JP2619682B2 - Aqueous recording ink - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention is an aqueous recording ink which is most suitable for ink jet recording, writing implement, recorder, stamp, etc.
Especially for ink jet recording, there is no clogging at the nozzle, there is ejection stability, and it is also excellent in quick drying after recording,
The present invention also relates to a water-based recording ink having excellent print quality with less bleed-through.

(Prior art) Recording by the ink jet recording method has low noise, is easy to perform high-speed recording and is easy to colorize, and has the possibility that plain paper can be used. Application and development are being actively carried out.

As the ink jet recording service, various characteristic recording methods have been proposed by various combinations of the ink droplet control method and the discharge method, and the inks using these inks are also oily and water-based. A dye containing a water-soluble dye, a water-soluble organic solvent and water as essential components is used.

(Problems to be Solved by the Invention) However, in the above-mentioned ink jet recording system, the ink must be continuously and stably ejected as uniform droplets from a fine nozzle orifice. Problems to be solved include a problem of ejection stability, and a problem of clogging of a nozzle.

Problems to be solved after recording of the aqueous recording ink include problems such as dryness, show-through, and bleeding.

However, all of these problems are related, and a method that can solve all of them has not been found yet.

On the other hand, when plain paper is used as the recording paper in the ink jet recording method, since the surface tension is high with ordinary aqueous recording ink, the penetration is extremely slow due to a sizing agent on the surface of the paper, and even when printing, Because it does not dry, plain paper is not used as recording paper, but paper with a specially coated surface has been used.

As a method of printing on plain paper, there has been proposed a method of increasing the alkalinity of the ink and dissolving the sizing agent to increase the apparent drying speed. In this case, there is no problem such as show-through, bleeding, etc. Has a pH of 13 or more, which has a problem in safety to the human body, and is difficult to color.

Furthermore, it is conceivable to increase the apparent drying speed on plain paper by increasing the penetrating power of the ink using a surfactant or the like.However, in this case, since the surface tension of the ink is low, the ink may cause voids inside the ink. Since it penetrates into the paper so as to be embedded, problems such as show-through and bleeding occur.

Therefore, the present invention has no clogging in the nozzle, has excellent ejection stability, and is quick drying even on plain paper after recording, and has no problems such as show-through and bleeding. It is an object of the invention to propose such an aqueous recording ink.

(Means for Solving the Problems) In order to solve the above objects, the present invention relates to an aqueous recording ink containing water-soluble dye, water-soluble organic solvent and water as essential components, comprising polyoxyethylene represented by the following general formula: Benzyl ether compound (Where n is an integer in the range of 3 to 15).

The water-soluble dye which can be used in the present invention is, among direct dyes and acid dyes, dyes which have good solubility in water and water-soluble organic solvents and which improve the water resistance and weather resistance of the recorded image. # 17, # 19, # 38, # 108, # 154 CIAcid Black # 2, # 7, # 31, # 94, # 155 CIDirect Blue # 2, # 6, # 25, # 98, # 194 CIAcid Blue # 7 # 9, # 104, # 167, # 234 CIDirect Red # 1, # 9, # 17, # 28, # 99 CIAcid Red # 18, # 52, # 94, # 143, # 259 CIDirect Yellow # 8, # 27, # 58, # 86, # 142 CIAcid Yellow # 7, # 17, # 42, # 65, # 155, etc. The amount of addition can be determined in consideration of dissolution and precipitation of the dye after addition. It is desirable that the content be 9 Wt% or less.

Examples of the water-soluble organic solvent include polyhydric alcohols such as ethylene glycol, di- or tri- or polyethylene glycol, propylene glycol, dipropylene glycol, hexylene glycol, glycerin, and polyglycerin, ethylene glycol monomethyl ether, ethylene glycol monoethyl. Ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol dimethyl ether, triethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol Alkyl ethers of polyhydric alcohols such as monoethyl ether acetate, diethylene glycol monoethyl ether acetate, glycerin monoacetate and the like, and acetates thereof, or amino alcohols, N-methyl-2-pyrrolidone, 1,3-dimethylimidazoline, etc. One or a combination of two or more elemental compounds can be used. The addition amount is preferably 40 Wt% or less in consideration of the ejection stability and low-temperature stability of the ink after addition.

According to the study of the present inventors, the water-soluble dye, the polyoxyethylene benzyl ether of the above structural formula added to the aqueous recording ink containing water-soluble organic solvent and water as essential components, It has no harmful foaming property for stable ejection of the liquid, has no odor and is highly safe, and has an effect of improving the solubility of the dye in the ink.

In particular, this polyoxyethylene benzyl ether is
When added to the ink composition, it has sufficient penetrating power to paper without extremely lowering the surface tension of the liquid and despite the ink composition having a high surface tension.

The addition amount of the polyoxyethylene benzyl ether of the above structural formula to the ink is preferably 1.0 to 10 Wt%, and 1.0 Wt%.
% Or less, the penetrative power to paper is inferior, fast drying after recording cannot be obtained, and even if added at 10 Wt% or less, the penetrative power to paper does not change, and ink jet recording by increasing the viscosity of the ink. Adversely affects the ejection stability of the ink.

When the number of moles of ethylene oxide added to the polyoxyethylene benzyl ether of the above structural formula is 2 or less, the dissolution stability of the ink may be impaired depending on the type of the dye and the amount of the dye added, and When n is 16 or more, the viscosity of the ink becomes high when dissolved in the ink, and the ejection stability of the ink is impaired.

On the other hand, it is generally known that an oily substance is added to an aqueous ink for the purpose of expanding the selection range of recording paper, improving absorbability on paper, and improving solubility of various dyes. These oils include vegetable oils, unsaturated fatty acids, higher alcohols, fatty acid esters, mineral oils, etc. These are emulsified with surfactants to form emulsion inks, or solubilized with surfactants, various solvents, etc. Let
Although water-based inks have been prepared, inks containing these oily substances have disadvantages of extremely poor stability and high viscosity.

As a substance capable of eliminating the disadvantages of such an oily substance-containing ink and retaining the characteristics of containing an oily substance, it has an —OH group in the molecule, and is a poorly water-soluble and slightly soluble solvent such as 2-ethyl- Examples include 1,6-hexanediol, diethylene glycol hexyl ether, acetylene glycol, ethylene oxide adduct of acetylene glycol (additional mole number of 5 or less), ethylene glycol benzyl ether, and the like. An aqueous ink composition having the characteristics of the above oil-based substance-containing ink and having good stability can be obtained. Of course, water-soluble organic solvents are used together to dissolve in water because it is a substance that is poorly soluble in water and slightly soluble in water.
At this time, the polyoxyethylene benzyl ether according to the present invention acts very effectively also as a solubilizer for water.

In the ink according to the present invention, in addition to the above components, a surfactant, a humectant, a fungicide, and the like can be blended to such an extent that the properties are not impaired.

(Effects of the Invention) In summary, since the aqueous recording ink according to the present invention contains the polyoxyethylene benzyl ether of the above structural formula, even if the ink has a high surface tension, it has a sufficient penetrating power to the paper fibers. have. Therefore, it is not affected by the sizing agent on the paper surface, and when ink adheres to the paper surface,
The wettability of diffusion is suppressed and penetrates into the paper, but the rapid penetration into voids inside the paper is suppressed.

Therefore, the aqueous recording ink according to the present invention has a quick drying property on plain paper as well as the recording paper for ink jet recording, and can provide good print quality without bleeding or show-through.

Further, in the present invention, the solubility of the dye in the ink is promoted, and the problem of clogging of the nozzle due to the deposition of the dye is eliminated, and the ejection stability is also good, so that the speed of the ink jet recording apparatus can be increased. Can respond.

The aqueous recording ink according to the present invention can be used not only for ink jet recording but also for various water-soluble recording inks for writing instruments, recorders, stamps, and the like.

(Examples) Examples of the present invention will be described below, but the present invention is of course not limited to these examples.

Formulation Example 1 CIDirect Black # 19 2.0Wt% Glycerin 10.0Wt% Diethyl glycol 5.0Wt% Sodium dehydroacetate 0.1Wt% Polyoxyethylene benzyl ether (n = 5) 5.0Wt
% Ion-exchanged water Remaining Formulation Example 2 CIAcid Blue # 234 2.0Wt% PEG # 200 8.0Wt% Diethylene glycol monoethyl ether 5.0Wt% Sodium dehydroacetate 0.1Wt% Polyoxyethylene benzyl ether (n = 8) 5.0Wt
% Ion-exchanged water Residue Formulation Example 3 CIDirect Yellow # 142 2.0Wt% PEG # 300 10.0Wt% Polyoxyethylene alkyl ether 1.0Wt% Sodium dehydroacetate polyoxyethylene benzyl ether (n = 3) 4.0Wt% Residue of ion-exchanged water Example 4 CIAsid Black # 94 2.0Wt% diethylene glycol monobutyl ether acetate 2.
0 Wt% Propylene glycol 8.0 Wt% N-methyl-2-pyrrolidone 5.0 Wt% Sodium dehydroacetate 0.1 Wt% Polyoxyethylene benzyl ether (n = 14) 3.0 Wt
% Ion-exchanged water Remaining Formulation Example 5 CIDirect Red # 28 2.0Wt% Benzyl alcohol 1.0Wt% Glycerin 10.0Wt% Sodium dehydroacetate 0.1Wt% Polyoxyethylene benzyl ether (n = 15) 6.0Wt
% Ion-exchanged water Remaining Formulation Example 6 CIAcid Yellow 2.0Wt% Ethylene glycol monobenzyl ether 2.0Wt% PEG # 200 10.0Wt% Sodium dehydroacetate 0.1Wt% Polyoxyethylene benzyl ether (n = 7) 5.0Wt
% Deionized water Remainder Formulation Example 7 CIDirect Black # 19 2.0Wt% Acetylene glycol 0.2Wt% Glycerin 10.0Wt% Sodium dehydroacetate 0.1Wt% Polyoxyethylene benzyl ether (n = 8) 8.0Wt
% Ion-exchanged water Remainder Formulation Example 8 CIAcid Blue # 234 2.0Wt% 2-Ethyl-1,6-hexanediol 1.0Wt% PEG # 200 10.0Wt% Sodium dehydroacetate 0.1Wt% Polyoxyethylene benzyl ether (n = 12) 6.0Wt
% Ion-exchanged water Remaining Formulation Example 9 CIDirect Yellow # 142 2.0Wt% Glycerin 10.0Wt% Diethylene glycol hexyl ether 0.5Wt% Sodium dehydroacetate 0.1Wt% Polyoxyethylene benzyl ether (n = 5) 4.0Wt
% Benzyl ether (n = 13) 4.0Wt% Ion-exchanged water Remaining Formulation Example 10 CIAcid Black # 94 2.0Wt% Diethylene glycol 10.0Wt% Acetylene glycol EO adduct 5.0Wt% Dehydroacetic acid sodium 0.1Wt% Polyoxyethylene benzyl ether (n = 10) 5.0Wt
% Ion-exchanged water balance Comparative formula 1 CIDirect Black # 19 2.0Wt% PGE # 200 12.0Wt% Diethylene glycol 6.0Wt% Sodium dehydroacetate 0.1Wt% Ion-exchange water balance Comparative formula 2 CIDirect Blue # 234 2.0Wt% Glycerin 12.0Wt % Diethylene glycol monoethyl ether 5.0Wt% Sodium dehydroacetate 0.1Wt% Ion-exchanged water Residue Comparative formula 3 CIAcid Blue # 234 2.0Wt% Glycerin 10.0Wt% Polyoxyethylene benzyl ether (n = 2) 8.0Wt
% Sodium dehydroacetate 0.1Wt% Ion-exchanged water Residue Comparative formula 4 CIDirect Yellow # 142 2.0Wt% PEG # 200 10.0Wt% Sodium dehydroacetate 0.1Wt% Polyoxyethylene benzyl ether (n = 18) 10.0Wt
% Ion-exchanged water balance Comparative Formulation Example 5 CIDirect Red # 28 2.0Wt% PEG # 300 15.0Wt% Sodium dehydroacetate 0.1Wt% Sodium dioctylsulfosuccinate 2.0Wt% Ion-exchanged water balance The above Formulation Examples 1-10 and Comparative Formulation Example 1 After mixing the compositions of No. 3 and No. 3 and suction-filtering with a membrane filter having a pore size of 0.45 μ,
The ink was prepared by deaeration under reduced pressure.

The obtained ink was subjected to various recording tests using a drop-on-demand type ink jet recording apparatus under the conditions of a frequency of 2 KHZ, a pulse voltage of 80 V, and a nozzle diameter of 60 μm, and the following properties (1) to (3) were tested.

(1) Continuous discharge stability In a constant-temperature environment room, each in an atmosphere of 5 ° C, 20 ° C, and 40 ° C, 48
A continuous discharge test was carried out for a long time, and in Formulation Examples 1 to 10 and Comparative Examples 1 and 2, stable and clear recordings were obtained under any conditions. However, Comparative Formulation Example 3 was at 5 ° C. 4
Caused clogging at 5 ° C. and 40 ° C. In addition, Comparative Formulation Example 5 caused clogging which was considered to be due to bubbles under any conditions.

(2) Discharge response Intermittent discharge every 15 minutes and discharge after standing for 4 weeks were performed. However, in each of Formulation Examples 1 to 10 and Comparative Formulation Examples 1 and 2, there was no abnormality such as nozzle clogging. Although stable and clear recording was obtained, which was completely the same as the expected recording state, in the case of Comparative Formulation Examples 2 to 5, even after ejection for 4 weeks, printing disorder was observed.

(3) Recording drying properties Recording paper A (silica-coated paper) for ink-jet writing paper A (paper station paper according to JIS / P3201 standard), writing paper B (office paper according to JIS / P3202 standard), writing paper C
Using four types of recording paper (note paper conforming to the standards of JIS / P3203), the drying properties were compared by the following test.

(A) Transfer test method The above paper was set by an ink jet printer so that printing was performed at an interval of 5 seconds per line, and printing was performed for 1 minute (12 lines). Place the printed paper on the glass plate, and after 10 seconds, place the same quality paper on the printing surface, put the glass plate and the weight on top of it, weigh 500g, press both papers together, stop for 1 minute, When released, the printing time at which the print was transferred to the superposed paper was examined. Table 1 shows the test results.

In Table 1, transfer within a print time of 10 seconds or less means that practically no print is transferred, and transfer of a print time of 1 minute or more means that all prints have been transferred.

(B) Friction test method After rubbing the printing surface of the above paper with a finger immediately after recording (1 to 2 seconds after recording and printing) with an ink jet printer,
The printing condition was observed. Table 2 shows the results.

(Evaluation of Image Quality) The image quality was evaluated by observing the bleeding state and the state of show-through of the images recorded on the paper by the ink jet printer. The results are shown in Tables 3 and 4.

(A) Bleed state (B) Show-through state As is clear from the above test results, the general aqueous inks (Comparative Examples 1 and 2) have no problem in continuous ejection stability and ejection response, but the recording dryness is only when ink jet recording paper is used. And no other records can be made.

In the case of ink having a low surface tension and a high penetrating power (Comparative Example 5), a problem arises in continuous ejection stability and ejection response,
In addition, the ink according to the present invention has good continuous ejection stability and ejection responsiveness, whereas the ink according to the present invention has a quick drying property with respect to plain paper, but has good ink ejection qualities. It was also found that the ink had excellent quick-drying properties, bleeded on any paper, showed almost no show-through, and did not impair the image quality.

Claims (1)

(57) [Claims] An aqueous recording ink comprising a water-soluble dye, a water-soluble organic solvent and water as essential components, comprising a compound represented by the following general formula: (Wherein, n is an integer in the range of 3 to 15).