JP7304784B2 - printing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a printing method, and more particularly to a printing method that enables good printing on absorbent substrates such as coated paper, fine paper, and art paper.

Various inks have been developed as inks used for printing by inkjet printers, but water-based inks are widely used from the viewpoint of reducing environmental impact. However, since water-based ink contains water as a solvent, it tends to cause bleeding during printing. As a method for improving bleeding of a printed layer formed by printing, for example, a method of using a treatment liquid having an action of aggregating colored ink together is known (for example, JP-A-6-57192 and JP-A-6-57192 and JP-A-6-57192). 2009-190379).

Regarding a water-based ink set containing a colored ink and a treatment liquid, JP-A-2017-222793 discloses an ink set containing a water-based colored ink and a water-based coating liquid, wherein the water-based colored ink comprises water and a self-dispersible pigment. , containing a water-soluble solvent and a resin, the water-based coating liquid containing water, a water-soluble solvent and a resin, the resin contained in the water-based coating liquid containing a water-soluble polymer having a quaternary ammonium cation, the water-based An ink set is described in which the pH of the coating liquid is in the range of 7.1 to 10.0.

JP-A-6-57192 JP 2009-190379 A JP 2017-222793 A

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

However, as a result of further studies by the present inventors, it was found that the water-based ink set described in Patent Document 3 is sufficiently compatible with printing on non-absorbent substrates such as polyethylene terephthalate (PET) films. However, on absorbent substrates such as coated paper, high-quality paper, and art paper, there is a problem that good printing cannot be performed due to the occurrence of streaks and bleeding, and there is room for improvement. Specifically, in printing on a PET film, since the coating liquid spreads sufficiently on the film, it is possible to fix the color ink to be printed later in a predetermined position. On the other hand, in printing on coated paper, the coating liquid permeates the base material and cannot spread sufficiently. In this case, there is a problem that the coating liquid cannot sufficiently exert its aggregating action, and as a result, the color ink cannot be fixed at a predetermined position.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a printing method that solves the above-described problems of the prior art and enables good printing on absorbent substrates such as coated paper, high-quality paper, and art paper. It is in.

As a result of intensive studies to achieve the above object, the present inventors have found that when the surface of the absorbent substrate is treated with the coating liquid, the coating liquid on the absorbent substrate is dried once, and then the absorbent The inventors have found that when the surface of the substrate is treated again with the coating liquid, the coating liquid spreads sufficiently and the surface of the absorbent substrate can be uniformly treated, leading to the completion of the present invention.

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,
a first step of providing an absorbent substrate;
a second step of treating the surface of the absorbent substrate with the water-based coating liquid;
a third step of drying the surface of the absorbent substrate treated in the second step;
A fourth step of treating the surface of the absorbent substrate dried in the third step with the water-based coating liquid;
and a fifth step of printing with the water-based color ink on the surface of the absorbent substrate treated in the fourth step,
Here, 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.

In a preferred embodiment 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 embodiment of the printing method of the present invention, the organic solvent contains at least one alkanediol solvent.

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

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

In another preferred embodiment of the printing method of the present invention, the water-based coating liquid further contains at least one silicone-based surface conditioner.

In another preferred embodiment 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 embodiment 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 embodiment of the printing method of the present invention, the water-based coating liquid further contains at least one macromer-modified acrylic surface conditioner.

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

In another preferred embodiment 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 embodiment 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 of 70° or less at a temperature of 25°C.

In another preferred embodiment of the printing method of the present invention, the surface of the absorbent substrate dried in said third step has a surface lifetime of 100 ms compared to the surface of the absorbent substrate prepared in said first step. and the difference in 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 absorbent substrates such as coated paper, fine 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 this 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 to color the base material and draw letters, images, etc. Usually, water, resin , organic solvents and colorants. The water-based coating liquid is used for treating the surface of the base material and is a liquid for aggregating the water-based color ink to be printed afterward, 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 cations.

In this specification, a composition containing more than 0.1% by mass of a coloring agent is referred to as "ink", and a composition that does not contain a coloring agent or contains 0.1% by mass or less of a coloring agent is simply referred to as "liquid". is expressed as Further, in this specification, "aqueous color ink" and "aqueous 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 inks may consist of a plurality of water-based color inks emitting different colors, and include at least four kinds of inks: cyan ink, magenta ink, yellow ink, and black ink. can be exemplified. Unlike water-based color inks, water-based coating liquids are often used alone, but in the printing method of the present invention, a two-step process using water-based coating liquids is performed, so multiple water-based coating liquids with different compositions can be used. may be used.

In the ink set of the present invention, the water-based color ink and the water-based coating liquid contain water, and suitable examples include pure water such as ion-exchanged water and distilled water, ultrapure water, and the like. Further, when the ink or coating liquid is to be stored for a long period of time, water sterilized by ultraviolet irradiation or the like may be used in order to prevent the generation of mold or bacteria. Here, in each of the water-based color ink and the water-based coating liquid, the water content can be exemplified as being 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 within the range of 80% by mass. As a result, it is possible to provide color inks and coating liquids that are less harmful to 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 the color ink. As a result, the adhesion of the printed layer to the base material can be improved while suppressing the bleeding of the printed layer, and high-speed printing becomes possible. Moreover, if it is a cation, it can exhibit the ability to coagulate the color ink even if it is present in the aqueous coating liquid whose pH is in the basic range. However, the above water-soluble polymer has a high ability to coagulate the color ink, and causes the coagulation of the color ink to occur remarkably early, which may reduce the glossiness of the printed layer. preferable. Moreover, the water-based coating liquid prepared using a water-soluble polymer having a cation maintains its viscosity and pH even when stored for a long period of time, and exhibits excellent storage stability.
In this specification, a water-soluble polymer means a polymer that dissolves in water or an aqueous solution containing less than 50% by mass of a water-soluble organic solvent.

The water-soluble polymer having a 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, bleeding of the printed layer is further suppressed, and the abrasion resistance of the printed layer and the storage stability of the aqueous coating liquid are improved.

The weight-average molecular weight of the cation-containing water-soluble polymer is preferably 1,000 or more, more preferably 2,500 or more, and even more 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 ensure that the polymer exists on the substrate, and as a result, it is possible to prevent repelling of the water-based coating liquid and water-based color ink. can. On the other hand, the water-soluble polymer having a cation preferably has a weight average molecular weight of 100,000 or less, more preferably 50,000 or less, even more preferably 45,000 or less. The following are particularly preferred. 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 developability can be improved. On the other hand, if the weight-average molecular weight of the cation-containing water-soluble polymer is too high, the dot diameter tends to be small, resulting in streaks on printed matter. Also, when the weight average molecular weight is high, the adhesion of the printed layer of the color ink may be reduced due to the formation of a layer of polymer having cations.
In this 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 its 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 instantly aggregates, preventing the water-based color inks from mixing with each other. Since it is fixed at the printed position, it is more preferable in the case of performing high-speed printing.

The water-soluble polymer having a cation is preferably two or more water-soluble polymers having different cationic degrees. By using a plurality of water-soluble polymers with different cationic degrees, it becomes easy to adjust the size of the dot diameter and bleeding.
Specifically, the water-soluble polymer having the above cations includes a water-soluble polymer having a cationic degree of 5.5 to 7.5 meq/g at pH 7.1 and a water-soluble polymer having a cationic degree of 2.0 to 5 meq/g at pH 7.1. a water-soluble polymer having a cationic degree at pH 7.1 of 6.0 to 7.0 meq/g and a cationic degree at pH 7.1 of 2.0 meq/g. and a water-soluble polymer that is between 5 and 4.5 meq/g. The ratio of the water-soluble polymer having two types of cationic degree ranges is such that the mass ratio of the water-soluble polymer with a high cationic degree range: the water-soluble polymer with a low cationic degree range is in the range of 1:1 to 20:1. preferably within the range of 7:3 to 10:1.
In this specification, the degree of cation can be determined by colloidal titration using a polyvinyl potassium sulfate reagent. The detailed procedure is as follows.
90 mL of deionized water is placed in a conical beaker, 10 mL of a 500 ppm aqueous solution of the sample (on a dry basis) is added, adjusted to pH 7.1 with an aqueous amine solution, and stirred for about 1 minute. Then add 2-3 drops of toluidine blue indicator and titrate with N/400 polyvinyl potassium sulfate reagent (N/400 PVSK). The titration rate is 2 mL/min, and the end point is when the color of the test water changes from blue to reddish purple and is maintained for 10 seconds or more. The formula for calculating the degree of cation (meq/g) is as follows.
Cationic degree = (N/400 PVSK titer) x (N/400 PVSK titer)/2

A commercially available product can be used as the water-soluble polymer having the above cation. Among them, a water-soluble polymer having a quaternary ammonium cation is preferable, but from the viewpoint of stably existing even in basic conditions, for example, DK6810, DK6851, DK6864, WS4030, WS4027, WS4052, CA6018 (manufactured by Seiko PMC), Hersize CP-300, CP-800 (manufactured by Harima Chemicals), PAS-H-1L, PAS-H-5L, PAS-2401, PAS-A-1 (manufactured by Nitbo Medical), Catiomaster PDT -2, PD-7, PD-30 (manufactured by Yokkaichi Gosei Co., Ltd.). The water-soluble polymer having the cation may be used singly or in combination of two or more.

In the water-based coating liquid, the content of the water-soluble polymer having a 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 tint of the color ink can be prevented from being impaired.

Other resins that can be used in the water-based coating liquid include resins commonly used in the ink industry other than the water-soluble polymer having a cation. Examples include acrylic resins, silicone resins, acrylic silicone resins, styrene-acrylic copolymer resins, polyester resins, rosin resins, phenolic resins, urethane resins, melamine resins, urea resins, epoxy resins, cellulose resins, butyral resins, maleic acid resins, and fumaric resins. acid resins, vinyl resins, and the like. These resins may be used individually by 1 type, and may be used in combination of 2 or more types.

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

In the water-based coating liquid, the content of the resin can be exemplified to be 0.005 to 15% by mass, preferably 0.5 to 10% by mass, and 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, resins that are commonly used in the ink industry can be used for the water-based color inks. , rosin resin, petroleum resin, coumarone resin, phenolic 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 resins, and the like. These resins may be used individually by 1 type, and may be used in combination of 2 or more types.

The resin that can be used in the water-based color ink can contain a self-dispersing resin. A self-dispersing resin is a resin that can maintain a dispersed state in an ink without using a surfactant or an emulsifier. A polymer having a group at its terminal or side chain, a polymer having a hydrophilic group such as a polycarbonate group, a polyester group, or a polyether group in its main chain, and the like are preferably used. These self-dispersible resins may be used singly or in combination of two or more. In addition, self-dispersing resin may use a commercial item.

The self-dispersing resin preferably contains a self-dispersing urethane resin from the viewpoint of improving the performance of the printed layer such as scratch resistance and water resistance, and from the viewpoint of imparting high adhesion to various substrates. , a polyester group- or polyether group-containing self-dispersible urethane resin. The proportion of the self-dispersing urethane resin in the self-dispersing 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 more preferred. If the weight-average molecular weight of the self-dispersible urethane resin is within the specified range, the abrasion resistance can be further improved, and a strong printed layer can be formed.
In this 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 polyester polyol, polyether polyol, polycarbonate polyol, etc., a polyisocyanate component, and optionally a chain extender.

The polyester polyol is not particularly limited, and examples thereof include polyethylene adipate, polyethylene propylene adipate, polybutylene adipate, polyhexamethylene adipate, polydiethylene adipate, polyethylene terephthalate, polyethylene isophthalate, polyhexamethylene isophthalate, polyethylene succinate, poly Butylene succinate, polyethylene sebacate, polybutylene sebacate, poly-ε-caprolactamdiol, poly(3-methyl-1,5-pentylene adipate) and the like can be mentioned. A polyester group-containing self-dispersible urethane resin can be obtained by using a polyester polyol as the polyol component. Since such resins are dispersed in the ink in the form of particles, they are 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. A polyether group-containing self-dispersible urethane resin can be obtained by using a polyether polyol as the polyol component. Since such resins are dispersed in the ink in the form of particles, they are also referred to as polyether urethane resin particles 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-dispersible urethane resin can be obtained. Since such resins are dispersed in the ink in the form of particles, they are also referred to herein as polycarbonate urethane resin particles.
As the polyol component, acrylic polyol or the like may be used.
These polyol components can be used singly or in combination of two or more.

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

Examples of chain extenders 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, penta dimethylolalkanoic acids such as erythritol, 1,4-cyclohexanedimethanol, dimethylolbutanoic acid and dimethylolpropionic acid; Examples of low-molecular-weight polyamines include ethylenediamine, trimethylenediamine, tetramethylenediamine, hexamethylenediamine, hydrazine, piperazine, isophoronediamine, norbornanediamine, diaminodiphenylmethane, diaminocyclohexylmethane, tolylenediamine, xylenediamine, diethylenetriamine, triamine. ethylenetetramine, tetraethylenepentamine, iminobispropylamine and the like. These chain extenders can be used singly or in combination of two or more.

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

The self-dispersing resin is dispersed in the ink and is in the form of particles. Here, the average particle diameter (D50) of the self-dispersing resin is preferably 10 nm to 90 nm, more preferably 20 nm to 70 nm, even more preferably 30 nm to 60 nm. When the average particle size is within the specified range, an ink can be prepared in which the self-dispersing resin is well dispersed and the storage stability is excellent.
As used herein, the average particle size (D50) refers to the 50% particle size (D ₅₀ ) of the volume-based particle size distribution, and is measured by a laser diffraction/scattering particle size distribution analyzer (eg, SALD-7000: manufactured by Shimadzu Corporation). ) can be determined from the particle size distribution measured using The particle diameter in this specification is represented by a sphere-equivalent diameter according to a laser diffraction/scattering method.

The self-dispersing resin preferably has an acid value of 5.0 to 60.0. If the acid value is within the range specified above, the dispersibility can be improved. As used herein, the acid value of a resin means mg of potassium hydroxide required to neutralize 1 g of resin.

In the ink set of the present invention, by adjusting the acid value of the self-dispersible 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, It is possible to increase the dot diameter and form a highly glossy printed layer that does not cause bleeding. Here, the ratio (C:D) of the acid value (C) of the self-dispersing resin and the cationic degree (meq/g) (D) of the cationic polymer at pH 7.1 is 10:1 to 1:2. is preferably within the range of , more preferably within the range of 6:1 to 1.2:3, and even more preferably within the range of 3:1 to 1:1.

The resin content in the water-based color ink is preferably 1 to 10% by mass. Moreover, the proportion of the self-dispersible 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 that are commonly used as colorants in the ink industry can be used. is preferred. A self-dispersing pigment is a pigment that can maintain a dispersed state in ink without using a pigment dispersant, and is usually obtained by imparting a highly hydrophilic functional group to the surface. The present inventors believe that the combination of a water-soluble polymer having the above-described cations, particularly a water-soluble polymer having a quaternary ammonium cation, and a self-dispersing pigment, causes aggregation to occur too quickly, resulting in the surface of the printed layer. It has been found that it is possible to prevent the formation of unevenness, thereby preventing the decrease in glossiness of the printed layer.

In the present invention, the self-dispersible pigment is preferably a pigment having anions such as carboxyl ions, sulfate ions, nitrate ions, phosphate ions, and hydroxide ions directly bonded to the surface. By using such an anionic 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 suitably used as these anionic self-dispersing pigments.

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 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; 26, 27, 28, Pigment White 6 and the like. In addition, these pigments may be used individually by 1 type, and may be used in combination of 2 or more types.
Examples of pigments that can be used in 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. ,
Pigments that can be used in magenta ink include, for example, 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 in 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 in black ink include Pigment Black 1, 7, 26, 27, and 28.
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 Brown 23, 25, 26; Pigment White 6 and the like can be used for the basic color inks, and can also be used for special color inks such as orange ink, violet ink, green ink, and red ink.

The content of the pigment in the water-based color ink can be arbitrarily determined depending on the type of pigment used, 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 organic solvents commonly used in the ink industry can be used. In each of the water-based coating liquid and the water-based color ink, the content of the organic solvent can be exemplified as 5 to 49% by mass, preferably 5 to 35% by mass, more preferably 10 to 35% by mass. , particularly preferably within a low range of 15 to 35% by weight. As a result, it is possible to provide water-based coating liquids and water-based color inks with less environmental impact, and since organic solvents are less likely to remain in the formed film, physical properties such as abrasion resistance are improved. easier. In addition, an organic solvent may be used individually by 1 type, and may be used in combination of 2 or more types.

The organic solvent that can be used for 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 alkanediol solvent, particularly at least two alkanediol solvents. By using an alkanediol-based solvent, it is possible to prevent drying of the ink at the ejection part (especially the print head) of printing equipment such as inkjet printers, and as a result, it is possible to improve the storage stability, wettability and ejection stability of the ink. can. The content of the alkanediol solvent in each of the water-based coating liquid and the water-based color ink is preferably 5.0 to 40.0% by mass.

Organic solvents that can be used for water-based coating liquids and water-based color inks include alkanediol-based solvents, glycol ether-based solvents, and 3- to 5-membered organic solvents from the viewpoint of improving ink ejection stability, wettability, and storage stability. It preferably contains at least one selected from the group consisting of cyclic lactone solvents and amide solvents.
Here, in the ink set of the present invention, from the viewpoint of adjusting the dynamic surface tension values of the color inks and the coating liquid, the water-based coating liquid and the water-based color ink independently contain an alkanediol-based solvent and a glycol ether-based solvent. It preferably contains at least one (preferably at least two) selected from the group consisting of solvents, and in particular from the viewpoint of adjusting the surface tension value of the coating liquid, it contains both an alkanediol-based solvent and a glycol ether-based solvent. is preferred. 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.

Alkanediol solvents are acyclic saturated hydrocarbons having two hydroxyl groups, such as 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. 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 preferred. .

Specific examples of glycol ether 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. Glycol benzyl 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, triethylene glycol Ethylene glycol ethers such as ethylene glycol phenyl ether, triethylene glycol benzyl ether and triethylene glycol monobutyl ether, and propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol propyl ether, propylene glycol butyl ether, propylene glycol pentyl ether, 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 Propylene glycol ethers such as propylene glycol methyl ether, tripropylene glycol ethyl ether, tripropylene glycol propyl ether, tripropylene glycol butyl 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.

A three- to five-membered ring lactone solvent is a compound having a lactone ring containing 4 or a five-membered ring with 5 atoms. Specific examples include α-acetolactone, β-propionlactone, γ-butyrolactone, δ-valerolactone and the like. Among these, γ-butyrolactone is preferred.

Amide solvents are preferably non-cyclic amide compounds such as dimethylacetamide, dimethylformamide, sulfanilamide, 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 modifier from the viewpoint of adjusting the surface tension value. Examples of surface modifiers include silicone-based surface modifiers, acrylic surface modifiers, vinyl-based surface modifiers, fluorine-based surface modifiers, and acetylene glycol-based surface modifiers. agent, and more preferably 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 silicone-based surface conditioners include polyether-modified polysiloxane, polyester-modified polysiloxane, polyether-modified hydroxyl-containing polysiloxane, polyester-modified hydroxyl-containing polysiloxane, etc. BYK-Chemie and Shin-Etsu Chemical Co., Ltd. Products commercially available from, etc. are readily 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 represented by the following formula (1)

(In the formula, R ¹ and R ² each represent an independent hydrocarbon group). Preferred nonionic surfactants have a bilaterally symmetrical structure centered on an acetylene group. In the present specification, acetylene glycol-based surface conditioners also include alkylene oxide adducts obtained by adding alkylene oxides (ethylene oxide, propylene oxide, etc.) to hydroxyl groups of surfactants. Acetylene glycol-based surface conditioners are readily available as commercial products from Nissin Chemical Industry Co., Ltd. and the like.

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

The water-based coating liquid and the water-based color ink preferably use a surface modifier so that the desired surface tension value is obtained. 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 inks may further contain pH adjusters, antifoaming agents, humectants, wetting and dispersing agents, preservatives/antifungal agents, dissolution aids, and oxidizing agents, if necessary. An inhibitor, a metal trapping agent, and 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 50% to 90% by mass of water, 5% to 35% by mass of organic solvent, and 0.005% to 5% by mass of resin. Such a water-based coating liquid with a small amount of resin dries quickly, and is therefore preferable from the viewpoint of suppressing the occurrence 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 (especially print heads) of printing equipment such as inkjet printers, and have a pH of 7.01 to 10.0. is preferably within the range of
A pH adjuster can be used for pH adjustment, but an amine compound is preferably used, and an amine compound having a boiling point of 70 to 270° C. is more preferably used. Specific examples of amine compounds 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 individually by 1 type, and may be used in combination of 2 or more types. 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, the water-based color ink and the water-based coating liquid each independently preferably have a viscosity within the range of 3.0 to 10.0 mPa·s at 25°C. In this specification, the viscosities of inks and coating liquids are measured after adjusting the liquid temperature to 25° C. using a rheometer (for example, rheometer ARES manufactured by TA Instruments).

In the ink set of the present invention, the water-based coating liquid preferably has a surface tension value of 28.0 mN/m or less at 25° C., more preferably 27.0 mN/m or less. By setting the surface tension of the water-based coating liquid to 28 mN/m or less, it is possible to suppress repelling that occurs on the absorbent substrate.
In the ink set of the present invention, the water-based coating liquid preferably has a surface tension value of 21.0 mN/m or more at 25° C., more preferably 24.0 mN/m or more. By setting the surface tension of the water-based coating liquid to 21 mN/m or more, the penetration of the coating liquid into the substrate can be suppressed.

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. .

As used herein, the "surface tension value" of inks and coating liquids 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.
Both the color ink and the coating liquid used in the ink set of the present invention are water-based and generally tend to have high surface tension values. It is important to adjust the surface tension value by appropriately adjusting the type and content of the additive including the surface modifier, more preferably 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 substrate 2nd step: treating the surface of the absorbent substrate with a water-based coating liquid 3rd step: drying the surface of the absorbent substrate treated in the 2nd step 4th step Process: The surface of the absorbent substrate dried in the third step is treated with a water-based coating liquid. Fifth step: The surface of the absorbent substrate treated in the fourth step is printed with water-based color ink.

The first step of the printing method of the present invention is the step of preparing an absorbent substrate as a substrate to be printed. The absorbent substrate is a substrate that absorbs water-based coating liquids and water-based inks, and in this 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 substrate, and after 10 seconds have passed, the substrate is wiped off. At that time, it is confirmed whether or not there are traces of water permeation. If the third and fourth steps, which will be described later, are not performed, the coating liquid permeates into the absorbent substrate, so that the coating liquid cannot sufficiently exert its aggregating action, and as a result, the color ink is fixed at a predetermined position. Can not do it.

In the printing method of the present invention, the absorbent substrate may be a white substrate. As used herein, the term “white substrate” refers to a substrate whose printed surface is at least white, and “white” here refers to achromatic white, but is not limited to beige or gray. Also included is an off-white.

In the printing method of the present invention, specific examples of the absorbent white substrate mainly include coated paper (specifically, resin-coated paper), art paper, cast paper, lightly coated paper, fine paper, synthetic paper, and inkjet. Examples include paper substrates such as paper, and since these paper substrates are particularly susceptible to shrinkage and bending due to permeation of the coating liquid, 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 the step of treating the surface of the absorbent substrate with a water-based coating liquid. The surface treatment of the absorbent substrate with the water-based coating liquid can be performed by various printing means. Specifically, inkjet printing, gravure printing, offset printing, flexographic printing, screen printing, coater printing, and the like can be mentioned.

The temperature of the substrate in the second step is preferably 30 to 50°C. When the substrate surface temperature is 30° C. or higher, the wettability of the aqueous coating liquid to the substrate can be improved. Further, when the temperature is 50° C. or less, drying of the water-based coating liquid at the head interface can be prevented. The temperature of the base material is the temperature of the surface of the base material to which the water-based 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, it is preferable that the water-based coating liquid used in the second step is used in 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 substrate treated with the water-based coating liquid in the second step. By drying the surface of such an absorbent substrate, the water-soluble polymer having cations can be deposited on the absorbent substrate. This can prevent the water-based coating liquid used in the treatment of the fourth step from penetrating the surface of the absorbent substrate. In addition, the dried water-soluble polymer having a cation does not have the effect 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 deposited on the absorbent substrate.

In the third step, drying is preferably performed with hot air. In this case, the surface of the absorbent substrate treated with the water-based coating liquid is dried by applying hot air (usually using air). In the third step, drying is preferably carried out at 70 to 130°C, more preferably at 80 to 110°C. Moreover, in the third step, the drying is preferably performed for 2 seconds or more and less than 120 seconds, more preferably 5 seconds or more and 60 seconds or less. Although the drying means is not particularly limited, a dryer equipped with a blower function is preferable. The air volume is preferably 1.0 m ³ /min or more, more preferably 1.5 to 5.0 m 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 of 70° or less at a temperature of 25.0°C. It is more preferably 25° to 65°. The water-based coating printed in the fourth step by making the dynamic contact angle of water on the absorbent substrate after drying the surface of the absorbent substrate treated with the water-based coating liquid within the above specific range. It is possible to create a substrate environment in which the liquid is difficult to repel and is easy to wet and spread. As a method for lowering 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 above has a surface life of 100 ms and a temperature of 25° C. compared to the surface of the absorbent substrate prepared in the first step. The dynamic contact angle of water is low, and the difference is preferably 10° or more, more preferably 15° to 60°. After drying the surface of the absorbent substrate treated with the water-based coating liquid, the water content of the absorbent substrate is higher than that of the absorbent substrate prepared in the first step, which has not been treated with the water-based coating liquid. By setting the dynamic contact angle difference within the above specific range, it is possible to create a substrate environment that makes it difficult to repel the water-based coating liquid printed in the fourth step and is easy to wet and spread. As a result, the color ink in the fifth step A printed matter with a high degree of perfection can be produced at the time of printing.

In this 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 Interface Science Co., Ltd.). In this specification, contact angle measurement is performed on a substrate at 25° C. with a surface lifetime of 100 ms.
Dynamic contact angle measurement is obtained by contacting a base material with a liquid inserted in a syringe and measuring the contact angle when the liquid lands on the base material in units of time. By this measurement, it is possible to measure the contact angle of the instantaneously spreading liquid droplet and the temporal change in the liquid absorption amount.

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 landing 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 wetting and spreading, and the behavior of spreading immediately after landing develops on a very short scale. 100 ms is the timing when the ink that has landed on the substrate just finishes wetting and spreading, so by controlling the dynamic contact angle value at this time to an appropriate value, wetting due to contact of the aqueous coating liquid with the substrate can be controlled. can be performed in the most suitable conditions.

The fourth step of the printing method of the present invention is a step of treating the surface of the absorbent substrate dried in the third step with a water-based coating liquid. The water-soluble polymer having dried cations 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 sufficiently wets the absorbent substrate. It is possible to spread. For this reason, the coating liquid can exert its aggregating action, and the color ink can be fixed at a predetermined position.

In the fourth step, the surface treatment of the absorbent substrate with the water-based coating liquid can be performed by various printing means as in the second step. Specifically, inkjet printing, gravure printing, offset printing, flexographic printing, screen printing, coater printing, and the like can be mentioned.

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 contains a smaller amount of the water-soluble polymer having a cation 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 substrate treated with the water-based coating liquid in the fourth step. In the printing method of the present invention, from the viewpoint of sufficiently exhibiting the aggregation action of the coating liquid, without waiting for drying of the aqueous coating liquid used in the fourth step (that is, without drying the aqueous coating liquid). It is preferred to print with colored inks. In the above printing method, the total thickness of the discharged liquid of the water-based coating liquid and the water-based color ink immediately after the completion of printing (that is, before the water and the organic solvent evaporate) is in the range of 1 to 20 μm. is preferred.

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. of the plurality of water-based color inks. is the lowest. Water-based color inks, which are first printed on the coating liquid layer, are most strongly affected by the cohesion of the color inks 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 water-based color ink is preferably printed by an inkjet printing method, but is not limited thereto. Gravure printing, offset printing, flexographic printing, screen printing, coater It is also possible to carry out by various printing methods such as a system.

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

In the sixth step, drying is preferably performed with hot air. By applying hot air (usually using air) to the printed layer and drying it, the resin contained in the layer can be fused to the base material and a strong film can be formed. It is possible to provide excellent printed matter. From the viewpoint of fusing the resin contained in the printed layer onto the substrate, the drying in the sixth step is preferably carried out at 70 to 130°C, more preferably at 80 to 110°C. Moreover, in the sixth step, the drying is preferably performed for 2 seconds or more and 20 seconds or less, more preferably 5 seconds or more and 15 seconds or less. Although the drying means is not particularly limited, a dryer equipped with a blower function is preferable. The air volume is preferably 1.0 m ³ /min or more, more preferably 1.5 to 5.0 m ³ /min.

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

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

The formulations described 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 Synthesis, dimethylamine/ethylenediamine/epichlorohydrin polymer resin, resin content 50% by mass, weight average molecular weight (Mw): 9000, cation degree at pH 7.1 6.5 meq/ 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 Co., Ltd., polyamine resin, resin content 70.0% by mass, cation degree 6.8 meq/g at pH 7.1)
*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 Co., Ltd., 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 Nitbo 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 As the resin dispersion liquid E, the following was used.
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 As the cationic resin dispersion liquid F, the following was used.
Superflex 650 (manufactured by Daiichi Kogyo Seiyaku, cationic polycarbonate urethane resin dispersion, resin content 28% by mass, cation degree 0.8 meq/g at pH 7.1)
*7 As the aqueous resin solution G, the following was used.
Hylos 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 Olfine D-10PG (manufactured by Nissin Chemical Industry Co., Ltd., acetylene glycol surfactant, surfactant content 50% by mass, surface modifier)
*11 Surfynol 107L (manufactured by Nissin Chemical Industry Co., Ltd., acetylene glycol surfactant, surfactant content 50% by mass, surface modifier)
*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 modifier)

<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. Table 4 shows the results obtained by measuring the surface tension value (25°C) and viscosity (25°C) of each water-based color ink.

The formulations listed in Table 4 above are as follows. Already described compounding agents are omitted.
*15 The following was used as the self-dispersible pigment dispersion.
・CAB-O-JET 250C
(manufactured by Cabot Corporation, cyan self-dispersing pigment aqueous dispersion, pigment content 10% by mass)
・CAB-O-JET-465M
(manufactured by Cabot Corporation, magenta self-dispersible pigment aqueous dispersion, pigment content 15% by mass)
・CAB-O-JET 270Y
(manufactured by Cabot Corporation, yellow self-dispersing pigment aqueous dispersion, pigment content 10% by mass)
・CAB-O-JET 300K
(manufactured by Cabot Corporation, black self-dispersing pigment aqueous dispersion, pigment content 15% by mass)
*16 WET280 (manufactured by EVONIC, polyether-modified silicone surfactant, surfactant content 100% by mass, surface modifier)

<Water-based color ink containing non-self-dispersing pigment>
According to the formulation shown in Table 5, a non-self-dispersing pigment, an antifoaming agent, a water-soluble solvent, a wetting and dispersing agent, and an aqueous coloring dispersion prepared by dispersing ion-exchanged water by a known method, a resin and a surface control agent are added, Water-based color inks containing non-self-dispersed pigments were prepared. Table 5 shows the results obtained by measuring the surface tension value (25°C) and viscosity (25°C) of each water-based color ink.

The formulations listed in Table 5 above are as follows. Already described compounding agents are omitted.
*17 The following were used as non-self-dispersing pigments.
・FASTOGEN Blue FA5380 (phthalocyanine blue, cyan pigment manufactured by DIC)
・Shinkasha Magenta RT (dichloroquinacridone, magenta pigment manufactured by BASF)
・Hostaperm Yellow H5G (Quinoxaline dione, yellow pigment manufactured by Clariant)
・ Nerox-1000 (carbon black, manufactured by Orion Engineered 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 Daiichi Kogyo Seiyaku Co., Ltd., wetting and dispersing agent, component content 100% by mass)

<Printability>
The ink sets shown in Tables 6 to 16 were prepared and the printability was evaluated.
Using Tritech's Stage JET, first, the water-based coating liquid used in the second step shown in Tables 6 to 16 was discharged in a single pass at a conveying speed of 12 pL and 25 m / min under high-speed printing conditions, and 100% Top coat plus (manufactured by Oji Paper Co., Ltd., basis weight 127.9 g/m ² ), multicolor foam gloss (manufactured by Oji Paper Co., Ltd., basis weight 157.0 g/m ² ), and Sword ijet 4.3 It was printed on the surface of a substrate of gross (manufactured by Mitsubishi Paper Mills, basis weight: 127.9 g/m ² ). After printing the water-based coating liquid, it was dried at the temperature and time shown in Tables 6 to 16 using a drying oven in which the temperature can be changed. After that, 12 pL of the water-based coating liquid used in the fourth step shown in Tables 6 to 16 was discharged in a single pass at a conveying speed of 25 m / min under high-speed printing conditions, and a 50% solid image was formed on the surface of the dried substrate. (However, in Comparative Example 1, it is printed on the substrate surface without drying), and then, without drying the printed water-based coating liquid, cyan excluding black ink on the landed water-based coating liquid. Ink droplets of ink, magenta ink, and yellow ink are ejected in a single pass in accordance with the order of the color ink sets in Tables 6 to 16 at a transport speed of 12 pL and 25 m / min under high-speed printing conditions. 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. After that, drying was performed at a temperature of 100° C. for 5 minutes. The printed portion was visually observed and 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 composition of the ink set used and the evaluation results.
◯: Bleeding and streaks are not observed in solid printing of each color and solid printing of three colors.
Δ: Bleeding or streaks are observed in solid printing of each color and solid printing of three colors.
x: Bleeding and streaks are observed in solid printing of each color and solid printing of three colors.

<Scratch resistance>
The ink sets shown in Tables 6 to 16 were prepared and evaluated for abrasion resistance.
Using Tritech's Stage JET, first, the water-based coating liquid used in the second step shown in Tables 6 to 16 was discharged in a single pass at a conveying speed of 12 pL and 25 m / min under high-speed printing conditions, and 100% Top coat plus (manufactured by Oji Paper Co., Ltd., basis weight 127.9 g/m ² ), multicolor foam gloss (manufactured by Oji Paper Co., Ltd., basis weight 157.0 g/m ² ), and Sword ijet 4.3 It was printed on the surface of a substrate of gross (manufactured by Mitsubishi Paper Mills, basis weight: 127.9 g/m ² ). After printing the water-based coating liquid, it was dried at the temperature and time shown in Tables 6 to 16 using a drying oven in which the temperature can be changed. After that, 12 pL of the water-based coating liquid used in the fourth step shown in Tables 6 to 16 was discharged in a single pass at a conveying speed of 25 m / min under high-speed printing conditions, and a 50% solid image was formed on the surface of the dried substrate. (However, in Comparative Example 1, it is printed on the substrate surface without drying), and then, without drying the printed water-based coating liquid, cyan excluding black ink on the landed water-based coating liquid. Ink droplets of ink, magenta ink, and yellow ink are ejected in a single pass in accordance with the order of the color ink sets in Tables 6 to 16 at a transport speed of 12 pL and 25 m / min under high-speed printing conditions. Solid printing was performed with a print density of 80% for each yellow ink and a total print density of 240%. After that, drying was performed at a temperature of 100° C. for 5 minutes. The printed portion was rubbed back and forth with a cotton swab (registered trademark, manufactured by Hakujuji Co., Ltd.) five times, 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 composition of the ink set used and the evaluation results.
◯: No ink adheres to the cotton swab.
Δ: Ink adhered to the cotton swab, but the ink did not peel off from the substrate.
x: Ink adhered to the cotton swab, and the ink was peeled off from the substrate.

<color development>
The ink sets shown in Tables 6 to 16 were prepared and evaluated for color development.
Using Tritech's Stage JET, first, the water-based coating liquid used in the second step shown in Tables 6 to 16 was discharged in a single pass at a conveying speed of 12 pL and 25 m / min under high-speed printing conditions, and 100% Top coat plus (manufactured by Oji Paper Co., Ltd., basis weight 127.9 g/m ² ), multicolor foam gloss (manufactured by Oji Paper Co., Ltd., basis weight 157.0 g/m ² ), and Sword ijet 4.3 It was printed on the surface of a substrate of gross (manufactured by Mitsubishi Paper Mills, basis weight: 127.9 g/m ² ). After printing the water-based coating liquid, it was dried at the temperature and time shown in Tables 6 to 16 using a drying oven in which the temperature can be changed. After that, 12 pL of the water-based coating liquid used in the fourth step shown in Tables 6 to 16 was discharged in a single pass at a conveying speed of 25 m / min under high-speed printing conditions, and a 50% solid image was formed on the surface of the dried substrate. (However, in Comparative Example 1, it is printed on the substrate surface without drying), and then, without drying the printed water-based coating liquid, cyan excluding black ink on the landed water-based coating liquid. Ink droplets of ink, magenta ink, and yellow ink are ejected in a single pass in accordance with the order of the color ink sets in Tables 6 to 16 at a transport speed of 12 pL and 25 m / min under high-speed printing conditions. Solid printing was performed with a print density of 80% for each yellow ink and a total print density of 240%. After that, drying was performed at a temperature of 100° C. for 5 minutes to prepare a printed image.
In addition, printing was performed in the same manner as the above procedure except that the printing of the aqueous coating liquid in the second step shown in Tables 6 to 16 was not performed, and then drying was performed at a temperature of 100 ° C. for 5 minutes. An image was created.
The printed portions of the printed image and the comparative image were 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 composition of the ink set used and the evaluation results.
◯: A state in which the printed image has clearer coloration than the image for comparison.
Δ: The printed image is in a state of color development equivalent to that of the image for comparison.
x: The printed image is inferior in color development to the comparative image, or a different color is formed.

<Dynamic contact angle 1>
The ink sets shown in Tables 6 to 16 were prepared and evaluated for dynamic contact angle.
Using Tritech's Stage JET, 12 pL of the water-based coating liquid used in the second step shown in Tables 6 to 16 was discharged in a single pass at a conveying speed of 25 m / min under high-speed printing conditions, and 100% solid Image OK Top Coat Plus (Oji Paper Co., basis weight 127.9 g/m ² ), Multicolor Foam Gloss (Oji Paper Co., basis weight 157.0 g/m ² ), and Sword ijet 4.3 gloss ( It was printed on the surface of a base material manufactured by Mitsubishi Paper Mills, basis weight: 127.9 g/m ² ). After printing the water-based coating liquid, it was dried at the temperature and time shown in Tables 6 to 16 using a drying oven in which the temperature can be changed. Next, using DM700 manufactured by Kyowa Interface Science Co., Ltd., the dynamic contact angle of ion-exchanged water was measured with respect to the dried substrate at a surface life of 100 ms and a temperature of 25°C. Evaluation criteria are as follows. The evaluation results are shown in Tables 6-16.
◎: Dynamic contact angle is 60 ° or less ○: Dynamic contact angle is greater than 60 ° and 70 ° or less △: Dynamic contact angle is greater than 70 ° and 80 ° or less ×: Dynamic contact angle is greater than 80 ° big

<Dynamic contact angle 2>
The ink sets shown in Tables 6 to 16 were prepared and evaluated for dynamic contact angle.
Using Tritech's Stage JET, 12 pL of the water-based coating liquid used in the second step shown in Tables 6 to 16 was discharged in a single pass at a conveying speed of 25 m / min under high-speed printing conditions, and 100% solid Image OK Top Coat Plus (Oji Paper Co., basis weight 127.9 g/m ² ), Multicolor Foam Gloss (Oji Paper Co., basis weight 157.0 g/m ² ), and Sword ijet 4.3 gloss ( It was printed on the surface of a base material manufactured by Mitsubishi Paper Mills, basis weight: 127.9 g/m ² ). After printing the water-based coating liquid, it was dried at the temperature and time shown in Tables 6 to 16 using a drying oven in which the temperature can be changed. Next, using DM700 manufactured by Kyowa Interface Science Co., Ltd., the dynamic contact angle of ion-exchanged water was measured with respect to the dry substrate at a surface life of 100 ms and a temperature of 25°C. For comparison, the same measurement was performed on a base material not printed with the water-based coating liquid (the base material itself). Evaluation criteria are as follows. The evaluation results are shown in Tables 6-16.
◎: 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 untreated base material ○: The dynamic contact angle of the base material surface-treated with the water-based coating liquid 10 ° or more and less than 20 ° than the substrate without treatment △: The dynamic contact angle of the substrate surface-treated with the aqueous coating liquid is 5 ° or more and less than 10 ° than the substrate without treatment × : The dynamic contact angle of the substrate surface-treated with the water-based coating solution is less than 5° than that of the untreated substrate.

<Ejectability>
Using Tritech's Stage JET, first, after filling the printer with the water-based coating liquid used in the second step shown in Tables 6 to 16, make it land on the transparent OHP sheet, and check the pattern read in 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 corresponding to 25 m ² was performed. After that, the same water-based coating droplets as in step A were made to land on a transparent OHP sheet, and the same check pattern as in step A read into the apparatus was printed (step B). Each OHP sheet on which the check pattern was printed in the process A and process B was visually confirmed, and the ratio of pins missing from the check pattern was evaluated. Evaluation criteria are as follows. The evaluation results are shown in Tables 6-16.
◯: There is no ejection failure in the check pattern printed in the process A, and the ratio of pins missing from the check pattern printed in the process B is less than 5%.
Δ: There is no ejection failure in the check pattern printed in process A, and the percentage of pins missing from the check pattern printed in process B is 5% or more and less than 30%.
x: There is no ejection failure in the check pattern printed in process A, and the percentage of pins missing from the check pattern printed in process B is 30% or more.

<Storage stability>
Take 100 g of the water-based coating liquid used in the second step shown in Tables 6 to 16 in a 110 cc glass bottle, store it at 60 ° C. for 4 weeks, and measure the viscosity, surface tension, specific gravity, and pH before and after storage. rice field. The results were compared. Evaluation criteria are as follows. The evaluation results are shown in Tables 6-16.
○: Rate of change within 10% for all items △: Rate of change of more than 10% and less than 20% in any one item ×: Rate of change of 20% or more in 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 effect of aggregating the water-based color ink,
a first step of providing an absorbent substrate;
a second step of treating the surface of the absorbent substrate with the water-based coating liquid;
a third step of drying the surface of the absorbent substrate treated in the second step;
A fourth step of treating the surface of the absorbent substrate dried in the third step with the water-based coating liquid;
and a fifth step of printing with the water-based color ink on the surface of the absorbent substrate treated in the fourth step,
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. 2. 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. 3. The printing method according to claim 1, wherein the organic solvent contains at least one type of alkanediol 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 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 macromer-modified acrylic surface conditioner. The printing method according to any one of claims 1 to 9, characterized in that drying is performed at 70 to 130°C in the third step. 11. 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 one of claims 1 to 11, wherein 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 of 70° or less at a temperature of 25°C. or the printing method according to 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. compared to the surface of the absorbent substrate prepared in the first step. The printing method according to any one of claims 1 to 12, characterized in that the difference between is 10° or more.