JP2021053815A - Printing method - Google Patents

Abstract

To provide a printing method which enables good printing of absorptive base materials such as coat paper, high-quality paper and art paper.SOLUTION: A printing method using an ink set containing an aqueous color ink and an aqueous coating liquid having an effect of flocculating the aqueous color ink includes a first step of preparing an absorptive base material, a second step of treating the surface of the absorptive base material with the aqueous coating liquid, a third step of drying the surface of the absorptive base material treated in the second step, a fourth step of treating the surface of the absorptive base material dried in the third step with the aqueous coating liquid, and a fifth step of performing printing of the surface of the absorptive base material treated in the fourth step with the aqueous color ink. The aqueous coating liquid contains at least water, a resin and an organic solvent, and the resin contains a water-soluble polymer having cation.SELECTED DRAWING: None

Description

The present invention relates to a printing method, and more particularly to a printing method that enables good printing on an absorbent base material such as coated paper, woodfree paper, and art paper.

Various inks have been developed as inks used for printing with an inkjet printer, but water-based inks are widely used from the viewpoint of reducing the environmental load. However, since the water-based ink contains water as a solvent, it tends to cause bleeding during printing. As a method for improving the bleeding of the printing layer formed by printing, for example, a method of using a treatment liquid having an action of aggregating colored inks in combination is known (for example, JP-A-6-57192 and JP-A-6-57192). 2009-190379 (Japanese Patent Publication No. 2009-190379).

Regarding a water-based ink set containing a coloring ink and a treatment liquid, Japanese Patent Application Laid-Open No. 2017-222793 is an ink set containing a water-based coloring ink and a water-based coating liquid, wherein the water-based coloring ink is water and a self-dispersing pigment. The water-based coating liquid contains water, a water-soluble solvent and a resin, and the resin contained in the water-based coating liquid contains a water-soluble polymer having a quaternary ammonium cation. An ink set characterized in that the pH of the coating liquid is in the range of 7.1 to 10.0 is described.

Japanese Unexamined Patent Publication No. 6-57192 Japanese Unexamined Patent Publication No. 2009-190379 Japanese Unexamined Patent Publication No. 2017-222793

According to the ink set described in Patent Document 3, it is possible to suppress the occurrence of bleeding of the printing layer and the occurrence of corrosion of the printing equipment, and to form a printing layer having good fixability without lowering the gloss. An ink set can be provided.

However, as a result of the study by the present inventor, the water-based ink set as described in Patent Document 3 is sufficiently capable of printing on a non-absorbent base material such as polyethylene terephthalate (PET) film. However, there is a problem that good printing cannot be performed on absorbent base materials such as coated paper, high-quality paper, and art paper due to the occurrence of streaks and bleeding, and there is room for improvement. Specifically, in printing on a PET film, the coating liquid is sufficiently wet and spread on the film, so that the color ink to be printed thereafter can be fixed in a predetermined position. On the other hand, in printing on coated paper, the coating liquid permeates the base material and cannot be sufficiently wet and spread. In this case, there is a problem that the agglutinating action of the coating liquid cannot be sufficiently exerted, and as a result, the color ink cannot be fixed in a predetermined position.

Therefore, an object of the present invention is to provide a printing method that solves the above-mentioned problems of the prior art and enables good printing on an absorbent base material such as coated paper, woodfree paper, and art paper. It is in.

As a result of diligent studies to achieve the above object, the present inventor has dried the coating liquid on the absorbent base material once when treating the surface of the absorbent base material with the coating liquid, and then the absorbable base material. When the surface of the base material was treated with the coating liquid again, the coating liquid was sufficiently wetted and spread, and it was found that the surface of the absorbent base material could be treated uniformly, and the present invention was completed.

The printing method of the present invention is a printing method using an ink set containing a water-based color ink and a water-based coating liquid having an action of aggregating the water-based color ink.
The first step of preparing the absorbent substrate and
The second step of treating the surface of the absorbent base material with the water-based coating liquid, and
The third step of drying the surface of the absorbent base material treated in the second step, and
The fourth step of treating the surface of the absorbent base material dried in the third step with the water-based coating liquid, and the fourth step.
The fifth step of printing with the water-based color ink on the surface of the absorbent base material treated in the fourth step is included.
Here, the water-based coating liquid is characterized by containing at least water, a resin, and an organic solvent, and the resin contains a water-soluble polymer having a cation.

In a preferred example of the printing method of the present invention, the content of the water-soluble polymer having the cation in the water-based coating liquid is 0.5 to 8.0% by mass.

In another preferred example of the printing method of the present invention, the organic solvent contains at least one alkanediol-based solvent.

In another preferred example of the printing method of the present invention, the water-soluble polymer having a cation has a weight average molecular weight of 1,000 or more.

In another preferred example of the printing method of the present invention, the water-soluble polymer having a cation has a weight average molecular weight of 100,000 or less.

In another preferred example of the printing method of the present invention, the aqueous coating liquid further comprises at least one silicone-based surface conditioner.

In another preferred example of the printing method of the present invention, the water-based coating liquid has a surface tension value of 28.0 mN / m or less at 25 ° C.

In another preferred example of the printing method of the present invention, the water-based coating liquid has a surface tension value of 21.0 mN / m or more at 25 ° C.

In another preferred example of the printing method of the present invention, the aqueous coating solution further comprises at least one macromer-modified acrylic surface conditioner.

In another preferred example of the printing method of the present invention, drying is performed at 70 to 130 ° C. in the third step.

In another preferred example of the printing method of the present invention, drying is performed for 2 seconds or more and less than 120 seconds in the third step.

In another preferred example of the printing method of the present invention, the surface of the absorbent substrate dried in the third step has a surface life of 100 ms and a dynamic contact angle of water at a temperature of 25 ° C. of 70 ° or less.

In another preferred example of the printing method of the present invention, the surface of the absorbent substrate dried in the third step has a surface life of 100 ms as compared with the surface of the absorbent substrate prepared in the first step. And the difference in the dynamic contact angle of water at a temperature of 25 ° C. is 10 ° or more.

According to the present invention, it is possible to provide a printing method that enables good printing on an absorbent base material such as coated paper, wood-free paper, and art paper.

The printing method of the present invention will be described in detail below. The printing method of the present invention is a printing method using an ink set containing a water-based color ink and a water-based coating liquid having an action of aggregating the water-based color ink. In the present specification, the "ink set used in the printing method of the present invention" is also referred to as the "ink set of the present invention".

In the ink set of the present invention, the water-based color ink is an ink that is printed on the surface of a base material treated with a water-based coating liquid, colors the base material, and draws characters, images, etc., and is usually water or resin. , Includes organic solvents and colorants. The water-based coating liquid is a liquid used for treating the surface of the base material and for aggregating the water-based color ink to be printed thereafter, and usually contains water, an organic solvent, and a resin. In the present invention, the water-based coating liquid contains a water-soluble polymer having a cation.

In the present specification, a composition containing a colorant in an amount of more than 0.1% by mass is referred to as an "ink", and a composition containing no colorant or containing 0.1% by mass or less of a colorant is simply a "liquid". It is expressed as. Further, in the present specification, the "water-based color ink" and the "water-based coating liquid" are color inks and coating liquids containing water as a main solvent.

In the ink set of the present invention, the water-based color ink may consist of a plurality of water-based color inks that emit different colors, and is a water-based color ink containing at least four types of inks: cyan ink, magenta ink, yellow ink, and black ink. Can be exemplified. Unlike the water-based color ink, the water-based coating liquid is often used alone. However, in the printing method of the present invention, since the two-step treatment with the water-based coating liquid is performed, a plurality of water-based coating liquids having different compositions can be used. You may use it.

In the ink set of the present invention, the water-based color ink and the water-based coating liquid contain water, and pure water such as ion-exchanged water and distilled water, ultrapure water and the like are preferably mentioned. When the ink or coating liquid is stored for a long period of time, water sterilized by ultraviolet irradiation or the like may be used in order to prevent the growth of mold and bacteria. Here, it can be exemplified that the water content in each of the water-based color ink and the water-based coating liquid is in the range of 20 to 90% by mass, preferably 50 to 90% by mass, and more preferably 60 to 90% by mass. It is in the range of 80% by mass. Thereby, it is possible to provide a color ink and a coating liquid having a smaller burden on the environment.

In the ink set of the present invention, the water-based coating liquid contains a resin, and the resin contains a water-soluble polymer having a cation. Since the water-soluble polymer has a cation, it can exhibit the ability to aggregate color inks. As a result, the adhesion of the print layer to the substrate can be improved while suppressing the occurrence of bleeding of the print layer, and high-speed printing becomes possible. Further, if it is a cation, it can exhibit the ability to aggregate color ink even if it is present in an aqueous coating liquid having a pH in the basic region. However, the water-soluble polymer has a high ability to agglomerate color inks, causes agglomeration of color inks to occur remarkably quickly, and may reduce the gloss of the print layer. preferable. Further, the aqueous coating liquid prepared by using the water-soluble polymer having a cation keeps its viscosity and pH even when stored for a long period of time, and excellent storage stability can be obtained.
In addition, in this specification, a water-soluble polymer means a polymer which dissolves in water or an aqueous solution containing less than 50% by mass of a water-soluble organic solvent.

The water-soluble polymer having the above cation is preferably a water-soluble polymer having a quaternary ammonium cation (cationized nitrogen atom). By using a water-soluble polymer having a quaternary ammonium cation, the occurrence of bleeding of the printing layer is further suppressed, and the scratch resistance of the printing layer and the storage stability of the water-based coating liquid are improved.

The water-soluble polymer having the cation preferably has a weight average molecular weight of 1,000 or more, more preferably 2,500 or more, and further preferably 5,000 or more. By setting the weight average molecular weight of the water-soluble polymer to 1,000 or more, it is possible to secure the state in which the polymer is present on the substrate, and as a result, it is possible to prevent the water-based coating liquid and the water-based color ink from repelling. it can. On the other hand, the water-soluble polymer having the above cation preferably has a weight average molecular weight of 100,000 or less, more preferably 50,000 or less, still more preferably 45,000 or less, and 40,000. The following is particularly preferable. By setting the weight average molecular weight of the water-soluble polymer to 100,000 or less, the dots of the water-based color ink printed on the surface-treated substrate can be easily spread, and as a result, the color development property can be improved. Further, if the weight average molecular weight of the water-soluble polymer having the cation is too high, the dot diameter tends to be small, and as a result, the printed matter has streaks. Further, when the weight average molecular weight is high, the adhesiveness of the print layer of the color ink may be lowered by forming the polymer layer having a cation.
In the present specification, the weight average molecular weight is a value measured by gel permeation chromatography (GPC), polystyrene is used as a standard substance, and tetrahydrofuran is used as a mobile phase.

The water-soluble polymer having a cation preferably has a cation in the main chain. When a water-soluble polymer having such a structure is used, when the water-based color ink is printed on the water-based coating liquid layer, only the interface of the water-based color ink is instantly aggregated, and the water-based color inks do not mix with each other. Since it is fixed at the printed position, it is more preferable in the case of high-speed printing.

The water-soluble polymer having the cation is preferably two or more kinds of water-soluble polymers having different cation degrees. By using a plurality of water-soluble polymers having different cations, it becomes easy to adjust the size of the dot diameter and the bleeding.
Specifically, the water-soluble polymers having the above cations are a water-soluble polymer having a cation degree of 5.5 to 7.5 meq / g at pH 7.1 and a cation degree of 2.0 to 5 at pH 7.1. It is preferable to contain a water-soluble polymer having a cation degree of .0 meq / g, a water-soluble polymer having a cation degree of 6.0 to 7.0 meq / g at pH 7.1, and a cation degree at pH 7.1 of 2. It is more preferable to include a water-soluble polymer of 5 to 4.5 meq / g. The ratio of the water-soluble polymer having the above-mentioned two types of cation degree ranges is such that the mass ratio of the water-soluble polymer having a high cation degree range to the water-soluble polymer having a low cation degree range is 1: 1 to 20: 1. It is preferably in the range of 7: 3 to 10: 1, and more preferably in the range of 7: 3 to 10: 1.
In this specification, the degree of cation can be determined by colloidal titration using a potassium polyvinyl sulfate reagent. The detailed procedure is as follows.
Take 90 mL of deionized water in a conical beaker, add 10 mL of a 500 ppm aqueous solution of the sample (dry product equivalent) to pH 7.1 with an aqueous amine solution, and stir for about 1 minute. Next, 2-3 drops of toluidine blue indicator are added and titrated with N / 400 polyvinyl sulfate potassium reagent (N / 400PVSK). The titration rate is 2 mL / min, and the end point is when the test water changes color from blue to purplish red and is held for 10 seconds or longer. The formula for calculating the degree of cation (meq / g) is as follows.
Catility = (N / 400PVSK titration) x (N / 400PVSK titer) / 2

Commercially available products can be used as the water-soluble polymer having the above cation. Of these, a water-soluble polymer having a quaternary ammonium cation is preferable, but from the viewpoint that it can exist stably even if it is basic, for example, DK6810, DK6851, DK6864, WS4030, WS4027, WS4052, CA6018 (all manufactured by Seiko PMC), Harsize CP-300, CP-800 (manufactured by Harima Kasei Co., Ltd.), PAS-H-1L, PAS-H-5L, PAS-2401, PAS-A-1 (manufactured by Knitbo Medical Co., Ltd.), Kachio Master PDT -2, PD-7, PD-30 (all manufactured by Yokkaichi Chemical Co., Ltd.), a reaction product of epichlorohydrin and alkylamine commercially available, a polyamine resin, a polyamide / epichlorohydrin resin, and the like can be mentioned. The water-soluble polymer having the above cation may be used alone or in combination of two or more.

In the water-based coating liquid, the content of the water-soluble polymer having the cation is preferably 0.5 to 8.0% by mass, more preferably 1.0 to 4.0% by mass. By setting the content of the water-soluble polymer to 0.5 to 8.0% by mass, the water-based coating liquid can be easily wetted and spread, and the color tint of the color ink can be prevented from being impaired.

As the other resin that can be used in the water-based coating liquid, a resin that is usually used in the ink industry other than the water-soluble polymer having a cation can be used. For example, acrylic resin, silicone resin, acrylic silicone resin, styrene acrylic copolymer resin, polyester resin, rosin resin, phenol resin, urethane resin, melamine resin, urea resin, epoxy resin, cellulose resin, butyral resin, maleic acid resin, fumaru. Acid resin, vinyl resin and the like can be mentioned. These resins may be used alone or in combination of two or more.

The proportion of the water-soluble polymer having the cation in the resin contained in the water-based coating liquid is preferably 50% by mass or more, but in particular, from the viewpoint of appropriately controlling the aggregating action, the water-based coating liquid contains the water-based coating liquid. The proportion of the water-soluble polymer having the quaternary ammonium cation in the resin contained in the above is preferably 50% by mass or more.

It can be exemplified that the content of the resin in the water-based coating liquid is 0.005 to 15% by mass, but it is preferably 0.5 to 10% by mass, preferably 0.5 to 5% by mass. %, More preferably 0.5 to 4.5% by mass, and particularly preferably 0.5 to 4.0% by mass.

Further, in the ink set of the present invention, a resin usually used in the ink industry can be used as the water-based color ink, for example, acrylic resin, silicone resin, acrylic silicone resin, styrene acrylic copolymer resin, polyester resin. , Rosin resin, petroleum resin, kumaron resin, phenol resin, urethane resin, melamine resin, urea resin, epoxy resin, cellulose resin, xylene resin, alkyd resin, aliphatic hydrocarbon resin, butyral resin, maleic acid resin, fumaric acid resin , Vinyl resin and the like. These resins may be used alone or in combination of two or more.

The resin that can be used for the water-based color ink can include a self-dispersing resin. The self-dispersible resin is a resin that can maintain a dispersed state in an ink without using a surfactant or an emulsifier, and is usually hydrophilic such as sulfonic acid or a salt thereof or carboxylic acid or a salt thereof. A polymer having a group at the end or a side chain, a polymer having a hydrophilic group such as a polycarbonate group, a polyester group, or a polyether group in the main chain, or the like is preferably used. These self-dispersible resins may be used alone or in combination of two or more. As the self-dispersing resin, a commercially available product may be used.

The self-dispersible resin preferably contains a self-dispersible urethane resin from the viewpoint of improving the performance of the printed layer such as scratch resistance and water resistance, and further from the viewpoint of imparting high adhesion to various substrates. , It is more preferable to contain a self-dispersing urethane resin containing a polyester group or a polyether group. The proportion of the self-dispersible urethane resin in the self-dispersible resin is preferably 30 to 100% by mass.

The self-dispersible urethane resin preferably has a weight average molecular weight of 100,000 to 1,000,000, more preferably 150,000 to 750,000, and more preferably 200,000 to 500,000. Is even more preferable. When the weight average molecular weight of the self-dispersible urethane resin is within the specified range, the scratch resistance can be further improved and a strong printed layer can be formed.
In the present specification, the weight average molecular weight is a value measured by gel permeation chromatography (GPC), polystyrene is used as a standard substance, and tetrahydrofuran is used as a mobile phase.

The self-dispersible urethane resin can be obtained by reacting a polyol component such as a polyester polyol, a polyether polyol, or a polycarbonate polyol with a polyisocyanate component, and optionally a chain extender.

The polyester polyol is not particularly limited, and is, for example, polyethylene adipate, polyethylene propylene adipate, polybutylene adipate, polyhexamethylene adipate, polydiethylene adipate, polyethylene terephthalate, polyethylene isophthalate, polyhexamethylene isophthalate, polyethylene succinate, poly. Examples thereof include butylene succinate, polyethylene sebacate, polybutylene sebacate, poly-ε-caprolactamdiol and poly (3-methyl-1,5-pentylene adipate). By using a polyester polyol as the polyol component, a polyester group-containing self-dispersing urethane resin can be obtained. Since such a resin is dispersed in the ink in the form of particles, it is also referred to as polyester urethane resin particles in the present specification.
The polyether polyol is not particularly limited, and examples thereof include polyoxytetramethylene glycol, polyoxypropylene glycol, polyoxyethylene glycol, and polyoxyethylene / propylene glycol. By using a polyether polyol as a polyol component, a polyether group-containing self-dispersing urethane resin can be obtained. Since such a resin is dispersed in the ink in the form of particles, it is also referred to as a polyether urethane resin particle in the present specification.
The polycarbonate polyol is not particularly limited, and examples thereof include 1,6-hexanediol polycarbonate polyol, 1,4-butanediol polycarbonate polyol, and poly-1,4-cyclohexanedimethylene carbonate diol. By using a polycarbonate polyol as the polyol component, a polycarbonate group-containing self-dispersing urethane resin can be obtained. Since such a resin is dispersed in the ink in the form of particles, it is also referred to as polycarbonate urethane resin particles in the present specification.
As the polyol component, an acrylic polyol or the like may be used.
These polyol components may be used alone or in combination of two or more.

Examples of the polyisocyanate component include tolylene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, naphthylene diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, tetramethylxylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate and the like. Examples thereof include polyisocyanate compounds such as norbornandiisocyanate. Among these polyisocyanate components, xylene diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate) or norbornane diisocyanate are preferable. These polyisocyanate components may be used alone or in combination of two or more.

Examples of the chain extender include low molecular weight polyhydric alcohols and low molecular weight polyamines. Examples of low molecular weight polyhydric alcohols include ethylene glycol, diethylene glycol, 1,4-butanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, trimethylolpropane, and penta. Examples thereof include dimethylol alkanoic acids such as erythritol, 1,4-cyclohexanedimethanol, dimethylol butanoic acid and dimethylol propionic acid. Examples of low molecular weight polyamines include ethylenediamine, trimethylenediamine, tetramethylenediamine, hexamethylenediamine, hydrazine, piperazine, isophoronediamine, norbornandiamine, diaminodiphenylmethane, diaminocyclohexylmethane, tolylenediamine, xylenediamine, diethylenetriamine, and triamine. Examples thereof include ethylenetetramine, tetraethylenepentamine and iminobispropylamine. These chain extenders may be used alone or in combination of two or more.

The water-based color ink preferably contains urethane-based resin particles such as polyether urethane resin particles and polyester urethane resin particles. The ink containing urethane-based resin particles can also improve the scratch resistance of the print layer.

The self-dispersing resin is dispersed in the ink and is in the form of particles. Here, the self-dispersible resin preferably has an average particle size (D50) of 10 nm to 90 nm, more preferably 20 nm to 70 nm, and even more preferably 30 nm to 60 nm. If the average particle size is within the specified range, an ink having a good dispersion state of the self-dispersive resin and excellent storage stability can be prepared.
In the present specification, average particle diameter (D50) refers to the 50% particle diameter on a volume basis particle size distribution _{(D 50),} a laser diffraction / scattering particle size distribution analyzer (e.g., SALD-7000: Shimadzu Corporation Ltd. ) Can be obtained from the particle size distribution measured. The particle size in the present specification is represented by a sphere-equivalent diameter obtained by a laser diffraction / scattering method.

The self-dispersible resin preferably has an acid value of 5.0 to 60.0. If the acid value is within the specified range, the dispersibility can be improved. In the present specification, the acid value of the resin means the number of mg of potassium hydroxide required to neutralize 1 g of the resin.

Further, in the ink set of the present invention, the acid value of the self-dispersing resin contained in the water-based color ink and the cation degree of the water-soluble polymer having a cation contained in the water-based coating liquid are adjusted to obtain the water-based color ink. It is possible to form a print layer having an excellent gloss, which has a large dot diameter and does not cause bleeding. Here, the ratio (C: D) of the acid value (C) of the self-dispersing resin to the degree of cationism (meq / g) (D) at pH 7.1 of the cationic polymer is 10: 1 to 1: 2. It is preferably in the range of 6: 1 to 1.2: 3, more preferably in the range of 3: 1 to 1: 1 and even more preferably in the range of 3: 1 to 1: 1.

The resin content in the water-based color ink is preferably 1 to 10% by mass. The proportion of the self-dispersing resin in the resin is preferably 50% by mass or more.

In the ink set of the present invention, the water-based color ink is not particularly limited, and pigments such as organic pigments and inorganic pigments usually used as colorants in the ink industry can be used, but include self-dispersing pigments. Is preferable. The self-dispersible pigment is a pigment that can maintain a dispersed state in an ink without using a pigment dispersant, and is usually obtained by imparting a functional group having excellent hydrophilicity to the surface. In the case of a combination of the above-mentioned water-soluble polymer having a cation, particularly a water-soluble polymer having a quaternary ammonium cation and a self-dispersing pigment, the present inventor causes the aggregation to occur too quickly on the surface of the printing layer. It has been found that it is possible to prevent the formation of unevenness, thereby preventing the deterioration of the gloss of the print layer.

In the present invention, as the self-dispersing pigment, a pigment in which anions such as carboxyl ion, sulfate ion, nitrate ion, phosphate ion and hydroxide ion are directly bonded to the surface is preferable. By using such an anion-type self-dispersing pigment, the pigment can be stably dispersed in the ink without adding a dispersant, and a clearer image can be printed. Commercially available products can be preferably used as these anion-type self-dispersing pigments.

Examples of the pigment include Pigment Yellow 12, 13, 14, 17, 20, 24, 31, 42, 53, 55, 74, 83, 86, 93, 109, 110, 117, 120, 122, 125, 128. , 129, 137, 138, 139, 147, 148, 150, 151, 152, 153, 154, 155, 166, 168, 180, 181, 184, 185, 213; Pigment Orange 16, 36, 38, 43, 51 , 55, 59, 61, 64, 65, 71; Pigment Red 9, 48, 49, 52, 53, 57, 97, 101, 122, 123, 149, 168, 177, 180, 192, 202, 206, 215. , 216, 217, 220, 223, 224, 226, 227, 228, 238, 240, 244, 254; Pigment Violet 19, 23, 29, 30, 32, 37, 40, 50; Pigment Blue 15, 15: 1. , 15: 3, 15: 4, 15: 6, 22, 27, 28, 29, 30, 60, 64, 80; Pigment Green 7, 36; Pigment Brown 23, 25, 26; and Pigment Black 1, 7, 26, 27, 28, Pigment White 6 and the like. These pigments may be used alone or in combination of two or more.
Examples of pigments that can be used for cyan ink include Pigment Blue 15, 15: 1, 15: 3, 15: 4, 15: 6, 22, 27, 28, 29, 30, 60, 64, 80 and the like. ,
Examples of pigments that can be used in magenta ink include Pigment Red 9, 48, 49, 52, 53, 57, 97, 101, 122, 123, 149, 168, 177, 180, 192, 202, 206, 215, 216. , 217, 220, 223, 224, 226, 227, 228, 238, 240, 244, 254, etc.
Examples of pigments that can be used for yellow ink include Pigment Yellow 12, 13, 14, 17, 20, 24, 31, 42, 53, 55, 74, 83, 86, 93, 109, 110, 117, 120, 122. , 125, 128, 129, 137, 138, 139, 147, 148, 150, 151, 152, 153, 154, 155, 166, 168, 180, 181, 184, 185, 213, etc.
Examples of pigments that can be used for black ink include Pigment Black 1, 7, 26, 27, 28 and the like.
In addition, Pigment Orange 16, 36, 38, 43, 51, 55, 59, 61, 64, 65, 71; Pigment Violet 19, 23, 29, 30, 32, 37, 40, 50; Pigment Green 7, 36; Pigment browns 23, 25, 26; pigments such as pigment white 6 can also be used as the basic color inks, and can also be used as special color inks such as orange inks, violet inks, green inks, and red inks.

The content of the pigment in the water-based color ink can be arbitrarily determined depending on the type of pigment used and the like, but is preferably 0.5 to 10% by mass.

In the ink set of the present invention, an organic solvent can be used for the water-based coating liquid and the water-based color ink. The organic solvent that can be used for the water-based coating liquid and the water-based color ink is not particularly limited, and an organic solvent that is usually used in the ink industry can be used. It can be exemplified that the content of the organic solvent in each of the water-based coating liquid and the water-based color ink is 5 to 49% by mass, but preferably 5 to 35% by mass, and more preferably 10 to 35% by mass. It can also be adjusted in a low range of 15 to 35% by mass, particularly preferably. As a result, it is possible to provide a water-based coating liquid and a water-based color ink that have less impact on the environment, and since the organic solvent is less likely to remain in the formed film, the physical properties of the film such as scratch resistance are improved. It will be easier. The organic solvent may be used alone or in combination of two or more.

The organic solvent that can be used in the water-based coating liquid and the water-based color ink is preferably a water-soluble organic solvent, and more preferably contains at least one kind of alkanediol-based solvent, particularly at least two kinds of alkanediol-based solvents. By using an alkanediol-based solvent, it is possible to prevent the ink from drying in the ejection portion (particularly the print head) of a printing device such as an inkjet printer, and as a result, improve the storage stability, wettability and ejection stability of the ink. it can. The content of the alkanediol-based solvent in each of the water-based coating liquid and the water-based color ink is preferably 5.0 to 40.0% by mass.

In addition, the organic solvents that can be used for water-based coating liquids and water-based color inks are alkanediol-based solvents, glycol ether-based solvents, and three to five members from the viewpoint of improving ink ejection stability, wettability, and storage stability. It is preferable to contain at least one selected from the group consisting of a lactone-based solvent of the ring and an amide-based solvent.
Here, in the ink set of the present invention, from the viewpoint of adjusting the dynamic surface tension values of the color ink and the coating liquid, the water-based coating liquid and the water-based color ink are independently the alcandiol-based solvent and the glycol ether-based ink. It preferably contains at least one type (preferably at least two types) selected from the group consisting of solvents, and particularly contains both an alcandiol-based solvent and a glycol ether-based solvent from the viewpoint of adjusting the surface tension value of the coating liquid. Is preferable. Here, when both the alkanediol-based solvent and the glycol ether-based solvent are contained, the mass ratio (E: F) of the alkanediol-based solvent (E) and the glycol ether-based solvent (F) is 8: 1 to 1: 8. It is preferably within the range, preferably within the range of 5: 1 to 1: 5.

The alkanediol-based solvent is an acyclic saturated hydrocarbon having two hydroxyl groups, for example, ethylene glycol, propylene glycol, 2-methyl-1,3-propanediol, 1,2-butanediol, 1,3-. Butanediol, 1,4-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,2-heptanediol, 1,2-octanediol, 1,9-nonane Diol, 1,10-decanediol and the like can be mentioned. Among these, ethylene glycol, 1,2-propylene glycol, 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-heptanediol, and 1,2-octanediol are preferable. ..

Specific examples of glycol ether-based solvents include ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol propyl ether, ethylene glycol butyl ether, ethylene glycol pentyl ether, ethylene glycol hexyl ether, ethylene glycol cyclohexyl ether, ethylene glycol phenyl ether, and ethylene. Glycolbenzyl ether, ethylene glycol isobutyl ether, ethylene glycol tertiary butyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol propyl ether, diethylene glycol butyl ether, diethylene glycol pentyl ether, diethylene glycol hexyl ether, diethylene glycol cyclohexyl ether, diethylene glycol phenyl ether, diethylene glycol benzyl ether, Diethylene glycol monobutyl ether, diethylene glycol isobutyl ether, triethylene glycol methyl ether, triethylene glycol ethyl ether, triethylene glycol propyl ether, triethylene glycol butyl ether, triethylene glycol pentyl ether, triethylene glycol hexyl ether, triethylene glycol cyclohexyl ether, tri Ethylene glycol ethers such as ethylene glycol phenyl ether, triethylene glycol benzyl ether and triethylene glycol monobutyl ether, as well as propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol propyl ether, propylene glycol butyl ether, propylene glycol pentyl ether and propylene glycol. Hexyl ether, propylene glycol cyclohexyl ether, dipropylene glycol methyl ether, dipropylene glycol ethyl ether, dipropylene glycol propyl ether, dipropylene glycol butyl ether, dipropylene glycol pentyl ether, dipropylene glycol hexyl ether, dipropylene glycol cyclohexyl ether, tri Propropylene glycol methyl ether, tripropylene glycol ethyl ether, tripropylene glycol propyl ether, tripropylene glyco Examples thereof include propylene glycol ethers such as rubutyl ether, tripropylene glycol pentyl ether, tripropylene glycol hexyl ether and tripropylene glycol cyclohexyl ether. Among these, ethylene glycol monobutyl ether, ethylene glycol isobutyl ether, ethylene glycol tertiary butyl ether, diethylene glycol monobutyl ether, diethylene glycol isobutyl ether and triethylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol. Monopropyl ether and triethylene glycol monobutyl ether are preferred.

The three- to five-membered lactone-based solvent is a compound having a lactone ring containing -C (= O) -O- as a part, and the three-membered ring having three atoms constituting the ring and the number of atoms is three. It is a compound of a 4-membered ring having 4 or a 5-membered ring having 5 atoms. Specific examples include α-acetolactone, β-propionlactone, γ-butyrolactone, δ-valerolactone and the like. Among these, γ-butyrolactone is preferable.

The amide-based solvent is preferably an acyclic amide compound, for example, dimethylacetamide, dimethylformamide, sulfanylamide, toluenesulfonamide, benzenesulfonamide, N-dimethyl-β-methoxypropionamide, N, N-dimethyl-β-. Butoxypropionamide, N, N-dimethyl-β-pentoxypropionamide, N, N-dimethyl-β-hexoxypropionamide, N, N-dimethyl-β-heptoxypropionamide, N, N-dimethyl-β -2-Ethylhexoxypropionamide, N, N-dimethyl-β-octoxypropionamide, N, N-diethyl-β-methoxypropionamide, N, N-diethyl-β-butoxypropionamide, N, N- Diethyl-β-pentoxypropionamide, N, N-diethyl-β-hexoxypropionamide, N, N-diethyl-β-heptoxypropionamide, N, N-diethyl-β-octoxypropionamide and the like. Be done. Among these, dimethylacetamide, dimethylformamide, N, N-dimethyl-β-methoxypropionamide, N, N-dimethyl-β-butoxypropionamide, N, N-diethyl-β-methoxypropionamide, N, N- Diethyl-β-butoxypropionamide is preferred.

In the ink set of the present invention, the water-based coating liquid and the water-based color ink preferably contain a surface conditioner from the viewpoint of adjusting the surface tension value. Examples of the surface adjusting agent include silicone-based surface adjusting agents, acrylic-based surface adjusting agents, vinyl-based surface adjusting agents, fluorine-based surface adjusting agents, acetylene glycol-based surface adjusting agents, and the like, but at least one type of silicone-based surface adjusting agent. It is preferable to contain an agent, and it is more preferable to contain both a silicone-based surface conditioner and an acetylene glycol-based surface conditioner. Here, when both the silicone-based surface conditioner and the acetylene glycol-based surface conditioner are contained, the mass ratio (A: B) of the silicone-based surface conditioner (A) and the acetylene glycol-based surface conditioner (B) is 5. : 1 to 1: 5, more preferably 3: 1 to 1: 3.

Specific examples of the silicone-based surface conditioner include polyether-modified polysiloxane, polysell-modified polysiloxane, polyether-modified hydroxyl group-containing polysiloxane, polyester-modified hydroxyl group-containing polysiloxane, and the like. BYK-Chemie, Shinetsu Chemical Industry Co., Ltd. Commercially available products are easily available.

（式中、Ｒ¹及びＲ²は、それぞれ独立した炭化水素基を示す）で表されるような、アセチレン基を中心とした左右対称構造を有する非イオン性界面活性剤が好適である。また、本明細書においては、界面活性剤の水酸基にアルキレンオキシド（エチレンオキシド、プロピレンオキシド等）を付加してなるアルキレンオキシド付加物もアセチレングリコール系表面調整剤に含まれる。アセチレングリコール系表面調整剤は、日信化学工業株式会社等から市販される商品が容易に入手可能である。 The acetylene glycol-based surface conditioner is a surfactant having an acetylene group and two hydroxyl groups, and is, for example, the following formula (1).

A nonionic surfactant having a symmetrical structure centered on an acetylene group as represented by (R ¹ and R ^{2 each indicate an independent hydrocarbon group in the formula) is suitable.} Further, in the present specification, the acetylene glycol-based surface conditioner also includes an alkylene oxide adduct formed by adding an alkylene oxide (ethylene oxide, propylene oxide, etc.) to the hydroxyl group of the surfactant. As the acetylene glycol-based surface conditioner, commercially available products from Nissin Chemical Industry Co., Ltd. and the like are easily available.

In the ink set of the present invention, the water-based coating liquid preferably contains at least one type of macromer-modified acrylic surface conditioner as the acrylic surface conditioner. By using a macromer-modified acrylic surface conditioner as the water-based coating liquid, the surface free energy of the dry film can be improved, and as a result, repelling when the water-based color ink is printed can be prevented. The macromer-modified acrylic surface conditioner is a material produced by reacting an acrylic additive with a single-terminal reactive silicone (macromer). Macromer-modified acrylic surface conditioners are readily available on the market from Big Chemie Japan Co., Ltd.

Although it is preferable to use a surface conditioner for the water-based coating liquid and the water-based color ink so as to obtain a desired surface tension value, the content of the surface conditioner is 0.1 to 1 in each of the water-based coating liquid and the water-based color ink. It can be exemplified that it is 5.0% by mass.

In the ink set of the present invention, the water-based coating liquid and the water-based color ink are further subjected to a pH adjuster, a defoaming agent, a moisturizer, a wet dispersant, a preservative / antifungal agent, a dissolution aid, and an oxidation, if necessary. An inhibitor, a metal trapping agent, or the like may be appropriately selected and blended within a range that does not impair the object of the present invention.

In the ink set of the present invention, the water-based coating liquid and the water-based color ink can be prepared by mixing various components appropriately selected as necessary.
The water-based coating liquid preferably contains water in the range of 50% by mass to 90% by mass, an organic solvent in the range of 5% by mass to 35% by mass, and a resin in the range of 0.005% by mass to 5% by mass. Such an aqueous coating liquid having a small amount of resin dries quickly, and is preferable from the viewpoint of suppressing the generation of printing streaks after aggregation.

The water-based color ink and the water-based coating liquid are preferably basic from the viewpoint of suppressing the occurrence of corrosion in metal parts (particularly print heads) of printing equipment such as inkjet printers, and have a pH of 7.01 to 10.0. It is preferable that it is within the range of.
Although a pH adjusting agent can be used for adjusting the pH, it is preferable to use an amine compound, and it is more preferable to use an amine compound having a boiling point of 70 to 270 ° C. Specific examples of the amine compound having a boiling point of 70 to 270 ° C. include N-methyldiethanolamine, N-ethyldiethanolamine, N, N-dimethylethanolamine, N, N-diethylethanolamine and the like. These amine compounds may be used alone or in combination of two or more. The content of the amine compound in each of the water-based coating liquid and the water-based color ink is preferably 0.1 to 2.0% by mass.

In the ink set of the present invention, it is preferable that the water-based color ink and the water-based coating liquid each independently have a viscosity at 25 ° C. in the range of 3.0 to 10.0 mPa · s. In the present specification, the viscosities of the ink and the coating liquid are measured after adjusting the liquid temperature to 25 ° C. using a rheometer (for example, a rheometer ARES manufactured by TA Instruments).

In the ink set of the present invention, the surface tension value of the aqueous coating liquid at 25 ° C. is preferably 28.0 mN / m or less, and more preferably 27.0 mN / m or less. By setting the surface tension of the aqueous coating liquid to 28 mN / m or less, the cissing generated on the absorbent base material can be suppressed.
Further, in the ink set of the present invention, the surface tension value of the aqueous coating liquid at 25 ° C. is preferably 21.0 mN / m or more, and more preferably 24.0 mN / m or more. By setting the surface tension of the aqueous coating liquid to 21 mN / m or more, it is possible to suppress the permeation of the coating liquid into the substrate.

In the ink set of the present invention, since the water-based color ink is usually printed on the water-based coating liquid layer, the surface tension value at 25 ° C. is preferably 20.0 mN / m or more and 50.0 mN / m or less. ..

In the present specification, the "surface tension value" of the ink and the coating liquid refers to the surface tension value that has reached an equilibrium state (so-called static surface tension value), and is measured based on the plate method.
Since the color ink and the coating liquid used in the ink set of the present invention are both water-based and the surface tension value generally tends to be high, the type and content of the organic solvent and / or the surface conditioner (preferably silicone-based). It is important to adjust the surface tension value by appropriately adjusting the type and content of the additive containing the surface conditioner, more preferably the polyether-modified polysiloxane).

The printing method of the present invention is a printing method for printing using the ink set of the present invention described above, and includes the following first to fifth steps.
1st step: Preparing an absorbent base material 2nd step: Treating the surface of the absorbent base material with an aqueous coating liquid 3rd step: Drying the surface of the absorbent base material treated in the 2nd step 4th step Step: Treat the surface of the absorbent base material dried in the third step with a water-based coating liquid. Fifth step: Print on the surface of the absorbent base material treated in the fourth step with a water-based color ink.

The first step of the printing method of the present invention is a step of preparing an absorbent base material as a base material to be printed. The absorbent base material is a base material having absorbency to a water-based coating liquid or a water-based ink, and in the present specification, the presence or absence of absorbency can be determined by the following simple measurement method. Specifically, 10 mg of water is dropped on the base material, and after 10 seconds have passed, wiping is performed. At that time, it is confirmed whether or not there is a trace of water permeation, and if the trace of water permeation can be visually recognized, the base material is used as an absorbent base material. If the third and fourth steps, which will be described later, are not performed, the coating liquid permeates into the absorbent base material, so that the coating liquid cannot sufficiently agglomerate, and as a result, the color ink is fixed in a predetermined position. Can not do it.

In the printing method of the present invention, the absorbent base material may be a white base material. In the present specification, the "white base material" is a base material whose printed surface is at least white, and here, "white" refers to achromatic white, but is not limited to this, and has a slight tint such as beige or gray. Off-white with it is also included.

In the printing method of the present invention, specific examples of the absorbent white base material are mainly coated paper (specifically, resin coated paper), art paper, cast paper, finely coated paper, high-quality paper, synthetic paper, and inkjet. Examples thereof include paper base materials such as paper, but these paper base materials are particularly prone to shrinkage and bending due to permeation of the coating liquid, and therefore it is preferable to perform printing by the printing method of the present invention.

The second step of the printing method of the present invention is a step of treating the surface of the absorbent base material with a water-based coating liquid. The surface treatment of the absorbent base material with the water-based coating liquid can be performed by various printing means. Specific examples thereof include an inkjet printing method, a gravure printing method, an offset printing method, a flexographic printing method, a screen printing method, and a coater method.

In the second step, the temperature of the base material is preferably 30 to 50 ° C. When the temperature of the surface of the base material is 30 ° C. or higher, the wettability of the water-based coating liquid to the base material can be improved. Further, when the temperature is 50 ° C. or lower, it is possible to prevent the water-based coating liquid from drying at the head interface. The temperature of the base material is the temperature of the surface of the base material to which the aqueous coating liquid is applied. The temperature of the base material is preferably 30 to 50 ° C. throughout the entire steps from the second step to the fifth step.

In particular, the water-based coating liquid used in the second step preferably has a larger amount (treatment amount) than the water-based coating liquid used in the fourth step.

The third step of the printing method of the present invention is a step of drying the surface of the absorbent base material treated with the aqueous coating liquid in the second step. By drying the surface of such an absorbent base material, a water-soluble polymer having a cation can be attached on the absorbent base material. This makes it possible to prevent the water-based coating liquid used in the treatment of the fourth step from permeating the surface of the absorbent base material. Further, the water-soluble polymer having the dried cation does not have an action of aggregating the water-based coating liquid used in the treatment of the fourth step, and is present in the water-based coating liquid used in the treatment of the fourth step. Since it does not react with a water-soluble polymer having a cation, it is preferable as a resin to be adhered to an absorbent substrate.

In the third step, the drying is preferably performed by hot air. In this case, hot air (usually using air) is applied to the surface of the absorbent base material treated with the water-based coating liquid to perform drying. In the third step, the drying is preferably performed at 70 to 130 ° C, more preferably 80 to 110 ° C. Further, in the third step, the drying is preferably performed for 2 seconds or more and less than 120 seconds, and more preferably for 5 seconds or more and 60 seconds or less. The drying means is not particularly limited, but a dryer having a blowing function is preferable. Flow rate is preferably 1.0 m ³ / min or more, further preferably 1.5~5.0m ³ / min.

In the printing method of the present invention, the surface of the absorbent substrate dried in the third step preferably has a surface life of 100 ms and a dynamic contact angle of water at a temperature of 25.0 ° C. of 70 ° or less. It is more preferably 25 ° to 65 °. By setting the dynamic contact angle of water with respect to the absorbent base material after drying the surface of the absorbent base material treated with the water-based coating liquid within the above specific range, the water-based coating printed in the fourth step It is possible to create a substrate environment in which the liquid is hard to repel and easily wets and spreads, and as a result, a printed matter having a high degree of perfection can be produced at the time of printing the color ink in the fifth step. As a method for reducing the dynamic contact angle of water, for example, it is effective to increase the amount of the water-soluble polymer having a cation contained in the water-based coating liquid used in the second step.

In the printing method of the present invention, the surface of the absorbent substrate dried in the third step has a surface life of 100 ms and a temperature of 25 ° C. as compared with the surface of the absorbent substrate prepared in the first step. The dynamic contact angle of the water is low, and the difference is preferably 10 ° or more, and more preferably 15 ° to 60 °. The absorbent base material after drying the surface of the absorbent base material treated with the water-based coating liquid is water as compared with the absorbent base material prepared in the first step not treated with the water-based coating liquid. By setting the dynamic contact angle difference of the above within the above-mentioned specific range, it is possible to create a base material environment in which the water-based coating liquid printed in the fourth step is hard to repel and easily wets and spreads, and as a result, the color ink in the fifth step is used. It is possible to produce a printed matter having a high degree of perfection at the time of printing.

In the present specification, the dynamic contact angle of water can be measured by measuring the dynamic contact angle using a general contact angle meter (for example, DM700 manufactured by Kyowa Surface Chemistry Co., Ltd.). In the present specification, the contact angle is measured for a substrate at 25 ° C. with a surface life of 100 ms.
The dynamic contact angle measurement is obtained by bringing the liquid inserted into the syringe into contact with the base material and measuring the contact angle when the liquid lands on the base material in time units. By this measurement, it is possible to measure the contact angle of the droplet that spreads instantly and the change over time in the amount of liquid absorbed.

The reason why the surface life is set to 100 ms is that it is considered to be the most suitable timing for controlling the behavior of wetting and spreading from the impact of the ink. In high-speed printing with an inkjet printer, it takes about 10 to 100 ms from the landing of one dot to the completion of wet spreading, and the spreading behavior itself immediately after landing is developed on a very short scale. Since 100 ms is the timing at which the ink that has landed on the base material has just finished wetting and spreading, by controlling the dynamic contact angle value at this time to an appropriate value, wetting control due to contact of the water-based coating liquid with the base material is controlled. Is considered to be possible in the most suitable condition.

The fourth step of the printing method of the present invention is a step of treating the surface of the absorbent base material dried in the third step with a water-based coating liquid. A water-soluble polymer having a dried cation is present on the surface of the absorbent substrate dried in the third step, and the water-based coating liquid used in the fourth step is sufficiently wetted on the absorbent substrate. It is possible to spread. Therefore, it is possible to exert the agglutinating action of the coating liquid and fix the color ink in a predetermined position.

In the fourth step, the surface treatment of the absorbent base material with the water-based coating liquid can be performed by various printing means as in the second step. Specific examples thereof include an inkjet printing method, a gravure printing method, an offset printing method, a flexographic printing method, a screen printing method, and a coater method.

The water-based coating liquid used in the fourth step may be the same as or different from the water-based coating liquid used in the second step. In particular, the water-based coating liquid used in the fourth step preferably has a smaller amount of the water-soluble polymer having a cation contained in the water-based coating liquid than the water-based coating liquid used in the second step.

The fifth step of the printing method of the present invention is a step of printing with a water-based color ink on the surface of the absorbent base material treated with the water-based coating liquid in the fourth step. In the printing method of the present invention, from the viewpoint of sufficiently exerting the aggregating action of the coating liquid, the water-based coating liquid used in the fourth step is not waited for drying (that is, without drying the water-based coating liquid). It is preferable to print color ink. In the above printing method, the total thickness of the water-based coating liquid and the total discharge liquid of the water-based color ink immediately after the completion of printing (that is, before the water or the organic solvent evaporates) is within the range of 1 to 20 μm in total. Is preferable.

In the printing method of the present invention, when the water-based color ink is composed of a plurality of water-based color inks, the water-based color ink that is first printed on the coating liquid layer has a surface tension value at 25 ° C. among the plurality of water-based color inks. Is preferably the lowest. The water-based color ink that is first printed on the coating liquid layer is most strongly affected by the agglutination action of the color ink by the coating liquid. Therefore, by first printing the water-based color ink having the lowest surface tension value on the coating liquid layer, the cohesive action of the color ink by the coating liquid can be effectively exhibited.

In the fifth step, the printing of the water-based color ink is preferably performed by the inkjet printing method, but the printing is not limited to this, and the gravure printing method, the offset printing method, the flexo printing method, the screen printing method, and the coater. It can also be performed by various printing methods such as a method.

Further, the printing method of the present invention preferably further includes a step of drying the print layer (hereinafter, also referred to as a sixth step) after printing with the water-based color ink. By drying the printed layer formed on the substrate after the printing is completed, the resin contained in the printed layer can be fused onto the substrate to form a strong film, resulting in robustness. It is possible to provide excellent printed matter.

In the sixth step, the drying is preferably performed by hot air. By applying hot air (usually using air) to the printed layer to dry it, the resin contained in the layer can be fused to the substrate to form a strong film, resulting in robustness. It is possible to provide excellent printed matter. From the viewpoint of fusing the resin contained in the printing layer onto the substrate, the drying in the sixth step is preferably performed at 70 to 130 ° C., more preferably 80 to 110 ° C. Further, in the sixth step, the drying is preferably performed for 2 seconds or more and 20 seconds or less, and more preferably 5 seconds or more and 15 seconds or less. The drying means is not particularly limited, but a dryer having a blowing function is preferable. Flow rate is preferably 1.0 m ³ / min or more, further preferably 1.5~5.0m ³ / min.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.

<Water-based coating liquid>
Resins, amine compounds, water-soluble solvents, surface conditioners and ion-exchanged water were mixed by a known method to prepare aqueous coating solutions 1 to 30 according to the formulation shown in Tables 1 to 3. The pH, surface tension (25 ° C.), and viscosity (25 ° C.) of each aqueous coating liquid were measured, and the obtained results are shown in Tables 1 to 3.

The compounding agents listed in Tables 1 to 3 above are as follows.
* 1 The following was used as the aqueous solution A of the water-soluble polymer having a quaternary ammonium cation.
Catiomaster PE-30 (manufactured by Yokkaichi Synthetic, dimethylamine / ethylenediamine / epichlorohydrin-based polymer resin, resin content 50% by mass, weight average molecular weight (Mw): 9000, cation degree 6.5 meq / at pH 7.1 g)
* 2 The following was used as the aqueous solution B of the water-soluble polymer having a quaternary ammonium cation.
DK6851 (manufactured by Seiko PMC, polyamine resin, resin content 70.0% by mass, cation degree at pH 7.1, 6.8 meq / g)
* 3 The following was used as the aqueous solution C of the water-soluble polymer having a quaternary ammonium cation.
DK6864 (manufactured by Seiko PMC, polyamine resin, resin content 50.0% by mass, cation degree 6.5 meq / g at pH 7.1)
* 4 The following was used as the aqueous solution D of the water-soluble polymer having a primary cation.
PAA-SA (manufactured by Knitbo Medical, allylamine amide sulfate polymer resin, resin content 20% by mass, Mw: 12,000, cation degree at pH 7.1, 5.8 meq / g)
* 5 The following was used as the resin dispersion liquid E.
NEOREZ R-9621 (manufactured by DSM Coating Resins, polyester group-containing self-dispersing urethane resin, particle size 50 nm, acid value 18, resin content 38% by mass)
* 6 The following was used as the dispersion liquid F of the resin having cationic properties.
Superflex 650 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., cationic polycarbonate urethane resin dispersion, resin content 28% by mass, cationic content 0.8 meq / g at pH 7.1)
* 7 The following was used as the resin aqueous solution G.
Hi-Loss X AW-36H (manufactured by Seiko PMC, water-soluble acrylic resin, no particle size, acid value 60, resin content 25% by mass)
* 8 Twin 4100 (manufactured by EVONIK, polyether-modified silicone oil, silicone oil content 100% by mass, surface conditioner)
* 9 BYK 349 (manufactured by BYK, polyether-modified silicone oil, silicone oil content 100% by mass, surface conditioner)
* 10 Orphine D-10PG (manufactured by Nissin Chemical Industry Co., Ltd., acetylene glycol-based surfactant, surfactant content 50% by mass, surface conditioner)
* 11 Surfinol 107L (manufactured by Nissin Chemical Industry Co., Ltd., acetylene glycol-based surfactant, surfactant content 50% by mass, surface conditioner)
* 12 BYK3550 (manufactured by BYK, silicon macromer-modified acrylic surfactant, surfactant content 100% by mass, surface conditioner)
* 13 BYK3566 (manufactured by BYK, silicon macromer-modified acrylic surfactant, surfactant content 100% by mass, surface conditioner)
* 14 S-242 (manufactured by AGC Seimi Chemical Co., Ltd., fluorine-based surfactant, surfactant content 100% by mass, surface conditioner)

<Preparation example of water-based color ink containing self-dispersing pigment>
According to the formulation shown in Table 4, a self-dispersing pigment, a resin, a water-soluble solvent, a surface conditioner and ion-exchanged water were mixed by a known method to prepare a water-based color ink containing the self-dispersing pigment. The surface tension value (25 ° C.) and viscosity (25 ° C.) of each water-based color ink were measured, and the obtained results are shown in Table 4.

The compounding agents listed in Table 4 above are as follows. The combination drug already described will be omitted.
* 15 The following were used as the self-dispersing pigment dispersion.
・ CAB-O-JET 250C
(Cabot, self-dispersing pigment aqueous dispersion of cyan, pigment content 10% by mass)
・ CAB-O-JET-465M
(Cabot's self-dispersing pigment aqueous dispersion of magenta, pigment content 15% by mass)
・ CAB-O-JET 270Y
(Cabot, yellow self-dispersing pigment aqueous dispersion, pigment content 10% by mass)
・ CAB-O-JET 300K
(Cabot, black self-dispersing pigment aqueous dispersion, pigment content 15% by mass)
* 16 WET280 (manufactured by EVONIC, polyether-modified silicone-based surfactant, surfactant content 100% by mass, surface conditioner)

<Water-based color ink containing non-self-dispersing pigment>
According to the formulation shown in Table 5, a resin and a surface conditioner were added to an aqueous coloring dispersion in which a non-self-dispersing pigment, a defoaming agent, a water-soluble solvent, a wet dispersant, and ion-exchanged water were dispersed by a known method. A water-based color ink containing a non-self-dispersing pigment was prepared. The surface tension value (25 ° C.) and viscosity (25 ° C.) of each water-based color ink were measured, and the obtained results are shown in Table 5.

The compounding agents listed in Table 5 above are as follows. The combination drug already described will be omitted.
* 17 The following were used as the non-self-dispersing pigment.
・ FASTOGEN Blue FA5380 (phthalocyanine blue, cyan pigment manufactured by DIC Corporation)
・ Shinkasha Magenta RT (dichloroquinacridone, BASF magenta color pigment)
-Hostaperm Yellow H5G (Quinoxaline Zion, yellow pigment manufactured by Clariant)
・ Neurox-1000 (carbon black, manufactured by Orion Engineer Lido Carbon Co., Ltd., black pigment)
* 18 SN Deformer 1312 (manufactured by San Nopco, antifoaming agent, component content 100% by mass)
* 19 Neugen E-157 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., wet dispersant, component content 100% by mass)

<Printability>
The ink sets shown in Tables 6 to 16 were prepared and the printability was evaluated.
Using Stage JET manufactured by Tritech, first, the aqueous coating liquid used in the second step shown in Tables 6 to 16 was discharged in a single pass at a transport speed of 12 pL and 25 m / min under high-speed printing conditions, and 100%. Top coat plus (manufactured by Oji Paper Mills, basis weight 127.9 g / m ² ), multicolor foam gloss (manufactured by Oji Paper ^{Mills, basis weight 157.0 g / m 2} ), and Word ijet 4.3 Printing was performed on the surface of a base material of gross (manufactured by Mitsubishi Paper Mills Limited, basis weight 127.9 g / m ^2). After printing the aqueous coating liquid, it was dried at the temperatures and times shown in Tables 6 to 16 using a drying oven having a variable temperature. Then, the water-based coating liquid used in the fourth step shown in Tables 6 to 16 was discharged in a single pass at a transport speed of 12 pL and 25 m / min under high-speed printing conditions, and a 50% solid image was printed on the dried substrate surface. (However, in Comparative Example 1, printing was performed on the surface of the base material without drying), and then the printed water-based coating liquid was not dried, and the black ink was removed on the landed water-based coating liquid. Ink, magenta ink, and yellow ink droplets are ejected and landed in a single pass according to the order of the color ink sets shown in Tables 6 to 16 at a transport speed of 12 pL under high-speed printing conditions of 25 m / min. Solid printing was performed with a print density of 80% for each of the yellow inks and a total print density of 240%, and 100% solid printing was also performed for each of the cyan ink, magenta ink, and yellow ink. Then, it dried at a temperature of 100 degreeC for 5 minutes. The printed portion was visually evaluated according to the following evaluation criteria. The resolution of each water-based coating liquid and water-based color ink was set to vertical × horizontal = 600 × 600 dpi. Tables 6 to 16 show the configurations and evaluation results of the ink sets used.
◯: No bleeding or streaks are observed in the solid printing of each color and the solid printing of three colors.
Δ: Blurring or streaks are observed in the solid printing of each color and the solid printing of three colors.
X: Blurring and streaks are observed in the solid printing of each color and the solid printing of three colors.

<Scratch resistance>
The ink sets shown in Tables 6 to 16 were prepared and the scratch resistance was evaluated.
Using Stage JET manufactured by Tritech, first, the aqueous coating liquid used in the second step shown in Tables 6 to 16 was discharged in a single pass at a transport speed of 12 pL and 25 m / min under high-speed printing conditions, and 100%. Top coat plus (manufactured by Oji Paper Mills, basis weight 127.9 g / m ² ), multicolor foam gloss (manufactured by Oji Paper ^{Mills, basis weight 157.0 g / m 2} ), and Word ijet 4.3 Printing was performed on the surface of a base material of gross (manufactured by Mitsubishi Paper Mills Limited, basis weight 127.9 g / m ^2). After printing the aqueous coating liquid, it was dried at the temperatures and times shown in Tables 6 to 16 using a drying oven having a variable temperature. Then, the water-based coating liquid used in the fourth step shown in Tables 6 to 16 was discharged in a single pass at a transport speed of 12 pL and 25 m / min under high-speed printing conditions, and a 50% solid image was printed on the dried substrate surface. (However, in Comparative Example 1, printing was performed on the surface of the base material without drying), and then the printed water-based coating liquid was not dried, and the black ink was removed on the landed water-based coating liquid. Ink, magenta ink, and yellow ink droplets are ejected and landed in a single pass according to the order of the color ink sets shown in Tables 6 to 16 at a transport speed of 12 pL under high-speed printing conditions of 25 m / min. Solid printing was performed with a print density of 80% for each of the yellow inks and a total print density of 240%. Then, it dried at a temperature of 100 degreeC for 5 minutes. The printed portion was rubbed 5 times with a cotton swab (registered trademark, manufactured by Hakujuji Co., Ltd.) and visually evaluated according to the following evaluation criteria. The resolution of each water-based coating liquid and water-based color ink was set to vertical × horizontal = 600 × 600 dpi. Tables 6 to 16 show the configurations and evaluation results of the ink sets used.
◯: Ink does not adhere to the cotton swab.
Δ: Ink adheres to the cotton swab, but the ink does not come off from the base material.
X: Ink adheres to the cotton swab and the ink peels off from the base material.

<Color development>
The ink sets shown in Tables 6 to 16 were prepared and the color development was evaluated.
Using Stage JET manufactured by Tritech, first, the aqueous coating liquid used in the second step shown in Tables 6 to 16 was discharged in a single pass at a transport speed of 12 pL and 25 m / min under high-speed printing conditions, and 100%. Top coat plus (manufactured by Oji Paper Mills, basis weight 127.9 g / m ² ), multicolor foam gloss (manufactured by Oji Paper ^{Mills, basis weight 157.0 g / m 2} ), and Word ijet 4.3 Printing was performed on the surface of a base material of gross (manufactured by Mitsubishi Paper Mills Limited, basis weight 127.9 g / m ^2). After printing the aqueous coating liquid, it was dried at the temperatures and times shown in Tables 6 to 16 using a drying oven having a variable temperature. Then, the water-based coating liquid used in the fourth step shown in Tables 6 to 16 was discharged in a single pass at a transport speed of 12 pL and 25 m / min under high-speed printing conditions, and a 50% solid image was printed on the dried substrate surface. (However, in Comparative Example 1, printing was performed on the surface of the base material without drying), and then the printed water-based coating liquid was not dried, and the black ink was removed on the landed water-based coating liquid. Ink, magenta ink, and yellow ink droplets are ejected and landed in a single pass according to the order of the color ink sets shown in Tables 6 to 16 at a transport speed of 12 pL under high-speed printing conditions of 25 m / min. Solid printing was performed with a print density of 80% for each of the yellow inks and a total print density of 240%. Then, it was dried at a temperature of 100 degreeC for 5 minutes, and a printed image was prepared.
For comparison, printing is performed in the same manner as described above except that the water-based coating liquid in the second step shown in Tables 6 to 16 is not printed, and then dried at a temperature of 100 ° C. for 5 minutes. An image was created.
The printed portion of the printed image and the comparative image was visually evaluated according to the following evaluation criteria. The resolution of each water-based coating liquid and water-based color ink was set to vertical × horizontal = 600 × 600 dpi. Tables 6 to 16 show the configurations and evaluation results of the ink sets used.
◯: The printed image has a clearer color than the comparison image.
Δ: The color of the printed image is about the same as that of the comparison image.
X: A state in which the printed image is inferior in color development to the comparison image or a different color is formed.

<Dynamic contact angle 1>
The ink sets shown in Tables 6 to 16 were prepared and the dynamic contact angle was evaluated.
Using Stage JET manufactured by Tritech, the water-based coating liquid used in the second step shown in Tables 6 to 16 is discharged in a single pass at a transport speed of 12 pL and 25 m / min under high-speed printing conditions, and is 100% solid. The image is OK Top Coat Plus (manufactured by Oji Paper Mills, basis weight 127.9 g / m ² ), multicolor foam gloss (manufactured by Oji Paper ^{Mills, basis weight 157.0 g / m 2} ), and Word ijet 4.3 gloss (manufactured by Oji Paper Mills, basis weight 157.0 g / m 2). Printing was performed on the surface of a base material manufactured by Mitsubishi Paper Mills Limited and having a basis weight of 127.9 g / m ^2). After printing the aqueous coating liquid, it was dried at the temperatures and times shown in Tables 6 to 16 using a drying oven having a variable temperature. Next, using DM700 manufactured by Kyowa Surface Chemistry Co., Ltd., the dynamic contact angle of ion-exchanged water at a surface life of 100 ms and a temperature of 25 ° C. was measured with respect to the dried substrate. The evaluation criteria are as follows. The evaluation results are shown in Tables 6 to 16.
⊚: Dynamic contact angle is 60 ° or less ○: Dynamic contact angle is greater than 60 ° and 70 ° or less Δ: Dynamic contact angle is greater than 70 ° and 80 ° or less ×: Dynamic contact angle is greater than 80 ° large

<Dynamic contact angle 2>
The ink sets shown in Tables 6 to 16 were prepared and the dynamic contact angle was evaluated.
Using Stage JET manufactured by Tritech, the water-based coating liquid used in the second step shown in Tables 6 to 16 is discharged in a single pass at a transport speed of 12 pL and 25 m / min under high-speed printing conditions, and is 100% solid. The image is OK Top Coat Plus (manufactured by Oji Paper Mills, basis weight 127.9 g / m ² ), multicolor foam gloss (manufactured by Oji Paper ^{Mills, basis weight 157.0 g / m 2} ), and Word ijet 4.3 gloss (manufactured by Oji Paper Mills, basis weight 157.0 g / m 2). Printing was performed on the surface of a base material manufactured by Mitsubishi Paper Mills Limited and having a basis weight of 127.9 g / m ^2). After printing the aqueous coating liquid, it was dried at the temperatures and times shown in Tables 6 to 16 using a drying oven having a variable temperature. Next, using DM700 manufactured by Kyowa Surface Chemistry Co., Ltd., the dynamic contact angle of ion-exchanged water at a surface life of 100 ms and a temperature of 25 ° C. was measured with respect to the dried substrate. In addition, the same measurement was performed for the base material (base material itself) on which the water-based coating liquid was not printed as a comparison. The evaluation criteria are as follows. The evaluation results are shown in Tables 6 to 16.
⊚: The dynamic contact angle of the base material surface-treated with the water-based coating liquid is 20 ° or more smaller than that of the base material not treated. ○: The dynamic contact angle of the base material surface-treated with the water-based coating liquid is treated. 10 ° or more and smaller than 20 ° than the untreated substrate Δ: The dynamic contact angle of the substrate surface-treated with the water-based coating liquid is 5 ° or more and smaller than 10 ° than the untreated substrate × : The dynamic contact angle of the base material surface-treated with the water-based coating liquid is smaller than that of the untreated base material by 5 °.

<Dischargeability>
Using the Stage JET manufactured by Tritech, first, the printer is filled with the water-based coating liquid used in the second step shown in Tables 6 to 16, and then landed on a transparent OHP sheet, and the check pattern is read into the device. Was printed (step A). Next, the same water-based coating liquid as in step A was discharged, and 12 pL 100% solid printing equivalent to ^{25 m 2 was performed.} Then, the same water-based coating droplet as in step A was landed on the transparent OHP sheet, and the same check pattern as in step A loaded in the apparatus was printed (step B). Each OHP sheet on which the check pattern was printed was visually confirmed in step A and step B, and the proportion of pins missing from the check pattern was evaluated. The evaluation criteria are as follows. The evaluation results are shown in Tables 6 to 16.
◯: There is no non-ejection in the check pattern printed in step A, and the proportion of pins missing from the check pattern printed in step B is less than 5%.
Δ: There is no non-ejection in the check pattern printed in step A, and the proportion of pins missing from the check pattern printed in step B is 5% or more and less than 30%.
X: There is no non-ejection in the check pattern printed in step A, and the proportion of pins missing from the check pattern printed in step B is 30% or more.

<Storage stability>
Take 100 g of the aqueous coating liquid used in the second step shown in Tables 6 to 16 in a 110 cc glass bottle, store at 60 ° C. for 4 weeks, and measure the viscosity, surface tension, specific gravity, and pH before and after storage. It was. The results were compared. The evaluation criteria are as follows. The evaluation results are shown in Tables 6 to 16.
◯: Change rate of 10% or less for all items Δ: Change rate of more than 10% and less than 20% for any one item ×: Change rate of 20% or more for any one item

Claims (13)

A printing method using an ink set containing a water-based color ink and a water-based coating liquid having an action of aggregating the water-based color ink.
The first step of preparing the absorbent substrate and
The second step of treating the surface of the absorbent base material with the water-based coating liquid, and
The third step of drying the surface of the absorbent base material treated in the second step, and
The fourth step of treating the surface of the absorbent base material dried in the third step with the water-based coating liquid, and the fourth step.
The fifth step of printing with the water-based color ink on the surface of the absorbent base material treated in the fourth step is included.
Here, the printing method, wherein the water-based coating liquid contains at least water, a resin, and an organic solvent, and the resin contains a water-soluble polymer having a cation. The printing method according to claim 1, wherein the content of the water-soluble polymer having a cation in the water-based coating liquid is 0.5 to 8.0% by mass. The printing method according to claim 1 or 2, wherein the organic solvent contains at least one kind of alkanediol-based solvent. The printing method according to any one of claims 1 to 3, wherein the water-soluble polymer having a cation has a weight average molecular weight of 1,000 or more. The printing method according to any one of claims 1 to 4, wherein the water-soluble polymer having a cation has a weight average molecular weight of 100,000 or less. The printing method according to any one of claims 1 to 5, wherein the water-based coating liquid further contains at least one kind of silicone-based surface conditioner. The printing method according to any one of claims 1 to 6, wherein the water-based coating liquid has a surface tension value of 28.0 mN / m or less at 25 ° C. The printing method according to any one of claims 1 to 7, wherein the water-based coating liquid has a surface tension value of 21.0 mN / m or more at 25 ° C. The printing method according to any one of claims 1 to 8, wherein the water-based coating liquid further contains at least one kind of macromer-modified acrylic surface conditioner. The printing method according to any one of claims 1 to 9, wherein drying is performed at 70 to 130 ° C. in the third step. The printing method according to any one of claims 1 to 10, wherein drying is performed for 2 seconds or more and less than 120 seconds in the third step. Any of claims 1 to 11, wherein the surface of the absorbent base material dried in the third step has a surface life of 100 ms and a dynamic contact angle of water at a temperature of 25 ° C. of 70 ° or less. The printing method described in item 1. The surface of the absorbent substrate dried in the third step has a surface life of 100 ms and a dynamic contact angle of water at a temperature of 25 ° C. as compared with the surface of the absorbent substrate prepared in the first step. The printing method according to any one of claims 1 to 12, wherein the difference between the two is 10 ° or more.