JPH05239390A - Water-based ink and method for recording using the same - Google Patents

Abstract

PURPOSE:To obtain a water-based ink, comprising a colorant dispersible in water, etc., a wetting agent and a carboxyl group-containing water-soluble polymer, having a prescribed value or below of surface tension, providing high image quality, excellent in quick-drying properties, permeability, preservation stability and jetting stability and useful for ink jet recording, etc. CONSTITUTION:The objective water-based ink comprises (A) a colorant at least dispersible or soluble in water such as an acid and/or a direct dye, (B) a wetting agent such as diethylene glycol monophenyl ether and (C) preferably 0.01-2wt.% water-soluble polymer compound such as alginic acid having carboxyl groups as hydrophilic groups. This ink has <=5mJ/m<2> surface tension and pH>=7. Furthermore, this water-based ink is preferably used and discharged from a fine discharge port and flown as droplets to form an image on a substance to be recorded at pH<=6.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to the technical field of an aqueous ink suitable for ink jet recording, particularly an aqueous ink composition exhibiting excellent properties as a color ink for so-called plain paper.

[0002]

2. Description of the Related Art In recent years, ink jet printers have become popular due to their advantages of low noise and low running cost, and color printers capable of printing on plain paper have been put on the market. However, image color reproducibility, water resistance, light resistance,
It is difficult to satisfy all of the image dryness, image blurring, and ejection reliability. Particularly in the case of a color printer, even if the image quality is not deteriorated in the yellow, magenta, and cyan single-color printing portions, the image quality is easily deteriorated in the two-color overlapping portion of red, green, and blue. In particular, when drying is carried out without using a fixing device, since the drying property is improved by increasing the permeability as in JP-A-55-29546, the paper is considerably blotted. Further, Japanese Patent Laid-Open No. 56-57862 discloses an ink to which a strong basic substance is added, but it is effective for rosin-sized acidic paper, but is not effective for paper using alkyl ketene dimer as a sizing agent. has no effect. Further, Japanese Patent Laid-Open No. 1-203483 discloses a recording liquid containing a polyhydric alcohol derivative and pectin, which contains pectin as a thickener to prevent bleeding. However, since pectin is a nonionic compound having a hydroxyl group as a hydrophilic group, there is a problem in that the ejection stability after printing is not sufficient.

[0003]

It is an object of the present invention to provide a water-based ink which satisfies various characteristics as an inkjet, is excellent in drying property, and is improved in deterioration of image quality, and a recording method using the same.

[0004]

The present invention relates to a water-based ink which is suitable for ink jet recording, particularly when it is color printed on plain paper, and which has excellent drying properties and little deterioration in image quality. According to the present invention, an ink having a surface tension of 50 mJ / m ² or less contains a hydrophilic polymer having a carboxyl group as a thickening agent for the purpose of enhancing penetrability into paper. It utilizes the fact that it dissolves in water and becomes insoluble in water on the acidic side, and when stored it is made alkaline to give storage stability. When ink adheres to the surface of the recording paper, it donates protons and evaporates water from the recording paper. The present invention has been completed by finding that the effect of preventing bleeding appears due to a rapid change in viscosity due to. In the ink of the present invention, by setting the pH to 7 or more, the storage stability of the ink can be obtained, and many copy papers, sticky notes and the like used in the office have a pH of 5 to 6, and these records (EN) Provided is a recording method for forming a high-quality and high-resolution recorded image by ejecting ink onto a paper from a minute ejection port of 30 to 60 µm and flying as droplets at 6 to 20 m / s for recording. it can.

Examples of the water-soluble polymer having a carboxyl group used in the present invention include alginic acid extracted from brown algae, gellan gum obtained by fermentation using a microorganism, pectic acid derived from pectin, and chicken corolla. Extracted hyaluronic acid and hyaluronic acid compound with low molecular weight by hyaluronidase, natural and semi-natural hydrophilic polymer compounds such as carboxymethylcellulose which is a fibrin derivative, and polyacrylic acid and acrylic acid and other monomers Examples thereof include synthetic water-soluble polymers such as polymers. The amount of the water-soluble polymer compound added varies depending on the type and desired physical properties of the ink, but normally it is preferably used within the range of 0.01 to 2% by weight in the ink. When the polymer substance itself is insoluble in water, it can be made water-soluble by forming a salt thereof.
When the polymeric substance having a carboxyl group is used as a salt, the salt may be prepared in advance before the ink is prepared by mixing it with other ink components, but it may be carried out simultaneously with the pH adjustment when preparing the ink. The salt is preferably an alkali metal hydroxide such as lithium hydroxide, sodium hydroxide or potassium hydroxide, and a quaternary ammonium hydroxide represented by the following formulas (II-1) to (II-8): Alternatively, it is preferable to use a quaternary phosphonium hydroxide to form a cation salt.

[Chemical 2]

[Chemical 3] Although the amount of the cation ion varies depending on the kind of the hydrophilic polymer, it is usually added so as to be 30% or more, and more preferably 50% or more with respect to the number of moles of the water-soluble polymer. Is preferred. However, the ratio of substitution of the carboxyl group of alginic acid with the salt is about 80%, and it is not necessary to completely replace the proton of alginic acid.

[Chemical 4] (Y: nitrogen or phosphorus, R _{3 to} R ₆ : alkyl group having 1 to 4 carbon atoms, hydroxyalkyl group, halogenated alkyl group)

As the pH adjuster, any substance can be used as long as it can adjust the pH to 7 or more without adversely affecting the ink to be prepared. Examples thereof include amines such as diethanolamine and triethanolamine, hydroxides of alkali metal elements such as lithium hydroxide, sodium hydroxide and potassium hydroxide, ammonium hydroxide, quaternary ammonium hydroxide and quaternary phosphonium. Examples thereof include hydroxides, carbonates of alkali metals such as lithium carbonate, sodium carbonate and potassium carbonate.

Although the ink of the present invention uses water as a liquid medium, it improves the dissolution stability of the compound of the present invention in order to make the ink have desired physical properties, prevent the ink from drying. The following water-soluble organic solvents can be used for the purpose of, for example, Polyhydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, glycerol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol Polyhydric alcohol alkyl ethers such as monomethyl ether and propylene glycol monoethyl ether, polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether; N-methyl-2-pyrrolidone, N-hydroxyethyl- 2-pyrrolidone, 1,3-dimethyl Nitrogen-containing heterocyclic compounds such as imidazolidinone, ε-caprolactam, γ-butyrolactone; amides such as formamide, N-methylformamide, N, N-dimethylformamide; monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine, Examples thereof include amines such as triethylamine, sulfur-containing compounds such as dimethyl sulfoxide, sulfolane and thiodiethanol, propylene carbonate and ethylene carbonate.
These solvents may be used alone or in combination with water. Among these, particularly preferred are diethylene glycol, thiodiethanol, polyethylene glycol 200 to 600, triethylene glycol, glycerol, and N-methyl-2-pyrrolidone. By using these, high solubility of the present compound and water vaporization An excellent effect can be obtained for preventing defective injection characteristics.

The penetrant added for the purpose of adjusting the surface tension is diethylene glycol monophenyl ether, ethylene glycol monophenyl ether, ethylene glycol monoallyl ether, diethylene glycol monophenyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, Alkyl and aryl ethers of polyhydric alcohols such as tetraethylene glycol chlorophenyl ether, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl esters, sorbitan alkyl esters, polyoxyethylene sorbitan alkyl esters Nonionic surfactants such as compounds, fatty acid salts, higher alcohol sulfates Sulfates of fatty amines and fatty amides, fatty alcohol phosphate ester salts, dibasic fatty acid ester sulfonates, fatty acid amide sulfonates, alkylallyl sulfonates and other anionic surfactants, fats Surfactants such as group amines and quaternary ammonium salts, aromatic quaternary ammonium salts, heterocyclic quaternary ammonium salts, amphoteric surfactants such as betaine, aminocarboxylic acid salts and imidazoline derivatives, fluorine-based surfactants , Lower alcohols such as ethanol and 2-propanol can be mentioned, but diethylene glycol monobutyl ether is particularly preferable. The surface tension in the present invention is an index showing the permeability to paper, and in particular, it shows the dynamic surface tension in a short time of 1 second or less after the surface is formed, which is different from the static surface tension measured at the saturation time. ..
As a measuring method, any conventionally known method described in JP-A-63-31237 can be used as long as it can measure a dynamic surface tension of 1 second or less.
It measured using the lhelmy type hanging plate type surface tensiometer. The value is preferably from 50 mJ / m ² or less surface tension, and more preferably dry can be obtained and excellent and 40 mJ / m ² or less.

As the water-soluble dye used as a coloring material, those which are classified into acid dyes, direct dyes, basic dyes, reactive dyes and food dyes in the color index and which have excellent water resistance and light resistance are used. Be done. Specific examples of these dyes include acid dyes and food dyes such as C.I. I. Acid. Yellow 17,23,42,4
4,79,142 C.I. I. Acid. Red 1,8,13,14,1
8, 26, 27, 35, 37, 42, 52, 82, 8
7, 89, 92, 97, 106, 111, 114, 11
5,134,186,249,254,289 C.I. I. Acid. Blue 9, 29, 45, 92,
249 C.I. I. Acid. Black 1, 2, 7, 24, 2
6,94 C.I. I. hood. Yellow 3,4 C.I. I. hood. Red 7,9,14 C.I. I. hood. Black 1,2 as a direct dye C.I. I. direct. Yellow 1,12,24,2
6, 33, 44, 50, 120, 132, 142, 14
4,86 C.I. I. direct. Red 1,4,9,13,1
7, 20, 28, 31, 39, 80, 81, 83, 8
9,225,227 C.I. I. direct. Orange 26,29,62,1
02 C. I. direct. Blue 1, 2, 6, 15, 2
2,25,71,76,79,86,87,90,9
8, 163, 165, 199, 202 C.I. I. direct. Black 19, 22, 32, 3
8, 51, 56, 71, 74, 75, 77, 154, 1
68,171 as a basic dye, C.I. I. basic. Yellow 1, 2, 11, 13,
14, 15, 19, 21, 23, 24, 25, 28, 2
9, 32, 36, 40, 41, 45, 49, 51, 5
3,63,65,67,70,73,77,87,91 C.I. I. basic. Red 2, 12, 13, 14,
15, 18, 22, 23, 24, 27, 29, 35, 3
6,38,39,46,49,51,52,54,5
9,68,69,70,73,78,82,102,1
04, 109, 112 C.I. I. basic. Blue 1,3,5,7,9,2
1, 22, 26, 35, 41, 45, 47, 54, 6
2,65,66,67,69,75,77,78,8
9, 92, 93, 105, 117, 120, 122, 1
24, 129, 137, 141, 147, 155 C.I. I. basic. Black 2,8 As a reactive dye, C.I. I. Reactive. Black 3, 4, 7, 11,
12, 17 C.I. I. Reactive. Yellow 1,5,11,1
3,14,20,21,22,25,40,47,5
1,55,65,67 C.I. I. Reactive. Red 1,14,17,2
5,26,32,37,44,46,55,60,6
6,74,79,96,97 C.I. I. Reactive. Blue 1, 2, 7, 14, 1
5,23,32,35,38,41,63,80,95 etc. can be used. In particular, acid dyes and direct dyes are preferable because the addition of the water-soluble polymer improves the fixability of these dyes on the paper surface and the water resistance. For example, in the case of sodium alginate and a dye, a 0.1% aqueous solution of sodium alginate exhibits Newtonian flow to which the acid dye C.I. An aqueous solution containing 1% by weight of I Acid Yellow 23 (used in Example 1) exhibits thixotropic properties and becomes a non-Newtonian fluid. It is speculated that the difference in water resistance between Example 1 and Comparative Example 1 may be due to such a dye and sodium alginate forming an association.

As the pigment, organic pigments such as azo type, phthalocyanine type, anthraquinone type, quinacridone type,
Examples include dioxazine-based, indigo-based, thioindigo-based, perylene-based, isoindolenone-based, aniline black, azomethine-based, rhodamine B lake pigments, carbon black, and the like. As inorganic pigments, iron oxide, titanium oxide, calcium carbonate, barium sulfate, Examples include aluminum hydroxide, barium yellow, dark blue, cadmium red, chrome yellow, and metal powder.

As a pigment dispersant, a hydrophilic polymer,
In the natural system, gum arabic, tragum gum, guar gum, karaya gum, locust bean gum, arabinogalactone, pectin, quince seed starch, and other physical properties, alginic acid, carrageenan, seaweed macromolecules such as agar, gelatin, casein, albumin. , Animal-based polymers such as collagen, microbial-based polymers such as xanthene gum and dextran, and fibrin-based polymers such as methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, carboxymethylcellulose, etc. in semi-synthetic systems, sodium starch glycolate ,
Starch-based polymers such as sodium starch phosphate, seaweed-based polymers such as sodium alginate and propylene glycol alginate, vinyl-based polymers such as polyvinyl alcohol, polyvinylpyrrolidone, and polyvinyl methyl ether, and non-crosslinked Acrylamide, polyacrylic acid and its alkali metal salts, acrylic resins such as water-soluble styrene acrylic resin, water-soluble styrene maleic acid resin, water-soluble vinyl naphthalene acrylic resin, water-soluble vinyl naphthalene maleic acid resin, polyvinylpyrrolidone, polyvinyl alcohol, Alkali metal salt of β-naphthalenesulfonic acid formalin condensate,
Examples thereof include polymer compounds having a side chain with a salt of a cationic functional group such as quaternary ammonium or amino group, and natural polymer compounds such as cerac.

To the ink of the present invention, conventionally known additives can be added in addition to the above colorant and solvent.
For example, as a preservative and fungicide, sodium dehydroacetate,
Sodium sorbate, 2-pyridinethiol-1-oxide sodium, sodium benzoate, pentachlorophenol sodium and the like can be used in the present invention.

Examples of the chelating agent include sodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, and sodium uramildiacetate. As the rust preventive agent, for example,
Acid sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite,
Examples include pentaerythritol tetranitrate and dicyclohexyl ammonium nitrite. In addition, a water-soluble ultraviolet absorber, a water-soluble infrared absorber and a surfactant can be added depending on the purpose. Examples and comparative examples of the present invention will be shown below.

[0014]

【Example】

Example 1 Using the compound obtained by the above-mentioned synthesis method, the composition having the following formulation was dissolved by stirring at 60 ° C., and after cooling at room temperature,
The pH was adjusted to 8 with a 10% aqueous solution of lithium hydroxide and filtered with a 0.22 μm Teflon filter to prepare Yellow Ink 1. C. I. Acid Yellow 23 1% by weight Glycerol 5% by weight Diethylene glycol monobutyl ether 10% by weight Sodium alginate 0.2% by weight Sodium dehydroacetate 0.2% by weight Ion-exchanged water Remaining amount

Example 2 Magenta ink 1 was prepared in the same manner as in Example 1 except that the following composition was used, and the pH was adjusted to 9 with sodium hydroxide. C. I. Acid Red 254 1.5% by weight Diethylene glycol 8% by weight Diethylene glycol monobutyl ether 8% by weight Hyaluronic acid 0.1% by weight Specific example (II-1) 25% aqueous solution 1.8% by weight 2-pyridinethiol-1-oxide sodium 0 .2 wt% ion-exchanged water remaining

Example 3 The pH was the same as in Example 1 except that the following composition was used.
Was adjusted to 9 with lithium hydroxide to prepare cyan ink 1. C. I. Acid blue 249 1.8% by weight N-methyl-2-pyrrolidone 5% by weight glycerol 2% by weight propylene glycol monobutyl ether 8% by weight Pectic acid 0.1% by weight Specific example (II-3) 25% aqueous solution 2% by weight dehydro Sodium acetate 0.2 wt% Ion-exchanged water Remaining amount

Example 4 The pH was the same as in Example 1 except that the following composition was used.
Was adjusted to 9 with lithium hydroxide to prepare Black Ink 1. C. I. Food Black 2 2.2% by weight Ethylene glycol 5% by weight Glycerol 2% by weight Ethylene glycol monophenyl ether 10% by weight Polyacrylic acid 0.1% by weight Concrete example (II-4) 25% Aqueous solution 2% by weight Sodium benzoate 0 .2 wt% ion-exchanged water remaining

Example 5 The pH was the same as in Example 1 except that the following composition was used.
Was adjusted to 9 with sodium hydroxide to prepare Yellow Ink 2. Direct Yellow 120 1% by weight Triethylene glycol 5% by weight Glycerol 2% by weight Diethylene glycol monobutyl ether 5% by weight Carboxymethyl cellulose 0.1% by weight Fluorosurfactant FC430 (Sumitomo 3M) 0.1% by weight Specific example (II- 2) 25% aqueous solution 1.5% by weight deionized water remaining amount

Example 6 The pH was the same as in Example 1 except that the following composition was used.
Was adjusted to 8 with lithium hydroxide to prepare magenta ink 2. Direct Red 9 1.5% by weight Propylene glycol 8% by weight Diethylene glycol monobutyl ether 10% by weight Alginic acid 0.1% by weight Specific example (II-7) 25% Aqueous solution 2% by weight Ion-exchanged water Remaining amount

Example 7 The same procedure as in Example 1 was repeated except that the following composition was used.
Was adjusted to 9 with lithium hydroxide to prepare cyan ink 2. Direct Blue 199 1.8% by weight N-methyl-2-pyrrolidone 8% by weight Ethylene glycol monophenyl ether 8% by weight Gellan gum 0.1% by weight Sodium benzoate 0.1% by weight Deionized water residual amount

Example 8 The pH was the same as in Example 1 except that the following composition was used.
To 8 with sodium hydroxide to obtain black ink 2. Direct Black 168 2.8% by weight Thiodiethanol 5% by weight Diethylene glycol monobutyl ether 10% by weight Sodium alginate 0.2% by weight Deionized water remaining

Comparative Example 1 Yellow ink 3 was prepared in the same manner as in Example 1 except that sodium alginate was omitted.

Comparative Example 2 Magenta ink 3 was prepared in the same manner as in Example 2 except that glycerol was used instead of diethylene glycol monobutyl ether.

Comparative Example 3 A cyan ink 3 was prepared in the same manner as in Example 3, except that pectin acid was replaced with pectin, and the specific example (II-3) 25% aqueous solution was replaced with ion-exchanged water.

Comparative Example 4 Black ink 3 was prepared in the same manner as in Example 4 except that the 25% aqueous solution of the specific example (II-4) was removed and the pH of the ink was changed to 4.5.

Comparative Example 5 Yellow ink 4 was prepared in the same manner as in Example 5 except that polyacrylic acid and the 25% aqueous solution of the specific example (II-2) were omitted.

Comparative Example 6 Magenta Ink 4 was prepared in the same manner as in Example 6 except that the 25% aqueous solution of Concrete Example (II-7) was removed and the pH was adjusted to 8 with potassium hydroxide.

Comparative Example 7 Cyan ink 4 was prepared in the same manner as in Example 7, except that ethylene glycol monophenyl ether was used instead of ethylene glycol monophenyl ether.

Comparative Example 8 Black ink 4 was prepared in the same manner as in Example 8 except that sodium alginate was replaced with polyvinyl alcohol (average molecular weight 2000).

Next, the above Examples 1 to 8 and Comparative Examples 1 to 8
The following test was performed on the. 1) Image clarity 300 dp of thermal inkjet method shown in FIG.
Inkjet printer with i nozzle and FIG.
The laminated PZT shown in Fig. 3 was used to pressurize the liquid chamber channel.
Printing was performed with an inkjet printer having a nozzle of dpi, and image bleeding, color tone, and density were visually comprehensively judged. The printing paper was printed on three commercially available recycled papers, high-quality paper and bond paper. 2) Image drying property The filter paper was pressed against the printed image under certain conditions, and the time until the ink was not transferred to the filter paper was measured. When any of the papers dried within 10 seconds, it was judged as ◯. 3) Water resistance of image The image sample was dipped in water at 30 ° C. for 1 minute, the change in image density before and after the immersion was measured by a Macbeth densitometer, and the water resistance (fading rate%) was calculated by the following formula.

[Equation 1] 4) Storage stability Each ink was placed in a polyethylene container and stored at -20 ° C, 5 ° C,
It was stored at 20 ° C. and 70 ° C. under each condition for 3 months, and the surface tension after storage, the viscosity, and the presence or absence of precipitate deposition were examined. The product with no change in physical properties under any conditions was rated as ◯. 5) Reliability when printing is stopped During operation of the printer having the head shown in FIG. 2, it is checked how long printing can be resumed without capping, cleaning, etc., and how long (seconds) the ejection direction The table shows the results of evaluation of the reliability depending on whether the deviation occurs or the weight of the ejected droplets changes. 6) Surface tension The following shows the results of measuring the dynamic surface tension of each ink after measuring the time change of the surface tension with a Wilhelmy hanging plate type surface tension meter. (Below margin)

[0031]

[Table 1]

[0032]

According to the water-based ink of the present invention, the permeability of the ink can be enhanced by setting the dynamic surface tension to 50 mJ / m ² or less, and a water-soluble polymer having a carboxylic acid as a hydrophilic group is added. By doing so, it is possible to provide a water-based ink that is high in image quality and quick-drying when color-printed on plain paper, while suppressing deterioration of image quality due to improvement of permeation rate by a rapid increase in viscosity after evaporation of water. Further, according to the present invention, by selecting a counter ion of the water-soluble polymer that is a thickener, it is possible to provide a water-based ink having excellent storage stability and jetting stability as compared with conventional thickeners. .. According to the present invention, it is possible to improve the water resistance by using a known acid dye or direct dye by the interaction of the dye and the water-soluble polymer on the paper surface. Further, according to the present invention, by setting the pH of the ink to 7 or more, it is possible to provide a water-based ink which is stable during storage of the ink and has an excellent image quality improving effect after printing. With these, the present invention can provide a recording method for forming an excellent color image on plain paper.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a thermal inkjet type inkjet printer used in Examples and Comparative Examples of the present invention.

FIG. 2 is a laminated P used in Examples and Comparative Examples of the present invention.
The sectional view of a ZT pressure type inkjet printer is shown.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ink ejection nozzle 2 Heating element 3 Substrate 4 Nozzle plate 5 Ink liquid chamber 6 Ink supply pipe 7 Flow path 8 Flow path plate 9 Common liquid chamber 10 Laminated PZT

Claims (5)

[Claims] 1. A colorant, a humectant, and a water-soluble polymer compound having a carboxyl group as a hydrophilic group, which are dispersed or dissolved in water, and have a surface tension of 50 mJ.
/ M ² or less, a water-based ink. 2. The aqueous ink according to claim 1, wherein the pH of the ink is 7 or more. 3. Sodium, lithium and the following formula (I):
7. At least one cation ion selected from the group consisting of quaternary ammonium or quaternary phosphonium represented by: is contained as a counter ion of the carboxyl group of the water-soluble polymer compound. 1
Alternatively, the water-based ink according to item 2. [Chemical 1] (In the formula, Y: nitrogen or phosphorus, R _{3 to} R ₆ : carbon number 1 to 4
Alkyl group, hydroxyalkyl group, halogenated alkyl group) 4. The water-based ink according to claim 1, 2 or 3, wherein the colorant is an acidic and / or direct dye. 5. The aqueous ink according to claim 2, which is ejected from a fine ejection port to fly as a droplet,
The recording method is characterized in that an image is formed on a recording medium having a number of 6 or less.