JPS61185576A - Ink composition - Google Patents

Abstract

PURPOSE:An aqueous ink composition for ink jet recording capable of forming improved blue image without causing ink clogging, etc. for a long time, comprising specific dye, a wetting agent, and water as main components. CONSTITUTION:(A) 0.5-20pts.wt. (based on 100pts.wt. composition) of dye shown by the formula (CuPc is copper phthalocyanine; R1 and R2 are H, or hydroxyethyl; R3 and R4 are H, alkylamine, alkoxyalkylamine, or alkanolamine which has 8-16C; a and b are in 2<=a+b<=4, and 1-3 integer) is blended with (B) a wetting agent (e.g., ethylene glycol, etc.), and (C) water, to give the aimed composition.

Description

Detailed Description of the Invention (1) Industrial Application Field The present invention relates to an aqueous ink composition suitable for printing, writing instruments, recorders, stamps, etc., and particularly for long-term intermittent use in inkjet recording. The present invention also relates to an aqueous ink composition for inkjet recording that can form excellent blue images without causing nozzle clogging or the like.

(2) Prior Art Usually, aqueous ink compositions are basically composed of a dye, a polyhydric alcohol or its ethers called a wetting agent, and water, and in particular, it is possible to use this ink composition. In order to perform accurate inkjet recording, various conditions are required for the ink used.

The physical properties of ink depending on the droplet generation method and droplet flight direction control method include ink viscosity, surface tension, specific conductivity,
It is necessary that the density is within an appropriate range. and,
Precipitates must not be generated due to chemical changes during long-term storage, long-term use, or recording suspension, and the physical properties of the ink must not change. The ejection nozzle of a recording device generally has a diameter of about 10 to 60 μm, and if the nozzle is clogged with deposits, droplets cannot be ejected. Even if the nozzle is not completely clogged, if solid matter or sticky matter adheres to the vicinity of the nozzle, or if the physical properties of the ink that were adjusted to desired values during ink formulation change, recording performance, ejection stability, and ejection response may deteriorate. descend.

The recorded image has sufficiently high contrast,
Of course, it is also required to be clear and have water resistance, light resistance, and abrasion resistance.

Conventionally, direct dyes and acid dyes that are water-soluble and have excellent water resistance and light emitting properties have been used as blue dyes for water-based inks. For example, blue dyes include C,1,
Direct Blue 1.8.71, 76.78.108.
163.195.202.236, C, I, Acid Blue 1, 7.126.175.234, etc.

However, since conventional direct dyes have poor solubility, it is not possible to sufficiently increase image density and contrast, and the dyes tend to coagulate and precipitate during storage or use, causing nozzle clogging. Also, the water resistance of the image is insufficient. In order to improve this drawback, various organic amines and surfactants are added, but these additives can cause corrosion of the various components that make up the recording device, and if the ink liquid bubbles and the nozzles become clogged, the image quality may deteriorate. may become unclear. Furthermore, when conventional acid dyes are used, the color tone is clear, but the water resistance is particularly poor, and special paper must be used as in the case of direct dyes.

For this reason, water-based inks, especially inkjet recording inks, have excellent solubility, exhibit good storage stability and nozzle clogging, and form images with excellent water resistance and light resistance. There is a strong need for dyes that can

(3) Problems to be Solved by the Invention While conducting research to improve the drawbacks of conventional water-based inks, particularly inkjet recording inks, as described above, the inventors have particularly investigated in depth the causes of nozzle clogging. death,
While ink is ejected intermittently for a long period of time, slight changes in the ink composition adhering to the vicinity of the nozzle tip, especially the water content ratio, may occur, which may cause agglomeration and precipitation of water-soluble dyes and poorly soluble substances in the vehicle. I learned that this was causing the nozzle to clog. The present invention has been made based on this knowledge.

That is, an object of the present invention is to provide a composition that satisfies all of the required characteristics of aqueous inks, particularly inkjet recording inks. It is an object of the present invention to provide an improved dye for an aqueous ink composition that does not cause clogging, particularly during storage or use of the ink. Another object of the present invention is to provide a dye that can be easily obtained in high purity and is suitable for use in water-based inks.

Still another object is to provide a dye that has excellent water resistance after printing.

(4) Means to solve problems As a means for achieving the object of the present invention.

The dye has a special structure that has a higher affinity for wetting agents than water, and its composition is as follows.

6 General formula (I) (wherein CuPc is Copper phthalocyanine is shown. R2 and R2 represent hydrogen or a hydroxyethyl group, and R3 and the corner represent hydrogen, an alkylamine, an alkoxyalkylamine or an alkanolamine.

However, the total number of carbon atoms in R3 and R4 is in the range of 6 to 18, and R3 and R4 are not hydrogen at the same time, and a and b are integers from 1 to 3 that satisfy the relationship 2≦a+b≦4, respectively. Shown independently. ) General formula CI used in the present invention
), specific examples of amines represented by N R+ Rz include NH2, ethanolamine,
Examples include jetanolamine. Specific examples of the C6 to IS alkylamine, alkoxyalkylamine and alkanolamine represented by N R3R4 include hexylamine, 2-ethylbutylamine, diisopropylamine, heptylamine, octylamine, N,N-di Butylamine, N-ethyl-N-
Hexylamine, 2-ethylhexylamine, nonylamine, cyamylamine, dodecylamine, dioctylamine, cetylamine, stearylamine, methoxyhexylamine, propoxybutylamine, butoxyhexylamine, hexyloxyethylamine, 2-ethylhexyloxypropylamine, heptatoolamine , octatoolamine, dodecylethanolamine, and the like.

If the alkylamine, alkoxyalkylamine, or alkanolamine represented by N R3R1 in the above general formula CI) is C6 or less, the dye itself cannot be purified easily, the dye has strong water solubility, and has poor affinity for wetting agents. for,
During long-term use, the nozzle gets clogged, and the water resistance of the image suffers. Moreover, if the dye exceeds cog, the affinity of the dye for both water and wetting agent is poor, a large amount of solvent is required, and even then, the image density does not increase, and it is unsuitable in all conditions such as storage stability and nozzle clogging.

The dye of general formula (I) used in the present invention can be obtained by, for example, converting copper phthalocyanine into a necessary amount of chlorosulfonate using a conventional method.
It can be easily obtained by reacting ammonia or an organic amine by a conventional method.

Since these dyes have essentially poor water solubility, they can be easily separated from impurities such as inorganic salts produced as by-products during synthesis, making it easy to obtain high-purity products. In addition, the water resistance when used as an ink is extremely excellent.

Examples of the dye represented by the general formula CI) include those shown in Table 1.

As the wetting agent used in the present invention, those conventionally used for water-based inks can be used, but thermally stable ones are particularly preferably used.

For example, polyhydric alcohols, cellosolves, carpitols, etc., specifically, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, glycerin.

polyethylene glycol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether,
Examples include diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, 1-lyethylene glycol monomethyl ether, triethylene glycol monoethyl ether, and the like. In addition to these, dimethylformamide, pyrrolidone, alcohol, alkanolamine, etc., which are commonly used as dye dissolving agents, can also be used.

The basic composition of the aqueous ink composition of the present invention is a dye, a wetting agent, and water. The amount of the dye represented by general formula (1) to be added is usually 0.5 to 100 parts by weight of the ink composition.
The content is 20 parts by weight, preferably 1 to 15 parts by weight.

If it is less than 0.5 part by weight, the color will be pale.

If the amount exceeds 20 parts by weight, precipitation may occur over a long period of time.

Furthermore, the dye represented by general formula CI) is usually blue in color and can be used alone or in combination, and conventionally used dyes for water-based inks can also be used in combination as long as the characteristics of these dyes are not impaired. . The wetting agent is added to the recording medium liquid (vehicle) in a necessary amount as desired so as to satisfy the desired characteristics, and the amount added is usually 1 to 80 parts by weight per 100 parts by weight of the ink composition. It is preferable to include parts by weight. These wetting agents can be used alone as well.

Two or more types may be used in combination provided that they do not adversely affect each other.

In the present invention, various conventionally used additives are used to provide more remarkable properties.

For example, antiseptic and antifungal agents such as sodium dehydroacetate, 2,2-dimethyl-6-acetoxydioxane, ammonium thioglycolate, etc.; antirust agents such as acid sulfite,
These include sodium thiosulfate, dicyclohexyl ammonium nitrite, and other ultraviolet absorbers, viscosity modifiers, surface tension modifiers, pH modifiers, resistivity modifiers, infrared absorbers, and the like.

(5) Actions and Effects The dye represented by general formula (I) used in the aqueous ink composition of the present invention differs from the physical properties of dyes used in conventional aqueous ink compositions, and one characteristic is that it is poorly water-soluble. At the same time, another feature is that it has improved affinity for polyhydric alcohols, cellosolve, and calpitol.

By selecting such a configuration, it is possible to sufficiently deal with a wide range of compositions, and it has become possible to always maintain an extremely stable solution state even with slight changes in the ink composition during storage or use. This, combined with the fact that it is easier to separate inorganic by-products during dye synthesis than with conventional dyes, making it possible to obtain high-purity dyes, makes it possible to produce a single image with high density, high water resistance, and It is now possible to make it clearer.

(6) Examples The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples.

Examples 1 to 12, Comparative Examples 1 to 3 The components of each formulation shown in Table 2 were thoroughly mixed, thoroughly stirred at 50 DEG C., and filtered under pressure using a 0.5 .mu. membrane filter to prepare a recording liquid.

The storage stability, jetting stability, image sharpness, and water resistance of each recording liquid were tested in the following manner, and the results are shown in Table 2.

1) Storage stability The ink was sealed in a Pyrex test tube and left to stand at 0°C and 50°C for one month, respectively, and then the presence or absence of precipitates was examined. The amount of precipitation was expressed as follows.

O No precipitates at all On Almost none Δ 〃 Small amount x 〃 Large amount 2) Ejection stability Put the ink into the ink tank of an inkjet device with a nozzle with a hole diameter of 30μ, and run a cycle of ejecting for 1 second at 1 second intervals. After running for 24 hours, it stopped for 10 days, 20 days,
After being left at room temperature for 30 days, 60 days and 90 days,
The spray was re-injected and the nozzle was checked to see if it was clogged. The maximum number of days it can be left unused for re-injection without clogging is displayed.

3) Image clarity Images were jet-recorded on high-quality paper using the inkjet device described in 2), and the clarity was visually determined.

O Excellent. 0 Fair, Δ Insufficient, × Inferior.

4) Water Resistance Jet recording was performed on high-quality paper using the inkjet device described in 2), and the degree of bleeding when immersed in water for 1 minute was judged with the naked eye.

O Excellent. O: Fair, Δ: Insufficient, ×: Poor.

As is clear from the results in Table 2, the aqueous ink composition of the present invention has better blue image quality than inks using conventional dyes, can be stored for a long period of time, and has improved nozzle clogging. I know that there is.

Claims (1)

[Scope of Claims] An ink composition containing a dye, a wetting agent, and water as main components, characterized by containing a dye represented by the following general formula (I). General formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, CuPc represents copper phthalocyanine. R_1 and R_2 represent hydrogen or hydroxyethyl group, and R_
3 and R_4 represent hydrogen, alkylamine, alkoxyalkylamine or alkanolamine. However, the total number of carbon atoms in R_3 and R_4 is in the range of 6 to 18, and R_3 and R_4 are never hydrogen at the same time. a and b each independently represent an integer of 1 to 3 that satisfies the relationship 2≦a+b≦4. )