JPS612774A - Ink composition - Google Patents

Abstract

PURPOSE:The titled composition for ink jet recording that contains a dye with a specific structure, a humectant and water, thus being good in storage stability and giving excellent images of magenta color without nozzle clogging even in intermittent use for a long period of time. CONSTITUTION:The objective composition is obtained by using preferably 1- 15pts.wt. of a dye of formula I (M1-M3 are H, alkali metal; m is 1-3; one of X1 and X2 is residue of alkylamine or alkoxyalkylamine of 6-18 carbon atoms and the other is residue of alkylamine or alkoxyalkylamine of 1-18 carbon atoms), (B) 1-80pts.wt. of a humectant (preferably being thermally stable such as ethylene glycol) and (C) water.

Description

Detailed Description of the Invention (I) 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 magenta 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.

First, 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, recording performance may deteriorate if solid matter or sticky matter adheres to the vicinity of the nozzle, or if the physical properties of the ink, which were adjusted to desired values during ink formulation, change.

Discharge stability and discharge responsiveness deteriorate.

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 resistance have been used as magenta dyes for water-based inks. For example, magenta dye is C,
1, Direct Red-1, 11, 37, 62, 75,
83, 99, 220, 227 and C, 1, acid red - 87, 92, 94, 115, 131, 154, 186
, 254, 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. In order to improve this drawback, various organic amines and surfactants are added as dye dissolving agents, but these additives can cause corrosion of the various components that make up the recording device or cause the ink liquid to foam. If the nozzle is clogged, the image 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.

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, resulting in agglomeration and precipitation of water-soluble dyes and poorly soluble substances in the vehicle. I learned that this caused 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.

(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.

The present invention is an ink composition containing a dye, a wetting agent, and water as main components, and is characterized by containing a dye represented by the following general formula (I) or/and (n).

(In the formula, Ml, M2 and M3 are hydrogen, alkali metal,
Indicates ammonia or an organic amine and may be the same or different. m represents an integer of 1 to 3. X.

Is either one of the X2's 66~l? There are also alkylamine residues or alkoxyalkylamine residues.

The other is a c, , tg alkylamine residue, alkoxyalkylamine residue or alkanolamine residue. ) (In the formula, 1M4, M5 and M6 are hydrogen, alkali metal,
9Y1 and Y2 represent ammonia or an organic amine, and 0m is an integer of 1 to 3, which may be the same or different.9Y1 and Y2 are an alkylamine residue or an alkoxyalkylamine residue of 06 to 1g, and the other is an alkylamine residue or an alkoxyalkylamine residue. is a C1-18 alkylamine residue, alkoxyalkylamine residue or alkanolamine residue. ) Specific examples of C6-+8 alkylamines and alkoxyalkylamines corresponding to the residues represented by Xl, X2 or Yl, Y2 in the dyes represented by general formulas (I) and (II) used in the present invention Examples include hexylamine, 2-ethylbutylamine, diisopropylamine, heptylamine, octylamine, N,
N-dibutylamine, N-ethyl-N-hexylamine, 2-ethylhexylamine, nonylamine, cyamylamine, dodecylamine, dioctylamine, cetylamine, stearylamine, methoxyhexylamine, propoxybutylamine, butoxyhexylamine, hexyloxyethylamine, 2 -ethylhexyloxypropylamine and the like. 06 The following lower alkylamines and alkoxyalkylamines include, for example, methylamine, ethylamine, propylamine, butylamine, amylamine, dimethylamine, diethylamine, methylethylamine, methoxyethylamine,
Examples include ethoxyethylamine and propoxyethylamine.

Examples of alkanolamines include ethanolamine, jetanolamine, propatoolamine, butanolamine, heptatoolamine, and octatoolamine. Examples of the arylamine include aniline, aniline sulfonic acid, toluidine, and benzylamine.

In addition, as the organic amine of Ml and M2, the above-mentioned C
6~Iε alkylamine or alkoxyalkylamine, or other amines such as C8~
5 alkylamine or alkoxyalkylamine,
Also included are alkanolamines, anilines, benzylamines, cycloalkylamines, and the like.

X, , X, or Y of the above general formulas (I) and (II).

, If the alkylamine or alkoxyalkylamine residue represented by Y2 is C6 or less, the dye itself cannot be purified easily, and the dye has strong water solubility.

Due to poor affinity for wetting agents, nozzles become clogged during long-term use, resulting in poor water resistance for single images. If the dye is 018 or higher, the affinity of the dye for both water and wetting agent is poor, requiring a large amount of solvent, and even then, the image density does not increase.
Unsuitable under all conditions including storage stability and nozzle clogging.

The dye of general formula (I) used in the present invention includes 1 mole of a monoazo dye obtained by coupling, for example, 2-naphthylamine sulfonic acids or a salt thereof with H acid in a conventional manner;
It can be easily obtained by condensing 1 mole of cyanuric halide in a conventional manner, then reacting an amine corresponding to Xl and then an amine corresponding to X2 in a conventional manner. Further, the dye of the general formula (n) can be prepared by combining, for example, 1 mol of a monoazo dye obtained by coupling 8-aminomethyl-2-naphthylamine-4-sulfonic acid or a salt thereof with benzoylamino H acid in a conventional manner; Cyanuric halide 1
It can be easily obtained by condensing the amines corresponding to Y1 and Y2 in a conventional manner.

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.

Examples of the dyes represented by formulas (■) and (II) include those shown in Tables 1 and 2.

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, calpitols, etc., specifically, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, glycerin, polyethylene glycol, ethylene glycol monobutyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl Examples include ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene 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 dyes represented by general formulas (I) and (formerly) is usually 0.5 to 20 parts by weight, preferably 1 to 15 parts by weight, in 100 parts by weight of the ink composition. From 0.5 parts by weight If the amount is too low, the color will be pale, and if it exceeds 20 parts by weight, precipitation may occur over a long period of time.

Furthermore, the dyes represented by general formulas (I) and (II) are usually magenta in color and can be used alone or in combination, and dyes for water-based inks conventionally used may also be used as long as the characteristics of these dyes are not impaired. Can be used together. In addition, the wetting agent is added in the necessary amount as desired to satisfy the desired properties of the recording medium liquid (vehicle).
The amount added is usually 1 to 8 parts by weight per 100 parts by weight of the ink composition.
It is preferable to include 0 parts by weight. These wetting agents may be used alone or in combination of two or more types 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 dyes represented by formulas (T) and (II) used in the aqueous ink composition of the present invention differ from the physical properties of dyes used in conventional aqueous ink compositions in that they have poor water solubility. This is one feature, and another feature is that it simultaneously improves its 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 highly pure dyes, makes both images highly concentrated and clear. Now I can do it.

(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 3 were thoroughly mixed, thoroughly stirred at 50 DEG C., and then filtered under pressure using a 0.5 .mu. membrane filter to prepare a recording liquid.

The storage stability, jetting stability, and image sharpness of each recording liquid were tested in the following manner, and the results are shown in Table 3.

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 △ 〃 A small amount x 〃 A 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 sharpness Jet recording was performed on high-quality paper using the inkjet device described in 2), and the sharpness was visually judged as 80.Excellent. 0 Normal.

Δ Insufficient. X Inferior.

Examples 13 to 24, Comparative Examples 4 to 6 The components of each formulation shown in Table 4 were thoroughly mixed, thoroughly stirred at 50°C, and then filtered under pressure using a 0.5μ membrane filter to prepare a recording liquid.

The storage stability, jetting stability, and image sharpness of each recording liquid were tested in the same manner as in Example 1, and the results are shown in Table 4.

As is clear from the results in Tables 3 and 4, the aqueous ink composition of the present invention has better magenta image quality than inks using conventional dyes, can be stored for a long time, and has improved nozzle clogging. I can see that it is being done.

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) or/and (II). General formula (I) ▲Mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, M_1, M_2, and M_3 represent hydrogen, alkali metal, ammonia, or organic amine, and may be the same or different. represents an integer of 1 to 3. One of X_1 and X_2 is an alkylamine residue or alkoxyalkylamine residue of C_6_ to_1_8, and the other is an alkylamine residue or an alkoxyalkylamine residue of C_1_ to_1_8. or alkanolamine residues) General formula (II) ▲Mathematical formulas, chemical formulas, tables, etc.▼(II) (In the formula, M_4, M_5 and M_6 represent hydrogen, alkali metal, ammonia or organic amine, and are the same However, they may be different. Either Y_1 and Y_2 are C_
6_~_1_8 alkylamine residue or alkoxyalkylamine residue, the other is C_1_~_1_8 alkylamine residue, alkoxyalkylamine residue,
It is an alkanolamine residue or an arylamine residue. )