JPH0138830B2 - - 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. Also, in the so-called inkjet recording method, in which recording is performed by ejecting liquid in the recording head from an 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 are required to have many properties under stricter conditions. 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. This type of inkjet recording method involves flying droplets of a recording liquid called ink.
Recording is performed by attaching this 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, a recording head 1 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. 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 according to 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 piezo 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). There is also a device that continuously generates electrically charged droplets and uses some 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 transform 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. 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 part of the heat generating 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 or the method of controlling the flying direction of droplets is quite different. Therefore, in order to perform good recording, physical properties such as viscosity, surface tension, and
The value of resistivity 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 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 a chemical change, 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 recording agent that is chemically stable as a liquid medium component that is difficult to vaporize, or for a combination of a liquid medium and a recording agent 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 an attempt is made 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 that has high solubility in a liquid medium and has a bright color tone. Furthermore, in addition to the above characteristics, recording can be performed without controlling the type of recording material, high fixing speed, providing images with excellent water resistance, light resistance, abrasion resistance, and resolution, and odor. Characteristics such as the absence of 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 image fading, and when performing high-speed recording due to poor permeability,
This method has drawbacks such as contamination caused by the recording liquid and the inability to faithfully reproduce color tones due to mixing of recording liquids of different tones when forming a color image. 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 significantly or the temperature dependence of viscosity increases, making it impossible to generate droplets faithfully to the recording signal and perform recording. It disappears. 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 purpose is a recording liquid mainly composed of a recording agent and a liquid medium for dissolving or dispersing the recording agent, and is represented by the following general formula (A) or (B). It is characterized by containing at least one type of compound. (However, in the above general formula, R ₁ , R ₂ , R ₃ , R ₄ are
Each represents an alkyl group having 1 to 4 carbon atoms, and Y is -
CH ₂ CH ₂ O—or

[Formula] represents a group, and n is an integer from 1 to 30. ) Here, specific examples of the compound represented by the above general formula (A) or (B) are illustrated below. Incidentally, these compounds can be synthesized by a known synthesis method, for example, a method in which dialkyl alkanolamine is reacted with ethyleneoxide or propylene oxide. In this way, when the recording liquid contains the compound represented by the above general formula (A) or (B), it not only has excellent storage stability, versatility, and maintainability of the device, but also improves ejection stability and ejection response. Good results can also be obtained in terms of 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 is composed 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. The compound shown in A) or (B) is considered to be an essential component. 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, bentyl 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, ethyl glycol monoethyl ether acetate, and lactate ethyl propylene carbonate; polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, and glycerin; other triethanolamine, dimethyl Various types of amines such as formamide, amide systems, nitrogen-containing heterocyclic systems such as N-methyl-2-pyrrolidone and 1,3-dimethylimidazolidinone, and intramolecular esters of oxycarboxylic acids such as parerolactone and caprolactone. Examples include solvents. 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 above-mentioned compounds varies considerably depending on the type of liquid medium used, the range of target physical property values, etc., but generally the content of the above-mentioned compounds is based on the total weight of the recording liquid. , 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 as 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 thereof, but many of the conventionally known dyes and pigments are 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, pyrazolone azo, and stilbenazo. , various azo dyes of the thiazole azo type, anthrone, anthraquinone dyes consisting of anthroquinone derivatives, indigo dyes, indigoid dyes consisting of indigo and thioindigo derivatives, phthalocyanine dyes, diphenylmethane, triphenylmethane, xanthene,
Dyes such as acridine-based carbonium dyes, azine, oxazine, and thiazine-based quinone imine dyes, polymethine, 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 pigments 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 1% by weight, based on the total weight of the recording liquid.
It is best to set it in the range of 30%. 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 to 0.01μ.
It is 0.01μ, more preferably in the range of 1μ to 0.01μ.
Furthermore, it is preferable that the particle size distribution of the dispersed recording agent be as narrow as possible. The compound represented by the general formula (A) or (B) used in the present invention has a function of improving 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 improves the solubility of the recording agent in the liquid medium. Images obtained with the liquid are clear, high-contrast, and high-quality. Furthermore, this compound has properties desirable 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 becomes high, so that the liquid physical properties can be easily adjusted, and the obtained liquid medium mixture has various physical properties, especially viscosity. It has the characteristics that its temperature dependence is small, and its physical property values do not deviate significantly from the appropriate range even with slight changes in environmental conditions. Liquid medium components containing such compounds exhibit remarkable affinity for many dyes used as recording materials, are capable of dissolving a sufficient amount of dyes, and are capable of causing volatilization of the components. Since it has the advantage of being hard to clean, it does not easily generate solid content. In this way, the recording liquid of the present invention not only has excellent ejection stability, ejection response, droplet uniformity, and continuous recording performance, but also has excellent image quality, storage stability, maintainability of the device, and selection of constituent components. It also shows excellent properties in terms of the degree of freedom. 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 Chemical Industry] 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 both cases. (T ₁ ) Long-term storage stability of the recording liquid: No precipitation of insoluble matter was observed even after the recording liquid was sealed in a glass container and stored at -30℃ and 60℃ for 6 months.
There was no change in the color tone of the physical properties of the liquid. (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 concentration decrease rate after 3 months of exposure to indoor light was less than 1%, and 1% in water.
When immersed for a minute, there was very little smearing 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 the box indicate the composition ratio). All of these had excellent recording performance. In addition, an on-demand type multi-head (discharge orifice diameter 35μ, heating 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. Each of these compositions was filled into a felt pen and written on medium-quality paper [Shiro Botan (product 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】

【table】 [Brief explanation of drawings]

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... 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, 25... Recording material, S... Recording signal, 14... Liquid chamber, 15... Heat generating head, 16... Protective layer, 17... Electrode, 18... Heat generating 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 , R ₂ , R ₃ , and R ₄ each represent an alkyl group having 1 to 4 carbon atoms, and Y is -
CH ₂ CH ₂ O— or a [Formula] group, and n is an integer of 1 to 30. ) A recording liquid characterized by containing at least one compound represented by the following.