JP3204761B2 - Ink jet recording method and method for improving black image density and fixability - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording method in which ink droplets are ejected from fine discharge ports and landed on a recording material to perform recording , and a black image formed by the ink jet method.
For forming a multicolor image including a black image, and a multicolor image including a black image
Improves the density and fixability of black images in images
About the method .

[0002]

2. Description of the Related Art An ink jet recording method has the advantages that noise during recording is small and a high-resolution recorded image can be obtained at a high speed by using a highly integrated head. As an ink used in such an ink jet recording method, a dye-based ink in which various water-soluble dyes are dissolved in water or a mixture of water and an organic solvent has been used. However, images recorded with dye-based inks often have problems with fastness such as light fastness and water fastness. In particular, black, which is often used in official documents and the like, has been required to have particularly fastness as compared with other colors. On the other hand, pigment-based inks in which a pigment dispersion obtained by dispersing a pigment in a polymer dispersant is dissolved in a water-soluble solvent are disclosed in JP-A-56-147859 and JP-A-56-147860.
It is disclosed in gazettes and the like. Since pigment-based inks are remarkably excellent in both water resistance and light fastness, various pigment-based inks have been studied and disclosed in JP-A-4-57859 and JP-A-4-559.
JP 7860 and the like disclose an ink in which a pigment and a dye are used in combination.

[0003]

However, in the case of the dye-based ink, the dye develops color by dyeing on the recording material, so that the surface condition of the recording material has little effect on the image density. In the case of a pigment-based ink, the pigment is aggregated and fixed on the surface of the recording material to form a color, so that the surface condition of the recording material greatly affects the image density.

[0004] For this reason, the pigment-based ink has the disadvantage that the image density is significantly deteriorated depending on the type of the recording material, and the image quality is impaired. In particular, plain paper such as copy paper, bond paper, and the like generally used in offices and the like, unlike the specialty paper for inkjet, has a problem in the image density of the pigment-based ink because the surface state of the paper is not uniform.

[0005] JP-A-3-240557, JP-A-3-24
In 0558, before or after the pigment-based ink is ejected, an ink jet recording method for ejecting a solution having an action of thickening the ink to thicken the ink to obtain a recorded image with good fixability without bleeding is provided. Although disclosed, this method has a disadvantage that it takes time until the ink is fixed because the ink is thickened on the recording paper. Further, depending on only the thickening, the pigment cannot be completely left on the recording paper, so that good image density may not be obtained in some cases.

[0006] Further, the ink for ink jet recording is
Unlike stationery inks, they are required to have ejection stability, long-term storage stability, and properties that do not solidify at the tip of a fine nozzle. It is contradictory.

Accordingly, the present invention solves the above-mentioned problems and provides a pigment-based ink while maintaining the discharge stability, long-term storage stability, and the property of not being solidified at the tip of a fine nozzle, which are required for ink for ink-jet recording. It is an object of the present invention to provide a recording image having a sufficient print density on all types of paper including plain paper and having excellent fastness by increasing the cohesiveness of the ink on the surface of the recording material. In particular, it is an object of the present invention to provide a black print having a sufficient print density on all paper surfaces and excellent in fastness. The present invention also provides a black image
Inkjet method with improved density and fixability
To form a multicolor image including a black image by using the method
With the goal. The invention is further directed to an inkjet method.
Density of a black image in a multicolor image including a black image and
The purpose is to improve the fixing property.

[0008]

In order to achieve the above object, the present invention provides a pigment-based black ink and a dye-based color ink.
And applying the energy to each of the inks and ejecting them as ink droplets from the ejection openings to form a multicolor image including a black image.
An inkjet recording method with that step, said pigment
Of the dye-based color ink and the dye-based color ink
Is landed on the recording material so that the two intersect on the recording material.
It is allowed and a step of forming the said black image, the pigment-based Bra
The dye-based color ink to be mixed with
Is lower, when the intersects with the drop of the pigment-based black ink
In addition, the dispersion state of the pigment-based black ink becomes unstable
An ink jet recording method, wherein those.

Further, the present invention relates to a pigment-based black ink.
By applying energy to each of the dye-based color inks and ejecting them as ink droplets from the ejection openings, multiple
An ink jet recording method having a step of forming a color image , wherein the pigment-based black ink droplets and the dye-based
Ink droplets so that they intersect on the recording material
Forming a black image by landing on the recording material.
And the dye-based color to be mixed with the pigment-based black ink.
-The ink contains salt and intersects with the pigment black ink.
The dispersion state of the pigment-based black ink is unstable
An ink jet recording method is characterized in that one that of.

Further, the present invention includes that the pigment-based ink has at least a pigment dispersion, a water-soluble organic solvent and water as constituents, and that the pigment-based ink is black.

Further, the present invention includes that the dye-based ink has at least a water-soluble dye, a water-soluble organic solvent and water as constituents, and that the dye-based ink is cyan, magenta or yellow.

Further, the present invention provides a pigment-based black ink,
For cyan, magenta and yellow dye-based color inks
Is discharged as an ink droplet from the discharge port by applying energy to each landed the ink droplets onto a recording material black
An ink jet recording method for recording a color image including an image, wherein at least one of the dye-based color inks is used.
And a drop of the pigment black ink on the recording material.
To form the black image by landing on the recording material
A dye to be mixed with the pigment-based black ink
PH inks have a pH of 4 or less, and the pigment
When the pigment-based black ink is
An ink jet recording method characterized in that the dispersion state becomes unstable .

Further, the present invention provides a pigment-based black ink,
For cyan, magenta and yellow dye-based color inks
Is discharged as an ink droplet from the discharge port by applying energy to each landed the ink droplets onto a recording material black
An ink jet recording method for recording a color image including an image, wherein at least one of the dye-based color inks is used.
And a drop of the pigment black ink on the recording material.
To form a black image by landing on the recording material
The dye-based ink to be mixed with the pigment-based black ink
The color ink contains a salt, and the pigment-based black ink
When they intersect, the dispersion state of the pigment black ink is
An ink jet recording method characterized by being unstable . In addition, the present invention provides a method for producing a composition comprising:
Has a color tone of cyan, magenta or yellow, and
The density of a black image contained in a multicolor image formed by applying a color ink containing a dye as a color ink and a black ink containing a pigment as a color material on a recording material using an inkjet method, and the recording material. A method of improving the fixability to a recording medium, wherein the color ink is applied to an area where a black image is to be formed on the recording material before or after the black ink is applied to the area. The black ink droplet and the color ink
The black ink on the recording material,
A method for improving the density and fixability of a black image, characterized by destabilizing the dispersion state of the black image. The present invention also includes a salt, a cyan, magenta or yellow color.
Black ink contained in a multicolor image formed by applying a color ink containing a dye as a color material and a black ink containing a pigment as a color material onto a recording material using an ink-jet method. A method for improving the density of an image and the fixability to a recording material, wherein a black image on the recording material is to be formed, before or after applying the black ink to the region. Controlling the application of the color ink so as to apply a drop of the black ink.
And a drop of the color ink on the recording material,
This is a method for improving the density and fixability of a black image, characterized by destabilizing the dispersion state of black ink .

[0014]

The present inventors have conducted intensive studies on the relationship between the surface condition of the recording material and the image density, and have obtained the following findings.

Immediately after the pigment ink reaches the surface of the recording material, the pigment is aggregated and stays on the surface of the recording material, so that a color image is obtained. Therefore, if the surface state of the recording material makes the dispersion state of the pigment-based ink unstable, sufficient image density can be obtained, and conversely, the dispersion state of the pigment-based ink is stable, and If the permeation of the ink into the material takes precedence, a sufficient image density cannot be obtained.

On the other hand, so-called plain paper widely used in offices and the like is roughly classified into acidic paper and neutral paper, and has various surface states according to the use.

The properties required for ink jet recording ink, such as ejection stability, long-term storage stability, and prevention of solidification at the fine nozzle tip, require dispersion stability of the pigment-based ink. It has the opposite property to the aggregation on the recording material.

The inventors of the present invention have found that the dispersion stability of pigment-based inks is remarkably deteriorated in an acidic region having a pH of 4 or less or in the presence of a small amount of salt.
The present inventors have found that ejection stability, long-term storage stability, and the property of not solidifying at the tip of a fine nozzle are maintained by selecting a dye or a solvent, and the present invention has been accomplished.

According to the present invention constituted as described above, a pigment-based ink having good dispersion stability crosses an acidic or salt-containing dye-based ink on a recording material, whereby a stable dispersion state is obtained. It is possible to obtain a sufficient image density by breaking, instantaneously aggregating, and fixing to the surface of the recording material. Further, by setting the pigment-based ink to black and the dye-based ink to be overlaid on the pigment-based ink to one of cyan, magenta, and yellow, for example, a black image excellent in image density and fastness can be obtained. Further, by using a pigment-based black ink and dye-based inks of three colors of cyan, magenta and yellow, a black image having excellent image density and fastness can be obtained even in a color image.

Hereinafter, an ink suitable for the present invention will be described.

The pigment-based black ink preferably comprises at least a pigment dispersion, a water-soluble organic solvent and water.

The pigment dispersion is obtained by dispersing a pigment in a polymer dispersant.

As the pigment, carbon black is preferable. Particularly, the pigment is produced by a furnace method or a channel method, and has a primary particle diameter of 15 to 40 mμ and a specific surface area of 50% by a BET method.
~ 300m ² / g, DBP oil absorption 40 ~ 150ml / 1
Carbon black having 00 g, a volatile content of 0.5 to 10% and a pH of 2 to 9 is preferred. As such carbon black, NO. 2300, NO. 900, MCF. 8
8, NO. 33, NO. 40, NO. 45, NO. 5
2, MA7, MA8, NO. 2200B (Mitsubishi Chemical), RAVE 1255 (Columbia), REG
AL400R, REGAL330R, REGAL660
R, MOGUL L (all made by Cabot), Colo
r Black FW1, Color Black F
W18, Color Black S170, Colo
r Black S150, Printex 35, P
A commercially available product such as printx U (above, manufactured by Tegussa) may be used, or a newly manufactured product may be used.

The polymer dispersant is preferably a water-soluble resin, and has a weight average molecular weight of 1,000 to 3,000.
0, especially 3000-15000 resins are preferred.
For example, styrene, styrene derivatives, vinyl naphthalene, vinyl naphthalene derivatives, esters of α, β-ethylenically unsaturated carboxylic acids and aliphatic alcohols, acrylic acid, acrylic acid derivatives, maleic acid, maleic acid derivatives, itaconic acid, itacone A block copolymer, a graft copolymer or random, which is composed of at least two or more monomers selected from acid derivatives, fumaric acid, fumaric acid derivatives, and is soluble in an aqueous solution in which a base is dissolved and an alkaline solution. Examples of the dispersant include a copolymer, a salt thereof, a homopolymer composed of a hydrophilic monomer or a salt thereof, and a water-soluble resin such as polyvinyl alcohol, carboxymethyl cellulose, and a condensate of naphthalenesulfonic acid and formaldehyde. In particular, an alkali-soluble resin has the advantage that the viscosity of the dispersion can be reduced and the dispersion is easy. Further, a resin which starts aggregation at a pH of 6 or less is particularly preferable for improving the image density.

The dispersing agent is used in an amount of 0.1 to
It is preferable to use 5% by weight. In the present invention,
In order to improve the solubility of the dispersant and improve long-term storage properties, it is preferable to adjust the entire ink to neutral to alkaline. However, in this case, p is set to such an extent that various members used in the ink jet recording apparatus are not corroded.
H7 to 10 is preferred. The pH is adjusted by appropriately adding various surfactants, a solvent for imparting permeability, and the like.

Examples of the surfactant include anionic surfactants such as fatty acid salts, higher alcohol sulfates, alkylbenzene sulfonates and higher alcohol phosphates, and cationic surfactants such as aliphatic amine salts and quaternary ammonium salts. Activator, higher alcohol ethylene oxide adduct, alkylphenol ethylene oxide adduct, aliphatic ethylene oxide adduct, polyhydric alcohol fatty acid ester ethylene oxide adduct, higher alkylamine ethylene oxide adduct, fatty acid amide ethylene oxide adduct, polypropylene glycol Use nonionic surfactants such as ethylene oxide adducts, fatty acid esters of polyhydric alcohols, fatty acid amides of alkanolamines, and amino acid type or betaine type surfactants. It is possible. In particular, nonionic surfactants such as higher alcohol ethylene oxide adduct, alkylphenol ethylene oxide adduct, ethylene oxide-propylene oxide copolymer, and ethylene oxide adduct of acetylene glycol are preferable. More preferably, the addition mole number of the ethylene oxide adduct is from 4 to 20.

The amount of the surfactant added is 0.01 to 1
It is preferably set to 0%. If it is less than 0.01%, the permeability is generally low, depending on the type of surfactant,
%, It is not preferable because the initial viscosity of the ink increases.

Examples of the solvent for imparting permeability include ethers such as tetrahydrofuran and dioxane, lower alkyl ethers of polyhydric alcohols such as ethylene glycol methyl ether, diethylene glycol monomethyl ether and triethylene glycol monomethyl ether, ethanol, isopropyl alcohol and the like. Is preferred. The content of these is preferably 0.1% to 20% of the total amount of the ink. If the content is less than 0.1%, depending on the type of the solvent,
In general, when the permeability is small and exceeds 20%, the solubility of the colorant is slightly lowered, which is not preferable.

Examples of the water-soluble organic solvent include amides such as dimethylformamide and dimethylacetamide, ketones such as acetone, polyalkylene glycols such as polyethylene glycol and polypropylene glycol, ethylene glycol, propylene glycol, butylene glycol, and triethylene glycol. Alkylene glycols such as 1,2,6-hexanetriol, thiodiglycol, hexylene glycol and diethylene glycol; lower alkyl ethers of polyhydric alcohols such as ethylene glycol methyl ether, diethylene glycol monomethyl ether and triethylene glycol monomethyl ether; Monohydric alcohols such as ethanol and isopropyl alcohol, glycerin, n-methyl-2-pyrrolidone, 3 Jimechiru-2-imidazolidinone, triethanolamine, sulfolane, dimethyl monkey sulfoxide and the like can be used. These water-soluble organic solvents are used to prevent solidification and clogging of the ink at the tip of the nozzle.
It is preferably contained at 80% by weight.

As the water, ion-exchanged water is preferable, not water containing various ions.
Preferably, it is contained at 90%.

In order to obtain desired physical properties, an antifoaming agent, a preservative and the like may be added as required in addition to the above components.

The dye-based ink comprises at least a water-soluble dye, water and a water-soluble organic solvent.

As the water-soluble dye, those used in a usual ink jet recording method can be used. For example, cyan ink: C.I. I. Basic Blue 41,
C. I. Basic Blue 75, C.I. I. IRE
ct Blue 86, C.I. I. Direct Blue
199, C.I. I. Acid Blue 9, Magenta Ink: C.I. I. Basic Red 27,
C. I. Basic Red 46, C.I. I. Basic
Red 29, C.I. I. Acid Red 35, C.I.
I. Acid Red 37, yellow ink: C.I. I. Basic Yellow2
4, C.I. I. Basic Yellow 51, C.I. I. B
asic Yellow 67, C.I. I. Direct
Yellow 86, C.I. I. Direct Yellow
w142, C.I. I. Acid Yellow, Direct Dye and Basic Dye described in Color Index such as Acid Yellow 23. In addition, any dye not described in the color index can be used as long as it is a water-soluble dye.

The water-soluble organic solvent and water are the same as in the pigment black ink.

Further, in order to obtain desired physical properties, a surfactant, an antifoaming agent, and a preservative may be added as required in addition to the above components.

The above-mentioned dye-based ink is adjusted to pH 4 or less in order to promote the aggregation of the pigment-based ink. The adjusting method includes a method of adding an acid such as acetic acid and hydrochloric acid as necessary. There is a method using a basic dye.

Further, even if the pH of the dye-based ink is not adjusted to 4 or less, the aggregation of the pigment-based ink can be promoted by adding a salt to the dye-based ink. Needless to say, even when a salt is contained, the pH may be 4 or less.

[0038] Such salts include sodium chloride,
Hydrochloride such as potassium chloride, lithium chloride, ammonium chloride, calcium chloride, magnesium chloride, barium chloride, carbonate such as calcium carbonate, magnesium carbonate, barium carbonate, sodium carbonate, lithium carbonate, ammonium carbonate, sodium acetate, potassium acetate, Acetates such as lithium acetate, sulphates such as sodium sulphate, potassium sulphate and aluminum sulphate, furthermore nitrates, sulphites and nitrites can be used. However, it dissolves in water,
It is not limited to the above as long as it ionizes.

Next, a recording apparatus suitable for the recording method of the present invention will be described.

In the present invention, it is preferable to use a device which applies thermal energy corresponding to a recording signal to ink in a chamber of a recording head and generates ink droplets by the thermal energy.
FIGS. 1, 2 and 3 are schematic views showing examples of the configuration of a head which is a main part of a recording apparatus suitable for the present invention.

FIG. 1 shows a recording head 1 along an ink flow path.
3 is a sectional view, and FIG. 2 is a cross-sectional view taken along a line AB in FIG.

The recording head 13 includes a glass, ceramics or plastic plate having a groove 14 through which ink passes, and a heating head 15 used for thermal recording (a head is shown in the drawing, but is not limited to this). ) Are adhered. The heating head 15 includes a protective film 16 made of silicon oxide or the like, and 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.

The ink 21 has a discharge orifice (fine hole) 2
2, and the meniscus 23 is formed by the pressure P.

When an electric signal is applied to the electrodes 17-1 and 17-2, the area of the heating head 15 indicated by n rapidly generates heat, and bubbles are generated in the ink 21 in contact with the area. The meniscus 23 projects due to the pressure, the ink 21 is ejected, becomes an ink droplet 24 from the orifice 22, and flies toward the recording material 25.

FIG. 3 is an external view of a multi-head in which many heads shown in FIG. 1 are arranged. 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 such a 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 disposed at a position adjacent to a recording area of the recording head, and in this example, is held in a form protruding into the movement path of the recording head. Reference numeral 62 denotes a cap, which is disposed at a home position adjacent to the blade 61, and has a configuration in which the cap moves in a direction perpendicular to the direction in which the print head moves and comes into contact with the ejection port surface to perform capping. Further, an absorber 63 is provided adjacent to the blade 61 and, like the blade 61, is held in a form protruding into the movement path of the recording head. The blade 61, the cap 62, and the absorber 63 constitute an ejection recovery section 64,
The blade 61 and the absorber 63 remove water, dust, and the like from the ink ejection port surface. A recording head 65 having ejection energy generating means for ejecting ink onto a recording material facing an ejection port surface provided with ejection ports to perform recording;
Reference numeral denotes a carriage on which the recording head 65 is mounted to move the recording head 65. The carriage 66 has the guide shaft 6
7 is slidably engaged, and a part of the carriage 66 is connected to a belt 69 driven by a motor 68 (not shown). As a result, the carriage 66 can move along the guide shaft 67, and the recording head 65 can move the recording area and the adjacent area.

Reference numeral 51 denotes a paper feed unit for inserting a recording material,
Reference numeral 2 denotes a paper feed roller driven by a motor (not shown). With such a configuration, the recording material is fed to a position facing the ejection port surface of the recording head, and is discharged to a discharge section provided with a discharge roller 53 as recording proceeds.

In the above configuration, when the recording head 65 returns to the home position at the end of recording or the like, the cap 62 of the head recovery unit 64 is retracted from the moving path of the recording head 65, but the blade 61 protrudes into the moving path. I have. 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 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. Position, and the wiping is performed along with the movement.

FIG. 5 is a diagram showing an example of an ink cartridge containing ink supplied to the head via an ink supply member, for example, a tube. Here, reference numeral 40 denotes an ink storage portion that stores the supply ink, for example, an ink bag, and a rubber stopper 42 is provided at the tip thereof. By inserting a needle (not shown) into the stopper 42, the ink in the ink bag 40 can be supplied to the head. 44
Is an absorber for receiving 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 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 suitably used in an integrated one as shown in FIG.

In FIG. 6, reference numeral 70 denotes a recording unit, in which an ink storage portion for storing ink, for example, an ink absorber is stored, and the ink in the ink absorber has a plurality of orifices. Head part 71
Are ejected as ink droplets from the ink. As the material of the ink absorber, it is preferable for the present invention to use polyurethane. 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.

As described above, the recording apparatus according to the present invention is not limited to the above example, and may be, for example, a piezo-type ink jet recording apparatus using a piezoelectric element.

FIG. 7 is a schematic diagram showing an example in which four recording heads shown in FIG. 3 are used side by side on a carriage. 8
1, 82, 83 and 84 are yellow, magenta,
This is a recording head for ejecting cyan and black inks. The head is mounted on the recording device described above,
Each color ink is ejected according to the recording signal. FIG. 7 shows an example in which four recording heads are used. However, the present invention is not limited to this. As shown in FIG.
A method of supplying magenta, cyan, and black separately through the liquid flow path may be used.

In any of the head configurations, when a black recording signal is received, the dye-based ink is configured to land on the same location as the black ink before or after black is printed. Either of the landing orders may be performed first. However, when the black ink and the other ink are landed with little time difference, it is preferable to land the black ink first because the fixing of the ink to the paper becomes faster.

The ink droplet volume of the dye-based ink to be superimposed on the black ink is preferably as small as possible within a range that does not cause any problem when an image is formed alone, since the fixability of the overprinted ink is improved. Also, the size of the ink cartridge can be reduced. The volume of the ink droplet can be reduced by increasing the dot diameter by adding a surfactant, a permeable solvent, and the like.

[0058]

The present invention will be described below in detail with reference to examples. Unless otherwise specified, “parts” and “%” are based on weight. (1) Preparation of black ink B1 1) Preparation of pigment dispersion

[0059]

[Table 1] Mix the above ingredients and heat to 70 ° C in a water bath,
The resin was completely dissolved. To this solution, 10 parts of carbon black (MCF88 manufactured by Mitsubishi Kasei) and 1 part of isopropyl alcohol were added, and premixing was performed for 30 minutes.
Next, a dispersion treatment was performed for 3 hours using zirconium beads having a diameter of 1 mm, and further a centrifugation treatment (12000 rpm) was performed.
m, 20 minutes) to remove coarse particles and obtain a dispersion 1
And

2) Preparation of ink

[0061]

[Table 2] The above components were mixed, and the pH was adjusted to 8 to 10 by further adding monoethanolamine to obtain a black ink B1. (2) Preparation of black ink B2 1) Preparation of pigment dispersion

[0062]

[Table 3] Mix the above ingredients and heat to 70 ° C in a water bath,
The resin was completely dissolved. 15 parts of carbon black (MCF88 manufactured by Mitsubishi Kasei) was added to this solution, and premixing was performed for 30 minutes. Next, dispersion treatment was performed using glass beads having a diameter of 1 mm for 3 hours, and further centrifugation treatment (12000 rpm, 20 minutes) was performed to remove coarse particles, thereby obtaining dispersion liquid 2.

2) Preparation of ink

[0064]

[Table 4] The above components were mixed, and aminomethylpropanol was further added to adjust the pH to 8 to 10, to obtain a black ink B2. (3) Preparation of black ink B3 1) Preparation of pigment dispersion

[0065]

[Table 5] Mix the above ingredients and heat to 70 ° C in a water bath,
The resin was completely dissolved. To this solution, 11 parts of carbon black (S170, manufactured by Tegussa) and 1 part of isopropyl alcohol were added, and premixing was performed for 60 minutes. Then, using zirconium beads having a diameter of 0.5 mm, 1
Dispersion treatment was performed for 0 hours, followed by centrifugation (12000).
rpm, for 20 minutes) to remove coarse particles to obtain a dispersion 3.

2) Preparation of ink

[0067]

[Table 6] The above components were mixed, and the pH was adjusted to 8 to 10 with the addition of monoethanolamine to obtain a black ink B3. (4) Preparation of dye-based ink 1) Preparation of ink containing salt

[0068]

[Table 7]

[0069]

[Table 8]

[0070]

[Table 9] After mixing the above components for each of yellow, magenta and cyan, the mixture was filtered under pressure through a membrane filter having a pore size of 0.22 μm (trade name: Fluoropore Filter, manufactured by Sumitomo Electric Industries, Ltd.), and yellow ink Y1, magenta ink M1, A cyan ink C1 was obtained.

2) Preparation of ink having a pH of 4 or less

[0072]

[Table 10]

[0073]

[Table 11]

[0074]

[Table 12] After mixing and dissolving the above components for each of yellow, magenta and cyan, acetic acid was added to adjust the pH to 3, 3.5 and 2.5, respectively. This solution was filtered through a membrane filter having a pore size of 0.22 μm (trade name: Fluoropore Filter, manufactured by Sumitomo Electric Industries, Ltd.) to obtain a yellow ink Y2, a magenta ink M2, and a cyan ink C2.
I got (5) Recording Examples 1 to 12 Using the inks prepared as described above, two types of copy paper (Xerox 4024 of Xerox, N of Canon)
P-DRY) was recorded with alphanumeric characters and solid portions by an ink jet recording method. As the recording head, the same recording head as that mounted on a Canon inkjet printer BJC820 was used. Fig. 4 shows two recording heads.
7 are arranged in parallel as shown in FIG. 7 on the carriage of the recording apparatus, and the recording conditions such as the ejection order (equivalent to the landing order) and the ink droplet volume are changed as shown in Table 14 to change the pigment black ink. And a yellow, magenta or cyan dye-based ink were landed on the same spot.
However, the conditions for energizing the heaters for applying thermal energy to the ink were all constant, the applied voltage was 28 V, the pulse width was 3.2 μsec, and the driving frequency was 5 kHz. (6) Comparative Examples Comparative Examples 1 to 3 Each of the black inks B1 to B3 was independently used to record on two types of paper in the same manner as in the example.

Comparative Example 4 A yellow ink Y3 was prepared and recorded in the same manner as in the example except that NaNO ₃ was omitted from the components shown in Table 4.

Comparative Example 5 A magenta ink M3 was prepared in the same manner as in the example except that AgNO ₃ was omitted from the components shown in Table 5, and recording was performed in the same manner.

Comparative Example 6

[0078]

[Table 13] After mixing the above components, the mixture was filtered under pressure through a membrane filter having a pore size of 0.22 μm (trade name: Fluoropore Filter, manufactured by Sumitomo Electric Industries, Ltd.) to obtain a black ink B4. Recording was performed in the same manner as in the example using black ink B4. (7) Evaluation of Recorded Image The recorded image was evaluated as follows.

1) Image density The recording density of a recorded image consisting of alphanumeric characters and a solid portion left for one hour after printing was measured with a Macbeth RD915 (trade name, manufactured by Macbeth Co.), and was found to be 1.25 or more. ○ indicates that the concentration was less than 1.25 and 1.15 or more, and Δ indicates that the concentration was less than 1.15.

2) Fixing time After recording a solid block of 0.5 cm × 1 cm, a silbon paper was superimposed on the recording surface at regular intervals, and 75 g of the paper was placed on the surface.
/ Cm ² and rubbed with a weight of / cm ² to observe the condition of the stain on the silk paper. As a result, those that do not adhere in 10 seconds or less (including those in 10 seconds) ◎ Those that do not adhere in 10 to 20 seconds (including those in 20 seconds) ○ In 20 to 40 seconds Those that did not adhere (including those for 40 seconds) were marked with x, those that took more than 40 seconds and did not adhere.

Table 14 shows the evaluation results.

[0082]

[Table 14]

[0083]

According to the present invention, the image density of a pigment-based ink can be improved by utilizing the ability of the dye-based ink to adhere to a recording member, particularly paper. Therefore, an image with high image quality and high robustness can be obtained.

Further, by using black ink for the pigment ink and any of cyan, magenta and yellow for the dye ink to be superimposed on the black ink, not only the image density and the fastness are improved, but also the unique tint is improved. Can be obtained.

Further, according to the present invention, the above effects can be obtained for any recording paper including plain paper.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing an example of a liquid flow path of a recording head suitable for the present invention.

FIG. 2 is a cross-sectional view of the recording head shown in FIG. 1 taken along section line AB.

FIG. 3 is a perspective view showing one embodiment of a recording head having a large number of ink ejection ports.

FIG. 4 is a perspective view showing one embodiment of an ink jet recording apparatus suitable for the present invention.

FIG. 5 is a side sectional view showing one embodiment of an ink cartridge.

FIG. 6 is a perspective view illustrating one embodiment of a recording unit.

FIG. 7 is a perspective view showing an example of the arrangement of a plurality of recording heads.

FIG. 8 is a perspective view showing one embodiment of a recording head having a plurality of liquid chambers.

[Explanation of symbols]

 13 Recording Head 15 Heating Head 21 Ink 22 Discharge Port 23 Meniscus 24 Ink Drop 25 Recording Material 40 Ink Bag 44 Ink Absorber 45 Ink Cartridge 61 Wiping Member 65 Recording Head 66 Carriage 70 Recording Unit 71 Head Unit 72 Air Communication Hole

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masahiko Tongaki 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Akio Kashiwazaki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon (56) References JP-A-64-58583 (JP, A) JP-A-3-240557 (JP, A) JP-A-1-188394 (JP, A) JP-A-2-255875 (JP, A) A) JP-A-3-210373 (JP, A) JP-A-4-59880 (JP, A) JP-A-5-208548 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) ) B41M 5/00 B41J 2/21

Claims (22)

(57) [Claims] 1. A pigment-based black ink and a dye-based color ink.
Energy to each ink and eject it as ink droplets from the ejection port to form a multi-color image including a black image
An inkjet recording method comprising the step of, the the pigment-based black ink droplets and the dye-based color ink
Droplet onto the recording material so that the two intersect on the recording material.
Forming a black image by landing the dye-based color ink to be mixed with the pigment-based black ink.
Link is at pH4 or less, drop of the pigment-based black ink
When the pigment black ink is dispersed
An ink jet recording method characterized in that the ink becomes unstable . 2. A pigment-based black ink and a dye-based color ink.
Energy to each ink and eject it as ink droplets from the ejection port to form a multi-color image including a black image
An inkjet recording method comprising the step of, the the pigment-based black ink droplets and the dye-based color ink
Droplet onto the recording material so that the two intersect on the recording material.
Forming a black image by landing the dye-based color ink to be mixed with the pigment-based black ink.
Ink contains salt, and when crossed with the pigment-based black ink
The dispersion state of the pigment black ink becomes unstable
The ink jet recording method which is a shall. 3. The ink jet recording method according to claim 1, wherein the pigment ink has at least a pigment dispersion, a water-soluble organic solvent, and water as constituents. 4. A dye-based ink-jet recording method according to claim 1乃<br/> Optimum 3 any one having a component at least a water-soluble dye, a water-soluble organic solvent and water. 5. The ink jet recording method according to claims 1 to 4 any one dye-based inks cyan, magenta or yellow. 6. Black pigment ink, cyan, magenta
Energy is applied to each of the dye and yellow dye-based color inks and ejected as ink droplets from the ejection openings, and the ink droplets land on a recording material to form a color containing a black image.
An ink jet recording method for recording an image, comprising: at least one droplet of the dye-based color ink and the pigment-based color ink.
Recorded so that the black ink drops intersect with the recording material
Forming a black image by landing on a recording material, wherein the dye-based color ink is mixed with the pigment-based black ink.
Has a pH of 4 or less and exchanges with the pigment-based black ink.
When the pigment black ink disperses,
An ink jet recording method characterized by being stabilized . 7. A pigment-based black ink, cyan, magenta
Energy is applied to each of the dye color inks of yellow and yellow to be ejected from the ejection ports as ink droplets, and the ink droplets are landed on a recording material to form a color image including a black image. An inkjet recording method for performing recording , comprising: at least one droplet of the dye-based color ink and the pigment-based color ink.
Recorded so that the black ink drops intersect with the recording material
A step of forming a black image by landing on a recording material, wherein the dye-based color ink is mixed with the pigment-based black ink.
The ink contains salt and crosses with the pigment-based black ink.
The dispersion state of the pigment black ink becomes unstable
The ink jet recording method which is a shall. 8. The ink jet recording according to claim 7 , wherein the salt is at least one selected from a hydrochloride, a carbonate, an acetate, a sulfate, a nitrate, a sulfite and a nitrite.
Method. 9. The inkjet according to claim 8 , wherein the hydrochloride is at least one selected from sodium chloride, potassium chloride, lithium chloride, ammonium chloride, calcium chloride, magnesium chloride, and barium chloride.
Recording method. 10. The ink jet recording method according to claim 8 , wherein the carbonate is at least one selected from calcium carbonate, magnesium carbonate, barium carbonate, sodium carbonate, lithium carbonate and ammonium carbonate . 11. The ink jet recording method according to claim 8 , wherein said acetate is at least one selected from sodium acetate, potassium acetate and lithium acetate. 12. The method according to claim 1, wherein said sulfate is at least one selected from sodium sulfate, potassium sulfate and aluminum sulfate.
Inkjet Symbol recording method according to claim 8 One in which. 13. The ink jet recording method according to claim 6 , wherein the black ink contains an aqueous medium, carbon black as a pigment, and a polymer dispersant.
Law. 14. The ink jet recording method according to claim 13 , wherein the polymer dispersant is a water-soluble resin having a weight average molecular weight of 1,000 to 30,000 . 15. The ink jet recording method according to claim 14 , wherein the polymer dispersant is a water-soluble resin having a weight average molecular weight of 3,000 to 15,000 . 16. The polymer dispersant is styrene, a styrene derivative, vinyl naphthalene, a vinyl naphthalene derivative, an ester of an α, β-ethylenically unsaturated carboxylic acid and an aliphatic alcohol, acrylic acid, an acrylic acid derivative,
Maleic acid, maleic acid derivatives, itaconic acid, itaconic acid derivatives, Burroku copolymer comprising at least two monomers selected from fumaric acid and fumaric acid derivatives, claims a graft copolymer or a random copolymer 13 Ink jet recording according to any one of to 15
Recording method. 17. polymer dispersant is a styrene - acrylic acid - claim butyl acrylate copolymer from 1:13
7. The inkjet recording method according to any one of 6 . 18. The polymer dispersant is a styrene-maleic acid-maleic acid half ester copolymer.
Ink jet recording method according to any one of 13 to 16
Law. 19. The polymer dispersant is at least one selected from the group consisting of polyvinyl alcohol, carboxymethyl cellulose, and naphthalenesulfonic acid formamide condensate.
The ink jet according to any one of claims 13 to 16 , wherein
Jet recording method. 20. The ink jet recording method according to claim 19 , wherein the polymer dispersant is a sodium salt of β-naphthalenesulfonic acid formamide condensate . 21. Cyan and magenta having a pH of 4 or less
Or have a yellow color tone and contain a dye as a coloring material.
Color ink and a black ink containing a pigment as a coloring material are each applied to a recording material by using an ink jet method, and thereby the density of the black image contained in the multicolor image formed and the fixability to the recording material are improved. A method for improving the method, wherein the color ink is controlled to be applied to an area of the recording material on which a black image is to be formed, before or after applying the black ink to the area. The bra
The ink ink droplet and the color ink droplet on the recording material.
The black ink dispersion state.
A method for improving the density and fixability of a black image. 22. Salt containing cyan, magenta or
It has a yellow color tone and contains a dye as a coloring material.
Ink and a black ink containing a pigment as a coloring material, each of which is applied to the recording material using an ink jet method, to thereby determine the density of the black image contained in the multicolor image and the fixability to the recording material. A method for improving the method, wherein the color ink is controlled to be applied to an area of the recording material on which a black image is to be formed, before or after applying the black ink to the area. The bra
The ink ink droplet and the color ink droplet on the recording material.
The black ink dispersion state.
A method for improving the density and fixability of a black image.