JP2001164160A - Ink set for color inkjet recording, inkjet recording method, recording unit, ink cartridge, inkjet recording apparatus, and bleeding mitigation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a print image having high print density and good print quality, and to form a color image without causing bleeding between a black ink and a color ink, and an inkjet method. Provided is an ink set for color inkjet recording that can ensure the reliability as a printing ink. SOLUTION: In an ink jet recording ink set for recording a color image on a recording material using two or more inks including a black ink and a color ink, the black ink is a cationic self-dispersible carbon. An ink set for color inkjet recording, which has black black and the color ink contains an anionic dye and another anionic substance, an inkjet recording method, recording equipment, an inkjet recording apparatus, and a bleeding mitigation method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink set for color ink jet recording, in which a clear and high quality color image can be obtained with good density and quality even on plain paper in image recording by an ink jet recording method. The present invention relates to an ink jet recording method, a recording unit, an ink cartridge, an ink jet recording apparatus, and a method for alleviating bleeding.

[0002]

2. Description of the Related Art Conventionally, pigments have been used in ink-jet recording in order to form black images excellent in fastness, such as print density, print quality, water resistance and light resistance, especially on plain paper. Black ink has been proposed.
Also, an ink set that does not cause bleeding between different colors (hereinafter, referred to as bleed) at a boundary between an image printed with adjacent black ink and an image printed with color ink, an ink jet recording method using the same, Equipment has been reported. For example, JP-A-7-145336 discloses that at least one ink is an anionic ink containing a polymer, and the ink and the cationic ink are brought into contact with each other on a multicolor printing element to reduce bleed. An ink set that can be reduced is described. JP-A-10-183046 discloses that a carbon black pigment having a cationic group on its surface is used as a coloring material, and the black ink is combined with a color ink using an anionic dye as a coloring material. This describes an ink set that can reduce the occurrence of bleed.

[0003] However, Japanese Patent Laid-Open No.
No. 6, in the case of a method of reducing bleed by bringing an anionic ink and a cationic ink into contact with each other in the presence of a polymer during multicolor printing, depending on the type of polymer to be contained. May adversely affect the reliability of the ink. Especially during printing,
After the ink is ejected from a certain nozzle, if the ink is not ejected from the nozzle for a certain period of time (for example, about 1 minute), the ink becomes stable when the next first ink is ejected from the nozzle. Discharge could not be performed, and printing would be disturbed (this state is hereinafter referred to as poor singularity), and there were cases where there was a problem in the reliability of the inkjet ink.

Further, a combination of a black ink using a cationic carbon black and a color ink using an anionic dye described in the above-mentioned Japanese Patent Application Laid-Open No. Hei 10-183046 is used to combine a cationic coloring material with an anionic dye. In the case of the method of reducing bleed by agglomeration with the color material, the agglutination reaction is caused using the color material contained in each ink, but the color material concentration in the ink is not so high for inkjet In the case of ink, the cohesive force is not sufficient, and if black ink and color ink are printed by the same scan, the bleeding between black and color, especially on a highly permeable paper such as so-called plain paper, is performed. Black ink is generated inside the recording medium due to the high permeability of the color ink at the boundary between the black image and the color image. By being retracted, a phenomenon that the image should be originally black becomes whitish (hereinafter referred to as "white also Ya") is observed.

[0005]

SUMMARY OF THE INVENTION The present inventors have studied a black ink containing a self-dispersion type carbon black as a coloring material as a black ink which gives a high-quality black image and is stable as an ink composition. In the course of the process, the present inventors also examined the formation of a multicolor image using this black ink, and found that a high-quality multicolor image can be obtained due to the excellent characteristics of the black ink. However, they have come to the knowledge that it is necessary to control the bleed in the boundary region between the black image and the color image in order to achieve higher quality of the multi-color image. The technical knowledge of using black ink containing self-dispersion type carbon black as a colorant for forming multi-color images has not yet been fully obtained, and the bleed prevention technology is still a definitive technology. At present, it has not been found.

SUMMARY OF THE INVENTION The present invention has been made in view of the above background, and an object of the present invention is to provide a bleeding image in a boundary region between black ink and color ink when a high density image is formed and a color image is formed. An object of the present invention is to provide a color ink jet recording ink set which can suppress the ink jet recording and can further secure the reliability as an ink jet ink. Another object of the present invention is to provide an ink jet recording method capable of forming a color image having high image density and excellent quality. Still another object of the present invention is to provide an ink jet recording apparatus capable of forming a high-quality color image, and an ink cartridge and a recording unit that can be used in the apparatus. An object of the present invention is to provide a recording device and an inkjet recording device. Furthermore, the present invention provides a bleeding in a boundary region between a black inkjet image and a color inkjet image,
An object of the present invention is to provide a bleeding mitigation method capable of stably and sufficiently mitigation.

[0007]

An ink set for ink jet recording according to an embodiment of the present invention, which can achieve the above object, uses at least two colors of ink including at least a black ink and a color ink. An ink jet recording ink set for recording a color image on a recording material, wherein the black ink has a cationic self-dispersion type carbon black, and the color ink has an anionic dye and It is characterized by having another anionic substance.

Further, the ink jet recording method according to one embodiment of the present invention, which can achieve the above object, comprises:
Discharging a black ink containing a cationic self-dispersible carbon black from an orifice according to a recording signal; and discharging a color ink containing an anionic dye according to a recording signal. In the ink jet recording method, a color ink further containing an anionic substance is used as the color ink. In addition, an ink jet recording apparatus according to an embodiment of the present invention that can achieve the above object has a first ink containing section containing a black ink containing a cationic self-dispersion type carbon black, A second containing a color ink containing an anionic colorant and another anionic substance;
, And a head unit for discharging the black ink and the color ink, respectively.

A recording unit according to an embodiment of the present invention, which can achieve the above object, has a first ink containing black ink containing cationic self-dispersion type carbon black. , A second ink containing section containing a color ink containing an anionic dye and another anionic substance, and a black ink contained in the first ink containing section and the second ink containing section. And a head for ejecting each of the color inks stored in the second ink storage section. An ink cartridge according to one embodiment of the present invention that can achieve the above object has a first ink containing section containing black ink containing cationic self-dispersible carbon black, and And a second ink containing section containing a color ink containing an anionic coloring material and another anionic substance.

Further, the bleeding mitigation method according to one embodiment of the present invention, which can achieve the above object, is a method for reducing a boundary area between a black image formed by an ink jet recording method and a color image formed by an ink jet recording method. Wherein the black image is formed with a black ink containing cationic self-dispersion type carbon black, and the color image is formed with an anionic coloring material and another anionic substance. And a color ink containing the following.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to preferred embodiments of the present invention. The present inventors have conducted intensive studies to solve the above-mentioned conventional technology, and as a result, while taking advantage of the use of carbon black as a pigment as a coloring material, solve the problem of the pigment ink, and further, When such a black pigment ink is used for multicolor printing, a technique capable of extremely effectively preventing occurrence of bleeding with the color ink has been found, and the present invention has been achieved.

First, in the ink set according to the present invention, a black ink using a cationic self-dispersion type carbon black as a coloring material is used. As mentioned earlier,
To ensure high image density and perfect image robustness,
It is advantageous to use pigment inks rather than dye inks. For this reason, various inks using carbon black as a coloring material as a coloring material have been developed as black inks used for inkjet recording. However, when such a pigment is used as a coloring material of an ink, some dispersant must be added in order to disperse the pigment in the ink. was there. For example, when a polymer type dispersant is used, the face surface of the head portion may be easily wetted, clogged, or may have poor storage stability.
Further, when a surfactant is used as a dispersant, problems such as low print density and easy wetting of the face surface may occur. On the other hand, if so-called self-dispersion type carbon black is used, the problem caused by the above-mentioned dispersant does not occur.

The following are conceivable reasons for this. As described above, when a pigment such as carbon black that has not been subjected to a surface treatment is used as a coloring material of an ink, a dispersant is required to maintain the dispersion stability of the pigment, and the dispersant is contained in the ink. Nevertheless, there is still a problem with the storage stability of the ink, and the presence of the dispersant makes it easier for the ink to wet the face of the head of the ink jet recording apparatus. It may be damaged. However, in the self-dispersion type carbon black, since the surface of the carbon black has a hydrophilic group, the carbon black itself shows a stable dispersibility in an aqueous medium such as water, even if the dispersant is not particularly contained. Since the carbon black itself is self-dispersed and kept in a dispersed state, it is possible to obtain a pigment ink free from the conventional problems caused by the dispersant.

Further, in the ink set according to the present invention, a color ink is used in combination with the black ink having the above-described structure. However, the color material of the color ink currently used for forming a color image has a color developing property and a light fastness. Anionic coloring materials are often used from the viewpoint of safety and safety. Therefore, in order to suppress the bleeding of the image formed by the black ink and the color ink,
It is desirable to use a cationic coloring material for the black ink. Therefore, in the present invention, cationic self-dispersion type carbon black is used as a coloring material of the black ink. As a result, the image density, robustness and print quality of the black ink image can be improved, and the storage stability of the ink and the reliability during inkjet recording (discharge durability) despite being a pigment ink , Discharge stability, clogging resistance, etc.)
Can be satisfied.

In the ink set according to the present invention,
A color ink having an anionic dye and at least one anionic substance is used in combination with the black ink having the above configuration. As a result, the cohesive force when the black ink and the color ink come into contact with each other on the paper surface can be increased, and as a result, the bleeding generated between the adjacent black ink image and the color ink image can be more effectively performed. It can be suppressed.

The anionic substance used at this time is preferably, for example, a substance having a carboxyl group or a sulfone group, and more preferably a substance having a plurality of sulfone groups. In particular, it is preferable to use a substance in which an aromatic ring is substituted with a sulfone group, more preferably, a substance in which an aromatic ring is substituted with a plurality of sulfone groups. It is considered that the reason for this is that the aggregation of the sulfone group to the cationic group is stronger. Furthermore, by using a substance having a plurality of sulfone groups, the cohesive force with the cationic group can be further increased, and as a result, even when the black ink and the color ink are printed by the same scan, the bleeding suppressing effect is reduced. It is thought that it can be improved. Further, in the present invention, it is preferable to similarly use a dye having a sulfone group as the anionic dye in the color ink.

As described above, the ink set according to the present invention aims at suppressing bleeding occurring between adjacent black ink images and color ink images. Has no particular treatment. However, since color inks are often used in images, graphs, and the like, when preparing color inks, a practical method such as giving a quick penetration to sized paper is used. It is preferable that the print quality is not significantly reduced.

Hereinafter, a black ink containing a cationic self-dispersible carbon black as a coloring material, an anionic dye, and at least one anionic substance, which constitute an ink set according to an embodiment of the present invention, will be described. Will be described for each ink.
As a more preferable form of the ink set for ink jet recording of the present invention, the anionic substance in the color ink is a substance containing a carboxyl group, and further, an anionic substance containing a sulfone group.

First, the black ink constituting the ink set according to the present invention will be described. The black ink used in the present invention is characterized by containing a cationic self-dispersion type carbon black, and the cationic self-dispersion type carbon black may be an existing one or a newly synthesized one. But you can use most things.

Examples of the cationic self-dispersion type carbon black include self-dispersion type carbon black in which at least one kind of cationic hydrophilic group is bonded directly or via another atomic group to the surface of carbon black. Can be used. As described above, by using such a self-dispersion type carbon black as a coloring material, it is possible to disperse the carbon black in the ink in a stable state in an aqueous medium without using a dispersant. Become.

The cationic self-dispersible carbon black which can be suitably used in the present invention includes, for example, a phenyl group, a benzyl group or a benzyl group, wherein a hydrophilic group bonded directly or via another atomic group to the surface of the carbon black. And a heterocyclic group such as a pyridyl group and at least one aromatic group such as a group, a phenacyl group and a naphthyl group, and at least one cationic group. More preferably, the cationic group bonded to the surface of carbon black is preferably a quaternary ammonium group. Also, instead of a quaternary ammonium group,
Those having a quaternary phosphonium group are also effective.

The hydrophilic group bonded to the surface of the self-dispersible carbon black preferably used in the present invention includes those having the following structures. However, the present invention is not limited to these. However, in the following formula, R represents a linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted phenyl group, or a substituted or unsubstituted naphthyl group.

[0023]

The content in the self-dispersion type carbon black ink having the above-mentioned cationic group bonded to the surface is not particularly limited, but is in the range of 0.5 to 15% of the total weight of the ink. It is particularly preferable that the content be in the range of 1.0 to 10%. That is,
By setting this range, for example, the reliability as an inkjet ink, such as print density and ink ejection stability, can be further improved.

As a method for producing a cationically charged self-dispersible carbon black having a hydrophilic group bonded thereto as described above, for example, a method of bonding an N-ethyl viridyl group having the following structure is exemplified. For example, there is a method of treating carbon black with 3-amino-N-ethylpyridium bromide.

The carbon black charged cationically by introducing a hydrophilic group into the surface of the carbon black by the method described above has excellent water dispersibility due to repulsion of ions. For this reason, the cationically charged carbon black, when contained in an aqueous ink, exhibits good dispersibility without adding a dispersant or the like, and can maintain a stable dispersion state. Become.

The carbon black used at this time is, for example, a carbon black produced by a furnace method or a channel method, and has a primary particle diameter of 15 to 40.
nm, specific surface area by BET method is 50 to 300 m ² /
g, DBP oil absorption of 40 to 150 ml / 100 g, volatile matter of 0.5 to 10%, and pH of 2 to 9 are preferably used.

Commercial products having such properties include:
For example, no. 2300, no. 900, MCF88,
No. 33, no. 40, no. 45, no. 52, M
A7, MA8, No. 2200B (above, manufactured by Mitsubishi Chemical), RAVEN 1255 (above, manufactured by Columbia), R
EGAL400R, REGAL330R, REGAL6
60R, MOGUL L (all made by Cabot), Co
lor Black FW-1, Color Blac
k FW18, Color Black S170, C
color Black S150, Printex 3
5, Printex U (all manufactured by Degussa) and the like.

The cationically charged carbon black used in the present invention may be one in which various hydrophilic groups as described above are directly bonded to the surface of the carbon black, or other atomic groups may be used. An embodiment in which the hydrophilic group is indirectly bonded to the surface of the carbon black by being interposed between the carbon black surface and the hydrophilic group may be used. Other atomic groups include, for example, one having 1 carbon atom.
To 12 alkyl groups, a phenyl group which may have a substituent or a naphthyl group which may have a substituent. Here, examples of the substituent of the phenyl group or the naphthyl group include a linear or branched alkyl group having 1 to 6 carbon atoms.

Specific examples of the hydrophilic group bonded to the carbon black surface via another atomic group include, for example, -C _{2
H 4 COOM, -PhSO 3 M,} -PhCOOM, -C 5
H ₁₀ ⁺ NH ₃ etc. (where M is a hydrogen atom, an alkali metal,
Represents ammonium or organic ammonium, and Ph represents a phenyl group. ), But of course, the present invention is not limited to these. The self-dispersion type carbon black described above used in the present invention is not limited to one type, and by using a mixture of two or more types,
The color tone and characteristics of the ink may be adjusted.

The black ink constituting the ink set according to the present invention comprises the above-described cationic self-dispersible carbon black held in a dispersed state in an aqueous medium. The component of the aqueous medium used at this time may be any one containing at least water. As a ratio of water to the total weight of the ink, for example, 20 to 9
5% by weight, especially 40-95% by weight, furthermore 60-95%
% By weight.

The aqueous medium may contain the following water-soluble organic solvents in addition to water. Suitable water-soluble organic solvents include, for example, alkyl alcohols having 1 to 4 carbon atoms (for example, methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol and tert-butyl alcohol etc.), ketone or keto alcohols (e.g. amides such as dimethylformamide and dimethylacetamide, acetone and diacetone alcohol etc.), ethers (e.g. tetrahydrofuran and dioxane etc.), polyalkylene glycols (e.g. , Polyethylene glycol and polypropylene glycol), alkylene glycols in which the alkylene group contains 2 to 6 carbon atoms (eg, ethylene glycol, propylene glycol, butylene glycol) , Triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol, etc.) and alkyl ethers such as polyhydric alcohols (eg, ethylene glycol methyl ether, ethylene glycol ethyl ether, triethylene Monomethyl ether and triethylene glycol monoethyl ether, etc.), and N-methyl-2-
Pyrrolidone, 2-pyrrolidone and 1,3-dimethyl-2
-Imidazolidinones and the like. The total amount of the water-soluble organic solvent in the ink is 2 to 60% by weight based on the total amount of the ink, and more preferably 5 to 25%.

Further, a particularly preferred water-soluble organic solvent in the present invention is glycerin, and its addition amount is 2 to 30% by weight, more preferably 5 to 15% by weight in the ink.
Is preferred. Further suitable water-soluble organic solvent is a mixed solvent containing glycerin and a polyhydric alcohol (for example, diethylene glycol or ethylene glycol),
The mixing ratio of glycerin and other polyhydric alcohol is glycerin: other polyhydric alcohol = 10: 5 to 10:50
It is preferable to use those within the range. Other polyhydric alcohols used with glycerin include, for example, diethylene glycol, ethylene glycol, polyethylene glycol and propylene glycol.
These glycerin or a mixed solvent of glycerin and a polyhydric alcohol can be used by further mixing with another water-soluble organic solvent. Further, in addition to the above-mentioned coloring materials, various additives such as a surfactant, a pH adjuster and a fungicide may be added to the black ink used in the present invention, if necessary. .

The black ink constituting the ink set according to the present invention is preferably used in an ink jet recording method for recording an image by ejecting ink from a recording head by thermal energy or mechanical energy and attaching the ink to a recording medium. It is something that can be done. Therefore, if the black ink composed of the above-described constituent materials is to be particularly suitable for inkjet recording, the ink 25
The surface tension is 15 to 60 mN / m
(Dyn / cm), and 20 to 50 mN / m (dy)
n / cm), and the viscosity is preferably 15 cP or less, particularly preferably 10 cP or less, and more preferably 5 cP or less. Also, pH
Is preferably from 3 to 11, and more preferably from 3.5 to 8.

The ink set according to the present invention is characterized in that a color ink having at least one anionic dye and further another anionic substance is used in combination with the black ink having the above constitution. I do. Less than,
The constituent materials of the color ink used at this time will be described.

First, as the anionic dye which is preferable as a component of the color ink constituting the ink set according to the present invention, any of existing dyes, newly synthesized dyes, and dyes having appropriate color tone and density can be used. Most things can be used. Further, any of these can be used in combination. The content of the anionic dye is 0.2 to 1 based on the total weight of the ink.
It is preferably in the range of 5% by weight, more preferably,
The range is 0.5 to 10% by weight. That is, by setting the content within this range, for example, the ink has good color developability, and the reliability of the inkjet ink such as the ejection stability of the ink can be further improved.

Further, the anionic color ink used in the present invention is characterized by containing at least one anionic substance other than the above-mentioned dyes. As the anionic substance, any existing substances can be used as long as they have anionic property, and most of those newly synthesized can be used, but those having a carboxyl group or a sulfone group are more preferable. . Examples of the anionic substance having a carboxyl group or a sulfone group that can be used in the present invention include salts of organic acids. More specifically, for example, sodium alkyl sulfate, sodium alkyl sulfate, sodium dialkyl sulfosuccinate, sodium alkyl naphthalene sulfonate, sodium alkyl diphenyl ether disulfonate, sodium alkyl taurine, sodium lauryl sulfo acetate and sodium dialkyl sulfosuccinate, etc. Anionic surfactants, aromatic compounds containing a sulfone group such as sodium benzenesulfonate, sodium benzenedisulfonate, sodium naphthalenesulfonate, sodium naphthalene disulfonate and sodium naphthalene trisulfonate, sodium benzoate, ammonium benzoate And other carboxyl-containing aromatic compounds, but are not limited thereto. .

The content of the anionic substance is as follows:
It is preferably in the range of 0.2 to 10% by weight, more preferably 0.5 to 8% by weight, based on the total weight of the color ink. That is, by setting the content in this range, for example, a desired aggregation effect can be exhibited, and the reliability as an inkjet ink can be ensured.

The color ink used in the present invention includes:
It is preferable to include a surfactant in order to have a high permeability to so-called plain paper. As the surfactant, in addition to the above-mentioned anionic surfactant, higher alcohol ethylene oxide adduct, alkylphenol ethylene oxide adduct, aliphatic ethylene oxide adduct, polyhydric alcohol fatty acid ester ethylene oxide adduct, fatty acid amide ethylene oxide Adducts, higher alkylamine ethylene oxide adducts, polypropylene glycol ethylene oxide adducts, nonionic surfactants of fatty acid esters of polyhydric alcohols and fatty acid amides of alkanolamines, amino acid type or betaine type amphoteric surfactants, etc. Is mentioned. These surfactants may be appropriately selected and used as a mixture of two or more.

The amount of the surfactant to be added in the color ink is not particularly limited, but is preferably in the range of 0.01 to 10% by weight based on the total weight of the ink. That is, by setting the content in this range, a desired penetration effect can be exhibited, and further, the reliability as the ink for inkjet recording can be secured.

In order to make the ink have high permeability, for example, ethylene glycol monomethyl ether,
Ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, propylene glycol monobutyl ether and dipropylene It is also effective to include ethers of a polyhydric alcohol such as glycol monobutyl ether. Furthermore, when permeability is insufficient, fast permeability to plain paper or the like can be supplemented by adding a highly permeable water-soluble organic solvent such as hexylene glycol or dipropylene glycol.

When a color ink is produced using the above-described constituent materials, water and a water-soluble organic solvent are used as a liquid medium for dispersing or dissolving the above-mentioned anionic dyes and anionic substances. It is preferred to use a mixture. Examples of the aqueous medium used for the color ink include water or a mixed medium of water and a water-soluble organic solvent. As the water-soluble organic solvent, it is particularly preferable to use one having an ink drying prevention effect.

Specifically, examples of the water-soluble organic solvent include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, and tert-butyl alcohol.
Alkyl alcohols having 1 to 4 carbon atoms such as butyl alcohol; amides such as dimethylformamide and dimethylacetamide; ketones or ketone alcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; polyethylene glycol and polypropylene glycol Polyalkylene glycols such as ethylene glycol, propylene glycol, butylene glycol, triethylene glycol,
1,2,6-hexanetriol, thiodiglycol,
Alkylene glycols having an alkylene group containing 2 to 6 carbon atoms, such as hexylene glycol and diethylene glycol; lower alkyl ether acetates, such as polyethylene glycol monomethyl ether acetate; glycerin; ethylene glycol monomethyl (or ethyl)
Ether, diethylene glycol methyl (or ethyl)
Lower alkyl ethers of polyhydric alcohols such as ether and triethylene glycol monomethyl (or ethyl) ether; polyhydric alcohols such as trimethylolpropane and trimethylolethane; N-methyl-2-pyrrolidone, 2-pyrrolidone and 1,3 -Dimethyl-2-imidazolidinone and the like can be used. The water-soluble organic solvents as described above can be used alone or as a mixture.

The content of the water-soluble organic solvent contained in the ink according to this embodiment is not particularly limited, but is preferably in the range of 3 to 50% by weight based on the total weight of the ink. or,
The content of water contained in the ink is preferably in the range of 50 to 95% by weight based on the total weight of the ink. It is desirable to use deionized water.

The color ink having the above-mentioned constitution constituting the ink set according to the present invention can be used for ink for writing implements and ink for ink jet recording. Ink jet recording methods include a recording method in which mechanical energy is applied to ink to eject droplets, and a recording method in which thermal energy is applied to ink to eject droplets by bubbling of the ink. The above color inks are particularly suitable. When the color ink is used for ink jet recording, it is preferable that the ink is configured to have a characteristic that can be ejected from an ink jet head. That is, from the viewpoint of ejection from the inkjet head, the characteristics of the ink include:
For example, the viscosity is 1 to 15 cP and the surface tension is 25 mN
/ M (dyn / cm) or more, in particular, the viscosity is 1 to 5c.
P, the surface tension is preferably 25 to 50 mN / m (dyn / cm).

The preferred aqueous medium composition for supporting the above-mentioned properties in the color ink includes, for example, glycerin, trimethylolpropane, thioglycol, ethylene glycol, diethylene glycol,
It is preferable to include isopropyl alcohol and acetylene alcohol. In addition, as an acetylene alcohol, the acetylene alcohol shown by a following formula can be mentioned, for example.

[0047]

In addition, in addition to the above components, urea, thiourea, ethylene urea, alkyl urea, alkyl thiourea, dialkyl as a humectant may be contained in the color ink used in the ink set of the present invention. Nitrogen-containing compounds such as urea and dialkylthiourea, and pH adjusters, viscosity adjusters, preservatives, antioxidants, evaporation promoters, rust preventives, fungicides, and chelates for imparting desired performance to inks. An additive such as an agent may be blended.

The ink set of the present invention, which is a combination of the black ink and the color ink described above, is suitably used in an ink jet recording method in which ink droplets are ejected from an orifice according to a recording signal to perform recording on a recording medium. However, it is particularly suitably used for an ink jet recording system in which recording is performed by ejecting ink droplets by the action of thermal energy. As a recording method for suitably performing recording using the ink set of the present invention, an ink jet recording method in which thermal energy corresponding to a recording signal is applied to inks of respective colors accommodated in a recording head and droplets are generated by the energy. In the following, an example of the inkjet recording apparatus of the present invention to which such an inkjet recording method is applied will be described.

First, an example of the configuration of a head, which is a main part of the apparatus, is shown in FIGS. FIG. 1 is a cross-sectional view of the head 13 along the ink flow path, and FIG.
It is sectional drawing in the -B line. The head 13 includes a glass, ceramic or plastic plate or the like having a groove 14 through which ink passes, and a heating head 15 (a thin film head is shown in the figure, but is not limited to this). ) Are adhered. The heating head 15
It comprises a protective film 16 made of silicon oxide or the like, aluminum electrodes 17-1 and 17-2, a heating resistor layer 18 made of nichrome or the like, a heat storage layer 19, and a substrate 20 having good heat dissipation such as alumina. I have.

The ink 21 has a discharge orifice (fine hole).
22 and a meniscus 23 is formed by the pressure P. Now, aluminum electrodes 17-1 and 17-2
When electric signal information is added to the area, the area indicated by n of the heating head 15 rapidly generates heat, and the ink 21 in contact with the area is heated.
Bubbles are generated, and the meniscus 23 projects by the pressure,
The ink 21 is ejected to form ink droplets 24 and flies from the ejection orifice 22 toward the recording medium 25.

FIG. 3 is an external view of a multi-head in which many heads shown in FIG. 1 are arranged. The multi-head is manufactured by closely contacting a glass plate 27 having a multi-groove 26 and a heating head 28 similar to that described with reference to FIG.

FIG. 4 shows an example of an ink jet recording apparatus incorporating the above head. In FIG. 4, reference numeral 61 denotes a blade as a wiping member, one end of which is held by a blade holding member to become a fixed end, and forms a cantilever. The blade 61 is arranged at a position adjacent to a recording area of the recording head 65, and in the present example, is held in a form protruding into the movement path of the recording head 65. Reference numeral 62 denotes a cap on the ejection 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, contacts the ink ejection port surface, and performs capping. Is provided. Further, reference numeral 63 denotes an ink absorber provided adjacent to the blade 61, which is held in a form protruding into the movement path of the recording head 65, similarly to the blade 61.

The blade 61, the cap 62, and the ink absorber 63 constitute an ejection recovery section 64, and the blade 61 and the ink absorber 63 remove water, dust, and the like from the ink ejection port surface. 65 is a recording head that has ejection energy generating means, and performs recording by ejecting ink to a recording medium facing an ejection port surface where ejection ports are arranged;
Reference numeral 66 denotes a carriage on which the recording head 65 is mounted and moved. The carriage 66 is slidably engaged with the guide shaft 67, and a part of the carriage 66 is a motor 68.
(Not shown) connected to the belt 69 driven by the motor. As a result, the carriage 66 can move along the guide shaft 67, and the recording head 65 can move the recording area and the adjacent area.

Reference numeral 51 denotes a paper feed unit for inserting a recording medium, and reference numeral 52 denotes a paper feed roller driven by a motor (not shown). With such a configuration, the recording medium is fed to a position facing the discharge port surface of the recording head 65, and is discharged to a discharge section provided with a discharge roller 53 as recording proceeds. In the above configuration, when the recording head 65 returns to the home position at the end of recording or the like, the cap 62 of the ejection recovery unit 64 is retracted from the moving path of the recording head 65, but the blade 61 protrudes into the moving path. As a result, the ejection port surface of the recording head 65 is wiped.
When capping is performed with the cap 62 in contact with the ejection surface of the recording head 65, the cap 62 moves so as to protrude into the movement path of the recording head.

When the recording head 65 moves from the home position to the recording start position, the cap 62 and the blade 61 are at the same position as the position at the time of wiping described above. As a result, the ejection port surface of the recording head 65 is also wiped during this movement. The movement of the print head 65 to the home position is performed not only at the end of printing or at the time of ejection recovery, but also at the home position adjacent to the printing area at a predetermined interval while the printing head 65 moves through the printing area for printing. And the wiping is performed with this movement.

FIG. 5 is a diagram showing an example of an ink cartridge 45 containing ink supplied to the 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. An ink absorber 44 receives the waste ink.
It is preferable for the present invention that the ink container has a surface in contact with the ink made of polyolefin, particularly polyethylene.

The ink jet recording apparatus of the present invention is not limited to the above-described head and the ink cartridge which are separated from each other, but can also be suitably used for an integrated apparatus as shown in FIG. In FIG. 6, reference numeral 70 denotes a recording unit, in which an ink storage unit storing ink, for example, an ink absorber is stored, and a head unit having a plurality of orifices in which the ink in the ink absorber is stored. It is configured to be ejected from 71 as ink droplets.

As the material of the ink absorber, it is preferable to use polyurethane, cellulose, polyvinyl acetate or polyolefin resin. Reference numeral 72 denotes an atmosphere communication port for communicating the inside of the recording unit with the atmosphere.
The recording unit 70 is used in place of the recording head shown in FIG. 4, and is detachable from the carriage 66.

FIG. 7 is a perspective view showing an ink jet recording apparatus applicable to the present invention. The recording medium 106 inserted at the sheet feeding position of the recording apparatus is transported by the feed roller 109 to a recordable area of the recording head unit 103. A platen 108 is provided below the recording medium in the recordable area. The carriage 111 is configured to be movable in a direction determined by two guide shafts, a guide shaft 104 and a guide shaft 105, and reciprocally scans a recording area. A carriage 111 includes a print head that discharges a plurality of color inks, and a print head unit 103 that includes an ink tank that supplies ink to each print head.
Is installed. The plurality of color inks provided in the ink jet recording apparatus of this example are four color inks of black (Bk), cyan (C), magenta (M), and yellow (Y).

At the left end of the area where the carriage can move,
A recovery system unit 110 is provided at a lower portion, and the ejection port of the recording head is capped during non-printing. This left end is called the home position of the recording head. Reference numeral 107 denotes a switch unit and a display element unit. The switch unit is used when turning on / off the power of the recording apparatus, setting various recording modes, and the like.

FIG. 8 is a perspective view showing the recording head unit of FIG. Bk, C, M,
A recording head 102 for ejecting ink of each color of Y;
Ink tank 20Bk for C, ink tank 20C for C, M
The ink tank 20M for Y and the ink tank 20Y for Y are mounted. Each tank is connected to the print head via a connection to the print head, and supplies ink to the ejection openings. In addition to this example, for example, the tanks for the respective color inks of C, M, and Y may have an integral structure.

FIG. 9 is an enlarged sectional view of the vicinity of the heating element of the recording head. In the ink jet recording apparatus of this example, a heating element, which is an electric-to-heat converter, is arranged corresponding to each ink ejection port, and a drive signal corresponding to recording information is applied to the heating element to eject ink from a nozzle. The recording method is adopted. The heating element 31 is configured to be capable of independently generating heat for all nozzles.

The ink in the nozzle, which has been rapidly heated by the heat generated by the heating element 31, forms bubbles by film boiling, and the pressure of the bubble generation causes the ink droplets 35 as shown in FIG.
Is ejected toward the recording medium 106 to form characters and images on the recording medium. Each of the ejection ports 37 is provided with an ink liquid path communicating with the ejection port.
A common liquid chamber 32 for supplying ink to these liquid passages is provided behind the portion where the 8 is provided. In the ink liquid passage corresponding to each of the discharge ports, a heating element 31 which is an electric-to-heat converter that generates thermal energy used for discharging ink droplets from these discharge ports, and supplies power to the heat element 31 Electrode wiring is provided. These heating elements 31 and electrode wirings are formed by a film forming technique on a substrate 33 made of silicon or the like. On the heating element 31,
A protective film 36 is formed so that the ink and the heating element do not come into direct contact with each other. Furthermore, the above-described ejection port, ink liquid path, common liquid chamber, and the like are formed by laminating a partition wall 34 made of resin or glass material on this substrate.

As described above, the recording method using the heating element which is an electric / heat converter uses bubbles formed by applying thermal energy at the time of discharging ink droplets. It is called a method.
In the above-described recording apparatus of the present invention, an ink-jet recording apparatus that ejects ink droplets by applying thermal energy to ink has been described as an example. May be used as the ink jet recording apparatus.

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.
FIG. 1 is a schematic perspective view illustrating a main part of an example of a liquid discharge head as a liquid discharge head of a discharge method according to the present invention in which bubbles communicate with the atmosphere at the time of discharge and an ink jet printer as a liquid discharge device using the head.

In FIG. 10, the ink-jet printer uses a sheet P 1028 as a recording medium provided in a casing 1008 along the longitudinal direction as indicated by an arrow P in the drawing.
And a recording unit 1010 that is reciprocated substantially in parallel with a guide shaft 1014 in an arrow S direction substantially perpendicular to the transport direction P of the sheet 1028 by the transport device 1030. , Recording unit 10
Moving drive unit 10 as a driving means for reciprocating the motor 10
06 is included.

The movement driving unit 1006 is provided with pulleys 1026a arranged on rotating shafts which are arranged to face each other at a predetermined interval.
And a belt 101 wound around a pulley 1026b.
6, a roller unit 1022a, and a motor 1018 that is disposed substantially parallel to the roller unit 1022b and drives a belt 1016 connected to the carriage member 1010a of the recording unit 1010 in the forward and reverse directions.

When the motor 1018 is activated and the belt 1016 rotates in the direction of arrow R in FIG. 10, the carriage member 1010a of the recording unit 1010 moves to the position indicated by arrow S in FIG.
In the direction by a predetermined amount of movement. Also, the motor 101
8, when the belt 1016 rotates in the direction opposite to the direction of the arrow R shown in the figure, the carriage member 1010a of the recording unit 1010 moves by a predetermined amount in the direction opposite to the direction of the arrow S in FIG. It will be moved by an amount. Further, one end of the movement driving unit 1006 is provided with a recording unit 1 at a position which is a home position of the carriage member 1010a.
Recovery unit 102 for performing the discharge recovery process of 010
6 is provided to face the ink ejection port arrangement of the recording unit 1010.

The recording unit 1010 includes an ink jet cartridge (hereinafter sometimes simply referred to as a cartridge) 1012Y, 1012M, 1012C, and 101.
2B is detachably provided for the carriage member 1010a for each color, for example, yellow, magenta, cyan, and black.

FIG. 11 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 that stores a liquid such as ink.

The ink jet recording head 100 has a large number of discharge ports 832 for discharging a liquid.
Liquid such as ink is led from the liquid tank 1001 to a common liquid chamber (see FIG. 12) of the liquid ejection head 100 via a liquid supply passage (not shown). FIG.
In the cartridge 1012 shown in FIG. 1, the ink jet recording head 100 and the liquid tank 1001 are integrally formed so that liquid can be supplied into the liquid tank 1001 as necessary.
Alternatively, a structure in which the liquid tanks 1001 are exchangeably connected to each other may be adopted.

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. 12 is a schematic perspective view schematically showing a main part of a liquid discharge head suitable for the ink jet recording apparatus of the present invention. FIGS. 13 to 16 show discharge ports of the liquid discharge head shown in FIG. It is a front view which shows a shape. Note that, in these drawings, 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 as shown in FIG. 12 is used. The material of such a substrate is not the essence of the present invention,
There is no particular limitation as long as it functions as a part of the flow path constituent member and can function as a support for a material layer forming the ink discharge energy generating element and a liquid flow path and a discharge port described later. . Therefore, in this example, a case where a Si substrate (wafer) is used will be described. Such a substrate 934
An ink discharge port is formed on the upper surface. In addition to the formation method using a laser beam, for example, an orifice plate (discharge port plate) 935 described later is used as a photosensitive resin, and an MPA (Mirror Projection A) is used.
and a method of forming the discharge port by an exposure apparatus such as a liner.

In FIG. 12, reference numeral 934 denotes a substrate provided with an electrothermal conversion element (hereinafter sometimes referred to as a heater) 931 and an ink supply port 933 comprising a long groove-shaped through hole as a common liquid chamber. On both sides of the opening 933 in the longitudinal direction, heaters 9 serving as thermal energy generating means are provided.
31 are arranged in a zigzag pattern in a row, and the intervals between the electrothermal conversion elements are arranged, for example, at 300 dpi. An ink flow path wall 936 for forming an ink flow path is provided on the substrate 934. This ink flow path wall 9
The discharge port plate 9 further includes a discharge port 832.
35 are provided.

Here, in FIG.
36 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 a method such as spin coating. Can be formed simultaneously as the same member. here,
Further, the ejection port surface (upper surface) 935a is subjected to a water-repellent treatment.

In the illustrated apparatus, recording is performed at, for example, 1,200 dpi using a serial type head that performs recording while scanning in the direction of arrow S in FIG. The driving frequency is 10 kHz, and one ejection port performs ejection at a minimum time interval of 100 μs.

As an example of the actual dimensions of the head, for example, as shown in FIG. 13, a partition wall 936a that fluidly isolates adjacent nozzles has a width w = 14 μm. FIG.
As shown in FIG. 6, the foaming chamber 1337 formed by the ink flow path wall 936 has N ₁ (width of the foaming chamber) = 33 μm.
m, N ₂ (length of foaming chamber) = 35 μm. The size of the heater 931 is 30 μm × 30 μm, the heater resistance value is 53Ω, and the driving voltage is 10.3V. The height of the ink flow path wall 936 and the partition wall 936a is 12 μm.
The thickness of the discharge port plate can be 11 μm.

As shown in FIG. 12, of the cross section of the discharge port portion 940 provided on the discharge port plate including the discharge port 832, cutting is performed in a direction intersecting the ink discharge direction (the thickness direction of the orifice plate 935). As shown in FIG. 14, the shape of the cross section thus obtained is substantially star-shaped, and includes six raised portions 832a having obtuse angles and these raised portions 83.
2a, and is roughly constituted by six ridges 832b alternately arranged and having acute angles. That is, the recess 832 as a region locally separated from the center O of the discharge port
b as its top and a base 832a as a region locally close to the center O of the discharge port adjacent to this region, and six grooves in the thickness direction (liquid discharge direction) of the orifice plate shown in FIG. (Refer to 1141a in FIG. 17 for the position of the groove).

In the liquid ejection head of the illustrated example,
The discharge port 940 is formed, for example, by forming two equilateral triangles each having a side of 27 μm cut along a direction intersecting the thickness direction thereof into 60 μm.
It has a shape that is combined in a state rotated by degrees, and T1 shown in FIG. 14 is 8 μm. The angles of the raised portions 832a are all 120 degrees, and the angles of the bent portions 832b are all 6 degrees.
0 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. (See FIG. 14) The opening area of the discharge port 832 in this example is 4
A 00Myuemu ^2, the opening area of the groove (and the top of the groove, the area of a figure formed by connecting the two bases adjacent to this top) is about 33 .mu.m ² per. FIG. 15 is a schematic diagram showing the state of ink adhesion at the ejection port shown in FIG.

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. 17 to 24 are cross-sectional views for explaining the liquid discharging operation of the liquid discharging head shown in FIGS. 12 to 16, 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 114 of the groove 1141.
1a.

FIG. 17 shows a state in which a film-like bubble has been generated on the heater. FIG. 18 shows about 1 μs after FIG. 17, FIG. 19 shows about 2 μs after FIG. 17, FIG. 20 shows about 3 μs after FIG. FIG.
1 is about 4 μs after FIG. 17, and FIG. 22 is about 5 μs from FIG.
FIG. 23 shows the state after about 6 μs in FIG. 17, and FIG. 24 shows the state after about 7 μs in FIG. In the following description, "fall" or "drop", "drop"
Does not mean falling in the direction of gravity,
It refers to movement in the direction of the electrothermal conversion element regardless of the mounting direction of the head.

First, as shown in FIG. 17, when air bubbles 101 are generated in the liquid flow path 1338 on the heater 931 due to energization of the heater 931 based on a recording signal or the like, the air bubbles are generated in about 2 μs. As shown in FIGS. 18 and 19, the volume grows rapidly. 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 has been reduced from a fraction of the atmospheric pressure to a fraction of the atmospheric pressure.

Next, at about 2 μs after the generation of the bubble 101, the bubble 101 starts to decrease in volume from the maximum volume as described above. At the same time, the formation of the meniscus 1004 also starts. The meniscus 1004 also retreats toward the heater 931 as shown in FIG. 19, that is, falls.

Here, in the liquid discharge head of the illustrated example, since the plurality of grooves 1141 are provided in the discharge port portion in a dispersed state, when the meniscus 1004 retreats, the meniscus Reverse direction F
Capillary force acts in the direction FC opposite to M. As a result, even if the slight variation in state of the bubble 101 by some cause was observed, meniscus and the main liquid droplet at the time of retraction of the meniscus (hereinafter, may be described as liquid or ink) the shape of I _a Is corrected so as to be substantially symmetrical with respect to the center of the discharge port.

In the liquid ejection head of the illustrated example, since the falling speed of the meniscus 1004 is faster than the contraction speed of the bubble 101, as shown in FIG. 21, at about 4 μs after the bubble is generated. The bubble 101 is the discharge port 8
32 communicates with the atmosphere near the lower surface. At this time, the discharge port 8
The liquid (ink) near the central axis of 32 drops toward the heater 931. This negative pressure fluid that is drawn back to the heater 931 side by the (ink) I _a of the bubble 101 before communicating with the atmosphere retains the velocity of the heater 931 side direction by inertia even after the air communication of the bubble 101 Because.

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. 22, and as shown in FIG. It 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 intersects with the surface of the heater 931, for example, the vector in the vertical direction disappears, and the heater 9.
The liquid above it, trying to stay on the surface of 31,
That is, the liquid maintaining the velocity vector in the ejection direction is pulled downward.

[0090] Then, Yuki become liquid portion I _b is thin between the liquid and the upper liquid spread on the surface of the heater 931 (main droplet) in FIG. 24 at a later time about 7μs from the generation of the bubble 101 liquid portion I _b is cut in the middle of the surface of the heater 931 as shown, is separated into a liquid I _c that has spread on the surface of the main liquid droplet I _a heater 931 to keep the velocity vector in the discharge direction. 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 being displaced in the ejection direction and without being distorted, and lands at a predetermined position on the recording surface of the recording medium. or,
The liquid I _c 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. Incidentally, in FIGS.
_Id is the ink attached to the groove (ink in the groove),
_Ie represents the ink remaining in the liquid flow path.

As described above, in the liquid ejection head of the illustrated example, when the liquid is ejected in the volume reduction stage after the bubble has grown to the maximum volume, the plurality of grooves dispersed with respect to the center of the ejection port is used. The direction of the main droplet during ejection can be stabilized. 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, in the liquid ejection head of the illustrated example,
By discharging the liquid by starting this 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 connected to the atmosphere and discharge the droplet, so-called sudden non-discharge It is also possible to suppress the state in which droplets adhere to the ejection port surface, which causes the above.

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 discharging, as described in Japanese Patent No. 2783647, for example, a so-called edge shooter is disclosed. Type.

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

The typical configuration and principle are described in, for example, US Pat.
It is preferable to use the basic principle disclosed in the specification of US Pat. No. 740,796. This method can be applied to both the so-called on-demand type and the 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 recording information and providing a rapid temperature rise exceeding film boiling to the electrothermal transducer, the thermal energy is generated in the electrothermal transducer, and the recording head This is effective because a film in the liquid (ink) corresponding to this drive signal can be formed one-to-one by causing film boiling on the heat acting surface.
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 liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable.

The pulse-shaped drive signal is disclosed in US Pat. Nos. 4,463,359 and 4,34,359.
Suitable are those described in US Pat. No. 5,262. If the conditions described in U.S. Pat. No. 4,313,124 relating to the temperature rise rate of the heat acting surface described above are adopted, more excellent recording can be performed.

The ink cartridge, the recording unit, and the recording head constituting the ink jet recording apparatus according to the present invention include a discharge port, a liquid path and an electrothermal converter as disclosed in the above-mentioned respective specifications. U.S. Pat. No. 4,558,333 and U.S. Pat. No. 4,459,600, which disclose configurations in which a heat acting portion is arranged in a bent region, in addition to a combination configuration (a linear liquid flow path or a right-angled liquid flow path). It is also preferable to use the one having the configuration used.

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, or 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 an opening corresponds to a discharge unit.

Further, as a full-line type recording head having a length corresponding to the width of the recording medium in the maximum range that can be recorded by the recording apparatus, a combination of a plurality of recording heads disclosed in the above-mentioned specification is used. However, the present invention can more effectively exhibit the above-described effects, although the configuration may satisfy the length of the recording head or the configuration as a single recording head.

In addition, the print head is replaceable with a print head of a replaceable chip type, which can be electrically connected to the main body of the apparatus and can supply ink from the main body of the apparatus, or is integrated with the print 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 recording head, preliminary auxiliary means, and the like provided in the structure of the ink jet recording apparatus of the present invention since the effects of the present invention can be further stabilized. is there. If these are specifically mentioned, capping means for the recording head, cleaning means, pressurizing or suction means, preheating means using an electrothermal converter or another heating element or a combination thereof, and printing Performing a preliminary ejection mode for performing another ejection is also effective for performing stable printing.

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

In the embodiment 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 and softens at room temperature or is a liquid, or in the above-described inkjet method, the ink itself is heated to 30 ° C. to 70 ° C. Since it is common to control the temperature so that the viscosity of the ink is in the stable ejection range by adjusting the temperature within the following range, any ink can be used as long as the ink is in a liquid state when the use recording signal is applied. good.

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 a solid state to a liquid state, or solidified in a standing state for the purpose of preventing 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 an ink having a property of being liquefied for the first time by thermal energy is also applicable to the present invention. In such a case, ink is disclosed in JP-A-54-56847.
JP-A No. 60-71260 or JP-A-60-71260, in a state in which the porous sheet is held as a liquid or solid material in a concave portion or a through-hole and faces the electrothermal converter. Is also good. 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, as an embodiment of the ink jet recording apparatus of the present invention, in addition to those provided integrally or separately as an image output terminal of an information processing device such as a word processor and a computer, a copying apparatus combined with a reader,
Further, 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. 25 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 having the above-described configuration can be mounted and applied.

In FIG. 25, an ink jet head cartridge 601 is formed by integrating the above-described liquid discharge head and an ink tank for holding ink to be supplied to the liquid discharge head. 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. The carriage 607 is reciprocated along the guide 608 with the power of the drive motor 602 in the directions of arrows a and b. The recording medium P ′ is conveyed over the platen roller 609 by a recording medium conveying unit (not shown), and is pressed against the platen roller 609 by the paper pressing plate 610 in the moving direction of the carriage 607.

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 the 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 suctioning the ink accumulated inside the cap member 614 due to idle discharge or the like from the inkjet head cartridge 601. The ink suction unit 615 allows the ink-jet head cartridge 601 to pass through an opening (not shown) in the cap.
Suction recovery is performed. A cleaning blade 617 for wiping the ejection port surface of the ink jet head cartridge 601 is provided so as to be movable in a front-rear direction (a direction perpendicular to the moving direction of the carriage 607) by a moving member 618. These cleaning blades 61
7 and the moving member 618 are supported by the main body support 619. The cleaning blade 617 is not limited to this mode, 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.
The movement of the driving force from the driving motor 602 is controlled by known transmission means such as clutch switching. An ink jet recording control unit for giving a signal to a heating element provided in the liquid ejection head of the ink jet head cartridge 601 and for controlling 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-described configuration, the recording medium P ′ conveyed on the platen roller 609 by the recording medium conveying means (not shown) corresponds to the entire width of the ink jet head cartridge 601. Recording while reciprocating over

[0114]

Next, the present invention will be described more specifically with reference to examples and comparative examples. In the following description, parts and percentages are by weight unless otherwise specified.

First, a cationic self-dispersion type carbon black for use as a coloring material of a black ink was prepared as follows. Of water ^{_{30g H 3 N + C 6 H}} 4 N
^{_{+ (CH 3) 3 Cl -}} · I - is in a solution dissolved 3.08 g, is added with stirring silver nitrate 1.69 g. The generated precipitate is removed by filtration, and the filtrate is added to 70 g of water while stirring, to a suspension in which 10 g of carbon black having a specific surface area of 230 m ² / g and DBPA of 70 ml / 100 g is dispersed. Next, 2.25 g of concentrated hydrochloric acid are added, and then a solution of 0.83 g of sodium nitrite dissolved in 10 g of water is added. Then, NN ⁺ C ₆ H ₄ having the structure shown below
A diazonium salt having an N ⁺ (CH ₃ ) ₃ group reacts with carbon black to generate nitrogen gas. When the bubbling of the nitrogen gas stops, the dispersion is dried in an oven at 120 ° C. As a result, C ₆ H ₄ N ⁺ (C
A product with ₃ H ₃ ) groups was obtained.

[0116]

<Example 1> Using the self-dispersible carbon black obtained above, a black ink having the following composition was prepared, and further combined with each color ink having the following composition to obtain a black ink of Example 1. Created an ink set. (1) Black ink (cationic) ・ 4 parts of the above carbon black ・ 8 parts of ethylene glycol ・ 5 parts of triethylene glycol ・ 6 parts of 1,5-pentanediol ・ 77 parts of water

(2) Yellow ink (anionic) I. Acid Yellow 23 3 parts ・ Glycerin 5 parts ・ Hexylene glycol 5 parts ・ Urea 7 parts ・ Sodium benzoate 1.5 parts ・ Water 78.5 parts

(3) Magenta ink (anionic) I. Acid Red 52 4 parts ・ 2-pyrrolidone 7 parts ・ Triethylene glycol monomethyl ether 7 parts ・ Urea 7 parts ・ Acetyleneol EH (trade name: manufactured by Kawaken Fine Chemical) 1 part ・ Sodium laurate 2 parts ・ Water 72 parts

(4) Cyan ink (anionic) I. Direct Blue 199 3 parts ・ Dipropylene glycol 8 parts ・ 1,2,6-hexanetriol 7 parts ・ Urea 6 parts ・ Ammonium benzoate 2 parts ・ Water 74 parts

<Example 2> Using the self-dispersion type carbon black obtained above, a black ink having the following composition was prepared, and further combined with each color ink having the following composition to obtain a second example. Created an ink set. (1) Black ink (cationic) ・ 4 parts of the above carbon black ・ 8 parts of ethylene glycol ・ 5 parts of triethylene glycol ・ 6 parts of 1,5-pentanediol ・ 77 parts of water

(2) Yellow ink (anionic) I. Acid Yellow 23 3 parts ・ Glycerin 5 parts ・ Hexylene glycol 5 parts ・ Urea 7 parts ・ Sodium lauryl sulfate 1.5 parts ・ Water 78.5 parts

(3) Magenta ink (anionic) I. Acid Red 52 4 parts ・ 2-Pyrrolidone 7 parts ・ Triethylene glycol monomethyl ether 7 parts ・ Urea 7 parts ・ Acetyleneol EH (trade name: manufactured by Kawaken Fine Chemical) 1 part ・ Sodium benzenesulfonate 2 parts ・ Water 72 parts

(4) Cyan ink (anionic) I. Direct Blue 199 3 parts ・ Dipropylene glycol 8 parts ・ 1,2,6-hexanetriol 7 parts ・ Urea 6 parts ・ N-lauroymethyltaurine sodium 2 parts ・ Water 74 parts

<Example 3> Using the self-dispersion type carbon black obtained above, a black ink having the following composition was prepared, and further combined with the respective color inks having the following compositions to obtain a third example. Created an ink set. (1) Black ink (cationic) ・ 4 parts of the above carbon black ・ 8 parts of ethylene glycol ・ 5 parts of triethylene glycol ・ 6 parts of 1,5-pentanediol ・ 77 parts of water

(2) Yellow ink (anionic) I. Acid Yellow 23 3 parts ・ Glycerin 5 parts ・ Diethylene glycol 5 parts ・ Urea 7 parts ・ Acetylene EH (trade name: manufactured by Kawaken Fine Chemical) 1 part ・ Naphthalene-1,3,6-trisulfonic acid trisodium 2 parts ・ Water 77 parts

(3) Magenta ink (anionic) I. Acid Red 52 4 parts ・ 2-Pyrrolidone 7 parts ・ Triethylene glycol monomethyl ether 7 parts ・ Urea 7 parts ・ Acetylene EH (trade name: manufactured by Kawaken Fine Chemical) 1 part ・ Naphthalene-1,3,6-trisulfonic acid Trisodium 2 parts ・ Water 72 parts

(4) Cyan ink (anionic) I. Direct Blue 199 3 parts ・ Propylene glycol 8 parts ・ 1,2,6-hexanetriol 7 parts ・ Urea 6 parts ・ Acetylene EH (trade name: manufactured by Kawaken Fine Chemical) 1 part ・ Disodium 1,5-naphthalenedisulfonic acid 2 parts ・ Water 73 parts

<Comparative Example 1> An ink set of Comparative Example 1 was prepared using the self-dispersion type black ink used in Example 1 in combination with each color ink having the following composition. (1) Black ink (cationic) ・ 4 parts of the above carbon black ・ 8 parts of ethylene glycol ・ 5 parts of triethylene glycol ・ 6 parts of 1,5-pentanediol ・ 77 parts of water

(2) Yellow ink C.I. I. Acid Yellow 23 3 parts ・ Glycerin 5 parts ・ Diethylene glycol 5 parts ・ Urea 7 parts ・ Acetyleneol EH (trade name: manufactured by Kawaken Fine Chemical) 1 part ・ Water 79 parts

(3) Magenta ink C.I. I. Acid Red 52 4 parts ・ 2-pyrrolidone 7 parts ・ Triethylene glycol monomethyl ether 7 parts ・ Urea 7 parts ・ Acetyleneol EH (trade name: manufactured by Kawaken Fine Chemical) 1 part ・ Water 74 parts

(4) Cyan ink I. Direct Blue 199 3 parts ・ Propylene glycol 8 parts ・ 1,2,6-hexanetriol 7 parts ・ Urea 6 parts ・ Acetyleneol EH (trade name: Kawaken Fine Chemical Co., Ltd.) 1 part ・ Water 75 parts

The black inks of the ink sets of Examples 1 to 3 and Comparative Example 1 obtained above were placed in a BC-60 cartridge (manufactured by Canon), and the color inks were placed in a BC-62 cartridge.
A cartridge (manufactured by Canon Inc.) was filled to produce an ink jet cartridge. Next, BJF-800 which is an inkjet recording apparatus that ejects the ink by applying thermal energy according to a recording signal to the ink using the inkjet cartridge manufactured as described above.
(Manufactured by Canon Inc.), a printing test was performed, and the following evaluation was performed. In addition, the BJF-
Reference numeral 800 is a modified one in which black ink is applied to a recording medium during the same scan as each color ink, and further, black ink can be applied to the recording medium immediately before application to the color ink recording medium. It is. As a printing method, a black ink is applied based on the above-described modification, and a color ink is applied immediately adjacent to the black ink applied area immediately after the black ink is applied during the same scan. The recorded matter thus obtained was evaluated according to the following criteria. Table 1 shows the results.

(1) Bleeding between Black Ink and Color Ink The above printing test was conducted using Canon copy paper: PB PAP
ER, manufactured by Xerox: 4024 PAPER, and the above two plain papers were used. (Evaluation Method and Evaluation Criteria) A solid portion was printed with black ink on each of the above two papers with each ink set, and immediately thereafter, a solid portion was printed with yellow, magenta, or cyan ink adjacent thereto. The evaluation criteria are as follows, and the evaluation results are shown in the table.

A: No bleeding is visually observed at all the boundaries. B: Although slight bleeding can be visually observed, there is no practical problem. C: Although slight bleeding is observed visually, it is within an allowable range. D: Clear bleed is seen visually.

[0136] As is clear from the results in Table 1, the ink sets of Examples 1 to 3 according to the present invention all showed excellent results with respect to bleed. In particular, when a substance having a sulfonic acid group is used as the other anionic substance added to the color ink, a particularly remarkable effect in reducing bleeding is recognized.

[0137]

As described above, according to the present invention,
Even if black ink and color ink are printed by the same scan on so-called plain paper, high-quality images with high print density are provided without bleeding or white haze at the boundary between black ink and color ink. Provided are an ink set for color ink jet recording that can be performed, an ink jet recording method using the ink set, and recording equipment. Further, according to the present invention, it is possible to obtain an ink set that can ensure the reliability as an inkjet ink despite using a pigment ink as a black ink.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an ink jet recording apparatus head.

FIG. 2 is a vertical and horizontal view of an ink jet recording apparatus head.

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

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

FIG. 5 is a vertical sectional view of the ink cartridge.

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

FIG. 7 is a perspective view showing an ink jet recording apparatus.

8 is a perspective view showing the recording head unit of FIG.

FIG. 9 is an enlarged sectional view of the vicinity of a heating element of a recording head.

FIG. 10 is a schematic perspective view illustrating a main part of an example of an ink jet printer on which a liquid discharge head can be mounted.

FIG. 11 is a schematic perspective view showing an example of an ink jet cartridge provided with a liquid ejection head.

FIG. 12 is a schematic perspective view schematically showing a main part of an example of a liquid ejection head used in the ink jet cartridge shown in FIG.

FIG. 13 is a conceptual diagram illustrating a part of an example of the liquid ejection head illustrated in FIG. 11;

FIG. 14 is an enlarged view of a discharge port shown in FIG.

FIG. 15 is a schematic diagram showing the state of ink attachment at the ejection port shown in FIG. 14;

FIG. 16 is a schematic diagram of a main part in FIG.

17 corresponds to a perspective sectional shape taken along line XX in FIG. 16 and FIG.
FIG. 25 is a schematic cross-sectional view for explaining the liquid discharging operation of the liquid discharging head with time along with FIGS. 8 to 24.

FIG. 18 corresponds to the perspective sectional shape taken along line XX in FIG. 16;
FIG. 25 is a schematic cross-sectional view for explaining the liquid discharging operation of the liquid discharging head with time, together with FIG. 7 and FIGS.

19 corresponds to a perspective sectional shape taken along line XX in FIG. 16 and FIG.
FIG. 27 is a schematic cross-sectional view for explaining the liquid discharging operation of the liquid discharging head with time, together with FIG. 7, FIG. 18, and FIGS.

FIG. 20 corresponds to a perspective sectional view taken along line XX in FIG. 16;
FIG. 25 is a schematic cross-sectional view for explaining the liquid discharging operation of the liquid discharging head with time along with FIGS. 7 to 19 and FIGS.

FIG. 21 corresponds to a perspective sectional shape taken along line XX in FIG.
FIG. 25 is a schematic cross-sectional view for explaining the liquid discharging operation of the liquid discharging head with time along with FIGS. 7 to 20 and FIGS.

FIG. 22 corresponds to a perspective sectional shape taken along line XX in FIG.
FIG. 27 is a schematic cross-sectional view for explaining the liquid discharging operation of the liquid discharging head with time along with FIGS. 7 to 21 and FIGS.

FIG. 23 corresponds to a perspective sectional shape taken along line XX in FIG.
FIG. 25 is a schematic cross-sectional view for explaining the liquid discharging operation of the liquid discharging head with time along with FIGS. 7 to 22 and 24.

FIG. 24 corresponds to a perspective sectional shape taken along line XX 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.

FIG. 25 is a schematic perspective view of an ink jet recording apparatus 600 which is an example of a liquid ejection apparatus to which the liquid ejection head of the present invention can be mounted.

[Explanation of symbols]

13: Head 14: Ink Groove 15: Heating Head 16: Protection Film 17: Aluminum Electrode 18: Heating Resistor Tank 19: Heat Storage Layer 20: Substrate 21: Ink 22: Discharge Orifice (Micro Hole 23: Meniscus 24: Ink Drop 25) : Recording material 26: Multi-groove 27: Glass plate 28: Heating head 31: Heating element 32: Liquid chamber 33: Substrate 34: Partition wall 35: Ink droplet 36: Protective film 37: Discharge port 38: Ink liquid path 40: Ink Bag 42: stopper 44: ink absorber 45: ink cartridge 51: paper supply unit 52: paper feed roller 53: paper discharge roller 61: blade 62: cap 63: ink absorber 64: ejection recovery unit 65: recording head 66: Carriage 67: Guide shaft 68: Motor 69: Belt 70: Recording unit 71: Head 72: Atmospheric communication port 1 00: inkjet recording head 101: air bubble 102: recording head 103: recording head unit 104: guide shaft 105: guide shaft 106: recording material 107: switch and display element 108: platen 109: feed roller 110: recovery unit 111: Carriage 20Bk, 20C, 20M, 20Y: Ink tank 600: Inkjet recording device 601: Inkjet head cartridge 602: Driving motor 603, 604: Driving force transmission gear 605: Lead screw 606: Spiral groove 607: Carriage 607a: Lever 608: Guide 609: Platen roller 610: Paper holding plate 611, 612: Photocoupler 613: Support member 614: Cap member 615: Ink suction means 616: Opening inside cap 617: C Cleaning blade 618: Moving member 619: Main body support 620: Lever 621: Cam 832: Discharge port 832a: Initiating portion 832b: Depressed portion 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 channel wall 936a: Partition wall 940: Discharge port 1337: Bubble chamber 1338: Liquid channel 1141: Groove 1141a : Top portion 1004: Meniscus 1001: Liquid tank 1006: Movement drive unit 1008: Casing 1010: Recording unit 1010 a: Carriage member 1012: Cartridge 1012 Y, M, C, B: Inkjet cartridge 1014: Guide shaft 1016: Belt 1018: Mo Data 1020: drive units 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 backward F _C: meniscus retraction direction opposite direction G: center of gravity I: ink I _a: main droplet (liquid ink) I _b, I _c: liquid (ink) I _d : ink attached to the groove (ink in the groove) I _e : ink remaining in the liquid flow path L: line from liquid chamber (ink supply port) to discharge port N ₁ : width dimension of bubbling chamber N ₂ : length dimension of foaming chamber O: center of discharge port P ': recording material P: paper transport method Direction R: Rotation direction of belt S: Direction substantially perpendicular to the paper transport direction T ₁ : Discharge port protrusion w: Wall width of partition

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yuko Yakushigawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Yoshihisa Takizawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Non Corporation

Claims (16)

[Claims] An ink set for ink-jet recording for recording a color image on a recording material using at least two colors of ink including at least a black ink and a color ink, wherein the black ink is a cationic ink Wherein the color ink comprises an anionic dye and another anionic substance. 2. The ink set for color inkjet recording according to claim 1, wherein the anionic substance contained in the color ink contains a carboxyl group. 3. The ink set for inkjet recording according to claim 1, wherein the anionic substance contained in the color ink contains a sulfone group. 4. The ink set for inkjet recording according to claim 3, wherein the ink set has a plurality of sulfone groups. 5. The ink set for color inkjet recording according to claim 1, wherein the anionic substance contained in the color ink is a substance in which an aromatic ring is substituted with a sulfone group. 6. The ink set for inkjet recording according to claim 5, wherein the ink set has a plurality of sulfone groups. 7. The ink set for ink-jet recording according to claim 1, wherein the anionic dye contained in the color ink is a dye containing a sulfone group. 8. A step of ejecting a black ink containing a cationic self-dispersible carbon black from an orifice according to a recording signal; and ejecting a color ink containing an anionic dye according to a recording signal. An ink jet recording method comprising the steps of: using a color ink further containing an anionic substance as the color ink. 9. The ink jet recording method according to claim 8, wherein each step of discharging the black ink and the color ink includes a step of applying thermal energy to the black ink and the color ink to discharge the black ink and the color ink. . 10. A first ink container containing a black ink containing a cationic self-dispersible carbon black, and containing a color ink containing an anionic dye and another anionic substance. And a head for discharging each of the black ink contained in the first ink containing section and the color ink contained in the second ink containing section. A recording unit, comprising: 11. The recording unit according to claim 10, wherein the head section is a head that ejects the ink by applying thermal energy to the ink. 12. A first ink containing section containing a black ink containing a cationic self-dispersible carbon black, and a color containing an anionic coloring material and another anionic substance. Second containing ink
An ink cartridge characterized by comprising the above ink storage section. 13. A first ink containing section containing a black ink containing a cationic self-dispersible carbon black, and a color ink containing an anionic coloring material and another anionic substance. An ink jet recording apparatus comprising: a second ink storage unit that stores therein; and a head unit that ejects the black ink and the color ink, respectively. 14. The ink jet recording apparatus according to claim 13, wherein the head section is a head that ejects the ink by applying thermal energy to the ink. 15. An ink supply unit according to claim 13, further comprising an ink supply unit for supplying each of black ink and color ink contained in said first and second ink containing units to said head unit. Inkjet recording device. 16. A method for alleviating bleeding in a boundary region between a black image formed by an ink jet recording method and a color image formed by an ink jet recording method, wherein the black image is formed of a cationic self-dispersible carbon black. Wherein the color image is formed with a color ink containing an anionic coloring material and another anionic substance.