JP2000044854A - Ink set for ink jet recording - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ink set having excellent recoverability of fill-in, preserving stability and setting stability by including a prescribed amount of chelate reagent in an ink having a high coloring matter added amount among plural inks for ink jet recording. SOLUTION: This ink set is used for an ink jet recording device having more than one recording head having plural nozzle opening parts ejecting (n)- kinds (n) is a natural number) of recording inks containing coloring materials and water onto a recording medium and a recovering means simultaneously capable of sucking (n)-kinds of inks from an opening parts of the recording head. Among (n)-kinds of recording inks, a chelate reagent such as ethylenediaminetetraacetic acid disodium is contained in (n/2) kinds of inks having high coloring matter added amounts, and a weight ratio of the chelate reagent to the coloring matter content in the ink is within a range of (1/75)-(1/500). An adding amount of the chelate reagent is in a range of 0.005-0.2 wt.% and the ink is constituted with black, cyanogen, magenta and yellow (ink), and the chelate reagent is contained in the black and cyanogen (ink).

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to an ink jet recording apparatus having excellent color image reliability, which is used in an ink jet recording apparatus for performing ink jet recording using a plurality of kinds of inks. The present invention relates to an ink set. 2. Description of the Related Art In recent years, as an image output mechanism for a recording medium, an ink jet recording apparatus has attracted attention in various fields due to its size, speed, quietness, and price. I have. Especially in the field of printers that use paper as a recording medium, it is a technology that has existed for a long time.
So-called color ink jet recording apparatuses have become widespread. In general, a color ink jet recording apparatus has a plurality of inks of yellow (hereinafter, Y), magenta (hereinafter, M), cyan (hereinafter, C), black (hereinafter, Bk), and, if necessary, more. Then, these are ejected from a nozzle onto a print medium, and a print image is formed by using a single color and / or a composite color obtained by combining two or more colors. Inkjet recording devices are one or more for each color,
Generally, a print head having nozzles of about 10 to 300 for each color is provided. However, since ink is always present in the nozzles so that ink can always be ejected, ink components, especially water, are always present. Evaporation of volatile components such as occurs.
Therefore, when the ink is not used for a long time, non-volatile and low-volatile components such as a coloring material and a moisturizing component in the ink may be solidified and fixed in the vicinity of the nozzle portion. These solidifications / fixations hinder normal ejection of ink droplets, and cause clogging phenomena such as flight bending and ejection failure. [0004] Conventionally, in an ink jet recording apparatus, a cap for a recording head is automatically known by a head cap other than when printing, thereby preventing dust and the like from adhering to a nozzle portion and an ink component. A mechanism or the like is used to suppress evaporation of the ink, and when a clogging phenomenon occurs, a pump sucks ink from a recording head through a suction port which also serves as a head cap, thereby normalizing ejection. [0005] However, a color ink jet recording apparatus has a plurality of types of inks, and each of these inks has a composition and characteristics such as the kind and amount of a coloring material. However, the easiness of clogging and the resilience are also greatly different. For example, in the case of inks having the same color material but different contents, the viscosity tends to increase as the color material amount increases, and the water content is adjusted by adjusting the amount of the wetting agent to adjust the viscosity. Differences occur in the rate of increase in viscosity due to evaporation, the ease of solidification, and the recoverability when solidified. Therefore, when a recording apparatus using a plurality of kinds of inks tries to suck with one head cap at a time, only ink that is easy to recover recovers first, and ink that is more difficult to recover does not recover easily. You have to do more recovery action,
In the worst case, there is a problem that ink is continuously sucked from the recovered nozzle, and difficult ink is not recovered forever. In addition, even when the ink is recovered, there is a problem that the ink that is easily recovered is sucked wastefully. In order to solve this problem, Japanese Patent Laid-Open No. 6-31 is disclosed.
Japanese Patent No. 2516 discloses a method in which a recording apparatus is provided with different recovery operation means for each ink, and a recovery operation is performed by changing the operation content for each ink. According to this method, since the recovery operation is performed by optimizing the operation content independently for each ink, it is possible to satisfactorily recover the defective ejection even if the ink characteristics are different. However, since it is performed separately for each ink, if the method of sucking all the colors at once is used, even if only one recovery operation is needed, the recovery operation for the type of ink that is required is necessary. In addition, there is a problem that the operation time becomes very long. When the suction caps are individually provided for each ink type and the operations are performed simultaneously, time loss is reduced, but the mechanism itself is required for several inks, and it is not necessarily preferable in terms of size, cost, control mechanism, and the like. I can't say. There are many proposals for improving the clogging recovery of the ink itself. In particular, proposals for improving the ink by adding a chelating reagent are disclosed in JP-A-6-9.
A number of proposals have been made, including Japanese Patent No. 3218 and Japanese Patent Application Laid-Open No. 58-89667, all of which are intended for use in a single color, and a plurality of inks having different clogging recovery performances. At the same time, it is not a proposal based on the purpose of recovering effectively. Therefore, when a single ink is used, they work effectively and a sufficient improvement in recoverability is seen. However, when a plurality of types of inks are used at the same time, the recoverability becomes uneven, making recovery difficult. No ink was produced, and no effect was found. Accordingly, an object of the present invention is to solve these problems. In other words, in an ink jet recording apparatus that forms a printed image on a recording medium using a plurality of ink jet recording inks, the ink jet recording has excellent clogging recovery properties and excellent reliability such as storage stability and printing stability over a long period of time. It is to provide an ink set for use. The above object is achieved by the present invention. That is, n containing at least a coloring material and water
At least one recording head having a plurality of nozzle openings for discharging recording ink of a type (n is a natural number, the same applies hereinafter) to a recording medium, and simultaneously suctioning the n types of ink from the nozzle openings of the recording head An ink set used for an ink jet recording apparatus having a possible recovery means, wherein at least n / 2 kinds of inks having a high coloring material addition amount among the n kinds of ink jet recording inks contain a chelating reagent, and The weight ratio of the chelating reagent to the colorant content in the ink is in the range of 1:75 to 1: 500. DETAILED DESCRIPTION OF THE INVENTION An ink set for ink-jet recording according to the present invention is characterized in that at least n of the n kinds of inks constituting the ink set have a color material added to a half (n / 2) of the high color material addition amounts. , Water and a colorant in a weight ratio of 1:75 to
It is characterized by containing a chelating reagent contained in the range of 1: 500. Using the ink set of Comparative Example 1 described below, the present inventors left the recording apparatus for one month in an environment of 40 ° C. according to the method of the embodiment and evaluated the clogging recovery property. Since the recoverability was the poorest,
According to No. 18, 40 ppm (= 0.004%) of ethylenediaminetetraacetic acid (EDTA) was added to the Bk and all colors, but almost no improvement was observed (Comparative Examples 2 and 3). Next, the present inventors adjusted the amount of EDTA to 4
000 ppm (= 0.4%), and added to Bk and all the colors to perform the same evaluation (Comparative Examples 4 and 5).
In the case where only Bk was added, although the improvement was seen in Bk, C deteriorated, and in each case, the phenomenon that the ejection stability of ink droplets was remarkably reduced and the quality of the printed image was greatly deteriorated occurred. I have. The present inventors have conducted intensive studies on the relationship between the chelating reagent to be added and the ink composition. As a result, when added in a weight ratio of 1:75 to 1: 500 with respect to the amount of the coloring material, an extremely large amount was obtained. It has been found that clogging effectively acts on clogging. When the addition amount of the chelating reagent is less than 1: 500, no improvement effect of the clogging recovery property is seen, and
When the number is more than 75, the clear cause is unknown, but the ejection stability of the ink drops is deteriorated, and a good recorded image is not obtained.
Therefore, it is preferable to add in the range of 1:75 to 1: 500 with respect to the amount of the coloring material. It has also been found that more preferable results can be obtained when the absolute amount of the chelating reagent is used in the range of 0.005 to 0.2%. If it is less than 0.005%, the effect is not sufficient, and if it is more than 0.2%, the precipitation of EDTA itself is observed due to the evaporation of water in the ink, which may cause the recovery to be more difficult. [0015] In the ink set of the present invention, it is preferable that the chelating reagent is contained in at least a half or more of the inks in the amount in the order of increasing the amount of the coloring material. If it is less than half, unevenness occurs in the improvement of the recovery property, and a sufficient effect cannot be obtained, and even if it is included only in the ink with a small amount of the coloring material even if it is half, the effect cannot be obtained. . As the chelating reagent to be used, in addition to the above-mentioned EDTA, trans-1,2-cyclohexanediaminetetraacetic acid, glycol etherdiaminetetraacetic acid, diethylenetriaminepentaacetic acid, triethylene Tetraamine hexaacetic acid, nitrilotriacetic acid, ethylenediaminediacetic acid, dioxaoctanediaminetetraacetic acid, tetraethylenepentamineheptaacetic acid, N- (2
-Hydroxyethyl) ethylenediaminetriacetic acid, salts thereof, and the like can be used. Among them, disodium ethylenediaminetetraacetate works very effectively and is most preferable. The coloring material used in the ink set of the present invention is a water-soluble dye soluble in an aqueous ink, and specifically, a water-soluble acid dye, a direct dye, a reactive dye and the like can be used. . Further, it is desirable that the amount of the coloring material to be added is in the range of 0.4 to 20% by weight in the ink containing the chelating reagent. In addition, in the ink set containing no chelating reagent, the content is desirably in the range of 0.1 to 10% by weight. Further, as the solvent used for the ink constituting the ink set of the present invention, water or a mixture of water and a water-soluble organic solvent is preferable. As the water-soluble organic solvent, a low-volatile solvent is preferable from the viewpoint of suppressing clogging. For example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, 1,3-propanediol, 1,2 Polyhydric alcohols such as 1,6-hexanetriol and glycerin; ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether;
Glycol ethers such as dipropylene glycol monomethyl ether; formamide, dimethylformamide, diethanolamine, triethanolamine, 1,
Nitrogen-containing solvents such as 3-dimethyl-2-imidazolidinone, 2-pyrrolidone, and N-methyl-2-pyrrolidone; and sulfur-containing solvents such as thiodiglycol and dimethylsulfoxide. These solvents may be used alone,
Two or more kinds may be used in combination, and the content is 3 to 40% by weight, preferably 3 to 30% by weight based on the whole ink.
Range. When the content is less than 3 wt%, clogging at the nozzle tip is likely to occur quickly, and when the content is more than 40 wt%, the dryness of the recorded image is reduced, and the image is blurred and the print quality is reduced. This is because a phenomenon occurs. The inks constituting the ink set of the present invention include lower alcohols such as ethanol, 1-propanol and 2-propanol, fatty acid salts, and alkyl sulfate in order to promote drying of the ink after image formation. It is preferable to include an anionic surfactant such as an ester salt, or a nonionic surfactant such as acetylene glycols, polyoxyethylene alkyl ethers, and polyethylene fatty acid esters. In the case of lower alcohols, the content is 2 to 10% by weight, preferably 2 to 6% by weight.
% In the case of a surfactant, and 0.01 to 2 wt.
% Is desirable. If the content of each is less than this, sufficient effect to promote the drying property is not obtained, and if the content is too large, bleeding occurs in a printed image, and the ejection stability of ink droplets is affected, and printing quality is deteriorated. May be caused. In particular, when an image is formed using a plurality of types of inks as in the ink set of the present invention, bleeding at the boundary between adjacent color inks is a major problem in print quality. By including the above-mentioned acetylene glycol-based nonionic surfactants and glycol ethers, this problem is solved, and a clear image without bleeding at the boundary can be obtained. More preferably, by using an acetylene glycol-based nonionic surfactant and a glycol ether in combination, a clearer and more excellent print quality color image can be obtained. Examples of the acetylene glycol-based nonionic surfactant include Olfin E1010, Olfin STG, and Surfynol 104E (all products of Nissin Chemical Industry Co., Ltd.). As the glycol ethers, the above-mentioned water-soluble organic solvents are preferred, and particularly preferred are diethylene glycol monobutyl ether, triethylene glycol monobutyl ether and propylene glycol monobutyl ether. Also, the amount of addition is the same as that of the above-mentioned water-soluble organic solvent, and it is more preferable that it is selected in the range of 3 to 30% by weight. If less than 3 wt%, almost no effect is obtained, and 30 wt%
Above, on the contrary, bleeding becomes large, and the whole image is blurred, and conversely, the print quality is degraded. Therefore, it is preferable to use it within the described range. Further, the ink constituting the ink set of the present invention may contain a water-soluble polymer or a water-soluble resin, if necessary.
An antifoaming agent, a pH adjusting agent, a preservative, a rust inhibitor, and the like may be included. The present invention will be described more specifically below with reference to examples. Examples 1 to 4 and Comparative Examples 1 to 8 described in Table 1
Is a four-color ink set of Bk, C, M, and Y. Each of these inks can be manufactured by a conventional method. For example, there is a method in which, after sufficiently mixing and dissolving each component, pressure filtration is performed with a membrane filter having a pore size of 1 μm, and this is degassed to prepare an ink. [Table 1] [Table 2] [Table 3] The following tests were performed on these ink sets using an ink jet recording apparatus: MJ-830C (manufactured by Seiko Epson Corporation). That is, after the ink of the ink set was injected into the ink cartridge for the recording apparatus for each color chamber, the ink set was mounted on the recording apparatus, and the following test was evaluated and confirmed by printing. Test 1: Evaluation of clogging recovery property After confirming that all nozzles discharge normally, the power of the recording apparatus was turned off in a normal state,
2 months in a 40 ° C. environment, 3 months in a 25 ° C. environment, and 4 months in a 40 ° C. environment for 12 months. For each of these, the number of times required for normal recovery in the recovery operation by simultaneous suction of all colors was measured for each color. A: Clean discharge or recovery operation 1-2 immediately after power-on
Normalized at times (good). B: Normalization after 3 to 4 recovery operations (no problem in use). C: Normalized after 5 to 6 recovery operations (use problem). D: No recovery was performed up to six recovery operations (bad). Test 2: Print stability 1) 10%, 2) 25 ° C, 3) Duty print on average 25% (6.25% for each color) in each temperature environment of 40 ° C.
Four sheets were printed, and the printing stability of each color was checked. A: Good printing (good) without problems over 500 pages. B: Good printing with no problem for 300 pages or more, print bending or missing up to 500 pages (no problem in use). C: Good printing without any problem on 50 pages or more, print bending or missing occurred up to 300 pages (there is a problem in use). D: Print bending or missing occurred up to 50 pages of printing (defective). The results of Tests 1 and 2 are shown in Table 1. By using the ink set for ink-jet recording of the present invention, the ink-jet recording apparatus is capable of forming a print image on a recording medium using n kinds of ink-jet recording inks. In a case where the suction operation performed to maintain the ejection reliability and the like is a recovery means having a structure in which n number of inks are simultaneously suctioned from one suction port, without causing unevenness of recoverability for each ink, It is possible to recover clogging effectively in a short time, and to provide reliability such as storage stability and printing stability for a long period of time.

Claims (1)

Claims 1. An at least one printhead having a plurality of nozzle openings for discharging n types (n is a natural number, hereinafter the same) of recording ink containing at least a colorant and water to a recording medium. And an ink set for use in an ink jet recording apparatus comprising: a recovery unit capable of simultaneously suctioning the n types of inks from the nozzle openings of the recording head, wherein at least a coloring material among the n types of ink jet recording inks It is characterized in that the chelating reagent is contained in n / 2 kinds of inks having a high addition amount, and the ratio of the chelating reagent to the coloring material content in the ink is in the range of 1:75 to 1: 500 by weight. Ink set for ink jet recording. 2. The amount of the chelating reagent added is 0.005.
2. The composition according to claim 1, wherein the content is in the range of 0.2 to 0.2 wt%.
2. The ink set for inkjet recording according to item 1. 3. The method according to claim 1, wherein the chelating reagent is disodium ethylenediaminetetraacetate.
3. The ink set for inkjet recording according to 2. 4. The method according to claim 1, wherein the n kinds of inks are composed of black ink, cyan ink, magenta ink and yellow ink, and at least the black ink and cyan ink contain the chelating reagent. The ink set for inkjet recording according to the above.