JP3214930B2 - Inkjet recording ink - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an azo dye and an ink jet recording ink using the same.

[0002]

2. Description of the Related Art In ink jet recording, in order to perform good recording over a long period of time, it is necessary that the ink used satisfies the following conditions.

(1) As ink properties according to a method of generating droplets and a method of controlling the direction of flight of droplets, the viscosity, surface tension, specific conductivity, and density of the ink are included in appropriate ranges. Precipitation must not occur due to chemical changes during use for a period of time, or during recording suspension, and ink physical properties must not change. The discharge nozzle of the recording apparatus generally has a diameter of 10
When the nozzle is clogged due to precipitation,
Eventually, the droplets cannot be discharged. Even if the nozzle is not completely dull, if solids or sticky substances adhere to the vicinity of the nozzle, or if the ink physical property value adjusted to the desired value during ink preparation changes, the recording performance, ejection stability, and ejection response will decrease. I do.

(2) The recorded image has sufficiently high contrast and is sharp.

In the conventional ink, the contrast of an image is increased by increasing the content of the dye in the ink. However, in such a method, the clogging of the discharge nozzle is easily caused. Therefore, a dye having high solubility in a solvent used for the ink and a high absorption coefficient has been demanded, but a satisfactory dye has not yet been obtained.

(3) The printed image dries quickly.

In the conventional ink, a large amount of a wetting agent is contained in the ink in order to prevent nozzle clogging due to drying of the ink in the nozzle during recording suspension. Hastened drying. However, the use of such specialty paper has the drawback that not only does image bleeding occur significantly, but also that many general papers cannot be used.

(4) The recorded image must be a clear image free from bleeding, as a matter of course, in terms of water resistance, light resistance and abrasion resistance.

Many ink-jet recording inks have been proposed to satisfy the above-mentioned requirements, but none of the inks satisfying all of the above conditions has been obtained yet. It is.

[0010]

The present invention has been made in view of the above situation. An object of the present invention is to provide an ink jet recording ink that satisfies all the above conditions. Another object of the present invention is to provide a dye suitable for use in the ink and a method for producing the dye.

[0011]

The present invention provides (1) an azo dye represented by the following general formula (1).

[0012]

Embedded image

(Wherein R ¹ and R ² are each an alkyl group,
Represents an alkoxy group, a halogen atom or a hydrogen atom, which may be the same or different. n is 1 to
4, M + represents an alkali metal, amine cation or ammonium ion)

[0014]

(2) The method for producing a dye as described in (1) above, wherein the pigment represented by the following formula is stirred and dissolved in sulfuric acid.

[0016]

Embedded image

(Wherein R ¹ and R ² are each an alkyl group,
Represents an alkoxy group, a halogen atom or a hydrogen atom, which may be the same or different. )

[0018]

( 3 ) An ink jet recording ink containing at least one of the azo dyes described in (1) above.

Particularly preferred azo dyes represented by the general formula (1) of the present invention include:

[0021]

Embedded image

And the like.

[0023]

[0024]

[0025]

The azo dye of the present invention can be easily produced by sulfonating the corresponding azo pigment.

In general, sulfonation includes a method using fuming sulfuric acid, a method using chlorosulfuric acid, a method using sulfur oxide, and the like. In the case of the compounds of this patent, the reaction proceeds simply by dissolving the pigment in sulfuric acid.

The ink-jet recording ink of the present invention contains water, a water-soluble organic solvent, and, if necessary, a preservative / antifungal agent in addition to the dye represented by the above general formula. A specific electric conductivity adjuster, a chelating reagent, a rust preventive, and the like can also be appropriately compounded.

As the water-soluble organic solvent, a mixed solvent of diethylene glycol and glycerin is suitable. In addition, ethylene glycol, triethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, etc. There is.
The pH adjuster that can be suitably used in the present invention includes, without adversely affecting the ink to be prepared,
Any substance can be used as long as H can be controlled in the range of 9-11. Examples thereof include amines such as diethanolamine and triethanolamine, hydroxides of alkali metal elements such as lithium hydroxide, sodium hydroxide and potassium hydroxide, and alkali metal such as ammonium hydroxide, lithium carbonate, sodium carbonate and potassium carbonate. Carbonates and the like.

Other substances that can be added to the ink include the following.

The specific electric conductivity of the ink is

[0032]

(Equation 1)

[0033] (25 ° C.) for the on or more specific electric conductivity modifier as for example potassium chloride, ammonium chloride, sodium sulfate, sodium carbonate, inorganic salts such as sodium carbonate, water-soluble amines such as triethanolamine There is.

As the chelating reagent, for example, sodium ethylenediaminetetraacetate, sodium nitrilotriacetate,
Sodium hydroxyethylethylenediamine triacetate, uramil sodium acetate and the like.

Examples of the rust preventive include acid sulfites,
Examples include sodium thiosulfate, ammonium thioglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, and dicyclohexylammonium nitrite.

Examples of the water-soluble preservatives and fungicides include sodium 2,2-dimethyl-6-acetoxy-dioxane-1,3 dihydroacetate, butyl p-hydroxybenzoate,
Potassium sorbate, sodium 2-pyridinethiol-1-oxide anionic surfactant and the like.

In addition, a water-soluble ultraviolet absorber, a water-soluble infrared absorber, a magnetic fluid comprising a magnetite long fine particle dispersion, a latex emulsion and the like can be added according to the purpose.

As a recording member to which the ink jet recording ink of the present invention is applied, a member capable of sufficiently absorbing the ink liquid or a member having no ink absorbing ability can be used. Paper, plastic film, metal plate and glass can be mentioned. Further, the present invention uses a recording member having a surface coating layer containing a pigment, a binder, and a water-soluble salt of a metal having an ionic valence of 2 or more as a water resistance improving agent. The effect can be further enhanced.

[0039]

The present invention will be described in more detail with reference to the following Examples along with Comparative Examples, but the present invention is not limited thereto.

All percentages in the examples are given by weight.

Example 1 Sulfonation is carried out by dissolving 3 g of a pigment represented by the following formula in 50 g of primary sulfuric acid and stirring for 4 hours. This was stirred and added dropwise to 500 ml of water, and the resulting precipitate was collected by filtration, added with 500 ml of water and neutralized with sodium carbonate, and after removing insolubles, salted out with sodium chloride and filtered. At that time, vacuum drying is performed by removing a small amount of water to remove inorganic salts.

[0042]

Embedded image

It can be seen that the produced substance was dissolved in water and sulfonated.

It can be seen from the elemental analysis that the number of sulfonations per molecule is about 2.5 on average.

Elemental Analysis Calculated value and average value assuming that the average number of sulfone groups is 2.5 / molecule Calculated value (C ₄₇ H ₃₂ N ₆ O _10.5 SNaCl ₂ ) Actual value (calculated value) C: 57.96 ( 57.91), H3.34 (3.3
1), N: 8.61 (8.62), S: 3.48 (3.
28) The infrared absorption spectrum (KBr tablet method) is shown in FIG.

The dye thus prepared 3% Diethylene glycol 22.5% Glycerin 7.5% Deltop (manufactured by Takeda Pharmaceutical Co., Ltd.) 0.2% Ion-exchanged water 66.8% The above mixture was heated to 70 ° C. After stirring and dissolving, the pH was adjusted to 10 with sodium hydroxide, and the mixture was filtered twice through a 0.2 μm filter to prepare an ink. Next, the ink was tested for the following items using a commercially available coated paper for inkjet and a treated paper prepared as described below as a recording member, and the following results were obtained. The above treated paper is coated on a high quality paper with a coating solution having the following composition: calcium carbonate powder 17% Al (OH) ₃ powder 8% methyl methacrylate-butadiene copolymer latex 12% water 63% at 15 g / m ² , Further, a 3% aqueous solution of AlCl ₃ was applied thereon at 35 g / -m ² by an air knife application method, and then heated and pressurized by calendering.

1) Image Visibility and Dryness of Image The ink was jet-recorded on a commercially available ink-jet coated paper and the above treated paper under the condition of a particleization frequency of 100 KHz from a nozzle having an inner diameter of 30 μm, and a clear image was obtained. . The drying time of the recorded matter was within 10 seconds at normal temperature and normal humidity.

2) Preservation The ink was sealed in a glass container and kept at -20 ° C for 4 months.
The solution was stored for one month at 20 ° C., for one year at 20 ° C., and for one week at 90 ° C., but no precipitation was observed. No change was observed in the physical properties or color tone of the ink.

3) Injection stability The jet recording of the above 1) was performed continuously for 1000 hours. However, the nozzle was not clogged or the ejection direction did not change, and stable recording was performed.

4) Jet responsiveness After jet recording according to 1), the jet recording was left at room temperature and humidity for one month and at 40 ° C. and 30% RH for one week, respectively, and then jet recording was performed again. As in 3), stable recording was performed.

5) Light fastness of image When light was irradiated with a carbon arc lamp for 4 hours, the fading rate was 5
% Or less.

6) Image Water Resistance Test An image was immersed in water at 30 ° C. for 1 minute, and the change in image density before and after immersion was evaluated as a density fading rate. Commercially coated paper had poor water resistance as compared to treated paper.

Further, when the color tone and the dyeing density of the recorded image were evaluated, satisfactory results were obtained with both commercially available coated paper and treated paper.

Embodiment 2

[0055]

Embedded image

An ink was prepared and evaluated in the same manner as in Example 1 except that the pigment to be sulfonated had the above structure. Table 1 shows the results.

Embodiment 3

[0058]

Embedded image

An ink was prepared and evaluated in the same manner as in Example 1 except that the pigment to be sulfonated had the above structure. Table 1 shows the results.

Comparative Example 1 The dye of Example 1 was replaced with C.I. I. Acid Red 92 /
C. I. Evaluation was made in the same manner as in Example 1 except that Acid Yellow 23 was set at 1/1 = 1 weight ratio.

[0061]

[Table 1]

[0062]

[0063]

[0064]

[0065]

[0066]

[0067]

[0068]

[0069]

[0070]

[0071]

[0072]

[0073]

[0074]

[0075]

[0076]

[0077]

[0078]

[0079]

[0080]

[0081]

[0082]

By using the dye of the present invention [general formula (1)], it is possible to obtain a red-brown ink jet dye having excellent overall characteristics required for an ink jet recording ink .

[Brief description of the drawings]

FIG. 1 is an IR spectrum of the azo dye of the present invention obtained in Example 1.

Continuation of the front page (56) References JP-A-4-136864 (JP, A) JP-A-4-272962 (JP, A) JP-A-57-92052 (JP, A) JP-A-56-152867 (JP) JP-A-56-152868 (JP, A) JP-A-56-167759 (JP, A) JP-A-57-195768 (JP, A) JP-A-57-195767 (JP, A) 58-1222967 (JP, A) JP-A-63-56574 (JP, A) JP-A-1-221458 (JP, A) JP-A-63-117082 (JP, A) JP-A-59-22967 (JP, A) A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C09B 35/039 C09B 35/233 C09D 11/00 C09D 11/02

Claims (3)

(57) [Claims] 1. An azo dye represented by the following general formula (1). Embedded image (In the formula, R ¹ and R ² each represent an alkyl group, an alkoxy group, a halogen atom or a hydrogen atom, which may be the same or different. N is 1 to 4, M ⁺ is an alkali metal or an amine. Cation or ammonium ion) 2. The method according to claim 1, wherein the pigment represented by the following formula is stirred and dissolved in sulfuric acid. Embedded image (In the formula, R ¹ and R ² each represent an alkyl group, an alkoxy group, a halogen atom or a hydrogen atom, which may be the same or different.) 3. An ink jet recording ink comprising at least one of the azo dyes according to claim 1.