JP2006160930A - Ink composition, ink set, image recording apparatus and image recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink composition that can give a high image density and a good print grade to an image formed on various recording media, achieves excellent rub-off resistance and excellent line marker resistance, and exhibits excellent inkjet ejection properties in a print head wherein there is formed a water-repellent area at at least an area around the periphery of an ejection opening on the ejection opening forming face of the print head, to provide an ink set comprising the ink composition in combination with a reaction liquid and to provide an image recording apparatus and an image recording method. <P>SOLUTION: The ink composition is an ink composition which is used in combination with a reaction liquid for aggregating an ink composition and comprises a self-dispersing pigment having on its surface an anionic group chemically bonded to the surface and an acrylic polymer wherein the acrylic polymer has an acid value of 250 or less; and the acrylic polymer has a specific structure. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ink composition, an ink set, an image recording method, and an image recording method suitable for writing instruments such as water-based ballpoint pens, fountain pens, and water-based sign pens, and inkjet printers.

  Inkjet recording, which has the feature that high-resolution and high-quality images can be printed at high speed with an inexpensive device, is a printing method in which droplets of an ink composition are ejected and attached to a recording medium such as paper. Is the method. As a means for forming a high-quality color image, a combination of a black ink that thickens or aggregates due to the action of salt and a color ink containing the salt is used in combination with a high image density and no color bleeding. A technical means for obtaining a quality color image is also disclosed (see, for example, Patent Document 1). That is, a good image can be obtained by printing two liquids of the first liquid containing salt and the ink composition.

Furthermore, various proposals using two liquids have been made (see, for example, Patent Documents 2 and 3). Furthermore, a recording material comprising a self-dispersing pigment having an excellent discharge performance when used in dispersion stability and ink jet recording, an ink composition containing an anionic polymer, and a reaction liquid has been proposed (for example, Patent Documents). 4).
JP-A-6-106735 JP-A-9-207424 JP 2000-37942 A JP-A-11-349873

  The inventors of the present invention performed recording on plain paper using a self-dispersing pigment as described in JP-A No. 11-349873 and an ink containing an anionic polymer and a reaction liquid, and as a result, high quality was recorded. It has been recognized that this is an effective means for realizing simple image formation.

  However, when a long-term durability test was conducted using the above-mentioned ink in which at least the area around the ejection opening on the ejection opening forming surface of the print head was formed as a water-repellent area, an ink pool occurred in the area around the ejection opening. It came to recognize the problem that the ink flight direction was shifted.

  Accordingly, one of the objects of the present invention is to provide an ink composition and an ink set that can provide high image density and good print quality on various recording media and are excellent in scratch resistance and line marker resistance. It is to provide.

  Another object of the present invention is to provide a high image density and good print quality on various recording media, and is excellent in scratch resistance and line marker resistance. An object of the present invention is to provide an ink composition having excellent inkjet discharge characteristics in a head in which at least the area around the discharge port is formed as a water-repellent area.

  According to an embodiment of the present invention, there is provided an ink composition used together with a reaction liquid that agglomerates the ink composition, the ink composition comprising a self-dispersing pigment having an anionic group chemically bonded to the surface, an acrylic composition The acrylic polymer has an acid value of 250 or less, and the acrylic polymer is made from a hydrophilic monomer and at least one or more hydrophobic monomers represented by the formulas (1) and (2) When the weight% of the monomers of the formula (1) and formula (2) charged when polymerizing the acrylic polymer is X1 and X2, the condition of the formula (A) is satisfied. Features.

(Wherein R ₁ represents H or a methyl group, R ₂ represents a phenyl group or a naphthyl group, R ₃ represents a linear, branched or alicyclic alkyl group / alkenyl group of C = 1 to 20, benzyl Group or polydialkylsiloxane group)
According to this embodiment, it is possible to provide high image density and good print quality on various recording media, and at the same time, excellent scratch resistance and line marker resistance, and at least the discharge port forming surface of the print head. It is possible to provide an ink composition having excellent inkjet discharge characteristics in a head in which the area around the outlet is formed as a water-repellent area.

  Even if the water-repellent treatment is performed on the area around the discharge port, the occurrence of “printing” in the long-term durability test greatly depends on the ink type. In particular, inks containing polymer components are sensitive. In addition, the occurrence of “printing” is naturally affected by the polymer alone, but at the same time it is affected by the physical properties of the self-dispersing pigment. This is not to say that self-dispersing pigments alone cause “printing”, but to emphasize that it is a complex factor. As a result of intensive studies by the present inventors, it has been found that the occurrence of “slip printing” in the water-repellent head can be effectively prevented according to the above embodiment.

  By using the ink composition and ink set of the present invention, it is possible to provide high image density and good print quality on various recording media, and to realize excellent scratch resistance and line marker resistance. It becomes possible.

  In addition, it is possible to provide an ink composition having excellent inkjet discharge characteristics in a head in which at least a region around the discharge port on the discharge port forming surface of the print head is formed as a water-repellent region.

  Next, the present invention will be described in detail with preferred embodiments.

(Ink composition)
(Self-dispersing pigment)
The self-dispersing pigment that can be used in the present invention is a self-dispersing pigment in which at least one anionic group is directly or directly bonded to the surface of the pigment through another atomic group.

Specific examples of the anionic group are as follows. _{-COO (M2), - SO 2} (M2) 2, -PO 3 H (M2), - PO 3 (M2) 2 (M2 represents a hydrogen atom, an alkali metal, ammonium or organic ammonium). These anionic groups may be directly bonded to the pigment surface, or may be bonded via an alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted phenyl group, or a substituted or unsubstituted naphthyl group. . Particularly preferred in this embodiment in particular -COO (M2) or -SO ₃ (M2) and for the pigment was allowed charged bind to anionic surface of the pigment excellent in dispersibility in the ink in the anionic group It can be used for. By the way, among those expressed as “M2” in the hydrophilic group, specific examples of the alkali metal include Li, Na, K, Rb and Cs, and specific examples of the organic ammonium include, for example, methylammonium, dimethyl Examples include ammonium, trimethylammonium, ethylammonium, diethylammonium, triethylammonium, methanolammonium, dimethanolammonium, and trimethanolammonium.

  In addition to the above-mentioned anionic groups, even if a hydroxyl group or a ketone group is present as an intentional or incidental product by a production method, it can be used without any problem as long as it satisfies the requirements indicated in the claims.

  Examples of a method for producing an anionically charged self-dispersing pigment include a method of oxidizing a pigment with sodium hypochlorite (Japanese Patent Laid-Open No. 8-3498), and a method of acidifying carbon by ozone treatment in water. (Japanese Patent Laid-Open No. 10-212426), a method in which wet treatment with an oxidizing agent is performed after ozone treatment, and the surface of the pigment is modified (Japanese Patent Laid-Open No. 11-148027). And a method of introducing a functional functional group into carbon (Japanese Patent Publication No. 10-510862). In the present invention, the above manufacturing method and other methods can be suitably used as long as they satisfy the requirements indicated in the claims.

  By the way, in the present embodiment, two or more of the above-described self-dispersing pigments may be used as an ink color material appropriately selected. The addition amount of the self-dispersing pigment in the ink is preferably in the range of 1 to 10% by weight with respect to the total weight of the ink. By setting this range, the self-dispersing pigment can maintain a sufficiently dispersed state in the ink. Furthermore, for the purpose of adjusting the color tone of the ink, a dye may be added as a coloring material in addition to the self-dispersing pigment.

(Pigment)
Examples of the pigment used include carbon black and organic pigments.

(Carbon black)
Examples of the carbon black include carbon black pigments such as furnace black, lamp black, acetylene black, and channel black. For example, Raven 7000, Ray Van 5750, Ray Van 5250, Ray Van 5000, Ray Van 3500, Ray Van 2000, and Ray Van 1500. , Ray Van 1250, Ray Van 1200, Ray Van 1190 ULTRA-II, Ray Van 1170, Ray Van 1255 (above Colombia), Black Pearls L, Legal 400R, Regal 330R, Legal 660R, Mogul L, Monak (Monarch) 700, Monak 800, Monak 880, Monak 900, Monak 1000, Mon Nak 1100, Monak 1300, Monak 1400, Vulcan XC-72R (made by Cabot), 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 ( (Degussa) 25, no. 33, no. 40, no. 47, no. 52, no. 900, no. 2300, MCF-88, MA600, MA7, MA8, MA100 (manufactured by Mitsubishi Chemical Co., Ltd.) and the like can be used, but are not limited thereto, and conventionally known carbon black can be used. . Further, magnetic fine particles such as magnetite and ferrite, titanium black and the like may be used as the black pigment.

(Organic pigment)
Specific examples of organic pigments include 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, indane Derivatives from vat dyes such as Throne and 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 Isoindolinone pigments such as yellow and isoindolinone orange, imidazoles such as benzimidazolone yellow, benzimidazolone orange and benzimidazolone red Pigments, pyranthrone pigments such as pyranthrone red, pyranthrone orange, thioindigo pigments, condensed azo pigments, thioindigo pigments, flavanthrone yellow, acylamide yellow, quinophthalone yellow, nickel azo yellow, copper azomethine yellow, peri Other pigments such as non-orange, anthrone orange, dianthraquinonyl red, dioxazine violet can be exemplified.

  Moreover, the following can be illustrated when an organic pigment is shown by a color index (CI) number. Of course, conventionally known organic pigments can be used in addition to the following.

C. I. Pigment Yellow: 12, 13, 14, 17, 20, 24, 74, 83, 86, 93, 109, 110, 117, 120, 125, 128, 137, 138, 147, 148, 151, 153, 154, 166 168 etc. C.I. I. Pigment Orange: 16, 36, 43, 51, 55, 59, 61 etc. 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, etc. C.I. I. Pigment Violet: 19, 23, 29, 30, 37, 40, 50, etc. C.I. I. Pigment Blue: 15, 15: 3, 15: 1, 15: 4, 15: 6, 22, 60, 64, etc. C.I. I. Pigment Green: 7, 36 etc. C.I. I. Pigment Brown: 23, 25, 26, etc. (About acrylic polymer)
The acrylic polymer that can be used in the present invention must satisfy the following conditions.

  The acid value of the acrylic polymer is 250 or less.

  The acrylic polymer is polymerized using a hydrophilic monomer and at least one hydrophobic monomer represented by the formulas (1) and (2) as raw materials, and charged when the acrylic polymer is polymerized (1) When the weight% of the monomer of the formula (2) is X1 and X2, the condition of the formula (A) is satisfied.

(Wherein R ₁ represents H or a methyl group, R ₂ represents a phenyl group or a naphthyl group, R ₃ represents a linear, branched or alicyclic alkyl group / alkenyl group of C = 1 to 20, benzyl Group or polydialkylsiloxane group derivative)
Examples of the method for polymerizing an acrylic polymer include, but are not limited to, solution polymerization / suspension polymerization / emulsion polymerization using a radical initiator, living anion polymerization, and living radical polymerization. The polymerization form may be random graft block.

  If the acid value exceeds 250, the dispersion stability of the self-dispersing pigment used together may be impaired. This phenomenon is particularly noticeable when a self-dispersing pigment having an anionic functional group density of 0.1 to 0.6 mmol / g is used. Further, if the value of the formula (A) exceeds 35, even if a head in which at least the area around the discharge port on the discharge port forming surface of the print head is formed as a water-repellent region is used, May occur.

  The amount of acrylic polymer added to the ink is preferably such that the ratio of the self-dispersing pigment (self-dispersing pigment: acrylic polymer) in the ink composition is in the range of 10: 1 to 1: 1. When the content of the acrylic polymer is below this range, the effect of scratch resistance does not appear, and when it exceeds, it is necessary to increase the amount of polyvalent metal added in the reaction solution, such as storage stability. May cause adverse effects on reliability.

(Aqueous medium)
The aqueous medium in which the color material as described above is dispersed is not particularly limited. In addition, when the ink is attached to a recording medium by an ink jet method (for example, bubble jet (registered trademark) method), the ink has a desired viscosity and surface tension so as to have excellent ink jet discharge characteristics as described above. It is preferable to prepare so that it has.

  Examples of the aqueous medium used in the ink composition according to 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 effect of preventing the reaction solution from drying 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 Alkylene glycols containing carbon atoms; 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 monomethyl (or ethyl) ether, etc. Lower alkyl ethers of polyhydric alcohols; polyhydric alcohols such as trimethylolpropane and trimethylolethane; 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. It is desirable to use deionized water as the water.

  The content of the water-soluble organic solvent contained in the ink composition 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 composition. Further, the content of water contained in the ink composition is preferably in the range of 50 to 95% by mass with respect to the total mass of the reaction solution. In addition to the above components, a moisturizing agent may be added as necessary, and a surfactant, an antifoaming agent, an antiseptic, an antifungal agent, etc. may be added to obtain an ink having a desired physical property value. It doesn't matter.

(Reaction solution)
The reaction liquid used in the present invention is a component capable of destroying and aggregating on the recording medium the dispersion stability of the coloring material dispersed or dissolved in the aqueous medium by the action of ionic groups in the aqueous medium. It preferably contains a metal salt and an aqueous medium. In the present invention, a resin may be added to the reaction solution in consideration of the scratch resistance of the printed matter.

  Examples of a method for attaching the reaction liquid to the recording medium include an image forming area to which ink adheres and an ink jet method capable of selectively and uniformly attaching only to the vicinity of the image forming area. With respect to a reaction solution that is not suitable for inkjet, the entire surface of a recording medium may be applied by roller coating or the like.

(About metal salts)
The metal salt that can be used in the reaction solution is composed of monovalent metal ions, divalent or higher polyvalent metal ions, and anions that bind to these polyvalent metal ions, and is soluble in water. is there. Specific examples of the polyvalent metal ions include, for example, divalent metal ions such as Ca ²⁺ , Cu ²⁺ , Ni ²⁺ , Mg ²⁺ , Zn ²⁺ , and Ba ²⁺ , Al ³⁺ , Fe ³⁺ , Cr ³⁺ , and Y ^A trivalent metal ion such as ³⁺ may be mentioned, but is not limited thereto. In addition, the content of the salt in the reaction solution is preferably 0.01 to 20% by mass in consideration of the effect of the present invention. Further, the reaction solution does not necessarily have to show no absorption in the visible range. Even if absorption is shown in the visible range, absorption in the visible range may be used as long as it does not substantially affect the image.

(resin)
The resin to be added is preferably a nonionic water-soluble polymer that basically does not participate in the reaction, although it depends on the ionicity of the ink and the reaction liquid. Examples include, but are not limited to, water-soluble celluloses such as polyacrylamide, polyvinylpyrrolidone, carboxymethylcellulose, hydroxymethylcellulose, hydroxypropylcellulose, and the like, polyvinylmethyl ether, polyvinyl acetal, polyvinyl alcohol, and the like. As long as each basic performance of the reaction solution can be maintained, a resin obtained by adding an anion unit or a cation unit to these nonionic polymers may be used. Further, the above-mentioned resin is satisfactory as long as it is water-soluble, but it may be a dispersion such as latex or emulsion.

(Aqueous medium)
Examples of the aqueous medium used in the reaction liquid according to 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 effect of preventing the reaction solution from drying 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 Alkylene glycols containing carbon atoms; 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 monomethyl (or ethyl) ether, etc. Lower alkyl ethers of polyhydric alcohols; polyhydric alcohols such as trimethylolpropane and trimethylolethane; 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. It is desirable to use deionized water as the water.

  Although content of the water-soluble organic solvent contained in the reaction liquid concerning this invention is not specifically limited, Preferably the range of 3-50 mass% is suitable with respect to the reaction liquid total mass. The content of water contained in the reaction solution is preferably in the range of 50 to 95% by mass with respect to the total mass of the reaction solution. In addition to the above components, surfactants, antifoaming agents, antiseptics, antifungal agents, and the like can be added to obtain a reaction solution having desired physical properties as required.

(Ink set)
The color tone of the ink that constitutes the ink set in combination with the reaction liquid is not particularly limited. For example, the ink may have at least one color tone selected from yellow, magenta, cyan, red, green, blue, and black. Specifically, it can be used by appropriately selecting from the above-described color materials so as to obtain ink having a desired color tone.

  Further, the ink to be combined with the reaction liquid is not limited to one type, and it is more preferable to combine two or more inks having different color tones to make an ink set suitable for forming a multicolor image. In this case, at least one of the two or more inks may react with the reaction liquid.

  As long as the color material is dispersed in the aqueous medium by the action of ionic groups, the other ink may be an ink containing a dye as a color material. The ink may be dispersed by the action of ionic groups. According to such an ink set, it is possible to suppress bleeding when ink of different color tones is applied adjacently on a recording medium, which is a problem when a multicolor image is formed by an ink jet apparatus.

  More specifically, bleeding that is a problem in an inkjet multicolor image is at least one selected from black ink and other color inks (for example, yellow ink, magenta ink, cyan ink, red ink, green ink, and blue ink). In particular, in the present invention, black ink is used as an ink in which a color material is dispersed in an aqueous medium by the action of an ionic group so as to interact with the reaction liquid. Are preferably combined. Other color inks may be inks in which a dye is dissolved in an aqueous medium, or of course, inks in which a color material is dispersed in an aqueous medium by the action of ionic groups, as in black inks.

(Recording method)
The reaction liquid is combined with an ink in which a coloring material is dispersed in an aqueous medium by the action of an ionic group, and (i) a step of applying the ink to a recording medium; and (ii) the reaction liquid is recorded on the recording medium. By adopting a recording method having a step of applying to at least a region of the medium to which the ink is applied, the ambiguity of the contour is improved without extremely increasing the reactivity between the reaction liquid and the ink composition, and It is possible to provide an ink set, an ink jet recording method, and a recorded matter thereof that can form an excellent high-quality image without causing color bleeding.

When an ink set of the ink and the reaction liquid is used in an inkjet or the like,
a: When printing ink after printing the reaction liquid,
b: When printing the reaction liquid after printing the ink,
c: When printing the reaction liquid after printing the ink and further printing the ink,
d: Various recording methods are conceivable, for example, when ink is printed after the reaction liquid is printed, and further the reaction liquid is printed.

  The recording method using ink and reaction liquid may be selected as appropriate. However, in view of the object of the present invention, the above (a) or (d) including at least a step of recording the reaction liquid on the recording medium prior to the ink is preferable.

  According to the investigations by the inventors so far, the following is considered. In the recording method (a or (d)), first, the reaction liquid 91 is applied to the recording medium 25 (see FIG. 1A), and then the ink 92 is applied to the portion to which the reaction liquid is applied ( 1 (b)) Therefore, the coloring material in the ink reacts with the reaction liquid present on the surface of the recording medium immediately after being applied to the recording medium 25, so that more coloring material in the ink is recorded on the recording medium. As a result, it is considered that an excellent high-quality image can be formed without improving the ambiguity of the contour portion and causing color bleeding.

  Also, an ink set that can be suitably used for forming a color image by combining a plurality of ink sets of the reaction liquid and the ink composition, or combining an ink set of the reaction liquid and the ink composition with another ink composition. Can be provided. When such an ink set is used, for example, when the black ink and the color image portion are recorded adjacent to the black ink, the occurrence of bleeding can be suppressed extremely effectively. .

  Further, regarding the method of applying the reaction liquid, an ink jet method may be used in the same manner as the ink. Of course, any conventionally known method such as bar coating, roller coating, spray coating or the like does not depart from the technical idea of the present invention.

(Ink characteristics; ink jet ejection characteristics, permeability to recording media)
The ink set according to the present invention can be suitably used as an ink set for inkjet recording. As the ink jet recording method, there are a recording method in which mechanical energy is applied to ink to eject droplets, and a recording method in which thermal energy is applied to ink and ink droplets are ejected by foaming of the ink. The reaction liquid and ink of the present invention are particularly suitable.

  By the way, when the reaction liquid and ink according to the present invention are used for ink-jet recording, it is preferable that the reaction liquid and ink have a characteristic of being ejectable from an ink-jet head. From the viewpoint of dischargeability from an inkjet head, the liquid has, for example, a viscosity of 1 to 15 cps, a surface tension of 25 mN / m (dyne / cm) or more, particularly a viscosity of 1 to 5 cps, and a surface tension. Is preferably 25 to 50 mN / m (dyne / cm). Further, the reaction liquid needs to be reacted with only a specific ink composition on the paper surface. For this reason, the surface tension of the reaction liquid is within the range in which the reaction liquid can be ejected from the ink jet head so that the reaction liquid does not bleed into a place different from the recording portion of the specific ink composition. It is preferable to enlarge it.

(Inkjet recording method)
Next, an ink jet recording method in which each reaction liquid and ink of the present invention can be suitably used will be described. 2 is a cross-sectional view of the head 13 along the ink flow path, and FIG. 3 is a cross-sectional view taken along the line AB of FIG. The head 13 is obtained by bonding a heating element substrate 15 to 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, 17-2 formed of aluminum, gold, aluminum-copper alloy, etc., HfB2, TaN, TaAl, etc. From a heating resistor layer 18 formed from a high melting point material, a livestock heat layer 19 formed from thermal silicon oxide, aluminum oxide, or the like, and a substrate 20 formed from a material with good heat dissipation such as silicon, aluminum, aluminum nitride, or the like. It is made up.

  When a pulsed electric signal is applied to the electrodes 17-1 and 17-2 of the head, the region indicated by n of the heating element substrate 15 rapidly generates heat, and bubbles are generated in the ink in contact with the surface. Then, the meniscus 23 protrudes by the generated pressure, ink is ejected through the nozzle 14 of the head, becomes an ink droplet 24 from the ejection orifice 22, and flies toward the recording medium 25.

  FIG. 4 shows an external view of a multi-head in which a large number of heads shown in FIG. 2 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.

(Inkjet recording device)
FIG. 5 shows an example of an ink jet recording apparatus incorporating this head. In FIG. 5, 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 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 a discharge recovery unit 64, and the blade 61 and the ink absorber 63 remove moisture, dust, and the like from the discharge port surface. In addition, each ink of the recording head, and further, the ink located at the outlet of the reaction liquid are sucked by a pump (not shown) through the cap, and the original ink of the recording head or the ink and the reaction liquid It constitutes a recovery unit that restores the original discharge performance.

  Reference numeral 65 denotes a recording head which has discharge energy generating means and performs recording by discharging ink onto a recording medium facing the discharge port surface where the discharge port is arranged. Reference numeral 66 denotes a movement of the recording head 65 by mounting the recording head 65. It is a carriage for performing. 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 section for inserting a recording medium, and 52 is a paper feed roller driven by a motor (not shown).

  With these configurations, the recording medium is fed to a position facing the discharge port surface of the recording head 65, 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. 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.

(ink cartridge)
FIG. 6 is a view showing an example of a member 45 for supplying ink or a reaction liquid to the recording head, for example, an ink supplied via a tube or a cartridge 45 containing the reaction liquid. Here, reference numeral 40 denotes a storage portion, for example, a bag, which stores ink for supply or reaction liquid, and a rubber stopper 42 is provided at the tip thereof. By inserting a needle (not shown) into the stopper 42, the ink or reaction liquid in the bag 40 can be supplied to the head.

  Reference numeral 44 denotes an absorber that receives waste ink or waste reaction liquid. The container 40 preferably has a liquid contact surface with an ink or a reaction liquid formed of polyolefin, particularly polyethylene. Such a cartridge is configured to be detachable from, for example, a recording head 901 that discharges ink or reaction liquid as shown in FIG. 7, and the ink or reaction liquid is mounted in a state where the cartridge 45 is mounted on the recording head. Is supplied to the recording head 901.

  Further, as another aspect of the cartridge according to the present invention, the cartridge includes two storage portions that individually store the reaction liquid and the ink, and is configured to be detachable from the head for discharging the ink and the reaction liquid. And a cartridge configured to be able to supply ink and a reaction liquid to the recording head.

  FIG. 8 shows an example of such a cartridge 1001, where 1003 is a reaction liquid container, 1005 is an ink container, and the cartridge discharges each of ink and reaction liquid as shown in FIG. The recording head 1101 is configured to be detachable, and the reaction liquid and the ink are supplied to the recording head 1101 when the cartridge 1001 is mounted on the recording head 1101.

  Further, the ink set of the present invention is not limited to the one in which the reaction liquid and the ink are physically integrated as shown in FIG. 8, but, for example, as shown in FIG. 10, a cartridge containing the reaction liquid. 1201 and a cartridge 1203 containing ink are mounted on a common recording head 1205 for ejecting each of the reaction liquid and ink, and an inkjet image can be recorded using the reaction liquid and ink. Are also within the scope of the present invention.

(Recording unit)
The ink jet apparatus used in the present invention is not limited to the one in which the head and the cartridge are separated as described above, but is preferably used in an apparatus in which they are integrated as shown in FIG. In FIG. 11, reference numeral 70 denotes a recording unit, which is a storage unit that stores ink or a reaction liquid. For example, when ink is stored, the ink absorber is stored, and the ink in the ink absorber is ejected as ink droplets from the head portion 71 having a plurality of orifices. As the material of the ink absorber, it is preferable for the present invention to use polyurethane or polypropylene.

  Further, the structure may be such that the absorbent body is not used, and the housing portion is a bag in which a spring or the like is charged. 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. 5 and is detachable from the carriage 66.

  Furthermore, as another embodiment of the recording unit according to the present invention, one reaction liquid and at least one ink selected from color inks having black, yellow, magenta, cyan, red, green, blue and black hues are provided. A recording unit that is integrally provided with a recording head that is stored in each ink storage portion of the ink tank and discharges each ink, specifically, for example, as shown in FIG. In the storage unit 1301L, black ink dispersed in an aqueous medium by an ionic group is stored in the storage unit 1301Bk, and yellow, cyan, and magenta color inks are stored in the color ink storage units 1301Y, 1301C, and 1301M, respectively. In addition, the ink flow so that the reaction liquid and the other four different ink colors can be ejected individually. Recording unit 1301 and the like, such as those provided with a recording head 1303 configured separately.

  Next, as a form of the ink jet recording apparatus using the second mechanical energy, a nozzle forming substrate having a plurality of nozzles, a pressure generating element made of a piezoelectric material and a conductive material disposed facing the nozzles, and this An on-demand ink jet recording head that includes ink that fills 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 can be exemplified. FIG. 13 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 of a desired volume, a vibration plate 82 that directly applies pressure to ink, and the vibration plate 82. And a substrate 84 for indicating and fixing the orifice plate 81, the vibration plate, and the like.

  In FIG. 13, an ink flow path 80 is formed of photosensitive resin or the like, an orifice plate 81 is formed with a discharge port 85 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 strain 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. The ink is vertically pressed and ink droplets (not shown) are discharged from the discharge port 85 of the orifice plate 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.

(Recording apparatus and recording method using ink set)
Next, when recording a color image using an ink set, for example, a recording apparatus in which five recording heads shown in FIG. 4 are arranged on a carriage 1401 can be used. FIG. 14 shows an example, and 1401L, 1401Bk, 1401Y, 1401M, and 1401C are the reaction solution, black ink containing carbon black dispersed in an aqueous medium by the action of ionic groups, and cyan. This is a recording unit for ejecting magenta and yellow inks. The recording unit is disposed on the carriage of the above-described recording apparatus and ejects ink of each color according to a recording signal. In addition, the reaction liquid is attached to a portion where the recording ink of each color or at least one of the colors adheres to the recording medium in advance or after the ink is attached.

  FIG. 14 shows an example in which five recording units are used. However, the present invention is not limited to this. For example, as shown in FIG. Each color ink supplied from ink cartridges 1501L, 1501Bk, 1501Y, 1501M and 1501C each containing black ink containing carbon black and YMC three colors ink dispersed in a medium can be individually ejected. For example, an aspect in which recording is performed by attaching to a recording head 1501 configured by dividing ink flow paths is also possible.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. However, the present invention is not limited to the following Examples unless it exceeds the gist. In the following description, “parts” or “%” are based on mass unless otherwise specified.

(Pigment dispersion Bk1)
To a solution of 5 g of concentrated hydrochloric acid dissolved in 5.3 g of distilled water, 1.58 g of anthranilic acid was added at 5 ° C. By stirring using an ice bath, a solution in which 1.78 g of sodium nitrite is dissolved in 8.7 g of distilled water at 5 ° C. is added to the above solution so that the temperature is always kept at 10 ° C. or lower. It was. After stirring for 15 minutes, 7 g of carbon black having a specific surface area of 220 m ² / g and a DBP oil absorption of 105 mL / 100 g was added to the solution while stirring the solution. Thereafter, the mixture was further stirred for 15 minutes. The obtained slurry was Toyo Filter Paper No. 2 (manufactured by Advantech), the pigment particles were sufficiently washed with water, dried in an oven at 110 ° C., and distilled water was added to the pigment to prepare a pigment dispersion having a pigment concentration of 10% by mass.

The hydrophilic group density of the self-dispersing carbon black produced above was measured as follows and found to be 2.6 μmol / m ² . As a measuring method, an ion meter (manufactured by DKK) was used to measure the sodium ion concentration, and the hydrophilic group density was converted from the value. Then, by substituting sodium ions with ammonium ions using an ion exchange method, the self-dispersing carbon black in which a hydrophilic group -Ph-COONH ₄ group is introduced is dispersed on the surface of the carbon black. A pigment dispersion Bk1 was obtained. The solid content of the obtained pigment dispersion Bk1 was 10%.

(Pigment dispersion C1, pigment dispersion M1, pigment dispersion Y1)
In the same procedure as for the pigment dispersion Bk3, a pigment dispersion in which self-dispersed pigments were dispersed was also obtained for cyan, magenta, and yellow. Examples of cyan pigments include C.I. I. Pigment Blue 15: 3 (product name: Fastgen Blue FGF, manufactured by Dainippon Ink & Chemicals)), and magenta pigments include C.I. I. Pigment Red 122 (product name: TONER MAGENTA E02 (manufactured by Clariant)), and yellow pigments include C.I. I. Pigment Yellow 74 (product name: HANSA BRILLIANT YELLOW 5GX 03 (manufactured by Clariant)) was used. The obtained pigment dispersions are designated as pigment dispersion C1, pigment dispersion M1, and pigment dispersion Y1, respectively. The solid content was 10% each.

(Water-soluble polymer aqueous solution 1)
Benzyl methacrylate / methoxypolyethylene glycol monomethacrylate (trade name: M-230G (manufactured by Nakamura Chemical)) / methacrylic acid copolymer (copolymerization ratio: 41/30/29 (weight ratio)), acid value: 121, molecular weight: 5000 ) Was neutralized with an aqueous potassium hydroxide solution to obtain a water-soluble polymer aqueous solution 1 having a solid content of 10%.

(Water-soluble polymer aqueous solution 2)
A butyl acrylate / methacrylic acid copolymer (acid value: 230, molecular weight: 8000) was neutralized with a potassium hydroxide aqueous solution to obtain a water-soluble polymer aqueous solution 2 having a solid content of 10%.

(Water-soluble polymer aqueous solution 3)
A benzyl methacrylate / methacrylic acid copolymer (acid value: 220, molecular weight: 10,000) was neutralized with an aqueous potassium hydroxide solution to obtain a water-soluble polymer aqueous solution 3 having a solid content of 10%.

(Water-soluble polymer aqueous solution 4)
A styrene / acrylic acid copolymer (acid value: 290, molecular weight: 5000) was neutralized with an aqueous potassium hydroxide solution to obtain an aqueous water-soluble polymer solution 4 having a solid content of 10%.

  Using the pigment dispersion prepared in the above procedure, Bk, C, M, and Y inks were prepared with the compositions shown in Table 1, respectively.

  Each ink was sufficiently stirred and dissolved or dispersed, followed by pressure filtration with a micro filter (manufactured by Fuji Film) having a pore size of 3.0 μm.

  Ink sets 1 and 2 were prepared by combining the prepared inks and the reaction liquid prepared with the composition shown below as shown in Table 1. These are referred to as Example 1 and Comparative Example 1, respectively.

(Reaction solution)
The following components were mixed to prepare a reaction solution.
・ Calcium nitrate (tetrahydrate) 10 parts ・ Trimethylolpropane 10 parts ・ Glycerin 5 parts ・ Acetylene glycol ethylene oxide adduct 1 part (trade name: acetylenol EH)
74 parts of water Inkjet recording apparatus having an on-demand type multi-recording head that discharges ink by applying thermal energy according to a recording signal to the ink using the ink sets 1 and 2 and the reaction liquid shown above Recording was performed with a modified machine of BJ F900 (manufactured by Canon).

  The evaluation items are shown below. Copy paper (PB paper) was used as the printing material.

  The recording was performed on the entire surface of the copy paper with the reaction solution applied at 600 dpi so that the applied amount was 10 ng.

Image quality of plain paper A pattern in which black and cyan, magenta, and yellow solid colors are adjacent to each other and characters with 12 points of fonts were printed, and the blur of the character quality and solid color solid portions was evaluated.

(Evaluation results)
Each ink of the ink set of Example 1 had no blurring of characters and the blurring of the solid boundary portion was not noticeable. However, in the ink of the ink set of Comparative Example 1, some blurring was noticeable in cyan and magenta characters.

Face surface test Using the black ink of Example 1 and Comparative Example 1, the face test in BJS700 was performed according to the following criteria. In BJ S700, the discharge port forming surface (face surface) is subjected to water repellent treatment.

  At 1000 shots for each nozzle, the entire discharge is performed, and then the wiper attached to the main body is executed. After this operation was repeated 1000 times, the ink adhesion and printing deviation were evaluated.

(Evaluation results)
The black ink of Example 1 was not printed and the ink adhesion to the face surface was not noticeable. On the other hand, in the black ink of Comparative Example 1, printing deviation occurred, and ink adhesion to the face surface was conspicuous.

It is a schematic explanatory drawing of the recording method concerning one embodiment of this invention. It is a longitudinal cross-sectional view which shows an example of the head of an inkjet recording device. It is a cross-sectional view showing an example of the head of the ink jet recording apparatus. FIG. 3 is an external perspective view of a head in which the head shown in FIG. It is a schematic perspective view which shows an example of an inkjet recording device. It is a longitudinal cross-sectional view which shows an example of an ink cartridge. FIG. 3 is a schematic plan view showing a state in which the ink cartridge according to one embodiment of the present invention is mounted on a recording head. FIG. 6 is a schematic plan view showing another embodiment of the ink cartridge according to one embodiment of the present invention. FIG. 9 is a schematic plan view showing a state where the ink cartridge of FIG. 8 is mounted on a recording head. It is a schematic plan view which shows the other embodiment of the ink set concerning this invention. It is a perspective view which shows an example of a recording unit. It is a schematic perspective view which shows the other embodiment of the recording unit concerning this invention. It is a schematic sectional drawing which shows another structural example of an inkjet recording head. Each of the recording unit containing the liquid composition, the recording unit containing the black ink containing the color material dispersed in the aqueous medium by the action of the ionic group, and the CMY according to one embodiment of the ink set of the present invention 4 is a schematic diagram showing a state in which recording units containing color inks are mounted on the same carriage. FIG. 6 is an enlarged view of an orifice portion of one aspect of the recording head portion of the ink jet apparatus of FIG. 5.

Explanation of symbols

13 Head 14 Ink Groove 15 Heating Head 16 Protective Film 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 Medium 26 Multi-Groove 27 Glass Plate 28 Heating Head 40 Ink Bag 42 Plug 44 Ink Absorber 45 Ink Cartridge 51 Paper Feeder 52 Paper Feed Roller 53 Paper Discharge Roller 61 Blade 62 Cap 63 Ink Absorber 64 Ejection recovery part 65 Recording head 66 Carriage 67 Guide shaft 68 Motor 69 Belt 70 Recording unit 71 Head part 72 Atmospheric communication port 80 Ink flow path 81 Orifice plate 82 Vibration plate 83 Piezoelectric element 84 Substrate 85 Ejection port 91 Liquid composition 92 Ink 600 Inkjet recording apparatus 601 Inkjet head cartridge 602 Drive motor 603, 604 Drive force transmission gear 605 Lead screw 606 Spiral groove 607 Carriage 607a Lever 6 08 Guide 609 Platen roller 610 Paper pressing plate 611, 612 Photocoupler 613 Support member 614 Cap member 615 Ink suction means 616 Cap opening 617 Cleaning blade 618 Moving member 619 Main body support 620 (Suction start) lever 621 Cam 832 Discharge port 832a Protruding part 832b Protruding part 901 Recording head 1001 Cartridge 1003 Liquid composition container 1005 Ink container part 1101 Recording head 1201, 1203 Cartridge 1205 Recording head 1301 Recording unit 1303 Recording head 1401 Carriage 1501 Recording head

Claims (5)

An ink composition used together with a reaction liquid for aggregating the ink composition, the ink composition comprising a self-dispersing pigment having an anionic group chemically bonded to the surface, an acrylic polymer, and the acrylic composition The acid value of the polymer is 250 or less, and the acrylic polymer is polymerized using a hydrophilic monomer and at least one or more hydrophobic monomers represented by the formulas (1) and (2) as raw materials, An ink composition characterized by satisfying the condition of the formula (A) when the weight percent of the monomers of the formulas (1) and (2) charged when the acrylic polymer is polymerized is X1 and X2.

(Wherein R ₁ represents H or a methyl group, R ₂ represents a phenyl group or a naphthyl group, R ₃ represents a linear, branched or alicyclic alkyl group having 1 to 20 carbon atoms, an alkenyl group, benzyl Group or polydialkylsiloxane group)   The hydrophilic monomer is selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, itaconic acid, C = 1-4 alkoxy polyethylene glycol (meth) acrylate (PEG chain length 1-50), and polyethylene glycol (meth) acrylate. The ink composition according to claim 1, which is selected.   An ink set comprising a reaction liquid for aggregating the ink composition and at least one ink composition according to claim 1.   4. The ink according to claim 1, wherein at least a region around the ejection port on the ejection port forming surface is formed as a water-repellent region. 5. An image recording apparatus using the composition and the ink set.   The reaction according to any one of claims 1 to 3, wherein the reaction liquid is applied on a recording material, and the ink recording method is applied on the recording material by an ink jet recording method. An image recording method using a liquid and an ink composition.

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