JP2006028256A - Black ink composition, inkjet ink and inkjet ink set - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a black ink composition that provides a black tone having excellent color development and fastness, especially color reproducibility. <P>SOLUTION: The black ink composition comprises a short-wave dye being a single compound exhibiting 440-540 nm absorption maximum of a visible absorption spectrum in a water solvent and 90-200 nm half-width and a long-wave dye exhibiting 550-700 nm absorption maximum and ≥100 nm half-width. When the chromaticity in forming a gray image (neutral color by CIE) by the black ink composition is shown by L<SP>*</SP>a<SP>*</SP>b<SP>*</SP>color system, chromaticity b<SP>*</SP>in 0.5-2.5 reflection concentration of gray image is in the range of 2 to -6. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a black ink composition (preferably a black ink composition for image formation (preferably an ink jet ink composition)) containing an azo dye having a specific structure and characteristics, and an ink jet recording method using the black ink composition About.

The ink jet recording method is rapidly spreading and further developing because of its low material cost, high speed recording, low noise during recording, and easy color recording.
Inkjet recording methods include a continuous method in which droplets are continuously ejected and an on-demand method in which droplets are ejected in accordance with image information signals. There are a method of discharging bubbles, a method of generating bubbles in the ink by heat and discharging droplets, a method of using ultrasonic waves, and a method of sucking and discharging droplets by electrostatic force.
As the ink for ink jet recording, water-based ink, oil-based ink, or solid (melted type) ink is used.

  For such colorants used in ink jet recording inks, they have good solubility or dispersibility in solvents, excellent color development, high density recording, good hue, light It is robust against active gases in the environment of heat, oxidizing gases such as NOx and ozone, SOx, etc., has excellent fastness to water and chemicals, and has fixability to image receiving materials. It is required that the ink does not bleed well, has excellent storability as an ink, has no toxicity, has high purity, and can be obtained at low cost. However, it is extremely difficult to search for colorants that meet these requirements at a high level. In particular, there is a strong demand for a colorant for black ink that has a good black tone, enables high-density printing, and is robust against light, humidity, and heat.

Conventionally, disazo dyes or trisazo dyes have been used as black pigments, but these dyes alone often lack blue to green light absorption and often do not provide a good black tone. In general, a dye for color correction that absorbs blue to green light is used in combination. As such a correction dye, for example, dyes as described in Patent Document 1 and Patent Document 2 have been proposed, and black tone adjustment ability, color developability, fastness, ink storage stability, water resistance, nozzle resistance, and the like. Improvements such as clogging have been attempted.
However, the conventionally proposed color correction dyes have the problem of lack of black tone adjustment ability, such as the necessity of adding a large amount because the absorption is too short, and the need for another color correction dye. It was.

  Dyes that can absorb blue to green light are generally known, but their fastness is inferior, so the hue changes greatly upon exposure to light, heat, and active gases in the environment, and the fixability is insufficient. For this reason, almost all of the phenomena such as yellowing of the outline portion under high humidity conditions occur, and further improvement is necessary.

In view of these drawbacks, Patent Document 3 describes a black ink composition comprising a triazine dye having a maximum absorption spectrum of 435 nm in an aqueous solvent as a color correction dye and a black dye. .
However, a general black dye has a maximum absorption of 570 to 620 nm, and even when the color correction dye is used, a suitable black tone cannot be obtained in consideration of a complementary color relationship important for black tone adjustment. This is clear (Non-Patent Document 1), and it has been found that there is a problem that the performance of color reproducibility when using black ink is not fully satisfied.
JP-A-9-255906 Japanese Patent No. 3178200 JP 2002-332426 A "Color Science Handbook (2nd edition)", The University of Tokyo Press, 1998, p560-562

An object of the present invention is to solve the above problems and achieve the following objects.
That is, the object of the present invention is to enable excellent black tone and high density printing without adding a large amount (or other short-wave side dyes are required), and excellent color development, fixing properties and fastness. It is to provide a short wave side dye. The present invention also provides a printing ink composition using such a short wave side dye and a water-based ink composition for writing.
Further, the object of the present invention is to have a good color tone for black, to enable high density printing, to form an image having high fastness to light and ozone, and to be stored under high humidity conditions. An object of the present invention is to provide an ink composition for ink jet recording having sufficient moisture resistance that does not cause bleeding, and an ink jet recording method using the ink composition for ink jet recording.

The present inventors have detailed various dye compounds aiming at color correction dyes having good black tone adjusting ability, good color development, high fastness to light and ozone, and excellent moisture resistance. As a result of the investigation, it has been found that the above-mentioned problems can be solved by dyes having the following specific structures and absorption characteristics.
(1) The short wavelength side dye, which is a single compound having an absorption maximum of 440 to 540 nm and a half width of 90 to 200 nm in an aqueous solvent, and an absorption maximum of 550 to 700 nm and a half width of 100 nm or more. A black ink composition containing a long-wave side dye as shown in the above, preferably when gray data of neutral color is output to a color printer and a gray image (neutral color by CIE) is formed with the black ink composition When the chromaticity is displayed in the L ^* a ^* b ^* color system, the chromaticity b ^* is in the range of 2 to −6 when the reflection density of the gray image is between 0.5 and 2.5. A black ink composition.
(2) The short wavelength side dye which is a single compound having an absorption maximum of 440 to 540 nm and a half-value width of 90 to 200 nm and an absorption maximum of 550 to 700 nm and a half-value width of 100 nm or more in an aqueous solvent. A black ink composition containing a long wave side dye as shown in FIG. 1, and forming a gray image (neutral color by CIE) having a reflection density of 1.0 with the black ink composition, A black ink composition having a color difference (ΔE _ab ^* ) of 20 or less before and after irradiation with xenon light (100,000 lux) for 14 days.
(3) The black ink composition as described in (1) or (2), wherein the single compound has 2 to 6 azo groups in one molecule and does not have a phenolic hydroxyl group. Here, the dissociable phenolic hydroxyl group means a dissociable hydroxyl group substituted with an aryl group. This aryl group may be substituted with other substituents.
(4) The black ink composition according to any one of (1) to (3), wherein the shortwave side dye is contained in the ink in an amount of 0.1 to 4% by mass.
(5) The black ink according to any one of (1) to (4), wherein the long wave side dye is a water-soluble black dye having 2 to 4 conjugated azo groups in one molecule. Composition.
(6) The black ink composition as described in (5), wherein the long wave side dye has a hydroxyl group at the conjugated position of the azo group (preferably the ortho position of the azo group). Here, the conjugated position means a substitution position having a conjugated relationship with the azo group, and the hydroxyl group is preferably substituted at the ortho position or the para position with respect to the substitution position of the azo group.
(7) The black ink composition as described in (5) or (6), wherein the long wave side dye has 1 or less heterocyclic group in the chromophore.
(8) An ink-jet ink comprising the composition according to any one of (1) to (8).
(9) An ink jet ink set comprising the ink jet ink.
(10) Forming an image by using an ink containing the composition according to any one of (1) to (8) on an image receiving material having an ink receiving layer containing white inorganic pigment particles on a support. An ink jet recording method.
(11) The short wavelength side dye which is a single compound having an absorption maximum of 440 to 540 nm and a half value width of 90 to 200 nm and an absorption maximum of 550 to 700 nm and a half value width of 100 nm or more in an aqueous solvent. When a black image composition containing a long-wave side dye is used and a gray image (neutral color by CIE) is formed with the black ink composition in a recording method for recording on a recording material in response to a recording signal When the chromaticity of the gray image is displayed in the L ^* a ^* b ^* color system, the chromaticity b ^* between the gray image reflection density of 0.5 and 2.5 is in the range of 2 to -6. A characteristic recording method.
(12) The short wavelength side dye, which is a single compound having an absorption maximum of 440 to 540 nm and a half width of 90 to 200 nm, and an absorption maximum of 550 to 700 nm and a half width of 100 nm or more in an aqueous solvent. In a recording method in which recording is performed on a recording material in accordance with a recording signal using a black ink composition containing the long-wave side dye shown, a gray image having a reflection density of 1.0 (middle by CIE) with the black ink composition A color difference (ΔE _ab ^* ) before and after irradiation with xenon light (100,000 lux) for 14 days using a weather meter manufactured by Atlas Co., Ltd. is 20 or less. Method.
(13) The recording method according to (11) or (12), wherein the single compound has 2 to 6 azo groups in one molecule and does not have a phenolic hydroxyl group.
(14) The recording method according to any one of (11) to (13), wherein the shortwave side dye is contained in an ink in an amount of 0.1 to 4% by mass.
(15) The recording method according to any one of (11) to (14), wherein the long wave side dye is a water-soluble black dye having 2 to 4 conjugated azo groups in one molecule. .
(16) The recording method according to (15), wherein the long wave side dye has a hydroxyl group at a conjugate position of an azo group (preferably an ortho position of the azo group).
(17) The recording method according to (15) or (16), wherein the long wave side dye has one or less heterocyclic group in a chromophore.
(18) The recording method according to any one of (15) to (17), wherein the long wave side dye has an associative property.
(19) An ink jet recording method using the recording method according to any one of (11) to (18).
(20) The ink jet recording method according to (19), wherein a recording material including an ink receiving layer containing white inorganic pigment particles is used on a support.

  By the ink for ink jet recording and the ink jet recording method using the black ink composition of the present invention, it is possible to form an image having high printing density and high fastness against light and active gas in the environment. It has an excellent black tone and a good color tone after irradiation with xenon light.

Hereinafter, the present invention will be described in more detail.
In the present invention, the short wavelength side dye which is a single compound having an absorption maximum in the visible region absorption spectrum of 440 to 540 nm and a half width of 90 to 200 nm and an absorption maximum of 550 to 700 nm and a half width of 100 nm or more in an aqueous solvent. A black ink composition containing a long-wave side dye, preferably achromatic gray data is output to a color printer, and a gray image (neutral color by CIE) is formed with the black ink composition When the chromaticity of the gray image is displayed in the L ^* a ^* b ^* color system, the chromaticity b ^{* of} the gray image having a reflection density of 0.5 to 2.5 may be in the range of 2 to −6. It is a feature.
Further, in the present invention, the short wavelength side dye which is a single compound having an absorption maximum in the visible region absorption spectrum in an aqueous solvent of 440 to 540 nm and a half width of 90 to 200 nm and the absorption maximum is 550 to 700 nm, and the half width is A black ink composition containing a long-wave dye having a wavelength of 100 nm or more, and forming a gray image (neutral color by CIE) having a reflection density of 1.0 with the black ink composition. It is characterized in that the color difference (ΔE _ab ^* ) before and after irradiation with xenon light (100,000 lux) using a weather meter made for 14 days is 20 or less.
Here, said the b ^* and Delta] E _ab ^* are those in the L ^* a ^* b ^* color system, for L ^* a ^* b ^* color system, Handbook of Image Analysis (University of Tokyo Press) Fourth Printing (July 15, 1992), pages 108-109 can be referred to.
[dye]
The short-wave dye, which is a single compound of the present invention, is a dye that achieves broad absorption in the visible absorption spectrum in an aqueous solvent, having an absorption maximum at 440 to 540 nm and a half-value width of 90 nm to 200 nm ( Hereinafter, in order to avoid confusion, the dye is referred to as “shortwave dye S”).
In the present specification, the term “single compound” means a compound that is not a plurality of compounds having different physical properties. That is, when a visible region absorption spectrum in an aqueous solvent is measured, combining a plurality of compounds does not indicate physical properties such as a desired absorption maximum and a full width at half maximum, but indicates that such physical properties are exhibited by one compound.
Since the short wave dye S has such an absorption characteristic, it can absorb a wide range of light from blue to green, which tends to be insufficient in the absorption spectrum of the disazo dye or the trisazo dye, and is a preferable absorption as a color correction dye. Has characteristics.
The absorption maximum of the short wave dye S is preferably between 450 and 520 nm, particularly preferably between 460 and 500 nm.
The full width at half maximum of the short wave dye S is preferably between 100 nm and 180 nm, particularly preferably between 110 nm and 160 nm.

Further, the short wave dye S of the present invention preferably does not have a dissociable phenolic hydroxyl group present in a general pigment. Owing to such a structure, there is little change in color tone depending on the image receiving material to be used. It has preferable performance such as low reactivity with oxidizing gas such as excellent gas resistance.
Furthermore, it is preferable that the short wave dye S of the present invention has 2 to 6 azo groups in one molecule, and this structure enhances color developability and also has a fixing property because the dye plane is greatly expanded. Can give a good picture.
Further, the number of the azo groups is more preferably 4 to 6 per molecule from the viewpoint of color development and fixing properties.

The short wave dye S is not particularly limited as long as it has the physical properties defined in the present specification and solves the above problems, and examples thereof include polyazo dyes represented by the following general formula.
(D) n-Y
In the above general formula, D represents a dye residue composed of 2 to 3 azo groups conjugated with each other and 3 to 4 aromatic rings having a total of 20 or more π electrons. , N is 1 or 2, when n is 1, Y represents a hydrogen atom, and when n is 2, Y represents a divalent linking group. The aromatic ring constituting the chromophore may be a heterocyclic ring or a hydrocarbon ring, but is preferably a hydrocarbon ring. When the aromatic ring constituting the chromophore is a condensed ring, the number of π electrons on the aromatic ring is the number of π electrons as the whole condensed ring. For example, a naphthalene ring has 10 π electrons. It is. The divalent linking group represented by Y is an alkylene group, an arylene group, a heterocyclic residue, -CO-, -SOn- (n is 0, 1, 2), -NR- (R is a hydrogen atom, alkyl Group, represents an aryl group), —O—, and a divalent group obtained by combining these linking groups, and further includes an alkyl group, an aryl group, an alkoxy group, an amino group, an acyl group, an acylamino group, and a halogen atom. May have a substituent such as a hydroxyl group, a carboxyl group, a sulfamoyl group, a carbamoyl group, or a sulfonamide group. Particularly preferred examples of the linking group include —NH—CO—NH—, —NH—CS—NH—, and groups having the following general formula.

  In the above general formula, X represents a hydroxyl group, a sulfo group, an alkoxy group, an aryloxy group, an amino group (including an alkylamino group or an arylamino group), or an alkyl or arylsulfenyl group, and each group further has a substituent. You may have.

  For example, commercially available CIDirect Red 84, Brown 106, and Brown 202 are useful as such short-wave dye S, and CI Direct Red 84, which can be used to adjust the color tone of many black dyes and is excellent in color development, fastness, and fixing properties. Is particularly useful.

Furthermore, although the example of the short wave dye S preferably used by this invention is shown with the structure of a free acid below, it cannot be overemphasized that you may use as arbitrary salts.
Preferred counter cations include alkali metals (eg, lithium, sodium, potassium), ammonium, and organic cations (eg, pyridinium, tetramethylammonium, guanidinium).

Among them, CI Direct Red 84 (Na salt of the above compound example 2) and Brown 106 (Na salt of the above compound example 14) are preferable because they are commercially available dyes, and are particularly suitable for adjusting the color tone of many black dyes. CIDirect Red 84, which can be used and has excellent color development, fastness, and fixing properties, is particularly useful.
In addition, the short wave dye S other than the commercially available dye can be easily obtained from commercially available raw materials according to the synthesis route of CI Direct Red 84 or Brown 106 described in Color Index Vol. 4 (issued by The Society of Dyers and Colorists). Can be synthesized.
In the present invention, two or more of the short wave dyes S may be used in combination.

  The black ink composition of the present invention preferably contains 0.1 to 4% by mass, preferably 0.5 to 3.0% by mass, particularly preferably 1.0 to 2.5% by mass of the short wave dye S in the ink. It is also possible to change.

  The black ink composition of the present invention is a water-soluble black dye having 2 to 4 conjugated azo groups in one molecule as a long wave side dye, preferably having an absorption maximum wavelength longer than 550 nm. It is preferable to contain a water-soluble black dye (hereinafter referred to as “long wave dye L”). Further, by using the long wave dye L in combination with the short wave dye S, a good black tone can be obtained.

Furthermore, the long wave dye L has a hydroxyl group at the conjugated position of the azo group, or the number of heterocyclic groups in the chromophore is 1 or less. It is preferable for securing a wide absorption characteristic having a half width suitable for the color tone and ink stability.
In general, a dye having a hydroxyl group at the conjugated position of an azo group may be inferior in fastness to light or active gas in the air depending on the type of image receiving material and the storage conditions of the printed matter. What has the property which has an associative property and can suppress reaction physically is still more preferable.
As to whether the dye is in an association state, measure the visible absorption spectrum by changing the solvent type or the dye concentration, and check whether the dye has an association property by examining the change in the absorption maximum wavelength, molar extinction coefficient and waveform. Therefore, it can be easily judged from a comparison between the physical properties of the solution and the absorption spectrum of the dye on the image receiving material.
Specifically, as defined in Japanese Patent Application No. 2004-65569, a molar extinction coefficient (ε1) at a maximum wavelength of absorption in the visible region, measured using a 0.1 mmol / l dye aqueous solution using a cell having an optical path length of 1 cm, A dye that satisfies the relationship of ε1 / ε2> 1.2 between the molar extinction coefficients (ε2) when a 0.2 mol / l aqueous solution is measured using a liquid crystal cell having an optical path length of 5 μm is preferable.

Among the long wave dyes L preferably used in the present invention and having an absorption maximum wavelength longer than 550 nm, those corresponding to the following general formula are particularly preferable.
In the following general formula, the dye is represented by the structure of a free acid, but it goes without saying that it may be used in the form of a salt in actual use.

In the above general formulas 1 to 3, when there are a plurality of substituents represented by the same symbol in the same molecule, they may be the same as or different from each other. X represents an amino, a hydroxyl group or a hydrogen atom. Y represents a hydrogen atom or an amino group. R represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aralkyl group, an alkenyl group, an aryl group, a heterocyclic group, an acyl group, or a sulfonyl group, which may have a substituent. Representative examples of the substituent that may be included include halogen atoms, ionic hydrophilic groups (sulfo groups, carboxyl groups, etc.), alkoxy groups, hydroxy groups, acylamino groups, acyl groups, carbamoyl groups, sulfamoyl groups, and the like. Can be cited as a thing. n represents an integer of 0 to 3, and the sulfo group may be substituted at any position of the benzene ring or naphthalene ring. A ₁ and A ₂ each represent a monovalent aromatic group or a heterocyclic group. B represents a divalent aromatic group or a heterocyclic group. A ₁ and A ₂ may be further substituted with an azo group. A ₁ , A ₂ and B may further have a substituent. The number of heterocyclic groups contained in the chromophore of the dye is preferably 1 or less. Further, a part of the dyes represented by these general formulas may be dissociated to form a chelate dye coordinated with a transition metal.

Among the above general formulas, the dyes represented by the general formula 1 or the general formula 2 are preferable, and among them, the dyes of the general formula 1 are particularly preferable. Among the dyes of the general formula 1, those in which X is an amino group or a hydroxyl group are preferred, and those having a hydroxyl group are particularly preferred. Further, from the viewpoint of fastness, it is preferable that the electron withdrawing group is substituted on the dye or that any of A ₁ , A ₂ and B is a heterocyclic group.
Preferred examples of the electron withdrawing group include a nitro group, a cyano group, a halogen atom, a sulfamoyl group, a carbamoyl group, and an ester group.
Examples of the heterocyclic ring constituting the preferable heterocyclic group include pyrazole, thiazole, isothiazole, oxazole, isoxazole and pyridine which may have a condensed ring.
Particularly preferred among the general formula 1 is a compound represented by the following general formula 4.

In General Formula 4, A ₃ and A ₄ each independently represent a heterocyclic group or an aryl group represented by General Formula 5. n represents an integer of 0 to 3.

  In the general formula 5, EWG (Electron Withdrawing Group) is an electron-withdrawing group selected from the group consisting of a nitro group, a cyano group, an azo group, a sulfamoyl group, a carbamoyl group, and an ester group, Represents an azo group. Z represents a substituent selected from an alkyl group, an alkoxy group, a sulfo group, a carboxyl group, an amino group, and an acylamino group. The substituent represented by EWG or Z may further have a substituent. p represents an integer of 0 to 4. q represents an integer of 0 to 3, preferably 1 or 2.

Although the example of the preferable long wave dye L is shown with the structure of a free acid below, it cannot be overemphasized that you may use as arbitrary salts.
Preferred counter cations include alkali metals (eg, lithium, sodium, potassium), ammonium, and organic cations (eg, pyridinium, tetramethylammonium, guanidinium).
In the present invention, two or more of the long wave dyes L may be used in combination.

  In addition to the dyes represented by the above formula, JP-A-10-130557, JP-A-9-255906, JP-A-7-97541, JP-A-6-234944, European Patent 982371A1, JP-A-2002-302619, 2002-2002. No. 327131, 2002-265809, International Publication Nos. 2000-43450, 2000-43451, 2000-43451, 2000-43453, 2003-106572, 2003-104332 These dyes can also be preferably used as the long wave dye L.

The black ink composition of the present invention preferably contains 0.2 to 30% by mass, particularly preferably 0.5 to 15% by mass, and most preferably 1 to 10% by mass of the long wave dye L in the ink. preferable.
The ratio of the short wave dye S and the long wave dye L of the present invention is preferably 1 to 50% by mass, more preferably 5 to 40% by mass with respect to the long wave dye L. Most preferably, it is -30 mass%.

[ink]
The ink of the present invention means an ink containing at least one water-soluble dye of the present invention. The ink of the present invention can contain a medium, but when a solvent is used as the medium, it is particularly suitable as an ink for inkjet recording.
The ink of the present invention can be prepared by dissolving and / or dispersing the dye of the present invention in a lipophilic medium or an aqueous medium as a medium. Preferably, an aqueous medium is used. As the aqueous medium, a mixture containing water as a main component and optionally adding a water-miscible organic solvent can be used. Examples of the water miscible organic solvent include those described in JP-A No. 2003-306623. In addition, the said water miscible organic solvent may use 2 or more types together. The ink of the present invention includes an ink composition excluding a medium.

  The ink of the present invention may contain other additives as necessary within a range that does not impair the effects of the present invention. Other additives include, for example, anti-drying agents (wetting agents), anti-fading agents, emulsion stabilizers, penetration enhancers, ultraviolet absorbers, preservatives, anti-fungal agents, pH adjusters, surface tension adjusters, Well-known additives (refer Unexamined-Japanese-Patent No. 2003-306623), such as a foaming agent, a viscosity modifier, a dispersing agent, a dispersion stabilizer, a rust preventive agent, and a chelating agent, are mentioned. These various additives are directly added to the ink liquid in the case of water-soluble ink.

  The method for preparing the ink for ink jet recording is described in detail in JP-A-5-295212, JP-A-7-97541, and JP-A-7-82515 in addition to the above-mentioned patent documents. It can also be used for preparing ink jet recording inks.

  In addition to the short wave dye S and the long wave dye L of the present invention, other dyes may be used in combination with the inkjet ink of the present invention. When two or more kinds of dyes are used in combination, the total dye content is preferably 0.1 to 30 parts by mass in 100 parts by mass of the ink jet recording ink, and 0.2 parts by mass The content is more preferably 20 parts by mass or less, and still more preferably 0.5 to 15 parts by mass.

  The ink of the present invention can be used not only for monochromatic image formation but also for full color image formation. In order to form a full-color image, in addition to the ink of the present invention, a magenta color ink, a cyan color ink, and a yellow color ink can be used, and two-color inks can be used for each color. Furthermore, an intermediate tone ink such as blue or orange can be used.

  As the dye that can be used in the ink for ink jet recording and the ink of each color used for full color image formation in the present invention, any dye can be used. For example, paragraph number of JP-A-2003-306623 Each dye described in 0090 to 0092 can be used.

[Inkjet recording method]
In the recording method of the present invention (preferably an ink jet recording method), energy is supplied to the recording ink, and a known image receiving material as a recording material, that is, plain paper, resin-coated paper, for example, JP-A-8-169172. JP-A-8-27693, JP-A-2-276670, JP-A-7-276789, JP-A-9-323475, JP-A-62-238783, JP-A-10-153789, JP-A-10-217473. No. 10-235995, No. 10-337947, No. 10-217597, No. 10-337947, etc., dedicated inkjet paper, film, electrophotographic co-paper, fabric, glass Form images on metal, ceramics, etc. As the image receiving material, an image receiving material having an ink receiving layer containing white inorganic pigment particles on a support is preferable. The description of paragraph numbers 0093 to 0105 of JP-A No. 2003-306623 can be applied as the ink jet recording method of the present invention.

  In forming an image, a polymer latex compound may be used in combination for the purpose of imparting glossiness or water resistance or improving weather resistance. The timing of applying the latex compound to the image receiving material may be before, after, or simultaneously with the application of the colorant, and therefore the addition location may be in the image receiving paper. It may be in ink or may be used as a liquid material of polymer latex alone. Specifically, JP 2002-166638, JP 2002-121440, JP 2002-154201, JP 2002-144696, JP 2002-080759, Japanese Patent Application 2000-299465, and Japanese Patent Application 2000. The method described in -297365 can be preferably used.

  Polymer latex may be added to the constituent layers (including the backcoat layer) of the ink jet recording paper and recording film. The polymer latex is used for the purpose of improving film physical properties such as dimensional stabilization, curling prevention, adhesion prevention, and film cracking prevention. The polymer latex is described in JP-A Nos. 62-245258, 62-1316648, and 62-110066. When a polymer latex having a low glass transition temperature (40 ° C. or lower) is added to a layer containing a mordant, cracking and curling of the layer can be prevented. Also, curling can be prevented by adding a polymer latex having a high glass transition temperature to the backcoat layer.

  The ink of the present invention is not limited to the ink jet recording method, and is a known method, for example, a charge control method for ejecting ink using electrostatic attraction, a drop on demand method (pressure) using the vibration pressure of a piezo element. Pulse method), acoustic ink jet method that converts electrical signals into acoustic beams, irradiates ink and ejects ink using radiation pressure, and thermal ink jet that heats ink to form bubbles and uses the generated pressure Used for systems. Inkjet recording methods use a method of ejecting a large number of low-density inks called photo inks in a small volume, a method of improving the image quality using a plurality of inks having substantially the same hue and different concentrations, and colorless and transparent inks. The method is included.

[Example]
EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to this.

  After adding ultrapure water (resistance value of 18 MΩ or more) to the following components to make 1 liter, the mixture was stirred for 1 hour while heating at 30 to 40 ° C. Thereafter, the mixture was filtered under reduced pressure with a microfilter having an average pore diameter of 0.25 μm to prepare a black ink liquid Bk-101 as a black ink composition.

[Black ink Bk-101 prescription]
(Solid content)
Long wave dye L (Li salt of long wave dye L compound example 1-19) 60g / l
Shortwave dye S (Na salt of compound example 2 of shortwave dye S: CIDirect Red 84) 15g / l
Proxel 5g / l
Urea 20g / l
Benzotriazole 3g / l
(Liquid component)
Diethylene glycol monobutyl ether (DGB) 100g / l
Glycerin (GR) 125g / l
Diethylene glycol (DEG) 100g / l
2-pyrrolidone 100g / l
Triethanolamine (TEA) 30g / l
Surfynol STG (Air Products) (SW) 10g / l

The black inks of the black ink liquids Bk-101 and PM-G800 were loaded into a black ink cartridge of an ink jet printer PM-920C manufactured by EPSON, and a gray image pattern having a density changed stepwise was printed. The image-receiving sheet was printed on Epson inkjet printer paper photographic paper <glossy> and evaluated for image quality, ink ejection and image fastness. In the case of Bk-101, sample No. 101, and the case of PM-G800 black ink is sample No. 102. Absorption spectrum in water of long wave dye L used above: λmax = 578 nm, half width = 130 nm, Absorption spectrum of short wave dye S in water: λmax = 472 nm, half width = 130 nm.
(Evaluation experiment)
1) About discharge stability, after setting a cartridge in a printer and confirming the protrusion of the ink from all the nozzles, 20 sheets of A4 were output and evaluated according to the following criteria.
A: No printing disturbance from the start to the end of printing B: Output with a disturbance in printing occurs C: Printing is disturbed from the start to the end of printing This experiment was performed immediately after ink filling (ejection A) and the ink cartridge The test was carried out after storage for 2 weeks (dischargeability B) at 40 ° C. and 80% RH.
2) The image storability of the yellow dye was evaluated as follows using a print sample.
[1] Light fastness is measured by measuring the image density Ci immediately after printing with X-rite 310, then irradiating the image with xenon light (100,000 lux) using an Atlas weather meter for 14 days, and then again image density Cf was measured and the dye residual ratio Cf / Ci × 100 was determined and evaluated. The afterimage rate of the dye is evaluated at three points of reflection density of 1, 1.5, and 2. A is the case where the dye residual rate is 70% or more at any concentration, and B is the case where the point is less than 70%. When the concentration was less than 70%, C was designated.
[2] For ozone resistance, the photographic paper <glossy> on which the image has been formed is left in a box where the ozone gas concentration is set to 5 ppm for 10 days, and the image density before and after being left under ozone gas is measured using a reflection densitometer (X -Rite310TR), and evaluated as a dye residual ratio. The reflection density was measured at three points of 1, 1.5 and 2.0. The ozone gas concentration in the box was set using an ozone gas monitor (model: OZG-EM-01) manufactured by APPLICS.
Evaluation was made in three stages, with A being a dye residual ratio of 80% or more at any concentration, A being 1 or 2 points being less than 80% B, and C being less than 70% at all concentrations.
3) Regarding the chromaticity, CIEL ^* a ^* b ^* was measured with a SpectroEye manufactured by GretagMacbeth for a gray monochromatic image pattern whose density changed stepwise. Color difference before and after irradiation of xenon light (100,000 lux) using a weather meter manufactured by Atlas for 14 days with a b ^* value between 0.5 and 2.0 and a reflection density of 1.0. (ΔE _ab ^* )
Is shown in the table below.

From the results in the table, it was found that the system using the ink of the present invention was superior in light fastness performance (color change after fading was small).
As a result of printing the image on the Epson inkjet printer paper photographic paper <glossy> and performing the same evaluation, the value of b ^* in the case of Bk-101 is 1 to -3, and in the case of PM-G800, b ^* is b ^* . The value was -3 to -7, and it was shown that the ink liquid of the present invention has excellent color reproducibility.
As a result of printing the image receiving sheet on Epson inkjet printer paper photographic paper <silk-tone> and performing the same evaluation, the value of b ^* in the case of Bk-101 is 1-2, and in the case of PM-G800 black The value of b ^* was −2 to −8, indicating that the ink liquid of the present invention has excellent color reproducibility.

Claims (9)

The short wave side dye which is a single compound having an absorption maximum of 440 to 540 nm and a half value width of 90 to 200 nm in an aqueous solvent, and a long wave side having an absorption maximum of 550 to 700 nm and a half value width of 100 nm or more. A black ink composition containing a dye, wherein the chromaticity when a gray image (neutral color by CIE) is formed with the black ink composition is displayed in the L ^* a ^* b ^* color system, A black ink composition, wherein a gray image has a reflection density of 0.5 to 2.5 and a chromaticity b ^* of 2 to -6. The short wave side dye which is a single compound having an absorption maximum of 440 to 540 nm and a half value width of 90 to 200 nm in an aqueous solvent, and a long wave side having an absorption maximum of 550 to 700 nm and a half value width of 100 nm or more. A black ink composition containing a dye, and forming a gray image (neutral color by CIE) having a reflection density of 1.0 with the black ink composition, and using the weather meter manufactured by Atlas A black ink composition having a color difference (ΔE _ab ^* ) before and after irradiation with xenon light (100,000 lux) for 14 days is 20 or less.   The black ink composition according to claim 1 or 2, wherein the single compound has 2 to 6 azo groups in one molecule and does not have a phenolic hydroxyl group.   The black ink composition according to claim 1, wherein the short wave side dye is contained in an amount of 0.1 to 4% by mass in the ink.   5. The black ink composition according to claim 1, wherein the long wave side dye is a water-soluble black dye having 2 to 4 conjugated azo groups in one molecule.   The black ink composition according to claim 5, wherein the long wave side dye has a hydroxyl group at a conjugate position of an azo group.   The black ink composition according to claim 5 or 6, wherein the long wave side dye has 1 or less heterocyclic group in a chromophore.   An ink-jet ink comprising the composition according to claim 1.   An ink jet ink set comprising the ink jet ink.