JP3274788B2 - Aqueous ink and inkjet recording method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous ink and an ink jet recording method.

[0002]

2. Description of the Related Art Conventionally, an ink jet recording system employs an electrostatic suction system, a system in which mechanical vibration or displacement is applied to ink using a piezoelectric element, bubbles are generated by heating ink, and the pressure at that time is used. An ink ejection method such as a method is known. Ink droplets are formed by these ejection methods, and a part or all of them is attached to a recording material such as paper to perform recording. When a writing instrument such as a fountain pen, a felt pen, and a ballpoint pen is used, ink is ejected from a capillary tube as is well known, and recording is performed by receiving the ink on a recording material. As the ink used in such an ink jet recording system or writing instrument, those obtained by dissolving or dispersing various water-soluble dyes or pigments in water or a liquid medium composed of water and a water-soluble organic solvent are known and used. I have.

[0003]

It is a matter of course that various performances are required in the above-described conventional inks, but the most required performance is that when printing is performed using inks. The liquid stability is such that there is no clogging at the nozzle, orifice or pen tip of the recording apparatus and no generation of sediment when recording is interrupted or when recording is not performed for a long time. In particular, in the ink jet system, it is more expensive than the writing implement, and it is important to prevent clogging of the ink jet nozzle and the orifice. Further, in the ink jet system, even if nozzles and orifices are not clogged, there is also a serious problem in that the printing direction is deviated due to the generation of sediment, the ink droplet amount is changed, and the flying speed is changed. Furthermore, in the thermal ink jet system using thermal energy among the ink jet systems, a problem is important in addition to the fact that foreign matter is easily deposited on the surface of the heating element due to a change in temperature.

[0004] Attempts have been made to solve the above problem by defining the amount of impurities that can cause precipitation in the ink.

[0005] For example, Japanese Patent Publication No. 3-48951 discloses that the total content of iron and silicon contained in a liquid composition containing a water-soluble dye used in an ink jet recording system is 9%.
A liquid composition having a concentration of 1 ppm or less is disclosed, and Japanese Patent Publication No. 2-2906 discloses an aqueous solution containing a water-soluble acidic dye or a water-soluble direct dye ion-exchanged with a cation exchange resin as a main component. There is disclosed an ink which determines the amount of inorganic impurities such as ink for inkjet recording.

Further, Japanese Patent Application Laid-Open No. Sho 64-4350 discloses that the concentration of sodium ions in ink is 0.001% by weight to 0.2% by weight, and that fatty acids and fatty acid derivatives contained in a material constituting an ink tank are used. 10 to 10
An ink jet recording apparatus with 0 ppm is disclosed.

Japanese Patent Publication No. 60-48552 discloses an ink containing water, a water-soluble dye, a polyhydric alcohol or a polyhydric alcohol derivative, and containing 0.001 to 5% by weight of a fatty acid ester or the like as an antifoaming agent. Is disclosed.

[0008] However, although the conventional ink based on the definition of the amount of inorganic impurities is improved as compared with the ink containing an excessive amount of impurities, for example, when the ink is stored for a long period of time and changes in the temperature environment are taken into consideration. However, a sufficient effect was not always obtained.

[0009] Japanese Patent Application Laid-Open No. 64-4350 does not specify the amount of fatty acid ester in the ink.

In Japanese Patent Publication No. 60-48552, the amount of a fatty acid ester intentionally added as an antifoaming agent is also specified, but the amount of a fatty acid ester including impurities actually present in the ink is included. Does not specify anything.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the nozzles and orifices can be clogged even during use and during long-term storage due to changes in the temperature environment.
It is an object of the present invention to provide a water-based ink and an ink jet recording method which do not cause printing failure due to bending in a flight direction, a change in an ink droplet amount, and a change in a flight speed.

Commercially available dyes and pigments, which are ink materials, contain many impurities (for example, various organic and inorganic substances such as dispersants and leveling agents), and ink components other than dyes and pigments such as water It is a well-known fact that water and water-soluble organic solvents contain considerable amounts of organic and inorganic impurities.In addition, it is well-known that various impurities are mixed in the production and preparation of inks depending on the container, equipment and environment used. It is. In order to achieve the above-mentioned object, the present inventor has conducted intensive studies. As a result, these impurities cause the above-mentioned problems. Clogging, bends in jets, changes in ink drop volume, changes in flight speed,
A major cause of precipitation during storage of the ink is a fatty acid ester contained in the ink, and the use of an ink having an impurity amount of a certain value or less solves the various problems described above. This has led to the completion of the present invention.

[0013]

In order to achieve the above object, according to the first aspect of the present invention, in an aqueous ink containing a water-soluble dye or pigment as a colorant, the content of the fatty acid ester contained in the ink is determined. Is 0.6% by weight or less.

Further, in the aqueous ink according to the second aspect, the total content of the fatty acid ester is 0.3% by weight or less.

Further, in the aqueous ink according to the third aspect, the fatty acid ester is methyl palmitate and methyl stearate.

In the aqueous ink according to the fourth aspect, the content of the methyl palmitate is 0.2% by weight or less,
In addition, the content of the methyl stearate is 0.4% by weight or less.

Further, in the aqueous ink according to the fifth aspect, the content of the methyl palmitate is 0.1% by weight or less,
In addition, the content of the methyl stearate is 0.2% by weight or less.

Further, in order to achieve this object, the present invention provides an ink jet recording method using an aqueous ink containing a water-soluble dye or pigment as a colorant as a recording liquid. The recording is performed on the recording material by ejecting the aqueous ink of 0.6% by weight or less.

Further, in the ink jet recording method according to claim 7, the total content of the fatty acid ester contained in the aqueous ink is 0.3% by weight or less.

Further, in the ink jet recording method according to claim 8, the fatty acid ester contained in the aqueous ink is methyl palmitate and methyl stearate.

Further, in the ink jet recording method according to the ninth aspect, the content of methyl palmitate contained in the aqueous ink is 0.2% by weight or less, and the content of methyl stearate contained in the aqueous ink. Is 0.4% by weight
It is characterized by the following.

In the ink jet recording method according to the present invention, the content of methyl palmitate contained in the aqueous ink is 0.1% by weight or less, and the content of methyl stearate contained in the aqueous ink. Is 0.2% by weight or less.

The ink jet recording method according to the eleventh aspect is a thermal ink jet system in which the aqueous ink is ejected by using thermal energy from a heating element provided in an ink chamber filled with the aqueous ink. I do.

[0024]

The present invention will be described in further detail. The basic components of the ink used in the present invention are already known, and the dyes are represented by direct dyes, acid dyes, basic dyes, reactive dyes and the like. It is a water-soluble dye, particularly suitable as an ink jet recording ink, sharpness, water solubility,
Those satisfying stability, light resistance and other required performances include, for example, C.I. I. Direct black 17, 1
9, 32, 51, 71, 108, 146, 154, 16
8; I. Direct Blue 6, 22, 25, 71,
86, 90, 106, 199; I. Direct red 1, 4, 17, 28, 83, 227; I. Direct yellow 12, 24, 26, 86, 98, 142;
C. I. Direct orange 34, 39, 44, 46,
60; I. Direct violet 47, 48;
C. I. Direct brown 109; I. Direct green 59; I. Acid Black 2, 7, 2
4, 26, 31, 52, 63, 112, 118;
I. Acid Blue 9, 22, 40, 59, 93, 10
2, 104, 113, 117, 120, 167, 22
9, 234; I. Acid Red 1, 6, 32, 3
7, 51, 52, 80, 85, 87, 92, 94, 11
5, 181, 256, 289, 315, 317;
I. Acid Yellow 11, 17, 23, 25, 29,
42, 61, 71; I. Acid orange 7, 1
9; I. Acid violet 49; C.I. I. Basic black 2; I. Basic Blue 1, 3,
5, 7, 9, 24, 25, 26, 28, 29; I.
Basic Red 1, 2, 9, 12, 13, 14, 3,
7; I. Basic violet 7, 14, 27;
C. I. Food Black 1, 2 and the like.

The above dye examples are particularly preferred for the ink of the present invention, but the present invention is not limited to these dyes.

As the pigment, many inorganic pigments and organic pigments can be used in addition to carbon black. For example,
Azo lakes, azo pigments such as insoluble azo pigments, condensed azo pigments, chelate azo pigments, and polycyclics such as phthalocyanine pigments, perylene and perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments Pigments, dye lakes such as basic dye lakes and acid dye lakes, organic pigments such as nitro pigments, nitroso pigments, aniline black daylight fluorescent pigments, and inorganic pigments such as titanium oxide, iron oxide, and carbon black Can be mentioned. Other pigments can be used as long as they can be dispersed in the aqueous phase. Further, those obtained by subjecting the above pigment to a surface treatment with a surfactant, a polymer dispersant, or the like, for example, graft carbon and the like can also be used.

The above-mentioned pigment examples are particularly preferred for the ink of the present invention, but the present invention is not limited to these pigments.

When the above pigment is used as the coloring agent of the present invention, it is dispersed by a conventionally known method together with a suitable dispersing agent, a solvent, pure water and, if necessary, other additives.

As the dispersant, for example, JP-A-62-10
Polymer dispersion agents and surfactants used for pigment dispersion described in JP-A-1672 can be used. Examples of the polymer dispersants include proteins such as gelatin and albumin, natural rubbers such as gum arabic and gum tragacanth, and saponin. Such as glucosides, methylcellulose, carboxycellulose,
Cellulose derivatives such as hydroxymethylcellulose, natural polymers such as ligninsulfonate and shellac, polyacrylates, styrene-acrylic acid copolymer salts, vinylnaphthalene-acrylic acid copolymer salts, styrene-maleic acid salts Polymer salts, vinyl naphthalene-maleic acid copolymer salts, sodium salts of β-naphthalenesulfonic acid folimarin condensates, anionic polymers such as phosphates, and non-polymers such as polyvinyl alcohol, polyvinylpyrrolidone, and polyethylene glycol. Polymer dispersants such as ionic polymers, surfactants, higher alcohol sulfates, liquid fatty acid sulfates, anionic surfactants such as alkyl allyl sulfonates, polyoxyethylene alkyl ethers, Polyoxyethylene alkyl esters, sol Tan alkyl esters, there are a nonionic surfactant such as polyoxyethylene sorbitan alkyl esters, can be used to select these one or more appropriate. It is generally desirable that the amount used is 1 to 20% by weight based on the total amount of the ink.

On the other hand, a dispersing machine used for dispersing the pigment
Any general disperser may be used, and examples thereof include a ball mill, a roll mill, and a sand mill. Among them, a high-speed sand mill is particularly preferred.

The dyes and pigments may be used alone or in combination of dyes, pigments, or a mixture of two or more dyes and pigments.

The dyes and pigments are generally used in a proportion of 0.1 to 20% by weight, preferably in a range of 0.3 to 15% by weight, based on the ink of the present invention.

The solvent used in the ink of the present invention and the ink used in the present invention is water or a mixed solvent of water and a water-soluble organic solvent. Particularly preferred is a mixed solvent of water and a water-soluble organic solvent. In addition, it has a drying prevention (wetting) effect of the ink as a water-soluble organic solvent. Also, as water,
It is preferred to use deionized water instead of ordinary water containing various ions.

Examples of the water-soluble organic solvent used by mixing with water include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol and isobutyl. Alkyl alcohols having 1 to 4 carbon atoms such as alcohol; amides such as dimethylformamide and dimethylacetamide; ketones or keto alcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; polyethylene glycol, polypropylene glycol and the like Polyalkylene glycols; ethylene glycol, propylene glycol, butylene glycol,
Diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, 1,
2,6-hexanetriol, thiodiglycol, 1,
Alkylene glycols having an alkylene group containing 2 to 6 carbon atoms such as 3-butanediol, 1,5-pentanediol, hexylene glycol; glycerin; ethylene glycol methyl (or ethyl or n-propyl or isopropyl or n- Butyl or isobutyl) ether, propylene glycol methyl (or ethyl or n-propyl or isopropyl or n-
Butyl or isobutyl) ether, diethylene glycol methyl (or ethyl or n-propyl or isopropyl or n-butyl or isobutyl) ether, dipropylene glycol methyl (or ethyl or n-propyl or isopropyl or n-butyl or isobutyl) ether, triethylene Glycol methyl (or ethyl or n-propyl or isopropyl or n-butyl or isobutyl) ether, tripropylene glycol methyl (or ethyl or n
Lower alkyl ethers of polyhydric alcohols such as -propyl or isopropyl or n-butyl or isobutyl) ether; pyrrolidones such as 2-pyrrolidone and N-methyl-2-pyrrolidone; 1,3-dimethyl-2-imidazolidinone And the like. Among these many water-soluble organic solvents, polyhydric alcohols such as diethylene glycol and glycerin, and lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl (or ethyl or n-propyl or isopropyl or n-butyl or isobutyl) ether are It is preferred.

The content of the water-soluble organic solvent in the ink is generally 0 to 95% by weight, preferably 10 to 80% by weight, more preferably 20% by weight based on the total amount of the ink.
５０50% by weight.

The content of water at this time is determined in a wide range depending on the kind of the water-soluble organic solvent component, its composition, or desired characteristics of the ink. 10 to 95% by weight, preferably 10 to 7
It is in the range of 5% by weight, more preferably 20-70% by weight.

Although the basic components of the ink used in the present invention are as described above, the main feature of the present invention is that the content of the fatty acid ester contained in the ink is set to 0.6.
% By weight or less. Further, the content of the above fatty acid ester is desirably controlled to 0.3% by weight or less.

The present inventors have conducted intensive studies on the stability of the ink. As a result, the wetting agents and other additives used in the conventional inks include, in the case of synthetic products, by-products during the synthesis and production. In the case of impurities such as garbage and natural products mixed in,
Organic and inorganic impurities such as impurities originally contained are included, and in dyes used in conventional inks, for example, surfactants, leveling agents, sodium chloride, sulfuric acid, etc. It was found that it contained a great number of inorganic and organic impurities such as sodium and alkaline earth metal salts. Also, pigments used in conventional inks contain many inorganic and organic impurities such as impurities contained in the pigment itself and impurities contained in the dispersant. It is known that these impurities cause various problems in ink jet recording and writing instruments, and the present inventor has also diligently removed these inorganic and organic impurities to obtain high-purity ink materials. However, the problem was solved to a considerable extent, but the jet bending in the ink jet system, the change in the ink droplet amount,
It does not completely solve changes in flight speed, etc.
In the ink jet system using thermal energy, it is not always possible to sufficiently prevent foreign matter from depositing on the heating element.

As a result of further detailed research, the present inventor has found that the main cause of these problems is based on the analysis of the nozzle and the orifice surface of the ink jet head that has caused a jet bend and the like and the analysis of deposits on the heating element. It was found to be a fatty acid ester. In addition, jet bending in the ink jet system, change in the appropriate amount of ink,
It has been clarified that the frequency of occurrence of the change in the flying speed and the amount of deposits generated on the heating element in the ink jet system using thermal energy and the amount of the fatty acid ester in the ink show a good correlation, leading to the present invention. .

The reasons why the fatty acid ester causes the above-mentioned problems are considered as follows. That is, the fatty acid ester present in the ink exists in a state of being completely dissolved or dispersed in the ink immediately after the preparation of the ink including the microfiltration step.
Under such environmental changes, the fatty acid ester reacts with a cation represented by an alkali metal present in the ink to form an insoluble salt of the fatty acid. This insoluble salt clogs the nozzles and orifices of the inkjet head,
This causes deposition on the heating element.

The salt of a fatty acid and a cation is remarkably precipitated particularly at a low temperature, and is remarkably precipitated even at a high pH.

The method for adjusting the fatty acid ester content in the ink will be described below.

That is, after the ink material is mixed by a general method and subjected to microfiltration to prepare the ink, the temperature of the ink is raised to normal temperature, preferably, left at 40 ° C. or higher for one day. Thereafter, the temperature of the ink is lowered, and the ink is left at room temperature or lower, more preferably at 10 ° C. or lower for one day. The ink subjected to such aging treatment is subjected to microfiltration again in a temperature environment of room temperature or lower, preferably 10 ° C. or lower.

Here, in the above-mentioned adjusting method, the temperature of the ink is raised to a normal temperature or higher because the reaction between the fatty acid ester contained in the ink and the cation represented by the alkali metal is promoted, This is because it is replaced with an insoluble salt form. Further, the temperature of the ink is thereafter lowered to room temperature or lower in order to promote the precipitation of the insoluble salt of the fatty acid. Further, the reason why the microfiltration is performed at a temperature equal to or lower than room temperature is to remove the precipitated insoluble salt of the fatty acid without dissolving it again in the ink.

The amount of the fatty acid ester in the ink thus obtained is remarkably reduced as compared with that before the treatment, and the amount of metal cations such as alkali metals contained in the ink is also remarkably reduced. Thus, an ideal state with very few impurities is achieved for ink-jet ink.

As described above, one method for adjusting the content of the fatty acid ester in the ink has been described, but the adjusting method is not limited to this method, and any method capable of removing the fatty acid ester or the fatty acid salt can be used. All can be used effectively.

In practice, it is preferable to remove not only the fatty acid ester but also various inorganic salts such as sodium chloride, sulfuric acid and sodium, or calcium and magnesium.

The basic constitution of the ink used in the present invention is as described above. Other conventionally known various dispersants, surfactants, viscosity modifiers, surface tension regulators, pH regulators, antiseptic / antifungal agents, etc. Can be added as needed.

When preparing an ink used for an ink jet recording method of charging a recording liquid, a specific resistance adjuster such as inorganic salts such as lithium chloride, ammonium chloride and sodium chloride is added.

When the present invention is applied to an ink jet system of a type in which ink is ejected by the action of thermal energy, thermal physical properties (for example, specific heat, thermal expansion coefficient, thermal conductivity, etc.) may be adjusted. .

The ink used in the present invention obtained as described above sufficiently solves the problems of the prior art, and the recording characteristics (signal responsiveness, stability of droplet formation, and the like) of the ink-jet method are used as they are. Ejection stability, long-term continuous recording, ink ejection stability after long-time operation suspension), storage stability, fixability to recording material, light resistance of recorded images, water resistance, etc. It is useful as an ink for various types of ink jet recording, and is also suitable as an ink of an ink jet recording method using heat energy which is most resistant to generation of deposits, and gives excellent recording. be able to.

[0052]

Embodiments of the present invention will be described below.

Incidentally, "%" in the text is based on weight.

<Example 1> Liquid composition Acid Yellow 23 (Acid Yellow XX-SF: manufactured by Hoechst) 1% Diethylene glycol 10% Glycerin 2% Pure water 87% After sufficiently mixing and stirring the above materials, 0.8 µm , And the filtrate was heated to 40 ° C. and left for 1 day. Thereafter, the filtrate was further cooled to 5 ° C. and allowed to stand for 1 day. Thereafter, the ink was filtered again with a 0.8 μm membrane filter while maintaining the temperature at 5 ° C.

The content of the fatty acid ester in this ink was measured using a gas chromatograph-mass spectrometer.
17%. Also, among these fatty acid esters,
0.05% was methyl palmitate and 0.10% was methyl stearate. The total amount of fatty acid esters other than methyl palmitate such as methyl behenate and methyl myristate and methyl stearate was 0.02%.

Using this ink, an on-demand type multi-head (ejection orifice diameter 35 μm, heating resistor resistance 150 ohms, which performs recording by applying thermal energy to the ink in the recording head to generate droplets and perform driving) Voltage 3
A recording apparatus having 0 volts and a frequency of 2 kHz, and an on-demand type multi-head (discharge orifice diameter of 40 μm, drive voltage of 30 μm) which performs recording by applying pressure by piezo element vibration to ink in the recording head to generate droplets
Volts, frequency 10 KHz)
When the following T1 to T5 were examined, good results were obtained in all cases.

(T1) Long-term stability: Even after the ink was sealed in a plastic film bag and stored at -30 ° C. and 60 ° C. for 6 months, no precipitation of insoluble components was observed, and the physical properties and color tone of the liquid were not affected. There was no change.

(T2) Discharge stability: room temperature, 5 ° C., 40 ° C.
In each atmosphere, continuous discharge was performed for 24 hours.
Under all conditions, stable high-quality recording was performed throughout.

(T3) Discharge responsiveness: Intermittent discharge for 2 seconds and discharge after standing for 2 months were examined. In each case, there was no clogging at the tip of the orifice, and stable and uniform recording was performed.

(T4) Quality of recorded image: The image recorded on the recording material shown below was high in density and clear. After 6 months exposure to room light, the decrease in density was less than 1%.

[0061] Recording material; high-quality paper "Silver Ring" manufactured by Sanyo Pulp Co., Ltd. High-quality paper "Seven Star" manufactured by Hokuetsu Paper Co., Ltd. Medium-sized paper "Shiro Botan" manufactured by Honshu Paper Co., Ltd. manufactured by Toyo Roshi Co., Ltd. Non-size paper “Toyo Filter Paper No. 4” (T5) Fixing property to various recording materials; 15 seconds after printing on the recording material shown in (T4), rubbing the printed portion with a finger to determine the presence or absence of image displacement and bleeding As a result, all showed no image shift, no bleeding, etc., and exhibited excellent fixability.

<Examples 2 to 4> Inks were prepared using the following liquid compositions in the same manner as in Example 1, and T1 to T5 were examined in the same manner as in Example 1. All of these showed excellent results as in Example 1.

Example 2 Acid Blue 9 (Acid Blue AE-SF: manufactured by Hoechst) 2% Diethylene glycol 12% Pure water 86% → Fatty acid ester content in ink 0.16% Methyl palmitate 0.04% Stearic acid Methyl 0.09%.

Example 3 Acid Red 52 (Acid Rhodamine B-SF: manufactured by Hoechst) 1% Diethylene glycol 10% Triethanolamine 3% Pure water 86% → Fatty acid ester content in ink 0.17% Methyl palmitate 0 0.05% Methyl stearate 0.11%.

Example 4 Direct Black 168 (Direct Black HEF-SF: manufactured by Hoechst) 3% Glycerin 10% Ethanol 5% Pure water 82% → Fatty acid ester content in ink 0.25% Methyl palmitate 0.08 % Methyl stearate 0.15%.

<Embodiment 5> Embodiment 1 was performed using cyan ink.
Examples 1 to 4 using the ink of Example 2 as the magenta ink, the ink of Example 3 as the yellow ink, and the ink of Example 4 as the black ink, respectively.
A full-color photograph was reproduced using the same ink jet recording apparatus as that used in the above. The obtained image was extremely clear and had good color reproduction.

<Examples 6 to 9> Using the same liquid composition as in Examples 1 to 4, the temperature for high-temperature storage in the ink preparation method of Example 1 was set to 35 ° C. The ink was prepared at a temperature of 10 ° C. (Examples 6 to 10).
9). As a result of examining T1 to T5 in the same manner as in Example 1 for each of the prepared inks, T1, T2, T4,
In T5, all showed excellent results as in Example 1. In T3, the jet was bent and the flying speed change was slightly observed in the discharge after leaving for 2 months, but recovered immediately after the start of printing.

Example 6 Same liquid composition as in Example 1 → fatty acid ester content in ink 0.50% methyl palmitate 0.14% methyl stearate 0.29%.

Example 7 Same liquid composition as in Example 2 → fatty acid ester content in ink 0.44% Methyl palmitate 0.12% Methyl stearate 0.28%

Example 8 The same liquid composition as in Example 3 → fatty acid ester content in ink 0.45% methyl palmitate 0.14% methyl stearate 0.26%.

Example 9 Same liquid composition as in Example 4 → fatty acid ester content in ink 0.58% methyl palmitate 0.19% methyl stearate 0.35%.

<Example 10> Pigment carbon black and 1
The mixture was stirred with a 00-fold amount of pure water for 1 hour, filtered three times, and then dried. Using this, a liquid composition having the following composition was prepared and subjected to a dispersion treatment with a pearl mill (trade name, manufactured by Ashizawa Co., Ltd.) to obtain a dispersion.

Incidentally, zirconia was used as the grinding media to be filled in the mill. The liquid-contacting part of the dispersing device used was a ceramic-processed one.

Liquid composition Carbon black (MA-7, manufactured by Mitsubishi Chemical Corporation) 10% Styrene-maleic anhydride copolymer (molecular weight 10,000, acid value 175) 7% glycerin 5% Nikkor TS-30 (manufactured by Nikko Chemicals) 2% pure water 75% triethanolamine 1%

Next, this dispersion was centrifuged to remove coarse particles, and then this dispersion was filtered under pressure through a membrane filter having an average pore diameter of 1 μm, and the filtrate was heated to 40 ° C. for one day. The mixture was allowed to stand, then cooled to 5 ° C., further left for 1 day, and then refiltered with a 1 μm membrane filter at 5 ° C. When the fatty acid ester content of the prepared ink was measured in the same manner as in Example 1, the content was 0.2%.
It was 0%. Further, of these fatty acid esters, methyl palmitate was 0.06% and methyl stearate was 0.11%. This ink was examined for T1 to T5 in the same manner as in Example 1, but showed excellent results as in Example 1.

<Comparative Examples 1 to 4> Using the same liquid composition as in Examples 1 to 4, the ink was prepared without performing the heating, cooling, and re-filtration in the ink preparation method of Example 1 (Comparative Examples 1 to 4). Examples 1-4). As a result of examining T1 to T5 for each of the prepared inks in the same manner as in Example 1, precipitation of insoluble components was observed at T1. At T2 and T3, clogging, jet bend, change in flying speed, and the like were frequently observed and did not recover.

Comparative Example 1 Same liquid composition as in Example 1 → fatty acid ester content in ink 1.62% methyl palmitate 0.55% methyl stearate 0.94%

Comparative Example 2 Same liquid composition as in Example 2 → fatty acid ester content in ink 1.40% methyl palmitate 0.49% methyl stearate 0.88%

Comparative Example 3 Same liquid composition as in Example 3 → fatty acid ester content in ink 1.35% methyl palmitate 0.44% methyl stearate 0.79%

Comparative Example 4 Same liquid composition as in Example 4 → fatty acid ester content in ink 1.94% methyl palmitate 0.65% methyl stearate 1.14%.

[0081]

As is apparent from the above description, in the aqueous ink of the present invention and the ink jet recording method using the aqueous ink, the content of the fatty acid ester contained in the ink is 0.6% by weight or less. It is more preferable that the content of the fatty acid ester contained in the ink is 0.3% by weight or less. Also, good printing is possible without causing clogging of nozzles and orifices, bending in the flight direction, change in ink drop amount, and change in flight speed.
Further, when the water-based ink of the present invention is used in the thermal ink jet system using thermal energy, foreign matters are hardly deposited on the surface of the heating element, and thus there is an effect of improving the durability of the head.

Claims (11)

(57) [Claims] 1. A water-based ink containing a water-soluble dye or pigment as a colorant, wherein the total content of fatty acid esters contained in the ink is 0.6% by weight or less. 2. The method according to claim 1, wherein the total content of the fatty acid ester is 0.1%.
2. The aqueous ink according to claim 1, wherein the content is 3% by weight or less. 3. The aqueous ink according to claim 1, wherein the fatty acid ester is methyl palmitate and methyl stearate. 4. The content of the methyl palmitate of 0.
The aqueous ink according to claim 3, wherein the content of the methyl stearate is 2% by weight or less, and the content of the methyl stearate is 0.4% by weight or less. 5. The method according to claim 1, wherein the content of the methyl palmitate is 0.1%.
The aqueous ink according to claim 3, wherein the content of the methyl stearate is 1% by weight or less and the content of the methyl stearate is 0.2% by weight or less. 6. An ink-jet recording method using a water-based ink containing a water-soluble dye or pigment as a colorant as a recording liquid, wherein the total content of fatty acid esters is 0.1%.
An ink jet recording method, characterized in that recording is performed on a recording material by ejecting the aqueous ink of 6% by weight or less. 7. The method according to claim 1, wherein the total content of the fatty acid ester is 0.
7. The ink jet recording method according to claim 6, wherein the recording is performed on the recording material by ejecting the aqueous ink at 3% by weight or less. 8. The ink jet recording method according to claim 6, wherein the fatty acid esters contained in the aqueous ink are methyl palmitate and methyl stearate. 9. When the content of methyl palmitate contained in the aqueous ink is 0.2% by weight or less, and the content of methyl stearate contained in the aqueous ink is 0.4% by weight or less. The ink jet recording method according to claim 8, wherein: 10. When the content of methyl palmitate in the aqueous ink is 0.1% by weight or less and the content of methyl stearate in the aqueous ink is 0.2% by weight or less. The ink jet recording method according to claim 8, wherein: 11. The thermal recording method according to claim 6, wherein the recording method is a thermal ink jet method in which the aqueous ink is ejected using thermal energy from a heating element provided in an ink chamber filled with the aqueous ink. Or 7 or 8
Or the ink jet recording method according to 9 or 10.