JP2020073692A - Ink set, ink cartridge, ink jet recording method and inkjet recording device - Google Patents

Abstract

To provide an ink set exhibiting a smaller color difference in an image obtained by forward scan recording and backward scan recording, even if used in bi-directional recording by an inkjet system.SOLUTION: An ink set includes at least two kinds of ink each containing: a coloring material; an organic solvent; and water, the ink set to be used in bi-directional recording by an inkjet system. A content of the organic solvent in the entire ink is 30 mass% or more. The ink set has 0.5 or more of a relative displacement degree difference of a maximum value and a minimum value of relative displacement degrees (a maximum value of relative displacement degrees minus a minimum value of relative displacement degrees) of the coloring material in the entire ink, obtained, using thin layer chromatography, by developing the coloring material with the organic solvent in the entire ink as a developing solvent.SELECTED DRAWING: None

Description

  The present invention relates to an ink set, an ink cartridge, an inkjet recording method, and an inkjet recording device.

  The inkjet recording method has a simple recording process, low cost, multi-color printing, non-contact printing that enables overprinting, which makes it easy to improve printing quality, and high-speed printing without noise makes it suitable for household use. Widely used from printers to commercial printers.

In the ink jet recording method, since a low viscosity ink is adhered to a recording medium for recording, it is known that the color development varies depending on the fixing state of the dye in the ink on the recording medium.
When printing using an ink set having a plurality of color inks containing dyes as color materials, the color material in the ink that has landed first on the recording medium is fixed to the surface layer side of the recording medium, and the ink that landed afterwards It is known that the coloring material in the inside is hard to fix on the surface side of the recording medium, and is fixed to the lower side in the thickness direction of the recording medium than the coloring material in the ink that has landed first.

  Therefore, when bidirectional printing is performed using a plurality of colors of ink, the order in which ink is landed on the printing medium differs between forward scan printing and backward scan printing, and a color difference (bidirectional color difference) occurs in the formed image. There is a problem.

  Therefore, in the recording head, the ejection openings are arranged so that the ejection openings of the ink are symmetrical with respect to the main scanning direction, and even if the ink is ejected in the forward scanning recording and the backward scanning recording, the ink landing on the recording medium An ink jet recording apparatus has been proposed in which the order is the same and an image with a small color difference due to bidirectional printing can be obtained (for example, refer to Patent Document 1). Further, an ink jet recording head has been proposed in which only ejection ports having a large ejection amount are arranged symmetrically with respect to the main scanning direction, and an image with a small color difference due to bidirectional printing is obtained (see, for example, Patent Document 2). ).

  It is an object of the present invention to provide an ink set having a small color difference in images obtained by forward scan recording and backward scan recording even when used for bidirectional printing by an inkjet method.

  The ink set of the present invention as a means for solving the above problems is a color material, an organic solvent, and an ink set having an ink containing water, the content of the organic solvent in all the ink is Of 30% by mass or more, and the relative mobility of the coloring materials in all the inks obtained by developing the coloring materials using the organic solvent in the ink as a developing solvent using thin layer chromatography. The relative mobility difference between the maximum value and the minimum value (the maximum value of the relative mobility-the minimum value of the relative mobility) is 0.1 or more.

  According to the present invention, it is possible to provide an ink set having a small color difference in images obtained by forward scanning recording and backward scanning recording even when used for bidirectional recording by an inkjet method.

FIG. 1 is a schematic diagram showing the movement of an ink head and the conveyance state of a recording medium in an inkjet recording apparatus of the present invention. FIG. 2 is a schematic diagram showing an example of a recording method for the same recording area in the inkjet recording method of the present invention. FIG. 3 is a plan view of an essential part showing an example of a serial type image forming apparatus. FIG. 4 is a side view for explaining a main part of an example of the liquid ejection unit of the apparatus shown in FIG. FIG. 5 is a side view of a main part showing another example of the liquid ejection unit of the apparatus of FIG. FIG. 6 is a schematic view showing an example of developing a coloring material using thin layer chromatography. FIG. 7 is a photograph of a TLC plate in which the coloring materials used in Examples and Comparative Examples were developed by thin layer chromatography.

(Ink set)
The ink set of the present invention has at least two kinds of inks containing a coloring material, an organic solvent, and water, and the content of the organic solvent in all the inks is 30% by mass or more. By using the organic solvent in the ink as a developing solvent to obtain the color material, the relative mobility difference between the maximum value and the minimum value of the relative mobility of the color material in all the inks. (Maximum relative mobility-minimum relative mobility) is 0.1 or more, and further contains other inks as necessary.
The ink set of the present invention is based on the knowledge that the configuration of the recording head is complicated, a large number of nozzle rows are required, the ink supply system is complicated, and other disadvantages are large as an apparatus.

Moreover, the present inventors have found the following.
Conventionally, since attention has been paid to bleeding immediately after landing, the lateral fixing position is suppressed and bleeding between colors is suppressed by controlling the mobility of the coloring material in the mixed system of water and solvent. However, since the fixing position in the thickness direction of the recording medium after the ink has landed is not taken into consideration, a difference in color development occurs depending on the landing order, and a color difference occurs when bidirectional recording is performed.
According to the present invention, all inks constituting an ink set contain an organic solvent in an amount of 30% by mass or more, and among all inks constituting an ink set, all of the thin-layer chromatography using the organic solvent as a developing solvent At least two types in which the relative mobility difference between the maximum value and the minimum value of the relative mobility of the color material in the ink (the maximum value of the relative mobility-the minimum value of the relative mobility) is 0.1 or more. It was found that by using an ink set composed of the combination of inks described above, it is possible to eliminate the influence on the color development due to the order in which the inks land on the recording medium.
Further, since the ink set of the present invention can eliminate the influence of the order in which ink is landed on the recording medium, even when it is used for bidirectional printing by an inkjet method, it is possible to perform forward scan printing and backward scan printing in bidirectional printing. The color difference of the obtained image can be reduced.
After landing on the recording medium, the water in the ink is rapidly volatilized and the organic solvent permeates the recording medium. Along with the permeation of the organic solvent into the recording medium, the coloring material also permeates into the recording medium, causing the recording medium to move in the thickness direction. At this time, the relative mobility can be used as an index as the amount of movement of the color material in the thickness direction of the recording medium, and the amount of movement of the color material in the thickness direction of the recording medium varies depending on the relative mobility. The increase in the relative mobility increases the penetration of the color material into the recording medium, cancels out the influence of the fixing position of the color material on the recording medium due to the ink landing order on the recording medium, and the relative movement of the color material. By adjusting the amount of movement of the recording medium due to the degree, it is possible to reduce the color difference between the images obtained in the forward scan recording and the backward scan recording even when used in bidirectional recording.
Here, forward scanning recording means forward scanning main scanning recording of main scanning reciprocal recording (bidirectional recording), and backward scanning recording means backward scanning main scanning recording of main scanning reciprocal recording. To do.
Further, in the terms of the present invention, image formation, recording, printing, printing, printing, modeling and the like are synonymous.

The ink used in the ink set of the present invention is not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include inks having a process color such as black ink, cyan ink, magenta ink and yellow ink. Can be mentioned.
A multicolor image can be formed by recording using an ink set in which two or more of the above inks are combined, and a full color image can be formed by using an ink set combining inks having all process colors. Can be formed.

  Examples of the ink having a color other than the process color include red ink, green ink, blue ink, gray ink, light cyan ink, light magenta ink, and dark yellow ink. By using a color other than the process color, it is possible to widen the color gamut of the full-color image and reduce the graininess of the image. In addition, since it is possible to reduce the amount of the process color ink used for producing the secondary color, it is less likely that the recording medium will be improperly absorbed, and beading and bleeding will be reduced to prevent the hue from bending. It is possible to reduce the change in hue during drying.

[Relative mobility difference (maximum relative mobility-minimum relative mobility)]
In thin layer chromatography developed with the organic solvent as the developing solvent, the relative mobility difference between the maximum value and the minimum value of the relative mobilities of the color materials in all the inks (maximum relative mobility-relative mobility). The minimum value of is 0.1 or more, preferably 0.5 or more. When the relative mobility difference (maximum relative mobility-minimum relative mobility) is 0.1 or more, even in the bidirectional recording, the images obtained in the forward scanning recording and the backward scanning recording Color difference can be reduced.
The maximum value of the relative mobility means the largest relative mobility among the relative mobilities of the coloring materials in each ink in the ink set, and the minimum value of the relative mobility means the ink set. Among the relative mobilities of the coloring materials in the inks, the smallest relative mobility is meant.

The relative mobility of the coloring material in thin layer chromatography (hereinafter, also referred to as “Rf value”) can be specifically calculated by the following (1) to (4).
(1) Using a developing thin layer chromatography (TLC) plate, an organic solvent similar to the organic solvent used in the ink is used as a developing solvent. When the ink contains a plurality of organic solvents, the plurality of organic solvents are used as developing solvents in the same mass ratio.
(2) 0.5 μL of the evaluation sample solution diluted with pure water so that the concentration of the coloring material to be measured is 0.5% by mass is applied on the TLC plate.
(3) After the applied evaluation sample liquid is sufficiently dried, the TLC plate is soaked in the vapor of the developing layer containing the developing solvent, and then the TLC plate is immersed in the developing solvent and developed for 15 hours.
(4) After the development, the TLC plate is sufficiently dried, the developed TLC plate is captured by a scanner to form an image, and the obtained image is analyzed using image analysis software to calculate the Rf value of the coloring material.
As the developing thin layer chromatography (TLC) plate, a trade name: unmodified silica gel TLC plate (manufactured by Merck & Co., average layer thickness: 200 μm, plastic sheet) or the like can be used, and as image analysis software, , Software name: Image J can be used.

Calculation of the Rf value of the color material will be described with reference to FIG. FIG. 6 is a schematic view showing an example of developing a coloring material using thin layer chromatography.
Generally, the Rf value of the color material is calculated by: (distance from the original line (D) to the spot center of the component (A)) / (distance from the original line (D) to the developing solvent tip (B) )) Will be the value specified in. However, when a dye is used as the coloring material, the dye is often not composed of a single component, and since the developing solvent is an organic solvent used in the ink, the tailing is also large. Therefore, the following formula (1) The Rf value of each spot (P) is obtained by using, and the average value obtained by averaging the Rf values of each spot (P) can be calculated as the Rf value of the coloring material.
Rf value of color material in each spot (P) = [{(spot width (W)) × (unit length (L)) / (total area of the spot (S))} × (from the original line (D) Distance (A))] / (Distance from the original line (D) to the tip of the developing solvent (B)) Equation (1)
The unit length (L) in the formula (1) is an image decomposition interval used when analyzing a thin layer chromatography image, and when the image is digitized, the pixel interval of the image is used as a unit length. However, the pixel can be obtained as a unit length. In the case of a 400 dpi image, the unit length is 63.5 μm.

[Difference in relative mobility of cyan dye, magenta dye, and yellow dye]
When the ink contains a cyan ink containing a cyan dye, a magenta ink containing a magenta dye, and a yellow ink containing a yellow dye, in the thin layer chromatography developed with the organic solvent as a developing solvent, the cyan dye The difference between the relative mobility, the relative mobility of the magenta dye, and the relative mobility of the yellow dye is preferably 0.1 or more. When the difference in relative mobility is 0.1 or more, the color difference in the obtained image can be reduced even when high-speed recording is performed.

  The Rf value is determined by the relationship between the coloring material and the developing solvent (organic solvent of the same kind as the solvent contained in the ink, or organic solvent mixed with the same mass ratio when a plurality of organic solvents are contained). Dyes used in water-based dye inks tend to be strongly hydrophilic because they are soluble in water. Therefore, the higher the hydrophilicity of the developing solvent, the larger the Rf value, and the more hydrophobic the developing solvent, the smaller the Rf value. Further, as a factor on the dye side, the solubility varies depending on the introduced amount and molecular weight of a hydrophilic group such as a sulfonic acid group or a carboxylic acid group, and the dye skeleton. When the dye is likely to form a cluster due to the skeleton of the dye, the solubility in an organic solvent tends to be low and the Rf value tends to be small.

  In the ink, in order to control the Rf value of the color material, it is necessary to confirm the solubility between the color material used and the organic solvent. An organic solvent having a high solubility of the coloring material has a high affinity and a high Rf value, whereas an organic solvent having a low solubility has a low affinity and a low Rf value. By confirming the solubility in a plurality of organic solvents, it is possible to control the Rf value to a desired value by combining solvents having different solubilities. In addition, the use of a low molecular weight dye, a dye that does not easily form clusters, etc. in the organic solvent formulation tends to reduce the apparent molecular weight of the dye in a dissolved state and increase the Rf value. This can be utilized to control the Rf value.

  The ink set of the present invention can be obtained by combining two or more of the above inks.

<Ink>
Hereinafter, the organic solvent, water, coloring material, resin, additive and the like used in the ink will be described.

<Organic solvent>
The organic solvent used in the present invention is not particularly limited, and a water-soluble organic solvent can be used. Examples thereof include polyhydric alcohols, ethers such as polyhydric alcohol alkyl ethers and polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, and sulfur-containing compounds.
Specific examples of the water-soluble organic solvent include, for example, ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butane. Diol, 2,3-butanediol, 3-methyl-1,3-butanediol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol , 2,4-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,3-hexanediol, 2,5-hexanediol, 1,5-hexanediol, Glycerin, 1,2,6-hexanetriol, 2-ethyl-1,3- Polyhydric alcohols such as sundiol, ethyl-1,2,4-butanetriol, 1,2,3-butanetriol, 2,2,4-trimethyl-1,3-pentanediol and petriol, ethylene glycol mono Polyhydric alcohol alkyl ethers such as ethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monophenyl ether, ethylene glycol mono Polyhydric alcohol aryl ethers such as benzyl ether, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl- -Pyrrolidone, 1,3-dimethyl-2-imidazolidinone, nitrogen-containing heterocyclic compounds such as ε-caprolactam, γ-butyrolactone, formamide, N-methylformamide, N, N-dimethylformamide, 3-methoxy-N, Amides such as N-dimethylpropionamide and 3-butoxy-N, N-dimethylpropionamide, amines such as monoethanolamine, diethanolamine and triethylamine, sulfur-containing compounds such as dimethylsulfoxide, sulfolane and thiodiethanol, propylene carbonate, Examples thereof include ethylene carbonate.
It is preferable to use an organic solvent having a boiling point of 250 ° C. or less because it not only functions as a wetting agent but also obtains good drying properties.

A polyol compound having 8 or more carbon atoms and a glycol ether compound are also preferably used. Specific examples of the polyol compound having 8 or more carbon atoms include 2-ethyl-1,3-hexanediol and 2,2,4-trimethyl-1,3-pentanediol.
Specific examples of glycol ether compounds include polyhydric alcohol alkyls such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether. Ethers; polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.

  The polyol compound having 8 or more carbon atoms and the glycol ether compound can improve the ink permeability when paper is used as the recording medium.

  The content of the organic solvent is 30% by mass or more, preferably 30% by mass or more and 60% by mass or less, and more preferably 40% by mass or more and 60% by mass or less, based on the total amount of the ink. When the content is 30% by mass or more, the mobility can be maintained even when the coloring material is in a concentrated state in the drying process after the ink has landed on the recording medium, and the dye is distributed in the thickness direction of the recording medium. The moving time can be obtained, and the color difference of the obtained image can be reduced.

<Water>
The content of water in the ink is not particularly limited and can be appropriately selected according to the purpose, but from the viewpoint of the drying property of the ink and the ejection reliability, it is preferably 10% by mass or more and 90% by mass or less, and 20% by mass. % To 60% by mass is more preferable.

  The water is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include pure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water and distilled water; and ultrapure water. .. These may be used alone or in combination of two or more.

<Color material>
In the thin layer chromatography using the organic solvent as a developing solvent, the coloring material has a relative mobility difference (maximum relative mobility) between a maximum value and a minimum value of relative mobilities of the coloring materials in all the inks. The value-the minimum value of relative mobility) is not particularly limited as long as it is 0.1 or more, and can be appropriately selected according to the purpose.

Examples of the coloring material include dyes.
The dye is appropriately selected depending on the intended purpose without any limitation, but it is preferably water-soluble dye. By using the water-soluble dye, a vivid hue can be obtained, and an image in which the glossiness of the recording medium is maintained can be obtained.

  As the dye, dyes having different Rf values by thin layer chromatography using an organic solvent used in the ink are selected, and an ink set is formed by using the dye, whereby the dye in the thickness direction of the recording medium is formed. It is possible to change the ease of penetration and reduce the bidirectional color difference.

<< Dye >>
As the dye, even if it is used in cyan, magenta, yellow, and black inks which are process colors, the durability of the obtained image can be improved by using the dye that can enhance the weather resistance of the obtained image. Examples of dyes that can obtain such high weather resistance include those described in the following documents.
Cyan dye: Paragraphs [0189] to [0231] of JP2007-224274A, and paragraphs [0025] to [0062] of JP2009-062515A.
Magenta dye: Paragraphs [0152] to [0182] of JP2009-062515A, JP2003-192930A, JP2005-0088868A, JP5419705A, and JP4989975A. Yellow dye : Paragraphs [0016] to [0118] of JP2007-224274A, and paragraphs [0063] to [0130] of JP2009-062515A.
-Black dye: Paragraphs [0132] to [0189] of JP2007-224274A, and paragraphs [0189] to [0259] of JP2009-062515A.

  Specific examples of the cyan dye include, for example, the following compound (CI) (Rf value: 0.92), the following compound (C-II) (Rf value: 0.34), C.I. I. Direct Blue 199 (Rf value: 0.93), FujiFilm Pro-Jet Cyan of 1 liq. (Rf value: 0.91), Blue No. 1 (Rf value: 0.97), Bayscript Cyan GA liq. (Rf value: 0.92) and the like. Among these, compound (C-I), compound (C-II), FujiFilm Pro-Jet Cyan of 1 liq. Is preferred.

Compound (C-I)
However, in the compound (CI), l is 0.3, m is 2.3, and n is 1.4.

Compound (C-II)

  Specific examples of the magenta dye include the following compound (M-I) (Rf value: 0.93), the following compound (M-II) (Rf value: 0.96), C.I. I. Acid Red 52 (Rf value: 0.95), FujiFilm Pro-Jet Magenta 1 liq. (Rf value: 0.95), C.I. I. Acid Red 254 (Rf value: 0.95) and the like. Among these, compound (M-I), compound (M-II), C.I. I. Acid Red 52 is preferred.

Compound (M-I)

Compound (M-II)

  Specific examples of the yellow dye include, for example, the following compound (Y-I) (Rf value: 0.85), the following compound (Y-II) (Rf value: 0.95), C.I. I. Direct Yellow 132 (Rf value: 0.94), C.I. I. Direct Yellow 142 (Rf value: 0.95), 1,3-naphthalenedisulfonic acid (Rf value: 0.96), Edible Yellow No. 4 (Rf value: 0.95) and the like can be mentioned. Among these, the compound (Y-I), C.I. I. Direct Yellow 132, C.I. I. Direct Yellow 142 is preferred.

Compound (Y-I)
However, in the compound (Y-I), t-Bu represents a tert-butyl group.

Compound (Y-II)

  Specific examples of the black dye include the following compound (KI) (Rf value: 0.83), C.I. I. Direct Black 168, Li salt (Rf value: 0.91), FujiFilm Pro-Jet Fast Black 2 CF1 liq. (Rf value: 0.92), LANXESS Bayscript Black SP liq. (Rf value: 0.89) and the like. Among these, the compound (KI), C.I. I. Direct Black 168, Li salt, FujiFilm Pro-Jet Fast Black 2 CF1 liq. Is preferred.

Compound (K-I)

  The Rf values in the specific examples of the cyan dye, the specific example of the magenta dye, the specific example of the yellow dye, and the specific example of the black dye are glycerin, 1,3-propanediol, and 2- It is a numerical value when the pyrrolidone was developed for 15 hours by thin layer chromatography using an organic solvent having a mixing ratio of 10: 30: 1 by mass ratio.

As the dye used for the intermediate hue ink, commercially available dyes from yellow to orange and red hues may be used alone or in combination of two or more.
Examples of the commercially available dyes from yellow to orange to red hue include C.I. I. Direct Orange 6, 8, 10, 26, 29, 39, 41, 49, 51, 62, 102; C.I. I. Acid Orange 7, 8, 10, 33, 56, 64; C.I. I. Food Yellow 3, 4, 5, and the like. Among these, from the viewpoint of hue and coloring surface, C.I. I. Acid Orange 33, C.I. I. Food Yellow 5 is preferred.

  As a dye other than the above dye, as a complementary color, for example, an acid dye, an edible dye, a direct dye, a basic dye, a reactive dye or the like can be contained. These may be used alone or in combination of two or more.

Examples of the acid dye and the food dye, for example,
C. I. Acid Yellow 17,23,42,44,79,142
C. I. Acid Red 1, 8, 13, 14, 18, 26, 27, 35, 37, 42, 52, 82, 87, 89, 92, 97, 106, 111, 114, 115, 134, 186, 249, 254. 289
C. I. Acid Blue 9, 29, 45, 92, 249
C. I. Acid Black 1, 2, 7, 24, 26, 94
C. I. Food Yellow 3,4
C. I. Hood Red 7, 9, 14
C. I. Food Black 1, 2 etc. are mentioned. These may be used alone or in combination of two or more.

As the direct dye, for example,
C. I. Direct Yellow 1, 12, 24, 26, 33, 44, 50, 120, 132, 142, 144, 86
C. I. Direct Red 1, 4, 9, 13, 17, 20, 28, 31, 39, 80, 81, 83, 89, 225, 227
C. I. Direct Blue 1, 2, 6, 15, 22, 25, 71, 76, 79, 86, 87, 90, 98, 163, 165, 199, 202
C. I. Direct Black 19, 22, 32, 38, 51, 56, 71, 74, 75, 77, 154, 168, 171 and the like. These may be used alone or in combination of two or more.

As the basic dye, for example,
C. I. Basic Yellow 1, 2, 11, 13, 14, 15, 19, 21, 23, 24, 25, 28, 29, 32, 36, 40, 41, 45, 49, 51, 53, 63, 465, 67 , 70, 73, 77, 87, 91
C. I. Basic Red 2, 12, 13, 14, 15, 18, 22, 23, 24, 27, 29, 35, 36, 38, 39, 46, 49, 51, 52, 54, 59, 68, 69, 70 , 73, 78, 82, 102, 104, 109, 112
C. I. Basic Blue 1, 3, 5, 7, 9, 21, 22, 26, 35, 41, 45, 47, 54, 62, 65, 66, 67, 69, 75, 77, 78, 89, 92, 93 , 105, 117, 120, 122, 124, 129, 137, 141, 147, 155.
C. I. Basic Black 2, 8 and so on. These may be used alone or in combination of two or more.

As the reactive dye, for example,
C. I. Reactive Black 3, 4, 7, 11, 12, 17
C. I. Reactive Yellow 1, 5, 11, 13, 14, 20, 21, 22, 25, 40, 47, 51, 55, 65, 67
C. I. Reactive Red 1, 14, 17, 25, 26, 32, 37, 44, 46, 55, 60, 66, 74, 79, 96, 97
C. I. Reactive Blue 1, 2, 7, 14, 15, 23, 32, 35, 38, 41, 63, 80, 95 and the like. These may be used alone or in combination of two or more.

  The content of the dye is preferably 2% by mass or more and 6% by mass or less based on the total amount of the ink.

  The content of the coloring material in the ink is preferably 0.1% by mass or more and 15% by mass or less, more preferably 1% by mass or more and 10% by mass, from the viewpoints of improving the image density, good fixing property and ejection stability. It is the following.

<Resin>
The type of resin contained in the ink is not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include urethane resin, polyester resin, acrylic resin, vinyl acetate resin, styrene resin, and butadiene resin. Examples thereof include resins, styrene-butadiene resins, vinyl chloride resins, acrylic styrene resins, acrylic silicone resins and the like.
You may use the resin particle which consists of these resins. It is possible to obtain ink by mixing resin particles with a material such as a coloring material or an organic solvent in the state of a resin emulsion in which water is used as a dispersion medium. As the resin particles, those synthesized appropriately may be used, or commercially available products may be used. Further, these may be used alone or in combination of two or more kinds of resin particles.

<Additive>
If necessary, a surfactant, an antifoaming agent, an antiseptic / antifungal agent, an anticorrosive agent, a pH adjusting agent and the like may be added to the ink.

<Surfactant>
As the surfactant, any of silicone-based surfactants, fluorine-based surfactants, amphoteric surfactants, nonionic surfactants, and anionic surfactants can be used.
The silicone surfactant is not particularly limited and can be appropriately selected according to the purpose. Among them, those that do not decompose even at high pH are preferable, and examples thereof include side chain-modified polydimethylsiloxane, both-end modified polydimethylsiloxane, one-end modified polydimethylsiloxane, and side-chain both-end modified polydimethylsiloxane. Those having an oxyethylene group or a polyoxyethylene polyoxypropylene group are particularly preferable because they exhibit good properties as an aqueous surfactant. Further, as the silicone-based surfactant, a polyether-modified silicone-based surfactant can be used, and examples thereof include a compound having a polyalkylene oxide structure introduced into the side chain of the Si moiety of dimethylsiloxane.
Examples of the fluorinated surfactant include a perfluoroalkyl sulfonic acid compound, a perfluoroalkyl carboxylic acid compound, a perfluoroalkyl phosphoric acid ester compound, a perfluoroalkyl ethylene oxide adduct and a perfluoroalkyl ether group in the side chain. A polyoxyalkylene ether polymer compound is particularly preferable because it has a low foaming property. Examples of the perfluoroalkyl sulfonic acid compound include perfluoroalkyl sulfonic acid and perfluoroalkyl sulfonate. Examples of the perfluoroalkylcarboxylic acid compound include perfluoroalkylcarboxylic acid and perfluoroalkylcarboxylic acid salts. Examples of the polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in its side chain include a sulfuric acid ester salt of a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in its side chain and a perfluoroalkyl ether group in its side chain. Examples thereof include salts of polyoxyalkylene ether polymers. As counter ions of the salt in these fluorine-based surfactants, Li, Na, K, NH ₄ , NH ₃ CH ₂ CH ₂ OH, NH ₂ (CH ₂ CH ₂ OH) ₂ , NH (CH ₂ CH ₂ OH) are used. ₃ etc. are mentioned.
Examples of the amphoteric surfactant include lauryl aminopropionate, lauryl dimethyl betaine, stearyl dimethyl betaine, and lauryl dihydroxyethyl betaine.
Examples of the nonionic surfactant include polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl ester, polyoxyethylene alkylamine, polyoxyethylene alkylamide, polyoxyethylene propylene block polymer, sorbitan fatty acid ester, polyoxyethylene sorbitan. Examples thereof include fatty acid esters and ethylene oxide adducts of acetylene alcohol.
Examples of the anionic surfactant include polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, lauryl acid salt, and salt of polyoxyethylene alkyl ether sulfate.
These may be used alone or in combination of two or more.

The silicone-based surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include side-chain modified polydimethylsiloxane, both-end modified polydimethylsiloxane, one-end modified polydimethylsiloxane, and side-modified. Examples thereof include polydimethyl siloxane modified at both chain ends, and a polyether modified silicone surfactant having a polyoxyethylene group or a polyoxyethylene polyoxypropylene group as a modifying group exhibits good properties as an aqueous surfactant. preferable.
As such a surfactant, those synthesized appropriately may be used, or commercially available products may be used. Commercially available products can be obtained from, for example, Big Chemie Co., Ltd., Shin-Etsu Chemical Co., Ltd., Toray Dow Corning Silicone Co., Ltd., Nippon Emulsion Co., Ltd., Kyoeisha Kagaku, etc.
The polyether-modified silicone-based surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. For example, the polyalkylene oxide structure represented by the general formula (S-1) is represented by dimethylpolyethylene. Examples thereof include those introduced into the side chain of the Si portion of siloxane.
General formula (S-1)
(However, in the general formula (S-1), m, n, a, and b represent an integer. R and R ′ represent an alkyl group or an alkylene group.)
As the above polyether-modified silicone-based surfactant, commercially available products can be used, and examples thereof include KF-618, KF-642, KF-643 (Shin-Etsu Chemical Co., Ltd.), EMALEX-SS-5602, SS-. 1906EX (Japan Emulsion Co., Ltd.), FZ-2105, FZ-2118, FZ-2154, FZ-2161, FZ-2162, FZ-2163, FZ-2164 (Toray Dow Corning Silicone Co., Ltd.), BYK-33, BYK-387 (Big Chemie Co., Ltd.), TSF4440, TSF4452, TSF4453 (Toshiba Silicon Co., Ltd.), etc. are mentioned.

The fluorine-containing carbon number of the fluorine-based surfactant is preferably 2 or more and 16 or less, more preferably 4 or more and 16 or less.
Examples of the fluorine-based surfactant include perfluoroalkyl phosphate ester compounds, perfluoroalkylethylene oxide adducts, and polyoxyalkylene ether polymer compounds having a perfluoroalkyl ether group in the side chain.
Among these, a polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain is preferable from the viewpoint of low foaming property, and a fluorine-based surfactant represented by the following general formula (F-1), the following general formula The fluorine-based surfactant represented by the formula (F-2) is more preferable.
General formula (F-1)
In the compound represented by the general formula (F-1), m is preferably an integer of 0 or more and 10 or less, and n is preferably an integer of 0 or more and 40 or less in order to impart water solubility.
General formula (F-2)
_{C n F 2n + 1 -CH 2} CH (OH) CH 2 -O- (CH 2 CH 2 O) a -Y
In the compound represented by the general formula (F-2), Y is H, or C _n F _{2n + 1} , n is an integer of 1 or more and 6 or less, or CH ₂ CH (OH) CH ₂ -C _n F _{2n + 1} is n. Is an integer of 4 or more and 6 or less, or C _p H _{2p + 1} and p is an integer of 1 or more and 19 or less. a is an integer of 4 or more and 14 or less.
A commercially available product may be used as the fluorine-based surfactant.
Examples of the commercially available product include Surflon S-111, S-112, S-113, S-121, S-131, S-132, S-141, S-145 (all manufactured by Asahi Glass Co., Ltd.); FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, FC-431 (above, manufactured by 3M Japan KK); Megafac F-470, F-1405. , F-474 (above, manufactured by DIC Corporation); Zonyl TBS, FSP, FSA, FSN-100, FSN, FSO-100, FSO, FS-300, UR (above, manufactured by DuPont); FT- 110, FT-250, FT-251, FT-400S, FT-150, FT-400SW (above, Neos Co., Ltd.), Polyfox P -136A, PF-156A, PF-151N, PF-154, PF-159 (manufactured by OMNOVA Solutions Inc.), UNIDYNE DSN-403N (manufactured by Daikin Industries, Ltd.) and the like. Among these, FS-300 manufactured by Du Pont, FT-110 manufactured by Neos Co., Ltd., and FT, from the viewpoint that good printing quality, particularly color developability, penetrability to paper, wettability, and level dyeing property are remarkably improved. -250, FT-251, FT-400S, FT-150, FT-400SW, Polyfox PF-151N manufactured by Omnova Co., Ltd. and Unidyne DSN-403N manufactured by Daikin Industries, Ltd. are preferable.

  The content of the surfactant in the ink is appropriately selected depending on the intended purpose without any limitation, but it is 0.001 mass% from the viewpoint of excellent wettability and ejection stability and improving image quality. % Or more and 5 mass% or less is preferable, and 0.05 mass% or more and 5 mass% or less is more preferable.

<Antifoam>
The defoaming agent is not particularly limited, and examples thereof include a silicone defoaming agent, a polyether defoaming agent, and a fatty acid ester defoaming agent. These may be used alone or in combination of two or more. Among these, a silicone-based defoaming agent is preferable because of its excellent foam breaking effect.

<Antiseptic and fungicide>
The antiseptic / antifungal agent is not particularly limited, and examples thereof include 1,2-benzisothiazolin-3-one.

<Rust preventive>
The rust preventive agent is not particularly limited, and examples thereof include acid sulfite and sodium thiosulfate.

<PH adjuster>
The pH adjuster is not particularly limited as long as the pH can be adjusted to 7 or higher, and examples thereof include amines such as diethanolamine and triethanolamine.

The physical properties of the ink are not particularly limited and may be appropriately selected depending on the purpose. For example, the viscosity, surface tension, pH and the like are preferably in the following ranges.
The viscosity of the ink at 25 ° C. is preferably 5 mPa · s or more and 30 mPa · s or less, from the viewpoint that the printing density and character quality are improved, and that good ejection properties are obtained, and 5 mPa · s or more and 25 mPa · s or less are preferable. More preferable. Here, as the viscosity, for example, a rotary viscometer (RE-80L manufactured by Toki Sangyo Co., Ltd.) can be used. The measurement conditions are 25 ° C., standard cone rotor (1 ° 34 ′ × R24), sample liquid volume 1.2 mL, rotation speed 50 rpm, and 3 minutes.
The surface tension of the ink is preferably 35 mN / m or less, and more preferably 32 mN / m or less at 25 ° C. from the viewpoint that the ink is preferably leveled on the recording medium and the drying time of the ink is shortened.
The pH of the ink is preferably 7 to 12, and more preferably 8 to 11 from the viewpoint of preventing the corrosion of the metal member with which the ink comes into contact.

  The ink set of the present invention is preferably used for bidirectional recording by an inkjet method.

<Recording medium>
The recording medium used for recording is not particularly limited, and examples thereof include plain paper, glossy paper, special paper, cloth, film, OHP sheet, and general-purpose printing paper.

The recording medium to be the subject of the inkjet recording method of the present invention has at least one ink receiving layer on a support, and further has other layers as necessary.
An inkjet recording medium having a lower layer containing silica, polyvinyl alcohol and a cross-linking agent on the support, containing alumina or colloidal silica and polyvinyl alcohol, and comprising an upper layer containing substantially no cross-linking agent for polyvinyl alcohol. preferable.
The upper layer of such a recording medium becomes the recording surface of the recording medium, and it is preferable that the Beck's smoothness of this surface is 300 seconds or more. When it is 300 seconds or more, the pixels become uniform, roundness is easily obtained, and noise in photographic gradation is less likely to occur.

The ink receiving layer has a multi-layer structure of two or more layers, and the lower layer contains porous particles such as an inorganic oxide having a large specific surface area so as to quickly absorb the ink and fix the colorant. Preferably. Specific examples of the porous particles include silica and alumina. Particularly, among silica, an average primary particle size obtained by a vapor phase method is 30 nm or less, and a BET specific surface area is 250 m ² / g or more. Synthetic silica is preferable because it has high ink absorbency and gloss.
Examples of the alumina include β-alumina and γ-alumina.

Further, in the upper layer corresponding to the surface of the recording medium, it is preferable to use colloidal silica or alumina having a small primary particle size and a large secondary particle size as the porous particles, and particularly colloidal silica particles treated with an aluminum salt are also preferably used. be able to.
As the binder in the ink receiving layer, a hydrophilic binder having high transparency and high permeability of the ink solvent is preferably used. In using the hydrophilic binder, it is important that the hydrophilic binder does not swell and block the voids at the initial penetration of the ink solvent, and a hydrophilic binder that does not easily swell at around room temperature is preferably used. Particularly preferred hydrophilic binders are fully or partially saponified polyvinyl alcohol or cation-modified polyvinyl alcohol. The lower layer forms a gel structure by adding a cross-linking agent such as borax to polyvinyl alcohol, and by drying the gel structure as it is, an ink receiving layer having large voids and high liquid absorption can be formed.
As the base material of the recording medium, any of known paper, synthetic paper, resin-coated paper, film and the like can be used, but a non-ink absorbing base material is preferable.
In particular, resin coated paper such as used for photographic printing paper is more preferable as a media base material for reproducing photographic image quality.

<Recorded matter>
The ink recorded matter of the invention has an image formed by using the ink of the invention on a recording medium.
A recorded matter can be obtained by recording with an inkjet recording apparatus and an inkjet recording method.

<Ink cartridge>
The ink cartridge of the present invention contains the ink used in the ink set of the present invention in a container, and further has other members appropriately selected as necessary.
The container is not particularly limited and its shape, structure, size, material and the like can be appropriately selected according to the purpose, and for example, an ink bag formed of an aluminum laminate film, a resin film or the like can be used at least. Preferable ones have.

<Inkjet recording apparatus and inkjet recording method>

The inkjet recording method of the present invention preferably includes a heating and drying step of heating and drying the recording medium on which an image is formed by flying ink as necessary.
The inkjet recording apparatus of the present invention preferably has a heating / drying apparatus for heating and drying the recording medium on which an image is formed by flying the ink as necessary, and the ink used in the ink set of the present invention is imaged. A recording head having a plurality of recording sections for recording on the entire width in one direction of the formation area, and a main scanning drive section for driving at least one of the recording heads and the recording medium to perform main scanning. Preferably.
The inkjet recording method of the present invention can be preferably carried out by the inkjet recording apparatus of the present invention, and the ink flying step can be preferably carried out by the ink flying means. Further, the heating step can be suitably performed by a heating means, and the other steps can be suitably performed by the other means.

  In the inkjet recording method of the present invention, bidirectional recording is preferably performed by an inkjet recording method.

-Ink flight process and ink flight means-
The ink jetting step is a step of applying a stimulus (energy) to the ink used in the ink set of the present invention, causing the ink to fly from various nozzles for ejecting ink, and recording an image on a recording medium.
The ink ejecting unit is a unit that applies a stimulus (energy) to the ink used in the ink set of the present invention to eject the ink from various nozzles for ejecting the ink and eject the ink to the recording medium.

  The stimulus is not particularly limited and may be appropriately selected depending on the intended purpose, and examples thereof include heat (temperature), pressure, vibration, and light. These may be used alone or in combination of two or more. Among these, heat and pressure are preferable.

  As a mode of flight of the ink used in the ink set, for example, a piezoelectric element is used as a pressure generating means for pressurizing the ink in the ink flow path, and the vibration plate forming the wall surface of the ink flow path is deformed. A so-called piezo method (see, for example, Japanese Patent Publication No. 2-51734) in which ink volume is changed by changing the volume of the flow path, ink is heated in the ink flow path using a heating resistor to generate bubbles. In a so-called thermal method (see, for example, Japanese Patent Publication No. 61-59911), a diaphragm forming a wall surface of an ink flow path and an electrode are arranged to face each other, and electrostatic force generated between the diaphragm and the electrode is used. An electrostatic method (for example, see Japanese Patent Laid-Open No. 6-71882) in which the volume of the ink flow path is changed to eject ink droplets by deforming the vibrating plate can be used. That.

The droplets of the ink to be ejected have a size of, for example, preferably 3 pL or more and 40 pL or less, a speed of ejection and ejection thereof of 5 m / s or more and 20 m / s or less, and a driving frequency thereof. 1 kHz or more is preferable, and its resolution is preferably 300 dpi or more.
The recording speed is preferably at least 8.0 cm ² / sec, more preferably at least 16cm ² / sec, more 33cm ² / sec is particularly preferable.

-Heating step and heating means-
The heating step is a step of heating the recording medium on which an image is recorded.
The heating means is means for heating the recording medium on which an image is recorded.
The ink jet recording method and the ink jet recording apparatus can perform recording with high image quality on the recording medium, but can also form images with higher image quality, abrasion resistance, and adhesion, and high-speed recording conditions. In order to be compatible, it is preferable to heat the recording medium after recording. When the heating step is provided after recording, the film formation of the resin contained in the ink is promoted, so that the image hardness of the recorded matter can be improved.

As the device used in the heating step, many known devices can be used, and examples thereof include devices such as forced air heating, radiant heating, conduction heating, high frequency drying, and microwave drying. These may be used alone or in combination of two or more.
The heating temperature can be changed according to the type and amount of the organic solvent contained in the ink, and the minimum film-forming temperature of the resin emulsion to be added, and also depending on the type of the substrate to be printed. be able to.
The heating temperature is preferably high, more preferably 20 ° C. or higher and 120 ° C. or lower, further preferably 40 ° C. or higher and 100 ° C. or lower, and particularly preferably 50 ° C. or higher and 90 ° C. or lower, from the viewpoints of drying property and film forming temperature. preferable. When the heating temperature is 40 ° C. or higher and 120 ° C. or lower, it is possible to prevent the recording medium to be printed from being damaged by heat and to prevent ejection failure due to warming of the ink head.

  The ink used in the ink set of the present invention is not limited to the inkjet recording method and can be widely used. In addition to the inkjet recording method, for example, a blade coating method, a gravure coating method, a gravure offset coating method, a bar coating method, a roll coating method, a knife coating method, an air knife coating method, a comma coating method, a U comma coating method, an AKKU coating method. , Smoothing coating method, micro gravure coating method, reverse roll coating method, four to five roll coating method, dip coating method, curtain coating method, slide coating method, die coating method, spray coating method and the like.

Here, a method of forming an image on a recording medium in the same area of the image will be described with reference to the drawings.
FIG. 1 is a schematic diagram showing the movement of an ink head and the conveyance state of a recording medium in an inkjet recording apparatus of the present invention, showing the main scanning direction. The recording is performed by moving the recording medium on the platen 4 using the registration roller (conveying means) 1 and moving the carriage 7 holding the ink head 6 in the main scanning direction. FIG. 2 is a schematic diagram showing an example of a recording method for the same recording area in the inkjet recording method of the present invention. It should be noted that printing by the ink head scanning in the main scanning direction is referred to as pass, printing with one scan is referred to as 1-pass printing, and printing with multiple scans is referred to as multi-pass, When the image is completed by scanning n times and recording at the same location n times, it is called n-pass recording. The recording width recorded in one pass is called a band.
In FIG. 2, the circled numbers on the recording medium indicate how many times the images are overlapped at that time. For example, when 2 is written in a circle, the marks are recorded twice (two times for the same area). It shows the range of recording).

  In FIG. 2, when printing on paper with the ink head 21, the number of multi-passes is set to 4, and the printing range of the ink head 21 is divided into bands 21-1 to 21-4 corresponding to the number of passes 4. , Recording is started from the band 21-1 at the upstream end of the ink head 21, recording is performed in the band (1 pass), then the recording medium is fed by the width of one band, and the next recording ( 2 passes) and this is repeated sequentially. Bidirectional recording means recording in both directions, that is, in a reciprocating process.

By using the ink set of the present invention, it is possible to achieve both high-speed recording and reduction of color difference caused by the difference in ink recording order in the ink set. Conventionally, in order to eliminate color difference in bidirectional printing, main scanning printing is performed a plurality of times on the same area of an image, and the image is divided into main scanning times and printed to disperse the printing order in time series. Has been considered to eliminate the color difference. However, in this case, the bidirectional color difference could not be sufficiently canceled without increasing the number of divisions. On the other hand, according to the present invention, a great effect can be obtained in the case where the same area of an image is printed by main scanning four times (four passes) or less, and further, two times (two passes) or less. A remarkable effect can be obtained when printing is performed by main scanning.
It should be noted that the main-scan reciprocal printing (bidirectional printing) means a total of two times (two passes) by one forward scan printing (one pass) and one backward scanning printing (one pass).

  Here, an inkjet recording apparatus that can perform recording using the ink will be described with reference to the drawings. The ink jet recording apparatus includes a serial type (shuttle type) in which a carriage scans, a line type having a line type head, and the like. FIG. 3 is a plan view of a principal part showing an example of a serial type image forming apparatus. is there. FIG. 4 is a side view for explaining a main part of an example of the liquid ejection unit of the apparatus shown in FIG. FIG. 5 is a side view of a main part showing another example of the liquid ejection unit of the apparatus of FIG.

  As shown in FIG. 3, the inkjet recording apparatus is a serial type apparatus, and the carriage 403 reciprocates in the main scanning direction by a main scanning movement mechanism 493. The main scanning movement mechanism 493 includes a guide member 401, a main scanning motor 405, a timing belt 408, and the like. The guide member 401 is bridged between the left and right side plates 491A and 491B and movably holds the carriage 403. Then, the carriage 403 is reciprocally moved in the main scanning direction by the main scanning motor 405 via the timing belt 408 that spans between the driving pulley 406 and the driven pulley 407.

  On the carriage 403, a liquid ejection unit 440 in which a liquid ejection head 404 and a head tank 441 according to the present invention are integrated is mounted. The liquid ejection head 404 of the liquid ejection unit 440 ejects liquids of yellow (Y), cyan (C), magenta (M), and black (K), for example. Further, the liquid ejection head 404 has a nozzle row composed of a plurality of nozzles arranged in a sub-scanning direction orthogonal to the main scanning direction, and is mounted with the ejection direction facing downward.

  The liquid ejecting unit includes a housing portion including side plates 491A and 491B and a back plate 491C, a main scanning moving mechanism 493, a carriage 403, and a liquid among the members that configure the device that ejects the liquid. It is composed of the ejection head 404.

  It is also possible to configure a liquid discharge unit in which at least one of the maintenance / recovery mechanism 420 and the supply mechanism 494 described above is further attached to, for example, the side plate 491B of this liquid discharge unit.

  The liquid stored in the liquid cartridge 450 is supplied to the head tank 441 by the supply mechanism 494 for supplying the liquid stored outside the liquid discharge head 404 to the liquid discharge head 404.

  The supply mechanism 494 includes a cartridge holder 451, which is a filling unit for mounting the liquid cartridge 450, a tube 456, a liquid sending unit 452 including a liquid sending pump, and the like. The liquid cartridge 450 is detachably attached to the cartridge holder 451. The liquid is sent from the liquid cartridge 450 to the head tank 441 by the liquid sending unit 452 via the tube 456.

  The inkjet recording apparatus includes a transport mechanism 495 for transporting the sheet 410. The transport mechanism 495 includes a transport belt 412, which is a transport unit, and a sub-scanning motor 416 for driving the transport belt 412.

  The conveyance belt 412 adsorbs the sheet 410 and conveys it at a position facing the liquid ejection head 404. The conveyor belt 412 is an endless belt, and is stretched between a conveyor roller 413 and a tension roller 414. The adsorption can be performed by electrostatic adsorption or air suction.

  Then, the transport belt 412 is rotated in the sub-scanning direction by the sub-scanning motor 416 rotatably driving the transport roller 413 via the timing belt 417 and the timing pulley 418.

  Further, on one side of the carriage 403 in the main scanning direction, a maintenance / recovery mechanism 420 for maintenance / recovery of the liquid ejection head 404 is arranged beside the transport belt 412.

  The maintenance / recovery mechanism 420 is composed of, for example, a cap member 421 that caps the nozzle surface (a surface on which nozzles are formed) of the liquid ejection head 404, a wiper member 422 that wipes the nozzle surface, and the like.

  The main-scanning moving mechanism 493, the supply mechanism 494, the maintenance / recovery mechanism 420, and the transport mechanism 495 are attached to a housing including side plates 491A and 491B and a back plate 491C.

  In the inkjet recording apparatus configured as described above, the paper 410 is fed and adsorbed on the conveyor belt 412, and the paper 410 is conveyed in the sub-scanning direction by the orbital movement of the conveyor belt 412.

  Therefore, by moving the carriage 403 in the main scanning direction and driving the liquid ejection head 404 in accordance with the image signal, the liquid is ejected onto the stopped paper 410 to form an image.

  As described above, since the inkjet recording apparatus includes the liquid ejection head, it is possible to stably form a high quality image.

  Next, still another example of the liquid ejection unit according to the present invention will be described with reference to FIG. FIG. 17 is a front explanatory view of the liquid ejection unit in the inkjet recording apparatus.

  This liquid ejection unit is composed of a liquid ejection head 404 to which a flow path component 444 is attached and a tube 456 connected to the flow path component 444.

  The flow path component 444 is arranged inside the cover 442. A head tank 441 may be included instead of the flow path component 444. Further, a connector 443 for electrically connecting with the liquid ejection head 404 is provided on the flow path component 444.

  In the present invention, the inkjet recording apparatus is an apparatus that includes a liquid ejection head or a liquid ejection unit, and drives the liquid ejection head to eject the liquid. The inkjet recording apparatus includes not only an apparatus capable of ejecting a liquid onto an object to which the liquid can be attached, but also an apparatus ejecting the liquid toward the air or into the liquid.

  This ink jet recording apparatus can also include means for feeding, carrying, and discharging paper, to which liquid can be attached, as well as a pretreatment device and a posttreatment device.

  Further, the ink jet recording apparatus is not limited to the one in which a significant image such as characters and figures is visualized by the ejected liquid.

  The "liquid can be adhered" means a liquid to which a liquid can be at least temporarily adhered, which is adhered and fixed, or adhered and permeated. Specific examples are recording media such as paper, recording paper, recording paper, film, cloth, and the like, and all those to which liquid adheres are included unless otherwise specified.

  The material of the above-mentioned "liquid can be adhered" may be paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, ceramics, etc. as long as the liquid can be adhered even temporarily.

  For example, as a liquid ejection unit, there is one in which a liquid ejection head and a head tank are integrated, like the liquid ejection unit 440 shown in FIG. In addition, there is one in which the liquid ejection head and the head tank are integrated by being connected to each other by a tube or the like. Here, a unit including a filter may be added between the head tank and the liquid ejection head of these liquid ejection units.

  Further, as a liquid ejection unit, there is one in which a liquid ejection head and a carriage are integrated.

  Further, as a liquid ejection unit, there is a unit in which a liquid ejection head and a scanning movement mechanism are integrated so that a liquid ejection head is movably held by a guide member forming a part of the scanning movement mechanism. Further, as shown in FIG. 16, there is a liquid ejection unit in which a liquid ejection head, a carriage, and a main scanning movement mechanism are integrated.

  Further, as a liquid ejection unit, as shown in FIG. 3, there is a unit in which a tube is connected to a liquid ejection head having a head tank or a flow path component attached, and the liquid ejection head and the supply mechanism are integrated. ..

  The main scanning movement mechanism includes a single guide member. The supply mechanism also includes a tube unit and a loading unit unit.

  Further, the “liquid ejection head” is not limited to the pressure generating means used. For example, in addition to the piezoelectric actuator (which may use a laminated piezoelectric element) described in the above embodiment, a thermal actuator using an electrothermal conversion element such as a heating resistor, a vibration plate and a counter electrode are used. An electrostatic actuator or the like may be used.

  Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

  The relative mobilities of the coloring materials used in the following examples and comparative examples were measured as follows.

[Relative mobility of color materials]
The relative mobility of the color material was calculated by the following (1) to (4).
(1) Using a developing thin layer chromatography (TLC) plate (trade name: manufactured by Merck Ltd., unmodified silica gel TLC plate, average layer thickness: 200 μm, plastic sheet), used as a developing solvent in Examples and Comparative Examples The organic solvent in which glycerin, 1,3-butanediol, and 2-pyrrolidone, which are similar to the organic solvent used, are mixed at a mass ratio of 10: 30: 1 was used.
(2) 0.5 μL of the evaluation sample liquid diluted with pure water so that the concentration of the color material to be measured was 0.5% by mass was applied to the TLC plate.
(3) After the applied evaluation sample solution was sufficiently dried, the TLC plate was soaked in the vapor of the developing layer containing the developing solvent, and then the TLC plate was immersed in the developing solvent and developed for 15 hours.
(4) After the development, the TLC plate is sufficiently dried, the developed TLC plate is captured by a scanner to form an image, and the obtained image is analyzed using image analysis software (software name: Image J) to obtain Rf of the coloring material. The value was calculated.
To calculate the Rf value of the color material, the Rf value at each spot (P) is obtained by the following formula (1), and the average value obtained by averaging the Rf values at each spot (P) It was calculated as the Rf value of the material.
Rf value of color material in each spot (P) = [{(spot width (W)) × (unit length (L)) / (total area of the spot (S))} × (from the original line (D) Distance (A))] / (Distance from the original line (D) to the tip of the developing solvent (B)) Equation (1)
The unit length (L) in the formula (1) was set to 63.5 μm by reading a TLC plate scanner image as an image of 400 dpi using image analysis software: Image J. FIG. 7 shows a photograph of the TLC plate on which each color material was developed by thin layer chromatography. In FIG. 7, 1 is a compound (KI), 2 is C.I. I. Direct Black 168, Li salt, 3 is black dye 1, 4 is compound (C-I), 5 is compound (C-II), 6 is C.I. I. Direct Blue 199 and 7 are C.I. I. Acid Red 52, 8 is compound (M-I), 9 is compound (M-II), 10 is compound (Y-I), 11 is C.I. I. Direct Yellow 132, 12 are C.I. I. It is Direct Yellow 142.

(Preparation example 1 of ink)
<Preparation of Ink 1>
Glycerin 10.0% by mass, 1,3-propanediol 30.0% by mass, 2-pyrrolidone 1.0% by mass, polyoxyalkylene alkyl ether (trade name: Emulgen LS-106, manufactured by Kao Corporation, effective ingredient amount : 100% by mass) 0.3% by mass, pH adjusting agent (2-aminoethylpropanediol, manufactured by Tokyo Chemical Industry Co., Ltd.) 0.5% by mass, and antifungal agent (trade name: Proxel LV, Lonza Japan Co., Ltd.) 0.2% by mass was mixed and stirred for 30 minutes to obtain a uniform mixed solution. The following compound (K-1) (black dye) 5.0% by mass (active ingredient content) and the remaining amount of water were added to this mixed solution, and the mixture was stirred for 30 minutes. Thereafter, pressure filtration was performed with a cellulose acetate membrane filter (trade name: DISMIC25CS080AS, manufactured by Toyo Roshi Kaisha, Ltd.) having an average pore diameter of 0.8 μm, coarse particles were removed, and Ink 1 was prepared. Table 1 shows the composition.
(Compound (K-1))

(Ink preparation examples 2 to 12)
<Preparation of Inks 2 to 12>
Inks 2 to 12 were produced in the same manner as in Ink Production Example 1 except that the type and content of the coloring material in Ink Production Example 1 were changed to those of Table 1. .. Tables 1 and 2 show the types of coloring materials and the relative mobilities (Rf values) of the coloring materials. The content of each component shown in Table 1 and Table 2 is the content of the active ingredient.

In addition, in Table 1 and Table 2, a manufacturing company name, a brand name, and a compound are as follows.
C. I. Direct Black 168, Li salt: manufactured by Clariant Japan Co., Ltd.-Black dye 1: manufactured by Fuji Film Co., Ltd., product name: FujiFilm Pro-Jet Fast Black 2 CF1 liq.
-Compound (CI):
However, in the compound (CI), l is 0.3, m is 2.3, and n is 1.4.
-Compound (C-II):
C. I. Direct Blue 199: manufactured by FUJIFILM Corporation C.I. I. Acid Red 52: manufactured by FUJIFILM Corporation Compound (M-I):
-Compound (M-II):
-Compound (Y-I):
However, in the compound (Y-I), t-Bu represents a tert-butyl group.
C. I. Direct Yellow 132: manufactured by JPD C. I. Direct Yellow 142: manufactured by JPD-Proxel LV: antifungal agent, manufactured by Lonza Japan Co., Ltd.

(Example 1)
The obtained ink 1 (black ink), ink 5 (cyan ink), ink 9 (magenta ink), and ink 10 (yellow ink) were combined to form an ink set 1.

(Examples 2-3, and Comparative Examples 1-3)
Ink sets 2 to 6 were obtained in the same manner as in Example 1 except that the ink combination in Example 1 was changed to the ink combination shown in Tables 3 and 4.

  Next, using the above-mentioned ink set, the small color difference of the image was evaluated as follows. The results are shown in Table 5.

<Image color difference>
The ink supply path including the recording head of the printer (IPSiO GX e5500 manufactured by Ricoh Co., Ltd.) is cleaned by passing pure water through it, and the cleaning liquid is sufficiently passed until it does not become colored, and the liquid is completely removed from the device. And used as a printing apparatus for evaluation. Further, each ink used in the ink set was stirred under a reduced pressure condition of 5 Pa or more and 10 Pa or less for 30 minutes to degas the gas in the ink and then filled in the ink cartridge to obtain an evaluation ink cartridge. The ink cartridge was set in the evaluation printing apparatus, filled with ink, and then left overnight. Next, in an environment of 23 ° C. and 40% RH, the following recording conditions (1) to (3) by the ink jet method were used on a paper (trade name: Kasai Photo Finish Pro, manufactured by FUJIFILM Corporation). 6 cm each for blue (RGB value 0,0,255), red (RGB value 255,0,0), green (RGB value 0,255,0), gray (RGB value 127,127,127) Recording was performed so that a corner patch image was obtained, and a patch image was obtained. Using the obtained patch image, a spectral colorimeter (trade name: X-Rite 939, manufactured by X-Rite Co.) was used to perform 9-point color measurement on the patch image to obtain color difference, and the following evaluation criteria Based on the above, the small color difference of the image was evaluated.
[Recording conditions (1) to (3)]
-Recording condition (1): bidirectional recording with four times of main scanning reciprocal recording, recording at 1,200 dpi x 1,200 dpi. Recording speed 8.2 cm ² / sec
-Recording condition (2): bidirectional recording is performed twice in the main scanning reciprocation, and recording is performed at 1,200 dpi x 1,200 dpi. Recording speed 16.6 cm ² / sec
-Recording condition (3): bidirectional recording is performed once in the main scanning reciprocating recording, and recording is performed at 600 dpi x 600 dpi. Recording speed 33.2 cm ² / sec
-Evaluation criteria-
A: ΔE is 3 or less B: ΔE is more than 3 and 7 or less C: ΔE is more than 7 and 11 or less D: ΔE is more than 11

  From the above results, it can be seen that the color difference of the obtained image can be reduced even when bidirectional recording is performed using the ink set in the example.

Aspects of the present invention are as follows, for example.
<1> An ink set having at least two kinds of inks containing a color material, an organic solvent, and water,
The content of the organic solvent in all the ink is 30% by mass or more,
Using thin layer chromatography, obtained by developing the coloring material using the organic solvent in the ink as a developing solvent, relative to the maximum value and the minimum value of the relative mobility of the coloring material in all the inks. The ink set is characterized in that a mobility difference (maximum relative mobility-minimum relative mobility) is 0.1 or more.
<2> The ink set according to <1>, wherein the relative mobility difference (maximum relative mobility-minimum relative mobility) is 0.5 or more.
<3> The ink includes a cyan ink containing a cyan dye, a magenta ink containing a magenta dye, and a yellow ink containing a yellow dye,
The difference between the relative mobility of the cyan dye, the relative mobility of the magenta dye, and the relative mobility of the yellow dye in thin layer chromatography using the organic solvent as a developing solvent is 0.1 or more, respectively. > To <2>.
<4> The ink set according to any one of <1> to <3>, which is used for bidirectional recording by an inkjet method.
<5> The ink set according to any one of <1> to <4>, wherein the content of the coloring material is 0.1% by mass or more and 15% by mass or less.
<6> The ink set according to any one of <1> to <5>, in which the organic solvent is glycerin, 1,3-propanediol, and 2-pyrrolidone.
<7> Mass ratio of the glycerin content (mass%), the 1,3-propanediol content (mass%), and the 2-pyrrolidone content (mass%) (glycerin: 1 , 3-Propanediol: 2-pyrrolidone) is the ink set according to <6>, wherein the ratio is 10: 30: 1.
Is.
<8> The ink set according to any one of <1> to <7>, in which the content of the organic solvent is 30% by mass or more and 60% by mass or less.
<9> The ink set according to any one of <1> to <8>, wherein the content of the organic solvent is 40% by mass or more and 60% by mass or less.
<10> The ink set according to any one of <1> to <9>, wherein the color material is a dye.
<11> The ink set according to any one of <1> to <10>, further containing a surfactant.
<12> An ink cartridge, wherein the ink used in the ink set according to any one of <1> to <11> is contained in a container.
<13> An ink flying step of applying a stimulus to the ink used in the ink set according to any one of <1> to <11> to fly the ink and print an image on a printing medium. And an inkjet recording method.
<14> The inkjet recording method according to <13>, wherein bidirectional recording is performed by an inkjet method.
<15> The inkjet according to any one of <13> to <14>, in which main scanning reciprocal recording for forming the image on the recording medium is four times or less for the same area of the image. It is a recording method.
<16> The inkjet recording method according to <15>, wherein the main-scan reciprocal recording for forming the image on the recording medium is twice or less for the same area of the image.
<17> The inkjet recording method according to any one of <6> to <9>, wherein the recording speed is 8.0 cm ² / sec or more.
<18> An ink jet recording apparatus including an ink flying unit that applies a stimulus to the ink used in the ink set according to any one of <1> to <11> to fly to a recording medium. is there.
<19> A recording head having a plurality of recording units for recording the ink used in the ink set according to any one of <1> to <11> on the entire width in one direction of an image forming area,
The inkjet recording apparatus according to <18>, further comprising: a main scanning drive unit that drives at least one of the recording head and the recording medium to perform reciprocal main scanning recording.
<20> The inkjet recording apparatus according to <19>, wherein the main scanning reciprocal recording is performed four times or less for the same area of the image.

  The ink set according to any one of the items <1> to <11>, the ink cartridge according to the item <12>, the inkjet recording method according to the items <13> to <17>, and the items <18> to <20>. According to the ink jet recording apparatus of any one of the above, it is possible to solve the problems of the related art and achieve the object of the present invention.

Japanese Patent No. 4383778 Japanese Patent No. 5230084

Claims (11)

An ink set having at least two kinds of inks containing a coloring material, an organic solvent, and water, which is used for bidirectional recording by an inkjet method,
The content of the organic solvent in all the ink is 30% by mass or more,
Using thin layer chromatography, obtained by developing the coloring material using the organic solvent in the ink as a developing solvent, relative to the maximum value and the minimum value of the relative mobility of the coloring material in all the inks. An ink set having a mobility difference (maximum relative mobility-minimum relative mobility) of 0.5 or more. The ink includes a cyan ink containing a cyan dye, a magenta ink containing a magenta dye, and a yellow ink containing a yellow dye,
The difference in the relative mobility of the cyan dye, the relative mobility of the magenta dye, and the relative mobility of the yellow dye in thin layer chromatography using the organic solvent as a developing solvent is 0.1 or more, respectively. Ink set described in.   The ink set according to claim 1, wherein the coloring material is a water-soluble dye.   The ink set according to claim 1, wherein the developing solvent does not contain water.   An ink cartridge comprising the ink used in the ink set according to any one of claims 1 to 4 in a container.   An ink flying step of applying a stimulus to the ink used in the ink set according to any one of claims 1 to 4 to fly the ink to bidirectionally record an image on a recording medium. Inkjet recording method.   7. The inkjet recording method according to claim 6, wherein the main scanning reciprocal recording for forming the image on the recording medium is 4 times or less for the same area of the image.   The inkjet recording method according to claim 7, wherein the main scanning reciprocal recording for forming the image on the recording medium is performed twice or less in the same area of the image. The inkjet recording method according to claim 6, wherein a recording speed is 8.0 cm ² / sec or more. An ink jetting unit that applies a stimulus to the ink used in the ink set according to any one of claims 1 to 4 to jet the ink to a recording medium,
A recording head having a plurality of recording portions for recording the ink on the entire width in one direction of the image forming area;
An ink jet recording apparatus, comprising: a main scanning drive unit that drives at least one of the recording head and the recording medium to perform reciprocal main scanning recording. The inkjet recording apparatus according to claim 10, wherein the main scanning reciprocal recording is performed four times or less for the same area of the image.