Printing method and printing apparatus

Abstract

To provide a printing method capable of suppressing generation of beading, and acquiring a recorded matter having excellent scratch resistance, glossiness and adhesion properties.SOLUTION: There is provided a printing method which executes to a non-permeable substrate, a primer application step, a color ink application step for applying a color ink to a region to which the primer is applied, and a clear ink application step for applying a clear ink to a region to which the color ink is applied, where the primer includes a cationic resin, a polyvalent metal salt, and a diethylene glycol alkyl ether-based organic solvent. The color ink includes resin particles whose glass transition temperature (Tg) is less than 0°C, and an organic solvent expressed by a following formula (1), the clear ink includes resin particles whose volume average particle diameter is 50 nm or smaller and the organic solvent which is expressed by the following formula (1), and a dry film of the clear ink has the glass transition temperature (Tg) in a range of 50°C or greater and less than 0°C.(In the following formula (1), R1 expresses an alkyl group whose carbon number is 1 or greater and 4 or smaller.)SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a printing method and a printing apparatus. [Background technology]

[0002] In recent years, as printer speeds have increased, problems such as uneven image quality due to beading caused by insufficient ink drying have become a concern, and the development of new primers is needed to obtain high-quality printed materials. Furthermore, in applications such as advertising, signage, and other industrial uses, as well as in packaging materials for food, beverages, and daily necessities, non-permeable recording media such as plastic films are used as recording media to improve durability such as lightfastness, water resistance, and abrasion resistance, and various inks have been developed for use in such non-permeable recording media. Examples of the aforementioned inks include water-based inks that have a low environmental impact and can be recorded directly on non-permeable recording media. However, a problem with water-based inks that can be recorded directly on non-permeable recording media is their low abrasion resistance.

[0003] Conventional printing methods using inks include, for example, a printing method using an ink set comprising a color ink containing a coloring agent and water, a primer containing malonic acid, phosphoric acid, etc., resin particles containing acidic groups selected from the group consisting of sulfo groups, salts of sulfo groups, phosphonic acid groups, salts of phosphonic acid groups, phosphoric acid groups, and salts of phosphoric acid groups, and a clear ink containing water (see, for example, Patent Document 1). [Overview of the project] [Problems that the invention aims to solve]

[0004] The present invention aims to provide a printing method that suppresses the occurrence of beading and allows for the production of a record with excellent abrasion resistance, gloss, and adhesion. [Means for solving the problem]

[0005] The printing method of the present invention as a means for solving the above problems includes a primer application step of applying a primer onto a non-permeable substrate, a color ink application step of applying color ink onto the area where the primer has been applied, a clear ink application step of applying clear ink onto at least the area where the color ink has been applied, and is a printing method having at least the above steps, the primer contains a cationic resin, a polyvalent metal salt, and a diethylene glycol alkyl ether-based organic solvent, the color ink contains resin particles having a glass transition temperature (Tg) of less than 0°C and an organic solvent represented by the following general formula (1), the clear ink contains resin particles having a volume average particle diameter of 50 nm or less and an organic solvent represented by the following general formula (1), and the dry film of the clear ink has a glass transition temperature (Tg) of 50°C or higher and less than 0°C.

Chemical formula

Advantages of the Invention

[0006] According to the present invention, it is possible to provide a printing method capable of suppressing the occurrence of beading and obtaining a recording material having excellent abrasion resistance, glossiness, and adhesion.

Brief Description of the Drawings

[0007] [Figure 1] FIG. 1 is a perspective explanatory view schematically showing an example of a printing apparatus according to the present invention. [[ID=3,8]] [Figure 2] FIG. 2 is a perspective explanatory view schematically showing an example of a main tank according to the present invention. [Figure 3] FIG. 3 is a schematic view showing an example of the printing apparatus of the present invention used in the printing method of the present invention.

Embodiments for Carrying Out the Invention

[0008] (Printing method and printing apparatus) The printing method of the present invention comprises at least a primer application step, a color ink application step, and a clear ink application step, and further includes other steps as necessary. The printing apparatus of the present invention comprises at least a primer-applying means, a color ink-applying means, and a clear ink-applying means, and further comprises other means as necessary. The primer application step can be performed by the primer application means, the color ink application step can be performed by the color ink application means, the clear ink application step can be performed by the clear ink application means, and the other steps can be performed by the other means.

[0009] The printing method described in the prior art document (Japanese Patent Publication No. 2018-35270) has the problem that the printed material has poor beading resistance, gloss, and adhesion because the primer contains acids such as malonic acid and phosphoric acid as flocculants, but does not contain polyvalent metal salts. Furthermore, the aforementioned printing method has the problem that the printed material has poor scratch resistance because the glass transition temperature of the resin particles contained in the color ink is not below 0°C. Furthermore, the aforementioned printing method has the problem that the drying properties and abrasion resistance of the printed material are poor because the color ink does not contain the organic solvent represented by the general formula (1). Furthermore, the aforementioned printing method has the problem that the printed material dries poorly because the clear ink does not contain the organic solvent represented by the general formula (1). Furthermore, the aforementioned printing method has the problem that the printed material has poor scratch resistance because the glass transition temperature of the dried clear ink film is neither 50°C or higher nor below 0°C.

[0010] <Primer application process and primer application means> The primer application step involves applying a primer to a non-permeable substrate. By applying the primer, a primer layer can be formed. The primer application means is a means for applying a primer onto a non-permeable substrate.

[0011] <<Primer>> The primer preferably contains a cationic resin, a polyvalent metal salt, and a diethylene glycol alkyl ether-based organic solvent, and more preferably contains water, and may further contain other components as needed. In the present invention, "primer" may be referred to as "treatment solution," "pretreatment solution," "composition solution," "reaction solution," or "liquid composition."

[0012] -Cationic resin- The cationic resin is a resin having a cationic substituent. By including the cationic resin in the primer, a recording material with excellent image gloss and scratch resistance can be obtained.

[0013] The cationic resin is not particularly limited and can be appropriately selected depending on the purpose. Examples include urethane-based cationic resins, olefin-based cationic resins, and allylamine-based cationic resins. These may be used individually or in combination of two or more. Among these, urethane-based cationic resins are preferred.

[0014] The cationic resin may be synthesized as appropriate, or a commercially available product may be used. Examples of commercially available cationic resins include non-yellowing isocyanate ester resins such as Superflex 600, Superflex 610, Superflex 620, Superflex 630, Superflex 640, and Superflex 650 (all manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Hydran CP-7010, Hydran CP-7020, Hydran CP-7030, Hydran CP-7040, Hydran CP-7050, Hydran CP-7060, and Hydran CP-7610 (all manufactured by DIC Corporation), and Aqueous Urethane Dispersion WBR-2120C and Aqueous Urethane Dispersion WBR-2122C (both manufactured by Taisei Fine Chemical Co., Ltd.).

[0015] There are no particular restrictions on the state of the cationic resin, and it can be appropriately selected depending on the purpose, but it is preferable that it be in the state of a resin emulsion dispersed with water as the dispersion medium. This allows a primer to be obtained by mixing it with materials such as organic solvents. Furthermore, considering the ease of preparing an aqueous ink by compounding it with an organic solvent and water, and the need to disperse it as uniformly as possible in the primer, a resin emulsion state in which the resin particles are stably dispersed with water as the dispersion medium is preferable.

[0016] The cationic resin is easily dissolved in an organic solvent added to the primer to form a film, and the film formation of resin particles is accelerated as the organic solvent and water evaporate. When dispersing the cationic resin in water as a dispersion medium, examples of the resin particles include forced emulsification type resin particles using a dispersant, and self-emulsifying type resin particles having cationic groups in their molecular structure. Among these, self-emulsifying type resin particles having cationic groups in their molecular structure are preferred from the standpoint of increasing the strength of the recorded material.

[0017] There are no particular restrictions on the content of the cationic resin, and it can be appropriately selected depending on the purpose. However, in the primer, it is preferably 1.5% by mass or more and 15.5% by mass or less, and more preferably 2.0% by mass or more and 15.0% by mass or less, as this yields a recording with excellent image gloss and adhesion.

[0018] -Polyvalent metal salts- The aforementioned polyvalent metal salt is a polyvalent metal salt in which a divalent or higher metal ion is bonded to an acid ion, and is used as a flocculant. Since the aforementioned polyvalent metal salt reacts with the components in the color ink described later to suppress image blurring, etc., a high-quality image can be formed. The polyvalent metal salt is preferably a compound of a carboxylic acid or nitrate ion, and is preferably soluble in water.

[0019] The acid ion is not particularly limited and can be appropriately selected according to the purpose. Examples thereof include saturated aliphatic monocarboxylic acid ions and nitrate ions. The saturated aliphatic monocarboxylic acid ion is not particularly limited and can be appropriately selected according to the purpose. Examples thereof include formate ion, acetate ion, propionate ion, butyrate ion, isobutyrate ion, valerate ion, isovalerate ion, pivalate ion, hexanoate ion, and the like. As the acid ion, acetate ion and nitrate ion are preferable, and acetate ion is more preferable in terms of obtaining excellent image glossiness and adhesion.

[0020] The metal ion is not particularly limited and can be appropriately selected according to the purpose. Examples thereof include divalent metal ions such as calcium ion (Ca 2+ ), copper ion (Cu 2+ ), nickel ion (Ni 2+ ), magnesium ion (Mg 2+ ), zinc ion (Zn 2+ ), barium ion (Ba 2+ ), etc., and trivalent metal ions such as aluminum ion (Al 3+ ), iron ion (Fe 3+ ), chromium ion (Cr 3+ ), etc. Among these, magnesium ion (Mg 2+ ) is preferable.

[0021] The polyvalent metal salt is not particularly limited and can be appropriately selected according to the purpose. Examples thereof include calcium carbonate, calcium nitrate, calcium chloride, calcium acetate, calcium sulfate, magnesium chloride, magnesium acetate, magnesium nitrate, magnesium sulfate, barium sulfate, zinc sulfide, zinc carbonate, aluminum chloride, aluminum nitrate, magnesium acetate, magnesium nitrate, or anhydrides or hydrates thereof. Among these, magnesium acetate and magnesium nitrate are preferable, and magnesium acetate is more preferable in terms of obtaining a recording material having excellent image glossiness and adhesion.

[0022] There are no particular restrictions on the content of the polyvalent metal salt, and it can be appropriately selected depending on the purpose, but it is preferably 0.25% by mass or more and 10.0% by mass or less, and more preferably 0.5% by mass or more and 3% by mass or less. When the polyvalent metal salt content is between 0.25% by mass and 10% by mass, the adhesion, gloss, and ethanol resistance of the resulting image are improved.

[0023] -Organic Solvents- The aforementioned organic solvent includes diethylene glycol alkyl ether-based organic solvents. Examples of the diethylene glycol alkyl ether-based organic solvents include diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monopentyl ether, diethylene glycol monohexyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol ethyl methyl ether, diethylene glycol isopropyl methyl ether, and diethylene glycol butyl methyl ether. These may be used individually or in combination of two or more. Among these, diethylene glycol diethyl ether is preferred because it yields recordings with excellent image gloss and adhesion.

[0024] There are no particular restrictions on the content of the diethylene glycol alkyl ether-based organic solvent, and it can be appropriately selected depending on the purpose, but it is preferably 4.5% by mass or more and 30.5% by mass or less, more preferably 5.0% by mass or more and 30.0% by mass or less, and particularly preferably 15.0% by mass or more and 30.0% by mass or less.

[0025] -water- There are no particular restrictions on the water mentioned above, and it can be appropriately selected depending on the purpose. Examples include pure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, and distilled water, as well as ultrapure water. These may be used individually or in combination of two or more types. There are no particular restrictions on the water content, and it can be appropriately selected depending on the purpose. However, from the viewpoint of primer drying properties and discharge reliability, it is preferable that the water content be 10% to 80% by mass relative to the primer, and more preferably 30% to 60% by mass.

[0026] -Other ingredients- The other components that can be contained in the primer are not particularly limited and can be appropriately selected depending on the purpose. Examples include surfactants, preservatives and fungicides, and organic solvents other than the diethylene glycol alkyl ether-based organic solvents.

[0027] The aforementioned surfactant is not particularly limited and can be appropriately selected depending on the purpose. Examples include polysiloxane-based surfactants having hydrophilic groups or hydrophilic polymer chains in the side chains or terminals of a compound having a polysiloxane structure (silicone-based compound). Note that the term "polysiloxane-based surfactant" means that it is sufficient to have a polysiloxane structure in its structure, and includes polysiloxane-based surfactants. Examples of compounds having the aforementioned polysiloxane structure include polydimethylsiloxane.

[0028] There are no particular restrictions on the hydrophilic group or the hydrophilic polymer chain, and they can be appropriately selected depending on the purpose. For example, polyether groups (polyethylene oxide, polypropylene oxide, or copolymers thereof), polyglycerin (C3H6O(CH2CH(OH)CH2O) n -H etc.), pyrrolidone, betaine (C3H6N + (C2H4)2-CH2COO- etc.), sulfate (C3H6O(C2H4O) n -SO3Na etc.), phosphate (C3H6O(C2H4O) n -P(=O)OHONa etc.), quaternary salt (C3H6N + (C2H4)3Cl - Examples include the following. However, in the above chemical formula, n represents an integer of 1 or more. Among these, the polyether group is preferred. Furthermore, vinyl copolymers having side chains of silicone compounds such as polydimethylsiloxane, obtained by copolymerizing polydimethylsiloxane having polymerizable vinyl groups at its termini with other copolymerizable monomers (preferably hydrophilic monomers such as (meth)acrylic acid or its salts are used for at least a portion of the monomers), are also preferred. Among these, compounds having a polysiloxane structure and a hydrophilic polymer chain are preferred, more preferably containing a polyether group as the hydrophilic polymer chain, and particularly preferred that the polysiloxane-based surfactant is a nonionic surfactant having methylpolysiloxane as the hydrophobic group and a polyoxyethylene structure as the hydrophilic group.

[0029] The polysiloxane-based surfactant is not particularly limited and can be appropriately selected depending on the purpose. Examples include polyether-modified silicones and polyoxyalkylene group-containing silicone compounds.

[0030] As the polysiloxane-based surfactant, commercially available products can be used. Examples of such commercially available products include Silface SAG503A, Silface SAG005, Silface SAG008 (all manufactured by Nisshin Chemical Industry Co., Ltd.), FZ2110, FZ2166, SH-3772M, L7001, SH-3773M (all manufactured by Toray Dow Ltd.), KF-353, KF-945, KF-6017 (all manufactured by Shin-Etsu Chemical Co., Ltd.), and FormBan MS-575 (manufactured by Ultra Addives Inc.).

[0031] There are no particular restrictions on the content of the surfactant, and it can be appropriately selected depending on the purpose, but it is preferably 0.1% by mass or more and 4.0% by mass or less relative to the primer, and more preferably 1.0% by mass or more and 2.0% by mass or less. When the content is 0.1% by mass or more and 4.0% by mass or less, when used in combination with a diethylene glycol alkyl ether-based organic solvent, the fixation of ink to non-permeable recording media can be improved, and further, image quality such as image gloss can be improved.

[0032] There are no particular restrictions on the aforementioned preservative and antifungal agent, and it can be appropriately selected depending on the purpose. For example, 1,2-benzisothiazolin-3-one is one such example.

[0033] Commercially available preservatives and fungicides can be used, and examples of such commercial products include Proxel Lv (manufactured by Abyssia).

[0034] There are no particular restrictions on the content of the aforementioned preservative and antifungal agent, and it can be appropriately selected depending on the purpose, but it is preferable that the primer contains 0.005% by mass or more and 0.05% by mass or less.

[0035] There are no particular restrictions on organic solvents other than the diethylene glycol alkyl ether-based organic solvents mentioned above, and they can be appropriately selected depending on the purpose. Examples include polyhydric alcohols, ethers such as polyhydric alcohol alkyl ethers and polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, sulfur-containing compounds, propylene carbonate, and ethylene carbonate.

[0036] Examples of the aforementioned polyhydric alcohols include ethylene glycol, diethylene glycol, propylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 3-methyl-1,3-butanediol, 3-methoxy-3-methyl-1-butanol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,2-pentanediol, 1,3-pentanediol Examples include ol, 1,4-pentanediol, 2,4-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,3-hexanediol, 2,5-hexanediol, 1,5-hexanediol, glycerin, 1,2,6-hexanetriol, 2-ethyl-1,3-hexanediol, ethyl-1,2,4-butanetriol, 1,2,3-butanetriol, 2,2,4-trimethyl-1,3-pentanediol, petriol, and others.

[0037] Examples of the polyhydric alcohol alkyl ethers include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether.

[0038] Examples of the aforementioned polyhydric alcohol aryl ethers include ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.

[0039] Examples of the nitrogen-containing heterocyclic compounds include 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, ε-caprolactam, and γ-butyrolactone.

[0040] Examples of the aforementioned amides include formamide, N-methylformamide, N,N-dimethylformamide, 3-methoxy-N,N-dimethylpropionamide, and 3-butoxy-N,N-dimethylpropionamide.

[0041] Examples of the aforementioned amines include monoethanolamine, diethanolamine, and triethylamine.

[0042] Examples of the aforementioned sulfur-containing compounds include dimethyl sulfoxide, sulfolane, and thiodiethanol.

[0043] There are no particular restrictions on the content of organic solvents other than the diethylene glycol alkyl ether-based organic solvents, and they can be appropriately selected depending on the purpose. However, from the viewpoint of ink drying properties and ejection reliability, it is preferable that the content be 10% by mass or more and 60% by mass or less relative to the primer, and more preferably 20% by mass or more and 60% by mass or less.

[0044] There are no particular restrictions on the method for preparing the primer, and it can be appropriately selected depending on the purpose. For example, it can be prepared by mixing and stirring the cationic resin, the flocculated salt, the organic solvent, the water, and any other components as needed, and filtering the mixture through a 10 μm filter (Minisart, manufactured by Sartorius).

[0045] There are no particular restrictions on the method of applying the primer in the primer application process, and it can be appropriately selected according to the purpose. Examples include the inkjet method, blade coating method, gravure coating method, gravure offset coating method, bar coating method, roll coating method, knife coating method, air knife coating method, comma coating method, U-comma coating method, AKKU coating method, smoothing coating method, microgravure coating method, reverse roll coating method, 4-roll coating method, 5-roll coating method, dip coating method, curtain coating method, slide coating method, and die coating method. Among these, the inkjet method is preferred.

[0046] There are no particular restrictions on the amount of primer applied in the primer application process, and it can be appropriately selected according to the purpose, but 1.0 g / m 2 More than 15.0g / m 2 The following is preferable: The amount applied is 1.0 g / m². 2 If the amount is greater than this, the colorants contained in the color ink will be more likely to aggregate, and the amount applied will be 15.0 g / m². 2 The following factors can help suppress primer beading.

[0047] <Color ink application process and color ink application means> The color ink application step involves applying color ink to the region to which the primer has been applied. By applying the color ink, a color ink layer can be formed. The color ink application means is a means for applying color ink to the area to which the primer has been applied.

[0048] <<Color Ink>> The aforementioned color ink contains resin particles having a glass transition temperature (Tg) of less than 0°C, and an organic solvent represented by the following general formula (1), preferably containing water, and may further contain other components as needed. [ka] (However, in the above general formula (1), R 1 (This represents an alkyl group with 1 to 4 carbon atoms).

[0049] -Resin particles- The glass transition temperature Tg (°C) of the resin particles contained in the color ink is less than 0°C, and preferably -4°C or lower. When the glass transition temperature of the resin particles is less than 0°C, the adhesion between the image formed by the color ink and the recording medium is improved, and a recording material with excellent scratch resistance can be obtained.

[0050] There are no particular limitations on the method for measuring the glass transition temperature of the resin particles contained in the aforementioned color ink, and a suitable method can be selected depending on the purpose. For example, it can be measured using a differential scanning calorimeter (DSC).

[0051] The resin particles contained in the color ink are not particularly limited as long as their glass transition temperature is less than 0°C, and can be appropriately selected according to the purpose. Examples include polyurethane resin, polyester resin, acrylic resin, vinyl acetate resin, styrene resin, butadiene resin, styrene-butadiene resin, vinyl chloride resin, acrylic-styrene resin, and acrylic-silicone resin. These may be used individually or in combination of two or more types.

[0052] There are no particular restrictions on the content of the resin particles having a glass transition temperature of 0°C or lower, and they can be appropriately selected depending on the purpose, but it is preferable that the content is 0.5% by mass or more and 20.0% by mass or less relative to the color ink.

[0053] The resin particles contained in the aforementioned color ink may be added to the ink in the form of a resin emulsion, in which the resin particles are dispersed in water as a dispersion medium during the ink manufacturing process. The aforementioned resin particles may be synthesized as appropriate, or commercially available products may be used.

[0054] There are no particular restrictions on the volume-average particle size of the resin particles contained in the color ink, and it can be appropriately selected depending on the purpose, but it is preferably 5 nm to 50 nm, and more preferably 10 nm to 40 nm. When the volume-average particle size of the resin particles is 50 nm or less, a uniform color ink layer can be formed. For example, the volume-average particle size of the aforementioned resin particles can be measured using a particle size analyzer (Nanotrac Wave II, manufactured by Microtrac-Bel).

[0055] -Organic Solvents- The organic solvent contained in the color ink is an organic solvent represented by the following general formula (1). By containing the organic solvent represented by the following general formula (1) in the color ink, the drying properties of the color ink are improved and the occurrence of beading in the color ink can be suppressed.

[0056] [ka] (However, in the above general formula (1), R 1 (This represents an alkyl group with 1 to 4 carbon atoms).

[0057] In the organic solvent represented by the general formula (1) above, R 1 Examples of alkyl groups include methyl, ethyl, propyl, and n-butyl groups. Among these, the methyl group is preferred. Examples of organic solvents represented by the general formula (1) include 3-methoxy-N,N-dimethylpropionamide, 3-ethoxy-N,N-dimethylpropionamide, 3-propyloxy-N,N-dimethylpropionamide, and 3-butoxy-N,N-dimethylpropionamide. Among these, 3-methoxy-N,N-dimethylpropionamide is preferred. The organic solvent represented by the general formula (1) may be one that has been appropriately synthesized or a commercially available product may be used. For example, the commercially available product is R in the general formula (1). 1 Equamid M100 (manufactured by Idemitsu Kosan Co., Ltd.) in which R is a methyl group, and in the above general formula (1) 1 Examples include Equamid B100 (manufactured by Idemitsu Kosan Co., Ltd.), which has an n-butyl group.

[0058] There are no particular restrictions on the content of the organic solvent represented by the general formula (1) and it can be appropriately selected depending on the purpose, but it is preferably 3% by mass or more and 5% by mass or less relative to the color ink, and more preferably 4% by mass or more and 5% by mass or less. When the content is 3% by mass or more and 5% by mass or less, the drying properties of the color ink are improved and a record with excellent scratch resistance can be obtained.

[0059] -water- There are no particular restrictions on the water mentioned above, and it can be appropriately selected depending on the purpose. Examples include pure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, and distilled water, as well as ultrapure water. These may be used individually or in combination of two or more types. There are no particular restrictions on the water content, and it can be appropriately selected depending on the purpose. However, from the viewpoint of drying properties and discharge reliability of the color ink, 10% by mass or more and 90% by mass or less is preferred, and 20% by mass or more and 60% by mass or less is more preferred.

[0060] -Other ingredients- The other components that can be contained in the color ink are not particularly limited and can be appropriately selected depending on the purpose. Examples include resin particles other than those having a glass transition temperature of less than 0°C, organic solvents other than those represented by general formula (1), colorants, surfactants, preservatives, and fungicides.

[0061] There are no particular restrictions on the resin particles other than those with a glass transition temperature of less than 0°C, and they can be appropriately selected according to the purpose. For example, they can be the same as the resin particles contained in the primer.

[0062] Other organic solvents besides the one represented by the general formula (1) are not particularly limited and can be appropriately selected depending on the purpose. Examples include polyhydric alcohols, ethers such as polyhydric alcohol alkyl ethers and polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, sulfur-containing compounds, propylene carbonate, ethylene carbonate, and ethyl acetate.

[0063] Examples of the aforementioned polyhydric alcohols include ethylene glycol, diethylene glycol, propylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 3-methyl-1,3-butanediol, 3-methoxy-3-methyl-1-butanol, triethylene glycol, 2-ethyl-1,3-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, polyethylene glycol, polypropylene glycol, Examples include 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 2,4-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,3-hexanediol, 2,5-hexanediol, 1,5-hexanediol, glycerin, 1,2,6-hexanetriol, 2-ethyl-1,3-hexanediol, ethyl-1,2,4-butanetriol, 1,2,3-butanetriol, 2,2,4-trimethyl-1,3-pentanediol, and petriol.

[0064] Examples of the aforementioned polyhydric alcohol alkyl ethers include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether.

[0065] Examples of the aforementioned polyhydric alcohol aryl ethers include ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.

[0066] Examples of the nitrogen-containing heterocyclic compounds include 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, ε-caprolactam, and γ-butyrolactone.

[0067] Examples of the aforementioned amides include formamide, N-methylformamide, N,N-dimethylformamide, 3-methoxy-N,N-dimethylpropionamide, and 3-butoxy-N,N-dimethylpropionamide.

[0068] Examples of the aforementioned amines include monoethanolamine, diethanolamine, and triethylamine.

[0069] Examples of the aforementioned sulfur-containing compounds include dimethyl sulfoxide, sulfolane, and thiodiethanol.

[0070] There are no particular restrictions on the boiling point of organic solvents other than the organic solvent represented by the general formula (1) above, and they can be appropriately selected depending on the purpose. However, a boiling point of 250°C or lower is preferred because it not only functions as a wetting agent but also provides good drying properties.

[0071] There are no particular restrictions on the content of organic solvents other than the organic solvent represented by the general formula (1) above, and they can be appropriately selected depending on the purpose. However, from the viewpoint of the drying properties and discharge reliability of the color ink, it is preferable that the content is 10% by mass or more and 60% by mass or less relative to the primer, and more preferably 20% by mass or more and 60% by mass or less.

[0072] The aforementioned coloring agent is not particularly limited as long as it exhibits a color, and can be appropriately selected according to the purpose. Examples include dyes and pigments. These may be used individually or in combination of two or more. Among these, pigments are preferred. Examples of the aforementioned pigments include inorganic pigments and organic pigments.

[0073] The inorganic pigments mentioned above are not particularly limited and can be appropriately selected depending on the purpose. Examples include titanium dioxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chromium yellow, carbon black, hollow resin particles, and inorganic hollow particles. These may be used individually or in combination of two or more. As the carbon black mentioned above, carbon black manufactured by known methods such as the contact method, furnace method, or thermal method may be used.

[0074] There are no particular restrictions on the organic pigments mentioned above, and they can be appropriately selected according to the purpose. For example, for black pigments, examples include carbon blacks (CI Pigment Black 7) such as furnace black, lamp black, acetylene black, and channel black, as well as copper, iron (CI Pigment Black 11), and aniline black (CI Pigment Black 1). For color pigments, examples include CI Pigment Yellow 1, 3, 12, 13, 14, 17, 24, 34, 35, 37, 42 (yellow iron oxide), 53, 55, 74, 81, 83, 95, 97, 98, 100, 101, 104, 108, 109, 110, 117, 120, 138, 150, 153, 155; CI Pigment Orange Ji 5, 13, 16, 17, 36, 43, 51; CI Pigment Red 1, 2, 3, 5, 17, 22, 23, 31, 38, 48:2, 48:2 (Permanent Red 2B(Ca)), 48:3, 48:4, 49:1, 52:2, 53:1, 57:1 (Brilliant Carmine 6B), 60:1, 63:1, 63:2, 64: Examples include 1, 81, 83, 88, 101 (red iron oxide), 104, 105, 106, 108 (cadmium red), 112, 114, 122 (quinacridone magenta), 123, 146, 149, 166, 168, 170, 172, 177, 178, 179, 185, 190, 193, 209, 219; CI Pigment Violet 1 (rhodamine lake), 3, 5:1, 16, 19, 23, 38; CI Pigment Blue 1, 2, 15 (phthalocyanine blue), 15:1, 15:2, 15:3 (phthalocyanine blue), 16, 17:1, 56, 60, 63; CI Pigment Green 1, 4, 7, 8, 10, 17, 18, 36, etc. These may be used individually or in combination of two or more types.

[0075] There are no particular restrictions on the aforementioned dyes, and they can be appropriately selected according to the purpose. For example, CI Acid Yellow 17, 23, 42, 44, 79, 142; CI Acid Red 52, 80, 82, 249, 254, 289; CI Acid Blue 9, 45, 249; CI Acid Black 1, 2, 24, 94; CI Food Black 1, 2; CI Direct Yellow 1, 12, 24, 33, 50, 55, 58, 8 Examples include 6, 132, 142, 144, 173; CI Direct Red 1, 4, 9, 80, 81, 225, 227; CI Direct Blue 1, 2, 15, 71, 86, 87, 98, 165, 199, 202; CI Direct Black 19, 38, 51, 71, 154, 168, 171, 195; CI Reactive Red 14, 32, 55, 79, 249; CI Reactive Black 3, 4, 35, etc. These may be used individually or in combination of two or more types.

[0076] There are no particular restrictions on the content of the coloring agent, and it can be appropriately selected depending on the purpose. However, from the standpoint of improving image density and obtaining good fixation and discharge stability, it is preferable that the content be between 0.1% by mass and 15% by mass, and more preferably between 1% by mass and 10% by mass.

[0077] Methods for dispersing the aforementioned pigment to obtain ink include introducing hydrophilic functional groups into the pigment to make it a self-dispersible pigment, coating the surface of the pigment with a resin and dispersing it, and using a dispersant to disperse it. One method for introducing hydrophilic functional groups into the aforementioned pigment to create a self-dispersible pigment is to add functional groups such as sulfo groups or carboxyl groups to a pigment such as carbon, thereby making it dispersible in water. One method for coating and dispersing the surface of the aforementioned pigment with a resin is to encapsulate the pigment in microcapsules so that it can be dispersed in water. The pigment obtained by this method can be referred to as a resin-coated pigment. In this case, it is not necessary for all the pigments contained in the ink to be coated with resin, and uncoated pigments or partially coated pigments may be dispersed in the ink as long as the effects of the present invention are not impaired. Methods for dispersion using the aforementioned dispersant include using known low-molecular-weight dispersants such as surfactants, or high-molecular-weight dispersants. Examples of the dispersant include anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants, which can be appropriately selected depending on the pigment. Examples include RT-100 (nonionic surfactant, manufactured by Takemoto Oil & Fat Co., Ltd.) and sodium naphthalene sulfonate formalin condensate. These may be used individually or in combination of two or more.

[0078] The aforementioned pigment dispersion can be mixed with materials such as water and organic solvents to obtain ink. Alternatively, ink can be manufactured by mixing a pigment with other materials such as water and organic solvents to create a pigment dispersion. The aforementioned pigment dispersion is obtained by dispersing water, pigment, pigment dispersant, and other components as needed, and adjusting the particle size. Dispersion is preferably carried out using a disperser. There are no particular restrictions on the volume-average particle size of the pigment in the aforementioned pigment dispersion, and it can be appropriately selected according to the purpose. However, for non-white pigments, it is preferable that the particle size be between 30 nm and 110 nm, as this improves the dispersion stability of the pigment and enhances image quality such as ejection stability and image density. Furthermore, for hollow resin particles, it is preferable that the average volume particle size be between 200 nm and 1,000 nm, as this provides high dispersion stability and high whiteness. Furthermore, for inorganic hollow particles, it is preferable that the average volume particle size be between 10 nm and 200 nm, as this provides high dispersion stability and high whiteness. There are no particular restrictions on the pigment content in the pigment dispersion, and it can be appropriately selected depending on the purpose. However, from the standpoint of obtaining good discharge stability and increasing image density, a content of 0.1% to 50% by mass is preferred, and a content of 0.1% to 30% by mass is more preferred. The pigment dispersion is preferably filtered to remove coarse particles and degassed using a filter, centrifuge, or the like, if necessary.

[0079] The surfactant is not particularly limited and can be appropriately selected depending on the purpose. Examples include silicone-based surfactants, fluorine-based surfactants, amphoteric surfactants, nonionic surfactants, and anionic surfactants. These may be used individually or in combination of two or more.

[0080] The silicone-based surfactant is not particularly limited and can be appropriately selected depending on the purpose. Examples include side-chain modified polydimethylsiloxane, both-end modified polydimethylsiloxane, one-end modified polydimethylsiloxane, and both-end modified polydimethylsiloxane. Those having a polyoxyethylene group or a polyoxyethylene polyoxypropylene group as a modifying group are preferred because they exhibit good properties as an aqueous surfactant. Furthermore, as the silicone-based surfactant, a polyether-modified silicone-based surfactant can be used, for example, a compound in which a polyalkylene oxide structure is introduced into the Si side chain of dimethylsiloxane. The aforementioned silicone-based surfactant is preferably one that does not decompose even at high pH.

[0081] Commercially available polyether-modified silicone surfactants can be used, such as KF-618, KF-642, KF-643, etc. (all manufactured by Shin-Etsu Chemical Co., Ltd.), EMALEX-SS-5602, SS-1906EX, etc. (all manufactured by Nippon Emulsion Co., Ltd.), FZ-2105, FZ-2118, FZ-2154, FZ-2161, FZ-2162, FZ-2163, FZ-2164, etc. (all manufactured by Toray Dow Corning Silicone Co., Ltd.), BYK-33, BYK-387, etc. (all manufactured by BIC Chemie Co., Ltd.), TSF4440, TSF4452, TSF4453, etc. (all manufactured by Toshiba Silicone Co., Ltd.).

[0082] There are no particular limitations on the fluorine-based surfactant, and it can be appropriately selected depending on the purpose. However, perfluoroalkyl sulfonic acid compounds, perfluoroalkyl carboxylic acid compounds, perfluoroalkyl phosphate ester compounds, perfluoroalkyl ethylene oxide adducts, and polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups in their side chains are preferred because they have low foaming properties. Examples of the perfluoroalkyl sulfonic acid compound include perfluoroalkyl sulfonic acid and perfluoroalkyl sulfonate salts. Examples of the perfluoroalkylcarboxylic acid compound include perfluoroalkylcarboxylic acids and perfluoroalkylcarboxylic acid salts. Examples of polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups in their side chains include sulfate ester salts of polyoxyalkylene ether polymers having perfluoroalkyl ether groups in their side chains, and salts of polyoxyalkylene ether polymers having perfluoroalkyl ether groups in their side chains. Examples of counterions for the salts in these fluorinated surfactants include Li, Na, K, NH4, NH3CH2CH2OH, NH2(CH2CH2OH)2, and NH(CH2CH2OH)3.

[0083] The fluorine-based surfactant is not particularly limited and can be appropriately selected depending on the purpose, but compounds with 2 to 16 carbon atoms substituted with fluorine are preferred, and compounds with 4 to 16 carbon atoms substituted with fluorine are more preferred. Examples of the fluorine-based surfactants include perfluoroalkyl phosphate compounds, perfluoroalkyl ethylene oxide adducts, and polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups in their side chains. Among these, polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups in their side chains are preferred because they have low foaming properties.

[0084] Commercially available fluorine-based surfactants may be used. Examples of such commercially available surfactants include Surflon S-111, S-112, S-113, S-121, S-131, S-132, S-141, S-145, etc. (all manufactured by Asahi Glass Co., Ltd.), Flurad FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, FC-431, etc. (all manufactured by Sumitomo 3M Limited), Megafac F-470, F-1405, F-474, etc. (all manufactured by DIC Corporation), Zonyl TBS, FSP, FSA, FSN-100, FSN, FSO-100, FS Examples include O, FS-300, UR, Capstone FS-30, FS-31, FS-3100, FS-34, FS-35, etc. (all manufactured by Chemors), FT-110, FT-250, FT-251, FT-400S, FT-150, FT-400SW, etc. (all manufactured by Neos Corporation), Polyfox PF-136A, Polyfox PF-156A, Polyfox PF-151N, Polyfox PF-154, Polyfox PF-159, etc. (manufactured by Omnova), and Unidyne DSN-403N, etc. (manufactured by Daikin Industries, Ltd.). Among these, Chemors' FS-3100, FS-34, and FS-300, Neos Corporation's FT-110, FT-250, FT-251, FT-400S, FT-150, and FT-400SW, Omnova's Polyfox PF-151N, and Daikin Industries, Ltd.'s Unidyne DSN-403N are preferred because they offer excellent print quality, particularly in terms of color development, penetration into paper, wettability, and uniform dyeing.

[0085] The aforementioned amphoteric surfactant is not particularly limited and can be appropriately selected depending on the purpose. Examples include laurylaminopropionate, lauryldimethylbetaine, stearyldimethylbetaine, and lauryldihydroxyethylbetaine.

[0086] The nonionic surfactant is not particularly limited and can be appropriately selected depending on the purpose. Examples include polyoxyethylene alkylphenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene alkylamines, polyoxyethylene alkylamides, polyoxyethylene propylene block polymers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, and ethylene oxide adducts of acetylene alcohols.

[0087] The anionic surfactant is not particularly limited and can be appropriately selected depending on the purpose. Examples include polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, lauryl salt, and polyoxyethylene alkyl ether sulfate salts.

[0088] The surfactant may be one that has been synthesized as appropriate, or a commercially available product may be used. There are no particular restrictions on the commercially available product, and it can be appropriately selected according to the purpose. For example, it can be obtained from companies such as BIC Chemie Inc., Shin-Etsu Chemical Co., Ltd., Toray Dow Corning Silicone Co., Ltd., Nippon Emulsion Co., Ltd., and Kyoeisha Chemical Co., Ltd.

[0089] There are no particular restrictions on the content of the surfactant, and it can be appropriately selected depending on the purpose. However, in order to have excellent wettability and discharge stability and improve image quality, the content of the surfactant in the color ink is preferably 0.001% by mass or more and 5% by mass or less, and more preferably 0.05% by mass or more and 5% by mass or less.

[0090] There are no particular restrictions on the aforementioned preservative and antifungal agent; for example, 1,2-benzisothiazolin-3-one is one such example.

[0091] There are no particular restrictions on the physical properties of the aforementioned color ink, and they can be appropriately selected according to the purpose. For example, it is preferable that the viscosity, surface tension, pH, etc., are within the following ranges.

[0092] There are no particular restrictions on the viscosity of the color ink at 25°C, and it can be appropriately selected depending on the purpose. However, a viscosity of 5 mPa·s to 30 mPa·s is preferred, and a viscosity of 5 mPa·s to 25 mPa·s is more preferred, as it improves print density and character quality and provides good ejection performance. As a method for measuring viscosity, for example, a rotational viscometer (RE-80L manufactured by Toki Sangyo Co., Ltd.) can be used, and the measurement can be performed at 25°C with a standard cone rotor (1°34'×R24), a sample volume of 1.2 mL, a rotation speed of 50 rpm, and a measurement time of 3 minutes.

[0093] There are no particular restrictions on the surface tension of the color ink, and it can be appropriately selected depending on the purpose. However, a surface tension of 35 mN / m or less at 25°C is preferred, and 32 mN / m or less is more preferred, in order to allow the ink to level nicely on the recording medium and shorten the ink drying time.

[0094] There are no particular restrictions on the pH of the color ink, and it can be appropriately selected depending on the purpose. However, from the viewpoint of preventing corrosion of metal components that come into contact with the liquid, a pH of 7 to 12 is preferred, and a pH of 8 to 11 is more preferred.

[0095] There are no particular restrictions on the method of applying color ink in the color ink application process, and it can be appropriately selected according to the purpose. Examples include the inkjet method, blade coating method, gravure coating method, gravure offset coating method, bar coating method, roll coating method, knife coating method, air knife coating method, comma coating method, U-comma coating method, AKKU coating method, smoothing coating method, microgravure coating method, reverse roll coating method, 4-roll coating method, 5-roll coating method, dip coating method, curtain coating method, slide coating method, and die coating method. Among these, the inkjet method is preferred.

[0096] There are no particular restrictions on the average thickness of the color ink layer in the color ink application step, and it can be appropriately selected depending on the purpose, but it is preferably 1 μm or more and 10 μm or less. If the average thickness is 1 μm or more, a recording with excellent image quality can be obtained, and if the average thickness is 10 μm or less, drying performance is improved, so blocking of the recording can be suppressed.

[0097] There are no particular restrictions on the amount of color ink applied in the color ink application process, and it can be appropriately selected according to the purpose, but 3.0 g / m² is a reasonable amount. 2 More than 35.0g / m 2 The following is preferable: The amount applied is 3.0 g / m². 2 If the amount is greater than or equal to 35.0 g / m², the image quality will improve, and the amount added will be 35.0 g / m². 2 The following conditions can suppress beading of colored inks.

[0098] <Clear ink application process and clear ink application means> The clear ink application step involves applying the clear ink to at least the area to which the color ink has been applied. By applying the clear ink, an overcoat layer can be formed. The means for applying the clear ink is a means for applying it to at least the area to which the color ink has been applied.

[0099] <<Clear Ink>> The aforementioned clear ink is a colorless, transparent ink that contains virtually no colorants. The clear ink contains resin particles and an organic solvent represented by the following general formula (1), preferably contains water, and may contain other components as needed. The clear ink preferably has a glass transition temperature (Tg) of 50°C or higher and below 0°C when the dried film is between 50°C and below 100°C, and between -50°C and below 0°C. When the glass transition temperature is between 50°C or higher and below 0°C, a record with excellent scratch resistance can be obtained.

[0100] [ka] (However, in the above general formula (1), R 1 (This represents an alkyl group with 1 to 4 carbon atoms).

[0101] There are no particular restrictions on the method for measuring the glass transition temperature of the dried film of the clear ink, and a suitable method can be selected depending on the purpose. For example, it can be measured using a differential scanning calorimeter (TA-60WS and DSC-60, manufactured by Shimadzu Corporation). Specifically, it can be measured by the following method. First, 4g of clear ink is evenly spread in a 50mm diameter tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) petri dish. After drying at 50°C for one week, 5.0mg of the resulting dried film is placed in an aluminum sample container. The sample container is then placed on a holder unit and set in an electric furnace. Next, under a nitrogen atmosphere, the temperature is raised from 0°C to 150°C at a rate of 10°C / min, then cooled from 150°C to -80°C at a rate of 5°C / min, and finally raised again to 150°C at a rate of 10°C / min to measure the DSC curve. From the obtained DSC curve, the glass transition temperature (Tg) is determined by analyzing the inflection point during the second heating cycle using the midpoint method with the analysis program in the DSC-60 system.

[0102] Clear inks described in prior art documents sometimes failed to provide sufficient abrasion resistance because the volume-average particle size of the resin particles and the glass transition temperature of the dried clear ink film did not meet the requirements of being 50°C or higher and less than 0°C. In contrast, the clear ink of the present invention is a clear ink comprising resin particles with a volume-average particle size of 50 nm or less and an organic solvent represented by the general formula (1), wherein the dried clear ink film has a glass transition temperature (Tg) of 50°C or higher and less than 0°C, thereby forming a dried film with strong abrasion resistance and excellent drying properties.

[0103] -Resin particles- The resin particles contained in the clear ink are resin particles with a volume average particle size of 50 nm or less, preferably between 5 nm and 40 nm, and more preferably between 10 nm and 40 nm. When the volume average particle size is 50 nm or less, a uniform overcoat layer can be formed, and a record with excellent scratch resistance can be obtained. There are no particular restrictions on the method for measuring the volume-average particle size, and it can be appropriately selected depending on the purpose. For example, it can be measured using a particle size analyzer (Nanotrac Wave II, manufactured by Microtrac-Bel).

[0104] When manufacturing the clear ink, it is preferable to add the resin particles made of the above resin, or the resin particles may be added to the ink in the form of a resin emulsion dispersed in water as a dispersion medium. The resin particles may be synthesized as appropriate, or commercially available products may be used. These resin particles may be used individually, or two or more types of resin particles may be used in combination.

[0105] Preferably, the clear ink contains at least two types of resin particles: resin particle A and resin particle B.

[0106] There are no particular restrictions on the glass transition temperature of the resin particles A, and it can be appropriately selected depending on the purpose, but it is preferably 50°C or higher, and more preferably 50°C or higher and less than 100°C. When the glass transition temperature of the resin particles A is 50°C or higher, the clear ink dried film becomes tougher and its abrasion resistance improves. Furthermore, polyurethane resin particles are preferred as the resin particles A.

[0107] There are no particular restrictions on the glass transition temperature of the resin particles B, and it can be appropriately selected depending on the purpose, but it is preferably less than 0°C, and more preferably between -50°C and 0°C. When the glass transition temperature of the resin particles B is less than 0°C, the adhesion between the clear ink and the substrate is improved, and the abrasion resistance of the dried film of the clear ink (hereinafter sometimes referred to as the "overcoat layer") is improved.

[0108] The mass M of the resin particle A in the resin particle contained in the clear ink. A and the mass M of the resin particles B B The mass ratio M A :M B There are no particular restrictions on this, and it can be selected as appropriate depending on the purpose, but 98:2 to 80:20 is preferred. This makes it possible to obtain a recording material with excellent abrasion resistance and adhesion.

[0109] The resin particles contained in the clear ink are not particularly limited as long as they have a volume-average particle size of 50 nm or less, and can be appropriately selected according to the purpose. Examples include polyurethane resin, polyester resin, acrylic resin, vinyl acetate resin, styrene resin, butadiene resin, styrene-butadiene resin, vinyl chloride resin, acrylic-styrene resin, and acrylic-silicone resin.

[0110] By using the aforementioned polyurethane resin as the resin particles, when an overcoat layer is formed using clear ink, the dried film itself becomes tougher, and problems such as partial peeling of the dried film due to internal rupture or changes in the surface condition of the dried film causing changes in the color of the friction area can be suppressed.

[0111] Examples of the polyurethane resin include polyether-based polyurethane resins, polycarbonate-based polyurethane resins, and polyester-based polyurethane resins.

[0112] There are no particular restrictions on the polyurethane resin, and it can be appropriately selected depending on the purpose. For example, a polyurethane resin obtained by reacting a polyol with a polyisocyanate can be used.

[0113] Examples of the aforementioned polyols include polyether polyols, polycarbonate polyols, and polyester polyols. These may be used individually or in combination of two or more.

[0114] Examples of the polyether polyol include those obtained by addition polymerization of alkylene oxide using at least one compound having two or more active hydrogen atoms as a starting material.

[0115] Examples of compounds having two or more active hydrogen atoms include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, trimethylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, glycerin, trimethylolethane, and trimethylolpropane. These may be used individually or in combination of two or more.

[0116] Examples of the alkylene oxides include ethylene oxide, propylene oxide, butylene oxide, styrene oxide, epichlorohydrin, and tetrahydrofuran. These may be used individually or in combination of two or more.

[0117] There are no particular restrictions on the polyether polyol, and it can be appropriately selected depending on the purpose, but polyoxytetramethylene glycol and polyoxypropylene glycol are preferred because they can provide excellent abrasion resistance. These may be used individually or in combination of two or more.

[0118] Furthermore, examples of polycarbonate polyols that can be used in the production of the polyurethane resin include those obtained by reacting a carbonate ester with a polyol, and those obtained by reacting phosgene with bisphenol A, etc. These may be used individually or in combination of two or more.

[0119] Examples of the aforementioned carbonate esters include methyl carbonate, dimethyl carbonate, ethyl carbonate, diethyl carbonate, cyclocarbonate, and diphenyl carbonate. These may be used individually or in combination of two or more.

[0120] Examples of the polyols include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,5-hexanediol, 2,5-hexanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1, Examples include relatively low molecular weight dihydroxy compounds such as 11-undecanediol, 1,12-dodecanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, hydroquinone, resorcinol, bisphenol-A, bisphenol-F, and 4,4'-biphenol; polyether polyols such as polyethylene glycol, polypropylene glycol, and polyoxytetramethylene glycol; and polyester polyols such as polyhexamethylene adipate, polyhexamethylene succinate, and polycaprolactone. These may be used individually or in combination of two or more.

[0121] Examples of the polyester polyols include those obtained by esterifying a low molecular weight polyol with a polycarboxylic acid, polyesters obtained by ring-opening polymerization of cyclic ester compounds such as ε-caprolactone, and copolymer polyesters thereof. These may be used individually or in combination of two or more.

[0122] Examples of the low molecular weight polyols include ethylene glycol and propylene glycol. These may be used individually or in combination of two or more. Examples of the polycarboxylic acid include succinic acid, adipic acid, sebacic acid, dodecanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, their anhydrides, or ester-forming derivatives. These may be used individually or in combination of two or more.

[0123] Examples of the polyisocyanates include aromatic diisocyanates such as phenylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, and naphthalene diisocyanate; and aliphatic or alicyclic diisocyanates such as hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, and 2,2,4-trimethylhexamethylene diisocyanate. These may be used individually or in combination of two or more. Among these, alicyclic diisocyanates are preferred from the viewpoint of weather resistance.

[0124] Furthermore, using at least one type of alicyclic diisocyanate makes it easier to obtain the desired dry film strength and abrasion resistance. Examples of the alicyclic diisocyanates include isophorone diisocyanate and dicyclohexylmethane diisocyanate. The content of the alicyclic diisocyanate is preferably 60% by mass or more relative to the total amount of the isocyanate compound.

[0125] [Method for manufacturing polyurethane resin] Polyurethane resin is not particularly limited and can be obtained by conventionally used manufacturing methods, such as the following: First, an isocyanate-terminated urethane prepolymer is produced by reacting the polyol and the polyisocyanate in an equivalent ratio that results in an excess of isocyanate groups, either in the absence of a solvent or in the presence of an organic solvent. Next, the anionic groups in the isocyanate-terminated urethane prepolymer are neutralized with a neutralizing agent as needed, then reacted with a chain extender, and finally, the organic solvent in the system is removed as needed to obtain the product.

[0126] Examples of organic solvents that can be used in the production of the polyurethane resin include ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran and dioxane; acetic acid esters such as ethyl acetate and butyl acetate; nitriles such as acetonitrile; and amides such as dimethylformamide, N-methylpyrrolidone, and N-ethylpyrrolidone. These may be used individually or in combination of two or more. Examples of the chain extender include polyamines and other active hydrogen group-containing compounds.

[0127] Examples of the polyamines include diamines such as ethylenediamine, 1,2-propanediamine, 1,6-hexamethylenediamine, piperazine, 2,5-dimethylpiperazine, isophoronediamine, 4,4'-dicyclohexylmethanediamine, and 1,4-cyclohexanediamine; polyamines such as diethylenetriamine, dipropylenetriamine, and triethylenetetramine; hydrazines such as hydrazine, N,N'-dimethylhydrazine, and 1,6-hexamethylenebishydrazine; and dihydrazides such as succinate dihydrazide, adipic acid dihydrazide, glutaric acid dihydrazide, sebacate dihydrazide, and isophthalic acid dihydrazide. These may be used individually or in combination of two or more.

[0128] Examples of the aforementioned other active hydrogen group-containing compounds include glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, hexamethylene glycol, sucrose, methylene glycol, glycerin, and sorbitol; phenols such as bisphenol A, 4,4'-dihydroxydiphenyl, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfone, hydrogenated bisphenol A, and hydroquinone; and water. These can be used individually or in combination of two or more, as long as the storage stability of the ink is not reduced.

[0129] As the polyurethane resin, polycarbonate-based polyurethane resin is preferred due to its high cohesiveness of carbonate groups, resulting in excellent water resistance, heat resistance, abrasion resistance, weather resistance, and image scratch resistance. When a polycarbonate-based polyurethane resin is used, an ink suitable for recording materials used in harsh environments such as outdoor applications can be obtained.

[0130] The polyurethane resin may be a commercially available product, such as U-Coat UX-485 (polycarbonate-based polyurethane resin), U-Coat UWS-145 (polyester-based polyurethane resin), Permarine UA-368T (polycarbonate-based polyurethane resin), and Permarine UA-200 (polyether-based polyurethane resin) (all manufactured by Sanyo Chemical Industries, Ltd.). These may be used individually or in combination of two or more types.

[0131] The total content of resin particles in the clear ink is preferably 10% by mass or more, and more preferably 10% by mass or more and 25% by mass or less from the viewpoint of excellent scratch resistance and clear ink discharge stability. When the total content of resin particles is 10% by mass or more, scratch resistance is further improved.

[0132] -Organic Solvents- The organic solvent contained in the clear ink is an organic solvent represented by the following general formula (1). Because the clear ink contains the organic solvent represented by the following general formula (1), the drying properties of the clear ink are improved, and blocking can be suppressed even when a large amount of clear ink is applied.

[0133] [ka] In the organic solvent represented by the general formula (1) above, R 1 Examples of such groups include methyl, ethyl, propyl, and n-butyl groups. Among these, the methyl group is preferred. Examples of organic solvents represented by the general formula (1) include 3-methoxy-N,N-dimethylpropionamide, 3-ethoxy-N,N-dimethylpropionamide, 3-propyloxy-N,N-dimethylpropionamide, and 3-butoxy-N,N-dimethylpropionamide. Among these, 3-methoxy-N,N-dimethylpropionamide is preferred. The organic solvent represented by the general formula (1) may be one that has been appropriately synthesized or a commercially available product may be used. For example, the commercially available product is R in the general formula (1). 1 Equamid M100 (manufactured by Idemitsu Kosan Co., Ltd.) in which R is a methyl group, and in the above general formula (1) 1 Examples include Equamid B100 (manufactured by Idemitsu Kosan Co., Ltd.), which has an n-butyl group.

[0134] There are no particular restrictions on the content of the organic solvent represented by the general formula (1) and it can be appropriately selected depending on the purpose, but it is preferably 3.0% by mass or more and 30.0% by mass or less relative to the clear ink, and more preferably 3.0% by mass or more and 20.0% by mass or less. When the content is 3% by mass or more and 30.0% by mass or less, the drying properties of the clear ink are improved and a record with excellent scratch resistance can be obtained.

[0135] -water- There are no particular restrictions on the water mentioned above, and it can be appropriately selected depending on the purpose. Examples include pure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, and distilled water, as well as ultrapure water. These may be used individually or in combination of two or more types. There are no particular restrictions on the water content, and it can be appropriately selected depending on the purpose, but it is preferably 15% by mass or more and 60% by mass or less relative to the clear ink. When the water content is 15% by mass or more, the viscosity of the clear ink is prevented, thereby improving the discharge stability, and when the water content is 60% by mass or less, the wettability to impermeable recording media is suitable, and the image quality can be improved.

[0136] -Other ingredients- Other components that may be included in the clear ink are not particularly limited and can be appropriately selected depending on the purpose. Examples include surfactants, organic solvents other than the organic solvent represented by the general formula (1), defoamers, antiseptics and antifungal agents, rust inhibitors, and pH adjusters.

[0137] There are no particular restrictions on the surfactant contained in the clear ink, and it can be appropriately selected depending on the purpose. Examples include silicone-based surfactants, fluorine-based surfactants, amphoteric surfactants, nonionic surfactants, and anionic surfactants. Surfactants are classified into nonionic, anionic, and amphoteric based on the polarity of their hydrophilic groups. Furthermore, based on the structure of the hydrophobic group, they are classified into fluorine-based, silicone-based, acetylene-based, etc. In this invention, fluorine-based surfactants are mainly used, but silicone-based surfactants and acetylene-based surfactants may also be used in combination.

[0138] There are no particular restrictions on the silicone-based surfactant, and it can be appropriately selected depending on the purpose. Among these, the silicone-based surfactant that does not decompose even at high pH is preferred. Examples include side-chain modified polydimethylsiloxane, both-end modified polydimethylsiloxane, one-end modified polydimethylsiloxane, and both-end modified polydimethylsiloxane. Those having a polyoxyethylene group or a polyoxyethylene polyoxypropylene group as a modifying group are particularly preferred because they exhibit good properties as aqueous surfactants. In addition, a polyether-modified silicone-based surfactant can also be used as the silicone-based surfactant. Examples include compounds in which a polyalkylene oxide structure is introduced into the Si side chain of dimethylsiloxane.

[0139] Such silicone-based surfactants may be synthesized as appropriate, or commercially available products may be used. Commercially available silicone-based surfactants include, for example, those from BIC Chemie Inc., Shin-Etsu Chemical Co., Ltd., Toray Dow Corning Silicone Co., Ltd., Nippon Emulsion Co., Ltd., and Kyoeisha Chemical Co., Ltd.

[0140] The polyether-modified silicone surfactant is not particularly limited and can be appropriately selected depending on the purpose. For example, one example is a polyalkylene oxide structure, represented by the following general formula (S-1), which is introduced into the Si side chain of dimethylpolysiloxane. [ka] (However, in the general formula (S-1) above, m, n, a, and b each independently represent integers, R represents an alkylene group, and R' represents an alkyl group.)

[0141] Specific examples of commercially available silicone-based surfactants include KF-618, KF-642, KF-643 (all manufactured by Shin-Etsu Chemical Co., Ltd.), EMALEX SS-5602, EMALEX SS-1906EX (both manufactured by Nippon Emulsion Co., Ltd.), DOWSIL FZ-2105, DOWSIL FZ-2118, DOWSIL FZ-2154, DOWSIL FZ-2161, DOWSIL FZ-2162, DOWSIL FZ-2163, DOWSIL FZ-2164 (all manufactured by Toray Dow Corning Silicone Co., Ltd.), BYK-33, BYK-387, BYK-019, BYK-025 (all manufactured by BIC Chemie Co., Ltd.), TSF4440, TSF4452, TSF4453 (all manufactured by Momentive Performance Materials Japan LLC), and Silface. Examples include SAG503A (manufactured by Nisshin Chemical Industry Co., Ltd.).

[0142] There are no particular restrictions on the content of the silicone-based surfactant, and it can be appropriately selected depending on the purpose, but it is preferably 4.00% by mass or less, more preferably 0.01% by mass or more and 4.00% by mass or less, and even more preferably 0.75% by mass or more and 3.00% by mass or less, relative to the total mass of the ink. By setting the content of the silicone-based surfactant to 4.00% by mass or less, the clouding of the ink is suppressed and it greatly contributes to improving the initial filling performance.

[0143] There are no particular restrictions on the fluorinated surfactant, and it can be appropriately selected depending on the purpose, but compounds with 2 to 16 fluorine-substituted carbon atoms are preferred, and compounds with 4 to 16 fluorine-substituted carbon atoms are more preferred. Among these, perfluoroalkyl sulfonic acid compounds, perfluoroalkyl carboxylic acid compounds, perfluoroalkyl phosphate ester compounds, perfluoroalkyl ethylene oxide adducts, and polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups in their side chains are preferred as fluorine-based surfactants because they have low foaming properties. These may be used individually or in combination of two or more.

[0144] Examples of the perfluoroalkyl sulfonic acid compound include perfluoroalkyl sulfonic acid and perfluoroalkyl sulfonate salts.

[0145] Examples of the perfluoroalkylcarboxylic acid compound include perfluoroalkylcarboxylic acids and perfluoroalkylcarboxylic acid salts.

[0146] Examples of polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups in their side chains include sulfate ester salts of polyoxyalkylene ether polymers having perfluoroalkyl ether groups in their side chains, and salts of polyoxyalkylene ether polymers having perfluoroalkyl ether groups in their side chains.

[0147] Examples of counterions for the salts in these fluorinated surfactants include Li, Na, K, NH4, NH3CH2CH2OH, NH2(CH2CH2OH)2, and NH(CH2CH2OH)3.

[0148] Among these, polyoxyalkylene ether polymer compounds having a perfluoroalkyl ether group in the side chain are preferred as the fluorine-based surfactant because they have low foaming properties, and fluorine-based surfactants represented by the following general formulas (F-1) and (F-2) are particularly preferred. [ka] (However, in the general formula (F-1) above, m and n each represent an integer independently.)

[0149] In the compound represented by the general formula (F-1) above, in order to impart water solubility, m is preferably an integer between 0 and 10, and n is preferably an integer between 0 and 40.

[0150] [ka] (However, in the above general formula (F-2), Y is H, C m F 2m+1 (where m is an integer from 1 to 6), CH2CH(OH)CH2-C m F 2m+1 (where m is an integer between 4 and 6), or C p H 2p+1 (where p represents an integer between 1 and 19, n represents an integer between 1 and 6, and a represents an integer between 4 and 14.)

[0151] As the fluorine-based surfactant, a suitably synthesized one may be used, or a commercially available product may be used. Examples of commercially available fluorine-based surfactants include: Surflon® S-111, S-112, S-113, S-121, S-131, S-132, S-141, S-145 (all manufactured by AGC Seimi Chemical Co., Ltd.); Flurad FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, FC-431 (all manufactured by Sumitomo 3M Limited); Megafac F-470, F-1405, F-474 (all manufactured by DIC Corporation); Zonyl® TBS, FSP, FSA, F Examples include SN-100, FSN, FSO-100, FSO, FS-300, UR, Capstone FS-30, FS-31, FS-3100, FS-34, FS-35 (all manufactured by Chemors); Futtergent (FT)-110, FT-250, FT-251, FT-400S, FT-150, FT-400SW (all manufactured by Neos Corporation); Polyfox (PF)-136A, PF-156A, PF-151N, PF-154, PF-159 (all manufactured by Omnova); and Unidyne DSN-403N (manufactured by Daikin Industries, Ltd.). Among these, the FS-3100, FS-34, and FS-300 from Chemors, Inc., the FT-110, FT-250, FT-251, FT-400S, FT-150, and FT-400SW from Neos Corporation, the PF-151N from Omnova Corporation, and the Unidyne DSN-403N from Daikin Industries, Ltd. are particularly preferred due to their excellent print quality, especially their significantly improved color development, penetration into paper, wettability, and uniform dyeing properties.

[0152] The aforementioned amphoteric surfactant is not particularly limited and can be appropriately selected depending on the purpose. Examples include laurylaminopropionate, lauryldimethylbetaine, stearyldimethylbetaine, and lauryldihydroxyethylbetaine. These may be used individually or in combination of two or more.

[0153] The nonionic surfactant is not particularly limited and can be appropriately selected depending on the purpose. Examples include polyoxyethylene alkylphenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene alkylamines, polyoxyethylene alkylamides, polyoxyethylene propylene block polymers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, and ethylene oxide adducts of acetylene alcohol. These may be used individually or in combination of two or more.

[0154] The anionic surfactant is not particularly limited and can be appropriately selected depending on the purpose. Examples include polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, lauryl salt, and polyoxyethylene alkyl ether sulfate salts. These may be used individually or in combination of two or more.

[0155] Other than the organic solvent represented by the general formula (1) above, there are no particular restrictions on the organic solvent, and they can be appropriately selected depending on the purpose, such as water-soluble organic solvents. Note that water solubility means, for example, that 5 g or more dissolves in 100 g of water at 25°C.

[0156] Examples of the water-soluble organic solvents include polyhydric alcohols such as ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 3-methyl-1,3-butanediol, 3-methoxy-3-methylbutanol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,5-pentanediol, 2-methyl-2,4-pentanediol, 1,6-hexanediol, glycerin, 1,2,6-hexanetriol, 2-ethyl-1,3-hexanediol, ethyl-1,2,4-butanetriol, 1,2,3-butanetriol, petriol, etc.; ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether Examples include polyhydric alcohol alkyl ethers such as diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol monoethyl ether, and dipropylene glycol monomethyl ether; polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether; nitrogen-containing heterocyclic compounds such as 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethylimidazolidinone, ε-caprolactam, and γ-butyrolactone; amides such as formamide, N-methylformamide, and N,N-dimethylformamide; amines such as monoethanolamine, diethanolamine, and triethylamine; sulfur-containing compounds such as dimethyl sulfoxide, sulfolane, and thiodiethanol; and propylene carbonate. These may be used individually or in combination of two or more.

[0157] There are no particular restrictions on the content of organic solvents other than the organic solvent represented by the general formula (1) above, and they can be appropriately selected depending on the purpose. However, from the viewpoint of ink drying properties and discharge reliability, the clear ink is preferably 10% by mass or more and 60% by mass or less, and more preferably 20% by mass or more and 60% by mass or less.

[0158] There are no particular limitations on the aforementioned defoaming agent; examples include silicone-based defoaming agents, polyether-based defoaming agents, and fatty acid ester-based defoaming agents. These may be used individually or in combination of two or more. Among these, silicone-based defoaming agents are preferred due to their superior foam-breaking effect.

[0159] There are no particular restrictions on the aforementioned preservative and antifungal agent; for example, 1,2-benzisothiazolin-3-one is one such example.

[0160] There are no particular restrictions on the rust inhibitor, and examples include acidic sulfites and sodium thiosulfate.

[0161] The pH adjusting agent is not particularly limited as long as it can adjust the pH to 7 or higher, and examples include amines such as diethanolamine and triethanolamine.

[0162] There are no particular restrictions on the physical properties of the clear ink, and they can be appropriately selected according to the purpose. For example, it is preferable that the viscosity, surface tension, pH, etc., are within the following ranges. The viscosity of the clear ink at 25°C is preferably between 5 mPa·s and 30 mPa·s, and more preferably between 5 mPa·s and 25 mPa·s, as this improves print density and character quality and ensures good ejection. Here, viscosity can be measured using, for example, a rotational viscometer (RE-80L, manufactured by Toki Sangyo Co., Ltd.). Measurement conditions are 25°C, standard cone rotor (1°34'×R24), sample volume of 1.2 mL, rotation speed of 50 rpm, and measurement can be performed in 3 minutes. The surface tension of the clear ink is preferably 35 mN / m or less, and more preferably 32 mN / m or less, at 25°C, in order to ensure that the clear ink levels well on the recording medium and shorten the drying time of the clear ink. The pH of the clear ink is preferably 7 to 12, and more preferably 8 to 11, from the viewpoint of preventing corrosion of the metal components that come into contact with the ink.

[0163] There are no particular restrictions on the method of applying the clear ink in the clear ink application step, and it can be appropriately selected according to the purpose. Examples include the inkjet method, blade coating method, gravure coating method, gravure offset coating method, bar coating method, roll coating method, knife coating method, air knife coating method, comma coating method, U comma coating method, AKKU coating method, smoothing coating method, microgravure coating method, reverse roll coating method, 4-roll coating method, 5-roll coating method, dip coating method, curtain coating method, slide coating method, and die coating method. Among these, the inkjet method is preferred.

[0164] There are no particular restrictions on the average thickness of the dried film of the clear ink (hereinafter sometimes referred to as the "overcoat layer") in the clear ink application step, and it can be appropriately selected depending on the purpose, but it is preferably 3 μm or more and 10 μm or less. If the average thickness is 3 μm or more, a record with excellent scratch resistance can be obtained, and if the average thickness is 10 μm or less, drying performance is improved, so blocking of the record can be suppressed.

[0165] There are no particular restrictions on the amount of clear ink applied in the clear ink application step, and it can be appropriately selected according to the purpose, but 10.0 g / m² is a reasonable amount. 2 More than 35.0g / m 2 The following is preferable: The amount applied is 10.0 g / m². 2 When the amount is greater than or equal to 35.0 g / m², the abrasion resistance is improved, and the amount applied is 35.0 g / m². 2 The following conditions improve adhesion.

[0166] <Other processes and other means> The aforementioned other processes are not particularly limited and can be selected as appropriate depending on the purpose, for example, a drying process. The aforementioned other means are not particularly limited and can be appropriately selected depending on the purpose, and examples include drying methods.

[0167] The drying step involves drying at least one of the primer layer, the color ink layer, and the clear ink layer, and can be carried out by the drying means. The drying process can be carried out after the formation of the primer layer but before the formation of the color ink layer, during the formation of the color ink layer, after the formation of the color ink layer but before the formation of the clear ink layer, and after the formation of the clear ink layer.

[0168] The drying means is not particularly limited as long as it is a means of heating or drying the printed surface or back surface of the recording medium, and can be appropriately selected depending on the purpose. Examples include hot air heaters and infrared heaters. The infrared heater preferably includes at least a near-infrared irradiation device. Examples of the near-infrared irradiation device include a device having a halogen lamp and a reflective mirror, and a product has been commercialized that achieves efficient heating by incorporating a halogen heater into the reflective mirror and creating a heating unit. There are no particular restrictions on commercially available infrared heaters, and they can be appropriately selected according to the purpose. Examples include UH-USC-CL300, UHUSC-CL700, UH-USC-CL1000, UH-USD-CL300, UHUSD-CL700, UH-USD-CL1000, UH-MA1-CL300, UHMA1-CL700, and UH-MA1-CL1000 (all manufactured by Ushio Inc.).

[0169] There are no particular restrictions on the drying temperature in the drying process, and it can be appropriately selected depending on the purpose, but 50°C or higher is preferred, and 70°C to 90°C is more preferred. When the drying temperature is 50°C or higher, the drying performance of each layer is improved. The drying temperature refers to the surface temperature of the drying means itself.

[0170] The aforementioned substrate (which may hereinafter be referred to as the "recording medium") is not particularly limited and can be appropriately selected depending on the purpose. Examples include plain paper, glossy paper, specialty paper, cloth, and non-permeable substrates. The printing method and printing apparatus of the present invention are capable of forming good images even on non-permeable substrates that are prone to beading. The aforementioned non-permeable substrate is a substrate having a surface with low water permeability and absorption, and includes materials that have numerous internal cavities but do not open to the outside. More quantitatively, in the Bristow method, from the start of contact for 30 msec 1 / 2 Up to 10 mL / m² of water absorption capacity 2 The following refers to the base material. The aforementioned non-permeable substrate is not particularly limited and can be appropriately selected depending on the purpose. Examples include plastic films such as polyvinyl chloride resin film, polyethylene terephthalate (PET) film, polypropylene, polyethylene, and polycarbonate film. In addition to materials commonly used as recording media, other materials such as wallpaper, flooring, tiles, fabrics for clothing like T-shirts, textiles, and leather can be used as appropriate. Furthermore, by adjusting the configuration of the transport path for the recording media, ceramics, glass, and metals can also be used.

[0171] There are no particular restrictions on the polypropylene and polyethylene mentioned above, and they can be appropriately selected depending on the purpose. For example, AR1025, AR1056, AR1082, EC1082, 1082D, 1073D, 1056D, 1025D, FR1073 (Asahi-DuPont Flashspun) Examples include Yupo Products Co., Ltd., P2002, P2102, P2108, P2161, P2171, P2111, P4266, P5767, P3162, P6181, P8121, P1162, P1111, P1128, P1181, P1153, P1157, P1146, P1147, P1171 (Toyobo Co., Ltd.), YPI, Aqua Yupo, Super Yupo, Ultra Yupo, New Yupo, Yupo Illuminated Paper, Yupo Building Materials Paper, Yupo High Gloss, Yupo Jet, Metallic Yupo (Yupo Corporation).

[0172] <Records> The ink recording material of the present invention has an image formed on a recording medium using the ink of the present invention. It can be recorded and produced as a recording material by an inkjet printing apparatus and an inkjet recording method.

[0173] The printing apparatus of the present invention comprises at least a primer-applying means, a color ink-applying means, and a clear ink-applying means.

[0174] The primer-applying means is a means of applying a primer containing a cationic resin, a polyvalent metal salt, and a diethylene glycol alkyl ether-based organic solvent onto a non-penetrating substrate. As the primer, the primer described above in the printing method of the present invention can be used.

[0175] The color ink application means is a means of applying a color ink containing resin particles having a glass transition temperature (Tg) of less than 0°C and an organic solvent represented by the following general formula (1) to the region to which the primer has been applied. As the aforementioned color ink, the color ink described above in the printing method of the present invention can be used.

[0176] The clear ink application means is a means of applying a clear ink to at least the region to which the color ink has been applied, which contains resin particles having a volume-average particle size of 50 nm or less, and an organic solvent represented by the following general formula (1), and whose dried film has a glass transition temperature (Tg) of 50°C or higher and below 0°C. As the clear ink, the clear ink described above in the printing method of the present invention can be used.

[0177] Examples of printing devices of the present invention include various printing devices using inkjet recording methods. Furthermore, the printing device of the present invention can be suitably used in printers, facsimile machines, copying machines, printer / fax / copier combination machines, 3D modeling machines, and the like. In this application, "printing apparatus" and "recording method" refer to an apparatus capable of ejecting ink or various processing liquids onto a recording medium, and a method of recording using such an apparatus. "Recording medium" means a material to which ink or various processing liquids can be temporarily attached. This printing apparatus may include not only the print head that ejects ink, but also means for feeding, transporting, and ejecting recording media, as well as other devices referred to as pre-processing devices and post-processing devices. Furthermore, printing devices and recording methods are not limited to those that visualize meaningful images such as characters and figures using ink. For example, they also include those that form patterns such as geometric designs, and those that create three-dimensional images. In addition, unless otherwise specified, printing devices include both serial type devices that move the ejection head and line type devices that do not move the ejection head. Furthermore, this printing equipment includes not only desktop models, but also wide-format printers capable of printing on A0-sized recording media, and continuous-feed printers that can use, for example, rolls of continuous paper as recording media.

[0178] An example of the aforementioned printing apparatus will be described with reference to Figures 1 and 2. Figure 1 is a perspective view illustrating the device. Figure 2 is a perspective view of the main tank. The image forming apparatus 400, as an example of the printing apparatus, is a serial-type image forming apparatus. A mechanism 420 is provided inside the outer casing 401 of the image forming apparatus 400. The ink storage sections 411 of the main tanks 410 (410k, 410c, 410m, 410y) for each color, black (K), cyan (C), magenta (M), and yellow (Y), are formed from packaging materials such as aluminum laminate film. The ink storage sections 411 are housed in, for example, plastic storage containers 414. Thus, the main tanks 410 are used as ink cartridges for each color. Meanwhile, a cartridge holder 404 is provided at the back of the opening when the cover 401c of the main body of the device is opened. The main tank 410 is detachably mounted on the cartridge holder 404. As a result, the ink outlets 413 of the main tank 410 and the ejection heads 434 for each color are connected via supply tubes 436 for each color, enabling the ejection heads 434 to eject primer onto the recording medium.

[0179] Here, embodiments of the printing apparatus used in the printing method of the present invention will be described in detail with reference to the drawings. In each drawing, the same components are denoted by the same reference numerals, and redundant explanations may be omitted. Furthermore, the number, position, shape, etc. of the following components are not limited to this embodiment, and can be set to a number, position, shape, etc. that is preferable for carrying out the present invention.

[0180] Figure 3 is a schematic diagram showing an example of a printing apparatus used in the printing method of the present invention. Note that the primer application step, the color ink application step, and the clear ink application step in the printing method of the present invention may be performed in the same printing apparatus or in separate printing apparatuses.

[0181] The printing apparatus 100 in Figure 3 includes a primer application unit 110, an ink application unit 120, a clear ink application unit 130, a drying unit 140, and a transport unit 150. The drying unit 140 and the transport unit 150 may be omitted.

[0182] The primer application unit 110 applies a primer to the recording medium M.

[0183] The color ink application unit 120 applies color ink to the primer-coated surface of the recording medium M. For example, a known inkjet head can be used as the color ink application unit 120. The color ink dispensing unit 120 may be an inkjet head that ejects ink of any color. For example, an inkjet head that ejects ink of the following colors as needed may be provided: Y (yellow), M (magenta), C (cyan), K (black), and W (white). Alternatively, a primer may be ejected from a portion of the head that ejects the color ink. In this case, the primer application unit 110 may be omitted.

[0184] The clear ink application unit 130 only needs to be able to apply clear ink to the colored ink-applied area on the colored ink-applied surface of the recording medium M. For example, in addition to an inkjet head, a spray or roller can be used.

[0185] The drying unit 140 dries the recording medium M to which the clear ink has been applied with hot air. The drying unit 140 may use infrared rays, microwaves, a roll heater, or the like instead of hot air to heat and dry the recording medium M to which the clear ink has been applied, or the recording medium M to which the clear ink has been applied may be allowed to air dry without operating the drying unit 140.

[0186] The transport unit 150 transports the recording medium M. The transport unit 150 is not particularly limited as long as it is capable of transporting the recording medium M, and can be appropriately selected according to the purpose, for example, a transport belt, a platen, etc.

[0187] The printing apparatus 100 may further include a fixing unit for heating and fixing the image formed on the recording medium M. There are no particular restrictions on the fixing unit, and it can be appropriately selected according to the purpose; for example, a fixing roller can be used.

[0188] Furthermore, in the terminology used in this invention, image formation, recording, printing, and the like are all synonymous. [Examples]

[0189] The following describes embodiments of the present invention, but the present invention is not limited in any way to these embodiments.

[0190] (Example of primer preparation 1) In a container fitted with a stirrer, reflux condenser, and thermometer, 2.0% by mass of Superflex 650 (urethane-based cationic resin particles, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., non-volatile content: 26%) as a cationic resin, 0.25% by mass of magnesium acetate tetrahydrate as a polyvalent metal salt, 5.5% by mass of diethylene glycol diethyl ether as a diethylene glycol alkyl ether-based organic solvent, 15% by mass of propylene glycol and 10% by mass of 3-methoxy-3-methyl-1-butanol as other organic solvents, 0.5% by mass of SAG503A (polysiloxane-based surfactant, manufactured by Nisshin Chemical Industry Co., Ltd., HLB value: 11) as a surfactant, 0.01% by mass of Proxel LV (manufactured by Abyssia) as a preservative and antifungal agent, and 66.7% by mass of water were added and mixed and stirred. The mixture was then filtered through a filter (Minisart, manufactured by Sartorius, 10 μm) to obtain Primer A. The composition of Primer A is shown in Table 1 below.

[0191] (Example of primer preparation 2) Primer B was obtained in the same manner as in Primer Preparation Example 1, except that the content of magnesium acetate tetrahydrate as a polyvalent metal salt was changed to 10.0% by mass. The composition of Primer B is shown in Table 1 below.

[0192] (Example of primer preparation 3) Primer C was obtained in the same manner as in Primer Preparation Example 1, except that the content of Superflex 650 as a cationic resin was changed to 15.0% by mass. The composition of Primer C is shown in Table 1 below.

[0193] (Example of primer preparation 4) Primer D was obtained in the same manner as in Primer Preparation Example 3, except that the content of magnesium acetate tetrahydrate as a polyvalent metal salt was changed to 10.0% by mass. The composition of Primer D is shown in Table 1 below.

[0194] (Example of primer preparation 5) Primer E was obtained in the same manner as in Primer Preparation Example 1, except that the content of diethylene glycol diethyl ether as the diethylene glycol alkyl ether-based organic solvent was changed to 30.0% by mass. The composition of Primer E is shown in Table 1 below.

[0195] (Example of primer preparation 6) Primer F was obtained in the same manner as in Primer Preparation Example 2, except that the content of diethylene glycol diethyl ether as the diethylene glycol alkyl ether-based organic solvent was changed to 30.0% by mass. The composition of Primer F is shown in Table 1 below.

[0196] (Example of primer preparation 7) Primer G was obtained in the same manner as in Primer Preparation Example 3, except that the content of diethylene glycol diethyl ether as the diethylene glycol alkyl ether-based organic solvent was changed to 30.0% by mass. The composition of Primer G is shown in Table 1 below.

[0197] (Example of primer preparation 8) Primer H was obtained in the same manner as in Primer Preparation Example 4, except that the content of diethylene glycol diethyl ether as the diethylene glycol alkyl ether-based organic solvent was changed to 30.0% by mass. The composition of Primer H is shown in Table 1 below.

[0198] (Example of primer preparation 9) Primer I was obtained in the same manner as in Primer Preparation Example 1, except that the content of Superflex 650 as a cationic resin was changed to 12.0% by mass, and the content of diethylene glycol diethyl ether as a diethylene glycol alkyl ether-based organic solvent was changed to 4.5% by mass. The composition of Primer I is shown in Table 2 below.

[0199] (Example of primer preparation 10) Primer J was obtained in the same manner as in Primer Preparation Example 9, except that the content of diethylene glycol diethyl ether as the diethylene glycol alkyl ether-based organic solvent was changed to 30.5% by mass. The composition of Primer J is shown in Table 2 below.

[0200] (Example of primer preparation 11) Primer K was obtained in the same manner as in Primer Preparation Example 9, except that 4.5% by mass of diethylene glycol diethyl ether was replaced with 5.0% by mass of diethylene glycol dimethyl ether. The composition of Primer K is shown in Table 2 below.

[0201] (Example of primer preparation 12) Primer L was obtained in the same manner as in Primer Preparation Example 9, except that the content of diethylene glycol diethyl ether as the diethylene glycol alkyl ether-based organic solvent was changed to 14.5% by mass. The composition of Primer L is shown in Table 2 below.

[0202] (Example of primer preparation 13) Primer M was obtained in the same manner as in Primer Preparation Example 1, except that the content of Superflex 650 as a cationic resin was changed to 12.0% by mass, and magnesium acetate tetrahydrate as a polyvalent metal salt was changed to magnesium nitrate hexahydrate. The composition of Primer M is shown in Table 2 below.

[0203] (Example of primer preparation 14) Primer N was obtained in the same manner as in Primer Preparation Example 1, except that the content of Superflex 650 as a cationic resin was changed to 1.5% by mass. The composition of Primer N is shown in Table 2 below.

[0204] (Example of primer preparation 15) Primer O was obtained in the same manner as in Primer Preparation Example 1, except that the content of Superflex 650 as a cationic resin was changed to 15.5% by mass. The composition of Primer O is shown in Table 2 below.

[0205] (Primer preparation example 16) Primer P was obtained in the same manner as in Primer Preparation Example 1, except that diethylene glycol diethyl ether was replaced with triethylene glycol monobutyl ether. The composition of Primer P is shown in Table 3 below.

[0206] (Primer preparation example 17) Primer Q was obtained in the same manner as in Primer Preparation Example 1, except that diethylene glycol diethyl ether was replaced with ethyl acetate. The composition of Primer Q is shown in Table 3 below.

[0207] (Example of primer preparation 18) Primer R was obtained in the same manner as in Primer Preparation Example 1, except that diethylene glycol diethyl ether was replaced with γ-butyrolactone. The composition of Primer R is shown in Table 3 below.

[0208] (Example of primer preparation 19) Primer S was obtained in the same manner as in Primer Preparation Example 1, except that Superflex 650 as the cationic resin was replaced with Superflex 126 (urethane-based anionic resin particles, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., non-volatile content: 30%). The composition of Primer S is shown in Table 3 below.

[0209] (Example of primer preparation 20) Primer T was obtained in the same manner as in Primer Preparation Example 1, except that magnesium acetate tetrahydrate, used as a polyvalent metal salt, was replaced with sodium acetate. The composition of Primer T is shown in Table 3 below.

[0210] [Table 1]

[0211]

Table 2

[0212]

Table 3

[0213] <Preparation Example of Pigment Dispersion (Black Pigment Dispersion)> 100 g of SRF-LS (carbon black, manufactured by Tokai Carbon Co., Ltd.) was added to 3,000 mL of 2.5 N (normal) sodium hypochlorite solution, and stirred at a temperature of 60 °C and a speed of 300 rpm for 10 hours for oxidation treatment to obtain a pigment with carboxylic acid groups imparted on the surface of the carbon black. The obtained pigment was filtered, and the separated carbon black was neutralized with an aqueous sodium hydroxide solution followed by ultrafiltration. Next, ultrafiltration using a dialysis membrane was performed using the pigment dispersion and ion-exchanged water, and further, ultrasonic dispersion was performed to obtain a black pigment dispersion having a volume average particle diameter of 100 nm with the pigment solid content concentrated to 20%.

[0214] <Preparation Example 1 of Resin Particles> In a 2 L reactor equipped with a stirrer, a thermometer, a nitrogen seal tube and a cooler, 100 parts by mass of methyl ethyl ketone, 345 parts by mass of polyester polyol (polyester polyol obtained from isophthalic acid (IPA) / adipic acid (AA) = 6 / 4 (molar ratio) and ethylene glycol (EG) / neopentyl glycol (NPG) = 1 / 9 (molar ratio), number average molecular weight Mn: 2,000, average functional group number: 2), and 9.92 parts by mass of 2,2-dimethylolpropionic acid (DMPA) were charged and uniformly mixed at 60 °C. Thereafter, 40.5 parts by mass of triethylene glycol diisocyanate (TEGDI) and 0.08 parts by mass of dioctyltin dilaurate (DOTDL) were charged and reacted at 72 °C for 3 hours to obtain a polyurethane solution. To the obtained polyurethane solution, 80 parts by mass of isophthalic acid (IPA), 220 parts by mass of methyl ethyl ketone (MEK), 3.74 parts by mass of triethanolamine (TEA), and 596 parts by mass of water were charged and the mixture was inverted. Then, MEK and IPA were removed using a rotary evaporator to obtain a resin emulsion. After the obtained resin emulsion was cooled to room temperature, deionized water and sodium hydroxide aqueous solution were added to obtain [resin emulsion 1] (polyester-based polyurethane resin) with a solid content of 30% by mass and pH 8.

[0215] The glass transition temperature (Tg) of the obtained [resin emulsion 1] was measured according to the <Method for measuring the glass transition temperature of resin emulsion> described below, and was found to be -4°C. In addition, the volume-average particle size was measured using a particle size analyzer (Nanotrac WaveII, Microtrac-Bell) and was found to be 105 nm.

[0216] <Method for measuring the glass transition temperature of resin emulsions> Differential scanning calorimeters (TA-60WS and DSC-60, manufactured by Shimadzu Corporation) were used to measure the glass transition temperature of the resin emulsion. First, 4 g of resin emulsion was uniformly spread in a 50 mm diameter tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) petri dish. After drying at 50°C for one week, 5.0 mg of the resulting resin film was placed in an aluminum sample container. The sample container was then placed on a holder unit and set in an electric furnace. Next, under a nitrogen atmosphere, the temperature was raised from 0°C to 150°C at a rate of 10°C / min, then cooled from 150°C to -80°C at a rate of 5°C / min, and finally raised again to 150°C at a rate of 10°C / min to measure the DSC curve. From the obtained DSC curve, the glass transition temperature (Tg) was determined by analyzing the inflection point during the second heating cycle using the midpoint method with the analysis program in the DSC-60 system.

[0217] <Example of resin particle preparation 2> In a reactor equipped with a stirrer, reflux condenser, and thermometer, 1,500 parts by mass of polycarbonate diol (reaction product of 1,6-hexanediol and dimethyl carbonate, number average molecular weight Mn: 1,200), 300 parts by mass of 2,2-dimethylolpropionic acid (DMPA), and 1,420 parts by mass of N-methylpyrrolidone (NMP) were charged under a nitrogen stream and heated to 60°C to dissolve the DMPA. Next, 1,824 parts by mass of 4,4'-dicyclohexylmethane diisocyanate and 2.6 parts by mass of dibutyltin dilaurylate as a catalyst were added, and the mixture was heated to 90°C. The urethane reaction was carried out over 5 hours to obtain an isocyanate-terminated urethane prepolymer. The obtained isocyanate-terminated urethane prepolymer was cooled to 80°C, 260 parts by mass of triethylamine was added, and 4,340 parts by mass were withdrawn from the mixture and added to a mixed solution of 5,400 parts by mass of water and 15 parts by mass of triethylamine under strong stirring. Next, 1,500 parts by mass of ice were added, and 830 parts by mass of a 35% by mass aqueous solution of 2-methyl-1,5-pentanediamine was added to carry out the chain extension reaction. The solvent was then removed by distillation to obtain [resin emulsion 2] (polycarbonate-based polyurethane resin). The glass transition temperature (Tg) of the obtained [Resin Emulsion 2] was measured in the same manner as for [Resin Emulsion 1], and it was found to be 55°C. Furthermore, the volume-average particle size was measured in the same manner as for [Resin Emulsion 1], and it was found to be 44 nm.

[0218] <Example 3 of resin particle preparation> In a reactor equipped with a stirrer, reflux condenser, and thermometer, 1,500 parts by mass of polycarbonate diol (reaction product of 1,6-hexanediol and dimethyl carbonate, number average molecular weight Mn: 1,200), 260 parts by mass of 2,2-dimethylolpropionic acid (DMPA), and 1,320 parts by mass of N-methylpyrrolidone (NMP) were charged under a nitrogen stream and heated to 60°C to dissolve the DMPA. Next, 1,530 parts by mass of 4,4'-dicyclohexylmethane diisocyanate and 2.6 parts by mass of dibutyltin dilaurylate as a catalyst were added, and the mixture was heated to 90°C. The urethane reaction was carried out over 5 hours to obtain an isocyanate-terminated urethane prepolymer. The obtained isocyanate-terminated urethane prepolymer was cooled to 80°C, 245 parts by mass of triethylamine was added, and 4,340 parts by mass were withdrawn from the mixture and added to a mixed solution of 5,400 parts by mass of water and 15 parts by mass of triethylamine under strong stirring. Next, 1,500 parts by mass of ice were added, and 793 parts by mass of a 35% by mass aqueous solution of 2-methyl-1,5-pentanediamine was added to carry out the chain extension reaction. The solvent was then removed by distillation to obtain [resin emulsion 3] (polycarbonate-based polyurethane resin). The glass transition temperature (Tg) of the obtained [resin emulsion 3] was measured in the same manner as for [resin emulsion 1], and it was found to be 45°C. Furthermore, the volume-average particle size was measured in the same manner as for [resin emulsion 1], and it was found to be 40 nm.

[0219] <Example 4 of resin particle preparation> In a reactor equipped with a stirrer, reflux condenser, and thermometer, 1,500 parts by mass of polycarbonate diol (reaction product of 1,6-hexanediol and dimethyl carbonate, number average molecular weight Mn: 1,200), 350 parts by mass of 2,2-dimethylolpropionic acid (DMPA), and 2,300 parts by mass of N-methylpyrrolidone (NMP) were charged under a nitrogen stream and heated to 60°C to dissolve the DMPA. Next, 2,100 parts by mass of 4,4'-dicyclohexylmethane diisocyanate and 2.6 parts by mass of dibutyltin dilaurylate as a catalyst were added, and the mixture was heated to 90°C. The urethane reaction was carried out over 5 hours to obtain an isocyanate-terminated urethane prepolymer. The obtained isocyanate-terminated urethane prepolymer was cooled to 80°C, 270 parts by mass of triethylamine was added, and 4,340 parts by mass were withdrawn from the mixture and added to a mixed solution of 5,400 parts by mass of water and 15 parts by mass of triethylamine under strong stirring. Next, 1,500 parts by mass of ice were added, and 800 parts by mass of a 35% by mass aqueous solution of 2-methyl-1,5-pentanediamine was added to carry out the chain extension reaction. The solvent was then removed by distillation to obtain [resin emulsion 4] (polycarbonate-based polyurethane resin). The glass transition temperature (Tg) of the obtained [resin emulsion 4] was measured in the same manner as for [resin emulsion 1], and it was found to be 56°C. Furthermore, the volume-average particle size was measured in the same manner as for [resin emulsion 1], and it was found to be 57 nm.

[0220] (Example of color ink preparation 1) 5% by mass of the black pigment dispersion obtained in the above <Example of Pigment Dispersion Preparation>, 3% by mass of the above [Resin Emulsion 1] (polyester polyurethane resin, glass transition temperature: -4℃, volume average particle size: 105 nm, solids content: 30% by mass) as resin particles, 8% by mass of acrylic resin emulsion (Boncoat CP-6450, glass transition temperature: 42℃, solids content: 40% by mass), and Equamid M100 (manufactured by Idemitsu Kosan Co., Ltd., R) as an organic solvent represented by general formula (1). 1 Color ink A was obtained by mixing and stirring 3% by mass of methyl group, 5% by mass of diethylene glycol monobutyl ether as other organic solvents, 27% by mass of propylene glycol, 0.5% by mass of FS-300 (fluorine-based surfactant, manufactured by DuPont, solids content: 40% by mass) as a surfactant, and 48.5% by mass of water. The mixture was then filtered through a polypropylene filter with an average pore size of 0.2 μm (product name: Betafine polypropylene pleated filter PPG series, manufactured by 3M). The composition of the obtained color ink A is shown in Table 4 below.

[0221] (Example of color ink preparation 2) In the first example of color ink preparation, the organic solvent represented by general formula (1) is Equamid B100 (manufactured by Idemitsu Kosan Co., Ltd., R 1 Color ink B was obtained in the same manner as in Color Ink Preparation Example 1, except that the amount of n-butyl group was changed to 5% by mass and the propylene glycol content was changed to 24% by mass. The composition of color ink B is shown in Table 4 below.

[0222] (Preparation Example 3 of Color Ink) In Preparation Example 1 of color ink, except that 3% by mass of [Resin Emulsion 1] as resin particles and 8% by mass of acrylic resin emulsion were changed to 10% by mass of acrylic resin emulsion and the content of propylene glycol was changed to 30% by mass, color ink C was obtained in the same manner as in Preparation Example 1 of color ink. The composition of the obtained color ink C is shown in Table 4 below.

[0223] (Preparation Example 4 of Color Ink) In Preparation Example 1 of color ink, except that aquamide M100 as the organic solvent represented by the general formula (1) was not contained and the content of propylene glycol was changed to 29% by mass, color ink D was obtained in the same manner as in Preparation Example 1 of color ink. The composition of color ink D is shown in Table 4 below.

[0224] [Table 4]

[0225] (Preparation Example 1 of Clear Ink) 0.4% by mass of the above [Resin Emulsion 1] (polyester-based urethane resin, glass transition temperature: -4°C, volume average particle diameter: 105 nm, solid content: 30% by mass), 29.6% by mass of the above [Resin Emulsion 2] (polycarbonate-based urethane resin, glass transition temperature: 55°C, volume average particle diameter: 44 nm, solid content: 30% by mass), 3.5% by mass of aquamide M100 (manufactured by Idemitsu Kosan Co., Ltd., R 1 = methyl group) as the organic solvent represented by the general formula (1), 13.0% by mass of 1,2-propanediol, 10.5% by mass of 1,3-propanediol, 3.0% by mass of 1,2-butanediol as other organic solvents, 6% by mass of FS-300 (fluorine-based surfactant, manufactured by DuPont, solid content: 40% by mass) as a surfactant, and 34% by mass of high-purity water were added and mixed and stirred to prepare a mixture.<Next, the resulting mixture was filtered through a polypropylene filter with an average pore size of 0.2 μm (product name: Betafine Polypropylene Pleated Filter PPG Series, manufactured by 3M) to obtain [Clear Ink A]. The glass transition temperature (Tg) of the obtained [Clear Ink A] was measured according to the <Method for Measuring the Glass Transition Temperature of the Dry Film of Clear Ink> described below, and the results were 55°C and -4°C. Furthermore, the volume-average particle size was measured using a particle size analyzer (Nanotrac Wave II, Microtrac-Bel), and it was found to be 44 nm. The resin solid content in the obtained clear ink was 9% by mass. The composition of the obtained [Clear Ink A] is shown in Table 5 below.

[0226] <Method for measuring the glass transition temperature of a dried clear ink film> The glass transition temperature of the dried clear ink film was measured using a differential scanning calorimeter (TA-60WS and DSC-60, manufactured by Shimadzu Corporation). First, 4 g of clear ink was uniformly spread in a 50 mm diameter tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) petri dish. After drying at 50°C for one week, 5.0 mg of the resulting ink film was placed in an aluminum sample container. The sample container was then placed on a holder unit and set in an electric furnace. Next, under a nitrogen atmosphere, the temperature was raised from 0°C to 150°C at a rate of 10°C / min, then cooled from 150°C to -80°C at a rate of 5°C / min, and finally raised again to 150°C at a rate of 10°C / min to measure the DSC curve. From the obtained DSC curve, the glass transition temperature (Tg) was determined by analyzing the inflection point during the second heating cycle using the midpoint method with the analysis program in the DSC-60 system.

[0227] (Example of clear ink preparation 2) Clear Ink B was obtained in the same manner as in Clear Ink Preparation Example 1, except that the resin particles were changed to [Resin Emulsion 1] 1.0% by mass and [Resin Emulsion 2] 29.0% by mass. The glass transition temperature (Tg) of the obtained [Clear Ink B] ​​was measured in the same manner as for [Clear Ink A], and was found to be 55°C and -4°C. The volume-average particle size was also measured in the same manner as for [Clear Ink A], and was found to be 45 nm. The resin solid content in the obtained clear ink was 9% by mass. The composition of the obtained [Clear Ink B] ​​is shown in Table 6 below.

[0228] (Example of clear ink preparation 3) Clear Ink C was obtained in the same manner as in Clear Ink Preparation Example 1, except that the resin particles were changed to [Resin Emulsion 1] 3.0% by mass and [Resin Emulsion 2] 27.0% by mass, and the 1,2-propanediol content was changed to 13.5% by mass. The glass transition temperature (Tg) of the obtained [Clear Ink C] was measured in the same manner as for [Clear Ink A], and was found to be 54°C and -3°C. The volume-average particle size was also measured in the same manner as for [Clear Ink A], and was found to be 46 nm. The resin solid content in the obtained clear ink was 9% by mass. The composition of the obtained [Clear Ink C] is shown in Table 6 below.

[0229] (Example of clear ink preparation 4) Clear Ink D was obtained in the same manner as in Clear Ink Preparation Example 1, except that the resin particles were changed to [Resin Emulsion 1] 5.5% by mass and [Resin Emulsion 2] 24.5% by mass, and the 1,2-propanediol content was changed to 14.5% by mass. The glass transition temperature (Tg) of the obtained [Clear Ink D] was measured in the same manner as for [Clear Ink A], and was found to be 54°C and -3°C. The volume-average particle size was also measured in the same manner as for [Clear Ink A], and was found to be 47 nm. The resin solid content in the obtained clear ink was 9% by mass. The composition of the obtained [Clear Ink D] is shown in Table 6 below.

[0230] (Example of clear ink preparation 5) Clear Ink E was obtained in the same manner as in Clear Ink Preparation Example 1, except that the resin particles were changed to [Resin Emulsion 1] 7.0% by mass and [Resin Emulsion 2] 23.0% by mass, and the 1,2-propanediol content was changed to 15.5% by mass. The glass transition temperature (Tg) of the obtained [Clear Ink E] was measured in the same manner as for [Clear Ink A], and was found to be 54°C and -3°C. The volume-average particle size was also measured in the same manner as for [Clear Ink A], and was found to be 49 nm. The resin solid content in the obtained clear ink was 9% by mass. The composition of the obtained [Clear Ink E] is shown in Table 6 below.

[0231] (Example of clear ink preparation 6) Clear Ink F was obtained in the same manner as in Clear Ink Preparation Example 1, except that the resin particles were changed to [Resin Emulsion 1] 2.0% by mass and [Resin Emulsion 2] 32.0% by mass, and the 1,2-propanediol content was changed to 12.0% by mass. The glass transition temperature (Tg) of the obtained [Clear Ink F] was measured in the same manner as for [Clear Ink A], and was found to be 54°C and -3°C. The volume-average particle size was also measured in the same manner as for [Clear Ink A], and was found to be 46 nm. The resin solid content in the obtained clear ink was 10.2% by mass. The composition of the obtained [Clear Ink F] is shown in Table 6 below.

[0232] (Example of clear ink preparation 7) Clear Ink G was obtained in the same manner as in Clear Ink Preparation Example 1, except that the resin particles were changed to [Resin Emulsion 1] 1.0% by mass and [Resin Emulsion 2] 29.0% by mass, the organic solvent represented by general formula (1) was changed to Equamid M100 4.5% by mass, the content of 1,2-propanediol was changed to 12.0% by mass, and the content of 1,3-propanediol was changed to 9.5% by mass. The glass transition temperature (Tg) of the obtained [Clear Ink G] was measured in the same manner as for [Clear Ink A], and was found to be 55°C and -4°C. The volume-average particle size was also measured in the same manner as for [Clear Ink A], and was found to be 45 nm. The resin solid content in the obtained clear ink was 9% by mass. The composition of the obtained [Clear Ink G] is shown in Table 6 below.

[0233] (Example of clear ink preparation 8) Clear Ink H was obtained in the same manner as in Clear Ink Preparation Example 1, except that the resin particles were changed to [Resin Emulsion 1] 1.0% by mass and [Resin Emulsion 2] 29.0% by mass, the organic solvent represented by general formula (1) was changed to Equamid B100 10.0% by mass, the content of 1,2-propanediol was changed to 9.0% by mass, and the content of 1,3-propanediol was changed to 5.5% by mass. The glass transition temperature (Tg) of the obtained [Clear Ink H] was measured in the same manner as for [Clear Ink A], and was found to be 55°C and -4°C. The volume-average particle size was also measured in the same manner as for [Clear Ink A], and was found to be 45 nm. The resin solid content in the obtained clear ink was 9% by mass. The composition of the obtained [Clear Ink H] is shown in Table 6 below.

[0234] (Example of clear ink preparation 9) Clear Ink I was obtained in the same manner as in Clear Ink Preparation Example 1, except that the resin particles were changed to [Resin Emulsion 1] 1.0% by mass and [Resin Emulsion 2] 29.0% by mass, the organic solvent represented by general formula (1) was changed to Equamid M100 20.0% by mass, the content of 1,2-propanediol was changed to 2.5% by mass, the content of 1,3-propanediol was changed to 1.5% by mass, and the content of 1,2-butanediol was changed to 1.0% by mass. The glass transition temperature (Tg) of the obtained [Clear Ink I] was measured in the same manner as for [Clear Ink A], and was found to be 53°C and -4°C. The volume-average particle size was also measured in the same manner as for [Clear Ink A], and was found to be 45 nm. The resin solid content in the obtained clear ink was 9% by mass. The composition of the obtained [Clear Ink I] is shown in Table 6 below.

[0235] (Example of clear ink preparation 10) Clear Ink J was obtained in the same manner as in Clear Ink Preparation Example 1, except that the resin particles were changed to [Resin Emulsion 1] 3.0% by mass and [Resin Emulsion 3] 27.0% by mass, and the 1,2-propanediol content was changed to 15.5% by mass. The glass transition temperature (Tg) of the obtained [Clear Ink J] was measured in the same manner as for [Clear Ink A], and was found to be 45°C and -3°C. The volume-average particle size was also measured in the same manner as for [Clear Ink A], and was found to be 41 nm. The resin solid content in the obtained clear ink was 9% by mass. The composition of the obtained [Clear Ink J] is shown in Table 7 below.

[0236] (Example of clear ink preparation 11) Clear Ink K was obtained in the same manner as in Clear Ink Preparation Example 1, except that the resin particles were changed to [Resin Emulsion 2] at 30.0% by mass, the organic solvent represented by general formula (1) was changed to Equamid M100 at 3.5% by mass, and the content of 1,2-propanediol was changed to 12.5% ​​by mass. The glass transition temperature (Tg) of the obtained [Clear Ink K] was measured in the same manner as for [Clear Ink A] and was found to be 55°C. The volume-average particle size was also measured in the same manner as for [Clear Ink A] and was found to be 44 nm. The resin solid content in the obtained clear ink was 9% by mass. The composition of the obtained [Clear Ink K] is shown in Table 7 below.

[0237] (Example of clear ink preparation 12) Clear Ink L was obtained in the same manner as in Clear Ink Preparation Example 1, except that the resin particles were changed to [Resin Emulsion 1] 3.0% by mass and [Resin Emulsion 4] 27.0% by mass, and the 1,2-propanediol content was changed to 13.5% by mass. The glass transition temperature (Tg) of the obtained [Clear Ink L] was measured in the same manner as for [Clear Ink A], and was found to be 55°C and -4°C. The volume-average particle size was also measured in the same manner as for [Clear Ink A], and was found to be 56 nm. The resin solid content in the obtained clear ink was 9% by mass. The composition of the obtained [Clear Ink L] is shown in Table 7 below.

[0238] (Example of clear ink preparation 13) Clear Ink M was obtained in the same manner as in Clear Ink Preparation Example 1, except that the resin particles were changed to [Resin Emulsion 1] 1.0% by mass and [Resin Emulsion 2] 29.0% by mass, the organic solvent represented by general formula (1) was omitted, the content of 1,2-propanediol was changed to 16.5% by mass, and the content of 1,3-propanediol was changed to 11.0% by mass. The glass transition temperature (Tg) of the obtained [Clear Ink M] was measured in the same manner as for [Clear Ink A], and was found to be 55°C and -4°C. The volume-average particle size was also measured in the same manner as for [Clear Ink A], and was found to be 45 nm. The resin solid content in the obtained clear ink was 9% by mass. The composition of the obtained [Clear Ink M] is shown in Table 7 below.

[0239] [Table 6]

[0240] [Table 7]

[0241] (Examples 1-24 and Comparative Examples 1-12) Printing was performed using an inkjet printing apparatus (applicant name: modified IPSiO GXe5500, manufactured by Ricoh Co., Ltd.) which has an ink storage means in which each of the combinations of primers A to T, color inks A to D, and clear inks A to M listed in Tables 8 to 10 below is independently filled; an ejection means having a nozzle forming surface for ejecting each ink from a nozzle; a lid member covering the nozzle forming surface; and a supply means for supplying each ink from the ink storage means to the ejection means. First, the amount of primer applied to the polyvinyl chloride sheet (GIY-11Z5, manufactured by Lintec Corporation, hereinafter sometimes referred to as "PVC sheet") as the base material (hereinafter sometimes referred to as "recording medium") is 4.2 g / m². 2 A plain image of the primer (primer layer) was formed in this manner. Within 10 minutes or more after the formation of the primer layer, the amount of the primer layer is 10 g / m². 2 A solid image (color ink layer) of the aforementioned color ink was formed in this manner. After the formation of the color ink layer, it was dried at 80°C for 3 minutes. For a recording medium having at least the color ink layer after drying, the amount applied is 10 g / m². 2 The clear ink was applied in such a manner to form an 80% halftone image (overcoat layer). After the formation of the overcoat layer, it was dried at 80°C for 3 minutes to obtain the recorded material.

[0242] Examples 1-24 and Comparative Examples 1-12 were evaluated for "drying properties," "beading resistance (primer layer)," "beading resistance (color ink layer)," "glossiness," "adhesion," "scratch resistance (500 cycles)," and "scratch resistance (1,000 cycles)" using the following methods. The evaluation results are shown in Tables 8-10 below.

[0243] <Drying> The surface dryness of the obtained recordings was observed, and the dryness was evaluated based on the following evaluation criteria. A rating of "B" or higher is considered to be within the range of usable performance. [Evaluation Criteria] A: The surface is dry and has no tackiness when touched. B: The surface has a slight tackiness to the touch, but the ink on the surface does not bleed through to the other side. C: Ink transfer may occur on the surface, causing changes in gloss and image on the touched area.

[0244] <Beading resistance (adhesion)> The presence or absence of beading in solid images of the primer alone and solid images of the ink formed on a PVC sheet was visually observed, and the "beading resistance (primer layer)" and "beading resistance (color ink layer)" were evaluated based on the following evaluation criteria. A beading resistance evaluation result of A or higher is desirable for practical use. Here, beading refers to the phenomenon where irregular gaps, increased density, etc., occur due to adjacent dots connecting on the recording medium, resulting in impaired image quality. Furthermore, for Comparative Example 9, in which the "drying properties" evaluation results were not within a practical range, evaluations of "beading resistance (primer layer)" and "beading resistance (color ink layer)" were not performed. [Evaluation Criteria] A: There was no beading at all. B: There was slight beading. C: There was beading.

[0245] <Glossiness (Image Glossiness)> The 60° gloss of the solid image of the obtained recording was measured four times using a gloss meter (BYK Gardener, 4501), and the average gloss value was calculated. The "glossiness" was then evaluated based on the following evaluation criteria. A rating of "B" or higher is desirable for practical use. Furthermore, for Comparative Example 9, where the "drying properties" evaluation result was not within a practical range, the "glossiness" evaluation was not performed. [Evaluation Criteria] A: The average gloss value is 90 or higher. B: Average gloss value is between 80 and 90 C: Average gloss value is less than 80

[0246] <Adhesion> The obtained recording material was subjected to a grid-pattern peel test using cloth adhesive tape (Nichiban Co., Ltd., 123LW-50). The number of remaining squares in 100 test squares was counted, and the "adhesion" to the recording medium was evaluated based on the following evaluation criteria. An evaluation of "B" or higher is desirable for practical use. Furthermore, for Comparative Example 9, where the evaluation results for "drying properties" were not within a practical range, the evaluation of "adhesion properties" was not performed. [Evaluation Criteria] A: Number of remaining squares is 90 or more B: Number of remaining squares is 70 or more but less than 90. C: Number of remaining squares is less than 70

[0247] <Abrasion resistance> The obtained records were placed in a Japan Society for the Promotion of Science (JSPS) type abrasion tester (Friction Tester Type II) (device name: Dyed Material Friction Fastness Tester AR-2(BC), manufactured by Intec Co., Ltd.), and a friction element (load: 500g) with a white cotton cloth (JIS L 0803 compliant, attached white cloth for dye fastness testing, Kanakin No. 3) attached to the contact part was rubbed back and forth 500 or 1,000 times on the surface of the records. After that, the dried film of the records was visually inspected, and the "abrasion resistance (500 times)" and "abrasion resistance (1,000 times)" were evaluated based on the evaluation criteria below. In the evaluation, a score of "3" or higher for "abrasion resistance (500 times)" and a score of "2" or higher for "abrasion resistance (1,000 times)" is considered to be within the range of practical use. Furthermore, for Comparative Examples 1 to 5 and 9, where the evaluation results for any of the above-mentioned "drying properties," "beading resistance," "image gloss," and "adhesion" are not within a practical range, the evaluations for "scratch resistance (500 times)" and "scratch resistance (1,000 times)" were not performed. For Comparative Example 10, where the evaluation result for "scratch resistance (500 times)" is not within a practical range, the evaluation for "scratch resistance (1,000 times)" was not performed. [Evaluation Criteria] 5: No signs of rubbing are visible. 4: Upon closer inspection, slight scuff marks can be seen. 3: Upon closer inspection, changes in color and gloss can be seen in the rubbed areas. 2: Even when viewed from a distance, the color and gloss changes of the rubbed area are visible. 1: Part of the skin on the media is exposed.

[0248] [Table 8]

[0249] [Table 9]

[0250] [Table 10]

[0251] Examples of the present invention are as follows: <1> A primer application step in which a primer is applied to a non-permeable substrate, A color ink application step of applying color ink to the area to which the primer has been applied, A clear ink application step of applying clear ink to at least the area to which the color ink has been applied, A printing method having at least the following: The primer comprises a cationic resin, a polyvalent metal salt, and a diethylene glycol alkyl ether-based organic solvent. The aforementioned color ink contains resin particles having a glass transition temperature (Tg) of less than 0°C, and an organic solvent represented by the following general formula (1). The printing method is characterized in that the clear ink comprises resin particles having a volume-average particle size of 50 nm or less, and an organic solvent represented by the following general formula (1), and the dried film of the clear ink has a glass transition temperature (Tg) of 50°C or higher and below 0°C. [ka] (However, in the above general formula (1), R 1 (This represents an alkyl group with 1 to 4 carbon atoms.) <2> The content of the diethylene glycol alkyl ether-based organic solvent is 5.0% by mass or more and 30.0% by mass or less relative to the primer, <1> This is the printing method described. <3> The diethylene glycol alkyl ether-based organic solvent is diethylene glycol diethyl ether. <1> from <2> This is the printing method described in one of the following. <4> The content of the diethylene glycol diethyl ether in the primer is 15.0% by mass or more. <3> This is the printing method described. <5> The polyvalent metal salt is magnesium acetate, <1> from <2> This is the printing method described in one of the following. <6> The content of the cationic resin in the primer is 2.0% by mass or more and 15.0% by mass or less. <1> from <2> This is the printing method described in one of the following. <7> The resin particles contained in the clear ink include resin particles A having a glass transition temperature of 50°C or higher and resin particles B having a glass transition temperature of less than 0°C. <1> from <2> This is the printing method described in one of the following. <8> The mass (M) of the resin particle A A ) and the mass of the resin particles B (M B ) and the mass ratio (M A :M B ) is 98:2 to 80:20, as mentioned above <7> This is the printing method described. <9> The resin particle content in the clear ink is 10% by mass or more. <1> from <2> This is the printing method described in one of the following. <10> A primer-applying means for applying a primer containing a cationic resin, a polyvalent metal salt, and a diethylene glycol alkyl ether-based organic solvent onto a non-permeable substrate, A color ink application means for applying a color ink containing resin particles having a glass transition temperature (Tg) of less than 0°C and an organic solvent represented by the following general formula (1) to the region to which the primer has been applied, A clear ink application means for applying a clear ink to at least the region to which the color ink has been applied, the clear ink comprising resin particles having a volume-average particle size of 50 nm or less, and an organic solvent represented by the following general formula (1), wherein the dry film has a glass transition temperature (Tg) of 50°C or higher and less than 0°C. A printing apparatus characterized by having at least one of the following. [ka] (However, in the above general formula (1), R 1 (This represents an alkyl group with 1 to 4 carbon atoms.)

[0252] The aforementioned <1> from <9> The printing method described in any of the above, and the <10> The printing apparatus described herein can solve the problems of the past and achieve the objectives of the present invention. [Explanation of symbols]

[0253] 100 Printing equipment 110 Primer application section 120 Ink application unit 130 Clear ink application section 140 Drying section 150 Conveying section M recording medium 400 Image forming apparatus 401 Exterior 401c cover 404 Cartridge Holder 410, 410k, 410c, 410m, 410y main tank 411 Ink reservoir 413 Ink outlet 414 containment container 420 Mechanism Department 434 Discharge head 436 Supply Tube L Ink container [Prior art documents] [Patent Documents]

[0254] [Patent Document 1] Japanese Patent Publication No. 2018-035270

Claims

1. A primer application step in which a primer is applied to a non-permeable substrate, A color ink application step of applying color ink to the area to which the primer has been applied, A clear ink application step of applying clear ink to at least the area to which the color ink has been applied, A printing method having at least the following: The primer comprises a cationic resin, a polyvalent metal salt, and a diethylene glycol alkyl ether-based organic solvent. The aforementioned color ink contains resin particles having a glass transition temperature (Tg) of less than 0°C, and an organic solvent represented by the following general formula (1). A printing method characterized in that the clear ink comprises resin particles having a volume-average particle size of 50 nm or less, and an organic solvent represented by the following general formula (1), and the dried film of the clear ink has a glass transition temperature (Tg) of 50°C or higher and below 0°C. 【Chemistry 1】 (However, in the above general formula (1), R １ (This represents an alkyl group with 1 to 4 carbon atoms.)

2. The printing method according to claim 1, wherein the content of the diethylene glycol alkyl ether-based organic solvent is 5.0% by mass or more and 30.0% by mass or less relative to the primer.

3. The printing method according to any one of claims 1 to 2, wherein the diethylene glycol alkyl ether-based organic solvent is diethylene glycol diethyl ether.

4. The printing method according to claim 3, wherein the content of the diethylene glycol diethyl ether in the primer is 15.0% by mass or more.

5. The printing method according to any one of claims 1 to 2, wherein the polyvalent metal salt is magnesium acetate.

6. The printing method according to any one of claims 1 to 2, wherein the content of the cationic resin in the primer is 2.0% by mass or more and 15.0% by mass or less.

7. The printing method according to any one of claims 1 to 2, wherein the resin particles contained in the clear ink include resin particles A having a glass transition temperature of 50°C or higher and resin particles B having a glass transition temperature of less than 0°C.

8. The mass (M) of the resin particle A Ａ ) and the mass of the resin particles B (M Ｂ ) and the mass ratio (M Ａ : M Ｂ The printing method according to claim 7, wherein the ratio is 98:2 to 80:

20.

9. The printing method according to any one of claims 1 to 2, wherein the resin particle content in the clear ink is 10% by mass or more.

10. A primer-applying means for applying a primer containing a cationic resin, a polyvalent metal salt, and a diethylene glycol alkyl ether-based organic solvent onto a non-permeable substrate, A color ink application means for applying a color ink containing resin particles having a glass transition temperature (Tg) of less than 0°C and an organic solvent represented by the following general formula (1) to the region to which the primer has been applied, A clear ink application means for applying a clear ink to at least the region to which the color ink has been applied, the clear ink comprising resin particles having a volume-average particle size of 50 nm or less, and an organic solvent represented by the following general formula (1), wherein the dry film has a glass transition temperature (Tg) of 50°C or higher and less than 0°C. A printing apparatus characterized by having at least one of the following. 【Chemistry 2】 (However, in the above general formula (1), R １ (This represents an alkyl group with 1 to 4 carbon atoms.)

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