JPH06234944A - Recording ink - Google Patents

Abstract

PURPOSE:To obtain a recording ink improved in the contrast, sharpness and water resistance of image by using a specified water-soluble dye as the recording agent. CONSTITUTION:A recording agent comprising a dye derived from a water-soluble dye of any one of formulas I-III and having a molecular structure in which sulfonic acid groups exist, one sulfonate group forms a salt with triethylenetetramine, and the rest of the sulfonic acid groups form salts with an alkali metal is obtained by treating an aqueous solution of a water-soluble dye of any one of formulas I-III where Na, K or Li is bonded to the sulfonic acid groups with an H-form ion exchange resin, adding triethylenetetramine to the treated solution to convert one of the sulfonic acid groups into a salt, and adding an alkali metal hydroxide thereto to convert the rest of the sulfonic acid groups into salts with the alkali metal. 0.5-10wt.% this agent and additives are dissolved in an aqueous medium.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording liquid. More specifically, the present invention relates to a recording liquid composition used in an inkjet recording system in which a recording liquid is ejected from an ejection orifice provided in a recording head and ejected as droplets for recording.

[0002]

2. Description of the Related Art The non-impact recording method has an advantage that noise generation during recording is small, and among them, high-speed recording is possible, and so-called plain paper is recorded without requiring a special fixing process. The inkjet recording method that can perform is an extremely effective recording method, and various methods have been devised and improved so far, and some have been commercialized. There are some that have been.

In the ink jet recording method, recording is performed by causing droplets of a recording liquid, so-called ink, to fly and adhere to a recording material. Such recording liquid is
A recording agent (a dye or a pigment is used) and a liquid medium (water or various organic solvents or a mixture thereof) which dissolves or disperses the recording agent is used as a basic component, and various additives are added as necessary. ing.

There are various ink jet recording methods, depending on the method of generating droplets of the recording liquid and the method of controlling the flight direction of the droplets. For example, a recording device that applies a recording signal to a recording head unit having a piezo-vibrator and generates liquid droplets of a recording liquid in accordance with the signal, and a liquid droplet is continuously generated while being charged. There are known a device that uses a part of the droplet for recording, a device that applies a signal to the recording liquid in the chamber of the recording head in the form of thermal energy, and the like.

There are various types of apparatus for recording by generating droplets as described above. Therefore, in order to perform good recording, a method of generating droplets or a method of controlling the flight direction of droplets is used. Accordingly, it is necessary for the recording liquid to have appropriate physical properties (for example, viscosity, surface tension, specific resistance, etc.). Furthermore, the recording liquid should not have solid content due to vaporization of the liquid medium components or chemical changes of the constituent components of the recording liquid during long-term storage or rest of the recording. Generally, a discharge orifice of a recording apparatus of this type has a fine hole (generally, a diameter of several 10 mm).
Therefore, the solid content may cause clogging, and the droplet may not be ejected at all.

Even if the ejection is not stopped, the generation of the solid content adversely affects the generation of uniform droplets or the stable flight of the droplets, resulting in the recording property, the ejection stability, and the ejection response. Alternatively, continuous recordability may decrease. Alternatively, when the constituent components of the recording liquid undergo a chemical change, the physical properties of the recording liquid adjusted to desired values during preparation may change, and the recording property, ejection stability, and ejection response may also deteriorate. Therefore, there is a demand for a liquid medium component that is difficult to vaporize, a chemically stable recording agent, or a combination of a liquid medium and a recording agent that does not cause the above-mentioned drawbacks.

By the way, it is said that the ink jet recording method can perform recording on so-called plain paper without requiring a special fixing process, and so-called plain paper currently commonly used in offices or homes is, for example, electronic paper. It is a very versatile material such as copy paper, bond paper, fan hold paper, etc. These papers have different sizing degrees, and when recorded on these papers by the ink jet recording method, the drying property after printing and the print quality are often inferior. There is a demand for a recording liquid having good properties and good print quality.

Furthermore, it is required that the recorded image has sufficiently high contrast and is clear. Generally, in the conventional recording liquid, when the content of the recording agent is increased to increase the contrast of the recorded image, the ejection orifice tends to be clogged. Therefore, there is a demand for a recording agent having a high solubility in a liquid medium and a vivid color tone. Alternatively, the image once recorded must have water resistance, light resistance, weather resistance, and abrasion resistance. A conventional recording liquid, especially an image recorded by a water-based recording liquid, tends to cause blushing or blurring due to water adhesion, light irradiation or mechanical friction, and a recording liquid improved with these drawbacks is strongly desired. . In particular, with respect to water resistance, the demand for it has been increasing in recent years, and urgent development is desired.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a recording liquid having excellent storage stability for ink jet recording and excellent water resistance when recorded on plain paper.

[0010]

The present invention provides a recording liquid containing a recording agent, which is a component forming a recorded image, and an aqueous medium, and has a sulfonic acid group in the molecular structure as the recording agent,
In addition, one of the sulfonic acid groups is salified with triethylenetetramine, and the remaining sulfonic acid group forms a salt with an alkali metal [A], [B],
The gist is a recording liquid containing at least one water-soluble dye represented by [C].

In the present invention, the general formula [A],
One of the sulfonic acid groups of the water-soluble dyes represented by [B] and [C] is salified with triethylenetetramine, and the remaining sulfonic acid groups form salts with alkali metals such as lithium, potassium and sodium. You need to use what you are doing. Lithium is most preferred as the alkali metal. In the present invention, it is necessary to form only one of the sulfonic acid groups with triethylenetetramine, and if two or more sulfonic acid groups have the same salt, the stability of the dye will be reduced.

The preparation of the recording agent which provides the water-resistant recording liquid is as follows.
Usually, a concentrated aqueous solution in which a sulfonic acid group in the molecular structure of the water-soluble dye is bonded to hydrogen (hereinafter referred to as H type) is prepared in advance, and a necessary amount of triethylenetetramine is added to the concentrated aqueous solution. Further, a necessary amount of an alkali metal hydroxide such as lithium hydroxide is added, and the mixture is stirred and treated.

In short, the sulfonic acid group is usually one bound to an alkali metal such as sodium, potassium or lithium (Na type, K type or Li type), but in order to form a salt with triethylenetetramine specified in the present invention. Therefore, it is necessary to once make them H-shaped. In order to make the above water-soluble dye H-type, it is usually Na-type, K-type or Li-type.
It can be easily obtained by an ion exchange method in which an aqueous solution of the above water-soluble dye of the type is passed through a packed bed of the H type cation exchange resin.

Even if triethylenetetramine is added to and mixed with an aqueous solution of the Na-type, K-type, or Li-type water-soluble dye, salification cannot be satisfactorily performed, and a desired effect cannot be sufficiently obtained. General formula [A] in which one of the sulfonic acid groups in the molecular structure is salified with triethylenetetramine and the remaining sulfonic acid groups form a salt with an alkali metal.
The concentration of the water-soluble dyes represented by [B] and [C] in the recording liquid is usually about 0.5 with respect to the total composition in the recording liquid.
The range is from 10 to 10% by weight, preferably from 2 to 6% by weight.
In the recording liquid of the present invention, various known aqueous media and additives are added according to a conventional method. Specific examples of these aqueous media and additives include diethylene glycol, thiodiglycol, glycerin, triethanolamine, ethyldiethanolamine, N-hydroxyethylmorpholine, N-methyl-2-pyrrolidone, 2-propanol, urea and thiourea. Etc.

It was confirmed by a stability test that the recording liquid of the present invention has excellent storage stability, and the water resistance of the recorded image is 0. D. It was confirmed by measuring (Optical Density).

[0016]

The present invention is described in detail in the following examples.
The present invention is not limited to these examples. The evaluation method in this example is as follows.

Water resistance test O. D. After the recorded image sample (solid print) was dried for 24 hours, it was measured with a Macbeth reflection densitometer (RD-914).
D. (Optical Density: Optical Density) (initial value), the same sample was placed in a container containing water at 25 ° C., immersed for 5 minutes, dried, and then dried. D. Was measured (test value) to obtain a ratio before and after the test (OD ratio = OD (test value) / OD (initial value)). O. D. The ratio close to 1 indicates that the water resistance is good.

Visual determination After the recorded image sample (character print) was dried for 24 hours, it was placed in a container containing water at 25 ° C. and immersed for 5 seconds, and then the degree of bleeding of characters when pulled up and dried was measured. It was judged visually. ◎: Almost no bleeding ○: Some bleeding △: Bleeding ×: Severe bleeding

Stability Test The prepared aqueous solution of the water-soluble dye [A] is heated to 40 ° C. in a constant temperature bath.
And the stability over time (14 days) was evaluated by LC analysis before and after the test. ⊚: No decomposition ○: Almost no decomposition △: Some decomposition ×: Severe decomposition

Example 1 In the form of free acid, the following general formula [A]

[0021]

[Chemical 2]

250 kg of a 2% aqueous solution of a Na-type water-soluble dye [A] having a sulfonic acid group in the molecular structure represented by
Packed with a strongly acidic sulfonic acid type cation exchange resin [Diaion SK-1B (H type / gel type, manufactured by Mitsubishi Kasei Co., Ltd., trade name)] (diameter 10 cm, height 1
The H-type water-soluble dye [A] was obtained by subjecting the solution to a liquid-flowing treatment at a temperature of 25 ° C. from the upper part of 40 cm).

The amount of triethylenetetramine (TETA) necessary for one of the sulfonic acid groups in the molecular structure of the H-type water-soluble dye [A] thus obtained to be salinized with triethylenetetramine (TETA). A water-soluble dye [A] having water resistance was prepared by adding lithium hydroxide necessary for the remaining sulfonic acid group to form a salt with lithium. A water-soluble dye [A] in which one of the sulfonic acid groups is salified with triethylenetetramine and the remaining sulfonic acid group forms a salt with lithium (hereinafter referred to as a water-soluble dye having a salinization degree of 1/4 [A ]), A recording liquid having the following composition was prepared, and a water resistance test and a stability test were performed on the recording liquid.

[0024]

[Table 1] Water-soluble dye [A] with a chlorination degree of ¼ 3.6% by weight Diethylene glycol 15.0% by weight 2-propanol 3.0% by weight Demineralized water 78.4% by weight

Comparative Example 1 H-type water-soluble dye [A] obtained in the same manner as in Example 1.
Of the sulfonic acid groups of the above, triethylenetetramine (TETA) is added so that two of the sulfonic acid groups are salified with triethylenetetramine (TETA), and the remaining sulfonic acid groups form salts with lithium. A water-soluble dye [A] of / 4 was prepared. A recording liquid having the following composition was prepared using the water-soluble dye [A] having a salinization degree of 2/4, and the results of water resistance test and stability test were conducted on the recording liquid.
Shown in.

[0026]

[Table 2] Water-soluble dye [A] having a chlorination degree of 2/4 4.2% by weight Diethylene glycol 15.0% by weight 2-propanol 3.0% by weight Demineralized water 77.8% by weight

Comparative Example 2 Three of the sulfonic acid groups of the H-type water-soluble dye [A] obtained in the same manner as in Example 1 were triethylenetetramine (T).
Triethylenetetramine (TETA) was added so as to form a salt by ETA), and a water-soluble dye [A] having a degree of salinization of 3/4, in which the remaining sulfonic acid group forms a salt with lithium, was prepared. Using the water-soluble dye [A] having a salinization degree of 3/4, a recording liquid having the following composition was prepared, and a water resistance test and a stability test were conducted on the recording liquid.

[0028]

[Table 3] Water-soluble dye having a degree of chlorination of 3/4 [A] 4.7% by weight Diethylene glycol 15.0% by weight 2-propanol 3.0% by weight Demineralized water 77.3% by weight

Comparative Example 3 Triethylenetetramine so that all (4) of the sulfonic acid groups of the H-type water-soluble dye [A] obtained in the same manner as in Example 1 were salified with triethylenetetramine (TETA). Degree of salinization is 4 by adding (TETA)
A water-soluble dye [A] of / 4 was prepared. This degree of salinization is 4 /
A recording liquid having the following composition was prepared using the water-soluble dye [A] of No. 4, and the results of the water resistance test and the stability test thereof are shown in Table 1.

[0030]

[Table 4] Water-soluble dye [A] having a chlorination degree of 4/4 5.2% by weight Diethylene glycol 15.0% by weight 2-propanol 3.0% by weight Demineralized water 76.8% by weight

Comparative Example 4 Li-type water-soluble dye [A] in which all (4) of the sulfonic acid groups of H-type water-soluble dye [A] obtained in the same manner as in Example 1 form a salt with lithium. ] Was prepared. A recording liquid having the following composition was prepared using this Li-type water-soluble dye [A], and the results of a water resistance test and stability of the recording liquid were shown in Table-
Shown in 1.

[0032]

[Table 5] Li-type water-soluble dye [A] 3.1% by weight Diethylene glycol 15.0% by weight 2-Propanol 3.0% by weight Deionized water 78.9% by weight

Comparative Examples 5, 6 and 7 All of the sulfonic acid groups of the H-type water-soluble dye [A] obtained in the same manner as in Example 1 were diethylenetriamine (DET).
A), tetraethylenepentamine (TEPA) and pentaethylenehexamine (PEHA) were prepared to prepare a water-soluble dye [A]. A recording liquid containing the salified water-soluble dye [A] as a recording agent was prepared, and a water resistance test and a stability test were carried out for the respective recording liquids.

[0034]

[Table 6]

In these comparisons, a water-soluble dye [A] in which one of the sulfonic acid groups in the molecular structure of Example 1 is salified with triethylenetetramine and the remaining sulfonic acid groups form a salt with lithium [A]. Shows that the storage stability is excellent and the water resistance is improved.

As described above, in a recording liquid comprising a recording agent which is a component for forming a recorded image and an aqueous medium, the molecule of the dye represented by the general formula [A], [B] or [C] is used as the recording agent. One of the sulfonic acid groups in the structure is salified with triethylenetetramine, and the remaining sulfonic acid group contains a water-soluble dye that forms a salt with lithium, resulting in excellent storage stability and water resistance. It has become possible to provide an excellent recording liquid.

Example 2 The following general formula [B] in the form of free acid was used.

[0038]

[Chemical 3]

For the Na-type water-soluble dye [B] having a sulfonic acid group in the molecular structure represented by the following, a recording liquid having the following composition was prepared in the same manner as in Example 1, and the water resistance test and the stability test were performed. The results obtained are shown in Table-2. Incidentally, in this example, sodium hydroxide was added so that the remaining sulfonic acid group formed with triethylenetetramine was a sodium salt.

[0040]

[Table 7] Water-soluble dye having a chlorination degree of 1/3 [B] 3.6% by weight Diethylene glycol 15.0% by weight 2-propanol 3.0% by weight Demineralized water 78.4% by weight

Comparative Example 8 Triethylenetetramine so that all (3) of the sulfonic acid groups of the H-type water-soluble dye [B] obtained in the same manner as in Example 2 were salified with triethylenetetramine (TETA). Degree of salinization of 3 by adding (TETA)
A water-soluble dye [B] of / 3 was prepared. This salinity degree 3 /
A recording liquid having the following composition was prepared using the water-soluble dye [B] of No. 3, and the results of the water resistance test and the stability test for the recording liquid are shown in Table 2.

[0042]

[Table 8] Water-soluble dye having a salinization degree of 3/3 [B] 4.6% by weight Diethylene glycol 15.0% by weight 2-propanol 3.0% by weight Demineralized water 77.4% by weight

Comparative Example 9 Na-type water-soluble dye [B] in which all the sulfonic acid groups (4 groups) of H-type water-soluble dye [B] obtained in the same manner as in Example 2 form salts with sodium [B] ] Was prepared. A recording liquid having the following composition was prepared using this Na-type water-soluble dye [B],
Table 2 shows the results of the water resistance test and the stability test.

[0044]

Table 9 Na-type water-soluble dye [B] 3.1% by weight Diethylene glycol 15.0% by weight 2-Propanol 3.0% by weight Demineralized water 78.9% by weight

[0045]

[Table 10]

Example 3 The following general formula [C] was used in the form of free acid.

[0047]

[Chemical 4]

For the Na-type water-soluble dye [C] having a sulfonic acid group in the molecular structure represented by the following, a recording liquid having the following composition was prepared in the same manner as in Example 1, and a water resistance test and a stability test were performed. The results obtained are shown in Table-3. In addition, in this example, lithium hydroxide was added so that the remaining sulfonic acid groups salted with triethylenetetramine became lithium salts.

[0049]

[Table 11] Water-soluble dye [C] having a degree of chlorination of 1/3 3.7% by weight Diethylene glycol 15.0% by weight 2-propanol 3.0% by weight Demineralized water 78.3% by weight

Comparative Example 10 Triethylenetetramine so that all (4) of the sulfonic acid groups of the H-type water-soluble dye [C] obtained in the same manner as in Example 3 were salified with triethylenetetramine (TETA). Degree of salinization is 4 by adding (TETA)
A water-soluble dye [C] of / 4 was prepared. This degree of salinization is 4 /
A recording liquid having the following composition was prepared using the water-soluble dye [C] of No. 4, and the results of a water resistance test and a stability test performed on it are shown in Table-3.

[0051]

[Table 12] Water-soluble dye [C] having a chlorination degree of 4/4 5.4% by weight Diethylene glycol 15.0% by weight 2-propanol 3.0% by weight Demineralized water 76.6% by weight

Comparative Example 11 Li-type water-soluble dye [C] in which all (4) of the sulfonic acid groups of H-type water-soluble dye [C] obtained in the same manner as in Example 3 form a salt with lithium. ] Was prepared. A recording liquid having the following composition was prepared using this Li-type water-soluble dye [C], and the results of the water resistance test and the stability of the recording liquid were shown in Table-
3 shows.

[0053]

[Table 13] Li-type water-soluble dye [C] 3.1 wt% Diethylene glycol 15.0 wt% 2-propanol 3.0 wt% Demineralized water 78.9 wt%

[0054]

[Table 14]

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Yumiko Minato 1-1-1 Kurosaki Shiroishi, Hachimansai-ku, Kitakyushu City Mitsubishi Kasei Co., Ltd. Kurosaki Plant

Claims (2)

[Claims] 1. A recording liquid containing a recording agent which is a component for forming a recorded image and an aqueous medium, wherein the recording agent is a water-soluble dye represented by the following general formula [A], [B] or [C]. A recording liquid, characterized in that one of the sulfonic acid groups is salified with triethylenetetramine, and the remaining sulfonic acid group contains at least one water-soluble dye forming a salt with an alkali metal. . [Chemical 1] 2. An aqueous solution of the above water-soluble dye having a sulfonic acid group bonded to sodium, potassium or lithium as a recording agent is treated with an H-type cation exchange resin, and then one of the sulfonic acid groups is salified. In general, triethylenetetramine necessary for the addition of styrene was used to form one of the sulfonic acid groups with triethylenetetramine, and the remaining sulfonic acid group was added with an alkali metal hydroxide to form a salt with an alkali metal. The recording liquid according to claim 1, which is a water-soluble dye represented by the formulas [A], [B], and [C].