JPS6210272B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a recording liquid composition for an inkjet used for recording by ejecting a recording liquid. Non-impact recording methods have the advantage of generating little noise during recording, and have been actively researched recently. Among these, the inkjet recording method, which enables high-speed recording and can record on so-called plain paper without the need for special fixing processing, is an extremely powerful recording method, and has been used in various ways until now. Some methods have been devised, improved and commercialized, and others are still being worked on to put them into practical use. 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. 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 in response to the signal. In FIG. 1, 1 is a recording head, which includes a piezo vibrator 2a,
It has a diaphragm 2b, a recording liquid inlet 3, 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. In addition to the above-described devices, several types of devices are known that perform recording by causing recording liquid to fly in the form of droplets. For example, as a modification of the device shown in Fig. 1, there is a device in which the liquid chamber 4 is shaped like a nozzle and a cylindrical piezo vibrator is installed around the outer circumference (the mechanism of droplet generation in this device is , essentially the same device as shown in FIG. 1). Also known is an apparatus having a recording head similar to that shown in FIG. 1, which continuously generates droplets and uses a portion of the droplets for recording. In this device, an electric field modulated by a recording signal is applied between the discharge orifice and a charging electrode installed in the droplet flight space in front of the discharge orifice, and the discharged droplets are charged by the electrode. Ru. Further in front of the charging electrode, a deflection electrode to which a constant electric field is applied is installed, and the charged droplet is deflected to perform recording. Alternatively, there is also known an apparatus that applies a high-voltage electric field modulated by a recording signal between an ejection orifice and a charging electrode in front, and generates droplets by electrostatic force. Furthermore, an apparatus is known in which thermal energy corresponding to a recording signal is applied to the recording liquid in the chamber of a recording head, and the energy is used to generate droplets. As described above, even if it is said to be a device that performs recording by flying droplets, the method of generating droplets and the method of controlling the flying direction of droplets are quite different. Therefore, in order to perform good recording, the physical properties of the recording liquid used, such as viscosity, surface tension, and specific resistance, must be adjusted according to the method of generating droplets or the method of controlling the flying direction of droplets. required. 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 for inkjet that satisfies all of the above conditions. That is, the object is to provide a recording liquid for an inkjet that does not cause clogging of the ejection orifice, deterioration of quality during storage, or generation of precipitates, and has excellent recording performance, ejection stability, and ejection response. Another object of the present invention is to provide a recording liquid for an inkjet with excellent color tone and contrast of recorded images. Another object of the present invention is to provide a recording liquid for an inkjet in which a recorded image has excellent fixing properties, has water resistance, light resistance, weather resistance, and abrasion resistance. The present invention, which achieves the above object, provides an inkjet recording liquid mainly composed of a recording agent and a liquid medium for dissolving or dispersing the recording agent. (However, at least -OH or ^-SO3- has been introduced into the naphthyl group, and φ represents a phenyl group that is unsubstituted or substituted with at least one substituent selected from the following group. Alkyl group, alkoxy group, amino group, nitro group, hydroxy group, halogen atom, formyl group,
Sulfo base, cyclohexyl group (optionally substituted), substituted sulfamoyl group, phenyl group (optionally substituted), substituted amino group, substituted benzyloxy group, substituted phenylsulfonyl group, substituted carbamoyl group, substituted benzothiazolyl It is characterized by containing a compound represented by the following. In this way, when the compound represented by the general formula (A) is included in the recording liquid, recording properties, ejection stability, ejection response, and continuous recording properties are excellent, the recorded images are clear, and the water resistance, light resistance, A practical recording liquid having weather resistance and abrasion resistance can be obtained. The dye compound of the present invention represented by general formula (A) includes:
It contains compounds represented by the following (A-1) and (A-2). These are α- and β-substituted isomers of each other (with respect to φ-N=N-). A compound having this structure has a relatively small conjugated system (a conjugated system of π electrons is composed of a phenyl group, an azoxy group, and a naphthyl group), and therefore has a reddish color tone. Specifically, the substituents introduced into φ are:
For example, --CH ₃ , --OCH ₃ , --NH ₂ , --NO ₂ , --
OH, -Cl, -CHO, _-SO3Na , _-NHCOCH3 ,

[Formula]--SO ₂ N (C ₂ H ₅ ) ₂ ,

【formula】

【formula】

【formula】

【formula】

【formula】

【formula】

Examples include [Formula]. In addition, the naphl group has at least one -SO ₃ ^-
Or -OH group has been introduced in the compound of general formula (A) to improve the dissolution stability in a liquid medium containing water, fixability to paper as a recording material, etc., or to make the color tone clearer. Helpful. In addition to the above -SO ₃ ^- or -OH group, the naphthyl group has -NH ₂ , -NHCOCH ₃ , or

[Formula] or

[Formula] (The phenyl group may be substituted with -CH ₃ , -Cl or -NH ₂ ) etc. may be introduced, among which electron-donating groups -NH ₂ , -
_NHCOCH3 ,

【formula】

[Formula] or

[Formula] etc. are preferred. Specific examples of the compound represented by general formula (A) include compounds represented by Nos. 1 to 30 below. Among these compounds, as substituents introduced into φ, -CH ₃ , -OCH ₃ , -Cl, -NO ₂ , -
CHO, NH ₂ , ―SO ₃ Na, ―NHCOCH ₃

【formula】

【formula】

【formula】

【formula】

[Formula] Or - SO ₂ N (C ₂ H ₅ ) ₂ etc. is selected No. 1, 4, 6, 10 ~ 18, 21, 22, 24 ~
Compounds such as 29 have excellent dissolution stability in liquid media mainly composed of water, clarity of recorded images, and
It is preferable in terms of light resistance, weather resistance, etc. The recording liquid of the present invention basically has the above general formula (A).
The dye represented by is used as a recording agent, and is composed of the recording agent and a liquid medium for dissolving the recording agent. As the liquid medium used in the present invention, water or a mixed system of water and a water-soluble organic solvent is suitably employed. Specifically, water-soluble organic solvents include:
For example, methyl alcohol, ethyl alcohol, n
- Alkyl alcohol having 1 to 4 carbon atoms such as propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, isobutyl alcohol;
Amides such as dimethylformamide and dimethylacetamide; Ketones or keto alcohols such as acetone and diacetone alcohol; Ethers such as tetrahydrofuran and dioxane N-methyl-
2-pyrrolidone and the like are effective examples. When these organic solvents are used in combination with water as the main liquid medium, they are mixed and added in the required amount within a range that does not adversely affect the prepared recording liquid. In the present invention, the amount of the dye compound represented by the general formula (A) to be added depends on the desired recorded image density, the recording method of the apparatus used, the types of other components added, and the required liquid. It is determined as appropriate depending on the physical properties, etc., but it is usually 0.1 to 15 wt%, preferably 0.5 to 10 wt%, and optimally 1 to 8 wt% of the total weight of the recording liquid to be prepared. It is. When the dye represented by the general formula (A) is dissolved in an aqueous liquid medium as a recording agent, the intended object of the present invention can be effectively achieved. In other words, the signal response, stability of droplet formation, ejection stability, and flowability are extremely good, and even when recording is performed continuously for a long time, the supply speed in the flow path in the device can sufficiently follow the recording speed. In addition, it has good adhesion to a recording member, and recorded images can be easily obtained with excellent light resistance, weather resistance, water resistance, high image density, and clarity. Therefore, by using the recording liquid of the present invention, stable recording can be performed at all times, and high quality recorded images with high clarity, sufficient density, and no satellite dots can be obtained. As mentioned above, the recording liquid of the present invention is basically composed of the dye compound represented by the general formula (A) and a liquid medium, but within the scope of the effects of the present invention, A necessary amount of a conventional recording agent or a third component for adjusting the physical properties of the liquid may be added. Third components for adjusting the physical properties of the liquid include viscosity modifiers, surface tension modifiers, PH modifiers, resistivity modifiers, etc. Furthermore, wetting agents and antifungal agents can also be used to further improve the properties of the recording liquid. May be used as an additive to improve The viscosity modifier and surface tension modifier are mainly used to distribute the flow inside the device at a sufficient flow rate depending on the recording speed.
It is added to prevent the recording liquid from going around in the discharge orifice, and to prevent bleeding (spreading of the spot diameter) when applied to the recording member. As the viscosity modifier and surface tension modifier, almost all commonly known agents can be used as long as they are effective and do not adversely affect the liquid medium and recording material used. Examples of the viscosity modifier include polyvinyl alcohol, hydroxypropyl cellulose, and water-soluble acrylic resin, and examples of the surface tension modifier include anionic and nonionic surfactants. Two or more types of surface tension modifiers may be mixed as necessary within a range that does not adversely affect each other or other constituent components so as to give a desired surface tension and generate stable droplets. May be used. The pH adjuster is added in an appropriate amount to ensure the chemical stability of the prepared recording liquid, for example to prevent changes in physical properties due to long-term storage and to prevent sedimentation and aggregation of the recording agent and other components. When recording by charging droplets of recording liquid, the specific resistance acts as an important factor in the charging characteristics. In other words, in order for the recording liquid droplets to be charged so that good recording can be performed, the specific resistance value is usually 10 ^-3 ~
It is necessary to mix the recording liquid so that the resistance is 10 ¹¹ Ωcm. In the case of recording in which the recording liquid droplets do not need to be charged, the specific resistance value may be arbitrary. As the wetting agent used in the present invention, there are many effective wetting agents such as polyhydric alcohols and ethers of polyhydric alcohols commonly known in the technical field related to the present invention. In the recording liquid of the present invention, particularly preferable results can be obtained by mixing the dye compound represented by the above-mentioned general formula with a liquid medium mainly composed of water and the above-mentioned wetting agent. Examples of humectants include polyhydric alcohols such as polyethylene glycol, ethylene glycol, propylene glycol, methoxytriglycol, and glycerin; ethers of polyhydric alcohols such as ethylene glycol methyl ether and diethylene glycol methyl (or ethyl) ether; ethylene glycol, Esters of polyhydric alcohol ethers such as methyl ether acetate and diethylene glycol methyl ether acetate are suitable compounds. These wetting agents may be used alone or in combination of two or more. In the present invention, for example, a water-soluble resin polymer such as polyvinyl alcohol is added in order to obtain a film having excellent film formation properties, especially film strength when attached to a recording member. Also good. Since the recording liquid of the present invention has the various recording properties described above, it has low viscosity, surface tension, pH, etc., and when recording using charged droplets, specific resistance or thermal energy. In the case of the method of recording by utilizing the heat exchanger, the composition is adjusted so that the characteristic values such as specific heat, coefficient of thermal expansion, and thermal conductivity are within a specific range of conditions. In other words, these physical properties include the stability of droplet formation,
Since it has an important relationship with signal response and fidelity, image density, chemical stability, flowability in the flow path in the device, etc., in the present invention, this is important when preparing the recording liquid. etc., it is necessary to pay sufficient attention. In the recording liquid of the present invention, the above-mentioned physical properties preferably have values as shown in Table 1 below.
However, it is not necessary that all of the listed physical properties satisfy the numerical conditions shown in Table 1, and some of these physical properties may be changed depending on the recording characteristics required of the recording liquid of the applied recording method. It is sufficient if it takes a value that satisfies the conditions in Table 1.

[Table] *Conditions for using charged droplets As already mentioned, the recording liquid of the present invention can be used in various types of inkjet recording systems when given desired physical properties. For example, in addition to the recording device shown in FIG. 1, as shown in FIG. 2, as a modification of the device shown in FIG. A recording method in which recording is performed using an installed device, a recording method in which charged droplets are generated by continuous vibration and recorded by deflecting them, a recording method in which recording is performed by generating droplets by electrostatic attraction, Alternatively, it is used in a recording method that performs recording by applying a recording signal in the form of thermal energy to the recording liquid in the recording head to generate droplets. The present invention will be specifically explained with reference to the following examples. Example 1 Ion exchange water 62 parts by weight N-methyl-2-pyrrolidone 15 〃 No. 1 dye 3 〃 The above components were thoroughly mixed and dissolved in a container,
After pressurizing through a Teflon (trade name) filter with a pore size of 1 μm, the solution was degassed using a vacuum pump to obtain a recording liquid (2). When T ₁ to _{T 4} were investigated using the recording apparatus shown in FIG. 2 (discharge orifice diameter 60 μm, piezo vibrator drive voltage 50 V, frequency 10 KHz), 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 0°C and 40°C for 6 months, no precipitation of insoluble matter was observed, and there were no changes in the physical properties or color tone of the liquid. I was bored. T ₂ ejection stability: Continuous ejection was performed for 24 hours, and stable high-quality recording was possible from beginning to end. _T3 Ejection response: Intermittent ejection every 2 seconds and ejection after being left for one month were investigated, and in both cases stable and uniform recording was achieved. T ₄ Quality of recorded images: The recorded images had high density and clarity. 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. Examples 2 to 14 Recording liquids having the compositions shown in the table below were prepared in the same manner as in Example 1, and T ₁ to _{T 4} were investigated in the same manner as in Example 1.

【table】

【table】

[Table] When a recording experiment was conducted in the same manner as in Example 1 using these recording liquids, the storage stability, ejection performance, and recorded image quality were all excellent as in Example 1. In Example 14, dye compounds No. 12, 13, 14, 15, 17, 25, etc. were used in place of dye compound No. 29, and good results were obtained in all cases.

[Brief explanation of the drawing]

1 and 2 are schematic diagrams of the recording apparatus. However, in the figure, 1...recording head, 2a, 2
a'...piezo vibrator, 2b...diaphragm, 3...inlet,
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 It's a signal.

Claims (1)

[Scope of Claims] 1. In an inkjet recording liquid mainly composed of a recording agent and a liquid medium for dissolving or dispersing the recording agent, the general formula (A) (However, at least -OH or -SO ^- ₃ has been introduced into the naphthyl group, and φ represents a phenyl group that is unsubstituted or substituted with at least one substituent selected from the following group. Alkyl group, alkoxy group, amino group, nitro group, hydroxy group, halogen atom, formyl group,
Sulfo base, cyclohexyl group (optionally substituted), substituted sulfamoyl group, phenyl group (optionally substituted), substituted amino group, substituted benzyloxy group, substituted phenylsulfonyl group, substituted carbamoyl group, substituted benzothiazolyl A recording liquid for an inkjet, characterized by containing a compound represented by the following. 2. The recording liquid for an inkjet according to claim 1, wherein the compound represented by formula (A) is contained in an amount of 0.1 to 15% by weight based on the total weight of the recording liquid.