JPH0564189B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD This invention relates to improved aqueous inkjet recording inks. Prior Art In inkjet recording, in order to perform good recording over a long period of time, the ink used must satisfy the following conditions. 1. Ink viscosity, surface tension, specific conductivity, and density must be within appropriate ranges as ink physical properties depending on droplet generation method and droplet flight direction control method; 2. Long-term storage, long-term use, or recording suspension. 3. The recorded image must have sufficiently high contrast and clarity; 4. The printed image should dry quickly. In order to meet the above requirements, it is required that the molecular extinction coefficient of the dye used in the ink is sufficiently high, and that the solubility of the dye in water and a wetting agent is sufficiently high. Furthermore, the ink used in full-color printers, etc. must: 5. exhibit color tone with excellent purity; 6. the recorded image must, of course, be water resistant;
It must be a clear image with good light and abrasion resistance and no bleeding. To date, many proposals have been made for inkjet recording inks to meet the above requirements, but at present no ink has yet been created that fully satisfies all of the above conditions. be. The properties required above are particularly influenced by the dyes among the materials used in the ink, and the development of new dyes has been awaited in order to satisfy these requirements. Purpose The purpose of the present invention is to provide an ink that satisfies the various conditions required for the above-mentioned conventional inkjet recording ink, and it consists in developing a dye particularly suitable for the ink. Structure In order to achieve the above object, the present invention provides a water-based ink containing a water-soluble dye, a wetting agent, and other additives, which has the following general formula as the water-soluble dye: [General formula] Here, _R1 :

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[Formula] (R ₅ is an alkyl group, a hydroxyalkyl group) R ₂ : hydroxyl group, unsubstituted or substituted amino group, R ₃ : hydroxyl group, unsubstituted or substituted amino group, R ₄ : hydrogen, alkyl group, alkoxy group, Halogen, sulfonic acid group, m: 0 or 1 n: 1, 2 or 3 M: hydrogen, lithium, sodium, potassium,
Indicates cations such as organic amines. It is characterized by using at least one kind of water-soluble dyes represented by the following. Representative examples of water-soluble dyes used in the present invention are listed below. These dyes can be synthesized by commonly known methods. For example, the dye shown in specific example (1) combines 4-nitrobenzoyl chloride and 2-pyrrolidone with N-
React in methyl-2-pyrrolidone at 130°C for 3 hours. When cooled and water is added, the reactant precipitates out, which is recrystallized from ethanol. m.
4-Nitrobenzoylpyrrolidone-(2) at p.131℃
is obtained. This nitro compound is catalytically reduced using a 5% Pd--C catalyst to give an amino compound, which is then diazotized by a conventional method. A red dye (1) can be obtained by coupling this diazotized liquid with gamma acid in an acidic manner. The ink of the present invention uses water as a solvent component, and water is used for purposes such as adjusting the physical properties of the ink to desired values, preventing drying of the ink, and improving the solubility of dyes. It is also possible to use a mixture of the following water-soluble organic solvents and water. ethylene glycol, diethylene glycol,
Polyhydric alcohols such as triethylene glycol, polyethylene glycol, polypropylene glycol, glycerin, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether,
Alikyl ethers of polyhydric alcohols such as diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, etc., N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3
-dimethylimidazolidinone, dimethylformamide, triethanolamine, etc. Among these, particularly preferred are diethylene glycol, polyethylene glycol 200-600, triethylene glycol, ethylene glycol, glycerin, and N-methyl-2-pyrrolidone.
By using these, the dye has high solubility,
It is possible to obtain the effect of preventing clogging by preventing moisture evaporation. The content of the above-mentioned water-soluble organic solvent in the ink can range from 5 to 80% based on the total weight of the ink, but it is preferably used within the range of 10 to 40% in view of viscosity, drying properties, etc. In addition to the dyes and solvents described above, conventionally known dyes and additives can be added to the ink of the present invention. As the preservative and fungicide, sodium dehydroacetate, sodium sorbate, sodium 2-pyridinethiol-1-oxide, sodium benzoate, sodium pentachlorophenol, etc. can be used in the present invention. 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 include amines such as diethanolamine and triethanolamine, hydroxides of alkali metal elements such as lithium hydroxide, sodium hydroxide, and potassium hydroxide, and alkali metal hydroxides such as ammonium hydroxide, lithium carbonate, sodium carbonate, and potassium carbonate. carbonates, etc. Specific electrical conductivity regulators include, for example, inorganic salts such as potassium chloride, ammonium chloride, sodium sulfate, and sodium carbonate, and water-soluble amines such as triethanolamine. Examples of the chelating reagent include sodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, and sodium uramildiacetate. Examples of rust preventives include acidic sulfites, sodium thiosulfate, ammonium thioglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, and dicyclohexylammonium nitrite. In addition, depending on the purpose, water-soluble ultraviolet absorbers, water-soluble infrared absorbers, water-soluble polymer compounds, dye solubilizers, surfactants, etc. can be added. Example 1 Dye Example (1) The following test was conducted using an ink consisting of 3wt% glycerin 5wt% diethylene glycol 15wt% sodium dehydroacetate 0.2wt% ion-exchanged water 76.8wt%, and the following satisfactory results were obtained. was gotten. 1. Image clarity and image drying properties: When ink was jet-recorded on commercially available high-quality paper using a nozzle with an inner diameter of 30 μm at a particle generation frequency of 100 KHz, a clear red image without bleeding was obtained. The drying time of the recorded material was within 10 seconds at room temperature and humidity. 2. Storage: The ink was sealed in a glass container and stored at -20°C for 1 month, at 4°C for 1 month, at 20°C for 1 year, and at 90°C for 1 week, but no precipitation was observed. Ta. Further, no change was observed in the physical properties or color tone of the ink. 3. Jetting stability: The jet recording described in 1 above was carried out continuously for 1000 hours, and stable recording was possible without any clogging of the nozzle or change in the jetting direction. 4 Injection response: After recording the jet according to 1 above, it was left at room temperature and humidity for 1 month and at 40°C and 30% RH for 1 week, and then the jet recording in 1 was performed again. However, as in 3 above, stable recording was possible. The following table shows the results of a similar test using ink of Example 1 except for the dye example.

[Table] Effects According to the present invention, as is clear from the test results in the above Examples and Comparative Examples, it is excellent in various conditions such as storage stability, jetting stability, and jetting response, especially when used as an inkjet ink. A water-based ink is obtained.

Claims (1)

[Scope of Claims] 1. An aqueous ink characterized by containing a dye of the following general formula, a wetting agent, and other additives. [General formula] Here, R ₁ : [Formula] [Formula] [Formula] [Formula] [Formula] [Formula] (R ₅ is an alkyl group, a hydroxyalkyl group) R ₂ : A hydroxyl group, an unsubstituted or substituted amino group, R ₃ : hydroxyl group, unsubstituted or substituted amino group, R ₄ : hydrogen, alkyl group, alkoxy group, halogen, sulfonic acid group, m: 0 or 1 n: 1, 2 or 3 M: hydrogen, lithium, sodium, potassium,
Indicates cations such as organic amines.