JPS6210549B2 - - 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 an inkjet recording method in which droplets are ejected from fine ejection orifices provided in a recording head and used for recording. 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 ink for stationery such as general fountain pens and felt pens, recording liquid for ink jets requires more stringent conditions in terms of many characteristics. The inkjet recording method does not generate noise.
It enables high-speed recording or color recording on plain paper without special fixing treatment, and various types are being actively researched. 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 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 . 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 material 12. In addition to the above devices, various types of devices are known. For example, as shown in FIG.
As a modification of the figure, there is a device in which the liquid chamber 4 is shaped like a nozzle and a cylindrical piezoelectric vibrator is installed around the outer periphery (the mechanism of droplet generation in this device is essentially the same as in FIG. 1). (same as the equipment shown). In addition, there is a device that continuously generates charged droplets and uses a part 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 liquid. Devices that generate droplets 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 15
consists 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. There is. 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 part of the heating head 15 indicated by n suddenly generates heat, bubbles are generated in the ink 21 in contact with this part, and the pressure causes the meniscus 23 to is ejected and the ink 21 is ejected from the orifice 22 to form 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 made by gluing together a glass plate 27 having multi-grooves 26 and a heating head 28 similar to that described in FIG. 3-a. 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 produce a good recording liquid, biological values such as viscosity, surface tension, and specific resistance must be adjusted for the recording liquid used, depending on the method of generating droplets or the method of controlling the flying direction of droplets. A value is required. In either method, the recording liquid must not contain any solid content due to vaporization of the liquid medium components or chemical changes in the constituent components during long-term storage or cessation of recording. 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 a solvent component that does not easily vaporize, a chemically stable recording agent, or a combination of a liquid medium and recording agent that does 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. Furthermore, in addition to the above characteristics, recording can be performed without limiting the type of recording material, the fixing speed is high, and images with excellent water resistance, light resistance, abrasion resistance, and resolution can be provided. Properties such as no odor are also required. Although various formulations have been adopted for the purpose of imparting the above-mentioned characteristics to recording liquids, it is quite difficult to simultaneously satisfy these requirements. For example, in general, the permeability and fixability of a recording liquid whose main component is water are greatly influenced by the size and air permeability of the paper. When recording on paper with a high degree of size, the permeability of the recording liquid is poor, which tends to cause blurring of the image.Due to the poor permeability, when performing high-speed recording, contamination by the recording liquid may occur, or color images may not be produced. This method has drawbacks such as the inability to faithfully reproduce color tones due to mixing of recording liquids of different tones. Therefore, in order to obtain the desired printing performance, conventional water-based systems require special paper that is low in size, smooth, and difficult to obtain on the market, and is said to lack versatility as a recording material. impractical in some respects. On the other hand, non-aqueous recording liquids generally have good permeability into paper, but have drawbacks such as large bleeding, poor resolution, and low dye dissolution stability, making it impossible to obtain deep images. Conventionally, systems have been known in which only polyhydric alcohols such as ethylene glycol, diethylene glycol, and glycerin are added to prevent clogging due to solvent evaporation in orifices. However, when polyhydric alcohols are added to a sufficient extent to have a sufficient clogging prevention effect, the viscosity increases markedly or the temperature dependence of viscosity becomes large, making it difficult to generate droplets faithfully to the recording signal and perform recording. becomes impossible. In other words, the recording liquid used in this type of recording method must not only have each of its constituent components exhibit excellent properties, but also have various properties when these components coexist as a composition. Must be. Under these circumstances, there is a strong desire to develop a versatile and practical recording liquid that satisfies the above-mentioned conditions and has excellent recording properties. The present invention has been made in view of the above points, and it is an object of the present invention to obtain a recording liquid that satisfies all the necessary conditions. That is, the main object of the present invention is to obtain a recording liquid that is excellent in ejection stability, ejection response, and continuous recording performance. Another object of the present invention is to obtain a recording liquid that can easily have appropriate physical properties. Another object of the present invention is to obtain a recording liquid that is less likely to generate solid content during a storage period or during a recording suspension period. Another object of the present invention is to obtain a recording liquid which can have a wide degree of freedom in selecting constituent components and is excellent in versatility and practicality. The recording liquid of the present invention that achieves the above object includes a recording agent which is a component for forming a recorded image, and a liquid medium for dissolving or dispersing this recording agent, and has the following general formula (A). or (B). (However, in the above general formula, R ₁ is an alkyl group having 1 to 4 carbon atoms, R ₂ and R ₃ are each hydrogen or a methyl group, and n ₁ , n ₂ and n ₃ are each 1 to 30 Here, specific examples of the compounds represented by the above general formula (A) or (B) are illustrated below. These compounds can be synthesized by known synthesis methods, such as monoalkylamine. It can be synthesized by a method of reacting ethylene oxide or propylene oxide.

【table】 \
_{CH2CH2OH _}

【table】 \
(CH ₂ CHO) ₂ H
｜
_CH3
In this way, when the recording liquid contains a compound represented by the general formula (A) or (B), it not only has excellent storage stability, versatility, and maintainability of the device, but also has excellent ejection stability and
Good results can also be obtained in terms of ejection response and long-term continuous recording. Furthermore, the solubilizing ability of the recording agent is large, and a clear, high-contrast image can be provided, resulting in an extremely practical recording liquid. The recording liquid of the present invention consists of a liquid medium as a carrier for a recording agent, a recording agent for forming a recorded image, and additives added as necessary to obtain desired characteristics. In particular, the above-mentioned compounds are essential. considered to be an ingredient. In the present invention, the above-mentioned compound may be used alone as a liquid medium component, or may be mixed with water or the following non-aqueous liquid medium that has been conventionally used in the recording field related to the present invention. For example, methyl alcohol, ethyl alcohol,
n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, Sec-butyl alcohol, tert-butyl alcohol, isobutyl alcohol, pentyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol,
Alkyl alcohols having 1 to 10 carbon atoms such as nonyl alcohol, decyl alcohol, and benzyl alcohol; For example, cyclopentane, hexane, cyclohexane, heptane, octane, nonane, decane,
Aliphatic or aromatic hydrocarbon solvents represented by undecane, dodecane, tridecane, tetralin, delicane, benzene, toluene, xylene, etc.;
For example, halogenated hydrocarbon solvents such as carbon tetrachloride, trichloroethylene, tetrachloroethane, and dichlorobenzene; Ether solvents such as ethyl ether, butyl ether, ethylene glycol diethyl ether, and ethylene glycol monoethyl ether; such as acetone, methyl ethyl ketone, and methyl propyl Ketone solvents such as ketones, methyl amyl ketone, and cyclohexanone; ethyl formate, methyl acetate, ethyl acetate,
Ester solvents such as propyl acetate, butyl acetate, phenyl acetate, ethylene glycol monoethyl ether acetate, and ethyl propylene carbonate; polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, and glycerin; and other triethanolamine and dimethyl formamide. Amine type, amide type, N-methylpyrrolidone, etc.
Various solvents include nitrogen-containing heterocyclic systems such as 1,3 dimethylimidazolidinone, and intramolecular esters of oxycarboxylic acids such as valerolactone and caprolactone. These listed liquid media are appropriately selected and used so as to satisfy the compatibility with the recording agent and additives used and the above-mentioned properties as a recording liquid. Two or more types may be mixed as appropriate within the range in which a recording liquid having characteristics can be prepared. In the present invention, the content of the compound represented by the above general formula (A) or (B) varies considerably depending on the type of liquid medium used, the range of desired physical property values, etc. However, the total weight of the recording liquid is generally 5
% or more, preferably within the range of 5% to 90%. The recording agent should be selected in relation to the liquid medium and additives to prevent sedimentation or agglomeration in the room or in the recording liquid tank due to long-term storage, as well as clogging of the supply pipe and discharge orifice. used. The recording agent that can be used in the present invention is appropriately selected depending on the characteristics of the recording material to suit the recording conditions, but many of the conventionally known dyes and pigments can be used. things are valid. The dye that can be effectively used in the present invention is one that can satisfy the above-mentioned properties of the prepared recording liquid, and generally includes, for example, monoazo, polyazo, metal complex azo, piazolonazo, and stilbene azo. , various azo dyes of the thiazole azo type, anthrone, anthraquinone dyes consisting of anthroquinone derivatives, indicoid dyes consisting of indico and thioindico derivatives, phthalocyanine dyes, diphenylmethane, triphenylmethane, xanthene, acridine carbonium dyes, azine,
Dyes such as oxazine and thiazine-based quinone imine dyes, polymethine and azomethine-based methine dyes, benzoquinone and naphthoquinone dyes, naphthalimide dyes, and perinone dyes can be mentioned. These dyes are appropriately selected as desired and used after being dissolved or dispersed in the liquid medium used. Pigments that can be effectively used in the present invention include many inorganic and organic pigments. The quantitative relationship of these recording agents is 0.5% to 50%, preferably 0.5% to 40%, and more preferably 1% to 50% by weight, based on the total weight of the recording liquid.
A range of 30% is recommended. As the recording agent, it is preferable to use a recording agent that is soluble in the liquid medium, but even if the recording agent is dispersible or poorly soluble in the liquid medium, such as a pigment, it can be dissolved in the liquid medium using an appropriate dispersant. The recording agent may be used as long as the particle size of the recording agent is sufficiently small when dispersed. In this case, the particle size of the recording agent is usually 3μ to 0.01μ, preferably 2μ.
It is in the range of μ to 0.01 μ, more preferably 1 μ to 0.01 μ. Furthermore, it is preferable that the particle size distribution of the dispersed recording agent be as narrow as possible. The above-mentioned compound used in the present invention shows a movement to improve the solubility of the recording agent, especially the dye, in the liquid medium, increases the concentration of the recording agent in the recording liquid, and the images obtained with the recording liquid are clear and have high contrast. It is of high quality. Furthermore, this compound has desirable properties as a liquid medium for ink jets or recording liquids for writing instruments, such as a high boiling point, low viscosity, no odor, and low flammability and toxicity. Furthermore, it has a favorable characteristic not found in other liquid media, that is, the viscosity hardly changes from high temperature to low temperature. In terms of the effect of increasing the solubility of the recording agent, it is generally recognized that the content of the above-mentioned compounds is 1% or more based on the total weight of the recording liquid, and it is particularly effective when the content is 5% or more. Become. The recording liquid of the present invention prepared in this manner exhibits many excellent properties. That is, when the above-mentioned compound is present in the liquid medium component, the solubility with various liquid medium components increases, so that the liquid physical properties can be easily adjusted. It has the characteristics that the temperature dependence of the viscosity is small, and the physical property values do not deviate significantly from the appropriate range even with small and large fluctuations in environmental conditions. The liquid medium component containing the above-described compound exhibits a remarkable affinity for many dyes used as recording agents, and
It has the advantage of being able to dissolve a sufficient amount of dye and furthermore, it is difficult for the components to volatilize.
Hard to generate solid content. In this way, the recording liquid of the present invention not only has excellent ejection stability, ejection response, uniformity of droplets, and continuous recording performance, but also has excellent image quality, storage stability, maintainability of packaging, and composition of components. It also exhibits excellent properties in terms of freedom of selection. The recording liquid of the present invention, which has the above-mentioned components as its basic constituents, has excellent properties in itself, but various additives may be added in order to provide even more remarkable recording properties. Examples of such additives include viscosity modifiers, surface tension modifiers, resistivity modifiers, and the like. The present invention will be specifically explained with reference to the following examples. Example 1 Water Black P-200 (CI35255) [Orient Kagaku Kogyo] 5% by weight Water 60〃 Compound of Exemplification No. 1 in the specification 35〃 Each of the above components was thoroughly mixed and dissolved in a container, and a pore size of 1 μm was prepared. After filtering under pressure using a Teflon (trade name) filter, the solution was degassed using a vacuum pump to obtain a recording liquid. Using the recording liquid, a recording device having an on-demand type recording head (discharge orifice diameter 50μ, piezoelectric vibrator drive voltage 60V, frequency 4KHz) that discharges the recording liquid by a piezoelectric vibrator is used to perform T ₁ to _T5 . When we investigated the following, we obtained good results in all cases. (T ₁ ) Long-term storage stability of 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 the physical properties and color tone of the liquid did not change. There was no change. (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 every 2 seconds and ejection after being left for 2 months 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 images recorded on the recording materials listed in the first table had high density and were clear. The rate of decrease in concentration after 3 months of exposure to indoor light is 1
% or less, and when immersed in water for 1 minute, there was very little blurring of the image. (T ₅ ) Fixability on various recording materials; After 15 seconds of printing on the following recording materials, the printed area was rubbed with a finger to determine the presence or absence of image shift and bleeding. All of them exhibited excellent fixing properties with no image shift or blurring.

[Table] 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 ₅ were examined in the same manner as in Example 1 (in Table 2, ) The numbers in parentheses indicate the composition ratio). All of these had excellent recording performance. We also have an on-demand type multi-head (discharge orifice diameter 35μ,
Heat generating resistor resistance value 150Ω, drive voltage 30V, frequency
The same study as in Example 1 was conducted using the recording device shown in FIG. 4 having a frequency of 2KHz) and excellent results were obtained.

【table】

【table】

[Table] Example 3 A recording liquid composition having the composition shown in Table 3 below was prepared in the same manner as in Example 1. Separately, the following composition was similarly prepared as a comparative example. These compositions were filled into felt-tip pens and written on medium-quality paper [Shiro Botan (trade name): Honshu Paper Industries] to examine the water resistance and writing properties after removing the cap and leaving it for 24 hours. It is shown in Table 4. The recording liquid of the present invention was excellent in both water resistance and writing properties after standing.

【table】

【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)

[Claims] 1. In a recording liquid mainly composed of a recording agent and a liquid medium for dissolving or dispersing the recording agent, the general formula: Or, (However, in the above general formula, R ₁ is an alkyl group having 1 to 4 carbon atoms, R ₂ and R ₃ are each hydrogen or a methyl group, and n ₁ , n ₂ and n ₃ are each 1 to 30 A recording liquid characterized in that it contains any one of the compounds represented by: