JP2003327883A - Ink for ink-jet recording, ink cartridge and recorder provided with the ink - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain high-level weather resistance while maintaining water resistance of an image formed by ink for an ink-jet recording, containing a water-soluble substance to be subjected to a condensation polymerization reaction in the absence of water. <P>SOLUTION: The ink contains an acidic group-containing free radical scavenger. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technical field of an inkjet recording ink, an ink cartridge, and a recording apparatus suitable for inkjet recording.

[0002]

2. Description of the Related Art Conventionally, as an ink used for ink jet recording, one containing a coloring material (dye or pigment), a moisturizing agent, and water is well known. However, when an image is formed on a recording medium such as a recording paper with ink containing a coloring material, there is a problem that the water resistance of the image, that is, the coloring material seeps out into the water when the image gets wet. In particular, plain paper (a wide range of commercially available papers, especially those used in electrophotographic copiers, not intended to have the optimum structure, composition, properties, etc. for inkjet recording. When recorded on paper, the water resistance is very poor.

Therefore, conventionally, for example, Japanese Unexamined Patent Application Publication No. 10-212.
As disclosed in Japanese Patent Laid-Open No. 439, Japanese Patent Laid-Open No. 11-293167 and Japanese Patent Laid-Open No. 11-315231,
Hydrolyzable silane compound (organosilicon compound) for ink
It has been proposed to improve the water resistance of the image on the recording medium by containing By thus containing the silane compound in the ink, when the ink droplet adheres to the recording medium and water (solvent) evaporates or penetrates into the recording medium, the silane compound remaining on the recording medium. Undergoes a polycondensation reaction, and the silane compound subjected to the polycondensation reaction surrounds the coloring material. As a result, even if the image on the recording medium gets wet with water, the coloring material is prevented from seeping out into the water.

[0004]

However, although the above-mentioned conventional ink has an effective effect of improving water resistance, when a recording medium on which an image is formed by the above-mentioned ink is stored in a room for a long period of time, it is exposed to sunlight or the like. There is a disadvantage that the image is discolored even if it is not exposed to the light. This is because the azo group (-N = N-) of the coloring material is attacked by peroxy radicals and ozone generated in the process of thermal oxidation by heat, humidity, and / or chemical substances, and the double bond is single. It is considered that the dye structure is decomposed due to a change in the bond or the double bond is cleaved, which causes a change in hue and a decrease in image density, resulting in fading of the image.

For example, in Japanese Patent Laid-Open No. 2001-240778, by adding a thiocyanate to a normal ink having no water resistance (ink containing no organosilicon compound), the ozone resistance of the ink is improved. What has been improved is described. Therefore, it is conceivable to add the thiocyanate to the water resistant ink in order to improve the weather resistance of the water resistant ink.

However, simply adding thiocyanate to the water-resistant ink does not improve the weather resistance of the image so much.
It was also confirmed that the weather resistance was significantly deteriorated after the image was wet with water.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a recording medium using an inkjet recording ink containing a water-soluble substance which undergoes a polycondensation reaction in the absence of water. It is to obtain a high level of weather resistance while maintaining the water resistance of the above image.

[0008]

To achieve the above object, the first invention comprises a coloring material, a humectant, water, and a water-soluble substance which undergoes a polycondensation reaction in the absence of water. The inkjet recording ink according to the present invention further contains a radical scavenger having an acidic group.

According to this structure, when the ink adheres to the recording medium (for example, paper) as an ink droplet, the water content evaporates or penetrates into the recording medium, and the water-soluble substance undergoes a condensation polymerization reaction, and this condensation occurs. The polymerization reaction product surrounds the coloring material. In this way, even if the image formed on the recording medium by the ink droplets gets wet with water, the coloring material is prevented from seeping out into the water, and the water resistance of the image is secured.

Further, since the ink contains a radical scavenger, even if the image formed on the recording medium by the ink is exposed to peroxy radicals or ozone, the radical scavenger does not allow the peroxy radicals to be absorbed. It captures radicals and ozone, which prevents the colorant from being attacked. As a result, deterioration of the color material is suppressed and deterioration of weather resistance is suppressed.

In particular, since the radical scavenger has an acidic group, the radical scavenger and the water-soluble substance are located close to each other in the ink due to the interaction. In addition, the colorant also interacts with the water-soluble substance,
It is located near the water-soluble substance in the ink. Therefore, when the water-soluble substance undergoes a polycondensation reaction,
The radical scavenger together with the coloring material is also surrounded by the polycondensation reaction product. As a result, the radical scavenger will be located near the coloring material on the recording medium, effectively blocking the coloring material from being attacked by peroxy radicals and ozone, and greatly improving weather resistance. To do.

Moreover, since the radical scavenger is surrounded by the water-soluble substance, even if the image on the recording medium gets wet with water, the radical scavenger can be prevented from flowing out into the water like the coloring material. . Thereby, even after the image on the recording medium is wet with water, deterioration of weather resistance can be continuously suppressed.

That is, if the radical scavenger does not have an acidic group, the interaction between the radical scavenger and the water-soluble substance is weak, and therefore the radical scavenger is not surrounded by the water-soluble substance. It is considered that when the image on the medium gets wet with water, the radical scavenger flows out and the weather resistance deteriorates.

On the other hand, in the present invention, by making the radical scavenger have an acidic group, the coloring material and the radical scavenger are both surrounded by the water-soluble substance, and the coloring material and the radical scavenger are mutually separated. Will be located in the vicinity,
As a result, not only the water resistance of the image is secured, but also a high level of weather resistance is obtained, and deterioration of the weather resistance after the image on the recording medium is wetted with water is also suppressed.

Here, the water-soluble substance is preferably a hydrolyzable silane compound. That is, the silane compound is very preferable in improving the water resistance, and the radical scavenger is surely taken in, and the weather resistance is also improved.

The radical scavenger may be a phenol compound or a sulfur compound. The acidic group contained in the radical scavenger may be, for example, sodium sulfonate or sodium carboxylate,
Among these, sodium sulfonate is preferable from the viewpoint of solubility in water.

It is preferable that the above ink further contains a penetrant. By doing so, the solvent of the ink consisting of the moisturizing agent, the penetrating agent and the water quickly permeates into the recording medium after the ink adheres to the recording medium (for example, paper). As a result, the polycondensation reaction of the water-soluble substance is promptly performed, and the color material (and the radical scavenger) is reliably surrounded. As a result, the water resistance of the image is further improved.

A second aspect of the present invention is a coloring material, a moisturizing agent, water,
The present invention relates to an ink cartridge including an inkjet recording ink containing a water-soluble substance that undergoes a polycondensation reaction in the absence of water. The ink further contains a radical scavenger having an acidic group.

A third aspect of the present invention is a coloring material, a moisturizing agent, water,
The present invention relates to a recording apparatus that includes an inkjet recording ink containing a water-soluble substance that undergoes a polycondensation reaction in the absence of water, and discharges the ink onto a recording medium to perform recording. The ink is a radical having an acidic group. A scavenger is further included.

According to the second or third invention, the same effect as that of the first invention can be obtained.

Also in the second or third aspect of the invention, the ink further contains a penetrant so that the solvent of the ink consisting of the moisturizer, the penetrant and water can be quickly permeated into the recording medium. It is preferable to further improve the water resistance.

[0022]

As described above, according to the ink-jet recording ink of the present invention, and the ink cartridge and the recording apparatus provided with the ink, the ink contains a radical scavenger having an acidic group. When is attached to the recording medium and the water-soluble substance undergoes a polycondensation reaction, since the coloring material and the radical scavenger are both surrounded by the polycondensation reaction product, while maintaining the water resistance of the image on the recording medium, A high level of weather resistance can be obtained, and further deterioration of weather resistance can be suppressed even after the image on the recording medium is wet with water.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 schematically shows an ink jet recording apparatus A having an ink for ink jet recording according to an embodiment of the present invention. This recording apparatus A has an ink cartridge 35 having the above ink on its upper surface. And an ink jet head 1 for ejecting the ink onto a recording paper 41 as a recording medium as described later. The inkjet head 1 is supported and fixed to a carriage 31, and a carriage motor (not shown) is provided on the carriage 31. The carriage motor drives the inkjet head 1 and the carriage 31 in the main scanning direction (see FIGS. 1 and 2). The carriage shaft 32 extends in the X direction) and is reciprocated in that direction.

The recording paper 41 is sandwiched between two transport rollers 42 which are rotationally driven by a transport motor (not shown), and the transport motor and the transport rollers 42 cause the recording paper 41 to be located below the ink jet head 1. The sheet is conveyed in the sub-scanning direction (Y direction shown in FIGS. 1 and 2) which is perpendicular to the main scanning direction.

As described above, the ink jet head 1 and the recording paper 41 are relatively moved by the carriage 31, the carriage shaft 32, the carriage motor, and the respective conveyance rollers 42 and the conveyance motor.

As shown in FIGS. 2 to 4, the ink jet head 1 has a plurality of pressure chamber recesses 3 each having a supply port 3a for supplying ink and a discharge port 3b for discharging ink. The head main body 2 is provided.
The recesses 3 of the head main body 2 are opened in the upper surface of the head main body 2 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 the opening of each recess 3 is about 1250 μm,
The width is set to about 130 μm. Both ends of the opening of each recess 3 have a substantially semi-circular shape.

The side wall of each recess 3 of the head body 2 is
An ink composed of a pressure chamber component 6 made of photosensitive glass having a thickness of about 200 μm, and the bottom wall of each recess 3 is adhesively fixed to the lower surface of the pressure chamber component 6 and laminated with six stainless steel thin plates. The flow path component 7 is used. In the ink flow path component 7, a plurality of orifices 8 respectively connected to the supply ports 3a of the recesses 3 and one supply ink flow path connected to the orifices 8 and extending in the sub-scanning direction. 11 and a plurality of ejection ink flow paths 12 respectively connected to the ejection ports 3b.

Each of the orifices 8 has an ink flow path component 7
Is formed in the second stainless steel thin plate from the top having a smaller plate thickness than the others, and its diameter is set to about 38 μm. Further, the supply ink flow path 11 is connected to the ink cartridge 35, and ink is supplied from the ink cartridge 35 into the supply ink flow path 11.

A nozzle plate 9 made of stainless steel and having a plurality of nozzles 14 for ejecting ink droplets toward the recording paper 41 is adhered and fixed to the lower surface of the ink flow path component 7. The lower surface of the nozzle plate 9 is covered with a water repellent film 9a. Each of the nozzles 14 is connected to the ejection ink flow path 12, and communicates with the ejection port 3b of each recess 3 through the ejection ink flow path 12, and the bottom surface of the inkjet head 1 is connected. In the sub-scanning direction. Each of the nozzles 14 is composed of a taper portion whose nozzle diameter decreases toward the nozzle tip side and a straight portion which is continuously provided on the nozzle tip side of the taper portion. It is set to about 20 μm.

Above the recesses 3 of the head body 2,
Each piezoelectric actuator 21 is provided. Each piezoelectric actuator 21 has a Cr vibrating plate 22 that closes each recess 3 of the head main body 2 in a state of being adhered and fixed to the upper surface of the head main body 2 and forms a pressure chamber 4 together with the recess 3. There is. The vibrating plate 22 is one common to all the piezoelectric actuators 21 and also functions as a common electrode common to all the piezoelectric elements 23 described later.

The piezoelectric actuators 21 are
Zirconate titanate is provided on a side surface (upper surface) of the vibration plate 22 opposite to the pressure chamber 4 at a portion corresponding to the pressure chamber 4 (a portion facing the opening of the recess 3) via an intermediate layer 25 made of Cu. Piezoelectric element 2 made of lead (PZT)
3, and the individual electrodes 24 made of Pt, which are joined to the side surface (upper surface) of each piezoelectric element 23 opposite to the vibrating plate 22 and for applying a voltage (driving voltage) to each piezoelectric element 23 together with the vibrating plate 22. And have.

The vibrating plate 22, the piezoelectric elements 23, the individual electrodes 24, and the intermediate layers 25 are all formed of thin films, and the vibrating plate 22 has a thickness of about 6 μm and a thickness of each piezoelectric element 23. Is set to 8 μm or less (for example, about 3 μm), the thickness of each individual electrode 24 is set to about 0.2 μm, and the thickness of each intermediate layer 25 is set to about 3 μm.

Each piezoelectric actuator 21 applies a drive voltage to each piezoelectric element 23 through the vibration plate 22 and each individual electrode 24, so that the pressure chambers 4 of the vibration plate 22 are affected.
By deforming a portion (opening portion of the concave portion 3) corresponding to the ink, the ink in the pressure chamber 4 is ejected from the ejection port 3b or the nozzle 1.
It is designed to discharge from No. 4. That is, when a pulsed voltage is applied between the diaphragm 22 and the individual electrode 24, the rise of the pulse voltage causes the piezoelectric element 23 to contract in the width direction perpendicular to its thickness direction due to the piezoelectric effect. Since the plate 22, the individual electrode 24, and the intermediate layer 25 do not contract, the portion corresponding to the pressure chamber 4 of the vibration plate 22 is bent and deformed toward the pressure chamber 4 side by the so-called bimetal effect. This flexural deformation increases the pressure in the pressure chamber 4, and the pressure causes the ink in the pressure chamber 4 to be pushed out of the nozzle 14 via the ejection port 3b and the ejection ink flow path 12. Then, the piezoelectric element 23 expands due to the fall of the pulse voltage, and the portion of the vibration plate 22 corresponding to the pressure chamber 4 returns to the original state. At this time, the nozzle 14
The ink extruded from the ink is torn off from the ink in the ink flow path 12 and is ejected to the recording paper 41 as an ink droplet (for example, 3 pl) and adheres to the surface of the recording paper 41 in a dot shape. Further, when the vibration plate 22 is bent and deformed in a convex shape and is returned to the original state, the ink is supplied from the ink cartridge 35 into the pressure chamber 4 via the ink supply channel 11 and the supply port 3a. Is filled.
As the pulse voltage applied to each piezoelectric element 23, even if the pulse voltage is not of the push-pull type as described above, after falling from the first voltage to the second voltage lower than the first voltage. A pull-and-push type of rising to the first voltage may be used.

The drive voltage is applied to each piezoelectric element 23 for a predetermined time (for example, when the ink jet head 1 and the carriage 31 are moved from one end to the other end of the recording paper 41 in the main scanning direction at a substantially constant speed). About 50 μs: Drive frequency is 20 kHz (however, no voltage is applied when the inkjet head 1 reaches a portion of the recording paper 41 where ink droplets are not landed).
As a result, the ink droplet is landed on the predetermined position of the recording paper 41. When the recording for one scan is completed, the recording paper 41 is conveyed by a predetermined amount in the sub-scanning direction by the conveyance motor and the respective conveyance rollers 42, and the ink droplets are moved again while moving the inkjet head 1 and the carriage 31 in the main scanning direction. Is ejected to perform printing for one new scan. By repeating this operation, a desired image is formed on the entire recording paper 41.

The ink used in the recording apparatus A is a coloring material, a moisturizing agent for suppressing the drying of the nozzles 14 of the ink jet head 1 and the like, and the recording paper 41 of the ink (solvent).
It contains a penetrating agent that enhances the permeability to the inside, water, and a water-soluble substance that undergoes a polycondensation reaction in the absence of water.

The dye as the coloring material may be any dye, but is preferably a water-soluble acid dye or a direct dye.

On the other hand, the following pigments are preferable as the coloring material. That is, as the black pigment, a carbon black surface-treated with a diazonium salt or a polymer surface-treated by graft polymerization of a polymer is preferable.

The color pigment is preferably a pigment treated with a surfactant such as a formalin condensate of naphthalene sulfonate, lignosulfonic acid, dioctyl sulfosuccinate, polyoxyethylene alkylamine, or fatty acid ester. . Specifically, examples of cyan pigments include Pigment Blue 15: 3, Pigment Blue 15: 4, and aluminum phthalocyanine. Examples of magenta pigments include Pigment Red 122 and Pigment Violet 19. Further, as the yellow pigment, for example, Pigment Yellow 74, Pigment Yellow 109, Pigment Yellow 110, or Pigment Yellow 12
8 etc. are mentioned.

The humectant is preferably a polyhydric alcohol such as glycerin or 1,3-butanediol, or a water-soluble nitrogen heterocyclic compound such as 2-pyrrolidone or N-methyl-2-pyrrolidone.

The penetrant may be diethylene glycol monobutyl ether, 2-butoxyethanol, or the like.
It is preferably a monoalkyl ether of a polyhydric alcohol.

As the water-soluble substance, an ink droplet ejected from the nozzle 14 of the ink jet head 1 is used as the recording paper 4.
1 and the water (solvent) evaporates on the recording paper 41.
When the image on the recording paper 41 is wet with water, the coloring material stains in the water when the image on the recording paper 41 is surrounded by the polycondensation reaction on the recording paper 41 when it penetrates into the inside. It prevents the image from being output and improves the water resistance of the image. Specifically, a hydrolyzable silane compound, a hydrolyzable titanium compound, etc. are mentioned as an example. Among these, a hydrolyzable silane compound (organosilicon compound) is particularly preferable from the viewpoint of stability.

Further, as the water-soluble substance, it is more preferable to use a compound having an amino group because the interaction with a radical scavenger having an acidic group described later becomes stronger.

Such water-soluble substance (organosilicon compound)
As a, a hydrolysis reaction product of an alkoxysilane containing an organic group having an amino group and an alkoxysilane not containing an amino group, or a hydrolysis reaction of an organic monoepoxy compound with a hydrolyzable silane containing an amino group. An organosilicon compound obtained by hydrolyzing a reactive silane and a hydrolyzable silane containing no nitrogen atom is preferable.

The ink jet recording ink according to this embodiment further contains a radical scavenger having an acidic group. This radical scavenger has a function of trapping peroxy radicals and ozone generated in the process of thermal oxidation.

Specific examples of the above-mentioned radical scavenger include phenol compounds and sulfur compounds.

Further, examples of the acidic group contained in the radical scavenger include sodium sulfonate and sodium carboxylate, but sodium sulfonate is preferable from the viewpoint of solubility in water.

Specific examples of the above-mentioned phenolic compounds include the compounds of the following "Chemical formula 1" to "Chemical formula 6". Incidentally, these compounds can be easily obtained by sulfonation or carboxylation of a phenolic compound marketed as an antioxidant.

[0048]

[Chemical 1]

[0049]

[Chemical 2]

[0050]

[Chemical 3]

[0051]

[Chemical 4]

[0052]

[Chemical 5]

[0053]

[Chemical 6]

Specific examples of the sulfur compounds include the compounds of the following "Chemical formula 7" to "Chemical formula 16". Incidentally, these compounds can be easily obtained by sulfonating or carboxylating a sulfur-based compound which is marketed as an antioxidant.

[0055]

[Chemical 7]

[0056]

[Chemical 8]

[0057]

[Chemical 9]

[0058]

[Chemical 10]

[0059]

[Chemical 11]

[0060]

[Chemical 12]

[0061]

[Chemical 13]

[0062]

[Chemical 14]

[0063]

[Chemical 15]

[0064]

[Chemical 16]

As described above, in the above embodiment, the ink for ink jet recording has a coloring material, a humectant, a penetrating agent, water, and water as a water-soluble substance which undergoes a polycondensation reaction in the absence of water. Since this ink contains a decomposable silane compound, the recording paper A is recorded by the recording apparatus A using this ink.
When an image is formed on the recording paper 41, the solvent composed of the moisturizing agent, the penetrant and the water quickly permeates into the recording paper 41 when the ink droplets adhere to the recording paper 41. As a result, the silane compound undergoes a polycondensation reaction and the polysilane compound that has undergone the polycondensation reaction surrounds the coloring material, and even if the image on the recording paper 41 gets wet with water, the coloring material may exude into the water. To be prevented.

The ink according to this embodiment further contains a radical scavenger having an acidic group.
Since this radical scavenger has an acidic group, it has a strong interaction with the silane compound having an amino group, and therefore, it is positioned in the vicinity of the silane compound in the ink like the coloring material. As a result, when the silane compound undergoes the polycondensation reaction, not only the coloring material but also the above-mentioned radical scavenger is surrounded by the silane compound that has undergone the polycondensation reaction. Come to be located. Therefore, even if the image on the recording paper 41 is exposed to peroxy radicals or ozone, the peroxy radicals and ozone are captured by the radical scavenger located in the vicinity of the coloring material. Prevented from being attacked. In this way, deterioration of the color material is suppressed, and deterioration of weather resistance can be effectively suppressed.

Since the radical scavenger is surrounded by the silane compound which has undergone the polycondensation reaction, the recording paper 41 is
Even if the above image gets wet with water, the radical scavenger is prevented from flowing out into water. Thereby, even after the image is wet with water, the radical scavenging effect of the radical scavenger can be obtained, and the deterioration of weather resistance can be continuously suppressed.

In this way, the ink jet recording ink according to the present embodiment can obtain a high level of weather resistance while maintaining the water resistance of the image on the recording medium.

In the above embodiment, the hydrolyzable silane compound is contained as the water-soluble substance which undergoes the polycondensation reaction in the absence of water.
If the ink droplets ejected from No. 4 adhere to the recording paper 41 and water (solvent) evaporates or penetrates into the recording paper 41, the condensation polymerization reaction surrounds the coloring material. It may be something like this.

In the above embodiment, the ink contains the penetrant, but the penetrant is not an essential component of the ink according to the present embodiment. However, when the penetrant is contained in the ink, the solvent of the ink quickly penetrates into the recording paper 41, whereby the water resistance of the image can be further improved.

[0071]

EXAMPLES Next, concretely implemented examples will be described.

First, eight types of ink jet recording inks having the following compositions (the content of each composition is a mass percentage) were prepared (Examples 1 to 8).

In all of Examples 1 to 8 above, glycerin was contained as a moisturizer.

Further, a dye is contained as a coloring material, and in Examples 1 to 5, JPD Yellow M is used.
Example 6 while containing T-NL (manufactured by Nippon Kayaku Co., Ltd.)
In ~ 8, dyes of different colors were included.

Further, as a water-soluble substance which undergoes a polycondensation reaction in the absence of water, an organosilicon compound was contained in all of Examples 1 to 8. This organosilicon compound was produced by the following method. That is, 120 g (6.67 mol) of water was placed in a reaction vessel equipped with a cooler,
While stirring this, 35 g (0.2 mol) of 1-trimethoxysilyl-3-aminopropane and 15.2 g
A mixture of (0.1 mol) tetramethoxysilane was added drop by drop. After dropping the whole amount, the temperature of the reaction vessel is set to 6
The temperature was raised to 0 ° C. and stirring was continued for 1 hour, then the temperature of the reaction vessel was raised to 90 ° C., and the reaction was continued while stirring for 2 hours. After the reaction, the produced methanol was removed by distillation. The organosilicon compound thus produced is the organosilicon compound contained in each of the examples.

Example 1 A compound represented by “Chemical Formula 1” was contained as a radical scavenger. JPD Yellow MT-NL (manufactured by Nippon Kayaku Co., Ltd.) ... 5% Glycerin ... 7% Diethylene glycol ... 5% Organosilicon compound ... 5% Radical scavenger (Chemical formula 1) ... 5% Pure water ... 73%.

Example 2 A compound represented by “Chemical Formula 2” was contained as a radical scavenger. JPD Yellow MT-NL (manufactured by Nippon Kayaku Co., Ltd.) ... 5% Glycerin ... 7% Diethylene glycol ... 5% Organosilicon compound ... 5% Radical scavenger (Chemical Formula 2) ... 5% Pure water ... 73%.

Example 3 A compound represented by "Chemical Formula 5" was incorporated as a radical scavenger. JPD Yellow MT-NL (manufactured by Nippon Kayaku Co., Ltd.) ... 5% Glycerin ... 7% Diethylene glycol ... 5% Organosilicon compound ... 5% Radical scavenger (Chemical Formula 5) ... 5% Pure water ... 73%.

Example 4 A compound represented by “Chemical Formula 9” was contained as a radical scavenger. JPD Yellow MT-NL (manufactured by Nippon Kayaku Co., Ltd.) ... 5% Glycerin ... 7% Diethylene glycol ... 5% Organosilicon compound ... 5% Radical scavenger (Formula 9) ... 5% Pure water ... 73%.

Example 5 As a radical scavenger,
4 ”was included. JPD Yellow MT-NL (manufactured by Nippon Kayaku Co., Ltd.) ... 5% Glycerin ... 7% Diethylene glycol ... 5% Organosilicon compound ... 5% Radical scavenger (Chemical formula 14) ... 5% Pure water ... 73%.

(Example 6) The dye was changed from Example 1. C. I. Acid red 289 ... 5% Glycerin ... 7% Diethylene glycol ... 5% Organosilicon compound ... 5% Radical scavenger (Chemical formula 1) ... 5% Pure water ... 73%.

(Example 7) The dye was changed from that in Example 1. C. I. Direct Blue 199 ... 5% Glycerin ... 7% Diethylene glycol ... 5% Organosilicon compound ... 5% Radical scavenger (Chemical formula 1) ... 5% Pure water ... 73%.

(Example 8) The dye was changed from Example 1. C. I. Direct Black 154 ... 5% Glycerin ... 7% Diethylene glycol ... 5% Organosilicon compound ... 5% Radical scavenger (Chemical Formula 1) ... 5% Pure water ... 73%.

Subsequently, for comparison, inks having the following compositions (the content of each composition is a mass percentage) were prepared (Comparative Examples 1 and 2). Among these, the comparative example 1 does not add a radical scavenger. In addition, Comparative Example 2
In Example 1, sodium thiocyanate was contained in place of the radical scavenger having an acidic group.

[0085]   (Comparative Example 1) JPD Yellow MT-NL (Nippon Kayaku Co., Ltd.) ... 5% Glycerin ... 7% Diethylene glycol: 5% Organosilicon compound: 5% Pure water ... 78%.

[0086]   (Comparative example 2) JPD Yellow MT-NL (Nippon Kayaku Co., Ltd.) ... 5% Glycerin ... 7% Diethylene glycol: 5% Organosilicon compound: 5% Sodium thiocyanate: 5% Pure water ... 73%.

Next, each of the above Examples 1 to 8 and Comparative Example 1,
As the weather resistance test with the ink of 2, the ozone resistance test,
A heat resistance test and a high temperature and high humidity resistance test were conducted.

The print samples used in these tests were made by using the above-mentioned inks and commercially available printers (piezoelectric actuators similar to those in the above embodiment (however, the thickness of the piezoelectric element is considerably larger than that in the above embodiments). ), Plain paper (brand name "Xerox40")
24 ": manufactured by Xerox Co., Ltd.) with solid printing of 15 mm square. Then, after 10 minutes from printing, each printed sample was immersed in distilled water for 5 minutes with its printed surface facing downward, and after the immersion, it was naturally dried for 30 minutes, and the OD value of each printed sample was measured ( This is the OD value before the ozone resistance, heat resistance, and high temperature and high humidity resistance test). The following tests were carried out using each printed sample after this water resistance test as an initial sample.

In the ozone resistance test, each of the above initial samples was placed in an ozone atmosphere environment of 1 ppm at 25 ° C. and 60% RH for 500 hours, and then the OD value was measured.

As a heat resistance test, each of the above initial samples was placed in an oven at 80 ° C. for 500 hours, and then O
The D value was measured.

As a high temperature and high humidity resistance test, each of the above initial samples was subjected to 500 ° C. in an atmosphere of 70 ° C. and 80% RH.
It was put in for a period of time, and then the OD value was measured.

The ozone resistance, heat resistance and high temperature and high humidity resistance tests were evaluated by the ratio (%) of the OD values measured before and after the test.
Went by. The results are shown in Table 1.

[0093]

[Table 1]

From Table 1, each of the inks of Examples 1 to 8 has ozone resistance, heat resistance and high temperature and high humidity resistance of 95% or more, while each of the inks of Comparative Examples 1 and 2 has high resistance to ozone. The ozone resistance, heat resistance and high temperature and high humidity resistance were each 80% or less.

From these results, it is found that the ink of Comparative Example 1 has almost no weather resistance because it does not contain a radical scavenger.

Further, in the ink of Comparative Example 2, since sodium thiocyanate has a weak interaction with the water-soluble substance (organosilicon compound), when the water-soluble substance undergoes a polycondensation reaction, sodium thiocyanate is condensed. It is presumed that it is not surrounded by the polymerization reaction product. In addition, since sodium thiocyanate has a high solubility in water, when the printed sample is immersed in water, the sodium thiocyanate dissolves in water, resulting in deterioration of weather resistance after immersion. Conceivable.

On the other hand, in the inks of the respective examples, since the radical scavenger has an acidic group, there is a strong interaction between the radical scavenger and the water-soluble substance. Therefore, when the water-soluble substance undergoes a polycondensation reaction, the radical scavenger is supposed to be surrounded by the polycondensation reaction product together with the coloring material. Therefore, it is considered that the radical scavenger was not flown into water even when the image formed by the ink of each example was wet, and as a result, the weather resistance was dramatically improved.

A water resistance test was conducted using the inks of the above Examples and Comparative Examples.
It was confirmed that high water resistance was obtained.

In addition, among the above-mentioned "Chemical formula 1" to "Chemical formula 16", inks containing other radical scavengers, which are not shown in the examples, have the same weather resistance as those of the respective examples. It was confirmed that Furthermore, it was confirmed that similar results were obtained even in the inks of the respective examples, in which the pigment contained a coloring material instead of the dye.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing an inkjet recording apparatus provided with an inkjet recording ink according to an embodiment of the present invention.

FIG. 2 is a partial bottom view of an inkjet head of the inkjet recording apparatus.

3 is a sectional view taken along line III-III in FIG.

4 is a sectional view taken along line IV-IV in FIG.

[Explanation of symbols]

1 inkjet head 14 nozzles 21 Piezoelectric actuator 23 Piezoelectric element 35 ink cartridges 41 Recording paper (recording medium) A inkjet recording device

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2C056 EA13 FC02                 2H086 BA53 BA55 BA59                 4J039 AE11 BC07 BC29 BC53 BC54                       BC57 BE01 BE02 BE22 CA03                       EA03 EA38 EA46 GA24

Claims (8)

[Claims] 1. An inkjet recording ink containing a coloring material, a humectant, water, and a water-soluble substance that undergoes a polycondensation reaction in the absence of water, further comprising a radical scavenger having an acidic group. An ink for ink-jet recording, characterized by containing. 2. The inkjet recording ink according to claim 1, wherein the water-soluble substance is a hydrolyzable silane compound. 3. The ink for ink jet recording according to claim 1, wherein the radical scavenger is a phenol compound or a sulfur compound. 4. The ink for inkjet recording according to claim 1, further comprising a penetrant. 5. An ink cartridge comprising an inkjet recording ink containing a coloring material, a humectant, water, and a water-soluble substance that undergoes a polycondensation reaction in the absence of water. An ink cartridge, which further contains a radical scavenger having an acidic group. 6. The ink cartridge according to claim 5, wherein the ink further contains a penetrant. 7. An inkjet recording ink containing a coloring material, a humectant, water, and a water-soluble substance that undergoes a polycondensation reaction in the absence of this water, and the ink is discharged onto a recording medium for recording. A recording apparatus for performing the above, wherein the ink further contains a radical scavenger having an acidic group. 8. The recording apparatus according to claim 7, wherein the ink further contains a penetrant.