JPH05230409A - Water-base recording ink composition and method for recording therewith - Google Patents

Abstract

PURPOSE:To provide a method for recording with the title compsn. which is excellent in frequency response, gives a high-quality printing, and enables a high-speed recording and cost reduction of a recording apparatus. CONSTITUTION:The title compsn. at least contg. a colorant, an org. solvent, and a fluorine compd. and having a surface tension at 25 deg.C of 35-dyn/cm or lower and a viscosity at 20 deg.C of 20 mPa.sec or lower is used for recording by discharging drops of the compsn. through a nozzle and causing the drops to adhere to a printing object under such conditions that the driving frequency is 3kHz or higher, that the resolution of an ink discharge nozzle is 180 dots/in or higher, and that the amt. discharged of the compsn. per dot is 0.1mug or lower.

Description

Detailed Description of the Invention

[0001]

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

[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 above, the frequency response of the ink is good. (5) The ink dries quickly on the recording material. (6) No nozzle clogging occurs during printing or when restarting after printing is interrupted. (7) In order to satisfy the above-mentioned various required characteristics, such as high safety, a coloring agent such as an aqueous dye has been conventionally examined. JP-A-59-9376
5, Japanese Patent Laid-Open No. 60-243175 and others examined organic solvents as solvents, and Japanese Patent Laid-Open Nos. 56-149475 and 56-163168 examined additive agents such as surfactants. JP-A-56-5781, JP-A-61
-250077, JP-A-63-139964, etc.,
Furthermore, examinations of ink physical properties such as ink viscosity, surface tension, and pH are disclosed in JP-A-53-61412, JP-A-62-116676, etc., and considerable effects are observed.

[0004]

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, the frequency response is improved as the ink viscosity is decreased, but the ejection stability is remarkably deteriorated under the driving condition of 3 kHz or more, and the frequency response is ensured 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, with respect to nozzle clogging, conventionally, a method has been taken to prevent the ink from drying and to prevent the ink from solidifying even when 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, and ink suction or a compression pump, a nozzle cap, a nozzle cleaning mechanism, etc. must be added. 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 consider both the ink composition and the recording method.

Therefore, the present invention is intended to solve such a problem, and an object 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 an aqueous recording ink composition which can prevent clogging and has a large number of mechanical mechanisms for ensuring reliability and can realize cost reduction of a recording apparatus. To provide the recording method that was used.

[0015]

A water-based recording ink composition of the present invention and a recording method using the same have a driving frequency of 3
Drive at a frequency of kHz or higher and set the ink ejection nozzle resolution to 1
In a recording method in which an ink droplet is discharged from a nozzle at a rate of 80 dots / inch or more and the ink droplet is attached to a recording medium to perform recording, the ink contains at least a colorant, an organic solvent, and a fluorine-based compound. It is characterized by having a surface tension of 35 dyn / cm or less at 25 ° C and a viscosity of 20 mPa · sec or less at 20 ° C. Furthermore, by using it, the ink discharge amount per dot is 0.1μ.
The recording method is characterized in that it is not more than g.

Further, 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.

[0017]

The operation of the present invention will be described. The aqueous recording ink composition used in the present invention contains a colorant for printing and a solvent for dissolving and dispersing the colorant as essential components, and further contains an organic solvent and at least one fluorine compound. Become. The organic solvent improves the solubility of the fluorine-based compound in the ink and also contributes greatly to the prevention of nozzle clogging due to its excellent moisturizing property, and at the same time, the uniformity of the ink including the colorant is improved. The unevenness in printing is eliminated, giving the impression that the hue is calm, and as a result, the optical density is increased.

Next, the fluorine compound used in the present invention is
Anionic compounds such as perfluoroalkylcarboxylates, perfluoroalkyl phosphates, cationic compounds such as perfluoroalkyltrimethylammonium salts, amphoteric compounds such as perfluoroalkylbetaines, perfluoroalkylamine oxides, perfluoroalkylethylene oxides Although it is a nonionic compound such as an adduct, the perfluoroalkyl group in its structure shows excellent wetting and leveling effects, and also has less foaming to reduce the surface tension of the ink and improve the wettability to the recording medium. Therefore, 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, even in the discharge head, the surface tension at 25 ° C. is 35 dyn / c.
By setting the viscosity at m or less and at 20 ° C. to 20 mPas or less, the wettability with the head constituent material is improved, the ink flow path resistance is reduced, ejection from nozzles, ink supply from ink supply holes, etc. The frequency response 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. This is greatly improved by a recording method in which ink droplets having an ink ejection amount of 0.1 μg or less are ejected from nozzles.

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.

The organic solvent used as a mixture with the ion-exchanged water is preferably an alcoholic organic solvent such as linear chains such as methanol, ethanol, propanol and butanol, and branched monovalent chains such as isopentyl alcohol and 3-ethyl-1-butanol. Alcohol, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol # 200, # 300, # 4
Glycols such as 00 and # 600, and their monoethers and monoesters can be used. The addition amount of these alcohol-based organic solvents may be variously considered depending on the type and characteristics required for the ink, and is preferably 4 to 70% by weight, and more preferably 10 to 30% by weight based on the total weight of the ink. These may be used alone or in combination.

The fluorinated compounds which can be used in the present invention are commercially available and easily available as Surflon S-111, S-112, S-113,
S-121, S-131, S-132, S-141, S
-141, S-145 (all registered trademarks of Asahi Glass Co., Ltd.), Fullard FC-93, FC-95, FC-98, FC-1
29, FC-135, FC-170C, FC-430,
FC431 (above registered trademark of Sumitomo 3M Co., Ltd.) and the like, which are added alone or in a mixture, adjust the surface tension at 25 ° C. to 35 dyn / cm or less as an ink composition. Usually, the addition amount is 0.001 to 5 with respect to the total weight of the ink, depending on the type and performance of the fluorine compound used.
The weight% is more preferably 0.01 to 2% by weight.

Further, it may be used in combination with a usual hydrocarbon-based or silicon-based surfactant, whereby the effect of the present invention may be more remarkable.

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, 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, 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, and 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, hexachlorophene, sorbic acid, p-hydroxybenzoic acid ester, ethylenediaminetetraacetic acid (EDTA) and the like can be contained for the purpose of antifungal agent, antiseptic agent and anticorrosive agent. ..
Further, it may contain an antifoaming agent, urea, thiourea, ethylene urea and the like.

The method for 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 or the like as a colorant, it is heated to 40 ° C. to 80 ° C., stirred with a screw or the like, mixed, 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 diameter of the ink discharge nozzle, the size of the ink discharge passage, the size of the ink supply passage, 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.

[0033]

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. 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% Florard FC-430 1% Urea 1% Ion-exchanged water 76% The above components are mixed and stirred at 60 ° C. for 2 hours and dissolved,
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 production was carried out 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 are classified as follows.

Bleeding is not observed with the naked eye ◎ ◎ Bleeding is seen 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 of 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 printed part with a cotton cloth at a pressure of 100 g / cm ² and investigating the time until the printing stain does not occur Quick drying evaluation.

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 ... △ Stain on the printed matter is observed even after 30 seconds ... ... × (Test 4) Finger touch evaluation is performed by rubbing the character printed portion with a finger 5 minutes after printing and visually observing the print stain.

The evaluation results are classified as follows.

No stain on the printed matter is observed .... ◎ Some stains on the printed matter occur, but the characters can be identified. △ Characters cannot be identified due to the stain on the printed matter.・ ・ × (Test 5) Continuous ejection stability evaluation for investigating the presence or absence of missing dots during continuous printing at room temperature for 36 hours.

The evaluation results are classified as follows.

10 times or more dot dropouts occur within 36 hours ... 10 times or more dot dropouts occur within 24 hours ... 10 times or more dot dropouts occur within 1 hour. Test 6) The same evaluation as in Test 5 was performed with the drive 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, Examples 2-1 to 2-7 are shown in Table 1.
An ink composition was obtained with the composition shown below. Numerical values in the table, unless otherwise specified, indicate% by weight. Further, after the ink was prepared, the surface tension at 25 ° C. and the viscosity at 20 ° C. are also shown as the physical properties.

[0052]

[Table 1]

Neocol SW in Table 1 is an anionic surfactant, sodium dialkyl solfosuccinate manufactured by Daiichi Kogyo Seiyaku Co., Ltd.

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 to 6 also contained other hydrocarbon-based surfactants, and although they did not appear in the evaluation results, further improvements in quick drying etc. were observed.
In Examples 2-7, the amount of the organic solvent added was less than 10% by weight with respect to the total amount of the ink, but both the surface tension and the viscosity satisfy the constitution of the present invention, and the evaluation results are all ◎.
Met.

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.

[0056]

[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, as in Comparative Example 2, 0.01% by weight of Florard FC-98 was added to the surfactant, but the surface tension of 35 dyn / cm or less did not spread the ink sufficiently. Since the dots were not connected and the coverage was lowered, the optical density was lowered and the quick drying property was also 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 was 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. should be 20 mPa · sec or less, and in order to achieve these constitutions, it is appropriate to improve the ink wettability by using a fluorine compound and to contain at least one organic solvent. Can be found. Further, when the added amount is 10% by weight or more based on the total weight of the ink, the characteristics are further improved.

Example 3 The ink of Example 1 was used in a trial 24 nozzle ink jet evaluation machine 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, alphabetical characters 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 results were all ⊚.

Example 4 The ink of Example 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. When solid letters, alphabetical characters 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 results were all ⊚.

Comparative Example 4 The ink of Comparative Example 1 was prepared by using the ink of the discharge nozzle diameter of 40 μm, the piezoelectric element driving voltage of 100 V, the driving frequency of 3 kHz, and the resolution of 360.
Prototype with dot / inch and ink discharge of 0.12μg 48
Using a nozzle inkjet evaluation machine, solid letters, alphabetical characters and the like were printed on the same type of paper as in Example 1, and the above tests 1 to 7 were evaluated. As for the evaluation result, the test 1 became x, and the tests 5 to 7 were also x.

That is, the recording method of the present invention is as follows:
The use of the ink composition shown in 2 has a great effect.

[0065]

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.

According to the present invention, a recording method using a water-based recording ink composition which gives a high-quality printed matter by drying quickly on a recording medium having no 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 can prevent clogging and has no mechanism in terms of a mechanism for ensuring reliability and can realize cost reduction of a recording apparatus. , Having the effect that can be provided.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yukari Sano Yukari Sano 3-3-5 Yamato, Suwa City, Nagano Seiko Epson Corporation

Claims (3)

[Claims] 1. Driving at a driving frequency of 3 kHz or higher,
In an ink composition used in a recording method in which an 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, the ink is at least colored. Agent, an organic solvent, and a fluorine compound, and has a surface tension of 35 dyn / at 25 ° C.
cm or less, and a viscosity at 20 ° C. of 20 mPa · sec or less, an aqueous recording ink composition. 2. The ink composition for water-based recording according to claim 1, wherein the added amount of the organic solvent contained in the ink is 10% by weight or more based on the total weight of the ink. 3. The ink discharge amount per dot is 0.1 μm.
The recording method using the aqueous recording ink composition according to claim 1, wherein the recording amount is g or less.