JP2005350561A - Pigment ink, ink set using the same, ink cartridge, printing unit, image-printing device and inkjet-printing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pigment ink having superior abrasion resistance and resistance to marking pens and capable of achieving an image of less reduction in image density, and to provide an ink set using the same, an ink cartridge, a printing unit, an image-printing device and an inkjet-printing method. <P>SOLUTION: This pigment ink comprises a pigment, wherein the pigment contains two kinds of atomic groups, on its surface, of at least one atomic group (I) selected from structural formula (I) and an atomic group (II) having a polymeric chain composed of a copolymer obtained from at least one hydrophilic monomer with ionicity and at least one hydrophobic monomer. The ink set using the same, the ink cartridge, the printing unit, the image-printing device and the inkjet-printing method are provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pigment ink (recording liquid), an ink set, an ink cartridge, a recording medium 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 a unit, an image recording 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 using organic pigments or carbon black instead of dyes have been proposed.

  However, when an organic pigment or carbon black is used in place of a dye as an ink coloring material, the scratch resistance and marker resistance of the formed image (for example, the image is rubbed with a finger or a marker is applied to the image). When a pen is used, there is a problem that the property of not causing rubbing or 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 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, the reliability of the ink for the recording head can be ensured, but there is room for further improvement in the scratch resistance and marker 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 and marker resistance.
In order to improve the scratch resistance and marker resistance of an image printed by ink jet 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, when such highly penetrable ink is used, there is an adverse effect that the image density of the printed matter tends to decrease.

  Accordingly, an object of the present invention is to provide a pigment ink (hereinafter referred to as ink) that can obtain an image with a small decrease in image density while maintaining excellent scratch resistance and marker resistance. . Another object of the present invention is to provide an image recording apparatus, an ink jet recording method, an ink cartridge and a recording unit used in the image recording apparatus, which can stably form an image with high image density and high color development.

  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 comprises at least one atomic group (I) selected from the following structural formula (I) and at least one hydrophilic monomer having an ionicity: Pigment ink having two types of atomic groups of atomic group (II) including a polymer chain which is a copolymer with at least one hydrophobic monomer on the surface, an ink set using the ink, and an ink A cartridge, a recording unit, an image recording apparatus, and an ink jet recording method.

（但し、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。）

(However, M in the 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, or a phenyl group or substituent that may have a substituent. Represents a naphthyl group which may have

  Since the ink according to the present invention contains a self-dispersing pigment having a specific configuration, when an image is formed with the ink, excellent scratch resistance and marker resistance are maintained, and the image density is high. It is possible to obtain a recorded matter (printed matter) that does not decrease the image quality.

  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 (I) and (II) 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.

  First, at least two types of atomic groups (I) and (II) having the above specific structure that are chemically bonded to the pigment surface will be described. The first atomic group (I) is at least one selected from atomic groups represented by the following structural formula (I).

Here, M in the above formula represents a hydrogen atom, an alkali metal, ammonium or organic ammonium, and R ₁ represents an alkyl group having 1 to 12 carbon atoms, a phenyl group which may have a substituent, or The naphthyl group which may have a substituent is represented. Examples of the alkali metal include Li, Na, K, Rb, and Cs. Examples of organic ammonium include methylammonium, dimethylammonium, trimethylammonium, ethylammonium, diethylammonium, triethylammonium, monohydroxymethylamine, dihydroxymethylamine, trihydroxymethylamine, ethanolammonium, diethanolammonium, triethanolammonium and the like. Can be mentioned. The bonding amount of the atomic group is not particularly limited as long as it is a sufficient amount to disperse the pigment stably.

  Further, the method of chemically bonding the atomic group (I) to the pigment may be carried out by a commonly used method, and is not particularly limited. The atomic group (I) represented by any one of the structural formulas (I) can be obtained by, for example, a method of introducing an ionic functional group into carbon by sandwiching phenylene by an azo coupling method, or a conventionally known ozone treatment. It can be introduced onto the pigment surface by an oxidation treatment method such as plasma treatment or liquid phase oxidation treatment. However, it is not necessarily limited to these manufacturing methods.

  The second atomic group (II) comprises a polymer chain that is a copolymer of at least one ionic hydrophilic monomer and at least one hydrophobic monomer. Examples of the polymer chain that is a copolymer composed of a hydrophilic monomer and a hydrophobic monomer include an anionic polymer having an anionic property or a cationic polymer having a cationic property.

  Examples of the anionic polymer include a polymer chain that is a copolymer of a hydrophobic monomer and a hydrophilic monomer, or a salt thereof. Typical hydrophobic monomers that can be used in this case include the following monomers, but the present invention is not limited to these. Specifically, for example, methacrylic acid alkyl esters such as styrene, vinyl naphthalene and methyl methacrylate, phenyl methacrylate, benzyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, 2-ethoxyethyl methacrylate, methacrylonitrile, 2-trimethylsiloxyethyl Methacrylate, glycidyl methacrylate, p-tolyl methacrylate, sorbyl methacrylate, methyl acrylate, n-butyl acrylate and other acrylic acid alkyl esters, phenyl acrylate, benzyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, acrylonitrile, 2-trimethylsiloxyethyl acrylate Glycidyl acrylate, p-tolylua A Relate and sorbyl acrylate.

  In addition, typical hydrophilic monomers that can be used in this case include the following monomers, but are not limited thereto. For example, acrylic acid, methacrylic acid, maleic acid, styrene sulfonic acid and the like can be mentioned.

  As a suitable anionic polymer constituting the atomic group (II), a block copolymer consisting of at least two monomers selected from the hydrophobic monomers and / or hydrophilic monomers (of which at least one is a hydrophilic monomer) Examples thereof include a polymer, a random copolymer, a graft copolymer, or a salt thereof. In addition, the acid value of the anionic polymer is preferably in the range of 100 to 400, and the variation of the acid value is preferably within 10% of the average acid value. Examples of the salt include alkali metal salts such as sodium, lithium and potassium, as well as ammonium salts, alkylamine salts, alkanolamine salts and the like, and these can be used alone or in combination of several kinds.

  Examples of the cationic polymer constituting the atomic group (II) in the present invention include a copolymer composed of a hydrophobic monomer and a hydrophilic monomer, or a salt thereof. Typical hydrophobic monomers that can be used in this case include the following monomers, but the present invention is not limited to these. Specific hydrophobic monomers include, for example, methacrylic acid alkyl esters such as styrene, vinyl naphthalene, methyl methacrylate, phenyl methacrylate, benzyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, 2-ethoxyethyl methacrylate, methacrylonitrile, 2 -Acrylic acid alkyl esters such as trimethylsiloxyethyl methacrylate, glycidyl methacrylate, p-tolyl methacrylate, sorbyl methacrylate, methyl acrylate, phenyl acrylate, benzyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, acrylonitrile, 2-trimethylsiloxyethyl acrylate, Glycidyl acrylate, p-tolyl acrylate Over preparative and sorbyl acrylate.

  Examples of hydrophilic monomers include, but are not limited to, the following monomers. Specifically, for example, allylamine, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, 3-butylaminoethyl methacrylate, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, dimethylaminopropyl methacrylamide, N-vinylcarbazole, methacrylamide, acrylamide And dimethylacrylamide.

  In the present invention, the cationic polymer capable of constituting the atomic group (II) used for the surface modification of the pigment is at least two monomers selected from the above monomers (of which at least one is a hydrophilic monomer) Or a random copolymer, a graft copolymer, or a salt thereof. The amine value is preferably in the range of 100 to 400, and the variation of the amine value is preferably within 10% of the average amine value. Here, the amine value is expressed in mg of KOH equivalent to hydrochloric acid required to neutralize 1 g of the sample.

  In the present invention, each polymer composed of the above-mentioned materials constituting the atomic group (II) preferably has a weight average molecular weight in the range of 1,000 to 30,000, and more preferably 3,000 to 20,000. The thing of the range of is preferable. The content of the polymer with respect to the pigment is preferably 5% by mass or more and 40% by mass or less with respect to the pigment whose surface is modified by the atomic group (II) containing the polymer. More preferably, it is used in a proportion of 10% by mass or more and 25% by mass or less. For this reason, when the content of the polymer with respect to the surface-modified pigment is high, the viscosity of the ink is increased by the bonded polymer, which is not preferable. On the other hand, when the content of the bonded polymer is low, the pigment surface cannot be effectively covered with the atomic group (II) containing the polymer, and dispersion stability cannot be obtained. Further, the effect of the present invention is not sufficiently exhibited by chemically bonding the atomic group (II) containing the polymer to the surface of the pigment. Similarly, when the weight average molecular weight of the atomic group (II) containing the polymer used for the surface modification of the pigment is too high, the viscosity of the ink is increased, which is not preferable. On the other hand, when the weight average molecular weight is too low, the effect of the present invention is not sufficiently exhibited by chemically bonding the atomic group (II) containing the polymer to the surface of the pigment.

  The ionic group contained in at least one atomic group (I) selected from the structural formula (I) and the ionic group in the monomer used for the polymer constituting the atomic group (II) are the same. Preferably there is. When the atomic groups (I) and (II) that modify the pigment surface are combined with different ionic groups, it may be disadvantageous in terms of ink stability, which is not preferable.

  In addition, as a method of chemically bonding the atomic group (II) containing the polymer used in the present invention to the pigment surface, for example, using a hydrophilic monomer and a hydrophobic monomer as described above, the terminal group is used. For example, a method of directly grafting to a carbon surface after synthesizing a polymer having an aminophenyl group is used, but the method is not limited thereto.

  By using a pigment in which at least two types of atomic groups having the specific structure as described above are chemically bonded to the pigment surface as described above, depending on the type of the recording medium. It is possible to obtain an ink capable of forming a high-quality image stably without greatly deteriorating the image density and color developability and without greatly changing the image quality. In addition, the pigment used in the present invention is self-dispersible because the surface is modified as described above, and has a scratch resistance compared to an ink in which the pigment is dispersed using a dispersant. A good image is obtained.

  The detailed mechanism by which such an ink exhibits the above-mentioned properties is not clear at present, but in the ink, the ink is stably stabilized by at least one atomic group (I) selected from the structural formula (I). When the existing pigment particles are printed on the recording medium, the atomic groups (I) are encapsulated in another atomic group (II) present on the surface of the pigment. We believe that this is because the binding power between each other increases.

  In addition, the production of the pigment having the surface modified as described above used in the present invention is based on, for example, the following carbon black as the base carbon, and the above-described atomic group (I) And (II) can be introduced. Examples of the carbon black pigment include carbon black pigments such as furnace black, lamp black, acetylene black, and channel black. Specifically, for example, Raven 7000, Rayvan 5750, Rayvan 5250, Rayvan 5000, Rayvan 3500, Rayvan 2000, Rayvan 1500, Rayvan 1250, Rayvan 1200, Rayvan 1190ULTRA-II, Rayvan 1170, Rayvan 1255 (or more, 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, Valcan XC-72R (above, manufactured by Cabot), Color Black ( 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. 2300, MCF-88, MA600, MA7, MA8, MA100 (above, manufactured by Mitsubishi Chemical Corporation) can be used, but is not limited thereto. It is also possible to use conventionally known carbon black.

  Moreover, as a pigment used by this invention, the organic pigments listed below can also be used. Specifically, for example, insoluble azo pigments such as toluidine red, toluidine maroon, Hansa yellow, benzidine yellow, and pyrazolone red; soluble azo pigments such as lithol red, heliobordeaux, pigment scarlet, and permanent red 2B; alizarin, indanthrone Derivatives from vat dyes such as thioindigo maroon; Phthalocyanine pigments such as phthalocyanine blue and phthalocyanine green; Quinacridone pigments such as quinacridone red and quinacridone magenta; Perylene pigments such as perylene red and perylene scarlet; Isoindolinone yellow , Isoindolinone pigments such as isoindolinone orange; imidazolones such as benzimidazolone yellow, benzimidazolone orange and benzimidazolone red Materials: Pilanthrone pigments such as pyranthrone red, pyranthrone orange; indigo pigments; condensed azo pigments; thioindigo pigments; flavanthrone yellow, acylamide yellow, quinophthalone yellow, nickel azo yellow, copper azomethine yellow, perinone orange And other pigments such as Anthrone Orange, Dianthraquinonyl Red and Dioxazine Violet.

  Moreover, when an organic pigment is shown by a color index (CI) number, for example, C.I. I. Pigment Yellow 12, 13, 14, 17, 20, 24, 74, 83, 86, 93, 109, 110, 117, 120, 125, 137, 138, 147, 148, 151, 153, 154, 166, 168; C. I. Pigment orange 16, 36, 43, 51, 55, 59, 61; C.I. I. Pigment Red 9, 48, 49, 52, 53, 57, 97, 122, 123, 149, 168, 175, 176, 177, 180, 192, 215, 216, 217, 220, 223, 224, 226, 227, 228, 238, 240; C.I. I. Pigment violet 19, 23, 29, 30, 37, 40, 50; C.I. I. Pigment Blue 15, 15: 1, 15: 4, 15: 6, 22, 60, 64; C.I. I. Pigment green 7, 36; I. Pigment brown 23, 25, 26, and the like. Of course, conventionally known organic pigments can be used in addition to the above.

  The method for analyzing the surface modification state of the pigment used in the present invention is not particularly limited, and the analysis can be performed using a method that can be generally considered. Preferably, a method for analyzing the chemical bonding state of the pigment surface whose surface has been modified by ESCA, TOF-SIMS, or the like can be used.

As described above, the ink according to the present invention is characterized by using a pigment whose surface is modified by chemically bonding two types of specific atomic groups to the surface. This is the same as the water-based ink component. Examples of other components include an aqueous medium and various additives.
Examples of the aqueous medium used in the ink according to the present invention include water or a mixed solvent of water and a water-soluble organic solvent. It is desirable to use deionized water as the water. As the water-soluble organic solvent, those having an ink drying preventing effect are particularly preferable. Specifically, for example, alkyl alcohols having 1 to 4 carbon atoms such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol; dimethylformamide, Amides such as dimethylacetamide; Ketones or ketoalcohols such as acetone and diacetone alcohol; Ethers such as tetrahydrofuran and dioxane; Polyalkylene glycols such as polyethylene glycol and polypropylene glycol; Ethylene glycol, propylene glycol, butylene glycol, tri 2 to 6 alkylene groups such as ethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol Polyols containing carbon atoms; lower alkyl ether acetates such as polyethylene glycol monomethyl ether acetate; glycerin; many such as ethylene glycol monomethyl (or ethyl) ether, diethylene glycol methyl (or ethyl) ether, triethylene glycol monomethyl (or ethyl) ether Lower alkyl ethers of monohydric alcohols; polyhydric alcohols such as trimethylolpropane and trimethylolethane; N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone and the like. The water-soluble organic solvents as described above can be used alone or as a mixture.

  The amount of the water-soluble organic solvent contained in the ink of 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.

  Further, in order to maintain the moisture retention of the ink, moisture retaining solids such as urea, urea derivatives, trimethylolpropane, and trimethylolethane may be used as the ink component. The content of moisturizing solids such as urea, urea derivatives, trimethylolpropane, etc. in the ink is generally preferably in the range of 0.1 to 20.0% by weight, more preferably 3.0 to 10%. It is in the range of 0% by mass.

  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 an agent and a chelating agent may be contained.

（但し、上記構造式（１）中、Ｒはアルキルを表し、ｎは整数を表す。） The surfactant preferably contains any of the surfactants represented by the following structural formulas (1) to (4).

(In the structural formula (1), R represents alkyl and n represents an integer.)

（但し、上記構造式（２）中、Ｒはアルキル基を表し、ｎは整数を表す。）

(In the structural formula (2), R represents an alkyl group, and n represents an integer.)

（但し、上記構造式（３）中、Ｒは水素原子又はアルキル基を表し、ｍ及びｎは、夫々整数を表す。）

(In the structural formula (3), R represents a hydrogen atom or an alkyl group, and m and n each represents an integer.)

（但し、上記構造式（４）中、ｍ及びｎは、夫々整数を表す。）

(In the structural formula (4), m and n each represents an integer.)

  The ink according to the present invention can be used for ink for writing instruments and ink for inkjet recording. As an ink jet recording system, there are a recording system in which mechanical energy is applied to ink to eject ink droplets, and a recording system in which thermal energy is applied to ink and ink droplets are ejected by foaming of the ink. In any case, the ink of the present invention is particularly suitable.

  When the ink of the present invention is used for inkjet recording, it is preferable that the ink has a characteristic that it can be ejected from an inkjet head. From the viewpoint of ejection properties from an inkjet head, the ink characteristics include, for example, a viscosity of 1 to 15 cps (mPa · s), a surface tension of 25 dyn / cm (mN / m) or more, and particularly a viscosity of 1 to 5 cps (mPa · s) and a surface tension of 25 to 50 dyn / cm (mN / m) are preferable.

  Next, an ink jet recording technique that can suitably use the ink according to the present invention having the configuration described above will be described. Examples of the image forming apparatus to which the ink according to the present invention can be preferably applied include an ink jet recording apparatus as described below. First, an ink jet recording apparatus using thermal energy as ink ejection means will be described. An example of a head configuration which is a main part of the apparatus is shown in FIGS.

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 made of silicon oxide, silicon nitride, silicon carbide, etc., electrodes 17-1, 17-2 made of aluminum, gold, aluminum-copper alloy, etc., 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, etc., and a substrate 20 formed of a material having good heat dissipation such as silicon, aluminum, aluminum nitride. It is made up of 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 meniscus 23 protrudes with the generated pressure, the ink is ejected through the nozzle 14 of the head 13, becomes an ink droplet 24 from the ejection orifice 22, and flies toward the recording material 25.

  FIG. 3 shows an external view of a multi-head in which a large number of heads as 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 such a 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 this example, is held in a form protruding in the moving path of the recording head 65.

  Reference numeral 62 denotes a cap on the protruding port surface of the recording head 65, which is disposed at the home position adjacent to the blade 61, moves in a direction perpendicular to the moving direction of the recording head 65, contacts the ink discharge port surface, and capping. The structure which performs is provided. Further, 63 is an ink absorber provided adjacent to the blade 61 and, like the blade 61, is held in a form protruding in the movement 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 ports are arranged. Reference numeral 66 denotes a recording head on which the recording head 65 is mounted. A carriage for moving the head 65. 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. Accordingly, the carriage 66 can move along the guide shaft 67, and the recording area by the recording head 65 and its adjacent area can be moved. Reference numeral 51 denotes a paper feed unit for inserting a recording material, and 52 denotes a paper feed roller driven by a motor (not shown).

  With these configurations, the recording material is fed to a position facing the discharge port surface 65 of the recording head, and is discharged to a paper discharge unit 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. Yes. 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 65. When the recording head 65 moves from the home position to the recording start position, the cap 62 and the blade 61 are in the same position as the above-described wiping position. As a result, the ejection port surface of the recording head 65 is wiped even during this movement.

  The above-described movement of the recording head 65 to the home position is not only at the end of recording or at the time of ejection recovery, but also at the home position adjacent to the recording area at a predetermined interval while the recording head 65 moves the recording area for recording. The wiping is performed along 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, such as a tube. Reference numeral 40 denotes an ink container, for example, an ink bag, which stores ink for supply, and a rubber plug 42 is provided at the tip of the ink container. By inserting a needle (not shown) into the stopper 42, the ink in the ink bag 40 can be supplied to the head. Reference numeral 44 denotes an ink absorber that receives waste ink. As the ink storage portion, a liquid contact surface with ink is preferably formed of polyolefin, particularly polyethylene.

  The ink jet recording apparatus is not limited to the one in which the head and the ink cartridge are separated as described above, and an apparatus in which they are integrated as shown in FIG. 6 is also preferably used. In FIG. 6, reference numeral 70 denotes a recording unit, in which an ink containing portion containing ink, for example, an ink absorber is accommodated, and the ink in the ink absorber is a head portion 71 having a plurality of orifices. The ink is discharged as ink droplets. As the material for the ink absorber, polyurethane is preferably used.

  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.

  Second, as an ink jet recording apparatus using mechanical energy as an ink discharge means, a nozzle forming substrate having a plurality of nozzles, a piezoelectric material disposed opposite to the nozzles, and a conductive material are used. An on-demand ink jet recording head that includes a pressure generating element and ink filling the periphery of the pressure generating element, displaces the pressure generating element by an applied voltage, and discharges a small droplet of ink from a nozzle. FIG. 7 shows a configuration example of a recording head which is a main part of the recording apparatus.

  The head includes an ink flow path 80 communicating with an ink chamber (not shown), an orifice plate 81 for ejecting ink droplets having a desired volume, a vibration plate 82 that directly applies pressure to ink, and the vibration plate. A piezoelectric element 83 that is bonded to 82 and is displaced by an electric signal, and a substrate 84 that supports and fixes 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, and an orifice plate 81 has a discharge port 85 formed by electroforming or punching a metal such as stainless steel or nickel. 82 is formed of a metal film such as stainless steel, nickel, or titanium, and a highly elastic resin film. The piezoelectric element 83 is formed of a dielectric material such as barium titanate or PZT.

  The recording head configured as described above applies a pulsed voltage to the piezoelectric element 83 to generate strain stress, and the energy deforms the vibration plate 82 bonded to the piezoelectric element 83, so that An operation is performed so that ink is vertically pressurized 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 a recording apparatus similar to that shown in FIG. The detailed operation of the recording apparatus can be performed in the same manner as described above.

  Next, in the case of recording a color image using a color recording ink set having black, cyan, magenta, yellow, etc. using the ink of the present invention, for example, as shown in FIG. A recording head 90 in which four multi-recording heads are arranged on a carriage can be used. FIG. 9 shows an example thereof, and reference numerals 91, 92, 93, and 94 denote recording units for ejecting yellow, magenta, cyan, and black inks, respectively. The recording units 91, 92, 93, and 94 are disposed on the carriage of the above-described recording apparatus and eject ink of each color according to a recording signal.

  FIG. 9 shows an example in which four recording units are used. However, the present invention is not limited to this. For example, as shown in FIG. 8, an ink cartridge 86 containing each of the above four color inks with one recording head, There is also an aspect in which recording is performed by attaching to a recording head 95 configured by dividing the ink flow path so that each color ink supplied from 87, 88 and 89 can be individually ejected.

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.
[Pigment dispersion A]
The following example shows an atomic group (II-1) having the following structure obtained using 4-aminobenzoic acid and an atomic group (II-) containing a polymer chain composed of an n-butyl acrylate / methacrylic acid copolymer. 1) discloses the preparation of a dispersion in which a surface-modified carbon black pigment chemically bonded to the surface of carbon black is dispersed in an aqueous medium.

(Modification with 4-aminobenzoic acid)
300 g of carbon black having a surface area of 220 m ² / g and a DBP oil absorption of 112 ml / 100 g was placed in a batch pin mixer heated to 70 ° C. 4-aminobenzoic acid (13.0 g) was added there. Mixing was started and an aqueous solution of sodium nitrite (6.21 g of sodium nitrite dissolved in 107.3 g of water) was added with mixing. Total mixing time was approximately 5 minutes. Mixing was then stopped and the material was removed from the batch pin mixer and cooled to room temperature. The resulting was then redispersed with 15% solids in water, adjusted to pH about 8.5 using sodium hydroxide and microfiltered to 0.5 μm (0.5 microns).

(Modification by an atomic group containing a polymer chain composed of an n-butyl acrylate / methacrylic acid copolymer)
First, a polymer derivative for bonding to the carbon black surface was prepared by the following steps. First, 190 g of an n-butyl acrylate / methacrylic acid copolymer having a weight average molecular weight of 8,000, an acid value of 180, and a polydispersity Mw / Mn = 1.9 (Mw: weight average molecular weight, Mn: number average molecular weight). Weighed, 1,800 g of distilled water was added thereto, NaOH necessary for neutralizing the resin was added, and the mixture was stirred and dissolved to prepare an aqueous solution of n-butyl acrylate / methacrylic acid resin. Next, 500 g of a pentaethylenehexamine (PEHA) solution having a concentration of 1/10 of this aqueous solution was dropped. At this time, the resin aqueous solution was vigorously stirred. The dropping mixture prepared as described above was transferred to a Pyrex (registered trademark) evaporating dish, heated at 150 ° C. for 15 hours, evaporated, and then the evaporated dried product was cooled to room temperature. As described above, a polymer in which a polymer chain composed of a copolymer of n-butyl acrylate and methacrylic acid and PEHA were combined was prepared.

  Next, the evaporated dry product (polymer) obtained above was dissolved at a concentration of 10% in NaOH-added distilled water adjusted to pH = 9.0, and then 5% of aminophenyl-2-sulfoethyl-sulfone (APSES). An aqueous solution was added dropwise. The input amount of 5% aqueous solution of aminophenyl-2-sulfoethyl-sulfone (APSES) was set to be 1 times the amount of the resin aqueous solution, and the solution was dripped over 1 hour while keeping at room temperature with vigorous stirring. The mixture was stirred for 18 to 48 hours and purified to remove impurities.

  As described above, aminophenyl-2-sulfoethyl-sulfone (APSES), PEHA, and an aminophenyl group at the terminal formed by bonding a polymer chain made of n-butyl acrylate / methacrylic acid copolymer. A polymer (hereinafter referred to as a binding polymer) was prepared.

  Subsequently, the binding polymer obtained above was modified by further linking to carbon black previously modified with 4-aminobenzoic acid. That is, 200 g of carbon black modified with 4-aminobenzoic acid obtained as described above and 1,000 g of a 5% aqueous solution of the binding polymer obtained above were charged into a reactor and kept at 55 ° C., The mixture was stirred for 20 minutes at 300 rpm. Thereafter, 30 g of 25% sodium nitrite was added dropwise for 15 minutes, and 100 g of distilled water was further added. Then, it was made to react for 2 hours, keeping at 60 degreeC. Then, with further stirring, 1.0 M NaOH is added to adjust the pH to 10-11, and then desalting, purification to remove impurities, and coarse particle removal are performed to obtain two types of atomic groups. A pigment dispersion A obtained by chemically bonding was obtained. The physical properties of the obtained pigment dispersion A were a solid content concentration of 10%, pH = 10.2, and an average particle size of 125 nm.

[Pigment dispersion B]
In creating the binding polymer to be used, instead of n-butyl acrylate / methacrylic acid copolymer, benzyl methacrylate / acrylic acid copolymer (weight average molecular weight 5,000, acid value 250, Mw / Mn = 1.95) A surface-modified carbon black was prepared using the same treatment method as that for preparing the pigment dispersion A, except that the content was changed to 1. On the surface of the modified carbon black, an atomic group (I-1) having the structure described above introduced by modification with 4-aminobenzoic acid and a polymer chain composed of a benzyl methacrylate / acrylic acid copolymer are provided. The polymer (II-2) to be contained is chemically bonded to the surface. The physical properties of the obtained pigment dispersion B were a solid content concentration of 10%, pH = 10.1, and an average particle size of 128 nm.

[Pigment dispersion C]
A pigment dispersion liquid was used except that polyacrylic acid (weight average molecular weight 10,000, Mw / Mn = 2.0) was used instead of n-butyl acrylate / methacrylic acid copolymer in the production of the binding polymer to be used. Surface-modified carbon black was prepared using the same treatment method as that used to prepare A. On the surface of the modified carbon black, the atomic group (I-1) having the structure described above introduced by the modification with 4-aminobenzoic acid and the atomic group containing polyacrylic acid are chemically formed on the surface. Combining. The physical properties of the obtained pigment dispersion C were a solid content concentration of 10%, pH = 10.0, and an average particle size of 130 nm.

[Pigment dispersion D]
A modified carbon black was prepared using only the above-mentioned 4-aminobenzoic acid obtained in the preparation of the pigment dispersion A, and a pigment dispersion D was obtained. The physical properties of the obtained pigment dispersion D were a solid content concentration of 10%, pH = 8.5, and an average particle size of 120 nm.

<Preparation of ink>
The following composition containing the pigment dispersion A obtained above was mixed and stirred well, and then filtered through a membrane filter having a pore size of 1.0 μm to prepare an ink of this example.

(Example 1)
-Pigment dispersion A 40 parts-Glycerol 8 parts-1,5-pentanediol 5 parts-Trimethylolpropane 6 parts-Acetylene glycol EO adduct 0.2 parts (trade name; acetylenol EH, Kawaken Fine Chemical Co., Ltd. ) Made)
・ 40.8 parts of ultrapure water

(Example 2)
Ink was produced with the same composition as Example 1 except that Pigment Dispersion A was changed to Pigment Dispersion B, and the ink of Example 2 was obtained.

(Comparative Example 1)
Ink was produced with exactly the same composition except that Pigment Dispersion A was changed to Pigment Dispersion C in Example 1 to obtain an ink of Comparative Example 1.

(Comparative Example 2)
Ink was produced with exactly the same composition except that Pigment Dispersion A was changed to Pigment Dispersion D in Example 1, and the ink of Comparative Example 2 was obtained.

<Evaluation>
For the inks of the examples and comparative examples obtained above, the tests described below were performed and evaluated according to the following criteria.

[Print stain scratch resistance]
Each ink was mounted on an ink jet recording apparatus (Pixus 850i manufactured by Canon), and printing was performed on each of the following five types of copy plain papers A to E. Each image obtained was allowed to stand for one day, and then the printed portion was rubbed against Silbon paper 5 times with a load of 40 g / cm ² , and the stain near the rubbed portion was visually observed and evaluated according to the following criteria. did.
(Evaluation criteria)
○: Dirt is not noticeable on all papers.
Δ: Contamination is noticeable on some paper.
X: Dirt is noticeable on all papers.

(Type of paper used)
A: Canon PPC paper NSK
B: Canon PPC paper NDK
C: Xerox PPC paper 4024
D: Fox River PPC paper Prober Bond E: Neuzidora PPC paper for Canon

[Print stain marker resistance]
Each ink was mounted on the same ink jet recording apparatus (Pixus 850i manufactured by Canon) as used previously, and printing was performed on the same five types of plain papers A to E as used previously. Then, after leaving the obtained images for one day, the printed part is marked using a commercially available aqueous fluorescent marker pen (for example, a fluorescent pen OPTEX OP-100-Y made by Zebra), and the marking part is visually checked. And evaluated according to the following criteria.
(Evaluation criteria)
○: Dirt is not noticeable on all papers.
Δ: Contamination is noticeable on some paper.
X: Dirt is noticeable on all papers.

It is a longitudinal cross-sectional view of an inkjet recording device head. FIG. 2 is a cross-sectional view taken along line AB in FIG. 1. 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. 10 is a diagram illustrating another example of the configuration of the recording head. FIG. 3 is a schematic explanatory diagram of a recording head to which four ink cartridges are attached. FIG. 3 is a schematic perspective view showing a configuration in which four recording heads are arranged on a carriage.

Explanation of symbols

13: head 14: 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: ejection orifice (micropore)
23: Meniscus 24: Ink droplet 25: Recording medium 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: ejection recovery unit 65: recording head 66: carriage 67: guide shaft 68: motor 69: belt 70: recording unit 71: head unit 72: air communication port 80: Ink channel 81: Orifice plate 82: Vibration plate 83: Piezoelectric element 84: Substrate 85: Ejection ports 86, 87, 88, 89: Ink cartridge 90: Recording heads 91, 92, 93, 94: Recording unit

Claims (12)

In a pigment ink containing a pigment, the pigment comprises at least one atomic group (I) selected from the following structural formula (I), a hydrophilic monomer having at least one ionicity, and at least one hydrophobic monomer. A pigment ink characterized in that it has two kinds of atomic groups (II) including a polymer chain, which is a copolymer thereof, on the surface.

(However, M in the 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, or a phenyl group or substituent that may have a substituent. Represents a naphthyl group which may have   The weight average molecular weight of the polymer chain constituting the atomic group (II) is in the range of 1,000 or more and 30,000 or less, and the acid value or amine value of the polymer chain is 100 or more and 400 or less. The pigment ink according to 1.   The pigment ink according to claim 1, wherein the ionic group of the hydrophilic monomer having at least one ionicity is the same as the ionic group in the atomic group (I).   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