JPH0693218A - Ink, method for ink jet recording using the same and apparatus for ink jet recording using the same ink - Google Patents

Abstract

PURPOSE:To obtain an ink, comprising a prescribed amount of a chelate reagent, excellent in printing and extrusion performances and reliability and useful as an apparatus, etc., for ink jet recording. CONSTITUTION:The ink comprises a chelate reagent such as ethylenediaminetetraacetic acid in an amount of 0.01-50ppm based on the total amount of the ink and has 1-5cP viscosity at 25 deg.C and 26-60dyne/cm surface tension.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink, an ink jet recording method using the ink, and an ink jet recording apparatus, and in particular, a so-called bubble jet in which thermal energy is applied to the ink to form ink droplets. The present invention relates to an inkjet recording ink used for recording, an inkjet recording method, an inkjet recording unit, an ink cartridge, and an inkjet recording device.

[0002]

2. Description of the Related Art Conventionally, various ink jet recording methods have been proposed.
In the so-called bubble jet recording method described in Japanese Patent Laid-Open No. 51837, a high-density multi-nozzle has a very simple structure, so a high-quality image can be obtained at high speed and at a very low cost, and a special method is also available. It has the feature that it can print on plain paper that does not have a coat layer.

In this recording method, a liquid subjected to the action of thermal energy causes a state change accompanied by a sudden increase in volume, and a droplet is ejected from an orifice at the tip of the recording head by an action force based on the state change. Recording is performed by flying and adhering to the recording material.

Although the principle and configuration are very simple,
In order for this recording method to always realize the features of high image quality and high speed recording with high reliability, a great deal of ink and head technology is required. In bubble jet type ink jet recording, the performance required as an ink that can be printed on plain paper is mainly classified into printing performance, reliability, and ejection performance.

Of these, the following five items are important for printing performance and reliability. (1) Fixing property: Judgment is made by the time until the ink printed on the recording paper is apparently dried and the finger and the paper are not stained even if rubbed with the finger. It is preferable that this time is short. (2) OD: reflection density of a recorded image printed on recording paper.
Generally, it is preferable that the dye does not penetrate to the inside of the paper and the ratio of the dye remaining on the surface is large because the OD becomes high. (3) Print quality: The closer the printed recording dots are to a perfect circle, the better the print quality, and when printing with conventional ink on plain paper, the dots become jagged due to the influence of the fibers of the paper. (4) Fixing property: A property in which the ink evaporates and solidifies (clogging) in the inkjet recording head. It is preferably hard to solidify. (5) Initial ejection characteristics: The ejection characteristics of the first few shots when water is evaporated from the nozzle tip during printing pauses and the viscosity of the ink is increased.
The ejection direction may be oblique or may not be ejected.

These various performances are roughly classified into the printing performances (1) to (3) and the reliability (4) to (5).
Since these properties are often in conflict with each other, it is difficult to make an ink that satisfies all the performances.

For example, the fixing property and the fixing property. When the fixability is emphasized, the ink that easily evaporates is a condition of the excellent ink, while when the importance of the fixing property is considered, the ink that is difficult to evaporate in the reverse direction is the condition of the excellent ink, which causes a large contradiction. Occurs.

Further, there is a similar contradiction with respect to fixability and OD. In order to improve the fixing property, the permeability of the ink into the recording paper should be improved, but then the ink will sink in the depth direction of the paper. If the ink penetrates into the paper, the fibers on the surface of the paper scatter the light, which lowers the OD.

Similarly, there is a contradiction between the fixability and the print quality. That is, if the permeability of the ink into the recording paper is improved, the fixability is improved. However, since the paper has a non-uniform structure (unevenness and fibers), the permeation distance is large and small. If ink that easily penetrates is used, the difference in this penetration distance becomes even larger, and the dots do not become perfect circles but become jagged dots.

On the other hand, in the bubble jet type ink jet recording, the following four points are mainly required as ejection performance. (1) Ejection stability: It is preferable that the size, speed, and direction of ink droplets ejected from the orifice are always uniform and do not vary. (2) Discharge speed: The speed of ink droplets discharged from the orifice. Generally, a higher discharge speed is preferable, and it is usually about 3 to 20 m / s. (3) Frequency response: It is preferable that the shorter the time for which ink is replenished after ink droplets have been ejected, the higher the frequency response. (4) Life of head: By recording a large amount of data,
The heater of the recording head is destroyed, ejection becomes impossible, and deposits (so-called kogation) are accumulated on the heater surface, causing problems such as the thermal energy of the heater not being effectively transferred to the ink. There are cases in which the ejection performance such as ejection stability, ejection speed, and frequency response deteriorates and the ejection amount changes. The life of the head is represented by the number of ejection pulses until the initial ejection performance can be maintained.

In particular, with respect to the life of the head, ink has been improved conventionally. For example, the life of the head is improved by setting the content of the heavy metal in the ink to a certain concentration or less, as disclosed in JP-A-61-1113668 (Fe≤4 ppm) and JP-A-61-1113669 (Fe + Si≤). 9 ppm), No. 61-113671 (divalent metal ≦ 20 ppm), No. 61-113673 (P ≦ 2 ppm), and the like.

On the other hand, for example, Japanese Patent Laid-Open No. 56-4268.
As disclosed in Japanese Patent Publication No. 4, a proposal that a substance used as a film forming means is included in the ink to form a film on the heater surface and to reduce shock (cavitation) when bubbles are generated and disappeared. There is also.
Metal-containing compounds such as organometallic chelate compounds, organic acid metal salts, and metal-containing dyes are used as the film forming means in this proposal. Although these proposals significantly improve the life of the head, they are still insufficient, and further improvement of the life has been required.

[0013]

The object of the present invention is to provide printing performance (fixing property, OD, printing quality), reliability (fixing property, initial ejection), which are performances required for the above-mentioned plain paper compatible valve jet recording. Characteristics) and ink ejection performance (ejection stability, ejection speed, frequency response, head life), and other ink jet recording inks that enable high-speed recording, and ink jets using such inks. To provide a recording device.

[0014]

The above object can be achieved by the present invention described below. That is, the present invention is a recording agent,
An ink containing a liquid medium that dissolves or disperses the same is characterized in that the ink contains a chelating reagent in an amount of 0.01 to 50 ppm with respect to the total weight of the ink.

Further, in the ink jet recording method for recording by ejecting the ink as ink droplets, the ink contains a recording agent and a liquid medium for dissolving or dispersing the recording agent, and the chelating reagent is contained in the total weight of the ink. It is an inkjet recording method characterized by containing 0.01 to 50 ppm.

Further, an ink of an ink jet recording unit having an ink accommodating portion for accommodating ink, a head portion for ejecting the ink as an ink droplet, and an ink accommodating portion for accommodating the ink. It is an inkjet recording apparatus including a recording unit having a cartridge and an ink containing section for containing the ink, and a head section for ejecting the ink as an ink droplet.

(Preferred Embodiment) The present invention will be described in detail below with reference to preferred embodiments. The ink of the present invention is characterized mainly in that the ink contains a chelating reagent in an amount of 0.01 to 50 ppm.

Conventional inks for ink jet recording include
In order to prevent clogging caused by metal ions in the dye, a chelating agent has been added to the ink for the purpose of masking the metal (Japanese Patent Laid-Open No. 51-8).
5804 and 58-89667).

However, when such ink is used for bubble jet recording, the life of the head is rather shortened.
Therefore, the present inventors examined the relationship between the life of the head and the chelating reagent contained in the ink, and set the amount of the chelating reagent contained in the ink to 0.01 to 50 ppm, thereby improving the printing performance. The present invention has been completed based on the finding that it is possible to perform recording with excellent reliability and ejection performance, in particular, a long head life and excellent ejection stability.

The inventors of the present invention included a chelating reagent, ethylenediaminetetraacetic acid (EDTA), in the ink by changing the concentration, and performed a head durability test by changing the pulse number, and observed the surface of the heater by SEM. As a result, EDT
When the A concentration is high (more than 100 ppm), the surface layer of the heater (Fig. 3, 16-a) is gradually eroded and the film thickness becomes thin,
Gradually, the lower layer (Fig. 3, 16-b) was completely visible, and eventually the heater was broken.

On the contrary, when EDTA was not contained at all, neither the surface layer of the heater nor the disconnection was observed. From the above, it is considered that when the chelating agent is contained in the ink at a certain concentration or more, the chelating agent corrodes the surface of the heater when bubbles are generated and disappears, and the heater is broken to shorten the life of the head. Be done.

FIG. 1 shows the relationship between the concentration of EDTA contained in the ink, the heater disconnection pulse, and the head life (2 × 1).
It is completed with ⁰⁹ pulses). From the figure, it is understood that when the EDTA concentration in the ink exceeds 100 ppm, the heater wire breakage occurs at 4 × 10 ⁸ pulses or less, and the head life is greatly shortened.

Further, the present inventor has found that when the EDTA concentration in the ink is too low (less than 0.001 ppm), there is no problem as described above regarding the breakage of the heater, but this time, in the long-term recording, the ejection performance of the head. It has been found that the deterioration of the above occurs, the initial ejection performance cannot be maintained, and the head life is shortened.

This is because when bubbles are repeatedly generated and disappeared over a long period of time, kogation occurs due to the difference in dye type and concentration even if impurities such as heavy metals in the ink are below a certain concentration. It is considered that when an ink having a high OD is made, the dye concentration becomes high and the kogation is more likely to occur.

When the kogation adheres to the heater surface,
Since the thermal energy of the heater is not effectively transferred to the ink, problems such as insufficient discharge energy and insufficient discharge density and discharge amount occur, and the life of the head expires before the heater burnout occurs.

On the other hand, the concentration of EDTA is 0.01
The ink added in the range of about 50 to 50 ppm had no problem of heater breakage, no deterioration in the ejection performance of the head, and the life of the head was significantly extended. In this region, the reason why the ejection performance of the head is not deteriorated is not clear, but even if some kogation adheres to the heater surface due to a large amount of recording, the corroded amount of EDTA contained in a small amount causes an appropriate kogation. It is speculated that a large amount of kogation does not adhere to the heater surface due to the erosion, and the heater surface is always in a smooth state.

The chelating agent contained in the ink of the present invention is not particularly limited as long as the effects of the present invention can be obtained, but ethylenediaminetetraacetic acid (EDTA), trans-1,2- Cyclohexanediaminetetraacetic acid, diethylenetriaminepentaacetic acid, ethylenediaminediacetic acid (EDDA), dioxaoctanediaminetetraacetic acid (GEDTA), N- (2-hydroxyethyl)
Ethylenediaminetriacetic acid (HEPTA), N- (2-hydroxyethyl) iminodiacetic acid (HIDA), Nitrilotriacetic acid (NTA), Triethylenetetraminehexaacetic acid (T
THA), glycine, dihydroxyethylglycine and salts thereof (eg, EDTA.4Na).

The content of the chelating reagent in the ink is 0.01 to 50 ppm, preferably 0.01 to 10 ppm, and further 0.0 to the total weight of the ink.
1 to 4 ppm is preferable.

The method of measuring the concentration of the chelating reagent is specifically the atomic absorption photometric method (Kunkel, R., et al.
l. : Anal. Chem. 45, 1465 (197
According to 3)), it is preferable to quantify the copper ion of the Cu (II) -chelating reagent by the atomic absorption spectrophotometry as a quantitative method for a small amount of the chelating reagent. Therefore, the quantitative value by this method is the chelating reagent of the present invention. Use the concentration. Further, when the concentration is low enough to cause a measurement variation, it is also possible to measure after concentrating the ink.

The ink of the present invention contains at least a recording agent and a liquid medium for dissolving or dispersing the recording agent, in addition to the chelating reagent. As the recording agent, a dye or a pigment is used properly, but in the present invention, a water-soluble dye is preferably used.

As the dye, any water-soluble dye such as direct dye, acid dye and basic dye can be used. The concentration of the dye is usually appropriately selected from the range of 0.1 to 10% by weight based on the total weight of the ink.

The liquid medium used in the ink of the present invention is preferably water in combination with a water-soluble organic solvent. As the water-soluble organic solvent, a water-soluble organic solvent generally used for ink jet recording ink is used.
In other words, it is preferable that the vapor pressure of itself is low and the evaporation rate of water in the ink is slowed down, and also the solubility of the dye or the like is possessed, so that it has an effect as a fixing property improving agent.

Examples of water-soluble organic solvents that are preferably used include amides such as dimethylformamide and dimethylacetamide; ketones or ketone alcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; N-methyl- 2-
Nitrogen-containing heterocyclic ketones such as pyrrolidone, 1,3-dimethyl-2-imidazolidinone and 2-pyrrolidone; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; ethylene glycol,
Propylene glycol, butylene glycol, triethylene glycol, 1,2,3-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol and other alkylene glycols having 2 to 6 carbon atoms; glycerin, ethylene glycol Examples thereof include lower alkyl ethers of polyhydric alcohols such as methyl (or ethyl) ether, diethylene glycol methyl (or ethyl) ether and triethylene glycol monomethyl (or ethyl) ether.

Water is usually 40 to 9 relative to the total weight of the ink.
6, preferably 60 to 95, more preferably 73 to 94
Used in the weight% range. If it is less than 40% by weight, problems such as high viscosity, easy bleeding and poor fixability occur, and if it is more than 96% by weight, the amount of evaporative components is too large and the fixing property deteriorates. In addition, in order to improve the sticking property, an anti-sticking agent different from the conventionally used water-soluble organic solvent such as one having an evaporation suppressing effect, one improving the solubility of the dye, one suppressing the viscosity increase is used. You may.

As the anti-sticking agent, urea, a salt of triethylamine such as triethylamine hydrochloride, a salt of triethanolamine such as triethanolamine hydrochloride, a derivative of toluenesulfonamide and the like are used. These anti-sticking agents are added in an amount of 0.
It is preferable to appropriately select and use in the range of 1 to 30% by weight.

By using such an anti-sticking agent, it is possible to maintain high reliability without causing clogging even if the amount of the constituent components (solvent etc.) other than water is extremely reduced. Further, since the amount of water in the ink is large, the ink of the recorded matter is easily evaporated, which is advantageous for the plain paper recording performance such as OD, fixing property and print quality. Further, since urea and the like have an effect of suppressing an increase in viscosity, they exhibit superiority in initial ejection characteristics.

In addition to this, a solvent for improving the fixing property may be used. The ink using such a solvent has very excellent dryness when printed on a recording paper. The solvent which can be expected to have such effects is preferably methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, isobutyl alcohol or the like having 1 to 10 carbon atoms.
4 alkyl alcohols; cycloalkyl alcohols such as cyclohexanol; amides such as dimethylformamide and dimethylacetamide; ketones or ketone alcohols such as acetone and diacetone alcohol;
Ethers such as tetrahydrofuran and dioxane; N
-Nitrogen-containing heterocyclic ketones such as methyl-2-pyrrolidone and 1,3-dimethyl-2-imidazolidinone; glycerin; fatty acid alkylolamide, thiodiglycol,
N-acyl-sulcosinate or the like is used.

Of these substances, many alcohols such as ethyl alcohol have a relatively low boiling point, and therefore, a foaming accelerator which is an ejection energy source in a recording method in which thermal energy is applied to ink to eject the ink. Therefore, there is also an effect of increasing the discharge speed.

Further, it is possible to use a surfactant in the ink of the present invention. The surfactant is usually 0.01 to 0.5% by weight, preferably 0.1% by weight, based on the total weight of the ink.
It is used in the range of 01 to 0.2% by weight.

The viscosity of the ink used in the present invention is 25.
It is preferably 0.7 to 12 cP, and more preferably 1 to 5 cP at 0 ° C. This is because an ink outside this range has a slightly poor ejection stability in ink jet recording, and an ink having a viscosity of more than 12 cP penetrates into the recording material slowly due to its viscosity resistance and is disadvantageous in fixing property.

The surface tension of the ink used in the present invention is
It is preferably 26 to 60 dyne / cm at 25 ° C. Ink with a surface tension of less than 26 dyne / cm has a weak force to pull back the meniscus after ejecting liquid droplets, or conversely, when the meniscus protrudes, the force to pull back is weak, so that bubbles are entangled or the orifice The parts may get wet, which may cause twisting.
Also, with ink having a surface tension of more than 60 dyne / cm, the wettability is poor, and the ink may not remain on the nozzle wall of the head and may remain as bubbles.

By exploring the composition of the ink as described above, the ink used in the valve jet recording for plain paper has a particularly long head life, and has OD, fixability, print quality, fixing property, and initial ejection property. , Discharge stability,
It is possible to provide ink having excellent ejection speed and frequency response performance.

The ink of the present invention is particularly suitable for use in an ink jet recording method in which droplets are ejected by the action of heat energy for recording, but it goes without saying that it can also be used for general writing instruments.

As a method and apparatus suitable for recording using the ink of the present invention, a thermal energy corresponding to a recording signal is applied to the ink in the chamber of the recording head, and a droplet is generated by the thermal energy. And equipment.

2, 3 and 4 show examples of the head structure which is the main part of the apparatus. The head 13 has a groove 14 through which ink passes.
A glass, ceramics or a plastic plate having a heat generating head 15 used for heat-sensitive recording (a head is shown in the drawing, but is not limited to this)
It is obtained by bonding and. The heating head 15 includes a protective film 16 formed of silicon oxide, an aluminum electrode 17-
1 and 17-2, a heating resistor layer 18 made of nichrome, a heat storage layer 19, and a substrate 20 having a good heat dissipation property such as alumina.

The ink 21 is a discharge orifice (fine hole) 2
2, the meniscus 23 is formed by a pressure (not shown). Now, when an electric signal is applied to the electrodes 17-1 and 17-2, the area indicated by n of the heating head 15 rapidly generates heat, and bubbles are generated in the ink 21 in contact therewith,
The meniscus 23 is projected by the pressure, the ink 21 is ejected, becomes a recording droplet 24 from the orifice 22, and is ejected toward the recording material 25. FIG. 4 shows an external view of a multi-head in which many heads shown in FIG. 2 are arranged. The multi-head is manufactured by closely adhering a glass plate 27 having a multi-groove 26 and a heating head 28 similar to that described in FIG.

FIG. 2 shows the head 1 along the ink flow path.
3 is a cross-sectional view of FIG. 3, and FIG. 3 is a cross section taken along line AB of FIG. 2. FIG. 5 shows an example of an ink jet recording apparatus incorporating such a head. In FIG. 5, reference numeral 61 is a blade as a wiping member, one end of which is held by a blade holding member to become a fixed end, which is in the form of a cantilever. The blade 61 is arranged at a position adjacent to the recording area of the recording head.

Further, in the case of this example, the recording head is held in a protruding form in the moving path. Reference numeral 62 denotes a cap, which is arranged at a home position adjacent to the blade 61, and has a structure for moving in a direction perpendicular to the moving direction of the recording head to come into contact with the ejection port surface for capping. Further, 63 is an ink absorber disposed adjacent to the blade 61, and like the blade 61, is held in a form protruding in the moving path of the recording head. The blade 61, the cap 62, and the absorber 63 constitute an ejection recovery unit 64, and the blade 61 and the absorber 63 remove water, dust, and the like from the ink ejection port surface.

Reference numeral 65 denotes a recording head which has an ejection energy generating means and ejects ink to a recording material facing the ejection port surface where the ejection ports are arranged to perform recording, and 66 is equipped with this recording head 65. And a carriage for moving the recording head 65. The carriage 66 slidably engages with the guide shaft 67, and a part of the carriage 66 is connected (not shown) to a belt 69 driven by a motor 68. As a result, the carriage 66 can move along the guide shaft 67, and the recording head 65 can move the recording area and its adjacent area.

Reference numeral 51 is a paper feed section for inserting a recording material, and 52 is a paper feed roller driven by a motor (not shown). With these configurations, the recording material is fed to a position facing the ejection port surface of the recording head, and is ejected to a paper ejection unit provided with a paper ejection roller 53 as the recording progresses.

In the above structure, when the recording head 65 returns to the home position after recording is completed, the cap 62 of the head recovery section 64 is retracted from the movement path of the recording head 65, but the blade 61 is moved in the movement path. It is protruding. As a result, the ejection port surface of the recording head 65 is wiped. When the cap 62 comes into contact with the ejection surface of the recording head 65 to perform capping, the cap 62 moves so as to project into the movement path of the recording head.

When the recording head 65 moves from the home position to the recording start position, the cap 62 and the blade 61 are at the same positions as the above wiping positions. As a result, the ejection opening surface of the recording head 65 is wiped even during this movement. The above-mentioned movement of the recording head to the home position is performed not only at the end of recording or at the time of ejection recovery, but also at a predetermined interval to the home position adjacent to the recording area while the recording head moves in the recording area for recording. However, the wiping is performed along with this movement.

FIG. 6 is a diagram showing an example of an ink cartridge in which ink is supplied to the head through an ink supply member, for example, a tube. Here, 40 is an ink containing portion for containing the supply ink, for example, an ink bag, and a rubber stopper 42 is provided at the tip thereof. By inserting a needle (not shown) into this stopper 42,
The ink in the ink bag 40 can be supplied to the head. An ink absorber 44 receives the waste ink. It is preferable for the present invention that the surface of the ink containing portion that comes into contact with the ink is made of polyolefin, especially polyethylene.

The ink jet recording apparatus used in the present invention is not limited to the one in which the head and the ink cartridge are separately provided as described above, but is also suitable for the one in which they are integrated as shown in FIG. Used.

In FIG. 7, reference numeral 70 denotes a recording unit, in which an ink containing portion containing ink, for example, an ink absorber is contained, and the ink in the ink absorber has a plurality of orifices. Head portion 71
It is configured to be ejected as an ink droplet from. For the present invention, it is preferable to use polyurethane as the material of the ink absorber. Reference numeral 72 denotes an atmosphere communication port for communicating the inside of the recording unit with the atmosphere. The recording unit 70 is used in place of the recording head shown in FIG. 5, and is detachable from the carriage 66.

[0056]

The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited thereto. In the text, parts or% are based on weight unless otherwise specified.

(Examples 1 to 6 and Comparative Examples 1 to 3) The components shown in Table 1 were mixed in a beaker and stirred at 25 ° C for 4 hours. This mixture was subjected to pressure filtration with a membrane filter having a pore size of 0.22 μm to obtain the ink of the present invention.

Using this ink, a Canon bubble jet printer BJC-820J (resolution 360 DPI, ink ejection amount 45 pl) for ejecting the ink by the action of thermal energy is used for plain paper (Canon PPC paper S
K) Printing was performed, and fixing property, OD, printing quality, fixing property, ejection stability, ejection speed, frequency response, initial ejection special property, head life were evaluated to determine ink viscosity and surface tension. . The results are shown in Table 1.

(Evaluation Method and Evaluation Criteria) (1) Evaluation of Fixing Property Regarding fixing property, after printing alphanumeric characters on SK paper with a printer, 10, 20, 30, 40, 50 and 60 seconds later, filter paper (Toyo It was rubbed with No. 2 (trademark name) made of filter paper), and the judgment was made based on the number of seconds until the printed part was not stained. (20 ±
Measured at 5 ° C. and 50 ± 10% RH) ◯: Within 15 seconds Δ: 16 to 30 seconds ×: 31 seconds or more

(2) OD evaluation After solid printing of 4.5 × 9 mm on SK paper, the printed material was left at room temperature and normal humidity for 24 hours or more, and the printed portion was measured with a Macbeth densitometer (RD918). Then, the OD value was used for the determination.

◯: OD value 1.1 or more Δ: OD value 0.8 to 1.0 ×: OD value less than 0.8

(3) Evaluation of printing quality After printing alphanumeric characters on SK paper, it is left for 1 hour or more, and then bleeding at a dot level and sharpness of edge are 2
The evaluation was performed under the environmental conditions of 5 ° C. and 60% RH.

◯: There is no bleeding and the edges are sharp. Δ: Some bleeding is seen, and the edges are slightly blurred. ×: Many bleeding, both dots and edges are blurred.

(4) Evaluation of Adhesion Characteristics After filling a printer with a predetermined ink and printing alphanumeric characters continuously for 10 minutes, the printing was stopped, a cap was put on and left for 30 days (standing condition: 60 ° C. , 10 ± 5%
After RH), alphanumeric characters were printed again, and judgment was made by the number of recovery operations until the initial printing state was reproduced.

◎: Printing equivalent to the initial printing is possible without recovery operation ○: Printing equivalent to the initial printing is possible after 1 to 5 recovery operations △: Printing equivalent to the initial printing is possible after 6 to 10 recovery operations X: Printing equivalent to the initial printing is possible with 11 or more recovery operations.

(5) Evaluation of Ejection Stability, Ejection Velocity, and Frequency Response Using an inkjet recording head evaluation device manufactured by Canon Inc. (a device that synchronously emits a droplet discharge state with a strobe and observes it with a microscope TV camera). The ejection speed variation, ejection speed, and frequency response of various inks were measured and determined under the same conditions as the head driving conditions for printing with a printer.

(A) Evaluation of Discharge Stability The discharge speed was measured 30 times at 4 kHz by the above apparatus,
The standard deviation was determined.

◯: Standard deviation 0 to 0.49 m / s Δ: Standard deviation 0.5 to 1.0 m / s ×: Standard deviation 1.1 m / s or more.

(B) Evaluation of discharge speed The discharge speed was measured 30 times at 4 kHz by the above-mentioned device,
The average value was calculated and judged.

◯: Discharge speed 7.1 to 15 m / s Δ: Discharge speed 5 to 7 m / s ×: Discharge speed less than 5 m / s

(C) Frequency response evaluation With the above apparatus, ejection was carried out at a driving frequency of 0.1 kHz, and the frequency was gradually increased, and the ejection shape became a sword-like unstable ejection with no main droplet. The frequency was measured and judged.

◯: Frequency response of more than 4 kHz Δ: Frequency response of 2 to 4 kHz X: Frequency response of less than 2 kHz

(6) Evaluation of Initial Ejection Property After ejecting ink in an environment of 15 ° C./10% RH, the state of ejection of the first several ink droplets when the cap is not attached for a predetermined time and the ink is ejected again Was evaluated, and it was judged by the time when the ejection state was good.

◯: More than 20 seconds Δ: 5 to 20 seconds ×: less than 5 seconds

(7) Life of Head 10 ⁷ is continuously discharged by the above device at 4 kHz.
Ejection stability, ejection speed, and frequency response are evaluated for each pulse, and the number of pulses when the performance (rank of ◯ to ×) changes from the evaluation results before continuous ejection is used as the head life, It judged by the pulse number.

⊚: Head life exceeds 1.8 × 10 ⁹ ◯: Head life 1.5 to 1.8 × 10 ⁹ △: Head life 0.8 to 1.49 × 10 ⁹ x: Head life less than 0.8 × 10 ⁹ .

(8) Viscosity The viscosity was measured at 25 ° C. using an E-type viscometer VISCONIC ELD (Tokyo Keiki).

(9) Surface tension The surface tension was measured at 25 ° C. using a Kyowa CBVP type surface tensiometer type A-1 (Kyowa Kagaku).

[0079]

[Table 1]

[0080]

As described above, according to the present invention, the reliability of the recording head is improved, and the ink capable of achieving high-speed drying property, high recording density and high printing quality for a long period of time,
It is possible to provide an inkjet recording method using the same and an inkjet recording device using the ink.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between EDTA concentration, heater burnout pulse, and head life.

FIG. 2 is a cross-sectional view of a head portion of an inkjet recording device.

FIG. 3 is a vertical cross-sectional view of a head portion of an inkjet recording device.

FIG. 4 is an external perspective view of a head in which the heads shown in FIGS. 2 and 3 are multi-headed.

FIG. 5 is a perspective view showing an example of an inkjet recording apparatus.

FIG. 6 is a vertical sectional view of an ink cartridge.

FIG. 7 is a perspective view showing a recording unit having an ink head and an ink cartridge integrated structure.

[Explanation of symbols]

 61 Wiping Member 62 Cap 63 Ink Absorber 64 Ejection Recovery Section 65 Recording Head 66 Carriage 71 Orifice Tip 72 Ejection Heater 73 Substrate

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location C09D 11/02 PTG 7415-4J

Claims (23)

[Claims] 1. An ink containing a recording agent and a liquid medium in which the recording agent is dissolved or dispersed, wherein the ink contains a chelating reagent in an amount of 0.01 to 50 ppm with respect to the total weight of the ink. 2. The ink according to claim 1, wherein the content of the chelating reagent is 0.01 to 10 ppm with respect to the total weight of the ink. 3. The ink according to claim 1, wherein the content of the chelating reagent is 0.01 to 4 ppm with respect to the total weight of the ink. 4. The ink according to claim 1, wherein the chelating reagent is ethylenediaminetetraacetic acid (EDTA). 5. The ink according to claim 1, wherein the ink is for inkjet recording. 6. The ink according to claim 1, wherein the ink is used in a method of applying thermal energy to the ink to eject ink droplets. 7. The viscosity of the ink is 1 at 25 ° C.
The ink according to claim 1, which is in a range of up to 5 cP. 8. The ink according to claim 1, wherein the viscosity of the ink is in the range of 0.7 to 2 cP at 25 ° C. 9. The ink according to claim 1, wherein the surface tension of the ink is in the range of 26 to 60 dyne / cm at 25 ° C. 10. The water content of the ink is in the range of 40 to 96% by weight based on the total weight of the ink.
Ink described. 11. The water content of the ink is in the range of 60 to 95% by weight based on the total weight of the ink.
Ink described. 12. The water content of the ink is in the range of 73 to 94% by weight based on the total weight of the ink.
Ink described. 13. An inkjet recording method for recording by ejecting ink as ink droplets, wherein the ink contains a recording agent and a liquid medium in which the ink is dissolved or dispersed, and the chelating reagent is added to the total weight of the ink. To 0.0
An ink jet recording method, which comprises 1 to 50 ppm. 14. The ink jet recording method according to claim 13, wherein the chelating reagent is ethylenediaminetetraacetic acid (EDTA). 15. The ink jet recording method according to claim 13, wherein the recording method is a method in which thermal energy is applied to the ink to eject ink droplets. 16. An ink containing portion containing ink, and
An ink jet recording unit comprising a head portion for ejecting the ink as an ink droplet, wherein the ink is the ink according to any one of claims 1 to 12. 17. The ink jet recording unit according to claim 16, wherein the head portion has a head which causes thermal energy to act on ink to eject ink droplets. 18. An ink cartridge of an ink jet recording unit comprising an ink containing portion containing the ink, wherein the ink is the ink according to any one of claims 1 to 12. 19. An ink jet recording apparatus comprising a recording unit having an ink containing section for containing the ink and a head section for ejecting the ink as ink droplets, wherein the ink is any one of claims 1 to 12. Inkjet recording apparatus characterized by being described in 1. 20. The ink jet recording apparatus according to claim 19, wherein the head portion has a head which causes thermal energy to act on ink to eject ink droplets. 21. An ink jet recording apparatus comprising an ink cartridge having an ink containing portion for containing the ink and a recording head for ejecting the ink as an ink droplet, wherein the ink is any one of claims 1 to 12. An ink jet recording apparatus, characterized in that 22. The ink jet recording apparatus according to claim 21, wherein the ink cartridge has an ink supply unit that supplies the ink contained in the ink cartridge to the recording head. 23. The ink jet recording apparatus according to claim 21, wherein the recording head has a head which applies thermal energy to ink to eject ink droplets.