JP2022034515A - Printing method, printer, and printed matter - Google Patents

Abstract

To provide a printing method that can prevent the bleeding of ink in a printing object that is porous one, and can achieve high image density.SOLUTION: A printing method includes a process liquid imparting step for imparting a process liquid containing silica and polyvalent metal salts to a printing object having a Cobb water absorbency of 20 g/m2 or more and 75 g/m2 or less after contact with water for 120 seconds, defined in JIS-P8140, and an ink application step for applying ink containing a colorant and water to the printing object.SELECTED DRAWING: None

Description

The present invention relates to a printing method, a printing apparatus, and a printed matter.

In recent years, inkjet printers have been developed not only for household use but also for packaging materials such as foods, beverages, and daily necessities. Examples of printed matter in packaging applications include corrugated cardboard.

The method of printing on corrugated board is to record an image on corrugated board base paper (front liner paper) with printing ink and then bond the core and back liner paper with a corrugator machine to manufacture corrugated board (pre-print method). It is roughly divided into a method of recording an image with printing ink on the surface liner paper of corrugated cardboard that has already been bonded (post-print method).

Conventionally, offset printing, flexographic printing, gravure printing, etc. have been used for printing on cardboard, but all of them are printing methods in which a plate or blanket is brought into contact with a printing medium and printing pressure is applied to transfer the ink. Therefore, in the post-printing method, density unevenness is likely to occur due to the influence of unevenness (flute grain) on the surface of the cardboard, and it is particularly difficult to post-print on thick cardboard. On the other hand, although the preprint method solves the problem in printing, there is a problem that it cannot cope with a short delivery time because the bonding process after printing takes time and the box making process cannot be started immediately after printing.

On the other hand, inkjet printing is a non-contact method of recording images on a printing medium, so post-print printing on thick corrugated cardboard is easy, and the box-making process can be started immediately after printing, resulting in a short delivery time. Demand for inkjet printing in corrugated cardboard printing is increasing because it can be handled.

However, in corrugated cardboard printing, conventional water-based inkjet printing has quality problems such as low density and bleeding (bleeding), and cannot sufficiently meet the quality requirements such as high density and high resolution from consumers.

Corrugated board base paper (liner paper) is attached to the printed surface of corrugated cardboard, but general corrugated board base paper has no or insufficient ink receiving layer, and is more porous than coated paper for offset printing. There is a feature. In particular, the water-based inkjet ink, which is a low-viscosity printing ink, has a problem that it easily permeates and diffuses into the corrugated board base paper, cannot develop a sufficient printing density, and easily causes bleeding of an image.

Therefore, for example, a liner paper provided with an ink receiving layer has been proposed (see, for example, Patent Document 1).
Further, a method of applying a treatment liquid containing a polyvalent metal salt has been proposed for the purpose of improving the image quality and resistance of the inkjet ink (see, for example, Patent Document 2).

An object of the present invention is to provide a printing method capable of preventing ink bleeding in a porous printed matter and achieving a high image density.

The printing method of the present invention as a means for solving the above-mentioned problems is a printed matter having a Cobb water absorption of 20 g / m ² or more and 75 g / m ² or less at a contact time of 120 seconds with water specified in JIS-P8140. Includes a treatment liquid application step of applying a treatment liquid containing silica and a polyvalent metal salt, and an ink application step of applying an ink containing a coloring material and water.

According to the present invention, it is possible to provide a printing method capable of preventing ink bleeding in a porous printed matter and achieving a high image density.

FIG. 1 is a schematic view showing an example of a method of printing on corrugated cardboard by a preprint method. FIG. 2 is a schematic view showing an example of a method of printing on corrugated cardboard by a post-printing method. 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.

(Printing method and printing equipment)
In the printing method of the present invention, silica and a polyvalent metal salt are contained in a printed matter having a Cobb water absorption of 20 g / m ² or more and 75 g / m ² or less at a contact time of 120 seconds with water specified in JIS-P8140. It includes a treatment liquid application step of imparting a treatment liquid and an ink application step of applying an ink containing a coloring material and water, and preferably includes a drying step, and further includes other steps as necessary.

The printing apparatus of the present invention contains silica and a polyvalent metal salt in a printed matter having a Cobb water absorption of 20 g / m ² or more and 75 g / m ² or less at a contact time of 120 seconds with water specified in JIS-P8140. It has a treatment liquid applying means for imparting a processing liquid and an ink applying means for applying an ink containing a coloring material and water, preferably having a drying means, and further having other means as necessary. ..

The printing method of the present invention can be suitably carried out by the printing apparatus of the present invention, the treatment liquid application step can be performed by the treatment liquid application means, the ink application step can be performed by the ink application means, and drying. The step can be carried out by drying means, and the other steps can be carried out by other means.

In the prior art described in Patent Document 1, a corrugated board base paper (liner paper) provided with an ink receiving layer is proposed, but a wide variety of corrugated cardboards on the market cannot be used, and the versatility is high. Not enough.
Further, in the prior art described in Patent Document 2, a method of applying a treatment liquid containing a polyvalent metal salt is proposed for the purpose of improving the image quality and durability of the inkjet ink, but the corrugated cardboard base paper (printed matter) is proposed. When liner paper) is used, there is a problem that the density color development and the bleed resistance are not sufficient.

In the present invention, silica and a polyvalent metal salt are contained in a printed matter having a Cobb water absorption of 20 g / m ² or more and 75 g / m ² or less at a contact time of 120 seconds with water specified in JIS-P8140. By applying the treatment liquid to be applied, the polyvalent metal salt as a coagulant stays on the surface layer due to silica, the ink can be prevented from settling, and a printed matter having excellent color development and bleed resistance can be obtained.
Further, even when a corrugated cardboard base paper (liner paper) is used as the printed matter, it is possible to obtain a printed matter having excellent density color development and bleed resistance.

<Treatment liquid application process and treatment liquid application means>
In the treatment liquid application step, silica and a polyvalent metal salt are contained in a printed matter having a Cobb water absorption of 20 g / m ² or more and 75 g / m ² or less at a contact time of 120 seconds with water specified in JIS-P8140. It is a step of applying the treatment liquid, and is carried out by the treatment liquid application means.

<< Treatment liquid >>
The treatment liquid is applied to the printed matter before the ink is applied to the printed matter. The treatment liquid may be referred to as a "pretreatment liquid" or a "precoat liquid".

The treatment liquid contains silica and a polyvalent metal salt, preferably contains a resin, and further contains other components, if necessary.

The viscosity of the treatment liquid may be adjusted at 25 ° C. in the range of 5 mPa · s or more and 1,000 mPa · s or less depending on the coating method, and such a viscosity may be adjusted, for example, by a rotary viscometer (Toki). RE-80L) manufactured by Sangyo Co., Ltd. can be used. As the measurement conditions, it is possible to measure at 25 ° C. with a standard cone rotor (1 ° 34'× R24), a sample liquid volume of 1.2 mL, a rotation speed of 50 rpm, and 3 minutes. When the viscosity of the treatment liquid at 25 ° C. is 5 mPa · s or more and 200 mPa · s or less, the coating on the printed matter becomes more uniform, and as a result, the ink coating tends to be uniform and even, which is preferable. ..

The method for applying the treatment liquid is not particularly limited and may be appropriately selected depending on the intended purpose. For example, an inkjet method, a blade coating method, a gravure coating method, a gravure offset coating method, a bar coating method, and a roll coating method can be selected. Method, knife coat method, air knife coat method, comma coat method, U comma coat method, AKKU coat method, smoothing coat method, micro gravure coat method, reverse roll coat method, 4 roll coat method, 5 roll coat method, dip Examples include a coat method, a curtain coat method, a slide coat method, and a die coat method. The coating method can be appropriately selected depending on the material, thickness, etc. of the printed matter.

The amount of the treatment liquid to be applied is preferably 2 g / m ² or more and 30 g / m ² or less, and more preferably 5 g / m ² or more and 20 g / m ² or less, in terms of the amount of solid content applied to the printed matter.

-silica-
As the silica, vapor phase silica, wet silica synthesized by a precipitation method, a sol-gel method, or the like, colloidal silica, or the like can be used.

In the present invention, by applying a treatment liquid containing silica to a printed matter, a silica layer formed near the surface layer of the printed matter suppresses concentration reduction and bleeding due to ink permeation absorption, and is of high quality. Printed matter can be obtained.

Silica is in the form of particles, and the particle size of silica may be as long as the treatment liquid can be applied to the object to be printed, the number average primary particle size is in the range of 5 nm or more and 40 nm or less, and the BET specific surface area is 30 m ² /. Silica in the range of g or more and 350 m ² / g or less can be preferably used, and silica having a BET specific surface area in the range of 35 m ² / g or more and 155 m ² / g or less is particularly preferable. The BET specific surface area of silica is preferably 30 m ² / g or more, and has excellent fixability to the corrugated cardboard surface layer, and is high, because the transparency of the treatment liquid can be increased and the appearance of the corrugated cardboard can be avoided from changing. The BET specific surface area is preferably 350 m ² / g or less from the viewpoint of obtaining an ink density.
The BET specific surface area of silica is a value measured by the Brunauer, Emmett, and Teller methods (BET method), and can be measured by a general gas adsorption method.
The number average primary particle size of silica can be measured, for example, by observation with a transmission electron microscope.

Specific examples of silica include AEROSIL50, 90G, 130, 200, 200V, 200CF, 200FAD, 300, 300CF, R972, R976, W7520 (manufactured by Nissan Aerosil Co., Ltd.) as the vapor phase silica. The SYLOJET series (manufactured by GRACE DAVISON) and the like, and the colloidal silica includes the Snowtex series (manufactured by Nissan Chemical Industries, Ltd.). These may be used alone or in combination of two or more.

As the silica, hydrophilic silica and hydrophobic silica treated with dimethylcyclolosilane or the like can be used regardless of the presence or absence of surface treatment, but when hydrophobic silica is used, for example, 1,2-propanediol or the like can be used. It is more preferable to use hydrophilic silica having excellent water dispersibility because it is necessary to disperse it in an organic solvent in advance and it may be restricted in formulation.

The amount of silica applied to the printed matter is preferably 0.02 g / m ² or more and 0.8 g / m ² or less, and 0.04 g / m ² or more and 0.6 g / m ² or less. The following are more preferable. The silica adhesion amount is preferably 0.02 g / m ² or more from the viewpoint of obtaining high ink density and bleeding prevention effect, and 0.8 g / m from the viewpoint of avoiding change in the appearance of corrugated cardboard as a printed matter. ² or less is preferable.

The content of silica in the treatment liquid is not particularly specified as long as the amount of silica adhered to the printed matter satisfies the above range and can be suitably applied to the surface of the printed matter, but the content of silica in the treatment liquid is not specified. Is preferably 0.3% by mass or more and 6% by mass or less, and more preferably 0.4% by mass or more and 5% by mass or less. The silica concentration is preferably 0.3% by mass or more from the viewpoint of obtaining a high ink concentration and bleeding prevention effect, and 6% by mass or less from the viewpoint of suppressing an increase in the viscosity of the treatment liquid and enabling good coating. preferable.

-Multivalent metal salt-
The polyvalent metal salt has a function of destabilizing the dispersion of the coloring material in the ink, and promptly aggregates the pigment in the ink after dripping, suppresses color bleeding, and improves color development. be able to.

The cation in the polyvalent metal salt is not particularly limited and may be appropriately selected depending on the intended purpose. For example, aluminum (Al (III)), calcium (Ca (II)), magnesium (Mg (II)). )), Copper (Cu (II)), Iron (Fe (II) or Fe (III)), Zinc (Zn (II)), Tin (Sn (II) or Sn (IV)), Yttrium (Sr (II)) )), Nickel (Ni (II)), Cobalt (Co (II)), Yttrium (Ba (II)), Lead (Pb (II)), Zirconium (Zr (IV)), Titanium (Ti (IV)) , Antimon (Sb (III)), Bismus (Bi (III)), Tantal (Ta (V)), Arsenic (As (III)), Cerium (Ce (III)), Lantern (La (III)), Yttrium Examples thereof include ions such as (Y (III)), mercury (Hg (II)), and yttrium (Be (II)). These may be used alone or in combination of two or more. Among these, calcium (Ca (II)) and magnesium (Mg (II)) are preferable.

The anion in the polyvalent metal salt is not particularly limited and may be appropriately selected depending on the intended purpose. For example, fluorine (F), chlorine (Cl), bromine (Br), iodine (I) and the like can be selected. Halogen element ions; Nitrate ion (NO _3- ), ^Sulfate ion ( ^{SO 4-2} ₎ ; Organic carboxylic acid ions such as formic acid, acetic acid, lactic acid, malonic acid, oxalic acid, maleic acid, benzoic acid; benzenesulphonic acid , Naftor sulphonic acid, organic sulphonic acid ions such as alkylbenzene sulphonic acid; ^{thiosian ion (SCN-, thiosulfate ion S 2 O 3-2-), phosphate ion (PO 4-3- ) ,} _{nitrite ion (} NO ^2- ) ) And so on. These may be used alone or in combination of two or more. Among these, chloride ion (Cl ⁻ ), sulfate ion (SO _4-2 ) _{, and acetate ion nitrate ion (NO 3-} ^{) are} preferable from the viewpoint of cost and safety.

The polyvalent metal salt is not particularly limited and may be appropriately selected depending on the intended purpose. For example, aluminum chloride, calcium chloride, nickel chloride, potassium acetate, sodium acetate, calcium acetate, magnesium acetate, aluminum nitrate, etc. Examples thereof include magnesium nitrate, magnesium chloride, calcium nitrate, magnesium hydroxide, aluminum sulfate, magnesium sulfate, and ammonium alum. More specifically, calcium acetate monohydrate, calcium nitrate tetrahydrate, calcium chloride hexahydrate, magnesium acetate tetrahydrate, magnesium sulfate (anhydrous), aluminum nitrate 9 hydrate, nickel chloride 6 Examples include hydrates. These may be used alone or in combination of two or more. Among these, calcium acetate monohydrate, calcium nitrate tetrahydrate, calcium chloride hexahydrate, magnesium acetate tetrahydrate, and magnesium sulfate (anhydrous) are preferable.

The content of the polyvalent metal salt is preferably 1% by mass or more and 25% by mass or less, more preferably 3% by mass or more and 20% by mass or less, and 5% by mass or more and 12% by mass or less with respect to the total amount of the treatment liquid. More preferred. It is preferably 1% by mass or more from the viewpoint of being able to suppress color bleeding satisfactorily, and is preferably 25% by mass or less from the viewpoint of high stability when stored and suppressing the occurrence of quality defects such as precipitation.

-resin-
The treatment liquid may contain a resin. The type of resin can be used without particular limitation, but is at least one selected from acrylic resin, polyolefin resin, polyvinyl acetate resin, polyvinyl chloride resin, urethane resin, and copolymers thereof. This is preferable because strong adhesion to various printed materials can be obtained.
When the resin is added to the treatment liquid, the resin particles may be added as a liquid dispersed in water. A commercially available resin may be used as the resin emulsion.
The volume average particle size of the resin particles is not particularly limited and may be appropriately selected depending on the intended purpose, but is 10 nm or more and 1,000 nm or less from the viewpoint of obtaining good dispersibility, fixability and high image hardness. It is preferably 10 nm or more and 200 nm or less, and particularly preferably 10 nm or more and 100 nm or less.
The volume average particle size can be measured using, for example, a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrac Bell Co., Ltd.).

Considering the compatibility and stability when mixed with the polyvalent metal salt, the acid value of the resin is preferably 20 mgKOH / g or less.

The glass transition temperature (Tg) of the resin may be such that the adhesion to the printed matter and the drying property can be maintained, and for example, a resin in the range of −25 ° C. or higher and 70 ° C. or lower can be preferably used. Tg is preferably -25 ° C or higher from the viewpoint of suppressing stickiness on the surface of the printed matter and blocking when stacked, to maintain adhesion and to prevent cracking and peeling during bending in the box making process. , Tg is preferably 70 ° C. or lower. In particular, when corrugated cardboard is used as the printed matter, a suitable effect can be obtained.

The content of the resin is preferably 30% by mass or less, more preferably 0.5% by mass or more and 20% by mass or less, based on the total amount of the treatment liquid. The content indicates the mass% of the resin solid content contained in the treatment liquid. When the content is 30% by mass or less, the thickness of the resin after coating the treatment liquid does not become too thick, the occurrence of blocking and the change in the appearance of corrugated cardboard are suppressed, and the effect of the polyvalent metal salt is obtained. Is preferable because it is fully exhibited.

-Other ingredients-
Examples of other components include organic solvents, water, surfactants, antifoaming agents, antiseptic and antifungal agents, rust preventives, pH adjusters and the like.

--Organic solvent--
The organic solvent used in the present invention is not particularly limited, and a water-soluble organic solvent can be used. Examples thereof include ethers such as polyhydric alcohols, polyhydric alcohol alkyl ethers and polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines and sulfur-containing compounds.
Examples of the water-soluble organic solvent include ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, and 2, , 3-Butandiol, 3-Methyl-1,3-Butanediol, Triethyleneglycol, Polyethylene glycol, Polypropylene glycol, 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 -Polyhydric alcohols such as pentanediol and petriol; such as 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. Polyvalent alcohol alkyl ethers; Polyvalent alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether; 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1, Nitrogen-containing heterocyclic compounds such as 3-dimethyl-2-imidazolidinone, ε-caprolactam, γ-butyrolactone; formamide, N-methylformamide, N, N-dimethylformamide, 3-methoxy-N, N-dimethylpropionamide. , 3-Butoxy-N, N-dimethylpropionamide and other amides; amines such as monoethanolamine, diethanolamine and triethylamine; sulfur-containing compounds such as dimethylsulfoxide, sulfolane and thiodiethanol; propylene carbonate, ethylene carbonate and the like. Be done.
It is preferable to use an organic solvent having a boiling point of 250 ° C. or lower because it not only functions as a wetting agent but also has good drying properties.

The content of the organic solvent in the treatment liquid is not particularly limited and may be appropriately selected depending on the intended purpose. However, considering the suitability for coating on the printed matter, uniform dispersibility, drying property, etc., 5% by mass or more. 90% by mass or less is preferable, and 10% by mass or more and 70% by mass or less is more preferable.

--water--
The water is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include ion-exchanged water, ultra-filtered water, reverse osmosis water, pure water such as distilled water, and ultrapure water. These may be used alone or in combination of two or more. There is no particular limitation on the content of water in the treatment liquid, and it is sufficient that the content is sufficient so that the polyvalent metal salt does not precipitate when stored at room temperature.

--Surfactant ---
Surfactants can reduce the surface tension of the treatment liquid, improve the wettability to various printed materials, and apply uniformly, and silica and polyvalent metal salts contained in the treatment liquid can be applied onto the printed material. It has the effect of being able to be evenly distributed.

As the surfactant, any of a silicone-based surfactant, a fluorine-based surfactant, an amphoteric surfactant, a nonionic surfactant, and an anionic surfactant can be used.
The silicone-based surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. Among them, those that do not decompose even at high pH are preferable, and examples thereof include side chain modified polydimethylsiloxane, double-ended modified polydimethylsiloxane, single-ended modified polydimethylsiloxane, side chain double-ended modified polydimethylsiloxane, and the like. Those having an oxyethylene group and a polyoxyethylene polyoxypropylene group are particularly preferable because they exhibit good properties as an aqueous surfactant. Further, as the silicone-based surfactant, a polyether-modified silicone-based surfactant can also be used, and examples thereof include a compound in which a polyalkylene oxide structure is introduced into the Si portion side chain of dimethylpolysiloxane.

Examples of the fluorine-based surfactant include a perfluoroalkyl sulfonic acid compound, a perfluoroalkyl carboxylic acid compound, a perfluoroalkyl phosphate ester compound, a perfluoroalkyl ethylene oxide adduct, and a perfluoroalkyl ether group in the side chain. Polyoxyalkylene ether polymer compounds are particularly preferred because they have low foaming properties. Examples of the perfluoroalkyl sulfonic acid compound include perfluoroalkyl sulfonic acid and perfluoroalkyl sulfonic acid salt. Examples of the perfluoroalkylcarboxylic acid compound include perfluoroalkylcarboxylic acid and perfluoroalkylcarboxylic acid salt. The polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain includes a sulfate ester salt of a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in the side chain and a perfluoroalkyl ether group in the side chain. Examples thereof include salts of polyoxyalkylene ether polymers. The counter ions of the salts in these fluorine-based surfactants include Li, Na, K, NH ₄ , NH ₃ CH ₂ CH ₂ OH, NH ₂ (CH ₂ CH ₂ OH) ₂ , and NH (CH ₂ CH ₂ OH). ₃ and the like can be mentioned.
Examples of the amphoteric tenside include laurylaminopropionate, lauryl dimethyl betaine, stearyl dimethyl betaine, and lauryl dihydroxyethyl betaine.
Examples of the nonionic surfactant include polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl ester, polyoxyethylene alkyl amine, polyoxyethylene alkyl amide, polyoxyethylene propylene block polymer, sorbitan fatty acid ester, and polyoxyethylene sorbitan. Examples thereof include a fatty acid ester and an ethylene oxide adduct of acetylene alcohol.
Examples of the anionic surfactant include polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, lauryl salt, polyoxyethylene alkyl ether sulfate salt and the like.
These may be used alone or in combination of two or more.

The silicone-based surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. For example, side chain-modified polydimethylsiloxane, double-ended modified polydimethylsiloxane, one-ended modified polydimethylsiloxane, side. Examples thereof include polydimethylsiloxane modified at both ends of the chain. Among these, a polyether-modified silicone-based surfactant having a polyoxyethylene group and a polyoxyethylene polyoxypropylene group as modifying groups has good properties as an aqueous surfactant. Is particularly preferable because it shows.
As such a surfactant, an appropriately synthesized one may be used, or a commercially available product may be used. As commercially available products, for example, they can be obtained from Big Chemie Co., Ltd., Shin-Etsu Chemical Co., Ltd., Toray Dow Corning Silicone Co., Ltd., Nippon Emulsion Co., Ltd., Kyoeisha Chemical Co., Ltd., and the like.

The above-mentioned polyether-modified silicone-based surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a polyalkylene oxide structure represented by the following general formula (S-1) is dimethyl. Examples thereof include those introduced into the Si part side chain of polysiloxane.

（但し、前記一般式（Ｓ－１）中、ｍ、ｎ、ａ、及びｂは、それぞれ独立に、整数を表し、Ｒは、アルキレン基を表し、Ｒ’は、アルキル基を表す。）

(However, in the general formula (S-1), m, n, a, and b each independently represent an integer, R represents an alkylene group, and R'represents an alkyl group.)

Commercially available products can be used as the above-mentioned polyether-modified silicone-based surfactant, for example, KF-618, KF-642, KF-643 (all manufactured by Shin-Etsu Chemical Industry Co., Ltd.), EMALEX-SS-. 5602, SS-1906EX (all manufactured by Nippon Emulsion Co., Ltd.), FZ-2105, FZ-2118, FZ-2154, FZ-2161, FZ-2162, FZ-2163, FZ-2164 (all are Toray Dow). Examples thereof include Corning Silicone Co., Ltd.), BYK-33, BYK-387 (all manufactured by Big Chemie Co., Ltd.), TSF4440, TSF4452, and TSF4453 (all manufactured by Toshiba Silicon Co., Ltd.).

As the fluorine-based surfactant, a compound having 2 to 16 carbon atoms substituted with fluorine is preferable, and a compound having 4 to 16 carbon atoms substituted with fluorine is more preferable.
Examples of the fluorine-based surfactant include a perfluoroalkyl phosphate ester compound, a perfluoroalkylethylene oxide adduct, and a polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain.
Among these, the polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain is preferable because it has less foaming property, and is particularly represented by either the general formula (F-1) or the general formula (F-2). The fluorosurfactant to be used is preferable.

上記一般式（Ｆ－１）で表される化合物において、水溶性を付与するためにｍは０～１０の整数が好ましく、ｎは０～４０の整数が好ましい。

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

[General formula (F-2)]
C _n F _{2n +} -CH ₂ CH (OH) CH ₂ -O- (CH ₂ CH ₂ O) _a -Y
In the compound represented by the above general formula (F-2), Y is H or C _m F _{2 m + 1} and m is an integer of 1 to 6, or CH ₂ CH (OH) CH ₂ -C _m F _{2 m + 1} and m is An integer of 4 to 6 or an integer of C _p H _{2P + 1} and p is an integer of 1 to 19. n is an integer of 1 to 6. a is an integer of 4 to 14.

Commercially available products may be used as the above-mentioned fluorine-based surfactant. Examples of this commercially available product include Surflon S-111, S-112, S-113, S-121, S-131, S-132, S-141, and S-145 (all manufactured by Asahi Glass Co., Ltd.); Full Lard FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, FC-431 (all manufactured by Sumitomo 3M Co., Ltd.); Megafuck F-470, F -1405, F-474 (all manufactured by DIC Co., Ltd.); Zonyl TBS, FSP, FSA, FSN-100, FSN, FSO-100, FSO, FS-300, UR, Capstone FS-30, FS-31, FS-3100, FS-34, FS-35 (all manufactured by The Chemours Company); FT-110, FT-250, FT-251, FT-400S, FT-150, FT-400SW (all manufactured by The Chemours Company). , Neos Co., Ltd.), Polyfox PF-136A, PF-156A, PF-151N, PF-154, PF-159 (manufactured by Omniova), Unidyne DSN-403N (manufactured by Daikin Industries, Ltd.), etc. Among these, FS-3100, FS-34, FS-300 manufactured by The Chemours Co., Ltd.; Neos Co., Ltd. FT-110, FT-250, FT-251, FT-400S, FT-150, FT-400SW; Polyfox PF-151N manufactured by Omninova, and Unidyne DSN-403N manufactured by Daikin Industries Co., Ltd. are particularly preferable. ..

The content of the surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. However, from the viewpoint of excellent wettability and ejection stability and improvement of image quality, 0.001% by mass or more 5 It is preferably 0.05% by mass or less, and more preferably 0.05% by mass or more and 5% by mass or less.

－－Antifoaming agent －－
The defoaming agent is not particularly limited, and examples thereof include a silicone-based defoaming agent, a polyether-based defoaming agent, and a fatty acid ester-based defoaming agent. These may be used alone or in combination of two or more. Among these, a silicone-based defoaming agent is preferable because it has an excellent defoaming effect.

－－Preservatives and fungicides －－
The antiseptic and antifungal agent is not particularly limited, and examples thereof include 1,2-benzisothiazolin-3-one and the like.

--anti-rust--
The rust preventive is not particularly limited, and examples thereof include acidic sulfites and sodium thiosulfate.

--PH regulator ---
The treatment liquid in the present invention may contain a pH adjuster. The pH adjusting agent is not particularly limited, and examples thereof include amines such as diethanolamine and triethanolamine. The pH of the treatment liquid is preferably 7 to 12, more preferably 8 to 11, from the viewpoint of preventing corrosion of the metal member in contact with the liquid.

<< Printed matter >>
By applying the treatment liquid of the present invention, an excellent concentration is obtained in a printed matter having a Cobb water absorption of 20 g / m ² or more and 75 g / m ² or less at a contact time of 120 seconds with water specified in JIS-P8140. An ink printed matter having excellent color development and bleed resistance can be obtained. Even when a corrugated cardboard (liner paper) is used as the printed matter, it is possible to obtain an ink printed matter having preferably excellent density color development and excellent bleed resistance.

Here, as a method of printing on corrugated board, as shown in FIG. 1, after recording the image 11 on the corrugated board base paper (front liner paper 10) with printing ink, the core 12 and the back liner paper 13 are bonded together with a corrugator machine. (Pre-printing method) and, as shown in FIG. 2, a method of recording the image 11 with printing ink on the surface liner paper 10 of the bonded corrugated board (post-printing method). Broadly speaking, the present invention can be suitably used for any method.
Since the surface liner paper can be rolled into a roll, a printed matter of continuous paper can be used, and the preprint method is preferably used because it can be printed using a printing machine for continuous paper. Be done. The post-printing method is preferably used because it is easy to store the printed matter and it can be delivered directly to the customer after printing.

Corrugated cardboard is basically composed of three sheets of paper, a front liner paper, a core, and a back liner paper. The strength can be adjusted by changing the materials of the front liner paper, the core, and the back liner paper. For the core, there are standards with different wave heights, and the basic ones have standards of 5 mm and 3 mm. Further, there is also, for example, a corrugated cardboard "double-sided corrugated cardboard" having a five-sheet structure in which a plurality of cores are laminated, which can be used as a printed matter in the present invention.
INDUSTRIAL APPLICABILITY The present invention can be suitably printed on a surface liner paper by either a preprint method or a post print method. It is also possible to print on corrugated cardboard printed on the back side liner paper and printed on both sides.

Examples of the fiber material used for producing liner paper include bleached kraft pulp of broadleaf or softwood, unbleached kraft pulp of broadleaf or softwood, and sulfite pulp of broadleaf or softwood. In addition, virgin pulp such as chemically treated pulp, kenaf, hemp, reeds and other chemically treated pulp, gland pulp, chemi-grand pulp, semi-chemical pulp, corrugated cardboard, newspapers, magazines and leaflets. It is also possible to use used paper such as.

The corrugated board base paper (liner paper) has a Cobb water absorption of 20 g / m ² or more and 75 g / m ² or less at a contact time of 120 seconds with water specified in JIS-P8140, and is 23 g / m ² or more and 69 g / m. ² or less is preferable, and 35 g / m ² or more and 60 g / m ² or less is more preferable. When the water absorption of the Cobb is 20 g / m ² or more, an appropriate spread of the ink can be obtained and the ink is less likely to be repelled on the surface. Further, when the water absorption of the Cobb is 75 g / m ² or less, the fixing property of the ink is good and the occurrence of bleeding can be prevented.
The Cobb water absorption degree is the Cobb water absorption degree at a contact time of 120 seconds with water specified in JIS-P8140. For example, a cylinder is set on a cardboard base paper (test piece) having a contact area with water of 100 cm ² . Pour 100 mL of water with the base paper and cylinder sandwiched between clamps so that water does not leak, discard the water after 120 seconds of contact time, quickly remove excess water on the base paper with absorbent paper, and weigh the change in weight of the base paper. By doing so, it can be measured.

The paper density of the corrugated board (liner paper) is preferably 100 g / m ² or more and 400 g / m ² or less, and more preferably 150 g / m ² or more and 300 g / m ² or less from the viewpoint of bonding suitability by a corrugator machine.

<Ink applying process and ink applying means>
The ink applying step is a step of applying ink containing a coloring material and water, and is carried out by the ink applying means.

The method for applying the ink is not particularly limited, and is an inkjet method, a blade coating method, a gravure coating method, a gravure offset coating method, a bar coating method, a roll coating method, a knife coating method, an air knife coating method, a comma coating method, and U. Comma coat method, AKKU coat method, smoothing coat method, micro gravure coat method, reverse roll coat method, 4-roll coat method, 5-roll coat method, dip coat method, curtain coat method, slide coat method, die coat method, etc. Can be mentioned. Among these, the inkjet method is preferably used.
The amount of ink applied when creating a solid image is preferably 4 g / m ² or more and 14 g / m ² or less, preferably 7 g, from the viewpoint of excellent solid filling property, suppressing color bleeding, and forming a high-quality image. It is more preferably / m ² or more and 14 g / m ² or less.
When printing ink in small droplets, it is preferable to reduce the amount of ink applied.

<< Ink >>
The ink used in the present invention is an ink containing a coloring material and water, but may contain an organic solvent, a resin, an additive, or the like.
Hereinafter, the organic solvent, water, coloring material, resin, additive, etc. used for the ink will be described.

-Organic solvent-
The organic solvent is not particularly limited and may be appropriately selected depending on the intended purpose. For example, the same organic solvent as that contained in the treatment liquid can be used. However, when any of 1,2-propanediol, 1,2-butanediol, and 2,3-butanediol is contained, the film-forming property of the resin is improved and the scratch resistance is further improved, which is preferable.
The content of the organic solvent in the ink is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 10% by mass or more and 60% by mass or less from the viewpoint of ink drying property and ejection reliability. More preferably, it is 20% by mass or more and 60% by mass or less.

-water-
The content of water in the ink is not particularly limited and may be appropriately selected depending on the intended purpose, but from the viewpoint of ink drying property and ejection reliability, it is preferably 10% by mass or more and 90% by mass or less, and 20% by mass. % Or more and 60% by mass or less are more preferable.

-Color material-
The coloring material is not particularly limited, and pigments and dyes can be used.
As the pigment, an inorganic pigment or an organic pigment can be used. These may be used alone or in combination of two or more. Further, a mixed crystal may be used as the pigment.
As the pigment, for example, a black pigment, a yellow pigment, a magenta pigment, a cyan pigment, a white pigment, a green pigment, an orange pigment, a glossy color pigment such as gold or silver, a metallic pigment, or the like can be used.
As inorganic pigments, carbon black produced by known methods such as contact method, furnace method, thermal method, in addition to titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, and chrome yellow. Can be used.
Examples of organic pigments include azo pigments and polycyclic pigments (for example, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc.). , Dye chelate (for example, basic dye type chelate, acid dye type chelate, etc.), nitro pigment, nitroso pigment, aniline black and the like can be used. Among these pigments, those having a good affinity with a solvent are preferably used. In addition, resin hollow particles and inorganic hollow particles can also be used.
As a specific example of the pigment, for black, carbon black (CI pigment black 7) such as furnace black, lamp black, acetylene black, channel black, etc., or copper, iron (CI pigment black 11) , Metals such as titanium oxide, and organic pigments such as aniline black (CI pigment black 1).

Further, for color, C.I. I. 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, 180, 185, 213, C.I. I. Pigment Orange 5, 13, 16, 17, 36, 43, 51, C.I. I. Pigment Red 1, 2, 3, 5, 17, 22, 23, 31, 38, 48: 2 (Permanent Red 2B (Ca)), 48: 3, 48: 4, 49: 1, 52: 2, 53: 1, 57: 1 (Brilliant Carmin 6B), 60: 1, 63: 1, 63: 2, 64: 1, 81, 83, 88, 101 (Bengara), 104, 105, 106, 108 (Cadmium Red), 112, 114, 122 (quinacridone magenta), 123, 146, 149, 166, 168, 170, 172, 177, 178, 179, 184, 185, 190, 193, 202, 207, 208, 209, 213, 219, 224, 254, 264, C.I. I. Pigment Violet 1 (Rhodamine Lake), 3, 5: 1, 16, 19, 23, 38, C.I. I. Pigment Blue 1, 2, 15 (phthalocyanine blue), 15: 1, 15: 2, 15: 3, 15: 4 (phthalocyanine blue), 16, 17: 1, 56, 60, 63, C.I. I. Pigment Green 1, 4, 7, 8, 10, 17, 18, 36 and the like.

The dye is not particularly limited, and acid dyes, direct dyes, reactive dyes, and basic dyes can be used, and one type may be used alone or two or more types may be used in combination.
As a dye, for example, C.I. I. Acid Yellow 17, 23, 42, 44, 79, 142, C.I. I. Acid Red 52,80,82,249,254,289, C.I. I. Acid Blue 9,45,249, C.I. I. Acid Black 1,2,24,94, C.I. I. Hood Black 1, 2, C.I. I. Direct Yellow 1,12,24,33,50,55,58,86,132,142,144,173, C.I. I. Direct Red 1,4,9,80,81,225,227, C.I. I. Direct Blue 1,2,15,71,86,87,98,165,199,202, C.I. I. Dylekdo Black 19,38,51,71,154,168,171,195, C.I. I. Reactive Red 14, 32, 55, 79, 249, C.I. I. Reactive Black 3, 4, 35 and the like can be mentioned.

The content of the coloring material in the ink is preferably 0.1% by mass or more and 15% by mass or less, more preferably 1% by mass or more and 10% by mass or less, from the viewpoint of improving the image density, good fixing property and ejection stability. preferable.

As a method of dispersing the pigment to obtain an ink, a method of introducing a hydrophilic functional group into the pigment to obtain a self-dispersible pigment, a method of coating the surface of the pigment with a resin and dispersing it, and a method of dispersing using a dispersant are used. The method, etc. can be mentioned.
As a method of introducing a hydrophilic functional group into a pigment to obtain a self-dispersing pigment, for example, by adding a functional group such as a sulfone group or a carboxyl group to the pigment (for example, carbon), the pigment can be dispersed in water. The method can be mentioned.
Examples of the method of coating the surface of the pigment with a resin and dispersing the pigment include a method of encapsulating the pigment in microcapsules so that the pigment can be dispersed in water. This can be rephrased as a resin-coated pigment. In this case, it is not necessary that all the pigments blended in the ink are coated with the resin, and the uncoated pigments and the partially coated pigments are dispersed in the ink as long as the effect of the present invention is not impaired. May be.
Examples of the method of dispersing using a dispersant include a method of dispersing using a known low-molecular-weight dispersant and high-molecular-weight dispersant represented by a surfactant.
As the dispersant, for example, an anionic surfactant, a cationic surfactant, an amphoteric surfactant, a nonionic surfactant and the like can be used depending on the pigment.
As the dispersant, RT-100 (nonionic surfactant) manufactured by Takemoto Oil & Fat Co., Ltd. and a naphthalene sulfonic acid Na formalin condensate can also be suitably used as the dispersant.
The dispersant may be used alone or in combination of two or more.

-Pigment dispersion-
It is possible to obtain an ink by mixing a material such as water or an organic solvent with a pigment. It is also possible to produce an ink by mixing a material such as water or an organic solvent with a pigment dispersion obtained by mixing a pigment and other water or a dispersant.
The pigment dispersion is obtained by mixing and dispersing water, a pigment, a pigment dispersant, and other components as necessary, and adjusting the particle size. A disperser may be used for dispersion.
The particle size of the pigment in the pigment dispersion is not particularly limited, but the maximum frequency in terms of the maximum number is 20 nm or more because the dispersion stability of the pigment is good and the image quality such as ejection stability and image density is also high. It is preferably 500 nm or less, and more preferably 20 nm or more and 150 nm or less.
The average particle size of the pigment can be measured using, for example, a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrac Bell Co., Ltd.) or the like.
The content of the pigment in the pigment dispersion is not particularly limited and may be appropriately selected depending on the intended purpose, but is 0.1% by mass from the viewpoint of obtaining good ejection stability and increasing the image density. 50% by mass or more is preferable, and 0.1% by mass or more and 30% by mass or less is more preferable.
It is preferable to degas the pigment dispersion by filtering the coarse particles with a filter, a centrifuge, or the like, if necessary.

-resin-
The type of resin contained in the ink is not particularly limited and may be appropriately selected depending on the intended purpose. For example, urethane resin, polyester resin, acrylic resin, vinyl acetate resin, styrene resin, butadiene resin, etc. Examples thereof include resins, styrene-butadiene resins, vinyl chloride resins, acrylic-styrene resins, and acrylic-silicone resins.
Resin particles made of these resins may be used. It is possible to obtain ink by mixing resin particles with a material such as a coloring material or an organic solvent in the state of a resin emulsion in which water is used as a dispersion medium. As the resin particles, those synthesized as appropriate may be used, or commercially available products may be used. Further, these may be used alone or in combination of two or more kinds of resin particles.

The volume average particle size of the resin particles is not particularly limited and may be appropriately selected depending on the intended purpose. However, from the viewpoint of obtaining good fixability and high image hardness, 10 nm or more and 1,000 nm or less are preferable. More than 200 nm is more preferable, and 10 nm or more and 100 nm or less is particularly preferable.
The volume average particle size can be measured using, for example, a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrac Bell Co., Ltd.).

The content of the resin is not particularly limited and may be appropriately selected depending on the intended purpose. However, from the viewpoint of fixability and storage stability of the ink, 1% by mass or more and 30% by mass with respect to the total amount of the ink. The following is preferable, and 5% by mass or more and 20% by mass or less is more preferable.

The particle size of the solid content in the ink is not particularly limited and can be appropriately selected according to the purpose, but from the viewpoint of improving image quality such as ejection stability and image density, the maximum frequency in terms of the maximum number of inks. Is preferably 20 nm or more and 1,000 nm or less, and more preferably 20 nm or more and 150 nm or less. The solid content includes resin particles, pigment particles, and the like. The particle size can be measured using a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrac Bell Co., Ltd.).

-Additive-
If necessary, a surfactant, an antifoaming agent, an antiseptic / antifungal agent, a rust preventive agent, a pH adjuster and the like may be added to the ink.

--Surfactant ---
The surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. For example, the same surfactant as that contained in the treatment liquid can be used.

－－Antifoaming agent －－
The defoaming agent is not particularly limited and may be appropriately selected depending on the intended purpose. For example, the same defoaming agent contained in the treatment liquid can be used.

－－Preservatives and fungicides －－
The antiseptic / antifungal agent is not particularly limited and may be appropriately selected depending on the intended purpose. For example, the same antiseptic / antifungal agent contained in the treatment liquid can be used.

--anti-rust--
The rust preventive agent is not particularly limited and may be appropriately selected depending on the intended purpose. For example, the same rust preventive agent contained in the treatment liquid can be used.

--PH regulator ---
The pH adjuster is not particularly limited and may be appropriately selected depending on the intended purpose. For example, the same pH adjuster contained in the treatment liquid can be used.

The ink can be prepared by dispersing or dissolving each of the components in, for example, water as a solvent, and further stirring and mixing, if necessary.
As the stirring and mixing, for example, a stirrer using a normal stirring blade, a magnetic stirrer, a high-speed disperser, or the like can be used.

The physical characteristics of the ink are not particularly limited and may be appropriately selected depending on the intended purpose. For example, the viscosity, surface tension, pH and the like are preferably in the following ranges.
The viscosity of the ink at 25 ° C. is preferably 5 mPa · s or more and 30 mPa · s or less, preferably 5 mPa · s or more and 25 mPa · s or less, from the viewpoint of improving the print density and character quality and obtaining good ejection properties. More preferred. Here, for the viscosity, for example, a rotary viscometer (manufactured by Toki Sangyo Co., Ltd., RE-80L) can be used. As the measurement conditions, it is possible to measure at 25 ° C. with a standard cone rotor (1 ° 34'× R24), a sample liquid volume of 1.2 mL, a rotation speed of 50 rpm, and 3 minutes.
The surface tension of the ink is preferably 35 mN / m or less, and more preferably 32 mN / m or less at 25 ° C. from the viewpoint that the ink is suitably leveled on the printed matter and the drying time of the ink is shortened.
The pH of the ink is preferably 7 to 12, and more preferably 8 to 11 from the viewpoint of preventing corrosion of the metal member that comes into contact with the liquid.

<Drying process and drying means>
The drying step is a step of drying the treatment liquid and the printed matter to which the ink is applied, and is carried out by a drying means.
In the present invention, the treatment liquid is applied to the printed matter by the above coating method, and then ink is applied and an image is recorded. After the treatment liquid is applied to the object to be printed, printing may be performed with ink before the applied treatment liquid dries, or after the applied treatment liquid dries, printing may be performed with ink.

Drying of the treatment liquid and ink is a step of heating and drying the printed matter (corrugated cardboard base paper) by a known method such as a roll heater, a drum heater, a warm air drying device, an infrared drying device, and an ultraviolet drying device. It is preferable to give a state in which the surface temperature of the printed matter is 60 ° C. or higher, and it is preferable that the surface temperature is 60 ° C. or higher and 100 ° C. or lower. The drying time is preferably 1 second or more and less than 300 seconds.

(Printed matter)
The printed matter of the present invention comprises a printed matter having a Cobb water absorption of 20 g / m ² or more and 75 g / m ² or less at a contact time of 120 seconds with water specified in JIS-P8140, and silica and polyvalent on the printed matter. It has a treatment liquid layer containing a metal salt and an ink layer containing a coloring material. As the printed matter, a corrugated board base paper can be preferably used.
The printed matter comprises an image formed on the printed matter using the ink used in the present invention.
It can be printed by the printing apparatus and printing method of the present invention to obtain a printed matter.
The printing device does not have to be a dedicated device for corrugated cardboard printing, and an inkjet printing device can be used.

<Printing equipment, printing method>
FIG. 3 is a schematic view showing an example of a printing apparatus and a printing method. The printing apparatus of FIG. 3 includes a processing liquid coating device 2 for applying a processing liquid, and an ink ejection head 3 for ejecting black ink (K), cyan ink (C), magenta ink (M), and yellow ink (Y). And a drying device 5, and a transport belt 6 for transporting the printed matter 1.
The recording device and the recording method may have a heating means used in the heating step and a drying means used in the drying step. The heating means and the drying means include, for example, means for heating and drying the printed surface and the back surface of the printed matter. The heating means and the drying means are not particularly limited, but for example, a hot air heater and an infrared heater can be used. Heating and drying can be performed before printing, during printing, after printing, and the like.
Further, the recording device and the recording method are not limited to those in which significant images such as characters and figures are visualized by ink. For example, those that form patterns such as geometric patterns and those that form three-dimensional images are also included.
Further, the recording device includes both a serial type device that moves the discharge head and a line type device that does not move the discharge head, unless otherwise specified.
Further, as this recording device, not only a desktop type but also a wide recording device capable of printing on an A0 size printed matter, or, for example, continuous paper wound in a roll shape can be used as the printed matter. A continuous book printer is also included.

Further, in the terms of the present invention, image formation, recording, printing, printing, etc. are all synonymous.
Recording media, media, and printed matter are all synonymous.

Hereinafter, examples of the present invention will be described, but the present invention is not limited to these examples. Unless otherwise specified, the preparation and evaluation of Examples and Comparative Examples were carried out under the conditions of 25 ° C. and 60% relative humidity.

(Preparation Example 1 of Pigment Dispersion)
-Preparation of Magenta Pigment Dispersion 1-
After premixing the mixture of the following formulation, it was circulated and dispersed for 7 hours in a disc type bead mill (KDL type, media: using 0.3 mm diameter zirconia balls), and magenta pigment dispersion 1 (Magenta pigment dispersion 1 (). Pigment concentration: 15% by mass) was obtained.
[Prescription of Magenta Pigment Dispersion 1]
・ C. I. Pigment Red 269 (manufactured by Clariant): 15 parts by mass ・ Acrylic polymer dispersant (Disperbyk-2010, manufactured by BYK Japan Co., Ltd.): 5 parts by mass ・ Ion-exchanged water: 80 parts by mass

(Ink manufacturing example 1)
-Making Magenta Ink 1-
After premixing the mixture of the following formulations, the mixture is stirred with a dissolver (DISPERMAT LC30, manufactured by Eiko Seiki Co., Ltd.) at 2,000 rpm for 10 minutes, and then filtered through a polypropylene filter with an average pore size of 0.8 μm to magenta ink. I got 1.
[Prescription of Magenta Ink 1]
-The magenta pigment dispersion 1: 20 parts by mass-TEGO (registered trademark) Wet270 (silicone-based surfactant, manufactured by Evonik): 1 part by mass-Propylene LV (antiseptic antifungal agent, manufactured by Abyssia): 0.1 Parts by mass ・ 1,2-Propanediol: 25 parts by mass ・ Propylene glycol monomethyl ether acetate: 5 parts by mass ・ Ion-exchanged water: 48.9 parts by mass

(Preparation Example 1 of Silica Dispersion)
-Preparation of silica dispersion 1-
After premixing the mixture of the following formulations, the mixture was stirred with a homogenizer (T25 Digital ULTRA-TURRAX, manufactured by IKA) at 10,000 rpm for 20 minutes to obtain silica dispersion 1 (silica concentration: 10% by mass).
[Prescription of silica dispersion 1]
・ AEROSIL 50 (hydrophilic silica, specific surface area 50 ± 15 m ² / g, manufactured by Nippon Aerosil Co., Ltd.): 10 parts by mass ・ Ion-exchanged water: 90 parts by mass

(Preparation Examples 2 to 4 of Silica Dispersion)
-Preparation of silica dispersions 2-4-
Silica dispersions 2 to 4 (silica concentration: 10% by mass) were prepared in the same manner as in Preparation Example 1 of the silica dispersion except that the formulation was changed to the formulation shown in Table 1 in Preparation Example 1 of the silica dispersion. ..

The details of each component in Table 1 are as follows.
AEROSIL 50 (hydrophilic silica, BET specific surface area 50 m ² / g, number average primary particle diameter: approx. 30 nm, manufactured by Nippon Aerosil Co., Ltd.)
AEROSIL 130 (hydrophilic silica, BET specific surface area 130 m ² / g, number average primary particle diameter: approx. 16 nm, manufactured by Nippon Aerosil Co., Ltd.)
-AEROSIL 300 (hydrophilic silica, BET specific surface area 300 m ² / g, number average primary particle diameter: about 7 nm, manufactured by Nippon Aerosil Co., Ltd.)
AEROSIL R972 (hydrophobic silica, BET specific surface area 110 m ² / g, number average primary particle size: approx. 16 nm, manufactured by Nippon Aerosil Co., Ltd.)
The BET specific surface area of silica can be measured by the Brunauer, Emmett, and Teller methods (BET method), and is a value measured by a general gas adsorption method.

(Preparation example 1 of treatment liquid)
-Preparation of treatment liquid 1-
After premixing the mixture of the following formulations, the mixture was stirred with a dissolver (DISPERMAT LC30, manufactured by Eiko Seiki Co., Ltd.) at 2,000 rpm for 10 minutes to obtain a treatment liquid 1.
[Prescription of treatment liquid 1]
-1,2-Propanediol: 10.0 parts by mass-3-methoxybutanol: 10.0 parts by mass-TEGO (registered trademark) Wet270 (silicone-based surfactant, manufactured by Evonik): 0.5 parts by mass-Proxel LV (manufactured by Abyssia, antiseptic and antifungal agent): 0.1 parts by mass ・ The silica dispersion 1: 10.0 parts by mass ・ Calcium acetate monohydrate: 6.0 parts by mass ・ Ion exchange water: 63.4 Mass part

(Preparation Examples 2 to 16 of Treatment Liquid)
-Preparation of treatment liquids 2 to 16-
Treatment liquids 2 to 16 were prepared in the same manner as in Preparation Example 1 of the treatment liquid except that the formulations shown in Tables 2 to 4 were changed in Preparation Example 1 of the treatment liquid.

Next, the viscosity of each of the obtained treatment liquids at 25 ° C. was measured as follows. The results are shown in Tables 2 to 4.

<Measurement of viscosity>
The viscosity of each treatment liquid was measured at 25 ° C. under the conditions of a standard cone rotor (1 ° 34'× R24), a sample liquid volume of 1.2 mL, a rotation speed of 50 rpm, and 3 minutes.

The details of each component in Tables 2 to 4 are as follows.
-Hiros-X-M-141 (acrylic resin emulsion, solid content 45% by mass, acid value 19 mgKOH / g, manufactured by Seiko PMC Corporation)
-TEGO (registered trademark) Wet270 (silicone-based surfactant, manufactured by Evonik)

<Coating of treatment liquid>
Each treatment liquid was applied onto each printed matter of the combinations shown in Tables 5 to 8 using a bar coater. After applying the treatment liquid, it was dried in a dryer set at 80 ° C. for 2 minutes. Tables 5 to 8 show the amount of the treatment liquid applied (g / m ² ) and the amount of silica adhered after drying (g / m ² ).

Next, the appearance change of each printed matter after the treatment liquid was applied was evaluated as follows. The results are shown in Tables 5-8.

<Evaluation of changes in the appearance of printed matter>
The treatment liquid was applied, and the degree of change in the appearance of each printed matter in the combinations shown in Tables 5 to 8 after drying was visually observed and evaluated according to the following criteria. In addition, Δ or more is the level that can be implemented and used.
[Evaluation criteria]
〇: There is almost no change in appearance compared to before coating △: Slight cloudiness and whitening are observed compared to before coating ×: Significant cloudiness and whitening are observed compared to before coating

(Examples 1 to 16 and Comparative Examples 1 to 4)
<Image recording process>
With the combinations shown in Tables 5 to 8, magenta ink 1 was filled in an inkjet printer (IPSiO GXe5500 manufactured by Ricoh Corporation), and a solid image was formed at 1,200 dpi on the printed matter coated with the treatment liquid.

<Printed matter>
The details of the printed matter are as follows.
-Printed matter A: NPK liner TF (rice amount 170 g / m ² , corrugated cardboard base paper, Cobb water absorption 55 g / m ² , manufactured by Nippon Paper Industries, Ltd.)
-Printed matter B: TPK-F (rice amount 170 g / m ² , corrugated cardboard base paper, Cobb water absorption 23 g / m ² , manufactured by Shintokai Paper Co., Ltd.)
-Printed matter C: NCNF liner (rice amount 160 g / m ² , corrugated cardboard base paper, Cobb water absorption 69 g / m ² , manufactured by Nippon Paper Industries Co., Ltd.)
The Cobb water absorption is a measured value at a contact time of 120 seconds with water specified in JIS-P8140.

Next, "optical density (magenta density)" and "bleeding (color bleed)" were evaluated as follows. The results are shown in Tables 5-8.

<Evaluation of optical density (magenta density)>
As a lining for color measurement, 10 sheets of recopy PPC paper type 6200 (manufactured by Ricoh Co., Ltd.) are laid under each printed matter of the combinations shown in Tables 5 to 8, and a spectroscopic color densitometer (device name: X-Rite939, The optical density (magenta density) was measured at any five points in the printed image using (manufactured by X-Rite), and the average value was evaluated according to the following criteria. In addition, Δ or more is the level that can be implemented and used.
[Evaluation criteria]
⊚: Optical density (magenta density) is 1.5 or more 〇: Optical density (magenta density) is 1.25 or more and less than 1.5 Δ: Optical density (magenta density) is 1.0 or more and less than 1.25 ×: Optical Concentration (magenta concentration) is less than 1.0

<Evaluation of bleeding (color bleed)>
By visually observing the edges of the formed solid image, the exudation distance of the image portion exuded to the non-printed portion of each of the combinations shown in Tables 5 to 8 was measured, and the following Evaluated by criteria. In addition, Δ or more is the level that can be implemented and used.
[Evaluation criteria]
◎: Almost no bleeding 〇: Bleeding with a bleeding distance of less than 1 mm is seen △: Bleeding with a bleeding distance of 1 mm or more and less than 2 mm is seen ×: Bleeding with a bleeding distance of 2 mm or more is seen

From the results of Tables 5 to 8, it was found that Examples 1 to 16 had a higher optical density (magenta density) than Comparative Examples 1 to 4 and could prevent bleeding (color bleeding).
Further, in Comparative Example 4, it was found that the magenta concentration decreased and the bleeding became remarkable unless the treatment liquid was applied.

Examples of aspects of the present invention are as follows.
<1> A treatment liquid containing silica and a polyvalent metal salt is applied to a printed matter having a Cobb water absorption of 20 g / m ² or more and 75 g / m ² or less at a contact time of 120 seconds with water specified in JIS-P8140. The process of applying the treatment liquid and the process of applying the liquid
An ink applying process for applying ink containing a coloring material and water,
It is a printing method characterized by including.
<2> The printing method according to <1>, wherein the printed matter is a corrugated cardboard base paper.
<3> The printing method according to any one of <1> to <2>, wherein the amount of silica adhered is 0.02 g / m ² or more and 0.8 g / m ² or less in the treatment liquid application step.
<4> The printing method according to any one of <1> to <3>, wherein the silica has a BET specific surface area of 30 m ² / g or more and 350 m ² / g or less.
<5> The printing method according to <4>, wherein the silica has a BET specific surface area of 35 m ² / g or more and 155 m ² / g or less.
<6> The printing method according to any one of <1> to <5>, wherein the content of the polyvalent metal salt in the treatment liquid is 1% by mass or more and 25% by mass or less.
<7> The printing method according to any one of <1> to <6>, wherein the content of the silica in the treatment liquid is 0.3% by mass or more and 6% by mass or less.
<8> The printing method according to any one of <1> to <7>, wherein the silica is hydrophilic silica.
<9> Any of the above <1> to <8>, wherein the treatment liquid contains a resin having an acid value of 20 mgKOH / g or less, and the content of the resin is 0.5% by mass or more and 20% by mass or less. The printing method described.
<10> The printing method according to any one of <1> to <9>, which comprises a drying step of drying the treatment liquid and the printed matter to which the ink is applied.
<11> The printing method according to any one of <1> to <10>, wherein the ink is applied by an inkjet method in the ink application step.
<12> A treatment liquid containing silica and a polyvalent metal salt is applied to a printed matter having a Cobb water absorption of 20 g / m ² or more and 75 g / m ² or less at a contact time of 120 seconds with water specified in JIS-P8140. The treatment liquid application means to be applied and
An ink applying means for applying an ink containing a coloring material and water,
It is a printing apparatus characterized by having.
<13> The printing apparatus according to <12>, which has a drying means for drying the processing liquid and the printed matter to which the ink is applied.
<14> Printed matter having a Cobb water absorption of 20 g / m ² or more and 75 g / m ² or less at a contact time of 120 seconds with water specified in JIS-P8140.
A layer containing silica and a polyvalent metal salt,
The layer containing the coloring material and
It is a printed matter characterized by having.

According to the printing method according to any one of <1> to <11>, the printing apparatus according to any one of <12> to <13>, and the printed matter according to <14>, various problems in the prior art. Can be solved and the object of the present invention can be achieved.

1 Printed matter 2 Processing liquid application device 3 Ink ejection head 5 Drying device 6 Conveyance belt

Japanese Unexamined Patent Publication No. 2006-150694 Special Table 2013-538132

Claims (14)

A treatment for applying a treatment liquid containing silica and a polyvalent metal salt to a printed matter having a Cobb water absorption of 20 g / m ² or more and 75 g / m ² or less at a contact time of 120 seconds with water specified in JIS-P8140. Liquid application process and
An ink applying process for applying ink containing a coloring material and water,
A printing method characterized by including. The printing method according to claim 1, wherein the printed matter is a corrugated cardboard base paper. The printing method according to any one of claims 1 to 2, wherein the amount of silica adhered is 0.02 g / m ² or more and 0.8 g / m ² or less in the treatment liquid application step. The printing method according to any one of claims 1 to 3, wherein the silica has a BET specific surface area of 30 m ² / g or more and 350 m ² / g or less. The printing method according to claim 4, wherein the silica has a BET specific surface area of 35 m ² / g or more and 155 m ² / g or less. The printing method according to any one of claims 1 to 5, wherein the content of the polyvalent metal salt in the treatment liquid is 1% by mass or more and 25% by mass or less. The printing method according to any one of claims 1 to 6, wherein the content of the silica in the treatment liquid is 0.3% by mass or more and 6% by mass or less. The printing method according to any one of claims 1 to 7, wherein the silica is hydrophilic silica. The printing method according to any one of claims 1 to 8, wherein the treatment liquid contains a resin having an acid value of 20 mgKOH / g or less, and the content of the resin is 0.5% by mass or more and 20% by mass or less. The printing method according to any one of claims 1 to 9, further comprising a drying step of drying the processed matter and the printed matter to which the ink is applied. The printing method according to any one of claims 1 to 10, wherein the ink is applied by an inkjet method in the ink application step. A treatment for applying a treatment liquid containing silica and a polyvalent metal salt to a printed matter having a Cobb water absorption of 20 g / m ² or more and 75 g / m ² or less at a contact time of 120 seconds with water specified in JIS-P8140. Liquid application means and
An ink applying means for applying an ink containing a coloring material and water,
A printing apparatus characterized by having. The printing apparatus according to claim 12, further comprising a drying means for drying the processed matter and the printed matter to which the ink is applied. Printed matter having a Cobb water absorption of 20 g / m ² or more and 75 g / m ² or less at a contact time of 120 seconds with water specified in JIS-P8140.
A layer containing silica and a polyvalent metal salt,
The layer containing the coloring material and
A printed matter characterized by having.

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