JP2003253167A - Water-base recording fluid and recording process, ink cartridge, and inkjet recorder using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide water-base recording liquid having such high driability as to permit high-speed setting favorable for high-speed printing and as not to cause strike-through and to therefore permit both-side setting, to provide an inkjet recording process using the liquid, and to provide an ink cartridge and an inkjet recording using the liquid. <P>SOLUTION: The water-base recording liquid is an ink composition essentially consisting of a water-soluble or water-dispersible colorant, water, a wetting agent, and 2,4-diethyl-1,5-pentanediol. The recording liquid is held in the recording liquid holder of the ink cartridge, and the ink cartridge is set in the inkjet recorder. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous recording liquid suitable for ink jet recording to which an on-demand method such as a piezo method or a thermal method or a continuous ejection method such as a charge control method is applied, and particularly to non-coated plain paper. On the other hand, the present invention relates to an aqueous recording liquid comprising an ink composition exhibiting excellent properties, and further used for an aqueous writing instrument, a recorder and a pen plotter. The present invention also relates to a recording method, an ink cartridge and an inkjet recording device using this aqueous recording liquid.

[0002]

2. Description of the Related Art In recent years, ink jet recording methods have rapidly spread due to their advantages of small size, low price, low running cost and low noise. Electrophotographic transfer paper, printing paper, typewriter paper, wire dots. Inkjet printers (inkjet recording devices) capable of printing on various non-coated plain papers such as printer papers, word processor papers, letter papers, and report papers are also on the market. In these ink jet printers, there has been proposed a recording liquid (ink) having improved dryness so that a higher quality image can be obtained. However, it is difficult to satisfy all of the color reproducibility of an image, water resistance, light resistance, image drying property, image blurring and ejection reliability. In particular, in the case of a color printer, even if there is no image quality deterioration in the yellow, magenta, and cyan single-color printing portions, the image quality deterioration easily occurs in the two-color overlapping portion of red, green, and blue. In particular, when drying is performed without using a fixing device, it is known that the drying property is improved by increasing the permeability as in JP-A-55-29546, but this method causes remarkable bleeding on paper. There is a problem that occurs.

Further, Japanese Patent Publication No. 60-23793 discloses that a dialkylsulfosuccinate as a surfactant improves the drying property and causes less image deterioration. The diameters are significantly different,
There is a problem that the image density is significantly reduced. Further, Japanese Patent Publication No. Sho 58-6752 discloses a quick-drying ink with less bleeding by improving the permeability by using a surfactant which is an ethylene oxide adduct having an acetylene bond.

However, in an ink using a direct dye such as DBK168 depending on the colorant (coloring material),
The drying speed is not improved due to the hydrophobic interaction with the coloring material, and in the ink using pigment such as carbon black, the pigment is likely to aggregate and the nozzle is easily clogged and the ink jet direction is bent. There is such a problem.

Alternatively, Japanese Patent Application Laid-Open No. 8-113739 proposes an ink containing a dye and a water-soluble glycol ether in order to improve the drying speed.
JP-A-0-95941 proposes an ink composition comprising a pigment, a glycol ether such as diethylene glycol mono-n-butyl ether, and water.
However, in order to improve the drying speed, it is necessary to add a large amount of glycol ethers, which is not preferable in terms of odor of ink and safety.

Further, Japanese Patent Application Laid-Open No. 56-57862 discloses an ink to which a strongly basic substance is added. Although it is effective for rosin-sized acidic paper, it is effective for alkyl ketene dimer and alkenyl sulfosuccinic acid. Has no effect on paper with sizing agent. Moreover, even with acidic paper, the effect of overlapping two colors is not effective.

Further, JP-A-2-138374 proposes an aqueous recording ink comprising a water-soluble dye, water, and benzyl ether having a specific structure. Among them, in order to further improve the ink permeability, vegetable oil,
Oily substances such as unsaturated fatty acids, higher alcohols, fatty acid esters, and mineral oil, and 2-ethyl-1,6-hexanediol, diethylene glycol hexyl ether, which have a hydroxyl group in the molecule and are sparingly soluble or slightly soluble in water, It has been proposed to add an ethylene oxide adduct of acetylene glycol (addition mole number of 5 or less), ethylene glycol benzyl ether, and the like. But,
These inks have a safety problem, and oily substances, sparingly water-soluble, slightly soluble solvents, benzyl ether and the like are separated depending on the environmental temperature, resulting in a very great stability problem.

Japanese Patent No. 2894568 discloses a composition containing a dye and a liquid medium, wherein 60% by weight is contained in the liquid medium.
An inkjet ink containing the above water and 0.2 to 30% by weight of an alkylene glycol having 7 to 10 carbon atoms has been proposed. Preferred specific examples of the "alkylene glycol having 7 to 10 carbon atoms" are 1,7-heptanediol, 2,6-heptanediol, 2,4-dimethyl-2,4-pentanediol, 3-ethyl-1,
3-Pentanediol and the like are exemplified. Inclusion of these compounds in the ink "improves ink bleeding, drying and penetration on plain paper", "balances in terms of bleeding and penetration", and "reliability in clogging prevention" It is said that it is possible to provide "highly effective" ink. However, actually, addition of these exemplified compounds does not sufficiently improve the permeability of the ink, so that the drying property is low, and bleeding easily occurs depending on the paper type. It was

Further, Japanese Patent No. 2,714,482 contains an aliphatic diol compound having a specific structure having at least 6 carbon atoms and having a solubility of at least 4.5 parts by weight in 100 parts by weight of water at 25 ° C. Inkjet inks have been proposed. These diol compounds include 2-ethyl-2-methyl-1,3-propanediol, 3,3-dimethyl-1,2-butanediol, 2,
2-diethyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2,4-
Dimethyl-2,4-pentanediol, 2,5-dimethyl-2,5-hexanediol, 5-hexene-1,2
-Although diols and the like are exemplified, it cannot be said that the inks containing any of them have sufficient permeability, and color bleeding and feathering occurred.

Therefore, the present inventors have conducted extensive studies and have proposed an aqueous ink containing 2-ethyl-1,3-hexanediol and a recording method using the same for the purpose of enhancing penetrability (JP-A-6- 157959). 2-Ethyl-1,3-hexanediol contained in the water-based ink of the present invention is described in the above-mentioned Japanese Patent No. 2894568.
Not only is it not included in the exemplified compounds, but it has been discovered by the present inventors after extensive studies from a wide variety of compounds. By containing 2-ethyl-1,3-hexanediol, it is possible to provide an ink composition which satisfies various properties as an inkjet ink, has excellent penetrability and dryness, and has improved image quality deterioration. It was possible to provide a recording method for favorably forming an image using the ink composition. Also, 2-ethyl-1,
By adding a small amount of 3-hexanediol, an ink having high ejection stability driven by high frequency and high safety is provided.

However, due to the rapid progress of technology in recent years, the output speed of ink jet printers is increasing and it is expected that the output speed will be further increased in the future. Under such circumstances, it is required that the ink does not cause color bleeding even in high-speed printing, and that the ink is immediately dried without being contaminated even if it is rubbed after output. In general, highly dry inks have the drawbacks of improving the permeability to paper while lowering the image density and increasing the strike-through density due to the colorant (coloring material) penetrating in the thickness direction of the paper. is doing. Especially, it is clear that double-sided printing is indispensable from the viewpoint of so-called paper consumption, which is related to the development of inkjet printers and environmental problems. It can be said that an aqueous recording liquid) is required.

As described above, various properties as an ink-jet ink are satisfied even now, the penetrability and the drying property are excellent regardless of the colorant (coloring material) type and the paper type, and the image quality and strikethrough are improved. The desire for inkjet inks remains strong. In recent years, a system for reading recorded information with infrared rays or ultraviolet rays, which is usually invisible, has been put into practical use in fields such as bar code printing and postmark printing such as mail. From the standpoint of environmental pollution, it has been studied to make the inks used in these aqueous solutions as well, and in order to support the high-speed processing that is essential for such systems, an aqueous recording liquid that is highly penetrating while being aqueous Is needed.

[0013]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to overcome the problems of the prior art described above and to provide high-speed printing compatible with high-speed printing. (EN) Provided are a highly dry aqueous recording liquid capable of double-sided printing without strikethrough, an inkjet recording method using the aqueous recording liquid, and a device (ink cartridge, ink jet recording device) using the recording liquid. It is in.

[0014]

According to the present invention, at least a coloring material which is dissolved or dispersed in water, water, a wetting agent, and 2,4.
By containing diethyl-1,5-pentanediol as an ink composition, it is possible to provide a highly dry aqueous recording liquid without strike-through which enables high-speed printing and double-sided printing, and at the same time, to provide the aqueous recording liquid. By using the ink, an ink jet recording method corresponding to a high printing speed was achieved, and at the same time, an ink cartridge and an ink jet recording apparatus using the recording liquid were realized. Hereinafter, the present invention will be specifically described.

The invention of claim 1 comprises an ink composition containing at least a colorant soluble or dispersible in water, water, a wetting agent, and 2,4-diethyl-1,5-pentanediol. It is an aqueous recording liquid characterized by the following.

By using an aqueous recording medium comprising the ink composition of claim 1, the image quality is improved, such as excellent penetrability and dryness regardless of the coloring material (colorant) or paper type, and less bleeding. An aqueous recording liquid is provided. Further, even if the content of 2,4-diethyl-1,5-pentanediol is small, high penetrating properties can be obtained, and an aqueous recording liquid excellent in safety and odor can be provided. Furthermore, in addition to the above-mentioned high penetration characteristics and excellent image quality, it is possible to provide an aqueous recording liquid having high safety, storage stability and inexpensiveness.

The invention of claim 2 is characterized in that the content of the 2,4-diethyl-1,5-pentanediol is 0.1 to 5% by weight based on the total amount of the ink composition. The aqueous recording liquid according to claim 1.

When the content of 2,4-diethyl-1,5-pentanediol is within the above range, the penetration characteristics are high,
A stable aqueous recording liquid having excellent image quality, causing no phase separation, is provided.

The invention of claim 3 is the aqueous recording liquid according to claim 1 or 2, wherein the content of the wetting agent is 5 to 50% by weight based on the total amount of the ink composition. is there.

By setting the content of the wetting agent within the above range, it is difficult to cause clogging even when water in the aqueous recording medium made of the ink composition is evaporated, and even if clogging occurs, it is easy. Provided is a recording liquid capable of recovering a normal printing state by various cleaning operations.

According to a fourth aspect of the present invention, a surfactant is further added to the ink composition in an amount of 0.
The aqueous recording liquid according to any one of claims 1 to 3, which is contained in the range of 01 to 5% by weight.

By using a surfactant in combination as an ink composition, a synergistic effect is exerted, and reduction of image density and strike-through which are problems in the conventional penetrating type ink having improved penetrability are prevented. An aqueous recording liquid is provided. In addition, since it is possible to obtain high penetrability by adding a small amount as compared with the aqueous recording liquid containing each of them, compared with conventional inks in which a large amount of polyhydric alcohol ethers and the like are added to increase penetrability. There are also advantages such as less solvent odor.

According to a fifth aspect of the present invention, in the aqueous recording liquid according to the fourth aspect, the surfactant contains at least a polyoxyethylene alkyl ether acetate represented by the following general formula (1). is there.

[0024]

Embedded image R ₁ —O— (CH ₂ CH ₂ O) _m —CH ₂ COOM (1) (In the formula, R ₁ is an alkyl group having 6 to 14 carbon atoms and may be branched, and m is 3 to A natural number of 12, M represents an alkali metal ion, a quaternary ammonium, a quaternary phosphonium, or an alkanolamine.)

By containing the above polyoxyethylene alkyl ether acetate as a component, the filling of an image is improved, and an aqueous recording liquid having an excellent effect in increasing the image density is provided.

The invention according to claim 6 is characterized in that the wetting agent is a compound selected from at least one of diethylene glycol, triethylene glycol or glycerin. It is a liquid.

When an aqueous recording liquid containing at least one wetting agent selected from the above compounds in its composition is used in an ink jet recording apparatus, the occurrence of clogging due to evaporation of water near the nozzle is prevented, and 2,4-diethyl-1,5
-Acts as a dissolution aid for pentanediol. This provides an aqueous recording liquid with further improved storage stability and further improved jetting stability.

According to a seventh aspect of the invention, in the ink composition, 2-ethyl-1,3-hexanediol, 2,
7. The aqueous recording liquid according to claim 1, containing at least one compound selected from 2,4-trimethyl-1,3-pentanediol.

By using one or more selected from the above-mentioned compounds in combination as a composition component, a synergistic effect is exerted, and the problem of image density which has been a problem in the conventional penetrating type ink having enhanced penetrability is exhibited. Provided is an aqueous recording liquid which prevents deterioration and strike-through. In addition, it is possible to obtain high penetrability by adding a small amount of each of the above compounds as compared to the ink containing each of them alone, and to compare with an ink in which a large amount of ethers of a single polyhydric alcohol is added to increase the penetrability. An aqueous recording liquid having advantages such as little solvent odor is provided.

The invention of claim 8 is the aqueous recording liquid according to any one of claims 1 to 7, wherein the ink composition further contains 2-pyrrolidone.

By containing 2-pyrrolidone, the permeation of the ink into the paper is not impaired, the permeation of the ink into the paper layer beyond the necessary amount after penetrating the paper is suppressed, and the color near the paper surface is colored. A water-based recording liquid which can retain a material and has an excellent effect of preventing strike-through while further improving the image density is provided.

The invention according to claim 9 is the aqueous recording liquid according to any one of claims 1 to 8, wherein the coloring material is a pigment.

By using a pigment as the coloring material, water resistance and light resistance are improved, and an excellent water-based recording liquid having high penetrability and high image density and less strike-through is provided.

The invention according to claim 10 is the aqueous recording liquid according to claim 9, wherein the average particle diameter of the pigment is in the range of 10 nm to 200 nm.

When the average particle diameter of the pigment is within the above range, the dispersion stability becomes good, the storage stability and the ejection stability in the ink jet recording method are excellent, and
Provided is an excellent aqueous recording liquid with less image strike-through.

An eleventh aspect of the present invention is an aqueous recording liquid obtained by adding a pigment dispersion liquid, in which a pigment is dispersed in water by a dispersant, to an ink composition, wherein a carboxyl group is bound to the dispersant. It is an aqueous recording liquid characterized by the following.

By using a dispersant having a carboxyl group bonded, an extremely high-quality image with less blurring can be formed in addition to a higher image density and a lower strike-through density, and recording after printing can be performed. An aqueous recording liquid in which the water resistance of a medium is further improved is provided.

A twelfth aspect of the invention is an aqueous recording liquid obtained by adding a pigment dispersion liquid in which a pigment is dispersed in water with a dispersant to an ink composition, wherein a hydrophilic group is bonded to the surface of the pigment to form a surface. It is an aqueous recording liquid characterized by being modified.

By using a pigment having a modified surface and a hydrophilic group bonded thereto, an aqueous recording liquid having extremely high storage stability and reliability can be provided.

The invention according to claim 13 is the aqueous recording liquid according to claim 12, wherein the hydrophilic group is a carboxyl group.

By using a surface-modified pigment in which the hydrophilic group bonded to the pigment is a carboxyl group, an extremely high-quality image with less bleeding as well as a lower strike-through density with a higher image density can be obtained. An aqueous recording liquid which can be formed and has further improved water resistance of a recording medium after printing is provided.

According to a fourteenth aspect of the present invention, there is provided a recording method of forming an image on a recording medium by ejecting and ejecting the aqueous recording liquid as droplets from an ejection port of a recording head, the aqueous recording liquid comprising the first to thirteenth aspects. A recording method comprising the aqueous recording liquid according to any one of the claims.

Since the aqueous recording liquid comprising the ink composition of the present invention does not undergo phase separation and does not aggregate or thicken, it is ejected and ejected as droplets from a fine ejection port to form an image on the recording medium. Suitable for use in the method. There is provided a recording method in which printing is suspended for a long period of time, and even when the water content of the ink that has accumulated near the nozzles of the inkjet head is evaporated, good printing can be easily performed with a simple cleaning operation without causing clogging.

According to a fifteenth aspect of the present invention, in the recording method, thermal energy is applied to the aqueous recording liquid to eject and fly as droplets from the ejection port of the recording head to form an image on the recording medium. The recording method according to claim 14.

The method of forming an image by applying thermal energy to the aqueous recording liquid is particularly suitable because the wettability to the thermal element is improved, whereby a recording method excellent in ejection stability and frequency stability is obtained. Will be provided.

According to a sixteenth aspect of the present invention, the recording medium contains pulp fibers as a main component, and has a sizing degree of 10 s or more and an air permeability of 5 to 50 s.
The recording method described in 5 above.

When printing is performed with the aqueous recording liquid of the present invention using a recording medium containing pulp fibers as a main component and having the above-mentioned size and air permeability, even if printing is performed on both sides of the recording medium by the ink jet recording method, A low-cost recording method is provided in which the image on the back side does not interfere with the recognition of the front side image.

A seventeenth aspect of the present invention is a recording method for forming an image on a recording medium by ejecting and ejecting the aqueous recording liquid according to any one of the first to thirteenth droplets from an ejection port of a recording head. And the discharge amount V (pl) per droplet
Is a recording method characterized by satisfying the following expression (a).

[0049]

## EQU2 ## 2.5 × 10 ⁸ / R ^2.6 ≦ V ≦ 6.0 × 10 ⁸ / R ^2.6 (a)

(In the formula, R is a maximum ejection density of droplets when recording is performed on a recording medium having a pulp fiber as a main component and having a size degree of 10 s or more and an air permeability of 5 to 50 s. The unit is It is expressed by dpi (dot per inch), and the unit of the droplet discharge amount V is picoliter (pl).
It is represented by. )

By using the aqueous recording liquid of the present invention to perform recording by satisfying a predetermined relationship between the ejection amount per droplet ejected from the recording head and the impact density of the droplet, the dot dropout can be achieved. There is provided a recording method capable of obtaining a high-quality image having high density and less bleeding, which does not have white lines or white streaks.

According to an eighteenth aspect of the present invention, the aqueous recording liquid according to any one of the first to thirteenth aspects is ejected and ejected as a plurality of liquid droplets from the same or separate ejection ports of the recording head to form pixels on the recording medium. A recording method for forming an image so that at least a part of the areas overlap each other, wherein a difference in ejection time between two droplets causing an overlap on the recording medium is 0.125 milliseconds or less. Is.

By utilizing the high permeability of the aqueous recording liquid of the present invention, there is provided a recording method for recording a high quality image at a very high speed under the above high speed ejection conditions.

According to a nineteenth aspect of the invention, there is provided an ink cartridge having a recording liquid storage section for storing the recording liquid, wherein the recording liquid is the aqueous recording liquid according to any one of the first to thirteenth aspects. It is an ink cartridge that does.

When the aqueous recording liquid of the present invention is used as the recording liquid in the above-mentioned constitution having the recording liquid storage portion for storing the above-mentioned recording liquid, it has high penetration characteristics, high reliability, safety and excellent image characteristics. There is provided an ink cartridge capable of

According to a twentieth aspect of the present invention, there is provided an ink cartridge having a recording liquid storage portion for storing the recording liquid and a recording head portion for ejecting recording liquid droplets, wherein the recording liquid is one of the first to thirteenth embodiments. An ink cartridge comprising the aqueous recording liquid according to any one of the claims.

In the above-described structure having the recording liquid storage portion for storing the recording liquid and the recording head portion for ejecting the recording liquid droplets, if the aqueous recording liquid of the present invention is used as the recording liquid, high penetrability is obtained. In addition, an ink cartridge is provided that enables high reliability, safety, and excellent image characteristics.

According to a twenty-first aspect of the present invention, there is provided an ink jet recording apparatus comprising an ink cartridge having a recording liquid storage section for storing the recording liquid, and a recording head for ejecting recording liquid droplets, wherein the recording liquid is An inkjet recording apparatus comprising the aqueous recording liquid according to any one of claims 1 to 13.

When the aqueous recording liquid of the present invention is used as the recording liquid in the ink jet recording apparatus having the above-mentioned structure, it is possible to obtain high penetration characteristics compatible with high-speed printing, high reliability, safety and excellent image characteristics. A recording device is provided.

According to a twenty-second aspect of the present invention, there is provided an ink jet recording apparatus equipped with an ink cartridge having a recording liquid container for containing a recording liquid and a recording head for ejecting recording liquid droplets. Claims 1-13
An ink jet recording apparatus comprising the aqueous recording liquid according to any one of 1.

When the aqueous recording liquid of the present invention is used as the recording liquid in the ink jet recording apparatus having the above-mentioned constitution, it has high penetration characteristics compatible with high-speed printing similar to claim 21, and high reliability and safety. A recording device is provided that enables image characteristics.

[0062]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. The present inventors include 2,4-diethyl-1,5-pentanediol as an ink composition to increase the surface tension of 50 m for the purpose of enhancing the penetrability into paper.
Not only is it possible to lower the N / m or less, improve the wettability between the ink and the paper surface, and increase the permeation rate into the paper, but it is also possible to increase the penetrability centered on the conventionally known surfactants. Image deterioration is extremely small compared to the case of raising it,
Furthermore, when 2,4-diethyl-1,5-pentanediol is used, the permeation rate is almost the same regardless of the kind of the coloring material, and therefore the usable coloring material is limited. Instead, they have found that any of the coloring materials that have been conventionally used for inkjet can be used, and have reached the present invention.

The above 2,4 used in the ink composition of the present invention
-Diethyl-1,5-pentanediol is preferably 0.1 to 5% by weight, more preferably 0.1 to 3% by weight, based on the total amount of the ink composition. If it is less than 0.1% by weight, the effect of enhancing penetrability is small, and if it is added in an amount of more than 5% by weight, it does not dissolve stably in the ink composition, causing problems in storage stability as an aqueous recording liquid and jetting stability in inkjet. Occurs.

The surface tension in the present invention is an index showing the penetrability into paper, and particularly shows the dynamic surface tension in a short time of 1 second or less after the surface is formed, and the static surface tension measured at the saturation time. Is different from. As a measuring method, JP-A-63-31
Although any conventionally known method described in Japanese Patent No. 237, etc. can measure a dynamic surface tension of 1 second or less, any method can be used. In the present invention, the maximum bubble pressure method is used. This method is a method in which a capillary is vertically inserted into a liquid, and the dynamic surface tension is obtained by measuring the maximum pressure required for sending air and releasing generated bubbles. The surface tension of the aqueous recording liquid of the present invention is preferably 50 mN / m or less, and more preferably 40 mN / m or less to obtain excellent drying properties.

Further, in a recording method such as a so-called bubble method or thermal method in which thermal energy is applied to the ink to eject the ink as droplets from the fine holes to perform recording, it is conventionally 2 in order to obtain ejection stability. -There is a method of adding propanol, but by adding 2,4-diethyl-1,5-pentanediol instead of this, the wettability to the thermal element is improved, and the ejection stability is improved even with a small amount of addition. And frequency stability are obtained and the safety issues associated with the use of 2-propanol are also improved.

A wetting agent is added in an amount of 5% by weight to 50% for the purpose of preventing clogging caused by drying the ink and improving dissolution stability.
By containing it in a weight percentage, the aqueous recording liquid of the present invention does not easily cause clogging at the ejection port of the inkjet head (recording head) even when water in the ink evaporates, and normal printing can be performed. Instead, they found that even if clogging occurs, the normal printing state can be restored by a simple cleaning operation.

Further, 2,4-diethyl-1,5-pentanediol and a wetting agent, 2-ethyl-1,3-hexanediol, 2,2,4-trimethyl-1,3-pentanediol and / or It has been found that, by using a combination with a surfactant, a synergistic effect is exerted, and reduction of image density and strike-through which are problems in the conventional penetrating type ink having improved penetrability are prevented. In addition, compared with the ink containing each of the above components alone, when combined, high penetrability can be obtained by adding a small amount. Therefore, there is an advantage that the solvent odor is less than that of the conventional ink in which a large amount of ethers of polyhydric alcohol and the like is added to improve the permeability.

The water-based recording liquid of the present invention uses water as a liquid medium. To make the ink have desired physical properties, to prevent clogging due to drying of the ink, or to improve the dissolution stability of the ink. For the purpose of, for example, the following water-soluble organic solvent can be used as a wetting agent.

For example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,5-pentanediol, 1,6-hexanediol, glycerin,
Polyhydric alcohols such as 1,2,6-hexanetriol, 1,2,4-butanetriol, 1,2,3-butanetriol and petriol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl Polyhydric alcohol alkyl ethers such as ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether and propylene glycol monoethyl ether, polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether , 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-
Dimethyl imidazolidinone, ε-caprolactam, γ-
Nitrogen-containing heterocyclic compounds such as butyrolactone, amides such as formamide, N-methylformamide, N, N-dimethylformamide, amines such as monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine and triethylamine,
Sulfur-containing compounds such as dimethyl sulfoxide, sulfolane, thiodiethanol, propylene carbonate, ethylene carbonate and the like. These solvents may be used alone or in combination with water.

The amount of these wetting agents added to the ink composition is 5% by weight to 50% by weight, and preferably 8% by weight to 30% by weight, as described above. If it is less than 5% by weight, there is a problem that the storage stability of the ink and the ejection stability in the inkjet are inferior, and if it is more than 50% by weight, the ejection stability in the inkjet is inferior due to an increase in viscosity.

Among the above-mentioned wetting agents, it is particularly preferable that diethylene glycol, triethylene glycol and / or glycerin is contained to prevent clogging due to drying of the ink, that is, prevention of defective ejection characteristics due to water evaporation and an aqueous recording comprising the ink composition of the present invention. An excellent effect is obtained in improving the dissolution stability of the liquid. It was also found that when 2-pyrrolidone is added to the ink composition, the penetrability of the ink into paper is not impaired, and an excellent effect is obtained in improving the image density and preventing strike-through. This is 2-
It is presumed that the inclusion of pyrrolidone makes it easier for the ink to wet and spread on the paper surface, and because the penetration in the thickness direction of the paper is relatively suppressed, the coloring material tends to stay near the paper surface. . The amount of 2-pyrrolidone added is
It is preferably 0.05% by weight to 8% by weight, and more preferably 0.5% by weight to 4% by weight.

Examples of the surfactant used in the present invention include anionic surfactants such as dodecylbenzene sulfonate, polyoxyethylene alkyl ether acetate, lauryl acid salt and ammonium salt of polyoxyethylene alkyl ether sulfate, Cationic surfactants such as quaternary ammonium salts, amphoteric surfactants such as imidazoline derivatives, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene alkylamines, polyoxyethylene Noni such as alkyl amide, polyoxyethylene propylene block polymer, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, ethylene oxide additive of acetylene alcohol, etc. Emissions-based surfactants.

The amount of the above-mentioned surfactant added to the ink composition is 0.01% by weight to 5% by weight, preferably 0.
It is 5% to 3% by weight. If it is less than 0.01% by weight, the effect of addition is not obtained, and if it is more than 5% by weight, the penetrability into the recording medium becomes unnecessarily high, and there is a problem that the image density is lowered or strikethrough occurs. In particular, anionic surfactants are preferable, among which the following general formula (1)
The polyoxyethylene alkyl ether acetate represented by is more preferable. When this is used, the filling of the image is improved and an excellent effect is obtained in increasing the image density.

[0074]

Embedded image R ₁ —O— (CH ₂ CH ₂ O) _m —CH ₂ COOM
… (1)

(In the formula, R ₁ is an alkyl group having 6 to 14 carbon atoms and may be branched, m is a natural number of 3 to 12, M is an alkali metal ion, quaternary ammonium, quaternary phosphonium, or alkanol. Represents an amine.)

Specific examples of the compound represented by the above general formula (1) are shown in the following formulas (1-1) to (1-14) in the free acid form, but the compounds are not limited thereto.

[0077]

[Chemical 4]

The above compounds may be used alone or in combination of two or more. Commercially available surfactants containing this compound as a main component include ECTD3NEX (in the general formula (1), R ₁ : tridecyl group, m: 3, available from Nikko Chemicals Co., Ltd.).
M: Na), ECT3 (R ₁ : tridecyl group, m: 3,
M: H), ECTD6NEX (R ₁ : tridecyl group,
Surfactants such as m: 6, M: Na) can also be used.

When an alkali metal ion, quaternary ammonium, quaternary phosphonium, or alkanolamine is used as the counter ion of the compound represented by the general formula (1), excellent solubility stability is exhibited. Furthermore, it is more preferable to use sodium, lithium and / or a quaternary ammonium, quaternary phosphonium or alkanolamine cation represented by the following general formula (2) as the counter ion because the solubility of the cation is further increased.

[0080]

[Chemical 5]

(In the formula, Y represents nitrogen or phosphorus, and R ₁
To R ₄ each represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a hydroxyalkyl group, or a halogenated alkyl group. )

For example, when a lithium salt is used as the counter ion of the general formula (1), lithium hydroxide is added, and the quaternary ammonium, phosphonium or alkanolamine cation of the general formula (2) is added. When using ions or the like, specifically, the following formulas (2-1) to (2-
It is carried out by adding the hydroxide shown in 9).

[0083]

[Chemical 6]

[0084]

[Chemical 7]

[0085]

[Chemical 8]

[0086]

[Chemical 9]

[0087]

[Chemical 10]

[0088]

[Chemical 11]

[0089]

[Chemical 12]

[0090]

[Chemical 13]

[0091]

[Chemical 14]

In addition to 2,4-diethyl-1,5-pentanediol, penetrants added for the purpose of adjusting the surface tension include diethylene glycol monophenyl ether, ethylene glycol monophenyl ether and ethylene glycol monophenyl ether. Alkyl and aryl ethers of polyhydric alcohols such as allyl ether, diethylene glycol monophenyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, propylene glycol monobutyl ether, and tetraethylene glycol chlorophenyl ether, fluorine-based surfactants, ethanol, 2- Examples thereof include lower alcohols such as propanol, but diethylene glycol monobutyl ether or triethylene glycol is particularly preferable. It is a mono-butyl ether.

The coloring material used in the present invention may be either a pigment and / or a dye. As the water-soluble dye used as the coloring material, dyes classified in the color index into acid dyes, direct dyes, basic dyes, reactive dyes and food dyes are used. These dyes may be used as a mixture of a plurality of types, or may be used as a mixture with other dyes such as pigments as required. These coloring materials are added within a range that does not impair the effects of the present invention. Specific examples of these dyes are given below.

Acid dyes and food dyes include C.I. I.
Acid Yellow 17,23,42,44,79,1
42; C.I. I. Acid Red 1, 8, 13, 14,
18, 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. Acid Black 1, 2, 7, 24, 26,
94; C.I. I. Food Yellow 2, 3, 4; C.I. I.
Hood Red 7, 9, 14; C.I. I. Food Black 1, 2 etc. are mentioned.

As the direct dye, C.I. I. direct·
Yellow 1, 12, 24, 26, 33, 44, 50, 1
20, 132, 142, 144, 86; C.I. I. Direct Red 1, 4, 9, 13, 17, 20, 28, 3
1, 39, 80, 81, 83, 89, 225, 227;
C. I. Direct Orange 26, 29, 62, 10
2; C.I. 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, 38, 51, 56,
71, 74, 75, 77, 154, 168, 171 and the like.

As the basic dye, C.I. I. basic·
Yellow 1, 2, 11, 13, 14, 15, 19, 2
1, 23, 24, 25, 28, 29, 32, 36, 4
0, 41, 45, 49, 51, 53, 63, 465, 6
7, 70, 73, 77, 87, 91; C.I. I. Basic Red 2, 12, 13, 14, 15, 18, 22,
23, 24, 27, 29, 35, 36, 38, 39, 4
6, 49, 51, 52, 54, 59, 68, 69, 7
0, 73, 78, 82, 102, 104, 109, 11
2; C.I. I. Basic Blue 1, 3, 5, 7, 9,
21, 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 etc. can be mentioned.

As the reactive dye, C.I. I. Reactive Black 3, 4, 7, 11, 12, 17; C.I. I. Reactive Yellow 1, 5, 11, 13, 14, 2
0, 21, 22, 25, 40, 47, 51, 55, 6
5, 67; C.I. I. Reactive Red 1, 14, 1
7, 25, 26, 32, 37, 44, 46, 55, 6
0, 66, 74, 79, 96, 97; C.I. I. Reactive Blue 1, 2, 7, 14, 15, 23, 32, 3
5, 38, 41, 63, 80, 95 and the like.

As the dye, an acid dye and a direct dye can be preferably used, and excellent effects such as improvement in dissolution stability of the aqueous recording liquid of the present invention and excellent color tone, water resistance and light resistance can be obtained. The addition amount of the dye as a coloring material in the ink composition is preferably 0.5 to 25% by weight, more preferably 2 to 15% by weight.

As the pigment, an inorganic pigment or an organic pigment can be used without any particular limitation. Compared to dyes, they are dispersed as particles rather than dissolved in the ink, so even ink with the same penetrating characteristics does not easily penetrate deep into the paper, resulting in high image density and good image quality with less strikethrough. It will be possible to obtain.

As the inorganic pigment, titanium oxide, iron oxide,
Calcium carbonate, barium sulfate, aluminum hydroxide,
It is possible to use barium yellow, cadmium red, chrome yellow, or carbon black produced by a known method such as a contact method, a furnace method, or a thermal method. As the organic pigment, azo pigments (azo lake, insoluble azo pigment, condensed azo pigment,
(Including chelate azo pigments), polycyclic pigments (eg,
Phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, quinoflaron pigments, etc., dye chelates (for example, basic dye chelates, acidic dye mers) Chelate), nitro pigment, nitroso pigment or aniline black can be used. Among these pigments, those having a good affinity with water are preferably used. The addition amount of the pigment as a coloring material in the ink composition is 0.5 to 25% by weight.
Is preferable, and more preferably 2 to 15% by weight.

Specific examples of the pigment preferably used in the present invention are shown below. For black, carbon black (CI pigment black 7) such as furnace black, lamp black, acetylene black, channel black, or metal such as copper, iron (CI pigment black 11), titanium oxide, etc. And organic pigments such as aniline black (CI Pigment Black 1). Further, for color, C.I. I. Pigment Yellow 1, 3, 12, 13, 14, 17, 24, 3
4, 35, 37, 42 (yellow iron oxide), 53, 55, 8
1, 83, 95, 97, 98, 100, 101, 10
4, 408, 109, 110, 117, 120, 13
8, 150, 153; C.I. I. Pigment Orange 5,
13, 16, 17, 36, 43, 51; C.I. I. Pigment Red 1, 2, 3, 5, 17, 22, 23, 31,
38, 48: 2, 48: 2 (Permanent Red 2B
(Ca)), 48: 3, 48: 4, 49: 1, 52:
2,53: 1, 57: 1 (Brilliant Carmine 6
B), 60: 1, 63: 1, 63: 2, 64: 1, 8
1, 83, 88, 101 (Bengara), 104, 10
5, 106, 108 (Cadmium Red), 112, 1
14, 122 (quinacridone magenta), 123, 14
6, 149, 166, 168, 170, 172, 17
7, 178, 179, 185, 190, 193, 20
9, 219; C.I. I. Pigment Violet 1 (Rhodamine Lake), 3, 5: 1, 16, 19, 23, 3
8; C.I. I. Pigment Blue 1, 2, 15 (phthalocyanine blue), 15: 1, 15: 2, 15: 3 (phthalocyanine blue), 16, 17: 1, 56, 60, 6
3; C.I. I. Pigment Green 1, 4, 7, 8, 1
0, 17, 18, 36, etc.

The black pigment used as the coloring material is preferably carbon black. As a black ink, carbon black is excellent in color tone, water resistance, fading resistance and dispersion stability, and is inexpensive. In addition, it is possible to disperse in water by adding a functional group such as sulfo group or carboxyl group to the surface of a pigment (for example carbon), which is a graft pigment that can be dispersed in water by treating the surface of the pigment (for example, carbon) with resin. The processed pigment and the like can be used. Alternatively, the pigment may be contained in microcapsules so that the pigment can be dispersed in water.

According to a preferred embodiment of the present invention, the pigment in the ink composition preferably has an average particle size in the range of 10 nm to 200 nm. The average particle size referred to here is
A dynamic light scattering method in which particles that undergo Brownian motion in the recording liquid are irradiated with laser light, and the particle size is calculated from the amount of change in the frequency (light frequency) of the light (backscattered light) returning from the particles. It refers to a value of 50% of cumulative volume percentage measured using (Doppler scattered light analysis).

When the coloring material is a pigment, the water resistance and light resistance are improved, and it is possible to prevent strike-through (hereinafter simply referred to as strike-through), in which the ink leaks from the layer of the recording medium and seeps out to the back side. it can. Since the pigment is not dissolved in the aqueous recording liquid composed of the ink composition and is dispersed, it is less likely to enter the recording medium as compared with the liquid component of the ink when printed by an inkjet, and the pigment may be present near the surface of the recording medium. Since it remains, the drying property is fast and strike-through can be prevented. If the average particle size is 10 nm or less, the effect of preventing strike-through is small, and if it is 200 nm or more, the dispersion stability of the aqueous recording liquid is poor, and the particle size becomes large due to agglomeration or the like during storage, which may result in poor ejection stability.

The pigment is preferably dispersed in an aqueous medium in advance using a dispersant to prepare a pigment dispersion, which is preferably added as an ink composition in this dispersion state. As a preferable dispersant, a known dispersant used for preparing a conventionally known pigment dispersion liquid can be used. Examples of the polymer dispersant include the following.

As the hydrophilic polymer, naturally occurring plant polymers such as gum arabic, traggan gum, guar gum, karaya gum, locust bean gum, arabinogalactone, pectin and quince seed starch, and seaweed species such as alginic acid, carrageenan and agar. Polymers, animal-based polymers such as gelatin, casein, albumin and collagen, microbial polymers such as xanthene gum and dextran, and fibrin-based polymers such as methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose and carboxymethylcellulose in semi-synthetic systems. Polymers, starch-based polymers such as sodium starch glycolate and starch phosphate sodium, and seaweed-based polymers such as sodium alginate and propylene glycol alginate. .

In the pure synthetic system, polyacrylic acid, polymethacrylic acid, acrylic acid-acrylonitrile copolymer, vinyl acetate-acrylic acid ester copolymer, acrylic acid-acrylic acid alkyl ester copolymer, styrene-acrylic acid. Copolymer, styrene-methacrylic acid copolymer, styrene-acrylic acid-acrylic acid alkyl ester copolymer, styrene-methacrylic acid-acrylic acid alkyl ester copolymer, styrene-α-methylstyrene-acrylic acid copolymer , Styrene-α-methylstyrene-acrylic acid copolymer-acrylic acid alkyl ester copolymer, styrene-maleic acid copolymer, vinylnaphthalene-maleic acid copolymer, vinyl acetate-ethylene copolymer, vinyl acetate- Fatty acid vinyl ethylene copolymer, vinyl acetate-maleic acid Ester copolymer, vinyl acetate-
Examples thereof include crotonic acid copolymers and vinyl acetate-acrylic acid copolymers.

The above copolymer has a weight average molecular weight of 3,000.
It is preferably 0 to 50,000, more preferably 5,000 to 30,000, and most preferably 7,000.
~ 15,000. The polymer dispersant may be added in an appropriate amount so that the pigment is stably dispersed and the other effects of the present invention are not lost. The ratio of the pigment to the dispersant is preferably in the range of 1: 0.06 to 1: 3, more preferably 1: 0.125 to 1: 3.

It is also possible to use a water-soluble surfactant as a pigment dispersant. In this case, the increase in ink viscosity with respect to the amount used is smaller than that when a polymer dispersant is used, and it is easy to obtain a pigment-based ink having good ejection characteristics when used in an inkjet recording method.

As the water-soluble surfactant used as the pigment dispersant, anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants and the like can be used. The pigment may be added in an appropriate amount so that the pigment is stably dispersed and the other effects of the present invention are not lost. A specific example is shown below.

For example, as the anionic surfactant, alkylallyl or alkylnaphthalene sulfonate,
Alkyl phosphate, alkyl sulfate, alkyl sulfonate, alkyl ether sulfate, alkyl sulfosuccinate, alkyl ester sulfate, alkyl benzene sulfonate, alkyl diphenyl ether disulfonate, alkyl aryl ether phosphate, alkyl aryl ether Sulfate, alkyl aryl ether ester sulfate, olefin sulfonate, alkane olefin sulfonate, polyoxyethylene alkyl ether phosphate, polyoxyethylene alkyl ether sulfate ester salt, ether carboxylate, sulfosuccinate, α-sulfo Examples include fatty acid esters, fatty acid salts, condensates of higher fatty acids and amino acids, and naphthenates.

As the cationic surfactant, an alkylamine salt, a dialkylamine salt, an aliphatic amine salt,
Examples thereof include benzalkonium salt, quaternary ammonium salt, alkylpyridinium salt, imidazolinium salt, sulfonium salt and phosphonium salt.

Further, as the nonionic surfactant, polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene glycol ester, polyoxyethylene fatty acid amide, polyoxyethylene fatty acid ester. , Polyoxyethylene polyoxypropylene glycol, glycerin ester, sorbitan ester, sucrose ester, glycerin ester polyoxyethylene ether, sorbitan ester polyoxyethylene ether, sorbitol ester polyoxyethylene ether, fatty acid alkanolamide, amine oxide, Polyoxyethylene alkylamine, glycerin fatty acid ester, sorbitan fatty acid ester, polyoxye Rensorubitan fatty acid ester,
Examples thereof include polyoxyethylene sorbitol fatty acid ester and alkyl (poly) glycoxide.

Alternatively, examples of the amphoteric surfactant include imidazoline derivatives such as imidazolinium betaine, dimethylalkyllaurylbetaine, alkylglycine, and alkyldi (aminoethyl) glycine.

The dispersant in the ink composition is preferably one having a carboxyl group bonded. When a carboxyl group is bonded to the dispersant, not only the dispersion stability is improved, but also high quality printing quality is obtained and the water resistance of the recording medium after printing is further improved. Further, the effect of preventing the strike-through can be obtained. In particular, when a pigment dispersed with a dispersant having a carboxyl group bonded thereto and 2,4-diethyl-1,5-pentanediol are used together, a recording medium having a relatively high size such as plain paper can be obtained. Even when printing is performed, a sufficient drying speed can be obtained, and the effects of strike-through are small. The reason for this is that the dissociation constant of carboxylic acid is smaller than that of other acid groups, and therefore the pH value of the ink decreases after the pigment adheres to the recording medium, and polyvalent metal such as calcium existing near the surface of the recording medium. It is presumed that the solubility of the dispersant itself is lowered due to the interaction with ions and the dispersant itself and the pigment are aggregated.

Another more preferable form is a form in which the pigment in the ink composition is surface-modified so that the carboxyl group is directly bonded to the pigment and is dispersed in water in this state. In this case, since the pigment is surface-modified and the carboxyl group is bonded, not only the dispersion stability is improved, but also high quality printing quality is obtained by the same action as described above and the water resistance of the recording medium after printing is improved. Sex is improved. In addition, this form of ink has excellent redispersibility after drying, so even if printing is stopped for a long period of time and the water content of the ink near the nozzles of the inkjet head (recording head) evaporates, clogging does not occur and simple cleaning is possible. Good printing can be easily performed by operation.

Further, it is also applicable to bar code printing and postmark printing using an invisible recording liquid which has been rapidly spreading in recent years. In this case, an infrared absorber or an ultraviolet absorber which does not absorb in the visible region but absorbs infrared rays or ultraviolet rays is added to the ink composition in place of an ordinary dye or pigment. The aqueous recording liquid of the present invention comprises a coloring material, water, a wetting agent, 2,4-
It contains diethyl-1,5-pentanediol as a main component, and a surfactant and the like can be added as appropriate, but other conventionally known additives can also be added. For example,
A resin emulsion may be added to the aqueous recording liquid of the present invention.

The resin emulsion which can be used in the present invention means an emulsion in which the continuous phase is water and the dispersed phase is the following resin component. That is, as the resin component of the dispersed phase, an acrylic resin, a vinyl acetate resin,
Examples thereof include styrene-butadiene resin, vinyl chloride resin, acrylic-styrene resin, butadiene resin, styrene resin and the like. This resin is preferably a polymer having both a hydrophilic portion and a hydrophobic portion. The particle size of these resin components is not particularly limited as long as it forms an emulsion, but is preferably about 150 nm or less,
More preferably, it is about 5 to 100 nm. These resin emulsions can be obtained by mixing resin particles with water, optionally with a surfactant.

Examples of commercially available resin emulsions include Microgel E-1002 and E-5002 (styrene-acrylic resin emulsion: manufactured by Nippon Paint Co., Ltd.), Boncoat 4001 (acrylic resin emulsion: Dainippon Ink and Chemicals, Inc.). Made), Boncoat 5
454 (styrene-acrylic resin emulsion: manufactured by Dainippon Ink and Chemicals, Inc.), SAE-1014 (styrene-acrylic resin emulsion: manufactured by Nippon Zeon Co., Ltd.), Cybinol SK-200 (acrylic resin emulsion: Saiden Chemical Co., Ltd.) Company made) etc.

The ink composition in the aqueous recording liquid of the present invention preferably contains a resin emulsion such that the resin component accounts for 0.1 to 40% by weight of the ink composition.
It is more preferably in the range of 1 to 25% by weight. The resin emulsion has a property of thickening and aggregating, has an effect of suppressing permeation of a color material component in the depth direction of the paper, and further has an effect of promoting fixing to a recording medium. In addition, depending on the type of resin emulsion, it forms a film on the recording medium, and has the effect of improving the abrasion resistance of the printed matter.

The ink composition may contain sugar for the purpose of suppressing evaporation of water in the aqueous recording liquid. Examples of saccharides include monosaccharides, disaccharides, oligosaccharides (including trisaccharides and tetrasaccharides) and polysaccharides, preferably glucose, mannose, fructose, ribose, xylose, arabinose, galactose, maltose, cellobiose, Lactose, sucrose, trehalose, maltotriose and the like can be mentioned.
Here, the polysaccharide means a sugar in a broad sense, and is meant to include substances widely existing in the natural world such as α-cyclodextrin and cellulose.

Further, as the derivatives of these sugars, reducing sugars of the above-mentioned sugars (for example, sugar alcohol (general formula HO
Examples thereof include CH ₂ (CHOH) _n CH ₂ OH (represented by an integer of n = 2 to 5), oxidized sugar (eg, aldonic acid, uronic acid, etc.), amino acid, thioacid and the like. Particularly, sugar alcohols are preferable, and specific examples thereof include maltitol, sorbitol and the like. The content of these saccharides is appropriately in the range of 0.1 to 40% by weight, preferably 0.5 to 30% by weight of the ink composition.

The ink composition may further contain sodium alginate. Sodium alginate is a substance contained only in brown algae and is a hydrophilic polyelectrolyte which exists mainly as a cell membrane or a cell interstitial substance. D-Mannuro that chemically bonds with β-1,4
lic acid [M] and α-1,4 bond LG
It is a polymer of uluronic acid [G]. It has thickening action, stabilizing action, dispersing action, gelling action, film forming action and the like. When added to an ink composition for inkjet, it is possible to improve bleeding of a single color (feathering) and bleeding between different colors (color bleeding) due to viscosity change due to pH, precipitation due to salts, and gelation with a polyvalent cation.

Further, in the ink composition of the aqueous recording liquid,
An antiseptic / antifungal agent, a pH adjusting agent, a chelating agent, a rust preventive and the like can be added. As the antiseptic / antifungal agent, sodium dehydroacetate, sodium sorbate, sodium 2-pyridinethiol-1-oxide, sodium benzoate, sodium pentachlorophenol and the like can be used in the present invention.

As the pH adjustor, any substance can be used as long as it can adjust the pH to a desired value without adversely affecting the recording liquid 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.

Examples of the chelating agent include sodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, sodium uramildiacetate and the like.

Examples of the rust preventive agent include acidic sulfite,
There are sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, dicyclohexylammonium nitrite and the like. In addition, a water-soluble ultraviolet absorber can be added depending on the purpose.

The water-based recording liquid of the present invention is particularly preferably used in a so-called ink jet recording method in which ink is ejected and ejected as droplets from fine ejection openings of a recording head to form a color image on a recording medium. It goes without saying that it can be used as an ink for general writing instruments such as water-based pens, water-based markers, and water-based ballpoint pens, recorders, and pen plotters. Further, the aqueous recording liquid of the invention is not limited to the above applications.

When used in the ink jet recording method,
It is necessary to adjust the ink viscosity to the desired value. Although it depends on the ejection force of the head, the viscosity of the ink is generally 10 m.
It is preferably Pa · s or less. If it is larger than 10 mPa · s, sufficient ejection cannot be performed by the inkjet, and a problem of image defect often occurs. Suitable methods for recording using the aqueous recording liquid of the present invention include:
Applying thermal energy corresponding to the recording signal to the aqueous recording liquid,
A method of forming an image on a recording medium by generating droplets by the thermal energy can be mentioned.

A recording medium for forming an image using the aqueous recording liquid of the present invention contains pulp fibers as a main component and has a size degree of 1
It is preferable that the air permeability is 0 s or more and the air permeability is 5 to 50 s.
When printing is performed on such a recording medium with the aqueous recording liquid of the present invention, even if the recording is performed on both sides of the recording medium by the ink jet recording method, the image on the back side hinders recognition of the image on the front side. There is no. The sizing degree referred to here is the Steckigt sizing degree test method JIS for paper.
The air permeability is in accordance with JIS P8117-80, which is the air permeability test method for paper and paperboard. If the size is less than 10 s, the recording liquid permeates to the back surface and strike-through occurs, and the air permeability is 5
Even if it is smaller than s, the recording liquid penetrates to the back surface and strike-through occurs, and if it is 50 s or more, there is no problem in print quality and dryness, but the cost is high because the filler is added more than necessary. turn into. In addition, when this recording medium is used in an electrophotographic copying machine or printer, the filler is transferred to the photoconductor, fixing roller, etc., causing deterioration of the image quality and failure. It has to be used, and it becomes a burden because it is necessary for the consumer to use it properly. With the above size and air permeability, it can be handled in the same manner as non-coated plain paper such as electrophotographic transfer paper, printing paper, typewriter paper, wire dot printer paper, word processor paper, letter paper, and report paper. This makes it possible for the user to eliminate the trouble of separating the plain paper from other plain paper. In addition, even when producing paper, it is basically possible to produce using existing paper machines, and it is possible to minimize capital investment. Further, it can be commonly used for the applications of these other recording methods.

As the material of the pulp fiber used in the present invention, any material that does not affect the ink jet process can be appropriately used regardless of the type of pulp and the treatment method. Further, non-wood pulp (kenaf, flax, bamboo, seaweed, etc.) and waste paper pulp may be used, or those mainly composed of these may be used. Preferably, it is a chemical pulp represented by LBKP and NBKP. Paper making of these pulps is carried out by a conventional method using known sizing agents, fillers, and other paper making aids as necessary, as in ordinary plain paper.

As the sizing agent, rosin size and AK
D, sodium chloride, potassium chloride, styrene-maleic acid copolymer, quaternary ammonium salt, arnikelic succinic anhydride, petroleum resin-based size, epichlorohydrone, cationic starch, acrylamide and the like. Also, as the filler, clay, calcium carbonate, talc, titanium dioxide,
Examples thereof include synthetic silica. Further, a paper strength enhancer, a yield improver, a fixing agent, a dye, and other papermaking aids are added.

As a result of intensive studies, the present inventors have found that the aqueous recording liquid of the present invention was used in an ink jet recording apparatus.
Ejection volume V (p
By performing recording so that l) satisfies the relationship represented by the following formula (a), so-called plain paper has little strike-through, and a solid image is well-filled and there is no blank area. It was found that such an image can be obtained.

[0134]

## EQU3 ## 2.5 × 10 ⁸ / R ^2.6 ≦ V ≦ 6.0 × 10 ⁸ / R ^2.6 ...... (a)

(In the formula, R represents the maximum ejection density of droplets when recording is performed on a recording medium having pulp fibers as a main component and having a size degree of 10 s or more and an air permeability of 5 to 50 s, and the unit is Dot per inch (dpi), and the unit of the droplet discharge amount V is picoliter (p
It is represented by l). )

In the case of a serial type ink jet recording apparatus, the driving density (dpi) in the scanning direction (main scanning direction) of the recording head may differ from that in the paper conveying direction (sub scanning direction). It is preferable to use a value obtained by converting the number of shots per area so as to be uniform in the main scanning direction and the sub scanning direction.

The above formula (a) is a formula obtained experimentally as a result of studying various recording liquids. The left side of the formula (a) shows that when a solid image is formed on plain paper. It shows a relationship suitable for obtaining high image density without causing white streaks, etc., and the right side of the formula is for preventing increase of strikethrough density and occurrence of bleeding due to excess recording liquid adhered. Show suitable relationships. Any of these relationships is a relationship that can be established only when the aqueous recording liquid of the present invention has excellent penetrating properties into plain paper.

Since the aqueous recording liquid of the present invention has high permeability and gives a high-quality image without bleeding, it can be applied to a high-speed recording process which is usually difficult. That is, in the recording method of the present invention, an aqueous recording liquid is ejected and ejected as a plurality of liquid droplets from the same or different ejection ports of a recording head to form an image so that at least a part of pixel regions overlap on a recording medium. , Two aqueous recording liquid droplets that cause overlap on the recording medium have a discharge time difference of 0.1.
By setting the time to 25 milliseconds or less, very high speed recording becomes possible. In recent years, the technology for inkjet printers has made remarkable progress and the printing speed has also improved, but in order to maintain high image quality to some extent, dots in adjacent positional relationships are not formed continuously, The other recording liquid (ink) was not landed until it penetrated into the paper. That is, it can be said that high-quality printing is achieved while sacrificing the printing speed by a method called so-called multi-pass printing. Since the aqueous recording liquid of the present invention exhibits extremely high penetration characteristics, it has become possible to perform high-quality printing in a single pass, which could not be achieved conventionally.

An ink cartridge containing the aqueous recording liquid of the present invention and an ink jet recording apparatus equipped with the ink cartridge will be described with reference to the accompanying drawings. It does not add any limitation.

FIG. 1 is a schematic front view of a mechanical portion of a serial type ink jet recording apparatus equipped with an ink cartridge having a recording liquid containing portion containing the aqueous recording liquid of the present invention. The mechanism portion of this ink jet recording apparatus has a main support guide rod 3 and a sub-support guide rod 4 which are laterally bridged between the side plates 1 and 2 on both sides in a substantially horizontal positional relationship. The rod 4 supports the carriage unit 5 slidably in the main scanning direction.
The carriage unit 5 includes four heads 6 that eject yellow (y) ink, magenta (m) ink, cyan (c) ink, and black (k) ink, respectively.
Is mounted with its discharge surface (nozzle surface) 6a facing downward, and 4 is mounted above the head 6 of the carriage unit 5.
Four ink cartridges 7y and 7m, which are ink supply members of respective colors for supplying ink to the individual heads 6,
7c and 7k are mounted interchangeably.

The carriage unit 5 is connected to a timing belt 11 stretched between a driving pulley (driving timing pulley) 9 and a driven pulley (idler pulley) 10 which are rotated by a main scanning motor 8 to perform main scanning. By controlling the drive of the motor 8, the carriage 5, that is, the four heads 6 are moved in the main scanning direction. Further, subframes 13 and 14 are erected on a bottom plate 12 that connects the side plates 1 and 2, and a conveyance roller 15 for feeding the paper 16 in a sub scanning direction orthogonal to the main scanning direction is provided between the sub frames 13 and 14. Holds rotatably. Then, a sub-scanning motor 17 is arranged on the side of the sub-frame 14, and in order to transmit the rotation of the sub-scanning motor 17 to the conveying roller 15, the gear 18 fixed to the rotating shaft of the sub-scanning motor 17 and the conveying roller 15 are provided. And a gear 19 fixed to the shaft.

Further, a reliability maintaining / restoring mechanism (hereinafter referred to as “subsystem”) 21 of the head 6 is arranged between the side plate 1 and the subframe 13. Subsystem 2
1, a holder 23 holds four cap means 22 for capping the ejection surface of each head 6, and the holder 23
Is swingably held by the link member 24, and the carriage unit 5 contacts the engaging portion 25 provided on the holder 23 by the movement of the carriage unit 5 in the main scanning direction, so that the holder 23 moves in accordance with the movement of the carriage unit 5. Is lifted up and the ejection surface 6a of the inkjet head 6 is capped by the cap means 22, and the carriage unit 5 is moved to the printing area side, so that the holder 23 is lifted down as the carriage unit 5 moves and the cap means 22 is moved. Are separated from the ejection surface 6a of the inkjet head 6.

The cap means 22 is connected to the suction pump 27 through the suction tube 26, forms an atmosphere opening port, and communicates with the atmosphere through the atmosphere opening tube and the atmosphere opening valve. The suction pump 27 discharges the sucked waste liquid to a waste liquid storage tank (not shown) via a drain tube or the like.

Further, on the side of the holder 23, a fiber member for wiping the ejection surface 6a of the ink jet head 6,
A wiper blade 28, which is a wiping means made of a foamed member or an elastic member such as rubber, is attached to a blade arm 29, and the blade arm 29 is swingably supported.
The cam is rotated by the rotation of a cam (not shown).

Next, the ink cartridge 7 will be described with reference to FIGS. Here, FIG. 2 is an external perspective view of the ink cartridge before being loaded in the recording apparatus of FIG. 1, and FIG. 3 is a front sectional view of the ink cartridge. As shown in FIG. 3, the ink cartridge 7 includes an ink absorber 42 that absorbs ink of a desired color in a cartridge body 41. The cartridge body 41 is formed by adhering or welding an upper lid member 44 to the upper opening of a case 43 having a wide opening at the top, and is made of, for example, a resin molded product. The ink absorber 42 is made of a porous material such as a urethane foam body and absorbs ink after being compressed and inserted into the cartridge body 41. An ink supply port 45 for supplying ink to the recording head 6 is formed at the bottom of the case 43 of the cartridge body 41, and the seal ring 4 is provided on the inner peripheral surface of the ink supply port 45.
6 is fitted. Further, the upper lid member 44 is formed with an atmosphere opening port 47. In the cartridge main body 41, the case 43 is compressed and deformed in the state before loading by closing the ink supply port 45 and handling the cartridge during loading or transportation, or by the pressure applied to the wide side wall during vacuum packaging. A cap member 50 is attached to prevent the ink inside from leaking.

Further, as shown in FIG. 2, the atmosphere opening port 47 is sealed by sticking a film-like sealing member 55 having an oxygen permeability of 100 ml / m ² or more to the upper lid member 44. The sealing member 55 is sized to seal not only the atmosphere opening port 47 but also a plurality of grooves 48 formed around it. In this way, the atmosphere opening 47 has an oxygen permeability of 10
By sealing with a sealing member 55 of 0 ml / m ² or more, the ink cartridge 7 is packaged in a reduced pressure state using a packaging member such as an aluminum laminated film that does not have air permeability. Even when a gas is dissolved in the ink due to the atmosphere in the space A (see FIG. 3) generated between the ink and the cartridge body 41, the air in the ink is high outside the cartridge body 41 via the seal member 55. The ink is discharged into the space between it and the packaging member, and the degree of deaeration of the ink is improved.

Next, FIG. 4 shows an example of the construction of an ink cartridge provided with a recording liquid container containing the recording liquid of the present invention and an ink jet head (recording head) for ejecting recording liquid droplets. The ink cartridge will be described below. The ink cartridge 30 is of a serial type, and includes an inkjet head 6, an ink tank 33 that stores a recording liquid (ink) supplied to the inkjet head 6, and a lid member that seals the inside of the ink tank 33. The main part is composed. A large number of nozzles 32 for ejecting the recording liquid are formed in the inkjet head 6. The recording liquid is guided from the ink tank 33 to an unillustrated common liquid chamber via an ink supply pipe (not shown), and is ejected from the nozzle 32 in response to an electric signal from the recording apparatus main body input from the electrode 31. It The ink cartridge 30 of this type has a configuration
This structure is suitable for a head of a type that can be manufactured at low cost, that is, a so-called thermal method or a bubble method that uses thermal energy as a driving power source. The aqueous recording liquid of the present invention, in a recording method such as a bubble method or a thermal method,
By adding 2,4-diethyl-1,5-pentanediol, the wettability to the thermal element is improved,
Ejection stability and frequency stability are obtained even with a small amount of addition, and safety is high, which is very suitable.

Although the serial type ink jet recording apparatus as described above has been described here, the aqueous recording liquid of the present invention has the nozzles in an arbitrary arrangement such as a staggered pattern and has the same resolution as a target image or a fraction thereof. It is also possible to apply to a recording device having a so-called line head, which is integrated to a certain density and arranged over the width of the recording medium. Further, the recording device mentioned here may be not only an output printer for a PC or a digital camera, but also a device having a composite function in combination with a fax, a scanner, a telephone or the like.

[0149]

EXAMPLES Examples and comparative examples of the present invention will be shown below, but the present invention is not limited thereto. In addition,
The amount (%) of each component described in Examples and Comparative Examples is based on weight.

Example 1 First, carbon black was dispersed using a bead mill according to the formulation shown in Pigment Dispersion Liquid 1 below. The resulting Pigment Dispersion 1 was mixed with the ink formulation shown in Ink Composition 1 below and stirred, and then 10% lithium hydroxide was added to adjust the pH to 8.
It was adjusted with an aqueous solution. Then, filtration was performed with a membrane filter having an average pore size of 0.8 μm to obtain an aqueous recording liquid 1.

[0151]   <Pigment dispersion 1>     Carbon black (average particle size 104 nm) 15% by weight     Styrene-acrylate-methacrylic acid die     Tanolamine salt copolymer 3% by weight     Deionized water remaining

[0152]   <Ink composition 1>     Pigment dispersion 1 33.3% by weight     Glycerin 10% by weight     Diethylene glycol 6.5% by weight     Ethylene glycol 3.5% by weight    2,4-diethyl-1,5-pentanediol 5% by weight     Deionized water remaining

Example 2 After mixing and stirring with the ink formulation shown in the following ink composition 2, the pH was adjusted to 9 with an aqueous 10% sodium hydroxide solution. Then, filtration was performed with a membrane filter having an average pore size of 0.8 μm to obtain an aqueous recording liquid 2.

[0154]   <Ink composition 2>     Carboxyl group-bonded carbon black dispersion   (Solid content 16.4% by weight, average particle diameter 108 nm) 33.3% by weight     Glycerin 5% by weight     Diethylene glycol 15% by weight     Compound (Formula (1-1)) sodium salt 0.3% by weight     2,4-diethyl-1,5-pentanediol 2% by weight     Deionized water remaining

Example 3 After mixing and stirring with the ink formulation shown in the following ink composition 3, the pH was adjusted to 9 with an aqueous 10% lithium hydroxide solution. Then, filtration was performed with a membrane filter having an average pore diameter of 0.2 μm to obtain an aqueous recording liquid 3.

[0156]   <Ink composition 3>     C. I. Direct Yellow 142 2.0% by weight     Glycerin 8% by weight     Triethylene glycol 20% by weight     2,4-diethyl-1,5-pentanediol 5% by weight     2-pyrrolidone 2% by weight     Deionized water remaining

Example 4 In the same process as in Example 1, the dispersion shown in Pigment dispersion 2 below was formulated, and then the mixture was mixed and stirred with the ink formulation shown in Ink composition 4 so that the pH became 9. It was adjusted with a 10% aqueous solution of lithium hydroxide. Then, filtration was performed with a membrane filter having an average pore size of 0.8 μm to obtain an aqueous recording liquid 4.

[0158]   <Pigment dispersion 2>     C. I. Pigment Blue 15: 3     (Average particle size 138 nm) 15% by weight     Styrene-acrylate-methacrylic acid die     Tanolamine salt copolymer 3% by weight     Deionized water remaining

[0159]   <Ink composition 4>     Pigment dispersion 2 33.3% by weight     Glycerin 8% by weight     Triethylene glycol 20% by weight     Compound (Formula (1-8)) sodium salt 0.3% by weight     2,4-diethyl-1,5-pentanediol 4% by weight     2-pyrrolidone 2% by weight     Deionized water remaining

Example 5 In the same process as in Example 2, the ink composition shown in Ink Composition 5 below was mixed and stirred, and then adjusted to pH 9 with a 10% aqueous solution of lithium hydroxide. afterwards,
Aqueous recording liquid 5 was obtained by filtering with a membrane filter having an average pore diameter of 0.8 μm.

[0161]   <Ink composition 5>     Sulfonate-bonded carbon black dispersion   (Solid content 18% by weight, average particle size 132 nm) 33% by weight     Glycerin 3% by weight     Diethylene glycol 2% by weight     Lithium salt of compound (formula (1-13)) 1% by weight     2,4-diethyl-1,5-pentanediol 1.5% by weight     2-ethyl-1,3-hexanediol 0.5% by weight     Deionized water remaining

Example 6 In the same process as in Example 1, the dispersion liquid shown in Pigment dispersion liquid 3 below was formulated, and then the mixture was mixed with the ink formulation shown in Ink composition 6 and stirred to adjust the pH to 9. It was adjusted with a 10% aqueous solution of sodium hydroxide. Then, filtration was performed with a membrane filter having an average pore size of 0.8 μm to obtain an aqueous recording liquid 6.

[0163]   <Pigment dispersion 3>     Carbon black (average particle size 104 nm) 15% by weight     Styrene-acrylate-methacrylic acid die     Tanolamine salt copolymer 3% by weight     Deionized water remaining

[0164]   <Ink composition 6>     Pigment dispersion 3 30.0% by weight     Direct Black 168 0.5% by weight     Glycerin 5% by weight     Diethylene glycol 30% by weight     For the counterion of the compound (formula (1-2))     Salt using the compound (formula (2-2)) 4% by weight     2,4-diethyl-1,5-pentanediol 3% by weight     Deionized water remaining

Example 7 In the same process as in Example 1, the dispersion liquid shown in Pigment dispersion liquid 4 below was formulated, and then the mixture was mixed with the ink formulation shown in Ink composition 7 and stirred to adjust the pH to 8. It was adjusted with a 10% aqueous solution of lithium hydroxide. Then, filtration was performed with a membrane filter having an average pore diameter of 0.8 μm to obtain an aqueous recording liquid 7.

[0166]   <Pigment dispersion 4>     Carbon black (average particle size 53nm) 15% by weight     Formalin condensate of naphthalene sulfonate 3% by weight     Deionized water remaining

[0167]   <Ink composition 7>     Pigment dispersion 4 33.3% by weight     Ethylene glycol 5% by weight     Polyethylene glycol (molecular weight 200) 5% by weight     Polyoxyethylene (n = 7) (secondary alkyl     Ether: nonionic surfactant) 0.1% by weight     2,4-diethyl-1,5-pentanediol 3.5% by weight     Deionized water remaining

Example 8 In the same process as in Example 1, the dispersion liquid shown in Pigment dispersion liquid 5 below was formulated, and then the mixture was mixed with the ink formulation shown in Ink composition 8 and stirred to adjust the pH to 9. It was adjusted with a 10% aqueous solution of lithium hydroxide. Then, filtration was performed with a membrane filter having an average pore diameter of 0.8 μm to obtain an aqueous recording liquid 8.

[0169]   <Pigment dispersion 5>     Carbon black (average particle size 196 nm) 15% by weight     Formalin condensate of naphthalene sulfonate 3% by weight     Deionized water remaining

[0170]   <Ink composition 8>     Pigment dispersion 5 33.3% by weight     Glycerin 5% by weight     Fluorinated alkyl ester (nonionic surfactant) 0.3% by weight     2,4-diethyl-1,5-pentanediol 3% by weight     Diethylene glycol monobutyl ether 3% by weight     Deionized water remaining

Example 9 In the same process as in Example 3, after mixing and stirring by the ink formulation shown in the following ink composition 9, the pH was adjusted to 8 with an aqueous 10% sodium hydroxide solution. Then, filtration was performed with a membrane filter having an average pore diameter of 0.2 μm to obtain an aqueous recording liquid 9.

[0172]   <Ink composition 9>     C. I. Direct black 168 4% by weight     Glycerin 5% by weight     N-methyl-2-pyrrolidone 5% by weight     Polyethylene glycol with ethylene oxide added: poly     Propylene glycol molecular weight 950; Nonionic surfactant 2% by weight     2,4-diethyl-1,5-pentanediol 2.5% by weight     2-pyrrolidone 2.0% by weight     Deionized water remaining

Example 10 In the same process as in Example 3, the ink composition shown in Ink Composition 10 below was mixed and stirred, and the pH was adjusted to 8 with an aqueous 10% sodium hydroxide solution. Then, filtration was performed with a membrane filter having an average pore diameter of 0.2 μm to obtain an aqueous recording liquid 10.

[0174]   <Ink composition 10>     C. I. Direct Red 227 3% by weight     Diethylene glycol 20% by weight     Triethylene glycol 10% by weight     Ionette D-2 (anionic surfactant:     Sanyo Kasei Kogyo Co., Ltd.) 2.5% by weight     2,4-diethyl-1,5-pentanediol 0.5% by weight     2,2,4-trimethyl-1,3-pentanediol 1% by weight     Deionized water remaining

Example 11 In the same process as in Example 3, the ink composition shown in Ink Composition 11 below was mixed and stirred, and then the pH was adjusted to 9 with an aqueous 10% lithium hydroxide solution. Then, filtration was performed with a membrane filter having an average pore diameter of 0.2 μm to obtain an aqueous recording liquid 11.

[0176]   <Ink composition 11>     Projet FastCyan2 (Made by Zeneca) 3% by weight     20% by weight of ethylene glycol     Diethylene glycol 20% by weight     For the counterion of the compound (formula (1-5))     Salt using compound (formula (2-7)) 1% by weight     Ionette D-2 (anionic surfactant;     Sanyo Chemical Industry Co., Ltd.) 1% by weight     2,4-diethyl-1,5-pentanediol 2% by weight     2-pyrrolidone 0.5% by weight     Deionized water remaining

Comparative Example 1 In the same process as in Example 1, the dispersion shown in Pigment dispersion 6 below was formulated, and then the mixture was mixed with the ink formulation shown in Ink composition 12 and stirred, and then the pH was adjusted to 9. It was adjusted with a 10% aqueous solution of lithium hydroxide. Then, filtration was performed with a membrane filter having an average pore size of 0.8 μm to obtain an aqueous recording liquid 12.

[0178]   <Pigment dispersion 6>     Carbon black (average particle size 104 nm) 15% by weight     Styrene-acrylate-methacrylic acid die     Tanolamine salt copolymer 3% by weight     Deionized water remaining

[0179]   <Ink composition 12>     Pigment dispersion 6 33.3% by weight     Compound (Formula (1-1)) sodium salt 1% by weight     2,4-diethyl-1,5-pentanediol 2% by weight     Deionized water remaining

Comparative Example 2 In the same process as in Example 2, the ink composition shown in Ink Composition 13 below was mixed and stirred, and then adjusted to pH 9 with a 10% aqueous sodium hydroxide solution. Then, filtration with a membrane filter having an average pore diameter of 0.8 μm was performed to obtain an aqueous recording liquid 13.

[0181]   <Ink composition 13>     Black pigment (carboxyl group-bonded carbon     Black average particle size 108nm) 5% by weight     Glycerin 10% by weight     Diethylene glycol 10% by weight     Compound (Formula (1-8)) sodium salt 0.3% by weight     Diethylene glycol monobutyl ether 1% by weight     Deionized water remaining

Comparative Example 3 In the same process as in Example 3, the ink composition shown in Ink Composition 14 below was mixed and stirred, and then the pH was adjusted to 9 with a 10% aqueous solution of lithium hydroxide. Then, filtration was performed with a membrane filter having an average pore diameter of 0.2 μm to obtain an aqueous recording liquid 14.

[0183]   <Ink composition 14>     C. I. Direct Yellow 142 2.0% by weight     Glycerin 10% by weight     Diethylene glycol 10% by weight     4% by weight of lithium salt of compound (formula (1-13))     2-pyrrolidone 2% by weight     Deionized water remaining

Comparative Example 4 In the same process as in Example 2, the ink composition shown in Ink Composition 15 below was mixed and stirred, and then adjusted to pH 9 with a 10% aqueous solution of lithium hydroxide. Then, filtration was performed with a membrane filter having an average pore size of 0.8 μm to obtain an aqueous recording liquid 15.

[0185]   <Ink composition 15>     Sulfonate-bonded carbon black dispersion    (Solid content 18% by weight, average particle size 132 nm) 33% by weight     Glycerin 10% by weight     Diethylene glycol 10% by weight     For the counterion of the compound (formula (1-2))     Salt using the compound (formula (2-2)) 7% by weight     Deionized water remaining

Regarding the aqueous recording liquids 1 to 15 obtained in the above Examples 1 to 11 and Comparative Examples 1 to 4, the following three types of recording devices (evaluation devices) were used to obtain image sharpness, image dryness, The strike-through, scratch resistance, image filling, and storability were evaluated. The following three evaluation devices were used. Table 1 shows the evaluation device used for each output and the evaluation results for each evaluation item.

Evaluation device (A): The densities of droplets to be ejected onto plain paper are 600 × 600 dpi in the densest state, and the piezo with the drive voltage adjusted so that the ejection amount from each nozzle is 23 pl. Type inkjet printer (IPSIO JET300; manufactured by Ricoh Co., Ltd.). Evaluation device (B): The ejection density of droplets on plain paper is 2400 × 1200 dpi in the densest state, and a thermal inkjet printer (BJ S630; which ejects from each nozzle at an ejection amount of 5 pl per droplet).
Canon Inc.). Evaluation device (C): The droplet ejection density on plain paper is 1440 × 720 dpi in the densest state, and it is possible to control the ejection amount per droplet in accordance with the output image, and the minimum is 1. Piezo ink jet printer (EM-900) with a discharge amount of 3 pl per drop
C: manufactured by Seiko Epson Corporation).

The evaluation conditions for image sharpness, image drying property, strike-through, scratching property, image embedding, and storability and the evaluation judgment are as follows. (1) Image clarity: NBS as recording medium
Ricoh made; My paper (size 12s, air permeability 1
6s) is printed, and after bleeding, image bleeding, color tone, and density are visually inspected and a reflection-type color spectrophotometric densitometer (X-Rit
(manufactured by Company e). Very good was evaluated as ⊚, good was evaluated as ◯, normal to slightly inferior was evaluated as Δ, and defective was evaluated as x. (2) Image drying property: The time after which the filter paper was pressed against the image after the solid image was printed on the recording medium at a pressure of 0.1 kg / cm ² until the ink was not transferred to the filter paper was measured. When any of the papers was dried within 3 seconds, 3 to 20 seconds was evaluated as Δ and 20 seconds or more was evaluated as x. (3)
Strikethrough: A solid image was formed on the recording medium so that the density of each ink color measured by a reflection type color spectrophotometric densitometer (manufactured by X-Rite) was 1.0. Visually observing this image from the back side, if the colorant (coloring material) of the solid image is missing to the back side and the level cannot be used for double-sided printing, ×, the colorant (coloring material) of the solid image is missing to the back side. However, the boundary between the solid image and the white background is a little unclear,
△ when the level is acceptable for double-sided printing, ○ when the boundary between the solid image and the white background is almost unclear and the level is acceptable for double-sided printing, ○, for the solid image and the white background When the boundary was completely unclear and there was no problem in using it for double-sided printing, it was judged as ◎. (4) Rubability: The image formed with each ink on the recording medium is rubbed with a finger, cloth, eraser, and marking pen 30 seconds after printing, and the state after rubbing is visually observed, and the change in the image due to rubbing is observed. When it occurred, it was marked with X, and when it did not occur, it was marked with ◯. (5) Image filling: If the recording medium is uniformly colored with the ink even after observing the solid image after drying and magnifying the image, the recording medium is uniformly colored with the ink as long as it is visually observed. When the color was uneven, it was marked with ◯, and when it was unevenly colored so that the background could be visually observed, it was marked with x. (6) Storability: If the ink is set in the inkjet printer and left at 60 ° C. for 7 days, then it can be recovered with one cleaning operation of a conventionally known inkjet printer. ○ If it can be recovered with 2 to 5 times △, 5
If it doesn't return even after the number of times, it is marked as ×.

[0189]

[Table 1]

Example 12 Next, using the same aqueous recording liquid 2 as in Example 2, a recording medium (plain paper) was manufactured by Xerox Co .; Xerox Paper R.
(Sizing degree 8 s, Air permeability 20 s) was used, and the same evaluation items as described above were evaluated in the same manner as in Example 2 except that the evaluation device (A) was used. The results are shown in Table 2.

Example 13 Using the same aqueous recording liquid 2 as in Example 2, the recording medium (plain paper) was replaced by AUSTRALIAN PAPER (Australia); REFLEX (size 25s, air permeability 4s). In the same manner as in Example 2, the evaluation device (B) was used and the same evaluation items as described above were evaluated except for the evaluation of storability. The results are shown in Table 2.

Example 14 Using the same aqueous recording liquid 2 as in Example 2, the recording medium (plain paper) was manufactured by NBS Ricoh Co., Ltd .; NBS copy printing paper 90K.
(Sizing degree 60S, Air permeability 68s) was used, and the same evaluation items as described above were evaluated in the same manner as in Example 2 except that the evaluation device (A) was used.
The results are shown in Table 2.

Example 15 Next, using the same aqueous recording liquid 2 as in Example 2, a recording medium (plain paper) manufactured by Canon Inc .; PB paper (size degree 21) was used.
s, air permeability 8 s), and the same evaluation items as above were evaluated in the same manner as in Example 2 except that the evaluation device (C) was used. The results are shown in Table 2.

Example 16 Next, using the same aqueous recording liquid 2 as in Example 2, a recording medium (plain paper) was manufactured by NBS Ricoh Co., Ltd .; NBS copy printing paper 45K (size degree 11s, air permeability 45s). In the same manner as in Example 2 except that the above evaluation apparatus (A) was used,
The same evaluation items as described above were evaluated except for the evaluation of storability. The results are shown in Table 2.

Example 17 Next, using the same aqueous recording liquid 2 as in Example 2, a recording medium (plain paper) was manufactured by Honshu Paper Co .; Yamayuri (size degree 12).
s, air permeability 21 s), and the same evaluation items as above were evaluated in the same manner as in Example 2 except that the evaluation device (C) was used. The results are shown in Table 2.

Example 18 Using the same aqueous recording liquid 2 as in Example 2, a recording medium (plain paper) was manufactured by Ricoh Co., Ltd .; paper source PPC paper tie-fS ((size degree 22 s, air permeability 13 s). The same evaluation items as described above were evaluated using the evaluation device (B) in the same manner as in Example 2 except that the evaluation was changed, and the results are shown in Table 2.
Shown in.

Example 19 Using the same aqueous recording liquid 2 as in Example 2, the recording medium (plain paper) was changed to X paper manufactured by Xerox Co .; P paper (size degree 24 s, air permeability 19 s) and the evaluation device ( In the same manner as in Example 2 except that C) was used, the same evaluation items as described above were evaluated except for the evaluation of storability. The results are shown in Table 2.

Example 20 Using the same aqueous recording liquid 2 as in Example 2, a recording medium (plain paper) was manufactured by Xerox Co .; Multi Ace (size 25).
s, air permeability 17 s), and the same evaluation items as above were evaluated in the same manner as in Example 2 except that the evaluation device (A) was used. The results are shown in Table 2.

Example 21 Example 2 was repeated except that the same aqueous recording liquid 2 as in Example 2 was used, but the recording medium (plain paper) was changed to Xerox 4024 (size degree 32 s, air permeability 21 s) manufactured by Xerox Co., Ltd. Using the evaluation apparatus (B) in the same manner as described above, the same evaluation items as described above were evaluated except for the evaluation of storability. The results are shown in Table 2.

[0200]

[Table 2]

From the results shown in Tables 1 and 2, when the aqueous recording liquid comprising the ink composition of the present invention was used,
All of them have excellent image clarity, image dryness, strikethrough, scratching, image burying, and storage stability, and are confirmed to be highly dry even for high-speed printing and print without strikethrough. Was done.

[0202]

Effect of the Invention 2,4-Diethyl-1,5 according to the present invention
-By containing pentanediol as an ink composition, it is possible to realize a high-drying aqueous recording liquid without strikethrough that enables high-speed printing and double-sided printing.
An ink jet recording method compatible with a high printing speed is achieved, and an ink cartridge and an ink jet recording device using the recording liquid are provided. The effects of the invention will be described below.

In the invention according to claim 1, at least a coloring material which is dissolved or dispersed in water, water, a wetting agent, and 2,4
By using an ink composition containing -diethyl-1,5-pentanediol, excellent penetrability and dryness are obtained irrespective of the coloring material and paper type, less bleeding, and excellent safety and storage stability. It is possible to provide an aqueous recording liquid.

According to the second aspect of the present invention, the content of 2,4-diethyl-1,5-pentanediol is 0.1 to 5% by weight, so that the penetration characteristics are high and the image quality is excellent.
It is possible to provide a stable aqueous recording liquid that does not cause phase separation.

According to the third aspect of the present invention, by setting the content of the wetting agent to 5 to 50% by weight, clogging is less likely to occur, and a normal printing state can be recovered by a simple cleaning operation. It becomes possible to provide.

In the invention according to claim 4, by setting the content of the surfactant to 0.01 to 5.0% by weight, reduction of image density and strike-through can be prevented, and addition of a small amount provides high penetrability. Therefore, it is possible to provide an aqueous recording liquid with less solvent odor.

In the invention according to claim 5, by containing a surfactant containing at least a polyoxyethylene alkyl ether acetate, it is possible to provide an aqueous recording liquid having high penetrability with a small amount of addition.

In the invention according to claim 6, at least one of diethylene glycol, triethylene glycol, and glycerin is used as a wetting agent to prevent nozzle clogging, and to improve storage stability and jet stability. The recording liquid can be provided.

In the invention according to claim 7, 2-ethyl-
1,3-hexanediol, 2,2,4-trimethyl-
By containing at least one of 1,3-pentanediol, it is possible to provide an aqueous recording liquid having a low solvent odor in which reduction in image density and strike-through are prevented.

In the invention according to claim 8, by containing 2-pyrrolidone as the ink composition, an image in which the permeation into the paper is not impaired and the permeation of the ink into the paper layer is suppressed more than necessary It is possible to provide an aqueous recording liquid in which strikethrough is prevented as well as the concentration is improved.

In the invention according to claim 9, by using a coloring material as a pigment, the water resistance and the light resistance are improved, and the excellent water permeation characteristics are maintained, the image density is high, and the excellent water resistance with less strike-through is achieved. The recording liquid can be provided.

According to the tenth aspect of the present invention, by setting the average particle size of the pigment to 10 nm to 200 nm, it is possible to provide an aqueous recording liquid having excellent storage stability and ejection stability in the ink jet recording method.

In the invention according to claim 11, a pigment is dispersed by a dispersant having a carboxyl group bonded, whereby a high-quality image with less bleeding is formed, and the water resistance of the recording medium after printing is improved. It is possible to provide an aqueous recording liquid.

According to the twelfth aspect of the invention, it is possible to provide an aqueous recording liquid having extremely high storage stability and reliability by dispersing it in water using a pigment having a hydrophilic group bonded to its surface.

According to the thirteenth aspect of the invention, by using a hydrophilic group bonded to the surface of the pigment as a carboxyl group, a high-quality image with less bleeding is formed, and the water resistance of the recording medium after printing is improved. The recording liquid can be provided.

According to the fourteenth aspect of the present invention, by using the aqueous recording liquid of the present invention, it is possible to provide a recording method for forming an image on a recording medium at a high speed by the ink jet method.

According to the fifteenth aspect of the present invention, the aqueous recording liquid of the present invention is used, and thermal energy is applied to eject droplets.
By flying, the wettability to the thermal element is improved,
It is possible to provide a recording method having excellent ejection stability and frequency stability.

According to the sixteenth aspect of the invention, the main component of the recording medium for forming an image using the aqueous recording liquid of the present invention is pulp fiber, the sizing degree is 10 s or more, and the air permeability is 5 to 50.
By setting to s, it becomes possible to provide a recording method in which the recognition of images on both sides is not hindered even when printing is performed on both sides by the inkjet method.

According to the seventeenth aspect of the present invention, the aqueous recording liquid of the present invention is used to perform recording by satisfying a predetermined relationship between the ejection amount per droplet ejected from the recording head and the droplet ejection density. Therefore, it is possible to provide a recording method that can obtain a high-quality image with high density and less bleeding, without missing dots or white streaks.

According to the eighteenth aspect of the present invention, by using the aqueous recording liquid of the present invention, the ejection time difference between two ink jet liquid droplets that cause pixel areas to overlap on the recording medium is 0.125 milliseconds or less. Therefore, it becomes possible to provide a recording method capable of recording high-quality images at high speed.

According to the nineteenth and twentieth aspects of the present invention, by using the recording liquid of the present invention as the recording liquid (ink) of the ink cartridge having the recording liquid storage portion for storing the recording liquid, a high speed ink jet is obtained. It is possible to provide an ink cartridge for printing.

According to the twenty-first and twenty-second aspects of the present invention, the recording liquid (ink) of the present invention is used as the recording liquid of the ink cartridge provided in the ink jet recording apparatus and provided with the recording liquid storage portion for storing the recording liquid. By using it, it becomes possible to provide a high-speed inkjet recording device.

[Brief description of drawings]

FIG. 1 is a schematic front view showing a structural example of a mechanism of a serial type ink jet recording apparatus equipped with an ink cartridge containing an aqueous recording liquid of the present invention.

FIG. 2 is an external perspective view of an ink cartridge before being loaded in the recording apparatus shown in FIG.

FIG. 3 is a front sectional view of the ink cartridge shown in FIG.

4 is an external perspective view of an ink cartridge integrated with a recording head before being loaded in the recording apparatus shown in FIG.

[Explanation of symbols]

1 side plate 2 side plates 3 Main support guide rod 4 Secondary support guide rod 5 Carriage unit 6 heads 6a Discharge surface (nozzle surface) 7 ink cartridges 7y ink cartridge 7m ink cartridge 7c ink cartridge 7k ink cartridge 8 Main scanning motor 9 Drive pulley (drive timing pulley) 10 Driven pulley (idler pulley) 11 Timing belt 12 Bottom plate 13 subframes 14 subframes 15 Conveyor roller 16 sheets 17 Sub-scanning motor 18 gears 19 fixed gear 21 subsystem 22 Cap means 23 Holder 24 Link member 25 Engagement part 26 Suction tube 27 Suction pump 28 Wiper blade 29 blade arm 30 ink cartridges 31 electrodes 32 nozzles 33 ink tank 41 Cartridge body 42 ink absorber 43 cases 44 Upper lid member 45 ink supply port 46 seal ring 47 Atmosphere opening 48 grooves 50 Cap member 55 Seal member A space

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Claims (22)

[Claims] 1. An ink composition containing at least a colorant which is dissolved or dispersed in water, water, a wetting agent, and 2,4-diethyl-1,5-pentanediol. Aqueous recording liquid. 2. The content of 2,4-diethyl-1,5-pentanediol is 0.1 to 5% by weight with respect to the total amount of the ink composition. Aqueous recording liquid. 3. The aqueous recording liquid according to claim 1, wherein the content of the wetting agent is 5 to 50% by weight based on the total amount of the ink composition. 4. The ink composition according to claim 1, further comprising a surfactant in a range of 0.01 to 5% by weight based on the total amount of the ink composition. The aqueous recording liquid according to 1. 5. The aqueous recording liquid according to claim 4, wherein the surfactant contains at least a polyoxyethylene alkyl ether acetate represented by the following general formula (1). Embedded image R ₁ —O— (CH ₂ CH ₂ O) _m —CH ₂ COOM (1) (wherein, R ₁ is an alkyl group having 6 to 14 carbon atoms and may be branched, and m is 3 to A natural number of 12, M represents an alkali metal ion, a quaternary ammonium, a quaternary phosphonium, or an alkanolamine.) 6. The aqueous recording liquid according to claim 1, wherein the wetting agent is a compound selected from at least one of diethylene glycol, triethylene glycol and glycerin. 7. The ink composition further contains at least one compound selected from 2-ethyl-1,3-hexanediol and 2,2,4-trimethyl-1,3-pentanediol. 7. The method according to claim 1, wherein
The aqueous recording liquid according to any one of 1. 8. The aqueous recording liquid according to claim 1, further comprising 2-pyrrolidone in the ink composition. 9. The aqueous recording liquid according to claim 1, wherein the coloring material is a pigment. 10. The average particle diameter of the pigment is 10 nm to 2
The aqueous recording liquid according to claim 9, which is in a range of 00 nm. 11. An aqueous recording liquid obtained by adding a pigment dispersion liquid, in which a pigment is dispersed in water by a dispersant, to an ink composition, wherein a carboxyl group is bonded to the dispersant. Aqueous recording liquid. 12. An aqueous recording liquid obtained by adding a pigment dispersion liquid, in which a pigment is dispersed in water by a dispersant, to an ink composition, wherein a hydrophilic group is bonded to the surface of the pigment for surface modification. An aqueous recording liquid characterized in that 13. The aqueous recording liquid according to claim 12, wherein the hydrophilic group is a carboxyl group. 14. In a recording method of forming an image on a recording medium by ejecting and ejecting an aqueous recording liquid as droplets from an ejection port of a recording head, the aqueous recording liquid according to claim 1. A recording method characterized by being an aqueous recording liquid. 15. The image forming method according to claim 14, wherein in the recording method, thermal energy is applied to the aqueous recording liquid to eject and fly as droplets from the ejection port of the recording head to form an image on the recording medium. Recording method. 16. The recording method according to claim 14, wherein the recording medium contains pulp fibers as a main component, and has a size degree of 10 s or more and an air permeability of 5 to 50 s. 17. A recording method for forming an image on a recording medium by ejecting and ejecting the aqueous recording liquid according to claim 1 as droplets from an ejection port of a recording head,
The discharge amount V (pl) per droplet is the following formula (a)
A recording method characterized by satisfying. ## EQU1 ## 2.5 × 10 ⁸ / R ^2.6 ≤ V ≤ 6.0 × 10 ⁸ / R ^2.6 (a) (wherein R is pulp fiber as a main component, and size is 10 s
As described above, the maximum ejection density of droplets when recording is performed on a recording medium having an air permeability of 5 to 50 s, the unit is dp.
i (dot per inch), and the droplet discharge amount V
The unit of is represented by picoliter (pl). ) 18. At least a part of a pixel area on a recording medium by ejecting and ejecting the aqueous recording liquid according to claim 1 as a plurality of droplets from the same or separate ejection ports of a recording head. Is a recording method for forming images so that the two droplets overlap each other on the recording medium, and the difference in ejection time between two droplets that cause the overlapping is 0.125 milliseconds or less. 19. An ink cartridge provided with a recording liquid containing portion containing a recording liquid, wherein the recording liquid is the ink cartridge.
An ink cartridge comprising the aqueous recording liquid according to any one of 1 to 13. 20. An ink cartridge comprising a recording liquid containing portion containing a recording liquid and a recording head portion for ejecting recording liquid droplets, wherein the recording liquid is according to any one of claims 1 to 13. An ink cartridge which is an aqueous recording liquid. 21. An ink jet recording apparatus, comprising: an ink cartridge having a recording liquid storage section for storing the recording liquid; and a recording head for ejecting recording liquid droplets, wherein the recording liquid is the recording medium. An ink jet recording apparatus comprising the aqueous recording liquid according to any one of 1. 22. An ink jet recording apparatus equipped with an ink cartridge comprising a recording liquid containing portion containing a recording liquid and a recording head for ejecting recording liquid droplets, wherein the recording liquid is the ink according to any one of claims 1 to 13. An ink jet recording apparatus, which is the aqueous recording liquid according to any one of the claims.