JPH0841395A - Method for producing dye dispersion for inkjet recording liquid - Google Patents

Abstract

(57) [Abstract] [Purpose] A method for producing a pigment dispersion for inkjet recording liquid, in which pigments, oil-soluble dyes, and other pigments are dispersed in a liquid containing an aqueous medium and a dispersant, without using media. A method for producing a dye dispersion liquid for an inkjet recording liquid, characterized in that the dye is made into fine particles. As a method of atomizing without using the medium, a method of colliding liquids containing an aqueous medium, a dispersant and a dye, which are pressurized by a high pressure pump, from two directions is preferable. [Effect] It is possible to obtain an aqueous dye dispersion liquid in which foreign matters originating from media, containers, etc. are remarkably little mixed, and especially in a thermal jet printer,
Since contamination due to mixing of the foreign matter on the heater surface is small, good ejection stability and long life of the printer can be achieved, and even in an inkjet printer using a piezo piezoelectric element, there is little clogging at the nozzle tip,
Stable discharge is possible for a long time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a dye dispersion suitable for preparing a recording liquid for ink jet, especially for thermal ink jet.

[0002]

2. Description of the Related Art Conventionally, a roll mill, a ball mill, a sand grind mill or the like has been used as a method for making a dye into fine particles. When a roll mill is used, the dispersion of the dye in a liquid having a low viscosity is milled. The efficiency is extremely low, and when a ball mill and a sand grind mill are used, the media such as glass beads used for atomization or the collision between the media and the container causes crushing and abrasion of the media and the container, and the pigment dispersion liquid There is a big problem that it is unavoidable to mix in foreign substances derived from those constituent substances.

Usually, glass, zirconia, stainless steel or the like is used as the material of the media used for the above-mentioned fine particle formation, and stainless steel or urethane-coated stainless steel or the like is used as the material of the container. In addition to metal ions such as Fe, Si, Zr and colloids of these metals, minute particles such as urethane are also conceivable.

As a problem caused by mixing of these foreign matters, for example, in a general ink jet printer, there is clogging at the tip of the nozzle. Further, in a thermal inkjet (for example, bubble jet) printer of a type that ejects ink by heating, there is kogation at the heater portion. All of these make ink ejection from the printer unstable, which is a fatal problem for the printer.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for producing a dye dispersion liquid which is suitable for the preparation of a recording liquid for ink jet, especially for thermal ink jet, and in which the inclusion of foreign matters is extremely small. .

[0006]

SUMMARY OF THE INVENTION The gist of the present invention is to provide a method for producing an ink-jet dye dispersion, which comprises a dye dispersed in a liquid containing an aqueous medium and a dispersant. A method for producing a dye dispersion liquid for an inkjet recording liquid, which is characterized in that it is made into fine particles.
Hereinafter, the present invention will be described in detail. The present inventors, as a result of various studies on the ratio of fine particles in the aqueous medium of the dye,
By pressurizing an aqueous liquid containing a dye to a high pressure and then colliding with each other, it was found that a dye dispersion liquid containing less foreign matter from an apparatus used for atomization can be produced.
The present invention has been achieved.

The aqueous medium used in the present invention is mainly composed of water, but it is preferable to use a water-soluble organic solvent added to this water. Examples of the water-soluble organic solvent include ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol (# 200, # 400), glycerin,
Alkyl ethers of the above glycols, N-methylpyrrolidone, 1,3-dimethylimidazolinone, thiodiglycol, 2-pyrrolidone, sulfolane, dimethylsulfoxide, diethanolamine, triethanolamine, ethanol, isopropanol and the like can be mentioned. Further, as a moisturizing component, sodium hyaluronate, sodium pyrrolidonecarboxylate, sodium lactonate, etc. may be added.

Examples of the dispersant used in the present invention include various anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, and polymeric dispersants. . Anionic surfactants include fatty acid salts, alkyl sulfate ester salts, alkylbenzene sulfonates, alkylnaphthalene sulfonates, sulfosuccinates, alkyl sulfosuccinates, alkyl diphenyl ether disulfonates, alkyl phosphates, polyoxyethylene. Examples thereof include alkyl sulfate ester salts, polyoxyethylene alkylallyl sulfate ester salts, alkane sulfonates, naphthalene sulfonic acid formalin condensates, polyoxyethylene alkyl phosphate esters, α-olefin sulfonates and the like. Nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, oxyethylene / oxypropylene block copolymers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid Examples thereof include esters, glycerin fatty acid esters, polyoxyethylene fatty acid esters, polyoxyethylene alkylamines and the like. Examples of the cationic surfactant and the amphoteric surfactant include alkylamine salts, quaternary ammonium salts, alkylbetaines and aminoxides. As the polymer dispersant, polyacrylic acid, styrene / acrylic acid copolymer, styrene / acrylic acid / acrylic acid ester copolymer, styrene / (anhydrous) maleic acid copolymer, styrene / (anhydrous) maleic acid Acid / acrylic acid ester copolymer, styrene / methacrylic acid copolymer,
Styrene / methacrylic acid / acrylic acid ester copolymer, styrene / (anhydrous) maleic acid half ester copolymer, vinyl naphthalene / (anhydrous) maleic acid copolymer, vinyl naphthalene / acrylic acid copolymer or salts thereof, etc. (In addition, (anhydrous) maleic acid represents "maleic anhydride or maleic acid"). Among these dispersants, anionic surfactants, nonionic surfactants and polymer dispersants are particularly excellent.

The dye used in the present invention is a dye which is not dissolved in an aqueous medium but dispersed, and pigments such as carbon black and oil-soluble dyes, dyes for resin coloring, etc. can be used and are commercially available products. Can be used as is. Specific examples include dyes such as Solvent Yellow, Solvent Red, Solvent Violet, Solvent Blue, Solvent Green, Solvent Black, Pigment Yellow, Pigment Red, Pigment Violet, Pigment Blue, and Pigment Black described in the Color Index. However, other than these, dyes such as phthalocyanine dyes, azo dyes, anthraquinone dyes, azomethine dyes, and condensed ring dyes can also be used. In addition, yellow No. 4, No. 5, No. 205, No. 4
No. 01 Orange No. 204 Red No. 104, 201, 202, 204, 2
In addition to organic pigments such as No. 20, 226 to 228, No. 405, Blue No. 1, No. 404, etc., inorganic pigments such as titanium oxide, zinc oxide, zirconium oxide, iron oxide, ultramarine blue, dark blue, and chrome oxide can also be used. . The particle size of these dyes before atomization is usually 5 to 10
It is about 0 μm. It is also possible to use two or more of these dyes together for the purpose of toning. In addition to the various components described above, various additives such as a water-soluble resin, an antifungal agent, a bactericide, a pH adjuster, and urea may be added if necessary.

In the present invention, in order to reduce the mixing of foreign matter from the dispersing device, the dye is made into fine particles without using a medium. Preferably, the above components are mixed to form a slurry, which is made into a high-speed fluid under high pressure to collide with each other and the pigment is dispersed by the impact at that time. Dispersion of the dye is preferably carried out until the particle diameter of the dye becomes approximately 2 μm or less, whereby the dye is maintained in a stable dispersed state without settling in an aqueous medium. As such a mutual collision type dispersion device, there is Nanomizer (registered trademark) sold by Nanomizer Co., Ltd.

FIG. 1 is an exploded perspective view for explaining the structure of the nanomizer. In addition, A represents the flow path of the dye-containing liquid in this apparatus. As shown in Figure 1, Nanomizer
Two discs 11 (front disc) and 12
It has a (rear disc), the front disc side retainer 13 is provided in front of the front disc 11, and the rear disc 1
Rear disc-side restraints 14 are installed behind 2 respectively.

The front disk 11 is provided with two through holes 111 and a connecting groove (orifice) 112 for connecting the two through holes. On the other hand, rear disc 1
2 is provided with two through holes 121 and a connecting groove (orifice) 122 that connects these two through holes.
Then, the front disk 11 and the rear disk 12 are set so that the connecting groove 112 and the connecting groove 122 are 90 degrees out of phase so as to form a cross shape.

In FIG. 1, the dye-containing liquid pressurized from the front disk 11 side by a high pressure pump or the like to about 200 to 2000 kg / cm ² is divided into two and flows into two through holes of the front disk 11 and is accelerated. Then, the two flow-through holes flow into the orifice formed by the flat surface of the rear disk 12 and the connecting groove 112 of the front disk 11, and are further accelerated toward the central portion of the orifice to reach the maximum flow velocity. When the two collide with each other at the center of the connecting groove 112, the pigment is crushed and dispersed in the aqueous medium at the same time, and is composed of the connecting groove 122 of the rear disk 12 and the flat surface of the front disk 11 which are formed by shifting the phase by 90 degrees. Dispersion of dye into ultrafine particles from two orifices through the two through holes 122 of the rear disk 12 Next, it is discharged from the rear disc 12 side. In addition, in order to enhance the dispersion efficiency of the dye, it is preferable to cool the entire apparatus with brine or the like. As the cooling temperature, the temperature of the dye dispersion liquid discharged after atomization is preferably about 10 to 20 ° C.

In the dispersion treatment using such a mutual collision type dispersion device, the dispersion treatment can be efficiently carried out by using the high concentration dye-containing liquid, so that the high concentration dye-containing liquid is used. It is preferable to carry out a dispersion treatment and dilute the obtained treatment liquid with an aqueous medium to obtain an ink as a final product. For example, 3 to 20 wt%, preferably 5 to 15
Dispersion treatment is performed using a dye-containing liquid of about wt%, and the obtained treatment liquid is 0.5 to 5 wt%, preferably 2 to 4 w.
The final product, ink, is diluted to about t%. Usually, it is advantageous to carry out the dispersion treatment using a dye-containing liquid having a dye concentration of at least twice, preferably at least three times the dye concentration of the final product ink.

[0015]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples as long as the gist thereof is not exceeded. Example 1

[0016]

[Table 1] Composition of dispersion Amount used (part) Glycerin 34 Liporan PB-800 4 (α-olefin sulfonate-based dispersant, manufactured by Lion Corporation) Carbon black MA230 11 (average particle size before atomization 4 μm , Mitsubishi Kasei Co., Ltd.) Ion-exchanged water 51 ────────────────────────────────── Total 100

The mixed solution having the above composition was pulverized with a nanomizer at a pressure of 1700 kg / cm ² four times to form ultrafine particles. The average particle size of carbon black in the obtained dispersion was 0.14 μm. Further, the content of Fe and Si in the dispersion liquid was analyzed by an inductively coupled plasma emission spectrophotometer, and it was 1 ppm or less. This dispersion was mixed with an equal weight of ion-exchanged water to prepare a recording liquid for an inkjet printer. (Evaluation of ejection stability of recording liquid) Desk Jet 120
0C (Thermal jet printer, Hewlett
When the ejection stability of the recording liquid was evaluated using a Packard product, 400 ml of ink could be ejected stably.

Comparative Example 1 The mixed solution having the same composition as in Example 1 was atomized by a sand grinder using glass beads as a medium. The average particle size of carbon black was 0.25 μm. The content of Fe in the dispersion is 350 ppm, Si
Was 2100 ppm. Using this dispersion, the ejection stability as a recording liquid was evaluated in the same manner as in Example 1. When 80 ml of ink was ejected, some nozzles failed. When the surface of the heater in the nozzle was checked, Fe and Si were found to be deposited, which probably deteriorated the heat transfer property of the heater and resulted in ejection failure. Example 2

[0019]

Table 2 Composition of dispersion Amount used (parts) Diethylene glycol 30 Polystar S-2-10205 (Styrene-maleate dispersant, manufactured by NOF CORPORATION) Pigment Red 122 7 (average particle before atomization) Diameter 38 μm) Ion-exchanged water 58 ────────────────────────────────── Total 100

The mixed solution having the above composition was pulverized 3 times at a pressure of 1400 kg / cm ^{2 in the same} manner as in Example 1 to form ultrafine particles. Pigment, a quinacridone pigment
The average particle size of Red122 was 0.37 μm. Using this dispersion, a recording liquid for an inkjet printer was prepared in the same manner as in Example 1, and the ejection stability was evaluated. As a result, 400 ml of ink could be ejected stably. Examples 3 to 11 Dispersion treatments were carried out in the same manner as in Example 1 using the dyes shown in Table 1 below to prepare ultrafine particle dye dispersion liquids. Table 1 collectively shows the pressure and frequency of atomization and the average particle size of the dye after the treatment.

[0021]

[Table 3]

[0022]

According to the method for producing a dye dispersion liquid of the present invention,
It is possible to obtain an aqueous dye dispersion liquid in which foreign matter originating from the dispersion device is remarkably little mixed, and in particular, in the thermal jet type printer in which bubbles are generated by heat and ink is ejected, the heater surface is contaminated by foreign matter. As a result, the ejection stability can be maintained, and the life of the printer can be expected to be extended. Further, also in an inkjet printer using a piezo piezoelectric element, there is little clogging at the nozzle tip, and stable ejection over a long period of time can be expected.

[Brief description of drawings]

FIG. 1 is an exploded perspective view for explaining a structure of a nanomizer, which is an apparatus suitable for finely dispersing and dispersing a dye in a production method of the present invention.

[Explanation of symbols]

11 Front Disc 12 Rear Disc 13 Front Disc Side Suppression 14 Rear Disc Side Suppression 111 Front Disc Through Hole 112 Groove (Orifice) Connecting Two Through Holes 111 121 Rear Disc Through Hole 122 Connecting Two Through Holes 121 Groove (Orifice) A Dye-containing liquid flow path

Claims (4)

[Claims] 1. A method for producing a dye dispersion for an inkjet recording liquid, which comprises a dye dispersed in a liquid containing an aqueous medium and a dispersant, wherein the dye is finely divided without using a medium. A method for producing a dye dispersion liquid for an inkjet recording liquid. 2. The ink jet recording liquid according to claim 1, wherein the dye containing the aqueous medium, the dispersant and the dye is pressurized to collide with each other in two directions to form the dye into fine particles. Method for producing dye dispersion. 3. The method for producing a dye dispersion liquid for an inkjet recording liquid according to claim 1 or 2, which is used for preparing a recording liquid for a thermal inkjet recording liquid. 4. The method for producing a dye dispersion liquid for an inkjet recording liquid according to claim 1, wherein the dye is carbon black.