JPH10316915A - Ink for ink jet printer and ink jet printer equipped with this ink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ink which has good penetrability and does not cause curling because of its ability to equally elongate the printed surface and the fibers of a non-fibrous surface by specifying the wetting time and the absorption coefficient for a recording medium as measured by the Bristow method. SOLUTION: At least one organic solvent selected among polyhydric alcohols, polyhydric alcohol alkyl ethers, nitrogenous heterocyclic compounds, amines, sulfur-containing compounds, propylene glycol, etc., is mixed with a colorant selected among acid dyes, direct dyes, basic dyes, reactive dyes and food colors, a pigment dispersant comprising a hydrophilic polymer, water, a pH modifier, a chelating reagent and optionally a water-soluble ultraviolet absorber, a water- soluble infrared absorber, etc., to obtain an ink having a wetting time of 30 ms or below onto a recording medium irrespectively of a dye concentration when measured by the Bristow method and an absorption coefficient of 2 ml/ m<2> .ms<1/2> or above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ink for an ink jet printer and an ink jet printer.

[0002]

2. Description of the Related Art In recent years, ink jet printers have become low noise,
Due to the low running cost and certain advantages, it has rapidly spread, and printers that can print not only on paper dedicated to inkjet printers but also on copy paper used in ordinary offices (for example, electrophotographic copier paper) have been introduced to the market. ing.
Also, so-called co-papers having both electrophotographic copier suitability and ink jet printer suitability have been released from various companies. However, if the ink amount becomes extremely large due to almost solid printing or the like, a problem such as curling (curling of paper) occurs in these copy papers or co-papers. To improve this problem, see, for example,
In 413, a scratch or a hole is formed on the back side of the base paper of the recording material. However, in this method, the paper strength is weakened, and a problem such as tearing due to a slight occurrence occurs. Also, for example, see JP-A-7-2
In 05543, the expandable particles in the paper are expanded,
The manufacturing method must be complicated.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet printer ink that does not cause curl and an ink jet printer equipped with the ink.

[0004]

According to the present invention, the mechanism by which curling occurs in an ink-jet printer is described as follows.
In view of (3), it was possible to provide an ink jet printer ink free from curling and an ink jet printer equipped with the ink. (1) By printing, the fibers only on the printing surface absorb ink drops and extend. (2) At the time of printing, since the paper is fixed with a platen, etc.,
Cockling occurs but the paper is not curled as a whole. (3) If the paper is ejected and is no longer fixed after printing, the fibers on the printing surface alone dry and shrink over time, so that the printing surface is concave and curls. That is, the ink for an inkjet printer of the present invention has a wetting time of 30 minutes on a recording medium in the Bristow method.
ms and an absorption coefficient of 2 ml / m ² · ms ^1/2 or more, and has high permeability to a printing target. The ink for an ink jet printer of the present invention has good ink permeability, and the fibers on the printed surface and the non-printed surface are evenly stretched, so that curling can be prevented.

The Bristow method employed in the present invention will be described below. The permeability measuring device shown in FIG. 2 was used. The ink reservoir 2 is brought into contact with the paper moving at a constant speed, and the ink 3 is absorbed into the paper surface through the slit 1,
The contact time t and the transfer amount V of the ink 3 are obtained from the following equation. Contact time t (ms) = slit width d (mm) x 1000
/ Paper moving speed S (mm / sec) transfer amount V (ml / m ² ) = ink amount Q (μl) × 100
0 / [length L (mm) of transition trace left by liquid × length W (mm) of slit] ^Plotted against t ^1/2 and absorption curve of ink to paper as shown in FIG. Can be obtained. The time during which the graph is parallel to the horizontal axis is called the wetting time, and the slope thereafter is called the absorption coefficient. This time, slit width 1 (mm), slit length 17.5 (mm), ink amount 40 (μl), paper moving speed 1.25, 2.5, 5, 12.5, 25, 5
The experiment was performed at 0 (mm / sec).

[0006] In the ink of the present invention, a surfactant can be used for the purpose of improving the wettability and permeability of the ink. Further, the following organic solvents can be used for the purpose of preventing drying of the ink and improving the dissolution stability. Ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,5-pentanediol, 1,6-hexanediol, glycerol, 1,2,6-hexanetrio
Polyhydric alcohols such as 1,2,4-butanetriol, 1,2,3-butanetriol and triol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, Polyhydric alcohol alkyl ethers such as 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-dimethylimidazolidinone, ε
Nitrogen-containing heterocyclic compounds such as caprolactam; amides such as formamide, N-methylformamide, N, N-dimethylformamide; amines such as monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine, triethylamine;
Sulfur-containing compounds such as dimethyl sulfoxide, sulfolane, and thiodiethanol; propylene carbonate; ethylene carbonate; and γ-butyrolactone. These solvents can be used alone or in combination of two or more.

As a coloring material of the ink of the present invention, a dye classified into an acid dye, a direct dye, a basic dye, a reactive dye and an edible dye in a color index and having excellent water resistance and light resistance is used. . Specific examples of these dyes include C.I. I. Acid. Yellow 17,23,42,44,
79, 142 C.I. I. Acid. Red 1, 8, 13, 14, 18,
26, 27, 35, 37, 42, 52, 82, 87, 8
9, 92, 97, 106, 111, 114, 115, 1
34,186,249,254,289 C.I. I. Acid. Blue 9, 29, 45, 92, 24
9 C. I. Acid. Black 1, 2, 7, 24, 26,
94 C.I. I. hood. Yellow 3,4 C.I. I. hood. Red 7, 9, 14 C.I. I. hood. Black 1,2

As a direct dye, C.I. I. direct. Yellow 1,12,24,26,
33, 44, 50, 86, 120, 132, 142, 1
44 C.I. I. direct. Red 1,4,9,13,17,
20, 28, 31, 39, 80, 81, 83, 89, 2
25,227 C.I. I. direct. Orange 26,29,62,10
2 C. I. direct. Blue 1, 2, 6, 15, 22,
25, 71, 76, 79, 86, 87, 90, 98, 1
63, 165, 199, 202 C.I. I. direct. Black 19,22,32,3
6,51,56,71,74,75,77,154,1
68,171

As basic dyes, C.I. I. Basic. Yellow 1,2,11,13,1
4,15,19,21,23,24,25,28,2
9, 32, 36, 40, 41, 45, 49, 51, 5
3,63,64,65,67,70,73,77,8
7, 91, C.I. I. Basic. Red 2,12,13,14,1
5,18,22,23,24,27,29,35,3
6,38,39,46,49,51,52,54,5
9, 68, 69, 70, 73, 78, 82, 102, 1
04, 109, 112 C.I. I. Basic. Blue 1,3,5,7,9,2
1,22,26,35,41,45,47,54,6
2,65,66,67,69,75,77,78,8
9, 92, 93, 105, 117, 120, 122, 1
24, 129, 137, 141, 147, 155 C.I. I. Basic. Black 2,8

As reactive dyes, C.I. I. Reactive. Black 3,4,7,11,1
2,17 C.I. I. Reactive. Yellow 1,5,11,13,
14, 20, 21, 22, 25, 40, 47, 51, 5
5, 65, 67 C.I. I. Reactive. Red 1,14,17,25,
26, 32, 37, 44, 46, 55, 60, 66, 7
4,79,96,97 C.I. I reactive. Blue 1, 2, 7, 14, 15,
23, 32, 35, 38, 41, 63, 80, 95, etc. can be used. Particularly, acid dyes and direct dyes can be preferably used. Dyes newly developed for ink jet can of course also be used. For example, Projet Fast B marketed by Zeneca
luck2, Project Fast Magenta
2, Projet Fast Yellow2, Pro
jet Fast Cyan2 (registered trade name).

As the pigment, azo-based, phthalocyanine-based, anthraquinone-based, quinacridone-based, and organic pigments can be used.
Dioxazine type, indigo type, thioindigo type, perylene type, isoindolenone type, aniline black, azomethine type, rhodamine B lake pigment, carbon black, etc., and as inorganic pigments, iron oxide, titanium oxide, calcium carbonate, barium sulfate , Aluminum hydroxide, barium yellow, navy blue, cadmium red, chrome yellow, and metal powder.

As a pigment dispersant, as a hydrophilic polymer,
In the natural system, gum arabic, tragan gum, guar gum, karaya gum, locust bean gum, arabinogalactone, pectin, plant macromolecules such as quince seed starch, alginic acid, carrageenan, algae macromolecules such as agar, gelatin, casein, Animal polymers such as albumin and collagen; microbial polymers such as xanthene gum and dextran; sodium,
Starch-based polymers such as sodium starch phosphate, seaweed-based polymers such as sodium alginate and propylene glycol alginate, and pure synthetic systems include vinyl-based polymers such as polyvinyl alcohol, polyvinylpyrrolidone, and polyvinyl methyl ether. , 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 resin, polyvinyl pyrrolidone, polyvinyl alcohol, β An alkali metal salt of a naphthalenesulfonic acid formalin condensate, a polymer compound having a salt of a cationic functional group such as a quaternary ammonium or an amino group in a side chain, and a natural polymer compound such as shellac. .

The ink of the present invention may contain conventionally known additives in addition to water, the above-mentioned solvent, surfactant and colorant. Any substance can be used as the pH adjuster as long as it can adjust the pH to 7 or more without adversely affecting the ink to be prepared. Examples thereof include amines such as diethanolamine and triethanolamine, hydroxides of alkali metal elements such as lithium hydroxide, sodium hydroxide and potassium hydroxide, ammonium hydroxide, quaternary ammonium hydroxide, and quaternary phosphonium. Examples include hydroxides, carbonates of alkali metals such as lithium carbonate, sodium carbonate, and potassium carbonate.

Examples of the chelating reagent include sodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate and sodium uramil diacetate. As a rust inhibitor, for example,
Acid sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite,
Examples include pentaerythritol tetranitrate and dicyclohexylammonium nitrite. In addition, a water-soluble ultraviolet absorber and a water-soluble infrared absorber can be added according to the purpose.

An embodiment of the present invention will be described below. Table 1 shows the formulation of the ink used, the wetting time and the absorption coefficient. All the inks were stirred and dissolved at 60 ° C., allowed to cool at room temperature, and adjusted with a 10% aqueous solution of lithium hydroxide so that the pH became 8.5, and this was filtered with an effective filtration area of 4 cm ² and a filtration pore diameter of 0.2 μm.
m to give a filter. The wetting time and absorption coefficient are those for My Paper (NBS Ricoh). FIG. 1 shows a printing pattern.
With the above-mentioned ink, my paper was fed sideways to perform solid printing as shown in FIG. Table 2 shows the evaluation of the curl of the sheet after 3 minutes when left in an environment of 20 ° C. and 65% after printing. However, the present invention is not limited to these examples and schematic diagrams.

[0016]

[Table 1]

[0017]

[Table 2]

[0018]

[Table 3]

[0019]

[Table 4]

[0020]

[Table 5]

[0021]

[Table 6]

[0022]

[Table 7]

[0023]

[Table 8]

[0024]

[Table 9]

[0025]

[Table 10]

[0026]

[Table 11]

[0027]

[Table 12] In the curl, ○ means that the curl at the front both ends of the paper when left on a horizontal surface is less than 15 ° on average. In the curl, △ means that the curl at the front both ends of the paper when left on a horizontal plane averages 15 ° or more and less than 30 °. In the curl, x means that the curl at the front ends of the paper when left on a horizontal surface is 30 ° or more on average.

[0028]

The present invention provides an ink for an ink jet printer and an ink jet printer which do not cause curling.

[Brief description of the drawings]

FIG. 1 is a diagram showing a solid printing pattern.

FIG. 2 is a diagram showing a permeability measuring apparatus by the Bristow method.

FIG. 3 is a diagram showing the surface state of paper after measurement by the Bristow method.

FIG. 4 is a diagram illustrating an absorption curve of ink onto paper.

[Explanation of symbols]

 Reference Signs List 1 slit 2 ink reservoir 3 ink 4 paper 5 rotating wheel

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Akiko Konishi 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Hirotaka Mochizuki 1-3-6 Nakamagome, Ota-ku, Tokyo Share Inside Ricoh Company (72) Inventor Masayuki Kotani 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company (72) Inventor Takanori Tsukiki 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company (72) Inventor Ikuko Tanaka 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (3)

[Claims] 1. The wetting time of a recording medium in the Bristow method is 30 ms or less, and the absorption coefficient is 2 ml / m ² ···
ms ^1/2 or more. 2. An ink jet printer in which a plurality of inks of a high dye density ink and a low dye density ink are mounted as at least one ink of the same system color tone, each of the inks has a wetting time on a recording medium in the Bristow method. An ink jet printer characterized by having an absorption coefficient of not more than 30 ms and an absorption coefficient of not less than 2 ml / m ² · ms ^1/2 irrespective of the dye concentration. 3. The ink-jet printer according to claim ² , wherein the amount of ink deposited on the recording medium per ink drop is 5 g / m ² or more.