Pretreatment liquid, ink set and printed matter

Abstract

To provide a pretreatment liquid used together with an aqueous ink-jet ink, capable of obtaining a printed matter excellent in printing image quality, excellent even in initial discharge stability and continuous discharge stability, and excellent even in blend stability during manufacturing, and preferably excellent even in scratch resistance of the printed matter in addition to the above-mentioned effects.SOLUTION: A pretreatment liquid used together with aqueous ink-jet ink includes a flocculant, a resin, a water-soluble organic solvent and water. The resin includes a nonionic resin (R); the water-soluble organic solvent includes a water-soluble organic solvent (S1) having an octanol / water partition coefficient of -1.60 or more to less than -0.20 and a water-soluble organic solvent (S2) having an octanol / water partition coefficient of -0.20 to 1.00; and the ratio of the content of the nonionic resin (R) to the content of the water-soluble organic solvent (S2) is specified.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a pretreatment liquid, an ink set containing the pretreatment liquid, and a printed matter produced using the ink set. [Background technology]

[0002] Inkjet printing is a method of ejecting and depositing ink droplets from minute nozzles onto a substrate to produce printed matter bearing characters and / or images. The term "image" includes solid images (images printed at 100% coverage, covering the entire surface of the substrate) and seamless images such as checkerboard patterns. Compared to conventional plate-based printing methods such as offset printing and gravure printing, inkjet printing offers advantages such as the ability to downsize printing equipment, ease of colorization, and print quality that is less susceptible to the printing environment. As a result, inkjet printing is increasingly being used not only in offices and homes but also in industrial applications. While traditional inks used in inkjet printing in industrial applications have been solvent-based or UV-curable, there is growing demand for water-based inks, primarily due to concerns about the safety and health of printing personnel.

[0003] Furthermore, in recent years, when printing aqueous inks by inkjet printing on low-permeability substrates such as coated paper, art paper, and lightly coated paper, and non-permeable substrates such as plastic substrates, a pretreatment liquid has been used to improve print quality (see, for example, Patent Documents 1 and 2). Examples of the "improvement of print quality" include preventing whiteout (a phenomenon in which the substrate surface is exposed due to poor ink wetting and spreading in printed materials with high coverage) and color bleeding. The pretreatment liquid also contains a component (a flocculant) that can intentionally cause the aggregation of solid components (pigments and / or resins) present in the aqueous inkjet ink or thicken the ink. The addition of a resin different from the flocculant can also improve the properties of the printed material, such as improving abrasion resistance and providing adhesion to the substrate.

[0004] On the other hand, non-contact printing methods, such as inkjet printing, have been considered as methods for applying a pretreatment liquid used with aqueous inkjet ink, because the amount of pretreatment liquid applied can be controlled according to the coverage rate of the aqueous inkjet ink, making it easy to adjust the print image quality and allowing the printing apparatus to be made more compact. However, the pretreatment liquid applied by inkjet printing must have printability from an inkjet head, as exemplified by ejection stability, in addition to the ability to aggregate solid components in the aqueous inkjet ink, the ability to thicken the aqueous inkjet ink, and abrasion resistance. Therefore, formulating a pretreatment liquid applied by inkjet printing is extremely difficult. Furthermore, because aggregating agents are generally often cationic components, it can be said that it is extremely difficult to produce a pretreatment liquid containing the aggregating agent and an anionic component (e.g., an anionic resin).

[0005] For example, Patent Document 3 discloses a water-based primer ink (aqueous pretreatment liquid) containing a water-soluble resin having cationic properties as an aggregating agent and a nonionic thickener (a resin having a thickening effect) such as a polyether polyol urethane resin. However, when the present inventors evaluated the pretreatment liquid specifically disclosed in the examples of Patent Document 3, they found that the ejection stability may not be good depending on the type of inkjet head and printing conditions.

[0006] Furthermore, Patent Document 4 discloses a liquid composition for surface treatment (pretreatment liquid) that contains nonionic resin particles and a polyvalent metal salt and specifies the contact angle of water with a film formed on a printing substrate. However, evaluation of the pretreatment liquid specifically disclosed in the examples of Patent Document 4 revealed that the continuous ejection stability may not be good depending on the printing conditions, such as the occurrence of nozzle clogging (a phenomenon in which the aqueous inkjet ink is not ejected from the nozzle) during continuous ejection.

[0007] As described above, it can be said that there has not yet been sufficient research into a pretreatment liquid that is applied in an inkjet printing method and used together with an aqueous inkjet ink, that gives printed matter with excellent print quality, that has excellent ejection stability at the beginning of printing and continuous ejection stability, and that also has good blending stability during production. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-276253 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-56884 [Patent Document 3] Japanese Patent Application Publication No. 2019-143058 [Patent Document 4] Patent Publication No. 2021-790 Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a pretreatment liquid to be used with an aqueous inkjet ink, which can produce printed matter with excellent print quality, has excellent ejection stability at the beginning of printing and continuous ejection stability, and has good blending stability during production. Another object of the present invention is to provide a pretreatment liquid which, in addition to the above-mentioned effects, also has excellent abrasion resistance of printed matter. Another object of the present invention is to provide an ink set that includes a pretreatment liquid having the above-mentioned effects and an aqueous inkjet ink, and that can produce printed matter with excellent print quality even when printing at high speed. [Means for solving the problem]

[0010] As a result of extensive research, the present inventors have found that the above-mentioned problems can be solved by a pretreatment liquid and ink set having the following compositions, and have thus completed the present invention.

[0011] That is, the present invention relates to a pretreatment liquid as described in [1] to [5] below, an ink set as described in [6] below, and a printed matter produced using the ink set as described in [7] below. [1] A pretreatment liquid used together with an aqueous inkjet ink, the pretreatment liquid comprising a flocculant, a resin (excluding cationic resins), a water-soluble organic solvent, and water, The resin contains a nonionic resin (R), the water-soluble organic solvent comprises a water-soluble organic solvent (S1) having an octanol / water partition coefficient of −1.60 or more but less than −0.20, and a water-soluble organic solvent (S2) having an octanol / water partition coefficient of −0.20 to 1.00; The pretreatment liquid has a value of 0.03 to 10, where WR (g) is the content of the nonionic resin (R) and WS2 is the content of the water-soluble organic solvent (S2) contained in 100 g of the pretreatment liquid. [2] The pretreatment liquid according to [1], wherein the ratio of the mass content of the water-soluble organic solvent (S2) to the total mass content of the water-soluble organic solvent (S1) and the water-soluble organic solvent (S2) is 0.05 to 0.5. [3] The pretreatment liquid according to [1] or [2], wherein the nonionic resin (R) is a water-soluble resin. [4] further comprising a crosslinking agent, The pretreatment liquid according to any one of [1] to [3], wherein the crosslinking agent contains a polyhydrazide compound. [5] The pretreatment liquid according to any one of [1] to [4], which is used in an inkjet printing method. [6] An ink set comprising the pretreatment liquid according to any one of [1] to [5] and an aqueous inkjet ink containing a pigment, a water-soluble organic solvent, and water. [7] A printed matter obtained by printing the ink set according to [6] on a printing substrate. [Effects of the Invention]

[0012]

[0013] The present invention makes it possible to provide a pretreatment liquid to be used with an aqueous inkjet ink, which can produce printed matter with excellent print quality, has excellent ejection stability at the beginning of printing and continuous ejection stability, and has good blending stability during production. Furthermore, the present invention makes it possible to provide a pretreatment liquid to be used with an aqueous inkjet ink, which can produce printed matter with excellent print quality, has excellent ejection stability at the beginning of printing and continuous ejection stability, and has good blending stability during production. In addition to the above-mentioned effects, the present invention makes it possible to provide a pretreatment liquid to be used with an aqueous inkjet ink, which can produce printed matter with excellent scratch resistance. Furthermore, the present invention makes it possible to provide an ink set comprising the pretreatment liquid and an aqueous inkjet ink, which has the above-mentioned effects and is capable of producing printed matter with good print quality, even when printing at high speed in particular. DETAILED DESCRIPTION OF THE INVENTION

[0013] Preferred embodiments of the present invention will be described below. Note that the present invention is not limited to the following embodiments, and includes various modifications that are implemented within the scope of the invention.

[0014] Generally, when printing aqueous inkjet inks onto printing substrates with low permeability, such as coated paper or film, using inkjet printing methods, the droplets of the aqueous ink that land on the printing substrate tend to mix together, resulting in a degradation of print quality. One known solution to this problem is to use a pretreatment liquid containing a flocculant in combination with the aqueous inkjet ink. Specifically, the pretreatment liquid is applied to the printing substrate in advance, and the aqueous inkjet ink is printed on a layer (pretreatment layer) formed by the pretreatment liquid. In this way, the flocculant present in the pretreatment layer disrupts the dispersion of solid components contained in the aqueous inkjet ink and / or rapidly thickens the aqueous inkjet ink. As a result, the droplets of the aqueous inkjet ink are prevented from mixing together, improving print quality.

[0015] When a pretreatment liquid is printed on a printing substrate using an inkjet printing method, if the viscosity of the pretreatment liquid is too low, the viscosity falls below the viscosity range at which the pretreatment liquid can be ejected from an inkjet head, making it impossible to print the pretreatment liquid on the printing substrate. One method for imparting viscosity to a pretreatment liquid is to add a resin to the pretreatment liquid. In this case, to make the pretreatment liquid ejectable from an inkjet head, the resin must be stable even in the presence of a flocculant. From this perspective, it is preferable to use a resin that does not have ionic properties (a nonionic resin) as the resin. Furthermore, although the detailed mechanism is unknown, using a pretreatment liquid containing a nonionic resin and a flocculant can further improve the print quality of printed materials. Furthermore, using a nonionic resin improves blend stability during production, even when the pretreatment liquid contains a flocculant.

[0016] On the other hand, nonionic resins have the property that hydrophobic segments associate with each other due to hydrophobic interactions (association forces). This association force imparts an appropriate viscosity to a pretreatment liquid containing the nonionic resin, enabling it to be ejected from an inkjet head. However, if the association force becomes too strong, the nonionic resins may aggregate with each other. Furthermore, if strong association forces act between nonionic resins, the viscoelasticity of the pretreatment liquid may become too high, causing problems such as the pretreatment liquid not being ejected at the start of printing or difficulty in continuous ejection. Furthermore, during the production of the pretreatment liquid, the aggregated nonionic resin may appear as precipitation or turbidity.

[0017] Therefore, in the present invention, a predetermined amount of a water-soluble organic solvent (S2) having an octanol / water partition coefficient of -0.20 to 1.00 is blended with the nonionic resin (R). It is presumed that the relatively highly hydrophobic water-soluble organic solvent (S2) acts on the association sites of the hydrophobic segments in the nonionic resin (R), loosening the association sites appropriately and suppressing an increase in viscoelasticity, thereby improving initial ejection stability, continuous ejection stability, and blending stability during production. In particular, when the content of the nonionic resin (R) in 100 g of the pretreatment liquid is defined as WR (g) and the content of the water-soluble organic solvent (S2) is defined as WS2, by setting the value expressed by WR / WS2 to 0.03 or more, the effects of the water-soluble organic solvent (S2) described above are fully manifested, improving initial ejection stability, continuous ejection stability, and blending stability during production. Furthermore, by setting the ratio to 10 or less, the associated portions are not excessively loosened by the water-soluble organic solvent (S2), and the pretreatment liquid has suitable viscoelasticity, thereby realizing continuous and stable discharge.

[0018] On the other hand, as described above, the water-soluble organic solvent (S2) is highly hydrophobic, and therefore has low affinity with water and hydrophilic materials such as aggregating agents present in the pretreatment liquid, and may not be uniformly present in the pretreatment liquid. In such cases, the above-described effects are only exhibited to a limited extent within the pretreatment liquid, and there is a risk that the initial ejection stability and continuous ejection stability will not be sufficiently improved. Furthermore, when the water in the pretreatment liquid dries near the nozzles of the inkjet head, the presence ratio of the water-soluble organic solvent (S2) increases, which may cause the hydrophilic material to precipitate, thereby deteriorating the continuous ejection stability.

[0019] Therefore, in the present invention, a water-soluble organic solvent (S1) having a high affinity with water and an octanol / water partition coefficient of −1.60 or more and less than −0.20 is blended into the pretreatment liquid. This allows the affinity between the water-soluble organic solvent (S2) and the water and hydrophilic material to be maintained. As a result, even if a portion of the water in the pretreatment liquid evaporates, precipitation of the hydrophilic material does not occur, and the pretreatment liquid can be stably ejected. Furthermore, the favorable affinity of the above-mentioned materials further improves the blending stability when producing the pretreatment liquid.

[0020] Furthermore, the affinity-enhancing effect of the water-soluble organic solvent (S1) allows the hydrophilic flocculant to be uniformly distributed in the pretreatment liquid, which is mainly composed of water, and as a result, the action of the flocculant is not unevenly expressed in the pretreatment layer, making it possible to obtain printed matter with excellent print quality.

[0021] If only the water-soluble organic solvent (S1) is used without the water-soluble organic solvent (S2), the highly hydrophilic water-soluble organic solvent (S1) cannot act on the association sites of the hydrophobic segments of the nonionic resin (R), making it difficult to improve the initial and continuous ejection stability. On the other hand, if a water-soluble organic solvent with an octanol / water partition coefficient of more than 1.00 is used, the association sites of the hydrophobic segments of the nonionic resin (R) will be excessively loosened, making it difficult to ensure the initial and continuous ejection stability, and also worsening the blending stability when producing the pretreatment liquid.

[0022] As described above, in order to simultaneously and at a high level achieve the desired print quality of the printed matter, the initial ejection stability, the continuous ejection stability, and the blending stability during production, a pretreatment liquid that is used together with the aqueous inkjet ink having the configuration of the present invention is essential.

[0023] Next, each component constituting the pretreatment liquid (hereinafter simply referred to as "the pretreatment liquid of this embodiment") used together with the aqueous inkjet ink, which is an embodiment of the present invention, will be described in detail below.

[0024] <Flocculant> The pretreatment liquid of this embodiment contains a flocculant. Furthermore, from the viewpoint of simultaneously achieving continuous ejection stability, print image quality, and blending stability during production, the flocculant preferably contains at least one selected from the group consisting of polyvalent metal salts and cationic resins. As described above, this can disrupt the dispersion state of solid components contained in the aqueous inkjet ink and / or rapidly thicken the aqueous inkjet ink, thereby improving the print image quality of the resulting printed matter.

[0025] (polyvalent metal salts) When the pretreatment liquid of this embodiment contains a polyvalent metal salt as an aggregating agent, the combination of polyvalent metal ions and counter anions constituting the polyvalent metal salt is not particularly limited, and any combination of conventionally known ions can be used. Among these, polyvalent metal salts composed of divalent metal ions are preferred because they provide an excellent balance between the ability to disrupt the dispersion state of solid components in the aqueous inkjet ink and / or the ability to thicken the aqueous inkjet ink, and the wetting and spreading properties of the aqueous inkjet ink droplets. This allows for the production of printed materials with excellent print quality, free of whiteout and color bleeding, regardless of the type of image to be printed, even at high speeds. Examples of divalent metal ions that can be used include calcium ions, magnesium ions, zinc(II) ions, and iron(II) ions. Among these, calcium ions are particularly preferred because they provide printed materials with exceptional print quality, free of whiteout and color bleeding.

[0026] On the other hand, when calcium ions are selected as the polyvalent metal ions, examples of counter anions include chloride ions (75 g), nitrate ions (121 g), permanganate ions (338 g), formate ions (17 g), acetate ions (28 g), propionate ions (38 g), butyrate ions (17 g), benzoate ions (2 g), lactate ions (9 g), malate ions (0.8 g), gluconate ions (3 g), pantothenate ions (35 g), and hydroxide ions (0.1 g). The values ​​in parentheses are the solubility of anhydrous calcium salts in 100 g of water at 20°C.

[0027] When an aqueous inkjet ink is printed onto a dried pretreatment layer, the redissolution and release rate into droplets of the aqueous inkjet ink is not too high, improving the print quality of the printed matter, and furthermore, from the viewpoint of obtaining a printed matter with excellent abrasion resistance and adhesion, when the pretreatment liquid of this embodiment contains a polyvalent metal salt as an aggregating agent, it is preferable to use a polyvalent metal salt having a solubility of 1 to 70 g in 100 g of water at 20° C., more preferably 2 to 55 g, still more preferably 4 to 40 g, and particularly preferably 8 to 25 g. However, the above solubility is the value for the anhydrous salt.

[0028] From the above viewpoints, when a polyvalent metal salt is used as a flocculant in the pretreatment solution of this embodiment, one or more selected from the group consisting of calcium formate, calcium acetate, calcium propionate, calcium butyrate, calcium benzoate, calcium lactate, calcium gluconate, and calcium pantothenate can be suitably selected. These calcium salts may be used alone or in combination of two or more.

[0029] From the viewpoints of improving the print quality of printed matter and also improving the blending stability during production of the pretreatment liquid, the content of the polyvalent metal salt relative to the total amount of the pretreatment liquid is preferably 0.1 to 40 mass%, more preferably 0.3 to 20 mass%, and particularly preferably 0.5 to 10 mass%. However, the content of the polyvalent metal salt refers to the content of the anhydride, and when a polyvalent metal salt containing a hydrate is used, the content is calculated excluding the mass of the water content of the hydrate.

[0030] (cationic resin) The pretreatment solution of this embodiment can use a cationic resin as the flocculant. In this application, the term "cationic resin" refers to a resin having only cationic groups as ionic groups, or a resin having cationic and anionic groups as ionic groups, in which the molar equivalents of the cationic groups are greater than the molar equivalents of the anionic groups. Specifically, a resin having a cationic group millimole equivalent greater than 0.4 mmole / g and a cationic group millimole equivalent greater than the anionic group millimole equivalent is a "cationic resin" in this application.

[0031] The cationic group millimole equivalent is calculated by multiplying the number of millimoles of cationic groups contained in 1 g of resin by the valence of the cationic groups (however, when the resin contains two or more types of cationic groups, the product of the number of millimoles contained in 1 g of resin and the valence calculated for each cationic group is added together). The method for calculating the anionic group millimole equivalent is the same as the method for calculating the cationic group equivalent described above, except that "cationic group" is replaced with "anionic group."

[0032] Examples of the cationic group include a primary amino group, a secondary amino group, a tertiary amino group, a quaternary ammonium group, an amide group, a pyrrole group, a pyridine group, and an imidazole group. Examples of the anionic group include a carboxy group, a sulfo group, a sulfino group, a phosphate group (phosphoric acid group), and a phosphoryl group.

[0033] The cationic resin may be a water-soluble resin as described below or resin fine particles. In addition, a water-soluble cationic resin and resin fine particles may be used in combination.

[0034] When the pretreatment liquid of this embodiment contains a cationic resin as a flocculant, it is preferable that the cationic resin be a water-soluble resin, since this will enable printed matter with excellent print quality and abrasion resistance to be obtained and will also provide a pretreatment liquid with good blend stability during production. The term "water-soluble resin" will be described later.

[0035] Furthermore, in the pretreatment liquid of this embodiment, resins containing diallylamine structural units and / or diallylammonium structural units are preferably used because they can achieve both print quality and abrasion resistance of printed matter. Resins containing diallylammonium structural units are particularly preferably selected because they offer an excellent balance between the ability to disrupt the dispersion state of solid components in the aqueous inkjet ink and / or the ability to thicken the aqueous inkjet ink, and the wetting and spreading properties of droplets of the aqueous inkjet ink, thereby easily producing printed matter free of white spots and color bleeding, and because the quaternary ammonium groups interact with functional groups present on the surface of the printing substrate, resulting in printed matter with excellent adhesion. Furthermore, in terms of availability, the hydrochloride or ethyl sulfate salt of diallyldimethylammonium and / or diallylmethylethylammonium is preferably selected as the diallylammonium structural unit.

[0036] Commercially available examples of cationic resins containing diallylammonium structural units include PAS-H-1L, PAS-H-5L, PAS24, PAS-84, PAS-J-81L, PAS-J-81, PAS-J-41, PAS-880, PAS2351, and PAS2451 (manufactured by Nittobo Medical Co., Ltd.); and Unisense FPA100L, FPA101L, FPA102L, FPA1000L, FPA1001L, FCA1000L, FCA1001L, CA1002L, FCA1003L, FCA5000L, ZCA1000L, ZCA1001L, and ZCA1002L (manufactured by Senka Chemical Co., Ltd.).

[0037] The cationic resin may be used alone or in combination of two or more types. From the viewpoint of achieving both good print quality and good abrasion resistance of the printed matter, the content of the cationic resin relative to the total amount of the pretreatment liquid is preferably 1 to 30 mass %, more preferably 2 to 20 mass %, and particularly preferably 2.5 to 15 mass %.

[0038] (organic acid) When the pretreatment liquid of this embodiment contains an organic acid as a flocculant, any organic acidic compound having an acid group such as a carboxy group, a sulfo group, a sulfino group, a phosphate group (phosphoric acid group), or a phosphoryl group can be used. Among these, organic acids having a carboxy group or a phosphate group are preferred because they produce printed matter with excellent print quality. From a similar perspective, i.e., to improve the print quality of printed matter, compounds having multiple of the above-listed acid groups are also preferred. Specific examples of compounds that can be preferably used as organic acids include glutaric acid, malonic acid, succinic acid, malic acid, tartaric acid, citric acid, and pyrophosphoric acid.

[0039] The organic acid may be used alone or in combination of two or more kinds. From the viewpoint of improving the print quality of printed matter, the content of the organic acid relative to the total amount of the pretreatment liquid is preferably 1 to 30 mass %, and more preferably 3 to 20 mass %.

[0040] <Resins (excluding cationic resins)> The pretreatment solution of this embodiment contains at least one resin other than a cationic resin. As described above, the resin must be able to exist stably even in the presence of a flocculant, so a nonionic resin (R) is used.

[0041] (Nonionic Resin(R)) In this application, the term "nonionic resin" refers to a resin having an anionic group millimole equivalent of 0.4 mmole / g or less (or 0 mmole / g) and a cationic group millimole equivalent of 0.4 mmole / g or less (or 0 mmole / g). A resin that meets these requirements can be stably present in the pretreatment solution even in the presence of the flocculant.

[0042] Specific examples of resins that can be used as the nonionic resin (R) include urethane (urea) resins, (meth)acrylic resins, (maleic anhydride) resins, vinyl alcohol resins, polyolefin resins, polyester resins, vinyl chloride resins, etc., but are not limited to these as long as they satisfy the above-mentioned requirements. Furthermore, the nonionic resin (R) may be used alone or in combination of two or more types.

[0043] In one embodiment, the nonionic resin (R) preferably has a hydrophobic segment, since this can effectively impart viscosity to the pretreatment liquid and improve the initial discharge stability and continuous discharge stability. In a resin having a hydrophobic segment, the hydrophobic segments associate with each other through hydrophobic interaction. This can impart a viscosity to the pretreatment liquid that is effective in improving discharge stability. As described above, if the association force is too strong, there is a risk that the initial discharge stability, continuous discharge stability, etc. may deteriorate. However, in the pretreatment liquid of this embodiment, this deterioration can be suppressed by using a water-soluble organic solvent (S2) or the like in combination.

[0044] In this application, "urethane (urea)" means urethane and / or urethane urea, "(meth)acrylic" means acrylic and / or methacrylic, and "(maleic anhydride)" means maleic acid and / or maleic anhydride. In addition, in the present application, the term "(meth)acrylic resin" refers to a resin using one or more polymerizable monomers selected from the group consisting of acrylic acid, methacrylic acid, acrylic acid esters, and methacrylic acid esters. In addition to the polymerizable monomers listed above, a styrene-based monomer may also be used as a polymerizable monomer constituting the acrylic resin. However, resins containing maleic acid (anhydride) as the polymerizable monomer are not included in the "(meth)acrylic resin" in the present application. Furthermore, the term "maleic anhydride resin" in the present application refers to a resin using at least maleic anhydride as a polymerizable monomer. The maleic anhydride resin may further use one or more polymerizable monomers selected from the group consisting of α-olefins, acrylic acid, methacrylic acid, acrylic acid esters, methacrylic acid esters, styrene, and styrene derivatives.

[0045] Generally, resins are known to be in the form of water-soluble resins and resin particles. The nonionic resin (R) contained in the pretreatment liquid of this embodiment may be either of these, or may be used in combination.

[0046] In this application, a resin with a solubility of 1 g or more in 100 g of water at 25°C is referred to as a "water-soluble resin," and a resin with a solubility of less than 1 g is referred to as a "water-insoluble resin." Among the water-insoluble resins, a resin dispersed in water in a particulate form and having a volumetric median diameter (also referred to as "D50" in this application) of 10 to 1,000 nm is referred to as a "resin microparticle." Furthermore, the D50 value in this application is a value measured using a dynamic light scattering particle size distribution analyzer such as the Nanotrac UPA-EX150 manufactured by Microtrac-Bell, using water as the dispersion medium, at 25°C.

[0047] In one embodiment, a water-soluble resin is preferably used because it can impart a suitable viscosity to the pretreatment liquid and improve the initial discharge stability and continuous discharge stability. Furthermore, when a water-soluble resin is used as the nonionic resin (R), a hydrophobically modified urethane (urea) resin is preferably used because it improves the initial discharge stability and continuous discharge stability even when the blending amount is small, and because it rapidly increases the viscosity on a non-permeable substrate during printing and drying, improving the print quality of the printed matter.

[0048] In the present application, the term "hydrophobically modified urethane (urea) resin" refers to a urethane (urea) resin having an alkyl group and / or alkylene group having 6 or more carbon atoms in the molecule. Commercially available examples of the hydrophobically modified urethane (urea) resin include, but are not limited to, the ADEKA NOL UH series (manufactured by ADEKA Corporation) and the SN Thickener 600 series (manufactured by SAN NOPCO Corporation).

[0049] Furthermore, when the pretreatment liquid of this embodiment contains a water-soluble resin as the nonionic resin (R), the use of a resin having dispersion stabilizing ability as the water-soluble resin allows for further use in combination with, for example, an anionic resin, as described below. This is because the water-soluble resin having dispersion stabilizing ability functions as a protective colloid for the anionic resin, and can stabilize the anionic resin in the pretreatment liquid even in the presence of a flocculant.

[0050] In the present application, the term "resin capable of stabilizing dispersion" refers to a resin that contains a certain amount of aromatic ring structures, i.e., a moiety that adsorbs to the material to be stabilized (anionic resin in the above-mentioned example). Specifically, the term refers to a resin in which the content of aromatic ring structures represented by the following formula 1 is 10% by mass or more (preferably 15% by mass or more, and particularly preferably 20% by mass or more).

[0051] Formula 1: (Aromatic ring structure content) (mass%) = Σ[(ni × MS ÷ Mi) × Wi]

[0052] In the above formula 1, ni is the number of moles of an aromatic ring structure contained in a polymerizable monomer having an aromatic ring structure among the polymerizable monomers constituting the resin (for example, ni=1 for styrene and ni=2 for phenylstyrene), MS is the molecular weight (78.1) of the target structure (aromatic ring structure), Mi is the molecular weight of the polymerizable monomer having the aromatic ring structure, and Wi is the content (mass%) of the polymerizable monomer having the aromatic ring structure relative to the total amount of polymerizable monomers constituting the resin.

[0053] In addition, when the type and content of the polymerizable monomer constituting the resin are unknown, the content of the polymerizable monomer having an aromatic ring structure and the number of moles of the aromatic ring structure can be measured, for example, by NMR (nuclear magnetic resonance) measurement, and then the content of the aromatic ring structure can be calculated using the above formula 1.

[0054] Examples of water-soluble resins that have such dispersion stabilizing ability and are nonionic resins (R) include DISPERBYK-190, 192, and 2015; and BYKJET-9151 (manufactured by BYK-Chemie). The blending amount of these resins that have dispersion stabilizing ability and are nonionic resins (R) is preferably 5 to 40% by mass, and more preferably 10 to 30% by mass, relative to the blending amount of the material to be dispersed (anionic resin in the above-mentioned example).

[0055] When a water-soluble resin is contained as the nonionic resin (R), only one type may be used, or two or more types may be used in combination. From the viewpoint of significantly improving the initial discharge stability and continuous discharge stability of the pretreatment liquid, the content of the water-soluble resin as the nonionic resin (R) relative to the total mass of the pretreatment liquid is preferably 0.1 to 10 mass%, and particularly preferably 0.5 to 5 mass%.

[0056] On the other hand, in another embodiment, the pretreatment liquid of this embodiment can contain resin fine particles as the nonionic resin (R). The use of resin fine particles can improve the abrasion resistance of the resulting printed matter. Any resin that satisfies the above-mentioned anionic group millimole equivalent and anionic group millimole equivalent, as well as the requirements for resin fine particles, can be used as the nonionic resin (R). Among these, polyolefin resins are preferably used from the viewpoint of achieving both initial ejection stability and abrasion resistance of the printed matter. Commercially available examples of the polyolefin resins include the AQUACER series (manufactured by BYK-Chemie), the Hi-Tec E series, and the Hi-Tec P series (manufactured by Toho Chemical Industry Co., Ltd.), but are not limited to these.

[0057] When resin fine particles are used as the nonionic resin (R), only one type may be used, or two or more types may be used in combination. From the viewpoint of simultaneously achieving both the initial discharge stability and continuous discharge stability of the pretreatment liquid, as well as the abrasion resistance of the printed matter, the content of the resin fine particles as the nonionic resin (R) relative to the total mass of the pretreatment liquid is preferably 0.1 to 20 mass%, particularly preferably 1 to 10 mass%.

[0058] The pretreatment liquid of this embodiment can use the above-mentioned water-soluble resin and resin fine particles in combination as the nonionic resin (R). When a water-soluble resin and resin fine particles are used as the nonionic resin (R), the ratio of the mass content of the resin fine particles to the mass content of the water-soluble resin (mass of resin fine particles / mass of water-soluble resin) is preferably 0.1 to 200, and particularly preferably 0.5 to 100. By satisfying the above requirements, the initial ejection stability, continuous ejection stability, and abrasion resistance of the resulting printed matter are all improved.

[0059] (anionic resin) The pretreatment liquid of this embodiment may further contain a resin having anionic properties (anionic resin). Adding an anionic resin to the pretreatment liquid improves adhesion to the printing substrate and the abrasion resistance of the printed matter. In this application, the term "anionic resin" refers to a resin having an anionic group millimole equivalent greater than 0.4 mmole / g and having an anionic group millimole equivalent equal to or greater than the cationic group millimole equivalent.

[0060] On the other hand, since anionic resins generally aggregate due to the presence of a flocculant in the pretreatment solution, it is difficult to stably coexist with the flocculant in the pretreatment solution. However, by using the anionic resin in combination with a nonionic resin (R) that has the above-mentioned dispersion stabilizing ability and is a water-soluble resin, the anionic resin can be stably present even in the presence of a flocculant.

[0061] In the pretreatment liquid of this embodiment, the resin species exemplified as the resin that can be used as the nonionic resin (R) can be used as the anionic resin. From the viewpoint of achieving both the initial discharge stability and continuous discharge stability of the pretreatment liquid, as well as the abrasion resistance of the printed matter, the content of the anionic resin particles relative to the total amount of the pretreatment liquid is preferably 0.1 to 20 mass %, more preferably 0.5 to 15 mass %, and particularly preferably 1 to 10 mass %.

[0062] <Water-soluble organic solvent (S)> The pretreatment solution of this embodiment contains, as water-soluble organic solvents, a water-soluble organic solvent (S1) having an octanol / water partition coefficient of -1.60 or more and less than -0.20, and a water-soluble organic solvent (S2) having an octanol / water partition coefficient of -0.20 to 1.00. As the octanol / water partition coefficient in this application, for example, the value of "ClogP" obtained using "ChemDraw Professional Ver. 16.0" manufactured by PerkinElmer can be used.

[0063] In addition, in the present application, the term "water-soluble organic solvent" refers to an organic compound that has a solubility in water at 25°C of 1% by mass or more and is liquid at 25°C.

[0064] (Water-soluble organic solvent (S1)) The water-soluble organic solvent (S1) contained in the pretreatment liquid of this embodiment can be any water-soluble organic solvent having an octanol / water partition coefficient of -1.60 or more and less than -0.20. The pretreatment liquid of this embodiment may contain only one type of compound as the water-soluble organic solvent (S1), or two or more types of compounds may be used in combination.

[0065] The octanol / water partition coefficient of the water-soluble organic solvent (S1) is more preferably -1.40 to -0.30, and particularly preferably -1.20 to -0.40. By setting the octanol / water partition coefficient of the water-soluble organic solvent (S1) within the above range, the affinity of the water-soluble organic solvent (S2) with water and the hydrophilic material is increased, and a uniform pretreatment liquid can be obtained, thereby improving continuous discharge stability. Furthermore, the presence of a water-soluble organic solvent (S1) having an octanol / water partition coefficient within the above range can improve the blending stability during production of the pretreatment liquid and the storage stability of the pretreatment liquid.

[0066] The content of the water-soluble organic solvent (S1) in the pretreatment liquid of this embodiment is preferably 3 to 45 mass% and more preferably 5 to 30 mass% based on the total amount of the pretreatment liquid. Additionally, the content of the water-soluble organic solvent (S1) is preferably more than 60 mass% and less than 93 mass%, and particularly preferably more than 65 mass% and less than 91 mass%, based on the total content of the water-soluble organic solvent (S1) and the water-soluble organic solvent (S2). By keeping the content of the water-soluble organic solvent (S1) within the above range, the blending stability during production of the pretreatment liquid and the storage stability of the pretreatment liquid can be improved. Furthermore, even if water dries up near the nozzle, the flocculant will not precipitate, and a good discharge state can be maintained.

[0067] Examples of compounds that can be used as the water-soluble organic solvent (S1) include ethanol (-0.24), 3-methyl-1,5-pentanediol (-0.24), diethylene glycol dimethyl ether (-0.26), propylene glycol monomethyl ether (-0.30), 3-methyl-1,3-butanediol (-0.33), trimethylolpropane (-0.39), N-methyl-2-pyrrolidone (-0.40), 1,2-butanediol (-0.53), 1,5-pentanediol (-0.64), 2-methyl-1,3-propanediol (-0.65), and 2-methyl-1,3-propanediol (-0.66). Examples of water-soluble organic solvents include, but are not limited to, ethanol (-0.64), dipropylene glycol (-0.69), 1,3-butanediol (-0.73), diethylene glycol monomethyl ether (-0.78), triethylene glycol monomethyl ether (-0.96), 2-pyrrolidone (-0.97), propylene glycol (-1.06), 1,4-butanediol (-1.16), diethylene glycol (-1.30), ethylene glycol (-1.37), triethylene glycol (-1.48), and glycerin (-1.54). The numbers in parentheses are the octanol / water partition coefficients of each water-soluble organic solvent.

[0068] (Water-soluble organic solvent (S2)) The water-soluble organic solvent (S2) contained in the pretreatment solution of this embodiment can be any water-soluble organic solvent having an octanol / water partition coefficient of −0.20 to 1.00. The pretreatment solution of this embodiment may contain one type of compound as the water-soluble organic solvent (S2), or two or more types of compounds may be used in combination.

[0069] The octanol / water partition coefficient of the water-soluble organic solvent (S2) is more preferably 0.10 to 0.90, and particularly preferably 0.40 to 0.80. When the octanol / water partition coefficient of the water-soluble organic solvent (S2) is within the above range, the association state between the hydrophobic segments of the nonionic resin (R) can be adequately loosened, and the continuous discharge stability of the pretreatment liquid can be improved.

[0070] Furthermore, as described above, when the content of the nonionic resin (R) in 100 g of the pretreatment liquid is WR (g) and the content of the water-soluble organic solvent (S2) is WS2, the value expressed by WR / WS2 is preferably 0.03 to 10, and particularly preferably 0.1 to 2. By keeping the value expressed by WR / WS2 within the above range, the association state between the hydrophobic segments of the nonionic resin (R) can be appropriately loosened, and the continuous discharge stability of the pretreatment liquid and the blending stability during production are improved.

[0071] Furthermore, in the pretreatment liquid of this embodiment, the ratio of the mass content of the water-soluble organic solvent (S2) to the total mass content of the water-soluble organic solvent (S1) and the water-soluble organic solvent (S2) is preferably 0.05 to 0.5. This effectively exhibits both the effect of the water-soluble organic solvent (S1) of improving the affinity of the water-soluble organic solvent (S2) and the like, and the effect of the water-soluble organic solvent (S2) of loosening the nonionic resin (R), thereby simultaneously improving the initial discharge stability, continuous discharge stability, and blending stability during production.

[0072] In addition, the content of the water-soluble organic solvent (S2) in the pretreatment liquid of this embodiment is preferably 0.1 to 15 mass% and more preferably 1 to 10 mass% based on the total amount of the pretreatment liquid. Additionally, the content of the water-soluble organic solvent (S2) is preferably 5 to 50 mass%, more preferably 7 to 40 mass%, and particularly preferably 9 to 35 mass%, based on the sum of the contents of the water-soluble organic solvents (S1) and (S2). Because the water-soluble organic solvent (S2) is relatively hydrophobic, by keeping the content within the above range, it is easy to maintain affinity with hydrophilic materials such as water and aggregating agents, and a uniform pretreatment liquid can be obtained. As a result, continuous discharge stability is improved.

[0073] Examples of compounds that can be used as the water-soluble organic solvent (S2) include dipropylene glycol monomethyl ether (-0.16), diethylene glycol monoisopropyl ether (-0.08), tripropylene glycol monomethyl ether (-0.03), 2-methyl-2,4-pentanediol (-0.02), 1,2-pentanediol (0.00), ethylene glycol monoallyl ether (0.00), and the like. Examples of water-soluble organic solvents include, but are not limited to, ethylene glycol monoisopropyl ether (0.03), diethylene glycol ethyl methyl ether (0.13), dipropylene glycol dimethyl ether (0.36), 3-methoxy-3-methyl-1-butanol (0.42), triethylene glycol mono-n-butyl ether (0.49), diethylene glycol diethyl ether (0.52), 1,2-hexanediol (0.53), diethylene glycol monoisobutyl ether (0.54), propylene glycol mono-n-propyl ether (0.62), diethylene glycol mono-n-butyl ether (0.67), and dipropylene glycol mono-n-propyl ether (0.75). The numbers in parentheses are the octanol / water partition coefficients of each water-soluble organic solvent.

[0074] (Other water-soluble organic solvents) The pretreatment liquid of this embodiment may contain water-soluble organic solvents other than the water-soluble organic solvent (S1) and the water-soluble organic solvent (S2) (also referred to herein as "other water-soluble organic solvents"). As the other water-soluble organic solvents, only one type of compound may be used, or two or more types of compounds may be used in combination.

[0075] Examples of other water-soluble organic solvents that can be used in the pretreatment liquid of this embodiment include, but are not limited to, diglycerin (-2.96), glycereth-3 (-3.49), glycereth-20 (-5.42), propylene glycol monobutyl ether (1.15), 2-ethyl-1,3-hexanediol (1.26), diethylene glycol mono-n-hexyl ether (1.72), etc. The numbers in parentheses are octanol / water partition coefficients.

[0076] When the pretreatment liquid of this embodiment contains another water-soluble organic solvent, the content thereof is preferably 0.01 to 5% by mass relative to the total amount of the pretreatment liquid.

[0077] The total content of the water-soluble organic solvents contained in the pretreatment liquid of this embodiment is preferably 1 to 50 mass %, more preferably 3 to 40 mass %, and particularly preferably 5 to 30 mass %, relative to the total amount of the pretreatment liquid.

[0078] <Water> The content of water in the pretreatment liquid of this embodiment is preferably 30 to 95 mass %, more preferably 40 to 90 mass %, and even more preferably 50 to 85 mass %, based on the total mass of the pretreatment liquid. Water is an essential material for increasing the mutual solubility of the materials essential to the pretreatment liquid of this embodiment, such as the flocculant, nonionic resin (R), water-soluble organic solvent (S1), and water-soluble organic solvent (S2), and for improving the blending stability during production and storage stability of the pretreatment liquid.

[0079] <Other ingredients> In addition to the materials described above, the pretreatment liquid of this embodiment may contain materials such as a surfactant, a pH adjuster, a crosslinking agent, and a preservative, as needed.

[0080] (surfactant) The pretreatment liquid of this embodiment may further contain a surfactant. Examples of such surfactants include acetylene diol surfactants, acetylene monool surfactants, siloxane surfactants, fluorine surfactants, and polyoxyalkylene monoalkyl ether surfactants. These surfactants may be used alone or in combination.

[0081] In particular, it is preferable to use one or more surfactants selected from the group consisting of acetylene diol surfactants and siloxane surfactants as the surfactant, because the surface tension of the pretreatment liquid of this embodiment applied to the printing substrate is significantly reduced in a very short time, thereby improving the print quality of the printed matter, and because a pretreatment liquid with good wetting and spreading properties can be obtained even for printing substrates with relatively high interfacial free energy, thereby improving the print quality regardless of the type of printing substrate.

[0082] Examples of commercially available acetylene diol surfactants include Surfynol 61, 104E, 104H, 104A, 104BC, 104DPM, 104PA, 104PG-50, 420, 440, 465, 485, 2502, SE, SE-F, Dynol 604, 607 (manufactured by Evonik Chemical Industry Co., Ltd.), Olfine E1004, E1010, E1020, PD-001, PD-002W, PD-004, PD-005, EXP.4001, EXP.4200, EXP.4123, and EXP.4300 (manufactured by Nissin Chemical Industry Co., Ltd.).

[0083] Examples of commercially available siloxane surfactants include BY16-201, FZ-77, FZ-2104, FZ-2110, FZ-2162, F-2123, L-7001, L-7002, SF8427, SF8428, SH3749, SH8400, 8032ADDITIVE, SH3773M (manufactured by Dow Corning Toray Co., Ltd.), TEGO Glide 100, TEGO Glide 410, TEGO Glide 432, TEGO Glide 435, TEGO Glide 440, TEGO Glide 450, TEGO Twin 4000, TEGO Twin 4100, TEGO Wet250, TEGO Wet260, TEGO Wet270, TEGO Wet280 (manufactured by Evonik), SAG-002, SAG-503A (manufactured by Nissin Chemical Industry Co., Ltd.), BYK-331, BYK-333, BYK-345, BYK-346, BYK-347, BYK-348, BYK-349, BYK-3420, BYK-UV3500, BYK-UV3510 (manufactured by BYK-Chemie), KF-3 51A, KF-352A, KF-353, KF-354L, KF-355A, KF-6004, KF-6011, KF-6012, KF-6013, KF-6015, KF-6016, KF-6017, KF-6043, KF-615A, KF-640, KF-642, and KF-643 (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0084] (pH adjuster) The pretreatment liquid of this embodiment may further contain a pH adjuster. The use of a pH adjuster can suppress damage to components used in the pretreatment liquid application device, suppress pH fluctuations over time, maintain the performance of the pretreatment liquid over the long term, and maintain or improve its storage stability and ejection stability.

[0085] Specifically, to basify the pretreatment liquid, alkanolamines such as dimethylethanolamine, diethanolamine, triethanolamine, and N-methyldiethanolamine; aqueous ammonia; alkali metal hydroxides such as lithium hydroxide and potassium hydroxide; and alkali metal carbonates such as lithium carbonate, sodium carbonate, sodium bicarbonate, and potassium carbonate can be used. To acidify the pretreatment liquid, hydrochloric acid, sulfuric acid, acetic acid, citric acid, maleic acid, maleic anhydride, succinic acid, tartaric acid, malic acid, boric acid, fumaric acid, malonic acid, ascorbic acid, and glutamic acid can be used. The pH adjuster is not limited to the above materials, and one type may be used alone, or two or more types may be used in combination.

[0086] The amount of the pH adjuster is preferably 0.01 to 5% by mass, more preferably 0.05 to 3% by mass, based on the total amount of the pretreatment liquid. By keeping the amount of the pH adjuster within the above range, the pH will not change due to external stimuli such as the dissolution of carbon dioxide in the atmosphere, and the effects of the above-mentioned flocculant, nonionic resin (R), water-soluble organic solvent (S1), and water-soluble organic solvent (S2) will not be impaired.

[0087] (Crosslinking agent) The pretreatment liquid of this embodiment may further contain a crosslinking agent. The use of a crosslinking agent in the pretreatment liquid improves adhesion between the printing substrate and the pretreatment layer, and can also improve the abrasion resistance of the printed matter, although the detailed mechanism is unknown.

[0088] The crosslinking agent contained in the pretreatment liquid may be a material capable of exhibiting the above-mentioned effects, such as a polyhydrazide compound, a (poly)carbodiimide compound, a polyoxazoline compound, etc. The term "(poly)carbodiimide compound" refers to a carbodiimide compound and / or a polycarbodiimide compound. Among these, polyhydrazide compounds are preferably used, which can improve the scratch resistance of printed matter without adversely affecting the initial discharge stability, continuous discharge stability, and blending stability during production, because polyhydrazide compounds do not require ionic groups for the crosslinking reaction to proceed, and the degree of progress of the crosslinking reaction can be controlled by the amount of water, making it possible to cause the crosslinking reaction to proceed after application to the printing substrate.

[0089] Specific examples of polyhydrazide compounds, i.e., compounds having two or more hydrazine residues in the molecule, that can be used include alkylene dihydrazines such as methylene dihydrazine, ethylene dihydrazine, propylene dihydrazine, and butylene dihydrazine; dihydrazide compounds of saturated aliphatic dibasic acids such as oxalic dihydrazide, malonic dihydrazide, succinic dihydrazide, glutaric dihydrazide, adipic dihydrazide, and sebacic dihydrazide; and dihydrazide compounds of unsaturated dibasic acids such as phthalic dihydrazide, fumaric dihydrazide, and itaconic dihydrazide. Note that when a polyhydrazide compound is used as a crosslinking agent, it is not limited to the above materials, and one type may be used alone, or two or more types may be used in combination.

[0090] The blending amount of the crosslinking agent is preferably 0.01 to 5 mass %, and more preferably 0.05 to 3 mass %, based on the total amount of the pretreatment liquid. By keeping the blending amount of the crosslinking agent within this range, it is possible to improve adhesion to the printing substrate, abrasion resistance of the printed matter, initial discharge stability, continuous discharge stability, and blending stability during production, without inhibiting the effects of the flocculant and nonionic resin.

[0091] <Physical properties of pretreatment liquid> The viscosity of the pretreatment liquid of this embodiment at 25°C is preferably 1 to 30 mPa·s, more preferably 3 to 20 mPa·s, and particularly preferably 5 to 10 mPa·s. A pretreatment liquid that satisfies the above viscosity range can be stably ejected from an inkjet head, resulting in printed matter with excellent print quality and adhesion, and also exhibiting good initial ejection stability and continuous ejection stability. The viscosity of the pretreatment liquid can be measured, for example, using an E-type viscometer (TVE25L viscometer manufactured by Toki Sangyo Co., Ltd.).

[0092] The static surface tension of the pretreatment liquid of this embodiment is preferably 20 to 40 mN / m, more preferably 21 to 37 mN / m, and particularly preferably 22 to 35 mN / m, from the viewpoint of imparting favorable wetting and spreading properties to a non-permeable substrate and forming a uniform, even pretreatment layer to obtain a printed product with excellent print quality. Note that the static surface tension in this application is a value based on the Wilhelmy method (plate method, vertical plate method) in an environment of 25°C, and can be measured, for example, using an automatic surface tensiometer CBVP-Z (manufactured by Kyowa Interface Science Co., Ltd.) and a platinum plate.

[0093] <Method of manufacturing pretreatment liquid> The pretreatment liquid of this embodiment can be produced, for example, by adding a flocculant, a nonionic resin (R), a water-soluble organic solvent (S1), a water-soluble organic solvent (S2), water, and, if necessary, an anionic resin, a surfactant, a pH adjuster, a crosslinker, and other materials, stirring and mixing, and then filtering as needed. However, the method for producing the pretreatment liquid of this embodiment is not limited to the above method. For example, when using an anionic resin that will flocculate in the presence of a flocculant, it is preferable to premix it with a nonionic resin that has dispersion stabilizing properties and then mix it with other materials from the perspective of improving blend stability. When stirring and mixing, heating may be performed in the range of 35 to 100°C as needed.

[0094] <Water-based inkjet ink> The pretreatment liquid of this embodiment can be used in combination with one or more aqueous inkjet inks in the form of an ink set. Preferably, the aqueous inkjet ink contains a pigment, a resin, and water. The aqueous inkjet ink may further contain a water-soluble organic solvent, a surfactant, etc.

[0095] The pigment contained in the aqueous inkjet ink used in combination with the pretreatment liquid of this embodiment is preferably a blue pigment such as CI Pigment Blue 15:3 or 15:4; a red pigment such as CI Pigment Red 122, 150, 166, 185, 202, 209, 266, 269, or 282 or CI Pigment Violet 19; a yellow pigment such as CI Pigment Yellow 12, 13, 14, 74, 120, 155, 180, 185, or 213; a black pigment such as carbon black; or a white pigment such as titanium oxide, because these pigments are excellent in color development and lightfastness and can produce printed matter with excellent print quality.

[0096] Furthermore, the aqueous inkjet ink used in combination with the pretreatment liquid of this embodiment preferably contains a resin. The resin preferably contains a pigment dispersing resin used to disperse the pigment and / or a binder resin used to bind the ink layer to the pretreatment layer, and it is particularly preferable that the ink contains at least a binder resin. Note that it is also possible to add the function of a binder resin to the pigment dispersing resin while substantially not blending in a resin that functions only as a binder resin.

[0097] As the pigment dispersing resin and the binder resin, a resin selected from the group consisting of (meth)acrylic resin, urethane (urea) resin, and polyester resin can be suitably used. In addition to these resins, polyolefin resin particles may also be used. The use of polyolefin resin particles in combination significantly improves abrasion resistance and adhesion between the ink layer and the pretreatment layer without adversely affecting the print quality of the printed matter.

[0098] In one embodiment, when a resin selected from the group consisting of (meth)acrylic resin, urethane (urea) resin, and polyester resin is used in combination with polyolefin resin microparticles, the amount of polyolefin resin microparticles relative to the amount of the resin selected from the group consisting of (meth)acrylic resin, urethane (urea) resin, and polyester resin is preferably 10 to 100% by mass, and more preferably 20 to 80% by mass. By keeping the amount within this range, the functions of the resin selected from the group consisting of (meth)acrylic resin, urethane (urea) resin, and polyester resin are not impaired, and the print image quality during high-speed printing, abrasion resistance, and adhesion between the ink layer and the pretreatment layer are all suitably improved.

[0099] Both the pigment dispersing resin and the binder resin may have acid groups, and in this case, the acid groups may be neutralized with a neutralizing agent. In this case, preferred examples of the neutralizing agent used for neutralization include alkanolamines such as dimethylaminoethanol, diethylaminoethanol, diethanolamine, triethanolamine, aminomethylpropanol, and N-methyldiethanolamine; alkylamines such as trimethylamine, triethylamine, and butylamine; heterocyclic amines such as morpholine; ammonia; and alkali metal hydroxides such as potassium hydroxide and sodium hydroxide.

[0100] When the aqueous inkjet ink used in combination with the pretreatment liquid of this embodiment contains a water-soluble organic solvent, from the viewpoints of being able to obtain printed matter of excellent print quality even in high-speed printing when used in combination with the pretreatment liquid of this embodiment and of providing excellent ejection stability of the aqueous inkjet ink, the weighted average boiling point of the water-soluble organic solvent contained in the aqueous inkjet ink at 1 atmosphere is preferably 145 to 215° C., more preferably 150 to 200° C., and particularly preferably 155 to 190° C. Furthermore, from the viewpoints of being able to obtain printed matter of excellent print quality and good abrasion resistance when combined with the pretreatment liquid of this embodiment and of providing printed matter of excellent print quality and abrasion resistance when printed at high speed when combined with the pretreatment liquid of this embodiment, the amount of the water-soluble organic solvent having a boiling point of 220° C. or higher at 1 atmosphere is preferably 5% by mass or less (can be 0% by mass), more preferably 2% by mass or less (can be 0% by mass), and particularly preferably 1% by mass or less (can be 0% by mass), based on the total amount of the aqueous inkjet ink.

[0101] From these viewpoints, when the aqueous inkjet ink contains a water-soluble organic solvent, it preferably contains a glycol monoalkyl ether solvent (having a boiling point of 100 to 220°C at 1 atmospheric pressure) and / or a dihydric alcohol solvent (having a boiling point of 100 to 220°C at 1 atmospheric pressure) from the viewpoint of print quality during high-speed printing. Furthermore, from the viewpoint of print quality during high-speed printing, it is particularly preferable to use a glycol monoalkyl ether solvent (having a boiling point of 100 to 220°C at 1 atmospheric pressure) in combination with a dihydric alcohol solvent (having a boiling point of 100 to 220°C at 1 atmospheric pressure).

[0102] Examples of glycol monoalkyl ether solvents (with a boiling point of 100 to 220°C at 1 atmospheric pressure) that can be preferably used include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, 2-methoxy-1-butanol, 3-methoxy-1-butanol, and 3-methyl-3-methoxy-1-butanol.

[0103] As the dihydric alcohol solvent (however, one having a boiling point of 100 to 220°C at 1 atmospheric pressure), from the viewpoint of print image quality during high-speed printing, an alkanediol that does not have hydroxyl groups at both ends of the hydrocarbon chain can be preferably used, and further, an alkanediol that has a branched alkyl group can be particularly preferably used. Examples of alkanediols that do not have hydroxyl groups at both ends of the hydrocarbon chain and do not have a branched alkyl group (provided that their boiling point at 1 atmosphere is 100 to 220°C) include 1,2-propanediol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, and 1,2-pentanediol. Examples of alkanediols that do not have hydroxyl groups at both ends of the hydrocarbon chain and have a branched alkyl group (provided that their boiling point at 1 atmosphere is 100 to 220°C) include 2-methyl-1,3-propanediol, 3-methyl-1,3-butanediol, and 2-methyl-2,4-pentanediol.

[0104] Furthermore, when the aqueous inkjet ink used in combination with the pretreatment liquid of this embodiment contains a surfactant, the amount of the surfactant added is preferably 0.01 to 5 mass %, and more preferably 0.05 to 3 mass %, relative to the total amount of the aqueous inkjet ink. The surfactant may be the same as the compounds listed above that can be used as surfactants that can be contained in the pretreatment liquid of this embodiment.

[0105] <Manufacturing method for printed matter> Next, the steps of a method for producing a printed matter using the above pretreatment liquid and aqueous inkjet ink will be described.

[0106] When producing a printed matter using the above-described pretreatment liquid and aqueous inkjet ink, it is preferable to carry out step (1) of printing the pretreatment liquid on a printing substrate and step (2) of printing the aqueous inkjet ink on the surface of the printing substrate obtained in step (1) to which the pretreatment liquid has been applied, in this order. In step (2), the aqueous inkjet ink may be printed on a layer of the pretreatment liquid in a dry state, or on a layer of the pretreatment liquid in a wet state. In particular, from the viewpoint of obtaining a printed matter that is particularly excellent in print image quality and abrasion resistance even in high-speed printing, it is preferable that the aqueous inkjet ink be printed on a layer of the pretreatment liquid in a wet state (i.e., the pretreatment liquid and aqueous inkjet ink are for use in a wet-on-wet printing method).

[0107] In the present application, "the pretreatment liquid is in a wet state" refers to a state in which, immediately before the landing of droplets of the aqueous inkjet ink, the total amount of volatile components remaining on the printing substrate is 50% by mass or more relative to the total amount of volatile components contained in the pretreatment liquid before application to the printing substrate. Furthermore, "the pretreatment liquid and the aqueous inkjet ink are for use in a wet-on-wet printing method" refers to a state in which the aqueous white ink is printed on a layer of the pretreatment liquid while the pretreatment liquid applied to the printing substrate before the aqueous inkjet ink is still wet. From the perspective of obtaining a printed product with excellent print quality and abrasion resistance, in step (2), the total amount of volatile components remaining on the printing substrate immediately before the landing of droplets of the aqueous inkjet ink is more preferably 70% by mass or more, and particularly preferably 90% by mass or more, relative to the total amount of volatile components contained in the pretreatment liquid before application to the printing substrate.

[0108] Here, the total remaining amount of volatile components contained in the pretreatment liquid on the printing substrate immediately before the droplets of the aqueous inkjet ink land can be calculated, for example, by the following method.

[0109] (i) First, calculate the mass per unit area (w0 [g / m 2]) has been measured, and step (1) (and, if a drying step or the like is performed after step (1) and before step (2) in the actual manufacturing method, that step) is performed without performing step (2) and subsequent steps to obtain a printed matter on which only a layer of pretreatment liquid is formed on the printing substrate. Note that the printing substrate used in the actual manufacturing method is used as the printing substrate. The pretreatment liquid is applied under the same conditions as in the actual manufacturing method. The amount applied is the maximum amount applied to the printing substrate in the actual manufacturing method. For example, when printing the pretreatment liquid on the printing substrate by inkjet printing, if the maximum amount in the actual manufacturing method is 100%, the pretreatment liquid is printed at a printing rate of 100%. On the other hand, for example, when applying the pretreatment liquid to the printing substrate by roller coating, the pretreatment liquid is applied so that the thickness of the layer of pretreatment liquid becomes the maximum thickness in the actual manufacturing method. Then, after producing a printed matter on which only a layer of pretreatment liquid is formed, the mass of the printed matter is measured and converted into mass per unit area (w1 [g / m 2 The mass of the printed matter is, for example, the value measured 30 to 60 seconds after the production of the printed matter in the state from '5 seconds before the impact of the aqueous inkjet ink droplets' to 'the impact of the aqueous inkjet ink droplets'. Alternatively, if the printed matter can be collected from the printing device immediately before the execution of step (2) in the actual manufacturing method, the printed matter may be collected from the actual manufacturing method, and w1 may be obtained from the printed matter.

[0110] (ii) On the other hand, using the same type of printing substrate and the same application conditions as those used in the measurement of w1, only step (1) is carried out (if a drying step or the like is carried out after step (1) and before step (2) in the actual manufacturing method, this step is not carried out), to obtain a printed matter on which only a layer of pretreatment liquid is formed on the printing substrate. The mass of the printed matter is measured and converted to mass per unit area (w2 [g / m 2 The mass of the printed matter is, for example, the value measured 30 to 60 seconds after the pretreatment liquid is applied to the printing substrate. Alternatively, if the printed matter can be collected from the printing device immediately after step (1) in the actual manufacturing method, the printed matter may be collected from the actual manufacturing method, and w2 may be determined from the printed matter. Alternatively, the density d [g / mL] of the pretreatment liquid and the volume per unit area of ​​the pretreatment liquid [mL / m 2 ] and the above-mentioned w0 [g / m 2 ], so w2 = w0 [g / m 2 ] + d [g / mL] × (volume per unit area of ​​pretreatment solution) [mL / m 2 When printing a pretreatment liquid onto a printing substrate using the inkjet method, the volume of the pretreatment liquid per unit area [mL / m 2 The density d of the pretreatment liquid can be measured using a pycnometer, for example.

[0111] (iii) The value obtained by the calculation formula 100 × (w10-w20 × Nvp) / [w20 × (1-Nvp)] is the total remaining amount (%) of volatile components contained in the pretreatment liquid on the printing substrate immediately before the aqueous inkjet ink droplets land, where in the above formula, w10 = w1-w0, w20 = w2-w0, and Nvp is the solids ratio of the pretreatment liquid (solids mass (g) / pretreatment liquid mass (g)).

[0112] In measuring the total amount of remaining volatile components, the mass is measured using a precision balance. The mass per unit area can be calculated by measuring the mass of a test piece cut out to a certain size and then dividing the mass by the area of ​​the test piece.

[0113] <Pretreatment liquid printing process (1)> In the step (1), the method of printing the pretreatment liquid of this embodiment onto the printing substrate is preferably an inkjet printing method, because the print image quality can be easily adjusted by controlling the amount of the pretreatment liquid applied in accordance with the coverage rate of the aqueous inkjet ink printed in the step (2), and the pretreatment liquid application device can be made compact. In other words, the pretreatment liquid of this embodiment is preferably used for the inkjet printing method.

[0114] The inkjet printing method may be a single-pass method in which a pretreatment liquid or the like is ejected onto a printing substrate only once, or a multi-pass method in which a short shuttle head is scanned back and forth multiple times in a direction perpendicular to the transport direction of the printing substrate while ejecting the pretreatment liquid or the like. Specific examples of the single-pass method include a method in which an inkjet head is scanned over a stationary printing substrate only once (referred to herein as a "scanning head single-pass method"), and a method in which the printing substrate is printed by passing it under a fixed inkjet head only once (referred to herein as a "fixed head single-pass method"). The method for producing a printed product using the pretreatment liquid of this embodiment may employ either of the above-mentioned methods. However, the fixed head single-pass method is preferably used from the viewpoint that it does not require adjustment of the ejection timing of the pretreatment liquid or the like relative to the scanning of the inkjet head and is less likely to cause deviation in the landing position, thereby producing a printed product with excellent print quality. The design resolution of the inkjet head used in the fixed head single pass method is preferably 600 dpi (dots per inch) or more, and more preferably 720 dpi or more, in order to obtain images with excellent quality.

[0115] On the other hand, when a coating method in which the pretreatment liquid is applied to a substrate is selected, a gravure coater, doctor coater, bar coater, blade coater, flexo coater, roll coater, or the like can be used.

[0116] In order to obtain a printed matter with excellent print quality and abrasion resistance, the thickness of the pretreatment layer immediately after application is preferably 1 to 10 μm, more preferably 2 to 8 μm, and particularly preferably 3 to 7 μm.

[0117] <Pre-treatment liquid drying process> As described above, in step (2), the aqueous inkjet ink may be printed on the pretreatment layer in a dry state or may be printed on the pretreatment layer in a wet state. When a drying step is performed after step (1) and before step (2), methods such as room temperature air drying and visible light drying are preferably used to prevent excessive drying of the pretreatment liquid. Furthermore, the energy applied to the pretreatment layer may be adjusted, and then a method used to dry the aqueous inkjet ink, as described below, may be used. Furthermore, these drying methods may be used alone or in combination.

[0118] <Water-based inkjet ink printing process (2)> In step (2), the aqueous inkjet ink is preferably printed on the pretreatment liquid in a wet state. Furthermore, in order to produce a print with excellent print quality, the aqueous inkjet ink is preferably printed so that at least a portion of the aqueous inkjet ink overlaps the area where the pretreatment liquid has been applied, and more preferably printed so that the aqueous inkjet ink overlaps only the area where the pretreatment liquid has been applied.

[0119] In step (2), the same aqueous inkjet ink may be filled into multiple inkjet heads, and the aqueous inkjet ink may be printed onto a printing substrate from each of the inkjet heads. Alternatively, the aqueous inkjet ink filled in the inkjet heads may be ejected from the inkjet heads in a heated state. In this case, the heating temperature of the aqueous inkjet ink in the inkjet heads is preferably 30 to 50°C, and more preferably 30 to 45°C. Furthermore, the aqueous inkjet ink may be printed while heating the printing substrate from, for example, the backside (the side opposite to the side on which the aqueous inkjet ink droplets land). In this case, the surface to be printed with the aqueous inkjet ink is preferably heated to a temperature of 30 to 55°C, and more preferably 35 to 50°C.

[0120] The aqueous inkjet ink may also contain a plurality of aqueous inkjet inks (aqueous inkjet ink set). Specifically, the aqueous inkjet ink may contain two or more inks selected from the group consisting of cyan ink, magenta ink, yellow ink, black ink, and white ink.

[0121] <Drying process after printing with water-based inkjet ink> After printing with the aqueous inkjet ink, it is preferable to carry out a step of drying the printing substrate to which the pretreatment liquid and aqueous inkjet ink have been applied. The drying method used in this step is not particularly limited, and conventionally known methods such as heat drying, hot air drying, infrared drying, microwave drying, drum drying, and high-frequency dielectric drying can be used. These drying methods may be used alone or in combination, but hot air drying and / or infrared drying are preferred in order to reduce damage to non-permeable substrates and achieve efficient drying.

[0122] <Printing base material> The printed matter produced by the present invention can be suitably printed on conventionally known printing substrates, but since a printed matter with excellent adhesion and abrasion resistance can be obtained, it is preferable to use a non-permeable substrate as the printing substrate. In this application, the term "non-permeable substrate" refers to a printing substrate into which water does not penetrate or be absorbed. Note that even if a printing substrate has voids inside, a substrate in which water does not penetrate into the voids (for example, when the surface of the printing substrate is coated) falls under the non-permeable substrate category in this application.

[0123] Specific examples of impermeable substrates include thermoplastic resin substrates such as polyvinyl chloride sheets, polyethylene terephthalate (PET) films, polypropylene films, polyethylene films, nylon films, and polystyrene films; metal substrates such as aluminum foil; and glass substrates. These printing substrates may have a smooth or textured surface and may be transparent, translucent, or opaque. Furthermore, a laminate of two or more of the above-listed printing substrates may be used, or a release adhesive layer or the like may be provided on the side opposite the printed surface of the pretreatment liquid and aqueous ink. An adhesive layer or the like may be provided on the printed surface after production of the printed matter. In addition, the printing substrate may be in the form of a roll or a sheet. Furthermore, from the viewpoint of printing the pretreatment liquid of this embodiment evenly and without unevenness and significantly improving the adhesion of the printed matter, it is also preferable to subject the above-listed impermeable substrates to a surface modification method such as corona treatment or plasma treatment before applying the pretreatment liquid. [Example]

[0124] The present invention will now be described in more detail with reference to the following examples and comparative examples. In the following description, "parts" and "%" are by mass unless otherwise specified.

[0125] <Production of pretreatment solutions 1 to 70> Each raw material was added to a stainless steel mixing vessel (capacity: 300 mL) equipped with a stirrer and a heating mechanism, so as to obtain the formulation shown in each column of Table 1 below. After addition, stirring and mixing were continued for 1 hour at room temperature (25°C), and then the contents of the mixing vessel were heated until the temperature reached 50°C, and stirred and mixed for another hour. The mixture was then cooled to room temperature and filtered through a nylon mesh with a pore size of 100 μm, and further filtered through a membrane filter with a pore size of 1.2 μm, to produce pretreatment solutions 1 to 70. The unit of addition for each raw material shown in Table 1 below is "g." Each raw material was added while stirring the mixture of materials already added to the mixing vessel. The ion-exchanged water, flocculant, water-soluble organic solvent (S), nonionic resin (R), and other raw materials were added to the mixing vessel in this order. However, if one of these components was not included, the component was skipped and the next component was added. For compositions containing two or more raw materials, the order of addition within that component was arbitrary.

[0126] [Table 1]

[0127] [Table 1]

[0128] [Table 1]

[0129] [Table 1]

[0130] Details of the product names and abbreviations listed in Table 1 above are as follows: In Table 1 and below, "Nv." refers to the solids concentration (unit: mass%), and "logP" refers to the water / octanol partition coefficient. PAS-H-5L: Nittobo Medical Co., Ltd., cationic resin containing diallyldimethylammonium hydrochloride as a structural unit PAS-J-81L: Manufactured by Nittobo Medical Co., Ltd. A cationic resin containing diallyldimethylammonium hydrochloride and acrylamide as structural units. 1,2-PD: 1,2-propanediol (log P: -1.06, boiling point at 1 atmosphere: 188°C) 1,2-BD: 1,2-butanediol (log P: -0.53, boiling point at 1 atmosphere: 193°C) EDG: Diethylene glycol monoethyl ether (log P: -0.39, boiling point at 1 atmosphere: 196°C) 3m-1,5-PenD: 3-methyl-1,5-pentanediol (log P: -0.24, boiling point at 1 atmosphere: 250°C) 2m-2,4-PenD: 2-methylpentane-2,4-diol (log P: -0.02, boiling point at 1 atmosphere: 198°C) DPDM: Dipropylene glycol dimethyl ether (log P: 0.36, boiling point at 1 atmosphere: 171°C) 1,2-HexD: 1,2-hexanediol (log P: 0.53, boiling point at 1 atmosphere: 224°C) DPnP: Dipropylene glycol-n-propyl ether (log P: 0.75, boiling point at 1 atmosphere: 210°C) PnB: Propylene glycol monobutyl ether (log P: 1.15, boiling point at 1 atmosphere: 170°C) ADEKA NOL UH-540: Hydrophobically modified water-soluble urethane resin manufactured by ADEKA Corporation DISPER BYK-190: Monoalkoxy polyethylene oxide ester of styrene-maleic acid copolymer (water-soluble resin) manufactured by BYK-Chemie Poval 3-80 aqueous solution: Poval 3-80 (polyvinyl alcohol manufactured by Kuraray, saponification degree: 80%) dissolved in ion-exchanged water to a solid content of 15% Superflex 500M: Polyurethane resin particles manufactured by Daiichi Kogyo Seiyaku Co., Ltd. Hi-Tec E-5403P: Oxidized polyethylene resin particles manufactured by Toho Chemical Co., Ltd. Vinyblan 278: Polyvinyl chloride resin particles manufactured by Nissin Chemical Industry Co., Ltd. NeoCryl XK-190: (Meth)acrylic resin particles manufactured by DSM Coating Resins Surfynol 440: Evonik acetylene diol surfactant Surfynol 485: Evonik acetylene diol surfactant TEGO Wet 280: Evonik polyether-modified siloxane surfactant ADH: Adipic acid dihydrazide SDH: Sebacic acid dihydrazide V-04: Carbodilite V-04 (Nisshinbo Chemical Co., Ltd., polycarbodiimide compound, Nv.: 40% by mass)

[0131] <Production of pigment dispersion> (Manufacturing black pigment dispersion) 15 parts of carbon black ("PrinteX85" manufactured by Orion Engineered Carbons), 3 parts of styrene-acrylic resin (a random polymer of styrene / acrylic acid / behenyl acrylate = 45 / 30 / 25 (mass ratio) in which all acid groups had been neutralized with dimethylaminoethanol, an anionic group millimolar equivalent of 4.2 mmole / g, and a weight-average molecular weight of 20,000), and 82 parts of water were placed in a mixing vessel equipped with a stirrer and premixed for 1 hour. Then, using a Shinmaru Enterprises "Dynomill" (0.6 L volume) filled with 1,800 g of 0.5 mm diameter zirconia beads, circulation dispersion was carried out until the 50% diameter of the carbon black reached approximately 100 nm, producing a black pigment dispersion.

[0132] (Manufacturing cyan pigment dispersions, magenta pigment dispersions, and yellow pigment dispersions) Cyan pigment dispersion liquid, magenta pigment dispersion liquid, and yellow pigment dispersion liquid were produced using the same raw materials and method as for the black pigment dispersion liquid, except that the pigments shown below were used as pigments and circulatory dispersion was carried out until the respective particles reached the 50% diameter shown below. Cyan pigment dispersion: Toyocolor LIONOL BLUE 7358G (CI Pigment Blue 15:3), 50% diameter = 150 nm Magenta pigment dispersion: Toshiki Red 150TR (CI Pigment Red 150) manufactured by Tokyo Color Materials Co., Ltd., 50% diameter = 200 nm Yellow pigment dispersion: Toyocolor LIONOL YELLOW TT1405G (CI Pigment Yellow 14), 50% diameter = 150 nm

[0133] <Production of aqueous binder resin solution> An aqueous solution of binder resin 40 (solid content 30%) was produced by the method described in the examples of JP 2020-180178 A, and designated as "aqueous solution of binder resin."

[0134] <Production of Water-Based Inkjet Inks 1 to 13> Each raw material was added to a stainless steel mixing vessel (capacity: 300 mL) equipped with a stirrer and a heating mechanism, according to the formulation shown in each column of Table 2 below. After addition, mixing and stirring were continued for 1 hour at room temperature (25°C), and then the contents of the mixing vessel were heated until the temperature reached 50°C and further mixed and stirred for 1 hour. The mixture was then cooled to room temperature and filtered through a membrane filter with a pore size of 1 μm to produce water-based black inks 1 to 13. In addition, water-based cyan ink, water-based magenta ink, and water-based yellow ink were obtained in the same manner as the water-based black ink, except that a cyan pigment dispersion, a magenta pigment dispersion, and a yellow pigment dispersion were used as the pigment dispersions, respectively. The water-based black ink, water-based cyan ink, water-based magenta ink, and water-based yellow ink with the same numbers were used as a water-based inkjet ink set in the following evaluations. The unit of the amount of each raw material added shown in Table 2 below is "g." Each raw material was added while stirring the mixture in the mixing container. Furthermore, the ion-exchanged water, water-soluble organic solvent, surfactant, aqueous binder resin solution, and pigment dispersion were added to the mixing container in this order. However, for components containing two or more types of raw materials, the order of addition within that component was arbitrary.

[0135] [Table 2]

[0136] Details of the trade names and abbreviations listed in Table 2 above that are not used in Table 1 above are as follows: Note that "bp" listed in Table 2 refers to the boiling point (unit: °C) at 1 atmosphere. 2,3-BD: 2,3-butanediol (boiling point at 1 atmosphere: 183°C) 3m-1,3-BD: 3-methyl-1,3-butanediol (boiling point at 1 atmosphere: 203°C) PM: Propylene glycol monomethyl ether (boiling point at 1 atmosphere: 121°C) DEG: Diethylene glycol (boiling point at 1 atmosphere: 244°C) Surfynol 465: Evonik acetylene diol surfactant

[0137] <Creating printed materials> An inkjet ejection device was prepared, with four Kyocera KJ4B-1200 inkjet heads (design resolution 1200 dpi, nozzle diameter 20 μm) arranged in the direction of transport of the printing substrate. Starting from the upstream inkjet head relative to the transport direction of the printing substrate, the inks were loaded in the following order: aqueous black ink, aqueous cyan ink, aqueous magenta ink, and aqueous yellow ink. Next, using an OSG System Products 250-OSP-02 non-wire bar coater, each of the pretreatment solutions prepared above was applied to a 20 μm-thick, biaxially oriented polypropylene film "OPU-1" manufactured by Mitsui Chemicals Tohcello, Inc., to a wet film thickness of 2.0 ± 0.2 μm. The film was then fixed directly onto the conveyor without a drying process. The conveyor was then driven at a constant speed, and as the polypropylene film passed under the inkjet heads, aqueous inkjet inks were ejected at a drop volume of 2 pL, printing the image described below. The printed polypropylene film was then immediately placed in an air oven at 70°C and dried for 3 minutes to produce a printed product.

[0138] The above-mentioned printed matter was produced using the combinations of pretreatment liquid and aqueous inkjet ink set shown in Table 3. In the above-mentioned method for producing a printed matter, the total amount of remaining volatile components contained in the layer of the pretreatment liquid on the printing substrate at the time of printing with the aqueous inkjet ink was calculated by the above-mentioned method and was found to be 95 to 100 mass %.

[0139] Three types of images were prepared for printing: a 5cm x 20cm image consisting of 100% coverage solid color patches arranged adjacently in the order cyan, magenta, yellow, and black (hereinafter referred to as the "solid patch image"); a 5cm x 20cm image consisting of a 5cm x 20cm area with a continuous coverage from 10% to 80% in the long side direction, with a single color gradation arranged adjacently in the order cyan, magenta, yellow, and black (hereinafter referred to as the "gradation image"); and an image consisting of 20 characters of each color printed in 6-point MS Mincho font, a mixture of hiragana and kanji (Japanese syllabary). Printed materials were then produced using each of the above pretreatment liquids.

[0140] The conveyor driving speed during the production of the prints was set to three conditions: 25 m / min, 50 m / min, and 75 m / min, and the above-mentioned three types of images were printed under each conveyor driving speed condition.

[0141] [Examples 1 to 74, Comparative Examples 1 to 8] The three types of printed matter described above were produced using the combinations of pretreatment liquid and aqueous inkjet ink set shown in Table 3. The following evaluations were carried out using these printed matter and the pretreatment liquid itself. The evaluation results are shown in Table 3. However, for the combinations of Examples 63 to 74, Evaluations 1 to 3, which were the same evaluation conditions as in Example 42, were not carried out.

[0142] <Evaluation 1: Evaluation of blend stability> The formulation stability of the pretreatment liquid during cleaning was evaluated by checking the occurrence of precipitates, turbidity, etc. during production of the pretreatment liquid described above, and for those in which no precipitates, turbidity, etc. occurred, the pretreatment liquid after production was left to stand for two weeks in an incubator set at 60°C, and then checking the occurrence of precipitates, turbidity, etc. The evaluation criteria were as follows, with ◎ and ○ being considered usable. ◎: When the pretreatment solution was produced, no precipitate or turbidity was observed before filtering through a nylon mesh. Furthermore, even after the pretreatment solution was filtered through a membrane filter and left to stand in an incubator set at 60°C for two weeks, no precipitate or turbidity was observed. ○: During production of the pretreatment liquid, precipitates and turbidity were observed in the pretreatment liquid before filtering through a nylon mesh. However, the precipitates and turbidity could be removed by filtering through the nylon mesh and membrane filter. Furthermore, even when the filtered pretreatment liquid was left to stand for 2 weeks in an incubator set at 60°C, no precipitates or turbidity were observed. ×: During the production of the pretreatment solution, precipitates or turbidity were observed in the pretreatment solution before filtering through a nylon mesh. The precipitates or turbidity could not be removed by filtering through a nylon mesh or membrane filter, or the precipitates or turbidity were removed by filtering, but when the filtered pretreatment solution was left to stand for 2 weeks in an incubator set at 60°C, precipitates or turbidity reappeared.

[0143] <Evaluation 2: Evaluation of initial ejection properties> To enhance visibility, a cationic dye (Rhodamine B, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was blended into each pretreatment liquid in an amount of 0.5% by mass relative to the total mass of the pretreatment liquid. Next, the pretreatment liquid containing the dye was filled into an inkjet ejection device equipped with a Kyocera inkjet head "KJ4B-1200" (design resolution: 1,200 dpi, nozzle diameter: 20 μm), and the pretreatment liquid in the inkjet head was pressurized until it oozed out of the nozzles of the inkjet head. After that, the pretreatment liquid adhering to the nozzle plate was wiped off, and a nozzle check pattern was immediately printed at a frequency of 40 kHz. The initial ejection performance was evaluated by visually counting the number of missing nozzles in the nozzle check pattern. The evaluation criteria were as follows: ◎, ○, and △ were considered usable. However, for pretreatment liquids that were rated "X" in the evaluation of blend stability, the initial ejection properties were not evaluated. ◎: No nozzle missing at all ○: The number of missing nozzles was 1 to 4 △: The number of missing nozzles was 5 to 9 ×: The number of missing nozzles was 10 or more.

[0144] <Evaluation 3: Evaluation of continuous ejection> After printing the nozzle check pattern in Evaluation 2 above, 10 solid images (100% printing rate) measuring 10 cm wide x 30 cm long were printed consecutively. A nozzle check pattern was then printed again, and the number of missing nozzles increased from the number of missing nozzles in the initial ejection performance evaluation was visually counted to evaluate continuous ejection performance. The evaluation criteria were as follows, with ◎, ○, and △ being considered usable. However, the evaluation of continuous ejection property was carried out only for pretreatment liquids that were determined to be practically usable in the evaluation of blend stability and the evaluation of initial ejection property described above. ◎: The number of clogged nozzles was the same as the number of clogged nozzles in the initial ejection performance evaluation. ○: The number of missing nozzles increased by 1 to 4 from the number of missing nozzles in the initial ejection performance evaluation. △: The number of missing nozzles increased by 5 to 9 from the number of missing nozzles in the initial ejection performance evaluation. ×: The number of clogged nozzles increased by 10 or more from the number of clogged nozzles in the initial ejection performance evaluation.

[0145] <Evaluation 4: Evaluation of print quality (white areas, dot shape)> Based on the above method, solid patch image prints produced by varying the conveyor drive speed were visually observed to confirm the degree of whiteout. Additionally, the dot shapes in the 10-20% coverage area of ​​the gradation image prints produced by varying the conveyor drive speed were observed at 200x magnification using an optical microscope. Furthermore, the prints of character images produced by varying the conveyor drive speed were visually inspected from the ink layer side (printed surface) to determine whether all characters were legible. The print quality was then comprehensively evaluated based on the degree of whiteout, dot shape, and character legibility. The evaluation criteria were as follows, with ◎, ○, and △ being considered usable. Table 3 lists the results for the color with the worst evaluation among the four colors evaluated. ◎: Printed at a conveyor speed of 75 m / min, and no white spots, irregular dot shapes, or illegible characters were found in any color. ○: In prints printed at a conveyor speed of 75 m / min, there were colors in which one or more of the following were confirmed: white spots, irregular dot shapes, and illegible characters. However, in prints printed at a conveyor speed of 50 m / min, there were no white spots, irregular dot shapes, or illegible characters in any of the colors. △: In prints printed at a conveyor speed of 50 m / min, there were colors in which one or more of the following were confirmed: white spots, irregular dot shapes, and illegible characters. However, in prints printed at a conveyor speed of 25 m / min, there were no white spots, irregular dot shapes, or illegible characters in any of the colors. ×: In prints printed at a conveyor drive speed of 25 m / min, there was a color in which one or more of the following was confirmed: white spots, irregular dot shapes, and illegible characters.

[0146] <Evaluation 5: Evaluation of abrasion resistance> Based on the above method, solid patch image prints were prepared at a conveyor speed of 50 m / min. Then, 2 cm x 20 cm test pieces were cut from the resulting prints for each color and placed in a Tester Sangyo AB-301 Gakushin-type abrasion fastness tester. Next, a test attachment white cotton cloth (Kanakin No. 3) was attached to the abrader (weight: 200 g), and the abrader was subjected to a predetermined number of vibrations while varying the load applied. After the abrasion test, the condition of the print surface and the degree of coloring of the cotton cloth were visually inspected to evaluate abrasion resistance. The evaluation criteria were as follows: ◎, ○, and △ were deemed usable, and ◎ and ○ were deemed particularly suitable for use. Table 3 lists the results for the color with the worst evaluation among the four colors evaluated. ◎: Even after placing a 300g weight on the friction element (load 500g) and shaking it 50 times, there were no scratches on the printed surface and no coloring was observed on the cotton cloth. ○: After a 300g weight was placed on the friction element (load 500g) and the friction element was shaken 25 times, there were no scratches on the printed surface and no discoloration of the cotton cloth was observed. However, after shaking the friction element 50 times under the same load conditions, scratches on the printed surface and / or discoloration of the cotton cloth were observed. △: After shaking the friction element 25 times without placing a weight (200 g load), there were no scratches on the printed surface and no discoloration of the cotton cloth was observed. However, after shaking the friction element 25 times with a 300 g weight (500 g in total), scratches on the printed surface and / or discoloration of the cotton cloth were observed. ×: After shaking the friction element 25 times without placing a weight (200 g load), scratches were observed on the printed surface and / or coloring of the cotton cloth was observed.

[0147] [Table 3]

[0148] [Table 3]

[0149] [Table 3]

[0150] As is clear from Table 3, the combinations of pretreatment liquids 1 to 62 that satisfy the above-mentioned requirements were confirmed to have practically usable quality in all evaluation items, including blending stability during production, initial ejection stability, continuous ejection stability, and print quality of printed matter. Furthermore, it was confirmed that when a certain amount or more of nonionic resin (R) and / or anionic resin, which are resin particles, is contained, or when a crosslinking agent is contained, the abrasion resistance of the printed matter is also particularly favorable for use.

[0151] In contrast, in the pretreatment liquid 63 that does not contain a flocculant, the pretreatment liquid 64 that does not contain the water-soluble organic solvent S1, the pretreatment liquids 65 and 66 that do not contain the water-soluble organic solvent S2, the pretreatment liquids 69 and 70 that do not contain the nonionic resin (R), the pretreatment liquid 67 in which the value expressed by WR / WS2 is less than 0.03, and the pretreatment liquid 68 in which the value expressed by WR / WS2 is greater than 10, one or more of the evaluated items did not reach a practically usable level. This result shows that if even one of the above requirements is missing, the above-mentioned effects cannot be achieved.

Claims

1. A pretreatment liquid for use with an aqueous inkjet ink, the pretreatment liquid comprising a flocculant, a resin (excluding cationic resins), a water-soluble organic solvent, and water, The resin contains a nonionic resin (R), the water-soluble organic solvent comprises a water-soluble organic solvent (S1) having an octanol / water partition coefficient of −1.60 or more but less than −0.20, and a water-soluble organic solvent (S2) having an octanol / water partition coefficient of −0.20 to 1.00; The pretreatment liquid has a value expressed by WR / WS2 of 0.03 to 10, where WR (g) is the content of the nonionic resin (R) contained in 100 g of the pretreatment liquid and WS2 is the content of the water-soluble organic solvent (S2).

2. 2. The pretreatment solution according to claim 1, wherein a ratio of a mass content of the water-soluble organic solvent (S2) to a total mass content of the water-soluble organic solvent (S1) and the water-soluble organic solvent (S2) is 0.05 to 0.

5.

3. 3. The pretreatment liquid according to claim 1, wherein the nonionic resin (R) is a water-soluble resin.

4. Further comprising a crosslinking agent, The pretreatment liquid according to claim 1 or 2, wherein the crosslinking agent comprises a polyhydrazide compound.

5. The pretreatment liquid according to claim 1 or 2, which is used in an inkjet printing method.

6. An ink set comprising the pretreatment liquid according to claim 1 or 2 and an aqueous inkjet ink containing a pigment, a water-soluble organic solvent, and water.

7. A printed matter obtained by printing the ink set according to claim 6 on a printing substrate.

Images