JPS6345429B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recording liquid composition for an inkjet, which is used for recording by ejecting a recording liquid and making it fly as droplets. 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 is an extremely effective recording method that allows high-speed recording and can record on so-called plain paper without requiring any special fixing process. This type of inkjet recording method involves flying droplets of recording liquid called ink.
Recording is performed by attaching it 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 of recording liquid in response to the signal.
In FIG. 1, a recording head 1 has a piezo vibrator 2a, a vibrator 2b, an inlet 3 for recording liquid, a liquid chamber 4 in the head, and a discharge port (discharge 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 the 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 ejected from the ejection orifice 5 as a droplet 11, and the recording member 12
Recording is done on the surface of the 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 as shown in FIG. 2 in which the liquid chamber 4 is shaped like a nozzle and a cylindrical piezo vibrator 2a' is installed on the outer circumference of the liquid chamber 4 (see FIG. 2). The droplet generation mechanism is essentially the same as the device 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 front of the discharge orifice in the droplet flight space, and the discharged droplets are charged by the electrode. be done. Further ahead of the charged electrode,
A deflection electrode to which a constant electric field is applied is installed, and the charged droplets are 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 energy corresponding to a recording signal is applied to the recording liquid in a liquid chamber of a recording head, and droplets are generated by the energy. 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 a chemical change, the physical properties of the recording liquid, which were adjusted to desired values during compounding, 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 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. 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 almost no practical recording liquid that satisfies all of the above conditions has 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 inkjet which has 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. To achieve the above object, the present invention provides an inkjet recording liquid mainly composed of a recording agent and a liquid medium for dissolving or dispersing the recording agent, which has the general formula (A). (However, Q ₁ and Q ₃ are unsubstituted or a phenyl group or naphthyl group that can be substituted with at least one group shown in Group B below, and Q ₂ is unsubstituted or substituted with at least one group shown in Group C below. 1,4-phenylene group or 1,4-naphthylene group that can be
At least one of R ₁ and R ₂ is a hydroxyl group, and at least one of R ₃ and R ₄ is a sulfone group. Group B: hydroxyl group, amino group, nitro group, alkyl group, alkoxy group, halogen atom, -N
(C ₂ H ₅ ) ₂ , [Formula] Sulfone group, -NHCH ₂ CH ₂ OH, -COONa, -
It is characterized by containing a compound represented by NHCH ₂ COONa (C group: alkyl group, alkoxy group, sulfone group). In this way, when the compound represented by the general formula (A) is included in the recording liquid, it is excellent in recording performance, ejection stability, ejection response, and continuous recording property, and the recorded image is clear black and has especially good water resistance. A practical recording liquid having light resistance, weather resistance, and abrasion resistance can be obtained. In the compound represented by the general formula (A), at least one of the groups R ₁ and R ₂ introduced into the naphthylene group is an -OH group, and an -NH ₂ group may be introduced as necessary. be. Q ₁ and Q ₃ are selected from phenyl or naphthyl groups, but a substituent may be introduced into these. A compound with this basic structure has a black tone introduced in Q ₁ and Q ₃ . Preferred substituents include electron-donating substituents for the purpose of deepening and clearing the color tone of the compound, improving the dissolution stability in the liquid medium components described below, and increasing the light resistance and water resistance of the resulting recorded image. A hydrophilic group, a hydrophilic group, or other substituents are selected. Specifically, for example, -OH, _-NH2 , _-CH3 , _-OCH3 , -Cl,
−SO ₃ Na, −N(C ₂ H ₅ ) ₂ , [Formula] −NHCH ₂ CH ₂ OH, −COONa, −NHCH ₂ COONa
Alternatively, _-NO2 group may be mentioned. Among these, -OH, _-NH2 , -Cl, -
Groups such _{as NHCH2CH2OH} , -COONa or _-SO3Na are preferred. Q ₂ is either a 1,4-phenylene group or a 1,4-naphthylene group, and a -CH ₃ , -OCH ₃ or -SO ₃ Na group, etc., may be introduced into these groups. Specific examples of compounds represented by general formula (A) include:
Compounds represented by Nos. 1 to 32 are listed below. Among these many compounds, No. 1, 2,
3, 4, 5, 8, 9, 12, 14, 15, 17, 18, 21,
22, 23, 24, 25, 26, 28, 29, 30, 31, etc. are preferred, and No. 1, 2, 3, 4, 8, 9, 15, 17, 22,
23, 24, 25, 28, 29, etc. can be mentioned as particularly preferred. The recording liquid of the present invention basically uses the dye represented by the general formula (A) 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 alcohols having 1 to 4 carbon atoms such as propyl alcohol and isopropyl alcohol; 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 etc. are effective.
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. The amount of the dye compound represented by the general formula (A) to be added depends on the desired recording image quality, the recording method of the device used for recording, the types of other components to be added, and the required liquid properties. Although it is determined as appropriate depending on the
15wt%, preferably 0.5~10wt%, optimally 1~
A desirable content is 8wt%. By preparing a recording liquid using the dye represented by the general formula (A) 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 recording materials, and the recorded images are particularly excellent in light resistance, weather resistance, and water resistance, and exhibit high image density and clear black color. 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 described above, the recording liquid of the present invention has the general formula
Although it is basically composed of the dye shown in (A) and a liquid medium, a conventional recording agent and a third component for adjusting the physical properties of the liquid are required within the range that does not deviate from the effects of the present invention. A certain amount may be added. Examples of the third component 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 in the recording liquid of the present invention. It is mentioned as an additive for further improvement. The viscosity modifier and surface tension modifier are mainly designed to be able to flow through the flow path within the device at a sufficient flow rate depending on the recording speed, to prevent the recording liquid from going around the ejection orifice, and to be applied to the recording member. It is added to prevent spot bleed (spreading of spot diameter). As the viscosity modifier and surface force 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, water-soluble acrylic resin, and the like, and examples of the surface tension modifier include anionic and nonionic surfactants. Two or more of these activators may be mixed as necessary to the extent that they do not adversely affect each other or other constituent components so as to impart a desired value of surface tension to the recording liquid and ensure stable droplet ejection. You can use it as well. 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 a recording liquid, the specific resistance of the recording liquid acts as an important factor in its charging characteristics. In order to charge the droplets so that good recording can be performed, the recording liquid must be prepared so that the specific resistance value is usually 10 ^-3 to 10 ¹¹ Ωcm. In the case of recording that does not require charging droplets of the recording liquid, the specific resistance value of the recording liquid may be arbitrary. As the wetting agent used in the present invention, many polyhydric alcohols, ethers of polyhydric alcohols, etc. commonly known in the technical field related to the present invention are effective. 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 wetting agents 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 addition to the above-mentioned additives, the recording liquid used in the present invention may contain additives, such as , a water-soluble resin polymer such as polyvinyl alcohol may be added. Since the recording liquid of the present invention has the various recording properties described above, it has various properties such as viscosity, surface tension, pH, etc., and when recording using charged recording liquid droplets, specific resistance or heat. In the case of a recording method using energy, the composition is adjusted so that characteristic values such as specific heat, coefficient of thermal expansion, and thermal conductivity fall within specific condition ranges. 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. The above-mentioned physical properties of the recording liquid that can be effectively used in the present invention preferably have values as shown in Table 1 below. However, it is not necessary to satisfy the numerical conditions as listed, and some of these physical properties may meet the conditions in Table 1 depending on the recording characteristics required for the recording liquid used in the recording method adopted. It is sufficient to take a value that satisfies the following. [Table] As shown above, the recording liquid of the present invention has desired physical property values.
Used in various types of inkjet recording methods.
The present invention will be specifically explained with reference to the following examples. Example 1 Ion-exchanged water N-methyl-2-pyrrolidone No. 1 dye 77 parts by weight 20 〃 3 〃 The above components were thoroughly mixed and dissolved in a container, and filtered through a Teflon (trade name) filter with a pore size of 1μ. After pressure filtration, the recording liquid was degassed using a vacuum pump. We investigated T ₁ to _{T 4} using the recording device shown in Fig. 2 (discharge oil pipe diameter 60μ, piezo vibrator drive voltage 50V,
Frequency: 10KHz), 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 40°C for 6 months, no precipitation of insoluble substances 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, and 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 one month were investigated, and in both cases stable and uniform recording was obtained. (T ₄ ) Quality of recorded images: The recorded images had high density and were clear. The concentration decrease rate is less than 1% after being exposed to light for 3 months, and it has excellent light and weather resistance, and when immersed in water for 1 minute,
There was very little blurring in the image. Examples 2 to 14 Recording liquids having the following compositions were 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. Dye compound of 2-water ethylene glycol propylene carbonate No. 3 72 parts by weight 10 〃 15 〃 3 〃 3-water diethylene glycol ethylene glycol monomethyl ether No. 8 dye compound 67 〃 10 〃 20 〃 3 〃 4-water N,N-dimethylformamide Dye compound of propylene carbonate No. 2 71 〃 15 〃 10 〃 4 〃 5-water diethylene glycol Dye compound of propylene carbonate No. 4 61 〃 15 〃 20 〃 4 〃 6-water diethylene glycol diethylene glycol diethyl ether No. 9 dye compound 56 〃 20 〃 20 〃 4 〃 7-water N-methyl-2-pyrrolidone ethylene glycol monomethyl ether No. 15 dye compound 62 〃 20 〃 15 〃 3 〃 8 -water ethylene glycol No. 17 dye compound 71 〃 25 〃 4 〃 9 water Dye compound of diethylene glycol monoethyl ether No. 22 67 〃 30 〃 3 〃 10 Water Dye compound of ethylene glycol propylene carbonate No. 23 62 〃 15 〃 20 〃 3 〃 11 Water Diethylene glycol N-methyl-2-pyrrolidone No. 24 Dye compound 67 〃 15 〃 15 〃 3 〃 12 -water diethylene glycol No. 25 dye compound 66 〃 30 〃 4 〃 13 -water ethylene glycol propylene carbonate No. 28 dye compound 61 〃 20 〃 15 〃 4 〃 14- water diethylene glycol No. 29 dye compounds 72 〃 25 〃 3 〃 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. was.

[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 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, Q ₁ and Q ₃ are unsubstituted or a phenyl group or naphthyl group that can be substituted with at least one group shown in Group B below, and Q ₂ is unsubstituted or substituted with at least one group shown in Group C below. 1,4-phenylene group or 1,4-naphthylene group that can be
At least one of R ₁ and R ₂ is a hydroxyl group, and at least one of R ₃ and R ₄ is a sulfone group. Group B: hydroxyl group, amino group, nitro group, alkyl group, alkoxy group, halogen atom, -N
(C ₂ H ₅ ) ₂ , [Formula] Sulfone group, -NHCH ₂ CH ₂ OH, -COONa, -
A recording liquid for an inkjet, characterized in that it contains a compound represented by NHCH ₂ COONa (group C: alkyl group, alkoxy group, sulfone group). 2. The recording liquid for an inkjet according to claim 1, wherein the compound represented by the general formula (A) is contained in an amount of 0.1 to 15% by weight based on the total weight of the recording liquid.