JPS6155545B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a recording liquid, particularly a recording liquid suitable for use in an inkjet recording method. Non-impact recording methods have the advantage of generating less noise during recording, and among them, inkjet recording allows for high-speed recording and can record on so-called plain paper without the need for special fixing treatment. The method is an extremely powerful recording method, and various methods have been devised, some have been improved and commercialized, and efforts are still being made to put them into practical use. There are some things. In such an inkjet recording method, recording is performed by causing droplets of a recording liquid called ink to fly and adhere to a recording member. 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 recording liquid droplets and the method of controlling the flying direction of the droplets. For example, in FIG. 1, a recording signal is applied to a recording head section having a piezo vibrator, and recording is performed by generating droplets of recording liquid in response to the signal. In FIG. 1, reference numeral 1 denotes a recording head, which includes 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 . still,
In some cases, an intermediate treatment means 9 such as a pump or a filter may be provided in the middle of the supply pipe 8. A signal converted from the recording signal S into a pulse by a signal processing means (for example, a pulse converter) 10 is applied to the piezo vibrator 2a, and the pressure changes in the recording liquid in the liquid chamber 4 in accordance with the signal. occurs. 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 member 12. Various types of such devices are known in addition to the ones mentioned above. For example, as shown in Fig. 2, the liquid chamber 4 is shaped like a nozzle, and a cylindrical piezo vibrator is installed around the outer circumference of the liquid chamber 4. (The mechanism of droplet generation in this device is essentially the same as the device shown in FIG. 1). Alternatively, although not shown in the figure, there is also a device that continuously generates droplets while electrically charging them, and uses a portion of the droplets for recording. Devices that provide signals are also known. There are various types of devices that perform recording by generating droplets in this way, and in order to perform good recording, it is necessary to determine the method of generating droplets or the method of controlling the flying direction of droplets. It is necessary that the recording liquid has appropriate physical properties (eg, viscosity, surface tension, specific resistance, etc.). Furthermore, the recording liquid must not contain any solid content due to vaporization of the liquid medium components or chemical changes in the constituent components of the recording liquid during long-term storage or when recording is stopped. Generally, the ejection orifice of this type of recording device is a minute hole (generally about several tens of microns in diameter), so the generation of solid content may cause clogging, resulting in no droplets being ejected at all. Furthermore, even if ejection does not stop, the generation of solid content has an adverse effect on the generation of uniform droplets or the stable flight of droplets, resulting in poor recording performance, ejection stability, etc.
Ejection responsiveness or continuous recording performance may deteriorate. Alternatively, if the constituent components of the recording liquid undergo chemical changes, the physical properties of the recording liquid, which were adjusted to desired values at the time of preparation, may change, and the recording performance, ejection stability, and ejection response may also deteriorate. Therefore, there is a need for liquid medium components that do not easily vaporize, chemically stable recording agents, or combinations of liquid medium and recording agents that do not cause the above-mentioned drawbacks. Furthermore, it is also required that the recorded image has sufficiently high contrast and clarity. In general, with conventional recording liquids, when attempting to increase the contrast of a recorded image by increasing the content of the recording agent, the ejection orifice tends to become clogged. Therefore, there is a need for a recording agent with high solubility in a liquid medium and a bright color tone. Alternatively, the image once recorded must have water resistance, light resistance, weather resistance, and abrasion resistance. Images recorded with conventional recording liquids, especially water-based ones, tend to bleed or fade due to adhesion of water, light irradiation, or mechanical friction, and there is a strong desire for recording liquids that can improve these drawbacks. ing. From this point of view, many proposals regarding recording liquids have been made, but hardly any practical recording liquids that satisfy all of the above conditions have been obtained. An object of the present invention is to provide a recording liquid that satisfies all of the above conditions. That is, the objective is to provide a recording liquid that does not cause clogging of the ejection orifice, deterioration of quality during storage, or generation of precipitates, and has excellent ejection stability, ejection response, and recording performance when the environmental temperature changes. Another object of the present invention is to provide a recording liquid with excellent color tone and contrast of recorded images. Furthermore, it is an object of the present invention to provide a recording liquid with excellent fixing properties in which recorded images have water resistance, light resistance, weather resistance, and abrasion resistance. The inkjet recording liquid of the present invention that achieves the above object is composed mainly of a dye compound represented by the following general formula (A) and a solvent containing at least a nitrogen-containing heterocyclic ketone compound and water. It is characterized by (However, in the above formula, Q ₁ is unsubstituted or represents a phenyl group or naphthyl group substituted with a group selected from the following group X, and Q ₂ is unsubstituted or
It represents a biphenylene group substituted with a group selected from the following group X, and Q ₃ represents a phenyl group that is unsubstituted or substituted with a group selected from the following group X. Group X; hydroxyl group, amino group, alkyl group, alkoxy group, halogen atom, nitro group, sulfone group)
In this way, when a nitrogen-containing heterocyclic ketone compound and a dye compound represented by the above general formula (A) are combined and incorporated into an aqueous recording liquid, recording properties, especially ejection stability, ejection response, and continuity can be improved. A practical recording liquid having excellent recording properties, clear recorded images, and water resistance, light resistance, weather resistance, and abrasion resistance can be obtained. The recording liquid of the present invention is basically prepared from a nitrogen-containing heterocyclic ketone compound, water, and a specific dye compound represented by general formula (A). As the nitrogen-containing heterocyclic ketone compound, a 5-membered ring compound such as pyrrolidone or imidazolidone is preferably used. In particular, N-methyl-2-pyrrolidone or 1,3-dimethyl-2-imidazolidinone is preferably used in the present invention in terms of versatility and properties of the resulting recording liquid. The content of these compounds is determined depending on the desired physical properties of the recording liquid, the types of other components, etc., but is usually 2% or more, preferably 2% or more based on the total weight of the recording liquid. It is in the range of 2 to 90%, more preferably 3 to 70%, particularly preferably 3 to 50%, and can take values in a fairly wide range. The water content at this time is generally 5 to 90% of the total weight of the recording liquid, depending on the content of the above compounds.
It is desirable that it be within the range of preferably 10 to 70%, more preferably 20 to 60%. The compound used as a recording agent in the present invention is represented by the above general formula, and Q ₁ , Q ₂ , and Q ₃ are -
Desirably, it is substituted with OH, _-NH2 , _-CH3 , _-OCH3 , -Cl, _-NO2 , or _-SO3Na group. Specific examples of the compound represented by general formula (A) include compounds represented by dye compound numbers 1 to 50 below. Among these dye compounds, the extreme Q ₁ , Q ₃
is a phenyl or naphthyl group having an amino group, and compounds in which Q ₂ has a biphenyl group substituted with 2 halogen atoms, a methyl group, a sulfone group of sodium salt (SO ₃ Na group), or a methoxy group are preferred. . Specifically, the dye compound number is 1, 3 to 5,
7-11, 13-15, 17, 19-22, 24-26, 28-30,
32, 34, 35, 37, 39-41, 43-47, 49-50, etc. are preferred. The content of these specific water-soluble dyes is determined depending on the composition of the liquid medium components, the characteristics required of the recording liquid (image density, etc.), but in general, it is 0.5% of the total weight of the recording liquid. ~20%, preferably 0.5-15
%, more preferably within the range of 1 to 10%. By using these water-soluble dyes in combination with the above-mentioned nitrogen-containing heterocyclic ketone compound and water, various properties as a recording liquid; ejection responsiveness and ejection stability, especially during long-term storage or after recording is stopped, can be improved. The performance, ejection stability when the environmental temperature changes, and the fixing performance on paper with a high degree of size are all improved. Further, although the recording liquid of the present invention has water and a nitrogen-containing heterocyclic ketone compound as main liquid medium components, it is also desirable to use a mixture of water and various water-soluble organic solvents. Examples of water-soluble organic solvents include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, and isobutyl alcohol.
~4 alkyl alcohols; amides such as dimethylformamide and dimethylacetamide; ketone or keto alcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; Alkylene glycols in which the alkylene group has 2 to 6 carbon atoms, such as ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1, 2, 6, hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol; glycerin ; ethylene glycol methyl ether, diethylene glycol methyl (or ethyl) ether,
Examples include lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl (or ethyl) ether. Among these many water-soluble organic solvents, polyhydric alcohols such as diethylene glycol and lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl (or ethyl) ether are preferred. 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 considered to be within the range of 50%. 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 added. For example, polyvinyl alcohol, cellulose,
Examples include viscosity modifiers such as water-soluble resins; various cationic, anionic, or nonionic surfactants; surface tension modifiers such as diethanolamine and triethanolamine; and PH modifiers using buffer solutions. To prepare a recording liquid used in a type of recording method in which the recording liquid is charged, a resistivity adjuster such as inorganic salts such as lithium chloride, ammonium chloride, and sodium chloride is used. Note that in the case of a type in which recording liquid is ejected by the action of thermal energy, thermal physical property values (eg, specific heat, coefficient of thermal expansion, thermal conductivity, etc.) may be adjusted. The invention will be explained in more detail in the following examples. Example 1 No. 17 dye 3 parts by weight diethylene glycol 30 1,3-dimethyl-2-imidazolidinone
10 〃 Ion-exchanged water 57 〃 The above components were thoroughly mixed and dissolved in a container, filtered under pressure using a Teflon (trade name) filter with a pore size of 1μ, and then degassed using a vacuum pump to form the recording liquid ( ). We investigated T ₁ to _{T 4} using the recording device shown in Figure 2 (discharge orifice diameter 65μ, piezoelectric element drive voltage 60V, frequency
3KHz), good results were obtained in both cases. (T ₁ ) Long-term storage stability of recording liquid: Even after recording liquid () was sealed in a glass container and stored at 0°C and 50°C for 6 months, no precipitation of insoluble matter was observed, and the physical properties of the liquid (viscosity, There was no change in surface tension (PH) or color tone. (T ₂ ) Ejection stability: Continuous ejection was performed for 24 hours, and stable high-quality recording was possible from beginning to end. (T ₃ ) Ejection responsiveness: Intermittent ejection every 2 seconds and ejection after one month of standing were investigated, and stable and uniform recording was obtained in both cases. (T ₄ ) Quality of recorded images: The recorded images had high density and were clear. After 3 months of exposure to room light, the density reduction rate was less than 1%, and when immersed in water for 1 minute, there was very little blurring of the image. Example 2 A recording liquid having the composition shown in the table below was prepared in the same manner as in Example 1, and T ₁ to T ₄ were examined in the same manner as in Example 1. Good results were obtained in all cases.
In Table 2, the numbers in parentheses indicate the composition ratio.

【table】

【table】

【table】

【table】 [Brief explanation of the drawing]

1 and 2 are schematic diagrams of the recording apparatus.
However, in the figure, 1...recording head, 2a...piezo vibrator, 2
b...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 ... Recording member, S ... Recording signal.

Claims (1)

[Scope of Claims] 1. A recording liquid for inkjet, characterized in that it is composed mainly of a dye compound represented by the following general formula (A) and a solvent containing at least a nitrogen-containing heterocyclic ketone compound and water. . (However, in the above formula, Q ₁ is unsubstituted or represents a phenyl group or naphthyl group substituted with a group selected from the following group X, and Q ₂ is unsubstituted or
It represents a biphenylene group substituted with a group selected from the following group X, and Q ₃ represents a phenyl group that is unsubstituted or substituted with a group selected from the following group X. group
90% of the inkjet recording liquid according to claim 1. 3. The recording liquid for an inkjet according to claim 1, wherein the nitrogen-containing heterocyclic ketone compound is a compound having a five-membered ring structure. 4 The nitrogen-containing heterocyclic ketone compound is N-methyl-2-pyrrolidone or 1,3-dimethyl-2-
The recording liquid for an inkjet according to claim 1, which is imidazolidinone. 5 Furthermore, at least one selected from polyhydric alcohols or alkyl ethers of polyhydric alcohols.
Claim 1 containing a species compound
Recording liquid for inkjet as described in .