JPH11131004A - Production of water-based pigment recording liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water-based pigment type recording liquid for ink jetting with excellent storage stability and ink-jetting stability, relating to the production process for water-based pigment type recording liquid. SOLUTION: When a water-based pigment type recording liquid is produced, a high-pressure homogenizer is used to lessen the number of steps of the production process. In addition, the channel of the recording liquid is controlled to 5 deg.C to 25 deg.C whereby a water-based pigment type recording liquid for ink jetting can be produced that has excellent storage stability and the ink-jetting stability.

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 an aqueous pigment recording liquid, and more particularly to a method for providing an aqueous pigment recording liquid for inkjet which has excellent storage stability.

[0002]

2. Description of the Related Art Dyes have generally been used as coloring materials for recording liquids. However, from the viewpoint of water resistance and weather resistance of the recorded matter, it is more advantageous to use a pigment than a dye. As the liquid medium, an aqueous liquid medium is more advantageous than a non-aqueous liquid medium from the viewpoint of bleeding on plain paper.

Heretofore, pigments have been placed in a closed apparatus together with an aqueous solvent and various additives, and fine beads of ceramic, glass, steel, etc. have been put thereinto, and subjected to impact or grinding action in the closed apparatus. The recording liquid has been produced while finely pulverizing the pigment.

However, in such a method for producing a recording liquid, the beads used for dispersion may be pulverized, and the pulverized beads may be mixed into the recording liquid, thereby deteriorating the quality of the recording liquid.

[0005] In addition, during dispersion, heat is generated by collision of pigments, beads, and the like, and thermal deterioration of additives such as dispersants occurs, thereby deteriorating the properties of the recording liquid.

Further, it takes a long time to disperse the pigment, and after the dispersion, the beads and the recording liquid must be separated by filtration or the like, which complicates the process and shortens the production time.

In Japanese Patent Application Laid-Open No. 7-305006,
Although a method for producing a pigment ink using a high-pressure homogenizer has been proposed, if the temperature of the ink flow path is not controlled to a low temperature, heat is generated around the orifice during dispersion, and the dispersion stability of the produced recording liquid is impaired. . When a recording liquid is manufactured using a normal high-pressure homogenizer, the ink flow path temperature may be 70 ° C. or higher, and additives and the like may be deteriorated due to high temperature, and the dispersion stability of the manufactured recording liquid may be deteriorated. There are cases.

[0008]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems and to prevent impurities such as beads from being mixed into the produced recording liquid, and to prevent deterioration of the recording liquid due to heat generated during the production. By preventing the dispersibility, the pigment dispersibility in the aqueous liquid medium and the long-term storage stability thereafter are excellent, and at the same time, the process after dispersing the recording liquid can be simplified and the production time can be shortened. Another object of the present invention is to provide a method for producing an aqueous pigment-based recording liquid for an ink jet printer which is excellent in weather resistance.

[0009]

In order to solve the above-mentioned problems, the present invention provides a method for producing an aqueous pigment-based recording liquid in which a pigment, an aqueous liquid medium, and various additives are dispersed by using a high-pressure homogenizer. , Pressure drop, shear force,
A method for producing an aqueous pigment-based recording liquid without dispersing the recording liquid and dispersing the recording liquid because the pigment is pulverized and dispersed by the impact force, and the dispersion is not brought into contact with the recording liquid such as beads. Is what you do.

In addition, when the recording liquid is dispersed by the high-pressure homogenizer, by controlling the temperature of the recording liquid flow path to a low temperature of 50 ° C. or less, it is possible to produce a recording liquid having excellent storage stability.

Further, after the production of the recording liquid by a high-pressure homogenizer, the recording liquid may be purified by centrifugal separation, filtration, etc., if necessary.

The temperature of the recording liquid flow path during dispersion of the recording liquid by the high-pressure homogenizer is preferably controlled to 50 ° C. or lower, more preferably to 5 ° C. to 25 ° C.

The recording liquid produced according to the present invention comprises a pigment and an aqueous liquid medium, and may contain various additives if necessary. These various additives are appropriately added to the recording liquid as needed. Examples of such additives include a dispersant, a pH adjuster, a surface tension adjuster, an antioxidant, an ultraviolet absorber, And stabilizers and fungicides.

(Function) If the dispersibility of the pigment is poor, the pigment particles aggregate and settle in the recording liquid. Even if the initial dispersibility is good, the dispersibility is reduced in a short time with the passage of time, and those in which the pigment particles are aggregated have poor storage stability.

In order to improve the storage stability of the recording liquid, it is necessary to improve the dispersion stability of the pigment in an aqueous liquid medium. Therefore, the dispersant is adsorbed on the surface of the finely pulverized pigment, and the steric hindrance of the dispersant is utilized, or the dispersion of the pigment is stabilized by utilizing the electric repulsion.

In the present invention, by using a high-pressure homogenizer and controlling the temperature of the recording liquid flow path, the dispersant is efficiently adsorbed on the finely pulverized pigment surface in a stable state, and at the same time, various other additives are used. And the like can be dispersed in a stable state, and a recording liquid that can withstand long-term storage can be produced.

[0017]

Next, the present invention will be described in more detail with reference to examples. However, this example does not limit the present invention. In each of the examples and comparative examples, the description of (20/35/45) of the copolymer in the compounding ratio indicates the polymerization ratio of each monomer in the copolymer.

[0018]

(Example 1) Hydraulic type in which the recording liquid flow path was adjusted to 20 ° C after pre-dispersion for 1 hour using a homogenizer while performing ultrasonic treatment at a temperature of 20 ° C at the following compounding ratio. A recording solution was prepared using a high-pressure homogenizer (manufactured by Micro Fredericks Corporation).

Carbon black (Special Black 4 manufactured by Degussa Co., Ltd.) 20% by weight Styrene-methacrylic acid-methyl methacrylate copolymer 10% by weight (20/35/45); molecular weight about 40,000 glycerin 20% by weight triethylamine 0.03% by weight % Pure water 49.97% by weight

(Example 2) The recording liquid flow path was set at 2 with the following compounding ratio.
A recording liquid was prepared using a hydraulic high-pressure homogenizer (manufactured by Micro Fredericks Corporation) whose temperature was adjusted to 0 ° C.

[0021] Recording solution of Example 1 20% by weight polyethylene glycol; molecular weight about 200 10% by weight Pure water 70% by weight

(Comparative Example 1) A recording liquid composition adjusted to the following compounding ratio was put in a closed container together with glass beads of 1 mm and vibrated for 12 hours with a paint conditioner. Then, the glass beads were filtered, and the recording liquid was filtered. Produced.

Carbon black (Special Black 4 manufactured by Degussa) 20% by weight Styrene-methacrylic acid-methyl methacrylate copolymer 10% by weight (20/35/45); molecular weight about 40,000 glycerin 20% by weight triethylamine 0.03% by weight % Pure water 49.97% by weight

(Comparative Example 2) A recording liquid composition adjusted to the following compounding ratio was placed in a closed container together with glass beads of 1 mm and vibrated for 12 hours with a paint conditioner. Then, the glass beads were filtered to prepare a recording liquid. did.

The recording liquid of Comparative Example 1 20% by weight polyethylene glycol; molecular weight about 200 10% by weight Pure water 70% by weight

(Comparative Example 3) A hydraulic high-pressure homogenizer (Micro Fredericks, Inc.) at the following compounding ratio without temperature control
Corp.) to prepare a recording liquid. The channel temperature at that time was 70 ° C.

[0027] Recording solution of Example 1 20% by weight polyethylene glycol; molecular weight about 200 10% by weight Pure water 70% by weight

The recording liquids obtained in Examples 1 and 2 and Comparative Examples 1 to 3 were evaluated by the following evaluation methods.

Evaluation Method of Dispersion Stability Immediately after the production of the recording liquid and after leaving it at 50 ° C. for one month, the particle size of the pigment was measured, and the change in the particle size was examined.

As a result, the change in particle size was 5% or less. The change in particle size was 5 to 10%. The change in particle size was evaluated as 10% or more.

The results of evaluations in Examples 1 and 2 and Comparative Examples 1 to 3 are shown in Table 1 below. Each example showed good dispersion stability. On the other hand, the recording liquids of Comparative Examples were all inferior in dispersion stability. As described above, the results of Examples and Comparative Examples show that the recording liquids produced by the production method of the present invention have excellent pigment dispersion stability.

[0032]

[Table 1]

[0033]

As described above, according to the method for producing a recording liquid of the present invention, the number of production steps is small, the pigment dispersibility is high,
A recording liquid having excellent storage stability can be provided. Further, since the recording liquid prepared by the production method of the present invention has excellent storage stability as described above, when used for ink jet recording, it provides good results in ejection stability.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Maki Takizawa, 840 Takeno, Shimotomi, Tokorozawa-shi, Saitama Prefecture Citizen Watch Co., Ltd.

Claims (2)

[Claims] 1. A method for producing an aqueous pigment-based recording liquid in which a pigment, an aqueous liquid medium, various additives, and the like are dispersed using a high-pressure homogenizer, wherein the temperature of the recording liquid channel is set to 50 ° C. when the recording liquid is dispersed by the high-pressure homogenizer. A method for producing an aqueous pigment-based recording liquid, characterized by maintaining the temperature at the following low temperature. 2. The method for producing an aqueous pigment-based recording liquid according to claim 1, wherein the temperature of the flow path of the recording liquid is maintained at 5 ° C. to 25 ° C. during dispersion of the recording liquid by a high-pressure homogenizer.