JPH01263168A - Ink jet recording liquid - Google Patents

Abstract

PURPOSE:To obtain the title recording liquid highly dense, clear and quick in setting in typewritten letters, good in long-term storage stability, capable of giving prints of high resistance to water and light, by dissolving or dispersing C.I. Direct Black 168 as a recording agent in a liquid medium of specified composition. CONSTITUTION:The objective recording liquid can be obtained by dissolving or dispersing (I) as a recording agent, C.I. Direct Black 168 in (II) a liquid medium comprising (A) sulfolane, (B) at least one volatile solvent selected from methanol, ethanol and butanol, (C) at least one kind of hygroscopic solvent selected from glycerin, trimethylolethane and trimethylolpropane, and (D) water. This liquid is used in such a recording system as to make a recording by flying droplets delivered through a delivery port fitted on the recording head onto the surface to be recorded.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is applicable to recording materials such as paper, film, cloth, etc., especially paper commonly used in offices and schools, so-called "loaf paper". A recording liquid (
(hereinafter referred to as ink).

(Prior art and its problems) A wide variety of compositions have been proposed as inks for recording on recording materials for writing instruments, stamps, recorders, inkjet recording, etc. . Many of them are made by dissolving or dispersing various dyes in water or other organic solvents.

However, due to the uniqueness of its recording method, inkjet inks are required to meet more stringent conditions in many characteristics than inks for writing instruments, stamps, and recorders. Preferred conditions are listed below: (1) A liquid layer is always stably discharged from the fine discharge port and no clogging occurs.

(2) Even if the ink is left without a cap during a printing stop, stable ejection can be obtained immediately after the recording 111 is opened; that is, the ink near the ejection ports is difficult to dry and clogging does not occur.

(3) Able to obtain high-quality prints without irregularly shaped or irregular bleeding; (4) Fast fixation (print drying properties) on the recording material; no staining even when the printed matter is rubbed; (5) Print density is high and clear; (6) Printed matter has excellent water resistance and light resistance; (7)
(8) It has good storage stability and retains its ink performance over a long period of time, and (8) it does not damage the parts that come into contact with the ink.

''It is extremely difficult to simultaneously satisfy conditions such as those mentioned above.

The above conditions are often in a contradictory relationship with each other, and trying to satisfy one will cause harm to the other,
%l in many cases.

For example, it prevents the tip of the ejection port of the recording head from drying out! In most cases, a slow-drying solvent with a high boiling point is used, or in this case, the fixing properties (print drying properties) on the recording material will be poor, and if the printed matter is rubbed with a damp finger, etc. It gets dirty. In addition, penetrating agents such as surfactants are generally used to improve fixing properties, or in this case, amorphous or irregular bleeding occurs, resulting in blurred prints.

Furthermore, when printing on plain paper, a clear image with high contrast cannot be obtained as when printing on coated paper.

If the printing density is low, no matter how much blurring is suppressed to produce high-quality printing, the entire printed matter will look uneven and blurred, and the characteristics of quality will not be expressed. For this reason, when the content of recording material (dye) is generally increased in order to increase print density, the ejection ports tend to become clogged.

Furthermore, in order to improve the water resistance and light resistance of printed matter, direct dyes are used as recording agents. Compared to acid dyes and basic dyes, direct dyes have the advantage that they have a strong dyeing property on cellulose of paper and are difficult to bleed, making them suitable as recording agents. However, they generally have low solubility in solvents and tend to precipitate due to environmental changes, resulting in clogging of nozzles.

For the reasons mentioned above, there has not yet been a proposal in the prior art that satisfies all of the stated conditions. for example,
Japanese Unexamined Patent Publication No. 50-15622 (Japanese Patent Publication No. 56-1543)
Sulfolane disclosed in Japanese Patent Publication No. 8) has low dissolving power for water-soluble dyes, so when used alone, it can only be used for dyes with good solubility. Furthermore, when a general high boiling point solvent is used in combination to obtain the effect of preventing clogging, the printed matter on plain paper will bleed severely and the drying performance of the printed matter will also be slowed down.

Also, JP-A-58-27761, JP-A-58-27
Publication No. 762 and Japanese Patent Application Laid-Open No. 176255-1987 disclose contents similar to Japanese Patent Publication No. 15622-1980 mentioned in IF5, but in this case, the size degree is For paper with a high temperature, amorphous or irregular bleeding occurs, and printing drying properties are also insufficient.

Therefore, in the conventional inkjet recording method, the paper is treated to have good ink absorption, uniform bleeding, and clear prints with high contrast, and is specially designed for inkjet recording that has water resistance and light resistance. The problem was solved as a system by using a combination of this special paper and ink intended to prevent the tip of the ejection port of the recording head from drying out.

However, compared to such ordinary L9 paper, it is more expensive and labor intensive, and the selectivity of the paper is also limited, which is not desirable for users.

From the above two points, it is clear that ordinary paper found in offices and schools, such as notebooks, report paper, copy paper, etc.
There has been a demand for an ink that satisfies all of the above conditions for plain paper such as stationery and leaf blades.

Therefore, the object of the present invention is the required 11 as described above.
An object of the present invention is to provide an inkjet ink that satisfies all eight conditions. In other words, (1) Provide an inkjet ink that has high print density on paper, has no amorphous or irregular bleeding, has good fixing properties, has excellent drying resistance of the recording head, and has excellent storage stability. It is to be.

(Means for solving problems) The above objects are achieved by the present invention as described below.

That is, the present invention provides an ink used in a recording method in which recording is performed by flying droplets ejected from an ejection port provided in a recording head onto a recording surface, as a recording agent.
The liquid medium containing C,l Direct Black 168 and dissolving or dispersing this recording agent is at least the following (a) and (b).
), (c) and (d).

(a) sulfolane; (b) at least one volatile solvent selected from methanol, ethanol and butanol; (c) at least one hygroscopic solvent selected from glycerin, trimethylolethane and trimethylolpropane. and (d) water.

(Function) The ink of the present invention is used in a recording method in which recording is performed by making droplets ejected from the ejection jet (I) provided in the recording head fly onto the recording surface, and is incompatible with a specific recording agent. By combining it with a liquid medium of a specific composition, it is possible to print well on not only special paper but also ordinary paper such as notebooks, report paper, copy paper, letter paper, postcards, etc. be. Further, it can also be used without problems in a special recording method, for example, a method in which thermal energy corresponding to a recording signal is applied to the ink in the chamber of the recording head, and droplets are generated by the energy. still.

In the case of this method, if regular ink is used, the solid content (dye and additives) in the ink will be affected by heat during continuous printing for a long period of time, and the impurities will accumulate on the surface of the heater inside the ejection port. This often causes the ejection direction to change or ejection to fail. However, with the ink of the present invention, such inconsistencies do not occur, and stable ejection over a long period of time is possible, and printing with no fluctuation is possible.

(Preferred Embodiments) Next, the present invention will be described in more detail by citing preferred embodiments.

C11° Direct Black 168, which is used as a recording agent in the ink of the present invention, has excellent water resistance and light resistance, and is less likely to cause amorphous or irregular bleeding when printed on plain paper than other dyes. This is a dye that produces sharp, high-quality prints around the dots.

However, on the other hand, when printing a solid area (a continuous dot area obtained by driving all nozzles simultaneously), the optical density tends to decrease because the spaces between the dots are not filled with ink and white areas are formed. Therefore, it is necessary to devise ways to make the dots bleed uniformly and greatly. .

The content of the dye is determined depending on the scale of the liquid medium components, the properties required of the ink, etc., but it is generally 0.1 to 15% by weight, preferably 0.1 to 15% by weight based on the total weight of the ink. is 0
．． It is in the range of 5 to 10% by weight, more preferably 1 to 5% by weight. When the content is less than 1% by weight, the printing density is insufficient, and when it exceeds 5Ja% by weight, the degree of freedom of the liquid medium components for matching tends to become narrower.

Of course, the above dyes can be used alone or in combination with other dyes, that is, the dyes can be used as an essential component and various dyes such as other direct dyes and acid dyes can also be used in combination.

Next, the liquid medium component consisting of at least the above-mentioned components (a) to (d) used in the present invention will be explained.

First, component (a), sulfolane, has the effect of causing ejected ink droplets to smear uniformly and greatly on plain paper, and has the effect of obtaining clear prints with high print density without reducing print quality. have In addition, because the solubility of the dye is poor, it is difficult to use it alone, or when used in combination with other moisture-absorbing solvents, it has the effect of promoting the solubility of the dye, so it is not suitable for use in a mixed system. ing.

For this reason, the amount of sulfolane contained in the total weight of the ink is generally ! to 30%,
More preferably 5 to 20 layers! J1%. If the content is less than 5 IA%, the effect of increasing print density will be weak, and if it exceeds 20J[i%], amorphous or irregular bleeding will likely occur.

Next, regarding component (b), volatile solvents such as methanol, ethanol, and butanol have the effect of promoting the ability of droplets to penetrate into paper and evaporate, so they are used as fixing accelerators. effective.

Among the volatile solvents, methanol is considered dangerous if it comes into contact with [1], and butanol is recommended due to its odor problem, etc.
Ethanol is preferred. The amount of volatile G-based liquid contained is about the same amount of ink! 11, generally 0.1
to 15%, more preferred
0i[rjJ%teJ'+ru. Including 4+ F+i Ka0,
5j (If less than 1.1 d%, the permeation riL force and f generation ability will be insufficient, and if it exceeds 10T] lj 1%, the permeation ability into paper will be too pronounced, resulting in an amorphous or irregular shape. Severe bleeding occurs and print density is low.
-ru.

Next, regarding component (c), this is because the recording agent, components (a) and (b) alone are insufficient to prevent clogging. It is used for this purpose, and it is preferable that it be effective in small amounts. Among them, glycerin is most preferred in terms of its resistance to amorphous or irregular bleeding, and trimethylolethane and trimethylolpropane are preferred in terms of their effectiveness in preventing 111 clogging. The content of these substances is generally 1 to 20 ii IU 1%, more preferably 315 to 15 IU % in the total ink type M. If the content (f amount) is less than 3 weight %, the clogging prevention effect will be insufficient, and if it exceeds 15 weight %, amorphous or irregular bleeding will likely occur, and the fixing performance will also be insufficient. Next is component (d), water, which is a basic component for forming water-soluble ink, and its content TtJ is generally 1J5T of 20 to 1 ink. !jut%,
More preferably, the amount is 50 to 80%.

The ink of the present invention, which has the above-mentioned components as essential components, has high print density, clear and crystalline characters (17), and has excellent fixing properties on not only special paper but also general paper. Good quality and does not stain printed matter.

It has excellent properties such as excellent water resistance and light resistance, and good storage stability, but if necessary, it may also contain viscosity modifiers, surface tension modifiers, PH modifiers, and antifungal agents. It is also possible to add additives such as rust preventives.

The jet printing method using the ink of the present invention is as follows:
Many methods are known in the art, and any of these methods can be used with the ink of the present invention.

(Examples) The present invention will be explained in detail using the following examples and comparative examples. In the above, all "parts" indicate "parts by weight."

Example I C11, Direct Black 1683 parts Sulfolane
15 parts ethanol
5 parts glycerin
5 parts water
After sufficient stirring with the composition of Part 72, the pore size becomes 0.
The ink of the present invention was prepared by applying pressure through a 45 μm Fluorobor filter (trade name of a filter manufactured by Sumitomo Electric Gyokugyo ■) for 71 minutes. Thereafter, inks of Examples 2 to 10 as inks of the present invention and Comparative Examples 1 to ¥6 as inks of comparative examples were obtained in the same manner.

Actual Mi Example 2 C, I Direct Black 1683 parts Sulfolane 10 parts Ethanol 5 parts Chrycerin
5 parts water
77 parts Example 3 C1, Direct Black 1683 parts Sulfolane 13 parts Ethanol 5 parts Trimethylolethane 5 parts Water
74 parts Example 4 C11, Direct Black 1683 parts Sulfolane
12 parts ethanol
5 parts trimethylolpropane
5 parts water, 75 parts Example 5 C,1, Direct Black 168 4 parts sulfolane io parts ethanol
3 parts trimethylolpropane 10 parts water
73 parts fruit jJb example 6 C soil direct brush 16!1 2% sulfolane 15 parts butanol
1 part trimethylolethane
6 parts water
761M~Example 7 C1! , Direct Black 1683 parts Sulfolane
14 parts methanol
4 part glycerin
6 parts water 7
3 parts Example 8 C, 1, Direct Black 1683 parts Sulfolane
15 parts butanol
0.4 parts glycerin
4 parts ethylene glycol 5 parts water
72.6 parts Example 9 C, 1, Direct Black! 68 3 parts sulfolane 4 parts ethanol
5 part glycerin
3-part diethylene glycol
10 parts water
75 copies Example 10 C1! , Direct Black! 68 3 parts sulfolane 5 parts ethanol
1 part triethylene glycol to part water
Below 71 parts, comparative examples will be described.

Comparative Example I C, 1, Acid Black 2 3 parts Diethylene glycol 5 parts Polyethylene glycol (average molecule i1: 100) 5R Water 77 parts Comparative Example 2, C, I, Acid Black 48 3 parts Polyethylene glycol (average molecule i1: 100) 10
1 part N-methyl-2-pyrrolidone 1 part water
77 parts Comparative Example 3 C, 1, Food Black 2 3 parts Glycerin 10 parts Diethylene glycol 20 parts Water
67 parts Comparative Example 4 C,1, Direct Black 19 3 parts Glycerin 10 parts Ethylene glycol 5 parts Neugen P (nonionic surfactant, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 0.02
Part Water 81.98 parts Comparative Example 5 C, I Direct Black 1543 parts Triethanolamine 10 parts Polyethylene glycol (average molecular ffi 200) 15 parts Water 72 parts Comparative Example 6 C, I Direct Black 1683 parts Ethanol 5 parts Diethylene glycol 5 parts Ethylene Glycol 15 parts water
72 copies Usage example An on-demand type multi-head (orifice size 50 x 40 μm, Table 1 below shows the evaluation results of printing performance, ejection performance, and storage stability when printing was carried out using a recording device having a driving voltage of 30 V and a frequency of 4 to 111). The methods and conditions for each evaluation item are as follows.

(1) Print density: Print on commercially available continuous slip paper by driving all nozzles simultaneously, create batches, and print at 24i1 indoors.
After air drying for 9 days, the optical density of the batch was measured and evaluated based on the following criteria.

○: Optical density is 1.26 or more Δ: Optical density is 1.10 to 1.25
Continuous printing is performed so that the dots do not come into contact with each other.
After air drying for 4 hours, the number of dots in which amorphous or irregular bleeding occurred was counted using a microscope, and the percentage thereof was evaluated based on the following criteria.

○: 15% or less △: 16 to 40% .5
After 0 and 60 seconds, the printed area was rubbed with lens cleaning paper, and the number of seconds until the printed area became clean was measured and evaluated based on the following criteria.

○: Within 20 seconds Δ: 21 to 40 seconds x, 41 seconds or more (4) Water resistance...Pour tap water into a petri dish and let stand. The batch evaluated in the previous section (1) was gently immersed in the solution, allowed to stand for 5 minutes, dried, and the optical density was measured in the same manner as in the previous section (1).
The optical density xtoo (percentage) of the immersed surface was calculated and evaluated based on the following criteria.

O0 Optical density residual rate is 80% or more △・Optical density residual rate is 60 to 79% It was evaluated.

O: % Constantly ×: Occurrence of non-discharge or printing irregularities (6) Clogging property (adhesion recovery property)...Leave it in a constant temperature bath at 60°C for 1 month, then leave it at room temperature for 24 hours, and perform the recovery operation ( Suction operation by pumping) is printed after the second row,
Evaluation was made based on the following criteria.

O: Returns to normal printing state within 5 recovery operations △: Returns to normal printing state within 6 to 10 recovery operations ×: Non-discharge or print disturbance within 6 to 10 recovery operations (7) Storage stability ...Pour 100cc of each ink into a heat-resistant glass bottle, seal the bottle, and store in a thermostat at 60℃ for 3 hours.
After being stored for several months, it is loaded into a recording device and printed as a continuous slip form 1.
00 sheets and evaluated based on the following criteria.

O: No abnormality ×: Non-discharge, irregular printing or discoloration occurs Evaluation results of Examples and Comparative Examples Fruit’ei example 1 0000000 Example 2 0000000 Example 3 000 0 0 0 0 Example 4 0 ooooo ○ Example 5 000000 0 Example 6 0000000 Example 7 000 0000 Example 8 00Δooo.

Example 9　△　oooooo.

Example 10 △ △ oooo ○Comparative example i
xxxxxxxx Comparative Example 2 △ X △ xx Δ X Comparative Example 3
0xxxO△ O Comparative example 4 X Δ Δ oxxx Comparative example 5 △ △ × o × △ X Comparative example 6
xo △ oox.

(Effects) As explained above, by using the ink of the present invention, (1.) Clear, high-quality prints with high print density can be obtained on plain paper.

(2) Fast fixation (print drying) and does not stain even if the printed matter is rubbed.

(3) The long-term storage stability of the ink is good, and stable ejection can be obtained at all times.

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

(5) The print head is difficult to dry, and even if the printing apparatus is left unused for a long period of time, stable IU ejection can be achieved from when printing started.

Because of these advantages, the ink of the present invention is suitable as an inkjet ink.

Patent applicant: Canon Co., Ltd. Agent: Patent Attorney Yoshi 1) Hiroshi Katsuki

Claims (1)

[Claims] (1) In a recording liquid used in a recording method in which recording is performed by flying droplets ejected from an ejection port provided in a recording head onto a recording surface, C.I. I. An inkjet recording liquid containing Direct Black 168, characterized in that a liquid medium in which this recording agent is dissolved or dispersed comprises at least the following components (a), (b), (c), and (d). (a) Sulfolane; (b) at least one volatile solvent selected from methanol, ethanol and butanol; (c) at least one hygroscopic solvent selected from glycerin, trimethylolethane and trimethylolpropane. and (d) water.