JP2003334940A - Color inkjet image recorder, method of recording, and ink set - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color inkjet image recorder capable of realizing reproduction of a clear image having little color bleeding on a plain paper at a high speed by using an inkjet recording ink, a method of recording and an ink set. <P>SOLUTION: This color inkjet image recorder comprises the ink set consisting one or more color inks and a black color and an inkjet printing section. An initial contact angle θ<SB>0</SB>of each of the color and black inks on a plain paper is in the range of 30-90°. A contact angle variation amount Xa of the ink A to be printed previously at a time after one second from the time when it is printed is in the range of -70<Xa<-10(°) by an active liquid suction measurement method, and a dot area rate Ya thereof at a time after ta seconds therefrom is in the range of 1.5<Ya. A contact angle variation amount Xb of the ink B to be printed later at a time after one second from the time when it is printed is in the range of -15<Xb<0(°) by the active liquid suction measurement method, and a dot area rate Yb thereof at a time after tb seconds therefrom is in the range of 1.0<Yb<1.7. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color ink jet type image recording apparatus, a recording method and an ink set, and more particularly to a color image recording method, and more particularly to a color ink jet type image recording method for a plain paper. The present invention relates to an ink set for inkjet recording, which can realize clear color reproduction with little color bleeding when a recorded image is recorded on the recording medium.

[0002]

2. Description of the Related Art In recent ink jet recording technology, it has become possible to print a high resolution image at a high speed by ejecting minute ink droplets with the development of a technology for manufacturing a head having highly integrated and highly precise nozzles. ing. In particular, it is possible to record an image having a high resolution and a high image quality equivalent to a silver salt photograph on a medium provided with an ink receiving layer on the surface as a paper for exclusive use of inkjet. However, even with recent inkjet recording technology, the quality of images recorded on plain paper tends to be low, and color bleeding and color mixing (bleeding) at the boundary of adjacent ink dots on plain paper may occur. The problem of being prominent has not yet been resolved.

In Japanese Unexamined Patent Publication No. 6-92008, the contact angle of ink is 5 seconds after dropping on a sized paper.
It is 0 degree or less, and it has been proposed to use an ink containing at least acetylene glycol. However, in actual ink jet recording, the ink droplet dries very quickly, so it is specified only by the contact angle 5 seconds after the dropping. Doing so leaves doubts about its validity.

In Japanese Patent Laid-Open No. 10-330666, a recording material having a size of 10 seconds or more has a wetting time of 0.2 sec or less by a Bristow method and an advancing contact angle of 40.
Although an ink of ° to 70 ° has been proposed, the wetting time by the Bristow method is a value that indicates the unevenness of the paper and captures the penetration of the ink macroscopically. Unlike the penetration of drops,
The relationship between ink bleeding and high-speed printing is unknown.

In Japanese Patent Laid-Open No. 2000-144028,
The rate of change over time of the dynamic contact angle on plain paper is 0.5 to 3.
Although a pigment ink of 5 degrees / second is proposed, the ink penetration is considerably slow and color mixing cannot be avoided.

As described above, various ink jet recording inks and recording methods have been proposed in order to suppress ink bleeding and color mixing. However, the control of bleeding and color mixing on plain paper is still insufficient, and an image is printed. At that time, it becomes blurred as a whole and a delicate image cannot be obtained. In recent years, inkjet recording requires higher image quality and higher speed, and there is a need for more detailed control technology.However, the development of inks and recording methods that fully satisfy these requirements is unsuccessful. The current situation is that it has not been done.

[0007]

Therefore, the present invention, when used as an ink for ink jet recording, can realize vivid color reproduction with little color bleeding even on high speed recording on plain paper, and a color ink jet system with less bleeding. An object is to provide an image recording device, a recording method, and an ink set.

[0008]

As a result of intensive studies to solve the above problems, the inventors of the present invention have found that the amount of change in the dynamic contact angle between the ink A to be printed first and the ink B to be printed later and The inventors have found that it is possible to obtain a clear color reproduction with less color bleeding and less ink bleeding by defining the change rate of the dot radius, and have completed the present invention.

That is, the present invention provides an ink set comprising one or more color inks containing a color dye and water as essential components and a black ink containing black pigment and water as essential components, and these inks having a smoothness. A color inkjet image recording apparatus comprising an inkjet printing unit for printing on plain paper of 100 sec or less, wherein the smoothness of at least one color ink of the ink set and two inks of black ink on the plain paper is 100 sec or less. Initial contact angle θ _{0 in} the range of 30 to 80 °, and for one ink A and the other ink B of the two color inks, 1 second after the dynamic liquid absorption measurement of the ink A. Contact angle change amount Xa of -70 <Xa <-10 (°)
And the dot area ratio Ya of ink A after ta seconds
Is in the range of 1.5 <Ya, and the contact angle change amount Xb after 1 second by the dynamic liquid absorption measurement of the ink B is −10 <Xb <
In the range of 0 (°), the dot area ratio Yb of the ink B after tb seconds is in the range of 1.0 <Yb <1.5, and the ink-jet printing unit prints the ink A before the ink B. It is a color inkjet type image recording device for printing. However, the contact angle change amount X = θ−θ ₀ , the dot area ratio Y = r _t ² / r ₀ ² , 0.1 <ta ≦ 5 (s), 0 <tb
≦ 10 (s), and θ is printing of ink A or B 1
The dynamic contact angle after seconds, r ₀ and r _t are the radii of dots when ink A or B is printed and after ta or tb seconds, respectively. The amount of liquid droplets in the dynamic liquid absorption measurement is 2 μL.

The present invention is also a color ink jet image recording apparatus in which the above-mentioned ink set is a self-dispersion type black pigment of black ink.

According to the present invention, the above ink set is
This is a color inkjet image recording apparatus in which at least one color ink contains at least one polyhydric alcohol or polyhydric alcohol ether.

Further, in the present invention, the above polyhydric alcohol or polyhydric alcohol ether is ethylene glycol monoalkyl ethers, diethylene glycol monoalkyl ethers, triethylene glycol monoalkyl ethers, propylene glycol monoalkyl ethers, dipropylene. Glycol monoalkyl ethers,
And a color inkjet image recording apparatus selected from the group consisting of: and an alkoxy-substituted aliphatic alcohol.

The present invention is also a color ink jet image recording apparatus in which the above ink set contains at least one color ink containing a glycol type or acetylene glycol type surfactant.

According to the present invention, the above ink set is
The surface tension of at least one color ink is 20 to 70 dyn
It is an image recording device of a color inkjet system in the range of e / m.

Furthermore, the present invention is a color ink jet system image recording apparatus in which the ink set has a viscosity of at least one color ink in the range of 1 to 20 cp.

The present invention is also a color ink jet image recording apparatus in which the above-mentioned ink set contains at least one color ink as a fixing resin, a water-soluble resin and / or an emulsion and / or a latex.

According to the present invention, the above ink set is
Ink A is a color ink, and ink B is a black ink.

Further, in the present invention, one or more color inks containing a color dye and water as essential components and a black ink containing a black pigment and water as essential components are jetted onto plain paper having a smoothness of 100 sec or less. In the image recording method of printing with, the initial contact angle θ _{0 of} at least one color ink and two colors of black ink on the plain paper having a smoothness of 100 sec or less is in the range of 30 to 80 °, and For the ink C and the ink D of the two color inks, the contact angle change amount Xc after 1 second by the dynamic liquid absorption measurement of the ink C is in the range of −70 <Xc <−10 (°). , Dot area ratio Yc of ink C after tc seconds
Is in the range of 1.5 <Yc, and the contact angle change amount Xd after 1 second by the dynamic liquid absorption measurement of the ink D is −10 <Xd <
A color inkjet in the range of 0 (°), the dot area ratio Yd of the ink D after td seconds is in the range of 1.0 <Yd <1.5, and the ink C is printed before the ink D. System image recording method. However, the contact angle variation X = θ-θ _0, the dot area ratio ^{_{Y = r t 2 / r 0}} 2, 0.1
<Tc ≦ 5 (s), 0 <td ≦ 10 (s), and θ
Indicates the dynamic contact angle after 1 second of printing, and r ₀ and r _t indicate the radius of the dot at the time of printing and at tc or td seconds later, respectively. In addition, the amount of liquid droplet in the dynamic liquid absorption measurement is 2 μL
Is.

The present invention also provides an ink jet recording ink set comprising at least one color ink containing a color dye and water as essential components and a black ink containing black pigment and water as essential components. The smoothness of the two color inks, color ink E and black ink F, is 1
The initial contact angle θ ₀ on plain paper of 00 sec or less is in the range of 30 to 80 °, and the contact angle change amount Xe after 1 second by the dynamic liquid absorption measurement of the color ink E is
It is in the range of −70 <Xe <−10 (°), the dot area ratio Ye of the color ink E after te seconds is in the range of 1.5 <Ye, and the dot area ratio Ye of the black ink F is 1 by the dynamic liquid absorption measurement. The contact angle change amount Xf after seconds is in the range of −10 <Xf <0 (°), and the dot area ratio Yf of the black ink F after tf seconds is:
The ink set for inkjet recording is in the range of 1.0 <Yf <1.5. However, the contact angle change amount X = θ−
theta _0, dot area ratio ^{_{Y = r t 2 / r 0}} 2, 0.1 <te ≦ 5
(S), 0 <tf ≦ 10 (s), and θ is the dynamic contact angle one second after printing, and r ₀ and r _t are when printing and at t
The radius of the dot after e or tf seconds is shown.
The amount of liquid droplets in the dynamic liquid absorption measurement is 2 μL.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described.
The color inkjet image recording apparatus of the present invention includes an ink set and an inkjet printing unit, and the ink set includes at least one color ink containing a color dye and water as essential components, a black pigment and water as essential components. And a combination with black ink. For the color ink and the black ink, the contact angle θ of the ink and the dot radius r can be adjusted by adding a surfactant or a water-soluble organic solvent. The contact angle change amount X (see the following formula 1) is -70 <Xa <-10.
(°), more preferably in the range of −50 <Xa <−20 (°), and the dot area ratio Ya after ta seconds satisfying 0.1 <ta ≦ 5 (s) (see the following formula 2) is 1 It is preferable to be in the range of 0.5 <Ya, more preferably 5.0 <Ya. It is difficult to create an ink in which the initial contact angle becomes smaller as the ink having a larger contact angle change amount Xa becomes smaller, and it is difficult to make an ink in which the Xa falls below the lower limit. Cause of.

The other ink B has a contact angle change amount Xb (see the following formula 1) of -10 <Xb after 1 second by dynamic liquid absorption measurement.
<0 (°) range, more preferably -7 <Xb <0
T in the range of (°) and satisfying 0 <tb ≦ 10 (s)
The dot area ratio Yb after b seconds (see the following formula 2) is 1.0 <
Y <1.5 range, more preferably 1.0 <Yb <1.
It is preferably within the range of 4. When the contact angle change amount Xb is below the lower limit or the dot area ratio Yb is above the upper limit, the ink permeation becomes faster, and the previously printed ink A
It causes the color mixture with.

In the above equation 1, the contact angle change amount X = θ−
θ ₀ and the above equation 2 is the dot area ratio Y = r _t ² / r ₀ ²
Is. Further, θ ₀ and θ represent a dynamic contact angle at the time of printing (initial contact angle) and one second after printing, and r ₀ and r _t represent a radius of a dot at the time of printing and t seconds later, respectively. It should be noted that the smoothness was measured on plain paper with 100 sec or less, and the liquid drop amount in the dynamic liquid absorption measurement was 2 μL.
(Liter).

The ink jet printing section of the color ink jet type image recording apparatus of the present invention has a smoothness of 100 se.
Ink A is printed on plain paper of c or less before ink B of the ink set.

In the color ink jet type image recording apparatus and recording method of the present invention, one ink droplet is landed on the recording material, and the next ink droplet adjacent to or overlapping the ink droplet is recorded. By allowing all the ink droplets that have landed first to permeate into the recording material before landing on the material, color mixing of the ink is prevented, and the permeation speed is too fast and the ink does not bleed laterally. As described above, by forming an image by an ink jet recording method using an ink and an ink set in which the contact angle of the ink and its area change rate are limited, a clear image without ink bleeding or color mixture on plain paper is obtained, In addition, the image printing time can be shortened to the maximum.

By adopting the ink jet recording system of the present invention, it is possible to obtain a clear image without blurring or color mixture on plain paper by high-speed printing.

Next, the color ink jet type image recording apparatus and recording method of the present invention, the colorant used in the ink set, and the recording liquid containing a solvent for dispersing or dissolving the colorant will be described. As the color water-soluble dye used as a colorant, an acid dye, a direct dye, a basic dye, a reactive dye, an edible dye and the like are used. These can be used as a mixture, if necessary, and are added in a range that does not inhibit the effect. Specific examples of these dyes include acid dyes and food dyes such as C.I. I. Acid Yellow 17,23,42,44,79,14
2, C.I. I. Acid Red 1,8,13,14,1
8, 26, 27, 35, 37, 42, 52, 82, 8
7, 89, 92, 97, 106, 111, 114, 11
5,134,186,249,254,289, C.I.
I. Acid Blue 9,29,45,92,249,
C. I. Food Yellow 3,4, C.I. I. Food Red 7, 9, 14 and C.I. I.
Direct Yellow I1, 12, 24, 26, 33,
44, 50, 86, 120, 132, 142, 14
4, C.I. I. Direct Red 1,4,9,13,1
7, 20, 28, 31, 39, 80, 81, 83, 8
9, 225, 227, C.I. I. Direct orange 2
6,29,62,102, C.I. I. Direct blue
1, 2, 6, 15, 22, 25, 71, 76, 79, 8
6,87,90,98,163,165,199,20
2, and as a basic dye, C.I. I. Basic Yellow 1, 2, 11, 13, 14, 15, 19, 21,
23, 24, 25, 28, 29, 32, 36, 40, 4
1,45,49,51,53,63,64,65,6
7, 70, 73, 77, 87, 91, C.I. I. Basic Red 2,12,13,14,15,18,22,
23, 24, 27, 29, 35, 36, 38, 39, 4
6,49,51,52,54,59,68,69,7
0, 73, 78, 82, 102, 104, 109, 11
2, C.I. I. Basic Blue 1, 3, 5, 7, 9,
21, 22, 26, 35, 41, 45, 47, 54, 6
2,65,66,67,69,75,77,78,8
9, 92, 93, 105, 117, 120, 122, 1
24,129,137,141,147,155, and C.I. I. Reactive Yellow 1,5,11,13,14,20,21,22,2
5, 40, 47, 51, 55, 65, 67, C.I. I. Reactive Red 1, 14, 17, 25, 26, 32,
37,44,46,55,60,66,74,79,9
6,97, C.I. 1. Reactive blue 1, 2, 7,
14, 15, 23, 32, 35, 38, 41, 63, 8
0,95 etc. can be used.

As the black pigment, carbon black generally used for black ink is used, but preferably, a self-dispersing carbon black which is electrically charged and dispersed in water is exemplified. Specifically, carbon black can be self-dispersed in water by subjecting it to surface modification treatment such as acid / base treatment, coupling agent treatment, polymer graft treatment, plasma treatment, and oxidation / reduction treatment. A pigment can be obtained. As a pigment self-dispersible in water,
In addition to the pigment obtained by subjecting the pigment to the surface modification treatment as described above, Cab-o-jet-200, C manufactured by Cabot Corporation.
ab-o-jet-300, IJX-55, Microjet Black CW-1 manufactured by Orient Chemical Company.
Alternatively, commercially available pigments such as those sold by Nippon Shokubai Co., Ltd. can be used.

The colorant used in the ink jet recording liquid in the present invention is preferably 0.5 to 20.0% by weight, and 1.0 to 1% by weight based on the weight of the ink jet recording liquid.
0.0% by weight is more preferable. When the amount of the coloring material is less than 0.5% by weight, sufficient image density cannot be obtained,
If it exceeds 20.0% by weight, the fixing property of the image may be deteriorated.

Next, the ink jet recording liquid of the present invention contains the following water-soluble organic solvent for the purpose of achieving desired physical properties, preventing drying of the recording liquid, and improving dissolution stability. You may mix and use two or more. That is, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,5-pentanediol, 1,6-hexanediol, glycerin, 1,
Polyhydric alcohols such as 2,6-hexanetriol, 1,2,4-butanetriol, 1,2,3-butanetriol and petriol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, Polyhydric alcohol alkyl ethers such as diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether and propylene glycol monoethyl ether, polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether, N -Methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethylimidazolidino , Nitrogen-containing heterocyclic compounds such as ε- caprolactam, formamide, N- methylformamide,
Formamide, amides such as N, N-dimethylformamide, amines such as monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine, triethylamine, dimethyl sulfoxide, sulfolane, thiodiethanol, ethylene urea,
Sulfur-containing compounds such as urea, propylene carbonate, ethylene carbonate, γ-butyrolactone and the like can be used alone or in combination.

Polymeric dispersants or binders that can be used in the present invention include proteins such as gelatin, albumin and casein, natural gums such as gum arabic, glucosides such as savonine, lignin sulfonate and shellac. Natural polymer, polyurethane resin, polyester resin,
Epoxy resin, acrylic resin or the like is used. These may be added alone or in combination of two or more.

From the dischargeability of the ink jet recording liquid in the color ink jet type image recording apparatus of the present invention,
Surface tension is 20 to 70 N / m, preferably 25 to 45 N
/ M is good. A surfactant may be added to control the permeability of the recording medium. The surfactant to be added is preferably one having good compatibility with other components of the inkjet recording liquid, and among the surfactants, those having high permeability and stability are particularly preferable. Specific examples thereof include nonionic surfactants. Examples of nonionic surfactants include polyoxyethylene-based surfactants, polyoxypropylene-based surfactants, polyoxy (ethylene-propylene) -based nonionic surfactants, polyoxyacetylene-based surfactants, polyoxyethylene nonylphenyl ethers. Ether system such as polyoxyethylene alkyl allyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, polyoxyethylene alkyl ether, polyoxyalkylene alkyl ether, polyoxyethylene oleic acid, polyoxyethylene oleic acid ester, poly Ester systems such as oxyethylene distearate, sorbitan laurate, sorbitan monostearate, sorbitan monooleate, polyoxyethylene stearate, etc. Other fluorine alkyl esters, such as fluorine-containing surfactants such as perfluoroalkyl carboxylate are exemplified.

Further, from the ejection property of the ink jet recording liquid in the color ink jet type image recording apparatus of the present invention, the viscosity is 1.0 to 10 m.s. 0 Pa · s is preferable, and a hydrophilic polymer compound can be added to adjust the viscosity. Examples of such hydrophilic polymer compounds include gum arabic, traggan gum, guar gum, karaya gum, locust bean gum, arabinagalactone, pectin, quince seed starch, and other plant polymers, alginic acid, carrageenan, and agar in a natural system. Seaweed macromolecules, animal macromolecules such as gelatin, casein, albumin and collagen, microbial macromolecules such as xanthene gum and dextran, shellac, etc. Fibrin-based polymers such as xymethylcellulose, starch-based polymers such as sodium starch glycolate and starch phosphate sodium, sodium alginate, propylene glycol alginate, etc. Algae-based polymer,
In pure synthetic systems, vinyl-based polymers such as polyvinyl alcohol, polyvinylpyrrolidone, and polyvinyl methyl ether,
Non-crosslinked polyacrylamide, polyacrylic acid and its alkali metal salts, acrylic resins such as water-soluble styrene acrylic resin, water-soluble styrene maleic acid resin, water-soluble vinyl naphthalene acrylic resin, water-soluble vinyl naphthalene maleic acid resin, polyvinyl pyrrolidone, Examples thereof include polyvinyl alcohol, an alkali metal salt of a β-naphthalenesulfonic acid formalin condensate, and a polymer compound having a side chain of a salt of a cationic functional group such as quaternary ammonium or amino group.

Further, conventionally known additives for recording liquids can be added to the ink jet recording liquid of the present invention. For example, as antiseptic / antifungal agents, sodium dehydroacetate, sodium sorbate, sodium 2-pyridinethiol-1-oxide, sodium benzoate, sodium pentachlorophenol and the like can be used. As the pH adjuster, any substance can be used as long as it can adjust the pH to 7 or more without adversely affecting the ink to be prepared, and examples thereof include diethanolamine and triethanolamine. Such as amines, hydroxides of alkali metal elements such as lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonium hydroxide, quaternary ammonium hydroxide, quaternary phosphonium hydroxide, lithium carbonate, sodium carbonate , Carbonates of alkali metals such as potassium carbonate, and the like. Examples of chelate samples include sodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, and sodium uramildiacetate. As the rust preventive, for example, acidic sulfite,
Examples thereof include sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate and dicyclohexylammonium nitrite. In addition, a water-soluble ultraviolet absorber, a water-soluble infrared absorber, a solubilizing agent, an antioxidant and the like can be added depending on the purpose.

Next, the present invention will be specifically described based on Examples and Comparative Examples, but the present invention is not limited to these Examples. First, the compositions of the inks used in Examples and Comparative Examples are shown below. In addition,% is based on weight. Regarding the composition, the types of dyes, pigments, solvents and additives and the addition amounts are as shown in FIG. 1, and ion-exchanged water was added as the remaining amount so that the total amount was 100. A-1 to A-4 are cyan, magenta, and yellow color inks, and the dyes used are Direct Blue 199, Reactive Red 180, and Acid Yellow 23. B-1 to B-6 are black inks and use self-dispersion type carbon black.

The components of the ink of FIG. 1 were mixed, stirred and mixed at 25 ° C. for 1 hour, and then pressure-filtered and degassed using a 1.2 μm membrane filter to obtain ink A-1.
~ A-4 were prepared.

The ink thus obtained was subjected to dynamic contact angle measurement on Sharp NM4A2S as plain paper to measure the initial contact angle, the dot radius, the contact angle after a fixed time, and the time change of the dot radius. The results are shown in FIG. The dynamic contact angle was measured as follows. In the environment of 25 ° C. and 60% RH, the dynamic contact angle measurement was performed by using a DAT device manufactured by Fibro to drop 2 μL of ink droplet on Sharp NM4A2S and measuring the contact angle θ. The initial contact angle is θ ₀ (a value measured immediately after the ink droplets land on the surface of the recording material), the contact angle 1 second after the ink droplets land is θ, and X = θ−θ ₀ And

Also, let the initial ink dot radius be r ₀ ,
After 10 seconds for ink A, 5 for ink B
Let dot radius after second be r _t, and dot area ratio Y = r _t ² /
Let r ₀ ² .

Next, the created A-1 to A-4 and B-1 to B
The ink composition of No. -5 was used for an inkjet printer (trade name: CL-700 (manufactured by Epson Corp.)), and the combinations shown in Examples 1 to 4 and Comparative Examples 1 to 9 in FIG. The evaluation pattern is printed on the following items, and (a) evaluation of color mixture (bleed) between inks A and B,
(B) Image bleeding evaluation, (c) Dryability test Evaluation tests were conducted on Sharp NM4A2S.

(A) Color mixture between inks A and B (bleed)
The yellow solid of ink A was printed under the environment of evaluation 25 ° C. and 25 RH, and the alphabet letters were printed with ink B on it. After 1 minute, color mixture bleeding at the boundary between both colors was visually evaluated. The evaluation criteria are shown below. A: Almost no ink scattering / color mixing, and dots and edges between two colors are extremely sharp. A: Some ink scattering and color mixing are seen, but the dots and the edge between the two colors are sharp. Δ: Ink scattering and color mixing are observed in almost all dots, and the dots and the edge between the two colors are slightly blurred. ×: Ink scattering and color mixture are seen in all dots, and dots and edges between two colors are not clear.

(B) Image bleeding evaluation In the environment of 25 ° C. and 25 RH, seven colors of RGBCMYK and an evaluation image were printed, and 1 minute later, the following evaluation was performed. The evaluation criteria are shown below. ◎ ... High quality with almost no bleeding or whiskers. ○: Bleeding and whiskers are slightly seen, but the overall image quality is good. Δ: Bleeding, beard were noticeable, and image quality was poor. ×: Bleeding and whiskers were very noticeable and the image quality was also very poor.

(C) Dryability test image An evaluation image was printed in an environment of 25 ° C. and 25 RH, and the judgment was made based on the time until the printed part was rubbed without rubbing with a filter paper. The evaluation criteria are shown below. ○: within 10 seconds △: within 10 seconds to 20 seconds ×: over 20 seconds

The evaluation results of Examples 1 to 4 and Comparative Examples 1 to 9 are shown in FIG. From this result, the larger the dot diameter area ratio Ya of the ink A, the better the color bleed. This is because the larger Ya is, the faster the ink permeates, and when the next dot is hit, the previous ink dries and the color bleed is suppressed. Further, the smaller the dot area ratio Yb of the ink B, the better the color mixture bleeding between A and B. In this case, since the ink does not spread after printing, bleeding due to penetration into paper and whiskers are less likely to occur. However, a comparison between Example 1 and Comparative Example 7 shows that the color mixture bleeding between A and B is worse even though the dot area ratio Yb of the ink B is small. In Comparative Example 7, since the dot area ratio Ya of the ink A is small and the drying is slow, the ink B is not sufficiently dried by the time the ink B arrives and color mixing occurs.

As described above, the ink A having a large amount of change in the dynamic contact angle and the large dot area ratio to be printed first and the ink B having a small amount of change in the dynamic contact angle of the ink to be printed and a small ink B having the small dot area ratio are printed. It was found that by combining them, it is possible to obtain a clear color reproduction with less color bleeding and to obtain an ink set for inkjet recording with less bleeding.

In the color-jet type image recording apparatus and recording method and ink set of the present invention, two kinds of ink having a specified dynamic contact angle and dot area ratio are used, so that color bleeding is reduced and clear even on plain paper. The effect that color reproduction can be realized, high-quality color images with less bleeding can be provided, and cheap plain paper can be used without using expensive special paper, leading to low running costs. Also has.

[0045]

According to the present invention, when used as an ink for ink jet recording, clear color reproduction with little color bleed can be realized even at high speed recording on plain paper.
Further, it is possible to obtain a color inkjet type image recording apparatus and recording method with less bleeding and an ink set.

[Brief description of drawings]

FIG. 1 is a diagram illustrating raw materials of inks used in Examples and Comparative Examples.

FIG. 2 is a diagram illustrating characteristics of inks used in Examples and Comparative Examples.

FIG. 3 is a diagram illustrating evaluation of ink sets of Examples and Comparative Examples.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI Theme Coat (reference) B41J 3/04 101Y (72) Inventor Hiromi Nakatsu 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Prefecture Sharp Corporation (72) Inventor Kiyofumi Morimoto 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Within Sharp Corporation (72) Inventor Shota Suzuki 22-22, Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Within Sharp Corporation (72) Inventor Ichiro Fujii 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Prefecture Sharp Corporation (72) Inventor Hiroaki Nakaya 22-22 Nagaike-cho, Abeno-ku, Osaka City Osaka Prefecture F-term (reference) 2C056 EA05 FC01 2H086 BA02 BA21 BA41 BA44 BA55 BA56 BA59 BA60 BA61 4J039 AB01 AB07 AB09 AD10 AE04 AE05 AE06 BA04 BC07 BC08 BC09 BC12 BC13 BC14 BC15 BE01 BE02 BE 22 BE28 CA03 CA06 EA19 EA47 EA48 GA24

Claims (11)

[Claims] 1. An ink set comprising one or more color inks containing a color dye and water as essential components and a black ink containing a black pigment and water as essential components, and these inks having a smoothness of 100 sec or less. In a color inkjet image recording apparatus including an inkjet printing unit for printing on paper, an initial contact angle of at least one color ink of the ink set and two colors of black ink on a plain paper having a smoothness of 100 sec or less. θ ₀ is 30 to 80
The contact angle change amount Xa after 1 second of the ink A of one of the two color inks and the ink B of the other of the two color inks by the dynamic liquid absorption measurement is −70 <
In the range of Xa <-10 (°), the dot area ratio Ya of the ink A after ta seconds is in the range of 1.5 <Ya, and the contact angle of the ink B after 1 second by the dynamic liquid absorption measurement. Change amount Xb
Is in the range of −10 <Xb <0 (°), and the dot area ratio Yb of the ink B after tb seconds is 1.0 <Yb <1.5.
And the ink jet printing section prints the ink A before the ink B. However, the contact angle variation X = θ-θ _0, the dot area ratio ^{_{Y = r t 2 / r 0}} 2, 0.
1 <ta ≦ 5 (s), 0 <tb ≦ 10 (s), and
θ is the dynamic contact angle of ink A or B one second after printing, r
₀ and r _t when printing ink A or the B is and ta
Alternatively, the radius of the dot after tb seconds is shown. The amount of liquid droplets in the dynamic liquid absorption measurement is 2 μL. 2. The color inkjet image recording apparatus according to claim 1, wherein the black pigment of the ink set is a self-dispersion pigment. 3. The color inkjet image recording apparatus according to claim 1, wherein at least one color of the ink set contains at least one polyhydric alcohol or polyhydric alcohol ether. 4. The polyhydric alcohol or polyhydric alcohol ether is ethylene glycol monoalkyl ethers, diethylene glycol monoalkyl ethers, triethylene glycol monoalkyl ethers, propylene glycol monoalkyl ethers, dipropylene glycol monoalkyl ethers. The color inkjet image recording apparatus according to claim 3, wherein the color inkjet image recording apparatus is selected from the group consisting of groups and alkoxy-substituted aliphatic alcohols. 5. The color inkjet image recording apparatus according to claim 1, wherein at least one color of the ink set contains a glycol-based or acetylene glycol-based surfactant. 6. The color inkjet image recording apparatus according to claim 1, wherein the ink set has a surface tension of at least one color ink in a range of 20 to 70 dyne / m. 7. The ink set according to claim 1, wherein the viscosity of at least one color ink is in the range of 1 to 20 cp.
2. The color inkjet image recording apparatus according to any one of 1. 8. The color inkjet image recording according to claim 1, wherein in the ink set, at least one color ink contains a water-soluble resin and / or an emulsion and / or a latex as a fixing resin. apparatus. 9. The ink set according to claim 1, wherein the ink A is a color ink and the ink B is a black ink.
2. The color inkjet image recording apparatus according to any one of 1. 10. A color dye and water as essential components 1
An image recording method of printing a color ink of at least one color and a black ink containing a black pigment and water as an essential component on a plain paper having a smoothness of 100 sec or less by an inkjet method, comprising at least one color ink and a black ink. The initial contact angles θ _{0 of the} color inks on plain paper having a smoothness of 100 sec or less are in the range of 30 to 80 °, and the ink C and the ink D of the two color inks are The contact angle change amount Xc after 1 second by the dynamic liquid absorption measurement is in the range of −70 <Xc <−10 (°), and the dot area ratio Yc of the ink C after tc seconds is 1.5.
<Yc range, 1 by dynamic liquid absorption measurement of ink D
The amount of change in contact angle Xd after second is in the range of −10 <Xd <0 (°), and the dot area ratio Yd of the ink D after td seconds has passed.
Is in the range of 1.0 <Yd <1.5, and the ink C is printed before the ink D. A color inkjet image recording method. However, the contact angle variation X = θ-θ _0, the dot area ratio ^{_{Y = r t 2 / r 0}} 2, 0.
1 <tc ≦ 5 (s), 0 <td ≦ 10 (s), and
θ represents a dynamic contact angle one second after printing, and r ₀ and r _t represent dot radii at the time of printing and after tc or td seconds, respectively. In addition, the amount of droplets in the dynamic liquid absorption measurement is 2
It is L. 11. A color dye and water as essential components 1
In an inkjet recording ink set comprising a combination of color inks of at least one color and a black ink containing black pigment and water as essential components, the smoothness of at least one color ink E and two color inks F The initial contact angle θ ₀ on plain paper for 100 seconds or less is 30 to 30
In the range of 80 °, and the contact angle change amount Xe after 1 second by the dynamic liquid absorption measurement of the color ink E is −70 <Xe.
<−10 (°), the dot area ratio Ye of the color ink E after te seconds is in the range of 1.5 <Ye,
The contact angle change amount Xf of the black ink F after 1 second by the dynamic liquid absorption measurement is in the range of −10 <Xf <0 (°), and the dot area ratio Yf of the black ink F after tf seconds is 1. .0 <Yf <
An ink set for inkjet recording, which is in the range of 1.5. However, the contact angle change amount X = θ−
theta _0, dot area ratio ^{_{Y = r t 2 / r 0}} 2, 0.1 <te ≦ 5
(S), 0 <tf ≦ 10 (s), and θ is the dynamic contact angle one second after printing, and r ₀ and r _t are when printing and at t
The radius of the dot after e or tf seconds is shown.
The amount of liquid droplets in the dynamic liquid absorption measurement is 2 μL.