JPH11166145A - Production of water-base recording fluid for ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a water-base recording fluid for ink jet printers which has excellent storage stability. SOLUTION: A water-based pigment dispersion for ink jet printers is obtained by feeding a suspension into a disperser composed of an external fixed container (I) having an inlet and an outlet for the suspension, a separator, and a cylindrical inner wall and a cylindrical rotor (II) being rotatable about a rotation axis and provided inside the container (1) so as to leave a certain clearance between the both, wherein the rotor (II) has a hollow liquid chamber, a slit capable of feeding the suspension into the liquid chamber and opponent to the inlet, and a plurality of liquid discharge ports communicating with the outside of the liquid chamber and formed on the side wall of the cylinder; and the external fixed container (I) is distant from the external periphery of the rotor so as to leave a certain clearance between the both (I) and (II) and has a separator having a plurality of holes smaller in diameter than the dispersion medium; and the dispersion medium is packed in the clearance between the rotor and the separator at such a rate as to give a residence time of 30 sec or shorter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel and useful method for producing an aqueous recording liquid for an ink jet printer.

[0002]

2. Description of the Related Art In response to recent environmental problems, in the field of using printing inks and paints, the use of water-based paints is rapidly increasing.
Most of the pigments used in water-based inks and water-based paints are organic pigments, and are more difficult to disperse in water than non-aqueous dispersions due to the large surface tension of water.

[0003] As a method of dispersing a pigment in water, conventionally,
Various methods have been presented and implemented.

[0004] For example, T.I. C. Patton's "P
aint Flow and Pigment Dis
version "(John Wiley & Son
, p. 386, 1979) describes a method for dispersing a pigment using a ball mill, pebble mill, high-speed disk impeller, high-speed collision mill, three-roll mill, high-speed stone mill, colloid mill, sand mill, batch mill, or the like. .

[0005] In the examples of JP-A-56-157470, examples of pigment polymer production using a ball mill, an attorter and a sand mill are described. U.S. Pat. No. 5,310,778 describes a method of dispersing with a two-roll mill.

[0006] Further, "Latest Pigment Dispersion Technology" (published by Technical Information Association Co., Ltd. on January 6, 1993) includes three rolls, ball mills, attritors, sand mills and sand mills. There are described a ball mill, a pearl mill PM-DCP type in which a short path is narrowed and a basket mill in which the entire inside of a tank flows by stirring media in a net, and the like.

Among the above dispersers, sand mills, coball mills, pearl mills PM-DCP type, dyno mills, bore mills, visco mills, motor mills and the like are generally used as flow-type wet bead mills for dispersing pigments. In a flow-type wet bead mill, a sample is fed into a disperser by a liquid feed pump, and beads, which are a dispersion medium (media) filled in the disperser, are rotated by a stirring blade, and the beads, the stirring blade, the inner wall of the disperser, and the like are rotated. In some cases, the sample is dispersed by collisions generated between the particles, and then circulated as needed to further disperse the sample. Then, only the sample is separated and collected through a slit.

[0008] In addition, a horizontal wet bead mill has conventionally been the mainstream, but a vertical one has recently appeared and has been improved so as not to cause a bias of beads.

In any of these dispersers, the dispersed particle size of the pigment can be controlled to some extent by setting conditions such as output, rotation speed and operation time.

In general, it is desirable that the pigment be as fine as possible in order to enhance the color developability and transparency, and that the state be maintained stably. In particular, a demand for a pigment dispersion used in an aqueous recording liquid for an ink jet printer requires a higher degree of fineness, and a high-dispersion type disperser such as the pearl mill has become mainstream. Also, distributed media
From glass beads, zirconia beads having higher hardness have been used.

However, on the other hand, the finer the pigment, the finer the pigment and the more the primary particles of the pigment are crushed,
Furthermore, an increase in surface energy causes an increase in cohesion energy at the same time, so that re-aggregation is liable to occur, resulting in a disadvantage that storage stability of the finely divided pigment dispersion is impaired.

In order to improve the storage stability of a pigment-based aqueous recording liquid for an ink jet printer, various additives for miniaturization and stabilization are added to the dispersion in addition to the intended aqueous resin. Is generally widely practiced.

However, the aqueous recording liquid for an ink jet printer containing a pigment dispersed using a surfactant is liable to bleed on the surface because the molecular weight of the surfactant is small, and the resulting image has a high water resistance. There is a problem that the performance is extremely poor and the utility is poor.
In addition, it is generally more difficult to disperse the pigment in an aqueous medium containing a water-soluble resin than in the case of dispersing the pigment in an organic solvent medium, and the pigment is finely dispersed at a high level, and It is difficult to keep that 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, and even if 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 of improving the dispersibility of the pigment, an acid is added to an aqueous dispersion of the pigment 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.

In order 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 any of these methods, the pigment is solidified or powdered 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 highly hydrophilic water-soluble resin, is re-neutralized with a basic compound after acid precipitation, and is easily dispersed in an aqueous medium. Are disclosed.

However, the basic structure of this method is a method of powdering or solidifying after re-neutralizing with a basic compound, and 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.

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, etc. in order to add printing characteristics as an ink.
Even with the aqueous pigment dispersion obtained by the method as described in JP-A-8-321 and JP-A-9-31360, distribution of the above-mentioned sand mill, coball mill, pearl mill PM-DCP type, dyno mill, bore mill, biscomil, motor mill, etc. Aqueous recording liquid for inkjet printers manufactured by a wet-type bead mill cannot avoid crushing the primary particles of the pigment, causing an increase in viscosity and particle size during storage, and the storage stability of the recording liquid is at a practical level. Has not yet been resolved.

[0023]

An object of the present invention is to provide a method for producing an aqueous recording liquid for an ink jet printer which prevents primary particles of the pigment from being crushed and thus has an excellent storage stability. It is in.

[0024]

The inventors of the present invention have conducted intensive studies on a method for producing a new and useful aqueous recording liquid for an ink jet printer, and as a result, have obtained a pigment dispersion using a specific dispersing apparatus under specific conditions. By producing an aqueous recording liquid for an inkjet printer in which a pigment is coated with an organic polymer compound having a neutralized anionic group, it is possible to obtain an aqueous recording liquid for an inkjet printer having excellent storage stability. Heading,
The present invention has been completed.

That is, the present invention provides the following inventions. (1) A method for producing an aqueous recording liquid for an ink jet printer comprising a pigment coated with a neutralized organic polymer compound having an anionic group, the method comprising: In mixing the suspension containing the pigment and finely dispersing the pigment into a pigment dispersion, as a dispersing device, having a supply port and a discharge port for the suspension, an inner wall having a separator having a cylindrical inner wall is externally fixed. A container (I) and a cylindrical rotor (II) provided inside the container with a predetermined gap and rotatable about a rotation axis,
The rotor (II) has a hollow liquid chamber inside the cylinder,
A rotor (II) having a slit facing the supply port, through which the suspension can be supplied toward the liquid chamber, and a plurality of liquid discharge holes in a cylindrical side wall communicating with the outside of the liquid chamber; ) Is an external fixed container (I) in which a separator having a plurality of holes having a predetermined diameter smaller than the dispersion medium and provided on a cylindrical inner wall, facing the outer peripheral wall surface of the rotor via a predetermined gap, Using a dispersing device filled with a dispersing medium in the gap between the rotor and the separator, the suspension is introduced into the liquid chamber from the supply port of the container (I) toward the slit of the rotor while rotating the rotor (II). To discharge the suspension from the discharge hole by centrifugal force and remove the suspension that has passed through the separator via the dispersion medium from the discharge port of the container (I). Is less than 30 seconds The suspension was supplied, a manufacturing method of an inkjet printer aqueous recording liquid pigment finely dispersed, characterized in that the pigment dispersion.

(2) The method for producing an aqueous recording liquid for an ink jet printer as described in (1) above, wherein the rotation axis of the rotor (II) is provided horizontally.

(3) A container for holding the suspension and a circulation pump are further provided, and a liquid discharge port, a container for holding the suspension, and circulation so that the pigment becomes a pigment dispersion having a predetermined particle size. A pump and a liquid supply port are connected in this order, and the suspension is circulated so as to be in the above-mentioned staying time range. The method for producing an aqueous recording liquid for an ink jet printer according to the above.

(4) The aqueous recording liquid for an ink jet printer according to the above (1), (2) or (3), 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. Production method.

(5) The organic polymer having an anionic group is an organic polymer 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. 5. The method for producing an aqueous recording liquid for an ink jet printer according to item 3 or 4.

(6) An organic polymer having an anionic group, which has been rendered water-soluble by neutralizing an anionic group with a basic compound, is mixed with an aqueous medium and a pigment to form a suspension. In order to uniformly and finely disperse the pigment in the medium, an external fixed container (I) having a cylindrical inner wall having a separator having a supply port and a discharge port for the suspension and having a predetermined gap therein is provided as a dispersing apparatus. And a cylindrical rotor (II) rotatable about the rotation axis, the rotor (II) having a hollow liquid chamber inside the cylinder, and supplying the suspension toward the liquid chamber. A rotor (II) having a slit facing the supply port and a plurality of liquid discharge holes in a cylindrical side wall communicating with the outside of the liquid chamber, and the external fixed container (I).
Is an external fixed container (I) in which a separator having a plurality of holes having a predetermined diameter smaller than the dispersion medium, which is opposed to a circumferential outer wall surface of the rotor via a predetermined gap, is provided on a cylindrical inner wall, In the gap between the rotor and the separator, a dispersion device filled with a dispersion medium is used.
While rotating I), the suspension is supplied to the liquid chamber from the supply port of the container (I) toward the slit of the rotor, and the suspension is discharged from the discharge hole by centrifugal force. When the suspension that has passed through the separator is taken out from the discharge port of the container (I), the suspension is supplied so that the residence time in the dispersing device is 30 seconds or less, and the pigment is finely dispersed. After preparing a pigment dispersion, an acidic compound is added to precipitate an organic polymer compound having an anionic group, thereby coating the pigment with an organic polymer compound having an anionic group. The ink-jet printer according to the above 1, 2, 3, 4 or 5, wherein the anionic group of the organic polymer compound having the above is neutralized and dispersed in an aqueous medium to form an aqueous dispersion, and an ink is prepared using the aqueous dispersion. Aqueous recording liquid Manufacturing method.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention relates to a method for producing an aqueous recording liquid for an ink jet printer, wherein a pigment is coated with an organic polymer compound having a neutralized anionic group. A specific dispersing apparatus is used for mixing a suspension containing the compound and the pigment and finely dispersing the pigment into a pigment dispersion.

The dispersion apparatus used in the present invention is as described in the above (1). For example, as shown in FIG. 1, a dispersion medium stirring type dispersion apparatus having a rotor and a separator in a short cylindrical pulverizing section. Is mentioned.

Hereinafter, description will be made with reference to FIG. The dispersion device that can be used in the present invention is an external fixed container (I) [hereinafter, referred to as an external fixed container 1]. ], A cylindrical rotor (II) [hereinafter, referred to as a cylindrical rotor 2] via a predetermined gap. ] Are provided so as to be rotatable about the rotation shaft 3 thereof. The direction of the rotation axis 3 is arbitrary, but it is preferable that the rotation axis 3 is horizontal, that is, parallel to the ground surface, for the reason described later. In FIG. 1, it is shown in a preferred orientation. The container 1 is provided with a supply port 4 for supplying a suspension containing a pigment and a discharge port 9.

A separator 8 having a plurality of holes having a predetermined diameter through which the pigment particles in the suspension containing the pigment have a predetermined particle diameter is fixed to the inner wall of the external fixed container 1. The gap between the container 1 and the rotor 2 is filled with particles of a dispersion medium 7 having a predetermined diameter for crushing the pigment in the suspension.

On the other hand, a hollow liquid chamber 6 is provided inside the cylinder of the rotor 2 so that the suspension containing the pigment supplied from the supply port 4 can be further supplied to the liquid chamber 6. ,
A slit 5 is formed as a ring-shaped cut having a shape sandwiched between two circles of different radii about the rotation axis. The slit 5 faces the supply port 4.

The cylindrical side wall of the rotor 2 is provided with a plurality of liquid discharge holes (without reference numerals) communicating with the outside of the liquid chamber 6 as shown by arrows. Each liquid discharge hole of the rotor 2 has a diameter larger than that of the particles of the dispersion medium 7, and the suspension is discharged from the liquid discharge holes. The diameter of each hole connected to the discharge port 9 is smaller than the particles of the dispersion medium 7, so that the dispersion medium 7 itself does not flow out to the discharge port 9.

The outer peripheral wall surface of the rotor 2 and the separator 8 are opposed to each other, and the suspension is filled with particles of the dispersion medium 7 from the liquid chamber 6 and the rotor 2.
Is supplied to the gap through the liquid discharge hole.

The suspension is supplied from the supply port 4 to the slit 5
The liquid is supplied to the liquid chamber 6 as shown by an arrow. When the suspension is supplied to the hollow liquid chamber 6 in a state where the rotor 2 is rotated about the rotation shaft 3, the pigment is pulverized based on a principle peculiar to the dispersing device.

A feature of the apparatus used in the present invention is that, when the rotor 2 is rotated, a centrifugal force is generated, and the medium 7 is pressed in layers on the inner wall of the separator 8. At the same time, a strong shearing force is generated between the media 7 due to the rotational movement of the rotor 2. Furthermore, since the centrifugal force and the flowing direction of the suspension containing the pigment are the same, uniform pulverization / dispersion and discharge of the suspension at a large flow rate from the separator 8 are possible. Stay time can be shortened.

The pigment in the suspension discharged from the liquid discharge hole by centrifugal force is pulverized in the gap filled with the particles of the dispersion medium 7, and is mixed with pigment particles smaller than the hole diameter provided in the separator 8. At this point, it passes through the hole and is taken out of the discharge port 9 together with the liquid medium of the suspension. The pigment dispersion in which the pigment is finely dispersed in this manner is taken out to the discharge port 9.

The reason why the rotating shaft 3 of the rotor 2 is made horizontal is to make full use of the effect of this centrifugal force.

The operating conditions of the dispersion apparatus used in the present invention are preferably such that the residence time of the sample in the dispersion apparatus is 30 seconds or less / pass (pass). When the residence time of the sample is long, primary particles of the pigment are easily broken, and a sharp particle size distribution cannot be obtained. Other operating conditions (speed,
The dispersion sample temperature, dispersion time, etc. are not particularly limited, but are appropriately set according to the size (capacity) of the apparatus, the type and amount of the dispersion sample, the target particle size distribution, and the like.

In the present invention, as described above, a suspension containing the specific organic polymer compound and the pigment is passed (passed) through the dispersing apparatus as described above, whereby a pigment dispersion in which the pigment is finely dispersed is obtained. Get. The supply of the suspension to the supply port 4 is usually performed by a pump (not shown), and the suspension is always supplied to the liquid chamber 6.
Is preferably supplied continuously so that is satisfied.

The suspension is once passed (passed) through a dispersion device.
In the case where a pigment dispersion in which the pigment is finely dispersed is not sufficiently obtained by merely performing the above, it is preferable to pass the pigment two or more times. The content of pigment particles having a predetermined particle size smaller than the hole and occupying the liquid medium is higher in the liquid medium when passing twice or more times than in the first pass. By repeating this process until the content of the pigment particles in the suspension passed through the dispersing device is saturated and constant, it was pulverized to a predetermined particle diameter smaller than the hole diameter of the separator 8 and finely dispersed in the liquid medium. A pigment dispersion in which pigment particles are uniformly and stably finely dispersed can be obtained.

When the suspension is repeatedly processed to obtain a pigment dispersion, a container (not shown) for holding the suspension and a circulation pump (not shown) are further provided. The liquid discharge port 9, the container for holding the suspension, the circulation pump, and the liquid supply port 4 are connected in this order so that the pigment dispersion liquid has a predetermined particle size. It is preferable to circulate so as to be in the range of the stay time.

In the present invention, the type of the dispersion medium 7 to be filled between the container 1 and the rotor 2 is not particularly limited, and examples thereof include glass beads, zirconia beads, steel beads, and ceramic beads. The filling amount of the beads is also not particularly limited, but is desirably set to 20 to 50% of the volume in the gap as an example.

As the size of the beads becomes finer, the dispersing ability increases, but on the other hand, a large pressure is required for separating the beads with a separator. 0.1-1
mm beads are used.

Next, a suspension containing a pigment and an organic polymer compound having a neutralized anionic group and used for obtaining the pigment dispersion of the present invention will be described.

The pigment used in the present invention is not particularly limited, and conventionally known pigments can be used. For example, quinacridone pigments, quinacridone quinone pigments, dioxazine pigments, phthalocyanine pigments, anthrapyrimidine pigments, anthanthrone pigments, indanthrone pigments, flavanthrone pigments, perylene pigments, diketopyrrolo Pyrrole pigments, perinone pigments,
Organic pigments such as quinophthalone pigments, anthraquinone pigments, thioindigo pigments, benzimidazolone pigments and azo pigments, and inorganic pigments such as carbon black, titanium oxide, and red iron oxide. Further, conventionally known pigment derivatives such as azo, phthalocyanine and quinacridone pigment derivatives can be appropriately used.

These may be used as a powder, as a wet cake, or as an aqueous slurry. Further, a water-soluble organic solvent can be appropriately used.

As the organic polymer compound having an anionic group used in the present invention, known and commonly used ones can be used, and the acid value based on the anionic group (KOH mg /
Organic polymer compounds having g) in the range of 30 to 150 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.

Examples of the polymerizable monomer having a carboxyl group include monoalkyl maleates such as acrylic acid, methacrylic acid, crotonic acid, fumaric acid, itaconic acid, (anhydrous) maleic acid and monobutyl maleate, and monobutyl itaconate. And monoalkyl itaconates, and the like, with acrylic acid, methacrylic acid and maleic acid being particularly preferred.

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; acrylic acid Acrylic esters such as ethyl, n-butyl acrylate, methyl acrylate, 2-hydroxyethyl acrylate, methyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, isoamyl methacrylate, methacryl 2-ethylhexyl acrylate, 2-hydroxyethyl methacrylate, isodecyl methacrylate, lauryl methacrylate, stearyl methacrylate, cyclohexyl methacrylate, butoxymethyl methacrylate, ethoxydiethylene methacrylate Call, benzyl methacrylate, cetyl methacrylate, tetrahydrofurfuryl methacrylate, such as methacrylic acid esters of isobornyl methacrylate; vinyl acetate, vinyl benzoate, vinyl versatate, vinyl esters such as 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 methacrylate, dimethylamino methacrylate Ethyl, N-vinylimidazole, N-
Tertiary amino group-containing monomers such as vinylcarbazole; 2- (2′-hydroxy-5-methacryloyloxyethylphenyl) -2H-benzotriazole,
Hydroxy-4- (2-methacryloyloxyethoxy)
Benzophenone, 1,2,2,6,6-pentamethyl-
Monomers having ultraviolet absorbing or antioxidant properties such as 4-piperidyl methacrylate; N-vinylpyrrolidone, glycidyl methacrylate, 1,3-dioxolan-2-one-4-ylmethyl methacrylate, 1,3-dioxolan-2 -On-4-ylmethyl vinyl ether,
Functional group-containing monomers such as N-alkoxymethyl (meth) acrylamides such as diacetone acrylamide, N-methylolacrylamide, and N-butoxymethyl (meth) acrylamide; γ-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane Monomers having a hydrolyzable alkoxysilane group such as 2-phosphooxyethyl methacrylate and 4-methacrylic acid 4-
Phosphoryl group-containing monomers such as phosphooxybutyl; macromonomers having one polymerizable unsaturated group at the molecular terminal; and the like, with preference given to 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate and styrene. .

As a method for polymerizing 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 polyester resin having a carboxyl group used in the present invention is prepared by subjecting a carboxyl group-containing compound and a hydroxyl group-containing compound to a dehydration condensation reaction 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, (anhydride) succinic acid, sebacic acid, dimer acid, (anhydride) maleic acid, (phthalic anhydride), 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 the 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 the 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 component 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 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.

The organic polymer compound having an anionic group used in the present invention preferably has a hydroxyl group in addition to a carboxyl group, and has a hydroxyl value based on a hydroxyl group (KOH mg / g) of 20 to 120. Those in the range are more preferred. The hydroxyl value is expressed in mg of KOH in an equimolar number with glacial acetic acid necessary to neutralize 1 g of the resin solids.

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. When used in baking paints, baking inks, printing agents, and the like, the hydroxyl groups bonded to the organic polymer compound can react with a curing agent to form a stronger film.

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, alkyl acrylates having a hydroxyl group such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, and 4-hydroxybutyl methacrylate; alkyl methacrylates; "Placel FM-2", " Praxel FA-
2 "(manufactured by Daicel Chemical Industries, Ltd.), methacrylic monomers to which a lactone compound is added; polyethylene glycol methacrylate monomers; polypropylene glycol monomethacrylate monomers; hydroxyl groups such as hydroxyethyl vinyl ether and hydroxybutyl vinyl ether And the like, and particularly preferred are 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate.

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.

Since the polyester resin used in the present invention is mostly of a branched type, unlike the case of a linear vinyl copolymer, the weight average molecular weight is low even when the number average molecular weight is small. Since it is large, it has sufficient toughness as a coating film. Therefore, the polyester resin preferably has a number average molecular weight in the range of 1,000 to 20,000, and has a weight average molecular weight of 5,
Those in the range of 000 to 100,000 are preferred.

Next, the manufacturing method of the present invention will be described sequentially according to the steps. In the present invention, the suspension containing a neutralized organic polymer compound having an anionic group and a pigment is dispersed as described above until the pigment has a narrow particle size distribution at a predetermined particle size and is uniformly and stably finely dispersed. Pass through the apparatus and mix thoroughly 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
An organic solvent is called an organic solvent medium, and water is called 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 with a basic compound and a pigment are mixed in an organic solvent medium to form a suspension, and the pigment is dispersed. Spread. (2) An organic polymer compound having an anionic group neutralized with a basic compound and a pigment are mixed and dispersed in an aqueous medium.

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 of an organic polymer compound having an anionic group and a pigment neutralized with an anionic compound and a pigment. Is finely dispersed using a dispersion medium stirring type dispersion apparatus having the above.

At this time, the organic solvent used generally has good solubility in the 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, the dispersion in an aqueous medium, which is the 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 polymer 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. 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.

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

As the above method of 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, a pigment dispersion is obtained, and the pigment is coated with a neutralized organic polymer compound having an anionic group by a known and commonly used 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 (6). 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 and finely dispersed in the liquid medium from the suspension in which the pigment is not sufficiently and uniformly dispersed in the liquid medium to be dispersed. Thus, the specific 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.

Further, 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 having an anionic group to the pigment is 10 to 20 in terms of the solid content of the organic polymer 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 compound 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.

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 wet cake was 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 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.

The 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, ethylene glycol, glycerin, a pH adjuster, an activator, and the like are added to the aqueous dispersion to prepare an aqueous recording liquid for an inkjet printer in order to further impart printing characteristics as an ink. And print the image.

Further, the storage stability was evaluated, for example, by preparing the prepared aqueous recording liquid for an ink jet printer at 70 ° C.
Can be evaluated by measuring the change in viscosity and the change in volume average particle diameter by keeping the sample in a constant temperature bath.

As a method of 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 method using a piezoelectric element in a printer head, a thermal method in which thermal energy is applied to a recording liquid to discharge the recording liquid as droplets from micropores and perform recording, and the like. Is raised. Furthermore, it is also possible to fix the image by applying energy such as heat or ultraviolet light after printing.

The aqueous pigment dispersion produced as described above can be used extremely practically as an aqueous recording liquid for an ink jet printer.

[0112]

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.

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

Further, an inkjet printer BJC-400 manufactured by Canon Inc. was used.
J, R-500 type viscometer (Toki Sangyo Co., Ltd., 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 Styrene / Acrylic 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 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 200 parts methacrylic acid 80 parts perbutyl O 80 parts (tert-butyl peroxyocto available from NOF Corporation) Eat)

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 low acid value styrene / acrylic 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. To
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 700 parts N-butyl acrylate 50 parts 2-hydroxyethyl methacrylate 150 parts Acrylic acid 100 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 65, a hydroxyl value of 65, and a number average molecular weight of 9,000. Was.

<Synthesis Example 3> (Synthesis of Low Hydroxyl Value Acrylic 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 Heat-Crosslinking 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 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,

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.

<Example 1> (1) Pigment dispersion step 4.6 parts of 20% sodium hydroxide and 5 parts of ion-exchanged water
5.4 parts were added, and 20 parts of the organic polymer compound solution A obtained in Synthesis Example 1 was added to the portion where the mixture became homogeneous, and the mixture was stirred to neutralize the carboxyl groups in the organic polymer compound by 100%. Then, the organic polymer compound was dissolved in water.

Next, Fastogen Blue T
GR (copper phthalocyanine blue pigment CI Pigment Blue 1 manufactured by Dainippon Ink and Chemicals, Inc.)
5: 3) Slowly add 20 parts with stirring, and add 3 parts.
The mixture was stirred well for 0 minutes to obtain a suspension of copper phthalocyanine blue pigment.

A suspension of the obtained copper phthalocyanine blue pigment was dispersed in a dispersion medium stirring type dispersion device (vessel capacity 2 L) having an external fixed container and an internal stirring device (rotor) and having a horizontal rotor rotation axis as shown in FIG. , Motor capacity 15kw)
To obtain an aqueous dispersion (pigment dispersion) composed of an organic polymer compound having a carboxyl group neutralized with a base and a pigment.

A container for holding the suspension and a circulation pump are further provided, and the liquid discharge port, the container for holding the suspension, the circulation pump, and the liquid supply port are connected in this order. The suspension was circulated in the holding container until the pigment became a pigment dispersion having a predetermined particle size within the above-mentioned staying time range.

The dispersion conditions at this time were as follows: the rotation speed of the internal stirring device of the dispersion device was 1650 rpm, and the medium was 0.3 m
mφ zirconia beads (YTZ manufactured by Nikkato Corporation)
(Beads) The filling rate was 40%, the supply rate of the copper phthalocyanine blue pigment suspension per hour was 900 L (residence time in the dispersing machine 8 seconds / pass), and circulation dispersion was performed for 1 hour.

(2) Solvent distillation Water was added to an aqueous dispersion (pigment dispersion) composed of an organic polymer compound having a carboxyl group and a pigment neutralized with a base, and diluted twice with water. Was distilled.

(3) Acid precipitation While stirring the aqueous dispersion after the solvent distillation with a disper,
1N hydrochloric acid was added to adjust the pH of the aqueous 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.

(4) 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.

(5) Neutralization and Redispersion in Aqueous Medium Under 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 continuing stirring for 1 hour, water is added to adjust the nonvolatile content to 20%, and the aqueous solution obtained by coating the pigment with an organic polymer compound having a carboxyl group neutralized with a base is added. A pigment dispersion A-1 was obtained.

(6) Preparation of aqueous recording liquid for inkjet printer Aqueous pigment 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

Were mixed to prepare an aqueous recording liquid for an ink jet printer in which a pigment was coated 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 ink jet printer BJC-400J manufactured by Canon Inc., and printed on color BJ paper (manufactured by Canon Inc.). As a result, a cyan image having sufficiently good color development was obtained.

Further, as an 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. The change in viscosity and the change in volume average particle size were small and the storage stability was excellent.

Example 2 A non-volatile component 2 was prepared in the same manner as in Example 1 except that the organic polymer compound solution A in Example 1 was replaced with the organic polymer compound solution B obtained in Synthesis Example 2.
A 0% aqueous pigment dispersion B-1 was obtained.

The aqueous pigment dispersion B-1 was prepared and printed in the same manner as in Example 1 by using an aqueous recording liquid for an ink jet printer. As a result, a cyan image having a sufficiently high color development was obtained.

Further, in the same manner as in Example 1, the change in viscosity and the change in volume average particle size during storage of the recording liquid were measured. The results are shown in Table 1. The change in viscosity and the change in volume average particle size were small and the storage stability was excellent.

Example 3 A non-volatile component 2 was prepared in the same manner as in Example 1 except that the organic polymer compound solution A in Example 1 was replaced with the organic polymer compound solution C obtained in Synthesis Example 3.
A 0% aqueous pigment dispersion C-1 was obtained.

The aqueous pigment dispersion C-1 was prepared and printed in the same manner as in Example 1 by using an aqueous recording liquid for an ink jet printer, and as a result, a cyan image having a sufficient color development was obtained.

Further, in the same manner as in Example 1, a change in viscosity and a change in volume average particle diameter during storage of the recording liquid were measured. The results are shown in Table 1. The change in viscosity and the change in volume average particle size were small and the storage stability was excellent.

Example 4 A pigment was dispersed in place of the organic polymer compound solution A in Example 1 in place of the organic polymer compound solution D obtained in Synthesis Example 4, and the solvent was distilled off. Then, an aqueous pigment dispersion D-1 having a nonvolatile content of 20% was obtained in the same manner as in Example 1 except that the dispersion was heated at 120 ° C. for 4 hours.

The aqueous pigment dispersion D-1 was prepared and printed in the same manner as in Example 1 in an aqueous recording liquid for an ink jet printer, and as a result, a cyan image having a sufficiently high color development was obtained.

Further, in the same manner as in Example 1, the change in viscosity and the change in volume average particle size during storage of the recording liquid were measured. The results are shown in Table 1. The change in viscosity and the change in volume average particle size were small and the storage stability was excellent.

<Example 5> The pigment in Example 1 was replaced with Fa.
stoken Super Magenta RY (a quinacridone pigment manufactured by Dainippon Ink and Chemicals, Inc. C.I.
I. Pigment Red 122) to obtain an aqueous pigment dispersion A-2 having a nonvolatile content of 20% in the same manner as in Example 1.

The aqueous pigment dispersion A-2 was prepared and printed in an aqueous recording liquid for an ink jet printer in the same manner as in Example 1, and as a result, a sufficiently good magenta color image was obtained.

Further, in the same manner as in Example 1, a change in viscosity and a change in volume average particle size during storage of the recording liquid were measured.
The results are shown in Table 1. Compared with Comparative Example 2, the change in viscosity and the change in volume average particle size were small and the storage stability was excellent.

<Example 6> The pigment in Example 1 was replaced with Sy
aqueous Fastener dispersion A- having a non-volatile content of 20% in the same manner as in Example 1 except that the former was replaced with Muller Fast Yellow 4192 (benzimidazolone pigment CI Pigment Yellow 154 manufactured by Dainippon Ink and Chemicals, Inc.). 3 was obtained.

The aqueous pigment dispersion A-3 was prepared and printed in an aqueous recording liquid for an ink jet printer in the same manner as in Example 1, and as a result, a yellow image having sufficiently good color development was obtained.

Further, in the same manner as in Example 1, the change in viscosity and the change in volume average particle diameter during storage of the recording liquid were measured. The results are shown in Table 1. The change in viscosity and the change in volume average particle size were small and the storage stability was excellent.

<Example 7> An aqueous pigment dispersion A-4 having a nonvolatile content of 20% was prepared in the same manner as in Example 1 except that the pigment in Example 1 was changed to carbon black # 960 (manufactured by Mitsubishi Chemical Corporation). I got

The aqueous pigment dispersion A-4 was prepared and printed in an aqueous recording liquid for an ink jet printer in the same manner as in Example 1, and as a result, a black image having sufficiently good color development was obtained.

Further, in the same manner as in Example 1, the change in viscosity and the change in volume average particle diameter during storage of the recording liquid were measured. The results are shown in Table 1. As compared with Comparative Example 3, the change in viscosity and the change in volume average particle diameter were small and the storage stability was excellent.

<Comparative Example 1> 20% sodium hydroxide
6 parts and 55.4 parts of ion-exchanged water were added, and the mixture was made uniform, and the organic polymer compound solution A obtained in Synthesis Example 1 was added.
20 parts were added and stirred to neutralize 100% of the carboxyl groups in the organic polymer compound and to dissolve the organic polymer compound in water.

Next, Fastogen Blue T
GR (copper phthalocyanine blue pigment CI Pigment Blue 1 manufactured by Dainippon Ink and Chemicals, Inc.)
5: 3) Slowly add 20 parts with stirring, and add 3 parts.
The mixture was stirred well for 0 minutes to obtain a suspension of copper phthalocyanine blue pigment.

The suspension of the obtained copper phthalocyanine blue pigment was dispersed using a stirrer type bead mill DCP-3 (manufactured by Dry Swerke Co., Ltd., capacity 12 L, motor capacity 45 kw), and carboxyl neutralized with a base was dispersed. An aqueous pigment dispersion (pigment dispersion) comprising an organic polymer compound having a group and a pigment was obtained.

The dispersion conditions at this time were as follows:
rpm, 0.3 mmφ zirconia beads (YTZ beads manufactured by Nikkato Co., Ltd.) filling rate: 80%, supply amount of the copper phthalocyanine blue pigment suspension per hour: 516
L (residence time in the dispersing machine: 84 seconds / pass), the dispersion was circulated for 1 hour.

After pigment dispersion, an aqueous pigment dispersion A-5 having a nonvolatile content of 20% was obtained in the same manner as in Example 1.

As a result of preparing and printing the aqueous pigment dispersion A-5 in an aqueous recording liquid for an ink jet printer in the same manner as in Example 1, no satisfactory cyan image was obtained.

Further, as an 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. The viscosity and particle diameter after storage of the recording liquid were greatly increased.

Comparative Example 2 A suspension of the quinacridone pigment obtained in Example 5 was dispersed in the same dispersing machine DCP-
After dispersion under the same conditions as in Comparative Example 1, the aqueous pigment dispersion A-6 was obtained in the same manner as in Comparative Example 1.

The aqueous pigment dispersion A-6 was prepared and printed in an aqueous recording liquid for an ink jet printer in the same manner as in Example 1. As a result, no satisfactory magenta image was obtained.

Further, in the same manner as in Comparative Example 1, the change in viscosity and the change in volume average particle size during storage of the recording liquid were measured.
The results are shown in Table 1. The viscosity and particle diameter after storage of the recording liquid were greatly increased.

<Comparative Example 3> A suspension of the carbon black pigment obtained in Example 7 was mixed with a stirring type bead mill apparatus System Zeta LMZ-10 (manufactured by Ashizawa Co., Ltd., capacity 1).
0 L, motor capacity 22 kW). The dispersion conditions at this time were as follows: a stirrer rotation speed of 900 rpm, 0.3 m
mφ zirconia beads (YTZ manufactured by Nikkato Corporation)
(Beads) 80% filling rate, 816 L supply amount per hour of suspension of carbon black pigment (dwell time in dispersing machine: 4
(4 seconds / pass) for 1 hour.

After dispersing the pigment, an aqueous pigment dispersion A-7 having a nonvolatile content of 20% was obtained in the same manner as in Example 1.

As a result of preparing and printing the aqueous pigment dispersion A-7 in an aqueous recording liquid for an ink jet printer in the same manner as in Example 1, no satisfactory black color image was obtained.

Further, as an evaluation of storage stability, the prepared recording liquid was allowed to stand in a constant temperature bath at 70 ° C., and a change in viscosity and a change in 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.

[0172]

[Table 1]

From the results shown in Table 1, the aqueous recording liquid for an ink jet printer comprising a pigment coated with an organic polymer compound having a carboxyl group neutralized with a base obtained by the production method of the present invention was obtained. Immediately after and 70 ° C after production 7
It can be understood that the storage stability is excellent since the change in the viscosity and the volume average particle diameter is small after a lapse of days.

[0174]

According to the present invention, there is provided a method for producing an aqueous recording liquid for an ink jet printer, wherein a pigment is coated with a neutralized organic polymer compound having an anionic group. Ink is prepared using a pigment dispersion liquid in which a pigment is finely dispersed by using a dispersion medium stirring type dispersion apparatus having a dispersion medium having a dispersion time of 30 seconds or less in the dispersion apparatus. An extremely remarkable effect is obtained in that an aqueous recording liquid for an inkjet printer having excellent storage stability and extremely high practicality can be obtained as compared with the case where the pigment dispersion is prepared using the pigment dispersion obtained using

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an example of a dispersion apparatus used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 External fixed container 2 Cylindrical rotor 3 Rotor rotation axis 4 Supply port 5 Slit 6 Liquid chamber 7 Dispersion media 8 Separator 9 Discharge port

Claims (6)

[Claims] 1. A method for producing an aqueous recording liquid for an ink jet printer, wherein a pigment is coated with a neutralized organic polymer compound having an anionic group, wherein the organic polymer has a neutralized anionic group. In mixing the suspension containing the compound and the pigment, and in finely dispersing the pigment into a pigment dispersion, as a dispersing device, having a supply port and a discharge port for the suspension, the inner wall having a separator has a cylindrical shape. An external fixed container (I), and a cylindrical rotor (II) provided inside thereof with a predetermined gap and rotatable around a rotation axis,
The rotor (II) has a hollow liquid chamber inside the cylinder,
A rotor (II) having a slit facing the supply port, through which the suspension can be supplied toward the liquid chamber, and a plurality of liquid discharge holes in a cylindrical side wall communicating with the outside of the liquid chamber; ) Is an external fixed container (I) in which a separator having a plurality of holes having a predetermined diameter smaller than the dispersion medium and provided on a cylindrical inner wall, facing the outer peripheral wall surface of the rotor via a predetermined gap, Using a dispersing device filled with a dispersing medium in the gap between the rotor and the separator, the suspension is introduced into the liquid chamber from the supply port of the container (I) toward the slit of the rotor while rotating the rotor (II). To discharge the suspension from the discharge hole by centrifugal force and remove the suspension that has passed through the separator via the dispersion medium from the discharge port of the container (I). Is less than 30 seconds The suspension was supplied, a manufacturing method of an inkjet printer aqueous recording liquid pigment finely dispersed, characterized in that the pigment dispersion. 2. The method for producing an aqueous recording liquid for an ink jet printer according to claim 1, wherein the rotation axis of the rotor (II) is provided horizontally. 3. A container for holding the suspension and a circulation pump, wherein a liquid discharge port, a container for holding the suspension, and a circulation pump are provided so that the pigment becomes a pigment dispersion having a predetermined particle size. ,
The liquid supply port is connected so as to be in this order, and the suspension is circulated so as to be in the range of the staying time, and the suspension is repeatedly processed to obtain a pigment dispersion. Of producing an aqueous recording liquid for an ink jet printer. 4. An organic polymer compound having a carboxyl group having an acid value of 30 to 150 KOH mg / g, wherein the organic polymer compound having an anionic group is an organic polymer compound having an acid value of 30 to 150 KOH mg / g.
The method for producing an aqueous recording liquid for an ink jet printer according to the above. 5. 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.
5. The method for producing an aqueous recording liquid for an ink jet printer according to claim 1, which is an organic polymer compound having a carboxyl group and a hydroxyl group of from 120 to 120 KOH mg / g. 6. An aqueous polymer and a pigment are mixed with an organic polymer compound having an anionic group, which is made water-soluble by neutralizing an anionic group with a basic compound, to form a suspension. To uniformly and finely disperse the pigment therein, an external fixed container (I) having a cylindrical inner wall having a separator having a supply port and a discharge port of the suspension and having a predetermined gap therein is used as a dispersing apparatus. And a cylindrical rotor (II) provided rotatable about the rotation axis.
Has a hollow liquid chamber inside the cylinder, has a slit facing the supply port through which the suspension can be supplied toward the liquid chamber, and has a plurality of liquid discharge holes in a cylindrical side wall communicating with the outside of the liquid chamber. A rotor (II), wherein the outer fixed container (I) faces a circumferential outer wall surface of the rotor via a predetermined gap, and has a cylindrical inner wall having a plurality of holes having a predetermined diameter smaller than the dispersion medium. An external fixed container (I) provided in the container, and a dispersing device filled with a dispersing medium is used in a gap between the rotor and the separator, and the rotor (II) is rotated from the supply port of the container (I) while rotating. The suspension is supplied to the liquid chamber toward the slit of the rotor, the suspension is discharged from the discharge hole by centrifugal force, and the suspension that has passed through the separator via the dispersion medium is discharged into the container (I). When removing from the exit, the dispersing device After the suspension is supplied so that the residence time in it is 30 seconds or less, and the pigment is finely dispersed to form a pigment dispersion, an acidic compound is added to precipitate an organic polymer compound having an anionic group. The pigment is coated with an organic polymer compound having an anionic group by adding, and then a basic compound is added to neutralize the anionic group of the organic polymer compound having an anionic group and dispersed in an aqueous medium to disperse in an aqueous medium. Claims 1 and 2, wherein the ink is prepared by using the
6. The method for producing an aqueous recording liquid for an ink jet printer according to 3, 4 or 5.