JP2005350548A - Pigment ink and ink set, ink cartridge, recording unit, apparatus for recording image and method for ink-jet recording using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pigment ink affording an image maintaining excellent fretting resistance without lowering image density in an ink prepared by using a self-dispersible pigment and to provide an ink set, an ink cartridge, a recording unit, an apparatus for recording the image and a method for ink-jet recording using the pigment ink. <P>SOLUTION: The pigment ink comprises a pigment and is characterized in that the pigment has two kinds of atomic groups of one kind or several kinds of atomic groups represented by structural formula (I), respectively and an atomic group containing at least an alkylene oxide chain on the surface. The ink set, ink cartridge, recording unit, apparatus for recording the image and method for ink-jet recording using the pigment ink are provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is a pigment ink, ink set, ink cartridge, recording unit, and image recording that can be suitably used for writing instruments such as water-based ballpoint pens, fountain pens, water-based sign pens, and on-demand type ink jet printers such as thermal jet and piezo methods. The present invention relates to an apparatus and an ink jet recording method.

  Conventionally, dyes have been used as colorants for inks that require excellent color developability and stability. However, although the dye has the above-mentioned advantages, there is a problem that the formed image is inferior in fastness such as water resistance and light resistance, and improvement is required. In recent years, in order to improve these problems, many pigment inks (hereinafter also simply referred to as “inks”) using organic pigments or carbon black instead of dyes have been proposed.

  However, when an organic pigment or carbon black is used instead of a dye as an ink coloring material, the scratch resistance of the formed image (for example, the image is rubbed with a finger or a marker pen is used for the image) In such a case, there is a problem that the property of not causing rubbing and bleeding is not sufficient. In order to solve this problem, there is a proposal about using a resin-bonded self-dispersing pigment or the like (see, for example, Patent Document 1). This is a segment (A) having a reactive group capable of reacting with a functional group on the pigment surface in a recording medium liquid (ink) containing a liquid medium used in the ink jet recording method and a colorant component (coloring material). A pigment composite polymer obtained by heating a polymer having a segment (B) having substantially no reactive group and having a higher affinity for the liquid medium than the segment (A) with a pigment; In this technique, ink is contained as a colorant component. However, in the pigment composite polymer used in the present invention, a polymer having a specific functional group is required as a polymer (segment) that reacts with the pigment surface, so that usable polymers are limited. In addition, a functional group capable of reacting with the polymer is essential on the pigment surface, and the types of pigments that can be used are limited. Further, as a problem in production, there is a problem that it is difficult to impart ionicity to the pigment surface and a segment having no reactive group, and it is difficult to obtain an aqueous dispersion having ionicity.

  Further, there is a disclosure of using a resin-bonded self-dispersing pigment using a plurality of molecules (see, for example, Patent Document 2). This resin-bonded self-dispersible pigment can be dispersed in an aqueous pigment having ionic properties. By using these resin-bonded self-dispersing pigments, although the reliability of the ink for the recording head can be secured, there is room for further improvement in the scratch resistance of the printed matter.

Further, a pigment ink has been proposed in which an ester functional group for improving water resistance and a functional group for imparting dispersibility are bonded to the pigment surface to achieve both water resistance and dispersion stability (for example, Patent Document 3). reference). However, printed matter printed using this ink has room for further improvement in scratch resistance.
In order to improve the scratch resistance of an image printed by inkjet recording, a method of increasing the ink permeability and allowing the coloring material to penetrate into the recording medium is a known technique in the industry.
JP-A-9-272831 International Publication No. 01/51566 Pamphlet JP 2001-55532 A

However, it is also known in the industry that when such highly penetrating ink is used, there is an adverse effect that the image density of the printed matter is lowered.
Accordingly, an object of the present invention is to provide an ink capable of maintaining an excellent scratch resistance and obtaining an image without a decrease in image density in an ink prepared using a self-dispersing pigment. .

（但し、上記式中にあるＭは、水素原子、アルカリ金属、アンモニウム又は有機アンモニウムを表わし、Ｒ₁は、炭素原子数１〜１２のアルキル基、置換基を有してもよいフェニル基又は置換基を有してもよいナフチル基を表わす。） The above object is achieved by the present invention described below. That is, the present invention provides a pigment ink containing a pigment, wherein the pigment has, on the surface, one or several atomic groups represented by the following structural formula (I) and an atomic group containing at least an alkylene oxide chain. A pigment ink having two types of atomic groups, an ink set using the ink, an ink cartridge, a recording unit, an image recording apparatus, and an ink jet recording method.

(However, M in the above formula represents a hydrogen atom, an alkali metal, ammonium or organic ammonium, and R ₁ is an alkyl group having 1 to 12 carbon atoms, an optionally substituted phenyl group or a substituted group. Represents an optionally substituted naphthyl group.)

  According to the present invention, an ink using a self-dispersing pigment having a specific configuration as a coloring material can improve a scratch resistance and can provide a recorded matter without a decrease in image density.

  Next, the present invention will be described in more detail with reference to preferred embodiments. The ink according to the present invention is characterized in that the pigment in the ink has at least two types of atomic groups having a specific structure on the surface. In addition, it is more preferable that these two types of atomic groups are chemically bonded to the pigment surface in a specific amount and a specific ratio, as will be described later. Moreover, it is more preferable to use a pigment in which these two types of atomic groups are bonded in a specific amount and a specific ratio, as will be described later.

  First, at least two types of atomic groups having a specific structure that is chemically bonded to the pigment surface will be described. The first atomic group is characterized in that it is at least one selected from atomic groups consisting of the structural formula (I) listed below.

Here, M in the above formula represents a hydrogen atom, an alkali metal, ammonium or organic ammonium, and R ₁ is an alkyl group having 1 to 12 carbon atoms, an optionally substituted phenyl group or a substituted group. A naphthyl group which may have a group; Examples of the alkali metal include Li, Na, K, Rb, and Cs. Examples of the organic ammonium include methylammonium, dimethylammonium, trimethylammonium, ethylammonium, diethylammonium, triethylammonium, monohydroxymethylamine, dihydroxymethylamine, trihydroxymethylamine, ethanolammonium, diethanolammonium, and triethanolammonium. Etc.

  The second atomic group contains at least an alkylene oxide chain. The alkylene oxide chain is preferably an ethylene oxide chain (n = 10 to 300). More preferably, those having an ethylene oxide unit represented by the following structural formula (II) are preferred. Of course, the present invention is not limited to the atomic group represented by the following structural formula (II), and can be suitably used as long as it has an ethylene oxide unit.

（但し、式中のＲ₂は、水素原子、炭素原子数１〜１２のアルキル基、置換基を有してもよいフェニル基又は置換基を有してもよいナフチル基を表わし、ｎ＝１０〜３００を表わす。）

(However, R ₂ in the formula represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an optionally substituted phenyl group, or an optionally substituted naphthyl group, and n = 10. Represents ~ 300.)

  The ink according to the present invention is characterized by containing a pigment having at least two kinds of atomic groups having a specific structure as described above. Since the pigment has these atomic groups, it becomes a self-dispersing pigment. According to the ink according to the present invention having such a configuration, even when printed on a recording medium such as plain paper, a recorded matter without deterioration in image density can be obtained while maintaining excellent scratch resistance. . As another effect, it has been found that the dispersion stability of the ink may be improved even during long-term storage.

  Although the detailed mechanism by which such an ink exhibits the above-mentioned characteristics is not clear at present, it is considered as follows. That is, when pigment particles that were stably present in the ink by the atomic group represented by the structural formula (I) are printed on a recording medium, the atomic group represented by the structural formula (I) Encapsulated in the atomic group represented by the formula (II) increases the binding force between the pigment particles, and as a result, a recorded product without deterioration in image density can be obtained while maintaining excellent scratch resistance. I believe.

  As for the dispersion stability of the ink, the pigment particles are stabilized by electrostatic repulsion by the ionic functional group of the atomic group represented by the structural formula (I), and by the bonding of the atomic group represented by the structural formula (II). It is presumed that the dispersibility of the pigment particles is increased due to an increase in the hydration power of the polymer and steric hindrance due to the polymer chain.

  Next, a method for producing a pigment in which at least two types of atomic groups having the specific structure as described above are chemically bonded to the surface will be described. In particular, when the pigment produced by the following method is used in ink, the above-described effects are more easily exhibited.

  First, all the atomic groups represented by the structural formula (I) described above are a method of introducing an ionic functional group into a pigment by sandwiching phenylene by an azo coupling method, or a conventionally known ozone treatment or plasma. It can be introduced onto the pigment surface by an oxidation treatment method such as treatment or liquid phase oxidation treatment. However, it is not necessarily limited to these manufacturing methods.

Further, the atomic group represented by the structural formula (II) is obtained by further chemically modifying the surface of the pigment modified with the atomic group represented by the structural formula (I) obtained as described above. It can be introduced. Specifically, for example, introduction of _{-COO (CH 2 CH 2 O)} n -H as atomic group represented by the structural formula (I), -COOH, or after introducing the -R ₁ -COOH , HO (CH ₂ CH ₂ O) _n —H is chemically bonded by a conventional esterification reaction. In this case, a part of the introduction amount of the atomic group represented by the structural formula (I) introduced by the method described above is replaced with the atomic group represented by the structural formula.

In addition, the introduction of —OCOCH ₂ (OCH ₂ CH ₂ ) _n —O—R ₂ shown as structural formula (II) is performed by introducing acidic carbon or an atomic group represented by structural formula (I). This is possible by chemically bonding a hydroxyl group on the treated carbon surface and R ₂ —O— (CH ₂ CH ₂ O) _n —CH ₂ —COOH by a normal esterification reaction. Of course, the method for introducing the atomic group represented by the structural formula (II) is not particularly limited to the above example.

  The pigment used in the present invention can be produced, for example, by using the following carbon black as the base carbon and introducing the above-mentioned atomic groups on the surface thereof. For example, carbon black such as furnace black, lamp black, acetylene black and channel black can be used. Specifically, for example, Raven 7000, Rayvan 5750, Rayvan 5250, Rayvan 5000ULTRA, Rayvan 3500, Rayvan 2000, Rayvan 1500, Rayvan 1250, Rayvan 1200, Rayvan 1190ULTRA-II, Rayvan 1170, Rayvan 1255 (and above) Colombia), Black Pearls L, Regal 400R, Regal 330R, Legal 660R, Mogul L, Monarch 700, Monak 800, Monak 880, Monak 900, Monak 1000, Monak 1100, Monak 1300, Monak 1400, Monak 2000, Valcan XC-72R (above, Bot), Color Black FW1, Color Black FW2, Color Black FW2V, Color Black FW18, Color Black FW200, Color Black S150, Color Black S160, Color Black S170, Printex 35, Printex U, Printex V, Printex 140U, Printex 140V, Special Black 6, Special Black 5, Special Black 4A, Special Black 4 (above, manufactured by Degussa), No. 25, no. 33, no. 40, no. 47, no. 52, no. 900, no. Commercial products such as 2300, MCF-88, MA600, MA7, MA8, MA100 (above, manufactured by Mitsubishi Chemical Corporation) can be used. Carbon black newly prepared for the present invention can also be used. However, the present invention is not limited to these, and any conventionally known carbon black can be used.

Hereinafter, other components used in the ink according to the present invention will be described.
[Aqueous medium]
Examples of the aqueous medium that can be used in the present invention include water or a mixed solvent of water and a water-soluble organic solvent. As the water-soluble organic solvent, those having an ink drying preventing effect are particularly preferable. Specific examples of the water-soluble organic solvent include 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, and tert-butyl alcohol. Amides such as dimethylformamide and 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 and propylene glycol , Butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol, etc. Alkylene glycols having 2 to 6 carbon atoms in the alkylene group; lower alkyl ether acetates such as polyethylene glycol monomethyl ether acetate; glycerin; ethylene glycol monomethyl (or ethyl) ether, diethylene glycol methyl (or ethyl) ether, triethylene glycol Lower alkyl ethers of polyhydric alcohols such as monomethyl (or ethyl) ether; N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone and the like. The above water-soluble organic solvents can be used alone or as a mixture. As the water, it is desirable to use deionized water.

  The content of the water-soluble organic solvent as mentioned above in the ink according to the present invention is not particularly limited, but is preferably in the range of 3 to 50% by mass with respect to the total mass of the ink. The amount of water contained in the ink is preferably in the range of 50 to 95% by mass with respect to the total mass of the ink.

  In addition, in order to maintain the moisture retention of the ink, other moisture retention solids such as urea, urea derivatives, ethylene urea, trimethylolpropane, trimethylolethane may be used as the ink component. The content of moisturizing solids such as urea, urea derivatives, and trimethylolpropane in the ink is generally preferably in the range of 0.1 to 20.0% by weight, more preferably 3.0. It is the range of-10.0 mass%.

  Furthermore, in addition to the above components, the ink according to the present invention includes a surfactant, a pH adjuster, a rust inhibitor, an antiseptic, an antifungal agent, an antioxidant, an anti-reduction agent, and an evaporation accelerator as necessary. Various additives such as chelating agents may be contained.

  The ink according to the present invention having the above-described configuration can be used for writing instrument ink and inkjet ink. As an ink jet recording method, there are a recording method in which mechanical energy is applied to ink to eject droplets, and a bubble jet (registered trademark) recording method in which thermal energy is applied to ink and ink droplets are ejected by foaming of the ink. However, the ink of the present invention is particularly suitable for these recording methods.

  By the way, when the ink according to the present invention is used for the ink jet recording as described above, it is preferable that the ink has a characteristic of being ejected well from the ink jet recording head. For this reason, from the viewpoint of ejectability from the ink jet recording head, the ink characteristics are, for example, a viscosity of 1 to 15 mPa · s, a surface tension of 25 mN / m or more, and a viscosity of 1 to 5 mPa · s. The surface tension is preferably 25 to 50 mN / m.

  The ink of the present invention having the above-described configuration is particularly effective when used for inkjet recording. As the ink jet recording method, there are a recording method for ejecting ink by applying mechanical energy to the ink, and an ink jet recording method for ejecting ink by foaming of the ink by applying thermal energy to the ink. In particular, the pigment ink of the present invention is particularly suitable.

[Recording method, recording unit, ink cartridge, and recording apparatus]
Next, an example of an ink jet recording apparatus suitable for recording using the ink according to the present invention will be described below. First, FIG. 1 and FIG. 2 show an example of a head configuration which is a main part of an ink jet recording apparatus using thermal energy. FIG. 1 is a cross-sectional view of the head 13 along the ink flow path, and FIG. 2 is a cross-sectional view taken along line AB in FIG. The head 13 is obtained by adhering a heating element substrate 15 and a glass, ceramic, silicon or plastic plate having a flow path (nozzle) 14 through which ink passes. The heating element substrate 15 includes a protective layer 16 formed of silicon oxide, silicon nitride, silicon carbide, etc., electrodes 17-1 and 17-2 formed of aluminum, gold, aluminum-copper alloy, HfB ₂ , TaN, A heating resistor layer 18 formed of a high melting point material such as TaAl, a heat storage layer 19 formed of thermal silicon oxide, aluminum oxide, or the like, and a substrate 20 formed of a material with good heat dissipation such as silicon, aluminum, or aluminum nitride. It has become more.

  When a pulsed electric signal is applied to the electrodes 17-1 and 17-2 of the head 13, the region indicated by n of the heating element substrate 15 rapidly generates heat, and bubbles are generated in the ink 21 in contact with the surface. The pressure causes the meniscus 23 to protrude, and the ink 21 is ejected through the nozzles 14 of the head to form ink droplets 24 from the ejection orifices 22 and fly toward the recording material 25. FIG. 3 shows an external view of an example of a multi-head in which a large number of heads shown in FIG. 1 are arranged. This multi-head is made by adhering a glass plate 27 having multi-nozzles 26 and a heating head 28 similar to that described in FIG.

  FIG. 4 shows an example of an ink jet recording apparatus incorporating this head. In FIG. 4, reference numeral 61 denotes a blade as a wiping member, one end of which is held and fixed by a blade holding member, and forms a cantilever. The blade 61 is disposed at a position adjacent to the recording area by the recording head 65, and in the illustrated example, is held in a form protruding in the moving path of the recording head 65.

  Reference numeral 62 denotes a cap on the projection port surface of the recording head 65, which is disposed at a home position adjacent to the blade 61, moves in a direction perpendicular to the moving direction of the recording head 65, contacts the ink ejection port surface, and performs capping. The structure to perform is provided. Further, reference numeral 63 denotes an ink absorber provided adjacent to the blade 61 and, like the blade 61, is held in a form protruding in the moving path of the recording head 65. The blade 61, the cap 62, and the ink absorber 63 constitute an ejection recovery unit 64, and the blade 61 and the ink absorber 63 remove moisture, dust, and the like from the ejection port surface.

  Reference numeral 65 denotes a recording head which has discharge energy generating means and performs recording by discharging ink onto a recording material facing the discharge port surface on which the discharge port is arranged. Reference numeral 66 denotes a recording head mounted with the recording head 65. It is a carriage for moving. The carriage 66 is slidably engaged with the guide shaft 67, and a part of the carriage 66 is connected to a belt 69 (not shown) driven by a motor 68. As a result, the carriage 66 can move along the guide shaft 67, and the recording area and its adjacent area can be moved by the recording head 65.

  51 is a paper feeding unit for inserting a recording material, and 52 is a paper feed roller driven by a motor (not shown). With these configurations, the recording material is fed to a position facing the ejection opening surface of the recording head 65, and is discharged to a paper discharge portion provided with a paper discharge roller 53 as recording progresses. In the above configuration, when the recording head 65 finishes recording and returns to the home position, the cap 62 of the ejection recovery unit 64 is retracted from the moving path of the recording head 65, but the blade 61 protrudes into the moving path. As a result, the ejection port of the recording head 65 is wiped.

  When the cap 62 is in contact with the ejection surface of the recording head 65 to perform capping, the cap 62 moves so as to protrude into the moving path of the recording head. When the recording head 65 moves from the home position to the recording start position, the cap 62 and the blade 61 are at the same position as that at the time of wiping described above. As a result, the ejection port surface of the recording head 65 is wiped even during this movement. The above-mentioned movement of the recording head to the home position is not only at the end of recording or at the time of ejection recovery, but also to the home position adjacent to the recording area at a predetermined interval while the recording head moves the recording area for recording. Then, the wiping is performed with this movement.

  FIG. 5 is a diagram illustrating an example of an ink cartridge 45 that contains ink supplied to the recording head via an ink supply member, for example, a tube. Here, reference numeral 40 denotes an ink container, for example, an ink bag, in which supply ink is stored, and a rubber plug 42 is provided at the tip thereof. By inserting a needle (not shown) into the stopper 42, the ink in the ink bag 40 can be supplied to the head. An ink absorber 44 receives waste ink. The ink container preferably has a liquid contact surface made of polyolefin, particularly polyethylene.

  The ink jet recording apparatus used in the present invention is not limited to the one in which the head and the ink cartridge are separated as described above, but is preferably used in an apparatus in which they are integrated as shown in FIG. It is done. In FIG. 6, reference numeral 70 denotes a recording unit, in which an ink storage portion that stores ink, for example, an ink absorber is stored, and the ink in the ink absorber from the head portion 71 having a plurality of orifices. It is configured to be ejected as ink droplets. It is preferable for the present invention to use polyurethane as the material of the ink absorber. Alternatively, a structure may be used in which the ink container is an ink bag with a spring or the like inside without using an ink absorber. Reference numeral 72 denotes an atmosphere communication port for communicating the inside of the cartridge with the atmosphere. The recording unit 70 is used in place of the recording head 65 shown in FIG. 4 and is detachable from the carriage 66.

  Next, as a preferable example of an ink jet recording apparatus using 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 the 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. An example of the configuration of a recording head which is a main part of the recording apparatus is shown in FIG.

  The head includes an ink flow path 80 communicating with an ink chamber (not shown), an orifice plate 81 for ejecting ink droplets of a desired volume, a vibration plate 82 that directly applies pressure to ink, and the vibration plate 82. And a substrate 84 for supporting and fixing the orifice plate 81, the diaphragm 82 and the like.

  In FIG. 7, an ink flow path 80 is formed of a photosensitive resin or the like, an orifice plate 81 has a discharge port 85 formed by electroforming or punching a metal such as stainless steel or nickel, and the vibration plate 82 is The piezoelectric element 83 is formed of a dielectric material such as barium titanate or PZT. The piezoelectric element 83 is formed of a metal film such as stainless steel, nickel, or titanium and a highly elastic resin film. The recording head configured as described above applies a pulsed voltage to the piezoelectric element 83 to generate a distortion stress, and the energy deforms the vibration plate bonded to the piezoelectric element 83, so that the ink in the ink flow path 80 is obtained. Is pressed vertically and ink droplets (not shown) are ejected from the ejection ports 85 of the orifice plate 81 to perform recording. Such a recording head is used by being incorporated in an ink jet recording apparatus similar to that shown in FIG. The detailed operation of the ink jet recording apparatus can be performed in the same manner as described above.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. In the following description, “parts” and “%” are based on mass unless otherwise specified. First, pigment dispersions 1 to 4 were prepared as follows, and then inks of Examples 1 to 3 and Comparative Example 1 were prepared using the obtained pigment dispersions.

(Pigment dispersion 1)
Carbon black with a surface area of 230 m ² / g and DBP oil absorption of 70 ml / 100 g is used as the base carbon, and liquid phase oxidation is performed using ordinary sodium hypochlorite to bond carboxyl groups to the surface of the carbon black. An anionic self-dispersing carbon black was obtained. Next, a part of the carboxyl group on the surface of the carbon black was chemically bonded to polyethylene glycol HO (CH ₂ CH ₂ O) _n —H (n = 150) by a normal esterification reaction. Then, to obtain a carboxyl _{group, -COO (CH 2 CH 2 O} ) n -H (n = 150) and the group, the pigment dispersion 1 was chemically bonded on the carbon black surface (pigment content 10 wt%).

(Pigment dispersion 2)
10 g of commercially available acidic carbon black and 4 g of p-amino-N-benzenesulfonic acid were mixed well with 72 g of water, and then 1.62 g of nitric acid was added dropwise thereto and stirred at 70 ° C. Several minutes later, a solution of 1.1 g of sodium nitrite dissolved in 5 g of water was added, and the mixture was further stirred for 1 hour. The obtained slurry was Toyo Filter Paper No. 2 (manufactured by Advantis), the pigment particles were washed thoroughly with water, and as shown in the following formula, the surface was anionic with a sulfonic acid group which is a hydrophilic group bonded via a phenyl group. A charged self-dispersing carbon black was obtained.

Next, a hydroxyl group present on the surface of the self-dispersing carbon black and C ₂ H ₅ —O— (CH ₂ CH ₂ O) _n —CH ₂ —COOH (n = 100) are converted into ordinary esters. Chemical bonding was performed by a chemical reaction. Thus, a sulfonic acid group bonded via a phenyl group and a —OCOCH ₂ (OCH ₂ CH ₂ ) _n —O—C ₂ H ₅ group (n = 100) are chemically bonded on the surface of the carbon black. Pigment dispersion 2 (pigment content 10 mass%) was obtained.

(Pigment dispersion 3)
10 g of commercially available acidic carbon black and 3.06 g of 3-amino-N-ethylpyridinium bromide were mixed well with 72 g of water, and then 1.62 g of nitric acid was added dropwise thereto and stirred at 70 ° C. Several minutes later, a solution of 1.07 g of sodium nitrite dissolved in 5 g of water was added, and the mixture was further stirred for 1 hour. The obtained slurry was Toyo Filter Paper No. 2 (manufactured by Advantis), the pigment particles were sufficiently washed with water, and a cationically charged self-dispersing carbon black in which the hydrophilic group represented by the following formula was directly bonded to the surface was obtained.

Next, a hydroxyl group present on the surface of the self-dispersing carbon black and C ₆ H ₁₃ —O— (CH ₂ CH ₂ O) _n —CH ₂ —COOH (n = 70) are converted into ordinary esters. Chemical bonding was performed by a chemical reaction. Thus, the pigment dispersion 3 (pigment content 10) in which the hydrophilic group represented by the above formula and the —OCOCH ₂ (OCH ₂ CH ₂ ) _n —O—C ₆ H ₁₃ group (n = 70) were chemically bonded on the surface. Mass%).

(Pigment dispersion 4)
An anionic property in which a carbon black having a surface area of 230 m ² / g and a DBP oil absorption of 70 ml / 100 g is subjected to liquid phase oxidation using ordinary sodium hypochlorite, and a carboxyl group is bonded to the surface of the carbon black. Self-dispersing pigment dispersion (pigment content 10% by mass) was obtained.

(Preparation of inks of Examples 1 to 3 and Comparative Example 1)
Each pigment dispersion obtained above and the other components shown below were mixed and stirred well, and then filtered through a membrane filter having a pore size of 1.0 μm to obtain inks of Examples 1 to 3 and Comparative Example 1. The pigment dispersion used in each example and comparative example is as shown in Table 1 below.

(Ink composition)
・ Each pigment dispersion (10 mass%) 40 parts ・ Glycerin 8 parts ・ Ethylene glycol 8 parts ・ Acetylenol E100 (trade name, Kawaken Fine Chemical Co., Ltd.) 0.05 parts ・ Pure water remaining

<Evaluation>
Using an ink jet recording apparatus (trade name, BJS-700, manufactured by Canon), each ink of Examples 1 to 3 and Comparative Example 1 was injected into the black ink side of the ink cartridge, and an image was output. The obtained recorded matter was evaluated by the following methods and criteria. Table 2 summarizes the evaluation results.

(Print stain scratch resistance)
Each of the inks of Examples 1 to 3 and Comparative Example 1 was printed on nine types of plain paper, and the obtained image was left for 1 day, and then the printed portion was printed on Sylbon paper at a weight of 40 g / cm ^2. The rubbing and rubbing around the rubbing part were visually observed and evaluated by the following methods and standards. For plain paper, Canon PPC paper NSK, Canon PPC paper NDK, Canon plain paper SW101, Canon plain paper brilliant white paper, plain paper Canon-OFFICE, Xerox plain paper XEROX 4200, Hewlett Packard (HP) Nine papers made of plain paper HP bright white paper, plain paper Stein vice, plain paper hammer mill jet print were used.
○: Dirt is not noticeable with more than half of the paper.
X: Dirt is noticeable on all papers.

It is a longitudinal cross-sectional view of an inkjet recording device head. It is a cross-sectional view of an inkjet recording apparatus head. FIG. 2 is an external perspective view of a head in which the head shown in FIG. It is a perspective view which shows an example of an inkjet recording device. It is a longitudinal cross-sectional view of an ink cartridge. It is a perspective view which shows an example of a recording unit. FIG. 3 is a diagram illustrating an example of a configuration of a recording head.

Explanation of symbols

13: head 14: ink nozzle 15: heating element substrate 16: protective layer 17-1, 17-2: electrode 18: heating resistor layer 19: heat storage layer 20: substrate 21: ink 22: discharge orifice (micropore)
23: Meniscus 24: Ink droplet 25: Recording material 26: Multi-nozzle 27: Glass plate 28: Heat generating head 40: Ink bag 42: Plug 44: Ink absorber 45: Ink cartridge 51: Paper feed unit 52: Paper feed roller 53: Discharge roller 61: Blade 62: Cap 63: Ink absorber 64: Discharge recovery unit 65: Recording head 66: Carriage 67: Guide shaft 68: Motor 69: Belt 70: Recording unit 71: Head unit 72: Atmospheric communication Port 80: Ink channel 81: Orifice plate 82: Vibration plate 83: Piezoelectric element 84: Substrate 85: Ejection port

Claims (12)

In the pigment ink containing a pigment, the pigment has two kinds of atoms on the surface, one or several kinds of atomic groups represented by the following structural formula (I) and an atomic group containing at least an alkylene oxide chain A pigment ink characterized by having a group.

(However, M in the above formula represents a hydrogen atom, an alkali metal, ammonium or organic ammonium, and R ₁ is an alkyl group having 1 to 12 carbon atoms, an optionally substituted phenyl group or a substituted group. Represents an optionally substituted naphthyl group.)   The pigment ink according to claim 1, wherein the alkylene oxide chain is an ethylene oxide chain (n = 10 to 300). The pigment ink according to claim 1, wherein the atomic group containing an alkylene oxide chain is any one of the atomic groups represented by the following structural formula (II).

(However, R ₂ in the formula represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an optionally substituted phenyl group, or an optionally substituted naphthyl group, and n = 10. Represents ~ 300.)   The pigment ink according to any one of claims 1 to 3, wherein the pigment is carbon black.   The color recording ink set having black, yellow, magenta, and cyan inks, wherein at least one ink is the ink according to any one of claims 1 to 3. set.   An ink cartridge comprising an ink tank containing the ink according to any one of claims 1 to 4.   A recording unit comprising: an ink containing portion containing the ink according to any one of claims 1 to 4; and a head portion for discharging the ink.   7. An image recording apparatus comprising: the ink cartridge according to claim 6; a recording head for discharging ink; and means for supplying ink from the ink cartridge to the recording head.   An image recording apparatus comprising the recording unit according to claim 7.   5. An image comprising: an ink storage unit storing the ink according to claim 1; and a head unit for discharging each of the ink stored in each ink storage unit. Recording device.   An ink cartridge including an ink storage portion that stores the ink according to any one of claims 1 to 4, a head portion that discharges ink stored in each ink storage portion, and each ink. An image recording apparatus comprising means for supplying each head part from each ink cartridge.   An ink jet recording method comprising: recording an image by causing the ink according to any one of claims 1 to 4 to fly toward the surface of a recording medium and depositing the ink on the surface of the recording medium.

Images