounds (B) selected from the group consisting of polyvalent metal salts, polyvalent amines, and organic acids; The surface-treated recording medium, wherein the organic compound (A) is a water-soluble organic compound having a boiling point of 300° C. or higher and an HLB value calculated by the Davis method of 6.0 or higher and 10.0 or lower.

10. An inkjet recording method comprising the following steps 1 and 2: Step 1: A step of applying the inkjet recording treatment liquid according to any one of claims 1 to 3 to a recording medium, and then heating and drying the applied liquid to obtain a surface-treated recording medium. Step 2: A step of forming an image on the treated surface of the surface-treated recording medium obtained in Step 1 by an inkjet recording method using an ink containing a colorant and water.

Images