JP2517600B2 - Recording liquid - Google Patents

Description

TECHNICAL FIELD The present invention relates to a dye, particularly a magenta dye which is excellent as an ink component for ink jet, and can be applied to a functional dye, various writing instruments, and a stamp ink.

[Prior Art] Although many dyes for magenta ink are conventionally known,
Among them, those having a good color tone are limited, and examples thereof include xanthene-based dyes or monoazo dyes using H acid as a coupler.

However, xanthene-based dyes have poor light resistance, and monoazo dyes have insufficient water resistance of images formed on plain paper.

[Object] The present invention solves the above problems of the prior art, and provides a magenta dye having a good color tone, excellent weather resistance, water resistance, and jetting stability, and an inkjet ink containing the same as a coloring component. Is intended.

[Structure] As a result of intensive studies to achieve the above object, it was found that the dye having the structure shown in the claims satisfies the above conditions. It is particularly emphasized that the dye of the present invention has a clear color tone, good water resistance and good solubility because of the sulfone group.

The feature of the present invention is to include a dye synthesized by reacting a compound A group having two diazonium ions with a coupler B group having two sites capable of forming an azo bond by the diazonium ion.

 A synthesis example will be described below.

The following compound (1) will be described as an example of the compound B group, and the following compound (2) will be described as an example of the group A.

0.01 mol of compound (1) and 0.02 mol of sodium carbonate in water
Add to 100 ml and stir. If necessary, 7 to 10 wt% of sodium chloride is added. This is a solution (1).

Separately, 0.01 mol of compound (3) was dissolved in 100 ml of water. Add 7 ml of 35% hydrochloric acid and add 0.02% sodium nitrite to this solution.
A solution of compound (2) is prepared by adding 10 ml of a molar aqueous solution at 5 ° C or lower [solution (2)].

This solution (2) is gradually added to the above solution (2) at 5 ° C. or lower. At this time, adjust with sodium carbonate to keep the pH at 8-10. The compound (2) is added in an amount of 0.5 times to 1.0 times the number of moles of (1).

When the addition amount of (2) is increased, the water resistance on paper is improved accordingly (see Table 4). On the other hand, the color tone is almost the same as that of the basic monoazo dyes exemplified below, and shows vivid magenta. The basic monoazo dye here means a monoazo dye having a skeleton close to that of the present dye.

The compound synthesized in this method is considered to have the following structure.

When the number of moles of the compound of the group B is 1, and the amount of the compound of the group A added is 0.5 mol or less, the process mainly proceeds according to the following formula.

A + 2B → B−A−B (1) Here, A and B are compounds of Group A and Group B, respectively.
The bond between them is connected by an azo bond -N = N-. Since it is an alkaline reaction, the coupling position of B is the ortho position of the hydroxyl group and BAB has the following structure.

Of course, at this time, since there are two coupling positions in B, the following reaction has proceeded to some extent.

B−A−B + A + B → (B−A) ₂₋ B (2) However, A is added very slowly (addition of 0.01 mol takes about 30 minutes). Moreover, if an inorganic salt (sodium chloride in this case) is added to the reaction solution in an amount of 7 wt% or more, the product will go out of the reaction system due to association, etc. (1)
Has priority. When actually observed by thin layer chromatography, A is B
It was confirmed that most of B was consumed at the time when half a mole of B was added.

When A is further added, the following formulas (3) and (4) proceed.

A + 2 (B-A-B)-> (B-A) _3- B ... (3) A + 2 [(B-A) _3- B]-> (B-A) _7- B ...
(4) When A is further added, a polymer having a higher molecular weight is produced.

→ (B−A) n−B As described above, if the addition rate of A is suppressed or the inorganic salt is added, the reactions (1), (3), and (4) are considered to be prioritized. It is expected that n = 2, 5, 6, etc. will co-produce simultaneously. However, there is no great difference in color tone and other properties, so there is no problem even if they are mixed.

However, if the amount of A added is made too large, the number of moles of B becomes 0.
If it exceeds 9 times, some of the components may not dissolve easily (it is expected that it has a considerably high molecular weight), so 0.9 times or less is preferable.

In the case of those shown on the synthesis side, these components which are expected to differ in n are observed by being separated by liquid chromatography, but the visible absorption spectrum shoulders are the same and a clear color tone is maintained. These are absorption type and the absorption wavelengths are almost the same as the following disazo dyes.

However, although these disazo dyes are developed by thin layer chromatography on silica gel (developing solvent pyridine 5, water 2, n-butyl acetate 3), those in which the amount of A added is 0.6 or more of B do not develop at all. This is because the molecules became larger and the adsorption capacity increased. However, its solubility in water and wetting agents
15% or more, which can be sufficiently used for inkjet ink. The following table shows the results of elemental analysis when the amount of A added was 0.8 times the molar amount of B. It was expected that n = 3 to 7, but it was confirmed from this elemental analysis result that n = 3 or more.

It is well known that when the reaction pH is lowered (4 to 6), an azo bond is formed at the para or ortho position of the amino group.

The structural examples of the compounds of group B and group A are shown below. Any combination of Group B total structures and Y structures and Group A species is possible. However, in the group A structure after No. 10 and in all the structures of group B, Nos. 4 and 5, there is a conjugation between both ends, so that the wavelength shift is easier than the basic monoazo structure. Of course, the water resistance is still improved.

The ink of the present invention uses water as a solvent component, but in order to adjust the physical properties of the ink to desired values, for the purpose of preventing the ink from drying, improving the solubility of the dye, etc., the following water-soluble It is also possible to use a mixture of an organic solvent and water.

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

Of these, particularly preferred are diethylene glycol, polyethylene glycol 200 to 600, triethylene glycol, ethylene glycol, glycerin, and N-methyl-2-pyrrolidone. By using this,
The high solubility of the dye and the effect of preventing clogging due to the prevention of water evaporation can be obtained.

The content of the water-soluble organic solvent in the ink can be used in the range of 5 to 80 wt% with respect to the total weight of the ink, but it is preferably used in the range of 15 to 60 wt% in view of viscosity, drying property and the like.

To the ink of the present invention, conventionally known additives may be added in addition to the dye and solvent.

For example, as antiseptic / antifungal agents, sodium dehydroacetate, sodium sorbate, 2-pyridinethiol-1
-Sodium oxide, sodium benzoate, 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 to 11 without adversely affecting the prepared ink.

Examples thereof include amines such as diethanolamine, triethanolamine and monoethanolamine, hydroxides of alkali metal elements such as lithium hydroxide, sodium hydroxide and potassium hydroxide, ammonium hydroxide, quaternary ammonium hydroxide and carbonic acid. Examples thereof include alkali metal carbonates such as lithium, sodium carbonate and potassium carbonate.

Examples of the chelating agent include ethylenediaminetetraacetic acid sodium salt, nitrilotriacetic acid sodium salt, hydroxyethylethylenediaminetriacetic acid sodium salt, diethylenetriaminepentaacetic acid sodium salt, and uramil diacetic acid sodium salt.

Examples of the rust preventive agent include acidic sulfite, sodium thiosulfate, ammonium thioglycolate, diisopropylammonium nitrite, pentaerythritol nitrate, and pentaerythritol nitrate.
Dicyclohexyl ammonium nitrite and the like.

In addition, a water-soluble ultraviolet absorber, a water-soluble infrared absorber, a water-soluble polymer compound, a dye dissolving agent, a surfactant and the like can be added depending on the purpose.

Examples Table 1 below shows the specific constitution of each example.

In each of the examples, A / B (molar ratio) is 0.75 or 0.85.
It is what

No. 1 to No. 12 are alkaline (pH 8 to 10) and No. 13 to 16 are acidic (pH 4 to 7).

Wetting agent species A. Glycerin B. Diethylene glycol C. Trierylene glycol D. Ethylene glycol Antiseptic and antifungal agent species A. Sodium sorbate B. Zodium omazine C. Sodium benzoate Comparative Example Table 2 below shows a specific configuration of the comparative example.

All are M≡N ⁺ (CH ₃ ) ₄ Dye of Comparative Example No. 1 (Example of monoazo dye) Comparative Example No.5 CI Direct Red 9 The test results of the inks produced in the above Examples and Comparative Examples are shown in Table 3 below.

 Each test method is as follows.

1) Image sharpness An ink jet printer for Ricoh word processor report 5600J was filled with the prepared ink and printing was performed.

The ink for which a clear image was obtained is represented by a circle in Table 3. Bond paper is used.

2) Lightfastness of image The image sample obtained in 1) was applied to a fade meter (carbon arc lamp, 63 ° C) for 3 hours, and the image density after light irradiation was measured by a Macbeth densitometer, and the photobleaching rate was calculated by the following formula. .

Fading rate (%) = (1-image density after light irradiation / image density before light irradiation) x 100 Paper is commercially available bond paper.

3) Water resistance of the image The image sample obtained in 1) is immersed in water at 30 ° C. for 1 minute,
The image densities before and after the immersion were measured with a Masbeth densitometer, and the water fading rate was obtained by the same formula as in the item 2). Commercially available bond paper is used.

4) Storability Put the ink in a container made of polyethylene, -20 ℃, 4 ℃,
It was stored at 20 ° C., 50 ° C. and 70 ° C. under the respective conditions for 3 months, and the viscosity before and after the storage, the change in surface tension, the electric conductivity, and the presence or absence of precipitation were examined. Table 3 shows that no change in physical properties or precipitation was observed under any conditions.
And

5) Nozzle Clogging Test 1) After printing in 1), printing is paused at 20 ℃, 65% RH
After being left for 2 months in the above environment, it was examined again whether or not normal printing was possible.

One sample was tested using 3 printers.

In Table 3 below, the case where all three printers were able to print normally is shown as ○, and the case where one or two printers failed to print normally was shown as ×, and the case where all three printers could not be printed normally is shown as XX. . The 5600J printer is a device for automatically detecting when nozzles are clogged and jetting is no longer possible, and when the jetting direction has changed significantly compared to before leaving it, the printer operation is stopped. Is attached.

Table 4 below shows the water fading rate of images formed on commercially available bond paper using the ink of the present invention and the other inks.

However, No. 1 in Table 4 is a compound having the following structure.

[Effects] As described above, an image using the recording liquid of the present invention has little fading due to water, and the present invention can be said to be extremely excellent as an image forming recording liquid.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiroyuki Uemura 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Kiyo Nagai 1-3-6 Nakamagome, Ota-ku, Tokyo No. Stock Company Ricoh

Claims (1)

(57) [Claims] 1. An aqueous solution containing any of the following compounds of group B under alkaline conditions (pH 8-10) or acidic conditions (pH 4-10).
6) A recording liquid containing a dye synthesized by azo coupling by adding the compound of any one of the following Group A under a molar amount of 0.5 to 1.0 times that of the compound of the B group under 6). Group B compounds However, the above Y is , M is any one of Li, Na, K, and (NR ′ ₄ ) ⁻ (wherein R ′ is an alkyl group). Where R is any one of an alkyl group, a carboxyl group, a sulfone group, and a halogen atom, p is any one of 0, 1, and 2, and X ⁻ is Cl ⁻ or BF ^−. Is.