JPH11172180A - Aqueous recording solution for ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a yellow pigment-based aqueous recording solution good in preservation stability and used for ink jet printers by using a pigment having a specific D. I. number such as C. I. Pigment Yellow 185 or others. SOLUTION: This aqueous recording solution for ink jet printers contains colored fin particles coated with one ore more pigments selected from the group consisting of C. I. Pigment Yellow 185, C. I. Pigment Yellow 180, C. I. Pigment Yellow 139, C. I.] Pigment Yellow 138, C. I. Pigment Yellow 110, C. I. Pigment Yellow 109 and C. I. Pigment Yellow 74.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an aqueous recording liquid for yellow ink jet printers.

[0002]

2. Description of the Related Art The ink jet recording system has features such as low noise generation, low running cost, and easy colorization, and has been rapidly spread in recent years.

[0003] Dyes have conventionally been used as colorants for aqueous recording liquids for ink jet printers. However, dyes have recently been shifting from dyes to pigments due to poor weather resistance and water resistance.

[0004] Methods of using pigments as colorants have been studied for a long time, and are described, for example, in JP-A-47-12104, JP-A-56-147859, and JP-A-56-1.
Many proposals have been made, such as 47863, and JP-A-56-147865.

[0005] In order to obtain a pigment-based aqueous recording liquid for an ink jet printer, in order to disperse the pigment in an aqueous medium, a method of dispersing a powder pigment using a surfactant or a water-soluble resin is generally used. It is still widely used today.
However, an aqueous recording liquid for an ink jet printer containing a pigment dispersed using a surfactant has a problem that the obtained image has extremely poor water resistance and can be used only for limited applications.

Further, it is generally more difficult to disperse a pigment in an aqueous medium containing a water-soluble resin than in the case of dispersing a pigment in an organic solvent medium. And it is difficult to keep the state stable.

On the other hand, when a pigment is simply dispersed using a water-soluble resin, the bond between the pigment and the resin is due to only a weak bond called adsorption. For example, the pigment is finely dispersed immediately after production. Even so, there is a problem that the storage stability is not good because the pigment aggregates with time.

As a method for improving the dispersibility of a pigment, an acid is added to an aqueous dispersion of a pigment which is dispersed in a resin having a carboxyl group neutralized with a base to make the resin hydrophobic. A so-called acid precipitation method is known in which a resin is fixed to a pigment.

For example, there is known a method in which rosin is fixed to a pigment by an acid precipitation method to obtain a powder pigment having good dispersibility. However, rosin cannot be a film-forming resin due to its low molecular weight, and when used in an aqueous recording liquid for an inkjet printer, a stable aqueous recording liquid cannot be obtained with rosin alone, and the obtained image also has There is a problem that the performance is low.

To solve this problem, Japanese Patent Laid-Open Publication No.
JP-A-122528 and JP-B-61-111979 disclose a method of obtaining a powder or solid pigment by performing acid precipitation using a limited resin such as an acrylic resin having a relatively high molecular weight.

However, in each of these methods, the pigment is powdered or solidified after the acid precipitation, so that the pigment agglomerates in the process in a small amount. Has to take the time-consuming process of dispersing again,
There is a problem. Moreover, although the powder or solid pigment obtained by these methods is more easily dispersible than the untreated powder pigment, it is a pigment that has been once powdered or solidified, so that it is used in aqueous recording liquids for inkjet printers. There is also a problem that a considerable amount of labor is required to finely disperse them to such an extent that they exhibit a high degree of coloring and coloring power.

On the other hand, US Pat. No. 4,166,811 discloses a pigment which uses a water-soluble resin having a high hydrophilicity, is re-neutralized with a basic compound after acid precipitation, and is easily dispersed in an aqueous medium. Are disclosed.

However, the basic constitution of this method is a method of re-neutralizing with a basic compound and then pulverizing or solidifying. When re-dispersing in an aqueous medium,
After all, once powdered or solidified, the problem of re-aggregation of the pigment cannot be ignored, and there is a problem that the coloring property and coloring power of the object to be coated cannot be exhibited at a high level. In addition, in order to facilitate redispersion in an aqueous medium after powdering or solidification, the resin that can be used in this method has a low molecular weight, and has a considerably high acid value, and is coated as a colorant. There is also a problem that the toughness and water resistance of the coating film are extremely low.

The aqueous recording liquid for an ink jet printer is usually composed of four colors of yellow, magenta, cyan and black. When a pigment is used as a coloring agent, the yellow color is usually C.I. I. Pigment Yellow 1
7, C. to magenta I. Pigment Red 1
22, C.I. I. Pigment Blue 1
5: 3 or C.I. I. Pigment Blue 1
5: 4, carbon black or the like is used for black.

[0015] However, C.I. I. Pigment Yellow 17 has insufficient light resistance and is not practical. As a method for improving light fastness, for example, European Patent 778,321 discloses C.I. I. Pigment Yellow 180,
C. I. Pigment Yellow 110, C.I.
I. Pigment Yellow 109 and C.I.
I. It is described that Pigment Yellow 74 can be used as a recording liquid for an ink jet printer to improve water resistance, light resistance and hue.

JP-A-9-31360 discloses an aqueous dispersion of a pigment finely dispersed with a resin having a carboxyl group neutralized with a basic compound and an aqueous dispersion of a pigment with an acidic compound. Alternatively, the resin is strongly fixed to the pigment by making the resin hydrophobic by acidification (so-called “acid precipitation”), and then, if necessary, after filtration and washing, neutralize the carboxyl group again with a basic compound. By re-dispersing in water, it is possible to obtain an aqueous pigment dispersion that is finely dispersed to a degree sufficient to exhibit high gloss, color developability, and coloring power, and that also has excellent storage stability. Are listed.

However, the aqueous recording liquid for an ink jet printer generally contains ethylene glycol, glycerin, a pH adjuster, an activator and the like in order to add printing characteristics as an ink.
No. 8,321 and the aqueous pigment dispersion obtained by the method as described in JP-A-9-31360, a specific yellow pigment, that is, C.I. I. Pigment Yellow
w 185, C.I. I. Pigment Yellow
180, C.I. I. Pigment Yellow 13
9, C.I. I. Pigment Yellow 138,
C. I. Pigment Yellow 110, C.I.
I. Pigment Yellow 109 and C.I.
I. Pigment Yellow 74, the aqueous recording liquid for yellow ink jet printers containing one or more pigments selected from the group consisting of Pigment Yellow 74 causes an increase in viscosity and an increase in particle diameter during storage, and the storage stability of the recording liquid becomes practical. It has not been resolved to the level.

[0018]

The object of the present invention is to provide a yellow pigment-based aqueous recording liquid for use in an ink jet printer, especially a C.I. I. Pigm
ent Yellow 185, C.I. I. Pigment
Yellow 180, C.I. I. Pigment Y
yellow 139, C.I. I. Pigment Yel
low 138, C.I. I. Pigment Yellow
w 110, C.I. I. Pigment Yellow 1
09 and C.I. I. Pigment Yellow 74
The purpose of the present invention is to improve the storage stability of an aqueous recording liquid containing one or more pigments selected from the group consisting of

[0019]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, it has been found that pigment fine particles not coated with an organic polymer compound and an organic polymer compound simply coexist. Without, when including colored fine particles coated with a specific yellow pigment with an organic polymer compound having a neutralized anionic group, not only water resistance, light resistance, excellent hue, but also storage stability We have found that an excellent aqueous recording liquid for an ink jet printer can be obtained, and have completed this research.

That is, the present invention provides the following invention. (1) An aqueous recording liquid for an inkjet printer containing colored fine particles obtained by coating a pigment with a neutralized organic polymer compound having an anionic group, wherein the pigment is C.I. I. Pigment Yellow 185, C.I.
I. Pigment Yellow 180, C.I. I.
Pigment Yellow 139, C.I. I. Pi
gment Yellow 138, C.I. I. Pigm
ent Yellow 110, C.I. I. Pigmen
t Yellow 109 and C.I. I. Pigment
An aqueous recording liquid for an inkjet printer, which is one or more pigments selected from the group consisting of Yellow 74.

(2) The method for producing an aqueous recording liquid for an ink jet printer according to the above (1), wherein the organic polymer compound having an anionic group is an organic polymer compound having a carboxyl group having an acid value of 30 to 150 KOH mg / g. .

(3) The organic high molecular compound having an anionic group is an organic high molecular compound having a carboxyl group and a hydroxyl group having an acid value of 30 to 150 KOH mg / g and a hydroxyl value of 20 to 120 KOH mg / g. Or the method for producing an aqueous recording liquid for an ink jet printer according to (2).

(4) After dispersing the pigment in a mixed solution of an organic polymer having an anionic group, which has been rendered water-soluble by neutralizing the anionic group with a basic compound, and an aqueous medium, the acidic compound is removed. In addition, the pigment is coated with an organic polymer compound having an anionic group by precipitating an organic polymer compound having an anionic group, and then a basic compound is added thereto to add an anionic group of the organic polymer compound having an anionic group. The aqueous recording liquid for an ink jet printer according to the above (1), (2) or (3), comprising an aqueous dispersion obtained by neutralizing and dispersing in an aqueous medium.

In the present invention, the acid value is defined as resin solid content 1
and the hydroxyl value is the amount of potassium hydroxide equivalent to glacial acetic acid required to neutralize 1 g of the resin solid content, and the hydroxyl value is expressed in mg of potassium hydroxide necessary to neutralize 1 g of the resin solids. Express.

The method for producing an aqueous recording liquid of the present invention basically comprises the following production steps. (1) An organic polymer compound having an anionic group or an organic solvent solution thereof, and an organic solvent solution thereof are mixed with a basic compound, and the mixture is neutralized and made water-soluble to form an organic polymer compound having an anionic group or an organic solvent solution thereof and an aqueous medium. And mix. (2) After mixing the pigment in the liquid mixture (suspension), the pigment is dispersed with a disperser or the like (pigment dispersion liquid). (3) If necessary, distill off the solvent. (4) The pigment is coated with an organic polymer having an anionic group by adding an acidic compound to precipitate an organic polymer having an anionic group. (5) Filter and wash as necessary. (6) A basic compound is added to neutralize the anionic group of the organic polymer compound having an anionic group and disperse it in an aqueous medium (aqueous dispersion).

As the organic high molecular compound having an anionic group used in the present invention, any of known organic compounds can be used.
Organic polymer compounds in the range of 150 (KOHmg / g) are preferred. A typical example of the anionic group is a carboxyl group.

Examples of such an organic polymer compound include a vinyl copolymer, a polyester resin, a polyurethane resin, an epoxy resin, and a rosin-modified resin. Among these, vinyl copolymers, polyester resins and polyurethane resins are preferred from the viewpoint of easy introduction of carboxyl groups and toughness of the coating.

The vinyl copolymer used in the present invention includes, for example, (meth) acrylate resin,
(Meth) acrylate-styrene copolymer resin,
Styrene- (anhydride) maleic acid copolymer resin, fluorinated vinyl copolymer resin and the like can be mentioned.

The polyester resin used in the present invention includes, for example, a saturated polyester resin, an unsaturated polyester resin, an alkyd resin and the like.
These resins must contain a carboxyl group as an anionic group in order to impart appropriate water solubility or water dispersibility.

The vinyl copolymer having a carboxyl group can be easily produced by a method of copolymerizing a polymerizable monomer composition containing a polymerizable monomer having a carboxyl group. Examples of the polymerizable monomer having a carboxyl group include acrylic acid, methacrylic acid, crotonic acid, fumaric acid, itaconic acid, (anhydrous) maleic acid, monoalkyl maleates such as monobutyl maleate, and itacons such as monobutyl itaconate. Monoalkyl acid and the like.

Examples of the polymerizable vinyl monomer other than the polymerizable vinyl monomer having a carboxyl group contained in the polymerizable monomer composition include aromatic vinyl monomers such as styrene, vinyltoluene and α-methylstyrene; methyl ( (Meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, isoamyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isodecyl (meth) Acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, butoxymethyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, benzyl (meth) (Meth) acrylic esters such as acrylate, cetyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate and isobornyl (meth) acrylate; vinyl esters such as vinyl acetate, vinyl benzoate, vinyl versatate and vinyl propionate Polymerizable nitriles such as (meth) acrylonitrile; vinyl monomers having a fluorine atom such as vinyl fluoride, vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene or chlorotrifluoroethylene; diethylaminoethyl (meth) acrylate, dimethyl Tertiary amino group-containing monomers such as aminoethyl (meth) acrylate, N-vinylimidazole and N-vinylcarbazole; 2- (2'-hydroxy-5-methacryloyloxyethyl) Eniru)
-2H-benzotriazole, 2-hydroxy-4- (2
-Methacryloyloxyethoxy) benzophenone,
Monomers having ultraviolet absorbing or antioxidant properties, such as 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate; N-vinylpyrrolidone, glycidyl (meth) acrylate, 1,3-dioxolan-2-one N-alkoxymethyl (meth) such as -4-ylmethyl (meth) acrylate, 1,3-dioxolan-2-one-4-ylmethylvinylether, diacetoneacrylamide, N-methylolacrylamide, and N-butoxymethyl (meth) acrylamide ) Functional group-containing monomers such as acrylamides; monomers having a hydrolyzable alkoxysilane group such as γ-methacryloxypropyltrimethoxysilane and vinyltrimethoxysilane; 2-phosphoxyethyl (meth) acrylate;
-Monomers containing a phosphoric acid group such as phosphooxybutyl (meth) acrylate; macromonomers having one polymerizable unsaturated group at a molecular terminal;

As the polymerization method of the polymerizable vinyl monomer composition, various known polymerization methods such as suspension polymerization, emulsion polymerization, bulk polymerization, and solution polymerization can be used, but solution polymerization is preferred because it is simple. As the polymerization initiator, known peroxides and azo compounds can be used.

The carboxyl group-containing polyester resin used in the present invention is subjected to a dehydration condensation reaction between a carboxyl group-containing compound and a hydroxyl group-containing compound by a known method such as a melting method and a solvent method so that the carboxyl group remains. Go and be manufactured.

The polyester resin includes a compound having a carboxyl group such as a monobasic acid, a dibasic acid, and a polybasic acid;
The alkyd resin is obtained by appropriately selecting a compound having a hydroxyl group such as a diol or a polyol and subjecting the compound to dehydration condensation, and further using an oil or a fat or a fatty acid as an alkyd resin.

The carboxyl group of the polyester resin used in the present invention is mainly an unreacted carboxyl group derived from the dibasic acid or polybasic acid constituting the polyester resin.

Examples of the dibasic acid or polybasic acid include adipic acid, (anhydrous) succinic acid, sebacic acid, dimer acid, (anhydrous) maleic acid, (anhydrous) phthalic acid, isophthalic acid, terephthalic acid, tetrahydro ( Phthalic acid, hexahydro (anhydride) phthalic acid, hexahydroterephthalic acid, 2,6-naphthalenedicarboxylic acid, (anhydride)
Trimellitic acid, (anhydrous) pyromellitic acid and the like.

Compounds having a carboxyl group that can be used other than dibasic acids or polybasic acids include, for example, lower alkyl esters of acids such as dimethyl terephthalate;
Monobasic acids such as benzoic acid, p-tert-butylbenzoic acid, rosin, hydrogenated rosin; fatty acids and fats and oils; macromonomers having one or two carboxyl groups at molecular terminals; 5-sodium sulfoisophthale Acids and dimethyl esters thereof.

As the compound having a hydroxyl group, for example,
Ethylene glycol, neopentyl glycol, propylene glycol, diethylene glycol, dipropylene glycol, 2-methyl-1,3-propanediol,
2,2-diethyl-1,3-propanediol, 1,4
-Butanediol, 1,3-propanediol, 1,6
-Hexanediol, 1,4-cyclohexanedimethanol, 1,5-pentanediol, an alkylene oxide adduct of bisphenol A, hydrogenated bisphenol A,
Alkylene oxide adduct of hydrogenated bisphenol A,
Polyethylene glycol, polypropylene glycol,
Diols such as polytetramethylene glycol; polyols such as glycerin, trimethylolpropane, trimethylolethane, diglycerin, pentaerythritol, and trishydroxyethyl isocyanurate;
Monoglycidyl compounds such as "Kajura E-10" (glycidyl ester of a synthetic fatty acid manufactured by Shell Chemical Industry Co., Ltd.), macromonomers having two hydroxyl groups at one molecular end, and the like.

When synthesizing a polyester resin,
Castor oil, hydroxyl-containing fatty acids or oils such as 12-hydroxystearic acid; dimethylolpropionic acid,
Compounds having a carboxyl group and a hydroxyl group, such as p-hydroxybenzoic acid and ε-caprolactone, can also be used.

Further, a part of the dibasic acid can be replaced with a diisocyanate compound. As a polyester resin having a carboxyl group used in the present invention,
A modified polyester resin obtained by grafting a polymerizable monomer having a carboxyl group to a polyester resin can also be used.

The polyurethane having a carboxyl group is
It can be easily produced by using a compound having a carboxyl group and a hydroxyl group such as dimethylolpropionic acid as the segment having a hydroxyl group.

The polyurethane resin having a carboxyl group used in the present invention is obtained by reacting a polyol component containing a compound having a carboxyl group and a hydroxyl group such as dimethylolpropionic acid as a component for introducing a carboxyl group with a polyisocyanate component. By doing so, it can be easily manufactured.

As the polyol component, in addition to the diol components listed in the polyester production method, a trifunctional or higher functional polyol compound can be used, if necessary.

The polyisocyanate component includes, for example, 2,
4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, phenylene diisocyanate, 1,5-naphthalene diisocyanate, metaxylylene diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, In addition to diisocyanate compounds such as hydrogenated 4,4'-diphenylmethane diisocyanate, hydrogenated meta-xylylene diisocyanate and crude 4,4'-diphenylmethane diisocyanate, polyisocyanate compounds such as polymethylene polyphenyl isocyanate can also be used.

The polyurethane resin can be produced by a known method. For example, the addition reaction is preferably performed at room temperature or at a temperature of about 40 to 100 ° C. in an inert organic solvent solution that does not react with the isocyanate group. At that time, a known catalyst such as dibutyltin dilaurate may be used.

The reaction system for producing the polyurethane resin includes, for example, N-alkyl dialkanolamines such as diamine, polyamine and N-methyldiethanolamine;
Known chain extenders such as dihydrazide compounds can also be used.

As the organic polymer compound having an anionic group used in the present invention, a vinyl copolymer or polyester resin having a hydroxyl group may be used, for example, maleic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, hexahydroanhydride. Resins having a carboxyl group obtained by a method in which a polybasic anhydride such as phthalic acid or trimellitic anhydride is subjected to an addition reaction can also be used.

The organic polymer having an anionic group used in the present invention is preferably an organic polymer having an acid value of 30 to 150 and having a carboxyl group. If the acid value exceeds 150, the hydrophilicity becomes too high, so that the water resistance of the coated object tends to be remarkably reduced. This is not preferred because redispersibility tends to decrease. Comparing an organic polymer compound having an acid value of 30 with an acid number of 30 at the same molecular weight, for example, when a recording liquid is used, when a compound in the range of 30 to 150 is used, the absolute chroma value becomes higher, and the viscosity and This is preferable because the rate of change of the particle diameter with time is significantly reduced, and the viscosity immediately after preparation and the absolute value of the particle diameter are further reduced.

The organic polymer having an anionic group used in the present invention preferably has a hydroxyl group in addition to the carboxyl group, and has a hydroxyl value based on the hydroxyl group (KOH mg / g) of 20 to 120. Those in the range are more preferred.

That is, the organic polymer compound having an anionic group has an acid value of 30 to 150 and a hydroxyl value of 20 to 120.
Of these, organic polymer compounds having a carboxyl group and a hydroxyl group are more preferred. If the hydroxyl value exceeds 120, the hydrophilicity becomes too high, and the water resistance of the coated object tends to decrease, which is not preferable. The hydroxyl group bonded to the organic polymer compound can form a stronger film by reacting with a curing agent when used in, for example, baking paints, baking inks, printing agents, and the like.

The vinyl copolymer having a carboxyl group and a hydroxyl group can be obtained by a method of copolymerizing the polymerizable monomer used for producing the vinyl copolymer having a carboxyl group with the polymerizable monomer having a hydroxyl group. It can be easily manufactured.

Examples of the polymerizable monomer having a hydroxyl group include:
For example, 2-hydroxyethyl (meth) acrylate,
Alkyl (meth) acrylates having a hydroxyl group such as 2-hydroxypropyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate;
(Meth) acrylic monomers to which a lactone compound represented by M-2 "and" Placcel FA-2 "(manufactured by Daicel Chemical Industries, Ltd.) are added; polyethylene glycol mono (meth) acrylate monomers; polypropylene glycol mono (meth) A) acrylate monomers; and alkyl vinyl ethers having a hydroxyl group such as hydroxyethyl vinyl ether and hydroxybutyl vinyl ether.

The polyester resin having a carboxyl group and a hydroxyl group may be reacted in a dehydration condensation reaction of the polyester resin according to a known method so that the hydroxyl group remains. The remaining hydroxyl group is an unreacted group derived from a diol compound, a polyol compound or a carboxylic acid polyol compound.

The vinyl copolymer having a carboxyl group and the polyurethane resin used in the present invention preferably have a number average molecular weight in the range of 5,000 to 20,000. When the number average molecular weight is smaller than 5,000, when the obtained aqueous pigment dispersion is used for a coating agent,
It is not preferable because the coating film tends to be brittle. On the other hand, if the number average molecular weight is larger than 20,000, a fine aqueous pigment dispersion tends to be difficult to obtain, which is not preferable.

The polyester resin used in the present invention is more preferably a branched resin, which is different from a linear vinyl copolymer or the like, even if the number average molecular weight is small. Since it has a large molecular weight, it has sufficient toughness as a coating film. Therefore, the polyester resin has a number average molecular weight of 1,000 to 20,000.
It is preferably in the range of 0, and in the weight average molecular weight,
Those in the range of 5,000 to 100,000 are preferred.

The pigment used in the present invention includes:
C. I. Pigment Yellow 185, C.I.
I. Pigment Yellow 180, C.I. I.
Pigment Yellow 139, C.I. I. Pi
gment Yellow 138, C.I. I. Pigm
ent Yellow 110, C.I. I. Pigmen
t Yellow 109 and C.I. I. Pigment
Yellow 74 is mentioned.

The pigment used in the present invention may be a powder and a solidified pigment, or a pigment dispersed in water such as an aqueous slurry or a press cake.

Next, the manufacturing method of the present invention will be described sequentially according to the steps. In the present invention, a mixed solution containing a neutralized organic polymer compound having an anionic group and a pigment is dispersed in a dispersion apparatus or the like until the pigment has a narrow particle size distribution with a predetermined particle size and is uniformly and stably finely dispersed. And thoroughly mixed to form a pigment dispersion.

This suspension usually contains a liquid medium to be dispersed in addition to the organic polymer compound and the pigment. As this liquid medium, an organic solvent or an aqueous medium is used. In the present invention, the main solvent constituting the liquid medium is
The organic solvent may be referred to as an organic solvent medium, and the water solvent may be referred to as an aqueous medium.

The following two methods are suitable for mixing and dispersing an organic polymer compound having an anionic group neutralized with a basic compound and a pigment.

(1) An organic polymer compound having an anionic group neutralized by a basic compound and a pigment are mixed in an organic solvent medium to form a suspension, and after the pigment is dispersed, the pigment is dispersed in an aqueous medium. Spread. (2) In an aqueous medium, an organic polymer compound having an anionic group neutralized with a basic compound and a pigment are mixed and dispersed.

In the dispersion in an organic solvent, which is the first method applicable to the step of mixing and dispersing an organic polymer compound having an anionic group neutralized with a basic compound and a pigment, a base is first used. To obtain a suspension containing an organic solvent solution and a pigment of an organic polymer compound having an anionic group neutralized by a neutral compound, and this is, for example, a bead mill, a ball mill,
Fine dispersion is performed using a known dispersion device such as a sand mill or a colloid mill.

At this time, the organic solvent used generally has good solubility in an organic polymer compound having an anionic group and has no problem in the synthesis of the organic polymer compound having an anionic group. Those which are higher than water and are easy to remove the solvent, and those which are miscible with water are preferred.

Examples of such a solvent include acetone, methyl ethyl ketone, methanol, ethanol, n
-Propanol, isopropanol, ethyl acetate, tetrahydrofuran and the like are particularly preferred. Although not miscible with water, methyl isopropyl ketone, methyl-n-propyl ketone, isopropyl acetate, n-propyl acetate, methylene chloride and the like can also be used.

To further disperse a pigment dispersion comprising an organic polymer compound having an anionic group neutralized with a basic compound and a pigment, dispersed in an organic solvent medium, and a pigment in an aqueous medium, Such a method is appropriate.

When dispersing in an aqueous medium, ordinary low shear stirring, high shear stirring with a homogenizer or the like, or ultrasonic waves are used. For the purpose of assisting dispersion in an aqueous medium, a surfactant, a protective colloid, or the like may be used in combination within a range that does not significantly reduce the water resistance of the coating film.

Examples of the basic compound for neutralizing the organic polymer compound having an anionic group include an inorganic base and an organic amine. Examples of the inorganic base include sodium hydroxide, potassium hydroxide, lithium hydroxide and the like. Examples of the organic amine include ammonia, ethanolamine, diethanolamine, triethanolamine, tributylamine, N-methylethanolamine, dimethylethanolamine, diisopropanolamine, N-ethyldiethanolamine, and 2-amino-2.
-Methylpropanol, 2-ethyl-2-amino-1,
3-propanediol, 2- (aminoethyl) ethanolamine, tris (hydroxymethyl) aminomethane,
Piperidine, morpholine and the like;

Next, dispersion in an aqueous medium, which is a second method applicable to the step of mixing and dispersing an organic polymer compound having an anionic group neutralized with a basic compound and a pigment, is as follows: First, the anionic group of the organic polymer compound having an anionic group is neutralized with the above-described basic compound, mixed with the pigment in an aqueous medium, and dispersed.

At this time, the organic high molecular compound having an anionic group dissolved or dispersed in water may contain an organic solvent, or even if the solvent is removed and the medium is substantially water only. Good. As the pigment, any of a powder pigment, an aqueous slurry, and a press cake can be used. When the pigment is dispersed in an aqueous medium, it is preferable to use an aqueous slurry or a press cake in which the pigment particles have a small secondary aggregation. The dispersion method, the organic solvent, and the basic compound can be the same method and the same material as those in the case of dispersion in an organic solvent medium.

As the above method for mixing and dispersing an organic polymer compound having an anionic group neutralized with a basic compound and a pigment, the former method (1) is preferred.

In the present invention, as described above, an ink jet printer comprising a pigment dispersion obtained by using a pigment dispersion and a pigment coated with a neutralized organic polymer having an anionic group by a known and usual method. To obtain an aqueous recording liquid for use.

The aqueous recording liquid of the present invention can be preferably prepared by the above method (4). More specifically, (i)
The pigment is mixed and suspended in a liquid medium containing an organic solvent having an anionic group, which has been rendered water-soluble by neutralizing the anionic group with a basic compound, and an aqueous medium which may contain an organic solvent. After the pigment is finely dispersed, the pigment is finely dispersed, and (ii) an acidic compound is added to precipitate an organic polymer compound having an anionic group, whereby the pigment has an anionic group. Coated with an organic polymer compound,
(Iii) It is preferable to add an aqueous dispersion obtained by adding a basic compound to neutralize the anionic group of the organic polymer compound having an anionic group and dispersing the same in an aqueous medium.

The step (i) of obtaining a pigment dispersion in which the pigment is uniformly finely dispersed in the liquid medium from the suspension in which the pigment is not sufficiently uniformly dispersed in the liquid medium in which the pigment is to be dispersed. Thus, a known and commonly used dispersing apparatus as described above is used. In the present invention, precipitation of an organic polymer compound having an anionic group using an acidic compound may be referred to as acid precipitation.

Regardless of whether the dispersion is an organic solvent-based dispersion or an aqueous dispersion, use of a pigment dispersant or wetting agent within the range that does not reduce the water resistance of the coating film is used for the purpose of assisting the dispersion of the pigment. Can also.

When the pigment is dispersed or after the dispersion and before the acid precipitation, substances other than the pigment, for example, a dye, an antioxidant, an ultraviolet absorber, a curing catalyst for a coating binder, a rust preventive, etc. Agents, fragrances, drugs and the like can also be added.

The ratio of the organic polymer compound having an anionic group to the pigment is 10 to 20 in terms of the solid content of the organic polymer compound having an anionic group per 100 parts by weight of the pigment.
A range of 0 parts by weight is preferred. When the amount of the organic polymer compound having an anionic group is less than 10 parts by weight,
Pigment tends to be difficult to disperse sufficiently finely,
When the amount is more than 200 parts by weight, the proportion of the pigment in the dispersion becomes small, and when the aqueous pigment dispersion is used as a coating agent or the like, there is a tendency that there is no room for the formulation design, which is not preferable.

The acid precipitation performed for coating a pigment finely dispersed in an aqueous medium with an organic polymer having an anionic group is carried out by adding an acidic compound to make the pH neutral or acidic. An organic polymer compound having an anionic group neutralized by an acidic compound is precipitated. When this acid precipitation is performed, the surface of the pigment is surely coated with the organic polymer compound, so that the organic polymer compound is present on the surface of the pigment at a conventional adsorption level,
Shows better properties.

Examples of the acidic compound used include, for example,
Inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid; formic acid, acetic acid,
Organic acids such as propionic acid can be used, but hydrochloric acid and sulfuric acid, which contain a small amount of organic substances in waste water and have a large acid precipitation effect, are preferred. The pH during acid precipitation is preferably in the range of 3 to 6, but some pigments are decomposed by acid,
In the case of such a pigment, it is preferable to carry out acid precipitation in a pH range of 4 to 7. Further, it is preferable to remove the organic solvent present in the system before the acid precipitation by using a method such as distillation under reduced pressure and distillation under normal pressure.

After the acid precipitation, if necessary, filtration and washing with water are performed to obtain a water-containing cake of the pigment coated with the organic polymer compound having an anionic group. As a filtration method, a known method such as suction filtration, pressure filtration, and centrifugation can be employed.

This water-containing cake is dried without drying.
By re-neutralizing the anionic group with a basic compound in a state of being hydrated, the pigment particles are re-dispersed in an aqueous medium while keeping a fine state without agglomeration. As a basic compound for redispersion,
The same basic compound as used for neutralizing the organic polymer compound having an anionic group can be used.

The aqueous dispersion obtained by coating the pigment with the organic polymer compound having a carboxyl group neutralized with a base thus obtained has a volume average particle diameter of 10 to 50.
Those in the range of 0 nm are preferred. When the volume average particle diameter is larger than 500 nm, it is difficult to obtain a coating film having excellent gloss, coloring properties, and coloring power, which is not preferable. In addition, a volume average particle diameter smaller than 10 nm is obtained. It is very difficult and unrealistic.

A method for evaluating an aqueous dispersion obtained by coating a pigment with an organic polymer compound having a carboxyl group neutralized with a base and obtained by the present invention includes, for example, the following method.

First, in order to further impart printing characteristics as an ink to the aqueous dispersion, ethylene glycol, glycerin, a pH adjuster, an activator, and the like are added to prepare an aqueous recording liquid for an ink jet printer, and then the cartridge is mounted on an ink jet printer cartridge. Print with stuffing.

First, the saturation of the obtained color image is measured. Further, the storage stability can be evaluated, for example, by keeping the prepared aqueous recording liquid for an ink jet printer in a constant temperature bath at 70 ° C. and measuring a change in viscosity and a change in volume average particle diameter.

As a method for forming a recorded image using the aqueous recording liquid for an ink jet printer obtained as described above, for example, various papers, sheets, films, fibers, metals, For example.

The ink jet printer is not particularly limited. For example, a piezo system using a piezoelectric element in a printer head, a thermal system in which heat energy is applied to a recording liquid to discharge the recording liquid as droplets from micro holes, and perform recording. Is raised. Furthermore, it is also possible to fix the image by applying energy such as heat or ultraviolet light after printing.

[0087]

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 following examples, “parts” and “%” are all based on weight unless otherwise specified.

The molecular weight in the following examples is G
It was measured by PC (gel permission chromatography).

Also, an inkjet printer BJC-400 manufactured by Canon Inc. was used.
J, Data Color UK (data)
SPECTRAFLASH 50 manufactured by Color Inc.)
0, R-500 type viscometer (manufactured by Toki Sangyo Co., 60 rpm)
Value), Microtrac UPA- for volume average particle size measurement
150 (Laser Doppler type particle size distribution analyzer manufactured by Nikkiso Co., Ltd.)
It was used.

<Synthesis Example 1> (Synthesis of vinyl copolymer) A three-liter four-necked flask equipped with a dropping device, a thermometer, a nitrogen gas inlet tube, a stirrer, and a reflux cooling tube was prepared.
After charging 1,000 parts of methyl ethyl ketone and raising the liquid temperature to 78 ° C. while stirring under a nitrogen seal,

Styrene 200 parts n-butyl methacrylate 400 parts n-butyl acrylate 50 parts 2-hydroxyethyl methacrylate 150 parts methacrylic acid 200 parts Perbutyl O 80 parts (tert-butyl peroxy octoate manufactured by NOF Corporation)

A mixed solution consisting of the following was dropped over 4 hours. Further, the reaction was continued at the same temperature for 8 hours. After allowing the reaction mixture to cool to room temperature, methyl ethyl ketone was added and diluted so that the nonvolatile content became 50%, to obtain an organic polymer compound solution A having an acid value of 130, a hydroxyl value of 65, and a number average molecular weight of 13,000. Was.

<Synthesis Example 2> (Synthesis of Vinyl Copolymer) A three-liter four-necked flask equipped with a dropping device, a thermometer, a nitrogen gas inlet tube, a stirrer, and a reflux condenser was prepared.
After charging 1,000 parts of methyl ethyl ketone and raising the liquid temperature to 78 ° C. while stirring under a nitrogen seal,

N-butyl methacrylate 685 parts n-butyl acrylate 25 parts 2-hydroxyethyl methacrylate 150 parts acrylic acid 140 parts perbutyl O 80 parts

A mixed solution consisting of the following was dropped over 4 hours. Further, the reaction was continued at the same temperature for 8 hours. After allowing the reaction mixture to cool to room temperature, methyl ethyl ketone was added and diluted so that the nonvolatile content became 50%, to obtain an organic polymer compound solution B having an acid value of 100, a hydroxyl value of 65, and a number average molecular weight of 9,000. Was.

<Synthesis Example 3> (Synthesis of Low Hydroxyl Value Vinyl Copolymer) A three-liter four-necked flask equipped with a dropping device, a thermometer, a nitrogen gas introducing tube, a stirring device, and a reflux condenser was prepared.
After charging 1,000 parts of methyl ethyl ketone and raising the liquid temperature to 78 ° C. while stirring under a nitrogen seal,

N-butyl methacrylate 735 parts n-butyl acrylate 50 parts 2-hydroxyethyl methacrylate 75 parts acrylic acid 140 parts perbutyl O 80 parts

A mixed solution consisting of the following was dropped over 4 hours. Further, the reaction was continued at the same temperature for 8 hours. After allowing the reaction mixture to cool to room temperature, methyl ethyl ketone was added and diluted so that the nonvolatile content became 50%, to obtain an organic polymer compound solution C having an acid value of 100, a hydroxyl value of 33, and a number average molecular weight of 9,000. Was.

<Synthesis Example 4> (Synthesis of vinyl copolymer-
Heat-crosslinking type) In a three-liter four-necked flask equipped with a dropping device, a thermometer, a nitrogen gas introduction tube, a stirring device, and a reflux cooling tube,
After charging 1,000 parts of methyl ethyl ketone and raising the liquid temperature to 78 ° C. while stirring under a nitrogen seal,

N-butyl methacrylate 335 parts n-butyl acrylate 358 parts 2-hydroxyethyl methacrylate 150 parts methacrylic acid 107 parts glycidyl methacrylate 50 parts perbutyl O 80 parts

A mixed solution consisting of the following was dropped over 4 hours. Further, the reaction was continued at the same temperature for 8 hours. After allowing the reaction mixture to cool to room temperature, methyl ethyl ketone was added and diluted so that the nonvolatile content became 50%, to obtain an organic polymer compound solution D having an acid value of 70, a hydroxyl value of 65, and a number average molecular weight of 10,000. Was.

<Synthesis Example 5> (Synthesis of Polyester Resin) A 2-liter four-necked flask equipped with a dehydrating tube, a thermometer, a nitrogen gas introducing tube and a stirring device was stirred under a nitrogen seal while stirring.

"Kajura E-10" 100 parts (glycidyl ester of synthetic fatty acid manufactured by Shell Chemical Industry Co., Ltd.) adipic acid 241 parts hexahydrophthalic anhydride 376 parts neopentyl glycol 195 parts trimethylolpropane 165 parts dibutyltin dioxide 0 .5 copies

Was heated, and the temperature was raised to 190 ° C. over 5 hours while dehydrating, and a dehydration condensation reaction was carried out at the same temperature. The acid value was measured by sampling, and the target acid value was 6
The reaction was terminated so as to be 0. After allowing the reaction mixture to cool, methyl ethyl ketone was added to dilute it so that the nonvolatile content became 65%, and the acid value was 61 and the number average molecular weight was 2.2.
An organic polymer compound solution E having a weight average molecular weight of 30,000 and a hydroxyl value per resin solid content of 60 was obtained.

<Synthesis Example 6> (Synthesis of Polyurethane Resin) In a three-liter four-necked flask equipped with a thermometer, a nitrogen gas inlet tube, a stirrer, and a reflux condenser, methyl ethyl ketone was stirred under a nitrogen seal while stirring. Charge 900 copies,

129 parts of dimethylolpropionic acid 521 parts of “Placcel 212” (polylactone diol manufactured by Daicel Chemical Industries, Ltd.) 350 parts of isophorone diisocyanate

After reacting at 78 ° C. for 2 hours, 0.1 part of dibutyltin dilaurate was added and further reacted at the same temperature for 4 hours. After allowing the reaction mixture to cool to 30 ° C., a solution prepared by dissolving 5.8 parts of ethylenediamine in 106 parts of methyl ethyl ketone was charged and reacted for 1 hour to obtain an organic solution having an acid value of 54 and a number average molecular weight of 12,000. A molecular compound solution F was obtained.

<Example 1> (1) Pigment dispersion step In a glass bottle having a capacity of 250 cc, 42.0 parts of ion-exchanged water and 2.0 parts of 10% sodium hydroxide were weighed and obtained in Synthesis Example 1 with stirring. 8.0 parts of an organic polymer compound solution A (vinyl copolymer, acid value 130, hydroxyl value 65) is added to prepare a mixed solution. Further, 8.0 parts of yellow pigment Palitolol Yellow D1155 (CI Pigment Yellow 185 manufactured by BASF).

Then, the suspension was weighed (suspension), and the average particle diameter was 0.1.
250 g of 5 mm zirconia beads were added and dispersed for 4 hours using a paint shaker (from the suspension to the pigment dispersion). After the dispersion is completed, the zirconia beads are filtered out,
A pigment dispersion composed of a pigment and an organic polymer compound having a carboxyl group neutralized with a base was obtained.

(2) Solvent Distillation Water was added to a pigment dispersion comprising an organic polymer compound having a carboxyl group neutralized with a base and a pigment, which was diluted twice, and then methyl ethyl ketone was distilled by atmospheric distillation.

(3) Acid precipitation While the aqueous pigment dispersion after solvent distillation was stirred with a disper, 1N hydrochloric acid was added to adjust the pH of the aqueous dispersion to 3 to 5, to precipitate an organic polymer compound, and to prepare a carboxyl group. The pigment was coated with an organic polymer having the following formula:

(4) Filtration and washing The slurry of the pigment coated with the organic polymer compound having a carboxyl group was suction-filtered and washed with water to obtain a water-containing cake.

(5) Neutralization and Redispersion in Aqueous Medium While stirring with a disper, a 10% aqueous solution of sodium hydroxide was added to the water-containing cake to adjust the pH of the dispersion to 8.5 to 9.5. Further, after stirring is continued for 1 hour, water is added to adjust the non-volatile content to 20%, and the pigment is coated with an organic polymer compound having a carboxyl group neutralized with a base. An aqueous dispersion A-1 containing fine particles was obtained.

(6) Preparation of aqueous recording liquid for ink jet printer Aqueous dispersion A-1 20.0 parts Ion-exchanged water 44.4 parts Ethylene glycol 4.0 parts Glycerin 8.0 parts Diethanolamine 2.4 parts Emulgen 147 (Nonionic activator manufactured by Kao Corporation) 1.2 parts

Was mixed to prepare an aqueous recording liquid for an ink jet printer containing colored fine particles obtained by coating a pigment with an organic polymer compound having a carboxyl group neutralized with a base.

The recording liquid thus prepared was packed in a cartridge of an inkjet printer BJC-400J manufactured by Canon Inc., and printed on color BJ paper (manufactured by Canon Inc.) to obtain a yellow image.

The image of this yellow was applied to a D65 light source, 10
Datacolor in UK (datacolor)
Color measurement with SPECTRAFLASH 500
The chroma C ^* was determined.

For evaluation of storage stability, the prepared recording liquid was allowed to stand in a constant temperature bath at 70 ° C., and the change in viscosity and the change in volume average particle diameter were measured. The results are shown in Table 1.
Compared with Comparative Example 1, storage stability was excellent.

Example 2 Novoperm Yellow PH-G (Cla) was used in place of the yellow pigment Palitol Yellow D1155 in Example 1.
C.l. I. Pigment Yellow
180), except that Example 180 was used.
An aqueous recording liquid for an ink jet printer containing colored fine particles coated with a pigment and an organic polymer compound having a carboxyl group neutralized with a base was prepared.

Further, in the same manner as in Example 1, the saturation of the yellow image, the change in viscosity during storage of the recording liquid, and the change in the volume average particle diameter were measured. The results are shown in Table 1. Comparative Example 1
In comparison with, storage stability was excellent.

<Example 3> Instead of the yellow pigment Paliotol Yellow D1155 in Example 1, Paliotol Yellow 1840 (BAS
F. C. I. Pigment Yellow 13
Except that 9) was used, an aqueous recording liquid for an ink jet printer was prepared in the same manner as in Example 1 and containing colored fine particles obtained by coating a pigment with an organic polymer compound having a carboxyl group neutralized with a base. .

Further, in the same manner as in Example 1, the saturation of the yellow image, the change in viscosity during storage of the recording liquid, and the change in the volume average particle diameter were measured. The results are shown in Table 1. Comparative Example 1
In comparison with, storage stability was excellent.

<Example 4> Instead of the yellow pigment Palitol Yellow D1155 in Example 1, Palitol Yellow 1090 (BAS
F. C. I. Pigment Yellow 13
An aqueous recording liquid for an ink jet printer was prepared in the same manner as in Example 1 except that 8) was used, which contained colored fine particles obtained by coating a pigment with an organic polymer compound having a carboxyl group neutralized with a base. .

Further, in the same manner as in Example 1, the saturation of the yellow image, the change in viscosity during storage of the recording liquid, and the change in the volume average particle diameter were measured. The results are shown in Table 1. Comparative Example 1
In comparison with, storage stability was excellent.

<Example 5> Instead of the yellow pigment Palitol Yellow D1155 in Example 1, Fastogen Super Yellow GR was used.
O (CI Pigm manufactured by Dainippon Ink and Chemicals, Inc.)
In the same manner as in Example 1 except that ent Yellow 110) was used, an aqueous recording liquid for an inkjet printer containing colored fine particles obtained by coating a pigment with an organic polymer compound having a carboxyl group neutralized with a base was used. Prepared.

Further, in the same manner as in Example 1, the saturation of the yellow image, the change in viscosity during storage of the recording liquid, and the change in the volume average particle diameter were measured. The results are shown in Table 1. Comparative Example 1
In comparison with, storage stability was excellent.

<Example 6> Irgazin Yellow 2GLTE (C.I. Pigment manufactured by Ciba Specialty Chemicals) was used in place of the yellow pigment Pariotol Yellow D1155 in Example 1.
Except for using Yellow 109), an aqueous recording liquid for an ink jet printer was prepared in the same manner as in Example 1 and containing colored fine particles obtained by coating a pigment with an organic polymer compound having a carboxyl group neutralized with a base. did.

Further, in the same manner as in Example 1, the saturation of the yellow image, the change in viscosity during storage of the recording liquid, and the change in the volume average particle diameter were measured. The results are shown in Table 1. Comparative Example 1
In comparison with, storage stability was excellent.

<Example 7> SUN Fast Yellow 272-4608 was used in place of the yellow pigment Palitol Yellow D1155 in Example 1.
(CI Pigmen manufactured by SUN CHEMICAL)
Example 1 except that t Yellow 74) was used.
In the same manner as in the above, an aqueous recording liquid for an ink jet printer containing colored fine particles obtained by coating the yellow pigment with an organic polymer compound having a carboxyl group neutralized with a base was prepared.

Further, in the same manner as in Example 1, the saturation of the yellow image, the change in viscosity during storage of the recording liquid, and the change in the volume average particle diameter were measured. The results are shown in Table 1. Comparative Example 1
In comparison with, storage stability was excellent.

Example 8 Instead of the organic polymer compound solution A in Example 1, the organic polymer compound solution B obtained in Synthesis Example 2 (vinyl copolymer, acid value 100, hydroxyl value 6
Except that 5) was used, an aqueous recording solution for an ink jet printer was prepared in the same manner as in Example 1 and containing colored fine particles coated with a yellow pigment with an organic polymer compound having a carboxyl group neutralized with a base. did.

Further, in the same manner as in Example 1, the saturation of the yellow image, the change in viscosity during storage of the recording liquid, and the change in the volume average particle diameter were measured. The results are shown in Table 1. Comparative Example 1
In comparison with, storage stability was excellent.

Example 9 Instead of the organic polymer compound solution A in Example 1, the organic polymer compound solution C obtained in Synthesis Example 3 (vinyl copolymer, acid value 100, hydroxyl value 3
An aqueous recording liquid for an ink jet printer was prepared in the same manner as in Example 1 except that 3) was used, in which the yellow pigment was coated with an organic polymer compound having a carboxyl group neutralized with a base and the yellow pigment was coated. did.

Further, in the same manner as in Example 1, the saturation of the yellow image, the change in viscosity during storage of the recording liquid, and the change in the volume average particle diameter were measured. The results are shown in Table 1. Comparative Example 1
In comparison with, storage stability was excellent.

<Example 10> (1) Pigment dispersion step In a glass bottle having a capacity of 250 cc, 42.0 parts of ion-exchanged water and 2.0 parts of 10% sodium hydroxide were weighed and obtained in Synthesis Example 4 with stirring. 8.0 parts of an organic polymer compound solution D (vinyl copolymer, heat-crosslinkable type) is added to obtain a mixed solution. Further, 8.0 parts of yellow pigment Palitolol Yellow D1155 (CI Pigment Yellow 185 manufactured by BASF).

Was weighed (suspension), and the average particle diameter was 0.1.
250 g of 5 mm zirconia beads were added and dispersed for 4 hours using a paint shaker. After the dispersion, the zirconia beads were separated by filtration to obtain a pigment dispersion comprising a pigment and an organic polymer compound having a carboxyl group neutralized with a base.

(2) Solvent Distillation Water was added to a pigment dispersion comprising an organic polymer compound having a carboxyl group neutralized with a base and a pigment, which was diluted twice, and then methyl ethyl ketone was distilled by atmospheric distillation.

(3) Heat treatment The pigment dispersion after solvent distillation was placed in an autoclave at 120
Heat treatment was performed at 4 ° C. for 4 hours.

(4) Acid precipitation While stirring the pigment dispersion after the heat treatment with a disper,
1N hydrochloric acid was added to adjust the pH of the pigment dispersion to 3 to 5, an organic polymer compound was precipitated, and the pigment was coated with an organic polymer compound having a carboxyl group.

(5) Filtration and Washing The pigment slurry coated with the organic polymer compound having a carboxyl group was suction-filtered and washed with water to obtain a water-containing cake.

(6) Neutralization and Redispersion in Aqueous Medium While stirring with a disper, a 10% aqueous solution of sodium hydroxide was added to the water-containing cake to adjust the pH of the dispersion to 8.5 to 9.5. Further, after stirring for 1 hour, water is added to adjust the nonvolatile content to 20%, and the pigment is coated with a cross-linked organic polymer compound having a carboxyl group neutralized with a base. Dispersion D-
1 was obtained.

(7) Preparation of aqueous recording liquid for inkjet printer Aqueous dispersion D-1 20.0 parts Ion-exchanged water 44.4 parts Ethylene glycol 4.0 parts Glycerin 8.0 parts Diethanolamine 2.4 parts Emulgen 147 (Nonionic activator manufactured by Kao Corporation) 1.2 parts

Was mixed to prepare an aqueous recording liquid for an ink jet printer containing colored fine particles obtained by coating a pigment with an organic polymer compound having a carboxyl group neutralized with a base.

The prepared recording liquid was treated in the same manner as in Example 1,
The saturation of the yellow image, the change in viscosity during storage of the recording liquid, and the change in the volume average particle diameter were measured. The results are shown in Table 1. Compared with Comparative Example 1, storage stability was excellent.

<Example 11> The procedure of Example 1 was repeated, except that the organic polymer compound solution E (polyester resin) obtained in Synthesis Example 5 was used instead of the organic polymer compound solution A in Example 1. Then, an aqueous recording liquid for an ink jet printer containing colored fine particles obtained by coating a pigment with an organic polymer compound having a carboxyl group neutralized with a base was prepared.

Further, in the same manner as in Example 1, the saturation of the yellow image, the change in viscosity during storage of the recording liquid, and the change in the volume average particle diameter were measured. The results are shown in Table 1. Comparative Example 1
In comparison with, storage stability was excellent.

<Example 12> In the same manner as in Example 1 except that the organic polymer compound solution F (polyurethane resin) obtained in Synthesis Example 6 was used instead of the organic polymer compound solution A in Example 1, Then, an aqueous recording liquid for an ink jet printer containing colored fine particles obtained by coating a pigment with an organic polymer compound having a carboxyl group neutralized with a base was prepared.

Further, in the same manner as in Example 1, the saturation of the yellow image, the change in viscosity during storage of the recording liquid, and the change in the volume average particle diameter were measured. The results are shown in Table 1. Comparative Example 1
In comparison with, storage stability was excellent.

<Comparative Example 1> Using the same organic polymer compound solution A and yellow pigment as in Example 1, an aqueous solution in which the pigment was not coated with an organic polymer compound having a carboxyl group neutralized with a base was used. A pigment dispersion was obtained.

(1) Pigment dispersing step 42.0 parts of ion-exchanged water and 2.0 parts of 10% sodium hydroxide were weighed into a glass bottle having a capacity of 250 cc, and the organic polymer obtained in Synthesis Example 1 was stirred. Add 8.0 parts of Compound Solution A to make a mixed solution. Further, 8.0 parts of yellow pigment Palitolol Yellow D1155 (CI Pigment Yellow 185 manufactured by BASF).

The resultant was weighed, 250 g of zirconia beads having an average particle diameter of 0.5 mm was added, and the mixture was dispersed for 4 hours using a paint shaker. After the dispersion, the zirconia beads were separated by filtration to obtain an aqueous dispersion comprising a pigment and an organic polymer compound having a carboxyl group neutralized with a base.

(2) Solvent Distillation Water was added to an aqueous dispersion composed of an organic polymer compound having a carboxyl group and a pigment neutralized with a base, and diluted twice with water. % Of water to obtain an aqueous dispersion a-1.

(3) Preparation of Aqueous Recording Liquid for Inkjet Printer Aqueous Dispersion a-1 20.0 parts Ion-exchanged water 44.4 parts Ethylene glycol 4.0 parts Glycerin 8.0 parts Diethanolamine 2.4 parts Emulgen 147 ( A nonionic activator manufactured by Kao Corporation (1.2 parts) was mixed to prepare an aqueous recording liquid for an inkjet printer in which a pigment was dispersed with an organic polymer compound having a carboxyl group neutralized with a base. Further, in the same manner as in Example 1, the saturation of the yellow image, the change in viscosity during storage of the recording liquid, and the change in the volume average particle diameter were measured. The results are shown in Table 1. In the case of this comparative example, unlike the coated state, the characteristics changed greatly with time, and the viscosity and particle size after storage of the recording liquid increased.

Comparative Example 2 In a glass bottle having a capacity of 250 cc, 2.7 parts of Pariotol Yellow D1155 (CI Pigment Yellow 185 manufactured by BASF) 4.5 parts of Joncryl J-61J 4.5 parts (water solubility manufactured by Johnson Polymer) Styrene-acrylic resin, acid value 195) Ion exchange water 12.8 parts

The resulting mixture was weighed, 250 g of zirconia beads having an average particle diameter of 0.5 mm was added, and the mixture was dispersed for 4 hours using a paint shaker. After the dispersion, the zirconia beads were separated by filtration. Further

Ion-exchanged water 44.4 parts Ethylene glycol 4.0 parts Glycerin 8.0 parts Diethanolamine 2.4 parts Emulgen 147 (nonionic activator manufactured by Kao Corporation) 1.2 parts

Were mixed to prepare an aqueous recording liquid for an ink jet printer containing a pigment.

The prepared recording liquid was treated in the same manner as in Example 1,
The saturation of the yellow image, the change in viscosity during storage of the recording liquid, and the change in the volume average particle diameter were measured. The results are shown in Table 1. The viscosity and particle diameter after storage of the recording liquid were greatly increased.

[0159]

[Table 1]

[0160]

[Table 2]

[0161]

[Table 3]

From the results shown in Table 1, as can be seen from the comparison between Comparative Example 1 and Example 1, pigments were prepared using an organic polymer compound having a carboxyl group and neutralized with a base obtained by the production method of the present invention. Aqueous recording liquid for an ink jet printer comprising colored fine particles coated with a conventional, aqueous recording liquid containing a conventional aqueous dispersion not coated with a pigment with an organic polymer compound, immediately after production and 70 after production
After a lapse of 7 days at 7 ° C., the change in viscosity and volume average particle diameter is small, which means that the storage stability is excellent.

[0163]

The present invention relates to an organic polymer compound having a carboxyl group neutralized with a base. I. Pigmen
t Yellow 185, C.I. I. Pigment
Yellow 180, C.I. I. Pigment Ye
low 139, C.I. I. Pigment Yellow
ow 138, C.I. I. Pigment Yellow
110, C.I. I. Pigment Yellow 10
9 and C.I. I. Pigment Yellow 74, which is an aqueous recording liquid containing colored fine particles coated with one or more yellow pigments selected from the group consisting of Pigment Yellow 74, so that a conventional aqueous dispersion in which the pigment was not coated with an organic polymer compound was used. An extremely remarkable technical effect is obtained in that an aqueous recording liquid for an ink jet printer, which cannot be obtained and has excellent storage stability and is extremely practical, can be obtained.

Claims (4)

[Claims] 1. An aqueous recording liquid for an ink jet printer, comprising colored fine particles obtained by coating a pigment with a neutralized organic polymer compound having an anionic group, and
The pigment is C.I. I. Pigment Yellow 18
5, C.I. I. Pigment Yellow 180,
C. I. Pigment Yellow 139, C.I.
I. Pigment Yellow 138, C.I. I.
Pigment Yellow 110, C.I. I. Pi
gment Yellow 109 and C.I. I. Pig
An aqueous recording liquid for an ink jet printer, which is one or more pigments selected from the group consisting of Ment Yellow 74. 2. The method for producing an aqueous recording liquid for an ink jet printer according to claim 1, wherein the organic polymer compound having an anionic group is an organic polymer compound having a carboxyl group having an acid value of 30 to 150 KOH mg / g. 3. The organic polymer compound having an anionic group has an acid value of 30 to 150 KOH mg / g and a hydroxyl value of 20.
The method for producing an aqueous recording liquid for an ink jet printer according to claim 1 or 2, which is an organic polymer compound having a carboxyl group and a hydroxyl group of from 120 to 120 KOH mg / g. 4. A pigment is dispersed in a mixed solution of an organic polymer having an anionic group, which has been rendered water-soluble by neutralizing an anionic group with a basic compound, and an aqueous medium. The pigment is coated with an organic polymer having an anionic group by precipitating an organic polymer having an anionic group, and then a basic compound is added to remove the anionic group of the organic polymer having an anionic group. 4. The aqueous recording liquid for an ink jet printer according to claim 1, comprising an aqueous dispersion neutralized and dispersed in an aqueous medium.