JPH0676569B2 - Recording liquid - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel recording liquid (hereinafter referred to as ink), and in particular, the liquid is ejected from a fine ejection port (ejection orifice) provided in a recording head. The present invention relates to an ink suitable for a method of recording by ejecting as droplets.

(Prior art) A writing instrument (fountain pen
For example, a felt pen is used as an ink in which various dyes are dissolved in water or other organic solvent.

Further, in a so-called ink jet method in which ink is ejected from an ejection orifice from an ejection orifice to perform recording by vibration of a piezoelectric vibrator or electrostatic attraction due to application of a high voltage, ink in which various dyes are dissolved in water or an organic solvent is used. Is used. However, compared to general stationery inks such as fountain pens and felt pens, inkjet inks have many characteristics and require more strict conditions.

Such an ink jet system is one in which a droplet of ink, which is so-called an ink, is ejected and adhered to a recording material for recording. Such an ink has a recording agent (a dye or a pigment is used) and a liquid medium (water or various organic solvents or a mixture thereof) which dissolves or disperses the recording agent as a basic component and, if necessary, various additives. Agent has been added.

(Problems to be Solved by the Invention) Conventionally, as an ink of this type, for example, Japanese Patent Publication No. 50-8361.
Various dyes or pigments as described in JP-B No. 51-40484, JP-B No. 52-13126, JP-B No. 52-13127, and JP-A No. 50-95008 as an aqueous or non-aqueous solvent. What is dissolved or dispersed in is known. Preferred conditions for this type of ink are (1) liquid properties (viscosity, surface tension, conductivity, etc.) that match ejection conditions (driving voltage of piezoelectric element, driving frequency, shape and material of orifice, orifice diameter, etc.) (2) Stable for long-term storage, and does not cause clogging of fine ejection openings and pores. (3) Fast fixing to recording material (paper, film, etc.) Smooth dots around the dots and little bleeding (4) Vivid color tone and high density of the printed image (5) Excellent fastness such as water resistance and light resistance of the printed image (6) Do not invade ink peripheral materials (container, connecting tube, sealing material, etc.), (7) Have excellent safety such as odor, toxicity, flammability, and the like.

It is considerably difficult to satisfy the above various characteristics at the same time. The above-mentioned prior art is unsatisfactory in this respect.

Since the ink applied to the recording for such a purpose is basically composed of a dye and its liquid medium, the above-mentioned ink characteristics largely depend on the characteristics peculiar to the dye.
Therefore, selecting a dye so that the ink has the above characteristics is a very important technique in the technical field.

Thus, the present invention has been completed by, as a result of intensive studies, finding a dye suitable for an ink used for such a purpose.

DISCLOSURE OF THE INVENTION That is, according to the present invention, an ink containing a recording agent which is a component forming a recorded image and a liquid medium for dissolving or dispersing the recording agent is represented by the following general formula (A). The ink is characterized by containing at least one of the dyes represented.

(However, Q _{1 to} Q ₄ in the above formulas each represent a benzene ring or a naphthalene ring which may be substituted with a sulfonic acid group, a carboxyl group, an amino group, an anilino group or an acetylamino group, and X represents —NHCONH -, -NH- or (R ₁ and R ₂ are a hydrogen atom or a hydroxyethyl group), M is a divalent or higher valent metal, the sulfonic acid group and the carboxyl group are alkali metal atoms, ammonia and organic amines. Salted with either base. Next, the present invention will be described in more detail. In order to achieve the above-mentioned object of the present invention, the present inventor conducted a detailed study on a dye as a recording agent component of an ink, and found that a specific metal complex salt dye was used. Is suitable as an ink recording agent, particularly as an ink recording agent used in an inkjet method, and when such a specific metal complex salt dye is adopted as an ink recording agent, when it is used in an inkjet method, ejection is performed. Ink that satisfies the required properties such as liquid physical properties that match the conditions, long-term storage stability, ink fixability on the recording material, image clarity, high density images, image light resistance, water resistance, etc. It is a finding.

The dye represented by the general formula (A) used in the present invention and mainly characterizing the present invention may be any dye as long as it is included in the general formula (A).
Particularly preferable specific examples include the followings.

Exemplified compound 1 Exemplified compound 2 Exemplified compound 3 Exemplified compound 4 Exemplified compound 5 Exemplified compound 6 Exemplified compound 7 Exemplified compound 8 Exemplified compound 9 The above exemplified compounds are shown as sodium salts,
The present invention is not limited to sodium salts.

As described above, by using the specific dye represented by the general formula (A) as a recording agent for ink, the physical properties such as viscosity and surface tension are within the proper range, and the fine ejection orifice is clogged. Without giving rise to a recording image of sufficiently high density, without changing physical properties or precipitation of solids during storage, recording can be performed on various members without limiting the type of recording material, and the fixing speed An ink that gives a large image with excellent water resistance, light resistance, abrasion resistance, and resolution can be obtained.

The content of the above-mentioned dye is determined depending on the type of liquid medium component, the properties required for the ink, etc., but is generally 0.1 to 20% by weight% with respect to the total weight of the ink, preferably The range is 0.5 to 15%, and more preferably 1 to 10%. The dyes may be used alone or in combination of two or more, or other dyes such as other direct dyes and acid dyes may be used in combination with the dye as an essential component.

The solvent suitable for use in the ink of the present invention is water or a mixed solvent of water and a water-soluble organic solvent, and particularly preferable is a mixed solvent of water, a water-soluble organic solvent and a water-soluble organic solvent. As a solvent, a polyhydric alcohol having an effect of preventing ink drying is contained. Further, as the water, it is preferable to use deionized water instead of general water containing various ions. Examples of the water-soluble organic solvent used by mixing with water include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, t
ert-Butyl alcohol, isobutyl alcohol, etc. C1-C4 alkyl alcohols; amides such as dimethylformamide, dimethylacetamide; ketones or keto alcohols such as acetone, diacetone alcohol; ethers such as tetrahydrofuran, dioxane;
Polyalkylene glycols such as polyethylene glycol and polypropylene glycol; ethylene glycol,
Propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol and other alkylene groups containing 2 to 6 carbon atoms; glycerin; ethylene glycol Lower alkyl ethers of polyhydric alcohols such as methyl (or ethyl) ether, diethylene glycol methyl (or ethyl) ether and triethylene glycol monomethyl (or ethyl) ether; N-methyl-2-pyrrolidone, 1,3-dimethyl-2 -Imidazolidinone and the like. Among these many water-soluble organic solvents,
Preferred are polyhydric alcohols such as diethylene glycol and lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl (or ethyl) ether.

The content of the water-soluble organic solvent in the ink is generally 5 to 95% by weight, preferably 10 to 80% by weight, more preferably 20 to 50% by weight based on the total weight of the ink. is there.

The content of water at this time is determined in a wide range depending on the kind of the solvent component, its composition or desired properties of the ink, but is generally 10 to 90%, preferably 10% in the total weight of the ink. ˜70%, more preferably 20 to 70%.

The ink of the present invention prepared from such components has recording characteristics (signal responsiveness, droplet formation stability, ejection stability, long-term continuous recording ability, ejection after a long recording pause) by itself. (Stability) Storage stability, fixability on a recording material, light resistance of a recorded image, weather resistance, water resistance, etc. are all well balanced and excellent. In order to further improve such characteristics, various conventionally known additives may be further added and contained.

For example, viscosity adjusting agents such as polyvinyl alcohol, celluloses and water-soluble resins; various surface active agents such as cationic, anionic or nonionic surfactants, diethanolamine, triethanolamine, etc .; pH adjusting agents with buffer solutions, antifungal agents. Examples thereof include agents.

Further, in order to prepare an ink used for an ink jet type of charging the ink, a specific resistance adjusting agent such as an inorganic salt such as lithium chloride, ammonium chloride or sodium chloride is added.

When applied to an inkjet system of a type that ejects ink by the action of thermal energy, thermal physical property values (for example, specific heat, coefficient of thermal expansion, thermal conductivity, etc.) may be adjusted.

The ink of the present invention as described above is useful as a recording ink for various writing instruments, recording instruments and the like, and is particularly useful as an inkjet ink.

The case of an inkjet system will be described as a preferred example. This inkjet system may be any system as long as it can effectively separate ink from a nozzle and apply the ink to a recording material that is a range body. , The typical ones of them are, for example, IEE Balance Actions on Industry.
Applications (IEEE Trans actions on Industry
Applications) Vol, JA-13, No. 1 (February, March, 1977), Nikkei Electronics April 19, 1976, 1973
January 29, 2014 and May 6, 1974.
The methods described in these are suitable for use of the ink of the present invention, and some of them will be described. First, there is the electrostatic suction method. In this method, the nozzle and the acceleration placed several mm ahead of the nozzle are accelerated. A method in which a strong electric field is applied between the electrodes and the ink is made into particles from the nozzle, and the ink is drawn out one after another, and while the drawn ink flies between the deflection electrodes, an information signal is given to the deflection electrodes for recording, and ink particles are deflected. There is a method of ejecting ink particles according to the information signal without doing so, and any of them is effective for the ink of the present invention.

The second method is a method of forcibly ejecting minute ink particles by applying a high pressure to the ink with a small pump and mechanically vibrating the nozzle with a crystal oscillator or the like.
The ejected ink particles are charged at the same time as the ejection according to the information signal. When the charged ink particles pass between the deflection electrode plates, they are deflected according to the charge amount. As another method using this method, there is also a method called a micro dot ink jet method. In this method, ink pressure and excitation conditions are maintained at appropriate values within a certain range, and two types of ink droplets, large and small, are ejected from the nozzle tip. It is generated, and only the medium and small diameter droplets are used for recording. The feature of this method is that a small droplet group can be obtained even with a nozzle diameter as thick as the conventional one.

As a third method, there is a piezo element method. In this method, an electric signal is applied to the piezo element that uses the piezo element as a pressure means to apply to ink, instead of a mechanical means such as a pump unlike other methods. In this method, pressure is applied to the ink by causing mechanical displacement, and the ink is ejected from the nozzle.

In addition, in the method described in JP-A-54-51837, an ink jet system in which ink subjected to the action of thermal energy causes a rapid volume change, and the action force caused by this state change ejects the ink from the nozzle Can also be used effectively.

The ink of the present invention as described above, by adopting a specific metal complex salt dye as a recording agent thereof, has excellent long-term storage stability and ejection as an ink for general recording, as well as an ink particularly used for an inkjet system. A recording image having excellent recording properties such as stability and ejection response, as well as excellent ink fixability by being applied to the recording material, has excellent light resistance, water resistance, sharpness, and resolution. To give.

Next, the present invention will be described more specifically with reference to implementation encouragement.
In the text, “part” or “%” is based on weight unless otherwise specified.

Example 1 Dye of Specific Example (1) (sodium salt) 5 parts Diethylene glycol 30 parts N-methyl-2-pyrrolidone 15 parts Water 50 parts The above composition was thoroughly mixed and dissolved in a container, and a Teflon filter having a pore size of 1 μm was used. After pressure filtration, the ink of the present invention was obtained by deaeration using a vacuum pump. Using the obtained ink, a recording device having an on-demand type recording head (ejection orifice diameter 50 μm, piezo oscillator driving voltage 60 V, frequency 4 KHz) for ejecting ink with a piezo oscillator, the following (T1) ~ ( When T5) was examined, good results were obtained in all cases.

(T1) Long-term storability of ink: No negative soluble matter deposit was observed even after the ink was sealed in a glass container and stored at -30 ° C and 60 ° C for 6 months, and the physical properties and color tone of the liquid also changed. There wasn't.

(T2) Discharge stability: Continuous discharge was performed for 24 hours in each of the atmospheres at room temperature, 5 ° C., and 40 ° C., and stable high-quality recording was always possible under all conditions.

(T3) Discharge response: Intermittent discharge every 2 seconds and discharge after being left for 2 months were examined, and in both cases, there was no clogging at the tip of the orifice, and stable and uniform recording was performed.

(T4) Quality of recorded image: The recorded image was high in density and clear. The concentration rate after exposure to room light for 3 months has a decrease rate of 1% or less, and when immersed in water for 1 minute,
Image bleeding was very slight.

(T5) Fixability on various recording materials: After printing on the recording materials shown in the table below, the printed area is rubbed with a finger after 15 seconds, and image misalignment occurs.
The presence or absence of bleeding was judged. In all cases, there was no image shift or bleeding, and excellent fixability was exhibited.

Example 2 Dye of Specific Example (5) (lithium salt) 7 parts Diethylene glycol 25 parts N-methyl-2-pyrrolidone 20 parts Water 48 parts An ink of the present invention having the above composition was prepared in the same manner as in Example 1, An on-demand type multi-head that prints by applying thermal energy to the ink in the print head to generate droplets (ejection orifice diameter 35 μm, heat resistance vs. resistance value 150
(T1) to (T5) were examined in the same manner as in Example 1 using a recording apparatus having Ω, a driving voltage of 30 V and a frequency of 2 KHz), and excellent results were obtained in all the examination experiments.

Example 3 Dye of Specific Example (3) (ammonium salt) 6 parts Ethylene glycol 20 parts N-Methyl-2-pyrrolidone 10 parts Polyethylene glycol (molecular weight 300) 15 parts Water 49 parts Similar to Example 1 above composition The on-demand type multi-head for preparing the ink of the present invention and applying heat energy to the ink in the recording head to generate droplets for recording (ejection orifice diameter 35 μm, heating resistor resistance value 150
(T1) to (T5) were examined in the same manner as in Example 1 using a recording apparatus having Ω, a driving voltage of 30 V and a frequency of 2 KHz), and excellent results were obtained in all the examination experiments.

Example 4 Dye of Specific Example (9) (M = triethanolamine) 4 parts Diethylene glycol 25 parts N-methyl-2-pyrrolidone 15 parts Water 56 parts Ink of the present invention having the above composition was prepared in the same manner as in Example 1. An on-demand type multi-head that prepares and applies heat energy to the ink in the recording head to generate droplets for recording (ejection orifice diameter 35 μm, heating resistor resistance value 150
(T1) to (T5) were examined in the same manner as in Example 1 using a recording apparatus having Ω, a driving voltage of 30 V and a frequency of 2 KHz), and excellent results were obtained in all the examination experiments.

Examples 5 to 13 and Comparative Examples 1 to 4 Inks having the following compositions were prepared in the same manner as in Example 1 using the exemplified compounds 1 to 9 and the compounds for comparison 10 to 13 described below.

Exemplified compound (sodium salt) 5 parts Thiodiglycol 5 parts Glycerin 5 parts Urea 5 parts Water 80 parts These inks were filled in the recording apparatus of Example 2 and allowed to stand at room temperature.
Continuous recording was carried out for 240 hours, and evaluation was made according to the following three grades.

A: We were able to make a stable record until the end.

B: The density of the recorded image was lowered and the ink ejection was disturbed halfway.

C: Ink ejection stopped halfway.

The results are shown in the table below.

Exemplified compound 10 Exemplified compound 11 Exemplified compound 12 Exemplified compound 13 As described above, by using the ink of the present invention, (1) long-term storage stability of the liquid is good, and clogging of the ejection port is unlikely to occur.

(2) The allowance for stable ejection is wide with respect to variations in temperature and driving conditions.

(3) Fast fixing to the recording material and a clear image.

(4) The printed matter has good water resistance and light resistance.

(5) The safety of the ink is high, and the surrounding materials (container sealing material, etc.) are not damaged.

And so on.

Claims (2)

[Claims] 1. A recording liquid comprising a recording agent which is a component for forming a recorded image and a liquid medium for dissolving or dispersing the recording agent, wherein a dye represented by the following general formula (A) is used as the recording agent. A recording liquid containing at least one kind. (However, Q _{1 to} Q ₄ in the above formulas each represent a benzene ring or a naphthalene ring which may be substituted with a sulfonic acid group, a carboxyl group, an amino group, an anilino group or an acetylamino group, and X represents —NHCONH -, -NH- or (R ₁ and R ₂ are a hydrogen atom or a hydroxyethyl group), M is a divalent or higher valent metal, the sulfonic acid group and the carboxyl group are alkali metal atoms, ammonia and organic amines. Salted with either base. ) 2. A dye represented by the general formula is used in the total weight of the recording liquid.
The recording liquid according to claim (1), which is contained in a proportion of 0.1 to 20% by weight.