JP3262568B2 - 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) High quality of printed matter (2) High storage stability of ink (3) High storage stability (light fastness and water resistance) of printed matter (4) Printing speed of printing device Good frequency response of ink corresponding to

(5) The ink dries quickly on the recording material. (6) No nozzle clogging occurs during printing or when restarting after printing is interrupted.

(7) High safety, etc.

Japanese Unexamined Patent Publication No. Sho 59 (1999) discloses a study of a coloring agent such as an aqueous dye in order to satisfy 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.

[0007]

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.

[0008] (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, with respect to the improvement of the printing speed, most of the studies are mainly focused on the mechanism such as the structure of the ejection head, and at present, little studies have been made on the ink face.

In general, as the ink viscosity decreases, the frequency responsiveness improves. However, under driving conditions of 3 kHz or more, the ejection stability is significantly deteriorated. 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.

Thirdly, with respect to nozzle clogging, conventionally, there has been adopted a method of preventing the ink from drying and solidifying even if it is dried by increasing the amount of a moisturizing component added to the ink composition. . However, at the same time, the drying property and the fixing property on the recording medium deteriorate, and a sufficient moisturizing component for clogging cannot be added to the ink. 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 consider both the ink composition and the recording method.

Accordingly, the present invention is to solve 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 has a small number of mechanisms for preventing clogging and ensuring reliability and which can realize a low cost recording apparatus. To provide a recording method.

[0018]

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 in which the ink droplets are ejected to perform recording by attaching the ink droplets to a recording medium, the ink contains at least a colorant, an organic solvent, and a nonionic surfactant such as polyoxyethylene acetylene glycols, The surface tension at 25 ° C. is 35 dyn / cm or less, and the viscosity at 20 ° C. is 20 m
It is characterized by using an aqueous recording ink composition of Pa · sec or less, and an ink ejection amount per dot of 0.1 μg or less.

Further, the organic solvent contained in the ink is selected from one or more alcoholic solvents having an ethylene oxide group in its structure and having an average molecular weight of 1,000 or less. It is characterized by being at least 10% by weight based on the weight.

[0020]

The present invention will be described in further detail. The aqueous recording ink composition used in the present invention comprises, as essential components, a colorant for printing and a solvent for dissolving and dispersing the colorant. And an alcohol-based organic solvent having an average molecular weight of 1,000 or less containing an ethylene oxide group in its structure, and at least one nonionic surfactant such as polyoxyethylene acetylene glycols.
The alcohol-based organic solvent having an ethylene oxide group in the structure improves the solubility of the nonionic surfactant in the ink and has excellent moisture retention, so that it is added in an amount of 10% by weight or more based on the total weight of the ink. This greatly contributes to the prevention of nozzle clogging, and at the same time, the uniformity of the ink including the coloring agent is improved, so that unevenness in printing is eliminated, and a hue is calmed down, and as a result, the optical density is also increased. . However, the average molecular weight is 1000
If the ratio exceeds 1, the moisturizing effect is reduced, and the effect of preventing clogging is also reduced.

Next, the nonionic surfactant of polyoxyethylene acetylene glycols has less foaming and lowers the surface tension of the ink as compared with the ionic surfactant.
Since the wettability to the recording medium is improved, quick drying 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, by setting the surface tension at 25 ° C. to 35 dyn / cm or less and the viscosity at 20 ° C. to 20 mPas or less, the wettability with the head constituent material is improved, and the ink flow path resistance is reduced. Frequency response, such as ejection from nozzles and ink supply from ink supply holes, is improved, and high-speed printing can be supported.

Conventionally, such a low surface tension ink has been problematic in that the print quality is deteriorated due to ink bleeding on the 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.

[0023]

EXAMPLES The materials which can be used in the aqueous recording ink composition used in the present invention will be described in detail below.

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 alcoholic organic solvent having an ethylene oxide group and having an average molecular weight of 1,000 or less and used as a mixture with the ion-exchanged water include straight-chain solvents 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 ink as a whole. These can be used alone or in combination.

Next, polyoxyethylene acetylene glycols are used as the nonionic surfactant for the ink composition that can be used in the present invention. Specific examples of the polyoxyethylene acetylene glycols include Surfinol 104 and Surfinol 465. Polyoxyethylene acetylene glycols are added alone or in a mixture, and the surface tension of the ink composition at 25 ° C. is adjusted to 35 dyn / cm or less. Usually, the amount of addition depends on the performance of the polyoxyethylene acetylene glycol to be used, but it is 0.001 to 5% by weight based on the total weight of the ink, and 0.01
~ 2% by weight is preferred. Nonionic surfactants other than polyoxyethylene acetylene glycols, for example, ethers such as polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, esters such as polyoxyethylene fatty acid ester, and polyoxyethylene polyoxypropylene copolymer Combinations, nitrogen-containing compounds such as polyoxyethylene alkylamine ethers and fatty acid diethanolamides can be used in combination with polyoxyethylene acetylene glycols.

For the purpose of improving various properties, amides such as dimethylformamide and dimethylacetamide, ketones such as acetone and diacetone alcohol, 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 rubbers such as gum arabic; glucooxides 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.

The method of preparing the aqueous recording ink composition used in the present invention is as follows. 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.

Further, in order to remove dusts, coarse particles and mixed substances after dissolution or dispersion, pressurization or filtration under 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 discharge 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. To obtain a practical recording speed at this resolution, a driving frequency of 3 kHz or more is required.

In order to reduce the amount of ink discharged to 0.1 μg / dot or less in such an ink discharge device, the structure of the ink discharge head such as the diameter of the ink discharge nozzle, the size of the ink discharge flow path, and the size of the ink supply path 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.

Hereinafter, the present invention will be described in more detail with reference to 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.

Example 1 After mixing and dissolving the components shown in Table 1 below at 60 ° C. for 2 hours, a 2 μm / cm ² membrane filter (registered trademark of Advantech) having a diameter of 0.8 μm was used. The mixture was filtered under pressure under pressure to obtain the ink compositions 1-1 to 1-4 of the present invention. Unless otherwise indicated, numerical values in the table indicate% by weight.

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 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. Table 1 shows the evaluation results.

(Test 1) Evaluation of print quality by visual observation of a character print sample. The evaluation results were classified as follows. Bleeding is not observed with the naked eye ◎ ◎ Bleeding is seen but characters can 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. O. D. Value 1.3 or more D. Value 1.1 or more and less than 1.3. D. Value less than 1.1

(Test 3) Evaluation of quick-drying in which the solid printed portion was rubbed with a cotton cloth at a pressure of 100 g / cm ² and the time until printing stains did not occur was examined. The evaluation results were classified as follows. No printed matter stain is observed within 2 seconds ........................ No printed matter stain is observed within 15 seconds ........................ Printed matter stain is observed even after 30 seconds. Done ... ××

(Test 4) Evaluation of finger touch by rubbing the printed portion of the character with a finger 5 minutes after the completion of printing and visually observing the printed stain. The evaluation results were classified as follows. No stain on the printed matter is observed .... ◎ Slightly stained on the printed matter, but the characters can be distinguished.・ ・ ・ ×

(Test 5) Evaluation of continuous ejection stability for investigating whether or not dots are missing during continuous printing at room temperature for 36 hours. The evaluation results were classified as follows. Within 10 hours of missing dots within 36 hours ·········· Within 10 hours of missing dots within 24 hours ············· 10 times or more missing dots within 1 hour.・ ・ ・ ・ ・ ・ ・ ×

(Test 6) The same evaluation as in Test 5 was performed with the driving 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 driving frequency set to 10 kHz. The classification of the evaluation result conforms to Test 5.

[0046]

[Table 1]

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

[0048]

[Table 2]

As in Comparative Example 1, an ink using Neocol YSK (registered trademark of Daiichi Kogyo Seiyaku Co., Ltd.), which is an anionic surfactant, suffers from severe 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.

Also 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 further achieve these configurations, a nonionic surfactant, preferably, polyoxyethylene acetylene glycols is used to improve ink wettability, One or more organic solvents, preferably alcoholic solvents having an average molecular weight of 1000 or less containing an ethylene oxide group in the structure, are contained, and the added amount is 10% by weight or more based on the total weight of the ink. Can be found.

[0053]

[0054]

[0055]

[0056]

[0057]

[0058]

[0059]

[0060]

[0061]

[0062]

[0063]

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

[0065]

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, a recording method using an aqueous recording ink composition which quickly dries a recording medium such as plain paper without special surface treatment and gives a high quality printed matter, 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 for securing reliability, and can realize a low cost recording apparatus. , Can be provided.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Masaaki Itano 3-3-5 Yamato, Suwa-shi, Nagano Seiko Epson Corporation (56) References JP-A-2-55184 (JP, A) JP-A-Hei JP-A-1-258979 (JP, A) JP-A-63-139963 (JP, A) JP-A-63-162773 (JP, A) JP-A-63-315285 (JP, A) A)

Claims (3)

(57) [Claims] Claims: 1. A driving frequency of 3 kHz or more,
A recording method using a water-based recording ink composition in which the resolution of an ink discharge nozzle is set to 180 dots / inch or more, ink droplets are discharged from the nozzles, and the ink droplets adhere to a recording medium to perform recording. It contains a colorant, an organic solvent, and a nonionic surfactant such as polyoxyethylene acetylene glycol, and has a surface tension at 25 ° C. of 35 dyn / cm or less,
Recording using an aqueous recording ink composition having a viscosity at 0 ° C. of 20 mPa · sec or less and an ink ejection amount per dot of 0.1 μg or less per dot. Method. 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. .