JP2007070566A - Ink stock solution and inkjet ink composition using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink stock solution suppressing dye precipitation and separation in the ink stock solution and improving quality of the dye and handleability in production even when used under a low temperature environment wherein the ink stock solution is frozen, and capable of avoiding increase of the production cost. <P>SOLUTION: The ink stock solution comprising at least water and a water-soluble dye and having ≥7 mass% dye content based on solid concentration contains at least one selected from the additive agent A group consisting of (a) monosaccharides, polysaccharides and derivatives thereof, (b) glycerol and alkylene glycols, (c) amino acids and amino acid derivatives, (d) urea and derivatives thereof and (e) compounds having a cyclic amide. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ink stock solution having a high dye concentration, which is a raw material for an ink-jet ink composition, and an ink-jet ink composition produced using the same.

In recent years, with the spread of computers, ink jet printers are widely used for printing on paper, film, cloth and the like not only in offices but also at home.
Inkjet recording methods include a method in which droplets are ejected by applying pressure using a piezo element, a method in which bubbles are ejected by generating bubbles in the ink composition by heat, a method using ultrasonic waves, or an electrostatic force. There is a method of sucking and discharging droplets. As these ink compositions for ink jet recording, water-based ink compositions, oil-based ink compositions, or solid (melted-type) ink compositions are used. Among these ink compositions, water-based ink compositions have become mainstream from the viewpoints of production, handleability, odor, safety, and the like.

For the colorant used in these ink jet recording ink compositions, it has high solubility in solvents, high density recording is possible, hue is good, light, heat, air, ozone, Excellent fastness to water and chemicals, good fixability to image-receiving materials, difficult to bleed, excellent storage stability as ink composition, no toxicity, high purity, and It is required to be available at low cost. However, it is extremely difficult to search for colorants that meet these requirements at a high level.
Various dyes and pigments have already been proposed and actually used for inkjet, but no colorant that satisfies all the requirements has yet been discovered. Conventionally well-known dyes and pigments having a color index (CI) number are difficult to achieve both hue and fastness required for an ink composition for ink jet recording. .

Therefore, the inventors of the present invention proposed a technique for improving the fastness of a dye by strengthening the interaction between dye molecules and making the presence state of the dye on the ink-jet image receiving paper similar to the pigment in Patent Document 1 and the like. However, when the interaction between the dye molecules was strengthened in this way, it was found that when used in a low temperature environment, there was a problem that the dye was precipitated, particularly in an ink stock solution having a high dye concentration. .
If the dye precipitates and is separated by freezing, it causes an increase in the variation of the dye concentration in the ink stock after thawing, and the redissolution of the dye after thawing becomes insufficient, increasing the filtration pressure during filtration and the ink absorbance. Manufacturing and quality problems such as degradation occur. In addition, a process for heating the ink stock solution is required to release the freezing, resulting in an increase in manufacturing cost.

  Patent Document 2 discloses a method of adding a cryoprotectant to an ink-jet ink composition, but it is an invention for an ink using a pigment as a colorant, and the stability of the ink is related to the aggregation of pigment particles. The effect is only stated, not the effect on the redissolvability of the dye. Further, the invention describing the effect of addition to an ink stock solution having a high dye concentration, in which the precipitation of the dye becomes more conspicuous under a low temperature environment, is novel. Furthermore, although these additives are described as having an effect on re-dissolution after freezing, they are not described at all as to the effect during preparation.

JP 2004-115620 A Japanese Patent Laid-Open No. 2001-271013

  The problem to be solved by the present invention is to suppress the precipitation and separation of the dye in the ink stock solution even when used in a low temperature environment where the ink stock solution freezes, and to improve the quality of the dye and the handleability during production. It is an object to provide an ink stock solution that is high and avoids an increase in manufacturing cost, and has excellent workability during preparation of the ink stock solution, and an ink-jet ink composition using the same.

The problems of the present invention can be solved by the following means.
1) An ink stock solution containing at least water and a water-soluble dye and having a dye concentration of 7% by mass or more in solid content contains at least one selected from the following additive A group. Ink stock solution.
a) Monosaccharides, polysaccharides and derivatives thereof b) Glycerin and alkylene glycol c) Amino acids and amino acid derivatives d) Urea and derivatives thereof e) Compounds having a cyclic amide group 2) Surface tension at 25 ° C. of 50 mN / m or more 1) The ink stock solution according to 1).
3) Using a cell with an optical path length of 10 mm, the molar extinction coefficient is 25 when the dye is diluted with water so that the absorbance at the maximum absorption wavelength (λmax) in visible light (350 to 700 nm) is 1.0. The ink stock solution according to 1) or 2), which is 1,000 or less.
4) Using a cell having an optical path length of 10 mm, the concentration of the dye was diluted 2000 times with water so that the absorbance at the maximum absorption wavelength (λmax) in visible light (350 to 700 nm) was 1.0. An aqueous dye solution is prepared, and the absorbance X (XAbs) at the maximum absorption wavelength (λmax) of the dye solution measured using a cell having an optical path length of 5 μm is 0.8 or less 1) to 3 ) The ink stock solution according to any one of the above.
5) The ink stock solution according to any one of 1) to 4), further comprising a preservative.
6) The ink stock solution according to any one of 1) to 5), further comprising a pH adjuster.
7) The ink stock solution according to any one of 1) to 6), wherein the content of the additive A component in the ink stock solution is 0.1 to 20% by mass.
8) An ink-jet ink composition produced using the ink stock solution according to any one of 1) to 7).

  According to the present invention, the workability at the time of preparation of the ink stock solution, particularly the workability in the dye dissolution step and the concentration adjustment step, and even when used in a low temperature environment where the ink stock solution freezes, To provide an ink stock solution that suppresses the precipitation and separation of dye in the ink stock solution, improves the quality of the dye and the handleability during production, and avoids an increase in production cost, and an ink-jet ink composition using the same. it can.

In the ink stock solution of the present invention, the dye concentration is 7% by mass or more in terms of solid content. The dye concentration is preferably 7 to 30% by mass, particularly preferably 10 to 20% by mass.
The ink stock solution of the present invention contains at least water and a dye, and contains at least one selected from the following group (sometimes referred to as additive A).
a) monosaccharides, polysaccharides and derivatives thereof b) glycerin and alkylene glycol c) amino acids and amino acid derivatives d) urea and derivatives thereof e) compounds having a cyclic amide group It contains a regulator and the like.

The effects of these additives A include not only an excellent effect of re-dissolution after freezing even when used in an ink stock solution using a water-soluble dye, but also workability during preparation of the ink stock solution. It has been clarified by examination of the present inventors that it is excellent in the above.
Here, the workability during preparation of the ink stock solution will be further described.

Since the ink stock solution is a raw material for the ink composition, it is necessary to accurately adjust the absorption strength of the stock solution at the target wavelength. However, when the dye used in the ink stock solution has a high solubility in water, it is common for the dye to contain moisture in the air during storage. Due to the moisture contained in the dye, the absorption strength of the finished ink stock solution may not reach the target. For this reason, a two-stage concentration adjustment method is generally performed in which an ink stock solution having a higher absorption intensity than the target is prepared, a dilution rate is obtained from the absorption intensity of the liquid, and the target absorption intensity is adjusted by addition of water. .
Here, since the dye content in the ink stock solution is generally higher than the final ink composition that is usually used, in the process of dissolving the dye in water, heat is applied, vibration due to ultrasonic waves, etc. It is necessary to give If the dye is not sufficiently dissolved or the absorption strength of the ink stock solution is not uniform, the heating process and the ultrasonic process may take a long time. There arises a problem that the absorption intensity cannot be adjusted. Such a problem causes degradation of the dye and a significant decrease in workability, and becomes a serious problem in terms of quality and manufacturing cost.

  The reason why the workability at the time of preparation of the ink stock solution is improved by adding the additive A may be that the water solubility of the dye has increased due to the interaction between the dye and the additive, but the details are unknown. is there.

As the additive A of the present invention, the following may be preferably mentioned.
(1) Monosaccharides, polysaccharides and derivatives thereof. For example, glucose, sucrose, maltose, trehalose, sorbitol, mannitol, mannose, fructose, ribose, xylose, arabinose, galactose, aldonic acid, cellobiose, lactose, maltotriose, and reducing sugars and oxides of these sugars, dehydrated sugar Derivatives, amino sugars, thio sugars and the like. Among these, glucose, arabinose and galactose are preferable.
(2) Glycerin or alkylene glycols. Examples include glycerin, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,2-hexanediol, 1,6-hexanediol, 1,5-pentanediol, 1,4-butanediol, and the like. It is done. Of these, glycerin and ethylene glycol are preferred.
(3) Amino acids and their derivatives. For example, histidine, arginine, lysine, glycine, L-alanine, DL-alanine, L-isoleucine, L-valine, L-leucine, L-serine, L-threonine, L-cysteine, L-cystine, L-phenylalanine, Examples include L-proline, L-tyrosine, L-homoserine, L-methionine, L-methionine, DL-methionine, ε-aminocaproic acid, γ-aminobutyric acid, DL-threonine, aspartic acid, and glutamic acid. Among these, glycine, L-alanine, DL-alanine and arginine are preferable.
(4) Urea and its derivatives. Examples thereof include urea, thiourea, ethylene urea, N-methylurea, N, N-dimethylurea, N-ethylurea, N-hydroxyethylurea and the like. Of these, urea, thiourea, and ethylene urea are preferable.
(5) A compound having a cyclic amide group. Examples include 2-pyrrolidone, N-methyl-2-pyrrolidone, ε-caprolactam, γ-caprolactam, N-hydroxyethyl-2-pyrrolidone, N-ethyl-2-pyrrolidone and the like. Of these, 2-pyrrolidone and N-methyl-2-pyrrolidone are preferred.
In addition, you may use these additives A in mixture of 2 or more types as needed.

  The amount of additive A added to the ink stock solution is preferably 0.1 to 20% by mass, more preferably 1.0 to 15% by mass, and still more preferably 2.0 to 10% by mass.

  The ink stock solution of the present invention preferably has a surface tension at 25 ° C. of 50 mN / m or more, more preferably 55 mN / m or more.

The ink stock solution of the present invention contains dye, water and additive A as essential components, and may contain other various components (additive B) which will be described later. The concentration of the additive B is appropriately selected.
As the additive B, an antiseptic, a pH adjuster, and a rust inhibitor and a chelating agent as necessary are appropriately selected.

Ink stock solutions may cause problems with the formation of insoluble matter due to decay. In order to prevent this, it is preferable to add a preservative to the ink stock solution.
Various preservatives that can be used in the present invention can be used.
Examples of the preservative include inorganic preservatives (such as silver ion-containing substances) and salts containing heavy metal ions. Organic preservatives include quaternary ammonium salts (tetrabutylammonium chloride, cetylpyridinium chloride, benzyltrimethylammonium chloride, etc.), phenol derivatives (phenol, cresol, butylphenol, xylenol, bisphenol, etc.), phenoxyether derivatives (phenoxyethanol) Etc.), heterocyclic compounds (benzotriazole, PROXEL, 1,2-benzisothiazolin-3-one, etc.), acid amides, carbamic acid, carbamates, amidine / guanidine, pyridines (sodium pyridinethione- 1-oxide, etc.), diazines, triazines, pyrrole / imidazoles, oxazoles / oxazines, thiazoles / thiadiazines, thioureas, thiosemicarbazides Dithiocarbamates, sulfides, sulfoxides, sulfones, sulfamides, antibiotics (penicillin, tetracycline, etc.), sodium dehydroacetate, sodium benzoate, p-hydroxybenzoic acid ethyl ester, and salts thereof It can be used. In addition, as the antiseptic, those described in the antibacterial and microscopic handbook (Technical Hall: 1986), the antibacterial and antifungal encyclopedia (edited by the Japanese Society for Antibacterial and Antifungal Society), etc. can be used.
The preservatives may be added to the ink stock solution alone or in combination of two or more.
Various compounds such as those having an oil-soluble structure and a water-soluble structure can be used, but a water-soluble compound is preferable.
Among these, at least one preservative is preferably a heterocyclic compound.
In the present invention, when two or more kinds of preservatives are used in combination, the effects of the present invention are further improved. For example, the combination of a heterocyclic compound and an antibiotic, the combination of a heterocyclic compound and a phenol derivative, etc. are mentioned preferably. The content ratio in the case of combining two kinds of preservatives is not particularly limited, but a range of preservative A / preservative B = 0.01 to 100 (mass ratio) is preferable.
The amount of the preservative added to the ink stock solution can be used in a wide range, but is preferably 0.001 to 10% by mass, and more preferably 0.1 to 5% by mass.

The pH of the ink stock solution of the present invention is preferably 3.0 to 9.0, more preferably 5.5 to 9, and particularly preferably 6 to 9.
Examples of the pH adjuster include basic organic bases and inorganic bases, and acidic bases such as organic acids and inorganic acids.
Basic compounds include sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, lithium carbonate, sodium bicarbonate (sodium bicarbonate), potassium bicarbonate, lithium bicarbonate, sodium acetate, potassium acetate, Inorganic compounds such as sodium phosphate, sodium monohydrogen phosphate, aqueous ammonia, methylamine, ethylamine, diethylamine, triethylamine, ethanolamine, diethanolamine, triethanolamine, ethylenediamine, piperidine, diazabicyclooctane, diazabicycloundecene, It is also possible to use organic bases such as pyridine, quinoline, picoline, lutidine and collidine, and alkali metal salts of organic acids such as lithium benzoate and potassium phthalate.
Examples of acidic compounds include inorganic compounds such as hydrochloric acid, sulfuric acid, phosphoric acid, boric acid, sodium hydrogen sulfate, potassium hydrogen sulfate, potassium dihydrogen phosphate, sodium dihydrogen phosphate, acetic acid, tartaric acid, benzoic acid, trifluoroacetic acid. Organic compounds such as methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, saccharic acid, phthalic acid, picolinic acid and quinolinic acid can also be used.

  When preparing the ink stock solution, it is preferable to add a step (filtering step) for removing dust that is a solid content by filtration. A filtration filter is used for this operation, and a filter having an effective diameter of 1 μm or less, preferably 0.3 μm or less is used as the filtration filter at this time. Various materials can be used as the filter material, but in the case of an ink stock solution of a water-soluble dye, it is preferable to use a filter prepared for an aqueous solvent. Among them, it is particularly preferable to use a jacket type filter made of a polymer material that is difficult to generate dust. As a filtration method, the jacket may be passed by liquid feeding, and either pressure filtration or vacuum filtration can be used.

  Various methods such as dissolution by stirring, dissolution by ultrasonic irradiation, dissolution by shaking and the like can be used as a method for dissolving the dye and other components in the step of preparing the ink stock solution and the preparation step. Of these, the stirring method is particularly preferably used. In the case of stirring, various methods such as fluidized stirring known in the art and stirring using shearing force using an inverted agitator or dissolver can be used. On the other hand, a stirring method using a shearing force with the bottom surface of the container, such as a magnetic stirrer, can also be preferably used.

Next, the dye used for the ink stock solution of the present invention will be described. Although there is no restriction | limiting in particular as this dye, When the dye which satisfy | fills the conditions of following (1) or (2) is used, it is possible to acquire the effect of especially favorable invention.
(1) When the dye is diluted with water so that the absorbance at the maximum absorption wavelength (λmax) in visible light (350 to 700 nm) is 1.0, the dye is 25,000 or less (preferably 10,000). A molar extinction coefficient of ˜20,000, more preferably 10,000-18,000. When a dye having a low molar extinction coefficient is used in an inkjet ink, it is necessary to increase the dye concentration in order to obtain a desired concentration, and the dye concentration in the ink stock solution is also required to be high.
(2) Using a cell having an optical path length of 10 mm, the concentration of 2000 times that of the condition in which the dye was diluted with water so that the absorbance at the maximum absorption wavelength (λmax) in visible light (350 to 700 nm) was 1.0. An aqueous dye solution is prepared, and the absorbance X (XAbs) at the maximum absorption wavelength (λmax) of the dye solution measured using a cell having an optical path length of 5 μm is 0.8 or less (preferably 0.76 to 0.5, More preferably, it is 0.7-0.5). The lower the XAbs, the higher the association property.
In addition, when polyvalent metal ions and the like are contained in the water used for the dye solution, problems such as dye precipitation are likely to occur. Therefore, ultrapure water having a specific resistance value such as deionized water of 18 MΩ · cm or more is required. It is preferable to use it.

The effect of the present invention is particularly effective when a dye having a high associative property or a low molar extinction coefficient is used as the dye used in the present invention.
Examples of the dye having a low molar extinction coefficient include an anthraquinone dye and an anthrapyridone dye, and an anthrapyridone dye is particularly preferable when used for inkjet recording. Specific examples of the anthrapyridone dyes include compounds described in JP2003-192930A, JP2005-8868A, JP2005-41846A, and the like.

The dye having a high associative property is not particularly limited as long as the above-described X value is 0.8 or less, but the effect of the present invention is particularly great in the case of a dye used for black inkjet ink. This is because the dye concentration in the black ink is generally higher than that of the color ink, and the dye concentration in the ink stock solution is required to be higher than that of other colors. Examples of such a black dye having a high associative property include compounds described in JP-A-2004-83609 and Japanese Patent Application No. 2004-3799.
The black dye (L) preferably has a half-value width (Wλ, _1/2 ) in an absorption spectrum of a dilute solution having a λmax of 500 nm to 700 nm and an absorbance of 1.0, preferably 100 nm or more, more preferably 120 nm. It is not less than 500 nm and more preferably not less than 120 nm and not more than 350 nm.
With this black dye (L) alone, it is possible to realize “(good) black” with high image quality (= black that does not depend on the observation light source and in which one of B, G, and R is difficult to be emphasized). In this case, it is possible to use the black dye alone as a raw material for the ink composition, but it is usually used in combination with a dye that covers a region where the absorption of the black dye is low as the ink composition. It is common. As the dye used in combination, a dye (S) having a main absorption (λmax of 350 nm to 500 nm) in the yellow region is preferable. Furthermore, it is possible to prepare an ink composition by using other dyes in combination.
The dye (S) may be used in combination with the black dye (L) at the stage of the ink stock solution. However, it is preferably stored as a single ink stock solution or powder when the ink composition is prepared. It is preferable from the viewpoint of stability.

  In the case of producing an ink composition using the ink stock solution of the present invention, the following conditions are satisfied in order to satisfy 1) excellent weather resistance and / or 2) that the black balance is not lost even after fading. A satisfying black ink composition is preferred.

First, the black square symbol of JIS code 2223 is printed at 48 points using the black ink composition, and the reflection density (D _vis ) measured by the status A filter (visual filter) is defined as the initial density. An example of a reflection density measuring machine equipped with a status A filter is an X-Rite density measuring machine. Here, when measuring the density of “black”, the measured value by D _vis is used as the standard observation reflection density. From this time (t) until the reflection density (D _vis ) reaches 80% of the initial reflection density value, this print is forcibly faded using an ozone fading tester capable of always generating 5 ppm of ozone. The forced fading rate constant (k _vis ) is obtained from the relational expression “0.8 = exp (−k _vis · t)”.
In the present invention, the rate constant (k _vis ) is 5.0 × 10 ⁻² [hour ⁻¹ ] or less, preferably 3.0 × 10 ⁻² [hour ⁻¹ ] or less, and more preferably 1.0 × 10 ^{−. 2} [hour ^-1 ] An ink composition having the following ^value is prepared.

Also, a black square symbol of JIS code 2223 is printed at 48 points using the black ink composition, and this is a density measurement value measured by a status A filter, and is not D _vis but C (cyan), M (magenta), The reflection density (D _R , D _G , D _B ) of the three colors Y (yellow) is also defined as the initial density. Here, (D _R , D _G , D _B ) indicates (C reflection density by the red filter, M reflection density by the green filter, and Y reflection density by the blue filter). This print is forcibly faded using an ozone fading tester capable of always generating 5 ppm of ozone in accordance with the above method, and each reflection density (D _R , D _G , D _B ) is 80% of the initial density value. Similarly, the forced fading rate constants (k _R , k _G , k _B ) are determined from the time until. When the three rate constants are obtained and the ratio (R) between the maximum value and the minimum value is obtained (for example, when k _R is the maximum value and k _G is the minimum value, R = k _R / k _G ) The ink composition is prepared such that the ratio (R) is 1.2 or less, preferably 1.1 or less, more preferably 1.05 or less.

  Note that the “printed matter in which the black square symbol of the JIS code 2223 is printed at 48 points” used above gives an image large enough to cover the aperture of the measuring instrument in order to give a sufficient size for density measurement. It is printed.

Examples of the dye used in the ink stock solution of the present invention, and thus the ink composition, include a dye having an azo group bonded to a heterocyclic ring (hereinafter also referred to as “heterocyclic azo dye”) and an associative phthalocyanine dye (hereinafter referred to as a complex). The dyes used in the present invention such as cyclic azo dyes and the phthalocyanine dyes are also collectively referred to as dyes for the present invention). The present invention preferably contains at least one heterocyclic azo dye or the phthalocyanine dye, but other dyes and / or pigments may be used in combination.
The dye for use in the present invention preferably has an oxidation potential of 1.0 V (vs SCE) or more.
A person skilled in the art can easily measure the value of the oxidation potential (Eox). Regarding this method, for example Delahay, “New Instrumental Methods in Electrochemistry” (published by Interscience Publishers, 1954) J. et al. "Electrochemical Methods" by Bard et al. (Published by John Wiley & Sons in 1980) and "Electrochemical Measurement Method" by Akira Fujishima et al. (Published by Gihodo Publishing Co., Ltd. in 1984).

Specifically, the oxidation potential is 1 × 10 ⁻² to 1 × 10 ⁻⁶ mol / min in a solvent such as dimethylformamide or acetonitrile containing a supporting electrolyte such as sodium perchlorate or tetrapropylammonium perchlorate. It is measured as a value relative to SCE (saturated calomel electrode) using various voltammetry (polarography using a dropping mercury electrode, cyclic voltammetry, a method using a rotating disk electrode, etc.). Although this value may be deviated by several tens of mil volts due to the influence of the liquid potential difference or the liquid resistance of the sample solution, the reproducibility of the potential can be ensured by inserting a standard sample (for example, hydroquinone).
In the present invention, SCE (saturated calomel) is used as a reference electrode in N, N-dimethylformamide (concentration of dye is 0.001 mol / liter) containing 0.1 mol / liter of tetrapropylammonium perchlorate as a supporting electrolyte. Electrode), a value (vs SCE) measured using a graphite electrode as a working electrode and a platinum electrode as a counter electrode was defined as the oxidation potential of the dye.

  The value of Eox represents the ease of transfer of electrons from the sample to the electrode, and the greater the value (the higher the oxidation potential), the less transfer of electrons from the sample to the electrode, in other words, less oxidation. In relation to the structure of the compound, the oxidation potential becomes more noble by introducing an electron withdrawing group, and the oxidation potential becomes lower by introducing an electron donating group. In the present invention, in order to lower the reactivity with ozone as an electrophile, it is desirable to introduce an electron withdrawing group into the dye skeleton to make the oxidation potential more noble.

  As yellow dyes which are heterocyclic azo dyes, JP-A No. 2004-83903 (paragraph numbers [0048] to [0062]), 2003-277661 (paragraph numbers [0041] to [0050]), 2003-277661 are disclosed. Nos. (Paragraph numbers [0042] to [0047]) and US application publication US2003 / 0213405 (paragraph number [0108]). Specific examples of particularly preferred yellow dyes are shown below, but the heterocyclic azo dyes used in the present invention are not limited to the following examples, and the ionic hydrophilic group is optional regardless of the following examples. Examples of counter ions that form salts include ammonium ions, alkali metal ions (eg, lithium ions, sodium ions, potassium ions) and organic cations (eg, tetramethylammonium ions, tetra Methylguanidinium ion, tetramethylphosphonium ion). Among the counter ions, alkali metal salts are preferable.

  Examples of magenta dyes that are heterocyclic azo dyes include International Patent Publication Nos. 2002/83795 (pages 35 to 55), 2002-83862 (pages 27 to 42), and JP-A No. 2004-149560 (paragraph [0046] to [0059]), and 2004-149561 (paragraph numbers [0047] to [0060]). Specific examples of particularly preferred magenta dyes are shown below, but the heterocyclic azo dyes used in the present invention are not limited to the following examples, and the ionic hydrophilic group is optional regardless of the following examples. Examples of counter ions that form salts include ammonium ions, alkali metal ions (eg, lithium ions, sodium ions, potassium ions) and organic cations (eg, tetramethylammonium ions, tetra Methylguanidinium ion, tetramethylphosphonium ion). Among the counter ions, alkali metal salts are preferable.

  The content of the heterocyclic azo dye in the ink composition is preferably 0.2 to 15% by mass, and more preferably 0.5 to 10% by mass.

Next, as the phthalocyanine dye which is the dye for the present invention, an associative phthalocyanine dye is preferable. As the associative phthalocyanine dye, those having an associative group are preferable. The associative group means a group having at least a binding site (or functional group) capable of hydrogen bonding between molecules in the group. One or more binding sites can be contained in one group. Examples of the bonding site include a hydroxyl group, an amino group, an amide bond, an oxide bond, and the like, and a hydrogen bond is formed between the same species or different species. The associative group may be capable of hydrogen bonding between the phthalocyanine dye and any additive.
The phthalocyanine dye is preferably a cyan dye. The dye preferably has at least one of the above properties (oxidation potential and associability), and more preferably has all the properties.
In the present invention, in order to reduce the reactivity with ozone, which is an electrophile, for example, a carbon atom of a phthalocyanine skeleton is partially substituted with a hetero atom such as azaphthalocyanine, or an electron withdrawing group is replaced with a phthalocyanine skeleton. It is desirable that the oxidation potential be made nobler than 1.0 V (vs SCE). The oxidation potential is preferably as noble, more preferably noble than the oxidation potential of 1.1 V (vs SCE), and particularly preferably noble than 1.15 V (vs SCE).

  As an associative phthalocyanine dye, International Patent Publication Nos. 2002/60994, 2003/811, 2003/62324, JP2003-213167, 2004-75986, 2004-323605, 2004- 315758, 2004-315807, and Japanese Patent Application No. 2003-421124. Specific examples of particularly preferred cyan dyes are shown below, but the coloring matter used in the present invention is not limited to the following examples.

  The phthalocyanine dye used in the present invention can be synthesized according to Japanese Patent Application Laid-Open No. 2004-315729, Japanese Patent Application Nos. 2003-411390, and 2004-094413 in addition to the above-mentioned patents. Further, the starting material, dye intermediate and synthetic route are not limited by these.

  The phthalocyanine dye can be used alone, but can be used in combination with other dyes, particularly other phthalocyanine dyes.

The use of the ink stock solution of the present invention is not particularly limited, but it is preferably used for an ink jet ink composition. In order to prepare an ink-jet ink composition from an ink stock solution, a material necessary as an ink composition may be added to the ink stock solution, and a solvent may be added as necessary to adjust the concentration or the like.
The inkjet ink composition preferably contains the ink stock solution, has a viscosity of 1 to 30 mPa · s at 25 ° C., and a surface tension of 20 mN / m to 45 mN / m at 25 ° C. Moreover, the ink composition for inkjet preferably contains 0.2 to 20% by mass of all dyes, and more preferably contains 0.5 to 10% by mass.

  The ink composition obtained from each of the yellow, magenta, cyan, and black ink stock solutions of the present invention can be used not only for forming a single color image but also for forming a full color image. In order to form a full-color image, ink compositions of a plurality of colors having the same hue and different densities can be used for each color. Furthermore, ink compositions of intermediate colors such as red, green, blue, and violet can also be used. The ink composition of the present invention can constitute an ink set for obtaining a full-color image. Alternatively, the ink composition can form part of an ink set. In other words, any ink composition other than the present invention may be combined with the ink composition of the present invention to constitute an ink set.

The ink composition of the present invention is produced using the ink stock solution of the present invention, and other colorants are used in combination to adjust the color tone in obtaining a full-color image together with the dye. May be.
Any colorant can be used as the colorant that can be used in the ink composition and ink set of the present invention, or the colorant that can be used in combination with the dye. Examples of colorants that can be used in combination are the dyes described so far, the dyes described in JP-A-2004-331871, [0331] to [0334], and the dyes described in [0335] to [0341]. A pigment etc. can be mentioned.

In addition to the colorant represented by the above formula, dyes described in the following publications can also be preferably used.
JP-A-10-130557, JP-A-9-255906, JP-A-6-234944, JP-A-7-97541, EP 982371, WO 00/43450, WO 00/43451, WO 00/43452, WO 00 / 43453, WO 03/106572, WO 03/104332, JP 2003-238862, JP 2004-83609, JP 2002-302619, JP 2002-327131, JP 2002-265809, WO 01 / 48090, WO 04/087815, WO 02/90441, WO 03/027185, WO 04/085541, JP 2003-321627, JP 2002-332418, JP 2002-332419, WO 02/059215, WO 02 / 059216, WO 0 / 087814, WO 04/046252, WO 04/046265, US Pat. No. 6,652,637, WO 03/106572, WO 03/104332, WO 00/58407, Patent 3558213, Patent 3558212, Patent 3558211, Special No. 2004-285351, WO 04/078860, JP-A No. 2004-323605, WO 04/104108.

  Examples of water-soluble dyes used in the present invention include magenta dyes described in JP-A No. 2002-371214, phthalocyanine dyes described in JP-A No. 2002-309118, JP-A Nos. 2003-12952 and 2003-12956. It is also preferable to use the dyes described in water-soluble phthalocyanine dyes.

  The inkjet ink composition of the present invention contains a dye in a medium, preferably an aqueous medium. In the aqueous medium, water or a solvent such as a water-miscible organic solvent is added to water as necessary. In the water-miscible organic solvent, the same additive A as that of the present application may be included. In the present invention, it is important that an antifreezing agent is contained in an ink stock solution having a high dye concentration. When this is diluted to form an ink composition for ink jetting, the same water-miscible organic solvent as additive A is used. There is no problem even if it is further used, and it is used for exhibiting the following functions. The drying inhibitors and viscosity modifiers described below are the same as described above.

The water-miscible organic solvent that can be used in the ink composition of the present invention is a material having a function such as a drying inhibitor, a penetration enhancer, or a wetting agent, and a high-boiling water-miscible organic solvent is mainly used. Is done. Specific examples of such a compound are described in [0419] to [0423] of JP-A-2004-331871.
In the present invention, alcohol-based solvents are particularly preferable among the water-miscible organic solvents. The ink composition of the present invention preferably contains a water-miscible organic solvent having a boiling point of 150 ° C. or higher.
These water-miscible organic solvents are preferably contained in the ink composition in a total amount of 5 to 60% by mass, particularly preferably 10 to 45% by mass.

  For the purpose of improving the ejection stability, print quality, image durability, and the like of the ink composition of the present invention, surfactants, anti-drying agents, penetration enhancers, urea-based agents described in JP-A-2004-331871 and the like Additives, chelating agents, UV absorbers, antioxidants, viscosity modifiers, surface tension modifiers, dispersants, dispersion stabilizers, antiseptics, antifungal agents, rust inhibitors, pH adjusters, antifoaming agents, polymers Additives such as materials and acid precursors can be appropriately selected and used. The preferred use amounts of these additives are as described in JP-A-2004-331871.

  In addition, about the preparation method of the inkjet ink composition, Unexamined-Japanese-Patent No. 5-148436, 5-295212, 7-97541, 7-82515, 7-118584, Unexamined-Japanese-Patent No. 2004-331871. Details are described in each of the above publications, and can also be used to prepare the ink composition of the present invention.

  As the recording paper and the recording film which are printing media suitably used in the present invention, those described in JP-A-2004-331871 are preferably used.

  The ink composition of the present invention can also be used for purposes other than inkjet recording. For example, it can be used for display image materials, image forming materials for interior decoration materials, outdoor decoration materials, and the like described in JP-A-2004-318771 [0727] to [0731].

  In the production of an ink stock solution or an ink composition, as described in JP-A-2004-331871, ultrasonic vibration can be applied to the dissolution step of additives such as dyes.

  In preparing the ink stock solution or ink composition of the present invention, a step of removing dust that is a solid content by filtration, which is performed after further preparation of the liquid, is important. The filtration step is also as described in JP-A-2004-318771.

  The conditions described in [0628] to [0652] of JP-A No. 2004-331871 are preferable for the ink composition to be ejected onto the recording material in the present invention.

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

  The dyes used in this example are as follows.

<Calculation of moisture content of dye>
Example 1
AQUAMICRON AX (Mitsubishi Chemical Co., Ltd.) is placed in a cell of Karl Fischer moisture meter MKC-210 (manufactured by Kyoto Denshi Kogyo Co., Ltd.), and 5.0 mg of the dye A (black dye) is weighed with a precision balance. Was added and dissolved, and the moisture content was measured. As a result, the moisture content was 7.2%. When 30 mg of the dye of the same lot as the one for which the moisture content was measured was dissolved in 1000 ml of deionized water and the absorption spectrum was measured with visible light (350 nm to 700 nm), the maximum absorption wavelength (λmax) was 601 nm and the absorbance was 1.13. From this, the target concentration of an aqueous solution obtained by diluting the ink-jet ink stock solution containing 15% by mass of the above dye A in an actual solid content 5000 times was set to 1.22.
7.2 L of deionized water and 425 g of ethylene glycol were added to 1500 g of the dye A containing water, and the mixture was stirred for 1 hour while heating at 60 to 65 ° C. After the dye was completely dissolved, it was cooled to room temperature to prepare 8610 g of an ink stock solution (hereinafter referred to as pre-ink stock solution) A before density adjustment. The reason why the amount of the pre-ink stock solution is reduced with respect to the amount added is that moisture has evaporated during dissolution heating. The absorbance at λmax of an aqueous solution obtained by diluting 1.0 g of this pre-ink stock solution 5000 times was 1.31, and the substantial dye solid content was 16.1% by mass (calculated amount: 17. 4% by mass, equivalent to 7.6% moisture content of the dye). Precalculated amounts of deionized water (1054 g) and ethylene glycol (37 g) were added and stirred for 30 minutes so that the solid content of the dye was 15% by mass and the ethylene glycol content was 5% by mass. The concentration of stock solution A was adjusted. The total liquid volume after dilution was 9.24 kg. Further, 9.2 g of a preservative PROXEL XL2 (manufactured by Avecia) was added so that the content was 0.1% by mass. After stirring for 10 minutes, sodium bicarbonate was added to adjust the pH to 8.0. After stirring for 10 minutes, the mixture was filtered through a microfilter having an average pore size of 0.2 μm to prepare an ink-jet ink stock solution A. The ink stock solution A1.0 was diluted 5000 times and the absorbance at 601 nm was measured. As a result, it was 1.21 and showed a good agreement with the target value.
Furthermore, in the dye A, using a cell having an optical path length of 10 mm, the dye A was diluted with water so that the absorbance at the maximum absorption wavelength (λmax) in visible light (350 to 700 nm) was 1.0. The absorbance X (XAbs) at the maximum absorption wavelength (λmax) of this dye solution measured using a cell having an optical path length of 5 μm was 0.62.
The surface tension of the ink stock solution A was measured with SURFACE TENSIOMETER CBVP-A3 manufactured by Kyowa Interface Science Co., Ltd. and found to be 55 mN / m under 25 ° C. conditions.

(Examples 2 to 14)
Implemented except that the dyes A to F were used as water-soluble dyes having an XAbs of 0.8 or less, and the dye amount, deionized water amount, additive A, and additive amount (additive A) were changed as shown in Table 1. Ink stock solutions B to N were prepared in the same manner as in Example 1. When the surface tension at 25 ° C. of these ink stock solutions was measured by the same method as in Example 1, all were 50 mN / m or more.

(Examples 15 to 17)
As a water-soluble dye having a molar extinction coefficient ε of 25,000 or less, GH dyes were used, and the dye amount, deionized water amount, additive A, and additive amount (additive A) were changed as shown in Table 2. Were processed in the same manner as in Example 1 to prepare inkjet ink stock solutions O to Q.

(Comparative Examples 1-4)
By using dyes A, C, D, and G, changing the amount of dye and the amount of deionized water as shown in Table 3, and treating the same as in Example 1 except that additive A is not added, an ink jet ink stock solution R -U was produced.

<Evaluation of workability during ink stock preparation>
Evaluation of workability with respect to preparation workability of the ink stock solutions of Examples 1 to 17 and Comparative Examples 1 to 4 was calculated from the absorbance of the 5000-fold diluted solution of the pre-ink stock solution, and the concentration of the finished ink stock solution was adjusted by adding water or the like to 5000 Depending on the difference between the double dilution concentration (concentration A) and the target value (concentration B), it was carried out as follows.
○: Difference between concentration A and concentration B is within 0.04 Δ: 0.04 <difference between concentration A and concentration B ≦ 0.1
X: Difference between density A and density B is greater than 0.1

<Ink stock solution freezing test>
The instability to freezing and thawing of the ink stock solutions of Examples 1 to 17 and Comparative Examples 1 to 4 was tested by the following method.
(Freeze-thaw conditions)
As the freeze-thaw condition, 200 cc of the above ink stock solution was treated at −30 ° C. for 8 hours and then left at 23 ° C. and 60% for 8 hours.
(Test items)
Instability was evaluated by the following test.
(1) Concentration variation of ink stock solution After stirring the melted ink stock solution for 5 minutes, 1 g of the ink stock solution is collected, diluted 2000 times with deionized water, and the absorbance at λmax of the aqueous solution is measured. This operation was performed with n = 3, and the evaluation was performed according to the following rank based on a value A (max / min) obtained by dividing the maximum absorbance (Amax) by the minimum value Amin.
○: A (max / min) ≦ 1.05 Δ: 1.05 <A (max / min) ≦ 1.1 ×: 1.1 <A (max / min)
(2) Filtration residue of ink stock solution 100 cc of the melted ink stock solution was filtered using a cellulose acetate filter (Advantech's pore size 0.8 μm, filter size 47 mm) under reduced pressure, and then filtered with a small amount of deionized water. The colored portion is washed, and the residue is visually observed.
○: No residue Δ: A small amount of residue is present ×: A large amount of residue is present or filtration is not possible.
The evaluation results are shown in Table 4.

  From the above results, by adding the additive of the present invention to the ink stock solution, it is excellent in workability at the time of preparation, and the concentration variation of the ink stock solution after freezing and thawing and the residue after filtration are improved. Ink stock solution can be obtained.

Claims (8)

An ink stock solution containing at least water and a water-soluble dye and having a dye concentration of 7% by mass or more in solid content contains at least one selected from the following additive A group. Ink stock solution.
a) monosaccharides, polysaccharides and their derivatives b) glycerin and alkylene glycol c) amino acids and amino acid derivatives d) urea and its derivatives e) compounds having a cyclic amide group   The ink stock solution according to claim 1, wherein the surface tension at 25 ° C is 50 mN / m or more.   Using a cell having an optical path length of 10 mm, the molar extinction coefficient is 25,000 when the dye is diluted with water so that the absorbance at the maximum absorption wavelength (λmax) in visible light (350 to 700 nm) is 1.0. The ink stock solution according to claim 1 or 2, wherein:   Using a cell having an optical path length of 10 mm, an aqueous dye solution having a concentration of 2000 times the condition in which the dye is diluted with water so that the absorbance at the maximum absorption wavelength (λmax) in visible light (350 to 700 nm) is 1.0. The absorbance X (XAbs) at the maximum absorption wavelength (λmax) of the dye solution measured using a cell having an optical path length of 5 μm is 0.8 or less. 2. An ink stock solution according to item 1.   The ink stock solution according to any one of claims 1 to 4, further comprising a preservative.   The ink stock solution according to any one of claims 1 to 5, further comprising a pH adjusting agent.   The ink stock solution according to any one of claims 1 to 6, wherein the content of the additive A component in the ink stock solution is 0.1 to 20% by mass.   An ink-jet ink composition produced using the ink stock solution according to any one of claims 1 to 7.