JPS6286071A - water-based ink composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention The present invention relates to a water-based ink composition suitable for printing, writing instruments, recorders, and stamps, and particularly a black water-based ink having excellent performance for inkjet printing. Regarding the composition.

In conventional inkjet 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) The viscosity, surface tension, specific conductivity, and density of the ink should be within appropriate ranges as physical properties of the ink according to the droplet generation method and the droplet flying direction control method.

2) During long-term storage, long-term use, or recording suspension, precipitation should not occur due to chemical changes, or the physical properties of the ink (a) should not change.

3) The recorded image should have sufficiently high contrast and be clear.

4) The printed image dries 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 inks used in full-color printers must 5) exhibit excellent color tone, and 6) the recorded images must be clear, without smudges, and have excellent water resistance, light resistance, and abrasion resistance. It is required that it must be an image.

To date, many proposals have been made for inkjet recording inks to meet the above requirements.
At present, no material has yet been obtained that satisfactorily satisfies all of the above conditions.

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.

Normally, aqueous ink compositions basically consist of a dye, a polyhydric alcohol or its ether known as a wetting agent, and water, and optionally contain additives such as an anti-abrasive agent. It is something.

In conventional black water-based ink, dyes include c, r, direct black -4, -11, -19, -32, -3.
8, -51, -75, -112, -154 etc. and C1■,
Acid Black-1, -2, -7, -24, -28,
There are direct dyes such as -94 and acid dyes R1.

However, among these dyes, direct dyes have poor solubility, so it is not possible to sufficiently increase image density and contrast by increasing their concentration.

Furthermore, although acidic dyes have good solubility, the water resistance of images is particularly poor, so special treated paper must be used.

Purpose The present invention provides an aqueous ink composition that solves the above-mentioned conventional drawbacks, and more specifically, has poor jetting characteristics and is free from clogging, and particularly has improved image clarity, water resistance, and light resistance. The present invention provides a black water-based ink with excellent properties.

Structure The present inventors have discovered that the use of a specific dye as a means to solve the above-mentioned drawbacks brings about sufficient effects, leading to the present invention. That is, the ink composition of the present invention is characterized by containing at least one water-soluble dye represented by the following general formula.

8r2 R1; hydrogen, alkyl group, alkoxy group, halogen, sulfonic acid group R2; hydrogen, alkyl group, alkoxy group, halogen Ar1, her2; alkyl group, hydroxyl group, amine group, substituted amino group, sulfonic acid group, etc. Phenyl group and naphthyl group M having a substituent; represents a cation such as hydrogen, sodium, potassium, lithium, or an organic amine.

The content of the dye represented by the above general formula is 10
0.5 to 20 parts by weight, preferably 1.0 parts by weight.
5 to 6 parts by weight is suitable. If it is less than 0.5 parts by weight, its effectiveness as a coloring agent will be weakened and the color tone of the obtained image will be insufficient, and if it exceeds 20 parts by weight, precipitation will occur in the ink if left for a long time. Inkjet recording tends to be insufficient.

Specific examples of the dye are listed below.

0ro u Convex U These dyes 1 can be more easily synthesized.

For example, 4.8 g of the dye shown in Example (1) is dissolved in 100 ml of water and 0.9 g of caustic soda, and 1.5 g of sodium nitrite is added to diazotize it by backwashing (total amount of 20
0m1>. Next is To! Dissolve 742 g of acid in 200 ml of water and 6 g of soda carbonate, and add the diazotized solution of J acid while stirring at 10° C. or lower to perform a coupling reaction. After reacting for 1 hour, add 4g of soda carbonate and add 4.
100 ml of a tetrazotized solution of 2.3Q of 4-diaminobenzanilide is added and reacted for 2 hours. After completion of the reaction, the reaction solution is salted out with common salt to obtain the dye (1) in the form of a black powder. The yield was 12.8Q (yield 84%).

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, triethylene glycol, polyethylene glycol, polypropylene glycol, polyhydric alcohols such as glycerin, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl, diethylene glycol monobutyl ether, triethylene glycol Alkyl ethers of polyhydric alcohols such as ethylene glycol monomethyl ether and triethylene glycol monomethyl ether, others, N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-1-methylimidazolidinone , dimethylformamide, triethanolamine, etc.

Among these, particularly preferred are diethylene glycol,
These are polyethylene glycol 200-600, triethylene glycol, ethylene glycol, glycerin, and N-methyl-2-pyrrolidone, and by using these, it is possible to obtain high dye solubility and the effect of preventing clogging by preventing water evaporation. .

The content (1) of the water-soluble organic solvent in the ink can be used in the range of 5 to 80% based on the weight of the ink, but it is preferably used in 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 fungicidal agent, sodium dehydroacetate, sodium sorbate, sodium 2-pyridinethiol-1-oxide, sodium chloride, sodium pentachlorophenol, and the like 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 being prepared.

Examples include amines such as jetanolamine and triethanolamine, hydroxides (hydroxides of alkali metal elements such as hylithium, sodium hydroxide, potassium hydroxide, ammonium hydroxide, lithium carbonate, sodium carbonate, potassium carbonate, etc.) Examples include carbonates of alkali metals.

Examples of piezoelectric conductivity modifiers include potassium chloride,
Examples include inorganic salts such as 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 laumyldiacetate.

As a rust preventive agent, for example, acidic sulfite, thiosulfate
-ammonium thioglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, dicyclohexylammonium nitrite, etc.

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.

Examples and comparative examples of the present invention are shown below.

All percentages are by weight.

Example 1 An ink was prepared by heating the following composition to about 50° C., stirring and dissolving it, and then filtering it through a Teflon filter with a pore size of 0.22 μm. The physical properties of the ink are shown in Table-1.

Dye of specific example (1) 3.0% diethylene glycol 15.0% glycerin
5.0% Sodium dehydroacetate
0.2% water
Inks of Examples 2 to 5 and Comparative Examples 1 to 3 were prepared in the same manner as in Example 1 except that materials having the following compositions were used.

Example 2 Dye of Specific Example C3] 3.0% diethylene glycol 15.0% glycol
5.0% Sodium dehydroacetate
0.2% water
76.8% Example 3 Dye of Specific Example Qll 3.0% Diethylene Glycol 15.0% Glycerin
5.0% Sodium dehydroacetate
0.2% water
7G, 8% Example 4 Specific example dye 3.0% triethylene glycine,! -L 10.0% 2.2'-Thiogetanol 10.0% Sodium Benzoate
0.2% water
76.8% Execution 11A5 Dye of Example 0 3.0% Polyethylene Glycol 200 5.0% Triethylene Glycol Monomethyl Ether 15.0% Sodium Benzoate 0.2% Water
76.8% Comparative Example 1 Dye (C, 1, Direct Black 32) 3.0% Diethylene glycol 15.0% Glycerin 5.0% Sodium dehydroacetate 0.2% Water
76.8% Comparative Example 2 Dye (C, 1, Direct Black 51) 3.0% Diethylene glycol 15.0% Glycerin 5.0% Sodium dehydroacetate 0.2% Water
76.8% Comparative Example 3 Dye (C, 1, Acid Black 28) 3.0% Diethylene glycol 15.0% Glycerin 5.0% Sodium dehydroacetate 0.2% Water
76.8% Table-1 Physical properties of ink *1 The ink was diluted with pure water to a dye a content of 1 wt%, applied to high-quality paper with a doctor blade, and air-dried for one day to prepare a sample. This sample was immersed in water at 30° C. for 1 minute, and the concentration was measured using a Macbeth's temperature meter and compared with the concentration before immersion.

Fading rate - [(S degree before immersion - concentration after immersion) / concentration before immersion] x 100 112 ml A sample prepared in the same manner as above was heated for 3 hours using a fade meter (carbon arc lamp, 6
3°C) and the rate of fading was determined in the same manner as in 1.

Effects (I) Evaluation tests were conducted on the ink composition of Example 1 on four items. The results are shown below.

1) Image clarity and image drying properties: When ink was jet-recorded on commercially available high-quality paper using a particle frequency of 1100 kHz from a nozzle with an inner diameter of 30 μm, a clear black image without bleeding was obtained. The drying time of the recorded matter was within 10 seconds at room temperature and humidity.

2) Storage: Seal the ink in a glass container and store at -20°C for 1 month, 4
Although it was stored for 1 month at 20°C, 1 year at 20°C, and 1 week at 90°C, no precipitation was observed. Further, no changes were observed in the physical properties or color tone of the ink.

3) Jetting stability: The jet recording described in 1) above was performed continuously for 1000 hours, and stable recording was achieved without clogging of the nozzle or change in the jetting direction.

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

(If) The inks of Examples 2 to 5 were tested for jetting response in the same manner as in Example 1, and similar to Example 1, good results were obtained. On the other hand, in the case of Comparative Examples 1 to 3, when left at room temperature and humidity for one week and at 40°C and 30% RH for three days, partial clogging of the nozzles occurred in each case, and the ink jet direction was significantly distorted. It became stable and no jet record was possible.

Patent Applicant Ricoh Co., Ltd. - Agent Patent Attorney Hidetake Komatsu Agent Patent Attorney Hiroshi Asahi Procedure Kokeguchi Seisho (Voluntary) December 9, 1985 Director General of the Patent Office Michibe Uga 1, Case Indication Special Application No. 60-224902 2, Name of the invention Aqueous ink composition 3, Relationship to the case of the person making the amendment Name of patent applicant (674) Ricoh Co., Ltd. 4, Agent ----i 5, Amendment order Date (voluntary) 6. In the specification to be amended, 1. Detailed explanation of the invention 7. Contents of the amendment (1) The structural formula of compound (9) on page 9 of the specification is corrected as follows.

(2) The structural formula of compound (13) on page 11 is corrected as follows.

Claims (1)

[Scope of Claims] A water-based ink composition characterized by containing at least one water-soluble dye represented by the following general formula. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ R_1; Hydrogen, alkyl group, alkoxy group, halogen,
Sulfonic acid group R_2; hydrogen, alkyl group, alkoxy group, halogen Ar_1, Ar_2; alkyl group, hydroxyl group, amino group,
A phenyl group and a naphthyl group M having a substituent such as a substituted amino group or a sulfonic acid group; represents a cation such as hydrogen, sodium, potassium, lithium, or an organic amine.