JP2006160814A - Ink composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink composition which can give a high image density and good printing qualities on various recording media, and particularly is excellent in scratch resistance on recording on a glossy medium. <P>SOLUTION: The ink composition is used for a recording device which records by an image-recording method comprising a step for applying at least one ink composition on a recording medium and a step for applying a reaction liquid reactive with at least one of the ink compositions where whether the step for applying the reaction liquid is necessary or not is decided according to the kinds of the recording medium, and the ink composition contains a second pigment dispersed in the ink by an action of a self-dispersible pigment, having its surface modified with a water-soluble resin A, with a water-soluble resin B. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ink composition that can provide high image density and good print quality on various recording media, and is particularly excellent in scratch resistance when recorded on a glossy medium.

  Conventionally, as ink for writing instruments (fountain pens, sign pens, water-based ballpoint pens, etc.) and ink for inkjet, inks using pigments with high printed matter density and excellent fastness have been proposed. In particular, in recent years, color materials have been developed so that excellent quality and robustness can be recorded on plain paper such as copy paper, report paper, and bond paper used in offices, glossy paper, and glossy media. Detailed research and development has been conducted from various aspects such as ink composition and physical properties. For example, an ink containing a pigment of a type in which a resin is bonded to the pigment surface and a method for producing a pigment dispersion are disclosed (for example, see Patent Documents 1 to 3). The ink containing the pigment is disclosed as having excellent reliability with respect to the recording head without any adverse effects such as ejection bending, wetting and non-discharge, as with a so-called self-dispersing pigment in which a water-soluble group is introduced on the pigment surface (for example, Patent Documents 4 and 5). However, the amount of binding resin is not uniform and cannot be controlled depending on the pigment and resin used, and at the same time, there is a problem that the choice of the pigment type and resin type to be used is narrow, and there is still room for improvement. .

  On the other hand, in the ink jet recording method, since the ink composition is a liquid, the ink droplet permeates into the recording medium when landing on the recording medium, so that the outline becomes unclear, or the adjacent ink is different. There was a phenomenon in which blurring between colors (so-called color bleeding) occurred. In order to solve this problem, a high-quality image with high image density and no color bleed is obtained by using a combination of black ink that thickens or aggregates due to the action of salt and color ink containing the salt. Technical means that a color image of the above can be obtained is disclosed (for example, see Patent Document 6). That is, a good image can be obtained by printing two liquids of the first liquid containing salt and the ink composition.

Further, a technical means is disclosed in which a good image can be obtained by applying an ink composition and a reaction liquid containing a component that insolubilizes the colorant in the ink composition to the paper surface. (For example, refer to Patent Document 7). Further, in the ink jet recording method for printing two liquids, the reaction liquid is attached to a recording medium, and then the recording medium is pressurized and heated by a plurality of rolls. Then, a technical means is disclosed in which a better image can be obtained by applying and printing an ink composition on a recording medium to which the reaction liquid is attached (see Patent Document 8).
JP-A-9-272831 JP 2000-53902 A JP 2000-95987 A JP-A-8-3498 Japanese Patent Laid-Open No. 10-195360 JP-A-6-106735 JP-A-9-207424 JP 2000-37942 A

  The inventors of the present invention performed recording on plain paper using an ink containing a pigment that binds a resin to the surface and a reaction liquid. As described above, in order to realize high-quality image formation, two liquids are used. Recognized that the recording means using is very good.

  On the other hand, when recording on glossy paper, glossy media, etc., if the reaction solution is used, depending on the paper type, the paper surface may be modified and image performance may deteriorate. Therefore, when recording on glossy paper, glossy media, etc., the above reaction solution is not necessarily essential, avoid meaningless use of the reaction solution on glossy paper, glossy media, etc. We have also recognized the need to use it. As means for appropriately using the reaction liquid according to the paper type, in addition to any conventionally known technical means such as paper type detection and paper type selection by a driver, Japanese Patent Laid-Open No. 2002-137378 discloses a transport path depending on the paper type. Means for making an appropriate selection is disclosed (Patent Document 9).

  However, in practice, the above image recording apparatus can obtain an image of high quality and fastness on plain paper, but in the recording of glossy paper, glossy media, etc., as described above, the resin that is bonded to the surface of the pigment. Since the amount of the ink varies depending on the pigment and resin used, there are new and difficult areas to achieve high-quality image formation on plain paper and glossy paper due to the appearance of inferior and inferior parts in printed matter. I found.

  That is, an object of the present invention is to provide an ink composition and an ink set that can give high image density and good print quality on various recording media, and have excellent scratch resistance when recorded on a glossy medium. There is to do. Another object of the present invention is to expand the range of options for pigments and resins by using the means of the present invention.

  The above object is achieved by the present invention described below.

  A step of applying at least one ink composition to the recording medium and a step of applying a reaction liquid that reacts with at least one of the ink compositions, and depending on the type of the recording medium, the reaction liquid A self-dispersible pigment whose surface is modified with a water-soluble resin A, and an ink composition for use in a recording apparatus for recording by an image recording method, wherein the presence or absence of the step of imparting is selected. An ink composition comprising a second pigment dispersed in an ink by the action of a water-soluble resin B is provided.

  The present invention also relates to an ink used in the recording apparatus, wherein the R / P ratio is 0.00 when the weight% of the pigment contained in the ink composition is P% and the weight% of the water-soluble resin is R%. The ink composition is characterized by being 15 or more.

  According to the present invention, it is possible to provide an ink composition that can provide high image density and good print quality on various recording media, and is excellent in scratch resistance when recorded on a glossy medium. Become.

  Next, the present invention will be described in detail with reference to the best form for carrying out the invention.

(Ink composition)
The first and second colorants used in the pigment ink of the present invention are not particularly limited, and those listed below can be used.

(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. (first colorant)
The first colorant constituting the pigment ink of the present invention is a pigment in which the surface of the pigment particles listed above is modified with the water-soluble resin A.

  The resin is obtained by bonding to a functional group chemically bonded to the pigment surface directly or through another atomic group. Here, the type of the functional group is selected in relation to the functional group carried by the resin. The reaction between the functional group and the resin is a reaction that generates a bond that does not cause hydrolysis or the like, such as an amide bond, considering that the pigment is dispersed in an aqueous medium. It is preferable. By making the functional group an amino group and having the copolymer carry a carboxyl group, the resin can be introduced to the pigment particle surface via an amide bond. Similarly, the resin can be introduced to the pigment particle surface via an amide bond by converting the functional group into a carboxyl group and loading the resin with an amino group.

  Here, the functional group chemically bonded to the pigment surface may be directly bonded to the pigment surface or may be bonded via another atomic group. However, when a resin having a relatively large molecular weight is introduced to the pigment surface, it is preferable to introduce a functional group to the pigment surface via another atomic group in order to avoid steric hindrance between the resins. Here, the other atomic groups are not particularly limited as long as they are polyvalent elements or organic groups. However, from the viewpoint of controlling the distance of the functional group from the pigment surface, for example, a divalent organic residue is preferably used. Examples of the divalent organic residue include an alkylene group and an arylene group (phenylene group).

  More specifically, for example, in the examples described later, the pigment is reacted with aminophenyl (2-sulfoethyl) sulfone to introduce an aminophenyl (2-sulfoethyl) sulfone group on the pigment surface. An amino group as a functional group is introduced by reacting an amino group of hexamine with an aminophenyl (2-sulfoethyl) sulfone group. In this case, it can be said that the amino group is chemically bonded to the pigment surface via an atomic group containing a phenyl (2-sulfoethyl) group.

  The first colorant used in the present invention is not limited to the above-mentioned pigments, and the types of pigments described in JP-A-9-272831, JP-A-2000-53902, and JP-A-2000-95987 are used. It doesn't matter.

(Second colorant)
The second colorant constituting the pigment ink of the present invention is obtained by dispersing pigment particles as listed above with a water-soluble resin B described later.

(resin)
In the present invention, the water-soluble resin A that is bonded to the pigment surface and the water-soluble resin B that contributes to the dispersion of the pigment are preferably anionic resins in consideration of the reactivity with the reaction solution. As long as it is a combination, a resin having a cationic property may be used. Of course, in this case, the water-soluble resin A and the water-soluble B need to be a combination that does not react with each other. Resin A and resin B may be the same type.

  Examples of the anionic resin include a resin composed of a hydrophobic monomer and an anionic monomer, or salts thereof. Typical hydrophobic monomers used at this time include the following monomers, but the present invention is not limited to these. For example, methacrylic acid alkyl esters such as styrene, vinyl naphthalene, methyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethoxyethyl methacrylate, methacrylonitrile, 2-trimethylsiloxyethyl methacrylate, glycidyl methacrylate, p-tolyl methacrylate, sorbyl methacrylate Alkyl acrylates such as methyl acrylate, phenyl acrylate, benzyl acrylate, acrylonitrile, 2-trimethylsiloxyethyl acrylate, glycidyl acrylate, p-tolyl acrylate and sorbyl acrylate.

  Examples of the anionic monomer used above include the following monomers, but the present invention is not limited thereto. For example, acrylic acid, methacrylic acid, maleic acid and the like can be mentioned.

  As an anionic resin comprising an anionic monomer and a hydrophobic monomer as one embodiment of the resin according to the present invention, any one selected from the hydrophobic monomers listed above and the anionic monomers listed above It consists of at least two or more monomers with at least one selected from

  In consideration of dispersion stability and the like, a nonionic component such as ethylene oxide may be added to the resin.

  The resin includes a block copolymer, a random copolymer, a graft copolymer, or a salt thereof. Examples of the salt include alkali metal salts such as sodium, lithium, and potassium, ammonium salts, alkylamine salts, alkanolamine salts, and the like, and these can be used alone or in combination of several kinds.

  The glass transition temperature of the resin is preferably 30 ° C. or higher in consideration of scratch resistance on glossy paper and glossy media.

  The resin preferably has a weight average molecular weight of 1,000 to 30,000, more preferably 3,000 to 15,000.

  In consideration of dispersion stability and the like, the pigment weight percent with respect to the total weight of the ink composition is preferably 0.1 to 15 weight percent.

  Further, as described above, there is a problem that the amount of the binding resin depends on the pigment type and the resin type in the type of the pigment that binds the resin to the surface.

  Considering the scratch resistance on glossy paper and glossy media, in order to overcome the above-mentioned adverse effects, the ratio R / P of the resin to the pigment contained in the ink composition should be 0.15 or more. In addition, it is necessary to add a pigment dispersed with a resin to prepare an ink. In other words, by defining the ratio of the total resin amount to the pigment rather than the total resin amount present in the ink, the intended scratching property is realized.

  At that time, considering the reliability of the head and the like, the R / P ratio is preferably 2 or less, more preferably 1 or less.

  Further, by adding a pigment dispersed by a resin, it is possible to exhibit further effects such as improvement of color developability and color reproduction range in addition to scratching on a special medium. The pigment type and resin B used at this time may be appropriately selected in consideration of the desired color developability and color reproduction range.

  In addition, when adding the resin, the coagulation value is preferably low from the viewpoint of the reactivity between the ink composition and the reaction liquid.

(Coagulation value test)
5 g of the reaction solution diluted 100-fold with pure water is placed in a container with an inner diameter of 10 mm, and 0.25 g of the ink composition is dropped into this container, and the mixture is allowed to stand for 60 minutes in a normal temperature and humidity environment (approximately 25 ° C./60%). The ratio of the height of the aggregate to the height from the bottom surface of the container to the liquid level after placing is defined as a coagulation value.

(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.

  Regarding the method of applying the reaction liquid, an ink jet method may be used as in the case of the ink, and of course, any conventionally known application method such as an application method such as bar coating, roller coating, or spray coating may be used. . Further, in detail, from the viewpoint of a certain modification on the recording medium, which is the object of the present invention, it is preferable to modify the entire surface of the recording medium in order to exhibit the effects of the present invention more reliably. It can also be said that. In consideration of the above points, the application of the reaction liquid to the recording medium does not necessarily have to be an ink jet system like the ink. Rather, the roller coat, the bar coat, and the spray coat as shown in FIGS. In some cases, it is preferable to modify the entire surface of the recording medium by the above-described method. These units may be integrated with the recording apparatus or separated.

(Metal salt)
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. For ^{example, Ca 2+, Cu 2+, Ni} 2+, Mg 2+, Zn 2+, and divalent metal ions or ^{Ba 2+, etc., Al 3+, Fe 3+, Cr} 3+, and trivalent metal ions of ^{Y 3+,} etc. However, it is not limited to this.

  In view of the effect of the present invention, the content of polyvalent metal ions in the reaction solution is preferably 0.01% or more and 10% or less on a mass basis with respect to the total amount of the reaction solution. More preferably, 1.0% or more and 5.0% or less. Furthermore, in order to sufficiently exhibit the function of destabilizing the ink and to obtain a high level of image uniformity and optical density, It is preferable to contain 2.0% to 4.0% of polyvalent metal ions. Moreover, it is also possible to contain more than 10% of polyvalent metal ions in the reaction solution. However, the reason is that it is necessary to add a large amount of a compound for preventing precipitation, and that even if it is added in an amount of more than 10%, a significant increase in the function of destabilizing the ink cannot be expected. And it is not so preferable to make it contain excessively.

  Further, the reaction solution preferably contains no color material and is transparent, but it does not necessarily have to exhibit no absorption in the visible region. That is, even if the absorption is shown in the visible range, the absorption may be shown in the visible range as long as it does not substantially affect the image.

(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 inks of different color tones are 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 that has discharge energy generating means and performs recording by discharging ink onto a recording medium facing the discharge port surface on which 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 ink jet 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. It is preferable for the present invention to use polyurethane, polypropylene or the like as the material of the ink absorber.

  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. Is pressed vertically 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, a mode in which recording is performed by attaching to a recording head 1501 configured by dividing ink flow paths is also possible.

  EXAMPLES Next, although an Example and a comparative example are given and this invention is demonstrated more concretely, this invention is not limited from the following Example, unless the summary is exceeded. In the text, “parts” and “%” are based on mass unless otherwise specified.

(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 (pigment dispersion Bk1)
This pigment dispersion contains the first colorant.

500 g of carbon black having a specific surface area of 220 m ² / g and a DBP oil absorption of 112 ml / 100 g, 45 g of aminophenyl-2-sulfoethylsulfone (APSES), 900 g of distilled water, were charged into the reactor at 55 ° C. And stirred at a rotational speed of 300 RPM for 20 minutes. Thereafter, 40 g of 25% sodium nitrite was added dropwise over 15 minutes, and 50 g of distilled water was further added. Then, it was kept at 60 ° C. and reacted for 2 hours. The reaction product was taken out while diluting with distilled water and adjusted to a concentration of 15% solids. Then, the centrifugation process and the refinement | purification process which removes an impurity were performed. The obtained dispersion became a dispersion in which the functional group of (APSES) described above was bonded to carbon black. This dispersion is designated as A1.

  In order to obtain the number of moles of the functional group bonded to the carbon black in the dispersion A1, the following operation was performed. Na ions in the dispersion were measured with a probe-type sodium electrode, and the obtained value was converted per carbon black powder to determine the number of moles of functional groups bonded to carbon black.

  Subsequently, the dispersion A1 having a solid content of 15% prepared above was dropped into a pentaethylenehexamine (PEHA) solution. At this time, the PEHA solution was kept at room temperature while vigorously stirring, and the dispersion A1 was added dropwise over 1 hour. The PEHA concentration at this time was 6 times the number of moles of Na ions measured previously, and the amount of the solution was the same as that of the dispersion A1. Furthermore, after this mixture was stirred for 30 hours, a purification treatment for removing impurities was performed. Finally, a 10% solid dispersion with pentaethylenehexamine (PEHA) bound thereto was obtained. This dispersion is designated as B1.

  Next, 500 g of the dispersion B1 having a solid content of 10% prepared above and an aqueous solution in which a styrene / acrylic acid copolymer was dissolved were added dropwise with stirring. The aqueous styrene / acrylic acid copolymer solution used here weighed 190 g of a styrene / acrylic acid copolymer having an acid value of 200 and a weight average molecular weight of 10,000, and 1,800 g of distilled water was added thereto. It was prepared by adding NaOH necessary for neutralizing the resin, stirring and dissolving. Next, the dripping mixture is transferred to a Pyrex (registered trademark) evaporating dish, heated at 150 ° C. for 15 hours to evaporate, and the evaporated dry product is cooled to room temperature. Next, this evaporated and dried product is dispersed in a NaOH-added distilled water adjusted to pH = 9.0 using a disperser. Further, 1.0 M NaOH is added with stirring to adjust the pH to 10-11. Thereafter, desalting, purification for removing impurities, and coarse particle removal were performed to obtain a pigment dispersion Bk1.

The obtained pigment dispersion Bk1 had a solid content of 12% and an amount of resin bonded to the pigment surface of 3.4%. (The amount of resin bound to the pigment surface was confirmed by thermal analysis.)
(Pigment dispersion C1, pigment dispersion M1, pigment dispersion Y1)
In the same procedure as the pigment dispersion Bk1, cyan, magenta, and yellow also contain pigments in which styrene / acrylic acid copolymer (acid value 200, weight average molecular weight 10,000) is chemically bonded to the pigment particle surface. A dispersion was obtained. 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 E 02 (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 of each dispersion and the amount of resin bonded to the pigment surface are shown in Table 1 below.

(Pigment dispersion Bk2)
10 parts of carbon black having a specific surface area of 220 m ² / g and a DBP oil absorption of 112 ml / 100 g, an anionic polymer P-1 (styrene-acrylic acid copolymer, acid value 200, weight average molecular weight 10,000, A 10% solids aqueous solution, neutralizing agent: 40 parts of potassium hydroxide) and 60 parts of pure water are mixed, and the following materials are charged into a batch type vertical sand mill (manufactured by IMEX), and 0.3 mm diameter zirconia beads 150 parts were filled and dispersed for 5 hours while cooling with water. This dispersion was centrifuged to remove coarse particles to obtain a pigment dispersion Bk2 having a solid content of about 10%.

(Pigment dispersion C2, pigment dispersion Y2)
A dispersion in which cyan, magenta, and yellow were dispersed with a styrene / acrylic acid copolymer (acid value 200, weight average molecular weight 10,000) was obtained in the same procedure as for pigment dispersion Bk2. Examples of cyan pigments include C.I. I. Pigment Blue 15: 3 (product name: Fastgen Blue FGF, manufactured by Dainippon Ink and Chemicals)), yellow pigments include C.I. I. Pigment Yellow 155 (product name: NOVOPERM YELLOW 4G (manufactured by Clariant)) was used. The obtained pigment dispersions are designated as pigment dispersion C2 and pigment dispersion Y2. The solid content of each dispersion is 13%.

  Bk, C, M, and Y inks were prepared with the compositions shown in Table 1 using the pigment dispersion prepared in the above procedure and the aqueous resin solution.

  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 2. These are referred to as Example 1 and Comparative Example 1, respectively.

  The R / P ratio and coagulation value of the ink composition used in the ink set are shown in Table 3 below.

  An inkjet recording apparatus BJF-900 (manufactured by Canon Inc.) having an on-demand type multi-recording head that ejects ink by applying thermal energy corresponding to a recording signal to the ink using the ink sets 1 and 2 described above. Recorded with a modified machine.

  The evaluation items are shown below. Copy paper (PB paper) and glossy media (PR101) were used as printing materials. At this time, in the case of copy paper (PB paper), after the reaction liquid was applied to the print area, ink was applied and image recording was performed. In the case of glossy media, image recording was performed using only ink without using a reaction solution.

(Image quality of plain paper)
A pattern in which black, cyan, magenta, and yellow solids were adjacent to each other and a character with 12 fonts were printed, and the quality of the character and the blurring of each color solid boundary portion were evaluated.

(Evaluation criteria)
○: Character quality of each ink is not disturbed, and there is no blurring of adjacent solid boundary portions of different colors.
Δ: Character quality of each ink is not disturbed, but blurring of adjacent solid boundary portions of different colors is slightly noticeable.
X: Character quality of each ink is disturbed, and blurring of adjacent solid boundary portions of different colors is also conspicuous.

(Abrasion resistance of glossy media)
Black, cyan, magenta, and yellow solids were printed, and after 10 minutes of printing, the solid portions were rubbed with fingers to evaluate scratch resistance.

(Evaluation criteria)
○: There is no shaving of the solid part for all colors.
Δ: The solid portion is shaved with some colors.
X: The solid portion is shaved for all colors.

  As is apparent from the above table, by using the ink of the present invention, it is possible not only to obtain good print quality as the ink alone, but also to exhibit good scratching properties with the glossy media, and it is good when used as an ink set. Image quality can be obtained.

  According to the present invention, it is possible to provide an ink composition and an ink set which can give high image density and good print quality on various recording media, and which are excellent in scratch resistance when recorded on a glossy medium. .

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. It is a schematic diagram which shows an example of the reaction liquid provision method. It is a schematic diagram which shows another example of the reaction liquid provision method.

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 321 Paper feed roller 322 Reaction liquid 323 Coating roller 324 Tank 331 Coating roller 901 Recording head 1001 Cartridge 1003 Liquid composition container 1005 Ink storage Contents 1101 printhead 1201 and 1203 cartridge 1205 recording head 1301 record unit 1303 recording head 1401 carriage 1501 recording head

Claims (2)

  A step of applying at least one ink composition to the recording medium and a step of applying a reaction liquid that reacts with at least one of the ink compositions, and depending on the type of the recording medium, the reaction liquid A self-dispersible pigment whose surface is modified with a water-soluble resin A, wherein the ink composition is used in a recording apparatus that performs recording by an image recording method. An ink composition comprising a second pigment dispersed in an ink by the action of a water-soluble resin B.   The ink used in the recording apparatus, wherein the R / P ratio is 0.15 or more, where P% is the weight percent of the pigment contained in the ink composition and R% is the weight percent of the water-soluble resin. Item 2. The ink composition according to Item 1.

Images