JP4713850B2 - Ink for inkjet recording - Google Patents

Description

  The present invention relates to an inkjet recording ink suitable for inkjet recording.

2. Description of the Related Art Conventionally, inks that are used for ink jet recording are well known that contain a dye as a coloring material, a humectant, and water. However, when an image is formed on a recording medium such as recording paper with the ink containing the dye, the water resistance of the image becomes a problem. In particular, plain paper (a wide range of commercially available paper, especially paper used in electrophotographic copying machines, which is not intended to have the optimum structure, composition, characteristics, etc. for inkjet recording) When recording on paper, the water resistance becomes very poor.
In order to improve the water resistance in printing on these plain papers, for example, Patent Document 1 and Patent Document 2 describe that a polyamine is contained in an aqueous ink composition. However, in such an ink, since the hydrophilic base of the dye is salted, the solubility of the dye is lowered, reliability is reduced such as nozzle clogging, and bronzing (dye association) on the printed matter. May cause uneven printing or density may not occur.
Patent Document 3 discloses that when a dye has a carboxyl group and further has an ammonium salt group or a volatile substituted ammonium salt group, ammonia or amine is volatilized on the recording material, and the carboxyl group is It describes that water resistance is improved by becoming a free acid. However, even in this case, even if the initial solubility of the dye is good, the solubility of the dye is lowered by the volatilization of ammonia or amine from the ink gradually, and the nozzle clogging prevention property and the ink are reduced. It often causes a decrease in stability.
Therefore, for example, as shown in Patent Document 4, Patent Document 5, Patent Document 6, and Patent Document 7, a hydrolyzable silane compound containing a nitrogen atom-containing organic group or a partial hydrolyzate thereof and hydrolyzable. It describes that the water resistance of an image on a recording medium is improved by including an organosilicon compound purified by hydrolyzing a silane compound or a partial hydrolyzate thereof. In this proposal, when the ink droplet adheres to the recording medium and the water in the ink droplet evaporates or penetrates into the recording medium, the organosilicon compound undergoes a condensation polymerization reaction. Since the organosilicon compound surrounds the dye, even if the image on the recording medium gets wet with water, the dye does not bleed into the water and the water resistance of the image is improved.

JP-A-2-296878 JP-A-2-255576 JP-A-3-91577 Japanese Patent Laid-Open No. 10-212439 JP-A-11-293167 Japanese Patent Laid-Open No. 11-315231 JP 2002-265829 A

The ink using the organosilicon compound as a substance that initiates the condensation polymerization reaction as water evaporates as proposed in the conventional example has a problem that the black ink is decolored when stored for a long period of time. In the case of an ink using an azo black dye, the decoloring was large. The mechanism of this decoloration is not clear, but if left unattended for a long time, it is assumed that the organosilicon compound attacks the azo bond of the azo black dye in the ink and the azo dye is reduced and decolored. ing.
It is an object of the present invention to provide a black ink that has almost no color erasure even when left for a long period of time and has excellent water resistance for images printed on plain paper.

In order to achieve the above object, inks were prepared by combining various types of black dyes and organosilicon compounds and tested for decoloring properties after long-term storage. The inventors have found that there is little decolorization and excellent water resistance, and have reached the present invention.
A first aspect of the present invention is for ink-jet recording comprising a coloring material comprising a chelate azo dye , a humectant, water, and a water- soluble organosilicon compound that starts a condensation polymerization reaction as the water evaporates. An ink, wherein the chelate azo dye is C.I. I. Acid Black 194 and / or C.I. I. The present invention relates to an ink for ink jet recording characterized by being reactive black 31 .
The second aspect of the present invention is characterized in that the ink for inkjet recording further contains a condensation polymerization accelerator for accelerating the condensation polymerization reaction of a water-soluble organosilicon compound that initiates the condensation polymerization reaction. Ink jet recording ink.
A third aspect of the present invention relates to the ink for ink jet recording according to claim 2 , wherein the condensation polymerization reaction accelerator is an inorganic or organic ammonium salt .
A fourth aspect of the present invention relates to the ink for ink jet recording according to claim 3 , wherein the ammonium salt is a salt of a weak acid .
A fifth aspect of the present invention relates to the ink for ink jet recording according to claim 3 , wherein the ammonium salt is a salt of a strong acid .

The present invention has found that by using a chelate-based azo dye as a coloring material, decoloring hardly occurs even after long-term storage, and an ink having excellent water resistance can be obtained, and the present invention has been completed. It was. As described above, it is speculated that the organosilicon compound attacks the azo bond of the black dye to cause decoloration, but it is less susceptible to attack by chelating the azo bond with a polyvalent metal. I guessed it.
Specific examples of chelate azo dyes include C.I. I. Direct Black 71, C.I. I. Acid Black 58, 60, 62, 64, 107, 108, 112, 115, 118, 119, 121, 122, 131, 132, 139, 140, 155, 156, 194, C.I. I. Reactive black 1, 8, 9, 31 and the like are available, and as black dyes used in the ink for ink jet recording of the present invention, C.I. I. Acid Black 194 and / or C.I. I. Reactive black 31 is preferable.

  The content of the color material in the recording liquid composition is preferably 0.5 to 15% by weight percentage, more preferably 1 to 10%, based on the whole ink. When the content is 0.5% or less, the printed image density is low, and when the content is 15% or more, the dye solubility is close to the upper limit, and nozzle clogging is likely to occur.

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic perspective view showing an ink jet recording apparatus using an ink for ink jet recording according to an embodiment of the present invention.
FIG. 2 is a partial bottom view of the ink jet head of the ink jet recording apparatus.
3 is a cross-sectional view taken along the line II of FIG.
4 is a cross-sectional view taken along line II-II in FIG.

  The ink jet recording apparatus A includes an ink jet head 3 that is mounted with an ink cartridge 1 having ink jet recording ink on its upper surface and that discharges the ink onto a recording paper 2 as a recording medium as will be described later. The inkjet head 3 is supported and fixed to a carriage 4. The carriage 4 is provided with a carriage motor (not shown). The carriage motor moves the inkjet head 3 and the carriage 4 in the main scanning direction (see FIGS. 1 and 2). It is guided by a carriage shaft 5 extending in the X direction shown in the figure, and reciprocates in that direction. The carriage 4, the carriage shaft 5 and the carriage motor constitute relative moving means for relatively moving the inkjet head 3 and the recording paper 2 in the main scanning direction.

The recording paper 2 is sandwiched between two conveyance rollers 6 that are rotationally driven by a conveyance motor (not shown), and is perpendicular to the main scanning direction below the inkjet head 3 by the conveyance motor and each conveyance roller 6. It is conveyed in the sub-scanning direction (Y direction shown in FIGS. 1 and 2). This conveyance motor and each conveyance roller 6
Thus, a relative moving means for relatively moving the inkjet head 3 and the recording paper 2 in the sub-scanning direction is configured.

  As shown in FIGS. 2 to 4, the inkjet head 3 has a head body 8 in which a plurality of pressure chamber recesses 7 having a supply port 7 a for supplying ink and a discharge port 7 b for discharging ink are formed. It has. The recesses 7 of the head main body 8 are opened on the upper surface of the head main body 8 so as to extend in the main scanning direction, and are arranged side by side at substantially equal intervals in the sub-scanning direction. The total length of each recess 7 opening is set to about 1250 μm and the width is set to about 130 μm. Note that both end portions of the opening of each recess 7 have a substantially semicircular shape.

The side wall portion of each recess 7 of the head body 8 is composed of a pressure chamber part 9 made of photosensitive glass having a thickness of about 200 μm, and the bottom wall part of each recess 7 is bonded and fixed to the lower surface of the pressure chamber part 9. And it is comprised by the ink flow path component 10 formed by laminating | stacking six stainless steel thin plates. In the ink flow path component 10, a plurality of orifices 11 connected to the supply ports 7 a of the recesses 7, and one supply ink flow path 12 connected to the orifices 11 and extending in the sub-scanning direction. And a plurality of ejection ink flow paths 13 respectively connected to the ejection ports 7b.
Each orifice 11 is formed in the second stainless steel thin plate having the smaller thickness than the others in the ink flow path component 10, and the diameter thereof is set to about 38 μm. Further, the supply ink flow path 12 is connected to the ink cartridge 1, and ink is supplied from the ink cartridge 1 into the supply ink flow path 12.

  A stainless steel nozzle plate 15 having a plurality of nozzles 14 for discharging ink droplets toward the recording paper 2 is bonded and fixed to the lower surface of the ink flow path component 10. The lower surface of the nozzle plate 15 is covered with a water repellent film 15a. Each nozzle 14 is connected to a discharge ink flow path 13 and communicates with the discharge port 7 b of each recess 7 via the discharge ink flow path 13. They are arranged in a row in the scanning direction. Each nozzle 14 includes a tapered portion in which the nozzle diameter decreases toward the nozzle tip side, and a straight portion provided on the nozzle tip side of the taper portion, and the nozzle diameter of the straight portion is set to about 20 μm. Has been.

Piezoelectric actuators 16 are respectively provided above the concave portions 7 of the head body 8. Each piezoelectric actuator 16 has a Cr vibration plate 18 that closes each recess 7 of the head body 8 while being bonded and fixed to the upper surface of the head body 8 and constitutes a pressure chamber 17 together with the recess 7. Yes. The diaphragm 18 is made of a single material common to all the piezoelectric actuators 16 and also serves as a common electrode common to all the piezoelectric elements 19 described later.
In addition, each piezoelectric actuator 16 is provided on a portion corresponding to the pressure chamber 17 on the side surface (upper surface) opposite to the pressure chamber 17 of the vibration plate 18 (a portion facing the opening of the recess 7) via a Cu intermediate layer 20. And a piezoelectric element 19 made of lead zirconate titanate (PZT) and bonded to a side surface (upper surface) opposite to the vibration plate 18 of each piezoelectric element 19, and a voltage ( And a Pt individual electrode 21 for applying a driving voltage).
The diaphragm 18, each piezoelectric element 19, each individual electrode 21 and each intermediate layer 20 are all formed of a thin film. The thickness of the diaphragm 18 is about 6 μm, and the thickness of each piezoelectric element 19 is 8 μm or less ( For example, the thickness of each individual electrode 21 is set to about 0.2 μm, and the thickness of each intermediate layer 20 is set to about 3 μm.

Each piezoelectric actuator 16 deforms a portion corresponding to the pressure chamber 17 of the diaphragm 18 by applying a driving voltage to each piezoelectric element 19 through the diaphragm 18 or each intermediate layer 20 and each individual electrode 21. By doing so, the ink in the pressure chamber 17 is ejected from the ejection port 7 b or the nozzle 14. That is, when a pulse voltage is applied between the diaphragm 18 and the individual electrode 21, the piezoelectric element 19 contracts in the width direction perpendicular to the thickness direction due to the piezoelectric effect due to the rise of the pulse voltage, whereas the vibration occurs. Since the plate 18, the individual electrode 21, and the intermediate layer 20 do not contract, a portion corresponding to the pressure chamber 17 of the diaphragm 18 is bent and deformed in a convex shape toward the pressure chamber 17 due to a so-called bimetal effect. Due to this bending deformation, a pressure is generated in the pressure chamber 17, and the ink in the pressure chamber 17 is pushed out from the nozzle 14 via the discharge port 7 b and the discharge ink flow path 13 by this pressure. Then, the piezoelectric element 19 expands due to the fall of the pulse voltage, and the portion corresponding to the pressure chamber 17 of the diaphragm 18 returns to the original state. At this time, the ink pushed out from the nozzle 14 is the ink flow path 13. The ink is torn off from the ink and discharged onto the recording paper 2 as ink droplets (for example, 3 pl), and adheres to the surface of the recording paper 2 in the form of dots. In addition, when the vibration plate 18 is bent and deformed to return to the original state, ink is supplied from the ink cartridge 1 to the pressure chamber 17 through the supply ink flow path 12 and the supply port 7a. Filled.
The pulse voltage applied to each piezoelectric element 19 is not a push-pull type as described above, but after falling from the first voltage to the second voltage lower than the first voltage. It may be of a pulling type that rises to the first voltage.

The drive voltage is applied to each piezoelectric element 19 when the inkjet head 3 and the carriage 4 are moved from one end of the recording paper 2 to the other end at a substantially constant speed in the main scanning direction (for example, about 50 μs: drive). (However, no voltage is applied when the ink jet head 3 reaches a position where ink droplets do not land on the recording paper 2), and this causes ink droplets to land at a predetermined position on the recording paper 2. . When the recording for one scan is completed, the recording paper 2 is transported by a predetermined amount in the sub-scanning direction by the transport motor and each transport roller 6, and the ink droplets are again moved while moving the inkjet head 3 and the carriage 4 in the main scanning direction again. Is discharged, and a new one-scan recording is performed. By repeating this operation, a desired image is formed on the entire recording paper 2.
The ink used in the ink jet recording apparatus A is composed of a coloring material, a humectant that suppresses drying at the nozzle 14 of the ink jet head 3 and the like, water, and a water-soluble substance (water) that undergoes a condensation polymerization reaction as the water evaporates. And an organosilicon compound as a water-soluble substance that undergoes a condensation polymerization reaction in the absence of water.

The organosilicon compound is used when ink droplets ejected from the nozzles 14 of the inkjet head 3 adhere to the recording paper 2 and water (solvent) in the ink droplets evaporates or penetrates into the recording paper 2. By performing a condensation polymerization reaction and surrounding the color material at this time, even if the image on the recording paper 2 gets wet with water, the color material is prevented from oozing into the water and the water resistance of the image is improved. Hydrolytic reaction product of an alkoxysilane containing an organic group having an amino group and an alkoxysilane not containing an amino group, or an organic monoepoxy compound to a hydrolyzable silane containing an amino group It is desirable to be an organosilicon compound obtained by hydrolyzing a hydrolyzable silane that has been reacted with hydrolyzable silane that does not contain a nitrogen atom.
The content of the organosilicon compound is 0.1 to 15%, preferably 1.0 to 10%, by weight, based on the entire inkjet recording ink. If it is less than 0.1%, the effect of water resistance is not observed. Conversely, if it is added in excess of 15%, the ink viscosity increases.

Moreover, it is preferable to contain the polycondensation reaction accelerator for accelerating the polycondensation reaction of an organosilicon compound.
By containing the polycondensation reaction accelerator, after the ink is deposited on the recording medium (for example, paper), the polycondensation reaction of the organosilicon compound is rapidly performed by the action of the polycondensation reaction accelerator. Enclose (dye or pigment) securely. Thus, even if this image gets wet with water immediately after the image is formed on the recording medium, the color material does not ooze into the water because it is surrounded by the water-soluble substance subjected to the condensation polymerization reaction. Therefore, the water resistance of the image is dramatically improved.
The content of the polycondensation reaction accelerator is 0.1 to 15%, preferably 1.0 to 10% by weight with respect to the entire inkjet recording ink. If it is less than 0.1%, the effect of promoting the condensation polymerization reaction is not seen. Conversely, if it is added in excess of 15%, the dissolution stability of the dye or the dispersion stability of the pigment is adversely affected.
The condensation polymerization accelerator is preferably an inorganic or organic ammonium salt. As used herein, the ammonium salt includes ammonium ion NH ₄ ⁺ and its hydrogen substituted with various substituents R (R: alkyl, aryl, etc.). By doing so, the ammonium salt is dissociated on the recording medium to release ammonia or amine, and the condensation reaction of the water-soluble substance is promoted by the action of the remaining inorganic or organic acid.
The ammonium salt is preferably a weak acid ammonium salt. As a result of studying ammonium salts of various acids, it has been clarified that ammonium salts of weak acids have a great effect of improving water resistance.
The ammonium salt is preferably a strong acid ammonium salt. As a result of studying ammonium salts of various acids, it has been clarified that ammonium salts of strong acids have a large effect of stably reducing the pH of the ink.

Examples of inorganic weak acid ammonium salts include, for example, monoammonium dihydrogen phosphate, diammonium hydrogen phosphate, triammonium phosphate, ammonium diphosphite, ammonium carbonate, ammonium bicarbonate, ammonium sulfide, ammonium borate, borofluoride Ammonium etc. are mentioned.
Examples of organic weak acid ammonium salts include, for example, ammonium acetate, diammonium oxalate, ammonium hydrogen oxalate, ammonium benzoate, monoammonium citrate, diammonium citrate, triammonium citrate, ammonium lactate, ammonium phthalate, succinate Ammonium acid, monoammonium tartrate, diammonium tartrate and the like.
Examples of inorganic strong acid ammonium salts include ammonium chloride, ammonium sulfate, ammonium hydrogen sulfate, ammonium sulfite, ammonium thiosulfate, ammonium nitrate, ammonium bromide, ammonium fluoride, and ammonium iodide.
Examples of strong organic acid ammonium salts include ammonium formate, ammonium monofluoroacetate, ammonium trifluoroacetate, ammonium trichloroacetate and the like.

  The humectant is ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, polyethylene glycol, polypropylene glycol, 1,5-pentanediol, 1,6-hexanediol, 1,2,6. -Hexanetriol, 1,2,4-butanetriol, 1,2,3-butanetriol, polyhydric alcohols such as petriol and glycerin, 2-pyrrolidone and N-methyl-2-pyrrolidone, 1,3- A water-soluble nitrogen heterocyclic compound such as dimethylimidazolidinone is desirable. The content of the humectant in the recording liquid composition is preferably 5 to 50% by weight percentage, more preferably 10 to 40%, with respect to the whole ink.

The ink for inkjet recording preferably further contains a penetrant. By doing so, the ink solvent composed of the humectant, the penetrating agent, and the water quickly penetrates into the recording medium after the ink is deposited on the recording medium (for example, paper). Thereby, the polycondensation reaction of the water-soluble substance is promptly performed to reliably surround the color material (dye or pigment). As a result, the water resistance of the image is further improved.
Specific examples of this penetrant include diethylene glycol monophenyl ether, ethylene glycol monophenyl ether, ethylene glycol butyl ether, ethylene glycol monoallyl ether, diethylene glycol monophenyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monobutyl ether, A monoalkyl ether of a polyhydric alcohol such as propylene glycol monobutyl ether is preferred.
The content is 0.1 to 30%, preferably 1.0 to 10% by weight percentage with respect to the whole ink. If the content is less than 0.1%, the effect of penetrating the ink into the recording paper 2 cannot be obtained without the surface tension of the ink at 25 ° C. being 50 mN / m or less as described later, while 30% This is because the solubility of the coloring material and the organosilicon compound in water deteriorates if the amount is more than.
When the penetrant is contained, the surface tension of the ink at 25 ° C. is preferably set to 20 to 50 mN / m by adjusting the content of the penetrant. This is because if the surface tension is less than 20 mN / m, it is difficult to form ink droplets when the ink is ejected from the nozzle 14, whereas if it is greater than 50 mN / m, the ink hardly penetrates the recording paper 2. Because it becomes.

In order to make the surface tension about 20 mN / m, it may be impossible to achieve the surface tension only by adding a penetrant. In this case, a fluorosurfactant may be added as a penetrant auxiliary agent. Good.
The fluorosurfactant is preferably, for example, an ammonium salt of perfluoroalkylsulfonic acid, a potassium salt of perfluoroalkylsulfonic acid, or a potassium salt of perfluoroalkylcarboxylic acid.

  An ink for inkjet recording according to an embodiment of the present invention contains a coloring material, a humectant, water, and the organosilicon compound as a water-soluble substance that undergoes a condensation polymerization reaction as the water evaporates. A polymerization reaction accelerator is contained. When an image is formed on the recording paper 2 by the ink jet recording apparatus A using this ink, when the ink droplets adhere on the recording paper 2, a solvent composed of a humectant and water is present in the recording paper 2. To penetrate. As a result, the colorant, the organosilicon compound, and the condensation polymerization accelerator remain on the recording paper 2. In this way, the organosilicon compound undergoes a condensation polymerization reaction and surrounds the color material. At this time, on the recording paper 2, the condensation polymerization accelerator is dissociated or decomposed, and the condensation reaction of the organosilicon compound is performed by the action of the generated acid. The reaction is completed quickly. As a result, the colorant is immediately and reliably surrounded by the organosilicon compound. Thus, the water resistance of the image is greatly improved without depending on the type of the dye. In addition, a high level of water resistance is exhibited immediately after image formation.

In the embodiment of the present invention, the organic silicon compound is included as a water-soluble substance that undergoes a condensation polymerization reaction as water evaporates. However, ink droplets ejected from the nozzles of an inkjet head adhere to the recording paper. When the water (solvent) evaporates or penetrates into the recording paper, it is necessary to have a material that surrounds the color material by a condensation polymerization reaction.

  As is apparent from the results in Table 1 and FIGS. 5 to 8, the combination of the specific black dye of the present invention and the organosilicon compound does not cause decoloration even when left for a long period of time, and when printed on plain paper. An image having excellent water resistance was obtained.

EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited at all by this.
Six types of inks for ink jet recording having the following compositions (the content of each composition is a percentage by weight) were prepared.
In the examples, two types of organosilicon compounds were used as water-soluble substances that undergo a condensation polymerization reaction as water evaporates. Each organosilicon compound was produced by the method shown below.
Organosilicon compound (A)
120 g (6.67 mol) of water was put into a 200 ml reactor equipped with a stirrer, a thermometer and a condenser, and mixed with stirring. A mixture of 44.4 g (0.2 mol) of H ₂ NCH ₂ CH ₂ NHCH ₂ CH ₂ CH ₂ Si (OCH ₃ ) ₃ and 15.2 g (0.1 mol) of Si (OCH ₃ ) ₄ at room temperature. When the solution was added dropwise over 10 minutes, the internal temperature rose from 25 ° C to 56 ° C. Furthermore, it heated to 60-70 degreeC with the oil bath, and stirred as it was for 1 hour. Next, an ester adapter was attached, the internal temperature was raised to 98 ° C., and methanol by-produced was removed to obtain 137 g of an organic silicon compound aqueous solution. The nonvolatile content (105 ° C./3 hours) of this product was 27.3%.
Organosilicon compound (B)
In a 200 ml reactor equipped with a stirrer, a thermometer and a condenser, 100 g (0.56 mol) of (CH ₃ O) ₃ SiCH ₂ CH ₂ CH ₂ NH ₂ was added and heated to 80 ° C. with stirring and mixing. Thereto, 62.2 g (0.84 mol) of 2,3-epoxy-1-propanol was added dropwise over 1 hour. The mixture was further stirred at 80 ° C. for 5 hours to cause reaction of amino group and epoxy group, and then the low fraction was distilled off at 80 ° C. under reduced pressure of 10 mmHg to obtain hydrolyzable silane. 120 g (6.67 mol) of water was placed in a 200 ml reactor equipped with a stirrer, a thermometer and a condenser, and mixed with stirring. A mixture of 50.6 g (0.2 mol) of the hydrolyzable silane and 13.6 g (0.1 mol) of CH ₃ Si (OCH ₃ ) _{3 was} added dropwise at room temperature over 10 minutes. The internal temperature rose from 36C to 36C. Furthermore, it heated to 60-70 degreeC with the oil bath, and stirred as it was for 1 hour. Next, an ester adapter was attached, the internal temperature was raised to 98 ° C., and methanol by-produced was removed to obtain 152 g of an organic silicon compound aqueous solution. The nonvolatile content (105 ° C./3 hours) of this product was 25.3%.

[Example 1]
C. I. Acid Black 194 aqueous solution (dye concentration 10% solution) 45%
(Basacid Black × 40 manufactured by BASF)
Glycerin 7%
Diethylene glycol 5%
Organosilicon compound (A) (non-volatile content: 27.3%) 18.3%
Pure water 24.7%

[Example 2]
C. I. Acid Black 194 aqueous solution (dye concentration 10% solution) 45%
(Basacid Black x 40 liquid 10% solution manufactured by BASF)
Glycerin 7%
Diethylene glycol 5%
Organosilicon compound (A) (non-volatile content: 27.3%) 18.3%
Diammonium hydrogen phosphate 4%
Pure water 20.7%

[Example 3]
C. I. Reactive Black 31 aqueous solution (dye concentration 10% solution) 45%
(Black KRL-SF liquid 10% solution manufactured by Clariant)
Glycerin 7%
Diethylene glycol 5%
Organosilicon compound (A) (non-volatile content: 27.3%) 18.3%
Ammonium carbonate 4%
Pure water 20.7%

[Example 4]
C. I. Reactive Black 31 aqueous solution (dye concentration 10% solution) 45%
(Black KRL-SF liquid 10% solution manufactured by Clariant)
Glycerin 7%
Diethylene glycol 5%
Diethylene glycol monobutyl ether 5%
Organosilicon compound (A) (non-volatile content: 27.3%) 18.3%
Ammonium chloride 4%
Pure water 15.7%

[Example 5]
C. I. Acid Black 194 aqueous solution (dye concentration 10% solution) 45%
(Basacid Black × 40 manufactured by BASF)
Glycerin 7%
Diethylene glycol 5%
Diethylene glycol monobutyl ether 5%
Organosilicon compound (B) (nonvolatile content 25.3%) 19.8%
Ammonium nitrate 4%
Pure water 14.2%

[Example 6]
C. I. Reactive Black 31 aqueous solution (dye concentration 10% solution) 45%
(Black KRL-SF liquid 10% solution manufactured by Clariant)
Glycerin 7%
Diethylene glycol 5%
Diethylene glycol monobutyl ether 5%
Organosilicon compound (B) (nonvolatile content 25.3%) 19.8%
Ammonium borate 5%
Pure water 13.2%

[Comparative Example 1]
C. I. Direct black 168 aqueous solution (dye concentration 10% solution) 45%
(Clariant Direct Black HEF-SF liquid
10% solution)
Glycerin 7%
Diethylene glycol 5%
Diethylene glycol monobutyl ether 5%
Organosilicon compound (A) (non-volatile content: 27.3%) 18.3%
Diammonium hydrogen phosphate 4%
Pure water 15.7%

[Comparative Example 2]
C. I. Direct Black 195 aqueous solution (10% dye concentration solution) 45%
(Pro-jet Fast Black2 10% solution manufactured by Avecia)
Glycerin 7%
Diethylene glycol 5%
Diethylene glycol monobutyl ether 5%
Organosilicon compound (B) (nonvolatile content 25.3%) 19.8%
Ammonium borate 4%
Pure water 14.2%

Next, Table 1 shows the water resistance test results and pH of the inks of Examples 1-6 and Comparative Examples 1-2. Here, the water resistance was determined from the ratio (%) of the OD value after the water resistance test to the OD value before the water resistance test of the print sample (optical density: density value measured with a spectrocolorimeter Xrite 938).
A print sample was prepared by mounting ink on the recording apparatus A and printing a 15 mm square sheet on plain paper (trade name “Xerox 4024” manufactured by Xerox Corporation). The water resistance test was carried out by immersing in distilled water for 5 minutes with the printed surface of the printed matter facing down. After soaking, the product was naturally dried for 30 minutes, and then the OD value was measured.

さらに、実施例２と実施例４及び比較例１と比較例２のインクサンプルをスクリュー管瓶に満たして密閉系とし、７０℃で２日間放置した。そのときの分光スペクトルの測定結果を図５、図６、図７および図８に示した。
実施例２と実施例４の図５、図６は、インクの分光吸収スペクトルに変化が見られないのに対して、比較例１と比較例２の図７、図８は、初期の分光吸収スペクトルに対して、１日保存後、または２日保存後の吸収スペクトルは大幅に吸光度が下がって、消色している。 A storage stability test was performed on the ink samples of Examples 1 to 6 and the ink samples of Comparative Examples 1 and 2.
In this storage stability test, each ink was filled in a screw tube bottle to form a sealed system, left at 50 ° C. for 1 month, and then the color of the ink was first visually confirmed. The ink sample that did not change from the initial color was determined as “◯”, and the ink sample erased from the initial color was determined as “x”. The results are also shown in Table 1.

Further, the ink samples of Example 2 and Example 4 and Comparative Example 1 and Comparative Example 2 were filled in a screw tube bottle to form a closed system and left at 70 ° C. for 2 days. The measurement results of the spectrum at that time are shown in FIG. 5, FIG. 6, FIG. 7, and FIG.
5 and 6 of Example 2 and Example 4 show no change in the spectral absorption spectrum of the ink, whereas FIGS. 7 and 8 of Comparative Example 1 and Comparative Example 2 show the initial spectral absorption. With respect to the spectrum, the absorption spectrum after storage for 1 day or after storage for 2 days is greatly reduced in absorbance and decolored.

1 is a schematic perspective view showing an ink jet recording apparatus using an ink for ink jet recording according to an embodiment of the present invention. It is a partial bottom view of the ink jet head of the ink jet recording apparatus. It is the II sectional view taken on the line of FIG. It is the II-II sectional view taken on the line of FIG. 4 is a spectral absorption spectrum of an ink for ink jet recording having the composition shown in Example 2. 4 is a spectral absorption spectrum of an ink for ink jet recording having the composition shown in Example 4. 2 is a spectral absorption spectrum of an ink for ink jet recording having the composition shown in Comparative Example 1. 3 is a spectral absorption spectrum of an ink for ink jet recording having the composition shown in Comparative Example 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS A Inkjet recording device 1 Ink cartridge 2 Recording paper 3 Inkjet head 4 Carriage 5 Carriage shaft 6 Conveying roller 7 Concave 7a Supply port 7b Ejection port 8 Head body 9 Pressure chamber component 10 Ink channel component 11 Orifice 12 Supply ink channel DESCRIPTION OF SYMBOLS 13 Discharge ink flow path 14 Nozzle 15 Nozzle plate 15a Water-repellent film 16 Piezoelectric actuator 17 Pressure chamber 18 Vibrating plate 19 Piezoelectric element 20 Intermediate layer 21 Individual electrode

Claims (5)

An ink for inkjet recording, comprising a coloring material comprising a chelate azo dye , a humectant, water, and a water- soluble organosilicon compound that starts a condensation polymerization reaction as the water evaporates, Azo dyes are C.I. I. Acid Black 194 and / or C.I. I. An ink for inkjet recording, wherein the ink is reactive black 31 . The ink for inkjet recording according to claim 1, further comprising a condensation polymerization accelerator for promoting a condensation polymerization reaction of a water-soluble organic silicon compound that initiates a condensation polymerization reaction. The ink for inkjet recording according to claim 2, wherein the condensation polymerization accelerator is an inorganic or organic ammonium salt. The ink for ink jet recording according to claim 3, wherein the ammonium salt is a salt of a weak acid. The ink for inkjet recording according to claim 3, wherein the ammonium salt is a salt of a strong acid.

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