JPH038669B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel recording liquid, and particularly to a recording liquid suitable for a recording method in which recording is performed by ejecting the liquid from fine ejection orifices provided in a recording head and flying the liquid as droplets. BACKGROUND ART Writing instruments (fountain pens, felt-tip pens, etc.) for recording on recording materials such as paper have conventionally used inks prepared by dissolving various dyes in water or other organic solvents. In addition, in the so-called inkjet recording method, in which recording is performed by ejecting the liquid in the recording head from the ejection orifice using vibrations by a piezo vibrator or electrostatic attraction due to the application of high voltage, various dyes are dissolved in water or organic solvents. It is known that compositions are used. However, compared to inks for stationery such as general fountain pens and felt pens, recording liquids for ink jets require more stringent conditions in terms of many characteristics. In such an inkjet recording method, recording is performed by causing droplets of a recording liquid called so-called ink to fly and adhere to a recording material. The basic components of such a recording liquid include a recording agent (dye or pigment is used) and a liquid medium for dissolving or dispersing it (water or various organic solvents or a mixture thereof is used), and if necessary, Various additives are added. There are various types of such recording methods depending on the method of generating droplets and the method of controlling the flight direction of the droplets. An example is shown in FIG. That is, the apparatus shown in FIG. 1 applies a recording signal to a recording head section having a piezo vibrator, and performs recording by generating droplets of recording liquid in response to the signal.
In FIG. 1, reference numeral 1 denotes a recording head, which has a piezo vibrator 2a, a diaphragm 2b, an inlet 3 for recording liquid, a liquid chamber 4 in the head, and an ejection port (ejection orifice) 5. A recording liquid 7 stored in a storage tank 6 is introduced into the liquid chamber 4 through a supply pipe 8 . Incidentally, an intermediate treatment means 9 such as a pump or a filter may be provided in the middle of the supply pipe 8 depending on the case. And in the piezo vibrator 2a,
A signal converted from the recording signal S into a pulse by a signal processing means (for example, a pulse converter) 10 is applied, and a pressure change occurs in the recording liquid in the liquid chamber 4 in accordance with the signal. As a result, the recording liquid 7 is discharged from the discharge orifice 5 in the form of droplets 11, and recording is performed on the surface of the recording material 12. In addition, various types of devices other than the above-mentioned devices are known. For example, as shown in FIG. 2, as a modification of FIG. There is an apparatus in which a piezo vibrator is installed (the mechanism of droplet generation in this apparatus is essentially the same as the apparatus shown in FIG. 1). In addition, there is a device that continuously generates charged droplets and uses a portion of the droplets for recording, or a device that applies thermal energy corresponding to the recording signal to the recording liquid in the chamber of the recording head, and uses the energy to generate the droplets. Devices and the like for generating this are also known. An example thereof is shown in Fig. 3-a, Fig. 3-b, and Fig. 4. The head 13 is made of glass, ceramic, plastic plate, etc., having grooves 14 through which ink passes, and a heat-generating head 15 used for thermal recording (a thin film head is shown in the figure, but is not limited to this). Obtained by gluing. Heat generating head 1
5 is made up of a protective film 16 made of silicon oxide or the like, aluminum electrodes 17-1, 17-2, a heating resistor layer 18 made of nichrome or the like, a heat storage layer 19, and a substrate 20 with good heat dissipation properties such as alumina. It's on. The ink 21 has reached the discharge orifice 22 and forms a meniscus 23 due to the pressure P. Now, when an electric signal is applied to the electrodes 17-1 and 17-2, the area indicated by n of the heating head 15 suddenly generates heat, bubbles are generated in the ink 21 in contact with this area, and the pressure causes the meniscus 23 to rise. protrudes, and the ink 21 is ejected from the orifice 22 into a recording droplet 2.
4 and flies toward the recording material 25. Fourth
The figure shows an external view of a multi-head in which a large number of heads shown in Figure 3-a are arranged. The multi-head is manufactured by gluing together a glass plate 27 having multi-grooves 26 and a heating head 28 similar to that described in FIG. 3-a. Note that FIG. 3-a is a sectional view of the head 13 along the ink flow path, and FIG. 3-b is a cross-sectional view taken along line A-B in FIG. 3-a. Conventionally, as this type of recording liquid, for example,
-8361, Special Publication No. 51-40484, Special Publication No. 13126, Special Publication No. 52-13126
As shown in Japanese Patent Publication No. 52-13127 and Japanese Patent Application Laid-Open No. 50-95008, various dyes and pigments are dissolved or dispersed in aqueous or non-aqueous solvents. The preferred conditions for this type of recording liquid are (1) liquid physical properties (viscosity, surface tension, electrical conductivity, etc.) that match the ejection conditions (piezoelectric element drive voltage, drive frequency, orifice shape and material, orifice diameter, etc.); have the following. (2) Stable for long-term storage and should not cause clogging. (3) Fixation is fast on the recording material (paper, film, etc.) and the dot periphery is smooth with little bleeding. (4) The color tone of the printed image is clear and the density is high. (5) The printed image must have excellent water resistance and light resistance. (6) The recording liquid should not corrode surrounding materials (containers, connecting tubes, sealing materials, etc.). (7) It must be safe in terms of odor, toxicity, flammability, etc. It is quite difficult to simultaneously satisfy the above characteristics. The prior art described above was unsatisfactory in this respect. Since the recording liquid used for such recording purposes is basically composed of a dye and its solvent, the above-mentioned characteristics of the recording liquid are largely influenced by the inherent properties of the dye. Therefore, selecting a dye so that the recording liquid has the above characteristics is an extremely important technique in this technical field. As a result of extensive research, the present invention was completed by finding a dye suitable for the recording liquid used for this purpose. That is, the recording liquid of the present invention includes a recording agent as a component for forming a recorded image and a liquid medium for dissolving or dispersing this recording agent, and the recording agent is represented by the following general formula [A]; (In the formula, M represents an alkali metal, ammonium, or amines.) It is characterized by containing at least one dye represented by the following formula. The general formula [A] contained in the recording liquid of the present invention
In the dye, M is an alkali metal such as Na, K, Li, NH ₄ , NH(C ₂ H ₄ OH) ₃ , NH
Examples include ammonium and amines such as (CH ₃ ) ₃ and NH(C ₂ H ₅ ) ₃ . The general formula [A] contained in the recording liquid of the present invention
Specifically, dyes having the following chemical structures can be mentioned. The dye of the present invention can be used, for example, in "New Dye Chemistry" by Yutaka Hosoda (published December 21, 1970), Gihodo, p. 397.
It can be produced by the following method according to the description from line 27 to page 398, line 19, etc. General formula below [] After diazotizing the amines represented by with sodium nitrite in a mineral acid such as hydrochloric acid or sulfuric acid, the following general formula [] Coupled with amines represented by the following general formula [] A monoazo compound represented by is obtained. After diazotizing this monoazo compound using sodium nitrite in a mineral acid such as hydrochloric acid or sulfuric acid,
1-hydroxy-7-amino-naphthalene-3,
The volume can be obtained by coupling with 6-disulfonic acid. Among the above-mentioned required properties, these dyes are especially stable for long-term storage compared to recording liquids using conventionally known dyes having similar chemical structural formulas (1) to (6) below. In addition to being extremely superior in not causing clogging, it also has clear superiority in terms of light resistance and water resistance. In the inkjet recording method, nozzle clogging is a very important factor in terms of the reliability of the recording method. Conventionally, for example, automatic capping of the nozzle (enveloping the nozzle in a saturated vapor state when not in use) was used. Mechanical countermeasures, such as manual pumps and other countermeasures, have been proposed, but they have not always been sufficiently effective. Recording fluids for inkjet use mainly water-based liquid media for safety reasons, and generally low-volatility water-soluble organic solvents such as glycols are added to this as wetting agents. There is. The solubility of dyes in these liquid media varies slightly depending on their structure, and generally the solubility in water and the solubility in glycols even tend to contradict each other. At the tip of the nozzle, water, which is a highly volatile component in the ink, tends to volatilize, and therefore the concentration of glycols tends to increase in this area. Therefore, if a dye with low solubility in glycols is added to the recording liquid, there is a high risk that the dye will precipitate and cause nozzle clogging. The dyes (1) to (6) listed above exhibit very good solubility in water, but have poor solubility in glycols. On the other hand, the dye represented by the general formula [A] used in the recording liquid of the present invention is
It has improved solubility in glycols while maintaining solubility in water within a practically sufficient range, and is therefore extremely unlikely to cause nozzle clogging. According to the present invention, physical property values such as viscosity and surface tension are within appropriate ranges, do not clog the fine discharge orifice, provide recorded images with sufficiently high density, and prevent changes in physical property values during storage. Alternatively, it can record on a variety of materials without causing solid content precipitation, without limiting the type of recording material, has a high fixing speed, and provides images with excellent water resistance, light resistance, abrasion resistance, and resolution. A recording liquid is obtained. The content of the above-mentioned color component, that is, dye, is determined depending on the type of liquid medium component, the characteristics required of the recording liquid, etc., but is generally 0.1 to 0.1% by weight based on the total weight of the recording liquid. 20%, preferably 0.5
~15%, more preferably 1~10%. Of course, these dyes can be used alone or in combination of two or more, or in combination with various dyes such as other direct dyes and acid dyes, using the dye as an essential component. As a liquid medium component for composing the recording liquid of the present invention, water or a mixture of water and various water-soluble organic solvents is used. Examples of water-soluble organic solvents include alkyl alcohols having 1 to 4 carbon atoms such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, and isobutyl alcohol. Alcohols; Amides such as dimethylformamide and dimethylacetamide; Ketones or ketone alcohols such as acetone and diacetone alcohol; Ethers such as tetrahydrofuran and dioxane; N-
Methyl-2-pyrrolidone, 1,3-dimethyl-2
-Nitrogen-containing heterocyclic ketones such as imidazolidinone; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,
Alkylene glycols in which the alkylene group contains 2 to 6 carbon atoms such as 2,6-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol: glycerin; ethylene glycol methyl ether, diethylene glycol methyl (or ethyl) ether, triethylene glycol; Examples include lower alkyl ethers of polyhydric alcohols such as ethylene glycol monomethyl (or ethyl) ether. The content of the water-soluble organic solvent in the recording liquid is generally 5% by weight based on the total weight of the recording liquid.
~95%, preferably 10-80%, more preferably 20
It is said to be in the range of ~50%. The water content at this time depends on the type of solvent component mentioned above,
Although it is determined within a wide range depending on the composition and desired properties of the recording liquid, it is generally 10 to 90%, preferably 10 to 70%, more preferably 20 to 70% of the total weight of the recording liquid. considered to be within the range. 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, and long-term recording cessation). discharge stability), storage stability,
Fixability to recording material or light resistance of recorded images,
Weather resistance, water resistance, etc. are both well-balanced and excellent. In order to further improve such properties, various conventionally known additives may be further added. For example, viscosity modifiers such as polyvinyl alcohol, celluloses, and water-soluble resins; various cationic, anionic, or nonionic surfactants; surface tension modifiers such as diethanolamine and triethanolamine; PH modifiers using buffer solutions, and mold prevention agents. Agents, etc. can be mentioned. Further, in order to prepare the recording liquid used in the type of inkjet recording method in which the recording liquid is charged, a resistivity adjusting agent such as inorganic salts such as lithium chloride, ammonium chloride, and sodium chloride is added. Note that when applied to an inkjet method in which the recording liquid is ejected by the action of thermal energy, the thermal properties (e.g., specific heat, coefficient of thermal expansion, thermal conductivity, etc.) may be adjusted. be. The invention will be explained in more detail in the following examples. Example 1 Ion exchange water (hereinafter abbreviated as water) 71 parts by weight diethylene glycol 25 No. 1 dye 4 The above components were thoroughly mixed and dissolved in a container, and filtered under pressure using a Teflon filter with a pore size of 1μ. ,
The recording liquid was degassed using a vacuum pump.
Using the obtained recording liquid, an on-demand recording head (discharge orifice diameter 50μ, piezo vibrator drive voltage
By a recording device with 60V, frequency 4KHz),
When the following examinations were conducted for T ₁ to _{T 5} , good results were obtained in all cases. Long-term storage stability of T ₁ recording liquid; Even after recording liquid was sealed in a glass container and stored at -30℃ and 60℃ for 6 months, no precipitation of insoluble matter was observed, and there was no change in the physical properties or color tone of the liquid. Ta. T ₂ ejection stability: Continuous ejection was performed for 24 hours in an atmosphere of room temperature, 5° C., and 40° C. Under all conditions, stable high-quality recording was possible from beginning to end. T ₃ Ejection response: Intermittent ejection for 2 seconds and ejection after 2 months of standing were investigated, and in both cases stable and uniform recording was achieved without clogging at the orifice tip. T ₄ Quality of recorded images: The recorded images had high density and clarity. The rate of decrease in concentration after 3 months of exposure to indoor light is 1%.
Furthermore, when immersed in water for 1 minute, there was very little blurring of the image. T ₅ Fixability for various recording materials; After 15 seconds of printing with the recording materials listed in the table below, the printed area was rubbed with a finger to determine the presence or absence of image shift/bleeding. All were excellent with no image shift/bleeding. It showed fixability.

[Synthesis of No. 1 dye in Example-1]

(1) Production of first diazo liquid 2-amino-naphthalene-5-sulfonic acid 22.3
g was added to 446 ml of 3% hydrochloric acid and stirred for 3 hours to form a uniform slurry. 200g of ice was added to this and the mixture was cooled to 3°C. An aqueous solution of 7.3 g of sodium nitrite dissolved in 73 ml of water was added to this slurry. then 3
After diazotization by stirring for 1 hour at °C, 3 g of sulfamic acid was added to eliminate remaining sodium nitrite to obtain a first diazo solution. (2) Production of second diazo liquid 1,7clave acid 22.3g was added to 450ml of water and stirred for 2 hours to form a uniform slurry. To this, add 300 g of ice, the first diazo solution obtained in (1) above, and 10 ml of 25% caustic soda.
After stirring for 15 hours at a temperature of 0 to 3°C and a pH of 2 to 3 to perform coupling, 200 g of common salt was added to perform salting out. After filtering out the precipitated monoazo compound,
Wash with 500ml of 10% saline and dry to form a monoazo compound. 40.1g was obtained. 25.0 g of the obtained monoazo compound was added to 500 ml of 5% hydrochloric acid and stirred for 5 hours to form a uniform slurry, and then 300 g of ice was added and cooled to 3°C.
In this slurry, add 3.8 g of sodium nitrite to 38 ml of water.
An aqueous solution of was added. Next, the mixture was stirred at 3° C. for 4 hours to undergo diazotization, and then 1 g of sulfamic acid was added to eliminate the remaining sodium nitrite to obtain a second diazo solution. (3) Coupling 1-hydroxy-7-amino-naphthalene
After adding 16.0 g of 3,6-disulfonic acid to 460 ml of water, 800 g of ice, the second diazo solution obtained in (2) above, and 55 ml of 25% caustic soda were added to the mixture to give a pH of 8 to 10.
Coupling was carried out at a temperature of 2-5°C. After stirring for 5 hours at the same temperature and pH, 250 g of salt
was added to salt out the dye. After filtering out the precipitated pigment, wash with 300ml of 10% saline and make a wet cake 240ml.
I got g. This wet cake is desalinated and then dried to produce the desired dye. 35.5g was obtained. The yield was 81.3%. The results of elemental analysis were as follows.

[Example-2 Synthesis of dye No. 2]

(1) Production of first diazo liquid A first diazo liquid was obtained according to the method (1) of Reference Example 1. (2) Production of second diazo liquid The steps in (2) of Reference Example 1 were repeated except that 1,6-clave acid was used instead of the first diazo liquid obtained in (1) above and 1,7-clave acid. According to the method, the following monoazo compounds A diazo liquid (second) was obtained. (3) Coupling According to the method (3) of Reference Example 1, the desired dye 35.4g was obtained. The yield was 81.0%. The results of elemental analysis were as follows.

【table】 [Brief explanation of the drawing]

1 and 2 are schematic diagrams of an inkjet recording apparatus, respectively. Figures 3-a and 3-b are a vertical sectional view and a horizontal sectional view of a main part of another recording device. FIG. 4 is an external perspective view of a multi-head head shown in FIGS. 3-a and 3-b. However, in the figure, 1...recording head, 2a...
...Piezo vibrator, 2b...Vibration plate, 3...Inflow port, 4...Liquid chamber, 5...Discharge orifice, 6...
Storage tank, 7... Recording liquid, 8... Supply pipe, 9...
...Intermediate processing means, 10...Signal processing means, 11...
...Droplet, 12, 25... Recording material, S... Recording signal, 14... Liquid chamber, 15... Heat generating head, 16...
... protective layer, 17 ... electrode, 18 ... heating resistor layer, 19 ... heat storage layer, 20 ... substrate, 26 ... groove.

Claims (1)

[Scope of Claims] 1. In a recording liquid containing a recording agent which is a component for forming a recorded image and a solvent for dissolving or dispersing this recording agent, the recording agent is represented by the following general formula [A] (In the formula, M represents an alkali metal, ammonium, or amines.) A recording liquid characterized in that it contains at least one dye represented by the following formula. 2. The recording liquid according to claim 1, wherein the dye represented by the general formula [A] is contained in an amount of 0.1 to 20% by weight based on the total weight of the recording liquid.