JPH0564954A - Recording method using water-color ink composition for use in recording - Google Patents

Abstract

PURPOSE:To provide a recording method using water-color ink composition for use in recording wherein high frequency response, high speed printing, and high printing quality are provided and further clogging is prevented and mechanism for ensuring reliability is not required and hence a recording device of low cost can be provided. CONSTITUTION:Recording is performed under conditions that drive frequency is 3kHz or more and resolving power of ink delivery nozzle is 180 dots/inch or more and ink droplets is delivered from a nozzle to attach the droplets to a recording object. The ink contains at least a coloring agent, organic solvent, and nonionic surface-active agent and a water-color ink composition for use in recording having surface tension of 35dyn/cm or less and viscosity at 20 deg.C of 20mPa.sec or less is used, wherein delivery quantity of ink per dot is 0.1mug or less.

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 an ink jet printer which records using a liquid ink.

[0002]

2. Description of the Related Art As an ink jet recording ink,
Examples thereof include those obtained by dissolving or dispersing a colorant in an aqueous medium, and the following characteristics including the relationship with the recording head are generally required.

(1) High quality of printed matter (2) High storage stability of ink (3) High preservation of printed matter (light resistance and water resistance) (4) Printing speed of printing device Corresponding to the ink frequency response is good.

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

(7) High safety, etc.

In order to satisfy the above-mentioned various required characteristics, a colorant such as an aqueous dye has been studied in the past.
-93765, JP-A-60-243175, and the like, an organic solvent as a solvent is examined in JP-A-56-149.
475, JP-A-56-163168, etc., the additives examined such as surfactants are disclosed in JP-A-56-5781,
Further, in JP-A-63-139964 and the like, further examinations of ink physical properties such as ink viscosity, surface tension, and pH are described in JP-A-53-61412, JP-A-62-116676 and the like. The effect is seen.

[0007]

However, in using the above-mentioned conventional ink, the following three points are noticed and studied intensively as the characteristics which are strongly demanded at present.

That is, (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 cost reduction Is.

First of all, regarding the improvement of the printing speed, most of the studies are focused on the mechanical aspects such as the structure of the ejection head, and the present situation is that the studies on the ink side have not been made so much.

Generally, as the ink viscosity decreases, the frequency response improves. However, under the driving condition of 3 kHz or more, the ejection stability deteriorates remarkably, and the frequency response can be improved while ensuring the ejection stability. It was difficult to improve.

Secondly, when color recording is performed on a recording medium having exposed fibers, for example, plain paper such as copy paper, bond paper, and recycled paper, the amount of ink on the recording medium is higher than that of monochromatic printing. Since the amount of ink increases, the ink bleeds along the fibers and the deterioration of the drying property becomes a problem. Regarding this problem, conventionally, the study has been mainly focused on the ink surface.

Thirdly, regarding the nozzle clogging, conventionally, a method has been taken to prevent the ink from drying and to prevent the ink from solidifying even if it is dried by increasing the addition amount of the moisturizing component in the ink composition. .. However, at the same time, the drying property and fixing property on the recording medium are also deteriorated, and a moisturizing component sufficient for clogging cannot be added to the ink. Since reliability was ensured, cost reduction was difficult compared to a simple ink ejection system such as an impact dot system.

As described above, in order to satisfy the above-mentioned characteristics, it is necessary to study both the ink composition and the recording method.

Therefore, the present invention solves such a problem, and one of the objects thereof 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,
It is an object of the present invention 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 a water-based recording ink composition which can prevent clogging and has a large number of mechanisms in order to secure reliability and can realize cost reduction of a recording apparatus. To provide the recording method that was used.

[0018]

A recording method using the water-based recording ink composition of the present invention is driven at a driving frequency of 3 kHz or more, the ink ejection nozzle resolution is 180 dots / inch or more, and ink droplets are discharged from the nozzle. In a recording method of recording by ejecting and depositing the ink droplets on a recording medium, the ink contains at least a colorant, an organic solvent, and a nonionic surfactant, and has a surface tension at 25 ° C. of 35 dyn. / Cm or less and a viscosity at 20 ° C. of 20 mPa · sec or less, an aqueous recording ink composition is used, and the ink discharge amount per dot is 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 the structure and having an average molecular weight of 1,000 or less. It is characterized by being 10% by weight or more based on the weight.

[0020]

The present invention will be described in more detail. The aqueous recording ink composition used in the present invention comprises a colorant for printing and a solvent for dissolving and dispersing the colorant as essential components, and further an additive. As an alcoholic organic solvent containing an ethylene oxide group in its structure and having an average molecular weight of 1,000 or less, and at least one nonionic surfactant. The alcohol-based organic solvent having an ethylene oxide group in its structure improves the solubility of the nonionic surfactant in the ink and also has excellent moisturizing properties, and therefore 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, improves the uniformity of the ink, including the colorant, so that there is no unevenness in printing, giving a calm hue impression.
As a result, the optical density also increases. However, when the average molecular weight exceeds 1,000, the moisturizing effect is lowered and the clogging preventing effect is also lowered.

Next, the nonionic surfactant has less foaming than the ionic surfactant, lowers the surface tension of the ink, and improves the wettability with respect to the recording medium, so that quick drying property can be imparted. Therefore, even if the amount of the organic solvent added is set with emphasis on the nozzle clogging, the quick drying property is not sacrificed. Furthermore, 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 also in the ejection head, 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 recording 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. However, the resolution of the ink ejection nozzle is set to 180 dots / inch or more, and This is greatly improved by a recording method in which ink droplets having an ink discharge amount of 0.1 μg or less are discharged from nozzles.

[0023]

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

First, as the colorant which can be used 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 addition amount of these colorants is determined depending on the type of colorant, the type of solvent component, the properties required for the ink, etc., but generally 0.2 to 20% by weight based on the total weight of the ink. , Preferably 0.5 to 10
It is set in the range of wt%.

The solvent for the ink composition has a low viscosity, is excellent in safety, and is easy to handle.
Water is mainly used for reasons such as low cost and no odor. However, ion-exchanged water is used to prevent unwanted ions from being mixed in the ink.

Examples of alcohol organic solvents having an ethylene oxide group and having an average molecular weight of 1000 or less, which are used by mixing with the ion-exchanged water, include linear chains such as methanol, ethanol, propanol and butanol, and isopentyl alcohol, 3-ethyl-1-butanol. Equibranched monohydric alcohols, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycols such as polyethylene glycol # 200, # 300, # 400, and # 600, and their monoether and monoester products can be used. The amount of these alcohol-based organic solvents to be added may vary depending on the type and characteristics required for the ink, and may be 10% by weight or more based on the total weight of the ink, but when adding a solvent with a low flash point, a high concentration is required. In that case, the flash point of the ink as a whole also decreases, so from the viewpoint of safety, it is preferably 20% by weight or less, and in the case of a highly viscous solvent, 70% by weight or less is preferable in order to suppress an increase in the viscosity of the entire ink. These may be used alone or in combination.

Next, as nonionic surfactants for the ink composition which can be used in the present invention, ethers such as polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether and esters such as polyoxyethylene fatty acid ester are used. Examples thereof include nitrogen-containing compounds such as polyoxyethylene polyoxypropylene copolymers, polyoxyethylene acetylene glycols, polyoxyethylene alkylamine ethers and fatty acid diethanolamides. These nonionic surfactants are added alone or in admixture to adjust the surface tension at 25 ° C. of the ink composition to 35 dyn / cm or less. Usually, the addition amount is 0.001 to 5% by weight, and more preferably 0.01 to 2% by weight, based on the total weight of the ink, although it depends on the type and performance of the nonionic surfactant used.

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, 1・ 2.6
-Hexanetriol and other trihydric alcohols, diethanolamine, triethanolamine, sulfolane, 2-pyrrolidone, N-methyl-2-pyrrolidone, 1.3-dimethyl-2-imidazolidinone and the like can be added to the ink before use. These organic solvents can also be used alone or in combination.

Further, as viscosity adjusting agents, surface tension adjusting agents and pH adjusting agents, proteins such as gelatin and casein, natural rubber such as gum arabic, glucoxides such as savonine, cellulose derivatives such as methylcellulose, carboxymethylcellulose and hydroxymethylcellulose, lignin. Natural polymers such as sulfonates and shellac, polyacrylic acid salts, styrene-acrylic acid copolymer salts, vinylnaphthalene-acrylic acid copolymer salts, styrene-maleic acid copolymer salts, vinylnaphthalene-maleic acid copolymers Polymer salt,
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 mixed and used. The amount of these additives added is 0.001 to 2 with respect to the total weight of the ink.
Weight% is preferable, and 0.01 to 1 weight% is more preferable.

Further, benzoic acid, dichlorophen, hexachlorophen, sorbic acid, p-hydroxybenzoic acid ester, ethylenediaminetetraacetic acid (EDTA) and the like can be contained for the purpose of antifungal agent, antiseptic agent and rust inhibitor. ..
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 solution type ink using a dye as a colorant, it is heated to 40 ° C. to 80 ° C. and stirred and mixed with a screw or the like. It can be easily prepared by dissolving. In the case of a dispersion type ink using a pigment or the like, the dispersion method is a pigment fine dispersion method which has been conventionally used, for example, a ball mill,
Sand mill, attritor, roll mill, agitator,
This can also be easily produced by a Henschel mixer, colloid mill, ultrasonic homogenizer, pearl mill, wet jet mill, or the like.

Further, in order to remove dusts, coarse particles, and blended substances after dissolution or dispersion, pressurization using a filter or vacuum filtration treatment is performed in one or more steps, or a centrifuge is used. It is preferable to perform the centrifugal separation treatment alone or in combination with the filtration treatment.

Finally, regarding the ink ejection device of the present invention,
It is possible to use one that utilizes the vibration energy of a piezoelectric element that has been conventionally used, one that utilizes the heat energy generated from a heater, and the like. These ink ejection devices
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. To print high-quality characters such as Chinese characters, 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 with this resolution.

In order to reduce the ink discharge amount to 0.1 μg / dot or less in such an ink discharge device, the structure of the ink discharge head such as the ink discharge nozzle diameter, the ink discharge passage size, the ink supply passage size, etc. Viscosity of the ink composition,
Set in consideration of physical properties such as surface tension. Further, it can be obtained by electrically optimizing the voltage applied to the piezoelectric element and the heater, the pulse waveform and the like.

The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples. In the description,% means the weight% of each component with respect to the total weight of the ink.

Example 1 Composition C.I. I. Direct Black 19 2% Glycerin 10% Diethylene glycol 10% Neugen ET135 (Daiichi Kogyo Seiyaku Kogyo) 1% Urea 1% Ion-exchanged water 76% The above components are mixed and stirred at 60 ° C. for 2 hours to dissolve,
Using a 0.8 μm diameter membrane filter (registered trademark of Advantech), pressure filtration was performed 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 tension meter (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, viscosity at 20 ° C. is 3.5 mPa · s
It was ec.

Further, a trial manufacture 24 was prepared in which the ejection nozzle diameter was 40 μm, the piezoelectric element drive voltage was 80 V, the drive frequency was 3 kHz, the resolution was 180 dots / inch, and the ink ejection amount was 0.1 μg.
Using a nozzle ink jet evaluation machine, PPC paper (PPC paper registered by Xerox Co., Ltd.), recycled paper (Yamayuri registered by Honshu Paper Co., Ltd.), bond paper (Gilbert bond 25% cotton paper registered by Mead Co., Ltd.), fine paper (Oji Paper Registration A solid alphabet letter or the like was printed on the trademark OK high-quality paper L), and the following tests 1 to 7 were evaluated. (Test 1) Character print sample Visual evaluation of print quality.

The evaluation results were classified as follows.

Bleeding is not observed with the naked eye ... ◎ Bleeding is visible but characters are recognizable ... △ Characters are not recognizable ...・ ・ ・ ・ ・ × (Test 2) Macbeth TR-927 type (Kol
Evaluation of the density of a solid printed portion using an optical densitometer (a registered trademark of Lomorgan) (aperture size: 4 mm).

The evaluation results are classified as follows.

O. D. Value 1.3 or more ・ ・ ・ ◎ O. D. Value 1.1 or more and less than 1.3 ... D. Value less than 1.1 ・ ・ ・ × (Test 3) Rubbing the solid print area with a cotton cloth at a pressure of 100 g / cm ² until no print stain occurs. Quick dry evaluation to investigate the time.

The evaluation results are classified as follows.

No stain on the printed matter is observed within 2 seconds ... ◎ No stain on the printed matter is observed within 15 seconds ... △ Contamination is observed .... × (Test 4) A finger touch evaluation is performed by rubbing the printed portion of the character with a finger 5 minutes after the printing is finished and visually observing the printed stain.

The evaluation results are classified as follows.

No stains on the printed matter are observed. ◎ Some stains on the printed matter occur, but the characters can be identified. △ Cannot be distinguished ..... × (Test 5) Continuous ejection stability evaluation to investigate the presence or absence of missing dots during continuous printing at room temperature for 36 hours.

The evaluation results are classified as follows.

10 missing dots within 36 hours ..... ◎ 10 missing dots within 24 hours ..... △ 10 or more missing dots within 1 hour. Occurrence ..... (Test 6) The same evaluation as in Test 5 was performed with the driving frequency set to 6 kHz.

Classification of the evaluation results conforms to Test 5.

(Test 7) The same evaluation as in Test 5 was performed with the driving frequency set to 10 kHz. Classification of evaluation results conforms to Test 5.

The evaluation results of Example 1 are all
Met.

(Example 2) In the same manner as in Example 1, ink compositions having compositions shown in Table 1 as Examples 2-1 to 2-7 were obtained. Numerical values in the table unless otherwise specified are% by weight
Is shown. After preparing the ink, the physical property value is 25 ° C.
The surface tension and the viscosity at 20 ° C. are also shown.

[0054]

[Table 1]

Regarding the inks of Examples 2-1 to 2-7,
Tests 1 to 7 were carried out in the same manner as in Example 1. In each of Examples 2-1 to 2-4, the evaluation result was ⊚. Examples 2-5 do not contain an organic solvent having an ethylene oxide group, Examples 2-6 use an organic solvent having an average molecular weight of more than 1000, and Examples 2-7 use an organic solvent. Although the addition amount of was less than 10% by weight with respect to the total amount of the ink, both surface tension and viscosity satisfied the constitution of the present invention, and the evaluation results were all ⊚.

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. After the ink was prepared, tests 1 to 7 were evaluated using the same evaluation machine as in Example 1. The results are also shown in Table 2.

[0057]

[Table 2]

As in Comparative Example 1, the ink using Neocoal YSK (registered trademark of Daiichi Kogyo Seiyaku Co., Ltd.), which is an anionic surfactant, has severe foaming of the ink and is inferior in frequency response and ejection stability. Therefore, the results of tests 5 to 7 were x.

Further, 1% by weight of Epan 740 (registered trademark of Dai-ichi Kogyo Seiyaku Co., Ltd.) was added to the surfactant as in Comparative Example 2, but the surface tension of 35 dyn / cm or less did not spread the ink. Is insufficient, the dots do not connect to each other and the coverage is lowered, so that the optical density is lowered and the quick drying property is adversely affected. Furthermore, because the wettability with the head constituent material was insufficient, dot omission occurred and the frequency response was also inferior.

Also in Comparative Example 3, the viscosity is 20 mPas.
In the above cases, the quick-drying properties of Tests 3 and 4 deteriorated, and dot omission occurred.

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 nonionic surfactant is used to improve the ink wettability, and an average of ethylene oxide groups contained in the structure is included. Molecular weight 10
It can be found that one or more kinds of alcoholic solvents of 00 or less are contained, and the addition amount is 10% by weight or more based on the total weight of the ink.

(Embodiment 3) The ink of the embodiment 1 was used in a prototype 24 nozzle ink jet evaluation machine having an ejection 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 ejection amount of 0.08 μg. Using the same type of paper as in Example 1, solid letters, letters and the like were printed, and the above tests 1 to 7 were evaluated. The evaluation results were all ⊚.

(Embodiment 4) The ink of the embodiment 1 was used in a prototype 48-nozzle inkjet evaluation machine 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. Using the same type of paper as in Example 1, solid letters, letters and the like were printed, and the above tests 1 to 7 were evaluated. The evaluation results were all ⊚.

(Comparative Example 4) The ink of Example 1 was used as a prototype 48-nozzle inkjet evaluation machine having a discharge nozzle diameter of 40 μm, a piezoelectric element drive voltage of 100 V, a drive frequency of 3 kHz, a resolution of 360 dots / inch, and an ink discharge amount of 0.12 μg. Using, the same type of paper as in Example 1 was printed with solid letters, alphabetical characters and the like, and the above tests 1 to 7 were evaluated. As for the evaluation results, the test 1 was x, and the other tests were all ◎. In Test 1, bleeding was noticeably observed especially on copy paper and recycled paper.

(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. The evaluation results were all x.

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

[0067]

As described above, according to the present invention, it is possible to provide a recording method using a novel aqueous recording ink composition.

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

Further, according to the present invention, a recording method using an aqueous recording ink composition which gives a high-quality printed matter by drying quickly on a recording medium without a special surface treatment such as plain paper, Has the effect of being able to provide.

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

Claims (3)

[Claims] 1. Driving at a driving frequency of 3 kHz or higher,
In a recording method using an ink composition for water-based recording, the ink ejection nozzle has a resolution of 180 dots / inch or more, and ink droplets are ejected from a nozzle to adhere the ink droplets to a recording medium to perform recording. Contains a colorant, an organic solvent, and a nonionic surfactant, and has a surface tension at 25 ° C. of 35 dyn / cm or less and 2
Recording using an aqueous recording ink composition having a viscosity at 0 ° C. of 20 mPa · sec or less and an ink discharge amount per dot of 0.1 μg or less 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
2. The recording method using the aqueous recording ink composition according to claim 1, wherein one or more kinds are selected from alcoholic solvents of 000 or less. 3. The recording method using the aqueous recording ink composition according to claim 1, wherein the addition amount of the organic solvent contained in the ink is 10% by weight or more based on the total weight of the ink. ..