JP2002201390A - Ink, ink-jet ink, image printing method, ink cartridge, ink tank, printing unit, ink set, sticking-mitigating method, image printer, printing head, and method for ameliorating intermittently issuing tendency - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink containing a pigment as the coloring material, particularly self-dispersible carbon black, and excellent in ink-jet printing characteristics. SOLUTION: This ink comprises an aqueous medium and a coloring material essentially comprising self-dispersible carbon black with at least one kind of hydrophilic group either directly or via another kind of atomic group bound to the surface thereof, and also contains >=0.6 mass%, based on the carbon black, of potassium ion.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD OF THE INVENTION

The present invention relates to an ink, an ink for ink jet, an ink jet recording method, an ink cartridge, an ink tank, a recording unit, an ink set, a method for alleviating sticking, an image recording apparatus, a recording head, and a method for improving intermittent ejection.

[Prior art]

Conventionally, writing instruments (fountain pens, felt-tip pens, water-based ball-point pens, etc.) using carbon black, which has a high density of printed matter and is excellent in fastness, etc., as a black colorant for printing inks
Inks and ink-jet inks have been reported in a wide variety of compositions. Above all, the composition of carbon black itself so that good recording can be performed on plain paper such as copy paper, report paper, notebooks, stationery, bond paper, and continuous slip paper that are commonly used in offices in recent years. Detailed research and development have been carried out on the properties and properties of inks containing the same, and on the properties and the like.

For example, JP-A-3-210373 discloses an aqueous ink jet ink containing acidic carbon black and an alkali-soluble polymer as a dispersant for carbon black. Also, Japanese Patent Application Laid-Open No. 3-134
No. 073 discloses a dispersion containing neutral or basic carbon black and a water-soluble resin as a dispersant thereof, which is excellent in storage stability and dischargeability in a bubble jet (registered trademark) recording device. Describes an ink-jet ink that can easily obtain the following.

Japanese Patent Application Laid-Open No. H8-3498 presents technical problems such as that ink containing carbon black together with a dispersant becomes unstable as an ink jet ink, and that sufficient print density cannot be obtained. Discloses an ink using self-dispersible carbon black which can be dispersed in a solvent without using a dispersant as an ink that can solve the problem. International Publication Number 96/18695 (Tokuheihei 10-510862)
And US Pat. No. 5,746,818 (JP-A-10-95941) also disclose ink jet inks containing self-dispersed carbon black, and describe that high-quality images can be obtained.

[0005] Further, the present inventors have disclosed European Patent Publication E
In P 943666, when the self-dispersion type carbon black is used as an inkjet ink, the self-dispersion type carbon black is used for the purpose of improving the image density depending on the type of paper, reducing the blur between black colors, and the like. In addition, a technical means for adding salt has been disclosed.

[0006] Incidentally, factors that determine the characteristics of ink-jet ink include intermittent ejection of ink and fixation of ink. Specifically, the intermittent ejection property of the ink is, 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 relatively long time (for example, about 12 hours), and then the ink is ejected again. When ink is re-discharged from the nozzle, re-discharge of ink may not be performed stably, and printing may be disturbed. In this way, the ink is ejected from the predetermined nozzle,
The operation of re-ejection of ink from the nozzle after the ejection from the nozzle is stopped for a predetermined time is called “intermittent ejection of ink”, and the instability of re-ejection of ink is called “poor intermittent ejection”. .

[0007] The ink sticking property means that after the ink is stopped for a long time (for example, several days or more), when the ink is again discharged from the nozzle, the viscosity increases or solidifies in the nozzle. In some cases, a recovery operation is required to remove the ink, and the state in which re-emission is not stable due to an increase in the viscosity of the ink in the nozzles or solidification is called "ink fixation", and recovery is performed to obtain stable re-ejection. The need for a large number of operations is called "poor sticking".

[0008] With respect to ink-jet inks, the characteristics required in recent years with ultra-high image quality of ink-jet recorded images are also becoming extremely sophisticated.

However, pigment inks containing the above-mentioned self-dispersion type carbon black as a coloring material, particularly black pigment inks, have high OD and sharp edges, and have poor intermittent ejection properties and sticking properties. It cannot be said that the technical knowledge for achieving the ink jet ejection characteristics is sufficiently accumulated, and there is a part where the behavior as the ink for ink jet recording is not clear.

For example, the ink containing the self-dispersion type carbon black and the salt by the present inventors described above is intended to reduce the dependence of the image density on the paper type and to bleed the boundary region of the black color image. Although it is extremely effective in reducing the amount of ink, as a result of further studies aimed at establishing a better ink jet recording technique by the present inventors, the intermittent ejection property and fixing property of the ink are large depending on the structure of the recording head used. There were occasional fluctuations.

It is expected that the structure of the recording head will be diversified with the widespread product development of the ink jet printer and the application field of the ink jet recording technology in the future. They have come to the perception that it is necessary to develop a technology for an ink that exhibits good and stable ink jet characteristics even with diversification of recording heads while making use of the characteristics.

Accordingly, an object of the present invention is to provide an ink which contains a pigment, particularly a self-dispersible carbon black, as a coloring material and has excellent ink jet recording characteristics.

Another object of the present invention is to provide an image recording method capable of stably forming a high quality ink jet recorded image.

Another object of the present invention is to provide an image recording apparatus capable of stably obtaining a high-quality printed matter, and an ink cartridge and a recording unit used therein.

Another object of the present invention is to provide a method for reducing the stickiness of an ink jet recording head.

Another object of the present invention is to provide a recording head which is hardly fixed.

Another object of the present invention is to provide an ink-jet ink whose characteristics are hardly changed even by the structure of a recording head.

Another object of the present invention is to provide an ink tank which can be suitably used for forming a high quality image.

Another object of the present invention is to provide a method for improving the intermittent ejection property in an ink jet recording method including a step of ejecting ink a plurality of times at a predetermined time interval from an ink jet recording head. It is an object of the present invention to provide a method for improving the intermittent discharge property when using a so-called side shooter type recording head that discharges liquid in a direction facing a discharge pressure generating element.

[0016]

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. It contains a coloring material containing at least carbon black and an aqueous medium, and has a potassium ion content of at least 0.6% by mass relative to carbon black.

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, a color material containing at least one self-dispersible carbon black in which at least one hydrophilic group is bonded directly or via another atomic group to the surface of the carbon black, and an aqueous medium, It is characterized by having potassium ion of 0.6% or more in ratio.

An ink cartridge which can achieve the above object is an ink cartridge having a tank accommodating portion for accommodating ink, wherein the ink is provided on at least one surface of carbon black, for example.
A coloring material containing at least a self-dispersible carbon black in which two hydrophilic groups are bonded directly or via another atomic group; and an aqueous medium containing potassium ions in a mass ratio of 0.6% or more with respect to the carbon black. It is characterized by having.

According to another aspect of the present invention, there is provided a recording unit including an ink storage unit for storing ink and a recording head unit for discharging the ink as ink droplets. The ink contains, for example, a colorant containing at least one self-dispersible carbon black in which at least one hydrophilic group is bonded directly or via another atomic group to the surface of carbon black, and an aqueous medium. By mass ratio
It is characterized by having 0.6% or more of potassium ions.

According to another aspect of the present invention, there is provided an image recording apparatus having a recording head having an ink storing section for storing ink and a recording head for discharging the ink as ink droplets by the action of thermal energy. In an ink jet recording apparatus comprising a unit, the ink contains at least one self-dispersible carbon black in which at least one hydrophilic group is bonded directly or via another atomic group to the surface of carbon black. Timber,
And an aqueous medium, and has a potassium ion content of at least 0.6% by mass with respect to carbon black.

According to another aspect of the present invention, there is provided an image recording apparatus comprising: an ink cartridge having a tank accommodating section for accommodating ink; and an ink cartridge for ejecting the ink as ink droplets by the action of thermal energy. In an ink jet recording apparatus having a recording head,
The ink contains, for example, a colorant containing at least one self-dispersible carbon black in which at least one hydrophilic group is bonded directly or via another atomic group to the surface of carbon black, and an aqueous medium. On the other hand, it has a potassium ion of 0.6% or more by mass ratio.

Further, according to the method for alleviating sticking of a recording head according to the present invention, when the ink is ejected from the recording head by applying energy to the ink,
A colorant containing at least one self-dispersible carbon black having at least one hydrophilic group bonded thereto directly or via another atomic group; and an aqueous medium, wherein the mass ratio of the colorant to the carbon black is 0.6% or more. It is characterized by using an inkjet ink having potassium ions.

Further, the ink set that can achieve the above object includes an ink containing at least one color material selected from cyan, magenta, yellow, red, green, and blue color materials, and carbon, for example. A colorant comprising at least one self-dispersible carbon black having at least one hydrophilic group bonded directly or via another atomic group to the surface of the black, and an aqueous medium,
It is characterized by having a potassium ion of 0.6% or more by mass ratio to carbon black.

In addition, the ink capable of achieving the above object has a self-dispersible pigment having a hydrophilic group as a coloring material, and has a counter ion to the hydrophilic group and, in addition to the counter ion, a polarity opposite to that of the hydrophilic group. , But having an ion having a lower hydration power than the hydration power of the hydrophilic group.

In addition, a recording head capable of achieving the above object has a self-dispersible pigment having a hydrophilic group as a coloring material, and has a counter ion for the hydrophilic group and a counter ion for the hydrophilic group other than the counter ion. It is characterized by comprising an ink having ions having a hydration power lower than the hydration power of the hydrophilic group while being polar.

In addition, the ink tank capable of achieving the above object has a self-dispersible pigment having a hydrophilic group as a coloring material, and has a counter ion for the hydrophilic group and a counter ion other than the counter ion for the hydrophilic group. It is characterized by containing an ink having ions having a hydration power lower than the hydration power of the hydrophilic group while being polar.

Further, one embodiment of the ink-jet ink which can achieve the above object is a self-dispersible carbon in which at least one hydrophilic group is bonded directly or via another atomic group to the surface of carbon black. An ink-jet ink containing black, a salt and an aqueous medium, wherein the ink is capable of stabilizing the self-dispersion type carbon black even when the flow state of the ink in a recording head becomes turbulent or disturbed. The characteristic feature is that a stable dispersion state is maintained.

According to another embodiment of the present invention, there is provided an ink jet recording method including the step of discharging ink using an ink jet recording head having an ink discharge port at a position facing an ink discharge pressure generating element. Self-dispersible carbon black in which at least one hydrophilic group is bonded directly or via another atomic group to the surface of carbon black as the ink. And a water-based medium containing at least 0.6% by weight of potassium ions with respect to the carbon black.

Another embodiment of the method for alleviating sticking according to the present invention is an ink jet method including the step of ejecting ink using an ink jet recording head having a portion in the ink flow path where the flow resistance of the liquid greatly changes. A method for reducing sticking of the recording head in a recording method,
As the ink, the carbon black comprises a colorant containing at least one self-dispersible carbon black having at least one hydrophilic group bonded directly or through another atomic group to the surface of the carbon black, and an aqueous medium, Characterized by using an inkjet ink having a potassium ratio of 0.6% or more by mass.

One embodiment of the method of improving intermittent ejection according to the present invention is an ink jet recording method comprising the steps of applying energy to ink and ejecting the ink from a recording head by an ink jet method at predetermined time intervals. A method for improving the intermittent ejection property in the method, wherein as the ink, at least one self-dispersible carbon black in which at least one hydrophilic group is bonded directly or via another atomic group to the surface of the carbon black. An ink jet ink containing a coloring material and an aqueous medium, and having potassium ions in a mass ratio of 0.6% or more with respect to the carbon black is used.

In another embodiment of the method of improving intermittent ejection according to the present invention, ink is ejected a plurality of times at predetermined intervals using a recording head which ejects ink in a direction facing the ink ejection pressure generating element. A method for improving the intermittent ejection property in an ink jet recording method including a step of performing self-dispersion in which at least one hydrophilic group is bonded directly or via another atomic group to the surface of carbon black as the ink. An ink jet ink containing a coloring material containing at least a type carbon black and an aqueous medium and having a potassium ion content of 0.6% or more by mass relative to the carbon black is used.

In another embodiment of the method of improving intermittent ejection according to the present invention, ink is supplied to a predetermined position by using a recording head having a portion in the ink flow path where the flow resistance of the liquid greatly changes. A method of improving intermittent ejection in an ink jet recording method including a step of ejecting a plurality of times at time intervals, as the ink, on the surface of carbon black,
A colorant containing at least one self-dispersible carbon black having at least one hydrophilic group bonded thereto directly or via another atomic group; and an aqueous medium, wherein the mass ratio of the colorant to the carbon black is 0.6% or more. It is characterized by using an inkjet ink having potassium ions.

(Action) The present inventors have solved the above-mentioned problem.
As a result of various experiments, it has been found that there is a correlation between the type of salt added to the ink and the structure of the recording head regarding the ink jet characteristics. For example, in the recording head shown in FIG.
252 denotes a discharge port, 253 denotes a supply port, 254 denotes a substrate, and 255 denotes a discharge port plate.

As is apparent from the drawing, the ink is largely bent at the supply port and moves toward the ejection energy generating element. The value indicating the degree of ink bending at this time is the angle θ formed by the substrate at the supply port. If θ is 90 degrees or less, the ink will bend substantially 90 degrees or more. Then, in such a recording head, it was found that the intermittent ejection property and the fixability of the ink greatly differed depending on the salt contained in the ink.

On the other hand, in the recording head having a structure in which the portion of the ink flow path that disturbs the flow of the ink is small, there is no noticeable difference in the intermittent ejection property and the fixing property due to the difference in salt. The salts that give excellent results irrespective of the structure of the recording head are all salts containing potassium, and the inks containing sodium salts and ammonium salts are not suitable for the recording head shown in FIG. It was inferior to the ink containing salt.

It is not clear why the ink containing the potassium salt is excellent in the intermittent ejection property and the fixability even in the recording head as shown in FIG. However, from the above findings, it was presumed that the salt in the ink had a great effect on the fluidity of the ink in the recording head.

Specifically, the intermittent ejection property of the above pigment ink,
It was presumed that the difference in the fixability was caused by the fact that the behavior of the cationic ion added as a salt in the ink, particularly the behavior in the recording head, was greatly different depending on the recording head used. The cause is considered to be two points: the behavior of the cation ion added as a salt and the behavior of the ink itself.

First, the behavior of an ink using a potassium salt as a salt will be discussed by the present inventors with reference to FIGS. 27 and 28. FIG. FIG. 27 (1) is a schematic diagram showing the state of carbon black in an ink containing self-dispersion type carbon black. In the figure, reference numeral 2701 denotes a self-dispersion type carbon black, reference numeral 2705 denotes a counter ion of a hydrophilic group of the carbon black, and reference numeral 2703 denotes a water molecule.
The self-dispersion type carbon black 2701 maintains a stable dispersion state by maintaining affinity with water molecules existing in the surroundings.

FIG. 27 (2) shows a case where a potassium salt is added as a salt to the ink, and FIG. 27 (3) shows a case where a sodium salt is added to the ink. Potassium ions have a negative hydration property as shown in FIG. 28 (2), while sodium ions and lithium ions have positive hydration properties as shown in FIG. 28 (1). It is.

When sodium ions are present in the ink at a predetermined concentration, as shown in FIG. 27C, water molecules 2703 existing around the self-dispersion type carbon black
Becomes localized on the sodium ion side. On the other hand, the potassium ion does not show much change in the relationship between the self-dispersible carbon black and the water molecule as compared with the case where no potassium ion is present.

This state is, of course, a schematic representation of a certain momentary state of each ink, and does not always indicate that it is in this state. I guess it is often the case. Therefore, this does not mean that the dispersion stability of the carbon black in the ink containing the sodium salt is immediately lowered.

However, as shown in FIG. 24, a recording head having a bent portion in which the main flow direction of the ink changes by 90 ° is considered to cause turbulence or disturbance in the flow state of the ink. Poor flow conditions can increase the apparent viscosity of the ink. And in such a recording head that causes disturbance in the flow state of the ink, it is caused by the difference in the state between carbon black and water molecules as shown in FIGS. 27 (2) and (3) described later. Difference in dispersion stability of self-dispersion type carbon black,
It is considered that the difference has become apparent as a difference between the intermittent ejection property and the fixability.

The present inventors have made the present invention based on such technical knowledge and consideration.

In view of such a technical background, the present inventors have conducted detailed studies on the above two points, such as the effects of a single pigment and a composite pigment, on an ink using a pigment, especially a self-dispersible carbon black. Reduces paper density dependence on density,
Even for carbon black to which salt is added for the purpose of reducing the bleeding between black colors, for example, having a potassium ratio of 0.6% or more in mass ratio, it is excellent regardless of the structure of the recording head used. The present invention has been found to have excellent intermittent ejection properties and fixability, and to be more easily used as an ink jet ink than before, and to be able to satisfy image quality with the ink.

[0039]

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 is a coloring material comprising at least one self-dispersible carbon black having at least one hydrophilic group bonded directly or via another atomic group to the surface of the carbon black. And an aqueous medium, and has a potassium ion content of at least 0.6% by mass with respect to carbon black. Hereinafter, constituent materials of the ink will be described.

(Potassium ion) The concentration of potassium ion in the ink according to the present embodiment is preferably 0.6% or more by mass with respect to carbon black. When the mass ratio is less than 50% with respect to carbon black, the storage stability of the ink itself can be maintained at an extremely high level.

That is, when the potassium ion concentration is within this range, the ink jet ink is realized with remarkable improvement in the intermittent ejection property and the fixing property. The improvement of the intermittent ejection property and the fixing property is not to improve the dispersion stability of the self-dispersion type carbon black by adjusting the pH value of the ink to an appropriate range, but to adjust the potassium ion concentration in the ink to the above range. The present inventors believe that the effect of the adjustment is greater.

The above effect is obtained by adding the pH value of the ink when potassium hydroxide, potassium benzoate or the like is added and the addition of amines such as ammonia or triethanolamine so that the potassium concentration in the ink is within the above range. Ink p
H value is adjusted equally, and the intermittent ejection property of each ink,
This is explained from the fact that the intermittent ejection property and the fixability are remarkably improved in the ink in which the potassium concentration is adjusted to the above range as compared with the ink having the same pH value when the fixability is compared. In comparison with inks to which lithium and sodium belonging to the same alkali metals are added, the ink to which potassium is added has an advantage in improving the intermittent ejection property and the fixability.

Of course, when the pH value is on the alkaline side, the stability of the ink of the present invention is further improved. If this point is combined with the present invention, the effects of the present invention can be more easily exhibited. The preferred pH range of the ink used in the present invention is as follows. The anionic self-dispersible carbon black according to the present invention tends to lack dispersion stability in an acidic aqueous solution, and is preferably 7 or more and 10 or less in consideration of ink contact with a recording head.

Although the detailed reason why the ink of the present invention exhibits the above properties is unknown, self-dispersion is caused by the interaction between potassium ions present in a predetermined amount in the ink and hydrophilic groups bonded to the surface of carbon black. It is considered that the reduction in dispersion stability and redispersibility of the carbon black is improved. That is, the present invention is fundamentally different from the addition of, for example, potassium hydroxide or the like for solubilizing a dispersant, that is, the addition for making the dispersion alkaline.

In the ink used in the present invention, the stability of the ink alone is higher on the alkali side than in the neutral region. However, the essence of the present invention is not to pursue only the stability of the ink alone, but rather to improve the stability near the ejection port. Also in this respect, the concept is fundamentally different from the addition of potassium hydroxide or the like for making the dispersion alkaline.

Further, the mechanism exerting the effect by the presence of potassium ions will be described in further detail below with reference to FIG. FIG. 27 is a schematic diagram for explaining the mechanism by which the presence of potassium ions brings about the effect of the present invention. In the figure, 2703 indicates a water molecule, 2709 indicates a sodium ion, 2707 indicates a potassium ion, 2701 indicates a self-dispersion type carbon black, and 2705 indicates a counter ion of a hydrophilic group of carbon black.

As shown in FIG. 27 (1), the self-dispersion type carbon black 2701 usually has a counter ion 2705 and a number of water molecules 2703 around the hydrophilic group and the counter ion.
Exist and are dispersed in a stable state. Next, FIG. 27 shows an image in the case where a large amount of monovalent cation ions are present in the ink and cations are present in addition to the carbon counter.
It is assumed that the state is as shown in (2) and (3).

That is, when a large amount of potassium ion 2707 is present around the self-dispersible carbon black as a cation other than the counter, there is not much difference from the state shown in FIG. There is no. On the other hand, when sodium ions are present as cations other than the counter around the self-dispersion type carbon black, as shown in FIG. 27 (3), the water molecules 2703 are converted to sodium ions 2709 rather than the self-dispersion type carbon black 2701.
Will be more likely to be around. It is speculated that as a result, the dispersion stability of the self-dispersion type carbon black is deteriorated.

At this time, it is considered that the difference as shown in FIG. 27 hardly occurs depending on the type of counter ion, and the counter ion is not particularly limited to potassium ion, but may be sodium ion or the like. Naturally, ions move in the ink, and the same ion does not always exist as a carbon counter ion, but always exchanges with each other in the ink.The conceptual diagram shown in FIG. It is something that caught.

However, if there is a large amount of potassium ions in the ink, the state of FIG. 27 (2) is likely to be high, and if there is a large amount of sodium ions, the state of FIG. 27 (3) is high. I have. It is believed that the difference between the two is due to the difference in hydration of the ions. Compared to potassium ions, lithium ions, sodium ions and the like are very easily hydrated.

As shown in FIG. 28, the present inventors point out that sodium ions and lithium ions have a so-called positive hydration property, whereas potassium ions have a negative hydration property. I believe. In other words, when sodium ions and lithium ions are present in the ink, water molecules that originally exist around the self-dispersible carbon black and maintain the dispersion stability of the self-dispersible carbon black are converted into water molecules of these ions. It is considered that, due to the high compatibility, the carbon black is separated from the periphery of the self-dispersible carbon black and is present around the cation ions.

On the other hand, the potassium ion has a weaker hydration property than the self-dispersion type carbon black, and hardly causes water molecules existing around the self-dispersion type carbon black to exist around itself. I believe. still,
FIG. 28 is a conceptual diagram for explaining that the hydration properties of sodium ions and the like and potassium ions are different.

Of course, it is ideal that all the self-dispersion type carbon black in the ink is in the state as shown in FIG. 27 (2). In order to exhibit the above, all the self-dispersion type carbon blacks do not necessarily need to be in the state as shown in FIG. 27 (2), and may be partially in the state as shown in FIG. 27 (3). That is, it has been found that the effects of the present invention can be exerted even in a mixed system in a state as shown in FIG. 27 (2) and FIG. 27 (3). That is, the present inventors have come to the conclusion that the effects of the present invention can be exhibited if potassium ions have a mass ratio of 0.6% or more with respect to carbon black.

Although the mechanism inferred by the present inventors has been described in detail above, the technical idea of the present invention is that the hydration of monovalent cation ions present around the self-dispersible carbon black is weak. Is important, and it is important that it is weaker than the hydration property of the self-dispersible carbon black. Therefore, other than potassium ion, if it has the same properties as potassium ion (non-affinity for water),
It is considered to be within the technical concept of the present invention.

The above phenomenon occurs when a recording head having a portion that disturbs the flow state of the ink accompanying the ink supply, for example, a recording head having a portion in the ink flow path where the flow resistance greatly changes is used. The effect will be more pronounced. The details of the reason are not clear, but the present inventors speculate as follows.

The phenomenon described with reference to FIG. 27 is extremely unlikely to occur with ink in a closed form (in other words, a state where there is no external factor other than time and gravity). However, as described above, even if the same ink is used, the fixing property and the like greatly differ depending on the recording head used.

In view of this point, the present inventors thought that something in the recording head was triggered and greatly degraded the dispersion stability of the ink. It became clear that it was not due to the material but to the structure itself. That is, it was concluded that a significant change in the flow path resistance during the ink flow path was triggered.

(Self-dispersion type carbon black) 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 the self-dispersible carbon black, those having ionicity are preferable.

Examples of the anionic charged carbon black include carbon black having the following hydrophilic groups bonded to the surface of the carbon black. -COOM, -SO ₃ M, -PO ₃ HM, -PO ₃ M _{2 In the} above formula, M represents a hydrogen atom, an alkali metal, ammonium or an organic ammonium, and among these, especially -C
Carbon black obtained by bonding OOM or —SO ₃ M to the surface of carbon black and anionically charged is particularly suitable for use in the present embodiment because of its good dispersibility in ink.

Among the hydrophilic groups represented by M, specific examples of the alkali metal include, for example, Li,
Na, K, Rb and Cs. Specific examples of the organic ammonium include, for example, methyl ammonium, dimethyl ammonium, trimethyl ammonium, ethyl ammonium, diethyl ammonium, triethyl ammonium, methanol ammonium, dimethanol ammonium, trimethanol ammonium and the like. Is mentioned.

An ink containing self-dispersion type carbon black in which M is ammonium or organic ammonium can further improve the water resistance of a recorded image, and can be suitably used in this respect. This is considered to be due to the effect that when the ink is applied on the recording medium, ammonium is decomposed and ammonia is evaporated.

The self-dispersible carbon black in which M is ammonium can be prepared by, for example, replacing the self-dispersible carbon black in which M is an alkali metal with M by ammonium using an ion exchange method, or adding an acid to form H-type carbon black. And then adding ammonium hydroxide to convert M to ammonium.

As a method for producing a self-dispersible carbon black charged anionic, for example, a method of oxidizing carbon black with sodium hypochlorite may be mentioned.
Na groups can be chemically bonded.

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. Can be 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. Specific examples of the combination of another atomic group and a hydrophilic group include, for example, -C ₂ H ₄ -COOM, -Ph-SO ₃ M, -Ph-
COOM and the like (where Ph represents a phenylene group and M is defined as above).

Further, as a result of intensive studies by the present inventors, carbon black having a hydrophilic group density of 1.8 μmol / m ² or more is used together with potassium among the above-mentioned anionic charged self-dispersion carbon blacks. As a result, it was found that particularly excellent intermittent ejection property and sticking property were exhibited. It is considered that the reason for this is that potassium ions interact with hydrophilic groups to improve the dispersion stability and redispersibility of the self-dispersible carbon black, and the use of carbon black having a hydrophilic group density in the above range is considered. It is conceivable that this effect appears more sensitively.

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 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 from 0.1% by mass to 15% by mass, more preferably from 1% by mass to 10% by mass, based on the total mass of the ink. Range. Further, the color tone of the ink may be adjusted by using a dye in addition to the self-dispersible carbon black.

(Hydrophilic Group Density) As a method for measuring the hydrophilic group density of the self-dispersible carbon black, for example, a carbon dispersion is purified, all the counter ions are converted to sodium ions, and the sodium ions are converted to a probe-type sodium electrode. To determine the amount of sodium ions contained in the entire dispersion. There is a method of converting the amount of sodium ions and the concentration of carbon black in the dispersion into parts per million (ppm) per solid content. The conversion is performed on the assumption that a hydrophilic group such as a carboxyl group is present in the same mole number as a sodium ion as a counter ion.

Next, the recording head will be described. The head in which the effects of the present invention are more remarkably exhibited, that is, when a self-dispersion type carbon black ink to which the salt disclosed by the present inventors is added is used, if the recording head which is difficult to use is described, There is a recording head having a portion in the ink flow path where the flow resistance greatly changes. As a specific example, for example, the following heads are mentioned as typical examples.

1) The flow path direction is substantially 9 in the head chip.
There is a part that bends 0 degrees or more 2) There is a part in the head chip where the surface energy is significantly different from the surroundings 3) There is a part where the flow path width in the head chip is 20 μm or less The above part is partially It is considered that the dispersibility of the ink whose dispersion is unstable becomes worse.
The details will be described below with reference to the drawings.

First, the case 1) will be described. Figure 24,
FIG. 25 is a schematic sectional view of a head having a configuration in which the effects of the present invention are more remarkably exhibited. In the figure, 251 is an ejection energy generating element, 252 is an ejection port, 253 is a supply port, 254 is a substrate,
255 indicates a discharge port plate.

As is apparent from the figure, the ink is largely bent at the supply port and moves toward the ejection energy generating element. The value indicating the degree of ink bending at this time is the angle θ formed by the substrate at the supply port. If θ is 90 degrees or less, the ink will bend substantially 90 degrees or more.

In this case, for example, it is considered that it is difficult to mix and uniform the inks in the chip by self-diffusion. In other words, it is difficult to stabilize the dispersion of the ink whose dispersion has become unstable due to the presence of a portion where a certain kind of stagnation is likely to be formed, by contact-mixing with the ink whose dispersion is stable. In addition, disturbance occurs in the flow state of the ink, or a turbulent state occurs, the apparent viscosity of the ink increases, and at this time, the influence of the self-dispersion type carbon black that has become unstable and dispersed as described above becomes apparent. Conceivable.

Next, 2) will be described. FIG. 26 shows a schematic view of a head having a portion where the surface energy is largely different from the surroundings. In this schematic diagram, a portion where the surface energy is significantly different from the surroundings is shown as a projection. In the figure 261
Is a coating resin layer, 262 is a discharge energy generating element, 263
Indicates a protrusion. In this case, it is conceivable that the ink is trapped in the vicinity of the protrusion and becomes difficult to move due to the difference in surface energy. In addition, the flow state of the ink is disturbed,
Alternatively, it is considered that a turbulent state occurs, the apparent viscosity of the ink increases, and at this time, the influence of the self-dispersion type carbon black which has become unstable as described above becomes apparent.

Next, 3) will be described with reference to FIG. 26 similarly to 2). The portion indicated by A in the figure is narrower than the periphery in the ink flow path. Specifically, there is a portion of 20 μm or less. In such a head, as in the case of 1), it is difficult for the inks to mix and uniform within the chip by self-diffusion. In other words, it is difficult to stabilize the dispersion of the ink whose dispersion has become unstable due to the presence of a portion where a certain kind of stagnation is likely to be formed, by contact-mixing with the ink whose dispersion is stable. In addition, disturbance occurs in the flow state of the ink, or a turbulent state occurs, the apparent viscosity of the ink increases, and at this time, the influence of the self-dispersion type carbon black that has become unstable and dispersed as described above becomes apparent. Conceivable.

Needless to say, when the above 1), 2) and 3) are combined, the effect of the present invention becomes more remarkable. For example, the flow path width in the vicinity of the bending portion is 20 μm or less. Further, as an example in which the effect of the present invention is remarkably exhibited, there is an example in which a recording head having a discharge amount per dot of 40 ng or less is used. This is because a print head with a small ejection amount is likely to fall under 3) in the example of a print head having a portion where the flow path resistance changes greatly. Of course, the present invention is not limited to the above-described ejection amount.

Next, a method for adjusting the potassium content in the ink will be described. As an adjustment method, a method of adding in the form of a salt may be mentioned.

Specifically, for example, potassium hydroxide, potassium benzoate, potassium phthalate, potassium acetate, potassium succinate, potassium citrate, potassium gluconate, potassium nitrate, potassium phosphate, potassium sulfate, potassium carbonate, chloride Potassium, potassium bromide and the like. The potassium salts as described above can be used alone or as a mixture.

When potassium ions are added in the above salt form, part or all of the counter ions of the surface functional groups of the self-dispersible carbon black are replaced by potassium ions, depending on the amount of addition.

(Monovalent Cation Ion) The total amount of monovalent cation ions in the ink according to the present embodiment is from 0.05 mol / L to 1 mol / L, particularly 0.1 mol / L, based on the total amount of the aqueous pigment ink. The range of 0.5 mol / L is preferable. That is, 1
When the total amount of the cationic cations is within this range, a high image density and a high quality image can be obtained, and there is no problem in the characteristics of the ink, such as storage stability.

The reason for obtaining high image density and high quality image as described above is that the total amount of monovalent cation ions in the ink is included in the above-mentioned predetermined amount, so that the ink discharged from the nozzles This is probably because solid-liquid separation occurs immediately after the adhesion. In this phenomenon, the total amount of monovalent cation ions in the ink is important.

That is, a certain amount or less, specifically 0.05 m
If it is less than 1 / L, solid-liquid separation may not occur at the required speed. On the contrary, if it exceeds 1 mol / L, the stability of the ink itself may not be preferable.

The causes of the solid-liquid separation are considered to be a capillary phenomenon, water evaporation, and the like. However, the present inventors believe that the largest factor causing the solid-liquid separation of the ink of the present invention is water evaporation after ejection. thinking. Of course, the capillary phenomenon on paper after impact is also one of the factors that cause solid-liquid separation.However, based on the following facts, the present inventors have determined that the evaporation of water after ejection can cause the solid-liquid separation of the ink of the present invention. Think of it as a factor.

The ink of the present invention can be used even on a clean glass surface.
Solid-liquid separation occurs earlier than in the case where the total amount of monovalent cation ions in the ink is equal to or less than the predetermined amount. That is,
The above facts clearly show that the ink of the present invention causes solid-liquid separation even when capillary action does not occur. Therefore, the present inventors have come to believe that the largest cause of the solid-liquid separation of the ink of the present invention is water evaporation after ejection.

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, etc. 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 quantifying cations in the ink, for example, a combination of ion chromatography and plasma emission spectroscopy is used.

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 tetramethyl ammonium ion, a mono to tetraethyl ammonium ion, and a mono to tetramethanol ammonium ion.

In order to adjust the total amount of cationic ions in the ink, for example, a method of adding the above-mentioned cations in the form of a salt can be used. Examples of combinations of the cation ion and the counter anion ion when the cation ion is added in the form of a salt include the following: As the cation ion, ammonium ion, potassium ion, sodium ion, lithium ion, etc. One selected from the group consisting of ammonium ion, halogen ion (chlorine ion, etc.), acetate ion, benzoate ion, etc.
One.

These salts provide inks that are particularly excellent in image density and image quality, probably because of their excellent compatibility with self-dispersible carbon black.

(Aqueous Medium) A preferable aqueous medium capable of supporting the above-described properties in the ink according to each of the above embodiments is water alone or 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, and
It is desirable 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 and sec-butyl. 1-4 carbon atoms such as alcohol and tert-butyl alcohol
Amides such as dimethylformamide and 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 Alkylene glycols whose alkylene group contains 2 to 6 carbon atoms, such as propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol; polyethylene Lower alkyl ether acetates such as glycol monomethyl ether acetate; glycerin; ethylene glycol monomethyl (or ethyl)
Lower alkyl ethers of polyhydric alcohols such as ether, diethylene glycol methyl (or ethyl) ether and triethylene glycol monomethyl (or ethyl) ether; polyhydric alcohols such as trimethylolpropane and trimethylolethane; N-methyl-2-pyrrolidone 2, 2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, acetylene alcohol and the like. 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 3% by mass or more based on the total mass of the ink.
The range is 50% by mass or less. The content of water contained in the ink is preferably 50 to the total mass of the ink.
It is in a range of not less than 95% by mass and not more than 95% by mass.

When it is necessary to adjust the surface tension of the ink, it is effective to appropriately add a predetermined amount of a surfactant such as acetylene alcohol or a permeable solvent represented by the following chemical formula.

[0093]

Embedded image

The aqueous pigment ink of the present invention may further comprise a surfactant, an antifoaming agent, a preservative, a fungicide, etc. in order to obtain an ink having desired physical properties, if necessary, in addition to the above components. 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 use mechanical energy
The ink of the present invention is particularly suitable for such a recording method in which a droplet is ejected by firing the ink by applying thermal energy to the ink.

(Inkjet Recording Apparatus, Inkjet Recording Method) First, as an inkjet recording apparatus, an example of a head configuration which is a main part of an apparatus utilizing thermal energy is shown in FIGS.

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 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 has a protective layer 16 made of silicon oxide, silicon nitride, silicon carbide, etc., electrodes 17-1, 17-2, HfB ₂ , made of aluminum, gold, aluminum-copper alloy, etc.
A heating resistor layer 18 formed of a high melting point material such as TaN or TaAl, a heat storage layer 19 formed of thermally oxidized silicon or aluminum oxide, or the like, formed of a material having good heat dissipation properties such as silicon, aluminum, or aluminum nitride. It consists of substrate 20.

When a pulse-like electric signal is applied to the electrodes 17-1 and 17-2 of the head, n of the heating element substrate 15
The area indicated by 発 熱 rapidly generates heat, bubbles are generated in the ink 21 in contact with the surface, the meniscus 23 protrudes due to the generated pressure, the ink is discharged through the nozzle 14 of the head, and the ink is smaller than the discharge orifice 22. The droplets 24 fly 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 serving 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 case,
The recording head 65 is held in a protruding form in the movement path.

Reference numeral 62 denotes a cap on the protruding port 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 port surface. And a configuration for performing capping. Further, reference numeral 63 denotes an ink absorber provided adjacent to the blade 61, and is held in a form protruding into the movement path of the recording head 65, similarly to the blade 61. The above blade 61, cap 62 and ink absorber
The discharge recovery section 64 is composed of 63 and the blade 61
In addition, the ink absorber 63 removes moisture, dust, and the like from the ejection port surface.

Reference numeral 65 denotes a discharge energy generating means,
A recording head 66 that discharges ink to a recording material facing an ejection port surface provided with ejection ports to perform recording.
And a carriage for moving the recording head 65 with the. 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). Thus, the carriage 66 can move along the guide shaft 67, and the recording head 65 can move the recording area and the area adjacent thereto. 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 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 print head 65 finishes printing and returns to the home position, the cap of the ejection recovery section 64
62 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 ejection surface of the recording head 65 with the cap 62, 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, the ejection port surface of the recording head 65 is also wiped during this movement.

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 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. Where 4
Reference numeral 0 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 of the ink storage unit. 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 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 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 used 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.
It is detachable from the carriage 66.

Next, as an embodiment of an ink jet recording apparatus utilizing 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 to face the nozzles, An on-demand inkjet recording head that includes ink filling around the pressure generating element, displaces the pressure generating element by an applied voltage, and discharges small droplets of ink from a nozzle can be given. 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 It comprises a pressure transmitting element 83 which is joined to the diaphragm 82 and is displaced by an electric signal, and a substrate 84 for pointing and fixing the orifice plate 81, the diaphragm and the like.

In FIG. 7, the wall of the ink flow path 80 is formed of a photosensitive resin or the like, and the orifice plate 81 has a discharge port 85 formed by punching a metal such as stainless steel or nickel by electroforming or pressing. The vibration plate 82 is formed of a metal film such as stainless steel, nickel, titanium and the like and a high elastic resin film, and the piezoelectric element 83 is formed of a dielectric material such as barium titanate and 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, and the energy thereof deforms the diaphragm joined to the piezoelectric element 83, and the ink flow path 80 The ink in the inside of the orifice plate is pressurized vertically, and an ink droplet (not shown) is ejected from the ejection port 85 of the orifice plate to perform printing.

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.

FIGS. 8 (a) to 8 (f) are cross-sectional views showing an example of a method of manufacturing a recording head which remarkably exhibits the effects of the present invention, which is arranged in the order of steps. Of course, the present invention is not limited to the recording head manufactured based on this manufacturing method.

First, for example, as shown in FIG.
A substrate 1 made of glass, ceramics, plastic, metal or the like is prepared.

The substrate 1 can function as a part of a liquid flow path constituting member, and can function as a support for a material layer forming an ink flow path and an ink discharge port described later. It can be used without any particular limitation on its shape, material and the like. On the substrate 1, a desired number of ink ejection energy generating elements 2 such as electrothermal conversion elements or piezoelectric elements are arranged. The ejection energy for ejecting the ink droplets by the ink ejection energy generating element 2 is applied to the ink liquid, and recording is performed.

Incidentally, for example, when an electrothermal conversion element is used as the ink discharge energy generating element 2, this element heats a recording liquid in the vicinity, thereby
A state change is caused in the recording liquid to generate ejection energy. Further, for example, when a piezoelectric element is used, ejection energy is generated by mechanical vibration of the element.

Note that these elements 2 are connected to control signal input electrodes (not shown) for operating these elements. Further, in general, various functional layers such as a protective layer are provided for the purpose of improving the durability of the ejection energy generating element. However, such a functional layer may be provided in the present invention.

FIG. 8A illustrates an example in which an opening 3 for supplying ink is provided in advance on the substrate 1 and ink is supplied from behind the substrate 1. In forming the opening 3, any method can be used as long as it can form a hole in the substrate 1. For example, it may be formed by a mechanical means such as a drill, or light energy such as a laser may be used. Alternatively, a resist pattern or the like may be formed on the substrate 1 and chemically etched.

Of course, the opening 3 for supplying ink may not be formed in the substrate 1 but may be formed in a resin pattern and provided on the same surface as the ink discharge port 8 with respect to the substrate 1.

Next, as shown in FIG. 8A, an ink flow path pattern 4 is formed on the substrate 1 with a resin that can be dissolved so as to cover the ink discharge energy generating element 2. The most common means is a means made of a photosensitive material, but it can also be made by means such as a screen printing method. When a photosensitive material is used, since the ink flow path pattern can be dissolved, a positive resist or
Alternatively, it is possible to use a soluble type negative resist.

As a method of forming a resist layer, when a substrate provided with an ink supply port on the substrate is used, the photosensitive material is dissolved in an appropriate solvent and the resist material is dissolved on a film such as PET (polyethylene terephthalate). It is preferable to form a dry film by coating and drying, and to form the film by lamination. As the above-mentioned dry film, a vinyl ketone-based photo-degradable polymer compound such as polymethyl isopropyl ketone and polyvinyl ketone can be suitably used. This is because these compounds maintain the properties (coating properties) as a polymer compound before light irradiation, and the opening 3
This is because it can be easily laminated on top.

Further, a filler which can be removed in a later step may be arranged in the opening 3 and a film may be formed by a usual spin coating method, roll coating method or the like.

As shown in FIG. 8 (b), on the dissolvable resin material layer 4 in which the ink flow path was patterned,
Further, the coating resin layer 5 is formed by a usual spin coating method, roll coating method or the like. Here, in the step of forming the coating resin layer 5, characteristics such as not deforming the soluble resin pattern are required. That is, when the coating resin layer 5 is dissolved in a solvent and formed on the dissolvable resin pattern 4 by spin coating, roll coating or the like, it is necessary to select a solvent so as not to dissolve the dissolvable resin pattern 4. is there.

Here, the coating resin layer 5 will be described.
As the coating resin layer 5, an ink ejection port described later can be easily and accurately formed by photolithography.
Photosensitive ones are preferred. Such a photosensitive coating resin layer 5 is required to have high mechanical strength as a structural material, adhesion to the substrate 1 and ink resistance, and at the same time, resolution for patterning a fine pattern of ink discharge ports. Is done. Here, it is found that the cationically polymerized cured product of the epoxy resin has excellent strength, adhesion, and ink resistance as a structural material, and has excellent patterning characteristics if the epoxy resin is solid at room temperature. Have been.

First, a cationically polymerized cured product of an epoxy resin has a higher crosslinking density (higher Tg) than a cured product of a usual acid anhydride or amine, and therefore exhibits excellent properties as a structural material. Further, by using a solid epoxy resin at normal temperature, diffusion of a polymerization initiation species generated from a cationic polymerization initiator by light irradiation into the epoxy resin can be suppressed, and excellent patterning accuracy and shape can be obtained.

In the step of forming the coating resin layer on the dissolvable resin layer, it is desirable to dissolve the solid coating resin in a solvent at room temperature and to form the coating resin layer by spin coating.

By using the spin coating method, which is a thin film coating technique, the coating resin layer 5 can be formed uniformly and accurately, and the distance between the ink ejection energy generating element 2 and the orifice is difficult with the conventional method. (OH
Distance) can be shortened, and the ejection of small droplets can be easily achieved.

When the above-mentioned negative photosensitive material is used as the coating resin, reflection from the substrate surface and scum (development residue) usually occur. However, in the case of the present invention, since the discharge port pattern is formed on the ink flow path formed of a dissolvable resin, the influence of reflection from the substrate can be neglected. Is lifted off in the step of washing out the soluble resin that forms

The solid epoxy resin used in the present invention includes a reaction product of bisphenol A and epichlorohydrin having a molecular weight of about 900 or more, a reaction product of bromosphenol A-containing epichlorohydrin, phenol novolak or o-phenol. Reaction product of cresol novolak with epichlorohydrin, JP-A-60-161973, JP-A-63-221121, JP-A-64-9216, JP-A-2-1
Examples thereof include a multi-sensitive epoxy resin having an oxycyclohexane skeleton described in Japanese Patent No. 40219, but the present invention is not limited to these compounds.

Examples of the cationic photopolymerization initiator for curing the epoxy resin include aromatic iodonium salts and aromatic sulfonium salts [J. POLYMER SCI: Sympo.
Shim No. 56 383-395 (1976)] and SP-150 and SP-170 marketed by Asahi Denka Kogyo Co., Ltd.

The cationic photopolymerization initiator described above can promote cationic polymerization (the crosslink density is improved as compared with single photocationic polymerization) by heating in combination with a reducing agent. However, when using a cationic photopolymerization initiator and a reducing agent in combination, the reducing agent is selected so as to be a so-called redox type initiator system which does not react at room temperature but reacts at a certain temperature or higher (preferably 60 ° C or higher). There is a need.

As such a reducing agent, a copper compound, particularly copper triflate (copper (II) trifluoromethanesulfonate) is most preferable in consideration of reactivity and solubility in an epoxy resin. Also, a reducing agent such as ascorbic acid is useful. In addition, higher crosslinking density, such as increasing the number of nozzles (high-speed printability) and using non-neutral ink (improving the water resistance of the colorant)
If (high Tg) is required, the crosslink density is increased by a post-process of immersing and heating the coating resin layer using the above-described reducing agent in the form of a solution after the step of developing the coating resin layer as described below. Can be.

Further, additives such as additives can be appropriately added to the above composition as needed. For example, addition of a flexibility-imparting agent for the purpose of lowering the elastic modulus of the epoxy resin, or addition of a silane coupling agent for obtaining further adhesion to the substrate may be mentioned.

Next, the photosensitive coating resin layer 5 made of the above compound is subjected to pattern exposure through a mask 6 as shown in FIG. The photosensitive coating resin layer 5 is of a negative type, and shields a portion for forming an ink discharge port with a mask (of course, also shields a portion for performing an electrical connection; not shown).

The pattern exposure can be appropriately selected from ultraviolet rays, Deep-UV light, electron beams, X-rays and the like in accordance with the photosensitive region of the cationic photopolymerization initiator to be used.

Here, in all of the steps so far, alignment can be performed by using the conventional photolithography technique, and it is possible to significantly improve the accuracy as compared with a method in which an orifice plate is separately formed and bonded to a substrate. it can. The photosensitive coating resin layer 5 thus pattern-exposed may be subjected to a heat treatment, if necessary, in order to accelerate the reaction. Here, as described above, since the photosensitive coating resin layer is composed of epoxy resin that is solid at room temperature, diffusion of the cationic polymerization initiation species generated by pattern exposure is restricted, and excellent patterning accuracy and shape are realized. it can.

Next, the photosensitive coating resin layer 5 that has been subjected to the pattern exposure is developed using an appropriate solvent to form an ink discharge port 8 as shown in FIG. Here, it is also possible to develop the dissolvable resin pattern 4 which forms the ink flow path simultaneously with the development of the unexposed photosensitive coating resin layer.

However, in general, a plurality of heads of the same or different forms are arranged on the substrate 1 and used as an ink jet liquid discharge head through a cutting step. Therefore, as a measure against dust during cutting, FIG. By selectively developing only the photosensitive coating resin layer 5 as shown in d),
It is also possible to leave the resin pattern 4 forming the ink flow path 9 (there is no dust generated during cutting because the resin pattern 4 remains in the liquid chamber) and develop the resin pattern 4 after the cutting step (FIG. 8). (e)). At this time,
The scum (development residue) generated when developing the photosensitive coating resin layer 5 is eluted together with the soluble resin layer 4, so that no residue remains in the nozzle.

If it is necessary to increase the crosslink density as described above, the photosensitive coating resin layer 5 in which the ink flow paths 9 and the ink discharge ports 8 are formed is then immersed in a solution containing a reducing agent. Post-curing is performed by heating.
Thereby, the crosslink density of the photosensitive coating resin layer 5 is further increased, and the adhesion to the substrate and the ink resistance become very good.

Of course, in the step of immersion and heating in the copper ion-containing solution, the photosensitive coating resin layer 5 is subjected to pattern exposure,
Even if the development is performed immediately after the formation of the ink discharge ports 8 by development, the dissolvable resin pattern 4 may be eluted afterwards. In the immersion and heating steps, heating may be performed while immersion may be performed, or heat treatment may be performed after immersion.

As such a reducing agent, any substance having a reducing action is useful. In particular, copper triflate,
Compounds containing copper ions such as copper acetate and copper benzoate are effective. Among the above compounds, copper triflate in particular exhibits a very high effect. In addition to the above, ascorbic acid is also useful.

An electric connection (not shown) for driving the ink supply member 7 and the ink discharge pressure generating element 2 to the substrate on which the ink flow path and the ink discharge port thus formed are formed. ) To form an inkjet liquid ejection head (see FIG. 8 (f)).

In the present production example, the formation of the ink discharge port 8 was performed by photolithography. However, the present invention is not limited to this, and by changing the mask, the ink discharge port 8 can be formed by dry etching using oxygen plasma or excimer laser. The discharge port 8 can be formed. When the ink discharge ports 8 are formed by excimer laser or dry etching, the substrate is protected by the resin pattern and is not damaged by laser or plasma, so that a highly accurate and reliable head can be provided. . Further, when forming the ink discharge ports 8 by dry etching, excimer laser, or the like, the coating resin layer 5 may be a thermosetting one other than a photosensitive one.

Next, another specific example of a recording apparatus and a recording head which can be suitably used in the present invention will be described. FIG. 9 is a schematic perspective view showing a main part of an example of a liquid discharge head as a liquid discharge head of a discharge method and a liquid discharge apparatus using this head, which communicates bubbles with the atmosphere at the time of discharge according to the present invention. is there.

In FIG. 9, the ink jet printer includes a transport device 1030 that intermittently transports a sheet 1028 as a recording medium provided along a longitudinal direction in a casing 1008 in a direction indicated by an arrow P in FIG. Transfer device 1
The direction S that is substantially perpendicular to the transport direction P of the paper 1028 by 030
A recording unit 1010 reciprocating substantially in parallel with the camera, and a moving drive unit as driving means for reciprocating the recording unit 1010
And 1006.

The movement driving unit 1006 is provided with pulleys 1026a and
A belt 1016 wound around 1026b and a recording unit 101 arranged substantially parallel to the roller units 1022a and 1022b.
And a motor 1018 for driving a belt 1016 connected to the carriage member 1010a in the forward and reverse directions.

The motor 1018 is activated and the belt 1
When 016 rotates in the direction of arrow R in FIG.
The carriage member 1010a is moved by a predetermined amount in the direction of arrow S in FIG. When the motor 1018 is activated and the belt 1016 rotates in the direction opposite to the direction of the arrow R in FIG. 9, the carriage member 1010a of the recording unit 1010 moves in the predetermined direction in the direction opposite to the direction of the arrow S in FIG. It will be moved by the moving amount. Further, at one end of the movement driving unit 1006, a recovery unit 1026 for performing an ejection recovery process of the recording unit 1010 is provided at a position serving as a home position of the carriage member 1010a so as to face the ink ejection port arrangement of the recording unit 1010. Is provided.

[0149] The recording unit 1010 includes an ink jet cartridge (hereinafter, may be simply referred to as a cartridge).
12Y, 1012M, 1012C, and 1012B are detachably provided for the carriage member 1010a for each color, for example, yellow, magenta, cyan, and black.

FIG. 10 shows an example of an ink jet cartridge that can be mounted on the above-described ink jet recording apparatus.
The cartridge 1012 in this example is of a serial type, and its main part is composed of an ink jet recording head 100 and a liquid tank 1001 for storing a liquid such as ink.

The ink jet recording head 100 has a large number of discharge ports 832 for discharging liquid.
Liquid such as ink is supplied from the liquid tank 1001 to a common liquid chamber of the liquid ejection head 100 through a liquid supply passage (not shown).
(See FIG. 11). The cartridge 1012 integrally forms the ink jet recording head 100 and the liquid tank 1001 so that liquid can be supplied to the liquid tank 1001 as needed. Tank 1001
May be employed in a replaceable manner.

A specific example of the above-described liquid discharge head that can be mounted on the ink jet printer having such a configuration will be described in more detail below.

FIG. 11 is a schematic perspective view schematically showing a main part of a liquid discharge head showing a basic mode of the present invention.
12 to 15 are front views showing the shapes of the ejection ports of the liquid ejection head shown in FIG. Note that electrical wiring and the like for driving the electrothermal transducer are omitted.

In the liquid ejection head of this embodiment, a substrate 934 made of glass, ceramics, plastic, metal, or the like, for example, as shown in FIG. 11, is used. The material of such a substrate is not the essence of the present invention, and functions as a part of the flow path constituting member, and serves as a support for the ink discharge energy generating element, and a material layer forming a liquid flow path and a discharge port described later. , If it works
There is no particular limitation. Therefore, in this example, Si
The case where a substrate (wafer) is used will be described. In addition to the forming method using a laser beam, for example, an orifice plate (discharge port plate)
It can also be formed by an exposure apparatus such as PA (Mirror Projection Aligner).

In FIG. 11, reference numeral 934 denotes an ink supply port 933 comprising an electrothermal conversion element (hereinafter sometimes referred to as a heater) 931 and a long groove-shaped through-hole serving as a common liquid chamber.
The heaters 931 serving as thermal energy generating means are provided on both sides of the ink supply port 933 in the longitudinal direction in such a manner that the heaters 931 are arranged in a row in a zigzag manner.
It is arranged at 00dpi. On this substrate 934, an ink flow path wall 936 for forming an ink flow path is provided. The ink flow path wall 936 is provided with a discharge port plate 935 further having a discharge port 832.

Here, in FIG. 11, the ink flow path wall 93 is shown.
6 and the discharge port plate 935 are shown as separate members, but the ink flow path wall 936 and the discharge port plate 935 are formed on the substrate 934 by, for example, a method such as spin coating. Can be formed simultaneously as the same member. In this example, the discharge port surface (upper surface) 935a side is further subjected to a water-repellent treatment.

In this example, a serial type head that performs recording while scanning in the direction of arrow S in FIG. 9 is used to perform recording at, for example, 1200 dpi. The driving frequency is 10 kHz, and one discharge port discharges at a minimum time interval of 100 μs.

Further, as an example of the actual size of the head,
For example, as shown in FIG. 12, a partition 936a that fluidly isolates adjacent nozzles has a width w = 14 μm. Fig. 15
As shown in the figure, in the foaming chamber 1337 formed by the ink flow path wall 936, N ₁ (width of the foaming chamber) = 33 μm and N ₂ (length of the foaming chamber) = 35 μm. The size of the heater 931 is
The heater resistance is 53 Ω at 30 μm × 30 μm, and the driving voltage is 10.3 V. The height of the ink flow path wall 936 and the partition 936a is 12 μm, and the thickness of the discharge port plate is 11 μm.
m can be used.

In the cross section of the discharge port portion 940 provided on the discharge port plate including the discharge port 832, the ink discharge direction
The cross section taken along a direction intersecting (thickness direction of the orifice plate 935) has a substantially star-shaped cross section, and has six raised portions 832a having obtuse angles and these raised portions 832a.
6 ridges alternating between and having sharp corners 8
32b. In other words, the bottom 832b as a region locally distant from the center O of the discharge port is its top, and the rising portion 832a as a region locally close to the center O of the discharge port adjacent to this region is its base. 11
Orifice plate thickness direction (liquid discharge direction)
6 grooves are formed (for the position of the grooves, see FIG. 1).
6 see 1141a).

In the present example, the discharge port 940 has a cross section cut in a direction intersecting the thickness direction, for example, with two sides.
The shape is such that two equilateral triangles each having a diameter of 7 μm are combined in a state rotated by 60 degrees, and T ₁ shown in FIG. 13 is 8 μm. The angle of the raised part 832a is all 120 degrees,
The angles of b are all 60 degrees.

Therefore, it is formed by connecting the center O of the discharge port and the center of the groove adjacent to each other (the center (center of gravity) of the figure formed by connecting the top of the groove and the two bases adjacent to the top). And the center of gravity G of the polygon.
The opening area of the discharge port 832 in this example is 400 μm ² , and the opening area of the groove (the area of a figure formed by connecting the top of the groove and two bases adjacent to the top) is about 33 μm ² per one.
It has become.

FIG. 14 is a schematic diagram showing the state of ink adhesion at the discharge port shown in FIG. 13, and C represents an ink adhesion part.

Next, the operation of discharging the liquid by the ink jet recording head having the above-described configuration will be described with reference to FIGS.

FIGS. 16 to 23 are cross-sectional views for explaining the liquid discharging operation of the liquid discharging head shown in FIGS. 11 to 15, and are XX cross-sectional views of the foaming chamber 1337 shown in FIG. . In this cross section, the end of the discharge port 940 in the thickness direction of the orifice plate is the top 1141a of the groove 1141.

FIG. 16 shows a state in which film-like air bubbles have been generated on the heater. FIG. 17 is about 1 μs after FIG. 16, and FIG.
After about 2 μs from FIG. 19, FIG. 19 shows about 3 μs after FIG.
After about 4 μs of FIG. 21, FIG. 21 shows about 5 μs of FIG. 16, and FIG.
FIG. 23 shows the state about 7 μs after FIG. 16 and FIG. 23 respectively. In the following description, "fall" or "drop" does not mean "drop in the direction of gravity", and does not mean movement in the direction of the electrothermal transducer regardless of the mounting direction of the head. Say.

First, as shown in FIG. 16, when the air bubbles 101 are generated in the liquid flow path 1338 on the heater 931 due to energization to the heater 931 based on a recording signal or the like, the period shown in FIGS. As shown in FIG. 18, it grows by rapid volume expansion. The height of the bubble 101 at the maximum volume is higher than the discharge port surface 935a, but at this time, the pressure of the bubble is reduced from a fraction of atmospheric pressure to a fraction of atmospheric pressure.

Next, at about 2 μs after the generation of the bubble 101, the bubble 101 changes from the maximum volume to the volume reduction as described above, but almost simultaneously, the formation of the meniscus 102 starts. The meniscus 102 also recedes in the direction toward the heater 931 as shown in FIG. 19, that is, falls.

[0168] Here, in the present embodiment, by having dispersed a plurality of grooves 1141 in the discharge port portion, when the meniscus 102 is retracted, the meniscus retraction direction F _M at a portion of the groove 1141 capillary force acts in an opposite direction F _C.
As a result, even if some variation in the state of the bubble 101 is recognized for some reason, the shape of the meniscus and the main droplet (hereinafter, sometimes referred to as liquid or ink) Ia when the meniscus is retracted, The correction is made so as to be substantially symmetrical with respect to the center of the discharge port.

In this example, the meniscus 102
Is faster than the shrinking speed of bubble 101,
As shown in FIG. 20, at about 4 μs after the generation of bubbles, the bubbles 101 communicate with the atmosphere near the lower surface of the discharge port 832. At this time, the liquid (ink) near the central axis of the discharge port 832 falls toward the heater 931. This is because the liquid (ink) Ia pulled back to the heater 931 side by the negative pressure of the bubble 101 before communicating with the atmosphere keeps the velocity in the plane of the heater 931 due to inertia even after the bubble 101 communicates with the atmosphere. It is.

The liquid (ink) that has dropped toward the heater 931 reaches the surface of the heater 931 at about 5 μs after the generation of the bubble 101 as shown in FIG.
As shown in FIG. 22, the heater 931 spreads so as to cover the surface of the heater 931. The liquid spread so as to cover the surface of the heater 931 has a horizontal vector along the surface of the heater 931, but the vector that intersects the surface of the heater 931, for example, the vector in the vertical direction disappears and the heater 931 Attempts to remain on the surface and pull downward the liquid above it, that is, the liquid that maintains the velocity vector in the ejection direction.

Thereafter, the liquid portion Ib between the liquid spread on the surface of the heater 931 and the liquid on the upper side (main droplet) becomes thinner, and about 7 μs after the generation of the bubble 101, FIG.
As shown in (1), the liquid portion Ib is cut at the center of the surface of the heater 1 and separated into a main droplet Ia maintaining a velocity vector in the ejection direction and a liquid Ic spread on the surface of the heater 931. Thus, the separation position is desirably inside the liquid flow path 1338, more preferably on the electrothermal conversion element 931 side than the discharge port 832.

The main droplet Ia is ejected from the central portion of the ejection port 832 without deviation in the ejection direction and without being distorted, and lands at a predetermined position on the recording surface of the recording medium. Further, the liquid Ic spread on the surface of the heater 931 flies as a satellite droplet following the main droplet in the related art, but stays on the surface of the heater 931 and is not discharged.

As described above, since the ejection of the satellite droplets can be suppressed, the splash which is easily generated by the ejection of the satellite droplets can be prevented, and the recording surface of the recording medium becomes dirty by the mist floating in the mist. Can be reliably prevented. 20 to 23, Id represents ink attached to the groove (ink in the groove), and Ie represents ink remaining in the liquid flow path.

As described above, in the liquid ejection head of this example,
When the liquid is ejected at the volume reduction stage after the bubble has grown to the maximum volume, the direction of the main droplet at the time of ejection can be stabilized by the plurality of grooves dispersed with respect to the center of the ejection port. As a result, it is possible to provide a liquid ejection head with high landing accuracy, which has no deviation in the ejection direction. In addition, high-speed and high-definition printing can be realized because the ejection can be stably performed even with respect to foaming variation at a high driving frequency.

In particular, by discharging the liquid by starting the bubble and communicating with the atmosphere at the stage of reducing the volume of the bubble, it is possible to prevent mist generated when the bubble is discharged by connecting the bubble to the atmosphere. It is also possible to suppress a state in which droplets adhere to the ejection port surface, which is a cause of so-called sudden ejection failure.

As another embodiment of a recording head of a discharge system which can be suitably used in the present invention and which communicates bubbles with the atmosphere at the time of discharge, for example, as described in Japanese Patent No. 2783647, a so-called edge shooter type Is mentioned.

The present invention particularly provides an excellent effect in an ink jet recording head and a recording apparatus in which a flying liquid droplet is formed by utilizing thermal energy and recording is performed.

With respect to the typical structure and principle, it is preferable to use the basic principle disclosed in, for example, US Pat. Nos. 4,723,129 and 4,740,796. This method can be applied to both the so-called on-demand type and continuous type.In particular, in the case of the on-demand type, it is arranged corresponding to the sheet or liquid path holding the liquid (ink). By applying at least one drive signal corresponding to the recorded information and giving a rapid temperature rise exceeding the nucleate boiling to the electrothermal transducer, heat energy is generated in the electrothermal transducer,
This is effective because film boiling occurs on the heat-acting surface of the recording head, and as a result, bubbles in the liquid (ink) corresponding one-to-one with this drive signal can be formed. The liquid (ink) is ejected through the ejection opening by the growth and contraction of the bubble to form at least one droplet. When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of the liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable.

As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,434,262 are suitable. If the conditions described in the specification of US Pat. No. 4,313,124 relating to the temperature rise rate of the heat acting surface are adopted, more excellent recording can be performed.

As the configuration of the recording head, in addition to the combination of the discharge port, the liquid path, and the electrothermal converter (linear liquid flow path or right-angle liquid flow path) as disclosed in the above-mentioned respective specifications, U.S. Pat.No.4,558,333, U.S. Pat.
A configuration using the specification is also included in the present invention.

In addition, JP-A-59-123670 discloses a configuration in which a common slit is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters, and absorbs pressure waves of thermal energy. The present invention is also effective as a configuration based on JP-A-59-138461, which discloses a configuration in which the openings correspond to the discharge portions.

Further, as a full-line type recording head having a length corresponding to the width of the maximum recording medium that can be recorded by the recording apparatus, the length is determined by combining a plurality of recording heads as disclosed in the above specification. The present invention can exhibit the above-mentioned effects more effectively, though it may be either a configuration that satisfies the above requirements or a configuration as a single recording head that is formed integrally.

In addition, an exchangeable chip-type recording head that can be electrically connected to the apparatus main body and supplied with ink from the apparatus main body by being attached to the apparatus main body, or integrated with the recording head itself. The present invention is also effective when a cartridge type recording head provided with an ink tank is used.

It is preferable to add recovery means for the print head, preliminary auxiliary means, and the like provided as components of the printing apparatus of the present invention, since the effects of the present invention can be further stabilized. If you list these specifically,
Capping means, cleaning means, pressurizing or suction means for the recording head, preheating means using an electrothermal transducer or a heating element different from this or a combination thereof, and a preliminary ejection mode for performing ejection different from recording Is also effective for performing stable recording.

Further, the recording mode of the recording apparatus is not limited to the recording mode of only the mainstream color such as black, but may be a single recording head or a combination of plural recording heads. The present invention is also extremely effective for an apparatus provided with at least one of full colors by color mixture.

In the embodiments of the present invention described above,
Although the ink is described as a liquid, it is an ink that solidifies at or below room temperature, softens at room temperature, or is a liquid, or in the inkjet method described above, the ink itself is kept at 30 ° C or more and 70 ° C or less. Generally, the temperature is adjusted within the range and the temperature is controlled so that the viscosity of the ink is in the stable ejection range. Therefore, it is sufficient that the ink is in a liquid state when the use recording signal is applied.

In addition, the temperature rise due to thermal energy is positively prevented by using it as energy for changing the state of the ink from the solid state to the liquid state, or the ink is solidified in a standing state to prevent evaporation of the ink. Either ink may be used, or in any case, the ink may be liquefied by application of heat energy according to the recording signal and ejected as a liquid ink, or may already start to solidify when reaching the recording medium. The use of ink having a property of being liquefied for the first time by heat energy is also applicable to the present invention. In such a case, as described in JP-A-54-56847 or JP-A-60-71260, the ink is held as a liquid or solid in a porous sheet recess or through hole, It is good also as a form which opposes an electrothermal transducer. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

In addition to the above, the recording device according to the present invention may be provided as an image output terminal of an information processing device such as a word processor or a computer as an integral or separate device, a copying device combined with a reader, and A facsimile apparatus having a transmission / reception function may be employed.

Next, an outline of a liquid ejection apparatus equipped with the above-described liquid ejection head will be described.

FIG. 29 is a schematic perspective view of an ink jet recording apparatus 600 which is an example of a liquid discharge apparatus to which the liquid discharge head of the present invention can be mounted.

Referring to FIG. 29, an ink jet head cartridge 601 has the above-described liquid discharge head and an ink tank for holding ink to be supplied to the liquid discharge head integrated with each other. The inkjet head cartridge 601 is mounted on a carriage 607 that engages with a spiral groove 606 of a lead screw 605 that rotates via driving force transmission gears 603 and 604 in conjunction with forward and reverse rotation of a driving motor 602. Then, it is reciprocated in the directions of arrows a and b along the guide 608 together with the carriage 607 by the power of the drive motor 602. The recording material P ′ is transferred to a platen roller 609 by a recording material conveying unit (not shown).
Conveyed above, and the carriage 607
Is pressed against the platen roller 609 in the moving direction of the roller.

In the vicinity of one end of the lead screw 605,
Photocouplers 611 and 612 are provided. These are home position detecting means for confirming the presence of the lever 607a of the carriage 607 in this area and switching the rotation direction of the drive motor 602 and the like.

The support member 613 supports a cap member 614 that covers the front surface (discharge port surface) of the above-described ink jet head cartridge 601 having the discharge port. Further, the ink suction means 615 is for sucking the ink that has been collected from the ink jet head cartridge 601 due to idle discharge or the like inside the cap member 614. The ink suction unit 615 performs suction recovery of the ink jet head cartridge 601 through an opening (not shown) in the cap. Inkjet head cartridge
The cleaning blade 617 for wiping the discharge port surface of the 601 is provided so as to be movable in the front-rear direction (the direction perpendicular to the moving direction of the carriage 607) by the moving member 618. The cleaning blade 617 and the moving member 618 are supported by the main body support 619. The cleaning blade 617 is not limited to this form, and may be another known cleaning blade.

In the suction recovery operation of the liquid discharge head, the lever 620 for starting suction moves with the movement of the cam 621 engaging with the carriage 607, and the driving force from the drive motor 602 changes the clutch or the like. The movement is controlled by a known transmission means. An ink jet recording control unit that gives a signal to a heating element provided in the liquid ejection head of the ink jet head cartridge 601 and controls the driving of each mechanism described above is provided on the apparatus main body side. Not shown.

In the ink jet recording apparatus 600 having the above structure, the recording material P 'conveyed on the platen roller 609 by the recording material conveying means (not shown), while the ink jet head cartridge 601 uses the full width of the recording material P' The recording is performed while reciprocating over.

[0196]

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 “%” are based on mass unless otherwise specified.

(Preparation of Pigment Dispersion) [Pigment Dispersion A] 1.58 g of anthranilic acid was added at 5 ° C. to a solution prepared by dissolving 5 g of concentrated hydrochloric acid in 5.3 g of water. To this, a solution obtained by adding 1.78 g of sodium nitrite to 8.7 g of water at 5 ° C. was added while constantly being kept at 10 ° C. or lower by stirring in an ice bath.

After stirring for 15 minutes, the surface area was 220 m.
7 g of carbon black having a DBP oil absorption of 105 mL / 100 g at ² / g was added in a mixed state. Thereafter, the mixture was further stirred for 15 minutes. The obtained slurry was filtered through Toyo Filter Paper No. 2 (manufactured by Advantis), and the pigment particles were sufficiently washed with water.
After drying in an oven at ℃, water was added to the pigment to prepare an aqueous pigment solution having a pigment concentration of 10% by mass.

Incidentally, the hydrophilic group density of the self-dispersible carbon black produced as described above was measured as follows, and it was 2.6 μmol / m ² . As a measuring method, a sodium ion concentration was measured using an ion meter (manufactured by DKK), and a hydrophilic group density was converted from the measured value. Then, by replacing sodium ions with ammonium ions using the ion exchange method,
Pigment dispersion A in which self-dispersion type carbon black into which -Ph-COONH ₄ groups were introduced was dispersed.

[Pigment Dispersion B] To a solution of 5 g of concentrated hydrochloric acid in 5.3 g of water, 1.58 g of anthranilic acid was added at 5 ° C. To this, always stir in an ice bath
1.78g in 8.7g of water at 5 ℃ while keeping it below 10 ℃
Of sodium nitrite was added.

After stirring for 15 minutes, the surface area was 220 m.
8 g of carbon black having a DBP oil absorption of 105 mL / 100 g at a rate of ² / g was added in a mixed state. Thereafter, the mixture was further stirred for 15 minutes. The obtained slurry was filtered through Toyo Filter Paper No. 2 (manufactured by Advantis), and the pigment particles were sufficiently washed with water.
After drying in an oven at ℃, water was added to the pigment to prepare an aqueous pigment solution having a pigment concentration of 10% by mass.

When the density of the hydrophilic group of the self-dispersible carbon black prepared above was measured in the same manner as described above,
1.6 μmol / m ² . Then, by replacing sodium ions with ammonium ions using an ion exchange method, -Ph-COONH
Pigment dispersion liquid B in which self-dispersible carbon black into which _four groups were introduced was dispersed was obtained.

Example 1 The following components were mixed, sufficiently stirred and dissolved, and then a microfilter having a pore size of 3.0 μm was obtained.
(Fuji Film Co., Ltd.), and filtered under pressure to prepare the ink of the present invention.

Pigment Dispersion A 45 parts Trimethylolpropane 6 parts Glycerin 6 parts Diethylene glycol 6 parts Acetylene glycol ethylene oxide adduct (trade name: acetylenol EH) 0.2 parts Potassium hydroxide 0.06 parts Water 36.74 parts <Example 2> The following components were mixed, sufficiently stirred and dissolved, and filtered under pressure through a 3.0 μm pore size microfilter (manufactured by Fuji Film) to prepare an ink of the present invention.

Pigment Dispersion A 45 parts Potassium benzoate 1.7 parts Trimethylolpropane 6 parts Glycerin 6 parts Diethylene glycol 6 parts Acetylene glycol ethylene oxide adduct (trade name: acetylenol EH) 0.2 parts Water 35.1 parts <Example 3> The following components were mixed, sufficiently stirred and dissolved, and filtered under pressure through a 3.0 μm pore size microfilter (manufactured by Fuji Film) to prepare an ink of the present invention.

Pigment dispersion B 45 parts Potassium benzoate 1.7 parts Trimethylolpropane 6 parts Glycerin 6 parts Diethylene glycol 6 parts Acetylene glycol ethylene oxide adduct (trade name: acetylenol EH) 0.2 parts Water 35.1 parts <Example 4> The following components were mixed, sufficiently stirred and dissolved, and then pressure-filtered with a micro filter having a pore size of 3.0 μm (manufactured by Fuji Film) to prepare an ink of the present invention.

The above-mentioned pigment dispersion A 45 parts Ammonium benzoate 0.7 parts Potassium benzoate 0.9 parts Trimethylolpropane 6 parts Glycerin 6 parts Diethylene glycol 6 parts Acetylene glycol ethylene oxide adduct (trade name: acetylenol EH) 0.2 parts Water 35.2 parts Example 5 The following components were mixed, sufficiently stirred and dissolved, and filtered under pressure through a micro filter (manufactured by Fuji Film) having a pore size of 3.0 μm to prepare an ink of the present invention.

Pigment Dispersion A 45 parts Ammonium benzoate 1.5 parts Trimethylolpropane 6 parts Glycerin 6 parts Diethylene glycol 6 parts Acetylene glycol ethylene oxide adduct (trade name: acetylenol EH) 0.2 parts Potassium hydroxide 0.06 parts Water 35.24 parts <Comparative Example 1> The following components were mixed, sufficiently stirred and dissolved, and then subjected to pressure filtration with a micro filter having a pore size of 3.0 µm (manufactured by Fuji Film) to prepare an ink of the present invention.

Pigment Dispersion A 45 parts Trimethylolpropane 6 parts Glycerin 6 parts Diethylene glycol 6 parts Acetylene glycol ethylene oxide adduct (trade name: acetylenol EH) 0.2 parts Ammonia water (28%) 0.06 parts Water 36.74 parts <Comparison Example 2> The following components were mixed, sufficiently stirred and dissolved, and then subjected to pressure filtration with a micro filter having a pore size of 3.0 μm (manufactured by Fuji Film) to prepare an ink of the present invention.

Pigment Dispersion A 45 parts Lithium benzoate 1.4 parts Trimethylolpropane 6 parts Glycerin 6 parts Diethylene glycol 6 parts Acetylene glycol ethylene oxide adduct (trade name: acetylenol EH) 0.2 parts Water 35.4 parts <Comparative Example 3> The following components were mixed, sufficiently stirred and dissolved, and then pressure-filtered with a micro filter having a pore size of 3.0 μm (manufactured by Fuji Film) to prepare an ink of the present invention.

Pigment dispersion B 45 parts Lithium benzoate 1.4 parts Trimethylolpropane 6 parts Glycerin 6 parts Diethylene glycol 6 parts Acetylene glycol ethylene oxide adduct (trade name: acetylenol EH) 0.2 parts Water 35.4 parts <Comparative Example 4> The following components were mixed, sufficiently stirred and dissolved, and then pressure-filtered with a micro filter having a pore size of 3.0 μm (manufactured by Fuji Film) to prepare an ink of the present invention.

Pigment Dispersion A 45 parts Ammonium benzoate 1.5 parts Trimethylolpropane 6 parts Glycerin 6 parts Diethylene glycol 6 parts Acetylene glycol ethylene oxide adduct (trade name: acetylenol EH) 0.2 parts Water 35.3 parts The main characteristics of the black inks of Examples 1 to 5 and Comparative Examples 1 to 4 are shown in Table 1 below.

[0211]

[Table 1]

Ink-jet recording having an on-demand type multi-recording head for discharging ink by applying thermal energy according to a recording signal to the ink using the inks of Examples 1 to 5 and Comparative Examples 1 to 4 described above. Device B
The following evaluation was performed using JF-850 (manufactured by Canon) without any modification.

1) Intermittent Ejectivity Using each of the above inks and the above ink jet recording apparatus, A
After printing one sheet of four sheets (210 mm x 297 mm, JIS P0138-1961), ejection was not performed for 2 hours, and then a cycle of printing one sheet of A4 paper was repeated 50 times. The intermittent ejection property of each of the above inks was evaluated from the degree of printing disorder at that time.

2) Stickiness Using the above-mentioned inks and the above-mentioned ink jet recording apparatus, after initial printing was performed, ejection was not performed for 72 hours, and thereafter printing was performed again. The sticking property of each of the above inks was evaluated from the number of recovery operations of the recording device required to recover the printing after the ejection for 72 hours to the initial printing state.

As a result of the above evaluation, both the intermittent ejection property and the fixability of the ink of Example 1 were clearly improved as compared with the ink of Comparative Example 1. In addition, the ink of Example 2 also clearly improved the intermittent ejection property and the fixability as compared with the ink of Comparative Example 2. As for the ink of Example 3, the intermittent ejection property and the fixability were improved as compared with the ink of Comparative Example 3. The inks of Example 4 and Example 5 clearly improved the intermittent ejection property and the fixability as compared with the ink of Comparative Example 4.

[0216]

According to the present invention, when printing with black ink during ink jet recording, the print density of the printed matter is high, the ink is an aqueous pigment ink excellent in intermittent ejection properties and fixability, and the ink jet ink using the ink is used. A recording method and an ink jet recording apparatus have been provided.

[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.

FIG. 8 is a cross-sectional view in which an example of a method for manufacturing an ink jet recording head is arranged in the order of steps.

FIG. 9 is a schematic perspective view illustrating a main part of an example of an inkjet printer on which a liquid discharge head can be mounted.

FIG. 10 is a schematic perspective view showing an example of an ink jet cartridge provided with a liquid ejection head.

FIG. 11 is a schematic perspective view schematically showing a main part of an example of a liquid ejection head.

FIG. 12 is a conceptual diagram in which a part of an example of a liquid ejection head is extracted.

FIG. 13 is an enlarged view of a discharge port shown in FIG.

FIG. 14 is a schematic view showing the state of ink adhesion at the ejection port shown in FIG.

FIG. 15 is a schematic diagram of a main part in FIG.

FIG. 16 corresponds to the XY perspective cross-sectional shape in FIG.
FIG. 24 is a schematic cross-sectional view for explaining the liquid discharging operation of the liquid discharging head with time along with FIGS.

17 corresponds to the XY perspective cross-sectional shape in FIG.
FIG. 26 is a schematic cross-sectional view for explaining the liquid discharging operation of the liquid discharging head with time along with FIG. 6 and FIGS.

18 corresponds to the XY perspective cross-sectional shape in FIG.
FIG. 26 is a schematic cross-sectional view for explaining the liquid discharging operation of the liquid discharging head with time, together with FIG. 6, FIG. 17 and FIGS.

19 corresponds to the XY perspective cross-sectional shape in FIG.
FIG. 24 is a schematic cross-sectional view for explaining the liquid discharging operation of the liquid discharging head with time along with FIGS. 6 to 18 and FIGS.

20 corresponds to the XY perspective cross-sectional shape in FIG.
FIG. 24 is a schematic cross-sectional view for explaining the liquid discharging operation of the liquid discharging head with time along with FIGS. 6 to 19 and FIGS.

21 corresponds to the XY perspective cross-sectional shape in FIG.
FIG. 26 is a schematic cross-sectional view for explaining the liquid discharging operation of the liquid discharging head with time along with FIGS. 6 to 20 and FIGS.

FIG. 22 corresponds to the XY perspective cross-sectional shape in FIG.
FIG. 24 is a schematic cross-sectional view for explaining the liquid discharging operation of the liquid discharging head with time, along with FIGS. 6 to 21 and 23.

FIG. 23 corresponds to the XY perspective cross-sectional shape in FIG.
FIG. 23 is a schematic cross-sectional view for explaining the liquid discharging operation of the liquid discharging head with time along with FIGS. 6 to 22.

FIG. 24 is a first example of a schematic cross-sectional view for explaining a head having a configuration that easily exerts the effects of the present invention.

FIG. 25 is a second example of a schematic cross-sectional view for explaining a head having a configuration that easily exerts the effects of the present invention.

FIG. 26 is a third example of a schematic cross-sectional view for explaining a head having a configuration easily exhibiting the effects of the present invention.

FIG. 27 is a schematic diagram for explaining a mechanism exhibiting the effects of the present invention.

FIG. 28 is a conceptual diagram for explaining the difference in the hydration of sodium ions and the like and potassium ions.

FIG. 29 is a schematic perspective view of an ink jet recording apparatus 600 as an example of a liquid ejection apparatus to which the liquid ejection head of the present invention can be mounted and applied.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Substrate 2 Ink ejection energy generating element 3 Opening 4 Soluble resin layer 5 Coating resin layer 6 Mask 7 Ink supply member 8 Ink ejection port 9 Ink flow path 13 Head 14 Ink groove 15 Heat generating element substrate 16 Protection layer 17-1 , 17-2 Electrode 18 Heating resistor layer 19 Thermal storage layer 20 Substrate 21 Ink 22 Discharge orifice (micro hole) 23 Meniscus 24 Ink droplet 25 Recording material 26 Multi nozzle 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 72 Air communication Port 80 Ink flow path 81 Orifice plate 82 Vibrating plate 83 Piezoelectric element 84 Substrate 85 Discharge port 251 Discharge energy generating element 252 Discharge port 253 Supply port 254 Substrate 255 Discharge port plate 261 Coating resin layer 262 Discharge energy generating element 263 Projection 600 Inkjet recording device 601 Inkjet head cartridge 602 Drive motor 603, 604 Driving force transmission gear 605 Lead screw 606 Spiral groove 607 Carriage 607a Lever 608 Guide 609 Platen roller 610 Paper press plate 611, 612 Photocoupler 613 Support member 614 Cap member 615 Ink suction means 616 Opening inside cap 617 Cleaning blade 618 Moving member 619 Main body support 620 (Suction start) lever 621 Cam 832: Discharge port 832a : Raised part 832b: Depressed part 931: Electrothermal conversion element (heater, ink discharge energy generating element) 933: Ink supply port (opening) 934: Substrate 935: Orifice plate (discharge port plate) 935a: Discharge port surface 936: Ink flow path wall 936a: Partition wall 940: Discharge port 1337: Bubble chamber 1338: Liquid flow path 1141: Groove 1141a: Top 100: Inkjet printing Recording head 101: Bubbles 102: Meniscus 1001: Liquid tank 1006: Movement drive unit 1008: Casing 1010: Recording unit 1010a: Carriage member 1012: Cartridge 1012Y, M, C, B: Inkjet cartridge 1016: Belt 1018: Motor 1020: Drive Unit 1022a, 1022b: Roller unit 1024a, 1024b: Roller unit 1026: Recovery unit 1026a, 1026b: Pulley 1028: Paper 1030: Transport device 2701: Carbon black 2703: Water molecule 2705: Counter ion 2707: Potassium ion 2709: Sodium ion C : Wet ink F _M : Meniscus retreat direction F _C : Opposite to meniscus retreat direction G: Center of gravity I: Ink Ia: Main droplet (liquid, ink) Ib, Ic: Liquid (ink) Id: Ink attached to groove ( ink) Ie in the grooves: ink remaining in the liquid flow path L: liquid chamber (lines N ₁ toward the discharge port from the ink supply port): the width of the bubbling chamber dimensions N _2: bubbling chamber length O : Discharge port Center P ': the recording material P: sheet conveying direction R: rotation direction of the belt S: Direction T ₁ substantially orthogonal to the conveying direction of the paper: the discharge port saphenous section dimensions w: width of the partition wall

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09C 1/56 C09C 3/08 3/06 B41J 3/04 101Y 3/08 103B (72) Inventor Shinya Shinya 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term (reference) in Canon Inc. CA10 CB09 EE02 EE19 EE46 FF15 4J039 BA04 BE01 CA06 EA41 EA42 EA44 GA24

Claims (49)

[Claims] 1. A color material comprising at least a self-dispersible carbon black having at least one hydrophilic group bonded directly or through another atomic group to the surface of the carbon black, and an aqueous medium, An ink comprising 0.6% or more of potassium ions in a mass ratio to black. 2. The ink according to claim 1, wherein the hydrophilic group is at least one selected from the following. _{-COOM, -SO 3 M, -PO 3} HM, -PO 3 M 2 ( representing where, M in the formula is a hydrogen atom, an alkali metal, ammonium or organic ammonium.) 3. The ink according to claim 1, wherein the potassium ion is present as a counter for a hydrophilic group of the carbon black. 4. The ink according to claim 1, wherein the potassium ion is derived from potassium hydroxide. 5. The ink according to claim 1, wherein the pH of the ink is 7 or more and 10 or less. 6. The ink according to claim 1, wherein the density of the hydrophilic group is 1.8 μmol / m ² or more. 7. The ink according to claim 1, wherein the total amount of monovalent cation ions in the ink is from 0.05 mol / L to 1 mol / L.
6. The ink according to any of 6. 8. The ink according to claim 7, wherein the monovalent cation ion contains at least one selected from an alkali metal ion, an ammonium ion and an organic ammonium ion together with a potassium ion. 9. The content of the monovalent cation ion is 0.1 mol / L or more and 0.5 mol / L based on the total amount of the aqueous pigment ink.
The ink according to claim 7, wherein: 10. The ink according to claim 1, wherein the ink is an ink jet ink. 11. An image recording method comprising the steps of: applying energy to ink, discharging the ink from a recording head, and attaching the ink to a recording medium.
An image recording method, characterized by being the ink described in (1). 12. The image recording method according to claim 11, wherein a recording head having an ejection amount per dot of 40 ng or less is used. 13. The image recording method according to claim 11, wherein the recording head is a recording head having a portion in the ink flow path where the flow path resistance changes greatly. 14. The image recording method according to claim 11, wherein said energy is heat energy. 15. The image recording method according to claim 14, wherein the thermal energy is applied by a heater disposed in an ink flow path. 16. The image recording method according to claim 15, wherein the heater is directly opposed to the ink ejection port. 17. The recording head according to claim 14, wherein a main flow direction of the ink changes by at least 90 ° until the ink reaches a part in contact with the heater.
The image recording method according to any one of the above. 18. The image recording method according to claim 11, wherein said energy is mechanical energy. 19. The recording medium according to claim 11, wherein said recording medium is plain paper.
19. The image recording method according to any one of claims 18 to 18. 20. A recording unit, comprising: an ink containing section containing ink; and a recording head for applying energy to the ink to eject the ink as ink droplets. A recording unit, which is the ink described in any one of the above. 21. The recording head according to claim 20, wherein the ejection amount per dot is 40 ng or less.
A recording unit according to item 1. 22. The recording unit according to claim 20, wherein the recording head is a recording head having a portion in the ink flow path where the flow resistance of the ink greatly changes. 23. The recording unit according to claim 20, wherein the energy is heat energy. 24. The recording unit according to claim 23, wherein said thermal energy is applied by a heater disposed in an ink flow path. 25. The recording unit according to claim 24, wherein the heater faces the ink ejection port. 26. The recording head according to claim 23, wherein a main flow direction of the ink changes by at least 90 ° until the ink reaches a part in contact with the heater.
The recording unit according to any one of the above. 27. An ink cartridge comprising an ink containing section containing ink, wherein the ink is the ink according to claim 1. Description: 28. An image recording apparatus comprising: a recording unit having an ink containing section containing ink and a recording head for ejecting the ink as ink droplets by the action of energy. An image recording apparatus comprising the ink according to claim 10. 29. An image 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 energy. An image recording apparatus comprising the ink according to claim 10. 30. The image recording apparatus according to claim 29, further comprising an ink supply unit that supplies the ink contained in the ink cartridge to the recording head. 31. The recording head according to claim 28, wherein the ejection amount per dot is 40 ng or less.
30. The image recording apparatus according to any one of claims 30 to 30. 32. The image recording apparatus according to claim 28, wherein the recording head is a recording head having a portion in the ink flow path where the flow resistance of the ink greatly changes. 33. The image recording apparatus according to claim 28, wherein said energy is heat energy. 34. The image recording apparatus according to claim 33, wherein the thermal energy is applied by a heater disposed in an ink flow path. 35. The image recording apparatus according to claim 34, wherein the heater is directly opposed to the ink ejection port. 36. The image recording apparatus according to claim 34, wherein the recording head has a portion where the main flow direction of the ink changes by at least 90 ° until the ink reaches a portion in contact with the heater. 37. A method for alleviating sticking of a print head, comprising using the ink according to claim 10 when applying energy to the ink to discharge the ink from the print head. 38. Cyan, magenta, yellow,
An ink containing at least one color material selected from red, green and blue color materials, and an ink containing at least one color material.
An ink set comprising a combination with the ink described in any one of the above. 39. Hydration of the hydrophilic group while having a self-dispersible pigment having a hydrophilic group as a coloring material and having a counter ion to the hydrophilic group and a counter ion other than the counter ion and having the opposite polarity to the hydrophilic group. An ink having ions having a hydration power lower than the power. 40. A hydration of the hydrophilic group while having a self-dispersible pigment having a hydrophilic group as a coloring material and having a counter ion to the hydrophilic group and a counter ion other than the counter ion while having the opposite polarity to the hydrophilic group. A recording head comprising an ink having ions having a hydration power lower than the power. 41. A self-dispersible pigment having a hydrophilic group as a coloring material, and a counter ion to the hydrophilic group and hydration of the hydrophilic group while being in a polarity opposite to that of the hydrophilic group other than the counter ion. An ink tank containing ink having ions having a hydration power lower than the power of the ink. 42. An ink-jet ink comprising a self-dispersible carbon black, a salt and an aqueous medium, wherein at least one hydrophilic group is bonded directly or via another atomic group to the surface of the carbon black, The ink is
An ink-jet ink characterized in that the self-dispersion type carbon black maintains a stable dispersion state even when the flow state of the ink in the recording head becomes a turbulent state or a disturbed state. 43. A method for alleviating sticking of a recording head in an ink jet recording method including a step of discharging ink using an ink jet recording head having an ink discharge port at a position facing an ink discharge pressure generating element. A method for alleviating sticking, wherein the ink according to claim 10 is used as the ink. 44. A method for alleviating sticking of a recording head in an ink jet recording method including a step of discharging ink using an ink jet recording head having a portion in which a flow path resistance of a liquid greatly changes in an ink flow path. A method for alleviating sticking, wherein the ink according to claim 10 is used as the ink. 45. The method according to claim 44, wherein the portion where the flow resistance of the liquid greatly changes is a portion where the flow direction of the liquid changes by 90 ° or more. 46. A method for improving the intermittent ejection property in an ink jet recording method, comprising a step of applying energy to the ink and discharging the ink from a recording head by an ink jet method at predetermined time intervals. A method for improving intermittent ejection, comprising using the ink according to claim 10. 47. Using a recording head for discharging ink in a direction facing the ink discharge pressure generating element,
A method for improving intermittent ejection in an inkjet recording method including a step of ejecting a plurality of times at predetermined intervals, wherein the ink according to claim 10 is used as the ink. 48. An intermittent ejection property in an ink jet recording method including a step of ejecting ink a plurality of times at predetermined time intervals using a recording head having a portion in the ink flow path where the flow path resistance of the liquid greatly changes. A method for improving intermittent ejection characteristics, wherein the ink according to claim 10 is used as the ink. 49. The method for improving intermittent ejection according to claim 48, wherein the portion where the flow resistance of the liquid greatly changes is a portion where the flow direction of the liquid changes by 90 ° or more.