JP2006063340A - Inkjet ink, ink set, inkjet recording method, ink cartridge holder, recording unit and inkjet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet ink that has excellent decay durability and excellent plugging-recovering properties. <P>SOLUTION: This is an inkjet ink to be used in an inkjet recorder equipped with a recording head that has a liquid face contacting to the heating part including at least a metal or its oxide and includes, as a color material, a compound represented by general formula (I) [wherein R<SB>1</SB>is H, an alkyl, a hydroxy-lower-alkyl, a cyclohexyl, a mono- or di-alkylaminoalkyl or a cyano-lower-alkyl; R<SB>2</SB>, R<SB>3</SB>, R<SB>4</SB>, R<SB>5</SB>and R<SB>6</SB>are independently H, a 1-8 C alkyl or carboxyl (wherein the case where all of R<SB>2</SB>, R<SB>3</SB>, R<SB>4</SB>, R<SB>5</SB>and R<SB>6</SB>are all H is excluded)] or its salt and glycerol wherein the amount of the glycerol is more than 0.0 mass% to 4.0 mass% based on the whole mass of the inkjet ink and the pH of the ink is not less than 8.3. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ink jet ink, an ink set, an ink jet recording method, an ink cartridge, a recording unit, and an ink jet recording apparatus that are excellent in durability and adhesion recovery.

  The ink jet recording method is a recording method in which ink droplets are applied on plain paper and a recording medium such as glossy media to form an image, and it is rapidly spreading due to its low price and improved recording speed. Progressing. Further, in addition to the progress of higher image quality of recorded images, with the rapid spread of digital cameras, it has become widely popular as a method for outputting photographic images comparable to silver salt photographs.

  In recent years, higher image quality has been achieved due to the miniaturization of ink droplets and the improvement of the color gamut associated with the introduction of multicolor inks. On the other hand, however, demands for coloring materials and inks are increasing, and more stringent characteristics are required in terms of reliability such as improvement in color development, fixing recovery, and ejection stability.

  On the other hand, the problem of the ink jet recording method when compared with a silver salt photograph is the image storability of the obtained recorded matter. The recorded matter obtained by the ink jet recording method has lower image storability compared to silver salt photography, and when the recorded matter is exposed to light, humidity, heat, environmental gases present in the air for a long time. However, there is a problem that the color material on the recorded material is deteriorated and the color tone of the image is likely to change or fading, and many proposals have been made to solve the above problems.

For example, there is a proposal for improving fastness by using a colorant having an anthrapyridone structure having a specific structure (see, for example, Patent Documents 1 and 2). The fastness of the recorded matter obtained using the ink containing the dye is very excellent.
JP 2002-332419 A JP 2003-192930 A

  However, when an ink containing a color material having excellent image storability as described above is used as an ink applied to an ink jet recording apparatus, it may be difficult to ensure reliability. In particular, when the ink jet recording apparatus is not used for a long period of time, there is a problem that printing cannot be performed due to the ink solidifying inside the recording head, that is, the fixing recovery property is poor.

  In order to solve the above-mentioned problems, the present inventors have studied. Among many water-soluble organic solvents that have the effect of imparting reliability to the ink, in particular, glycerin is effective in improving the fixing recovery property. I found out that

  However, as a result of further examination by the present inventors, when an ink containing a colorant and glycerin having excellent image preservability as described above is used as an ink applied to an ink jet recording apparatus, depending on the composition of the ink, In some cases, it was difficult to ensure reliability. In particular, in an ink jet recording method in which thermal energy is applied to ink to perform ejection, when continuous printing is performed for a long period of time, the heat generating part liquid contact surface of the recording head (in the case where the heat generating part is in direct contact with the liquid, the heat generating part itself, Moreover, in the case of a form having at least one protective layer on the surface of the heat generating part, the deterioration (dissolution) of the protective layer) and the disconnection of the wiring for applying a voltage to the heat generating part occur. There was a case to have an influence.

  The present inventors have examined the cause of the phenomenon described above in the ink containing the colorant and glycerin excellent in image storability as described above. As a result, it has been found that the above phenomenon depends on a specific portion in the color material structure and a specific ion in the ink. The specific site is a substituent that easily releases hydrogen ions, for example, a hydroxyl group bonded to a triazine ring, and the specific ion is a hydroxide ion.

  When a coloring material having a substituent that easily releases hydrogen ions in its structure is in an aqueous solution (ink) state, the ink may have a buffer region (a region that maintains a substantially constant hydrogen ion concentration). The ink having the buffer region has an advantage that, for example, the pH can be maintained constant even when left in various environments such as during distribution, so that the decomposition of the coloring material can be suppressed.

  However, when continuous printing is performed for a long time using an ink having a buffer region in an ink jet recording apparatus having a heat generating part wetted surface containing at least one compound of a metal and a metal oxide, the ink is discharged (into the ink). Each time heat energy is applied, at least one of the metal and metal oxide compounds contained on the surface of the heat-generating part in contact with the hydroxide ion reacts with the hydroxide ion to deteriorate (dissolve) the surface of the heat-generating part. There is also a problem that the wiring for applying a voltage to the heat generating portion is disconnected, that is, the durability is poor.

  The inventors of the present invention have found a method that can solve the above-mentioned problems by devising the composition of the ink and can make full use of the colorant having a substituent that easily releases hydrogen ions. The present invention has been made based on this finding.

  Accordingly, an object of the present invention is to provide an ink-jet ink excellent in durability and adhesion recovery.

  Another object of the present invention is to provide an ink set, an ink jet recording method, an ink cartridge, a recording unit, and an ink jet recording apparatus using the ink jet ink.

  The above object is achieved by the present invention described below. That is, the ink-jet ink of the present invention is an ink-jet ink used for an ink-jet recording apparatus provided with a recording head having a heating part wetted surface containing at least one compound of metal and metal oxide, It contains a compound represented by the following general formula (I) or a salt thereof and glycerin as a material, and the content (mass%) of the glycerin exceeds 0.0 mass% with respect to the total mass of the ink jet ink and is 4 0.0 mass% or less, and pH is 8.3 or more.

  Formula (I)

(In the general formula (I), R ₁ is a hydrogen atom, an alkyl group, a hydroxy lower alkyl group, a cyclohexyl group, a mono- or dialkylaminoalkyl group, or a cyano lower alkyl group, and R ₂ , R ₃ , R ₄ , R ₅ and R ₆ are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a carboxyl group (provided that R ₂ , R ₃ , R ₄ , R ₅ and R ₆ are all hydrogen atoms) ).)

  An ink set according to another embodiment of the present invention is an ink set composed of a plurality of inks, and includes the inkjet ink having the above-described configuration as a magenta ink.

  An ink jet recording method according to another embodiment of the present invention is an ink jet recording method including a step of recording on a recording medium by discharging ink by an ink jet method, wherein the ink is an ink jet ink having the above-described configuration. It is characterized by that.

  An ink cartridge according to another embodiment of the present invention is an ink cartridge provided with an ink containing portion for containing ink, wherein the ink is an ink jet ink having the above-described configuration.

  According to another embodiment of the present invention, there is provided a recording unit comprising an ink storage portion for storing ink and a recording head for discharging ink, wherein the ink is an inkjet ink having the above-described configuration. It is characterized by being.

  An ink jet recording apparatus according to another embodiment of the present invention is an ink jet ink having the above-described structure in an ink jet recording apparatus including an ink containing portion for containing ink and a recording head for discharging ink. It is characterized by that.

  ADVANTAGE OF THE INVENTION According to this invention, the ink for inkjets excellent in durability and fixed recovery property can be provided. According to another embodiment of the present invention, an ink set, an ink jet recording method, an ink cartridge, a recording unit, and an ink jet recording apparatus using the ink jet ink can be provided.

  Hereinafter, preferred embodiments of the present invention will be described in detail.

  In the present invention, when the color material is a salt, the salt is dissociated into ions in the ink, but it is expressed as “contains a salt” for convenience.

<Ink>
(Color material)
The inkjet ink according to the present invention (hereinafter sometimes simply referred to as “ink”) must use a compound represented by the following general formula (I) or a salt thereof as a coloring material. This is because the compound represented by the following general formula (I) or a salt thereof can give excellent image storability to the recorded matter.

  Formula (I)

(In the general formula (I), R ₁ is a hydrogen atom, an alkyl group, a hydroxy lower alkyl group, a cyclohexyl group, a mono- or dialkylaminoalkyl group, or a cyano lower alkyl group, and R ₂ , R ₃ , R ₄ , R ₅ and R ₆ are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a carboxyl group (provided that R ₂ , R ₃ , R ₄ , R ₅ and R ₆ are all hydrogen atoms) ).)

  The following exemplary compounds 1 to 7 are preferred exemplary compounds of the compound represented by the above general formula (I) or a salt thereof. Of course, the present invention is not limited to the following compounds.

  In the ink according to the present invention, the content (% by mass) of the compound represented by the general formula (I) or a salt thereof is preferably 0.1% by mass or more and 10.0% by mass or less. When the content is less than 0.1% by mass, sufficient image density and color developability may not be obtained. If the content exceeds 10.0% by mass, the image density becomes high, but good ink jet characteristics may not be obtained, for example, the fixing recovery property that is one of the effects of the present invention cannot be obtained. . In order to obtain a high image density, the content (% by mass) is preferably 3.0% by mass or more. To obtain a higher image density, the content (% by mass) is 4%. It is particularly preferably 5% by mass or more.

  In the ink of the present invention, in addition to the compound represented by the general formula (I) or a salt thereof, other color materials may be used in combination for the purpose of adjusting the color tone. However, when a colorant other than the compound represented by the general formula (I) or a salt thereof is used in combination, the compound represented by the general formula (I) or a salt thereof is sufficient to obtain the effects of the present invention. The content (% by mass) of the coloring material other than is preferably 0.1% by mass or more and 3.0% by mass or less, and more preferably 0.5% by mass or more and 3.0% by mass or less. preferable. Further, the content ratio of the color material is such that the content (mass%) of the compound represented by the general formula (I) or a salt thereof and the content (mass%) of other color materials are 1.0: 10. It is preferably 0.0 or more and 10.0: 1.0 or less.

[Color material verification method]
For the verification of the color material used in the present invention, the following verification methods (1) to (3) using high performance liquid chromatography (HPLC) can be applied.
(1) Peak retention time (2) Maximum absorption wavelength at peak of (1) (3) M / Z of mass spectrum at peak of (1) (posi, negative)
The analysis conditions of high performance liquid chromatography are as follows. An ink solution diluted about 1000 times with pure water is analyzed by high performance liquid chromatography under the following conditions, and a peak retention time and a maximum absorption wavelength of the peak are measured.
Column: Symmetry C18 2.1mm x 150mm
-Column temperature: 40 ° C
・ Flow rate: 0.2 ml / min
PDA: 210 nm to 700 nm
Mobile phase and gradient conditions: Table 1

The analysis conditions of the mass spectrum are as shown below. With respect to the obtained peak, a mass spectrum is measured under the following conditions, and the most strongly detected M / Z is measured for each of posi and negative.
・ Ionization method ・ ESI capillary voltage 3.5kV
Desolvent gas 300 ℃
Ion source temperature 120 ° C
・ Detector posi 40V 200-1500amu / 0.9sec
nega 40V 200-1500amu / 0.9sec
For example, Table 2 shows the retention time, maximum absorption wavelength, M / Z (posi), and M / Z (nega) values for the exemplified compound A described above. When it corresponds to the value shown in Table 2, it can be judged that it corresponds to the compound used in the present invention.

(Other color materials)
In the present invention, other colorants may be used in combination with the compound represented by the general formula (I) or a salt thereof.

  In order to form a full color image or the like, an ink having a color tone different from that of the ink of the present invention may be used in combination. For example, cyan ink, magenta ink, yellow ink, black ink, and the like. Also, light inks having the same color tone as these inks can be used in combination. The color material of the ink having the different color tone or the light ink may be a known dye or a newly synthesized color material.

  Below, the specific example of coloring materials other than the compound or salt represented with general formula (I) is given to the following. Of course, the present invention is not limited to this.

[Yellow color material]
C. I. Direct yellow: 8, 11, 12, 27, 28, 33, 39, 44, 50, 58, 85, 86, 87, 88, 89, 98, 100, 110, 132, 173, etc. I. Acid Yellow: 1, 3, 7, 11, 17, 23, 25, 29, 36, 38, 40, 42, 44, 76, 98, 99 etc. C.I. I. Pigment Yellow: 1, 2, 3, 12, 13, 14, 15, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 114, 128, 138, 180, etc.

[Magenta color material]
C. I. Direct Red: 2, 4, 9, 11, 20, 23, 24, 31, 39, 46, 62, 75, 79, 80, 83, 89, 95, 197, 201, 218, 220, 224, 225, 226 227, 228, 229, 230 etc. C.I. I. Acid Red: 6, 8, 9, 13, 14, 18, 26, 27, 32, 35, 42, 51, 52, 80, 83, 87, 89, 92, 106, 114, 115, 133, 134, 145 158, 198, 249, 265, 289, etc. C.I. I. Food Red: 87, 92, 94, etc. I. Direct violet: 107 grade C.I. I. Pigment Red: 2, 5, 7, 12, 48: 2, 48: 4, 57: 1, 112, 122, 123, 168, 184, 202, etc.

[Cyan color material]
C. I. Direct Blue: 1, 15, 22, 25, 41, 76, 77, 80, 86, 90, 98, 106, 108, 120, 158, 163, 168, 199, 226, 307, etc. C.I. I. Acid Blue: 1, 7, 9, 15, 22, 23, 25, 29, 40, 43, 59, 62, 74, 78, 80, 90, 100, 102, 104, 112, 117, 127, 138, 158 161, 203, 204, 221, 244, etc. I. Pigment Blue: 1, 2, 3, 15, 15: 2, 15: 3, 15: 4, 16, 22, 60, etc.

[Orange color material]
C. I. Acid Orange: 7, 8, 10, 12, 24, 33, 56, 67, 74, 88, 94, 116, 142, etc. C.I. I. Acid Red: 111, 114, 266, 374, etc. C.I. I. Direct orange: 26, 29, 34, 39, 57, 102, 118 etc. C.I. I. Food Orange: 3 etc. C.I. I. Reactive orange: 1, 4, 5, 7, 12, 13, 14, 15, 16, 20, 29, 30, 84, 107, etc. I. Disperse orange: 1, 3, 11, 13, 20, 25, 29, 30, 31, 32, 47, 55, 56 etc. C.I. I. Pigment orange: 43 mag C.I. I. Pigment Red: 122, 170, 177, 194, 209, 224, etc.

[Green color material]
C. I. Acid Green: 1, 3, 5, 6, 9, 12, 15, 16, 19, 21, 25, 28, 81, 84 etc. C.I. I. Direct green: 26, 59, 67 etc. I. Food Green: 3rd grade C.I. I. Reactive Green: 5, 6, 12, 19, 21 etc. C.I. I. Disperse Green: 6, 9 etc. C.I. I. Pigment Green: 7, 36 etc.

[Blue color material]
C. I. Acid Blue: 62, 80, 83, 90, 104, 112, 113, 142, 203, 204, 221, 244, etc. C.I. I. Reactive Blue: 49 etc. C.I. I. Acid Violet: 17, 19, 48, 49, 54, 129, etc. C.I. I. Direct violet: 9, 35, 47, 51, 66, 93, 95, 99 etc. C.I. I. Reactive violet: 1, 2, 4, 5, 6, 8, 9, 22, 34, 36 etc. C.I. I. Disperse violet: 1, 4, 8, 23, 26, 28, 31, 33, 35, 38, 48, 56 etc. C.I. I. Pigment Blue: 15: 6 etc. C.I. I. Pigment Violet: 19, 23, 37, etc.

[Black color material]
C. I. Direct black: 17, 19, 22, 31, 32, 51, 62, 71, 74, 112, 113, 154, 168, 195, etc. I. Acid Black: 2, 48, 51, 52, 110, 115, 156 etc. C.I. I. Food black: 1st, 2nd carbon black

(Glycerin)
The ink according to the present invention is characterized by containing glycerin, but is essential. This is because the adhesion recovery property can be improved by using a compound represented by the general formula (I) or a salt thereof and glycerin in combination. The mechanism for improving the fixing recovery property is that the compound represented by the general formula (I) has high solubility in glycerin, and since glycerin is non-volatile, even after volatile components are volatilized, This is presumably because the compound represented by the general formula (I) can be dissolved stably.

  In the ink according to the present invention, the glycerin content (% by mass) is more than 0.0% by mass and 4.0% by mass or less with respect to the total mass of the ink. The reason for this will be described later.

(Deterioration of the wetted surface of the heat generating part and the mechanism that causes the disconnection of the wiring to apply voltage to the heat generating part)
When ink is ejected by applying thermal energy to an ink containing the compound represented by the general formula (I) or a salt thereof and glycerin, a deterioration (dissolution) of the heat generating part of the recording head or a voltage is applied to the heat generating part. For this reason, a phenomenon of disconnection of the wiring occurs. Although the mechanism by which such a phenomenon occurs is not clearly understood, the present inventors presume as follows.

  It is considered that the deterioration (dissolution) of the heat generating part occurs due to the following mechanism. Hydroxide ions present in the ink are adsorbed on the liquid contact surface of the heat generating part containing at least one compound of metal and metal oxide. When a voltage is applied to the heat generating portion and the heat generating portion is heated, the hydroxide ions adsorbed on the heat generating portion wetted surface and the heat generating portion wetted surface react, and the heat generating portion wetted surface dissolves. It happens by doing (shaving).

For example, when an ink containing a normal dye is used as the coloring material, the amount of hydroxide ions present in the ink is small (for example, the amount of hydroxide ions present in the ink having a pH of 9.0). Is 1.0 × 10 ⁻⁵ mol / l), and the amount of hydroxide ions adsorbed on the liquid contact surface of the heat generating portion containing at least one compound of metal and metal oxide is small. For this reason, when ink is ejected, that is, when a voltage is applied to the heat generating portion and the heat generating portion is heated, the hydroxide ions and the surface contacting the heat generating portion hardly react. As a result, deterioration (dissolution) of the wetted surface of the heating part and disconnection of the wiring for applying a voltage to the heating part hardly occur.

On the other hand, when the ink containing the compound represented by the general formula (I) or a salt thereof is used as the coloring material, the compound represented by the general formula (I) or the salt thereof is buffered in the use area of the ink. Because of having a region, the amount of hydroxide ions present in the ink is larger than that of an ink containing a normal dye as a coloring material, and the heat generating part contact containing at least one compound of a metal and a metal oxide. The amount of hydroxide ions adsorbed on the liquid surface is also large. For this reason, when ink is discharged, that is, when a voltage is applied to the heat generating portion and the heat generating portion is heated, the hydroxide ions adsorbed on the heat generating portion wetted surface and the heat generating portion wetted surface react. The liquid contact surface of the heat generating part is dissolved. As a result, the hydroxide ion concentration of the ink decreases in the vicinity of the heat-generating part wetted surface. Here, the compound represented by the general formula (I) or a salt thereof is a color material having a buffer region within the ink use range, and has a substantially constant water amount with respect to a change in the hydroxide ion concentration of the ink. Since the function of maintaining the oxide ion concentration occurs, hydroxide ions are released (hydrogen ions are absorbed), and the hydroxide ion concentration of the ink increases. At this time, the amount of released hydroxide ions (absorbed hydroxide ions) varies depending on the pH of the ink at that time and the content of the compound represented by the general formula (I) or a salt thereof. Compared with the amount of hydroxide ions present in the initial ink (for example, the amount of hydroxide ions present in the ink having a pH of 9.0 is 1.0 × 10 ⁻⁵ mol / l). And more than a few digits. For this reason, more hydroxide ions are adsorbed on the wetted surface of the heat generating part.

  In this way, unlike the case where the color material of the ink is a normal dye, when the compound represented by the general formula (I) or a salt thereof is used, a very large amount of hydroxide ions are in contact with the heat generating part wetted surface. Adsorb to. When a voltage is applied to the heat generating portion and the heat generating portion is heated, a large amount of hydroxide ions adsorbed on the heat generating portion wetted surface, and the heat generating portion wetted surface reacts, and the heat generating portion wetted surface Dissolves (scraps) vigorously. Since the above reaction is repeated each time a voltage is applied to the heat generating portion and the heat generating portion is heated, in the case of an ink containing the compound represented by the general formula (I) or a salt thereof, the heat generating portion wetted surface Degradation (dissolution) and disconnection of the wiring for applying a voltage to the heat generating part occurs.

  In addition, when using the ink-jet ink of the present invention, there are many factors that change the pH of the ink. In the present invention, “having a buffer area within the ink use range” means that the ink is used when the ink is used. It means that the pH of the ink is in the range of the buffer region of the coloring material contained in the ink. Specifically, the factors that cause the pH to change include, for example, storage for a certain period under various environments, evaporation of volatile substances from the ink stored in the ink cartridge, etc. Is mentioned.

(Buffer area)
The buffer region in the present invention is a pH region where the solution maintains a substantially constant hydrogen ion concentration despite the addition or disappearance of a certain amount of acid or base. The titration of FIG. 1 shows the results of measuring the change in pH of the solution by adding acid or base to the solution, taking the amount of acid or base added on the horizontal axis, and the pH of the solution on the vertical axis. It is a curve. In FIG. 1, the buffer region is a region before and after a region where the pH change is small (with two inflection points of the titration curve as a boundary). For example, the buffer region of Exemplified Compound A ranges from A to B in FIG.

  In the present invention, “having a buffer region within the ink use range” means that the ink itself and the color material itself change during use of the ink as well as the initial pH after ink preparation. Therefore, the ink pH is also included in the buffer area afterward.

  FIG. 1 is an acid-base titration curve of Exemplified Compound A. In FIG. 1, the vertical axis represents the pH of the color material aqueous solution, and the horizontal axis represents the amount of acid or base added. On the horizontal axis, a number greater than 0 is the amount of sodium hydroxide aqueous solution added as a base, and a number smaller than 0 is the amount of nitric acid aqueous solution added as an acid.

  A specific example of the procedure for obtaining the titration curve of the color material aqueous solution is as follows. Two 50 ml of 10% by weight aqueous solutions of coloring materials are prepared and the initial pH is measured. Then, an acid is added to one side, a base is added to one side, and the pH of the coloring material aqueous solution is measured.

  The titration curve of Exemplified Compound A determined by the method described above is shown in FIG. From FIG. 1, it can be seen that pH of the buffer region of Exemplified Compound A is 7.3 or more and 10.5 or less.

(Ink pH)
When the pH of the ink is high, the proportion of the solubilizing groups that are ionized in the compound represented by the general formula (I) or a salt thereof increases. For this reason, the solubility of the compound represented by the general formula (I) or the salt thereof in the ink is increased, that is, it is difficult to precipitate, and as a result, the fixing recovery property is improved. Therefore, when the pH of the ink is high compared with the case where the pH of the ink is low, the glycerin content may be small. In the present invention, when the pH of the ink is 8.3 or more, if the glycerin content (% by mass) exceeds 0.0% by mass, excellent fixing recoverability can be obtained.

  Further, when the pH of the ink is low, the durability is good, and when the pH of the ink is high, the durability tends to deteriorate. The buffer region of exemplary compound A which is a compound represented by the general formula (I) or a salt thereof has a pH of 7.3 or more and 10.5 or less. That is, when the pH of the ink is 7.3 or more, the above-described mechanism is manifested, and the reaction between the exothermic part wetted surface containing at least one compound of metal and metal oxide and hydroxide ions is exemplified. Compound A begins to contribute. When the pH of the ink is 8.3 or more, the above-described mechanism is remarkably exhibited, and when the glycerin content (% by mass) exceeds 4.0% by mass with respect to the total mass of the ink, The durability is lowered, and further, when the content is 6.0% by mass or more, the durability is particularly remarkably lowered. However, in materials that make up members that come into contact with ink, such as ink cartridges and inkjet recording devices, depending on the type of the material, impurities may elute into the ink, preventing ink performance from degrading and materials from degrading. In view of this, it is preferable that the hydroxide ion concentration in the ink is low, that is, the pH of the ink is preferably lowered to some extent.

  From the above, in order to make the adhesion recovery and durability more excellent, the pH of the ink is 8.3 or more and the glycerin content (% by mass) is based on the total mass of the ink. Therefore, it is necessary to be more than 0.0% by mass and 4.0% by mass or less. Furthermore, the pH of the ink is 8.3 or more and pH 9.0 or less, and the glycerin content (% by mass) exceeds 0.0% by mass and is 4.0% by mass with respect to the total mass of the ink. The following is more preferable. In order to further improve the durability, the pH of the ink is preferably 10.0 or less, and more preferably, the pH of the ink is 9.5 or less. In order to further improve the fixing recovery property, the glycerin content (% by mass) is preferably 1.0% by mass or more based on the total mass of the ink. It is more preferably 0% by mass or more.

  In addition, the value of pH in this invention is a value which rounded off the second decimal place and made the significant figure of the decimal part one digit.

(Aqueous medium)
If the ink of the present invention satisfies the constitution of the present invention that the compound represented by the general formula (I) or a salt thereof and a specific amount of glycerin are satisfied, other water-soluble organic solvents contained in the ink include It does not specifically limit, As long as the effect of this invention is not impaired, the aqueous medium which is arbitrary water or the mixed solvent of water and various water-soluble organic solvents can be used.

  The water-soluble organic solvent is not particularly limited as long as it is water-soluble, and alcohol, polyhydric alcohol, polyglycol, glycol ether, nitrogen-containing polar solvent, and sulfur-containing polar solvent can be used. Specifically, for example, alkyl alcohols having 1 to 4 carbon atoms such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol; dimethylformamide, Amides such as dimethylacetamide; Ketones or ketoalcohols such as acetone and diacetone alcohol; Ethers such as tetrahydrofuran and dioxane; Polyalkylene glycols such as polyethylene glycol and polypropylene glycol; Ethylene glycol, propylene glycol, butylene glycol, tri 2-6 alkylene groups such as ethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol Alkylene glycols containing carbon atoms; lower alkyl ether acetates such as polyethylene glycol monomethyl ether acetate; multivalents such as ethylene glycol monomethyl (or ethyl) ether, diethylene glycol methyl (or ethyl) ether, triethylene glycol monomethyl (or ethyl) ether Lower alkyl ethers of alcohols; polyhydric alcohols such as trimethylolpropane and trimethylolethane; N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone and the like can be used. Of course, the present invention is not limited to these. The water-soluble organic solvent may be used alone or as a mixture.

  The content of these water-soluble organic solvents is preferably 5.0% by mass to 90.0% by mass, and more preferably 10.0% by mass to 50.0% by mass with respect to the total mass of the ink. When the content is less than this range, when used as an inkjet ink, there is a possibility that the reliability such as ejection properties may deteriorate. When the content is more than this range, the ink viscosity increases. This is because a supply failure may occur.

  Moreover, it is preferable to use deionized water (ion exchange water) as the water. The water content is preferably 10.0% by mass to 90.0% by mass with respect to the total mass of the ink.

(Other additives)
Furthermore, in the present invention, a surfactant, a pH adjuster, a rust inhibitor, an antiseptic, an antifungal agent, an antioxidant, an anti-reduction agent, an evaporation accelerator, a chelating agent, and a water-solubility, if necessary. Various additives such as a polymer may be contained.

<Recording medium>
As the recording medium used when forming an image using the ink of the present invention, any recording medium can be used as long as recording is performed by applying ink.

  The present invention is applied to a recording medium in which a color material such as a color material or a pigment is adsorbed to fine particles forming a porous structure in an ink receiving layer and an image is formed from at least the adsorbed fine particles. It is particularly suitable for use. Such an ink jet recording medium is preferably of a so-called absorption type in which ink is absorbed by a gap formed in an ink receiving layer on a support.

  The absorption type ink-receiving layer is constituted as a porous layer mainly composed of fine particles and containing a binder and other additives as required. Specific examples of the fine particles include inorganic pigments such as silica, clay, talc, calcium carbonate, kaolin, alumina or alumina hydrate, diatomaceous earth, titanium oxide, hydrotalcite, zinc oxide, urea formalin resin, ethylene resin. And organic pigments such as styrene resins, and one or more of these are used. Examples of suitable binders include water-soluble polymers and latex. For example, polyvinyl alcohol or a modified product thereof, starch or a modified product thereof, gelatin or a modified product thereof, gum arabic, carboxymethylcellulose, hydroxyethylcellulose, hydroxyprooylmethylcellulose and other cellulose derivatives, SBR latex, NBR latex, methylmethacrylate-butadiene Polymer latex, functional group-modified polymer latex, vinyl copolymer latex such as ethylene vinyl acetate copolymer, polyvinyl pyrrolidone, maleic anhydride or copolymer thereof, acrylate copolymer, etc. are used and necessary Depending on the situation, two or more kinds can be used in combination. In addition, additives can also be used. For example, a dispersant, a thickener, a pH adjuster, a lubricant, a fluidity modifier, a surfactant, an antifoaming agent, a mold release agent, a fluorescence enhancer, if necessary. Whitening agents, ultraviolet absorbers, antioxidants and the like are used.

In particular, the recording medium preferably used in the present invention is preferably a recording medium mainly composed of fine particles having an average particle diameter of 1 μm or less and having an ink receiving layer formed thereon. Particularly preferable examples of the fine particles include silica fine particles and aluminum oxide fine particles. A preferable silica fine particle is a silica fine particle typified by colloidal silica. Colloidal silica itself can be obtained from the market, and in particular, those described in, for example, Japanese Patent Nos. 2803134 and 2881847 are preferable. Preferred as the aluminum oxide fine particles are alumina hydrate fine particles and the like. One example of such alumina hydrate fine particles is an alumina hydrate represented by the following general formula.
AlO _3-n (OH) _2n · mH ₂ O
(In the above formula, n represents an integer of 1, 2 or 3, and m represents a value of 0 to 10, preferably 0 to 5. However, m and n are not 0 at the same time. MH _{Since 2} O often also represents a detachable aqueous phase that is not involved in the formation of the mH ₂ O crystal lattice, m can take an integer or non-integer value. M can reach a value of 0 when heated.)

  Alumina hydrate is obtained by hydrolysis of aluminum alkoxide, hydrolysis of sodium aluminate described in US Pat. No. 4,242,271 and US Pat. No. 4,202,870, or Japanese Patent Publication No. 57-44605. Can be produced by a known method such as a method of neutralizing by adding an aqueous solution of sodium sulfate, aluminum chloride or the like to an aqueous solution of sodium aluminate or the like described in 1.

  The recording medium preferably has a support for supporting the ink receiving layer. The support is not particularly limited as long as the ink receiving layer can be formed of the above-described porous fine particles and gives rigidity that can be transported by a transport mechanism such as an ink jet printer. Even things can be used. Specifically, for example, a paper support made mainly of natural cellulose fibers and made of pulp raw materials, a plastic support made of a material such as polyester (eg, polyethylene terephthalate), cellulose triacetate, polycarbonate, polyvinyl chloride, polypropylene, polyimide, etc. And a resin-coated paper (eg, RC paper) having a polyolefin resin-coated layer in which a white pigment or the like is added to at least one of the base papers.

<Ink set>
The ink of the present invention can be preferably used even when an ink set is combined with other inks. The ink set in the present invention is a state in which the ink of the present invention is used together with other inks such as cyan ink, magenta ink, yellow ink, and black ink. There is no particular limitation on other inks that can be combined as an ink set. In addition, the ink set in the present invention includes a case where a plurality of ink tanks are integrated, and includes a case where a plurality of individual ink tanks are used in combination. One thing is also included.

<Inkjet recording method>
The ink according to the present invention is particularly preferably used in an ink jet recording method having a step of ejecting ink by an ink jet method. Ink jet recording methods include a recording method in which mechanical energy is applied to ink and ink is ejected, and a recording method in which thermal energy is applied to ink and ink is ejected. In particular, in the present invention, an ink jet recording method using thermal energy can be preferably used.

<Ink cartridge>
Examples of the ink cartridge suitable for performing recording using the ink according to the present invention include an ink cartridge including an ink storage portion for storing these inks.

<Recording unit>
A recording unit suitable for performing recording using the ink according to the present invention includes a recording unit including an ink storage unit for storing these inks and a recording head. In particular, there is a recording unit in which the recording head causes thermal energy corresponding to a recording signal to act on the ink and generates ink droplets by the energy.

  The recording head in the present invention has a heat generating part wetted surface containing at least one of a metal and a metal oxide. Specific examples of the compound of at least one of the metal and the metal oxide include metals such as Ta, Zr, Ti, Ni, and Al, and oxides of these metals.

<Inkjet recording apparatus>
A recording apparatus suitable for performing recording using the ink according to the present invention applies thermal energy corresponding to a recording signal to ink in a recording head having an ink storage unit in which these inks are stored. An apparatus that generates ink droplets by energy is used.

  Below, the schematic structure of the mechanism part of an inkjet recording device is demonstrated. The recording apparatus main body is composed of a paper feed unit, a paper transport unit, a carriage unit, a paper discharge unit, a cleaning unit, and an exterior unit that protects these parts and has design properties from the role of each mechanism. The outline of these will be described below.

  FIG. 2 is a perspective view of the recording apparatus. 3 and 4 are diagrams for explaining the internal mechanism of the recording apparatus main body. FIG. 3 is a perspective view from the upper right part, and FIG. 4 is a side sectional view of the recording apparatus main body. is there.

  When paper feeding is performed in the recording apparatus, first, only a predetermined number of recording media are sent to a nip portion including a paper feed roller M2080 and a separation roller M2041 in a paper feed unit including a paper feed tray M2060. The sent recording medium is separated at the nip portion, and only the uppermost recording medium is conveyed. The recording medium sent to the paper transport unit is guided by the pinch roller holder M3000 and the paper guide flapper M3030, and is sent to the roller pair of the transport roller M3060 and the pinch roller M3070. A roller pair composed of a conveyance roller M3060 and a pinch roller M3070 is rotated by driving of the LF motor E0002, and the recording medium is conveyed on the platen M3040 by this rotation.

  When an image is formed on the recording medium in the carriage unit, the recording head H1001 (FIG. 5) is disposed at a target image forming position, and ink is ejected onto the recording medium in accordance with a signal from the electric substrate E0014. Although the detailed configuration of the recording head H1001 will be described later, a recording main scan in which the carriage M4000 scans in the column direction while recording by the recording head H1001, and a sub-scan in which the recording medium is conveyed in the row direction by the conveyance roller M3060. By alternately repeating the above, an image is formed on the recording medium.

  The recording medium on which the image is finally formed is sandwiched by the nip between the first paper discharge roller M3110 and the spur M3120 at the paper discharge unit, conveyed, and discharged to the paper discharge tray M3160.

  For the purpose of cleaning the recording head H1001 before and after image recording in the cleaning unit, if the pump M5000 is operated in a state where the cap M5010 is in close contact with the ink discharge port of the recording head H1001, it is unnecessary from the recording head H1001. Ink or the like is sucked. Further, by sucking the ink remaining in the cap M5010 with the cap M5010 opened, consideration is given to preventing the remaining ink from adhering and the subsequent adverse effects.

(Recording head configuration)
The configuration of the head cartridge H1000 will be described. The head cartridge H1000 has a recording head H1001, means for mounting the ink tank H1900, and means for supplying ink from the ink tank H1900 to the recording head, and is detachably mounted on the carriage M4000. .

  FIG. 5 is a diagram showing how the ink tank H1900 is mounted on the head cartridge H1000. The recording apparatus forms an image with yellow, magenta, cyan, black, light magenta, light cyan, and green ink, and therefore, ink tank H1900 is also prepared for seven colors independently. In the above, the ink according to the present invention is used as at least one kind of ink. As shown in the figure, each is detachable from the head cartridge H1000. The ink tank H1900 can be attached and detached while the head cartridge H1000 is mounted on the carriage M4000.

  FIG. 6 is an exploded perspective view of the head cartridge H1000. In the figure, a head cartridge H1000 includes a first recording element substrate H1100 and a second recording element substrate H1101, a first plate H1200, a second plate H1400, an electric wiring substrate H1300, a tank holder H1500, and a flow path forming member H1600. , Filter H1700, seal rubber H1800, and the like.

  The first recording element substrate H1100 and the second recording element substrate H1101 are Si substrates, and a plurality of recording elements (nozzles) for ejecting ink are formed on one side thereof by a photolithography technique. Electric wiring such as Al for supplying electric power to each recording element is formed by a film forming technique, and a plurality of ink flow paths corresponding to individual recording elements are also formed by a photolithography technique. Further, an ink supply port for supplying ink to the plurality of ink flow paths is formed to open on the back surface.

  FIG. 7 is an enlarged front view for explaining the configuration of the first recording element substrate H1100 and the second recording element substrate H1101. H2000 to H2600 are printing element rows (hereinafter also referred to as nozzle rows) corresponding to different ink colors, and the first printing element substrate H1100 has a nozzle row H2000 supplied with yellow ink and a supply of magenta ink. The nozzle row for three colors is configured, that is, the nozzle row H2100 to be supplied and the nozzle row H2200 to which cyan ink is supplied. The second recording element substrate H1101 includes a nozzle row H2300 supplied with light cyan ink, a nozzle row H2400 supplied with black ink, a nozzle row H2500 supplied with orange ink, and a nozzle supplied with light magenta ink. Nozzle rows for four colors of the row H2600 are configured.

Each nozzle row is composed of 768 nozzles arranged at an interval of 1200 dpi (dot / inch; reference value) in the conveyance direction of the recording medium, and ejects approximately 2 picoliters of ink droplets. The opening area at each nozzle outlet is set to approximately 100 square μm ² . Further, the first recording element substrate H1100 and the second recording element substrate H1101 are bonded and fixed to the first plate H1200. Here, the first recording element substrate H1100 and the second recording element substrate H1101 are attached. An ink supply port H1201 for supplying ink is formed.

  Further, a second plate H1400 having an opening is bonded and fixed to the first plate H1200. The second plate H1400 is composed of an electric wiring substrate H1300, a first recording element substrate H1100, and a second recording element substrate H1100. The electric wiring substrate H1300 is held so that the recording element substrate H1101 is electrically connected.

  The electrical wiring substrate H1300 applies an electrical signal for ejecting ink from each nozzle formed on the first recording element substrate H1100 and the second recording element substrate H1101, and the first recording element substrate Electrical wiring corresponding to the H1100 and the second recording element substrate H1101, and an external signal input terminal H1301 for receiving an electrical signal from the recording apparatus main body located at the end of the electrical wiring. The external signal input terminal H1301 is positioned and fixed on the back side of the tank holder H1500.

  On the other hand, in a tank holder H1500 that holds the ink tank H1900, a flow path forming member H1600 is fixed by, for example, ultrasonic welding to form an ink flow path H1501 that communicates from the ink tank H1900 to the first plate H1200.

  A filter H1700 is provided at the ink tank side end of the ink flow path H1501 that engages with the ink tank H1900, and can prevent dust from entering from the outside. Further, a seal rubber H1800 is attached to the engaging portion with the ink tank H1900 so that ink can be prevented from evaporating from the engaging portion.

  Further, as described above, the tank holder portion composed of the tank holder H1500, the flow path forming member H1600, the filter H1700, and the seal rubber H1800, the first recording element substrate H1100, the second recording element substrate H1101, and the first plate. The head cartridge H1000 is configured by bonding the recording head unit H1001 including the H1200, the electric wiring substrate H1300, and the second plate H1400 by bonding or the like.

  Here, as an embodiment of the recording head, a bubble jet (registration) that performs recording using an electrothermal transducer (recording element) that generates thermal energy for causing film boiling to the ink in response to an electrical signal. A trademark type recording head has been described with an example.

  About this typical structure and principle, for example, what is performed using the basic principle disclosed in US Pat. Nos. 4,723,129 and 4,740,796 is preferable. . This method can be applied to both the so-called on-demand type and the continuous type. In particular, in the case of the on-demand type, it corresponds to a sheet or liquid flow path in which liquid (ink) is held. By applying at least one drive signal that corresponds to the recorded information and gives a rapid temperature rise exceeding the nucleate boiling to the electrothermal transducer arranged in a manner, heat energy is generated in the electrothermal transducer, This is effective because film boiling occurs on the heat acting surface of the recording head, and as a result, bubbles in the liquid (ink) corresponding to the drive signal on a one-to-one basis can be formed. By the growth and contraction of the bubbles, liquid (ink) is ejected through the ejection opening to form at least one droplet. It is more preferable that the drive signal has a pulse shape because bubbles can be grown and contracted immediately and appropriately, and liquid (ink) discharge with particularly excellent responsiveness can be achieved.

  Further, as a form of the ink jet recording apparatus using the second mechanical energy, a nozzle forming substrate having a plurality of nozzles, a pressure generating element made of a piezoelectric material and a conductive material disposed opposite to the nozzles, and this pressure An on-demand ink jet recording head that includes ink that fills the periphery of the generating element, displaces the pressure generating element by an applied voltage, and discharges a small droplet of ink from a nozzle can be exemplified.

  Further, the ink jet recording apparatus is not limited to the one in which the head and the ink tank are separated as described above, and may be one in which they are integrated so as not to be separated. The ink tank is integrated with the head in a separable or non-separable manner and mounted on the carriage, and is provided at a fixed portion of the apparatus to supply ink to the recording head via an ink supply member, for example, a tube. It may be in the form of Further, when the ink tank is provided with a configuration for applying a preferable negative pressure to the recording head, a configuration in which an absorber is disposed in the ink storage portion of the ink tank, or a flexible ink storage bag and the same A form having a spring portion that applies a biasing force in the direction of expanding the internal volume can be employed. In addition to the serial recording method as described above, the recording apparatus may take the form of a line printer in which recording elements are aligned over a range corresponding to the entire width of the recording medium.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail using an Example and a reference example, this invention is not limited at all by the following Example, unless the summary is exceeded. Unless otherwise specified, the ink components in Examples and Comparative Examples mean “parts by mass”.

<Preparation of coloring material>
In xylene, the compound represented by the following compound (1), sodium carbonate, and ethyl benzoyl acetate were reacted, and the reaction product was filtered and washed. This was reacted in N, N-dimethylformamide by sequentially adding metaaminoacetanilide, copper acetate, and sodium carbonate, and the reaction product was filtered and washed. Further, after sulfonation in fuming sulfuric acid, filtration and washing were performed, and this was subjected to a condensation reaction with cyanuric chloride in the presence of sodium hydroxide. Anthranilic acid was added to the reaction solution, and a condensation reaction was performed in the presence of sodium hydroxide. This was filtered and washed to obtain the following exemplary compound A.

  Compound (1)

  Exemplary Compound A

<Preparation of ink>
After mixing each component shown in the following Table 3 and stirring sufficiently, pressure filtration was performed with a filter having a pore size of 0.2 μm to prepare inks of Examples 1 to 6 and Comparative Examples 1 to 3.

<Evaluation>
(1) Durability Using the modified ink machine of the ink jet recording apparatus (trade name: BJ F890; manufactured by Canon Inc.) that discharges ink droplets by applying thermal energy to the ink obtained above, the ink 3 The durability was evaluated by discharging 0.0 × 10 ⁸ shots. The same evaluation was performed at the time when 1.5 × 10 ⁸ inks were ejected. The evaluation criteria for durability are as follows. The evaluation results are shown in Table 4.

A: Discharge up to 3.0 × 10 ⁸ shots.
B: Discharge up to 1.5 × 10 ⁸ shots, but not up to 3.0 × 10 ⁸ shots.
C: Cannot eject up to 1.5 × 10 ⁸ shots.

(2) Fixing recovery property The ink obtained above was filled in a recording head of a modified machine of an ink jet recording apparatus (trade name: BJ F890; manufactured by Canon) that applies ink energy to eject ink droplets. Thereafter, the recording head portion was removed and the discharge port was exposed, and the recording head portion was left in an environment of a temperature of 35 ° C. and a humidity of 10% for one week. Thereafter, the recording head portion was mounted again on the ink jet recording apparatus, and suction was performed to evaluate the fixing recovery property. The evaluation criteria for fixing recovery are as follows. The evaluation results are shown in Table 4.
A: After the recording head is mounted, all the nozzles are recovered so that they can be discharged without any problem within two suctions.
B: There are nozzles that cannot be ejected even if suction is performed three times after the recording head is mounted.

  From Comparative Examples 1 to 3, it can be seen that when the ink does not contain glycerin, the fixing recovery property is deteriorated, and when the glycerin content (% by mass) exceeds 4.0% by mass, the durability is deteriorated. Also, from Examples 1 and 2, when the glycerin content (% by mass) is more than 0.0% by mass and within 4.0% by mass, both fixing recovery and durability are excellent. I understand. Further, from Examples 1, 3 and 4, it can be seen that when the pH of the ink is 10.0 or less, more preferably 9.5 or less, it is superior to the durability.

2 is a titration curve of exemplary compound A. It is a perspective view of a recording device. FIG. 6 is a perspective view of a mechanism unit of the recording apparatus. It is sectional drawing of a recording device. FIG. 5 is a perspective view illustrating a state where an ink tank is attached to the head cartridge. It is a disassembled perspective view of a head cartridge. FIG. 6 is a front view showing a recording element substrate in the head cartridge.

Explanation of symbols

M2041 Separation roller M2060 Paper feed tray M2080 Paper feed roller M3000 Pinch roller holder M3030 Paper guide flapper M3040 Platen M3060 Transport roller M3070 Pinch roller M3110 Paper discharge roller M3120 Spur M3160 Paper discharge tray M4000F Carriage M5000 Pump M500P Head cartridge H1001 Recording head H1100 First recording element substrate H1101 Second recording element substrate H1200 First plate H1201 Ink supply port H1300 Electrical wiring substrate H1301 External signal input terminal H1400 Second plate H1500 Tank holder H1501 Ink channel H1600 Flow path forming member H1700 Luther H1800 seal rubber H1900 ink tank H2000 yellow nozzle row H2100 magenta nozzle row H2200 cyan nozzle row H2300 light cyan nozzle row H2400 black nozzle row H2500 green nozzle row H2600 light magenta nozzle row

Claims (11)

An inkjet ink for use in an inkjet recording apparatus comprising a recording head having a heat generating part wetted surface containing at least one compound of a metal and a metal oxide,
A compound represented by the following general formula (I) or a salt thereof, glycerin as a colorant,
The glycerin content (% by mass) is more than 0.0% by mass and 4.0% by mass or less based on the total mass of the ink-jet ink.
An inkjet ink having a pH of 8.3 or more.
Formula (I)

(In the general formula (I), R ₁ is a hydrogen atom, an alkyl group, a hydroxy lower alkyl group, a cyclohexyl group, a mono- or dialkylaminoalkyl group, or a cyano lower alkyl group, and R ₂ , R ₃ , R ₄ , R ₅ and R ₆ are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a carboxyl group (provided that R ₂ , R ₃ , R ₄ , R ₅ and R ₆ are all hydrogen atoms) ).)   2. The inkjet ink according to claim 1, wherein the glycerin content (% by mass) is 2.0% by mass or more and 4.0% by mass or less based on the total mass of the inkjet ink.   The inkjet ink according to claim 1 or 2, wherein the pH of the ink is 10.0 or less.   The inkjet ink according to any one of claims 1 to 3, wherein the pH of the ink is 9.5 or less.   The content (% by mass) of the compound represented by the general formula (I) or a salt thereof is 0.1% by mass or more and 10.0% by mass or less with respect to the total mass of the inkjet ink. The inkjet ink according to any one of the above.   An ink for ink set used together with at least one of black ink, cyan ink, and yellow ink, wherein the ink is the ink for ink jet according to any one of claims 1 to 5. For ink.   An ink set comprising a plurality of inks, wherein the ink set includes the inkjet ink according to any one of claims 1 to 6 as magenta ink.   The inkjet recording method which has the process of discharging an ink with an inkjet method, The said ink is the inkjet ink of any one of Claims 1-6, The inkjet recording method characterized by the above-mentioned.   An ink cartridge comprising an ink container for containing ink, wherein the ink is the ink jet ink according to any one of claims 1 to 6.   A recording unit including an ink storage portion that stores ink and a recording head for ejecting ink, wherein the ink is the inkjet ink according to any one of claims 1 to 6. And recording unit. An ink jet recording apparatus comprising an ink containing portion for containing ink and a recording head for ejecting ink, wherein the ink is the ink for ink jet according to any one of claims 1 to 6. An ink jet recording apparatus.

Images