JPH1088043A - Ink composition for ink-jet use - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink for ink-jet use having a decreased drying time and showing no color bleeding, by incorporating in the ink a dye, a water- insoluble organic compound having a high boiling point and an amphiphilic agent together with water. SOLUTION: This ink composition comprises (A) 0.1 to 10wt.% at least one dye, (B) 1 to 70wt.% at least one water-insoluble organic compound selected from the group consisting of a water-insoluble mono- or polyglycol ether, a water-insoluble N-substituted 2-pyrrolidone, a water-insoluble mono- or polyglycol ester and a water-insoluble hydrocarbon, (C) at least one amphiphilic agent, preferably hydrotropic amphiphilic agent, in an amount sufficient to render component (B) soluble in water, and (D) water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to ink compositions for use in ink-jet printing, and more particularly to ink-jet ink compositions that produce a bleed-free (bleed-free) print with reduced drying time. Things.

[0002]

BACKGROUND OF THE INVENTION Ink jet printing is a non-impact printing process in which ink droplets are deposited on print media, such as paper, transparent film or fabric, in response to an electrical signal. Things. In thermal ink jet printing, ink is supplied to a resistor element in a chamber via a plenum (ink reservoir) connected to an ink container. The plurality of resistor elements are arranged in a specific pattern on the print head of the ink jet printing cartridge. Each resistor element is connected to a nozzle of the nozzle plate. In operation, each resistor element is connected to a microprocessor and its signal is one.
An instruction is given to immediately heat the above resistor elements. The heat creates vapor bubbles in the chamber that eject ink through a connecting nozzle onto the print media.
By energizing multiple resistor elements in a particular order,
Alphanumeric, fill (area fill) and other patterns are formed on the print media. In piezoelectric ink-jet printing, ink droplets are ejected by the vibrations of a piezoelectric crystal, also in response to electrical signals emitted by a microprocessor.

[0003] Ink jet printers provide low cost, high quality printing with relatively noise-free operation. As described above, the ink jet printer is a general-purpose alternative printer compared with other printers used in combination with the computer, for example, a relatively expensive laser printer or the like. However, at present, most inkjet printers can be obtained with laser printers due to the relatively slow drying time of the ink jet ink and the slowdown of the printer drive due to printer-specific bleed control algorithms. It is not possible to match the required throughput levels. In particular, with regard to bleed control, when performing color printing on a paper substrate, there is a tendency for ink-jet inks to bleed into each other's colors. Bleed occurs when colors mix on or within the paper substrate surface. In response to this problem, ink jet printers typically employ a bleed suppression algorithm to provide a boundary between colors so as to be clean and free from intrusion into other colors. However, this will slow down the printer. In order to increase the throughput levels obtained with ink jet printers, the drying time of the ink jet ink must be improved, preferably to achieve bleed control as well.

[0004] Various solutions have been provided for improving the drying time of ink-jet inks. Some solutions include changing the ink environment to speed up the drying time. For example, heated platens and other heat sources are used to achieve faster drying times. However, heated platens add to the cost of the printer and are generally not cost effective.

Another solution is to add various components to the composition of the ink-jet ink to achieve fast drying times. For example, a surfactant is added to the composition of the dye-containing inkjet ink to improve the drying time by increasing the penetration rate of the ink into the paper. See, for example, U.S. Pat. No. 5,106,416 ("Bleed Alleviation Using Zwitterionic Surfactan").
ts and Cationic Dyes "), US Patent No. 5,116,4
09 (“Bleed Alleviation in Ink-Jet Inks”),
U.S. Pat. No. 5,133,803 ("High Molecular W
eight Colloids Which Control Bleed ”). Notably, bleed control is achieved with the addition of a surfactant. Increasing the penetration rate of the ink shortens its drying time, but the undesirable decrease in edge sharpness may also be derived from the addition of surfactant. Further, it is known that the addition of a surfactant to an ink jet ink has a negative effect on the droplet ejection characteristics. More specifically, since the surface tension of the surfactant-containing ink is low, a liquid pool may be formed on the nozzle plate of the print head, resulting in deterioration of the droplet ejection characteristics. Short-chain alcohols have also been added to ink-jet ink compositions to speed up drying times, but depending on the particular print media, the addition of short-chain alcohols can adversely affect print quality due to increased edge roughness. May be exerted. Thus, the improvement in drying time achieved with surfactants and short chain alcohols is often
It is achieved at the expense of print quality.

Accordingly, there is a need for an ink-jet ink composition that dries quickly after impact with a print medium and exhibits low bleed.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the problem of long drying time and color bleeding after the aqueous ink composition has adhered to the print medium.

[0008]

According to the present invention, the drying time of an ink-jet ink composition which is printed on a printing medium such as paper, a transparent film or a woven fabric using an ink-jet printer is controlled by an amphiphilic agent. It is shortened by using a high boiling water-insoluble organic compound that dissolves in water. More specifically, the inks of the present invention comprise (a) at least one dye; (b) at least one high boiling water-insoluble organic compound; (c) at least one amphiphile; and (d) Contains water. As used herein, a "high boiling organic compound" is an organic compound whose vapor pressure is sufficiently low compared to the vapor pressure of water such that only water evaporates from the ink during normal operation of ink jet printing. Shall be referred to. Notably, such compounds act both as solvents and co-solvents.

[0009] Ink jet inks prepared in accordance with the present invention exhibit fast drying times and bleed control, while the edge sharpness achieved can be controlled by the choice of amphiphile. In particular, excellent print quality providing good edge sharpness is achieved by using hydrotropes (solubilisers) in addition to fast drying times and bleed control. Hydrotropes are a subset of the general class of amphiphiles, in which the resulting isotropic solution occupies a relatively large area in the phase diagram and is compared to solutions obtained with surfactants. It is characterized by its ability to solubilize water-insoluble organic compounds so as to have a very high surface tension. Typically, better print quality is desired for printing on paper media so that hydrotropes can be preferentially used to solubilize water-insoluble organic compounds. On the other hand, relatively poor print quality may also be acceptable in some applications, for example, for printing on textile media so that water-insoluble organic compounds can be solubilized using surfactants.

Notably, since current ink vehicles contain both water-insoluble compounds and water, either water-soluble or water-insoluble dyes may be used in the practice of this invention, Water-insoluble dyes may be preferred due to the inherent properties of (waterfastness).

The ink of the present invention has a continuous piezoelectric drop.
It may be used in various ink jet printers, such as on-demand printers and thermal or bubble jet drop-on-demand printers. The reduced drying time and reduced bleed by the printer achieved in the practice of the present invention can increase the throughput of the inkjet printer, while at the same time reducing bleed and maintaining good edge sharpness contributes to high print quality. Will be.

[0012]

In the practice of the present invention, the drying time indicated by the ink composition for ink-jet printing, once printed on a printing medium such as paper, transparent film or fabric by an ink-jet printer, is converted into an aqueous solution by an amphiphilic agent. It is reduced by providing a soluble, high boiling, water-insoluble organic compound. More specifically, the inks of the present invention comprise (a) at least one dye, (b) at least one high boiling water insoluble organic compound, (c) at least one amphipathic agent, and (d) Contains water. The amphipathic agent is present in an amount that renders the organic compound completely soluble, resulting in a clean, stable ink solution.

All concentrations herein are expressed in weight percent, unless otherwise indicated. The purity of all components is
It is one used for ordinary commercial use as an ink-jet ink.

Dyes that may be used in the practice of the present invention include both water-soluble and water-insoluble dyes. Any water-soluble or water-insoluble dye compatible with ink jet printing may be suitably used in the practice of the present invention.
Examples of water-soluble dyes that may be suitably used in the practice of the present invention include, but are not limited to, CI Acid Blue
9, CI Acid Red 18, CI Acid Red 27, CI Aci
d Red 52, CI AcidYellow, CI Direct Blue 199
And their monovalent alkaline earth ions such as Na ⁺ , Li ⁺ , Cs ⁺ , NH ₄ ⁺ and substituted ammonium salts. Examples of water-insoluble dyes that may be suitably used in the practice of the present invention include, but are not limited to, Isol Yellow,
d, Isol Orange, Isol Black and Solvent Blue B, all of which are available from Crompton & Knowles (Charlotte,
North Carolina). Dye (dye group)
Is present at about 0.1 to 10 wt% of the ink composition.

[0015] Water-insoluble organic compounds serve several purposes in the practice of the present invention. First, it acts as a co-solvent required for use with ink-jet pens. More specifically, when the pen of an inkjet printer is exposed to the atmosphere without being used, the water in the ink vehicle evaporates.
When the high boiling compound is present in the ink vehicle, crust formation and nozzle blockage can be prevented. Therefore, the vapor pressure of the organic compound must be sufficiently low compared to water that does not evaporate during ink jet printing. Second, the organic component is the primary solvent (prime) when a water-insoluble dye is selected for the practice of the present invention.
ary solvent).

Examples of organic compounds or oils that may be used include, but are not limited to, water-insoluble mono- or polyglycol ethers; water-insoluble N-substituted 2-pyrrolidone; mono- or polyglycol esters; There is hydrogen. Generally, any water-insoluble organic compound or combination thereof that is capable of dissolving the selected dye and solubilizing by the amphiphile may be used in the practice of the present invention.
The water-insoluble organic compound may be a liquid or a solid at room temperature. Specific examples of the water-insoluble organic compound suitably used in the present invention include, but are not limited to, monoethylene and polyethylene glycol phenyl ether; monopropylene and polypropylene glycol phenyl ether; and ethylene such as acrylate. , Propylene, polyethylene and polypropylene
Glycol esters are included. The water-insoluble organic compound may be in a concentration range of about 1-70 wt% of the inkjet ink.

The amphiphilic agent used in the practice of the present invention comprises
It may be any amphipathic agent or combination thereof that is compatible with the remaining components of the ink-jet ink and is capable of "solubilizing" the high boiling water-insoluble organic compound in water. Amphiphiles render water-insoluble organic compounds in water into very small droplets and make them soluble by maintaining them in a stable dispersion, ie, a microemulsion. Examples of common non-hydrotrope amphiphilic surfactants include alkyl sulfonates, benzene sulfonates, alkyl-substituted benzene sulfonates, naphthalene sulfonates, alkylamine oxides, substituted ammonium salts and nonionics ( non-ionics).

Preferably, the amphiphilic agent used in the present invention is one that is included in one class of amphiphilic agents known as "hydrtropes". The hydrotropic amphiphile has a function of making the water-insoluble organic compound in the ink composition soluble, like a general amphiphilic agent and a surfactant. However, hydrotrope amphiphiles do not have the sharp drop in surface tension associated with the use of other surfactants, and have a lower surface tension for inks using hydrotrope amphiphiles in the practice of the present invention. The decline is relatively suppressed. The use of hydrotrope amphiphiles is not always possible, as the relatively low surface tension associated with surfactant-containing inks is sometimes found to negatively impact drop ejection properties and print quality as described above. It is informative. Hydrotrope amphiphiles have a relatively fast drying time and improved bleed without occasional puddles or loss of edge sharpness on the nozzle plate that plagues surfactant-containing inks Provide ink. However, where edge sharpness is not important, such as in textile printing, a non-hydrotrope amphiphile may be used. Hydrotrope amphiphiles are generally desired where edge sharpness is important, such as prints on paper.

The hydrotrope amphiphiles may be anionic, cationic or non-ionic in nature. Examples of anionic hydrotrope amphiphiles suitably used in the practice of the present invention include, but are not limited to, sodium benzoate, sodium salicylate, sodium benzene sulfonate, sodium benzene sulfonate, sodium benzene disulfonate, sulfone sulfone. There are sodium citrate toluene, sodium xylene sulfonate, sodium cumene sulfonate, cimen sodium sulfonate and sodium cinnamate. Examples of cationic hydrotrope amphiphiles suitably used in the practice of the present invention include, but are not limited to,
There are p-aminobenzoic acid hydrochloride, procaine hydrochloride and caffeine. Examples of nonionic hydrotrope amphiphiles suitably used in the practice of the present invention include, but are not limited to, resorcinol and pyrogallol.

Optionally, a co-surfactant may be added to current ink-jet ink compositions. The cosurfactant preferably includes medium chain alcohols having 3 to 8 carbon atoms, such as isopropanol and pentanol. The cosurfactant may correspond to less than 10 wt% of the ink composition,
It acts as an individual component of the amphiphile or as a partial replacement thereof.

Consistent with the requirements for the present invention, various types of additives may be used in the ink to optimize the properties of the ink composition for a particular application. For example, as is well known to those skilled in the art, pesticides may be used in the ink composition to inhibit microbial growth, and may also include sequestering agents such as EDTA to reduce the toxic effects of heavy metal impurities. The pH of the ink may be controlled by using a buffer solution. Viscous modifiers and other known additives such as acrylic or non-acrylic polymers may be added to modify various properties of the ink composition as desired.

The ink composition of the present invention can be prepared by two different methods, namely, the omission method and another synthesis method. To prepare the inks of the present invention according to the abbreviation method, one or more organic insoluble components and water must first be combined in a ratio that reflects the final required composition of the ink. The resulting two-phase liquid is then titrated with the selected amphiphile until a clear solution is obtained, which means solubilizing the organic compound to reach a single-phase solution. An about 1% excess of amphiphile may optionally be added to ensure a stable solution. To this single phase solution, add the selected dye and any desired additives,
Complete the preparation of the basic ink composition. It should be noted that once the appropriate relevant concentration of one or more organic components and water and one or more amphiphiles has been determined through the titration process described above, the subsequent ink composition is then determined. They may be mixed in any order.

If one chooses another synthetic approach to preparing the inks of the present invention, the first step involves a phase diagram representing the combination of the water-insoluble organic compound and water. More specifically, the phase diagram combines water and one or more high boiling water insoluble organic compounds in various ratios and combines each mixture in the phase diagram until a clear single phase region is defined in the phase diagram. Or by titrating against a plurality of amphiphilic agents. Further titrations beyond the clearing point (clear point) define other multi-phase or semi-solid regions. These results, when plotted on a conventional triangular plot, represent a ternary phase diagram. For example, the only drawing illustrates the foregoing ternary phase diagram for an inkjet ink composition comprising propylene glycol phenyl ether, sodium xylene sulfonate, and water, as described in more detail in the Examples below. Where part A represents a milky region with two phases and part B
Represents a single-phase isotropic region, and part C represents a semi-solid region. The single-phase isotropic region (part B), which is more suitable for use in ink-jet ink compositions,
1 shows the composition of one or more organic compounds, water and one or more amphiphiles. Therefore, in the practice of the present invention,
Any composition may be selected from this single phase region, provided that the composition complies with any other criteria for a particular inkjet ink composition.

It should be noted that the composition in part A can be used for applications that do not require long shelf life, such as textile printing. Similarly, using a thermal printhead allows the composition in part C to be used.

The inks prepared according to the invention exhibit the expected fast drying times and bleed control for inks containing a surfactant component, and moreover, especially when hydrotrope amphiphiles are used. It will not exhibit the print quality degradation generally associated with it.
The following examples demonstrate the rate at which ink jet ink compositions made according to the invention dry when printed on an ink jet printer.

In accordance with the present invention, two types of ink compositions were prepared as follows. Example 1 Using the vehicle component concentration determined from the phase diagram shown in FIG.
An ink-jet ink composition comprising a low dye, 25 wt% of propylene glycol phenyl ether, 15 wt% of sodium xylene sulfonate and the balance water was prepared. More specifically, the phase diagram shown combines the propylene glycol phenyl ether and water in various ratios and then titrates each mixture against sodium xylene sulfonate until a clear single phase region is defined. And plotted. Thus, part A of the figure represents various combinations of propylene glycol phenyl ether, sodium xylene sulfonate, and water, resulting in two phases that have a milky appearance. Part B of the figure represents various combinations of propylene glycol phenyl ether, sodium xylene sulfonate, and water, resulting in a transparent single phase region. Part C of the figure was defined by further titrating the mixture of propylene glycol phenyl ether and water with sodium xylene sulfonate beyond the clearing point until a semi-solid region was defined. Portion B, which is a single-phase isotropic region in the figure, shows a combination of propylene glycol phenyl ether, sodium xylene sulfonate, and water, which may be appropriately used in the practice of the invention. Part A
And C represent ink vehicles outside the scope of the present invention.

The ink-jet ink composition of this embodiment belongs to the single-phase isotropic region of the portion B in the drawing. More specifically, the vehicle of the ink composition is
26% by weight of propylene glycol phenyl ether, 15% by weight of sodium xylene sulfonate,
It contained 9 wt% water, resulting in a slightly modified concentration to represent the percentage of ink vehicle rather than the total ink composition. Point D on the diagram indicates that the ink composition mediator of this example actually falls within the range of portion B, which is a transparent single phase region of the ternary phase diagram.

Using a 45 picoliter drop volume pen,
The ink-jet ink composition of this example was printed on plain paper. The ink dried instantaneously after colliding with plain paper. As a comparison, an ink-jet ink composition having a water-soluble co-solvent (eg, US Pat.
No. 3,189) has been found to exhibit a finite, easily measurable drying time when printed on plain paper.

Example 2: Using a concentration determined by a similar procedure as in Example 1 in which the vehicle is a single-phase liquid, 3% by weight of Isol Yellow dye, 25% by weight of propylene glycol phenyl ether, An ink-jet ink composition comprising 11 wt% sodium xylene sulfonate and the balance water was produced. The ink-jet ink composition was then printed on plain paper using a 45 picoliter drop volume pen. The ink dried instantly after colliding with plain paper.

As described above, it has been proved that the ink-jet ink composition produced according to the present invention has a short drying time when printed by an ink-jet printer.

The ink-jet ink compositions according to the present invention and methods of doing the same as disclosed herein are expected to find commercial use in black and color printing.

Thus, an ink composition has been disclosed that may be used to achieve fast drying times and bleed control without sacrificing print quality. Various changes and modifications of the obvious characteristics may be made without departing from the spirit of the invention, and all such changes and modifications are intended to be within the scope of the invention as defined in the appended claims. What is conceivable is obvious to a person skilled in the art.

The embodiments of the present invention have been described in detail above. Each embodiment of the present invention will be listed below. (1) At least one dye, at least one water-insoluble organic compound, at least one amphiphilic agent, and water, wherein the amphiphilic agent solubilizes at least one water-insoluble organic compound in water. Aqueous inkjet ink compositions exhibiting improved drying time and reduced bleed by including an amount sufficient to (2) at least one dye is about 0.1 to 10 wt%
(1) The ink composition for inkjet according to the above (1), wherein (3) The at least one water-insoluble organic compound is selected from water-insoluble monoglycol ether, water-insoluble polyglycol ether, water-insoluble N-substituted 2-pyrrolidone, water-insoluble monoglycol ester, water-insoluble polyglycol ester, and water-insoluble hydrocarbon. The ink composition for inkjet according to the above item (1), which is selected from the group consisting of: (4) The inkjet ink composition according to the above (1), wherein the at least one water-insoluble organic compound is in an amount ranging from about 1 to 70 wt%. (5) The inkjet ink composition according to the above (1), wherein the at least one amphiphilic agent is a hydrotropic amphiphilic agent. (6) The at least one water-insoluble organic compound is selected from the group consisting of propylene glycol phenyl ether and ethylene glycol phenyl ether, and the at least one amphiphilic agent is sodium xylene sulfonate. The ink composition for inkjet according to the above (1). (7) The inkjet ink composition according to (1), further having a carbon chain length of 3 to 8 carbon atoms,
An ink-jet ink composition comprising a cosurfactant comprising an alcohol having a concentration within the range of 0 to about 10% by weight of the ink composition. (8) a step of preparing the ink composition according to the above (1), and a step of printing the ink composition on a print medium using an ink-jet pen; A method for reducing the drying time of an ink used in ink jet printing, characterized by drying.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the relationship between the contents of the ink composition components of the present invention.

Claims (8)

[Claims] 1. The method of claim 1, wherein the at least one water-insoluble organic compound comprises at least one water-insoluble organic compound, at least one water-insoluble organic compound, at least one water-insoluble organic compound, and at least one water-insoluble organic compound. An ink-jet ink composition in an amount sufficient to solubilize the ink. 2. The ink-jet ink composition according to claim 1, wherein said at least one dye is in an amount ranging from about 0.1 to 10 wt%. 3. The at least one water-insoluble organic compound is a water-insoluble monoglycol ether, a water-insoluble polyglycol ether, a water-insoluble N-substituted 2-pyrrolidone,
The ink composition according to claim 1, wherein the ink composition is selected from the group consisting of a water-insoluble monoglycol ester, a water-insoluble polyglycol ester, and a water-insoluble hydrocarbon. 4. The ink-jet ink composition according to claim 1, wherein said at least one water-insoluble organic compound is in an amount ranging from about 1 to 70 wt%. 5. The ink composition according to claim 1, wherein the at least one amphiphilic agent is a hydrotropic amphiphilic agent. 6. The at least one water-insoluble organic compound is selected from the group consisting of propylene glycol phenyl ether and ethylene glycol phenyl ether, and the at least one amphiphilic agent is sodium xylene sulfonate. The ink composition for inkjet according to claim 1, wherein: 7. The ink-jet ink composition of claim 1, further having a carbon chain length of from 3 to 8 carbon atoms, and having a carbon chain length of from 0 to about 10 wt% of the ink composition. An ink-jet ink composition comprising a cosurfactant comprising an alcohol having a concentration. 8. The method according to claim 1, further comprising the steps of: preparing the ink composition according to claim 1; and printing the ink composition on a print medium using an ink-jet pen, wherein the ink composition comprises the print medium. A method for reducing the drying time of ink used in ink-jet printing, wherein the ink is dried instantly after colliding with the ink.