JPH0747702B2 - Aqueous ink composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a water-based ink composition suitable for printing, writing instruments, recorders, and stamps, and more particularly to a cyan water-based ink composition useful for inkjet printing.

2. Description of the Related Art In inkjet recording, in order to perform good print recording for a long time, the ink (water-based ink composition) used must satisfy the following conditions.

1) The ink spray characteristics are excellent. For that purpose, the viscosity, surface tension, specific electric conductivity, and density of the ink must fall within appropriate ranges as the physical properties of the ink according to the droplet generation method and the droplet flight direction control method.

2) It has excellent storability. Therefore, during long-term storage, continuous use, or during recording pauses, precipitation may occur due to chemical changes, which may cause nozzle clogging or change in ink physical properties.

3) The printed and recorded image has a sufficiently high contrast and is a clear image without blurring.

4) The recorded image dries quickly.

5) The printed and recorded image has other good water resistance, light resistance, etc., that is, good storability and excellent abrasion resistance.

6) Further, as an ink used in a full-color printer or the like, an image having a high-purity color tone and excellent color reproducibility should be formed.

In order to satisfy the above requirements, many proposals have been made so far as inks used for ink jet recording, etc., but none of them have sufficiently obtained all of the above conditions. Is the current situation. This is mainly due to the dye in the material constituting the ink.

That is, a normal aqueous ink composition is basically composed of a dye and a polyhydric alcohol or ether thereof called a wetting agent, and water, and further contains additives such as an antifungal agent, if necessary. It is a thing. Here, as the dye, for example, in the case of cyan ink, CI Direct Blue 1,8,
71,76,86,108,200,201,202,236 etc. and CI acid blue
Direct dyes and acid dyes such as 1,7,9,15,175,249 are used.

However, when a cyan ink containing such a dye is used for ink jet recording, the solubility of the direct dye is poor, so if nozzles are clogged during continuous recording or recording / reproduction, or if a color image is recorded. , An image with excellent color reproducibility cannot always be obtained. Many acid dyes have a good color tone, but the water resistance and light resistance of the image are poor, and there is a problem in the storability of the image.

OBJECT The object of the present invention is to provide a water-based ink composition, in particular an ink-jet recording water-based ink composition, in which all the conventional drawbacks are eliminated. More specifically, the injection characteristics are excellent,
It is an object of the present invention to provide a magenta water-based ink composition which is free from clogging and has excellent image sharpness, water resistance, light resistance and the like.

Configuration The present inventors have found that it is extremely effective to use a dye having a sufficiently high molecular extinction coefficient and a sufficiently high solubility in a wetting agent as a means for solving the above-mentioned drawbacks, and to complete the present invention. I arrived. That is, the aqueous ink composition of the present invention is characterized by containing at least one water-soluble dye represented by the following general formula.

[R: -COOM, - (CH 2) nCOOM, -O (CH 2) nCOOM-NH (CH
₂ ) nCOOM (n is 1 or 2, M is the same as the following) M: hydrogen, lithium, potassium, sodium, quaternary ammonium or organic amine l: 0,1 or 2 m: l is 0, 4 l is When 1 is 3 1 is 2 2] Specific examples of the dye represented by the above general formula of the present invention include the following compounds. Copper phthalocyanine nucleus Is abbreviated as Cu-Pc.

The content of these dyes is 0 with respect to the total weight of the ink.
5 to 20%, preferably 1.5 to 6% is suitable. If it is less than 0.5%, the effect as a colorant is lowered, and the color tone of the obtained image is insufficient.If it exceeds 20%, precipitation occurs in the ink after a long time and ink jet recording is sufficiently performed. It tends to get lost.

Any of the dyes of the above general formula of the present invention as described above can be easily produced, and the production method thereof is shown below, for example, by the dye of Specific Example 1).

Production Example While stirring 50 g of chlorosulfonic acid, 5.8 g (about 0.01 mol) of copper phthalocyanine was added, and the mixture was reacted at 135 ° C. for 4 hours. After completion of the reaction, the reaction solution is cooled to room temperature, 4.8 g of thionyl chloride is added, reacted at 75 ° C. for 3 hours, and then cooled to room temperature. When the reaction solution was poured into 400 ml of ice water by trickling, a blue precipitate was produced. It is suctioned off and washed with 150 ml of cold water. The cake obtained is 300m of cold water below 5 ° C.
Disperse with stirring in l, and add 4.2 g of para-aminobenzoic acid (approx.
0.03 mol) and then 100 ml of a 3% aqueous solution of sodium hydroxide is added and the reaction is carried out at 5 ° C for 5 hours, 15-20 ° C for 10 hours, and 50-60 ° C for 1 hour. After completion of the reaction, the reaction solution is cooled, acidified with hydrochloric acid, and the deposited precipitate is removed. This was washed 3 times with 200 ml of methanol to remove inorganic salts and dried to obtain 9.2 g of the dye of Example 1) in the form of free acid. To obtain Na salt, an aqueous solution containing an equivalent amount of caustic soda was added. Is obtained by dissolving and then evaporating the water.

λmax 667 nm (pH 10.0 of alkaline aqueous solution) IR spectrum: See FIG. 1. The ink of the present invention uses water as a solvent component, but since the physical properties of the ink are adjusted to desired values, ink drying is prevented. Therefore, the following water-soluble organic solvent can be mixed with water for the purpose of improving the solubility of the dye.

These water-soluble solvents include polyhydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol and glycerin; ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, Alkyl ethers of polyhydric alcohols such as diethylene glycol monobutyl ether, triethylene glycol monomethyl ether and triethylene glycol monoethyl ether; other N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethylimidazolidinone, dimethylformamide , Triethanolamine and the like.

Among these, particularly preferred are diethylene glycol, polyethylene glycol 200 to 600, triethylene glycol, ethylene glycol glycerin and N-methyl-2-pyrrolidone. By using these, the solubility of the dye and the prevention of water evaporation are used. The effect of preventing clogging can be further enhanced.

The content of the water-soluble organic solvent in the ink can be used in the range of 5 to 80% with respect to the total weight of the ink, but it is preferably used in the range of 15 to 60% from the viewpoint of viscosity, drying property and the like.

In the ink of the present invention, the dye, an organic solvent, a conventionally known antiseptic / antifungal agent, a pH adjusting agent, a chelating agent,
Additives such as anticorrosives can be added.

For example, as an antiseptic / antifungal agent, sodium dehydroacetate,
Sodium sorbate, 2-pyridinethiol-1-oxide sodium, sodium benzoate, pentachlorophenol sodium and the like can be used.

As the pH adjuster, any substance can be used as long as it can control the pH of the ink within the range of 9.0 to 11.0 without adversely affecting the ink to be prepared. Examples thereof include amines such as diethanolamine and triethanolamine; hydroxides of alkali metals such as lithium hydroxide, sodium hydroxide and potassium hydroxide; ammonium hydroxide; quaternary ammonium hydroxide; lithium carbonate and sodium carbonate. , Carbonates of alkali metals such as potassium carbonate, and the like.

Examples of chelating agents include sodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, and sodium uracildiacetate.

Examples of the rust preventive agent include acidic sulfite, sodium thiosulfate, ammonium thioglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, and dicyclohexylammonium nitrite.

In addition, a water-soluble ultraviolet absorber, a water-soluble infrared absorber, a water-soluble polymer compound, a dye dissolving agent, a surfactant and the like can be added depending on the purpose.

Examples and comparative examples of the present invention will be shown below. All percentages are weight percentages.

Example 1 A material having the following composition was heated to about 50 ° C., dissolved with stirring, and then passed through a Teflon filter having a pore size of 0.22 μm to prepare an aqueous ink composition.

Dye of Specific Example (1) 3.0% Diethylene glycol 15.0% N-Methyl-2-pyrrolidone 15.0% Sodium dehydroacetate 0.2% Water 66.8% Example 2 was conducted in the same manner as in Example 1 except that the material having the following composition was used. 5 and the inks of Comparative Examples 1 to 3 were prepared.

Example 2 Dye of Specific Example (4) 3.0% Polyethylene glycol 200 15.0% Triethylene glycol monomethyl ether 5.0% Sodium dehydroacetate 0.2% Water 76.8% Example 3 Dye of Specific Example (5) 3.0% Diethylene glycol 20.0% 1,3 -Dimethylimidazolidine 5.0% 6-acetoxy-2,4-dimethyl-m-dioxane 0.3% Water 71.7% Example 4 Dye of Specific Example (6) 3.0% Diethylene glycol 20.0% Glycerol 5.0% 6-acetoxy-2,4- Dimethyl-m-dioxane 0.3% Water 71.7% Example 5 Dye of Specific Example (9) 3.0% Polyethylene glycol 200 15.0% Triethylene glycol monomethyl ether 5.0% 2-Pyridinethiol-1-oxide sodium 0.3
% Water 76.7% Comparative Example 1 CI Acid Blue 9 3.0% Diethylene glycol 15.0% N-Methyl-2-pyrrolidone 15.0% Sodium dehydroacetate 0.2% Water 66.8% Comparative Example 2 CI Acid Blue 249 3.0% Polyethylene glycol 200 15.0% Triethylene glycol Monomethyl ether 5.0% Sodium dehydroacetate 0.2% Water 76.8% Comparative example 3 CI Direct Blue 86 3.0% Diethylene glycol 20.0% Glycerin 5.0% 6-Acetoxy-2,4-dimethyl-m-dioxane 0.3% Water 71.7% Next Example 1 5 and Comparative Examples 1 to 3 were performed with the following reagents.

1), Image sharpness An ink jet printer for Ricoh's word processor report 5600J was filled with the prepared ink and recording was performed.

The ink for which a clear image was obtained is indicated by a circle in Table-1.

2), Lightfastness of image The image sample obtained in 1) is applied to a fade meter (carbon arc lamp, 63 ° C) for 3 hours, and the image density before and after light irradiation is measured with a Macbeth densitometer. (Fade rate) was determined.

3), Water resistance of the image The image sample obtained in 1) is immersed in water at 30 ° C for 1 minute, the image density before and after immersion is measured with a Macbeth densitometer, and the water resistance is calculated by the same formula as the formula in (2). The sex (fading rate%) was determined.

4), storability The ink is put in a polyethylene container and stored at -20 ℃, 4 ℃, 20 ℃.
Under each condition of ℃, 50 ℃ and 70 ℃, the change of viscosity, surface tension, electric conductivity, and the presence or absence of precipitation were examined before and after storage for 3 months. Table 1 shows that the change in physical properties and the precipitation of the precipitate were achieved under any conditions.

5), Nozzle clogging test 1) After printing, at 20 ℃, 65% RH with printing paused
It was left for 2 months in the above environment, and after the standing, it was examined again whether normal printing is possible. One ink sample was tested using 3 printers.

Table 1 shows the case where all three printers were able to print normally. ○ The case where one or two of the three printers failed to print normally × The case where all three did not print normally XX Indicated by. In the 5600J printer, when the nozzle is clogged and the jetting is not possible, or when the jetting direction of the jet changes significantly compared to before leaving, it is automatically detected and the operation of the printer is stopped. The device is installed.

Effects As described above, the present invention uses a dye having a sufficiently high molecular extinction coefficient and a sufficiently high solubility in a wetting agent as a dye for water-based ink, so that it does not cause clogging, and thus has excellent storage stability and image sharpness. It is possible to provide a water-based ink composition having excellent water resistance, light resistance, and the like.

[Brief description of drawings]

FIG. 1 is an IR spectrum of an example of the dye used in the present invention.

Claims (1)

[Claims] 1. An aqueous ink composition containing at least one water-soluble dye represented by the following general formula. [R: -COOM, - (CH 2) nCOOM, -O (CH 2) nCOOM-NH (CH
₂ ) nCOOM (n is 1 or 2, M is the same as the following) M: hydrogen, lithium, potassium, sodium, quaternary ammonium or organic amine l: 0,1 or 2 m: l is 0, 4 l is 1 is 3 l is 2 is 2]