Pretreatment liquid, ink set, and printed matter

Abstract

Disclosed is a pretreatment liquid which contains a flocculant, a resin, a water-soluble organic solvent, and water, and is used together with an aqueous inkjet ink. In the pretreatment liquid: the resin contains a nonionic resin (R); the water-soluble organic solvent contains a water-soluble organic solvent (S1) that has an octanol / water partition coefficient of not less than -1.60 but less than 0.20, and a water-soluble organic solvent (S2) that has an octanol / water partition coefficient of -0.20 to 1.00; and if WR (g) is the content of the nonionic resin (R) and WS2 is the content of the water-soluble organic solvent (S2) in 100 g of the pretreatment liquid, the value represented by WR / WS2 is 0.03 to 10.

Description

Pretreatment liquid, ink set, and printed matter

[0001] An embodiment of the present invention relates to a pretreatment liquid, an ink set including the pretreatment liquid, and a printed matter produced using the ink set.

[0002] Inkjet printing is a method of producing printed matter with characters and / or images by ejecting and depositing ink droplets from fine nozzles onto a substrate. The term "image" also includes solid images (images printed at 100% coverage so as to completely cover the surface of the printing 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 possibility of downsizing the printing device, 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 office and home applications but also in industrial applications. In addition, inks used in industrial inkjet printing have traditionally been solvent-based or UV-curable inks. However, in recent years, there has been an increasing demand for water-based inks, primarily composed of water, 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, as well as 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 preventing color bleeding. Typically, the pretreatment liquid contains a component (a flocculant) that can intentionally cause aggregation of solid components (pigments and / or resins) present in the aqueous inkjet ink or thicken the aqueous inkjet ink. Additionally, adding a resin different from the flocculant to the pretreatment liquid can also improve the properties of the printed material, such as improving abrasion resistance and providing substrate adhesion.

[0004] Meanwhile, methods for applying a pretreatment liquid used with aqueous inkjet inks, such as inkjet printing, that involve non-contact printing on a printing substrate, have been investigated. This method allows the amount of pretreatment liquid applied to be controlled according to the coverage rate of the aqueous inkjet ink, making it easy to adjust the print quality. It also allows for a more compact printing apparatus. The pretreatment liquid applied in inkjet printing must have the ability to aggregate solid components in the aqueous inkjet ink, the ability to thicken the ink, and abrasion resistance. In addition to these properties, the pretreatment liquid must also have printability from an inkjet head, as exemplified by ejection stability. Therefore, formulating a pretreatment liquid applied in 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), which contains a water-soluble resin having cationic properties as an aggregating agent, and a polyether polyol-based urethane resin or the like as a thickener (a resin having a thickening effect). 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 or the printing conditions.

[0006] Furthermore, Patent Document 4 discloses a surface treatment liquid composition (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, as a result of evaluating the pretreatment liquid specifically disclosed in the examples of Patent Document 4, it was found that the continuous ejection stability may not be good depending on the printing conditions, such as the occurrence of nozzle failure (a phenomenon in which the aqueous inkjet ink is not ejected from the nozzle) when continuously ejected.

[0007] As described above, among the conventional pretreatment liquids that are applied in inkjet printing methods and used together with aqueous inkjet inks, there are no fully satisfactory pretreatment liquids yet. Therefore, there is a need for further investigation into pretreatment liquids that can produce printed matter with excellent print quality, that are excellent in ejection stability at the beginning of printing and in continuous ejection stability, and that also have good blending stability during production.

[0008] JP 2004-276253 A JP 2011-56884 A JP 2019-143058 A JP 2021-790 A

[0009] The present invention has been made to solve the above-mentioned problems, and an object of one embodiment is to provide a pretreatment liquid to be used with an aqueous inkjet ink, which produces 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 embodiment of the present invention aims to provide a pretreatment liquid that not only has the above-mentioned effects but also has excellent abrasion resistance of printed matter. Yet another embodiment of the present invention aims to provide an ink set that includes a pretreatment liquid having the above-mentioned effects and an aqueous inkjet ink, which ink set produces printed matter with excellent print quality even when printing at high speed.

[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, embodiments of the present invention relate to the following. However, the present invention is not limited to the following embodiments and includes various embodiments. One embodiment of the present invention relates to a pretreatment liquid that contains a flocculant, a resin (excluding cationic resins), a water-soluble organic solvent, and water, and is used together with an aqueous inkjet ink, wherein the resin contains a nonionic resin (R), and the water-soluble organic solvent contains 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, and wherein, when the content of the nonionic resin (R) contained 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 0.03 to 10. Another embodiment of the present invention relates to an ink set that contains the pretreatment liquid of the above embodiment and an aqueous inkjet ink containing a pigment, a water-soluble organic solvent, and water. Yet another embodiment of the present invention relates to a printed matter formed using the ink set of the above embodiment.

[0012] According to an embodiment of the present invention, it is 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 exhibits good blending stability during production. Furthermore, according to an embodiment of the present invention, it is possible to provide a pretreatment liquid to be used with an aqueous inkjet ink, which can produce printed matter with excellent abrasion resistance in addition to the effects described above. Furthermore, according to an embodiment of the present invention, it is possible to provide an ink set containing the pretreatment liquid and an aqueous inkjet ink, which has the effects described above and can produce printed matter with good print quality, even when printing at high speed.

[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 on 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 the print quality of the resulting print. A known solution to this degradation in print quality is the combined use of a pretreatment liquid containing a flocculant 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 formed by the pretreatment liquid (hereinafter referred to as the pretreatment layer). By printing using this method, the flocculant present in the pretreatment layer disrupts the dispersion of solid components contained in the aqueous inkjet ink and / or acts to rapidly thicken 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 that allows it to 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 non-ionic 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 the blend stability of the pretreatment liquid 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, there is a risk that the nonionic resin molecules will aggregate with each other. Furthermore, if strong association forces act between nonionic resin molecules, the viscoelasticity of the pretreatment liquid will become too high, causing problems such as the pretreatment liquid not being ejected at the start of printing or difficulty in continuous ejection. Furthermore, there is a risk that the aggregated nonionic resin will appear as a precipitate or turbidity during the production of the pretreatment liquid.

[0017] Therefore, in an embodiment of the present invention, a water-soluble organic solvent (S2) having an octanol / water partition coefficient of -0.20 to 1.00 is blended in a predetermined amount with the nonionic resin (R). The water-soluble organic solvent (S2), which is relatively hydrophobic, acts on the association sites of the hydrophobic segments in the nonionic resin (R), thereby appropriately loosening the association sites and suppressing an increase in viscoelasticity. This is presumably to improve initial ejection stability, continuous ejection stability, and blending stability during production. In particular, when the content of the nonionic resin (R) contained in 100 g of the pretreatment liquid is WR (g) and the content of the water-soluble organic solvent (S2) is WS2, if the value expressed by WR / WS2 is 0.03 or greater, the effects of the water-soluble organic solvent (S2) described above are fully manifested, and initial ejection stability, continuous ejection stability, and blending stability during production are easily improved. Furthermore, by setting the value of WR / WS2 to 10 or less, the associated portions are prevented from being excessively loosened by the water-soluble organic solvent (S2), the pretreatment liquid has suitable viscoelasticity, and continuous, stable ejection can be easily achieved.

[0018] On the other hand, as described above, the water-soluble organic solvent (S2) is highly hydrophobic. Therefore, the water-soluble organic solvent (S2) may have low affinity with the water and hydrophilic materials, such as a flocculant, present in the pretreatment liquid, and may not be uniformly present in the pretreatment liquid. In such cases, the effects of the water-soluble organic solvent (S2) are only exerted to a limited extent within the pretreatment liquid, and there is a risk that the initial ejection stability and continuous ejection stability may 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] In contrast, in an embodiment of 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. By blending the water-soluble organic solvent (S1), the affinity between the water-soluble organic solvent (S2) and the water and hydrophilic material can 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 between the water-soluble organic solvent (S2) and the water and hydrophilic material further improves blend stability during the production of the pretreatment liquid.

[0020] Furthermore, the affinity-improving effect of the water-soluble organic solvent (S1) allows the hydrophilic material, the flocculant, to be uniformly present in the pretreatment liquid containing water as the main component, which prevents the action of the flocculant from being exerted unevenly and limitedly within the pretreatment layer, making it possible to obtain printed matter with excellent print quality.

[0021] In addition, when the water-soluble organic solvent (S2) is not used and only the water-soluble organic solvent (S1) is used, the highly hydrophilic water-soluble organic solvent (S1) cannot act on the association portion of the hydrophobic segment of the nonionic resin (R), making it difficult to improve the initial ejection stability and continuous ejection stability. On the other hand, when a water-soluble organic solvent having an octanol / water partition coefficient of more than 1.00 is used, the association portion of the hydrophobic segment of the nonionic resin (R) tends to be excessively loosened. When the above-mentioned association portion is excessively loosened, it becomes difficult to ensure the initial ejection stability and continuous ejection stability, and the blending stability when producing the pretreatment liquid also tends to deteriorate.

[0022] As described above, by configuring a pretreatment liquid according to the embodiments of the present invention as a pretreatment liquid to be used together with an aqueous inkjet ink, it is possible 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.

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

[0024] <Aggregating Agent> The pretreatment liquid of this embodiment contains an aggregating agent. Furthermore, from the viewpoint of simultaneously achieving all of continuous ejection stability, print image quality, and blending stability during production, the aggregating agent preferably contains at least one or more selected from the group consisting of polyvalent metal salts and cationic resins. As described above, the aggregating agent can disrupt the dispersion state of solid components contained in the aqueous inkjet ink and / or can rapidly thicken the aqueous inkjet ink, thereby enabling improvement in the print image quality of the printed matter obtained after printing.

[0025] (Polyvalent Metal Salt) When the pretreatment liquid of this embodiment contains a polyvalent metal salt as an aggregating agent, the polyvalent metal salt used is not particularly limited. The polyvalent metal salt is composed of a polyvalent metal ion and a counter anion. The combination of these is not particularly limited, and any conventionally known combination of 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. When a polyvalent metal salt composed of divalent metal ions is used, printed materials of excellent print quality, free of whiteout and color bleeding, can be easily obtained 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 of exceptional print quality, free of whiteout and color bleeding.

[0026] On the other hand, examples of counter anions when calcium ions are selected as the polyvalent metal ions 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 composed of calcium ions and counter anions; specifically, they are the solubility values ​​of the anhydrous calcium salts in 100 g of water at 20°C.

[0027] When an aqueous inkjet ink is printed on a dried pretreatment layer, forming the pretreatment layer using a pretreatment liquid containing an aggregating agent with a specific solubility prevents the rate of redissolution and release of the aqueous inkjet ink into droplets from becoming too high, improving the print quality of the printed matter and easily producing a printed matter with excellent abrasion resistance and adhesion. From this perspective, 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 whose solubility in 100 g of water at 20°C is 1 to 70 g. The solubility of the polyvalent metal salt used is more preferably 2 to 55 g, even more preferably 4 to 40 g, and particularly preferably 8 to 25 g. However, the above solubility refers to the value in the anhydrous salt form.

[0028] From the above viewpoints, when a polyvalent metal salt is used as the flocculant in the pretreatment solution of this embodiment, one or more calcium salts 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 used. 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 polyvalent metal salt in an anhydrous form. When a polyvalent metal salt containing a hydrate is used, the content of the polyvalent metal salt is calculated by excluding the mass of water in the hydrate.

[0030] (Cationic Resin) The pretreatment liquid of this embodiment may use a cationic resin as the flocculant. In this disclosure, 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 equivalent number of the cationic groups is greater than the molar equivalent number of the anionic groups. Specifically, in this disclosure, a resin having a cationic group millimole equivalent number greater than 0.4 mmoleq. / g and a cationic group millimole equivalent number greater than the anionic group millimole equivalent number is referred to as a "cationic resin."

[0031] The cationic group millimole equivalent is a value obtained 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 value is the sum of the products of the number of millimoles contained in 1 g of resin and the valence calculated for each cationic group). 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 read as "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, an imidazole group, etc. Examples of the anionic group include a carboxy group, a sulfo group, a sulfino group, a phosphate group (phosphoric acid group), a phosphoryl group, etc.

[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, the cationic resin is preferably a water-soluble resin. When a water-soluble resin is used, printed matter with excellent print quality and abrasion resistance is easily obtained, and further, a pretreatment liquid with good blend stability during production tends to be easily obtained. 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 preferred. When a resin containing a diallylammonium structural unit is used, a 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 is excellent, making it easy to obtain printed matter free of whiteout and color bleeding. Furthermore, the quaternary ammonium groups in the resin 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] Examples of commercially available 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, FCA1002L, FCA1003L, FCA5000L, ZCA1000L, ZCA1001L, and ZCA1002L (manufactured by Senka Corporation).

[0037] The cationic resin may be used alone or in combination of two or more types. From the viewpoint of achieving both good print image 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% by mass, more preferably 2 to 20% by mass, and particularly preferably 2.5 to 15% by mass.

[0038] (Organic Acid) The pretreatment liquid of this embodiment may contain an organic acid as a flocculant. When the pretreatment liquid 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 from the viewpoint of obtaining printed matter with excellent print quality. Furthermore, from the same viewpoint, i.e., from the viewpoint of improving the print quality of printed matter, compounds having multiple of the above-listed acid groups are 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. 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% by mass, and more preferably 3 to 20% by mass.

[0040] <Resin (excluding cationic resin)> The pretreatment liquid of this embodiment may contain at least one type of resin. However, the resin is excluding cationic resin, i.e., a resin different from cationic resin. As described above, the resin needs to be able to exist stably even in the presence of a flocculant, so a nonionic resin (R) that does not have ionicity is used.

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

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

[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 ejection stability and continuous ejection 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 the ejection stability. As described above, if the association force is too strong, the initial ejection stability, continuous ejection 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 the present disclosure, "urethane (urea)" refers to urethane and / or urethane urea, "(meth)acrylic" refers to acrylic and / or methacrylic, and "(maleic anhydride)" refers to maleic acid and / or maleic anhydride. In the present disclosure, "(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 anhydride as the polymerizable monomer are not included in the "(meth)acrylic resin" in the present disclosure. In the present disclosure, "maleic anhydride (resin)" refers to a resin using at least maleic anhydride as a polymerizable monomer. The maleic acid (anhydride) resin may further contain, as the polymerizable monomer, one or more 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 disclosure, a resin having 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 having a solubility of less than 1 g is referred to as a "water-insoluble resin." Of the water-insoluble resins, a resin that is dispersed in water in a particulate form and has a volume-based median diameter (also referred to as "D50" in this disclosure) of 10 to 1,000 nm is referred to as a "resin microparticle." In addition, D50 in this disclosure is a value measured in an environment of 25°C 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.

[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, thereby improving the print quality of the printed matter.

[0048] In the present disclosure, 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 LTD.).

[0049] Furthermore, when the pretreatment liquid of this embodiment contains a water-soluble resin as the nonionic resin (R), by using a resin having dispersion stabilizing ability as the water-soluble resin, it becomes possible to further use an anionic resin, as described below, in combination. 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 disclosure, a "resin having dispersion stabilizing ability" refers to a resin containing a moiety that adsorbs to a material to be dispersed (an anionic resin in the above-mentioned example), i.e., a certain amount of aromatic ring structures. Specifically, it refers to a resin in which the content of aromatic ring structures represented by the following formula 1 is 10% by mass or more. The content of aromatic ring structures in this resin is preferably 15% by mass or more, and particularly preferably 20% by mass or more.

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

[0052] In the above formula 1, ni is the number of moles of the aromatic ring structure contained in a polymerizable monomer having an aromatic ring structure among the polymerizable monomers constituting the resin; for example, ni = 1 in the case of styrene and ni = 2 in the case of 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, 2015; BYKJET-9151 (manufactured by BYK-Chemie). The blending amount of the resin that has dispersion stabilizing ability and is a nonionic resin (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 of water-soluble resin 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). By using resin fine particles, the abrasion resistance of the resulting printed matter can be improved. 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 resin 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 of resin fine particles may be used, or two or more types may be used in combination. From the viewpoint of simultaneously achieving the initial ejection stability and continuous ejection stability of the pretreatment liquid, as well as the abrasion resistance of the printed matter, the content of the resin fine particles that are the nonionic resin (R) relative to the total mass of the pretreatment liquid is preferably 0.1 to 20 mass%, and 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 the water-soluble resin and resin fine particles are used in combination as the nonionic resin (R), the mass ratio of the content of the resin fine particles to the content of the water-soluble resin (amount of resin fine particles / amount 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 disclosure, the term "anionic resin" refers to a resin having an anionic group millimole equivalent greater than 0.4 mmoleq. / 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 the nonionic resin (R), which 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 resins that can be used as the nonionic resin (R) can also be used as anionic resins. Specific examples of resins that can be used as the anionic resin include urethane (urea) resins, (meth)acrylic resins, (maleic anhydride) resins, polyester resins, and polyolefin resins. Among these, one or more resins selected from the group consisting of urethane (urea) resins and (meth)acrylic resins are preferably used as the anionic resin. Furthermore, it is particularly preferable to use a (meth)acrylic resin as the anionic resin. By using a (meth)acrylic resin as the anionic resin, it becomes particularly easy to achieve both adhesion to the printing substrate and abrasion resistance of the printed matter.

[0062] The anionic resin may preferably be used in the form of resin fine particles. This is because all of the properties of the pretreatment liquid, such as the initial ejection stability and continuous ejection stability, blending stability during production, adhesion to the printing substrate, and abrasion resistance of the printed matter, can be easily improved. In this case, from the viewpoint of simultaneously achieving the initial ejection stability and continuous ejection stability of the pretreatment liquid and the abrasion resistance of the printed matter, the content of the anionic resin fine particles relative to the total amount of the pretreatment liquid is preferably 0.1 to 20% by mass, more preferably 0.5 to 15% by mass, and particularly preferably 1 to 10% by mass.

[0063] <Water-Soluble Organic Solvent (S)> The pretreatment liquid 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 the present disclosure, for example, a “ClogP” value obtained using “ChemDraw Professional Ver. 16.0” manufactured by PerkinElmer can be used.

[0064] In addition, in the present disclosure, 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.

[0065] (Water-soluble organic solvent (S1)) The water-soluble organic solvent (S1) contained in the pre-treatment 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 pre-treatment 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.

[0066] The octanol / water partition coefficient of the water-soluble organic solvent (S1) may be −1.40 or more, −1.20 or more, or −1.00 or more, and may be less than −0.20, −0.24 or less, or −0.30 or less. In some embodiments, the octanol / water partition coefficient of the water-soluble organic solvent (S1) is more preferably −1.40 to −0.30 (in the range of −1.40 or more and −0.30 or less), and particularly preferably −1.20 to −0.40. By adjusting the octanol / water partition coefficient of the water-soluble organic solvent (S1) to fall within the above range, the affinity of the water-soluble organic solvent (S2) with water and the hydrophilic material is increased, allowing the pretreatment liquid to be uniform, 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.

[0067] 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 %, relative to the total amount of the pretreatment liquid. Furthermore, 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 %, relative to the sum of the contents of the water-soluble organic solvent (S1) and the water-soluble organic solvent (S2). By ensuring that the content of the water-soluble organic solvent (S1) falls 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 near the nozzle, the flocculant will not precipitate, and a good discharge state can be maintained.

[0068] Specific 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 suitable 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 values ​​in parentheses indicate the octanol / water partition coefficient of each water-soluble organic solvent.

[0069] (Water-soluble organic solvent (S2)) The water-soluble organic solvent (S2) contained in the pretreatment liquid of this embodiment may be any water-soluble organic solvent having an octanol / water partition coefficient of −0.20 to 1.00, and any compound can be used. The pretreatment liquid 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.

[0070] The octanol / water partition coefficient of the water-soluble organic solvent (S2) may be -0.20 or more, -0.02 or more, 0.10 or more, or 0.3 or more, and may be 1.00 or less, 0.90 or less, or 0.80 or less. In some embodiments, the octanol / water partition coefficient of the water-soluble organic solvent (S2) is more preferably 0.10 to 0.90 (in the range of 0.10 or more and 0.90 or less), even more preferably 0.40 to 0.80, and particularly preferably 0.50 to 0.75. 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 easily improved.

[0071] Furthermore, in some embodiments, it is preferable to adjust the difference between the octanol / water partition coefficient of the water-soluble organic solvent (S1) and the octanol / water partition coefficient of the water-soluble organic solvent (S2). Specifically, when the octanol / water partition coefficient of the compound with the smallest octanol / water partition coefficient among the water-soluble organic solvents (S1) contained in the pretreatment solution of this embodiment is defined as Log PS1, and the octanol / water partition coefficient of the compound with the largest octanol / water partition coefficient among the water-soluble organic solvents (S2) contained in the pretreatment solution is defined as Log PS2, the difference between Log PS2 and Log PS1 (Log PS2 - Log PS1) is preferably 0.85 to 2.35. The value of the difference between Log PS2 and Log PS1 is more preferably 1.10 to 2.20, and particularly preferably 1.55 to 1.85. By adjusting the value of the difference to fall within the above-mentioned range, each of the water-soluble organic solvent (S1) and the water-soluble organic solvent (S2) can favorably exhibit the above-mentioned effects, and in particular, the initial ejection stability, continuous ejection stability, and blending stability during production are improved.

[0072] 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) in 100 g of the pretreatment liquid is WS2, the value represented by WR / WS2 may be 0.03 or more, 0.08 or more, 0.1 or more, or 0.2 or more. Furthermore, the value may be 10 or less, 5 or less, 3.5 or less, or 2 or less. In some embodiments, the value represented by WR / WS2 is preferably 0.03 to 10 (a range of 0.03 or more and 10 or less), and particularly preferably 0.1 to 2. By adjusting the value represented by WR / WS2 within the above range, the association state between the hydrophobic segments of the nonionic resin (R) can be appropriately loosened, thereby improving the continuous discharge stability of the pretreatment liquid and the blending stability during production.

[0073] Furthermore, in the pretreatment liquid of this embodiment, the mass ratio of the content of the water-soluble organic solvent (S2) to the total content of the water-soluble organic solvent (S1) and the water-soluble organic solvent (S2) is preferably 0.05 to 0.5. This satisfies 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 achieving good initial ejection stability, continuous ejection stability, and blending stability during production.

[0074] Furthermore, when TS1 is the product of the content of the water-soluble organic solvent (S1) and the value obtained by subtracting −0.2 from the value of the octanol / water partition coefficient of the water-soluble organic solvent (S1), and TS2 is the product of the content of the water-soluble organic solvent (S2) and the value obtained by adding 0.2 to the value of the octanol / water partition coefficient of the water-soluble organic solvent (S2), the value expressed by TS1 / TS2 is preferably in the range of 0.2 to 4.8. The value expressed by TS1 / TS2 is preferably 0.2 to 4.8, more preferably 0.6 to 4.0, and particularly preferably 1.0 to 3.6. When the value is within the above-mentioned range, the water-soluble organic solvent (S1), the water-soluble organic solvent (S2), the flocculant, and water all have favorable affinities, and continuous discharge stability, print image quality of printed matter, and blending stability during production are improved.

[0075] In the pretreatment liquid of this embodiment, the content of the water-soluble organic solvent (S2) is preferably 0.1 to 15% by mass, and more preferably 1 to 10% by mass, relative to the total amount of the pretreatment liquid. Furthermore, the content of the water-soluble organic solvent (S2) is preferably 5 to 50% by mass, more preferably 7 to 40% by mass, and particularly preferably 9 to 35% by mass, relative to 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.

[0076] 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 (0.03), ethylene glycol monoisopropyl ether (0.09), diethylene glycol ethyl methyl ether (0.13), dipropylene glycol monomethyl ether (0.04), 2-methyl-2,4-pentanediol (-0.04), 1,2-pentanediol (0.00), ethylene glycol monoallyl ether (0.03), ethylene glycol monoisopropyl ether (0.09), diethylene glycol ethyl methyl ether (0.13), dipropylene glycol monomethyl ether (0.04), 2-methyl-2,4-pentanediol (-0.04), 1,2-pentanediol (0.00), ethylene glycol monoallyl ether (0.04 ...4), diethylene glycol ethyl methyl ether (0.13), dipropylene glycol monomethyl ether (0.04), 2-methyl-2,4-pentanediol (-0.04), 1,2-pentanediol (0.00), 2-methyl-2,4-pentanediol (-0.04), 2-methyl-2,4-pentanediol (-0.04), 2-methyl-2,4-pent Examples of suitable water-soluble organic solvents include, but are not limited to, 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 values ​​in parentheses indicate the octanol / water partition coefficient of each water-soluble organic solvent.

[0077] (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 as "other water-soluble organic solvents" in the present disclosure). Furthermore, 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.

[0078] 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.

[0079] When the pretreatment liquid of this embodiment contains another water-soluble organic solvent, the content thereof is preferably 0.01 to 5% by mass based on the total amount of the pretreatment liquid.

[0080] The total content of the water-soluble organic solvents 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.

[0081] <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 amount 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, the nonionic resin (R), the water-soluble organic solvent (S1), and the water-soluble organic solvent (S2), and for improving the blending stability during production and storage stability of the pretreatment liquid.

[0082] <Other Materials> 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.

[0083] (Surfactant) The pretreatment liquid of this embodiment may further contain a surfactant. Examples of the surfactant that can be used 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 of two or more.

[0084] Among these, it is preferable to use one or more surfactants selected from the group consisting of acetylene diol-based surfactants and siloxane-based 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.

[0085] 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), 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.).

[0086] 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, 8032 ADDITIVE, 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 Twin4100, 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.).

[0087] (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 an apparatus for applying the pretreatment liquid, suppress pH fluctuations over time, maintain the performance of the pretreatment liquid over the long term, and maintain and improve its storage stability and ejection stability.

[0088] Specifically, when the pretreatment liquid is made basic, 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. When the pretreatment liquid is made acidic, 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.

[0089] 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 solution. 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 inhibited.

[0090] (Crosslinking Agent) The pretreatment liquid of this embodiment may further contain a crosslinking agent. By using a crosslinking agent in the pretreatment liquid, the adhesion between the printing substrate and the pretreatment layer is improved, and the abrasion resistance of the printed matter can also be improved, although the detailed mechanism is unknown.

[0091] The crosslinking agent contained in the pretreatment liquid can be a material capable of exhibiting the above-mentioned effects, such as a polyhydrazide-based compound, a (poly)carbodiimide-based compound, or a polyoxazoline-based compound. The term "(poly)carbodiimide-based compound" refers to a carbodiimide-based compound and / or a polycarbodiimide-based compound. Among these, a polyhydrazide-based compound is preferably used. Polyhydrazide-based 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, allowing the crosslinking reaction to proceed after application to the printing substrate. These advantages, for example, can improve the abrasion resistance of printed materials without adversely affecting the initial ejection stability, continuous ejection stability, or blending stability during production.

[0092] 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.

[0093] The blending amount of the crosslinking agent is preferably 0.01 to 5 mass %, and more preferably 0.05 to 3 mass %, relative to 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 ejection stability, continuous ejection stability, and blending stability during production, without inhibiting the effects of the flocculant and nonionic resin.

[0094] <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 satisfying the above viscosity range can be stably ejected from an inkjet head, resulting in printed matter with excellent print image quality and adhesion, and also exhibiting good initial ejection stability and continuous ejection stability. The viscosity of the pretreatment liquid can be measured using, for example, an E-type viscometer (TVE25L viscometer manufactured by Toki Sangyo Co., Ltd.).

[0095] Furthermore, from the viewpoint of imparting favorable wetting and spreading properties to a non-permeable substrate and forming a uniform and even pretreatment layer to obtain a printed matter with excellent print quality, 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. Note that the static surface tension in the present disclosure 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.

[0096] <Method for Producing Pretreatment Liquid> The pretreatment liquid of this embodiment can be produced by adding, for example, a flocculant, a nonionic resin (R), a water-soluble organic solvent (S1), a water-soluble organic solvent (S2), water, and, if necessary, materials such as an anionic resin, a surfactant, a pH adjuster, and a crosslinker, followed by stirring and mixing, and then filtering as necessary. 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 ability and then mix it with other materials, from the perspective of improving blend stability. Note that, when stirring and mixing, heating may be performed in the range of 35 to 100°C as needed.

[0097] <Aqueous Inkjet Ink> The pretreatment liquid of this embodiment can be combined with one or more aqueous inkjet inks and used in the form of an ink set. That is, one embodiment of the present invention relates to an ink set comprising the pretreatment liquid of this embodiment and an aqueous inkjet ink. Preferably, the aqueous inkjet ink contains a pigment, a resin, and water, and may further contain a water-soluble organic solvent, a surfactant, and the like. The aqueous inkjet ink used in combination with the pretreatment liquid of this embodiment may have a composition known in the technical field. Although not particularly limited, a preferred configuration will be described below as a specific example.

[0098] The pigment contained in the aqueous inkjet ink used in combination with the pretreatment liquid of this embodiment may be a blue pigment such as C.I. Pigment Blue 15:3 or 15:4; a red pigment such as C.I. Pigment Red 122, 150, 166, 185, 202, 209, 266, 269, or 282, or C.I. Pigment Violet 19; a yellow pigment such as C.I. 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; and these pigments are preferably used. When these pigments are used, printed matter with excellent color development and lightfastness and excellent print quality tends to be easily obtained.

[0099] 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 (a layer formed by the aqueous inkjet ink) to the pretreatment layer. It is particularly preferable that the aqueous inkjet ink contains at least a binder resin. It is also possible to impart 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.

[0100] 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.

[0101] In one embodiment, the aqueous inkjet ink preferably contains a resin selected from the group consisting of (meth)acrylic resins, urethane (urea) resins, and polyester resins, and polyolefin resin microparticles. In this case, the amount of polyolefin resin microparticles relative to the amount of the resin selected from the group consisting of (meth)acrylic resins, urethane (urea) resins, and polyester resins is preferably 10 to 100% by mass, and more preferably 20 to 80% by mass. By keeping the blending ratio within this range, the functions of the resin selected from the group consisting of (meth)acrylic resins, urethane (urea) resins, and polyester resins are not impaired, and it is easy to suitably improve all of the print image quality during high-speed printing, abrasion resistance, and adhesion between the ink layer and the pretreatment layer.

[0102] The pigment dispersing resin and the binder resin may each have an acid group, and the acid group may be neutralized with a neutralizing agent. 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. These can be preferably used.

[0103] The aqueous inkjet ink used in combination with the pretreatment liquid of this embodiment preferably contains a water-soluble organic solvent. In this case, the water-soluble organic solvent to be used is preferably selected taking into consideration its boiling point at 1 atmospheric pressure. In some embodiments, the weighted average boiling point at 1 atmospheric pressure of the water-soluble organic solvent contained in the aqueous inkjet ink is preferably 145 to 215°C, more preferably 150 to 200°C, and particularly preferably 155 to 190°C. By adjusting the weighted average boiling point of the water-soluble organic solvent to be used so that it falls within the above range, when combined with the pretreatment liquid of this embodiment, it is possible to easily obtain printed matter with excellent print quality even in high-speed printing, and it is also possible to easily obtain excellent jetting stability of the aqueous inkjet ink. Furthermore, from the viewpoint of easily obtaining printed matter with excellent print quality and good abrasion resistance without color bleeding or the like when combined with the pretreatment liquid of this embodiment, it is preferable that the amount of the water-soluble organic solvent having a boiling point of 220°C or higher at 1 atmospheric pressure be 5% by mass or less (or may be 0% by mass) relative to the total amount of the aqueous inkjet ink. The amount of the water-soluble organic solvent having a boiling point of 220°C or higher at 1 atmospheric pressure is more preferably 2% by mass or less (may be 0% by mass) and particularly preferably 1% by mass or less (may be 0% by mass) relative to the total amount of the aqueous inkjet ink.

[0104] When the aqueous inkjet ink contains a water-soluble organic solvent, from the viewpoint of print quality during high-speed printing as described above, it is preferable that the water-soluble organic solvent 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). Of these, from the viewpoint of print quality during high-speed printing as described above, it is particularly preferable to use a combination of a glycol monoalkyl ether solvent (having a boiling point of 100 to 220°C at 1 atmospheric pressure) and a dihydric alcohol solvent (having a boiling point of 100 to 220°C at 1 atmospheric pressure).

[0105] Examples of glycol monoalkyl ether solvents (provided that the boiling point at 1 atmospheric pressure is 100 to 220°C) 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, and these can be preferably used.

[0106] As the dihydric alcohol solvent (provided that the boiling point at 1 atmospheric pressure is 100 to 220°C), 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 is preferably used. Among the above alkanediols, an alkanediol that has a branched alkyl group is 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 the boiling point at 1 atmospheric pressure is 100 to 220°C), include 1,2-propanediol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, and 1,2-pentanediol. Furthermore, examples of alkanediols that do not have hydroxyl groups at both ends of the hydrocarbon chain and have a branched alkyl group (but have a boiling point of 100 to 220°C at 1 atmospheric pressure) include 2-methyl-1,3-propanediol, 3-methyl-1,3-butanediol, and 2-methyl-2,4-pentanediol.

[0107] The aqueous inkjet ink used in combination with the pretreatment liquid of this embodiment may contain a surfactant. In this case, 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. As the surfactant, the same compounds as those listed above that can be used as surfactants that can be contained in the pretreatment liquid of this embodiment can be used.

[0108] <Printed Material and Manufacturing Method Thereof> One embodiment of the present invention relates to a printed material formed using the pretreatment liquid and aqueous inkjet ink of this embodiment. To form the printed material, an ink set including the pretreatment liquid and aqueous inkjet ink of this embodiment may be used. The printed material has a printing substrate and a printed layer formed on the printing substrate by printing using the pretreatment liquid and aqueous inkjet ink of this embodiment. In other words, the printed layer is composed of a pretreatment layer and an ink layer. Below, the steps and other aspects of a method for manufacturing a printed material using the pretreatment liquid and aqueous inkjet ink are described.

[0109] When producing a printed matter using the above-described pretreatment liquid and aqueous inkjet ink, the production method may include 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, and it is preferable to perform steps (1) and (2) 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 easily 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 is printed on the pretreatment liquid in a wet state. In other words, it is preferable that the pretreatment liquid and the aqueous inkjet ink are for use in a wet-on-wet printing method.

[0110] In the present disclosure, "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 image 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.

[0111] 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 a method according to (i) to (iii) described below.

[0112] (i) First, the mass per unit area (w0 [g / m ２]) is 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 an inkjet method, if the maximum amount in the actual manufacturing method is a 100% printing rate, the pretreatment liquid is printed at a 100% printing rate. 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 to a mass per unit area (w1 [g / m ２ ]) The mass of the printed matter is, for example, a value measured 30 to 60 seconds after 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 immediately before the implementation of step (2) in the actual manufacturing method can be recovered from the printing apparatus, the printed matter may be recovered from the actual manufacturing method, and w1 may be determined from the printed matter.

[0113] (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 the 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, a 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 apparatus immediately after step (1) in the actual manufacturing method, the printed matter may be collected from the actual manufacturing method, and w2 may be calculated from the collected 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 liquid) [mL / m ２ When the pretreatment liquid is printed on the printing substrate by 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.

[0114] (iii) The value obtained by the calculation formula 100 × (w10 - w20 × Nvp) / [w20 × (1 - Nvp)] is defined as 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, 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)).

[0115] 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.

[0116] <Pretreatment Liquid Printing Step (1)> In the step (1), the method of printing the pretreatment liquid of this embodiment onto a printing substrate is preferably an inkjet printing method, because the print image quality can be easily adjusted by controlling the amount of 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 can be preferably used in printing applications using the inkjet printing method.

[0117] 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. Alternatively, a multi-pass method may be employed 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 as a "scanning head single-pass method" in this disclosure), and a method in which the printing substrate is printed by passing it under a fixed inkjet head only once (referred to as a "fixed head single-pass method" in this disclosure). In the method for producing a printed product using the pretreatment liquid of this embodiment, any of the above-mentioned methods may be employed. 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.

[0118] 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.

[0119] From the viewpoint of obtaining a printed matter having excellent print image quality and abrasion resistance, the thickness of the pretreatment layer immediately after application of the pretreatment liquid is preferably 1 to 10 μm, more preferably 2 to 8 μm, and particularly preferably 3 to 7 μm.

[0120] <Pretreatment Liquid Drying Step> As described above, in step (2), the aqueous inkjet ink may be printed on a pretreatment layer in a dry state, or may be printed on a pretreatment layer in a wet state. When a drying step is introduced after step (1) and before step (2), from the viewpoint of preventing excessive drying of the pretreatment liquid, for example, room temperature air drying, visible light drying, etc. may be preferably used. Furthermore, after adjusting the energy applied to the pretreatment layer, a method used for drying aqueous inkjet ink, which will be described later, may be used. Furthermore, these drying methods may be used alone or in combination.

[0121] <Step (2) of printing aqueous inkjet ink> In step (2), the aqueous inkjet ink is preferably printed on the pretreatment layer (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 to which the pretreatment liquid has been applied, and more preferably printed so that it overlaps only the area to which the pretreatment liquid has been applied.

[0122] In step (2), the same aqueous inkjet ink may be filled into a plurality of 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 particularly preferably 30 to 45°C. Furthermore, for example, the aqueous inkjet ink may be printed onto the surface of the printing substrate while being heated from the back surface of the printing substrate (the surface opposite to the surface on which the aqueous inkjet ink droplets land). In this case, heating is preferably performed so that the temperature of the surface to be printed with the aqueous inkjet ink (the surface of the printing substrate) reaches 30 to 55°C, and particularly preferably 35 to 50°C.

[0123] The aqueous inkjet ink may also include a plurality of aqueous inkjet inks (aqueous inkjet ink set). Specifically, the aqueous inkjet ink may include two or more inks selected from the group consisting of cyan ink, magenta ink, yellow ink, black ink, and white ink.

[0124] <Drying Step After Aqueous Inkjet Ink Printing> After printing with the aqueous inkjet ink, it is preferable to perform a step of drying the printing substrate to which the pretreatment liquid and the 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. In some embodiments, from the viewpoint of reducing damage to the non-permeable substrate and achieving efficient drying, it is preferable to use hot air drying and / or infrared drying.

[0125] <Printing substrate> 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 the present disclosure, 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 of the present disclosure.

[0126] Specific examples of non-permeable 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 uneven surface and may be transparent, translucent, or opaque. Furthermore, a substrate made by laminating 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. 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 non-permeable substrates exemplified above to a surface modification method such as corona treatment or plasma treatment before applying the pretreatment liquid.

[0127] Specific examples of embodiments of the present invention include the following: <1> A pretreatment liquid to be used with an aqueous inkjet ink, the pretreatment liquid comprising a flocculant, a resin (excluding cationic resins), a water-soluble organic solvent, and water, wherein the resin comprises a nonionic resin (R), the water-soluble organic solvents comprise 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, and wherein, when the content of the nonionic resin (R) contained in 100 g of the pretreatment liquid is WR (g) and the content of the water-soluble organic solvent (S2) is WS2, a value expressed by WR / WS2 is 0.03 to 10. <2> The pretreatment liquid according to <1> above, wherein the mass ratio of the content of the water-soluble organic solvent (S2) to the total content of the water-soluble organic solvent (S1) and the content of the water-soluble organic solvent (S2) is 0.05 to 0.5. <3> The pretreatment liquid according to <1> or <2> above, wherein the nonionic resin (R) is a water-soluble resin. <4> The pretreatment liquid according to any one of <1> to <3> above, further comprising a crosslinking agent, wherein the crosslinking agent comprises a polyhydrazide compound. <5> The pretreatment liquid according to any one of <1> to <4> above, wherein the pretreatment liquid is intended for use in inkjet printing. <6> An ink set comprising the pretreatment liquid according to any one of <1> to <5> above, and an aqueous inkjet ink containing a pigment, a water-soluble organic solvent, and water. <7> A printed material obtained by printing the ink set according to <6> above on a printing substrate. The present invention is related to the subject matter described in Japanese Patent Application No. 2024-060431, filed on April 3, 2024, the disclosure of which is incorporated herein by reference.

[0128] The present invention will now be described in more detail with reference to examples and comparative examples. In the following description, "parts" and "%" are by mass unless otherwise specified.

[0129] <Production of Pretreatment Solutions 1 to 86> 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 was 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 stirred and mixed for 1 hour. The mixture was then cooled to room temperature and filtered through a nylon mesh with a pore size of 100 μm, followed by filtration through a membrane filter with a pore size of 1.2 μm to produce pretreatment solutions 1 to 86. The unit of the amount of each raw material added shown in Table 1 below is "g." Each raw material was added to the mixture of materials already added to the mixing vessel while stirring. 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 these components were not included, the component in question was skipped and the next component was added. Also, for components containing two or more raw materials, the order of addition within the component was arbitrary.

[0130]

[0131]

[0132]

[0133]

[0134]

[0135] 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: manufactured by Nittobo Medical Co., Ltd., cationic resin containing diallyldimethylammonium hydrochloride as a structural unit. PAS-J-81L: manufactured by Nittobo Medical Co., Ltd., 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) 3m-MB: 3-methoxy-3-methyl-1-butanol (log P: 0.42, boiling point at 1 atmosphere: 174°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 manufactured by BYK-Chemie (water-soluble resin) Poval 3-80 aqueous solution: an aqueous solution obtained by dissolving Poval 3-80 (polyvinyl alcohol manufactured by Kuraray, saponification degree: 80%) in ion-exchanged water to a solid content of 15% Superflex 500M: polyurethane resin fine particles manufactured by Daiichi Kogyo Seiyaku Co., Ltd. Hitec E-5403P: Oxidized polyethylene resin microparticles manufactured by Toho Chemical Industry Co., Ltd. Vinyblan 278: Polyvinyl chloride-based resin microparticles manufactured by Nissin Chemical Industry Co., Ltd. NeoCryl XK-190: (meth)acrylic resin microparticles manufactured by DSM Coating Resins Co., Ltd. Surfynol 440: Acetylene diol-based surfactant manufactured by Evonik Corporation Surfynol 485: Acetylene diol-based surfactant manufactured by Evonik Corporation TEGO Wet 280: Polyether-modified siloxane-based surfactant manufactured by Evonik Corporation ADH: Adipic acid dihydrazide SDH: Sebacic acid dihydrazide V-04: Carbodilite V-04 (polycarbodiimide-based compound manufactured by Nisshinbo Chemical Inc., Nv.: 40% by mass),

[0136] <Preparation of Pigment Dispersion> (Preparation of Black Pigment Dispersion) 15 parts of carbon black ("PrinteX85" manufactured by Orion Engineered Carbons), 3 parts of a 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 millimole equivalent of 4.2 mmoleq. / g, and a weight average molecular weight of 20,000), and 82 parts of water were charged into a mixing vessel equipped with a stirrer, and premixing was carried out for 1 hour. Thereafter, using a "Dynomill" (volume 0.6 L) manufactured by Shinmaru Enterprises Corporation filled with 1,800 g of zirconia beads with a diameter of 0.5 mm, circulation dispersion was carried out until the 50% diameter of the carbon black reached approximately 100 nm, thereby producing a black pigment dispersion.

[0137] (Preparation of Cyan Pigment Dispersion, Magenta Pigment Dispersion, and Yellow Pigment Dispersion) Cyan pigment dispersion, magenta pigment dispersion, and yellow pigment dispersion were prepared using the same materials and method as for the black pigment dispersion, except that the following pigments were used as pigments and circulatory dispersion was carried out until the 50% diameters shown below were reached. Cyan pigment dispersion: LIONOL BLUE 7358G (C.I. Pigment Blue 15:3) manufactured by Toyocolor Co., Ltd., 50% diameter = 150 nm Magenta pigment dispersion: TOSHKI RED 150TR (C.I. Pigment Red 150) manufactured by Tokyo Shikizai Kogyo Co., Ltd., 50% diameter = 200 nm Yellow pigment dispersion: LIONOL YELLOW TT1405G (C.I. Pigment Yellow 14) manufactured by Toyocolor Co., Ltd., 50% diameter = 150 nm

[0138] <Production of aqueous binder resin solution> An aqueous binder resin solution (solid content 30%) was produced using the method described in the examples of JP 2020-180178 A, and used as the “aqueous binder resin solution.” The “aqueous binder resin solution” refers to a solution containing an aqueous medium and components dispersed and / or dissolved in the aqueous medium.

[0139] <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, stirring and mixing was continued for one hour at room temperature (25°C), and then the contents of the mixing vessel were heated to 50°C and further stirred and mixed for one 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. Water-based cyan inks, water-based magenta inks, and water-based yellow inks were prepared 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, respectively. The water-based black inks, water-based cyan inks, water-based magenta inks, and water-based yellow inks with the same numbers were used as water-based inkjet ink sets 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 to the mixing vessel while stirring the mixture. The ion-exchanged water, water-soluble organic solvent, surfactant, aqueous binder resin solution, and pigment dispersion were added to the mixing vessel in this order. However, for components containing two or more raw materials, the order of addition within the component was arbitrary.

[0140]

[0141] Among the trade names and abbreviations listed in Table 2 above, those not used in Table 1 above are detailed below. Note that "bp" 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: acetylene diol surfactant manufactured by Evonik

[0142] <Preparation of Printed Material> An inkjet ejection device was prepared, in which four Kyocera Corporation KJ4B-1200 inkjet heads (design resolution 1200 dpi, nozzle diameter 20 μm) were arranged in the transport direction of the printing substrate. Starting from the upstream inkjet head with respect to the transport direction of the printing substrate, the inks were filled in the following order: aqueous black ink, aqueous cyan ink, aqueous magenta ink, and aqueous yellow ink. Next, using a non-wire bar coater 250-OSP-02 manufactured by OSG System Products, Inc., a biaxially oriented polypropylene film "OPU-1" (thickness 20 μm) manufactured by Mitsui Chemicals Tocello, Inc., was coated with each of the pretreatment liquids prepared above to a wet film thickness of 2.0±0.2 μm, and the film was then fixed on a conveyor without a drying process. The conveyor was then driven at a constant speed, and as the polypropylene film passed below the installation section of the inkjet heads, aqueous inkjet inks were each ejected at a drop volume of 2 pL, thereby printing an image as described below. Immediately after printing, the polypropylene film was placed in an air oven at 70°C and dried for 3 minutes to produce a printed product.

[0143] The above-described printed matter was produced using the combinations of pretreatment liquid and aqueous inkjet ink set shown in Table 3. In the method for producing the 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 method described above and was found to be 95 to 100% by mass.

[0144] Furthermore, three types of images were prepared for printing: an image in which 5 cm × 20 cm solid color patches with a printing rate of 100% were arranged adjacently in the order of cyan, magenta, yellow, and black (hereinafter referred to as a "solid patch image"); an image in which, within a 5 cm × 20 cm area, solid color patches with a printing rate that continuously changed from 10 to 80% in the long side direction were arranged adjacently in the order of cyan, magenta, yellow, and black (hereinafter referred to as a "gradation image"); and an image in which 20 characters of each color were printed in 6-point MS Mincho font, a mixture of hiragana and kanji characters (hereinafter referred to as a "character image"). Printed materials were then produced using each of the above-mentioned pretreatment liquids.

[0145] 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 of the conveyor driving speed conditions.

[0146] [Examples 1 to 90, 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 were as shown in Table 3. However, for the combinations of Examples 79 to 90, Evaluations 1 to 3, which were performed under the same evaluation conditions as in Example 42, were not carried out.

[0147] <Evaluation 1: Evaluation of Blend Stability> The blend stability of the pretreatment liquid during cleaning was evaluated by checking the occurrence of precipitates, turbidity, etc. during the production of the pretreatment liquid described above, and for those in which precipitates, turbidity, etc. did not occur, the produced pretreatment liquid was allowed to stand for two weeks in an incubator set at 60°C, and then checking the occurrence of precipitates, turbidity, etc. The evaluation criteria are as follows, with "A" and "B" representing levels suitable for practical use. (Evaluation Criteria) A: No precipitates or turbidity were observed during the production of the pretreatment liquid before filtration through a nylon mesh. Furthermore, no precipitates or turbidity occurred even after the pretreatment liquid after filtration through a membrane filter was allowed to stand for two weeks in an incubator set at 60°C. B: Precipitates or turbidity were observed in the pretreatment liquid during the production of the pretreatment liquid before filtration through a nylon mesh, but the precipitates and turbidity were successfully removed by filtration through the nylon mesh and membrane filter. Furthermore, even when the filtered pretreatment liquid was allowed to stand for two weeks in an incubator set at 60°C, no precipitate or turbidity occurred. D: During the production of the pretreatment liquid, precipitate or turbidity was observed in the pretreatment liquid before filtration through a nylon mesh. The precipitate or turbidity could not be removed by filtration through a nylon mesh or membrane filter, or the precipitate or turbidity was removed by filtration, but when the filtered pretreatment liquid was allowed to stand for two weeks in an incubator set at 60°C, precipitate or turbidity occurred again.

[0148] <Evaluation 2: Evaluation of Initial Discharge Properties> To impart visibility, a cationic dye (Rhodamine B manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was blended into each pretreatment liquid in advance at an external ratio of 0.5 mass % relative to the total mass of the pretreatment liquid. Next, the pretreatment liquid to which the dye had been added 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 the pretreatment liquid oozed out from the nozzles of the inkjet head. Thereafter, the pretreatment liquid adhering to the nozzle plate was wiped off, and immediately thereafter, a nozzle check pattern was printed at a frequency of 40 kHz. The initial discharge properties were evaluated by visually counting the number of missing nozzles in the nozzle check pattern. The evaluation criteria were as follows, with "A," "B," and "C" representing practically usable levels. However, for pretreatment liquids that received a "D" rating in the above blend stability evaluation, initial discharge properties were not evaluated. (Evaluation criteria) A: No missing nozzles at all B: The number of missing nozzles was 1 to 4 C: The number of missing nozzles was 5 to 9 D: The number of missing nozzles was 10 or more

[0149] <Evaluation 3: Evaluation of continuous dischargeability> After printing the nozzle check pattern in Evaluation 2 above, 10 solid images (printing rate 100%) with a printing width of 10 cm and a length of 30 cm were printed consecutively. Thereafter, a nozzle check pattern was printed again, and the number of nozzle clogs increased visually from the number of nozzle clogs in the initial dischargeability evaluation, thereby evaluating the continuous dischargeability. The evaluation criteria are as follows, with "A," "B," and "C" representing levels suitable for practical use. However, the evaluation of continuous dischargeability was only carried out for pretreatment liquids that were determined to be suitable for practical use in the above-mentioned evaluation of blend stability and initial dischargeability. (Evaluation criteria) A: The number of nozzle clogs was the same as the number of nozzle clogs in the initial dischargeability evaluation. B: The number of nozzle clogs increased by 1 to 4 from the number of nozzle clogs in the initial dischargeability evaluation. C: The number of nozzle clogs increased by 5 to 9 from the number of nozzle clogs in the initial dischargeability evaluation. D: The number of nozzle clogs increased by 10 or more from the number of nozzle clogs in the initial dischargeability evaluation.

[0150] <Evaluation 4: Evaluation of Print Quality (White Out, Dot Shape)> Prints of solid patch images produced by varying the conveyor drive speed based on the above method were visually observed to confirm the degree of white out. Additionally, the dot shapes in the 10-20% coverage areas 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 side) to determine whether all characters were legible. The print quality was then comprehensively evaluated based on the degree of white out, dot shape, and character legibility. The evaluation criteria are as follows, with "A," "B," and "C" representing practically usable levels. Table 3 lists the results for the color with the worst evaluation among the four colors evaluated. (Evaluation criteria) A: In prints printed at a conveyor drive speed of 75 m / min, and in all colors, no white spots, irregular dot shapes, or illegible characters were observed. B: In prints printed at a conveyor drive speed of 75 m / min, there were colors in which one or more of white spots, irregular dot shapes, or illegible characters were observed, but in prints printed at a conveyor drive speed of 50 m / min, there were colors in which one or more of white spots, irregular dot shapes, or illegible characters were observed. C: In prints printed at a conveyor drive speed of 50 m / min, there were colors in which one or more of white spots, irregular dot shapes, or illegible characters were observed, but in prints printed at a conveyor drive speed of 25 m / min, there were colors in which one or more of white spots, irregular dot shapes, or illegible characters were observed. D: In prints printed at a conveyor drive speed of 25 m / min, there were colors in which one or more of the following were confirmed: white spots, irregular dot shapes, and illegible characters.

[0151] <Evaluation 5: Evaluation of Abrasion Resistance> Based on the above method, solid patch image prints were prepared at a conveyor drive speed of 50 m / min. Then, 2 cm x 20 cm test pieces were cut out of 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 a friction element (weight: 200 g), and the test piece was rubbed back and forth with the white cotton cloth for a predetermined number of times while varying the load applied to the friction element. After the back and forth abrasion, the condition of the print surface and the degree of coloring of the cotton cloth were visually confirmed to evaluate abrasion resistance. The evaluation criteria are as follows, with "A," "B," and "C" representing practically usable levels. "A" and "B" representing particularly suitable levels for practical use. Table 3 lists the results for the color with the worst evaluation among the four colors evaluated. (Evaluation criteria) A: Even after 50 reciprocating rubs with a 300g weight placed on the friction element (500g load), there were no abrasion marks on the printed surface and no discoloration on the cotton cloth. B: Even after 25 reciprocating rubs with a 300g weight placed on the friction element (500g load), there were no abrasion marks on the printed surface and no discoloration on the cotton cloth. However, after 50 reciprocating rubs under the same load conditions, there were abrasion marks on the printed surface and / or discoloration on the cotton cloth. C: After 25 reciprocating rubs without a weight placed on the friction element (200g load), there were no abrasion marks on the printed surface and no discoloration on the cotton cloth. However, after 25 reciprocating rubs with a 300g weight placed on the friction element (500g in total), there were abrasion marks on the printed surface and / or discoloration on the cotton cloth. D: After 25 reciprocating rubs without placing a weight on the rubber (load 200 g), scratches were observed on the printed surface and / or coloring of the cotton cloth was observed.

[0152]

[0153]

[0154]

[0155] As is clear from Table 3, the combinations (Examples) using pretreatment liquids 1 to 78 that satisfied 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 image quality of printed matter. Furthermore, when a certain amount or more of nonionic resin (R) and / or anionic resin, which are resin fine particles, was included, or when a crosslinking agent was included, it was confirmed that in addition to the above properties, the abrasion resistance of printed matter was also particularly suitable for practical use.

[0156] In contrast, the pretreatment liquids 79 to 86 (comparative examples) did not reach a practically usable level in one or more of the evaluated items. Specifically, pretreatment liquid 79 did not contain a flocculant, pretreatment liquid 80 did not contain water-soluble organic solvent S1, pretreatment liquids 81 and 82 did not contain water-soluble organic solvent S2, and pretreatment liquids 85 and 86 did not contain nonionic resin (R). Furthermore, the value expressed by WR / WS2 for pretreatment liquid 83 was less than 0.03, while the value expressed by WR / WS2 for pretreatment liquid 84 was greater than 10. These results demonstrate that if even one of the above requirements is missing, it becomes difficult to achieve the above-mentioned effects.

Claims

1. A pretreatment liquid containing a flocculant, a resin (excluding cationic resins), a water-soluble organic solvent, and water, and used together with an aqueous inkjet ink, wherein the resin contains a nonionic resin (R), and the water-soluble organic solvents contain 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, and wherein, when the content of the nonionic resin (R) contained 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 0.03 to 10.

2. The pretreatment liquid according to claim 1, wherein the mass ratio of the content of the water-soluble organic solvent (S2) to the total 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 claim 1 or 2, wherein the nonionic resin (R) is a water-soluble resin.

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

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

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 formed using the ink set according to claim 6.

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