JP2000094825A - Ink jet recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording method for printing at high speed even on a plain paper, providing the high printing quality not generating subduing and bleeding and also providing superior water resistance and the like. SOLUTION: In ink jet recording method, a plain paper coated with a solution containing dissociative polyvalent metallic salt in the range of 0.1-2.0 g/m2 dessociative polyvalent metallic salt coating amount is used as a recording paper, and an ink jet recording liquid of 30-45 mN/m surface tension is provided with the 30-300 mgKOH/g acid value and contains water-soluble resin dissolved in water under the presence of a basic compound and a pigment is used for printing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink-jet recording method, and more particularly, to an ink-jet recording method capable of printing high-quality characters and images at high speed using plain paper having high ink-jet recording liquid permeability. About.

[0002]

2. Description of the Related Art As a means for outputting color image data to a recording medium, the demand for a printer using an ink jet recording system has been remarkably growing, and it has rapidly spread not only for personal use but also for industrial use.

[0003] Originally, the ink jet recording system is one step away from the electrostatic image recording system in terms of printing speed or printing quality, but has very great advantages in terms of the cost of the apparatus itself and the operating cost. In addition, technological advances have made it possible to achieve higher speeds and higher definition, and the time and quality required for printing have both been dramatically improved.
This has led to a surge in current penetration rates.

In order to maintain high print quality in the ink jet recording method, it is necessary that a droplet of the ink jet recording liquid that has landed on the paper surface is dried at least so as not to ooze out when the next droplet lands. is necessary. Therefore, in order to speed up printing, the droplets must dry instantly when they land on the paper surface.

[0005] In the field of aqueous ink jet recording liquid, which is the object of the present invention, evaporation and drying are not enough. Therefore, the surface tension of the system is reduced as much as possible, and the solvent component is permeated into the paper from the droplets and dried. That is, a so-called osmosis drying method will be used.

At present, most commercially available ink jet recording liquids are of a type using a dye as a colorant.
It is known that high printing density and high chroma can be maintained even if the solvent component penetrates into the paper due to phenomena such as adsorption and dyeing of the dye on the paper surface. The printing speed has been increased.

[0007] However, as the fundamental drawbacks of dyes such as poor light fastness, preservation for a long period of time, and low water resistance to sweat and the like have been pointed out, the transition of ink jet recording liquid to pigment type has been pointed out. Is desired.

In the case of pigment-based ink jet recording liquids, in order to increase the speed in the aqueous type, it is necessary to use osmotic drying. However, in the case of pigment-based inks, as the surface tension becomes lower, the pigment particles are dispersed together with the penetration of the solvent. As it is, it is widely diffused in the paper as it is, so that there is a problem that sufficient print density and saturation cannot be obtained, and the ink is more likely to bleed.

Therefore, only the black recording liquid is shifting to the pigment type, but the surface tension is increased to suppress the diffusion of the pigment into the paper, and the recording liquids of other colors remain at the dye type to achieve high speed. At present, it is compatible with printing quality.

As described above, it is difficult to improve the speed and the quality by using a pigment type ink jet recording liquid because it is difficult to improve the recording liquid alone. Are being improved.

For example, in the case of ink-jet recording paper having a coating layer on the paper surface, such as glossy paper or coated paper, the coating layer has a function of suppressing the diffusion while increasing the absorbency of the recording liquid, thereby increasing the surface tension. Many methods have been developed to achieve both high speed, high density, and high definition, even with a pigment-based recording liquid having a low density.

However, these special papers are very costly and hinder the original merit of the ink jet recording system.

In recent years, there have been many applications for techniques for improving the quality of printing on plain paper.
For example, a method utilizing acid precipitation or salting out is disclosed in
For example, JP-A-8-22009 and JP-A-6-99576 disclose a method using a high-molecular-weight cation compound.
Japanese Patent Application Laid-Open No. 8-20161, for example, discloses a method of utilizing a polyamine, such as Japanese Patent No. 16498, by which the fixing component of the ink jet recording liquid is agglomerated on the very surface of the paper and fixed before dulling or bleeding occurs. Methods are known.

[0014]

However, the method utilizing acid precipitation has a problem that the weather resistance of printed matter is deteriorated if an acid component remains, and salting out, high molecular weight cation, polyamine, etc. In the method used, bleeding or the like cannot be sufficiently suppressed, and further improvement in printing quality is desired.

Further, in plain paper, there is a problem that a fluid component including a fixing resin easily permeates and diffuses, and water resistance and friction resistance are lowered.

Accordingly, an object of the present invention is to provide an ink jet recording method which enables high-speed printing even on plain paper, provides high printing quality without dulling or bleeding, and is excellent in water resistance and the like. It is.

[0017]

That is, according to the first aspect of the present invention, a solution containing a dissociable polyvalent metal salt is applied to a solution containing the dissociable polyvalent metal salt in an amount of 0.1 to 2.0 g / m ^2. Using plain paper coated in the range of
A surface tension of 30 having an acid value of mg KOH / g and containing a water-soluble resin and a pigment dissolved in water in the presence of a basic compound.
The present invention relates to an ink jet recording method characterized by printing an ink jet recording liquid of up to 45 mN / m.

In the invention according to claim 2, the dissociable polyvalent metal salt is a polyvalent metal salt having a solubility of not less than 0.01 mol / liter in water at ambient temperature. And an ink jet recording method.

According to a third aspect of the present invention, calcium formate is used as the dissociable polyvalent metal salt.
The invention relates to the inkjet recording method described above.

According to a fourth aspect of the present invention, the ink jet recording liquid has a viscosity of 1.0 to 10.0 mPa · s, p
The inkjet recording method according to any one of claims 1 to 3, wherein an inkjet recording liquid having a H of 6.8 to 10.0 is used.

According to a fifth aspect of the present invention, the water-soluble resin of the ink jet recording liquid has at least one kind of acid group selected from the group consisting of a carboxyl group, a sulfonic acid group and a phosphoric acid group in the molecule. The inkjet recording method according to any one of claims 1 to 4, wherein a resin is used.

The invention according to claim 6 is that the water-soluble resin of the ink jet recording liquid has 8 to 2 carbon atoms in the molecule.
Having a long-chain alkyl group of 0 and a weight average molecular weight of 1,000
The inkjet recording method according to any one of claims 1 to 5, wherein an acrylic water-soluble resin of 0 to 20,000 is used.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An object of the present invention is to obtain a printed matter which is not only free from dullness and bleeding but also excellent in water resistance even when plain paper is used as recording paper in an ink jet recording method. It is assumed that.

For this purpose, when the ink jet recording liquid adheres to the surface of the paper, it is necessary that the fixing component is instantaneously aggregated and precipitated and also insoluble in water.

Conventionally, there are many known methods for impregnating paper with an acid or a monovalent metal cation component to precipitate a fixing component of an ink jet recording liquid. This utilizes a phenomenon of so-called acid precipitation or salting out, in which the solubility of the fixing component of the recording liquid is reduced due to elution into the ink jet recording liquid and the precipitate is precipitated.

However, when plain paper is used as the recording paper, the solvent component penetrates into the paper very quickly, and in the case of salting out or aciding out, the fixing component is precipitated at a speed enough to fix the pigment on the paper surface. You can't do that.

According to the present invention, plain paper is impregnated with a dissociable polyvalent metal salt in advance, and a water-soluble resin used as a fixing component of an ink jet recording liquid is cross-linked to thereby significantly reduce acid precipitation and salt precipitation. In addition to providing the recording liquid with rapid aggregation and precipitation, it also provides the printed matter with high water resistance, thereby obtaining excellent printability on plain paper.

Hereinafter, the present invention will be described in detail.

First, the dissociable polyvalent metal salts usable in the present invention include chlorides, sulfates of alkaline earth metals such as calcium and barium, and other polyvalent metals such as magnesium, zinc, tin and manganese. Nitrate, formate, acetate and the like can be used, specifically, calcium acetate, calcium chloride,
Calcium nitrate, calcium formate, barium chloride, barium formate, magnesium chloride, magnesium sulfate, magnesium nitrate, magnesium formate, zinc chloride, zinc sulfate, zinc nitrate, zinc formate, tin chloride, tin nitrate, manganese chloride, manganese sulfate, manganese nitrate , Manganese formate and the like, which can be used alone or in combination of two or more.

Among these dissociable polyvalent metal salts, those having a solubility of preferably 0.01 mol / l or more in water at ambient temperature, and from this point, are composed of strong acids and strong bases. Polyvalent metal salts are preferred. On the other hand, in order for the acid group of the water-soluble resin contained in the inkjet recording liquid and the dissociated polyvalent metal cation to react and crosslink,
It is desirable that the counter ion of the polyvalent metal salt is not very strong. Therefore, in the balance of solubility and reactivity,
Particularly, calcium formate is preferred.

The coating solution obtained by dissolving the above polyvalent metal salt in water is applied or printed on plain paper in advance before the ink jet recording liquid is printed, and the polyvalent metal salt is added to the paper. Impregnated.

In order to immediately fix the ink jet recording liquid on the surface of the paper, it is effective if a large amount of the polyvalent metal salt is present at a portion closer to the surface of the paper. For this purpose, it is preferable to use a coating liquid with quick drying or high viscosity and reduce the permeability as much as possible, and use a highly volatile water-miscible organic solvent such as methanol, ethanol, acetone or methyl acetate. A method of increasing the drying property by using a water-soluble resin such as a polyvinyl alcohol resin, a cellulose resin, or a polyvinyl pyrrolidone resin, or an aqueous resin emulsion capable of maintaining dispersion stability even when containing a polyvalent metal salt. A method for increasing the viscosity can be used.

Next, the ink jet recording liquid used in the present invention contains a pigment and a water-soluble resin having an acid group in the molecule and dissolved in water in the presence of a basic compound. .

First, as the pigment, generally known inorganic and organic pigments which can be dispersed in an aqueous medium can be used. In particular, those which are easily wetted by an aqueous medium by surface treatment are preferable.

Specifically, as inorganic pigments, titanium oxide, red iron oxide, antimony red, cadmium red,
Cadmium yellow, cobalt blue, navy blue, ultramarine, carbon black, graphite, etc., as organic pigments, soluble azo pigments, insoluble azo pigments, azo lake pigments, condensed azo pigments,
Examples thereof include a copper phthalocyanine pigment and a condensed polycyclic pigment.

The amount of the pigment used is about 1 to 30% by weight, preferably 2 to 1% by weight in the ink jet recording liquid.
The amount is 0% by weight. When the amount is small, the color density is low. On the other hand, when the amount is large, it is difficult to use the recording liquid in terms of viscosity and fluidity.

The water-soluble resin having an acid group in the molecule used as a fixing component in the ink jet recording liquid includes an acrylic monomer having an acid group such as a carboxyl group, a sulfone group or a phosphoric acid group. Acrylic resin using as an essential component, known styrene / maleic acid-based copolymer resin using styrene monomer and maleic acid monomer as essential components, polyester resin, polyurethane resin And the like, and are water-soluble resins that can be dissolved in water in the presence of a basic compound.

Specifically, as the carboxyl group-containing copolymer, unsaturated monocarboxylic acid compounds such as acrylic acid, methacrylic acid and crotonic acid, unsaturated dicarboxylic acid compounds such as maleic acid, fumaric acid and itaconic acid, and the like. Using a half ester, as a sulfone group-containing copolymer,
Utilizing 2-acrylamido-2-methyl-1-propanesulfonic acid, 2-methacrylamido-2-methyl-1-propanesulfonic acid, styrenesulfonic acid, or the like, acid phosphonyl (meth ) Acrylate, acid phosphonylethyl (meth) acrylate, etc., as other monomers, ethylene, (meth) acrylic acid alkyl ester, (meth) acrylic acid hydroxyalkyl ester, (meth) acrylamide, styrene,
Copolymer resins obtained by copolymerizing with α-methylstyrene, vinyltoluene and the like can be mentioned. The other monomer has a carbon number of 8 to 2 from the viewpoint of the dispersibility of the pigment.
Monomers having 0 long-chain alkyl groups, particularly alkyl (meth) acrylates, are preferred, and examples include stearyl (meth) acrylate, lauryl (meth) acrylate, and palmityl (meth) acrylate.

The copolymer resin having particularly good pigment dispersibility is a copolymer resin obtained by using a monomer having a long-chain alkyl group having 8 to 20 carbon atoms in an amount of about 10 to 30% by weight. It is a coalescence, and among them, an acrylic copolymer resin is preferable.

Next, examples of the polyester resin having an acid group include a carboxyl group-containing polyester resin obtained by reacting a polyvalent carboxylic acid and a polyhydric alcohol under an excess condition of a carboxyl group.

Specifically, examples of polyvalent carboxylic acids include terephthalic acid, isophthalic acid, phthalic acid, 1,5
-Naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, aromatic dicarboxylic acids such as diphenic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, aliphatic dicarboxylic acids such as dodecanedicarboxylic acid, fumaric acid, maleic acid, Examples thereof include unsaturated aliphatic and alicyclic dicarboxylic acids such as itaconic acid, hexahydrophthalic acid, and tetrahydrophthalic acid.

On the other hand, polyhydric alcohols include aliphatic diols such as ethylene glycol, propylene glycol, butylene glycol and polyethylene glycol;
Trihydric or higher aliphatic polyhydric alcohols such as trimethylolethane, glycerin and pentaerythritol;
Alicyclic diols such as cyclohexanediol, 1,4-cyclohexanedimethanol, spiroglycol, hydrogenated bisphenol A, tricyclodecane, tricyclodecanedimethanol, para-xylene glycol, meta-xylene glycol, ortho-xylene glycol,
Examples thereof include aromatic diols such as 4-phenylene glycol.

Among the above components, a dicarboxylic acid and a diol are first reacted in excess of a hydroxyl group, and then a trivalent or higher polycarboxylic acid such as trimellitic acid, trimesic acid, and pyromellitic acid is added to the molecular terminal. By reacting
A polyester resin having an appropriate acid value can be obtained.

The phosphoric acid group-containing polyester resin is obtained by using at least one of phosphoric acid, pyrophosphoric acid, polyphosphoric acid, and phosphorous acid in the reaction process of the polyhydric alcohol compound and the polycarboxylic acid compound. be able to.

Further, as the sulfone group-containing polyester resin, sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfophthalic acid, 4-sulfonaphthalene-2,
Examples of the sulfone group-containing polyester resin obtained by using a sulfone group-containing dicarboxylic acid such as 7-dicarboxylic acid and 5- [4-sulfophenoxy] isophthalic acid, or a metal salt or an ammonium salt thereof, and a polyhydric alcohol. Can be.

Next, as a polyurethane resin having an acid group, a polyurethane resin obtained by reacting an organic diisocyanate compound with a high molecular weight diol compound to synthesize a urethane prepolymer and then reacting with a chain extender and a reaction terminator is used. And a carboxyl group-containing polyurethane resin using a compound having a carboxyl group in a polymer diol compound, a chain extender, or the like, and a sulfone group-containing polyurethane resin using a compound having a sulfone group in a polymer diol compound or the like. Can be.

Here, as the organic diisocyanate compound of the polyurethane resin used as the fixing component of the ink jet recording liquid, isophorone diisocyanate and tetramethylxylylene diisocyanate are useful.

Examples of the carboxyl group-containing high molecular weight diol compound include ethylene oxide adduct of dimethylolpropionic acid and a reaction product of polyethylene glycol with pyromellitic anhydride. Examples of the carboxyl group-containing chain extender include dimethylolpropion. Carboxyl group-containing diol compounds such as acids are useful.

Furthermore, a sulfone group-containing polyurethane resin can be obtained by using, as the polymer diol component, a sulfone group-containing polyester diol obtained by reacting the above-mentioned sulfone group-containing dicarboxylic acid compound or the like with a diol compound.

The acid value of these water-soluble resins is 30 mgKOH / g or more, preferably 50 mgKOH / g or more, more preferably 100 mgKOH / g or more in order to improve the solubility in water. 300 mgKOH / g or less, preferably 250 mgKOH
/ g or less.

The weight-average molecular weight of the water-soluble resin having an acid group in the molecule is preferably from 1,000 to 2
000, more preferably 3,000 to 17,000
It is. The weight average molecular weight of the water-soluble resin is 1,000
If it is lower, the effect of dispersing the pigment finely with only the water-soluble resin is reduced. On the other hand, if it is higher than 20,000, it is difficult to maintain the viscosity stably for a long time.

Among the water-soluble resins, an acrylic water-soluble resin having a long-chain alkyl group having 8 to 20 carbon atoms in the molecule and having a weight average molecular weight of 1,000 to 20,000 is particularly preferable.

In the present invention, the above-mentioned water-soluble resin having an acid group is dissolved in water and used as a water-soluble resin varnish. The basic compound usable for this purpose is an inorganic base such as ammonium hydroxide. Compound, triethylamine, monoethanolamine, triethanolamine, N
And organic basic compounds such as -methyl-2-pyrrolidone.

The amount of the basic compound used may be within a range capable of maintaining good solubility and drying property of the water-soluble resin, but is particularly preferably based on the amount required for neutralizing the copolymer. 8
The appropriate amount is about 0 to 120 mol%.

An organic solvent is preferably used as a component for the ink jet recording liquid. Examples of the organic solvent include lower alcohols such as methanol, ethanol and propanol, and (poly) alkylene glycols such as (poly) ethylene glycol and (poly) propylene glycol. And water-miscible solvents such as alkyl ethers thereof. In particular, as an organic solvent that can lower the surface tension of the system in a smaller amount,
Monoalkyl ethers of (poly) alkylene glycols are preferred.

Further, it is optional to add various additives such as a surfactant, a pigment dispersant, a viscosity modifier and an antifoaming agent as the ink jet recording liquid.

As a method for producing a recording liquid for ink jet recording using the above components, first, a pigment, a water-soluble resin varnish obtained by dissolving the resin having an acid group in an aqueous solution of a basic compound, an aqueous medium, If necessary, after mixing a surfactant, a pigment dispersant, a viscosity modifier, an antifoaming agent,
Various meat machines, for example, bead mill, ball mill, sand mill, attritor, roll mill, agitator, Henschel mixer, colloid mill, ultrasonic homogenizer,
A method in which the meat is ground using an ultra-high pressure homogenizer or the like and further the remaining materials are added and mixed can be used.

The content of the water-soluble resin in the ink jet recording liquid used in the present invention is 0.1%.
-10% by weight is preferred. If the content of the water-soluble resin is less than the above range, the fixability of the pigment on the paper surface tends to be inferior. On the other hand, if the content is more than the above range, the viscosity tends to be too high and the ejection responsiveness tends to be inferior.

The surface tension of the ink jet recording liquid used in the present invention is preferably from 30 to 30 by actively using an organic solvent and a surfactant in order to increase the penetrability into paper and to enhance the drying property. Set to 45 mN / m. When the surface tension of the ink jet recording liquid is lower than the above range, bleeding tends to occur at a low density of the printed image, while when the surface tension is high, drying becomes slow and the printing speed decreases.

The viscosity of the ink jet recording liquid used in the present invention is preferably 1.0 to 10.0 mPa · s at the ambient temperature during use. And a printed image with a small number of images can be obtained.

Further, the pH of the ink jet recording liquid used in the present invention is preferably from 6.8 to 10.0. When the pH is in this range, good storage stability and printing speed can be obtained.

Next, an ink jet recording method using the plain paper containing the dissociable polyvalent metal salt and the ink jet recording liquid will be described.

First, plain paper to be used in the present invention refers to recording paper, such as copy paper or bond paper, on which a special coating agent for improving the smoothness or gloss of the paper surface is not coated. As the method of impregnating the dissociable polyvalent metal salt solution, various coating means such as air knife coating, roll coating, spray coating, flexo method, gravure method, various printing means such as an ink jet method can be used. .

Further, the impregnated amount of the dissociable polyvalent metal salt is adjusted so that the resin is precipitated by crosslinking with an acid group of an acrylic resin having an acid group contained in an ink jet recording liquid to be printed later. The amount may be in excess of the amount, but 0.1 g / m ² or more is required to obtain good drying properties as a recording liquid. The upper limit of the impregnation amount of the dissociable polyvalent metal salt is 2.0 g depending on the type of the recording paper or the metal salt.
The effect leveled off at about / m ² , and further impregnation is not economically effective.

As the ink jet recording system,
A device that ejects droplets by vibrating a piezo vibrator by a recording signal, and a device that applies thermal energy corresponding to a recording signal to recording liquid in a room of a recording head and generates droplets by using the energy. Can be

According to the above-described method, even when printing is performed at a high speed using plain paper as the recording paper of the ink jet recording system, not only the printing quality is excellent but also the excellent effect on the water resistance can be obtained.

[0067]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

In the examples, “parts” and “%” are “parts by weight” and “% by weight” unless otherwise specified.
Represents

<Production of Water-Soluble Resin Varnish> Water-Soluble Resin Varnish A 350 parts of butyl acetate was charged into a four-necked flask equipped with a stirrer, a cooling tube, and a nitrogen gas inlet tube, and heated to 105 ° C. to remove nitrogen gas. While introducing, a mixture of 31 parts of methacrylic acid, 129 parts of methyl methacrylate, 40 parts of stearyl methacrylate, and 5 parts of benzoyl peroxide as an initiator was added dropwise over 2 hours, and the mixture was further copolymerized for 2 hours while maintaining the same temperature. Thereafter, butyl acetate was distilled off to obtain an acrylic copolymer resin having a weight average molecular weight of 11,000 and an acid value of 100 mgKOH / g.

30 parts of this acrylic copolymer resin was heated and dissolved in 70 parts of an aqueous ammonia solution in which ammonia corresponding to 100% of the neutralized amount of the copolymer was dissolved to form a water-soluble resin having a resin solid content of 30%. Varnish A was prepared.

Water-soluble resin varnish B 230 parts of N-methyl-2-pyrrolidone was charged into a four-necked flask equipped with a stirrer, a condenser and a nitrogen gas inlet tube, heated to 100 ° C., and nitrogen gas was introduced. , Methyl methacrylate 82 parts, stearyl methacrylate 30
Part, 38 parts of ATBS shown below, 50% by weight of t-butylperoxy-2-ethylhexanoate as an initiator
Toluene solution (Kayaester O-50 manufactured by Kayaku Akzo Co., Ltd.)
TL) and N-methyl-2-pyrrolidone 12
0 parts of the mixture was added dropwise over 1.5 hours, and further copolymerized for 1 hour while maintaining the same temperature to obtain a weight average molecular weight of 8.0 or less.
00, N of acrylic copolymer resin with acid value 103mgKOH / g
A solution of -methyl-2-pyrrolidone (solid content 30%) was obtained.

ATBS CH ₂ ＣＨCH—CO—NH—C (CH
_{3) 2} -CH ₂ -SO ₃ H soluble resin varnish C stirrer, condenser, a four-necked flask equipped with a nitrogen gas inlet pipe was charged with 350 parts of butyl acetate were heated to 105 ° C., introducing nitrogen gas Meanwhile, a mixture of 20 parts of acid phosphonyl methacrylate, 120 parts of methyl methacrylate, 60 parts of butyl acrylate, and 5 parts of benzoyl peroxide as an initiator was dropped over 2 hours, and further copolymerized for 2 hours while maintaining the same temperature. After that, butyl acetate was distilled off to obtain a weight average molecular weight of 12,000 and an acid value of 165 mg.
An acrylic copolymer resin of KOH / g was obtained.

30 parts of this acrylic copolymer resin was heated and dissolved in 70 parts of an aqueous ammonia solution in which ammonia corresponding to 100% of the neutralization amount of the copolymer was dissolved, and a water-soluble resin having a resin solid content of 30% was obtained. Varnish C was prepared.

Water-soluble resin varnish D In a four-necked flask equipped with a dehydrating tube, a thermometer, a nitrogen gas introducing tube and a stirrer, 10 parts of trimethylolpropane were added.
Hexanediol 40 parts, neopentyl glycol 36
, 31 parts of isophthalic acid, 27 parts of adipic acid and 0.3 part of dibutyltin dioxide, and 5
The temperature was raised to 220 ° C. over time, and a dehydration condensation reaction was performed at the same temperature. Thereafter, the mixture is cooled and trimellitic anhydride 20
Then, the mixture was heated to 160 ° C. and reacted until the acid value became 45 mgKOH / g to obtain a polyester resin having a resin acid value of 45 mgKOH / g and a weight average molecular weight of 3,000.

30 parts of this polyester resin was dissolved in 70 parts of an aqueous amine solution in which triethylamine was dissolved in an amount equivalent to 100% of the neutralized amount, to prepare a water-soluble resin varnish D having a resin solid content of 30%.

Water-soluble resin varnish E A polyethylene glycol 1 having an average molecular weight of 1,000 was placed in a four-necked flask equipped with a stirrer, a cooling pipe, and a nitrogen gas inlet pipe.
And 100 parts of isophorone diisocyanate, and reacted at 100 to 105 ° C. for 6 hours while introducing nitrogen gas. Then, as a chain extender, 1 mole of pyromellitic anhydride and 2 moles of ethylene glycol were reacted. .1
The mixture was added and reacted at 100 to 105 ° C for 5 hours. After cooling, diethylene glycol monomethyl ether 110
Parts, water 253 parts, triethylamine as a neutralizing agent 10.
After adding 9 parts and uniformly stirring, 6.1 parts of monoethanolamine was added as a reaction terminator, and the mixture was stirred at 30 ° C. for 1 hour. The resin acid value was 34 mgKOH / g, and the weight average molecular weight was 8,000.
A water-soluble resin varnish E containing 30% of the polyurethane resin as a solid content was obtained.

Water-soluble resin varnish F In a four-necked flask equipped with a stirrer, a condenser and a nitrogen gas inlet tube, 350 parts of butyl acetate was charged and heated to 105 ° C., and 95 parts of methacrylic acid was added while introducing nitrogen gas. , A mixture of 65 parts of methyl methacrylate, 40 parts of stearyl methacrylate, and 5 parts of benzoyl peroxide as an initiator were added dropwise over 2 hours.
After copolymerization for an hour, butyl acetate was distilled off to obtain an acrylic copolymer resin having a weight average molecular weight of 11,000 and an acid value of 310 mgKOH / g.

30 parts of this acrylic copolymer resin was heated and dissolved in 70 parts of an aqueous ammonia solution in which ammonia corresponding to 100% of the neutralized amount of the copolymer was dissolved, and a water-soluble resin having a resin solid content of 30% was obtained. Varnish F was prepared.

<Manufacture of Inkjet Recording Liquid> According to Table 1, a meat formulation comprising a pigment, a water-soluble resin varnish, a solvent and an antifoaming agent was stirred and mixed, and then an Eiger mill (bead mill type meat machine, manufactured by Eiger) was used. The mixture was kneaded for 3 hours, and further extended by adding and mixing to prepare ink jet recording liquids A to H. In addition, the water-soluble resin varnish G,
PGly (EO20) and PGmB refer to the following materials.

Water-soluble resin varnish G Commercially water-soluble acrylic copolymer resin varnish (BYK-1)
90, acid value 10 mgKOH / g, molecular weight 29,000, solid content 40%, manufactured by BYK-Chemie) PGly (EO20) = adduct of glycerin tetramer with 20 mol of ethylene oxide PGmB = propylene glycol monobutyl ether <Physical properties of inkjet recording liquid Value measurement> Surface tension of inkjet recording liquids A to H (surface tension meter HLV-ST)
Mold, Kyowa Interface Science Co., Ltd.), pH (pH meter, twin p
H-meter B-212, manufactured by Horiba, Ltd.) and viscosity (B-type viscometer, manufactured by Tokyo Kikai Co., Ltd., 25 ° C.)
The results are shown in Table 1.

<Preparation of Dissociable Metal Salt Solution and Method of Coating on Paper> 0.1%, 1.0%, 2.5%, 5.0% and 10.0% aqueous calcium formate solutions; 0%, 2.
A 5%, 5.0% and 10.0% aqueous magnesium sulfate solution, a 5.0% aqueous disodium hydrogen phosphate solution and a 5.0% aqueous sodium carbonate solution were prepared.
A plain paper (Xerox L, manufactured by Fuji Xerox Office Supply Co., Ltd.) was applied using a Mayer bar of m.

<Printing Method of Inkjet Recording Liquid> The inkjet recording liquids A to H were not coated with a dissociable metal salt solution using a commercially available inkjet printer (MJ-830C, piezo type, manufactured by Seiko Epson Corporation). It was printed on Xerox L for coating and coating.

The print density, drying property, bleeding,
The water resistance was evaluated by the following evaluation method, and the results were tabulated.
See Figure 2.

<Evaluation Method of Printed Material and Evaluation Result> Print density evaluation method The density of the solid portion of the printed material was measured by Macbeth optical densitometer RT-918.

Evaluation Results A: Density value exceeding 1.20 B: Density value exceeding 1.15 and 1.20 or less C: Density value exceeding 1.10 and 1.15 or less D: Concentration value of 1.10 or less Drying evaluation method Immediately after printing of inkjet recording liquids A to H,
The drying property was evaluated from the time until the recording liquid did not adhere to the finger due to finger touch.

Evaluation result A: Dry within 2 seconds.

B: Dry for more than 2 seconds and within 5 seconds.

C: Does not dry even if it exceeds 5 seconds.

Bleeding Evaluation Method A thin line of about 0.3 mm was printed, and the thickness due to bleeding was observed, and evaluated based on the following criteria.

Evaluation result A: Printing was performed with the same thickness without bleeding.

B: Fat is partially observed, but no more than double fat is observed.

C: Double or more thickening is observed as a whole.

Water resistance evaluation method A few drops of water were dropped on the surface of the print with a spoid.
After 5 seconds, the water resistance was observed from the state of the printed matter when wiped off with tissue paper.

Evaluation result A: Printing does not blur.

B: The print is slightly blurred, but the characters are clearly legible. C: The print is blurred and the characters are hard to read.

D: The print is blurred and the characters cannot be read.

The print density, drying property, bleeding and water resistance are all at a satisfactory level with a B rating or higher.

[0098]

[Table 1]

[0099]

[Table 2]

[0100]

As described above, the ink jet recording method according to the present invention has a
High-speed printing of a pigment type ink jet recording liquid on plain paper is enabled, and a printed matter having high density, no bleeding, and excellent water resistance can be obtained.

Continued on the front page (72) Inventor Yasumitsu Niki 1-23-37 Edobori, Nishi-ku, Osaka-shi Inside Sakata Inks Co., Ltd. 72) Inventor Yuka Hashimoto 1-23-37, Edobori, Nishi-ku, Osaka-shi F-term in Sakata Inks Co., Ltd. BA03 BA04 BA13 BA31 BA35 BA38 BA39 BC19 BC39 BC61 BE01 BE09 BE30 CA03 CA06 EA38 EA47 EA48 GA24

Claims (6)

[Claims] 1. A plain paper coated with a solution containing a dissociable polyvalent metal salt in a range where the dissociable polyvalent metal salt is applied in a range of 0.1 to 2.0 g / m ² is used as recording paper. And 30 ~
It is characterized by printing an inkjet recording liquid having a surface tension of 30 to 45 mN / m, which has an acid value of 300 mgKOH / g and contains a water-soluble resin and a pigment dissolved in water in the presence of a basic compound. Ink jet recording method. 2. The ink jet recording method according to claim 1, wherein the dissociable polyvalent metal salt is a polyvalent metal salt having a solubility of 0.01 mol / liter or more in water at ambient temperature. 3. The ink jet recording method according to claim 1, wherein calcium formate is used as the dissociable polyvalent metal salt. 4. The ink jet recording method according to claim 1, wherein an ink jet recording liquid having a viscosity of 1.0 to 10.0 mPa · s and a pH of 6.8 to 10.0 is used as said ink jet recording liquid. 5. A water-soluble resin having at least one kind of an acid group selected from the group consisting of a carboxyl group, a sulfonic acid group and a phosphoric acid group in a molecule is used as the water-soluble resin of the ink jet recording liquid. 5. The ink jet recording method according to any one of items 1 to 4. 6. An acrylic water-soluble resin having a weight average molecular weight of 1,000 to 20,000 and having a long-chain alkyl group having 8 to 20 carbon atoms in the molecule is used as the water-soluble resin of the ink jet recording liquid. The inkjet recording method according to claim 1.