JP2000144023A - Ink set for ink jet recording - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink set, which ensures no blotting at the boundary between a yellow ink and a black ink, by adding a specified ratio of an Ni ion to a black ink in an ink set composed of two or more colors including yellow and black. SOLUTION: An Ni ion is added, in an amount of 0.001 wt.% or above, to a black ink of an ink set, which comprises a colorant, a wetting agent and a surface active agent dispersed or dissolved in water. The Ni ion is added after preparation of the black ink. Especially, a greater effect can be expected when Pro-jet Fast Yellow 2 (commercial name of Zeneca Co., Ltd.) is used as a colorant for yellow ink. In the ink set, it is preferred to adjust the pH of the black ink to 7 to 10 and the pH of the yellow ink to 8 to 11. For a pH adjustor, there is used a substance, which does not adversely influence the inks to be prepared, e.g. an alkali metal hydroxide or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink set for two or more colors used in an ink jet printer, and more particularly to an ink set for ink jet recording which provides high quality image without causing border bleeding.

[0002]

2. Description of the Related Art An ink jet recording method is capable of high-speed recording, is capable of recording on a recording medium in a non-contact manner, so that various types of recording media such as plain paper can be used, and color images can be produced at low cost. In recent years, there has been a remarkable spread state because of the advantages such as the fact that it is possible to obtain

In order to perform good print recording over a long period of time in such ink jet recording, it is necessary that the ink used satisfies the following conditions. Excellent ejection characteristics, such as ink ejection direction stability and ejection stability, and excellent storage stability of the ink, that is, precipitation due to chemical change during long-term storage, continuous use, or recording suspension No clogging of nozzles and changes in physical properties of the ink that occur, the contrast of the recorded image is sufficiently high, the image is clear and clear, the drying of the recorded image is fast, The resulting image has excellent storability such as water resistance and weather resistance, and has a high-purity color tone as a color ink for a full-color printer, and can form an image with excellent color reproducibility.

[0004] In order to satisfy the above requirements, many proposals have been made on inks for ink-jet recording, but inks satisfying all of the above conditions have not yet been obtained. These properties are often mainly attributed to the dye which is a colorant in the composition constituting the ink. For example, a clear image with high contrast can be obtained with a high dye concentration, but a high dye dissolution stability is required to increase the dye concentration. However, when the dissolution stability of the dye is increased, the storage stability and ejection stability of the ink are increased, but on the contrary, the water resistance of the printed image is deteriorated. In the formation of a color image, it is also important that the print image has high drying properties in order to eliminate the bleeding between colors and obtain a high-resolution image. In addition, the color tone of each dye for good color tone reproduction is also an important issue.

[0005]

Regarding the above problem, Japanese Patent Application Laid-Open No. 8-310116 discloses an ink set combining Y, M, C, and Bk dyes having a specific structure. However, these dyes have insufficient water resistance. In addition, color tone and color reproducibility are not satisfactory. Japanese Patent Application Laid-Open No. 8-325493 discloses an ink set using a yellow dye having a specific structure by the present applicant. This ink set is excellent in color tone, color reproducibility, water resistance, and ejection stability. However, particularly when printing is performed on plain paper, the problem of bleeding with the black ink has not been completely solved.

The present invention has been made in view of the above background, and is excellent in color tone, color reproducibility, water resistance, weather resistance, and ejection stability, and particularly, ink jet recording ink which does not cause bleeding of the boundary between yellow ink and black ink. The purpose is to provide a set.

[0007]

According to the present invention, first, the ink comprises at least two colors of yellow and black inks containing a colorant, a wetting agent and a surfactant which are dispersed or dissolved in water. An ink set for ink jet recording is provided, wherein the black ink in the ink set contains 0.001% by weight or more of Ni ions.

[0008] Second, in the ink set for ink jet recording described in the first aspect, the yellow ink in the ink set is used as a colorant for Pro-jet Fast.
An ink set for inkjet recording, comprising Yellow 2 (manufactured by ZENECA) is provided.

Third, in the ink set for ink jet recording described in the first aspect, the surfactant contained in the ink in the ink set is a polyoxyethylene alkyl ether acetate represented by the following general formula (I): Or an ink set for inkjet recording, characterized by being a dialkyl sulfosuccinate represented by the following general formula (II).

[0010]

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[0011]

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Fourth, in the ink set for ink jet recording according to the first aspect, the surfactant contained in the ink in the ink set is a nonionic surfactant. A set is provided.

Fifth, in the ink set for ink jet recording described in the first aspect, the wetting agent contained in the ink in the ink set is a polyhydric alcohol alkyl ether and / or a polyhydric alcohol aryl ether. An ink set for ink-jet recording is provided.

Sixth, in the ink set for ink jet recording according to the first or second aspect, the colorant of the black ink is represented by the following general formula (III) or (IV)
And at least one selected from the group of compounds represented by formula (V).

[0015]

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[0016]

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[0017]

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Seventh, in the ink set for ink jet recording described in the first, second or sixth aspect, the pH of the black ink is 7 or more and 10 or less, and the pH of the yellow ink is 8 or more and 11 or less. An ink set for ink-jet recording is provided.

Hereinafter, the present invention will be described in detail. As described above, the ink-jet recording ink set of the present invention is an ink-jet recording ink set comprising at least two inks of yellow and black containing a colorant, a wetting agent and a surfactant which are dispersed or dissolved in water. In the above, the black ink in the ink set is Ni
It is characterized by containing not less than 0.001% by weight of ions. That is, according to such an ink set, blurring of the boundary between the yellow ink and the black ink on plain paper is prevented, and a color image having high quality image quality can be obtained.

The above-described effect is obtained by using Pro-jet Fast Yellow 2 (Z
This is particularly large when Eneca Corporation is used. It is considered that the effect of suppressing the boundary bleeding according to the present invention is because Ni ions in the black ink and the colorant in the yellow ink form a chelate.

The surfactant contained in the ink of the ink set according to the present invention may be a polyoxyethylene alkyl ether acetate represented by the above general formula (I) or a dialkyl sulfosuccinate represented by the above general formula (II) ,
Alternatively, a nonionic surfactant is preferable.
In other words, by using these surfactants, it is possible to increase the permeability of the ink to the recording paper, and in particular, to increase the permeability in the vertical direction on the recording paper, and it is quick drying and has excellent clarity with little bleeding. Further, it is possible to obtain an image having high image quality with less border bleeding.

Further, the wetting agent contained in the ink of the ink set according to the present invention is preferably a polyhydric alcohol alkyl ether or a polyhydric alcohol aryl ether, or a mixture thereof. That is, by containing these wetting agents, the evaporation of water in the ink can be prevented, the discharge failure due to the precipitation of the dye at the ink discharge port and the increase in viscosity can be further suppressed, and an ink set with high discharge reliability can be provided. be able to.

In the ink set according to the present invention, the colorant of the black ink is represented by the general formula (II)
Compounds represented by I), (IV) and (V) are preferred. According to these dyes, an ink set having an excellent effect of preventing the above-described boundary bleeding and a good color tone can be obtained.

In the ink set according to the present invention, it is preferable that the pH of the black ink is set to 7 or more and 10 or less, and the pH of the yellow ink is set to 8 or more and 11 or less. By doing so, the effect of preventing boundary bleeding can be more effectively exerted.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Ni ions may be added after preparing a black ink, and it is necessary that the amount of Ni ions be adjusted so that the Ni content in the ink is 0.001% by weight or more. is there.

Next, specific examples of the polyoxyethylene alkyl ether acetate represented by the general formula (I) and the dialkyl sulfosuccinate represented by the general formula (II) are shown in Tables 1 and 2.

[0027]

[Table 1]

[0028]

[Table 2]

The content of these surfactants is 0.1
It is suitably from 05% by weight to 10% by weight, preferably from 0.1% to 5% by weight, more preferably from 0.1% to 3% by weight. When the content of the surfactant is less than 0.05% by weight, the permeability to recording paper cannot be sufficiently increased.
On the other hand, if the content is more than 10% by weight, the compound itself tends to precipitate at a low temperature, so that the reliability deteriorates.

Examples of the polyhydric alcohol alkyl ether used in the present invention include 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 and the like. Examples of the polyhydric alcohol aryl ether include ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether. The content of these water-soluble organic solvents in the ink is preferably 5 to 30% by weight, and more preferably 10 to 30% by weight. If added in an amount of 30% by weight or more, the viscosity of the water-based ink increases, which often affects the ejection stability. Examples of the water-soluble organic solvent used in combination with the above-mentioned water-soluble organic solvent for the purpose of preventing water evaporation of the ink include the following.

Ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,5-pentanediol, 1,6-hexanediol, glycerol,
Polyhydric alcohols such as 2,6-hexanetriol, 1,2,4-butanetriol, 1,2,3-butanthrol and petriol, N-methyl-2-pyrrolidone,
Nitrogen-containing heterocyclic compounds such as N-hydroxyethyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethylimidazolidinone, ε-caprolactam; amides such as formamide, N-methylformamide, N, N-dimethylformamide Amines such as monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine and triethylamine; sulfur-containing compounds such as dimethyl sulfoxide, sulfolane and thiodiethanol; propylene carbonate; ethylene carbonate;
Butyrolactone.

Next, specific examples of the dyes represented by formulas (III) to (V) are shown in Tables 3 to 5 in free acid form.

[0033]

[Table 3]

[0034]

[Table 4]

[0035]

[Table 5]

As the pH adjuster, any substance can be used as long as it can adjust the pH to a predetermined value without adversely affecting the ink to be prepared. Examples thereof include amines such as diethanolamine and triethanolamine, hydroxides of alkali metals such as lithium hydroxide, sodium hydroxide and potassium hydroxide, ammonium hydroxide, quaternary ammonium hydroxide, and quaternary phosphonium water. Oxides, carbonates of alkali metals such as lithium carbonate, sodium carbonate, potassium carbonate and the like can be mentioned.

The water-soluble dye used in the present invention includes:
In the color index, acid dyes, direct dyes, basic dyes, reactive dyes, dyes classified as food dyes,
Those having excellent water resistance and light resistance are used. These are added in such a range that the effect is not inhibited. Among them, acid dyes and direct dyes can be preferably used.

To the ink used in the ink set of the present invention, conventionally known additives can be added in addition to the coloring agent, surfactant, wetting agent, and pH adjusting agent. In addition, a water-soluble ultraviolet absorber and a water-soluble infrared absorber can be added according to the purpose.

[0039]

The present invention will be described below with reference to examples and comparative examples. Example 1 An ink composition having the following formulation was sufficiently stirred and dissolved at room temperature, and the pH of the aqueous ink was adjusted to 1 with lithium hydroxide.
After adjusting to 0.5, the mixture was filtered through a 0.22 μm Teflon filter, and further degassed for about 30 minutes to produce Ink 1. Ink 1 (yellow ink) Fast Yellow 2 1.5% by weight C.I. I. Direct Yellow 142 0.5% by weight Surfactant (Specific Example I-1) 1.0% by weight Diethylene glycol 15.0% by weight Glycerin 5.0% by weight 1,2-benzoisothiazolin-3-one (San-Ivac AP Sanai 0.5% by weight of ion exchange water

Ink 2 (Black Ink) Mixed Colorant (Specific Examples (III-1), (III-2)) 4.0% by weight Surfactant (Specific Example I-1) 1.0% by weight Diethylene glycol 15 Glycerin 5.0% by weight 1,2-Benzoisothiazolin-3-one (San-Ivac AP Sanai Sekiyu KK) 0.5% by weight Deionized water

The ink 2 (black ink) was added with 0.001% by weight of nickel ions, adjusted to pH 8.5, filtered through a 0.22 μm Teflon filter, and further added for 30 minutes. It was produced by performing a degree of degassing.

<< Evaluation of Image Quality >>
Nozzle diameter 30 μm using ZT for pressurizing the liquid chamber flow path, 6
Printing was performed on an ordinary marketed plain paper using an inkjet printer having a recording frequency of 12 kHz having a nozzle of 00 dpi, and the bleeding between the yellow and black was visually evaluated according to the following criteria. Boundary bleeding that cannot be visually discriminated at all: ○ Boundary bleeding is slightly visible but can be distinguished: △ Boundary bleeding that can be easily visually discriminated: ×

<< Evaluation of Storage >> Each of the above yellow ink and black ink was placed in a polyethylene container, and -20C,
It was stored for 3 months under the conditions of 20 ° C. and 70 ° C., respectively, and the presence or absence of precipitates and suspended matters after storage was confirmed. A case where no precipitate or the like was observed under any of the conditions was evaluated as “○”. The nickel ion content in the black ink was measured by ion chromatography. Table 2 shows the above results.

Example 2 An ink composition having the following formulation was sufficiently stirred and dissolved at room temperature, and the pH of the aqueous ink was adjusted to 1 with lithium hydroxide.
After adjusting to 0.5, the mixture was filtered through a 0.22 μm Teflon filter, and further degassed for about 30 minutes to produce Ink 3. Ink 3 (Yellow Ink) Fast Yellow 2 2.0% by weight Surfactant (Specific Example I-1) 1.0% by weight Diethylene glycol 15.0% by weight Glycerin 5.0% by weight 1,2-benzoisothiazoline-3- ON (Sun Eye Back AP, manufactured by Sanai Sekiyu KK) 0.5% by weight Ion exchange water

Ink 4 (Black Ink) Mixed Colorant (Specific Examples (III-1), (III-2)) 4.0% by weight Surfactant (Specific Example I-1) 1.0% by weight Diethylene glycol 15 Glycerin 5.0% by weight 1,2-Benzoisothiazolin-3-one (San-Ivac AP Sanai Sekiyu KK) 0.5% by weight Deionized water

To Ink 4 (black ink), 0.01% by weight of nickel ions was added, and after the addition, the pH was adjusted to 8.5 in the same manner as in Ink 2 and then 0.22 μm.
And then degassed for about 30 minutes to produce.

Comparative Example 1 Ink 5 (yellow ink) and Ink 6 (black ink) were prepared in the same manner as in Example 2 except that nickel ion was not added to ink 4 (black ink).

Comparative Example 2 In Example 1, the surfactant of ink 1 (yellow ink) and ink 2 (black ink) was BT7 (manufactured by Nikko Chemicals), and no nickel ions were added to the black ink. Except for the above, ink 7 (yellow ink) and ink 8 (black ink) were prepared in the same manner as in Example 1.

With respect to the ink sets prepared in Example 2 and Comparative Examples 1 and 2, image evaluation and storability evaluation were performed in the same manner as in the ink set of Example 1. Table 6 shows the results.

[0050]

[Table 6]

From Table 6, it can be seen that the use of the yellow ink and the black ink of the embodiment significantly reduces the occurrence of boundary bleeding.
It can be seen that if the amount of Ni ions is about 0.01% by weight, it becomes impossible to visually judge at all.

[0052]

As described above, the ink set for ink jet recording according to claim 1 is an ink set containing at least two colors of yellow and black inks.
Ni ions are contained in the black ink in an amount of 0.001% by weight or more. According to this ink set, blurring of the boundary between yellow and black on plain paper can be significantly suppressed.

The ink set according to claim 2 specifies the colorant of the yellow ink in the ink set, whereby the effect of preventing the above-described boundary bleeding can be more effectively exhibited, and the color tone can be improved. The ink set excellent in the present invention is provided.

In the ink set of the third and fourth aspects, the seed of the surfactant contained in the ink is specified.
According to this, the penetrating power of the ink in the vertical direction on the recording paper can be increased, and the bleeding of the boundary between the yellow ink and the black ink can be further prevented.

According to a fifth aspect of the present invention, there is provided an ink set for specifying the type of humectant to be contained in the ink. According to the humectant, an ink set for ink jet recording having high storage stability and high ejection reliability is provided. Can be provided.

The ink set of claim 6 specifies the dye of the black ink. According to these black dyes, it is possible to maintain the effect of the ink set and provide an ink set excellent in color tone. it can.

According to the ink set of the present invention, the pHs of the yellow ink and the black ink are defined, whereby the above-mentioned effects can be exhibited more effectively.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kiyofumi Nagai 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Masato Igarashi 1-3-6, Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Akiko Sakauchi 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Masayuki Kotani 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Inventor Hirotaka Mochizuki 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (reference) 2C056 FC01 2H086 BA55 BA59 BA60 4J039 BA29 BA38 BC12 BC13 BC14 BC15 BC19 BC27 BC29 BC33 BC35 BC41 BC42 BC54 BC56 BC65 BC66 BC73 BC77 BC79 BE22 EA17 EA19 EA34 EA38 EA42 EA44 EA47 GA24

Claims (7)

[Claims] 1. An ink jet recording ink set comprising at least two color inks of yellow and black containing a colorant, a wetting agent and a surfactant which are dispersed or dissolved in water. Contains 0.001% by weight or more of Ni ions. 2. The ink set for ink jet recording according to claim 1, wherein the yellow ink in the ink set is Pro-jet Fast Yellow as a colorant.
w2 (manufactured by ZENECA), which is an ink set for inkjet recording. 3. The ink set for ink jet recording according to claim 1, wherein the surfactant contained in the ink in the ink set is a polyoxyethylene alkyl ether acetate represented by the following general formula (I), or An ink set for inkjet recording, which is a dialkyl sulfosuccinate represented by the general formula (II). Embedded image Embedded image 4. The ink set for ink jet recording according to claim 1, wherein the surfactant contained in the ink in the ink set is a nonionic surfactant. 5. The ink set for ink jet recording according to claim 1, wherein the wetting agent contained in the ink in the ink set is a polyhydric alcohol alkyl ether and / or a polyhydric alcohol aryl ether. Ink set for inkjet recording. 6. The ink set for inkjet recording according to claim 1, wherein the colorant of the black ink is represented by the following general formula (III), general formula (IV) or general formula (IV):
At least one selected from the group of compounds represented by (V)
An ink set for inkjet recording, wherein the ink set is a seed. Embedded image Embedded image Embedded image 7. The ink set for inkjet recording according to claim 1, wherein the pH of the black ink is 7 or more and 10 or less, and the pH of the yellow ink is
Is 8 or more and 11 or less.