Water-based inkjet ink set and method for producing printed matter

Abstract

To provide an ink set capable of forming a printed matter having excellent image quality and processability of a printed image especially for a low-permeability substrate.SOLUTION: There is provided an aqueous inkjet ink set which comprises a pretreatment liquid and an aqueous inkjet ink, wherein the pretreatment liquid contains a cationic water-soluble resin in which the absolute value of the surface charge amount is 5.5 meq / g or less, the amount of the cationic water-soluble resin is 1.0 mass% or more and 20 mass% or less based on the total amount of pretreatment liquid, the aqueous inkjet ink contains water, a coloring material and an anionic water-dispersible urethane resin in which the absolute value of the surface charge amount is 0.01 meq / g or more and 0.09 meq / g or less and the amount of the anionic water-dispersible urethane resin is 1.0 mass% or more and 15 mass% or less based on the total amount of the aqueous inkjet ink.SELECTED DRAWING: None

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION Embodiments of the present invention relate to aqueous inkjet ink sets and methods for producing printed materials. [Background technology]

[0002] Inkjet recording systems are printing systems that spray highly fluid liquid ink from minute nozzles onto a substrate to print. This system has recently become increasingly popular due to its ability to print high-resolution, high-quality images at high speed and with low noise using relatively inexpensive equipment. Water-based inks are widely used because they can produce high-quality prints at low cost. Water-based inks dry quickly due to their water content, and they also have the advantage of being environmentally friendly.

[0003] In recent years, inkjet recording systems have been used not only on paper media such as plain paper and specialty paper, but also on woven fabrics, nonwoven fabrics such as felt, wood materials, and functional porous materials that exhibit functionality through the pores in the substrate, all of which tend to allow ink to easily spread along the fibers. They are also being used on plastic substrates, synthetic paper, metal substrates, glass substrates, and other substrates that are difficult for ink to penetrate.

[0004] When using aqueous ink on a substrate that is difficult for ink to penetrate, such as a metal substrate, one method is to pretreat the metal substrate in advance to form a porous layer or ink-receiving layer, and then inkjet printing is performed on top of that. Patent Document 1 proposes a method in which a porous layer containing inorganic particles and resin is formed on a metal plate coated with a resin layer, and patterns, letters, etc. are printed on the porous layer by inkjet printing. Patent Document 2 proposes a method of recording by inkjet recording on an aluminum substrate carrying an ink-receiving layer, in which the ink-receiving layer is formed using a coating liquid containing a copolymer emulsion, a cationic compound, and an inorganic filler. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-37811 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-209774 Summary of the Invention [Problem to be solved by the invention]

[0006] When inkjet printing is performed on a substrate that is difficult for ink to penetrate without pre-treating the substrate, the ink may bleed on the substrate, causing the dots to spread and coalesce, resulting in an unsatisfactory image. For this reason, it is desirable to form an ink-receiving layer on the substrate in advance to ensure good ink dot formation on the substrate, or to apply a pre-treatment liquid to the substrate before printing, which reacts with the ink components to form good dots. When a pretreatment liquid containing an aggregating agent is used to suppress ink bleeding by aggregating components in the ink with the aggregating agent in the pretreatment liquid, cracks may occur in the printed image depending on the degree of aggregating, resulting in the printed image appearing whitish and failing to produce an image with good color development. In addition, the image portion of the printed matter may be subjected to processing such as bending or punching, which may cause the image to crack or become whitish.

[0007] An object of an embodiment of the present invention is to provide an aqueous inkjet ink set that can form printed matter with excellent image quality and processability, particularly on low-permeability substrates. Another embodiment of the present invention aims to provide a method for producing a printed matter that can form a printed matter that is excellent in image quality and processability, particularly on a low-permeability substrate. [Means for solving the problem]

[0008] According to one embodiment of the present invention, there is provided an aqueous inkjet ink set comprising a pretreatment liquid and an aqueous inkjet ink, wherein the pretreatment liquid comprises a cationic water-soluble resin having an absolute value of a surface charge of 5.5 meq / g or less, and the cationic water-soluble resin accounts for 1.0% by mass or more and 20% by mass or less with respect to the total amount of the pretreatment liquid, and the aqueous inkjet ink comprises water, a colorant, and an anionic water-dispersible urethane resin having an absolute value of a surface charge of 0.01 meq / g or more and 0.09 meq / g or less, and the anionic water-dispersible urethane resin accounts for 1.0% by mass or more and 15% by mass or less with respect to the total amount of the aqueous inkjet ink. According to another embodiment of the present invention, there is provided a method for producing a printed item, the method including: applying a pretreatment liquid to a substrate; and applying an aqueous inkjet ink to the substrate to which the pretreatment liquid has been applied by an inkjet method, wherein the pretreatment liquid contains a cationic water-soluble resin having an absolute value of a surface charge of 5.5 meq / g or less, and the cationic water-soluble resin accounts for 1.0% by mass or more and 20% by mass or less with respect to the total amount of the pretreatment liquid; and the aqueous inkjet ink contains water, a colorant, and an anionic water-dispersible urethane resin having an absolute value of a surface charge of 0.01 meq / g or more and 0.09 meq / g or less, and the anionic water-dispersible urethane resin accounts for 1.0% by mass or more and 15% by mass or less with respect to the total amount of the aqueous inkjet ink. [Effects of the Invention]

[0009] According to an embodiment of the present invention, it is possible to provide an aqueous inkjet ink set and a method for producing a printed matter that are capable of forming a printed matter that is excellent in image quality and processability, particularly on a low-permeability substrate. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will be described below using embodiments, but the examples in the following embodiments do not limit the present invention.

[0011] <Water-based inkjet ink set>

[0013] An aqueous inkjet ink set (hereinafter sometimes simply referred to as "ink set") according to one embodiment comprises a pretreatment liquid and aqueous inkjet inks (hereinafter sometimes simply referred to as "inks" or "aqueous inks"). The pretreatment liquid comprises a cationic water-soluble resin having an absolute value of a surface charge of 5.5 meq / g or less (hereinafter sometimes referred to as "cationic water-soluble resin A"), and the cationic water-soluble resin A accounts for 1.0% by mass or more and 20% by mass or less of the total amount of the pretreatment liquid. The aqueous inkjet ink comprises water, a colorant, and an anionic water-dispersible urethane resin having an absolute value of a surface charge of 0.01 meq / g or more and 0.09 meq / g or less (hereinafter sometimes referred to as "anionic water-dispersible urethane resin B"), and the anionic water-dispersible urethane resin B accounts for 1.0% by mass or more and 15% by mass or less of the total amount of the aqueous inkjet inks.

[0012] When an ink set according to one embodiment is used, it is possible to form a printed matter with excellent image quality and processability, particularly on a low-permeability substrate. The reasons for this are thought to be as follows, but the scope of the present invention is not limited to the theory below. A pretreatment liquid containing a cationic water-soluble resin (cationic water-soluble resin A) having an absolute surface charge of 5.5 meq / g or less in an amount of 1.0% by mass to 20% by mass, both inclusive, based on the total amount of the pretreatment liquid, and an anionic water-dispersible urethane resin (anionic water-dispersible urethane resin B) having an absolute surface charge of 0.01 meq / g to 0.09 meq / g in an amount of 1.0% by mass to 15% by mass, both inclusive, based on the total amount of the ink, are used. When the pretreatment liquid and the ink come into contact, the cationic water-soluble resin A in the pretreatment liquid acts as an aggregating agent that aggregates the colorant and anionic water-dispersible urethane resin B in the ink, causing these ink components to aggregate appropriately, suppressing ink bleeding and enabling the production of printed images with excellent color development. Furthermore, since the aggregation of ink components due to contact between the pretreatment liquid and the ink can be controlled to an appropriate degree, it is possible to suppress an excessive decrease in ink dot size due to excessive aggregation of ink components, and image cracking due to image shrinkage after ink application in areas where a large amount of ink is applied or during heat drying, etc., and to obtain a good printed image with excellent color development. Furthermore, when the aqueous inkjet ink contains anionic water-dispersible urethane resin B, the flexibility of the urethane resin makes it easier for the printed image to follow processing, and the image can be prevented from cracking or becoming whitish due to processing.

[0013] Furthermore, when the aqueous inkjet ink contains anionic water-dispersible urethane resin B in an amount of 1.0 mass % or more relative to the total amount of the ink, the fixing performance of the anionic water-dispersible urethane resin B as a binder is easily exhibited, and printed images with excellent durability can be obtained.

[0014] Pre-treatment liquid The pretreatment liquid will now be described.

[0015] The pretreatment liquid preferably contains a cationic water-soluble resin (cationic water-soluble resin A) having an absolute value of surface charge of 5.5 meq / g or less.

[0016] The cationic water-soluble resin A preferably has a solubility in water at 23° C. of 5 g / 100 g or more, more preferably 20 g / 100 g or more.

[0017] The cationic water-soluble resin A has a positive surface charge, and the absolute value of the surface charge is preferably 5.5 meq / g or less.

[0018] From the viewpoint of improving the aggregation of ink components and suppressing bleeding of ink dots to improve the quality of printed images, the absolute value of the surface charge of the cationic water-soluble resin A is preferably 1.0 meq / g or more, more preferably 2.0 meq / g or more, and even more preferably 2.5 meq / g or more.

[0019] From the viewpoint of controlling the degree of aggregation so that the ink components do not aggregate excessively, suppressing excessive reduction in ink dot size and image cracking, and improving the quality of printed images, the absolute value of the surface charge quantity of the cationic water-soluble resin A is preferably 5.5 meq / g or less, more preferably 5.0 meq / g or less, and even more preferably 4.5 meq / g or less.

[0020] From the viewpoint of achieving appropriate aggregation of the ink components and thereby improving the quality of the printed image, the absolute value of the surface charge of the cationic water-soluble resin A is preferably 1.0 meq / g or more and 5.5 meq / g or less, more preferably 2.0 meq / g or more and 5.0 meq / g or less, and even more preferably 2.5 meq / g or more and 4.5 meq / g or less.

[0021] The surface charge of cationic water-soluble resin A and the surface charge of anionic water-dispersible urethane resin B (described later) are expressed as the charge per active ingredient of the resin (unit: meq / g) and can be determined using polyelectrolyte titration. In polyelectrolyte titration, the charge of an aqueous sample can be quantitatively measured by titrating it with a polyelectrolyte of opposite charge. The endpoint of the titration reaction can be detected using the streaming potential method. A colloid particle charge analyzer (Model CAS, manufactured by AFG ANALYTIC GmbH) can be used as a measuring device using the streaming potential method. In this device, a liquid containing an aqueous sample containing the substance of interest is placed in the measurement cell, and a piston is moved up and down to induce a strong flow in the sample liquid, generating a streaming potential. Specifically, the surface charge of the resin can be determined as follows: The aqueous sample containing the resin to be measured is titrated with a polyelectrolyte of opposite charge with a known charge density. The total charge of the aqueous sample can be determined from the amount of polyelectrolyte used until the endpoint, at which the streaming potential reaches 0 mV, is reached. The total charge amount of this aqueous sample divided by the amount of the active ingredient of the resin contained in the aqueous sample is the surface charge amount of the resin (unit: meq / g). To measure the surface charge of a cationic substance such as cationic water-soluble resin A, an N / 400 PVSK solution (0.0025N potassium polyvinyl sulfate titrant, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) can be used as the oppositely charged polymer electrolyte. To measure the surface charge of an anionic substance such as anionic water-dispersible urethane resin B, an N / 400 DADMAC solution (0.0025N poly(diallyldimethylammonium chloride) solution, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) can be used as the oppositely charged polymer electrolyte.

[0022] The cationic water-soluble resin A may be, for example, a resin having a basic group in its constituent unit, or a resin into which a basic group has been introduced. For example, the cationic water-soluble resin A may be a resin having one or more cationic sites such as amine, ammonium salt, pyridinium salt, or imidazolidinone salt. More specifically, examples of the cationic water-soluble resin A include copolymers of polyvinylamine, polyallylamine, acrylamide, and derivatives thereof. Examples of cationic water-soluble resin A include acrylamide-acrylonitrile-N-vinylacrylamidine hydrochloride-N-vinylacrylamide-vinylamine hydrochloride-N-vinylformamide copolymer, diallylamine hydrochloride-acrylamide copolymer, and diallyldimethylammonium chloride-acrylamide copolymer. These may be used alone or in combination of two or more.

[0023] Commercially available cationic water-soluble resin A includes, for example, "Himax SC-700M" manufactured by Himo Co., Ltd. and "Unisense KCA101L" manufactured by Senka Co., Ltd. (both are trade names).

[0024] The above cationic water-soluble resin A may be used alone or in combination of two or more. The amount of the cationic water-soluble resin A in terms of the active ingredient is preferably 1.0% by mass or more and 20% by mass or less relative to the total amount of the pretreatment liquid.

[0025] From the viewpoint of improving the aggregation of ink components and suppressing bleeding of ink dots to improve the image quality of printed images, the amount of the cationic water-soluble resin A in terms of active ingredient is preferably 1.0% by mass or more, more preferably 1.5% by mass or more, even more preferably 2.0% by mass or more, still more preferably 2.5% by mass or more, and even more preferably 5.0% by mass or more, relative to the total amount of the pretreatment liquid.

[0026] From the viewpoint of controlling the degree of aggregation so that the ink components do not aggregate excessively and suppressing excessive reduction in ink dot size and cracking in the image to improve the quality of the printed image, the amount of the cationic water-soluble resin A in terms of the active ingredient is preferably 20% by mass or less, more preferably 18% by mass or less, even more preferably 15% by mass or less, and even more preferably 12% by mass or less, relative to the total amount of the pretreatment liquid.

[0027] From the viewpoint of achieving appropriate aggregation of the ink components and thereby improving the quality of the printed image, the cationic water-soluble resin A preferably accounts for 1.0 mass % or more and 20 mass % or less, more preferably 1.5 mass % or more and 18 mass % or less, still more preferably 2.0 mass % or more and 18 mass % or less, even more preferably 2.5 mass % or more and 15 mass % or less, and still more preferably 5.0 mass % or more and 12 mass % or less, in terms of the amount of active ingredient, relative to the total amount of the pretreatment liquid.

[0028] The pretreatment liquid may further contain a binder resin. Examples of the binder resin include a water-dispersible resin, a water-soluble resin other than the cationic water-soluble resin A, or a combination thereof. Examples of the binder resin include a cationic resin, a nonionic resin, or a combination thereof, with cationic resins being preferred from the viewpoint of the stability of the pretreatment liquid. The pretreatment liquid may contain, for example, a water-dispersible resin such as a cationic water-dispersible resin, a nonionic water-dispersible resin, or a combination thereof, with cationic water-dispersible resins being preferred.

[0029] The cationic water-dispersible resin may be one in which the cationic functional group of the resin is present on the surface of the resin particles, as in the case of a self-emulsifying resin, or one that has been surface-treated by attaching a cationic dispersant to the surface of the resin particles. Representative examples of the cationic functional group include primary, secondary, or tertiary amino groups, pyridine groups, imidazole groups, benzimidazole groups, triazole groups, benzotriazole groups, pyrazole groups, and benzopyrazole groups. Examples of cationic dispersants include primary, secondary, tertiary, or quaternary amino group-containing acrylic polymers, polyethyleneimine, cationic polyvinyl alcohol resins, and cationic water-soluble hyperbranched polyesteramide resins. Examples of cationic water-dispersible resins include urethane resins, (meth)acrylic resins, ethylene-vinyl chloride copolymer resins, styrene-maleic anhydride copolymer resins, and vinyl acetate-ethylene copolymer resins. The term (meth)acrylic resin refers to a polymer containing at least a methacrylic unit, an acrylic unit, or a combination thereof. The (meth)acrylic resin preferably contains, for example, a unit derived from a (meth)acrylic monomer, which will be described later.The cationic water-dispersible resin is more preferably a cationic water-dispersible (meth)acrylic resin.

[0030] The cationic water-dispersible resin is preferably a resin particle whose surface is positively charged. The absolute value of the surface charge amount of the cationic water-dispersible resin is preferably 0.01 meq / g or more and 0.5 meq / g or less. The surface charge amount of the cationic water-dispersible resin can be measured in the same manner as the surface charge amount of the cationic water-soluble resin described above.

[0031] The cationic water-dispersible resin can be blended in the ink as an oil-in-water (O / W) type resin emulsion that becomes particulate in the ink, and preferably becomes resin particles in the ink. Commercially available resin emulsions of cationic water-dispersible (meth)acrylic resins include, for example, "Polysol AP-1350" and "Polysol AP-1370" manufactured by Showa Denko KK (both are trade names).

[0032] The nonionic water-dispersible resin may be one in which the nonionic functional group of the resin is present on the surface of the resin particles, such as a self-emulsifying resin, or one that has been surface-treated by attaching a nonionic dispersant to the surface of the resin particles. Representative examples of the nonionic functional group include a polyoxyalkylene glycol group, a carboxyl group, and a hydroxyl group. Examples of the nonionic dispersant include a nonionic surfactant. Examples of nonionic resins include urethane resins, (meth)acrylic resins, ethylene-vinyl chloride copolymer resins, styrene-maleic anhydride copolymer resins, and vinyl acetate-ethylene copolymer resins. The nonionic water-dispersible resin is preferably a resin particle whose surface is almost uncharged, and the absolute value of the surface charge of the nonionic water-dispersible resin is preferably less than 0.01 meq / g.

[0033] The surface charge amount of the nonionic water-dispersible resin can be measured in the same manner as the surface charge amount of the cationic water-soluble resin A using N / 400 PVSK solution (0.0025N potassium polyvinyl sulfate titrant, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.).

[0034] The nonionic water-dispersible resin can be blended into the ink as an oil-in-water (O / W) type resin emulsion that becomes particulate in the ink, and preferably becomes resin particles in the ink.

[0035] The amount of the binder resin, in terms of the active ingredient, is preferably 1 to 20 mass %, more preferably 5 to 15 mass %, based on the total amount of the pretreatment liquid. The amount of the water-dispersible resin in terms of the active ingredient is preferably 1 to 20 mass %, more preferably 5 to 15 mass %, based on the total amount of the pretreatment liquid.

[0036] The pretreatment liquid preferably contains water as an aqueous solvent. In the pretreatment liquid, water may be the main solvent. When water is contained as a solvent in a resin emulsion or the like, the water in each component is converted into a part of the water in the pretreatment liquid when preparing the pretreatment liquid. The water is not particularly limited, but is preferably one that contains as few ionic components as possible. In particular, from the viewpoint of ink storage stability, it is preferable that the content of polyvalent metal ions such as calcium is low. Examples of water that can be used include ion-exchanged water, distilled water, and ultrapure water. From the viewpoint of adjusting the ink viscosity, the water content is preferably 20 to 90% by mass, and more preferably 30 to 80% by mass, based on the total amount of the pretreatment liquid.

[0037] The pretreatment liquid may contain a water-soluble organic solvent. The water-soluble organic solvent is preferably compatible with water. The water-soluble organic solvent may be an organic compound that is liquid at room temperature and soluble or miscible in water, and is preferably a water-soluble organic solvent that is uniformly miscible with an equal volume of water at 20°C under 1 atmosphere.

[0038] Examples of the water-soluble organic solvent include lower alcohols such as methanol, ethanol, 1-propanol, isopropanol, 1-butanol, 2-butanol, isobutanol, and 2-methyl-2-propanol; glycols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, and 1,3-propanediol; glycerins such as glycerin, diglycerin, triglycerin, and polyglycerin; acetins such as monoacetin and diacetin; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, and ethylene glycol monobutyl ether. Examples of glycol ethers that can be used include ethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monopropyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol dimethyl ether, and tetraethylene glycol diethyl ether; triethanolamine, 1-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, β-thiodiglycol, and sulfolane. These may be used alone or in combination of two or more kinds as long as they form a single phase.

[0039] Among the water-soluble organic solvents, glycols, glycerins, glycol ethers, and combinations thereof are preferably used, and glycol ethers are more preferred because these water-soluble organic solvents have better compatibility with water. Among water-soluble organic solvents, it is preferable to use a low-polarity solvent, such as diethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, triacetin, 3,5,5-trimethyl-2-cyclohexene-1-one, or 2-pyrrolidone.

[0040] From the viewpoint of viscosity adjustment and moisturizing effect, the amount of the water-soluble organic solvent may be 1 to 60 mass % of the total amount of the pretreatment liquid, more preferably 1 to 40 mass %, even more preferably 5 to 30 mass %, and still more preferably 10 to 20 mass %. The amount of the low-polarity water-soluble organic solvent is, for example, preferably 0.1 to 10 mass %, more preferably 0.2 to 5 mass %, based on the total amount of the pretreatment liquid.

[0041] The pretreatment liquid may contain a surfactant. As the surfactant, a nonionic surfactant, a cationic surfactant, or a combination thereof can be preferably used, and a nonionic surfactant is more preferred.

[0042] The HLB value of the surfactant is preferably 5-20.

[0043] Examples of surfactants include ester surfactants such as glycerin fatty acid esters and fatty acid sorbitan esters; ether surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers and polyoxypropylene alkyl ethers; ether ester surfactants such as polyoxyethylene sorbitan fatty acid esters; acetylene surfactants; silicone surfactants; and fluorine surfactants. Of these, acetylene surfactants and silicone surfactants are preferred. The surfactants may be used alone or in combination of two or more.

[0044] Examples of the acetylene surfactant include an acetylene glycol surfactant, an acetylene alcohol surfactant, and a surfactant having an acetylene group. The acetylene glycol surfactant is a glycol having an acetylene group, preferably a glycol having a symmetrical structure with the acetylene group located in the center, and may have a structure in which ethylene oxide is added to acetylene glycol.

[0045] Commercially available acetylene surfactants include, for example, "Olfine E1004," "Olfine E1010," "Olfine E1006," and "Olfine E1020" manufactured by Nissin Chemical Industry Co., Ltd., and "Surfynol 420," "Surfynol 440," "Surfynol 104," "Surfynol 465," and "Surfynol 485" manufactured by Evonik Industries Ltd. (all trade names).

[0046] The above surfactants may be used alone or in combination of two or more.

[0047] The content of the surfactant is preferably 0.1 to 10% by mass, more preferably 0.2 to 5% by mass, and even more preferably 0.5 to 2% by mass, based on the total amount of the pretreatment liquid.

[0048] The pretreatment liquid may contain, as appropriate, for example, a wetting agent (moisturizing agent), a surface tension adjuster (penetrating agent), an antifoaming agent, a fixing agent, a pH adjuster, an antioxidant, an antiseptic, and the like.

[0049] The method for preparing the pretreatment liquid is not particularly limited, and the desired pretreatment liquid can be obtained by appropriately mixing the components. For example, the pretreatment liquid can be obtained by mixing the materials all at once or in portions. The obtained composition can also be filtered using a filter or the like.

[0050] Water-based inkjet ink The aqueous inkjet ink will now be described.

[0051] The aqueous inkjet ink preferably contains an anionic water-dispersible urethane resin (anionic water-dispersible urethane resin B) having an absolute value of the surface charge of 0.01 meq / g or more and 0.09 meq / g or less.

[0052] As the anionic water-dispersible urethane-based resin B, a water-dispersible urethane-based resin having a urethane skeleton and having water-dispersibility can be used. As the water-dispersible urethane-based resin, for example, a urethane-based resin containing, in addition to a urethane bond, one or more bonds selected from the group consisting of an ether bond, an ester bond, and a carbonate bond in the main chain can be used. Specific examples of the anionic water-dispersible urethane resin B include polyether-type urethane resins containing ether bonds in the main chain in addition to urethane bonds, polyester-type urethane resins containing ester bonds in the main chain, polyester-ether-type urethane resins containing ether bonds and ester bonds in the main chain, and polycarbonate-type urethane resins containing carbonate bonds in the main chain. Of these, polycarbonate-type urethane resins and polyester-type urethane resins are preferred.

[0053] When the ink contains anionic water-dispersible urethane resin B, the flexibility of the urethane resin makes it easier for the printed image to follow processing, and the image can be prevented from cracking or becoming whitish due to processing.

[0054] The anionic water-dispersible urethane resin B exhibits water dispersibility, and therefore can disperse in water in particulate form without dissolving in water to form an oil-in-water (O / W) resin emulsion. The anionic water-dispersible urethane resin B is preferably contained in the ink in a dispersed state as resin particles. The anionic water-dispersible urethane resin B may be a resin in which an anionic functional group is present on the surface of the resin particles, as in the case of a self-emulsifying resin, or may be a resin that has been surface-treated by adhering an anionic resin particle dispersant to the surface of the resin particles. Examples of the anionic functional group include a carboxy group, a sulfo group, and a phosphate group. Examples of the anionic resin particle dispersant include an anionic surfactant.

[0055] The anionic water-dispersible urethane resin B has a negative surface charge, and the absolute value of the amount of surface charge is preferably 0.01 meq / g or more and 0.09 meq / g or less.

[0056] From the viewpoints of the anionic water-dispersible urethane resin B exhibiting anionic properties, improving the aggregation of ink components upon contact between the pretreatment liquid and the ink, and suppressing bleeding of ink dots to improve the quality of printed images, the absolute value of the surface charge quantity of the anionic water-dispersible resin is preferably 0.01 meq / g or more, more preferably 0.02 meq / g or more, and even more preferably 0.03 meq / g or more.

[0057] From the viewpoint of controlling the degree of aggregation so that the ink components do not aggregate excessively and suppressing excessive reduction in ink dot size and cracking in the image to improve the quality of the printed image, it is preferable that the absolute value of the surface charge quantity of the anionic water-dispersible resin be 0.09 meq / g or less.

[0058] From the viewpoint of achieving appropriate aggregation of the ink components and thereby improving the quality of the printed image, the absolute value of the surface charge of the anionic water-dispersible resin is preferably 0.01 meq / g or more and 0.09 meq / g or less, more preferably 0.02 meq / g or more and 0.09 meq / g or less, and even more preferably 0.03 meq / g or more and 0.09 meq / g or less.

[0059] The glass transition point of the anionic water-dispersible urethane resin B is preferably −40° C. to 40° C., and more preferably −30 to 30° C. From the viewpoints of suppressing shrinkage due to drying and suppressing cracking of the printed image, the glass transition point of the anionic water-dispersible urethane resin B is preferably −40° C. or higher, and more preferably −30° C. or higher. From the viewpoints of achieving good film formation during low-temperature drying and suppressing image cracking due to excessive hardness of the film during processing, the glass transition point of the anionic water-dispersible urethane resin B is preferably 40° C. or lower, and more preferably 30° C. or lower. The glass transition point can be measured by differential scanning calorimetry (DSC).

[0060] The anionic water-dispersible urethane resin B is preferably a resin that forms a transparent coating film on the substrate, thereby reducing the effect on the color development of the water-based ink.

[0061] The weight average molecular weight (Mw) of the anionic water-dispersible urethane resin B is not particularly limited, but is preferably from 10,000 to 100,000, and more preferably from 15,000 to 80,000.

[0062] The anionic water-dispersible urethane resin B can be blended into the ink as an oil-in-water (O / W) type resin emulsion that becomes particulate in the ink, and preferably becomes resin particles in the ink. The average particle size of the resin particles in the ink of the anionic water-dispersible urethane resin B may be any size suitable for inkjet printing, and is generally preferably 300 nm or less. From the viewpoints of ink ejection performance and storage stability, this average particle size is more preferably 250 nm or less, even more preferably 200 nm or less, and even more preferably 150 nm or less. Furthermore, when a pigment is used as the colorant, from the viewpoint of further improving the binding between pigment particles, the average particle size of the resin particles is preferably smaller than the average particle size of the pigment (generally about 80 to 200 nm). Furthermore, the lower limit of the average particle size of the resin particles of the anionic water-dispersible urethane resin B in the ink is not particularly limited, but from the viewpoint of the storage stability of the ink, it is preferably 5 nm or more, and more preferably 10 nm or more.

[0063] In this specification, unless otherwise specified, the average particle size refers to the volume-based particle size value (median size) in the particle size distribution measured by dynamic light scattering. As a dynamic light scattering particle size distribution measuring device, a nanoparticle analyzer nanoPartica SZ-100 (Horiba, Ltd.) or the like can be used.

[0064] Commercially available resin emulsions of anionic water-dispersible urethane resin B include, for example, "Superflex 470" and "Superflex 460S" manufactured by Daiichi Kogyo Seiyaku Co., Ltd. (both trade names).

[0065] The anionic water-dispersible urethane resin B may be used alone or in combination of two or more.

[0066] The anionic water-dispersible urethane resin B preferably accounts for 1.0% by mass or more and 15% by mass or less in terms of the amount of active ingredient relative to the total amount of the ink.

[0067] From the viewpoint of improving the aggregation of ink components, suppressing bleeding of ink dots, and improving the quality of printed images, and from the viewpoint of improving the durability of printed images by improving fixation, the amount of anionic water-dispersible urethane-based resin B, in terms of active ingredient, relative to the total amount of ink is preferably 1.0% by mass or more, more preferably 2.0% by mass or more, even more preferably 3.0% by mass or more, and even more preferably 5.0% by mass or more.

[0068] From the viewpoint of controlling the degree of aggregation so that the ink components do not aggregate excessively, suppressing excessive reduction in ink dot size and image cracking, and improving the quality of printed images, the amount of anionic water-dispersible urethane-based resin B, in terms of the amount of active ingredient, is preferably 15% by mass or less, and more preferably 12% by mass or less, of the total amount of ink.

[0069] The anionic water-dispersible urethane resin B preferably contains, in active ingredient amount, 1.0% by mass or more and 15% by mass or less, more preferably 2.0% by mass or more and 15% by mass or less, even more preferably 3.0% by mass or more and 12% by mass or less, and even more preferably 5.0% by mass or more and 12% by mass or less, based on the total amount of ink.

[0070] The amount of the anionic water-dispersible urethane resin B (amount of active ingredient) is preferably 0.1 to 10, more preferably 0.1 to 8, and even more preferably 0.5 to 5, parts by mass of the colorant per part by mass.

[0071] In addition to the anionic water-dispersible urethane resin B, the ink may contain another water-dispersible resin (hereinafter, sometimes referred to as "water-dispersible resin C").

[0072] The water-dispersible resin C exhibits water dispersibility, and therefore can disperse in water in particulate form without dissolving in water to form an oil-in-water (O / W) resin emulsion. The water-dispersible resin C is preferably contained in the ink in a dispersed state as resin particles. From the viewpoint of ink stability, the water-dispersible resin C is preferably an anionic resin, an amphoteric resin, a nonionic resin, or a combination thereof, and more preferably an anionic resin. The water-dispersible resin C may be a resin in which functional groups are present on the resin particle surface, such as a self-emulsifying resin, or may be a resin that has undergone surface treatment, such as by attaching a dispersant to the resin particle surface. When an anionic water-dispersible resin is used as the water-dispersible resin C, the anionic water-dispersible resin may be a resin in which anionic functional groups are present on the resin particle surface, such as a self-emulsifying resin, or may be a resin that has undergone surface treatment, such as by attaching an anionic dispersant to the resin particle surface. Examples of anionic functional groups include carboxy groups, sulfo groups, and phosphate groups. Examples of anionic resin particle dispersants include anionic surfactants.

[0073] The water-dispersible resin C preferably has a negative surface charge. The water-dispersible resin C is an anionic water-dispersible resin, and the absolute value of the surface charge is preferably 0.01 meq / g or more and 0.09 meq / g or less, more preferably 0.02 meq / g or more and 0.09 meq / g or less, and even more preferably 0.03 meq / g or more and 0.09 meq / g or less. The absolute value of the surface charge of the anionic water-dispersible resin is preferably 0.01 meq / g or more, more preferably 0.02 meq / g or more and even more preferably 0.03 meq / g or more. The absolute value of the surface charge of the anionic water-dispersible resin is preferably 0.09 meq / g or less. The surface charge of the anionic water-dispersible resin can be obtained in the same manner as the surface charge of the anionic water-dispersible urethane resin B described above.

[0074] The water-dispersible resin C is preferably a resin that forms a transparent coating film on the substrate, thereby reducing the effect on the color development of the water-based ink.

[0075] The weight average molecular weight (Mw) of the water-dispersible resin C is not particularly limited, but is preferably from 1,000 to 100,000, and more preferably from 5,000 to 80,000.

[0076] The water-dispersible resin C can be blended into the ink as an oil-in-water (O / W) type resin emulsion that becomes particulate in the ink, and preferably becomes particulate in the ink. The average particle size of the resin particles of the water-dispersible resin C in the ink may be any size suitable for inkjet printing, and is preferably in the same range as that of the anionic water-dispersible urethane resin B.

[0077] Examples of the water-dispersible resin C include (meth)acrylic resins, ethylene-vinyl chloride copolymer resins, styrene-maleic anhydride copolymer resins, and vinyl acetate-ethylene copolymer resins. These water-dispersible resins can be blended into the ink as oil-in-water (O / W) resin emulsions. As the water-dispersible resin C, water-dispersible (meth)acrylic resins are preferred, and anionic water-dispersible (meth)acrylic resins are more preferred.

[0078] The water-dispersible (meth)acrylic resin is preferably a polymer containing units derived from a (meth)acrylic monomer. The water-dispersible (meth)acrylic resin may contain units derived from other monomers in addition to the units derived from the (meth)acrylic monomer. Examples of (meth)acrylic monomers include acrylic acid, methacrylic acid, acrylate, methacrylate, acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, and derivatives thereof, which may be used alone or in combination of two or more. Examples of other units include styrene units, vinyl acetate units, vinyl chloride units, etc. These may be used alone or in combination of two or more. Examples of the water-dispersible (meth)acrylic resin include a (meth)acrylic polymer, a styrene-(meth)acrylic copolymer, a vinyl acetate-(meth)acrylic copolymer, a vinyl chloride-(meth)acrylic copolymer, or a combination thereof. Preferred are a (meth)acrylic polymer, a styrene-(meth)acrylic copolymer, or a combination thereof.

[0079] Commercially available resin emulsions of water-dispersible (meth)acrylic resins include "Mowinyl 9780," "Mowinyl 727," "Mowinyl 745," "Mowinyl 966A," and "Mowinyl 940" manufactured by Japan Coating Resins Co., Ltd.; "Joncryl 7100," "Joncryl PDX-7370," and "Joncryl PDX-7341" manufactured by BASF; "Boncoat EC-905EF," "Boncoat 5400EF," and "Boncoat CG-8400" manufactured by DIC Corporation; and "NeoCryl A-1125," "NeoCryl A-1127," "NeoCryl A-6069," "NeoCryl A-1092," and "NeoCryl A-2092" manufactured by DSM (all trade names).

[0080] The above-mentioned water-dispersible resin C may be used alone or in combination of two or more kinds. When the ink contains water-dispersible resin C, the amount of water-dispersible resin C in terms of active ingredient is preferably 0.1 to 15 mass %, more preferably 1 to 10 mass %, and even more preferably 2 to 8 mass %, relative to the total amount of ink. The amount of the active ingredient of the water-dispersible resin C is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 2% by mass or more, based on the total amount of the ink. The amount of the active ingredient of the water-dispersible resin C is preferably 15% by mass or less, more preferably 10% by mass or less, and even more preferably 8% by mass or less, based on the total amount of the ink.

[0081] When the ink contains water-dispersible resin C, the amount of water-dispersible resin C (amount of active ingredient) is preferably 0.1 to 8 parts by mass, more preferably 0.5 to 2 parts by mass, per 1 part by mass of colorant.

[0082] The anionic water-dispersible urethane resin B preferably accounts for 20% by mass or more, and more preferably 35% by mass or more, in terms of the amount of active ingredients, relative to the total amount of all resins contained in the ink. When the ink contains water-dispersible resin C, the total amount of anionic water-dispersible urethane resin B and water-dispersible resin C relative to the total amount of all resins contained in the ink is preferably 50% by mass or more, and more preferably 70% by mass or more, in terms of the amount of active ingredients. The total amount of all water-dispersible resins in the ink, including the anionic water-dispersible urethane resin B, is preferably 1 to 20 mass %, more preferably 2 to 15 mass %, and even more preferably 3 to 15 mass %, of the total amount of ink, in terms of the amount of active ingredients.

[0083] The aqueous inkjet ink may contain a coloring material. The coloring material may include a pigment, a dye, or a combination thereof. In terms of weather resistance and color development of the image, a pigment is preferably used.

[0084] The pigment can be preferably incorporated into the ink as a pigment dispersion. The pigment dispersion may be any one that allows the pigment to be dispersed in a solvent and maintains a dispersed state in the ink. For example, a pigment dispersed in water with a pigment dispersant, a self-dispersing pigment dispersed in water, or a microencapsulated pigment coated with a resin dispersed in water may be used.

[0085] Examples of pigments that can be used include organic pigments such as azo pigments, phthalocyanine pigments, polycyclic pigments, and dye lake pigments; and inorganic pigments such as carbon black and metal oxides. Examples of azo pigments include soluble azo lake pigments, insoluble azo pigments, and condensed azo pigments. Examples of phthalocyanine pigments include metal phthalocyanine pigments such as copper phthalocyanine pigments, and metal-free phthalocyanine pigments. Examples of polycyclic pigments include quinacridone pigments, perylene pigments, perinone pigments, isoindoline pigments, isoindolinone pigments, dioxazine pigments, thioindigo pigments, anthraquinone pigments, quinophthalone pigments, metal complex pigments, and diketopyrrolopyrrole (DPP). Examples of carbon black include furnace carbon black, lamp black, acetylene black, and channel black.

[0086] Further, examples of organic pigments include brilliant carmine 6B, lake red C, watching red, disazo yellow, Hansa yellow, phthalocyanine blue, phthalocyanine green, alkali blue, and aniline black. Examples of inorganic pigments include metals such as cobalt, iron, chromium, copper, zinc, lead, titanium, vanadium, manganese, and nickel, oxides and sulfides of these metals, as well as yellow ochre, ultramarine, and iron blue. Furthermore, a white pigment may be used as the pigment, and examples of the white pigment include inorganic pigments such as titanium oxide, zinc white, zinc sulfide, antimony oxide, and zirconium oxide.

[0087] The average particle size of these pigments is preferably 50 to 500 nm, more preferably 50 to 200 nm. From the viewpoint of color development, the average particle size of these pigments is preferably 50 nm or more, and from the viewpoint of ejection stability, the average particle size is preferably 500 nm or less.

[0088] In order to stably disperse the pigment in the ink, a pigment dispersant such as a polymer dispersant or a surfactant can be preferably used. Commercially available polymer dispersants include, for example, the TEGO Disperse series manufactured by EVONIK, including "TEGO Disperse 740W," "TEGO Disperse 750W," "TEGO Disperse 755W," "TEGO Disperse 757W," and "TEGO Disperse 760W," and the Solsperse series manufactured by Lubrizol Japan, including "Solsperse 20000," "Solsperse 27000," "Solsperse 41000," "Solsperse 41090," "Solsperse 43000," "Solsperse 44000," and "Solsperse 45000." Examples include "Rusperse 46000," Johnson Polymer's Johncryl series "Johncryl 57," "Johncryl 60," "Johncryl 62," "Johncryl 63," "Johncryl 71," and "Johncryl 501," BYK's "DISPERBYK-102," "DISPERBYK-185," "DISPERBYK-190," "DISPERBYK-193," and "DISPERBYK-199," and Dai-ichi Kogyo Seiyaku's polyvinylpyrrolidone "K-30" and "K-90" (all of which are trade names).

[0089] As the surfactant-type dispersant, a nonionic surfactant can be preferably used, taking into consideration the dispersion stability of the pigment in the ink and the influence of ionicity from the pretreatment liquid. Commercially available surfactant-type dispersants include, for example, nonionic surfactants such as the Emulgen series manufactured by Kao Corporation, including "Emulgen A-60," "Emulgen A-90," "Emulgen A-500," "Emulgen B-40," "Emulgen L-40," and "Emulgen 420" (all trade names).

[0090] These pigment dispersants can be used alone or in combination of two or more. When a pigment dispersant is used, the amount of pigment dispersant added varies depending on the type of pigment dispersant and is not particularly limited. For example, the pigment dispersant can be added in a mass ratio of active ingredients ranging from 0.005 to 0.5 per 1 part pigment.

[0091] A self-dispersing pigment may be blended as a colorant. A self-dispersing pigment is a pigment in which a hydrophilic functional group has been introduced onto its surface by chemical or physical treatment. The hydrophilic functional group introduced into the self-dispersing pigment is preferably ionic, and by charging the pigment surface anionically or cationically, the pigment particles can be stably dispersed in water due to electrostatic repulsion. Preferred anionic functional groups include sulfonic acid groups, carboxy groups, carbonyl groups, hydroxy groups, and phosphonic acid groups. Preferred cationic functional groups include quaternary ammonium groups and quaternary phosphonium groups.

[0092] These hydrophilic functional groups may be bonded directly to the pigment surface or via other atomic groups. Examples of such other atomic groups include, but are not limited to, alkylene groups, phenylene groups, and naphthylene groups. Examples of methods for treating the pigment surface include diazotization, sulfonation, hypochlorous acid treatment, humic acid treatment, and vacuum plasma treatment.

[0093] Preferred examples of self-dispersing pigments that can be used include the CAB-O-JET series manufactured by Cabot Corporation, such as "CAB-O-JET200," "CAB-O-JET300," "CAB-O-JET250C," "CAB-O-JET260M," and "CAB-O-JET270," and "BONJET BLACK CW-1," "BONJET BLACK CW-2," and "BONJET BLACK CW-4" manufactured by Orient Chemical Industries Co., Ltd. (all trade names).

[0094] A pigment dispersion in which the pigment is pre-dispersed with a pigment dispersant may be used. Commercially available pigment dispersions dispersed with a pigment dispersant include, for example, the HOSTAJET series manufactured by Clariant and the FUJI SP series manufactured by Fuji Pigment Co., Ltd. (both are trade names). A pigment dispersion dispersed with the above-mentioned pigment dispersant may also be used. Alternatively, a microencapsulated pigment in which the pigment is coated with a resin may also be used.

[0095] A dye may be blended as a coloring material. Any dye commonly used in the printing technical field can be used as the dye, and is not particularly limited. Specific examples include basic dyes, acid dyes, direct dyes, soluble vat dyes, acid mordant dyes, mordant dyes, reactive dyes, vat dyes, and sulfide dyes. Among these, water-soluble dyes and those that become water-soluble upon reduction or the like are preferably used. More specific examples include azo dyes, rhodamine dyes, methine dyes, azomethine dyes, xanthene dyes, quinone dyes, triphenylmethane dyes, diphenylmethane dyes, and methylene blue.

[0096] The above coloring materials can be used alone or in combination of two or more. The amount of the coloring material, in terms of the amount of active ingredients, is preferably 0.1 to 20% by mass, more preferably 1 to 10% by mass, and even more preferably 2 to 8% by mass, relative to the total amount of the ink.

[0097] The ink preferably contains water as an aqueous solvent, and may be a primary solvent. When the resin emulsion, pigment dispersion, or the like contains water as a solvent, the water in each component is calculated as a portion of the water in the ink when preparing the ink. The water is not particularly limited, but is preferably one that contains as few ionic components as possible. In particular, from the viewpoint of ink storage stability, it is preferable that the content of polyvalent metal ions such as calcium is low. Examples of water that can be used include ion-exchanged water, distilled water, and ultrapure water.

[0098] From the viewpoint of adjusting the ink viscosity, the water content is preferably 20 to 90% by mass, and more preferably 30 to 80% by mass, of the total amount of the ink.

[0099] The ink may contain a water-soluble organic solvent. The water-soluble organic solvent is preferably compatible with water. As the water-soluble organic solvent, an organic compound that is liquid at room temperature and soluble or miscible in water may be used, and it is preferable to use a water-soluble organic solvent that is uniformly mixed with an equal volume of water at 20°C under 1 atmosphere.

[0100] The water-soluble organic solvent may be, for example, one of the water-soluble organic solvents that can be blended in the pretreatment liquid, or a combination of two or more of them. When two or more of them are mixed, a combination that can form a single phase with water is preferred.

[0101] Among the water-soluble organic solvents, glycols, glycerins, glycol ethers, and combinations thereof are preferably used, and glycol ethers are more preferred because these water-soluble organic solvents have better compatibility with water. Among the water-soluble organic solvents, it is preferable to use a low-polarity solvent, for example, one or more low-polarity solvents selected from the low-polarity solvents that can be blended in the pretreatment liquid.

[0102] From the viewpoint of viscosity adjustment and moisturizing effect, the water-soluble organic solvent may be contained in an amount of, for example, 1 to 60 mass % of the total amount of ink, more preferably 5 to 40 mass %, and even more preferably 10 to 30 mass %. The amount of the low-polarity water-soluble organic solvent is preferably 1 to 20% by mass, more preferably 1 to 10% by mass, based on the total amount of the ink.

[0103] The ink may contain a surfactant. As the surfactant, a nonionic surfactant, an anionic surfactant, or a combination thereof can be preferably used, and a nonionic surfactant is more preferred.

[0104] The HLB value of the surfactant is preferably 5-20.

[0105] As the surfactant, for example, one or a combination of two or more surfactants selected from those that can be added to the pretreatment liquid described above can be used.

[0106] The surfactant content is preferably 0.1 to 10% by mass, more preferably 0.2 to 5% by mass, and even more preferably 0.5 to 2% by mass, based on the total amount of the ink.

[0107] In addition to the above components, the ink may optionally contain a wetting agent (moisturizing agent), a surface tension adjuster (penetrating agent), an antifoaming agent, a fixing agent, a pH adjuster, an antioxidant, a preservative, etc.

[0108] The suitable range of ink viscosity varies depending on factors such as the nozzle diameter of the ejection head and the ejection environment, but in general, a viscosity of 1 to 30 mPa·s at 23°C is preferred, and a viscosity of 5 to 15 mPa·s is more preferred, making it suitable for use in inkjet printing devices.

[0109] The method for preparing the ink is not particularly limited, but the desired ink can be obtained by appropriately mixing the various components. For example, when using a pigment dispersion, a mixture of the pigment, a pigment dispersant, and water is dispersed using a disperser such as a bead mill to obtain the pigment dispersion, and then the pigment dispersion, a resin emulsion of the anionic water-dispersible urethane resin A, and water and / or other materials, as needed, are mixed together or in portions to obtain the ink. The obtained composition may also be filtered using a filter or the like.

[0110] The aqueous inkjet ink set can include the above-described pretreatment liquid and the above-described aqueous inkjet ink. The aqueous inkjet ink set may further include other inks and / or a post-treatment agent, etc.

[0111] "Base material" The aqueous inkjet ink set can be applied to both permeable and low-permeable substrates. In particular, the image quality and processability of printed images can be further improved for low-permeable substrates.

[0112] A low-permeability substrate is a substrate into which liquid does not penetrate, specifically a substrate in which most of the liquid in the ink remains on the surface of the substrate. Examples of low-permeability substrates include metal substrates such as metal plates made of aluminum, iron, copper, titanium, tin, chromium, cadmium, alloys (e.g., stainless steel, steel, etc.); glass substrates such as plate glass made of borosilicate glass, quartz glass, soda-lime glass, etc.; resin substrates such as resin sheets made of PET film, OHT sheet, polyester sheet, polypropylene sheet, etc., and acrylic plate; and ceramic substrates such as molded bodies made of alumina, zirconia, steatite, silicon nitride, etc. These substrates may have a plating layer, a metal oxide layer, a resin layer, etc. formed thereon, or may have been surface-treated using a surfactant, corona treatment, etc. For example, even when a metal substrate without a resin layer is used, the image quality and processability of the printed image can be improved.

[0113] Examples of permeable substrates include printing paper such as plain paper, coated paper, and special paper; fabrics such as woven fabrics and nonwoven fabrics; porous building materials for humidity control, sound absorption, and heat insulation; wood, concrete, and porous materials.

[0114] <Manufacturing method for printed matter> A method for producing a printed item according to one embodiment includes applying a pretreatment liquid to a substrate (hereinafter also referred to as "step 1") and applying an aqueous inkjet ink to the substrate to which the pretreatment liquid has been applied by an inkjet method (hereinafter also referred to as "step 2"), wherein the pretreatment liquid contains a cationic water-soluble resin (cationic water-soluble resin A) having an absolute value of a surface charge of 5.5 meq / g or less, and the cationic water-soluble resin A accounts for 1.0% to 20% by mass of the total amount of the pretreatment liquid, and the aqueous inkjet ink contains water, a colorant, and an anionic water-dispersible urethane resin (anionic water-dispersible urethane resin B) having an absolute value of a surface charge of 0.01 meq / g to 0.09 meq / g, and the anionic water-dispersible urethane resin B accounts for 1.0% to 15% by mass of the total amount of the aqueous inkjet ink.

[0115] The pretreatment liquid may be any of the pretreatment liquids described above. The aqueous inkjet ink may be any of the aqueous inkjet inks described above. The substrate may be any of the substrates described above. The above-mentioned aqueous inkjet ink set may also be used.

[0116] In step 1, the method for applying the pretreatment liquid to the substrate is not particularly limited, and for example, an inkjet method may be used, or the required amount may be applied using a roller, a spray, etc. When an inkjet method is used, examples of the inkjet printing device include those that can be used in step 2 described below. The pretreatment liquid may be applied to the entire surface of the substrate, or may be applied selectively only to the image area. Alternatively, the pretreatment liquid may be applied only to areas where a certain amount of ink or more is to be applied per unit area, such as solid image areas. For example, the pretreatment liquid may be applied to an area that includes at least a portion of the area where ink is to be applied.

[0117] The amount of pretreatment liquid applied is 1 to 200 g / m per unit area. 2 is preferable, and 5 to 100 g / m 2 More preferably, 10 to 50 g / m 2 is more preferable.

[0118] In step 2, an inkjet system can be used as a method for applying the aqueous inkjet ink to the substrate to which the pretreatment liquid has been applied. The inkjet printing device used for application by the inkjet system may be any type, such as a piezoelectric system, an electrostatic system, or a thermal system, and it is preferable that the ink is ejected from an inkjet head based on a digital signal and the ejected ink droplets are deposited on the substrate.

[0119] The amount of ink applied is 1 to 200 g / m per unit area. 2 is preferable, and 5 to 100 g / m 2 More preferably, 10 to 50 g / m 2 is more preferable.

[0120] From the viewpoint of obtaining a printed image with superior image quality by improving the balance between the amount of anionic water-dispersible urethane resin B and the amount of cationic water-soluble resin A and making the dot size of the printed image more appropriate, the amount of cationic water-soluble resin A relative to the total amount of pretreatment liquid is set to X1 (mass %), and the amount of pretreatment liquid applied per unit area is set to X2 (g / m 2 ), the amount of anionic water-dispersible urethane resin B relative to the total amount of aqueous inkjet ink is Y1 (mass %), and the amount of aqueous inkjet ink applied per unit area is Y2 (g / m 2 ), the ratio Z represented by the following formula (1) is preferably 0.5 or more and 1.5 or less.

[0121] Ratio Z=(X1×X2) / (Y1×Y2) Equation (1)

[0122] When the ratio Z is 0.5 or more and 1.5 or less, the urethane resin aggregates appropriately, and the durability and processability of the printed image can be further improved.

[0123] The ratio Z may be, for example, 0.1 or more, or 0.2 or more. The ratio Z is preferably 0.5 or more, and more preferably 0.7 or more. On the other hand, the ratio Z may be, for example, 5.5 or less, or 2.5 or less. The ratio Z is preferably 1.5 or less, and more preferably 1.2 or less. The ratio Z may be, for example, 0.1 or more and 5.5 or less, or 0.2 or more and 2.5 or less. The ratio Z is preferably 0.5 or more and 1.5 or less, and more preferably 0.7 or more and 1.2 or less.

[0124] The method for producing the printed matter may include a heat treatment step. For example, it is preferable to carry out heat treatment to remove volatile components after step 1 and / or step 2. The heat treatment temperature is preferably 25° C. to 150° C., more preferably 50° C. to 120° C. The heat treatment time is preferably 10 seconds to 60 minutes, more preferably about 1 to 30 minutes.

[0125] After applying the ink to the substrate, a step of post-treating the substrate to form an overcoat layer may be further provided. The method of post-treating the substrate may be, for example, by applying a post-treatment agent to the substrate.

[0126] According to one embodiment, a printed material is provided. The printed material of one embodiment has a substrate, a pretreatment layer formed on the substrate, and an ink image layer formed on the pretreatment layer. The substrate may be the substrate described above. The pretreatment layer may be a layer obtained using the pretreatment liquid described above, and the ink image layer may be a layer obtained using the aqueous inkjet ink described above. The printed material can be produced, for example, using the aqueous inkjet ink set described above. The printed material of one embodiment can be produced, for example, using the aqueous inkjet ink set described above. The printed material can be produced, for example, using the method for producing a printed material described above. [Example]

[0127] The present invention will be described in more detail below with reference to examples. The present invention is not limited to the following examples. In the following description, "%" means "% by mass" unless otherwise specified.

[0128] <Preparation of pretreatment solution> Tables 1 and 2 show the formulations of pretreatment solutions 1 to 12. When the component contains a solvent or the like, the blending amount of each component in the tables is the total amount including the solvent or the like. The components were mixed according to the formulation of the pretreatment liquid shown in the table, and then filtered through a membrane filter with a pore size of 3 μm to obtain pretreatment liquids 1 to 12.

[0129] The ingredients used are as follows: (Component 1a: Cationic water-soluble resin) Cationic water-soluble resin 1: "Himax SC-700M" manufactured by Himo Co., Ltd., copolymer of acrylamide, acrylonitrile, N-vinylacrylamidine hydrochloride, N-vinylacrylamide, vinylamine hydrochloride, and N-vinylformamide, active ingredient 35.0% by mass Cationic water-soluble resin 2: Unisense KCA101L manufactured by Senka Corporation, diallylamine hydrochloride-acrylamide copolymer, active ingredient 23.0% by mass Cationic water-soluble resin 3: "Himax SC-506" manufactured by Himo Co., Ltd., quaternary ammonium salt of alkylamine-epichlorohydrin adduct, active ingredient 60.0% by mass Cationic water-soluble resin 4: Senka Corporation's "Unisense KHE1000L" diallyldimethylammonium chloride-acrylamide copolymer, active ingredient 23.0% by mass

[0130] (Component 1b: Polyvalent metal salt) Calcium chloride: Fujifilm Wako Pure Chemical Industries, Ltd. "Calcium chloride 10%", active ingredient 10.0% by mass

[0131] (Component 2: Binder resin (resin emulsion)) Cationic (meth)acrylic resin emulsion 1: "Polysol AP-1370" manufactured by Showa Denko K.K., active ingredient 32.5% by mass Cationic (meth)acrylic resin emulsion 2: "Polysol AP-1350" manufactured by Showa Denko K.K., active ingredient 46.5% by mass

[0132] (Component 3: Water-soluble organic solvent) Glycerin, ethylene glycol, and diethylene glycol monoethyl ether in the table are available from Fujifilm Wako Pure Chemical Industries, Ltd.

[0133] (Component 4: Surfactant) Acetylene glycol surfactant: Evonik Industries "Surfynol 440" (non-ionic), active ingredient 100.0% by mass

[0134] The absolute values ​​of the surface charge of the cationic water-soluble resin, polyvalent metal salt, and binder resin listed in Tables 1 and 2 were determined as follows. Aqueous samples were prepared for each of cationic water-soluble resins 1 to 4, calcium chloride, and cationic (meth)acrylic resin emulsions 1 and 2. The aqueous samples were diluted to a concentration of 0.03% active ingredient and titrated with N / 400 PVSK solution (0.0025N potassium polyvinyl sulfate titrant, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) using a colloid particle charge meter (Model CAS, manufactured by AFG ANALYTIC GmbH). The total charge of the aqueous sample was calculated from the amount of N / 400 PVSK solution used until the reaction endpoint, at which the streaming potential reached 0 mV, was reached. The total charge of the aqueous sample was divided by the amount of active ingredient (i.e., cationic water-soluble resin, polyvalent metal salt, or binder resin) to determine the surface charge (unit: meq / g). The absolute value of this value was used as the absolute value of the surface charge (unit: meq / g).

[0135] [Table 1]

[0136] [Table 2]

[0137] <Preparation of pigment dispersion> Table 3 shows the pigment dispersion formulation. The components were premixed according to the formula shown in the table. Then, 300 g of the mixture was placed in a 500 mL PP (polypropylene) container, and 0.5 mm diameter zirconia beads were added so that the total volume in the PP container was approximately 90% of the container's capacity. This PP container was placed in a rocking mill (manufactured by Seiwa Giken Co., Ltd.) and dispersed for 2 hours. The zirconia beads were then separated from the dispersion, yielding a magenta dispersion.

[0138] The ingredients used are as follows: Magenta pigment: DIC Corporation's "FASTOGEN SUPER MAGENTA RGT" (quinacridone pigment) Acrylic polymer dispersant: BYK "DISPERBYK-190", active ingredient 40% by weight pH adjuster: "TEA (triethanolamine)" manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Preservative: "PROXEL XL2(S)" manufactured by Lonza Japan Co., Ltd.

[0139] [Table 3]

[0140] <Ink preparation> Tables 4 and 5 show the formulations of inks 1 to 9. When the component contains a solvent or the like, the blend amount of each component in the tables is the total amount including the solvent or the like. Each component was mixed according to the ink formulation shown in each table, and then filtered through a membrane filter with a pore size of 3 μm to obtain an ink.

[0141] The ingredients used are as follows: (Component 1: Pigment dispersion) Magenta dispersion: Produced by the above procedure, pigment content 20% by mass

[0142] (Component 2a: Anionic urethane resin emulsion) Anionic urethane resin emulsion 1: "Superflex 470" manufactured by Daiichi Kogyo Seiyaku Co., Ltd., active ingredient 38.0% by mass Anionic urethane resin emulsion 2: "Superflex 460S" manufactured by Daiichi Kogyo Seiyaku Co., Ltd., active ingredient 38.0% by mass Anionic urethane resin emulsion 3: "NeoRez R-986" manufactured by DSM, active ingredient 25.0% by mass

[0143] (Component 2b: (meth)acrylic resin emulsion) Anionic (meth)acrylic resin emulsion: "Movinyl 966A" manufactured by Japan Coating Resin Co., Ltd., active ingredient 45.0% by mass

[0144] (Component 3: Water-soluble organic solvent) Glycerin, ethylene glycol, and diethylene glycol monoethyl ether in the table are available from Fujifilm Wako Pure Chemical Industries, Ltd.

[0145] (Component 4: Surfactant) Acetylene glycol surfactant: Evonik Industries "Surfynol 440" (non-ionic), active ingredient 100.0% by mass

[0146] The absolute values ​​of the surface charge of the anionic urethane resin emulsions and (meth)acrylic resin emulsions listed in Tables 4 and 5 were calculated as follows. Aqueous samples were prepared for each of the anionic urethane resin emulsions 1 to 3 and the anionic (meth)acrylic resin emulsion. The aqueous samples were diluted to a concentration of 0.03% active ingredient and titrated with N / 400 DADMAC solution (0.0025N poly(diallyldimethylammonium chloride) solution, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) using a colloid particle charge meter (Model CAS, manufactured by AFG ANALYTIC GmbH). The total charge of the aqueous sample was calculated from the amount of N / 400 DADMAC solution used until the reaction endpoint, at which the streaming potential reached 0 mV, was reached. The surface charge (unit: meq / g) was calculated by dividing the total charge of the aqueous sample by the amount of active ingredient of the resin in the aqueous sample. The absolute value of this value was used as the absolute value of the surface charge (unit: meq / g).

[0147] [Table 4]

[0148] [Table 5]

[0149] <Evaluation method> Decorative articles were produced using the inks obtained according to the following procedures, and the following evaluations were carried out. The results are shown in Tables 6 to 9. A white-painted aluminum plate (Nikkaru Shoko Co., Ltd., aluminum flat plate) was used as the substrate. A 20g / m wet application of the pretreatment solution was applied to a 10cm x 10cm cut white-coated aluminum plate using an air spray. 2 The white-painted aluminum plate was then heated in an oven at 120°C for 10 minutes. The ink was introduced into the inkjet head of an inkjet printer (Anajet mPower-10 manufactured by Anajet), and a magenta monochrome solid image was printed at the highest density possible with the printer on a white-coated aluminum plate that had been subjected to the pretreatment liquid application and heat treatment as described above, with a wet coating amount of 20 g / m. 2 It was printed to be. After printing, the printed matter was dried by heating in an oven at 150°C for 10 minutes, and the resulting printed matter was used as a decorated article.

[0150] In Tables 6 to 9, the ratio Z is the amount of cationic water-soluble resin with an absolute surface charge of 5.5 meq / g or less relative to the total amount of pretreatment liquid, X1 (mass %), and the wet application amount of pretreatment liquid per unit area, X2 (g / m 2 ), the amount of anionic water-dispersible urethane resin with an absolute value of surface charge of 0.01 meq / g or more and 0.09 meq / g or less relative to the total amount of aqueous inkjet ink is Y1 (mass %), and the wet coating amount of aqueous inkjet ink per unit area is Y2 (g / m 2 ) is the value obtained by the following formula (1).

[0151] Ratio Z=(X1×X2) / (Y1×Y2) Equation (1)

[0152] (Image quality of printed images) The image portion of the resulting decorated article was observed under a zoom microscope to check the density and uniformity of the solid image, as well as the presence of cracks. The image quality was evaluated according to the following evaluation criteria. AA: A dense, uniform solid image is formed A: The color is slightly pale, but a uniform solid image is formed. B: There are cracks in some parts of the solid image. C: The solid image is light and uneven in color, or cracks are visible throughout the solid image.

[0153] (Durability of printed images) The image portion of the resulting decorated article was subjected to a load of 60 kg / m 2 The surface of the substrate was then reciprocated with steel wool over a 9 cm x 9 cm area, and changes in the surface of the substrate were observed. The durability of the printed image was evaluated according to the following criteria. AA: No significant change in image even after rubbing 20 times A: After rubbing 20 times, part of the image becomes whitish. B: Part of the image peels off after 20 strokes or less C: Part of the image peels off after 10 strokes or less

[0154] (Printed image processing ability) The resulting decorated article was bent at 90 degrees using a bender, and the change in the image at the bent portion was observed. The processability of the printed image was evaluated according to the following evaluation criteria. AA: No whitening due to microcracks in the image was observed due to bending. A: No whitening was observed, but minute cracks were observed under a magnifying glass. B: Whitening was observed, but no peeling was observed C: Whitening was observed and peeling occurred from the cracked area of ​​the image.

[0155] [Table 6]

[0156] [Table 7]

[0157] [Table 8]

[0158] [Table 9]

[0159] As shown in each table, the printed matter (decorated article) of each example was excellent in image quality, processability, and durability of the printed image.

[0160] In Comparative Example 1, in which a pretreatment liquid containing a polyvalent metal salt but no cationic water-soluble resin was used, the image quality was inferior to that of Examples 1 to 10. In addition, whitening occurred during processing. Durability was also poor. In Comparative Examples 2 and 3, in which a pretreatment liquid containing a cationic water-soluble resin with an absolute value of the surface charge amount higher than 5.5 meq / g was used, good images could not be formed, cracks occurred, whitening occurred during processing, and durability was also poor. In Comparative Example 4, in which the amount of anionic water-dispersible urethane resin was less than 1.0% by mass of the total amount of ink, the image bled and became uneven. In addition, the processability and durability were also poor. In Comparative Example 5, in which the amount of anionic water-dispersible urethane resin was more than 15% by mass relative to the total amount of ink, the image was faint, and whitening occurred during processing. In Comparative Example 6, in which ink containing no anionic water-dispersible urethane resin was used, the processability was poor and the image quality was inferior to Examples 1 to 10. The durability was also poor. In Comparative Example 7, in which the amount of cationic water-soluble resin was less than 1.0% by mass of the total amount of the pretreatment liquid, images were not formed well and were thin and uneven. Whitening was also observed during processing. Durability was also poor. In Comparative Example 8, in which an anionic water-dispersible urethane resin having an absolute value of surface charge of more than 0.09 meq / g was used, the image was faint, whitening was observed during processing, and durability was also poor. In Comparative Example 9, in which the pretreatment liquid contained more than 20% by mass of a cationic water-soluble resin, the ink dots were small, the image was faint, and cracks were noticeable. Cracking during processing was also noticeable. Durability was also poor.

Claims

1. a pretreatment liquid and an aqueous inkjet ink, the pretreatment liquid contains a cationic water-soluble resin having an absolute value of a surface charge amount of 1.0 meq / g or more and 5.5 meq / g or less, and the content of the cationic water-soluble resin is 1.0 mass % or more and 20 mass % or less with respect to the total amount of the pretreatment liquid; the aqueous inkjet ink contains water, a colorant, and an anionic water-dispersible urethane resin having an absolute value of a surface charge of 0.01 meq / g or more and 0.09 meq / g or less, and the anionic water-dispersible urethane resin accounts for 1.0% by mass or more and 15% by mass or less of the total amount of the aqueous inkjet ink; Water-based inkjet ink set.

2. applying a pretreatment liquid to a substrate; applying an aqueous inkjet ink to the substrate to which the pretreatment liquid has been applied by an inkjet method, the pretreatment liquid contains a cationic water-soluble resin having an absolute value of a surface charge amount of 1.0 meq / g or more and 5.5 meq / g or less, and the content of the cationic water-soluble resin is 1.0 mass % or more and 20 mass % or less with respect to the total amount of the pretreatment liquid; the aqueous inkjet ink contains water, a colorant, and an anionic water-dispersible urethane resin having an absolute value of a surface charge of 0.01 meq / g or more and 0.09 meq / g or less, and the anionic water-dispersible urethane resin accounts for 1.0% by mass or more and 15% by mass or less of the total amount of the aqueous inkjet ink; Methods for producing printed materials.

3. The amount of the cationic water-soluble resin relative to the total amount of the pretreatment liquid is X １ (mass %), the amount of the pretreatment liquid applied per unit area is X ２ (g / m ２ ), the amount of the anionic water-dispersible urethane resin relative to the total amount of the aqueous inkjet ink is Y １ (mass %), the amount of the aqueous inkjet ink applied per unit area is Y ２ (g / m ２ 3. The method for producing a printed matter according to claim 2, wherein, when the ratio Z expressed by the following formula (1) is 0.5 or more and 1.5 or less: Ratio Z = (X) １ ×X ２ ) / (Y １ ×Y ２ Equation (1)

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