JPS58176256A - Recording liquid - Google Patents

Abstract

PURPOSE:To provide a recording liquid which has prolonged continuous recordability and discharge stability after long-term recording suspension and is suitable for use in writing utensiles and ink jet recording, containing a specified monoazo compd. CONSTITUTION:0.5-20wt% compd. (dye) of the formula [wherein R1 is H, OH, NH2; R2 is H, SO3M (wherein M is alkali metal, ammonium, amine); R3, R4 are each H, OH, NH2, NO2, SO3M; R5 is H, NH2; R6, R7 are each SO3M] is dissolved in a recording liquid. Since said compd. has an azo linkage in the molecule, it can be thought that even when the recording liquid is instantaneously exposed to high temperature above 250 deg.C in a thermal action part in a recording head and the compd. is decomposed, the molecular chain is mainly broken at the azo linkage part. Therefore, the decomposition products of said compd. are relatively stable per se and most of them contain highly hydrophilic groups such as SO3M or OH so that they are highly soluble in the recording liquid. Thus, stable recording becomes possible without forming precipitates.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recording liquid suitable for use in an inkjet system that performs recording by ejecting droplets from an orifice of a writing instrument or a recording head, and particularly for an inkjet system that uses thermal energy. @ Traditionally, writing instruments (fountain pens, felt-tip pens, etc.) that record on recording materials such as paper have used II'i, ink made by dissolving various dyes in water or other organic solvents, which is counterfeit. , recording head due to vibrations caused by a piezoelectric vibrator or electrostatic attraction caused by applying a high voltage.

It is known that the so-called inkjet method, which performs recording by ejecting a liquid inside, uses ink in which various dyes are dissolved in water or a specific solvent. However, ink for general stationery The inkjet recording method, which requires stricter conditions in terms of many properties, generates less noise, does not require special fixing treatment on plain paper, and can record at high speeds. One theory is that it is a turtle that can record in color, and various types of books are being actively researched.

The characteristics of the ink used in this type of recording method are that the physical property values of viscosity and surface tension are within appropriate ranges, and that the dissolution stability of dissolved substances is high and that the orifice tube is clogged finely. It is required that there be no change in physical properties or precipitation of solids during storage, and that there be no change in physical properties during storage. In addition to the above characteristics, recording can be performed without being limited to the type of recording material, fast fixing speed, water resistance, solvent resistance (
In particular, the following qualities are required: excellent alcohol resistance), excellent abrasion resistance, and giving an excellent painter to the darkness.

Among the inkjet recording methods, for example, Tokkai Sho! 4L-
! The method disclosed in No. 137 is significantly different from other methods in that the driving force for ejecting droplets is obtained by applying thermal energy. That is, in this method, thermal energy is generated in the recording head section in response to a supplied recording signal, and bubbles are instantaneously generated, grown, and disappeared in the recording liquid that has been affected by the thermal energy, and the accompanying configuration Recording is performed by ejecting droplets from the orifice at the tip of the recording head due to changes in the pressure energy of the recording liquid.◇This recording method is extremely effective for so-called on-demand recording, and also Since the section is made into a high-density multi-orifice, full-line type recording sickle operation can be easily realized, so it has the advantage of being able to obtain a high-resolution dark image bond at high speed.

However, in this recording method, thermal energy is directly applied to the recording liquid, and the temperature instantaneously reaches over 230'CI especially at mK where bubbles are generated. Therefore, in addition to the above-mentioned general inkjet ink properties, the recording liquid characteristics to satisfy long-term continuous recording performance or ejection stability after recording has stopped for a long period of time are particularly thermal. Other characteristics are also required, such as high dissolution stability, no clogging of orifices, and no change in ink color due to heat. However, a recording liquid that satisfies all of the characteristics was previously unknown.

An object of the present invention is to provide a recording liquid for writing instruments such as felt-tip pens and for inkjet recording.

Another object of the present invention is to provide a recording liquid for inkjet recording that uses thermal energy, which extends the life of a recording head and has high recording stability over a long period of time.

The above and other objects are achieved by the invention as follows.

That is, the present invention is a recording liquid characterized by containing a compound represented by the following general formula.

However, in the formula, R1 represents hydrogen, OH group or Nrlz group, R2H hydrogen or 803M group, 1t3 and R4 each independently represent hydrogen, on group NlI2 group,
represents a NO2 group or an 803M group, R5 represents a hydrogen-crossed NH2 group, at least 10,000 of H.6 and R7 represent a So3M group, M is a base selected from alkali metals, ammonium and amines; be.

The compound (dye) of the general formula contained in the recording liquid of the present invention generally has a solubility in the recording liquid medium of IO weight or higher, and is soluble at low temperatures (about -3Q゛C). The stability is also increased, and the compound has an azo bond (-N=N
-), so even if the recording liquid is instantaneously exposed to a high temperature exceeding 2 j O'0 in the heat-acting part of the recording head and the compound decomposes, the cleavage will occur mainly at the azo bond. Presumed. Even if decomposition occurs, the decomposition products themselves from the compound are relatively stable, and many of them are \SO3M groups or \O)-
Since it has a highly hydrophilic group such as an I group, it still has high solubility in the recording liquid. Therefore, even during long-term continuous recording, stable recording is possible without forming deposits inside the recording head. Of course, other properties required of dyes for writing instruments or inkjet inks, such as weather resistance, ozone resistance, water resistance of printed matter, alcohol resistance, and even toxicity, are also sufficient.

Specific examples of the compound of the general formula contained in the recording liquid of the present invention include dyes having the following chemical structures.

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More specifically, the bases that combine with the sulfonic acid groups of these compounds to form sulfonate salts include Na'', K'', Li'', and C.
Chirukali metal cations such as a+, NH4, NH(C'
Examples include quaternary ammonium cations such as 4CI()S and amines such as N(c2Hs)s.

In the recording liquid of the present invention, the Towara dye is usually O1! -20 weight, preferably laO, 3-1
3 fold 1 [s x ratio *v<Fit-i.

It can be used under warm conditions. These dyes can of course be used alone or in combination of two or more, or in combination with various dyes such as other direct dyes and acid dyes, with the dye as an essential component. .

Liquid medium components for composing the recording liquid of the present invention include:
A mixture of water or aqueous water and various water-soluble organic solvents is used. Examples of water-soluble organic solvents include methyl alcohol, ethyl alcohol, n-propyl alcohol, inoprobyl alcohol, n-7' methyl alcohol,
Carbon number of 5ec-butyl alcohol, tert-butyl alcohol, isobutyl alcohol, etc.! - Nanotaulkyl alcohols; amides such as dimethylform, dimethylacetate, and the like; acetone.

Ketones or ketone alcohols in the alcohol part; ethers such as tetrahydrofuran and dioxane; N-methyl-2-pyroI)ton, /, 3-dimethyl-
2-imidazo1) Nitrogen-containing complex lambda ketones such as dinone:
Polyethylene glycol, polypropylene glycol and other polyethylene glycols: ethylene glycol, propylene gelylcol, butylene glycol, triethylene glycol, i, 2. t-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol and other alkylene groups containing 2 to 2 carbon atoms; glycerin: ethylene glycol methyl ether, diethylene glycol
Examples include lower alkyl ethers of polyhydric alcohols such as coal methyl (51A-1 ethyl) ether and fluoromonomethyl (or ethyl) ether.

Among the many water-soluble organic solvents of et al., 1, polyhydric alcohol diethylene glycol, polyhydric alcohol lower alkyl ether triethylene glycol monomethyl (or a-ethyl) ether, etc. are preferred. The content of the above-mentioned water-soluble organic solvent is generally expressed as a percentage by weight based on the total weight of the recording liquid, preferably 1o-tos*. d20-60
It is considered to be within the range of 4.

The recording liquid of the present invention, prepared from such components, has excellent recording properties (signal response, stability of droplet formation, , ejection stability, long-term continuous recording performance, ejection stability after long-term recording cessation) storage stability, dissolution stability of the recording agent, fixability to the recording material, or light resistance of the recorded image,
Weather resistance, water resistance, alcohol resistance, etc. are all well-balanced and excellent. ◇In order to further improve these properties, various conventionally known additives are further added. You can let me.

Examples of #1 additives include viscosity modifiers such as polyvinylthicol, cellulose N, and water-based fats;
Various cationic, anionic, or nonionic surfactants; surface tension of jetanolamine, triethanolthymine, etc. 411! Agent: Persimmon is a pH adjusting agent using a buffering agent.

In order to adjust the recording liquid used in the type of recording method in which the recording liquid is charged, a resistivity adjusting agent of inorganic salts such as lithium chloride, ammonium chloride, and sodium chloride is used. In addition, urea and thiourea are preferably used as water retention improvers at the tip of the ejection orifice. E, Ge, Specific heat, Coefficient of thermal expansion,
When using the recording liquid of the present invention as a recording liquid for so-called silver recording utensils, the viscosity (%) may be adjusted.
It is necessary to adjust the physical property values in consideration of compatibility with recording members made of various materials.

The present invention will be explained in further detail in the following Examples □Example
A recording head 0 for inkjet recording, in which ink is ejected by the action of thermal energy, is created as follows: First, an 810 layer (lower layer) is formed on an aluminum substrate to a thickness of 3μ by sputtering, and then After laminating HfB2 to a thickness of 100X as a heat generating resistor layer and further to a thickness of 3000 mm as a chill gate electrode, a heat generating resistor pattern vr of S-0μm xioom was formed by selective etching. Next, a silicon layer was laminated to a thickness of 3300 mm as a protective layer (upper layer) by sputtering to form an electric/thermal converter on the substrate, and then a groove with a width of TOμ×depth of Oμ was carved. The glass plate was FC-bonded so that the groove and the heating resistor matched. Next, the distance between the tip of the heating resistor and the oriice is 2! A recording head was created by polishing the end face of the 11th fencing so as to be consistent with the θμ sheet. On the other hand, the recording liquid was created according to the following formulation using the dye having the chemical structural formula of A/ mentioned above. Structural formula gravel dye 3 parts by weight diethylene glycol Co! I N-methyl-covirolidone 2oz water
j2 I The above-mentioned components were thoroughly mixed and dissolved in a container, passed through a Teflon filter with a pore size of 1 μm under pressure, and then degassed using a vacuum pump to obtain a recording liquid.

This recording liquid is supplied to the recording head, and a continuous printing test is carried out and the recording head is supplied.
Rectangular voltage pulse printing signal! As a result, the recording liquid was able to withstand continuous recording for 750 hours, except that the type of dye and the amount of dye blended were changed. A recording liquid was prepared in the same manner as in Example 1.

Using these recording liquids, a continuous printing test for /j-0 hours similar to that in Example 1 was carried out@However, the printing signal was 310 μs
Table 1 shows the durability times in these trial stations added at the cycle of ec. In addition, the durability time was calculated by subtracting the time when the ink flight became unstable and it became impossible to record a in response to the pulse signal □

Claims (1)

[Claims] A recording liquid characterized by containing a compound represented by the following. However, in the formula, R1 represents hydrogen, an OH group or a Nl-12 group, R2 represents hydrogen or an 80 aM group, and R3
and R4 each independently represent hydrogen, OH group, NH2 group, NO2 group or So3M group, Rs represents hydrogen or NHz group, at least one of R6 and R7 represents a SO3M group, and M is an alkali metal , ammonium and amines.