JP2001089688A - Ink, method for improving intermittent jetting properties of ink jet recording apparatus, image recording method, recording unit, ink cartridge, ink set and image recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink comprising as a coloring material a self-dispersible carbon black and excellent in ink jet recording characteristics. SOLUTION: The subject ink comprises a coloring material comprising at least a self-dispersible carbon black composed of a carbon black having at least one hydrophilic group bonded on the surface thereof directly or via another atomic group and an aqueous medium, and has a Ka value, measured by the Bristow method, of less than 1.5 and a total monovalent cation content of 0.05-1 mol/l.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink, a method for improving intermittent ejection of an ink jet recording apparatus, an ink jet recording method, an ink cartridge, a recording unit, an ink set, and an image recording apparatus.

[0002]

2. Description of the Related Art Conventionally, inks for writing implements (fountain pens, felt-tip pens, water-based ball-point pens, etc.) and ink-jet inks using carbon black, which has a high density of printed matter and excellent robustness, as a black colorant for printing inks, It has been reported in various compositions. In particular, copy paper, report paper, notebooks,
Detailed research and development on the composition and properties of carbon black itself, and the composition and properties of inks containing it, so that good recording can be performed on plain paper such as stationery, bond paper, and continuous slip paper. Has been done.

For example, JP-A-3-210373 discloses an ink using acidic carbon black and an alkali-soluble polymer. Also, JP-A-3-134
No. 073 describes an inkjet ink in which a dispersion having excellent storage stability and excellent ejection properties in a bubble jet recording apparatus can be easily obtained. Also, JP-A-8-34
No. 98 presents a technical problem that ink containing carbon black together with a dispersant becomes unstable as an inkjet ink, or a sufficient print density cannot be obtained, and as an ink that can solve it, An ink using self-dispersible carbon black that can be dispersed in a solvent without using a dispersant is disclosed. International Publication Number 96 /
18695 (Tokuheihei 10-510862) and USP57
No. 46818 (Japanese Patent Application Laid-Open No. 10-95941) also discloses an ink-jet ink containing a self-dispersion type carbon black, and describes that a high-quality image can be obtained.

By the way, regarding the conventional pigment ink,
It is known that the ejection stability may be unstable. Specifically, for example, after the ink is ejected from a predetermined nozzle of the inkjet recording head, the ejection of the ink from the nozzle is stopped for a predetermined time (for example, about 20 seconds), and then the ink is again ejected from the nozzle. Sometimes, re-ejection of ink is not performed stably and printing is disturbed (hereinafter, ink is ejected from a predetermined nozzle, and after the ejection from the nozzle is stopped for a predetermined time, the The operation of re-discharging the ink from is referred to as “intermittent discharge of ink”, and the fact that re-discharge of the ink is unstable is referred to as “poor intermittent discharge”.

When multicolor printing is performed using black ink together with ink of another color (for example, at least one selected from magenta, cyan, yellow, red, green and blue), a black image is printed on a recording medium. At the boundary between the portion and the color image portion, the color may bleed or the ink may be mixed unevenly, and the image quality may deteriorate (hereinafter, "bleeding") may be observed. Regarding such bleeding, there is an idea of improving the permeability of the ink into the recording medium by adding a so-called surfactant (for example, Japanese Patent Application Laid-Open No. 55-65269) or an idea of using a volatile solvent as the ink solvent (for example, JP 55
No. 66976) has been proposed. In particular, black ink frequently used for printing characters and the like has a higher optical density (OD).
For example, in the method of suppressing bleeding by increasing the permeability to the recording medium, a high optical density and the sharpness of the edge of the image are compatible at a high level. I know that it is difficult.

As described above, with respect to black ink for ink jet, the characteristics required in recent years with ultra-high image quality of ink jet recorded images are becoming extremely sophisticated. However, with respect to the pigment ink containing the self-dispersion type carbon black as a coloring material, there is technical knowledge for suppressing bleeding, giving high OD and sharp edges, and achieving inkjet discharge characteristics such as intermittent discharge properties. It cannot be said that the ink is sufficiently accumulated, and there is a part where the behavior as the ink for ink jet recording is not clear.

[0007]

In view of such technical background, the present inventors have repeatedly studied inks using self-dispersion type carbon black, and as a result, have adjusted the permeability to a relatively low level on plain paper. When the amount of the monovalent cation ion in the ink containing the self-dispersible carbon black is within a predetermined range, the intermittent ejection property of the ink is improved, and the fixing property and the image quality are satisfied by the ink. It has been found that the present invention can be obtained, and the present invention has been accomplished.

Accordingly, an object of the present invention is to provide an ink containing a self-dispersion type carbon black as a coloring material and having excellent ink jet recording characteristics.

Another object of the present invention is to provide a method for improving the intermittent ejection property of an ink jet.

Another object of the present invention is to provide an ink set capable of stably obtaining an image with less bleeding.

In the present invention, bleeding is reduced.
It is an object of the present invention to provide an image recording method, an image recording apparatus, an ink cartridge, and a recording unit that can stably obtain a high-quality printed matter having excellent fixability.

[0012]

An ink capable of achieving the above object is a self-dispersing ink in which at least one hydrophilic group is bonded directly or via another atomic group to the surface of carbon black. A color material containing at least carbon black, and an aqueous medium, and the Ka value determined by the Bristow method is less than 1.5,
The total amount of monovalent cation ions is 0.05 to 1 mol / l.

A method of improving the intermittent ejection property of an ink jet recording apparatus which can achieve the above object is a means for applying energy to ink in an ink flow path of an ink jet recording head and discharging the ink from an orifice. A method for improving the intermittent ejection property of an ink jet recording apparatus comprising: a self-dispersible carbon black and an aqueous medium, wherein the Ka value obtained by the Bristow method is less than 1.5, and a monovalent cation An ink having a total amount of ions of 0.05 to 1 mol / l is located in the ink flow path.

An image recording method capable of achieving the above object is a method for recording an image, comprising the steps of applying energy to ink, ejecting the ink from a recording head, and attaching the ink to a recording medium. For example, on the surface of carbon black, a coloring material containing at least one self-dispersible carbon black in which at least one hydrophilic group is bonded directly or via another atomic group, and an aqueous medium, and are obtained by the Bristow method Ka value is 1.
5 or less, and the total amount of monovalent cation ions is 0.05 to 1 mol / l.

In an ink cartridge capable of achieving the above object, there is provided an ink cartridge provided with a tank accommodating portion for accommodating the ink, wherein the ink is directly attached to, for example, a surface of carbon black by at least one hydrophilic group. Or a coloring material containing at least a self-dispersible carbon black bonded via another atomic group, and an aqueous medium, and the Ka determined by the Bristow method
The ink has a value of less than 1.5 and the total amount of monovalent cation ions is 0.05 to 1 mol / l.

A recording unit capable of achieving the above object is a recording unit having an ink containing section containing ink and a head section for ejecting the ink as ink droplets. On the surface of the at least one hydrophilic group is directly or via another atomic group at least a self-dispersible carbon black colorant containing, and an aqueous medium,
And the Ka value determined by the Bristow method is less than 1.5, and the total amount of monovalent cation ions is 0.05
-1 mol / l.

According to another aspect of the present invention, there is provided an image recording apparatus including a recording unit having an ink storing section for storing ink and a head for discharging the ink as ink droplets by the action of thermal energy. In an ink jet recording apparatus comprising: a color material containing at least a self-dispersion type carbon black in which the ink is, for example, on the surface of carbon black, at least one hydrophilic group is bonded directly or via another atomic group, and The ink contains an aqueous medium, has a Ka value determined by the Bristow method of less than 1.5, and has a total amount of monovalent cation ions of 0.05 to 1 mol / l.

According to another aspect of the present invention, there is provided an image recording apparatus comprising: an ink cartridge having a tank accommodating ink; and a recording head for ejecting the ink as ink droplets by the action of thermal energy. In an ink jet recording apparatus comprising: a color material containing at least a self-dispersion type carbon black in which the ink is, for example, on the surface of carbon black, at least one hydrophilic group is bonded directly or via another atomic group, and The ink contains an aqueous medium, has a Ka value determined by the Bristow method of less than 1.5, and has a total amount of monovalent cation ions of 0.05 to 1 mol / l.

Further, the ink set that can achieve the above-mentioned object includes an ink containing at least one color material selected from cyan, magenta, yellow, red, green and blue color materials and, for example, carbon ink. On the surface of the black, a colorant and an aqueous medium including at least one self-dispersible carbon black in which at least one hydrophilic group is bonded directly or via another atomic group,
And the Ka value determined by the Bristow method is less than 1.5, and the total amount of monovalent cation ions is 0.05
１1 mol / l of an ink.

[0020]

Next, the present invention will be described in more detail with reference to preferred embodiments.

One embodiment of the ink according to the present invention contains a self-dispersible carbon black and an aqueous medium, has a Ka value according to the Bristow method of less than 1.5, and has a total amount of monovalent cation ions of 0.05 to 0.05. 1 mol / l ink. Hereinafter, constituent materials of the ink will be described.

(Self-dispersion type carbon black) The self-dispersion type carbon black is a carbon black in which at least one hydrophilic group is bonded to the carbon black surface directly or via another atomic group. As a result of introducing the hydrophilic group onto the surface of the carbon black, a dispersant for dispersing the carbon black, unlike the conventional ink, becomes unnecessary. As self-dispersed carbon black,
Those having ionicity are preferred.

(Cationic CB) Examples of the cationically charged carbon black include those in which at least one selected from the following quaternary ammonium groups is bonded to the surface of carbon black.

[0024]

[Outside 1] In the above formula, R represents an alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted phenyl group, or a substituted or unsubstituted naphthyl group.

It should be noted, for example, NO ₃ as a counter ion to the cationic group of the ^- or CH ₃ COO ^-, etc. are present.

As a method for producing a cationically charged self-dispersible carbon black having a hydrophilic group bonded thereto as described above, for example, a method of bonding an N-ethylpyridyl group having the following structure is exemplified. To illustrate with an example:

[0027]

[Outside 2]

There is a method of treating carbon black with 3-amino-N-ethylpyridium bromide. Since carbon black charged anionic or cationic by the introduction of a hydrophilic group on the surface of carbon black in this way has excellent water dispersibility due to repulsion of ions, even when contained in an aqueous ink, A stable dispersion state is maintained without adding a dispersant or the like.

(Anionic carbon black) Anion
Carbon black that has been charged
A hydrophilic group such as shown below is bonded to the surface of the
One that has been used. −COOM, −SO_ThreeM , -PO_ThreeHM, -PO_ThreeM_Two In the above formula, M is a hydrogen atom, an alkali metal, ammonium
Or organic ammonium, of which -CO
OM or -SO_ThreeM binds to the carbon black surface to form an anion
Carbon black charged to water is dispersible in ink
Is particularly suitable for this embodiment because
You. By the way, those represented as M in the above hydrophilic groups
That is, as specific examples of the alkali metal, for example, Li, Na,
K, Rb, Cs, etc .;
Specific examples of methylammonium, dimethyl
Ammonium, trimethyl ammonium, ethyl ammonium
, Diethylammonium, triethylammonium
, Methanol ammonium, dimethanol ammonium
And trimethanol ammonium. Soshi
With M as ammonium or organic ammonium
The ink of the present embodiment including the dispersion type carbon black,
The water resistance of the recorded image can be further improved.
Can be particularly preferably used. This
When the ink is applied on a recording medium, the
The decomposition of ammonia and the evaporation of ammonia
Conceivable. Here, self-dispersion type with M as ammonium
Carbon black is, for example, self-contained when M is an alkali metal.
Using self-dispersion type carbon black, M
After replacing with ammonium or adding an acid to make it H-type
To ammonium by adding ammonium hydroxide to
Method.

As a method for producing a self-dispersible carbon black charged anionic, for example, there is a method of oxidizing carbon black with sodium hypochlorite.
Groups can be chemically linked.

By the way, various hydrophilic groups as described above are
It may be directly bonded to the surface of carbon black. Alternatively, another atomic group may be interposed between the carbon black surface and the hydrophilic group, and the hydrophilic group may be indirectly bonded to the carbon black surface. Here, specific examples of the other atomic groups include a linear or branched alkylene group having 1 to 12 carbon atoms, a substituted or unsubstituted phenylene group, and a substituted or unsubstituted naphthylene group.
Here, examples of the substituent of the phenylene group and the naphthylene group include a linear or branched alkyl group having 1 to 6 carbon atoms. As specific examples of the combination of another atomic group and the hydrophilic group, for example, _{-C 2 H 4 -COOM, -Ph-} SO 3 M, -P
h-COOM and the like (provided that Ph represents a phenyl group).

Further, in the present invention, the self-dispersion type carbon black to be contained in the ink is not limited to one type, and the color tone may be prepared by mixing 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 10% by weight, based on the total weight of the ink. Further, the color tone of the ink may be adjusted by using a dye in addition to the self-dispersible carbon black.

(Monovalent Cation Ion) The total amount of monovalent cation ions in the ink according to the present embodiment is 0.05 to 1 mol / l, particularly 0.1 to 0.5 mol / l, based on the total amount of the aqueous pigment ink.
The range of 1 is preferred. That is, when the total amount of monovalent cation ions is within this range, the intermittent ejection property is remarkably improved, and there is no problem in the properties as ink, such as storage stability.

Here, the total amount of monovalent cation ions is
It refers to the amount of all monovalent cation ions contained in the ink. That is, for example, a counter ion of the surface functional group of the self-dispersible carbon black, a cation ion added as a pH adjuster, a cation ion added in the form of a salt, and the like are present as cations in the ink and detected as cations. It means the amount of all possible cationic ions. Here, as a method for measuring the total amount of cations in the ink, for example, a combination of quantification of metal ions by a plasma emission spectrometer and quantification of cations such as ammonium ions by ion chromatography can be mentioned.

Examples of the monovalent cation include, for example, alkali metal ions, ammonium ions, and organic ammonium ions. More specifically, examples of the alkali metal ion include a lithium ion, a sodium ion, and a potassium ion. Examples of the organic ammonium ion include a mono to tetra ammonium ion, a mono to tetra ethyl ammonium ion, a mono to tetra methanol ammonium ion, and the like.

Although the detailed reason why the ink of the present invention exhibits the above-mentioned properties is unknown, the ink of the present invention is capable of discharging the ink from a certain nozzle because the specific cation ion is contained at 0.05 to 1 mol / l. When the ink is not ejected from the nozzle for a certain period of time after the ejection, a thin film of carbon black and cation ions is formed at the nozzle portion, and further evaporation of the ink from the nozzle portion is suppressed. It is considered that the change of the physical properties of the ink can be minimized.

In the present invention, it is particularly effective to include a water-soluble organic solvent or a humectant described later in the ink. By including a water-soluble organic solvent or a humectant in the ink, the intermittent ejection property of the ink can be improved. The effect of improving the intermittent ejection property by using the solvent and the humectant was exceeded. It is not clear why these results are obtained,
It is considered that the effect of the regulation of the total amount of monovalent cation ions according to the present invention and the effect of using a water-soluble organic solvent or humectant act synergistically.

In order to adjust the total amount of cation ions in the ink, for example, a method of adding the above-mentioned cation in the form of a salt can be used. Then, in the combination of a cation ion when adding a cation ion in the form of a salt and an anion ion serving as a counter thereof, one selected from ammonium ions, sodium ions, lithium ions, and the like as the cation ion, particularly an ammonium ion, and A salt with one selected from a halogen ion (chlorine ion, etc.), an acetate ion, a benzoate ion, or the like as an anion ion is excellent in compatibility with self-dispersible carbon black, or an ink excellent in intermittent ejection property. Is to give.

(Regarding the Ka Value) As a measure of the permeability of the ink into the recording medium, there is a Ka value obtained by the Bristow method. That is, when the ink permeability is represented by the ink amount V per m ² , the ink penetration amount V (ml / m ² = μm) into the recording medium after a predetermined time t has elapsed since the ink droplet was ejected. Is represented by Bristow's equation shown below.

V = Vr + Ka (t-tw) ^1/2 Here, immediately after the ink droplets adhere to the surface of the recording medium, the ink is absorbed in the uneven portions on the surface of the recording medium (the roughness of the surface of the recording medium). In most cases, it hardly penetrates into the recording medium. The time during that time is the contact time (tw), and the amount of ink absorbed by the uneven portions of the recording medium during the contact time is Vr. If the contact time exceeds the contact time after the ink is attached, the amount of permeation into the recording medium increases by the time exceeding the contact time, that is, by an amount proportional to a half power of (t-tw). Ka is a proportional coefficient of this increase, and shows a value corresponding to the permeation rate. The Ka value can be measured using a liquid dynamic permeability tester (for example, trade name: Dynamic Permeability Tester S; manufactured by Toyo Seiki Seisakusho, etc.) by the Bristow method. In the ink according to each of the embodiments of the present invention described above, it is preferable that the Ka value is less than 1.5 in order to further improve the quality of the recorded image, and more preferably 0.2 to less than 1.5. is there. That is, when the Ka value is less than 1.5, solid-liquid separation occurs at an early stage in the process of penetrating the ink into the recording medium, and a high-quality image with very little feathering can be formed. The Ka value according to the Bristow method in the present invention is determined by the PB used for plain paper (for example, a copier or page printer (laser beam printer) using an electrophotographic system or a printer using an ink jet recording system manufactured by Canon Inc.). Paper or PPC paper, which is a paper for copying machines using the electrophotographic method)
Is a value measured using as a recording medium. The measurement environment is a normal office environment, for example, a temperature of 20 to 25.
C and a humidity of 40 to 60% are assumed. The dimension of the Ka value is represented by [ml · m ⁻² · msec ^-1/2 ].

(Aqueous Medium) A preferable aqueous medium capable of supporting the above-mentioned properties in the ink according to each of the above embodiments is a mixed solvent of water and a water-soluble organic solvent. As the solvent, those having an effect of preventing drying of the ink are particularly preferable, and it is preferable to use deionized water instead of general water containing various ions.

(Water-soluble organic solvent) Examples of the water-soluble organic solvent used in the present invention include, for example, methyl alcohol, ethyl alcohol, n-propyl alcohol,
Isopropyl alcohol, n-butyl alcohol, sec-
Carbon number of butyl alcohol, tert-butyl alcohol, etc.
1-4 alkyl alcohols; dimethylformamide,
Amides such as dimethylacetamide; ketones or keto alcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; ethylene glycol, propylene glycol, butylene glycol, tri Alkylene glycols having an alkylene group containing 2 to 6 carbon atoms, such as ethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol; lower alkyls, such as polyethylene glycol monomethyl ether acetate Ether acetate; glycerin; ethylene glycol monomethyl (or ethyl) ether, diethylene glycol methyl (or ethyl) ether, triethyl Lower alkyl ethers of polyhydric alcohols such as lenglycol monomethyl (or ethyl) ether; polyhydric alcohols such as trimethylolpropane and trimethylolethane; N-methyl-2-pyrrolidone, 2-pyrrolidone and 1,3-dimethyl- 2-imidazolidinone and acetylene alcohol. The water-soluble organic solvents as described above can be used alone or as a mixture.

The content of the above-mentioned 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 particular, when the Ka value is less than 1.5 as described above, a permeable solvent, for example, a surfactant such as an ethylene oxide adduct of acetylene glycol represented by the following chemical formula or a suitable permeable solvent. It is effective to add a predetermined amount.

[0045]

[Outside 3]

In addition to the above components, the aqueous pigment ink of the present invention may contain a surfactant, an antifoaming agent, a preservative, a fungicide, etc. in order to obtain an ink having desired physical properties as required. And a commercially available water-soluble dye or the like can also be added.

As described above, the ink of the present invention is particularly effective when used in ink jet recording. Ink jet recording methods include the use of mechanical energy in ink.
And the recording method in which thermal energy is applied to the ink to eject droplets by bubbling of the ink. The ink of the present invention is particularly suitable for those recording methods.

(Inkjet Recording Apparatus, Inkjet Recording Method) FIGS. 1 and 2 show examples of the structure of a head which is a main part of an apparatus utilizing heat energy as an inkjet recording apparatus.

FIG. 1 is a sectional view of the head 13 along the ink flow path, and FIG. 2 is a sectional view taken along the line AB in FIG. The head 13 is obtained by bonding a heating element substrate 15 to a glass, ceramic, silicon or plastic plate having a flow path (nozzle) 14 through which ink passes. The heating element substrate 15 includes a protective layer 16 formed of silicon oxide, silicon nitride, silicon carbide, or the like, and electrodes 17-1, 17-2, HfB2, TaN, TaAl, or the like formed of aluminum, gold, an aluminum-copper alloy, or the like. Heat generating resistor layer 18 formed of a high melting point material, heat storage layer 19 formed of thermally oxidized silicon, aluminum oxide, etc., and substrate 20 formed of a material having good heat dissipation properties such as silicon, aluminum, aluminum nitride, etc. It is made up.

When a pulse-like electric signal is applied to the electrodes 17-1 and 17-2 of the head, the area indicated by n on the heating element substrate 15 rapidly generates heat, and the ink in contact with the surface of the heating element substrate 15 Bubbles are generated, the meniscus 23 protrudes due to the generated pressure, and the ink is ejected through the nozzles 14 of the head, becomes ink droplets 24 from the ejection orifices 22, and flies toward the recording material 25.

FIG. 3 is an external view of a multi-head in which many heads shown in FIG. 1 are arranged. This multi-head is formed by bonding a glass plate 27 having a multi-nozzle 26 and a heating head 28 similar to that described in 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 to form a cantilever. The blade 61 is arranged at a position adjacent to the recording area of the recording head 65, and in this embodiment, is held in a form protruding into the movement path of the recording head 65.

Numeral 62 is a cap on the protruding opening surface of the recording head 65, which is disposed at a home position adjacent to the blade 61, and moves in a direction perpendicular to the moving direction of the recording head 65.
A configuration is provided in which the capping is performed in contact with the ink ejection port surface. Further, reference numeral 63 denotes an ink absorber provided adjacent to the blade 61. Like the blade 61, the ink absorber is held in a form protruding into the movement path of the recording head 65. Blade 6 above
1, the ejection recovery unit 6 by the cap 62 and the ink absorber 63
The blade 4 and the ink absorber 63 remove water, dust, and the like from the discharge port surface.

Reference numeral 65 denotes a recording head which has discharge energy generating means and discharges ink on a recording material facing a discharge port surface provided with discharge ports to perform recording. This is a carriage for moving the recording head 65. The carriage 66 is slidably connected to a guide shaft 67, and a part of the carriage 66 is connected to a belt 69 driven by a motor 68 (not shown). This allows the carriage
66 can be moved along the guide shaft 67, and the recording head
The movement of the recording area and the area adjacent to the recording area according to 65 becomes possible. Reference numeral 51 denotes a paper feed unit for inserting a recording material, and reference numeral 52 denotes a paper feed roller driven by a motor (not shown).

With these arrangements, 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, but the blade 61 is moved in the moving path. It is protruding. As a result, the ejection openings of the recording head 65 are wiped. The cap 62 is the recording head
When capping is performed by contacting the ejection surface of the print head 65, the cap 62 moves so as to protrude into the movement 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 position as the position 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 not only at the end of printing or at the time of ejection recovery, but also at a predetermined interval while the printing head moves through the printing area for printing. The wiping is performed in accordance with the movement.

FIG. 5 is a diagram showing an example of an ink cartridge 45 containing ink supplied to a recording head via an ink supply member, for example, a tube. Here, reference numeral 40 denotes an ink storage unit that stores 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 the stopper 42, the ink in the ink bag 40 can be supplied to the head. 44 is 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 the one in which they are integrated as shown in FIG. Is also preferably used. In FIG. 6, reference numeral 70 denotes a recording unit, in which an ink storage unit storing ink, for example, an ink absorber is stored, and the ink in the ink absorber is transmitted from a head unit 71 having a plurality of orifices. It is configured to be ejected as ink droplets. It is preferable for the present invention to use polyurethane as the material of the ink absorber.

Further, a structure may be adopted in which the ink container is an ink bag in which a spring or the like is provided inside without using an ink absorber. Reference numeral 72 denotes 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. 4, and is detachable from the carriage 66.

Next, as an embodiment of an ink jet recording apparatus utilizing the second mechanical energy, a nozzle forming substrate having a plurality of nozzles, a pressure generating element made of a piezoelectric material and a conductive material disposed opposite to the nozzles And an on-demand ink jet recording head 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. FIG. 7 shows a configuration example of a recording head which is a main part of the recording apparatus.

The head includes an ink flow path 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 The pressure transmitting element 83 is joined to the diaphragm 82 and deformed by an electric signal, and includes a substrate 84 for pointing and fixing the orifice plate 81, the diaphragm, and the like.

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. Plate 82 is stainless steel,
Nickel, formed of a metal film such as titanium and a high elastic resin film, etc., the piezoelectric element 83 is a barium titanate,
It is formed of a dielectric material such as PZT.

In the recording head having the above structure, a pulse voltage is applied to the piezoelectric element 83 to generate a strain stress,
The energy deforms the diaphragm bonded to the piezoelectric element 83, presses the ink in the ink flow path 80 vertically, and discharges ink droplets (not shown) from the discharge ports 85 of the orifice plate to perform recording. Operate.

Such a recording head is used by being incorporated in a recording apparatus similar to that shown in FIG. The detailed operation of the recording apparatus may be performed in the same manner as described above.

(Ink Set) The ink according to the present embodiment constitutes a black ink. This ink is a color ink containing a color material for yellow, a color ink containing a color material for magenta, and a color ink containing a color material for cyan. Good when combined with at least one color ink selected from a color ink containing a color material, a color ink containing a red color material, a color ink containing a blue color material, and a color ink containing a green color material. It is possible to provide an ink set that can be used for forming a color image.

[0067]

The present invention will be described in more detail with reference to the following examples and comparative examples. However, the present invention is not limited to the following examples unless it exceeds the gist of the present invention. In the following description, parts and percentages are by weight unless otherwise specified.

(Preparation of Pigment Dispersion) To a solution of 5 g of concentrated hydrochloric acid in 5.3 g of water was added 1.58 g of anthranilic acid at 5 ° C. To this, always stir in an ice bath
With the temperature kept at 10 ° C. or lower, a solution obtained by adding 1.78 g of sodium nitrite to 8.7 g of water at 5 ° C. was added. In addition, 15
After stirring for 20 minutes, 20 g of carbon black having a surface area of 320 m ² / g and a DBP oil absorption of 120 ml / 100 g was added in a mixed state.
Thereafter, the mixture was further stirred for 15 minutes. The obtained slurry is applied to Toyo filter paper.
The mixture was filtered through No. 2 (manufactured by Advantis), the pigment particles were sufficiently washed with water, dried in an oven at 110 ° C., and water was added to the pigment to prepare an aqueous pigment solution having a pigment concentration of 10% by weight. -Ph on the surface of carbon black by the above method
-A pigment dispersion in which self-dispersion type carbon black into which a COONa group was introduced was dispersed was obtained.

Example 1 The following components were mixed and thoroughly stirred to dissolve.
The ink of the present invention was prepared by pressure filtration with a 3.0 μm micro filter (manufactured by Fuji Film). -50 parts of the above pigment dispersion-1 part of sodium chloride-6 parts of trimethylolpropane-6 parts of glycerin-6 parts of diethylene glycol-0.2 parts of acetylene glycol-ethylene oxide adduct (trade name: acetylenol EH)- 30.8 parts of water

The ink was used with a plasma emission spectrometer (ICP) (trade name: SPS4000; manufactured by Seiko Electronics Co., Ltd.) and ion chromatography (trade name: ion chromatograph DX-100; manufactured by Nippon Dionesque Co., Ltd.). The total amount of cations was measured to be 0.19 mol / l. Further, the Ka value by the Bristow method using a dynamic permeability tester (trade name: dynamic permeability tester S; manufactured by Toyo Seiki Seisakusho) is shown below, and the plain paper for copying A, B, C, When measured in D and E, the average value was 1.1.

A: PPC paper NS manufactured by Canon Inc.
KB: PPC paper manufactured by Canon Inc. NDK C: PPC paper manufactured by Xerox Co., Ltd. 4024 D: PPC paper manufactured by Fox River Co., Ltd. Prober bond E: PPC paper manufactured by Neuijidora Inc. for Canon

In the following, plain paper for copying A, B, C,
D and E all correspond to the copy plain papers A, B, C, D and E.

Example 2 The following components were mixed, sufficiently stirred and dissolved, and the pore size was adjusted.
The ink of the present invention was prepared by pressure filtration with a 3.0 μm micro filter (manufactured by Fuji Film).・ 45 parts of the above pigment dispersion ・ 5 parts of ammonium benzoate ・ 6 parts of trimethylolpropane ・ 0.15 part of acetylene glycol ethylene oxide adduct (trade name: acetylenol EH) ・ 5 parts of glycerin ・ 5 parts of ethylene glycol Parts / Water 33.85 parts

The total cation ion content of this ink was measured in the same manner as in Example 1.
l. In addition, Ka of this ink by the Bristow method
The values are the same as in the first embodiment, and the plain papers A, B,
When measured in C, D and E, the average value was 1.2
Met.

Comparative Example 1 The following components were mixed, thoroughly stirred and dissolved,
The ink of the present invention was prepared by pressure filtration with a 3.0 μm micro filter (manufactured by Fuji Film).・ 50 parts of the above pigment dispersion ・ 6 parts of trimethylolpropane ・ 0.15 part of acetylene glycol ethylene oxide adduct (trade name: acetylenol EH) ・ 5 parts of glycerin ・ 5 parts of ethylene glycol ・ 33.85 parts of water

The total cation ion content of this ink was measured in the same manner as in Example 1.
l. In addition, Ka of this ink by the Bristow method
The values are the same as in the first embodiment, and the plain papers A, B,
When measured in C, D and E, the average value was 0.6
Met.

Table 1 below summarizes the main characteristics of the black inks of Examples 1, 2 and Comparative Example 1.

[0078]

[Table 1]

An ink-jet recording apparatus BJF having an on-demand type multi-recording head for ejecting ink by applying thermal energy according to a recording signal to the ink using the inks of Examples 1 and 2 and Comparative Example 1. -600
The following evaluation was performed using (manufactured by Canon). The results are shown in Table 2.

1) Intermittent Ejectivity (1) The above inks were applied to the above ink jet recording apparatus
Leave in a 15 ° C / 10% constant temperature and humidity chamber for 1 hour, then
A printing cycle in which one dot was ejected from each nozzle, and 5 seconds later, and one dot was ejected from each nozzle, was repeated 10 times. The printing of each dot was evaluated according to the following criteria. a: No printing disturbance of all nozzles at all 10 printing cycles b: Almost no printing disturbance of all nozzles at all 10 printing cycles c: Problem in actual use with 10 printing cycles There is no level of print disturbance d; There is print disturbance in 10 print cycles

2) Printing Density Each of the above inks was printed on the plain paper for copying A, B, C, D, and E using the ink jet recording apparatus, and the printing density at that time was measured using a printing density measuring device manufactured by Macbeth. It was measured and evaluated according to the following criteria. a: average print density of plain paper A, B, C, D, E for copy is 1.4 or more b; average print density of plain paper A, B, C, D, E for copy is 1.3 or more and less than 1.4 c; Average print density of plain paper A, B, C, D, E for copy is less than 1.3

(3) Fixability Using the above inks and the ink jet recording apparatus, printing of alphanumeric characters was continuously performed on each of the copy sheets A, B, C, D and E. At that time, the degree of adhesion of the ink of the immediately preceding printed matter to the back surface of each sheet was visually observed and evaluated according to the following criteria. a: In each of the sheets, almost no stain due to the adhesion of the ink to the back surface is recognized. b: Some stains due to the adhesion of the ink to the back surface of each sheet are observed. c: In each sheet, stains due to the adhesion of the ink to the back surface are conspicuous.

[0083]

[Table 2]

[0084]

As described above, according to the present invention, it is possible to obtain an ink jet recorded matter having high density and good edge sharpness. In addition, a high-quality ink-jet recorded product can be stably formed.

[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]

 DESCRIPTION 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 (micro 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 feed 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 Vibrating plate 83 Piezoelectric element 84 Substrate 85 Discharge port

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 2C056 EA04 FA03 FA04 FA10 FC01 JB04 JC10 KC10 KC11 KC14 KC22 2H086 BA02 BA21 BA55 BA60 BA62 4J037 AA02 CB09 CB21 CB22 DD24 EE02 FF15 4J039 BA04 BC07 BC11 BC10 BC10 BC10 BC10 BC10 BC10 BC10 BC25 BC31 BC36 BC54 BC75 BC79 BE01 BE12 CA06 EA19 EA42 EA43 EA46 GA24

Claims (23)

[Claims] 1. The method according to claim 1, wherein the surface of the carbon black is at least
A coloring material containing at least one self-dispersible carbon black in which one hydrophilic group is bonded directly or via another atomic group, and an aqueous medium, and the Ka value obtained by the Bristow method is less than 1.5. An ink, wherein the total amount of monovalent cation ions is 0.05 to 1 mol / l. 2. The ink according to claim 1, wherein said hydrophilic group is selected from the following. _{-COOM, -SO 3 M, -PO 3} HM, -PO 3 M 2 ( where, M in the formulas represents a hydrogen atom, an alkali metal, ammonium or organic ammonium, R represents the number of carbon atoms 1
Represents an alkyl group, a phenyl group which may have a substituent or a naphthyl group which may have a substituent. ) 3. The ink according to claim 1, wherein the monovalent cation ion is at least one selected from an alkali metal ion, an ammonium ion, and an organic ammonium ion. 4. The ink according to claim 3, wherein the monovalent cation is an ammonium ion. 5. The method according to claim 1, wherein the monovalent cation ion is 0.1 to 0.5 mol.
2. The ink according to claim 1, comprising l / l. 6. The Ka value is 0.2 or more and less than 1.5.
Ink according to 1. 7. A method for improving the intermittent discharge property of an ink jet recording apparatus provided with means for applying energy to ink in an ink flow path of an ink jet recording head and discharging the ink from an orifice, comprising: Containing carbon black and an aqueous medium, and having a Ka value determined by the Bristow method of less than 1.5, and 1
A method for improving the intermittent ejection property of an ink jet recording apparatus, wherein an ink having a total amount of cations having a valence of 0.05 to 1 mol / l is located in the ink flow path. 8. The method according to claim 7, wherein the self-dispersible carbon black has at least one hydrophilic group bonded directly or via another atomic group to the surface of the carbon black. 9. The method according to claim 7, wherein said hydrophilic group is selected from the following. —COOM, —SO ₃ M, —PO ₃ HM, and —PO ₃ M ₂ (where M represents a hydrogen atom, an alkali metal, ammonium or organic ammonium) 10. The method according to claim 7, wherein the monovalent cation is at least one selected from an alkali metal ion, an ammonium ion and an organic ammonium ion. 11. The method according to claim 10, wherein the monovalent cation is an ammonium ion. 12. The method according to claim 12, wherein the monovalent cation ion is 0.1 to 0.5.
The improvement method according to claim 7, which contains mol / l. 13. The method according to claim 7, wherein the Ka value is 0.2 or more and less than 1.5. 14. An image recording method comprising the steps of applying energy to ink, ejecting the ink from a recording head, and attaching the ink to a recording medium.
7. An image recording method, comprising the ink according to any one of 1 to 6. 15. The image recording method according to claim 14, wherein the energy is heat energy. 16. The image recording method according to claim 14, wherein said energy is mechanical energy. 17. The recording medium according to claim 14, wherein the recording medium is plain paper.
The image recording method described in the above. 18. A recording unit comprising an ink containing section containing ink and a head section for discharging the ink as ink droplets, wherein the ink is the ink according to any one of claims 1 to 6. Recording unit characterized by the above-mentioned. 19. An ink cartridge provided with a tank accommodating portion for accommodating the ink, wherein the ink comprises a tank accommodating portion.
7. An ink cartridge, which is the ink according to any one of items 1 to 6. 20. An ink jet recording apparatus comprising: a recording unit having an ink containing section containing ink and a head section for ejecting the ink as ink droplets by the action of thermal energy. 1
7. An image recording apparatus, comprising: the ink according to any one of claims 1 to 6. 21. An ink jet recording apparatus comprising: an ink cartridge having a tank accommodating section for accommodating ink; and a recording head for ejecting the ink as ink droplets by the action of thermal energy. An image recording apparatus comprising the ink according to any one of 1 to 6. 22. The image recording apparatus according to claim 21, further comprising an ink supply unit for supplying the ink contained in the ink cartridge to the recording head. 23. For cyan, magenta, yellow,
An ink set comprising an ink containing at least one color material selected from red, green and blue color materials and the ink according to any one of claims 1 to 6.