JPH1180636A - Aqueous pigment ink, ink-jet recording method using it and ink-jet recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous pigment ink which, although containing carbon black as a coloring material, offers a high printing density and a printed image with good image characteristics showing a complete resistance to water and light, has a high storage stability and is stably discharged without any clogging and an ink-jet recording method and device using ink. SOLUTION: An aqueous pigment ink comprises at least a coloring material, a water-soluble organic solvent wherein this coloring material is dispersed and water. The coloring material comprises a self-dispersing carbon black, to the surface of which at least one hydrophilic group is bound directly or through other atomic groups. The average particle size A (nm) and the degree of blackness index B of the self-dispersing carbon black satisfy formulae A>=20 and B/A>=5.0.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an aqueous pigment ink,
More specifically, the present invention relates to an aqueous pigment ink using a self-dispersion type carbon black suitable for ink jet recording as a coloring material, an ink jet recording method using the ink, and an ink jet recording apparatus.

[0002]

2. Description of the Related Art Conventionally, as a black colorant for printing ink,
Carbon black, which has excellent fastness such as water resistance and light resistance, is widely used. However, in order to use carbon black as a colorant (coloring material) for aqueous inks, it is necessary to stabilize carbon black in an aqueous medium. Dispersion is required. On the other hand, since carbon black generally has poor dispersibility, a method of adding a dispersant to an ink to disperse carbon black in an aqueous medium has been adopted as a means for obtaining a uniform dispersion system. . However, satisfactory dispersibility cannot be obtained even by the method using this dispersant, and therefore, there has been a problem that long-term storage stability is inferior especially in an ink in which carbon black is dispersed.

On the other hand, in general, in order for ink to be favorably used for ink jet recording, it is required that the ink be ejected as stable droplets from a fine tip of an ink jet recording head. For this reason, the ink for ink jet recording needs to have performance such that the ink does not solidify due to drying of the orifice of the ink jet recording head. However, when the ink containing the dispersant described above is used for ink jet recording, the polymer material forming the dispersant adheres to the orifice or the like, and is not redissolved. May cause non-ejection of the image. In addition, the aqueous pigment ink containing a dispersant is viscous, and when performing continuous ejection over a long period of time and high-speed printing, resistance occurs in the path to the nozzle tip, making ejection unstable and making smooth recording difficult. There was also the problem of becoming. Further, as in the normal case, a sufficient image density is required for performing black printing by ink jet recording, so that a certain level of density is required for carbon black contained in the ink.

[0004] On the other hand, the following reports have been made to solve the various problems of ink containing a dispersant for the purpose of dispersing carbon black well. For example, JP-A-3-234772, JP-A-5-202324, JP-A-6-19
No. 36 describes an ink in which the maximum particle size, average particle size, particle size distribution and the like of a pigment are specified. Also, JP-A-8
JP-A-151546 describes an ink in which carbon blacks having different particle diameters are used and the ratio thereof is limited. Further, JP-A-3-134073 describes an ink-jet ink in which a dispersion having excellent storage stability and excellent dischargeability in a bubble jet recording apparatus can be easily obtained.

Further, JP-A-5-186704 and JP-A-8-3498 disclose that a water-soluble group is introduced into the surface of carbon black so that the carbon can be added to the ink without using a dispersant. A self-dispersible carbon black capable of stably dispersing the black is described.

[0006]

However, the above-mentioned Japanese Patent Application Laid-Open Nos. Hei 3-234772 and Hei 5-2023 have been disclosed.
No. 24 and JP-A-6-1936, in the case of an ink in which the pigment particle size and the like are specified, even if the storage stability and the dispersion stability are good, the resin or the dispersant may be used. Due to the inclusion, clogging and non-discharge of liquid droplets may occur, and when performing continuous discharge and high-speed printing for a long time, resistance is caused in the path to the nozzle tip and discharge is unstable. And smooth recording may be difficult.

Also, in the case of the ink described in the above-mentioned Japanese Patent Application Laid-Open No. 8-151546, clogging and non-ejection of droplets occur due to the inclusion of resin or dispersant. When performing continuous ejection and high-speed printing for a long time, resistance occurs in the path to the tip of the nozzle, and the ejection becomes unstable, making it difficult to perform smooth recording. Further, after long-term storage, the carbon black having a large particle size and the carbon black having a small particle size may be separated from each other, resulting in a problem that the density of an obtained image is different. Further, the above-mentioned Japanese Patent Application Laid-Open No.
The ink described in JP-A-73 is easy to obtain a dispersion excellent in storage stability and excellent dischargeability in a bubble jet recording apparatus, but tends to be insufficient in print density and has high print density in excellent print quality. There was a problem that it was difficult to obtain an image.

In the case of the inks described in JP-A-5-186704 and JP-A-8-3498 which do not use the above-mentioned dispersants, problems of clogging and non-ejection of liquid droplets occur. Also, when performing continuous ejection over a long period of time and high-speed printing, ink that contains a dispersant causes resistance in the path to the nozzle tip, causing ejection to be unstable, making smooth printing difficult. Although there is no problem that the print density is high, it may not be possible to achieve both high print density and storage stability. That is, in the case of an ink using self-dispersion type carbon black, if the particle size of the carbon black is too large, the carbon black particles may settle when stored for a long time, Is too small, the print density may be too low.

Therefore, an object of the present invention is to provide an ink using carbon black as a coloring material, which, when used in ink jet recording, has a high print density, good print quality, and complete water resistance and complete light fastness. Aqueous pigment ink which can provide an image excellent in image characteristics satisfying the above, furthermore has excellent storage stability of the ink, and at the same time, can perform stable ejection without causing clogging, and an ink jet recording method using the ink And an ink jet recording apparatus.

[0010]

The above object is achieved by the present invention described below. That is, the present invention comprises at least a coloring material, a water-soluble organic solvent dispersing the coloring material, and water, and at least one hydrophilic group is bonded to the surface of the carbon black directly or via another atomic group as the coloring material. In the aqueous pigment ink containing the self-dispersible carbon black, when the average particle diameter of the self-dispersible carbon black is A (nm) and the blackness index is B, A and B Is a self-dispersible carbon black that satisfies the following two formulas, an aqueous pigment ink, an inkjet recording method and an inkjet recording apparatus using the ink. A ≧ 20 B / A ≧ 5.0 (The blackness index in the above formula is a value measured by a nigrometer.)

As described above, in the case of an aqueous pigment ink, a dispersant is usually added to disperse the pigment in the ink. This is likely to cause adverse effects. For example, when using a polymer type dispersant,
The face of the head may be easily wet or clogged. Further, when a surfactant-type dispersant is used, there are problems that the print density of the obtained image is insufficient and the print quality is poor, and that the face surface of the head portion is easily wetted.

On the other hand, in the case of the specific carbon black contained in the black ink used in the above-described ink jet recording method and ink jet recording apparatus of the present invention, the carbon black can be used without containing a dispersant. Since the ink itself is so-called self-dispersed in the ink, the above-mentioned adverse effects due to the inclusion of the dispersant do not occur.
That is, the carbon black used in the present invention has at least one kind of hydrophilic group bonded directly or via another atomic group to the surface thereof. Since the carbon black itself can maintain a stable dispersion state in an aqueous medium such as water, a dispersant for dispersing the pigment in the ink is not particularly required. As a result, there is no adverse effect caused by including the dispersant in the ink as described above.

However, as described above, in the case of ink using self-dispersion type carbon black,
If the particle size of the carbon black is too large, the carbon black particles may settle when stored for a long period of time, and if the particle size is too small, the print density may be too low, resulting in storage stability. There is a problem of compatibility between high printing density and high printing density.

The present inventors have conducted intensive studies in order to solve the above-mentioned problems of the prior art. As a result, when the average particle diameter of carbon black is A (nm) and the blackness index of carbon black is B, If the following relationship is established between A and B, when ink-jet recording is performed using the ink, a high-quality image having a high print density is obtained, and the ink is stored for a long time. In this case, the inventors have found that there is no problem that the carbon black particles settle and storage stability of the ink is impaired. A ≧ 20 B / A ≧ 5.0 Further, according to the study of the present inventors, if the following relationship is established between the average particle diameter A (nm) of carbon black and the blackness index B, The present invention was found that, when ink-jet recording was performed using the ink, a high-quality image with higher print density was obtained, and the long-term storage stability of the ink was also ensured. . A ≧ 20 B / A ≧ 10.0

[0015]

Next, the present invention will be described in more detail with reference to preferred embodiments. The reason that the aqueous pigment ink of the present invention can obtain the above-mentioned excellent effects is considered as follows. First, if the average particle size A of the carbon black is less than 20 nm, an image having a sufficient print density cannot be obtained. However, even if the average particle size of the carbon black is 20 nm or more and has a size capable of expressing a sufficient print density when an image is formed, particularly when the carbon black particles are too large, a dispersant is used. In a self-dispersion type carbon black that is not used, the dispersion stability cannot be secured, and the carbon black particles may settle when stored for a long period of time.

On the other hand, the blackness of carbon black is generally higher as the particle size of the carbon black is smaller and the aggregates are smaller, but in a system in which the carbon black is dispersed, such as an ink-jet ink. The surface properties (pH, volatile content) of carbon black also have a significant effect on blackness. It is also known that carbon black having a high degree of blackness cannot always form an image having high hiding power and high print density. The inventors of the present invention have conducted various studies on these facts and found that the average particle size A of the self-dispersible carbon black is
And the value B / of the ratio of the carbon black to the blackness index B of the carbon black
It has been found that A has a relationship between the dispersion stability of carbon black in the inkjet ink and the print density that appears when an image is formed. Therefore, in the present invention, the value B / A of the ratio between the blackness index B of the self-dispersion type carbon black and the average particle size A of the carbon black is adopted, and the dispersion stability of the carbon black in the inkjet ink is Various investigations were made on the conditions of the self-dispersion type carbon black which can achieve compatibility with high printing density when an image is formed.

As a result, a self-dispersible carbon black having an average particle diameter of carbon black of 20 nm or more and a B / A value of 5.0 or more, more preferably 10.0 or more, is used as a pigment for an ink-jet ink. For example, there is no adverse effect caused by including a dispersant, and the dispersion stability of the self-dispersible carbon black is ensured over a long period of time, and a sufficient print density can be exhibited when an image is formed. It was found that ink was obtained. That is, if the average particle size A of the carbon black is less than 20 nm, an image having a sufficient print density cannot be obtained. Further, even if the average particle size A of the self-dispersible carbon black is 20 nm or more, the B / A When the value is less than 5.0, an ink capable of exhibiting a sufficient print density cannot be obtained if the dispersion stability is ensured, and if the ink is capable of exhibiting a sufficient print density, carbon black particles are too large. Therefore, the dispersion stability cannot be secured, and the carbon black particles may settle.

Here, the average particle diameter A (nm) of the self-dispersible carbon black is an average particle diameter obtained by a method described below. That is, the value of the average particle diameter A used in the present invention is measured by an Ender device.

The blackness index B of the self-dispersible carbon black used in the present invention can be determined by a measurement with a nigrometer. That is, a method of reading a scale when the brightness of the light reflected by the light source from the light source by the carbon black kneaded with linseed oil passes through the non-plated portion and the light reflected by the plated portion matches.

Hereinafter, each material constituting the aqueous pigment ink of the present invention will be described. As a coloring material constituting the aqueous pigment ink of the present invention, a self-dispersion type carbon black having the average particle diameter A (nm) and the blackness index B satisfying the above relationship and having the following constitution is used. That is,
In the present invention, a self-dispersion type carbon black in which at least one hydrophilic group is bonded to the surface of the carbon black directly or through another atomic group is used. As a result, there is no need for a dispersant for dispersing carbon black as in the conventional ink. The self-dispersion type carbon black used in the present invention is preferably ionic, and for example, anionically charged or cationically charged carbon black is suitable.

The hydrophilic group bonded to the surface of the anionic charged carbon black includes, for example, -CO
_{OM, -SO 3 M, -PO 3} HM, -PO 3 M 2, -SO 2
NH ₂ , —SO ₂ NHCOR (wherein M represents a hydrogen atom, an alkali metal, ammonium or organic ammonium, and R represents an alkyl group having 1 to 12 carbon atoms and a phenyl group which may have a substituent) Or a naphthyl group which may have a substituent.). In the present invention, among these, -COOM, it is preferable to use a -SO ₃ M is attached to the carbon black surface.

The "M" in the above hydrophilic group includes, for example, lithium, sodium and potassium as alkali metals, and mono- to trimethylammonium, mono-triethylammonium and mono- to triethylammonium as organic ammonium. Trimethanol ammonium. As a method for obtaining anionic charged carbon black, a method for introducing -COONa to the surface of carbon black includes, for example, a method for oxidizing carbon black with sodium hypochlorite. However, it is not limited to these.

The hydrophilic group bonded to the surface of the cationically charged carbon black is, for example, preferably a quaternary ammonium group, and more preferably, the following quaternary ammonium group. In the above, one in which any of these is bonded to the surface of carbon black is preferably used as a coloring material.

[0024]

Embedded image

As a method for producing a cationic self-dispersion type carbon black having a hydrophilic group as described above, for example, as a method for bonding an N-ethylpyridyl group having the following structure, carbon black is used. Examples include a method of treating with 3-amino-N-ethylpyridinium bromide, but of course, the present invention is not limited to this.

[0026]

Embedded image

In the present invention, the above-mentioned hydrophilic groups may be bonded to the surface of carbon black via another atomic group. Examples of the other atomic group include an alkyl group having 1 to 12 carbon atoms, a phenyl group which may have a substituent, and a naphthyl group which may have a substituent. Specific examples of the hydrophilic group described above is bonded to the surface of carbon black via other atomic group, for _{example, -C 2 H 4 COOM, -PhSO} 3 M, -C 5
H ₁₀ NH ₃ ^{+ and the} like, but of course, the present invention is not limited to these.

The self-dispersion type carbon black used in the aqueous pigment ink of the present invention is cationically or anionically charged by a hydrophilic group on the surface of the carbon black, and has water dispersibility by repulsion of ions. The hydrophilicity is also improved by the hydrophilic group. Therefore, an aqueous pigment ink that is stably dispersed in an aqueous medium without increasing the particle size or viscosity of the pigment even after being left for a long time is obtained.

In the present invention, the above-mentioned self-dispersion type carbon black is not limited to one type, and the color tone may be adjusted by using a mixture of two or more types. The amount of the self-dispersible carbon black in the pigment ink of the present invention is preferably 0.1 to 15% by weight, more preferably 1 to 15% by weight, based on the total weight of the ink.
To 10% by weight. Further, the color tone of the ink may be adjusted by using a dye in addition to the self-dispersion type carbon black.

The aqueous pigment ink of the present invention may contain a compound represented by the following general formula as a humectant. _{H- (CH 2) m -C -} ((CH 2) n OH) 3 (. In the formula, m and n each represent an integer of 1 to 5) The content of the humectant as described above The amount is preferably 1 to 30% by weight, more preferably 1 to 10% by weight, based on the total amount of the aqueous pigment ink.

The aqueous medium contained in the aqueous pigment ink of the present invention comprises a mixed solvent of water and a water-soluble organic solvent. As the water-soluble organic solvent, those having an effect of preventing drying of the ink are particularly preferable. It is desirable to use deionized water instead of general water containing various ions.

As the water-soluble organic solvent used in the present invention, specifically, for example, methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol Alkyl alcohols having 1 to 5 carbon atoms such as isobutyl alcohol and n-pentanol; amides such as dimethylformamide and dimethylacetamide; ketones or keto alcohols such as acetone and diacetone alcohol; tetrahydrofuran;
Ethers such as dioxane; oxyethylene or oxypropylene copolymers such as diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol and polypropylene glycol; ethylene glycol, propylene glycol, trimethylene glycol; Alkylene glycols having an alkylene group containing 2 to 6 carbon atoms, such as triethylene glycol and 1,2,6-hexanetriol; glycerin; trimethylolethane, trimethylolpropane; ethylene glycol monomethyl (or ethyl) ether, diethylene glycol Lower alkyl ethers such as monomethyl (or ethyl) ether and triethylene glycol monomethyl (or ethyl) ether Ters; lower dialkyl ethers of polyhydric alcohols such as triethylene glycol dimethyl (or ethyl) ether and tetraethylene glycol dimethyl (or ethyl) ether; alkanolamines such as monoethanolamine, diethanolamine and triethanolamine; sulfolane; N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone and the like can be mentioned. The water-soluble organic solvents as described above can be used alone or as a mixture.

The content of the above water-soluble organic solvent contained in the aqueous pigment ink of the present invention is not particularly limited, but is preferably in the range of 3 to 50% by weight based on the total weight of the ink. . The content of water contained in the ink is preferably in the range of 50 to 95% by weight based on the total weight of the ink. In addition, the aqueous pigment ink of the present invention can contain an antifoaming agent, a preservative, a fungicide, and the like, if necessary, in addition to the above components, in order to obtain an ink having desired physical properties. Further, a commercially available water-soluble dye or the like can be added.

As described above, the aqueous pigment ink of the present invention
It is particularly effective when used in ink jet recording. Ink jet recording methods include a recording method in which mechanical energy is applied to the ink to discharge the ink, and an ink jet recording method in which thermal energy is applied to the ink to discharge the ink by foaming of the ink. The aqueous pigment ink of the present invention is particularly suitable.

Next, an example of the ink jet recording apparatus of the present invention suitable for performing recording using the above-described aqueous pigment ink of the present invention will be described below. First, an example of a head configuration which is a main part of an ink jet recording apparatus using thermal energy is shown in FIG. 1 and FIG. FIG. 1 is a cross-sectional view of the head 13 along the ink flow path, and FIG.
It is a sectional view in the -B line. The head 13 is obtained by bonding a glass, ceramic, silicon or plastic plate or the like having a flow path (nozzle) 14 through which ink passes to a heating element substrate 15. The heating element substrate 15 includes a protective layer 16 formed of silicon oxide, silicon nitride, silicon carbide, or the like, electrodes 17-1 and 17-2 formed of aluminum, gold, an aluminum-copper alloy, or the like, HfB ₂ , TaN, TaA.
1, a heat-generating resistor layer 18 formed of a material having a high melting point, a heat storage layer 19 formed of thermally oxidized silicon, aluminum oxide, or the like, and a substrate 20 formed of a material having good heat dissipation properties such as silicon, aluminum, or aluminum nitride. Is made up of

The electrodes 17-1 and 17- of the head 13
When a pulse-like electric signal is applied to the area 2, the area indicated by n on the heating element substrate 15 rapidly generates heat, bubbles are generated in the ink 21 in contact with the surface, and the meniscus 23 is protruded by the pressure. , Ink 21 is discharged through the nozzle 14 of the head, and the ink droplet 24 is discharged from the discharge orifice 22.
And fly toward the recording material 25. In FIG.
FIG. 2 shows an external view of an example of a multi-head in which many heads shown in FIG. This multi-head has a multi-nozzle 26
And a heat generating head 28 similar to that described with reference to FIG.

FIG. 4 shows an example of an ink jet recording apparatus incorporating this head. In FIG. 4, reference numeral 61 denotes a blade as a wiping member, one end of which is held and fixed by a blade holding member, and forms a cantilever. The blade 61 is arranged at a position adjacent to the recording area of the recording head 65, and in the case of this example,
The recording head 65 is held in a protruding form in the movement path.

Reference numeral 62 denotes a cap on the protruding opening surface of the recording head 65, which is disposed at a home position adjacent to the blade 61, moves in a direction perpendicular to the moving direction of the recording head 65, and comes into contact with the ink discharge opening surface. And a configuration for performing capping. Further, reference numeral 63 denotes an ink absorber provided adjacent to the blade 61, which is held in a form protruding into the movement path of the recording head 65, similarly to the blade 61. The blade 61, the cap 62 and the ink absorber 63 constitute an ejection recovery section 64, and the blade 61
In addition, moisture, dust, and the like are removed from the ejection port surface by the ink absorber 63.

Reference numeral 65 denotes a discharge energy generating means,
A recording head 66 for performing recording by discharging ink onto a recording material facing a discharge port surface having discharge ports, and 66 is a recording head 65
Is a carriage for moving the recording head 65 by mounting the same. The carriage 66 is slidably engaged with the guide shaft 67, and a part of the carriage 66 is connected to a belt 69 driven by a motor 68 (not shown). As a result, the carriage 66 can move along the guide shaft 67, and the recording head 65 can move the recording area and the adjacent area.

Reference numeral 51 denotes a paper feeding unit for inserting a recording material;
52 is a paper feed roller driven by a motor (not shown). With such a configuration, the recording material is fed to a position facing the discharge port surface 65 of the recording head, and is discharged to a discharge section provided with a discharge roller 53 as recording proceeds. In the above configuration, when the recording head 65 finishes recording and returns to the home position, the cap 62 of the ejection recovery unit 64 is retracted from the moving path of the recording head 65.
The blade 61 protrudes into the movement path. as a result,
The ejection port of the recording head 65 is wiped.

When capping is performed by contacting the cap 62 with the ejection surface of the recording head 65, the cap 62 moves so as to protrude into the moving path of the recording head. When the recording head 65 moves from the home position to the recording start position, the cap 62 and the blade 61 are at the same positions as the positions at the time of the wiping described above. As a result,
Also in this movement, the ejection port surface of the recording head 65 is wiped. The above-described movement of the print head to the home position is performed not only at the end of printing or at the time of ejection recovery, but also at a predetermined interval while the print head moves through the printing area for printing to the home position adjacent to the printing area. Then, the wiping is performed along with this movement.

FIG. 5 is a diagram showing an example of an ink cartridge containing ink supplied to a recording head via an ink supply member, for example, a tube. Here, reference numeral 40 denotes an ink storage section storing the supply ink, for example, an ink bag, and a rubber stopper 42 is provided at the tip thereof. By inserting a needle (not shown) into this stopper 42,
The ink in the ink bag 40 can be supplied to the head. 4
Reference numeral 4 denotes an ink absorber for receiving waste ink. The ink container preferably has a liquid contact surface with ink formed of polyolefin, particularly polyethylene.

The ink jet recording apparatus used in the present invention is not limited to the one in which the head and the ink cartridge are separated as described above, but may be the one in which they are integrated as shown in FIG. It is preferably used. In FIG. 6, reference numeral 70 denotes a recording unit, in which an ink container containing ink, for example, an ink absorber is stored, and the ink in the ink absorber is transferred from a head unit 71 having a plurality of orifices. It is configured to be discharged as droplets. It is preferable for the present invention to use polyurethane, cellulose, polyvinyl acetate or polyolefin resin as the material of the ink absorber.
Further, a structure may be used in which the ink storage unit is an ink bag in which a spring or the like is provided inside without using an ink absorber. 72
Is an atmosphere communication port for communicating the inside of the cartridge with the atmosphere. This recording unit 70 is used in place of the recording head 65 shown in FIG.
6 is detachable.

Next, as a preferred example of an ink jet recording apparatus utilizing mechanical energy, a nozzle forming substrate having a plurality of nozzles, and a pressure generating element made of a piezoelectric material and a conductive material disposed opposite to the nozzles are used. An on-demand ink jet recording apparatus that includes ink filling around the pressure generating element, displaces the pressure generating element by an applied voltage, and discharges a small droplet of ink from a nozzle can be given. FIG. 7 shows an example of a configuration of a recording head which is a main part of the recording apparatus.

The head includes an ink passage 80 communicating with an ink chamber (not shown), an orifice plate 81 for discharging ink droplets of a desired volume, a vibration plate 82 for directly applying pressure to ink, and a A piezoelectric element 83 joined to the vibration plate 82 and displaced by an electric signal; and a substrate 84 for supporting and fixing the orifice plate 81, the vibration plate 82 and the like.
It is composed of

In FIG. 7, an ink flow path 80 is formed of a photosensitive resin or the like, and an orifice plate 81 is formed with a discharge port 85 by punching a metal such as stainless steel or nickel by electroforming or pressing. The plate 82 is formed of a metal film such as stainless steel, nickel, titanium or the like and a high elastic resin film, and the piezoelectric element 83 is formed of a dielectric material such as barium titanate or PZT. In the recording head having the above-described configuration, a pulse-like voltage is applied to the piezoelectric element 83 to generate a strain stress, the energy of which causes the diaphragm bonded to the piezoelectric element 83 to be deformed, and the ink flow path 8
The operation is performed such that printing is performed by vertically pressurizing the ink in 0 and discharging ink droplets (not shown) from the discharge ports 85 of the orifice plate 81. Such a recording head is used by being incorporated in an ink jet recording apparatus similar to that shown in FIG. The detailed operation of the inkjet recording device
It can be performed in the same manner as described above.

[0047]

Next, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the following description, “parts” and “%” are based on weight unless otherwise specified.

Example 1 (Preparation of Pigment Dispersion 1) Commercially available acidic carbon black P
EERLESS MK II (manufactured by Columbian Co., Ltd.) was subjected to a general zinc hypoacid treatment, and the obtained pigment particles were sufficiently washed with water. This pigment wet cake was redispersed in water and desalted with a reverse osmosis membrane until the electric conductivity was 0.2 μs. Further, this pigment dispersion is concentrated to a pigment concentration of 10% by weight and subjected to an acid treatment, whereby a pigment dispersion 1 in which an anionic self-dispersion type carbon black having -COONa groups bonded to the surface of carbon black is dispersed. I got The average particle size A of the self-dispersible carbon black obtained as described above is 26.
nm. The blackness index B was measured by the above-mentioned method and found to be 160. When the value of B / A was calculated from these values, it was 6.15.

(Preparation of Ink 1) The following components were mixed,
After being sufficiently stirred and dissolved, the resultant was subjected to pressure filtration with a micro filter having a pore size of 3.0 μm (manufactured by Fuji Photo Film) to prepare Ink 1. -30 parts of pigment dispersion liquid-6 parts of trimethylolpropane-6 parts of glycerin-6 parts of diethylene glycol-4 parts of isopropyl alcohol-48 parts of water

Example 2 (Preparation of Pigment Dispersion Liquid 2) Commercially available acidic carbon black R
AVEN 11 (manufactured by Columbian Co., Ltd.) was subjected to a general zinc hypoacid treatment, and the obtained pigment particles were sufficiently washed with water.
This pigment wet cake is redispersed in water, and has an electric conductivity of 0.2.
It was desalted with a reverse osmosis membrane until μs. Further, this pigment dispersion is concentrated to a pigment concentration of 10% by weight and subjected to an acid treatment, whereby
Pigment Dispersion Liquid 2 in which anionic self-dispersible carbon black in which a -COONa group was bonded to the surface of carbon black was dispersed was obtained. The average particle diameter A of the self-dispersion type carbon black obtained as described above was 25 nm. The blackness index B was measured by the above-mentioned method and found to be 160. When the value of B / A was calculated from these values, it was 6.4.

(Preparation of Ink 2) The following components were mixed,
After sufficiently stirring to dissolve, ink 2 was prepared by pressure filtration with a micro filter (manufactured by Fuji Photo Film) having a pore size of 3.0 μm.・ 30 parts of pigment dispersion liquid ・ 5 parts of trimethylolpropane ・ 3 parts of isopropyl alcohol ・ 6 parts of glycerin ・ 6 parts of thiodiglycol ・ 50 parts of water

Comparative Example 1 (Preparation of Pigment Dispersion 3) Commercially available acidic carbon black S
TATEX (manufactured by Columbian Co., Ltd.) was subjected to a general zinc hypoacid treatment, and the obtained pigment particles were sufficiently washed with water. This pigment wet cake is redispersed in water, and the conductivity is 0.2 μs.
It was desalted with a reverse osmosis membrane until. Further, this pigment dispersion is concentrated to a pigment concentration of 10% by weight and subjected to an acid treatment, whereby a pigment dispersion 3 in which an anionic self-dispersible carbon black having a -COONa group bonded to the surface of carbon black is dispersed. I got The average particle diameter A of the self-dispersion type carbon black obtained as described above was 54 nm.
The blackness index B was measured by the above-mentioned method, and was found to be 95. When the value of B / A was calculated from these values, it was 1.76.

(Preparation of Ink 3) The following components were mixed,
After sufficiently stirring and dissolving, Ink 3 was prepared by filtration under pressure with a micro filter having a pore size of 3.0 μm (manufactured by Fuji Photo Film). -30 parts of pigment dispersion 3-6 parts of trimethylolpropane-6 parts of glycerin-6 parts of diethylene glycol-4 parts of isopropyl alcohol-48 parts of water

Comparative Example 2 (Preparation of Pigment Dispersion Liquid 4) Commercially available acidic carbon black S
TATEX F-12 (manufactured by Degussa Co., Ltd.) was subjected to a general zinc hypoacid treatment, and the obtained pigment particles were sufficiently washed with water.
This pigment wet cake is redispersed in water, and has an electric conductivity of 0.2.
It was desalted with a reverse osmosis membrane until μs. Further, this pigment dispersion is concentrated to a pigment concentration of 10% by weight and subjected to an acid treatment, whereby
Pigment dispersion liquid 4 in which anionic self-dispersion type carbon black having -COONa groups bonded to the surface of carbon black was dispersed was obtained. The average particle diameter A of the self-dispersion type carbon black obtained as described above was 29 nm. The blackness index B was measured by the method described above, and was found to be 130. When the value of B / A was calculated from these values, it was 4.48.

(Preparation of Ink 4) The following components were mixed,
After being sufficiently stirred and dissolved, the resultant was subjected to pressure filtration with a micro filter (manufactured by Fuji Photo Film) having a pore size of 3.0 μm to prepare Ink 4. -30 parts of pigment dispersion 4-5 parts of trimethylolpropane-3 parts of isopropyl alcohol-6 parts of glycerin-6 parts of thiodiglycol-50 parts of water

[0056]

[Table 1] Table 1

[Evaluation] The inks 1 to 4 obtained in Examples and Comparative Examples summarized in Table 1 above were filled in a BC-21 cartridge (manufactured by Canon), and heat energy corresponding to a recording signal was applied thereto. The following evaluation was performed using an ink jet recording apparatus BJC-4000 (manufactured by Canon) having an on-demand type multi-recording head for discharging ink by applying the ink to the ink. Table 2 shows the results.

(1) Density of Black Solid Image Solid images were printed on each of the above inks on 4024 PAPER (plain paper) manufactured by Xerox, and the density was visually evaluated. ：: Black solid image is sufficiently black △: Black solid image is slightly lighter ×: Black solid image is lighter

(2) Storage stability 100 ml of the ink was placed in a 100 ml glass bottle manufactured by Schott Co., Ltd., and allowed to stand in a thermostat at 60 ° C. for one month, and the state of the ink was visually evaluated. B
The cartridge was filled in a C-21 cartridge, printed using BJC-4000, and the density of the image was visually evaluated. ：: No deposits on the bottom of the bottle.
There is no particular difference in the value. Δ: There is no deposit on the bottom of the bottle.
The D. value is different. X: There is a deposit on the bottom of the bottle, or when printed, the OD value is significantly different from that before storage.

[0060]

[Table 2] Table 2: Evaluation results (Examples and Comparative Examples)

[0061]

According to the present invention, when used in ink-jet recording, the ink has high print density, good print quality, and complete water resistance and complete light fastness, even though it is an ink using carbon black as a coloring material. A water-based pigment ink that can provide excellent images, has excellent storage stability of the ink, and can perform stable ejection without clogging, and provides an inkjet recording method and an inkjet recording apparatus using the ink. Is done.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view illustrating an example of a head of an inkjet recording apparatus.

FIG. 2 is a cross-sectional view illustrating an example of a head of the inkjet recording apparatus.

FIG. 3 is an external perspective view of a head obtained by multiplying the head shown in FIG. 1;

FIG. 4 is a schematic perspective view illustrating an example of an ink jet recording apparatus.

FIG. 5 is a longitudinal sectional view illustrating an example of an ink cartridge.

FIG. 6 is a perspective view illustrating an example of a recording unit.

FIG. 7 is a schematic cross-sectional view illustrating another configuration example of the inkjet recording head.

[Explanation of symbols]

 13: Head 14: Ink groove 15: Heating head 16: Protective film 17-1, 17-2: Electrode 18: Heating resistor layer 19: Heat storage layer 20: Substrate 21: Ink 22: Discharge orifice (fine hole) 23: Meniscus 24: Ink droplet 25: Recording material 26: Multi-groove 27: Glass plate 28: Heating head 40: Ink bag 42: Plug 44: Ink absorber 45: Ink cartridge 51: Paper supply unit 52: Paper feed roller 53: Discharge roller 61: Blade 62: Cap 63: Ink absorber 64: Discharge recovery unit 65: Recording head 66: Carriage 67: Guide shaft 68: Motor 69: Belt 70: Recording unit 71: Head unit 72: Atmospheric communication port 80 : Ink flow path 81: orifice plate 82: diaphragm 83: piezoelectric element 84: substrate 85: discharge port

Continuing on the front page (72) Inventor Nofumi Hattori 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Takashi Katsuragi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. Inside

Claims (17)

[Claims] 1. A color material comprising at least a color material, a water-soluble organic solvent dispersing the color material, and water, wherein at least one hydrophilic group is bonded to the surface of the carbon black as a color material directly or via another atomic group. In an aqueous pigment ink containing a self-dispersible carbon black, when the average particle diameter of the self-dispersible carbon black is A (nm) and the blackness index is B,
And B are self-dispersible carbon blacks satisfying the following two formulas. A ≧ 20 B / A ≧ 5.0 (The blackness index in the above formula is a value measured by a nigrometer.) 2. A color material comprising at least a color material, a water-soluble organic solvent dispersing the color material and water, wherein at least one kind of hydrophilic group is bonded to the surface of the carbon black as a color material directly or via another atomic group. In an aqueous pigment ink containing a self-dispersible carbon black, when the average particle diameter of the self-dispersible carbon black is A (nm) and the blackness index is B,
And B are self-dispersible carbon blacks satisfying the following two formulas. A ≧ 20 B / A ≧ 10.0 (The blackness index in the above formula is a value measured by a nigrometer.) 3. The hydrophilic group is at least one selected from the following hydrophilic groups, and the other atomic group may have an alkyl group having 1 to 12 carbon atoms or a substituent. The aqueous pigment ink according to claim 1, wherein the aqueous pigment ink is a phenyl group or a naphthyl group which may have a substituent. Embedded image (However, M in the formula represents a hydrogen atom, an alkali metal, ammonium or organic ammonium, and R represents an alkyl group having 1 to 12 carbon atoms, a phenyl group which may have a substituent or a substituent. Represents a naphthyl group which may be substituted.) 4. The aqueous pigment ink according to claim 1, wherein the hydrophilic group is a basic group. 5. An ink jet recording method for recording on a recording material by discharging ink from an orifice according to a recording signal, wherein the ink is the ink according to claim 1. Characteristic ink jet recording method. 6. The ink jet recording method according to claim 5, wherein the ink is ejected by applying thermal energy to the ink. 7. A recording unit comprising an ink containing section containing ink and a head section for ejecting the ink, wherein the ink is the ink according to any one of claims 1 to 4. The recording unit to do. 8. The recording unit according to claim 7, wherein the head section is a head that ejects the ink by applying thermal energy to the ink. 9. The recording unit according to claim 7, wherein the ink container is formed of polyurethane, cellulose, polyvinyl acetate, or polyolefin resin. 10. An ink cartridge provided with an ink storage section for storing ink, wherein the ink is provided.
An ink cartridge comprising the ink according to claim 4. 11. The ink cartridge according to claim 10, wherein the ink container has a liquid contact surface made of polyolefin. 12. An ink jet recording apparatus comprising a recording unit having an ink storage section for storing ink and a head section for discharging the ink, wherein the ink according to any one of claims 1 to 4. An ink jet recording apparatus, which is an ink. 13. The ink jet recording apparatus according to claim 12, wherein the head section is a head that ejects the ink by applying thermal energy to the ink. 14. The ink jet recording apparatus according to claim 12, wherein the ink containing section is formed of polyurethane, cellulose, polyvinyl acetate or polyolefin resin. 15. A recording head for discharging ink,
5. An ink jet recording apparatus comprising: an ink cartridge having an ink containing section containing ink; and an ink supply section for supplying ink from the ink cartridge to a recording head, wherein the ink is any one of claims 1 to 4. An ink jet recording apparatus comprising the ink described in the above. 16. The recording head according to claim 1, wherein the recording head is a head that ejects the ink by applying thermal energy to the ink.
6. The ink jet recording apparatus according to 5. 17. The ink jet recording apparatus according to claim 15, wherein the ink containing section has a liquid contact surface formed of polyolefin.