JPH02245074A - Ink jet recording ink - Google Patents

Abstract

PURPOSE:To prevent the association of a dye, thickening of an ink, and clogging of a nozzle orifice by compounding a specific wetting agent as a component of an ink jet recording ink. CONSTITUTION:An ink jet recording ink contg. a first component comprising a salt of pyrrolidonecarboxylic acid of formula I (wherein M1 is an alkali metal or amine) and/or a second component comprising L-alpha-pyrrolidinecarboxylic acid or a salt thereof of formula II (wherein M2 is H, alkali metal or amine). The pref. amts. compounded of the first and/or the second component are 1.0-20wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an inkjet recording ink that eliminates clogging of nozzle orifices of inkjet printers.

<Prior Art> As is well known, an inkjet printer prints by ejecting ink as uniform minute droplets onto a recording medium from a minute nozzle orifice. A problem with the above-mentioned inkjet printer that has not been improved yet is the problem of clogging of the nozzle orifice. That is, water in the ink evaporates at the tip of the nozzle orifice, causing clogging due to the dried ink.

Therefore, it has been proposed to use an organic solvent with a low vapor pressure in the ink in order to suppress the evaporation of water in the ink at the tip of the nozzle orifice.

As an example of the above-mentioned proposal, an inkjet recording ink consisting of a dye, a wetting agent which is an aliphatic polyhydric alcohol or a derivative thereof, a dialkyl sulfosuccinate, and water is disclosed in Japanese Patent Publication No. 60-23793. be.

That is, the low vapor pressure organic solvent (wetting agent), which is a component of the above proposal, suppresses the drying of the ink at the tip of the nozzle orifice by lowering the vapor pressure of the water in the ink and slowing down the evaporation of the water. This is to prevent clogging of the nozzle orifice.

<Problems to be Solved by the Invention> However, in the above-mentioned inks, most of the low vapor pressure organic solvents used are high molecular weight and high viscosity liquids, so they cannot be used in large quantities for the above-mentioned purposes or at low temperatures. In some cases, dyes may aggregate or separate, resulting in high viscosity, and aggregates such as dyes tend to adhere to the tip of the nozzle orifice, and clogging occurs easily inside the nozzle orifice due to increased ink viscosity. There is.

<Means for Solving the Problems> The present invention was proposed in view of the above, and includes a first component which is a pyrrolidone carboxylate having the following structural formula, and L
The present invention relates to an inkjet recording ink characterized by containing either one or both of -α-pyrrolidinecarboxylic acid or a salt thereof as a second component.

First component (pyrrolidone carboxylic acid salt) C) I2-C) 12 (In the structural formula on the left, Ml is Al second component (I, -0-pyrrolidinecarboxylic acid or its salt) Therefore, for the inkjet recording of the present invention The ink contains one or more of the above-mentioned first component pyrrolidone carboxylic acid salt, second component L-α-pyrrolidinecarboxylic acid or its salt, and water, a water-soluble dye, and a water-soluble organic It is composed of a solvent or the like.

Among direct dyes and acid dyes, the above-mentioned water-soluble dyes are preferably dyes that have good solubility in water and water-soluble organic solvents and improve the water resistance and weather resistance of recorded images, such as C, 1 , Direct Black #17. #19,
I38, I108, #154C, 1, Ac1d Bla
ck I2, I7, I31, I94, I155C, 1,
Direct Blue I2, I6, I25, I98
, #194C, 1, Ac1d Blue I7, I9,
I104, I167, I234C, 1, Direct
Red #1. #9, I17, I28, #99C,1,
Ac1d Red I18, I52, I94, I143
, I259C, 1, Direct Yellow I8
, I27, I58, I86, #142C, 1, Ac1d
Yellow #7. #17, I42, I65, I1
55, etc., and the blending amount is preferably 9 wt % or less, taking into account dissolution, precipitation, etc. of the dye after blending.

In addition, examples of water-soluble organic solvents include polyhydric alcohols such as ethylene glycol, di- or tri- or polyethylene glycol, propylene glycol, dipropylene glycol, hexylene glycol, glycerin, and polyglycerin, and ethylene glycol monoethyl ether. ,
Ethylene glycol monoethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monomethyl ether, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, triethylene glycol monoethyl ether, brobylene glycol monoethyl ether, propylene glycol monoethyl ether, ethylene glycol Monomethyl ether acetate
1. Alkyl ethers of polyhydric alcohols such as ethylene glycol monoethyl ether acetate, diethyl glycol monoethyl ether acetate, glycerin monoacetate and their acetates, or amino alcohols, N-methyl-2-pyrrolidone, 1 .Gj compound such as 3-dimethylimidacillin can be used alone or in combination of two or more kinds, and the amount to be blended is 4.
It is desirable that the content be 0 wt% or less.

The above-mentioned pyrrolidone carboxylic acid salt has the following structural formula: CI+□-C1 (□ (in the above structural formula, Ml represents an alkali metal or amine), and L- a-Pyrrolidinecarboxylic acid or a salt thereof is a low molecular weight substance whose structural formula is H2CH2 (in the structural formula 2, M2 represents l), an alkali metal, or an amine). It is contained as a wetting agent in the inkjet recording ink of the present invention.

In addition, as the alkali metal in M, , M2 of the above-mentioned horizontal structure type, Na, K, etc. can be used, and as the amine, alkanolamines such as mono-, di-, and triethanolamine, or alkaline amines can be used.

The above-mentioned pyrrolidone carboxylic acid salt, L-α-pyrrolidine carboxylic acid, and its salt are all natural moisturizing factors contained in human skin, and are low molecular weight substances with high water solubility.

In the present invention, the above-mentioned pyrrolidone carboxylate,
Focusing on the excellent hygroscopic and moisturizing properties of L-α-pyrrolidinecarboxylic acid and its salts, it is used in inkjet recording inks as an odorless and harmless wetting agent.
As mentioned above, pyrrolidone carboxylate, L-α-pyrrolidinecarboxylic acid, and its salts are low molecular weight substances with high water solubility, so they stably exist in ink and do not cause dye association. (Also, it does not increase the viscosity of the ink.

The blending amount of the above-mentioned pyrrolidone carboxylate, L-α-pyrrolidinecarboxylic acid and its salt is 160 to 20w.
t% is desirable; below 1.0 wt%, almost no moisture absorption and moisturizing effects are observed. In addition, the blending amount is 20wt
% or more, there is a risk that pyrrolidone carboxylate, L-α-pyrrolidine carboxylic acid, and its salts will precipitate, and the formation of insoluble matter and increase in viscosity may easily cause nozzle clogging.

Furthermore, when the above-mentioned pyrrolidone carboxylic acid salt and Lα-pyrrolidinecarboxylic acid or its salt are used in the present invention, there is a synergistic effect, and even by adding a small amount, it is possible to expect the effect of imparting wettability and preventing an increase in viscosity. .

As explained above, the inkjet recording ink of the present invention contains a water-soluble dye, a water-soluble organic solvent, and one or more of a pyrrolidone carboxylate and L-α-pyrrolidinecarboxylic acid or a salt thereof. In addition to the above-mentioned components, surfactants, antifungal agents, other wetting agents, and the like may be added to an extent that does not impair its properties.

For example, the above-mentioned fungicides include sodium dehydroacetate, sulfur sorbate, 24-dimethyl-6-
Examples include acetoxydioxane, sodium 2-pyridinethiol-1-oxide, sodium benzoate, sodium pentachlorophenol, and the like.
It can be blended within a range of 3 wt%.

In particular, when polyoxyethylene allyl ether is blended as a surfactant into the inkjet recording ink of the present invention, the above-mentioned pyrrolidone carboxylate, L-a
- It has excellent compatibility with pyrrolidine carboxylic acid and its salts, and can impart the effect of promoting dye solubility.

<Examples> Examples of the present invention will be shown below, but the present invention is of course not limited to these.

Example 1 G:, r, Direct Black #154 Ethylene glycol dehydroacetic acid pyrrolidone carboxylic acid triethanolamine salt Ion exchange water Example 2 C, 1, Direct Yellow #142 Glycerin dehydroacetic acid M sodium U9F Sodium Carponate Salt Ion Exchange Water Example 3 C, 1, Direct Red #28 PEG (Polyethylene Glycol) #2002-Pyridinethiol-1
-N side sodium pyrrolidonecarboxylic acid triethanolamine salt L-a -pyrrolidinecarboxylic acid ion exchange water 2.0wt% 8.0wt% 0.1wt% 10.0wt% 79.9wt% 2.0wt% 10.0wt% 0.1wt% 10, Ost% 77.9wt% 2.0wt% 5.0wt% 0.2wt% 2.0wt% 5.0wt% 85.8wt% Example 4 C, 1, DLrect Blue 89g Triethylene Crygor Polyquine ethylene alkyl ether 2-pyridinethiol-1 - oxide sodium pyrrolidonecarboxylic acid sodium salt L-α-pyrrolidinecarboxylic acid ion exchange water Example 5 C,1,Direct Black #154 Polyoxyethylene allyl J-Tylsorbic acid Tansuumpyrrolidonecarboxylic acid triethanolamine salt 10-pyrrolidinecarboxylic acid ion-exchanged water Example 6 C,1,Ac1d Blue #234 Chrysanthemum sorbate sodium pyrrolidonecarboxylic acid salt L-α-pyrrolidinecarboxylic acid salt Acid triethanolamine salt ion-exchanged water Example 7 C,1, Ac1d Red #259 Triethylene glycol dehydroacetic acid chloride salt Sodium salt ion-exchanged water Example 8 C, 1, Direct Yellow #86 Acrylic dehydroacetic acid 1-g L-0-pyrrolidinecarboxylic acid ion exchange water Example 9 (:, 1.Ac1d Black #I55 Sodium sorbate L-α-pyrrolidinecarboxylic acid g IJ J N ethylene benzyl ether (n=3
)2.0wt% 80.9wt% 2.0wt% 6.0wt% 0.1wt% 3.0wt% 5.0wt% 83.9wt% 2.0wt% 10.0wt% 0.1. wt% 15.0wt% 73.9wt% 2.0wt% 0.2wt% 14.0wt% 3.0wt% Ion exchange water comparative example I C, 1, Direct Black #154PEG (
Polyethylene Kligol) #200 Dehydro Vinegar! Sodium ion exchange water comparative example 2 C, 1, Direct Blue #98 triethylene glycol polyoxyethylene 1-lkyl ether 2-pyridinethiol-1-oxide Sodium ion exchange water comparative example 3 C, 1, Direct Blue 89g propylene glycol polyol Sodium ethylene alkyl ether dehydroacetate ion-exchanged water Comparative example 4 C,1,Ac1d Black #155 2.0wt% 6.0wt% 1.0wt% 0.2wt% 4.0wt% 3.0wt% 83.8wt % 2.0wt% 2.0wt% 0.2wt% 4.0wt% 4.0wt% 87.8wt, % 2.0wt% 10.0wt% 0.1wt% 5.0wt% 80.8wt% 2.0wt% 15.0wt% 0.1wt% 82.9wt% 2, Ort% ], 5.0wt% 1.0wt% 0.1wt% 81.9wt% 2.0wt% 15.0wt% 2.0wt% 0, bvt% 80.9wt% 2, Owt% diethylene glycol
15.0wt% sodium sorbate
0.2wt% L-α-pyrrolidinecarboxylic acid
0.5wt% ion exchange water 82.3wt% Comparative example 5 C,1,Ac1d Red #259
2. Owt% triethylene resin
10.0wt% butylcarpitol
6.0wt% sodium dehydroacetate O,
1wt% ion exchange water 81.9
wt% Each of the compositions having the above formulations was suction filtered through a membrane filter with a pore size of 0.45 μm, and then degassed under reduced pressure to prepare inks for Examples 1 to 9 and Comparative Examples 1 to 5, respectively.

The obtained ink was applied to a drop-on-demand type inkjet recording device at a frequency of 2 KH2 and a pulse voltage of 80.
A clogging resistance test was conducted as follows under the conditions of V and a nozzle orifice diameter of 60 μm.

In an environmental test room, the indoor temperature was set at 5℃, 20℃, and 40℃, and a continuous discharge test was conducted for 24 hours under each temperature condition. The discharge condition was investigated.

The criteria for evaluation are as follows, and the results are shown in Table 1 when the indoor temperature is 5°C, Table 2 when the indoor temperature is 20°C, and Table 3 when the indoor temperature is 40°C.

(Judgment criteria) No abnormality is observed...0 There are no satellites, but the dots are slightly disordered...○Satellites appear and the dots are also greatly disordered...△No discharge at all...×In addition, the above Satellites are spherical droplets at the tip of the nozzle orifice of an inkjet recording device, and are usually generated when ink dries and solidifies, or becomes a thick viscous substance that hangs and attaches to the tip of the nozzle orifice. be. Due to the ejection pressure, the satellites may scatter toward the recording medium, stain the recording surface, or cause clogging.

Table 1 Table 2 Table As is clear from the test results in Tables 1 to 3 above, Examples 1 to 9 of the present invention could be used in any of the atmospheres of 5°C, 520°C, and 40°C without clogging the nozzle orifice. Even in this case, stable recording can be performed until the end, and the ink ejection condition is extremely good.

On the other hand, in Comparative Examples 1 to 5, when the standing time becomes long, satellites are formed, and eventually a clogging state occurs. This tendency is particularly noticeable in a 5°C atmosphere.

<Effects of the Invention> As explained above, since the inkjet recording ink of the present invention contains pyrrolidone carboxylate or L-α-pyrrolidinecarboxylic acid and its salt, it has excellent hygroscopicity and moisture retention. Due to its properties, it can prevent the evaporation of water in the ink at the tip of the nozzle orifice, and prevent dye association and viscosity increase, similar to the high molecular weight and high viscosity organic solvents that are humectants contained in conventional inkjet recording inks. Nozzle orifice clogging is less likely to occur.

In addition, pyrrolidone carboxylate and La-pyrrolidinecarboxylic acid and their salts are contained in human skin and are odorless and non-toxic, so the inkjet recording ink of the present invention has excellent safety. It's ink.

Furthermore, when the inkjet recording ink of the present invention is used, the dots after recording are small and clear recording can be obtained.

Patent applicant: Taihohe Gyo Co., Ltd.

Claims (1)

[Scope of Claims] Either or both of the first component which is a pyrrolidone carboxylic acid salt having the following structural formula and the second component which is L-α-pyrrolidinecarboxylic acid or a salt thereof. An inkjet recording ink characterized by containing the ink as a part of the inkjet recording ink. First component (pyrrolidone carboxylate) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the structural formula on the left, M
_1 indicates an alkali metal or amines) Second component (L-α-pyrrolidinecarboxylic acid or its salt) ▲There are numerical formulas, chemical formulas, tables, etc.▼ (In the structural formula on the left, M
_2 represents H, alkali metal, or amines)