JP2003096355A - Ink composition, ink-jet recording method and recording apparatus by using this ink composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet-printing ink composition which permits the high graceful image quality as that of a laser printer and permits stable setting with no clogging in a nozzle in spite of using a penetration-type ink composition, and to provide an ink jet-recording method. SOLUTION: The penetration-type high viscous ink composition has a pigment concentration of 6 wt.% or higher and contains a penetrant having a solubility in water at 25 deg.C of from 0.1 wt.% to not more than 4.5 wt.% and also has an ink composition viscosity of 8 cPs or more (25 deg.C).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink composition jet recording apparatus, and more particularly to a plain paper copier paper (PPC).
The present invention relates to an ink composition and a jet recording method for recording information such as characters, images and symbols on (paper) or the like.

[0002]

2. Description of the Related Art The present invention has hitherto been known as an excellent recording method in that the ink jet recording system is not limited to the type of recording material, and research and development on recording apparatus, recording methods, recording materials, etc. have been actively conducted. Has been done. However, in practice, in an inkjet recording apparatus that has been developed and commercialized in the past, it is necessary to use a recording material specially developed for inkjet recording, which is called an inkjet paper or an inkjet transparency film. , Good fixing property, good so-called “cut”, recorded image without characters, blurring around the image, blurring (hereinafter referred to as feathering), and recorded image with high optical density (OD) Paper that is difficult to obtain, such as plain paper copier paper (PPC paper), letter paper, bond paper, postcards, stationery, envelopes, report paper, etc., which are commonly used in offices, homes, etc. For recording materials such as transparency films (OHP films) that are generally commercially available In the case of recording with an ink jet recording apparatus as conventionally known, it was not possible to satisfy the above characteristics at the same time.

Although it is possible to satisfy the above characteristics by using an inkjet recording paper, it is natural that the inkjet recording paper is generally expensive and the inkjet recording paper is generally a single-sided coated paper. However, when recording is performed on the uncoated surface, there is a drawback that the fixability and the printing quality are remarkably deteriorated, which is one of the reasons why the inkjet recording apparatus is not widely used.

Therefore, various developments have been made in order to obtain the above-mentioned good fixing property, a recorded image excellent in print quality, and a recorded image having high optical density. For example, (1) JP-A-56-57862 and JP-A-57-1.
No. 02970, JP-A-57-102971 discloses a strong alkaline ink composition having a pH of about 13, and (2) a wax-like ink composition which is solid at room temperature is heated and ejected in a molten state. Recording method (JP-A 61-159470, JP-A 62-4)
No. 8774), and (3) a method of recording with an oil-based ink composition using a non-water-soluble organic solvent as a liquid medium has been developed and commercialized.

In addition, looking only at the purpose of obtaining a good fixing property, (4) an ink composition containing a large amount of a surfactant as shown in JP-A-55-29546,
(5) Glycerin, N-methyl-2-pyrrolidone, direct dye, and a surfactant having a low surface tension of less than or equal to cmc (critical micelle concentration) as disclosed in JP-A-56-49771. The combined ink composition, (6) the pH of the ink composition as shown in JP-A-56-57862 and JP-A-57-102971 is made strongly alkaline, and a fluorine-based surfactant is further added. The added ink composition and the like are known.

However, in the method (1), the ink composition is strongly alkaline and is dangerous in handling, and the acid paper using rosin or the like as a sizing agent has good fixing property and good printing quality. However, in recent years, the fixing properties of neutral papers using alkyl ketene dimer, stearic anhydride, etc., which have been increasing in production in Japan, show a marked decrease in fixability and a slight decrease in print quality. Moreover, this strong alkaline ink composition has a drawback that double-sided recording is extremely difficult because strike-through is likely due to its large penetrating power into the paper.

The method (2) is an excellent method capable of satisfying the above-mentioned characteristics, but the printed portion rises up, and the printed matter is transferred when a number of printed matter are left in piles. However, there is a known drawback that the papers are stuck together, and there is also a problem that the apparatus becomes complicated because a means for heating the ink composition is required. The method (3) is particularly excellent in fixability, but since it is necessary to consider the odor and safety of the organic solvent contained in the ink composition, it is manufactured on the bottom of the can, the outside of the box, etc. It is used only for industrial purposes such as printing a lot number, and is not in a situation where it is used in orifices or ordinary households.

The method of using the ink composition (4) is described in JP-A-55-80477 and JP-A-56-49771.
As disclosed in Japanese Patent Publication, there is a problem in print quality, and it cannot be said to be an excellent method.

In the method of using the ink composition of (5), the drying speed of the ink composition after printing (the "fixability" in the present invention is 8 to 8
It takes about 15 seconds, and it can be said that the fixing property is certainly superior to the conventionally known ink composition, but from the standpoint of using a recording apparatus, the time of 8 to 15 seconds seems to be long. Therefore, depending on the type of paper, if the printed matter coming out of the recording device is immediately picked up, the hand may be contaminated with the ink composition, and depending on the type of paper, feathering may become noticeable. Improvement is desired.

The fixing time of the ink composition (6) can be set to 5 seconds or less. It was confirmed by the present inventors that the ink composition is extremely excellent in fixing property, but as described in the method (1) above, it was found that the ink composition is safe and has good stability on neutral paper. There are problems in fixing property, print quality, and strike-through property, which is not preferable.

In addition, in general, it is desirable to use an aqueous ink composition in consideration of odor, safety, handleability of the ink composition, etc. in consideration of uses for offices and households. When an aqueous ink composition is used, generally, if the recording material has stains such as fingerprints, feathering tends to occur only in that portion, and depending on the paper, the print quality may be different between the front and back of the paper. There is also a problem that when the recording material is set in the ink composition jet recording apparatus, it is necessary to handle the recording material with extreme caution because it may change significantly.

Further, as well known in the art,
Contains 1 to 5% by weight of water-soluble dye and 20 to 50% by weight of water-soluble organic solvent such as glycols, and has a surface tension of 40 to
In a multi-nozzle ink composition jet recording apparatus that uses a water-based ink composition having a density of about 55 dyne / cm, nozzles that do not print (do not use for printing) may be Even during printing, it may become clogged. For example, "-"
Repeatedly printing for about 120 seconds, and then printing "1", the nozzle used for printing "-" normally ejects, but the other nozzles do not eject,
There was also a problem that "1" could not be printed correctly.

If the recording apparatus is left for a while after printing (for example, about two days and nights assuming weekends and holidays), the viscosity of the ink composition may increase due to evaporation of water from the nozzle. Discharge phenomenon is often observed,
It is often said that the ink composition jet recording apparatus is difficult to use because it is necessary to perform an operation for solving the non-ejection phenomenon every time when the recording apparatus is used.

Such troubles are often observed in the case of using a recording apparatus in which the energy used to fly the ink composition is relatively small, and compared with the ink composition jet recording apparatus using a piezo element, a bubble is generated. The jet recording device has a smaller ejection energy, which is often seen especially in the bubble jet recording device, and various improvement measures have been devised.

In order to prevent the above-mentioned troubles, it is necessary to incorporate various recovery devices such as a cap and a pump into the recording device, which is one of the causes for making the ink composition jet recording device complicated and expensive. It has become one.

[0016]

Therefore, an object of the present invention is (i) without selecting a recording surface (hard to be influenced by surface physical properties, materials, front and back of paper, film, etc.), (ii) density (OD) is high, (iii) print quality is good, recording with less feathering is possible, (iv) fixability is extremely good, and (v) without particularly complicated recovery device. A highly reliable and safe ink composition capable of immediately performing normal printing at any time, and an excellent ink composition that has never been obtained, particularly an inkjet ink composition, and a recording method using the ink composition. . Further, another object of the present invention is to provide an ink jet recording method capable of performing smooth and natural reproducible recording of complicated Chinese characters, diagonal lines and curved lines, and obtaining a recorded image with good water resistance. Especially.

[0017]

In order to solve the above problems, the present invention provides the following ink composition and an ink jet recording method using the ink composition. The present invention includes a pigment, a wetting agent, a penetrant having a solubility of 0.1 to less than 4.5% by weight in water at 25 ° C, an anionic or nonionic surfactant, a water-soluble organic solvent,
Containing at least water, the pigment concentration is 6 wt% or more, preferably 8 wt% or more, more preferably 8 to 20 wt.
%, And the viscosity of the ink composition is 5 cps (25 ° C.) or higher, preferably 8 cps to 20 cps (25 ° C.).
The above-mentioned subject was able to be solved.

In the low viscosity ink composition of about 3 cps (25 ° C.) used in the conventional ink jet printer, the water content in the ink composition is about 70%. However, by increasing the pigment concentration as described above, For example, 7 cps
With a high-viscosity ink composition of about (25 ° C.), it is about 50% or less, the water evaporation rate when the ink droplets land on the paper surface is 1.5 to 2.0 times higher, and the pigment is on the paper surface. Coagulation is facilitated, image density (OD) is improved, printing quality is significantly improved, and bleeding (feathering) is also reduced. However, if it exceeds 20 wt%, clogging due to the solid pigment content is likely to occur, and the image density does not become higher, so the addition amount of 20 wt% or more is not necessary.

Further, the ink composition of the present invention has a temperature of 25 ° C.
The surface tension at 40 dyne / cm or less, preferably 25 to 35 dyne / cm, is preferable. If the surface tension of the ink composition is adjusted so as to be 40 dyn / cm or less, it is possible to quickly fix even most recording materials, and with this fixing property, the marker resistance is at a level with no problem. I found it. The surface tension of the ink composition of the present invention is 40 dyn.
/ Cm or less, the wettability of the ink composition to the head member is improved, the frequency response is improved even with a high viscosity ink composition of 5 cps (25 ° C.) or more, and ejection stability is significantly improved. did it. The low surface tension of the ink composition of the present invention is 0.1 to 4.5 in water at 25 ° C.
This can be achieved by using a penetrant having a solubility of less than wt% and an anionic or nonionic surfactant.

Another feature of the present invention is that the aqueous ink composition is used under the following printing conditions. That is, 1
The volume of one droplet of the ink composition flying by an electric signal is (Mj) 14 to 35 pl (picoliter), the droplet speed (Vj) is 6 to 20 m / sec, the frequency is 1 KHz or more, and the resolution is 300 dpi or more. The inkjet recording method is characterized in that recording is carried out under the condition of one-pass printing within the range. The ink composition of the present invention has an Mj of 14 to 35 p.
By performing inkjet recording under the conditions of 1 and Vj of 6 to 20 m / sec, frequency of 1 KHz or more, resolution of 300 dpi or more, and one-pass printing condition, it was possible to obtain high-quality image comparable to a laser printer on plain paper.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described more specifically based on the embodiments. The ink composition of the present invention is composed of, for example, each component shown in the following (1) to (10). That is, a pigment as a coloring material for printing and a solvent for dissolving and dispersing the pigment are essential components, and further additives include a wetting agent, a surfactant, an emulsion, an antiseptic agent, and a pH adjusting agent. . (1) Pigment (preferably self-dispersion pigment) (2) Wetting agent 1 (3) Wetting agent 2 (4) Water-soluble organic solvent (5) Anionic or nonionic surfactant (6) 0 in water at 25 ° C Penetrant (7) Emulsion (8) Preservative (9) pH adjuster (10) Pure water wetting agent having a solubility of 1 to less than 4.5% by weight, but only one kind is preferable, but two kinds are preferable. Are combined and mixed. The reason why the wetting agents 1 and 2 are mixed is to utilize the characteristics of each wetting agent and to adjust the viscosity. The humectant 1 has properties such as high moisture retention and high viscosity, and the humectant 2 has properties such as low moisture retention and low viscosity. The constituent elements of each ink composition are described below.

(Pigment) With respect to the pigment, an inorganic pigment or an organic pigment can be used without any particular limitation, but it is a self-dispersion type having a characteristic of being dispersed in water without the aid of a dispersant. When a pigment is used, the viscosity of the ink composition does not change significantly even if the concentration of carbon black is increased, and it is possible to allow a high concentration of carbon black to exist stably in the ink composition, and Even after water is added to dryness, the particle size distribution returns to the original state, and the re-solubility (re-dispersibility) is excellent, which is preferable.

The self-dispersion pigment is a pigment that can be dispersed and / or dissolved in water without a dispersant, and has a value of hydrophilic functional group / specific surface area of 5 to 30 μmol / m 2.
It is in the range of ² .

The surface-modified carbon black in the present invention is one in which the surface of the carbon black is modified by introducing a large amount of hydrophilic functional groups into the carbon black, whereby the carbon black itself retains its hydrophilicity. is there. Therefore, the surface-modified carbon black has a particle size (preferably the minimum particle size) in which the carbon black can be dispersed so that the water-soluble dye dissolves in water as a single molecule, so that the dispersant aids. It is thought to disperse in water without. Such surface-modified carbon black is usually called a self-dispersion type carbon black,
In the present invention, such carbon black is used.

By using the aqueous pigment dispersion according to the present invention, an ink composition can be prepared without a dispersant. As a result, the viscosity of the ink composition does not change significantly even if the concentration of carbon black is increased, and a high concentration of carbon black can be stably present in the ink composition. Therefore, a high-density printed image can be realized. Furthermore, the aqueous pigment dispersion according to the present invention uses a carbon black having a specific amount of hydrophilic functional groups / specific surface area and having a specific surface modification, and thus does not satisfy the requirements of the present invention. Compared with the above, there is an advantage that a remarkable image quality can be improved.

In the present invention, the surface-modified carbon black means a carboxyl group, a carbonyl group, a hydroxyl group, a sulfone group, a phosphoric acid group, and a hydrophilic functional group such as a quaternary ammonium salt or a salt thereof directly or in an alkyl group. It means that it is bonded to the surface of carbon black as a pigment via a group, an alkyl ether group, an aryl group or the like.

In the present invention, "dispersing and / or dissolving in water without a dispersant" means a pigment (carbon black).
Means a state in which a particle size (preferably a minimum particle size) that can be dispersed in water without using a dispersant is present in a stable manner. The dispersible particle size means a particle size at which the particles are not further reduced even if the dispersion time is increased.

The surface-modified carbon black contained in the aqueous pigment dispersion according to the present invention has a hydrophilic functional group content (μmol).
/ G) divided by the specific surface area (m ² / g) of carbon black, that is, the value of hydrophilic functional group / specific surface area is 5
In the range of ˜30 μmol / m ² , preferably 7.
It is in the range of 5 to 15 μmol / m ² . When the aqueous pigment dispersion is used as an aqueous ink for writing or ink jet recording, the above value is 7.5 to 15 μmo.
The range of 1 / m ² is particularly preferable. The ink composition using the aqueous pigment dispersion liquid containing the surface-modified carbon black having a value in this range can achieve higher printing density and good dispersion stability and storage stability.

Here, the amount of hydrophilic functional group is a quantification of the amount of a hydrophilic functional group such as a carboxyl group, a carbonyl group and a hydroxyl group, which is generally a vacuum heat for measuring the volatile content of carbon black. It can be determined by the decomposition gas method. The vacuum pyrolysis gas method is the method described on pages 69 to 74 of the Chemical Society of Japan, Vol. 88, No. 3, (1967).

As the inorganic pigment, in addition to titanium oxide and iron oxide, carbon black produced by a known method such as a contact method, a furnace method or a thermal method can be used.

The organic pigments include azo pigments (including azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments, etc.), polycyclic pigments (eg, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments). , Quinacridone pigment, dioxazine pigment, thioindigo pigment, isoindolinone pigment, quinofuraron pigment, etc.), dye chelate (for example, basic dye type chelate,
Acid dye type chelates), nitro pigments, nitroso pigments, aniline black, etc. can be used.

According to a preferred embodiment of the present invention, among these pigments, those having a good affinity for water are preferably used and dispersed in water with a dispersant. Also,
The particle size of the pigment is preferably 0.05 to 10 μm, more preferably 1 μm or less.

Specific examples of the pigment preferably used in the present invention include the following.

For black, carbon black (CI pigment black 7) such as furnace black, lamp black, acetylene black and channel black, or copper, iron (CI pigment black 1).
1), metals such as titanium oxide, aniline black (C.
I. Pigment Black 1) and other organic pigments.

For color, C.I. I. Pigment Yellow 1 (Fast Yellow G), 3, 12 (Disazo Yellow AAA), 13, 14, 17, 24, 34, 3
5, 37, 42 (yellow iron oxide), 53, 55, 81, 8
3 (Disazo Yellow HR), 95, 97, 98, 10
0, 101, 104, 408, 109, 110, 11
7, 120, 138, 153, C.I. I. Pigment Orange 5, 13, 16, 17, 36, 43, 51, C.I.
I. Pigment Red 1, 2, 3, 5, 17, 22 (Brilliant First Scallet), 23, 31, 3
8, 48: 2 (Permanent Red 2B (Ba)), 4
8: 2 (Permanent Red 2B (Ca)), 48: 3
(Permanent Red 2B (Sr)), 48: 4 (Permanent Red 2B (Mn)), 49: 1, 52: 2,
53: 1, 57: 1 (Brilliant Carmine 6B), 6
0: 1, 63: 1, 63: 2, 64: 1, 81 (Rhodamine 6G rake), 83, 88, 101 (Bengara),
104, 105, 106, 108 (cadmium red), 112, 114, 122 (quinacridone magenta), 123, 146, 149, 166, 168, 17
0, 172, 177, 178, 179, 185, 19
0, 193, 209, 219, C.I. I. Pigment Violet 1 (Rhodamine Lake), 3, 5: 1, 16,
19, 23, 38, C.I. I. Pigment Blue 1, 2,
15 (phthalocyanine blue R), 15: 1, 15:
2, 15: 3 (phthalocyanine blue E), 16, 1
7: 1, 56, 60, 63, C.I. I. Pigment Green 1, 4, 7, 8, 10, 17, 18, 36 and the like.

Other pigments that are preferably used in the present invention include a graft pigment that is made dispersible in water by treating the surface of a pigment (for example, carbon) with a resin or the like, or a sulfo group or a sulfone group on the surface of the pigment (for example, carbon). A processed pigment or the like which has a functional group such as a carboxyl group added thereto and can be dispersed in water can be used. Alternatively, the pigment may be contained in microcapsules so that the pigment can be dispersed in water.

(Surface Treatment of Pigment) As the black carbon, carbon black produced by a furnace method or a channel method is used.
m, specific surface area by BET adsorption method is 50 to 300 m ² /
g, a DBP oil absorption amount of 40 to 150 ml / 100 g, a volatile content of 0.5 to 10%, and a pH of 2 to 9 are used, and acidic carbon black having a pH of 6 or less is particularly preferable at a high concentration. Further, carbon black subjected to hypochlorite oxidation treatment, carbon black treated with a sulfonating agent, and carbon black treated with a diazonium compound to introduce an anionic dissociative group such as sulfonic acid or carboxylic acid are more preferable.

As the yellow pigment, C.I. I Pigment Yellow 74, 128, 138
Is preferred. Examples of magenta pigments include quinacridone C.I. I. Pigment Red 122 and 209 are preferable.
Cyan is a phthalocyanine compound such as C.I. I. Pigment Blue 15: 3, aluminum-coordinated phthalocyanine, and metal-free phthalocyanine are preferable.

Of these color organic pigments, pigments having sulfonic acid groups and carboxylic acid groups introduced by surface treatment are more excellent in dispersion stability, and those which can obtain dispersion stability without a dispersant are preferably used as self-dispersion pigments. be able to. A pigment having a surface-encapsulated pigment, a pigment grafted with a polymer, or the like can also be used as an ink composition having excellent dispersion stability and high reliability.

(Dispersion) According to a preferred embodiment of the present invention, the pigment for the black ink composition is prepared by using a known dispersion liquid used for preparing a conventionally known pigment dispersion liquid. It is preferably added to the ink composition as a pigment dispersion obtained by dispersing it in a medium.

Examples of the dispersant for the dispersion liquid include the following. Polyacrylic acid, polymethacrylic acid,
Acrylic acid-acrylonitrile copolymer, vinyl acetate-
Acrylic 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 Polymer, vinyl naphthalene-maleic acid copolymer, vinyl acetate-ethylene copolymer, vinyl acetate-fatty acid vinyl ethylene copolymer, vinyl acetate-maleic acid ester copolymer, vinyl acetate-crotonic acid copolymer, vinyl acetate -Acrylic acid copolymers and the like.

According to a preferred embodiment of the present invention, these polymeric dispersants have a weight average molecular weight of 3,000 to 50,0.
It is preferably 00, more preferably from 5,000 to
30,000, most preferably 7,000 to 15,000
It is 0. The amount of dispersant added is to disperse the pigment in a stable manner,
It may be added as appropriate as long as the other effects of the present invention are not lost, and the addition amount is such that the ratio of the pigment to the dispersant is 1: 0.06 to.
The range of 1: 3 is preferable, and more preferably 1: 0.12.
It is in the range of 5 to 1: 3.

(Wetting Agent) The wetting agent is added mainly for the purpose of preventing ink drying at the nozzles or nozzle plates where the ink comes into contact with air. Only one type of wetting agent may be used, and glycerin is mostly used. However, by combining two kinds of wetting agents, it is possible to obtain properties that are not limited to glycerin. Therefore, in the wetting agent 1 and the wetting agent 2,
Wetting agent 1 is a multiplicity of complex glycerins and wetting agent 2 is a wetting agent other than glycerin. Glycerin has the best moisturizing effect, but it has a high viscosity and cannot be added in a large amount. In addition, the blurring of images, characters, etc. increases with the addition amount. Therefore, by mixing with other moisturizers, the moisturizing effect is inferior to that of glycerin, but having a lower viscosity, and that does not cause character blurring (moisturizer) than glycerin.
It is possible to balance the two and optimize the ink.

Specific examples of wetting agents other than glycerin include the following. Ethylene glycol, diethylene glycol, triethylene glycol,
Propylene glycol, dipropylene glycol, tripropylene glycol, tetraethylene glycol, hexylene glycol, polyethylene glycol, polypropylene glycol, 1,5-pentanediol, 1,
6-hexanediol, glycerol, 1,2,6-hexanetriol, 1,2,4-butanetriol,
Polyhydric alcohols such as 1,2,3-butanetriol and petriol.

Among them, a mixed wetting agent composed of a combination of 1,3-butanediol and glycerin, a combination of 1,6-hexanediol and glycerin, and a combination of trimethylolethane and glycerin is preferable. Further, a mixed wetting agent of at least two kinds of 1,3-butanediol, 1,6-hexanediol and trimethylolethane and glycerin is also preferable.

(Water-Soluble Organic Solvent) The ink composition of the present invention uses water as a liquid medium. In order to make the ink composition have desired physical properties and prevent the ink composition from drying, In order to improve dispersion stability and dissolution stability,
Further, for the purpose of improving the permeability and the fixing property, the following water-soluble organic solvents are used, for example. A plurality of these water-soluble organic solvents may be mixed and used.

(1) Specific examples of the water-soluble organic solvent include:
For example, the following (1) to (6) may be mentioned. Ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether,
Polyhydric alcohol alkyl ethers such as diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol monoethyl ether;

(2) Polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether; 2-pyrrolidone,
N-methyl-2-pyrrolidone, N-hydroxyethyl-
A nitrogen-containing heterocyclic compound such as 2-pyrrolidone, 1,3-dimethylimidazolidinone, ε-caprolactam, γ-butyrolactone;

(3) Amides such as formamide, N-methylformamide and N, N-dimethylformamide;

(4) Monoethanolamine, diethanolamine, triethanolamine, monoethylamine,
Amines such as diethylamine and triethylamine;

(5) Sulfur-containing compounds such as dimethyl sulfoxide, sulfolane and thiodiethanol;

(6) Others, propylene carbonate,
Examples include ethylene carbonate.

Among these organic solvents, especially diethylene glycol, thiodiethanol, polyethylene glycol 200 to 600, triethylene glycol, glycerol, 1,2,6-hexanetriol, 1,2,4-
Butanetriol, petriol, 1,5-pentanediol, 2-pyrrolidone and N-methyl-2-pyrrolidone are preferred. These have excellent effects on solubility and prevention of defective ejection characteristics due to water evaporation. In addition, at least one water-soluble organic solvent is a pyrrolidone derivative,
In particular, the use of 2-pyrrolidone improves the image quality.

The wetting agent of the present invention, for example, a mixture of 1,3-butanediol (1,6-hexanediol, trimethylolethane) and glycerin is a mixture of conventionally used ethylene glycol (diethylene glycol) and glycerin. The viscosity of the ink composition is higher than that of the low viscosity wetting agent described above, and it is possible to achieve a high viscosity ink composition in combination with a high pigment concentration.

The other wetting agent preferably contains sugar. Since saccharides have many hydroxyl groups, they are considered to have a high effect of binding to water molecules to maintain their moisturizing properties, but usually the saccharides alone are insufficient in moisturizing effect, and are well combined with glycerin. The saccharide not only has a moisturizing effect, but also contributes to the improvement of the fixing property of the ink since it is originally solid. 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.

The derivatives of these saccharides include reducing sugars of the above-mentioned saccharides (for example, sugar alcohol (general formula H
It is represented by OCH ₂ (CHOH) nCH ₂ OH (where n represents an integer of 2 to 5). ), Oxidized sugar (eg, aldonic acid, uronic acid, etc.), amino acid, thioacid, etc. Sugar alcohol is particularly 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.

(Surfactant) In the present invention, the use of a surfactant can improve the wettability to recording paper. The surfactant is not particularly limited as to the type of surfactant, but examples thereof include the following.

Examples of the anionic surfactant include polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, lauryl acid salt and polyoxyethylene alkyl ether sulfate salt.

Examples of the nonionic surfactant include, for example,
Examples thereof include polyoxyethylene alkyl ether, polyoxyethylene alkyl ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylphenyl ether, polyoxyethylene alkylamine, and polyoxyethylene alkylamide. The surfactants may be used alone or in combination of two or more.

Preferred surfactants are represented by the following formula (1)
To (6) polyoxyethylene alkyl ether acetate, dialkyl sulfosuccinate, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene polyoxypropylene block copolymer, acetylene glycol-based interface Activator etc. are mentioned.

[0062]

[Chemical 8] (R ₁ is an optionally branched alkyl group having 6 to 14 carbon atoms, m is an integer of 3 to 12, M is an alkali metal ion, a quaternary ammonium, a quaternary phosphonium, or an alkanolamine.)

[0063]

[Chemical 9] (R ₂ is a branched alkyl group having 5 to 16 carbon atoms, M is an alkali metal ion, quaternary ammonium, quaternary phosphonium or alkanolamine.)

[0064]

[Chemical 10] (R is a carbon chain having 6 to 14 carbon atoms which may be branched, k
Is an integer of 5 to 20. )

[0065]

[Chemical 11] (R is a carbon chain having 6 to 14 carbon atoms which may be branched, n is 5
Is an integer of -20. )

[0066]

[Chemical 12] (R is a carbon chain having 6 to 14 carbon atoms, m and n are integers of 5 to 20.)

[0067]

[Chemical 13] (P and q are integers of 0 to 40.)

Next, the surfactant (I) used in the present invention,
(II) is specifically shown in the free acid form.

[Chemical 14]

[Chemical 15]

The amount of the surfactants (I) to (VI) added should be 0.05 to 10% by weight so as to give desired penetrability to the ink composition characteristics required by the printer system. Is possible. Here, if it is 0.05% or less, bleeding occurs at the boundary of the two-color overlapping portion in any case,
If it is added in an amount of 10% by weight or more, the compound itself tends to precipitate at low temperature, resulting in poor reliability.

Particularly, as the anionic surfactant, the use of the surfactants of the above formulas (I) and / or (II) improves the plain paper properties, and further the solubility / dispersion stability of the colorant is selected. .

Further, a polyoxyethylene alkyl phenyl ether of the general formula (III) and an acetylene glycol-based surfactant of the general formula (VI) are used in combination as the nonionic surfactant. The synergistic effect is penetrability, which results in an ink composition with reduced color boundary bleeding and less character bleeding.

Furthermore, the use of lithium ion as a counter ion of the surfactant of the present invention and quaternary ammonium or quaternary phosphonium represented by the following general formula makes the surfactant exhibit excellent dissolution stability.

The surface tension in the present invention is an index showing the penetrability into paper, and in particular 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 method can be used as long as it can measure the dynamic surface tension of 1 second or less by the conventionally known method described in Japanese Patent No. 237, etc., in the present invention, it was measured using a Wilhelmy type hanging plate type surface tension meter. The surface tension value of the ink composition of the present invention is 40 mJ / m ² or less, more preferably 35 mJ / m ^2.
When it is J / m ² or less, excellent fixability and dryness can be obtained.

(Penetrant) The penetrant having a solubility of 0.1 to less than 4.5% by weight in water at 25 ° C. used in the present invention is preferably 0.1 to 4.
The partially water-soluble polyol and / or glycol ether having a solubility of less than 5% by weight is added to the recording ink composition by 0.1 to 10.0% by weight, based on the total weight of the ink composition. The wettability of the material to the thermal element is improved, and ejection stability and frequency stability can be obtained even with a small amount of addition.

Penetrants having a solubility between 0.1 and 4.5% by weight in water at 25 ° C. have the advantage that they have a very high permeability in spite of their low solubility. Therefore, 2
A highly penetrative ink composition is obtained by combining a penetrant having a solubility of less than 0.1 to 4.5% by weight in water at 5 ° C. with another solvent or another surfactant. It is possible to create.

0.1 to 4.5 wt in water at 25 ° C.
As specific examples of the penetrant having a solubility of less than%, for example, the following are preferable because they have high moisture permeability. 2-Ethyl-1,3-hexanediol 2,2,4-trimethyl-1,3-pentanediol 3,6-dimethyl-4-octyne-3,6-diol 2,5-dimethyl-3-hexyne-2 , 5-diol 2,5-dimethylhexane-2,5-diol 3,5-dimethyl-1-hexyne-3-ol 2,4-diethyl-1,5-pentanediol 2-butyl-2-ethyl-1 , 3-propanediol

Of these several penetrants, 2-ethyl-1,3-hexanediol and 2,2,4-trimethyl-1,3-pentadiol are the most preferred. That is, 0.1 to 4.5 in water at 25 ° C.
The oily compound of less than wt% has a function of permeating the coloring material in the lateral direction of the paper (viewed from the cross-sectional direction of the paper). However, the anionic or nonionic surfactant added together has the function of penetrating the coloring material in the longitudinal direction of the paper, so by blending both, micelles surrounding the oily part with the surfactant An active complex can be formed to allow the coloring material to permeate the paper in a balanced manner.

(Resin emulsion) A resin emulsion is preferably added to the recording ink composition of the present invention. The resin emulsion means an emulsion in which the continuous phase is water and the dispersed phase is the following resin component. Examples of the resin component of the dispersed phase include acrylic resin, vinyl acetate resin, styrene-butadiene resin, vinyl chloride resin, acrylic-styrene resin, butadiene resin, and styrene resin. According to a preferred embodiment of the present invention, 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 about 5 to 100 nm.

These resin emulsions can be obtained by mixing resin particles with water, optionally together with a surfactant. For example, an emulsion of acrylic resin or styrene-acrylic resin can be obtained by mixing these resins and a surfactant in water. The mixing ratio of the resin component and the surfactant is usually preferably about 10: 1 to 5: 1. If the amount of the surfactant used is less than the above range, it is difficult to form an emulsion, and if it exceeds the above range, the water resistance of the ink composition tends to decrease and the penetrability tends to deteriorate, such being undesirable.

The ratio of the resin as the dispersed phase component of the emulsion to water is 60 to 100 parts by weight of the resin.
A suitable range is 400 parts by weight, preferably 100 to 200.

Commercially available resin emulsions include Microgel E-1002, E-5002 (styrene-acrylic resin emulsion, manufactured by Nippon Paint Co., Ltd.), Boncoat 4001 (acrylic resin emulsion, manufactured by Dainippon Ink and Chemicals, Inc.), Boncoat 5454 (styrene-
Acrylic resin emulsion, made by Dainippon Ink and Chemicals, SAE-1014 (styrene-acrylic resin emulsion, made by Zeon Corporation), Cybinol SK-2
00 (acrylic resin emulsion, manufactured by Saiden Chemical Co., Ltd.) and the like.

The ink composition used in the present invention comprises a resin emulsion, the resin component of which is 0.1 to 0.1% of that of the ink composition.
The content is preferably 40% by weight, more preferably 1 to 25% by weight. The resin emulsion has a property of thickening and aggregating, has an effect of suppressing penetration of a coloring component, and further has an effect of promoting fixing to a recording material. Further, depending on the type of resin emulsion, a film is formed on the recording material, which has the effect of improving the abrasion resistance of the printed matter.

To the ink composition of the present invention, conventionally known additives can be added in addition to the above-mentioned colorant, solvent and surfactant.

For example, as antiseptic / antifungal agents, 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 adjuster, any substance can be used as long as it can adjust the pH to 7 or more without adversely affecting the prepared ink composition.

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 Examples thereof include quaternary phosphonium hydroxide, 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, water-soluble ultraviolet absorbers, water-soluble infrared absorbers and the like can be added depending on the purpose.

[0090]

EXAMPLES Examples, reference examples and comparative examples of the present invention will be shown below. In addition, the amount (%) of each component described in the reference example is based on weight. Further, the present invention is not limited to these examples.

Reference Example 1 Carbon black treated with hypochlorous acid 1: Commercial pH
300 g of 2.5 acidic carbon black (trade name Monarch 1300 manufactured by Cabot Corporation) was mixed well with 1000 ml of water, and then 450 g of sodium hypochlorite (effective chlorine concentration 12%) was added dropwise to the mixture at 100 to 105 ° C. for 8 hours. Stir for hours. To this liquid was further added 100 g of sodium hypochlorite (effective chlorine concentration: 12%), and the mixture was dispersed for 3 hours with a horizontal disperser. The resulting slurry is diluted 10 times with water, the pH is adjusted with lithium hydroxide, the salt is desalted and concentrated with an ultrafiltration membrane to an electric conductivity of 0.2 mS / cm, and a carbon black dispersion having a pigment concentration of 15% is obtained. And Coarse particles were removed by centrifugation and filtered with a 1-micron nylon filter to obtain carbon black dispersion 1. Microtrack UP
The average particle size (D50%) measured by A was 95 nm.

Reference Example 2 Carbon black treated with sulfonating agent 2: Commercially available carbon black pigment (“Printex # 8 manufactured by Degussa”)
5 ") was thoroughly mixed with 400 ml of sulfolane, finely dispersed with a bead mill, 15 g of amido sulfuric acid was added, and the mixture was stirred at 140 to 150 ° C for 10 hours. The obtained slurry was put into 1000 ml of ion-exchanged water, and 1200
A surface-treated carbon black wet cake is obtained by a centrifuge at 0 rpm. This carbon black wet cake was redispersed in 2000 ml of ion-exchanged water, the pH was adjusted with lithium hydroxide, and desalting and concentration were performed with an ultrafiltration membrane to obtain a carbon black dispersion liquid having a pigment concentration of 10% by weight. This product was filtered through a nylon filter of 1 micron to obtain carbon black liquid 2. Average particle size is 80n
It was m.

Reference Example 3 Diazo Compound Treated Carbon Black Dispersion 3: Surface Area of 230 m ² / g and DBP Oil Absorption of 70 ml / 100
100 g of carbon black and 34 g of p-amino-N-benzoic acid were mixed and dispersed in 750 g of water, to which 16 g of nitric acid was added dropwise and stirred at 70 ° C. After 5 minutes, a solution of 11 g of sodium nitrite in 50 g of water was added,
It was stirred for another hour. The obtained slurry was diluted 10 times, centrifuged to remove coarse particles, and the pH was adjusted to 8 to 9 with diethanolamine, and desalted and concentrated with an ultrafiltration membrane to obtain a carbon black dispersion having a pigment concentration of 15%. did. This was made into a carbon black dispersion 3 using a polypropylene 0.5 μm filter. Average particle size is 99 nm
Met.

Reference Example 4 Carbon Black Dispersion Treated with Diazo Compound 4: A solution of 2 liters of water and 43 g of sulfanilic acid at about 75 ° C. was stirred with a surface area of 230 m ² / g and 70
Added to 202 g carbon black with ml / 100 g DBPA. The mixture was cooled to room temperature with stirring and 26.2 g of concentrated nitric acid was added. A solution of 20.5 g of sodium nitrite in water was added. An inner salt of 4-sulfobenzenediazonium hydroxide was prepared and reacted with carbon black. The dispersion was stirred until the bubbling that occurred stopped. The obtained slurry is diluted, the pH is adjusted with lithium hydroxide to adjust the pH to 8 to 9, coarse particles are removed by centrifugation, and subsequently desalted and concentrated with an ultrafiltration membrane to disperse carbon black with a pigment concentration of 15%. It was a liquid. This product was filtered through a polypropylene 1 μm filter to obtain a carbon black dispersion liquid 4. The average particle size was 95 nm.

Reference Example 5 Surface Chemically Treated Color Pigment Dispersion: C.I. I. Pigment Yellow 128 was subjected to low temperature plasma treatment to prepare a pigment having a carboxylic acid group introduced. A dispersion of this in ion-exchanged water was desalted and concentrated with an ultrafiltration membrane to obtain a yellow pigment dispersion 1 having a pigment concentration of 15%. The average particle size was 70 nm (yellow dispersion liquid 1). Similarly, as a magenta pigment, C.I. I. Pigment Magenta 122
Was used to prepare a magenta pigment dispersion liquid 1 having a pigment concentration of 15%. The average particle size was 60 nm (magenta dispersion liquid 1). Similarly, as a cyan pigment, C.I. I. Pigment Cyan 15: 3 was used to prepare a cyan pigment dispersion 1 having a pigment concentration of 15%. Cyan dispersion 1) having an average particle size of 80 nm.

When the pH of the ink composition is set to 6 or more, the storage stability of the ink composition can be obtained, and the copy paper and the sticky note used in the office are p.
Most of H has a value of 5 to 6, and the ink composition is discharged onto these recording papers from a fine discharge port of 9 to 60 μm and the weight is 3 n.
flying as a droplet of g-50 ng at 5-20 m / s,
A high image quality can be obtained by recording on so-called plain paper having a Steckigt sizing degree of 3 seconds or more according to the JIS P-8122 test method, with the deposition amount of a single color being 1.5 g / m ² to 30 g / m ² .
A recording method for forming a high-resolution recorded image can be provided. However, if the pH is 9 or higher, the physical properties of the activator of (II) easily change due to decomposition during storage (II).
When using, the pH is preferably 6-9.

Example 1 An ink composition having the following formulation was prepared and adjusted to a pH of 9 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 ink composition. Carbon black dispersion 1 8.0 wt% triethylene glycol 22.5 wt% glycerol 7.5 wt% 2-pyrrolidone 5.0 wt% Activator of specific example (I-1) 2.0 wt% 2-ethyl-1,3- Hexanediol 2.0 wt% Emulsion 3.0 wt% Proxel LV (preservative) 0.2 wt% Ion-exchanged water Remaining amount

Example 2 An ink composition was prepared in the same manner as in Example 1 except that the following composition was used, and the pH was adjusted to 9 with sodium hydroxide. Carbon dispersion 2 10.0 wt% Propylene glycol 30.0 wt% Glycerol 10.0 wt% N-methyl-2-pyrrolidone 2.0 wt% Activator of specific example (I-2) 2.0 wt% 2,2,4- Trimethyl-1,3-pentanediol 2.0 wt% Emulsion 3.0 wt% Proxel LV (preservative) 0.2 wt% Ion-exchanged water Remaining amount

Example 3 An ink composition was prepared in the same manner as in Example 1 except that the following composition was used, and the pH was adjusted to 9 with sodium hydroxide. Carbon dispersion 3 12.0 wt% Dipropylene glycol 20.0 wt% Glycerol 10.0 wt% N-hydroxyethyl-2-pyrrolidone 5.0 wt% Activator of specific example (I-3) 2.0 wt% 2-Ethyl- 1,3-Hexanediol 2.0 wt% Emulsion 3.0 wt% Proxel LV (preservative) 0.2 wt% Ion-exchanged water Remaining amount

Example 4 An ink composition was prepared in the same manner as in Example 1 except that the following composition was used, and the pH was adjusted to 9 with lithium hydroxide. Carbon dispersion 4 10.0 wt% 1,3-butanediol 22.5 wt% Glycerol 7.5 wt% 2-Pyrrolidone 5.0 wt% Activator of specific example (I-4) 2.0 wt% 2,2,4- Trimethyl-1,3-pentanediol 2.0 wt% Emulsion 3.0 wt% Proxel LV (preservative) 0.2 wt% Ion-exchanged water Remaining amount

Example 5 An ink composition was prepared in the same manner as in Example 1 except that the following composition was used, and the pH was adjusted to 9 with lithium hydroxide. Emulsion coating type carbon black dispersion (manufactured by Kao Corporation) 9.0 wt% 2,3-butanediol 22.5 wt% Glycerol 7.5 wt% N-methyl-2-pyrrolidone 3.0 wt% Specific example (I-5) Activator 2.0 wt% 2-Ethyl-1,3-hexanediol 2.0 wt% Proxel LV (preservative) 0.2 wt% Ion-exchanged water Remaining amount

Example 6 An ink composition was prepared in the same manner as in Example 1 except that the following composition was used, and the pH was adjusted to 9 with lithium hydroxide. Self-dispersion type carbon black dispersion (manufactured by Toyo Ink Co., Ltd.) 10.0 wt% 1,4-butanediol 15.0 wt% glycerol 15.0 wt% N-hydroxyethyl-2-pyrrolidone 5.0 wt% Specific example (I-6 ) Activator 2.0 wt% 2,2,4-trimethyl-1,3-pentanediol 2.0 wt% Emulsion 3.0 wt% Proxel LV (preservative) 0.2 wt% Ion-exchanged water Remaining amount

Example 7 An ink composition was prepared in the same manner as in Example 1 except that the following composition was used, and the pH was adjusted to 9 with lithium hydroxide. Carboxyl group-added carbon black (manufactured by Cabot Specialty Chemicals Ink Composition Co., Ltd.) 13.0 wt% 1,3-propanediol 22.5 wt% glycerol 7.5 wt% 2-pyrrolidone 5.0 wt% Specific example (II- 1) Activator 2.0 wt% 2-Ethyl-1,3-hexanediol 2.0 wt% Emulsion 3.0 wt% Proxel LV (preservative) 0.2 wt% Ion-exchanged water Remaining amount

Example 8 An ink composition was prepared in the same manner as in Example 1 except that the following composition was used, and the pH was adjusted to 9 with lithium hydroxide. Sulfone group-added carbon black (manufactured by Cabot Specialty Chemicals Ink Composition Co., Ltd.) 14.0 wt% 1,4-butanediol 22.5 wt% glycerol 7.5 wt% N-methyl-2-pyrrolidone 2.0 wt % Activator of Specific Example (II-2) 2.0 wt% 2,2,4-trimethyl-1,3-pentanediol 2.0 wt% Emulsion 3.0 wt% Proxel LV (preservative) 0.2 wt% Ion exchange Water level

Example 9 An ink composition was prepared in the same manner as in Example 1 except that the following composition was used, and the pH was adjusted to 9 with lithium hydroxide. Carboxyl group-added carbon black (manufactured by Orient Chemical Industry Co., Ltd.) 10.0 wt% 1,5-pentanediol 15.0 wt% glycerol 15.0 wt% N-hydroxyethyl-2-pyrrolidone 2.0 wt% Specific example (II-3 ) Activator 2.0 wt% 2-Ethyl-1,3-hexanediol 2.0 wt% Emulsion 3.0 wt% Proxel LV (preservative) 0.2 wt% Ion-exchanged water Remaining amount

Example 10 An ink composition was prepared in the same manner as in Example 1 except that the following composition was used, and the pH was adjusted to 9 with lithium hydroxide. Microcapsule inclusion type carbon black (manufactured by Dainippon Ink and Chemicals, Inc.) 11.0 wt% 1,6-hexanediol 22.5 wt% glycerol 7.5 wt% 2-pyrrolidone 3.0 wt% Activity of specific example (II-4) Agent 2.0 wt% 2,2,4-trimethyl-1,3-pentanediol 2.0 wt% Proxel LV (preservative) 0.2 wt% Ion-exchanged water Remaining amount

Example 11 An ink composition was prepared in the same manner as in Example 1 except that the following composition was used, and the pH was adjusted to 9 with sodium hydroxide. Polymer dispersant Dispersion type carbon black (manufactured by Dainichiseika Kogyo Co., Ltd.) 8.0 wt% 2-methyl-2,4-pentanediol 22.5 wt% Glycerol 7.5 wt% N-methyl-2-pyrrolidone 5.0 wt% Activator of specific example (III) (R = C6, k = 5) 2.0 wt% 2-ethyl-1,3-hexanediol 2.0 wt% Proxel LV (preservative) 0.2 wt% Ion-exchanged water Remaining amount

Example 12 An ink composition was prepared in the same manner as in Example 1 except that the following composition was used, and the pH was adjusted to 9 with sodium hydroxide. Surfactant-dispersed carbon black (Fuji Dye Co., Ltd.) 8.0 wt% 1,2,6-hexanetriol 30.0 wt% glycerol 10.0 wt% N-hydroxyethyl-2-pyrrolidone 5.0 wt% Specific example (IV ) Activator (R = C6, n = 5) 2.0 wt% 2,2,4-trimethyl-1,3-pentanediol 2.0 wt% emulsion 3.0 wt% Proxel LV (preservative) 0.2 wt% Deionized water remaining

Example 13 An ink composition was prepared in the same manner as in Example 1 except that the following composition was used, and the pH was adjusted to 9 with sodium hydroxide. Carboxyl group-added self-dispersion type carbon black dispersion (manufactured by Taisei Kako Co., Ltd.) 10.0 wt% Trimethylolpropane 20.0 wt% Glycerol 20.0 wt% 2-Pyrrolidone 4.0 wt% Activator of specific example (V) (R) = 6, n = 2, M = 3) 2.0 wt% 2-ethyl-1,3-hexanediol 2.0 wt% Emulsion 3.0 wt% Proxel LV (preservative) 0.2 wt% Ion-exchanged water Remaining amount

Example 14 An ink composition was prepared in the same manner as in Example 1 except that the following composition was used, and the pH was adjusted to 9 with lithium hydroxide. Polymer dispersant Dispersion-type carbon black (manufactured by Mikuni Dye Co., Ltd.) 8.0 wt% Trimethylolethane 22.5 wt% Glycerol 7.5 wt% N-Methyl-2-pyrrolidone 2.0 wt% Activator of Specific Example (VI) ( p + q = 15, p + q = 0 mixture) 2.0 wt% 2,2,4-trimethyl-1,3-pentanediol 2.0 wt% Proxel LV (preservative) 0.2 wt% Ion-exchanged water remaining amount

(Example 15) A cyan ink composition was prepared in the same manner as in Example 1 except that the following composition was used, and the pH was adjusted to 9 with lithium hydroxide. Cyan Dispersion 1 6.0 wt% Urea 22.5 wt% Glycerol 7.5 wt% N-Hydroxyethyl-2-pyrrolidone 5.0 wt% ECTD-3NEX (Nikko Chemicals anionic surfactant) 2.0 wt% 2-ethyl -1,3-Hexanediol 2.0 wt% Emulsion 3.0 wt% Proxel LV (preservative) 0.2 wt% Ion-exchanged water Remaining amount

Example 16 A magenta ink composition was prepared in the same manner as in Example 1 except that the following composition was used, and the pH was adjusted to 9 with lithium hydroxide. Magenta dispersion 1 6.0 wt% 3-dimethylimidazolidinone 15.0 wt% Glycerol 15.0 wt% 2-Pyrrolidone 5.0 wt% ECTD-6NEX (Nikko Chemicals anionic surfactant) 2.0 wt% 2,2 , 4-Trimethyl-1,3-pentanediol 2.0 wt% Emulsion 3.0 wt% Proxel LV (preservative) 0.2 wt% Ion-exchanged water Remaining amount

Example 17 A yellow ink composition was prepared in the same manner as in Example 1 except that the following composition was used, and the pH was adjusted to 9 with sodium hydroxide. Yellow Dispersion 1 6.0 wt% Multitose 25.0 wt% Glycerol 15.0 wt% N-Methyl-2-pyrrolidone 5.0 wt% Dispanol TOC (Nonionic surfactant made by NOF Corporation) 2.0 wt% 2-Ethyl- 1,3-Hexanediol 2.0 wt% Emulsion 3.0 wt% Proxel LV (preservative) 0.2 wt% Ion-exchanged water Remaining amount

Comparative Example 1 An ink composition having the following formulation was prepared and adjusted to a pH of 9 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 ink composition. Carboxyl group-added carbon black (manufactured by Cabot Specialty Chemicals, Inc.) 5.0 wt% ethylene glycol 15.0 wt% glycerol 5.0 wt% 2-pyrrolidone 2.0 wt% ECTD-3NEX (Nikko Chemicals anionic surfactant) Agent) 1.0 wt% 2-ethyl-1,3-hexanediol 2.0 wt% Emulsion 3.0 wt% Proxel LV (preservative) 0.2 wt% Ion-exchanged water Remaining amount

Comparative Example 2 An ink composition was prepared in the same manner as in Comparative Example 1 except that the following composition was used, and the pH was adjusted to 9 with lithium hydroxide. Polymer dispersant Dispersion type carbon black (manufactured by Dainichiseika Co., Ltd.) 5.0 wt% Diethylene glycol 15.0 wt% Glycerol 5.0 wt% N-methyl-2-pyrrolidone 2.0 wt% ECTD-6NEX (Nikko Chemicals anion system) Surfactant) 1.0 wt% 2,2,4-trimethyl-1,3-pentanediol 2.0 wt% Proxel LV (preservative) 0.2 wt% Ion-exchanged water Remaining amount

Comparative Example 3 An ink composition was prepared in the same manner as in Comparative Example 1 except that the following composition was used, and the pH was adjusted to 9 with lithium hydroxide. Surfactant-dispersed carbon black (manufactured by Fuji Dye Co., Ltd.) 5.0 wt% Triethylene glycol 15.0 wt% Glycerol 5.0 wt% N-hydroxyethyl-2-pyrrolidone 2.0 wt% Dispanol TOC (Non-Fruit nonion) System surfactant) 1.0 wt% 2-ethyl-1,3-hexanediol 2.0 wt% Emulsion 3.0 wt% Proxel LV (preservative) 0.2 wt% Ion-exchanged water Remaining amount

Comparative Example 4 An ink composition was prepared in the same manner as in Example 1 except that the following composition was used, and the pH was adjusted to 9 with sodium hydroxide. Polymer dispersant Dispersion type carbon black (manufactured by Mikuni dye company) 5.0 wt% Ethylene glycol 15.0 wt% Glycerol 5.0 wt% 2-Pyrrolidone 2.0 wt% ECTD-6NEX (Nikko Chemicals anionic surfactant) 1.0 wt% 2,2,4-trimethyl-1,3-pentanediol 2.0 wt% Proxel LV (preservative) 0.2 wt% Ion-exchanged water Remaining amount

Comparative Example 5 An ink composition was prepared in the same manner as in Example 1 except that the following composition was used, and the pH was adjusted to 9 with lithium hydroxide. Self-dispersion type carbon black dispersion (manufactured by Taisei Kako Co., Ltd.) 5.0 wt% Diethylene glycol 15.0 wt% Glycerol 5.0 wt% N-Methyl-2-pyrrolidone 2.0 wt% ECTD-6NEX (Nikko Chemicals anionic surfactant) ) 1.0 wt% 2,2,4-trimethyl-1,3-pentanediol 2.0 wt% Emulsion 3.0 wt% Proxel LV (preservative) 0.2 wt% Ion-exchanged water Remaining amount

The viscosities of the black ink compositions of Examples 1 to 14, the cyan, magenta and yellow ink compositions of Examples 15 to 17 and the ink compositions of Comparative Examples 1 to 5 are shown in Table 1 below.

[Table 1]

Next, the above Examples 1 to 17 and Comparative Examples 1 to 5
The following test was conducted on The results are shown in Table 2.

1) Image sharpness (1) Ink composition jet printer EM-900
(Manufactured by Seiko Epson Corp.), the head drive voltage, frequency, and pulse width were changed, and printing was performed on each of the following papers. With respect to the printing pattern, each of the yellow, magenta, and cyan color ink compositions was printed at 100% duty, and the black ink composition filled with the black ink composition of the present invention printed characters at the same time. The printing conditions are: Mj 35 pl, Vj 20 m / sec, frequency 1 kHz, recording density 360
dpi, one-pass printing.

(2) Bubble jet type ink composition jet printer BJC430 manufactured by Canon Inc. and bubble jet type ink composition jet printer hpdiskjet815 manufactured by HP Co., Ltd. Vj is 2
0m / sec, frequency 1kHz, recording density 360d
The solid and the characters were printed by pi and one-pass printing.

(3) Solid ink and characters were printed by one-pass printing under the conditions that the driving voltage, frequency, and pulse width of the head of the ink composition jet printer IPSiO Jet300 manufactured by Ricoh Co., Ltd. were changed.

After the print was dried, the bleeding at the boundary between the two-color overlapping portions, the image bleeding, the color tone, and the image density were comprehensively examined visually and by a reflection type color spectrophotometric densitometer (manufactured by X-Rite Co.), and according to the evaluation criteria. It was judged. The printing test paper used is the following My Paper (manufactured by NBS Ricoh) Paper source S / recycled paper (manufactured by NBS Ricoh) PB paper (manufactured by Canon) Multi-Ace (manufactured by Fuji Xerox Office Supply) Yamayuri (Honshu) LH paper (manufactured by Fuji Xerox Office Supply Co.) Xerox 4024 paper (manufactured by Fuji Xerox Office Supply Co.) Neenah Bond paper (manufactured by Kimberly Clark Co.)

(Judgment Criteria) A: Clear printing without blurring on all paper. B: Some paper (recycled paper) has whisker-like bleeding. Δ: Whisker-like bleeding occurs on all paper. X: Blurring occurs so that the outline of the character is not clear.

2) Dryability of Image The filter paper was pressed against the image after printing under constant conditions, and the time until the ink composition was not transferred to the filter paper was measured. When any of the papers was dried within 10 seconds, it was judged as ◯.

3) Storage stability Each ink composition was placed in a polyethylene container and kept at -20 ° C.
It was stored at 5 ° C., 20 ° C. and 70 ° C. under each condition for 3 months, and the surface tension after storage, the viscosity, and the presence or absence of precipitate precipitation were examined. The case where there was no change in physical properties, etc. under any conditions of storage was marked as ◯.

4) Reliability at the time of printing suspension Using the head of Ricoh's printer IPSiO Jet300, it is checked how much printing can be resumed even if the printing is suspended without performing capping, cleaning, etc. during printer operation, and checking how much. Is the injection direction shifted in the time (second) of
Alternatively, the reliability of the discharged liquid droplets was evaluated by changing the weight of the liquid droplets. The results are shown in Table 2.

[0129]

[Table 2]

[0130]

EFFECTS OF THE INVENTION (1) Although the penetrating ink composition has been excellent in quick-drying property and fixing property, it has a problem in image quality such as feathering, decrease in print density and color bleeding.
In the high viscosity ink composition having a pigment concentration of 6 wt% or more and 8.0 cps or more according to the present invention, Mj [volume pl of one ink composition droplet (picoliter)] is 14 to 35 p.
1, Vj [speed of ink composition droplet m / sec] is 6 to
20m / sec, frequency 1kHz or more, resolution 30
Under one-pass printing conditions of 0 dpi or more, it was possible to achieve high-quality image quality on plain paper, comparable to a laser printer. That is, feathering and color bleed are similar to those of a laser, and image density is 1.4 to 1.5 (conventional 1.1 to
1.2). Furthermore, since the pigment aggregates on the paper surface, the strike-through is remarkably reduced as compared with the conventional case, and the double-sided printing becomes possible (the strike-through density: 0.02 to 0.04 / conventional 0.
2 to 0.3).

(2) Polyol having 8 or more carbon atoms and (I)
The surface tension of the ink composition is 40 dyn / cm or less due to the interaction of the surfactants of (VI) to (VI), and the pigment concentration is 6 wt% or more and the viscosity is 8.0 cps or more.
It quickly fixes to most recording materials and has sufficient marker resistance. In addition, the wetness to the head member was improved, the bubble discharge property of the ink composition was improved, the frequency response was improved, and the ejection stability was significantly improved.

(3) The ink composition of the present invention is a high-viscosity ink composition having a high pigment concentration. However, due to the effect of the selected wetting agent, the ink composition of the nozzle is higher than that of the conventional high-pigment / high-viscosity ink composition. Stable printing is possible without clogging.

(4) The ink composition of the present invention is a high-viscosity ink composition with a high pigment concentration, but the storage stability is higher than that of the conventional high-pigment / high-viscosity ink composition due to the effect of the selected wetting agent. Has improved significantly.

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Claims (21)

[Claims] 1. A pigment, a wetting agent, a penetrant having a solubility of 0.1 to less than 4.5% by weight in water at 25 ° C., an anionic or nonionic surfactant, a water-soluble organic solvent,
An ink composition containing at least water and water, having a pigment concentration of 6 wt% or more and a composition viscosity of 5 cps (25 ° C.) or more. 2. The composition has a viscosity of 8 to 20 cps (25 ° C.)
The ink composition according to claim 1, wherein 3. The ink composition according to claim 1, wherein the pigment concentration is 8 to 20 wt% (25 ° C.). 4. The surface tension is 40 dyne / cm (25
C) or less, The ink composition according to any one of claims 1 to 3. 5. The ink composition according to claim 1, wherein the pigment is a self-dispersion pigment. 6. The ink composition according to claim 5, wherein the self-dispersion pigment has at least one group selected from the group consisting of a carboxyl group, a sulfone group, a carbonyl group, and a hydroxyl group on the surface. . 7. The self-dispersion pigment is carbon black, and at least one hydrophilic group is treated with a diazo compound, an oxidation treatment, a hypochlorous acid treatment, a sulfonating agent treatment, or humin on the surface of the carbon black. The ink composition according to claim 5, wherein the ink composition is formed by acid treatment. 8. The ink composition according to claim 1, wherein the average particle size of the pigment is 0.16 μm or less. 9. A penetrant having a solubility of less than 0.1-4.5% by weight in water at 25 ° C. is 2-ethyl-1,
The ink composition according to any one of claims 1 to 8, which is 3-hexanediol and / or 2,2,4-trimethyl-1,3-pentanediol. 10. An anionic surfactant is one of the following general formulas (I), (II), (III), (IV), (V) and (V).
The ink composition for ink jet recording according to any one of claims 1 to 9, which is at least one selected from the surfactants of I). [Chemical 1] (R ₁ is an optionally branched alkyl group having 6 to 14 carbon atoms, m is an integer of 3 to 12, M is an alkali metal ion, quaternary ammonium, quaternary phosphonium or alkanolamine.) Chemical 2] (R ₂ is an optionally branched alkyl group having 5 to 16 carbon atoms, M is an alkali metal ion, quaternary ammonium, quaternary phosphonium or alkanolamine.) (R is a branched 6 to 14 carbon chain, k is 5
It is an integer of 20. ) [Chemical 4] (R is a carbon chain having 6 to 14 carbon atoms which may be branched, n
Is an integer of 5 to 20. ) [Chemical 5] (R is a carbon chain having 6 to 14 carbon atoms which may be branched,
m and n are integers of 5 to 20. ) [Chemical 6] (P and q are integers of 0 to 40.) 11. An anionic surfactant is represented by the general formula (II
The ink composition according to claim 1, which is a combination of I) and the surfactant of the general formula (VI). 12. The ink composition according to claim 1, wherein the wetting agent is represented by the following general formula (VII). [Chemical 7] (However, in the above formula, n represents an integer of 5 to 8.) 13. The ink composition according to claim 1, wherein the wetting agent is at least one selected from the group consisting of polyols, lactams, ureas, and sugars. 14. The ink composition according to claim 13, wherein the saccharide is at least one selected from the group consisting of maltose, sorbitose, gluconolactone, and maltose. 15. The ink composition according to claim 1, which is used in an inkjet recording method. 16. An ink jet recording method using the ink composition according to any one of claims 1 to 15. 17. The volume of one ink composition droplet flying by one electric signal is 14 to 35 pl (picoliter),
2. The recording is performed under a one-pass printing condition in which the speed of the ink composition droplets is 6 to 20 m / sec, the frequency is 1 KHz or more, and the resolution is 300 dpi or more.
6. The inkjet recording method according to 6. 18. The ink jet recording method according to claim 16 or 17, wherein the ink composition is ejected by causing thermal energy and / or mechanical energy to act on the ink composition. 19. An ink jet recording apparatus comprising the ink composition according to claim 1. 20. A recorded matter, which is recorded using the ink composition according to any one of claims 1 to 15. 21. A recorded matter, which is recorded by using the ink jet recording method according to any one of claims 16 to 18.