JPH0586314A - Method for ink jet recording - Google Patents

Abstract

PURPOSE:To provide the subject method which does not adversely affects the quality of a printed record when used for recording on plain paper commonly used in a business office, etc., gives the record a sufficient water resistance, and enables a high-quality printing with no problem even after an ink has been stored long. CONSTITUTION:An ink contg. a recording agent, a liq. medium in which the agent is dissolved or dispersed, and 0.1-5.0wt.% compd. of the formula (wherein two of four groups, R1 to R4, are alkyl and the rest are hydrogen) is used in ink jet recording wherein ink drops are jetted out through an orifice in response to a recording signal to record on a recording material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording method, and more specifically, it has excellent water resistance of printed matter.
An ink jet recording method capable of performing good recording such as print quality on so-called plain paper and other recording materials such as high-quality paper, neutral paper, bond paper, recycled paper, etc. used in general offices Regarding

[0002]

2. Description of the Related Art Writing instruments (fountain pens, felt-tip pens,
With regard to inks for water-based ballpoint pens and the like and ink jet inks, various compositions have been reported. In particular, the composition and physical properties of the ink have made it possible to perform good recording on plain paper such as copy paper, report paper, notebook, notepaper, bond paper, and continuous slip paper that are commonly used in offices in recent years. Detailed research and development has been carried out from various aspects such as. For example, many water-based inks for inkjet have been proposed that have achieved clogging and prevention of solidification at low temperatures.

[0003]

[Problems to be solved by the invention] However,
The water-soluble ink is inferior in water resistance to the ink of the recorded matter, and after printing, if water droplets such as rain adhere to the printed part of the recorded matter or the recorded matter is immersed in water, the printed matter will flow out, and There is a problem that the concentration of the substance decreases.
In particular, a water-based ink for ink jet for obtaining a colored image is still more preferable because a dye having a high solubility in water is used in order to form an ink having a high color saturation. In addition, water-soluble ink uses water and low boiling point solvents, and if stored for a long time, these solvents evaporate over time and the ink becomes highly viscous. There is also a problem that it becomes unsuitable for ink jet recording having a structure in which droplets are ejected, and uniform ink droplets cannot be obtained.

Therefore, an object of the present invention is to provide a printed record with sufficient water resistance without adversely affecting the print quality of the printed record when recorded on plain paper or the like used in general offices. An object of the present invention is to provide an inkjet recording method that has high performance and is capable of high-quality printing without any problem even if the ink is stored for a long period of time.

[0005]

The above object can be achieved by the present invention described below. That is, the present invention is an ink jet recording method for recording an ink on a recording material by ejecting an ink droplet from an orifice in response to a recording signal, a recording medium and a liquid medium for dissolving or dispersing the recording medium, and the following general formula (I).
The ink jet recording method is characterized by using an ink containing 0.1% or more and less than 5.0% of the compound shown by.

[Chemical 1] (However, any two of R _{1 to} R ₄ are alkyl groups, and the rest are hydrogen atoms.)

[0006]

The present inventor has conducted extensive studies on various ink compositions in order to improve the water resistance of water-soluble inks.
An ink containing a recording agent and a liquid medium in which it is dissolved or dispersed and containing a compound represented by the following general formula (I) in an amount of 0.1% to less than 5.0% is used in an inkjet recording method. In this case, the water resistance of the printed matter can be improved without impairing the printing quality, and good recording can be performed even after the ink has been stored for a long time, impairing the reliability of the inkjet recording system. The present invention has been completed by finding out that there is no.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to the preferred embodiments. Examples of the compound represented by the following general formula (I) contained in the ink used in the inkjet recording method of the present invention include 1,1 diethylurea, 1,3 diethylurea, 1,1 dimethylurea, 1,3
Dimethyl urea and the like can be mentioned.

[Chemical 1] The ratio of the compound represented by the general formula (I) in the ink is preferably 0.1% or more and less than 5.0%, more preferably 0.5 to 4.5 wt /%. ..

The recording material used in the present invention is not particularly limited, and various coloring materials such as dyes and pigments are used. In particular, various water-soluble dyes are preferable in terms of ink performance. The amount of these coloring materials used is not particularly limited, but is generally preferably in the range of 0.1 to 15% by weight, more preferably 0.1 to 10% by weight based on the total weight of the ink. %. The ink used in the present invention has a pH of 5 to 5 by adding a pH adjuster.
It is preferably adjusted to 10. The ink used in the present invention is a water-soluble organic solvent, if necessary, in addition to the above components,
Surfactants, rust preventives, antiseptics, fungicides, antioxidants,
Various additives such as an evaporation accelerator, a chelating agent, a water-soluble polymer may be added.

The liquid medium used in the present invention is preferably a mixture of water and a water-soluble organic solvent. Specific examples of the water-soluble organic solvent include, for example, amides such as dimethylformamide and dimethylacetamide; ketones such as acetone; ethers such as tetrahydrofuran and dioxane; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; Ethylene glycol, propylene glycol, butylene glycol,
Alkylene glycols having an alkylene group of 2 to 6 carbon atoms such as triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol and diethylene glycol; glycerin; ethylene glycol monomethyl (or ethyl) ether , Diethylene glycol monomethyl (or ethyl) ether,
Lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl (or ethyl) ether; N
-Methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, triethanolamine, sulfolane,
Examples thereof include dimethyl sulfoxide.

The content of the water-soluble organic solvent is generally preferably 1% to 40% by weight, more preferably 3% to 30%, based on the total weight of the ink. The water content of the ink is within the range of 30 to 95% by weight. If it is less than 30% by weight, the solubility of the coloring material is deteriorated and the viscosity of the ink is increased, which is not preferable. on the other hand,
If it is more than 95% by weight, the amount of vaporized components is too large to satisfy a sufficient fixing property.

The ink used in the present invention is particularly suitable when it is applied to an ink jet recording method of the type in which the ink is ejected due to the bubbling phenomenon of the ink due to thermal energy, the ejection becomes extremely stable, and satellite dots are generated. There is a feature that does not occur. However, in this case, a thermal property value (for example, specific heat, coefficient of thermal expansion, thermal conductivity, etc.) may be adjusted. Further, the ink used in the present invention solves the problem of water resistance of the printed matter when recorded on plain paper or the like, and at the same time, improves the matching with the inkjet head. Surface tension at 25 ° C is 30-6
8 dyne / cm, viscosity is 15 cP or less, preferably 1
It is desirable to adjust to 0 cP or less, more preferably 5 cP or less. Therefore, in order to adjust the ink to the above physical properties and solve the problem of plain paper, the amount of water contained in the ink of the present invention is 50% by weight or more and 98% by weight.
It is suitable that the content is preferably 60% by weight or more and 95% by weight or less.

The ink used in the present invention is particularly preferably used in an ink jet recording method in which droplets are ejected by the action of heat energy for recording. In the inkjet recording method of the present invention, printing is performed by applying thermal energy corresponding to a recording signal to the ink inside the chamber of the recording head, and generating droplets by the thermal energy.

An example of the head structure, which is the main part of the apparatus to which the method of the present invention is applied, is shown in FIGS. Head 13
Is a glass, ceramics, or plastic plate having a groove 14 through which ink passes, and a heating head 15 (a head is shown in the drawing, but not limited to this) used for thermal recording. can get. The heating head 15 includes a protective film 16 formed of silicon oxide or the like, aluminum electrodes 17-1 and 17-2, a heating resistor layer 18 formed of nichrome or the like, a heat storage layer 19, and a substrate 20 having good heat dissipation such as alumina. It depends on and. The ink 21 reaches the ejection orifice (fine hole) 22 and forms a meniscus 23 by the pressure P. Now electrodes 17-1, 1
When an electric signal is applied to 7-2, the area of the heating head 15 indicated by n rapidly generates heat, and the ink 2 in contact therewith
A bubble is generated at 1, the pressure causes the meniscus 23 to project, the ink 21 is ejected, the recording droplet 24 is made from the orifice 22, and the recording droplet 25 flies toward the recording material 25. FIG. 3 shows an external view of a multi-head in which many heads shown in FIG. 1 are arranged. The multi-head comprises a glass plate 27 having multi-grooves 26 and a heating head 28 similar to that described in FIG.
It is manufactured closely. 1 is a cross-sectional view of the head 13 taken along the ink flow path, and FIG. 2 is a cross section of FIG.
It is a cross section of a line.

FIG. 4 shows an example of an ink jet recording apparatus incorporating such a head. In FIG. 4, reference numeral 61 denotes a blade as a wiping member, one end of which is held by a blade holding member to become a fixed end, which is in the form of a cantilever. The blade 61 is arranged at a position adjacent to the recording area of the recording head, and in the case of this example, it is held in a protruding form in the moving path of the recording head. Reference numeral 62 denotes a cap, which is arranged at a home position adjacent to the blade 61, and has a configuration that moves in a direction perpendicular to the moving direction of the recording head and abuts the ejection port surface to perform capping. Further, 63 is an ink absorber provided adjacent to the blade 61, and like the blade 61,
The recording head is held in a protruding form in the moving path of the recording head.
The blade 61, the cap 62, and the absorber 63 constitute a discharge recovery unit 64, and the blade 61 and the absorber 6
3 removes water, dust and the like from the ink ejection port surface.

Reference numeral 65 denotes a recording head which has an ejection energy generating means and ejects ink to a recording material facing the ejection port surface where the ejection port is arranged to perform recording, and 66 is equipped with the recording head 65. It is a carriage for moving the recording head 65. The carriage 66 is slidably engaged with the guide shaft 67, and a part of the carriage 66 is connected (not shown) to a belt 69 driven by a motor 68. As a result, the carriage 66 can move along the guide shaft 67, and the recording head 65 can move the recording area and its adjacent area. Reference numeral 51 is a paper feed section for inserting a recording material, and 52 is a paper feed roller driven by a motor (not shown). With these configurations, the recording material is fed to a position facing the ejection opening surface of the recording head, and is ejected to the ejection section provided with the ejection roller 53 as the recording progresses.

In the above structure, when the recording head 65 returns to the home position after recording is completed, the cap 62 of the head recovery section 64 is retracted from the movement path of the recording head 65, but the blade 61 projects into the movement path. There is. As a result, the ejection port surface of the recording head 65 is wiped. When the cap 62 comes into contact with the ejection surface of the recording head 65 to perform capping, the cap 62 moves so as to project into the movement path of the recording head. Recording head 6
When 5 moves from the home position to the recording start position, the cap 62 and the blade 61 are at the same positions as the above-mentioned positions at the time of wiping. As a result, the ejection opening surface of the recording head 65 is wiped even during this movement. To move the recording head to the home position,
Not only at the end of recording or at the time of ejection recovery, the recording head moves to the home position adjacent to the recording area at a predetermined interval while moving in the recording area for recording, and the wiping is performed with this movement. .

[0017]

EXAMPLES Next, the present invention will be described more specifically with reference to Examples and Comparative Examples. In the text, "part" and "%" are based on weight unless otherwise specified. Examples 1 to 4, Comparative Example 1 and Comparative Example 2 The following components were mixed, thoroughly stirred and dissolved, and then a fluoropore filter having a pore size of 0.45 μm (trade name: manufactured by Sumitomo Electric Industries, Ltd.) ), And the inks of Examples and Comparative Examples of the present invention were prepared.

Ink composition of Example 1 C.I. I. Hood black 2
Part 4 ・ Glycerin
5 parts ・ Ethyl alcohol
2 parts ・ 1,1 diethyl urea
4 parts ・ Water
86 parts Ink composition of Example 2 C.I. I. Direct black 154
3 parts ・ Diethylene glycol
10 parts ・ 1,1 dimethylurea
3 parts ・ Water
84 parts Ink composition of Example 3 C.I. I. Direct black 154
5 parts ・ Diethylene glycol
10 parts ・ Isopropyl alcohol
2 parts ・ 1,3 diethyl urea
Part 1 ・ Water
79 parts Ink composition of Example 4 C.I. I. Hood black 2
Part 2 ・ Glycerin
7 parts ・ Isopropyl alcohol
3 parts ・ 1,1 diethyl urea
4 parts ・ Water
78 copies

Ink composition of Comparative Example 1 C.I. I. Direct black 154
3 parts ・ Diethylene glycol
10 parts ・ 1,1 diethylurea
10 copies of water
77 parts Ink composition of Comparative Example 2 C.I. I. Hood black 2
4 parts ・ Triethylene glycol
10 parts ・ Ethyl alcohol
2 parts ・ 1,3 diethyl urea
12 copies of water
72 parts Ink composition of Comparative Example 3 C.I. I. Direct black 154
3 parts ・ Diethylene glycol
10 parts ・ Isopropyl alcohol
4 parts ・ Water
73 parts Ink composition of Comparative Example 4 C.I. I. Hood black 2
4 parts ・ Triethylene glycol
10 parts-Urea
15 copies ・ Water
71 copies

Next, an on-demand type ink jet printer using the inks of Examples 1 to 4 and Comparative Examples 1 to 3 obtained and using a heating element as an ink discharge energy source is used as an ink jet recording apparatus. A printing test is conducted using the above to evaluate (1) water resistance, (2) frequency response, (3) printing quality, (4) clogging, (5) printing density, and (6) printing fixability. We conducted each according to the following criteria. The obtained results are shown in Table 1. The printing conditions of the above-mentioned ink jet recording apparatus are as follows: drive voltage 26 V, resistance value of heating resistor 150 Ω, frequency 4 KHz.
I went there.

[Evaluation Method and Evaluation Criteria] (1) Water Resistance After filling a predetermined ink in a printer and printing alphanumeric characters and solid portions on commercially available high-quality paper, printing is stopped,
After left for 1 hour or more, the print density is measured by Macbeth RD915 (trade name: manufactured by Macbeth). After that, the printed matter is dipped in a container filled with water for 3 minutes, left to stand and dried to measure the printed density again, and the residual rate of the printed matter density is obtained.
Water resistance was evaluated. ◯: The residual rate of printed matter density is 75% or more. X: The residual density of the printed matter is 65% or less.

(2) Frequency response The printed state of the obtained printed matter, that is, the state of scratches or white spots and the state of defective landing points such as slush and twist was visually observed and evaluated. ◯: The ink follow-up condition with respect to the frequency is almost good, and there is no blur, white spots, or defective landing point in character printing, but slight blur is observed in solid printing. Δ: No smearing or white spots are observed in character printing, but defective landing points are partially observed. Further, in solid printing, blurring and white spots are seen in about 1/3 of the whole solid printing. X: Many solid lines and white spots in solid printing, and many small lines and defective landing points in character printing.

(3) Evaluation of printing quality After printing alphanumeric characters on a commercially available high-quality paper with a printer and leaving it for 1 hour or more, the sharpness of the characters and the degree of the whisker-like bleeding generated from the characters are visually observed with a microscope. evaluated. ⊚: Characters are sharp and have no beard-like bleeding. ◯: The characters are sharp, but some beard-like bleeding occurs. Δ: Characters are not sharp. Or, there are many beard-like blurs. X: Characters are not sharp and have many beard-like blurs.

(4) Evaluation of clogging property The printer was filled with a predetermined ink and printed with alphanumeric characters continuously for 10 minutes, then the printing was stopped, the cap was put on and left for 10 days (standing condition: 60 ° C. 10 ± 5% R
After H), alphanumeric characters were printed again, and judgment was made by the number of recovery operations until the initial printing state was reproduced. ◎: Printing similar to the initial printing is possible without recovery operation. ◯: Printing similar to the initial printing is possible with 1-5 recovery operations. Δ: Printing similar to the initial printing is possible with 6 to 10 recovery operations. X: Printing similar to the initial printing is possible after 11 or more recovery operations.

(5) Evaluation of Printing Density After printing alphanumeric characters and solid portions on a commercially available high-quality paper, the printing density was measured with Macbeth RD915 (trade name: Macbeth Co., Ltd.) after standing for 1 hour or more. A: The print density was 1.35 or more. ◯: The print density was 1.30 or more and less than 1.35. Δ: The print density was 1.25 or more and less than 1.30. X: The print density was less than 1.25.

(6) Evaluation of print fixability Regarding print dryness, 5, 15, 25, and 35 were used after printing alphanumeric characters on a commercially available continuous slip paper with a printer.
After a second, it was rubbed with a filter paper (No. 2 (trade name) manufactured by Toyo Roshi Kaisha, Ltd.) and judged based on the number of seconds until the printed part was not stained (measured at 20 ± 5 ° C. and 50 ± 10% RH). ⊚: Stain is not noticeable after 5 seconds. ◯: Dirt is not noticeable after 15 seconds. Δ: Stain is not noticeable after 25 seconds. X: Stain is not noticeable after 35 seconds.

[0027]

[Table 1] Table 1 Evaluation results

[0028]

As described above, according to the ink jet recording method of the present invention, a printed matter is recorded on so-called plain paper such as high quality paper, neutral paper, bond paper and recycled paper used in general offices. The water resistance of the printed printed matter can be improved without adversely affecting the printing quality and the like. Furthermore, according to the ink jet recording method of the present invention, good printing is performed even after the ink is stored for a long period of time, and highly reliable recording can be performed without any problem as an ink jet recording system.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a head portion of an inkjet recording apparatus.

FIG. 2 is a cross-sectional view of a head portion of an inkjet recording device.

3 is an external perspective view of a head in which the head shown in FIG.

FIG. 4 is a perspective view showing an example of an inkjet recording apparatus.

[Explanation of symbols]

 61: Wiping member 62: Cap 63: Ink absorber 64: Ejection recovery section 65: Recording head 66: Carriage

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Kumiko Manafune 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (2)

[Claims] 1. An ink jet recording method for recording a recording material by ejecting ink droplets from an orifice in response to a recording signal, a recording medium, a liquid medium for dissolving or dispersing the recording medium, and a general formula (I) below. 0.1 to the indicated compound
%, And an ink containing less than 5.0% is used. [Chemical 1] (However, any two of R _{1 to} R ₄ are alkyl groups, and the rest are hydrogen atoms.) 2. The ink jet recording method according to claim 2, wherein thermal energy is applied to the ink to eject ink droplets.