JPH01126380A - Recording liquid - Google Patents

Abstract

PURPOSE:To obtain a recording liquid for ink jet recording, giving a recorded image having excellent quality especially to a plain paper, by using a dye containing a specific chemical structure unit in the molecule as a recording agent. CONSTITUTION:The objective recording liquid is produced by compounding a dye containing the chemical structure unit of formula (X is S or NH), e.g. a dye of formula II or III (S is SO3M; M is alkali metal, ammonium or organic amine) as a recording agent. The amount of the agent is preferably 1-10wt.% based on the whole ink.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a novel recording liquid (hereinafter referred to as ink), particularly an ink for writing instruments (fountain pens, felt pens, etc.) and fine ejection ports provided in a recording head. The present invention relates to an ink suitable for a so-called inkjet recording method in which recording is performed by ejecting from an ejection orifice and flying droplets.

(Prior Art) An inkjet recording method is a method of recording by causing droplets of ink, so-called ink, to fly and attaching them to a recording material. The basic components of such an ink include a recording agent (dye or pigment is used) and a liquid medium for dissolving or dispersing it (water, various organic solvents, acids, or mixtures thereof are used). Depending on the situation, various additives are added.

Preferred characteristics of the ink include (1) liquid physical properties (viscosity, surface tension, electrical conductivity, etc.) that match the ejection conditions (piezoelectric element drive voltage, drive frequency, orifice shape and material, orifice diameter, etc.); (2) It is stable for long-term storage and does not cause clogging; (3) It fixes quickly on the recording material (paper, film, etc.) and has a smooth dot periphery. Small bleeding, especially when printing on so-called plain paper that does not have a coating layer on the surface, does not cause irregular dot shapes (so-called feathering) due to uneven ink penetration speed, ( 4) The color tone of the printed image is clear and the density is high. (5) The printed image has excellent water resistance and light resistance. (7) It must be safe in terms of odor, toxicity, flammability, etc.

In particular, nozzle clogging is a very important factor from the aspect of reliability of the recording system, but it is extremely difficult to satisfy the above characteristics at the same time.

Further, since the ink used for recording for such purposes is basically composed of a recording agent and its solvent, the above-mentioned ink characteristics are largely influenced by the properties specific to the recording agent. Therefore, selecting an ink so that the ink has the above characteristics is an extremely important technique in this technical field.

(Problems to be Solved by the Invention) Therefore, an object of the present invention is to provide an ink that satisfies the above-mentioned characteristics and is capable of recording good print quality, especially on plain paper.

(°Means to solve the problem) The above objects are achieved by the present invention as described below.

In other words, the present invention relates to an ink containing a recording agent, which is a component for forming a recorded image, and a liquid medium for dissolving or dispersing this recording agent. The ink is characterized by containing at least one of the following.

(However, X in the formula is S or Nll.) (Preferred Embodiments) Next, the present invention will be explained in more detail by citing preferred embodiments.

As the recording agent used in the present invention and which mainly characterizes the present invention, any recording agent may be used as long as it includes the above chemical structural unit, but particularly preferred examples include the following: (The symbol S in the formula represents so or m, and M represents any base selected from alkali metals, ammonium, and organic amines.)

(6) ■ The ink of the present invention contains the above recording agent and a liquid medium for dissolving or dispersing the recording agent, and the liquid medium is water or a mixture of water and various organic solvents. .

Examples of water-soluble organic solvents used in combination with water include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, 5ee-butyl alcohol, tert-butyl alcohol, and isobutyl alcohol. Alkyl alcohols having 1 to 4 carbon atoms Amides such as dimethylformamide and dimethylacetamide; Ketones or keto alcohols such as acetone and diacetone alcohol; Ethers such as tetrahydrofuran and dioxane; N-methyl-2-pyrrolidone , 1.3-Dimethyl-2-imidazolidinone, etc., nitrogen-containing heterocyclic % formula % Polyalkylene gelicols such as glycol: ethylene glycol, propylene glycol, butylene gellicol, triethylene glycol, 1.2. Alkylene glycols in which the alkylene group contains 2 to 6 carbon atoms, such as 6-hexandriol, thiodiglycol, hexylene glycol, diethylene glycol: glycerin; ethylene glycol methyl (or ethyl) ether;
diethylene glycol methyl (or ethyl) ether,
Examples include lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl (or ethyl) ether.

When a mixture of water and the water-soluble organic solvent is used as a liquid medium component, the content of the water-soluble organic solvent is generally 5 to 95% by weight based on the total weight of the ink.
Preferably 10 to 80%, more preferably 20 to 5%
The range is 0%.

Further, the amount of the recording agent dissolved in the liquid medium is approximately 11 to 20%, preferably 0.5 to 15%, more preferably 1 to 10% by weight in the total amount of ink.
%. Of course, the recording agent described above can be used alone or as a mixture, and can also be used in combination with other recording agents within the range that does not impede the object of the present invention.

The ink of the present invention prepared from such components can itself improve the water resistance, light resistance, bleeding characteristics, and fixing properties of recorded images on recorded images, as well as the recording characteristics (signal response, stability of droplet formation, etc.). ,
It is well-balanced and excellent in terms of ejection stability, long-term continuous recording performance, ejection stability after long-term recording cessation), and storage stability.

In order to further improve such properties, various conventionally known additives may be added.

For example, viscosity modifiers such as polyvinyl alcohol, celluloses, and water-soluble resins; various cationic, anionic, or nonionic surfactants; surface tension modifiers such as jetanolamine and triethanolamine; pH modifiers using buffer solutions; Antifungal agents and the like can be mentioned.

In addition, in order to prepare ink used in inkjet recording methods that charge the ink, lithium chloride,
A resistivity adjuster such as inorganic salts such as ammonium chloride and sodium chloride is added.

When applied to an inkjet recording method in which ink is ejected by the action of thermal energy, thermal physical property values (e.g., specific heat, coefficient of thermal expansion, thermal conductivity, etc.)
may be adjusted.

(Functions/Effects) Inkjet ink is mainly made of a recording agent such as a dye or pigment dissolved or dispersed in a liquid medium mainly composed of water, from the viewpoint of safety. A low-volatility water-soluble organic solvent such as glycol is added as a solvent. Therefore, the various properties of the ink, particularly the water resistance of printed matter, bleeding of recorded images, fixability, etc., are largely influenced by the properties inherent to the recording material.

The recording agent used in the present invention has extremely high affinity for paper and other recording materials, and therefore has good fixing properties to the recording material, water resistance of printed matter, and bleeding resistance of recorded images. be.

Therefore, the ink of the present invention containing such a recording agent is
Not only the specially developed recording material called inkjet recording paper, but also the widely used copy paper, report paper, bond paper, slip paper, continuous slip paper, high size paper, low size paper, and ordinary paper. Since the ink of the present invention can be fully used as an ink for paper, which is widely used in households and offices, the ink of the present invention can further accelerate the spread of inkjet recording methods.

Furthermore, since the ink of the present invention sufficiently exhibits the above-mentioned effects even when its pH is around neutral, it is
It does not require the addition of a strong alkaline substance as described in Publication No. 2, is preferable in terms of safety, and is suitable for use in general homes and offices.

Furthermore, the ink of the present invention does not generate deposits on the heater even when used in an inkjet system in which ink is ejected by the action of thermal energy. In addition, physical property values such as viscosity and surface tension are within appropriate ranges,
The fine discharge orifice does not become clogged, provides a recorded image of sufficiently high density, and does not cause changes in physical properties or precipitation of solid content during storage.

Furthermore, the ink of the present invention is not only excellent as the above inkjet recording ink, but can also be used as an ink for writing instruments.

Next, the present invention will be explained in more detail with reference to Examples, Comparative Examples, and Usage Examples. In the text, parts or percentages are based on weight unless otherwise specified.

Furthermore, all sulfonic acid groups in the dye molecules are sodium salts.

Example 1 Ion exchange water (hereinafter abbreviated as water) 71% diethylene glycol 25% dye of Exemplary Compound 1 4% The above components were thoroughly mixed and dissolved in a container, and after filtering under pressure with a Teflon filter with a pore size of 1 μm, The ink of the present invention was obtained by degassing using a vacuum pump.

Example 2 Water: 77% Polyethylene glycol 300: 30% Dye of Exemplary Compound 3: 3% The above components were treated in the same manner as in Example 1 to obtain an ink of the present invention.

Example 3 Water 70% Diethylene glycol 25% Exemplary compound 6
5% of each of the above ingredients in Example 1
The ink of the present invention was prepared in the same manner as above.

Comparative Example 1 Water 70% Diethylene glycol 25% Dye having the following structure 5% The above components were treated in the same manner as in Example 1 to obtain an ink of a comparative example.

Usage Example An inkjet printer using the inks of the above Examples and Comparative Examples and using a heating element as an ink ejection energy source as an inkjet recording device (orifice size 40 x 50 μm, heater size 50 x 15
0 μm, 24 nozzles), and the following evaluations were performed (the evaluation results are shown in Table 2 below).

Long-term storage stability of Lae Biton' (T+) ink: After the ink was sealed in a glass container and stored at -30°C and 60°C for 3 months, the precipitation of insoluble matter and the characteristics and color tone of the liquid were observed.

(T2) Discharge stability: Continuous discharge was performed for 24 hours in an atmosphere of 5° C., room temperature, and 40° C., respectively.

(T3) Ejection responsiveness: Intermittent ejection for 2 seconds and ejection after being left for 2 months were performed.

(T4) Recorded image quality: Recorded image under room light
The rate of decrease in concentration after months of exposure was measured. Also, the sample was immersed in water for 1 hour and the change in concentration was measured.

In addition, the printed area was traced with a spot lighter (pink) manufactured by Pilot ■, and the degree of contamination of the printed area was observed.

(T5) Occurrence rate of feathering: Regarding the incidence of feathering, 300 dots were printed in a non-consecutive manner on the paper in Table 1 (20±5℃, 50±1O%).
After printing at RH), leave it for more than 1 hour, then use a microscope to count the number of dots that have feathered, and calculate the percentage of feathering.
was determined and evaluated.

'7 1-1 Manufacturer Canon N
P paper Copy paper Canon Watsukus Co., Ltd. 4024DP Copy paper
Xerox Co., Ltd. Eight Mar Mill Bond
Bond paper Hemmer Mill Co., Ltd. Gilbird Bond. -ri25! kff, door bond paper
Meade Co., Ltd. However, the recording material base in Table 1 above is a trade name.

γj 2- Eni and 3-m-1, TTT, -2LL Example t　　oooo.

Example 2 0 0 0 'OO Example 3 0
0000 Comparative Example 1 × × O × × ”r, :O = No precipitation of insoluble matter, no change in properties and color tone × = Precipitation of insoluble matter, increase in viscosity and change in color tone.

T2:O = stable discharge ×=Unstable discharge T3: O = stable discharge ×: Clogging occurred at the orifice tip.

T4: O = all good × = poor water resistance and marker resistance Ts: 0=10% or less ×=31% or more Patent applicant: Canon Co., Ltd. ・So 1.

Agent Patent Attorney Yoshi 1) Katsu Hiro 7:1 Shichi J

Claims (2)

[Claims] (1) In a recording liquid containing a recording agent which is a component for forming a recorded image and a liquid medium for dissolving or dispersing this recording agent, at least one kind of dye containing the following chemical structural unit in the molecule is used as the recording agent. A recording liquid characterized by containing. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (However, X in the formula is S or NH.) (2) Claim No. (2) for inkjet recording
The recording liquid described in section 1).