JP3120347B2 - Recording method using aqueous recording ink composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording method using an aqueous recording ink composition for use in an ink jet printer for recording using a liquid ink.

[0002]

2. Description of the Related Art Ink jet recording inks include:
Examples thereof include those in which a coloring agent is dissolved or dispersed in an aqueous medium, and the following properties including the relationship with a recording head are generally required.

(1) The quality of printed matter is high.

(2) The storage stability of the ink is high.

(3) The printed matter has high storage stability (light fastness and water fastness).

(4) The ink has a good frequency response corresponding to the printing speed of the printing apparatus.

(5) The ink dries quickly on the recording material.

(6) No clogging of nozzles occurs during printing or when restarting after printing is interrupted.

(7) High safety, etc.

Japanese Unexamined Patent Publication (Kokai) No. Sho 59-1992 discloses a colorant such as an aqueous dye for satisfying the above various required characteristics.
JP-A-93765 and JP-A-60-243175, etc., have examined organic solvents as solvents.
475, JP-A-56-163168 and the like, additives which have been examined such as surfactants are disclosed in JP-A-56-5781,
JP-A-63-139964 and the like further study ink properties such as ink viscosity, surface tension, pH and the like are described in JP-A-53-61412, JP-A-62-116676 and the like. The effect has been seen.

[0011]

However, in using the above-mentioned conventional inks, the following three characteristics have been noticed and are being studied earnestly as characteristics strongly required at present.

[0012] (1) Development of ink and recording method for higher speed recording (2) Development of color recording ink and recording method for plain paper (3) Development of ink and recording method for realizing low cost It is.

First of all, regarding the improvement of the printing speed, most of the studies are focused on the mechanism such as the structure of the ejection head, and at present, there is little study on the ink face.

In general, as the ink viscosity decreases, the frequency response improves, but under driving conditions of 3 kHz or more, the deterioration of the ejection stability is remarkable, and the frequency response is improved while securing the ejection stability. It was difficult to improve.

Second, when performing color recording on a recording medium on which fibers are exposed, for example, plain paper such as copy paper, bond paper, or recycled paper, the amount of ink on the recording medium is smaller than that in single-color printing. As the number of inks increases, the ink bleeds along the fibers and the drying property is deteriorated. Conventionally, this problem has mainly been studied from the ink side.

Third, with respect to nozzle clogging, conventionally, a method has been employed in which the amount of a moisturizing component added to an ink composition is increased to prevent the ink from drying, and to prevent the ink from solidifying even if it is dried. . However, at the same time, the drying property and the fixing property on the recording medium are also deteriorated, and a sufficient moisturizing component for clogging cannot be added to the ink, and ink suction or a compression pump, a nozzle cap, a nozzle cleaning mechanism, etc. are added. Since reliability was ensured, it was difficult to reduce the cost as compared with a simple ink ejection system such as an impact dot system.

In order to satisfy the above characteristics, it is necessary to study both the ink composition and the recording method.

Therefore, the present invention solves such a problem, and one object of the present invention is to provide a recording method using a novel aqueous recording ink composition.

Another object of the present invention is to provide a recording method using an aqueous recording ink composition having excellent frequency response and capable of high-speed recording.

Another object of the present invention is to quickly dry a recording medium without special surface treatment such as plain paper,
An object of the present invention is to provide a recording method using an aqueous recording ink composition that gives a high-quality printed matter.

Still another object of the present invention is to use an aqueous recording ink composition which can prevent clogging, has a small number of mechanisms for ensuring reliability, and can realize a low cost recording apparatus. To provide a recording method.

[0022]

The recording method using the aqueous recording ink composition of the present invention is driven at a driving frequency of 3 kHz or more, the ink discharge nozzle resolution is set to 180 dots / inch or more, and the ink droplet is discharged from the nozzle. In a recording method of performing recording by ejecting the ink droplets and attaching the ink droplets to a recording medium, the ink contains at least a colorant, an organic solvent, and a compound represented by the following general formula, and has a surface tension at 25 ° C. Is 35 dyn / cm or less, and the viscosity at 20 ° C. is 20 mPa · sec or less.
μg or less. Further, the organic solvent contained in the ink contains an ethylene oxide group in its structure, and at least one selected from alcoholic solvents having an average molecular weight of 1000 or less, the amount of addition of which is based on the total weight of the ink. It is not less than 10% by weight.

[0023]

Embedded image

M and n are integers of 1 or more.

R is a linear alkyl ether containing at least one ethylene oxide group or propylene oxide group.

[0026]

The operation of the present invention will be described. The aqueous recording ink composition used in the present invention has a colorant for printing and a solvent for dissolving and dispersing the same as essential components, and further has an average molecular weight containing an ethylene oxide group as an additive in its structure. 1000 or less alcoholic organic solvent,
It comprises at least one silicon-based compound. The alcohol-based organic solvent having an ethylene oxide group in the structure improves the solubility of the silicon-based compound in the ink and also has excellent moisture retention, so that by adding 10% by weight or more based on the total weight of the ink, At the same time as greatly contributing to the prevention of nozzle clogging, the uniformity of the ink including the colorant is improved, so that unevenness in printing is eliminated and the hue is settled, resulting in an increased optical density. However, if the average molecular weight exceeds 1,000, the moisturizing effect is reduced, and the clogging prevention effect is also reduced.

Next, the silicon compound used in the present invention exhibits lipophilicity centering on the dimethylsiloxane group in the structure and has surface activity. Furthermore, compared to surfactants such as linear alkanes, it is liquid or amorphous even at a high molecular weight, so it shows excellent permeability and lubricity, and has less foaming, lowers the surface tension of the ink, and Improves wettability, so that quick-drying properties can be imparted. For this reason, even if the addition amount of the organic solvent is set with emphasis on nozzle clogging, quick drying property is not sacrificed.
Further, also in the ejection head, the surface tension at 25 ° C is 35 dyn / cm or less, and the viscosity at 20 ° C is 20 dyn / cm.
By setting the pressure to mPas or less, the wettability with the head constituent material is improved, the ink flow path resistance is reduced, the frequency response such as the ejection from the nozzle and the ink supply from the ink supply hole is improved, and the high-speed printing is performed. Can respond to.

Conventionally, such a low surface tension ink has been problematic in that the print quality is deteriorated due to ink bleeding on a recording medium. This is greatly improved by a recording method in which an ink ejection amount of 0.1 μg or less is ejected from a nozzle.

Hereinafter, materials that can be used in the aqueous recording ink composition used in the present invention will be described in detail.

First, as a coloring agent usable in the aqueous ink composition used in the present invention, direct dyes, acid dyes, basic dyes, food dyes, reactive dyes, disperse dyes, vat dyes,
Soluble vat dyes, reactive dyes, oil dyes, organic pigments, inorganic pigments and the like can be mentioned. The amount of the colorant to be added is determined depending on the type of the colorant, the type of the solvent component, the characteristics required for the ink, and the like, but is generally 0.2 to 20% by weight based on the total weight of the ink. , Preferably 0.5 to 10
% By weight.

As the solvent for the ink composition, low viscosity, excellent safety, easy handling,
Water is mainly used for reasons such as low cost and no odor, but ion-exchanged water is used to prevent mixing of unnecessary ions into the ink.

Examples of the alcohol-based organic solvent having an average molecular weight of 1,000 or less and having an ethylene oxide group and used as a mixture with the ion-exchanged water include straight-chains such as methanol, ethanol, propanol and butanol, and isopentyl alcohol and 3-ethyl-1-butanol. Equally branched monohydric alcohols, glycols such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol # 200, # 300, # 400, and # 600, and monoetherified and monoesterified products thereof can be used. The addition amount of these alcohol-based organic solvents may be variously considered depending on the type and characteristics required of the ink. The amount of the alcohol-based organic solvent may be 10% by weight or more based on the total weight of the ink. When this happens, the flash point of the ink as a whole also decreases, so that it is preferably 20% by weight or less from the viewpoint of safety, and in the case of a high-viscosity solvent, it is preferably 70% by weight or less in order to suppress an increase in the viscosity of the entire ink. These can be used alone or in combination.

Next, as the silicon-based compound for the ink composition that can be used in the present invention, a compound having a relatively large HLB value is desirable in order to improve water solubility.
Usually, 2 or more, more preferably 5 or more are used.
One that is commercially available and easily available is SILWE
TL-77, L-720, L-7001, L-700
2, L-7602, L7604, L-7605, L-7
607N, Y-7006, FZ-2104, FZ-21
20, FZ-2161, FZ-2162, FZ-216
4, FZ-2165, FZ-2166, FZ-2171
(Registered trademark of Nippon Unicar Co., Ltd.), etc., alone or as a mixture, and the surface tension at 25 ° C. of the ink composition is adjusted to 35 dyn / cm or less.

Usually, the amount of addition depends on the type and performance of the silicon-based compound used, but may be 0.0 to the total weight of the ink.
It is preferably from 0.01 to 5% by weight, more preferably from 0.01 to 2% by weight. Also, it can be used in combination with a normal hydrocarbon surfactant.

For the purpose of improving various properties, amides such as dimethylformamide and dimethylacetamide, ketones such as acetone and diacetone alcohol, and keto alcohols, ethers such as tetrahydrofuran, dioxane and γ-butyrolactone, glycerin,・ 2.6
-Hexanetriol such as trihydric alcohols, diethanolamine, triethanolamine, sulfolane, 2-pyrrolidone, N-methyl-2-pyrrolidone, 1.3-dimethyl-2-imidazolidinone and the like can be used. These organic solvents can be used alone or as a mixture.

Further, as a viscosity adjuster, a surface tension adjuster and a pH adjuster, proteins such as gelatin and casein; natural rubber such as gum arabic; glucoxides such as savonin; Sulfonates, natural polymers such as shellac, polyacrylates, styrene-acrylic acid copolymer salts, vinyl naphthalene-acrylic acid copolymer salts, styrene-maleic acid copolymer salts, vinyl naphthalene-maleic acid copolymers Polymer salts,
sodium salt of β-naphthalenesulfonic acid formalin condensate, anionic polymer such as polyphosphoric acid, polyvinyl alcohol, polyvinylpyrrolidone, etc., one of these,
Alternatively, two or more kinds can be used as a mixture. The amount of these additives is 0.001 to 2 with respect to the total weight of the ink.
% By weight, more preferably 0.01 to 1% by weight.

Further, benzoic acid, dichlorophen, hexachlorophen, sorbic acid, p-hydroxybenzoic acid ester, ethylenediaminetetraacetic acid (EDTA) and the like can be contained for the purpose of a fungicide, a preservative, and a rust preventive. .
Further, it may contain an antifoaming agent, urea, thiourea, ethylene urea and the like.

In the method of preparing the aqueous recording ink composition used in the present invention, in the case of a dissolving ink using a dye or the like as a coloring agent, the ink is heated to 40 ° C. to 80 ° C., and stirred, mixed with a screw or the like, and mixed. It can be easily prepared by dissolving. In addition, the dispersion method in the case of a dispersion ink using a pigment or the like is a conventionally used pigment fine dispersion method, for example, a ball mill,
Sand mill, attritor, roll mill, agitator,
This can also be easily prepared using a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, a wet jet mill, or the like.

In order to remove dust, coarse particles, and mixed matter after dissolution or dispersion, pressurization or filtration under a pressure in one or more steps using a filter, or using a centrifuge. The centrifugation is preferably performed alone or in combination with the filtration.

Finally, regarding the ink ejection device of the present invention,
A device using the vibration energy of a conventionally used piezoelectric element, a device using thermal energy generated from a heater, and the like can be used. These ink ejection devices are
It is driven at a frequency of 3 kHz or more, and ink ejection nozzles are provided at a density of 180 dots / inch or more. In order to print characters such as Chinese characters with high quality, a resolution of 180 dots / inch or more is required, and a driving frequency of 3 kHz or more is required to obtain a practical recording speed at this resolution.

In order to reduce the ink ejection amount to 0.1 μg / dot or less in such an ink ejection apparatus, the structure of the ink ejection head such as the ink ejection nozzle diameter, ink ejection flow path size, and ink supply path size must be changed. Viscosity of the ink composition,
Set in consideration of physical properties such as surface tension. Further, it can be obtained by optimizing the electrical properties such as the voltage applied to the piezoelectric element and the heater and the pulse waveform.

[0042]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. It should be noted that "%" in the text is the weight% of each component with respect to the total weight of the ink.

[0043]

Table 1 Example 1 Composition C.I. I. Direct Black 19 2% Glycerin 10% Diethylene glycol 10% FZ-2161 1% Urea 1% Ion-exchanged water 76% Mix the above ingredients, stir at 60 ° C for 2 hours, dissolve,
Pressure filtration was performed using a 0.8 μm diameter membrane filter (registered trademark of Advantech) at a pressure of ² kg / cm ² to obtain the ink of the present invention.

With respect to the ink composition thus obtained,
The surface tension at 25 ° C. was measured using an HLV-ST type surface tensiometer (Kyowa Interface Science registered trademark), and the viscosity at 20 ° C. was measured using a B-type viscometer (Tokyo Keiki registered trademark) No. 1 rotor.

The surface tension at 25 ° C. is 30.1 dy.
n / cm, the viscosity at 20 ° C. is 3.5 mPa · s
ec.

The prototype 24 was adjusted to a discharge nozzle diameter of 40 μm, a piezoelectric element drive voltage of 80 V, a drive frequency of 3 kHz, a resolution of 180 dots / inch, and an ink discharge amount of 0.1 μg.
Using a nozzle ink jet evaluator, PPC paper (Xerox Corporation registered trademark PPC paper), recycled paper (Honshu paper registered trademark Yamayuri), bond paper (Mead registered trademark Gilbert Bond 25% cotton paper), fine paper (Oji Paper registered) Solid letters, such as solid letters, were printed on a trademark OK fine paper L), and the following tests 1 to 7 were evaluated. (Test 1) Print quality evaluation by visual observation of a character print sample.

The evaluation results were classified as follows.

[0048]

[Table 2] Bleeding is not observed with the naked eye ...
・ ・ ・ ・ ・ ・ ◎ Blurring is seen but characters can be recognized.
・ ・ △ Characters cannot be recognized ...
・ ・ × (Test 2) Macbeth TR-927 type (Kol
Lomorgan's registered trademark) An optical density meter (aperture size: 4 mm) was used to evaluate the density of a solid printed portion.

The evaluation results were classified as follows.

[0050]

[Table 3] D. 1.3 or more
…… ◎ O. D. Value 1.1 or more and less than 1.3 ...
・ ・ △ O. D. Value less than 1.1
·· × (test 3) rubbing at a pressure of 100g / cm ² a solid printed portion with cotton cloth, quick-drying evaluation to investigate the time until the print dirt does not occur.

The evaluation results were classified as follows.

[0052]

[Table 4] Printed matter stain is not observed within 2 seconds ...
・ ・ ・ ・ ・ ・ ◎ No stain on printed matter is observed within 15 seconds ・ ・ ・ ・ ・ ・ ・
・ ・ △ Print stains are observed even after 30 seconds ...
× × (Test 4) Evaluation of finger touch by rubbing the printed portion of the character with a finger 5 minutes after the end of printing and visually observing the printed stain.

The evaluation results were classified as follows.

[0054]

[Table 5] No stain on printed matter is observed.
・ ・ ・ ・ ・ ・ ◎ Slight print stains occur, but characters can be distinguished.
・ ・ △ Characters cannot be distinguished due to stains on printed matter ...
·· × (Test 5) Evaluation of continuous ejection stability for investigating whether or not dots were missing during continuous printing at room temperature for 36 hours.

The evaluation results were classified as follows.

[0056]

[Table 6] Less than 10 missing dots within 36 hours
・ ・ ・ ・ ・ ・ ◎ Within 10 hours, dot missing occurs within 24 hours ・ ・ ・ ・ ・ ・
・ ・ △ 10 or more missing dots within 1 hour ・ ・ ・ ・ ・ ・ ・
×× (Test 6) The same evaluation as in Test 5 was performed with the drive frequency set to 6 kHz.

The classification of the evaluation result conforms to Test 5.

(Test 7) The same evaluation as in Test 5 was performed with the drive frequency set to 10 kHz. The classification of the evaluation result conforms to Test 5.

The results of the evaluation in Example 1 are as follows:
Met.

Example 2 In the same manner as in Example 1, Tables 2-1 to 2-
An ink composition having a composition shown as 7 was obtained. Unless otherwise indicated, numerical values in the table indicate% by weight. After the preparation of the ink, the surface tension at 25 ° C.
And the viscosity at the same time.

[0061]

[Table 7]

For the inks of Examples 2-1 to 2-7,
Tests 1 to 7 were performed as in Example 1. In each of Examples 2-1 to 2-4, the evaluation result was ◎. Example 2-5 does not contain an organic solvent having an ethylene oxide group, Example 2-6 uses an organic solvent having an average molecular weight of more than 1,000, and Example 2-7 uses an organic solvent having an average molecular weight of more than 1,000. Was less than 10% by weight with respect to the total amount of the ink, but both satisfied the surface tension and viscosity of the constitution of the present invention, and the evaluation results were all ◎.

Comparative Examples 1 to 3 Inks having the compositions shown in Table 8 were prepared in the same manner as in Example 1 to obtain ink compositions. After preparation of the ink, Tests 1 to 7 were evaluated using the same evaluator as in Example 1. Table 2 also shows the results.

[0064]

[Table 8]

As in Comparative Example 1, the ink using Neocol YSK (registered trademark of Daiichi Kogyo Seiyaku Co., Ltd.), which is an anionic surfactant, has a significant foaming of the ink and is inferior in frequency response and ejection stability. Therefore, Tests 5 to 7 showed the result of x.

As in Comparative Example 2, 1% by weight of Epan 740 (registered trademark of Daiichi Kogyo Seiyaku Co., Ltd.) was added to the surfactant, but when the surface tension did not become 35 dyn / cm or less, the ink was spread. Was insufficient, the dots were not connected, and the coverage was reduced, so that the optical density was reduced and the quick-drying property was also adversely affected. Further, insufficient wettability with the head constituent material caused dot omission and resulted in poor frequency response.

In Comparative Example 3, the viscosity was 20 mPas.
When the above was reached, the quick-drying properties of Tests 3 and 4 deteriorated, causing dot missing.

That is, the ink composition used in the present invention has a surface tension at 25 ° C. of 35 dyn / cm or less.
The viscosity at 20 ° C. must be 20 mPa · sec or less, and in order to achieve these constitutions, a silicon-based compound is used to improve ink wettability, and an average molecular weight of 1000 containing an ethylene oxide group in the structure.
It is found that one or more of the following alcohol solvents are contained, and the added amount is 10% by weight or more based on the total weight of the ink.

Example 3 The ink of Example 1 was tested using a prototype 24-nozzle ink jet evaluator having a discharge nozzle diameter of 30 μm, a piezoelectric element drive voltage of 80 V, a drive frequency of 3 kHz, a resolution of 300 dots / inch, and an ink discharge amount of 0.08 μg. When solid letters, letters and the like were printed on the same kind of paper as in Example 1, and the above Tests 1 to 7 were evaluated, all the evaluation results were ◎.

Example 4 The ink of Example 1 was used by using a prototype 48 nozzle ink jet evaluator having a discharge nozzle diameter of 25 μm, a piezoelectric element drive voltage of 80 V, a drive frequency of 3 kHz, a resolution of 360 dots / inch, and an ink discharge amount of 0.05 μg. When solid letters, letters and the like were printed on the same kind of paper as in Example 1, and the above Tests 1 to 7 were evaluated, all the evaluation results were ◎.

Comparative Example 4 The ink of Example 1 was ejected with a discharge nozzle diameter of 40 μm, a piezoelectric element driving voltage of 100 V, a driving frequency of 3 kHz, and a resolution of 360.
Prototype 48 with dot / inch and ink ejection amount 0.12μg
Using a nozzle ink jet evaluator, solid letters and the like were printed on the same type of paper as in Example 1, and the above Tests 1 to 7 were evaluated. The evaluation result was x in test 1 and ◎ in all other tests. Test 1
In particular, bleeding on copy paper and recycled paper was remarkably observed.

Comparative Example 5 The inks of Comparative Example 2 were evaluated in Tests 1 to 7 using the evaluation machine shown in Comparative Example 4. All evaluation results were x.

That is, according to the present invention, even when the ink compositions shown in Examples 1 and 2 are used, the bleeding increases as the amount of ejected ink increases, and the print quality deteriorates depending on the type of recording paper. In a printing method in which the ink is driven at a drive frequency of 3 kHz or more and the ink discharge nozzle resolution is 180 dots / inch or more, it is appropriate that the ink discharge amount per dot is 0.1 μg or less.

[0074]

According to the present invention, there is provided an effect that a recording method using a novel aqueous recording ink composition can be provided.

Further, according to the present invention, there is an effect that a recording method using an aqueous recording ink composition having excellent frequency response and capable of high-speed recording can be provided.

Further, according to the present invention, there is provided a recording method using an aqueous recording ink composition which dries quickly and gives a high quality printed matter to a recording medium such as plain paper which has no special surface treatment. Can be provided.

Further, according to the present invention, there is provided a recording method using an aqueous recording ink composition which can prevent clogging, has no mechanism in terms of a mechanism for ensuring reliability, and can realize a low cost recording apparatus. , Can be provided.

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Miharu Yoshida 3-5-5 Yamato, Suwa-shi, Nagano Seiko Epson Corporation (56) References JP-A 1-258979 (JP, A) JP-A Sho JP-A-63-315285 (JP, A) JP-A-62-232473 (JP, A) JP-A-63-139963 (JP, A) JP-A-2-55184 (JP, A) JP-A-60-173068 (JP, A A) JP-A-59-66470 (JP, A) JP-A-5-64954 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41M 5/00 B41J 2/01 B41J 2 / 205 C09D 11/00

Claims (3)

(57) [Claims] Claims: 1. A driving frequency of 3 kHz or more,
In a recording method in which an ink discharge nozzle resolution is set to 180 dots / inch or more, an ink droplet is discharged from the nozzle, and the ink droplet is attached to a recording medium to perform recording, the ink comprises at least a colorant, an organic solvent, Containing a compound represented by the following general formula, having a surface tension at 25 ° C. of 35 dyn / cm or less and a viscosity at 20 ° C. of 20 mP.
Using an aqueous recording ink composition that is a · sec or less,
A recording method using an aqueous recording ink composition, wherein an ink ejection amount per dot is 0.1 μg or less. Embedded image m and n are integers of 1 or more. R represents at least one of an ethylene oxide group and a propylene oxide group;
It is a straight chain alkyl ether containing at least one. 2. The organic solvent contained in the ink contains an ethylene oxide group in its structure and has an average molecular weight of 1
The recording method using the aqueous recording ink composition according to claim 1, wherein at least one kind is selected from alcoholic solvents of 000 or less. 3. A recording method using an aqueous recording ink composition according to claim 1, wherein the amount of the organic solvent contained in the ink is 10% by weight or more based on the total weight of the ink. .