JP2022049649A - Printing method, printer and printed matter - Google Patents

Abstract

To provide a printing method that prints with a white ink on corrugated cardboard base paper having a high water absorption rate and then applying a non-white ink on the white ink, the printing method capable of realizing an excellent image quality while preventing the blot, density decrease and repelling of the non-white ink.SOLUTION: A printing method includes: a process liquid applying step of applying a process liquid containing a polyvalent metal salt onto a print target matter having a Cobb water absorbing capacity of 20 g/m2 to 75 g/m2 for 120 sec water contact time stipulated by JIS-P8140; a white ink applying step of applying a white ink containing a white coloring material and water to form a white ink layer; and a non-white ink applying step of applying, on the white ink layer, a non-white ink containing a non-white coloring material and water after 0.5 sec or more interval, without providing a drying step of drying by drying means, after applying the white ink.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 home use but also for packaging materials such as foods, beverages, and daily necessities. Examples of printed matter in packaging applications include corrugated cardboard.

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

For printing on cardboard, offset printing, flexographic printing, gravure printing, etc. have been used for some time, 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, uneven density is likely to occur due to the influence of the unevenness (flute grain) on the surface of the cardboard, and it is particularly difficult to print the post-print on a thick cardboard. On the other hand, although the preprint method solves the problem in printing, there is a problem that the bonding process after printing takes time and the box making process cannot be started immediately after printing.

Inkjet printing is a non-contact method of recording images on a print medium, so post-print printing on thick cardboard paper is easy, and the box-making process can be started immediately after printing, enabling quick delivery. Therefore, the demand for inkjet printing in cardboard printing is increasing.

When performing color printing on corrugated board, white corrugated board is widely used. This is because good color development cannot be obtained when color ink (hereinafter, also referred to as “non-white ink”) is directly printed on brown corrugated cardboard base paper.

On the other hand, although the penetration rate is low, printing has been devised in which white ink is printed on brown corrugated cardboard base paper and then non-white ink is applied onto the white ink. However, in the printing method using water-based ink, there are quality problems such as bleeding, density reduction, and repelling of non-white ink, and it is not possible to sufficiently meet the quality demands from consumers such as high density and high resolution.

Therefore, a method of improving color development and color reproducibility by using fluorescent ink together with non-white ink has been proposed (see, for example, Patent Document 1). Further, a method of printing a non-white ink on a white ink with good color development property has been proposed (see, for example, Patent Document 2).

INDUSTRIAL APPLICABILITY The present invention is excellent in a printing method in which white ink is printed on a cardboard base paper having a high water absorption rate and a non-white ink is applied onto the white ink, which can prevent bleeding, decrease in density, and repelling of the non-white ink. It is an object of the present invention to provide a printing method capable of achieving image quality.

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. A treatment liquid application step of applying a treatment liquid containing a polyvalent metal salt, a white ink application step of applying a white ink containing a white color material and water to form a white ink layer, and the white ink. A non-white ink that imparts a non-white color material and a non-white ink containing water onto the white ink layer after a time of 0.5 seconds or more without providing a drying step of drying by a drying means after the application. Including the granting step.

According to the present invention, in a printing method in which white ink is printed on a cardboard base paper having a high water absorption rate and non-white ink is applied onto the white ink, bleeding, density reduction, and repelling of the non-white ink can be prevented, which is excellent. It is possible to provide a printing method that can achieve high image quality.

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)
The printing method of the present invention is a treatment in which a multivalent metal salt is 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. A treatment liquid applying step of applying a liquid, a white ink applying step of applying a white ink containing a white color material and water to form a white ink layer, and a drying step of applying the white ink and then drying by a drying means. A non-white ink applying step of applying a non-white ink containing a non-white color material and water onto the white ink layer after a time of 0.5 seconds or more is included, and a drying step is performed. It is preferably included, and further includes other steps as necessary.

The printing apparatus of the present invention is a treatment for containing 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. A treatment liquid applying means for applying a liquid, a white ink applying means for applying a white ink containing a white color material and water to form a white ink layer, and a drying step of applying the white ink and then drying by the drying means. A non-white ink applying means for applying a non-white ink containing a non-white color material and water on the white ink layer after a time of 0.5 seconds or more without providing the drying means. It is preferable to have the above, and if necessary, other means are provided.

The printing method of the present invention can be suitably carried out by the printing apparatus of the present invention, the processing liquid applying step can be performed by the processing liquid applying means, and the white ink applying step can be performed by the white ink applying means. The non-white ink applying step can be performed by the non-white ink applying means, the drying step can be performed by the drying means, and the other steps can be performed by other means.

With the prior art described in Patent Document 1, it is difficult to eliminate the influence of the corrugated board base paper on the color development of the non-white ink, and the fluorescent substance is inferior in chemical resistance and weather resistance, so that the versatility is sufficient. Not really.
Further, in the prior art described in Patent Document 2, a first coagulant that reacts with white particles in the white ink and a second coagulant that reacts with the dye in the colored ink are used in the upper and lower layers of the white ink. However, there is a problem that the coagulant needs to be supplied to the printed matter multiple times, and the versatility is not sufficient.

In the present invention, a treatment liquid containing 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. A treatment liquid applying step, a white ink applying step of applying a white ink containing a white color material and water to form a white ink layer, and a drying step of applying the white ink and then drying by a drying means are provided. By including a non-white ink applying step of applying a non-white ink containing a non-white color material and water on the white ink layer after a time of 0.5 seconds or more, bleeding and low It is possible to obtain high-quality printed matter with less density and repelling. That is, by applying the non-white ink on the white ink layer after a time of 0.5 seconds or more without providing a drying step of applying the white ink and then drying it by the drying means, a large amount of the white ink is added to the treatment liquid. By ensuring the time required for the valence metal salt to react with the white color material in the white ink as a flocculant, bleeding (color bleeding) and concentration decrease caused by the mixture of the non-white ink with the white ink are prevented. can. Further, by not drying the white ink layer, the white ink does not form a dry film and the motility of the unreacted polyvalent metal salt diffused in the white ink is maintained and reacts with the coloring material in the non-white ink. Since it is in an easy state, it is possible to prevent the non-white ink from repelling.

<Treatment liquid application process and treatment liquid application means>
In the treatment liquid application step, a treatment liquid containing 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 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 white 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 a polyvalent metal salt and, if necessary, other components.

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 application method, and such a viscosity may be adjusted, for example, by a rotary viscometer (Toki Sangyo). RE-80L) manufactured by 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 50 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. ,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. , 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 coat Examples include the method, the curtain coat method, the slide coat method, and the die coat method. The application method can be appropriately selected depending on the material, thickness, etc. of the printed matter.

The amount of the treatment liquid 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.

The treatment liquid layer may be dried after the treatment liquid is applied to the object to be printed, but it is possible to save space by applying the white ink onto the treatment liquid layer without drying the treatment liquid layer. It is preferable from the viewpoint of property and energy saving, and it is preferable to apply the white ink within 5 seconds after applying the treatment liquid to the printed matter.

-Multivalent metal salt-
The polyvalent metal salt has a function of destabilizing the dispersion of the white color material in the white ink, and the white color material in the white ink is quickly aggregated after being dropped, and the non-white ink is a white ink. It is possible to prevent bleeding (color bleeding) and decrease in density caused by mixing with.

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 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 7% by mass or more, more preferably 12% by mass or more, still more preferably 12% by mass or less and 25% by mass or less, based on the total amount of the treatment liquid. The content of the polyvalent metal salt is preferably 7% by mass or more from the viewpoint of suppressing bleeding of the non-white ink on the white ink. It should be noted that 25% by mass or less is preferable because the treatment liquid has high stability when stored for a long period of time and can suppress the occurrence of quality defects such as precipitation.

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

--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. The glass transition temperature (Tg) of the resin is preferably -25 ° C or higher from the viewpoint of suppressing stickiness on the surface of the printed matter and blocking when stacked, maintaining adhesion, and cracking or peeling during bending in the box making process. The Tg is preferably 70 ° C. or lower in order to avoid the occurrence of. 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 suppressed. Is preferable because it is fully exhibited.

--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, Triethylene Glycol, 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; ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol monoethyl ether, etc. Polyvalent alcohol alkyl ethers; Polyhydric 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., the content is 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 ---
The surfactant can reduce the surface tension of the treatment liquid, improve the wettability to various printed materials, and apply uniformly, and the polyvalent metal salt contained in the treatment liquid can be uniformly applied on the printed material. It has the effect of being able to be 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 compounds 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, the polyalkylene oxide structure represented by the 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）式中、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 fluorosurfactant 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 preferably one of the following general formulas (F-1) and (F-2). The represented fluorosurfactant is preferred.

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, Neos Co., Ltd. manufactured by The Chemours Company, from the viewpoint of remarkably improving good print quality, especially color development, permeability to paper, wettability, and leveling property. 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% by mass or less is preferable, and 0.05% by mass or more and 5% by mass or less is more preferable.

－－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. A printed matter having excellent color development and bleed resistance can be obtained. Even when corrugated matter (liner paper) is used as the printed matter, it is possible to obtain a printed matter having excellent density color development and bleed resistance.

Here, as a printing method on the cardboard, as shown in FIG. 1, after recording the image 11 on the cardboard 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. To manufacture the cardboard (pre-printing method) and to record the image 11 with printing ink on the surface liner paper 10 of the bonded cardboard (post-printing method), as shown in FIG. Broadly speaking, the present invention can be suitably used for any method.
Since the surface liner paper can be wound 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. 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: front liner paper, core, and 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, leaflets, etc. 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 white 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 white 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.

The brightness L ^* value of the printed matter is preferably 60 or less, more preferably 55 or less.
When the brightness L ^* value is 60 or less, the difference in brightness between the white ink printed area and the non-printed area increases, so that there is an advantage that the visibility of the white ink is improved.
The brightness L ^* value can be measured using, for example, a spectrophotometric densitometer (device name: X-Rite939, manufactured by X-Rite).

<White ink applying process and white ink applying means>
The white ink applying step is a step of applying a white ink containing a white color material and water to form a white ink layer, and is carried out by the white ink applying means.

The method for applying the white ink is not particularly limited, and includes 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, and a comma coating 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 coat method, curtain coat method, slide coat method, die coat method, etc. Can be mentioned. Among these, the inkjet method is preferably used.
In the white ink applying step, it is preferable to apply the white ink twice or more from the viewpoint of improving the concealing property.
From the viewpoint of improving concealment, the amount of white ink applied when forming a solid image is preferably 5 g / m ² or more and 25 g / m ² or less, and more preferably 10 g / m ² or more and 25 g / m ² or less. It is more preferably 11 g / m ² or more and 22 g / m ² or less.

<< White ink >>
The white ink contains a white colorant and water, and further contains other components as needed.

-White color material-
ISO-2469 (JIS-8148) is a standard for the whiteness of white ink, and generally, when the whiteness is 70 or more, it is used as a white coloring material.
The coloring material used for the white ink is preferably a metal oxide, and examples thereof include titanium oxide, iron oxide, tin oxide, zirconium oxide, and iron titanate (composite oxide of iron and titanium). Further, white particles having a hollow structure are also preferably used.
Examples of the white particles having a hollow structure used for the white ink include hollow resin particles and inorganic hollow particles.
Examples of the resin composition of the hollow resin particles include acrylic resins such as acrylic resin, styrene-acrylic resin, and crosslinked styrene-acrylic resin, urethane-based resins, and malein-based resins.
Examples of the material of the inorganic hollow particles include oxides of metals such as silicon, aluminum, titanium, strontium, and zirconium that exhibit white color, nitrides, nitrides oxide, various glasses, and inorganic compounds such as silica.
As a coloring material used for white ink, when a metal oxide is used, the whiteness is excellent, and when white particles having a hollow structure are used, it is difficult to settle and is excellent in terms of settling property. There is.

The content of the white color material in the white ink is preferably 0.1% by mass or more and 15% by mass or less, and more preferably 1% by mass or more and 10% by mass or less.

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 the 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 with other water, a dispersant or the like.
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 particle size of the pigment can be measured using a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrac Bell Co., Ltd.).
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.

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

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

-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.).

The organic solvent, the surfactant, the antifoaming agent, the antiseptic / antifungal agent, the rust preventive agent, and the pH adjuster are not particularly limited and may be appropriately selected depending on the intended purpose, for example. The same organic solvent, the surfactant, the defoaming agent, the antiseptic and antifungal agent, the rust preventive agent, and the pH adjuster contained in the treatment liquid can be used.

The white ink can be prepared by, for example, dispersing or dissolving each of the components in 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 properties of the white 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 white 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 performance. Is more preferable. 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 white ink is preferably 35 mN / m or less, more preferably 32 mN / m or less at 25 ° C. from the viewpoint that the ink is preferably leveled on the printed matter and the drying time of the ink is shortened.
The pH of the white ink is preferably 7 to 12, more preferably 8 to 11, from the viewpoint of preventing corrosion of the metal member that comes into contact with the liquid.

<Non-white ink applying process and non-white ink applying means>
In the non-white ink applying step, the non-white color material and water are contained on the white ink layer after a time of 0.5 seconds or more without providing a drying step of applying white ink and then drying by a drying means. This is a step of applying non-white ink to be applied, and can be carried out by means for applying non-white ink.

The method for applying the non-white 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, and a comma coating 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 coat method, curtain coat method, slide coat method, die coat method. And so on. Among these, the inkjet method is preferably used.
From the viewpoint of achieving high image density, the amount of non-white ink applied when creating a solid image is preferably 5 g / m ² or more and 15 g / m ² or less, and 7 g / m ² or more and 15 g / m ² or less. preferable.

The time from applying the white ink to applying the non-white ink requires 0.5 seconds or more, preferably 1 second or more, more preferably 1 second or more and 4 seconds or less, and 2 seconds or more and 4 seconds or less. Is more preferable.
When the time from applying the white ink to applying the non-white ink is 0.5 seconds or more, it is necessary for the polyvalent metal salt in the treatment liquid to react with the white color material in the white ink as a coagulant. It is possible to secure a sufficient amount of time, and it is possible to prevent bleeding (color bleeding) and decrease in density caused by mixing non-white ink with white ink.
Here, the "time from the application of the white ink to the application of the non-white ink" is the period from the application of the white ink to the object to be printed (landing) to the application of the non-white ink to the object to be printed (landing). It means time, for example, the distance [m] between the landing position of the white ink and the landing position of the non-white ink on the printing machine is divided by the transport speed [m / sec] of the printed matter, or the white ink is used. The time from landing to landing of non-white ink can be measured by directly measuring with a measuring device such as a stop watch or a timer with a sensor.

<< Non-white ink >>
The non-white ink contains a non-white color material and water, and further contains other components as needed.

-Non-white color material-
Examples of the non-white ink include color ink, black ink, gray ink, clear ink, metallic ink and the like.
Examples of the color ink include cyan ink, magenta ink, yellow ink, light cyan ink, light magenta ink, red ink, green ink, blue ink, orange ink, violet ink and the like.
The color material used for the non-white ink is not particularly limited as long as it exhibits non-white color, and can be appropriately selected depending on the intended purpose, and examples thereof include dyes and pigments. These may be used alone or in combination of two or more. Among these, pigments are preferable.
Examples of the pigment include inorganic pigments and organic pigments.

Examples of the inorganic pigment include calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, and chrome yellow, as well as carbon black produced by known methods such as a contact method, a furnace method, and a thermal method. Can be mentioned. These may be used alone or in combination of two or more.

Examples of the organic pigment include azo pigments (including, for example, azolakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments, etc.) and polycyclic pigments (eg, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments). , Kinacridone pigment, dioxazine pigment, indigo pigment, thioindigo pigment, isoindolinone pigment, quinophthalone pigment, etc.), dye chelate (for example, basic dye type chelate, acidic dye type chelate, etc.), nitro pigment, nitroso pigment, aniline black, etc. Can be mentioned. These may be used alone or in combination of two or more.
Among these pigments, those having a good affinity with a solvent are preferably used.

Examples of the pigment for black include carbon black (CI pigment black 7) such as furnace black, lamp black, acetylene black, and channel black, copper, and iron (CI pigment black 11). , Organic pigments such as aniline black (CI pigment black 1) and the like. These may be used alone or in combination of two or more.

For color, for example, 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; 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, 185, 190, 193, 209, 219; 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 (phthalocyanine blue), 16, 17: 1, 56, 60, 63; C.I. I. Pigment Green 1, 4, 7, 8, 10, 17, 18, 36 and the like. These may be used alone or in combination of two or more.

As the 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. Food 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. Dilekdo 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. These may be used alone or in combination of two or more.

The coloring material used for the metallic ink is, for example, a simple substance of a metal, an alloy, or a fine powder obtained by finely pulverizing a metal compound. Specifically, one or more of a group of simple metals consisting of aluminum, silver, gold, nickel, chromium, tin, zinc, indium, titanium, silicon, copper, and platinum, or alloys. Can be mentioned. Examples of the metal compound include one or a plurality of oxides, nitrides, sulfides, and carbides of elemental metals or alloys.

The content of the non-white color material in the non-white ink is preferably 0.1% by mass or more and 15% by mass or less, and more preferably 1% by mass or more and 10% by mass or less.

-water-
The water is not particularly limited and may be appropriately selected depending on the intended purpose. For example, water similar to the water contained in the white ink can be used.

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

The resin is not particularly limited and may be appropriately selected depending on the intended purpose. For example, the same resin as the resin contained in the white ink can be used.
The organic solvent, the surfactant, the antifoaming agent, the antiseptic / antifungal agent, the rust preventive agent, and the pH adjuster are not particularly limited and may be appropriately selected depending on the intended purpose, for example. Since it is the same as the above treatment liquid, these descriptions are omitted.

<Drying process and drying means>
In the present invention, after applying the pretreatment liquid to the printed matter, the printed matter to which the pretreatment liquid is applied is dried, then white ink is applied, and after the white ink is applied, the drying step is performed by drying means. The non-white ink is applied after a time of 0.5 seconds or more without the provision. After applying the non-white ink, the white ink and the printed matter to which the non-white ink is applied are dried. Alternatively, after applying the pretreatment liquid to the printed matter, a drying step is provided in which the printed matter to which the pretreatment liquid is applied is not dried, then white ink is applied, and after the white ink is applied, the printed matter is dried by a drying means. The non-white ink is applied after a time of 0.5 seconds or more. After applying the non-white ink, the white ink and the printed matter to which the non-white ink is applied are dried.

After applying the white ink, the non-white ink is applied without providing a drying step of drying by the drying means. Examples of the drying means referred to here include a roll heater, a drum heater, a hot air drying device, an infrared drying device, an ultraviolet drying device, and the like, which are drying means other than natural drying. After applying the white ink and before applying the non-white ink, it is not necessary to provide a drying step using a drying means, and natural drying is not excluded.
After applying the white ink, the non-white ink is applied after a time of 0.5 seconds or more without providing a drying step of drying by a drying means. At this time, the time of 0.5 seconds or more is 0 ° C. or more. It is preferable to leave a time of 0.5 seconds or more at 50 ° C. or lower. More preferably, the time is preferably 15 ° C. or higher and 40 ° C. or lower for 0.5 seconds or longer.
After applying the white ink, it takes 0.5 seconds or more to apply the non-white ink, but 1 second or more is preferable, 1 second or more and 4 seconds or less is more preferable, and 2 seconds or more and 4 seconds or less is further preferable. ..
The drying step of drying the printed matter to which the non-white ink is applied is carried out by a drying means.

Drying of the printed matter to which the non-white ink is applied 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. Therefore, it is preferable to provide a state in which the surface temperature of the printed matter is 60 ° C. or higher, preferably 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 is a treatment containing a polyvalent metal salt on 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 liquid layer, a white ink layer containing a white color material, and a non-white ink layer containing a non-white color material.
Corrugated cardboard base paper can be preferably used as the printed matter.
The printed matter comprises an image formed on the printed matter using the non-white 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 device and printing method>
FIG. 3 is a schematic view showing an example of a printing apparatus used in the printing method of the present invention. The printing device 100 of FIG. 3 includes a processing liquid coating device 2 for applying the processing liquid, a white ink ejection head 3 for ejecting white ink (W), black ink (K), cyan ink (C), and magenta ink ( A non-white ink (color ink) ejection head 4 for ejecting M) and yellow ink (Y), a first drying device 5, a second drying device 6, and a conveying belt 5 for conveying a printed matter 1. Have.
In the printing device of FIG. 3, the first drying device 5 is installed between the processing liquid application device 2 and the white ink ejection head 3 as needed, and the processing is applied even when the first drying device 5 is installed. The liquid does not necessarily have to be dried. The second drying device 6 is installed behind the yellow ink (Y) ejection head of the non-white ink (color ink) ejection head 4, and drying the non-white ink causes rubbing and backing of the non-white ink. It is preferable in terms of preventing.
As described above, after the white ink is applied to the printed matter, the non-white ink is applied after a time of 0.5 seconds or more without providing a drying step of drying by the drying means. Therefore, the white ink ejection in FIG. 3 It is necessary to provide an appropriate distance between the head 3 and the color ink ejection head 4. As an example, when printing is performed at a speed of 60 meters per minute, the distance between the white ink ejection head 3 and the color ink ejection head 4 should be separated by about 0.5 meters or more in order to secure a time of 0.5 seconds or more. Similarly, in order to secure a time of 2 seconds or more, it is preferable that the distance between the white ink ejection head 3 and the color ink ejection head 4 is about 2.0 meters or more. The white ink ejection head 3 and the color ink ejection head 4 may be integrated into an ejection head and moved to a desired ejection position.
In FIG. 3, two or more white ink ejection heads 3 may be arranged in succession, and two or more layers of white ink may be stacked. In this case, better white ink hiding property can be obtained.

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 White Pigment Dispersion)
-Preparation of white pigment dispersion 1-
After premixing the mixture of the following formulation, it was circulated and dispersed in a disc type bead mill (manufactured by Simmal Enterprises, KDL type, media: using zirconia balls having a diameter of 0.3 mm) for 7 hours to obtain white pigment dispersion 1 (white pigment dispersion 1 (). Pigment concentration: 40% by mass) was obtained.
[Prescription of white pigment dispersion 1]
・ C. I. Pigment White 7 (manufactured by Ishihara Sangyo Co., Ltd.): 40 parts by mass ・ Acrylic polymer dispersant (Disperbyk-2015, manufactured by BYK Japan Co., Ltd.): 5 parts by mass ・ Ion-exchanged water: 55 parts by mass

(Preparation Example 1 of Non-White Pigment Dispersion)
-Preparation of Magenta Pigment Dispersion 1-
After premixing the mixture of the following formulation, it was circulated and dispersed in a disc type bead mill (manufactured by Simmal Enterprises, KDL type, media: using zirconia balls with a diameter of 0.3 mm) for 7 hours, and the 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

(Manufacturing example 1 of white ink)
-Preparation of white ink 1-
After premixing the mixture of the following white ink 1 formulations, a dissolver (DISPERMAT LC30, manufactured by Eiko Seiki Co., Ltd.) was used to stir at 2,000 rpm for 10 minutes, and then filtered through a polypropylene filter having an average pore size of 0.8 μm. By doing so, white ink 1 was obtained.
[Prescription of white ink 1]
-The white pigment dispersion 1:30 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: 38.9 parts by mass

(Manufacturing example 1 of non-white ink)
-Making Magenta Ink 1-
After premixing the mixture of the following magenta ink 1 formulations, a dissolver (DISPERMAT LC30, manufactured by Eiko Seiki Co., Ltd.) is used, and the mixture is stirred at 2,000 rpm for 10 minutes and then filtered through a polypropylene filter having an average pore size of 0.8 μm. By doing so, magenta ink 1 was obtained.
[Prescription of Magenta Ink 1]
-The magenta pigment dispersion 1:30 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: 38.9 parts by mass

(Preparation example 1 of treatment liquid)
-Preparation of treatment liquid 1-
After premixing the mixture of the formulation of the following treatment liquid 1, a dissolver (DISPERMAT LC30, manufactured by Eiko Seiki Co., Ltd.) was used, and the mixture was stirred at 2,000 rpm for 10 minutes to obtain the treatment liquid 1. The viscosity of the treatment liquid 1 at 25 ° C. was 7.0 mPa · s.
[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 (Abyssia, antiseptic and antifungal agent): 0.1 parts by mass ・ Magnesium acetate tetrahydrate: 12.0 parts by mass ・ Ion exchanged water: 67.4 parts by mass

(Preparation example 2 of treatment liquid)
-Preparation of treatment liquid 2-
After premixing the mixture of the formulation of the following treatment liquid 2, the treatment liquid 2 was obtained by stirring at 2,000 rpm for 10 minutes using a dissolver (DISPERMAT LC30, manufactured by Eiko Seiki Co., Ltd.). The viscosity of the treatment liquid 2 at 25 ° C. was 6.8 mPa · s.
[Prescription of treatment liquid 2]
-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 ・ Magnesium acetate tetrahydrate: 6.0 parts by mass ・ Ion exchanged water: 73.4 parts by mass

(Examples 1 to 10 and Comparative Examples 1 to 5)
<Process of applying treatment liquid>
Use NPK liner TF (rice amount 170 g / m ² , brown corrugated cardboard base paper, Cobb water absorption 55 g / m ² , brightness L ^* value 51, manufactured by Nippon Paper Industries Co., Ltd.) as the printed material, and place a bar coater on the printed material. The treatment liquid 1 or the treatment liquid 2 was applied using. The Cobb water absorption is a measured value at a contact time of 120 seconds with water specified in JIS-P8140. The coating amount of the treatment liquid was 10 g / m ² .
After the treatment liquid was applied, the treatment liquid was dried in a dryer set at 80 ° C. for 2 minutes under the condition of drying the treatment liquid. On the other hand, under the condition that the treatment liquid was not dried, the white ink was printed 5 seconds after the treatment liquid was applied.

<White ink application process>
The white ink 1 was filled in an inkjet ejection head (MH5421MF manufactured by Ricoh Corporation), and a solid image having a width of 5 cm and a length of 20 cm was formed on a printed matter coated with the treatment liquid at 600 dpi. The white ink 1 was printed by placing the printed matter on a conveyor device and passing it directly under the inkjet ejection head at a speed of 48 meters per minute. The amount of the white ink 1 applied was 11 g / m ² .
When the white ink 1 was printed twice in succession, the two inkjet ejection heads were connected for printing, and the amount of the white ink 1 applied in this case was 22 g / m ² .
After printing, the white ink 1 was dried in a dryer set at 80 ° C. for 2 minutes under the condition of drying. Under the condition that the white ink 1 was not dried, the magenta ink 1 was printed continuously after the seconds shown in Tables 1 to 3 after printing the white ink 1.

<Applying process of non-white ink>
The magenta ink 1 is filled in an inkjet ejection head (MH5421MF manufactured by Ricoh Co., Ltd.) to form a solid image having a width of 4 cm and a length of 10 cm directly above the white ink 1 printed on the printed matter. did. The inkjet ejection head filled with the magenta ink 1 prints the white ink 1 behind the inkjet ejection head filled with the white ink 1 on the conveyor device, and then continuously prints the magenta ink 1. Was installed at a distance from Table 1 to the number of seconds shown in Table 3. In Example 1, the distance between the inkjet ejection head filled with the white ink 1 and the inkjet ejection head filled with the magenta ink 1 was 1.6 meters.

<Drying process of printed matter>
After printing the magenta ink 1, the printed matter was dried in a dryer set at 80 ° C. for 2 minutes.

Next, "concealment of white ink", "magenta ink bleeding on white ink", "magenta ink density on white ink", and "magenta ink repelling on white ink" are described as follows. evaluated. The results are shown in Tables 1 to 3.

<Evaluation of concealment of white ink>
As a lining for color measurement, 10 sheets of recopy PPC paper type 6200 (manufactured by Ricoh Co., Ltd.) were laid under each printed matter of the combinations shown in Tables 1 to 3, and a spectroscopic color densitometer (device name: X-Rite939, Brightness (L ^* value) was measured at any 5 points in the solid image printed with only white ink using X-Rite), and the average value was evaluated according to the following criteria. In addition, 〇 or more is the level that can be actually used.
[Evaluation criteria]
⊚: Brightness (L ^* value) is 80 or more 〇: Brightness (L ^* value) is 75 or more and less than 80 Δ: Brightness (L ^* value) is 70 or more and less than 75 ×: Brightness (L ^* value) is less than 70

<Evaluation of bleeding of magenta ink on white ink>
By visually observing the edges of the solid image of magenta ink formed on the white ink, the magenta ink solid image portion exuded from the white ink solid image of each of the combinations shown in Tables 1 to 3. The exudation distance was measured and evaluated according to the following criteria. In addition, Δ or more is the level that can be actually used.
[Evaluation criteria]
◎: Almost no bleeding is seen 〇: Bleeding with a bleeding distance of less than 0.5 mm is seen △: Bleeding with a bleeding distance of 0.5 mm or more and less than 1 mm is seen ×: Bleeding with a bleeding distance of 1 mm or more Can be seen

<Evaluation of magenta ink density on white ink>
As a lining for color measurement, 10 sheets of recopy PPC paper type 6200 (manufactured by Ricoh Co., Ltd.) were laid under each printed matter of the combinations shown in Tables 1 to 3, and a spectroscopic color densitometer (device name: X-Rite939, Using (manufactured by X-Rite), the optical density (magenta) was measured at any five points in the solid image in which magenta ink was printed on white ink, and the average value was evaluated according to the following criteria. In addition, Δ or more is the level that can be actually used.
[Evaluation criteria]
〇: Optical density (magenta) is 1.5 or more Δ: Optical density (magenta) is 1.2 or more and less than 1.5 ×: Optical density (magenta) is less than 1.2

<Evaluation of repelling of magenta ink on white ink>
By visually observing the solid image of the magenta ink formed on the white ink, the degree of repelling of the solid image portion of the magenta ink on the white ink solid image of each of the combinations shown in Tables 1 to 3 is as follows. Evaluated according to the criteria of. In addition, 〇 or more is the level that can be actually used.
[Evaluation criteria]
◎: No repelling of magenta ink and no unevenness 〇: No repelling of magenta ink but unevenness is visible △: White ink in the lower layer of magenta ink is slightly exposed ×: Magenta ink The underlying white ink is clearly exposed

From the results of Tables 1 to 3, all of Examples 1 to 10 have "concealing property of white ink", "bleeding of magenta ink on white ink", and "on white ink" as compared with Comparative Examples 1 to 5. It was found that the evaluation results of "magenta ink density" and "magenta ink repelling on white ink" were good.
On the other hand, in Comparative Examples 1 to 3, the white ink layer was dried, and "bleeding of magenta ink on white ink" and "repelling of magenta ink on white ink" occurred. It is considered that this is because the motility of the unreacted polyvalent metal salt diffused in the white ink was suppressed by the drying of the white ink, and the reactivity with the coloring material (pigment) in the magenta ink was lowered. Further, the decrease in the "magenta ink density on the white ink" is considered to be the effect of the decrease in the ink acceptability of the magenta ink layer due to the effect of the cissing.
Further, in Comparative Examples 4 and 5, the time from applying the white ink to continuously printing the magenta ink was less than 0.5 seconds, and "bleeding of the magenta ink on the white ink" occurred. ..
Further, in Comparative Example 4, a decrease in "magenta ink density on white ink" occurred. This is because the time required for the polyvalent metal salt in the treatment liquid to react with the coloring material (pigment) in the white ink as a flocculant was insufficient, so the magenta ink was mixed with the white ink (color bleed). ) Is considered to be the effect.

Examples of aspects of the present invention are as follows.
<1> A treatment liquid containing 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. Treatment liquid application process and
A white ink applying step of applying a white ink containing a white color material and water to form a white ink layer,
After applying the white ink, a non-white ink containing a non-white color material and water is applied onto the white ink layer after a time of 0.5 seconds or more without providing a drying step of drying by a drying means. Non-white ink application process and
It is a printing method characterized by including.
<2> The step of allowing a time of 0.5 seconds or more without providing the drying step of drying by the drying means is a step of allowing a time of 0.5 seconds or more at 15 ° C. or higher and 40 ° C. or lower. 1> is the printing method.
<3> The step of allowing a time of 0.5 seconds or more without providing a drying step of drying by the drying means is a step of allowing a time of 1 second or more and 4 seconds or less at 15 ° C. or higher and 40 ° C. or lower. The printing method according to any one of <1> to <2>.
<4> The printing method according to any one of <1> to <3>, wherein the printed matter is a corrugated cardboard base paper.
<5> The printing method according to any one of <1> to <4>, wherein the brightness L ^* value of the printed matter is 60 or less.
<6> The printing according to any one of <1> to <5>, wherein the white ink is applied onto the treatment liquid layer without providing a drying step of applying the treatment liquid and then drying by the drying means. The method.
<7> The printing method according to any one of <1> to <6>, wherein the content of the polyvalent metal salt is 7% by mass or more.
<8> The non-white ink is applied onto the white ink layer without drying the white ink layer at a time of 2 seconds or more and 5 seconds or less after the white ink is applied. <1> The printing method according to any one of <7>.
<9> The printing method according to any one of <1> to <8>, wherein the white ink is applied twice or more in the white ink applying step.
<10> The printing method according to any one of <1> to <9>, which comprises a drying step of drying the printed matter to which the non-white ink is applied.
<11> The printing method according to any one of <1> to <10>, wherein the white ink and the non-white ink are applied by an inkjet method in the white ink applying step and the non-white ink applying step. ..
<12> A treatment liquid containing 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. Treatment liquid application means and
A white ink applying means for applying a white ink containing a white color material and water to form a white ink layer,
After applying the white ink, a non-white ink containing a non-white color material and water is applied onto the white ink layer after a time of 0.5 seconds or more without providing a drying step of drying by a drying means. Non-white ink applying means and
It is a printing apparatus characterized by having.
<13> The printing apparatus according to <12>, which has a drying means for drying a printed matter to which the non-white ink is applied.
<14> On 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.
A treatment liquid layer containing a polyvalent metal salt and
A white ink layer containing a white color material and
A non-white ink layer containing a non-white color material,
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 White ink ejection head 4 Non-white ink (color ink) ejection head 5 First drying device 6 Second drying device 7 Conveyance belt 100 Printing device

Japanese Patent No. 6140908 Japanese Unexamined Patent Publication No. 2014-83789

Claims (14)

A treatment liquid for imparting a treatment liquid containing 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. Process and
A white ink applying step of applying a white ink containing a white color material and water to form a white ink layer,
After applying the white ink, a non-white ink containing a non-white color material and water is applied onto the white ink layer after a time of 0.5 seconds or more without providing a drying step of drying by a drying means. Non-white ink application process and
A printing method characterized by including. The first aspect of claim 1, wherein the step of allowing a time of 0.5 seconds or more without providing the drying step of drying by the drying means is a step of allowing a time of 0.5 seconds or more at 15 ° C. or higher and 40 ° C. or lower. Printing method. From claim 1, the step of allowing a time of 0.5 seconds or more without providing the drying step of drying by the drying means is a step of allowing a time of 1 second or more and 4 seconds or less at 15 ° C. or higher and 40 ° C. or lower. The printing method according to any one of 2. The printing method according to any one of claims 1 to 3, wherein the printed matter is a corrugated cardboard base paper. The printing method according to any one of claims 1 to 4, wherein the brightness L ^* value of the printed matter is 60 or less. The printing method according to any one of claims 1 to 5, wherein the white ink is applied onto the treatment liquid layer without providing a drying step of applying the treatment liquid and then drying by the drying means. The printing method according to any one of claims 1 to 6, wherein the content of the polyvalent metal salt is 7% by mass or more. Any of claims 1 to 7, wherein the non-white ink is applied onto the white ink layer without drying the white ink layer after a time of 2 seconds or more and 5 seconds or less after applying the white ink. The printing method described in the ink. The printing method according to any one of claims 1 to 8, wherein the white ink is applied twice or more in the white ink applying step. The printing method according to any one of claims 1 to 9, further comprising a drying step of drying the printed matter to which the non-white ink is applied. The printing method according to any one of claims 1 to 10, wherein the white ink and the non-white ink are applied by an inkjet method in the white ink applying step and the non-white ink applying step. A treatment liquid for imparting a treatment liquid containing 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. Means and
A white ink applying means for applying a white ink containing a white color material and water to form a white ink layer,
After applying the white ink, a non-white ink containing a non-white color material and water is applied onto the white ink layer after a time of 0.5 seconds or more without providing a drying step of drying by a drying means. Non-white ink applying means and
A printing apparatus characterized by having. The printing apparatus according to claim 12, further comprising a drying means for drying the printed matter to which the non-white ink is applied. On 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,
A treatment liquid layer containing a polyvalent metal salt and
A white ink layer containing a white color material and
A non-white ink layer containing a non-white color material,
A printed matter characterized by having.

Images