JP2010100670A - Ink for inkjet, method for inkjet-recording, ink cartridge, recording unit, and inkjet recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink for inkjet providing a recording medium applicable to inkjet such as a plain-paper and a gloss paper with an image excellent in color tone, color developing property, light resistance and gas resistance. <P>SOLUTION: This ink for inkjet is an ink for inkjet comprising at least such two coloring materials as a first coloring material and a second coloring material in which the first coloring material is a metal chelate compound represented by Formula (I) or salts thereof and/or a compound represented by General Formula (II), and the second coloring material is a compound represented by General Formula (III). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an inkjet ink, an inkjet recording method, an ink cartridge, a recording unit, and an inkjet recording apparatus.

  The ink jet recording method is a recording method in which ink droplets are applied to a recording medium such as a so-called plain paper or glossy paper such as a special medium having a coating layer or an ink receiving layer on the surface to form an image. Due to its low price and improved recording speed, it is spreading rapidly. Moreover, in addition to the progress of high image quality of images obtained by the ink jet recording method, with the rapid spread of digital cameras, it has become widely used as an image output method comparable to silver salt photography.

  In recent years, in the ink jet recording method, image quality has been improved more than ever by minimizing ink droplets and improving the color gamut accompanying the introduction of multicolor ink. On the other hand, however, demands for color materials and inks are increasing, and more stringent characteristics are required in terms of reliability such as improved color development, clogging, and ejection stability.

  On the other hand, the problem of the ink jet recording method is that the obtained recorded matter is inferior in image storability. In general, the recorded matter obtained by the ink jet recording method has lower image storage stability than silver salt photographs. Specifically, when the recorded material is exposed to light, humidity, heat, or environmental gases that exist in the air for a long time, the color material on the recorded material deteriorates, causing a change in color tone or fading of the image. There is a problem that it is easy to do.

  Among these, from the viewpoint of fastness of an image formed using a dye ink containing a dye as a color material, particularly light resistance, low light resistance due to a chemical reaction peculiar to the color material is a problem. On the other hand, many proposals have heretofore been made in order to solve such a light resistance problem and to improve the light resistance of an image. Many proposals have been made regarding dyes used for magenta inks having low image storage stability among cyan, magenta, and yellow inks.

  For example, there are proposals relating to xanthene dyes and azo dyes using H acid as a colorant capable of forming an image with excellent image storage stability and color tone such as water resistance (see Patent Documents 1 and 2). . In addition, as a magenta dye excellent in color tone and light resistance, there is a proposal regarding an anthrapyridone dye (see Patent Document 3). Furthermore, there are proposals regarding a magenta ink that contains an anthrapyridone dye and an azo dye, and that can form an image with good color tone and good ozone resistance and light resistance (Patent Documents 4 and 5). reference). There is also a proposal for a magenta ink that contains a metal-containing azo dye and that has high ozone resistance and light resistance and enables formation of an image having good color developability (Patent Document 6).

JP-A-8-73791 JP-A-9-255882 JP 2005-008868 A JP-A-2005-105136 JP 2005-307068 A JP 2005-533900 A

  However, the methods described in Patent Documents 1 and 2 have the following problems. First, xanthene dyes are excellent in color tone, but are very inferior in light resistance. On the other hand, some azo dyes using H acid have good color tone, but are inferior in light resistance and gas resistance. In addition, for these types of dyes, the development of magenta dyes with excellent color tone and light fastness has been widely carried out, but other hues such as cyan dyes typified by copper phthalocyanine dyes and yellow dyes are used. The light resistance is still inferior to that of the dye having it.

In addition, in the method described in Patent Document 3, a magenta dye that satisfies the sharpness, gas resistance, and light resistance comparable to dyes having other hues has not been obtained.
In Patent Documents 4 and 5, an anthrapyridone dye having a high gas resistance and a low light resistance and an azo dye having a low gas resistance and a high light resistance are used in combination to supplement each other's characteristics. It is described that a magenta ink having both high gas resistance and light resistance can be obtained. Then, when such an ink having both an anthrapyridone dye and an azo dye is used, the colorant is resistant to an image in comparison with each ink containing only an anthrapyridone dye or only an azo dye. Gas and light resistance are improved to some extent. However, even when such an ink having both an anthrapyridone dye and an azo dye is used, the formation of an image that has reached a high level of fastness required in recent years has not been achieved. Furthermore, when the recording medium is a so-called plain paper that does not have an ink receiving layer, there is a problem that an image having sufficient color developability as a magenta image has not been obtained. Further, the magenta ink described in Patent Document 6 is not sufficient to satisfy the high level of image fastness demanded in recent years.

  Accordingly, an object of the present invention is to provide an ink jet ink that gives an image excellent in color tone, color developability, light resistance, and gas resistance to a recording medium applicable to ink jet such as plain paper and glossy paper. There is to do. Another object of the present invention is to provide an ink jet recording method, an ink cartridge, a recording unit, and an ink jet recording apparatus capable of forming a magenta image having excellent color developability, light resistance and gas resistance. .

（一般式（II）中、Ｍはそれぞれ独立に、水素原子、アルカリ金属、アンモニウム、又は有機アンモニウムである。）

（一般式（III）中、Ｒ₂、Ｒ₃、Ｒ₄、及びＲ₅はそれぞれ独立に、アルキル基であり、Ｍはそれぞれ独立に、水素原子、アルカリ金属、アンモニウム、又は有機アンモニウムである。） The above object is achieved by the present invention described below. That is, the ink-jet ink according to the present invention is an ink-jet ink containing at least two colorants of a first colorant and a second colorant, and the first colorant is represented by the following formula: A metal chelate compound represented by (I) or a salt thereof and / or a compound represented by the following general formula (II), wherein the second colorant is represented by the following general formula (III) It is a compound.

(In the general formula (II), each M is independently a hydrogen atom, an alkali metal, ammonium, or organic ammonium.)

(In General Formula (III), R ₂ , R ₃ , R ₄ , and R ₅ are each independently an alkyl group, and M is each independently a hydrogen atom, an alkali metal, ammonium, or organic ammonium. )

  An ink jet recording method according to another embodiment of the present invention is an ink jet recording method in which ink is ejected by an ink jet method to perform recording on a recording medium, wherein the ink is the ink jet ink of the present invention. Features.

  An ink cartridge according to another embodiment of the present invention is an ink cartridge including an ink container that stores ink, wherein the ink is the ink-jet ink of the present invention.

  According to another embodiment of the present invention, there is provided a recording unit comprising an ink storage portion for storing ink and a recording head for ejecting ink, wherein the ink is used for the inkjet according to the present invention. It is characterized by being ink.

  An ink jet recording apparatus according to another embodiment of the present invention is an ink jet recording apparatus including an ink storage portion for storing ink and a recording head for ejecting ink. It is an inkjet ink.

  According to the present invention, there is provided an ink jet ink that gives an image excellent in color tone, color developability, light resistance, and gas resistance to a recording medium applicable to ink jet such as plain paper and glossy paper. Can do. According to another embodiment of the present invention, there are provided an ink jet recording method, an ink cartridge, a recording unit, and an ink jet recording apparatus capable of forming a magenta image excellent in color development, light resistance and gas resistance. be able to.

  Hereinafter, the present invention will be described in detail with reference to preferred embodiments. In the present invention, when the compound is a salt, the salt is dissociated into ions in the ink, but is expressed as “contains a salt” for convenience. Hereinafter, the metal chelate compound represented by the formula (I) or a salt thereof may be abbreviated as “compound of the formula (I)”. In addition, the compound represented by general formula (II) and the compound represented by general formula (III) are abbreviated as “compound of general formula (II)” and “compound of general formula (III)”, respectively. May be described.

<Ink>
The components constituting the ink jet ink according to the present invention (hereinafter sometimes simply referred to as “ink”) will be described in detail below.

  As a result of the study by the present inventors, it is possible to improve the light resistance and gas resistance of the image at a high level by using a structure containing both a metal-containing dye having a specific structure and an azo dye. At the same time, it has been found that the compatibility of preferable color tones as magenta ink can be achieved. Furthermore, it has been found that by using the ink having such a configuration, it is possible to form an image having sufficient color developability as a magenta image even on plain paper.

  That is, the ink of the present invention is characterized by a metal-containing dye, a compound of the formula (I) described below and / or a compound of the following general formula (II) (first colorant), and an azo dye. , And a compound of the following general formula (III) (second coloring material) described later.

[First color material]
The ink of the present invention is a metal chelate compound represented by the following formula (I) or a salt thereof and / or the following general formula (II) having the characteristics of excellent color tone and light resistance as the first color material. It is necessary to contain this compound.

[Compound of Formula (I)]

  When the first coloring material is a salt of the metal chelate compound represented by the above formula (I), examples of the cation for forming the salt include alkali metal ions, ammonium ions, and organic ammonium ions. . Examples of the alkali metal include lithium, sodium, and potassium. Examples of the organic ammonium include acetamide, benzamide, methylamino, butylamino, diethylamino, and phenylamino.

  The first colorant used in the present invention can be in the form of a metal chelate compound represented by the above formula (I) or a salt of the metal chelate compound, and further, these tautomers, particularly triazole rings. Also includes tautomers.

  The metal chelate compound represented by the above formula (I) can be converted into a salt using a known technique. For example, an alkali metal salt of a compound can be converted to a salt with ammonia or an amine by dissolving the alkali metal salt of the dye in water and passing the solution through a column of an appropriately modified ion exchange resin.

（一般式（II）中、Ｍはそれぞれ独立に、水素原子、アルカリ金属、アンモニウム、又は有機アンモニウムである。） [Compound represented by formula (II)]

(In the general formula (II), each M is independently a hydrogen atom, an alkali metal, ammonium, or organic ammonium.)

  M in the general formula (II) is each independently a hydrogen atom, an alkali metal, ammonium, or organic ammonium. Examples of the alkali metal include lithium, sodium, and potassium. Examples of the organic ammonium include acetamide, benzamide, methylamino, butylamino, diethylamino, and phenylamino.

  Compounds of general formula (II) can be converted to salts using known techniques. For example, an alkali metal salt of a compound can be converted to a salt with ammonia or an amine by dissolving the alkali metal salt of the dye in water and passing the solution through a column of an appropriately modified ion exchange resin.

[Second coloring material: compound represented by formula (III)]
The ink of the present invention contains a compound represented by the following general formula (III), which is characterized by being particularly excellent in color tone, as the second color material.

（一般式（III）中、Ｒ₂、Ｒ₃、Ｒ₄、及びＲ₅はそれぞれ独立に、アルキル基であり、Ｍはそれぞれ独立に、水素原子、アルカリ金属、アンモニウム、又は有機アンモニウムである。）

(In General Formula (III), R ₂ , R ₃ , R ₄ , and R ₅ are each independently an alkyl group, and M is each independently a hydrogen atom, an alkali metal, ammonium, or organic ammonium. )

R ₂ , R ₃ , R ₄ and R ₅ in the general formula (III) are each independently an alkyl group. The alkyl group preferably has 1 to 3 carbon atoms from the viewpoint of solubility in an aqueous medium constituting the ink. Specifically, the alkyl group includes a methyl group, an ethyl group, a primary propyl group, and a second group. A secondary propyl group may be mentioned. In addition, when the carbon number of the alkyl group is 4 or more, the hydrophobicity of the coloring material increases, and the coloring material may not dissolve in the aqueous medium constituting the ink, which is not preferable.

  M in the general formula (III) is each independently a hydrogen atom, an alkali metal, ammonium, or organic ammonium. Examples of the alkali metal include lithium, sodium, and potassium. Examples of the organic ammonium include acetamide, benzamide, methylamino, butylamino, diethylamino, triethylamino, and phenylamino.

  Preferred specific examples of the compound of the general formula (III) include the following exemplified compounds 3 to 5. The following exemplary compounds are described in the form of free acid. Of course, the present invention is not limited to the following exemplary compounds as long as they are included in the structure of the general formula (III) and the definition thereof. In the present invention, it is particularly preferable to use the exemplified compound 4 among the following exemplified compounds.

  The azo dye used in the present invention is not necessarily a compound having any structure as long as it is a monoazo dye. For example, in an ink containing a combination of the compound of the formula (I) and / or the compound of the general formula (II) which is a metal-containing dye as described above and the compound of the following general formula (IV) which is a monoazo dye: An image having excellent light resistance cannot be obtained.

（一般式（IV）中、Ｒ₁、Ｒ₂、及びＲ₃はそれぞれ独立に、炭素数１乃至９の置換若しくは非置換のアルキル基、炭素数１乃至９のアルコキシ基、ハロゲン原子、水素原子、ヒドロキシル基。置換若しくは非置換のカルバモイル基、置換若しくは非置換のスルファモイル基、置換若しくは非置換のアミノ基。ニトロ基、スルホン酸エステル基、炭素数１乃至９のアルキルスルホニル基、炭素数６乃至１５のアリールスルホニル基、カルボキシル基、又はカルボン酸エステル基である。ｉは０、１、又は２である。Ｒ₄、Ｒ₅、及びＲ₆はそれぞれ独立に、水素原子、炭素数１乃至１８のアルキル基、炭素数２乃至１８の、アルケニル基、アリール基、アラルキル基、アリサイクリック基、又はヘテロサイクリック基である。これらのうち水素原子以外は置換基を有してもよい。）

(In the general formula (IV), R ₁ , R ₂ and R ₃ are each independently a substituted or unsubstituted alkyl group having 1 to 9 carbon atoms, an alkoxy group having 1 to 9 carbon atoms, a halogen atom, or a hydrogen atom. , Hydroxyl group, substituted or unsubstituted carbamoyl group, substituted or unsubstituted sulfamoyl group, substituted or unsubstituted amino group, nitro group, sulfonate group, alkylsulfonyl group having 1 to 9 carbon atoms, 6 to 6 carbon atoms 15 is an arylsulfonyl group, a carboxyl group, or a carboxylic acid ester group, i is 0, 1, or 2. R ₄ , R ₅ , and R ₆ are each independently a hydrogen atom or a carbon number of 1 to 18; An alkyl group having 2 to 18 carbon atoms, an alkenyl group, an aryl group, an aralkyl group, an alicyclic group, or a heterocyclic group. Except child may have a substituent.)

[Content of coloring material]
The aforementioned compounds of formula (I) and general formula (II) have a bluish magenta color tone. When an image is formed on a recording medium that can be used for ink jet, such as plain paper or glossy paper, an image with a high optical density can be obtained, but the image has sufficient ozone resistance. It has the characteristic of not. On the other hand, the compound of the general formula (III) described above has a yellowish magenta color tone. When an image is formed on a recording medium that can be applied to ink jet such as glossy paper as an ink, an image having a high optical density can be obtained, but an image formed on plain paper has a sufficient optical density. It has a characteristic that an image cannot be obtained. The ink of the present invention is obtained by combining the compound of the formula (I) and / or the compound of the general formula (II) and the compound of the general formula (III) having such characteristics. By using the ink having such a configuration, it is possible to form a magenta image with high color development on not only a recording medium applicable to inkjet such as glossy paper but also plain paper. In addition, it is possible to improve the high level of ozone resistance and light resistance that have been demanded in recent years for images formed on recording media that can also be used for inkjet such as glossy paper.

  In order to more suitably obtain the effects of the present invention as described above, the content (mass%) of the first color material in the ink is changed to the content (mass%) of the second color material in the ink. On the other hand, the mass ratio is preferably 0.1 or more and 5.0 or less. That is, (first color material / second color material) = 0.1 or more and 5.0 or less, specifically, {(compound of formula (I) and / or compound of general formula (II) Amount) / (content of compound of general formula (III))} = 0.1 to 5.0. In the ink of the present invention, by setting the mass ratio of the contents of the first color material and the second color material in the above range, the following two synergistic effects exceeding expectations can be obtained. First, the first synergistic effect is an improvement in the ozone resistance of the ink image that exceeds the expectation. That is, the ozone resistance of the image formed with the ink of the present invention is predicted from the ozone resistance of the image obtained by the ink containing each of the first color material and the second color material alone. When combined, the image will be far above the level of ozone resistance. Next, the second synergistic effect is to improve the color tone of the ink image. That is, in particular, by using an ink in which the mass ratio of the content of the first color material and the second color material is in the above range, a magenta image having a more preferable color tone (color development) can be obtained even on plain paper. Can do.

  Furthermore, the ink of the present invention is particularly preferable when the content of each color material satisfies the following configuration. First, the content (% by mass) of the first color material in the ink is preferably in the range of 0.1% by mass or more and 10.0% by mass or less based on the total mass of the ink. Further, the content (% by mass) of the second coloring material in the ink is preferably in the range of 0.1% by mass or more and 10.0% by mass or less based on the total mass of the ink.

  Furthermore, in the present invention, the total (mass%) of the content of the first color material and the content of the second color material in the ink is 4.0 mass% or more and 10 mass% or more based on the total mass of the ink. It is preferably within a range of 0.0 mass% or less. On the other hand, if the total content (% by mass) of the coloring material in the ink is less than 4.0% by mass, the image density of the recorded matter may not be obtained sufficiently, which is not preferable. On the other hand, if the total content (% by mass) of the color materials in the ink exceeds 10.0% by mass, it may not be possible to obtain inkjet characteristics such as anti-sticking property, which is not preferable.

[Color material verification method]
To verify whether or not the color material used in the present invention is contained in the ink, the following verification methods (1) to (3) using high performance liquid chromatography (HPLC) can be applied.
(1) Peak retention time (2) Maximum absorption wavelength for peak at (1) (3) M / Z (posi), M / Z (nega) of mass spectrum for peak at (1)

The analysis conditions of high performance liquid chromatography are as follows. A liquid (ink) diluted about 1,000 times with pure water is used as a measurement sample. Then, an analysis by high performance liquid chromatography is performed under the following conditions, and a peak retention time and a peak maximum absorption wavelength are measured.
Column: SunFire C ₁₈ (Nippon Waters) 2.1 mm x 150 mm
-Column temperature: 40 ° C
・ Flow rate: 0.2 mL / min
PDA: 200 nm to 700 nm
-Mobile phase and gradient conditions: Table 1 below

The analysis conditions of the mass spectrum are as shown below. About the obtained peak, a mass spectrum is measured on condition of the following, M / Z detected most strongly is measured with respect to each of posi and negative.
・ Ionization method ・ ESI
Capillary voltage: 3.5 kV
Desolvent gas: 300 ° C
Ion source temperature: 120 ° C
Detector posi: 40V 200-1500amu / 0.9sec
nega: 40V 200-1500amu / 0.9sec

  Under the method and conditions described above, as representative examples of the respective color materials, compounds of the formula (I) (metal chelate compounds), which are specific examples of the first color material, and specific examples of the second color material Each measurement was performed on Compound 4. As a result, the obtained retention time, maximum absorption wavelength, M / Z (posi), and M / Z (negative) values are shown in Table 2 below. When the unknown ink is measured under the same method and conditions as described above, and the obtained measured value corresponds to the value shown in Table 2, the compound of formula (I) (metal chelate compound) or exemplified compound 4 It can be judged that it corresponds to. Note that it is possible to verify whether or not other specific compounds of the first color material or the second color material are contained in the ink by measuring under the same method and conditions. Moreover, the 1st color material and 2nd color material which are used for this invention can respectively be synthesize | combined by a well-known method, and may use a commercial item.

(Aqueous medium)
In the ink of the present invention, water or an aqueous medium that is a mixed solvent of water and a water-soluble organic solvent can be used. It is preferable to use deionized water (ion exchange water) as the water. The water content (% by mass) in the ink is preferably 10.0% by mass or more and 90.0% by mass or less based on the total mass of the ink.

  The water-soluble organic solvent is not particularly limited as long as it is water-soluble, and alcohol, polyhydric alcohol, polyglycol, glycol ether, nitrogen-containing polar solvent, sulfur-containing polar solvent and the like can be used. The content (% by mass) of the water-soluble organic solvent in the ink is 5.0% by mass or more and 90.0% by mass or less, more preferably 10.0% by mass or more and 50.0% by mass or less based on the total mass of the ink. It is preferable that If the content of the water-soluble organic solvent is less than the above range, reliability such as ejection stability may not be obtained when the ink is used in an ink jet recording apparatus. Further, when the content of the water-soluble organic solvent is larger than the above range, the viscosity of the ink increases, and ink supply failure may occur.

  Specifically, for example, the following water-soluble organic solvents can be used. 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; Amides such as dimethylformamide and 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. Glycols such as ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, triethylene glycol, hexylene glycol, and thiodiglycol. Alkylene groups such as 1,5-pentanediol, 1,6-hexanediol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 1,2,6-hexanetriol Alkylene glycols having 2 to 6 carbon atoms. Bis (2-hydroxyethyl) sulfone. Lower alkyl ether acetates such as polyethylene glycol monomethyl ether acetate. Alkyl ethers of polyhydric alcohols such as ethylene glycol monomethyl (or ethyl) ether, diethylene glycol methyl (or ethyl) ether, triethylene glycol monomethyl (or ethyl) ether. N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone and the like. Of course, the present invention is not limited to these. These water-soluble organic solvents can be used alone or in combination of two or more as required.

(Other additives)
In addition to the components described above, the ink of the present invention is a water-soluble organic substance that is solid at room temperature, such as polyhydric alcohols such as trimethylolpropane and trimethylolethane, and urea derivatives such as urea and ethyleneurea, if necessary. A compound may be contained. Further, the ink of the present invention is optionally provided with a surfactant, a pH adjuster, a rust inhibitor, an antiseptic, an antifungal agent, an antioxidant, a reduction inhibitor, an evaporation accelerator, a chelating agent, and a water-soluble agent. Various additives such as polymers may be contained.

<Other inks>
Further, in order to form a full-color image or the like, the ink of the present invention can be used in combination with an ink having a color tone different from that of the ink of the present invention. The ink of the present invention is preferably used together with at least one kind of ink such as black ink, cyan ink, magenta ink, yellow ink, red ink, green ink, and blue ink. Further, so-called light ink having substantially the same color tone as these inks can be used in combination. The color material of these inks or light inks may be a known dye or a newly synthesized color material.

<Recording medium>
The recording medium used for forming an image using the ink of the present invention can be applied to ink jet printing, and any recording medium can be used as long as recording can be performed by applying the ink. Can do. For example, a commonly used recording medium such as plain paper or a special medium having a coated layer or an ink receiving layer on its surface, such as a glossy paper, a coated paper, or a glossy film, can be used. In the present invention, it is preferable to use an inkjet recording medium in which a PPC plain paper used as a so-called copy paper or a coloring material such as a dye or a pigment is adsorbed to fine particles forming the porous structure of the ink receiving layer. In particular, it is preferable to use a recording medium having a so-called gap absorption type ink receiving layer that absorbs ink by a gap formed in the ink receiving layer on the support. The gap absorption type ink receiving layer is composed mainly of fine particles, and may further contain a binder and other additives as necessary.

  Specifically, the following fine particles can be used. Inorganic pigments such as aluminum oxide such as silica, clay, talc, calcium carbonate, kaolin, alumina or alumina hydrate, diatomaceous earth, titanium oxide, hydrotalcite, or zinc oxide. Organic pigments such as urea formalin resin, ethylene resin, styrene resin. These fine particles can be used alone or in combination of two or more as required.

  Examples of the binder include water-soluble polymers and latex. Specifically, the following can be used. Polyvinyl alcohol, starch, gelatin, or modified products thereof. Arabic gum. Cellulose derivatives such as carboxymethylcellulose, hydroxyethylcellulose, or hydroxyprooylmethylcellulose. Vinyl-based copolymer latex such as SBR latex, NBR latex, methyl methacrylate-butadiene copolymer latex, functional group-modified polymer latex, or ethylene vinyl acetate copolymer. Polyvinyl pyrrolidone. Maleic anhydride or a copolymer thereof, or an acrylate copolymer. These binders can use 1 type (s) or 2 or more types as needed.

  In addition, additives can be used as necessary. For example, dispersants, thickeners, pH adjusters, lubricants, fluidity modifiers, surfactants, antifoaming agents, mold release agents, optical brighteners, ultraviolet absorbers, antioxidants, dye fixing agents, etc. Can be used.

  In particular, in the present invention, it is preferable to use a recording medium in which an ink receiving layer is mainly formed of fine particles having an average particle diameter of 1 μm or less. Specific examples of the fine particles include silica fine particles and aluminum oxide fine particles. A preferable silica fine particle is a silica fine particle typified by colloidal silica. Although a colloidal silica can also use a commercial item, it is preferable to use especially the colloidal silica described in patent 2803134, 2881847, for example. Further, preferable examples of the aluminum oxide fine particles include alumina hydrate fine particles (alumina pigments).

Among the alumina pigments, an alumina hydrate such as pseudoboehmite represented by the following formula can be particularly preferable.
AlO _3-n (OH) _2n · mH ₂ O
(In the formula, n is an integer of 1 to 3, and m is 0 to 10, preferably 0 to 5. However, m and n are not 0 at the same time.)
mH ₂ O often also represents a detachable aqueous phase that is not involved in the formation of the mH ₂ O crystal lattice. For this reason, m can take an integer or a non-integer value. Also, when this type of alumina hydrate is heated, m can reach zero.

  Alumina hydrate can be produced by the following known methods. For example, it can be produced by hydrolysis of aluminum alkoxide or hydrolysis of sodium aluminate described in US Pat. No. 4,242,271 and US Pat. No. 4,202,870. Moreover, it can manufacture by the method of adding aqueous solution, such as sodium sulfate and aluminum chloride, to the aqueous solution of sodium aluminate etc. which are described in Japanese Patent Publication No.57-44605.

  The recording medium preferably has a support for supporting the ink receiving layer. The support is not particularly limited as long as the ink receiving layer can be formed of the above-described porous fine particles and gives rigidity that can be transported by a transport mechanism such as an ink jet recording apparatus. Can also be used. For example, a paper support composed of a pulp raw material mainly composed of natural cellulose fibers can be used. In addition, a plastic support made of a material such as polyester (for example, polyethylene terephthalate), cellulose triacetate, polycarbonate, polyvinyl chloride, polypropylene, or polyimide can be used. Furthermore, a resin-coated paper (eg, RC paper) having a polyolefin resin coating layer added with a white pigment or the like on at least one surface of the base paper can be used.

  In particular, in the present invention, the pH of the surface of the recording medium is preferably 3.0 or more and 8.0 or less. In order to sufficiently obtain the effects of the present invention, the pH of the surface of the recording medium is particularly preferably 4.0 or more and 6.0 or less.

<Inkjet recording method>
The ink of the present invention is particularly preferably used in an ink jet recording method for recording on a recording medium by ejecting the ink by an ink jet method. Ink jet recording methods include a recording method in which ink is ejected by applying mechanical energy to the ink, and a recording method in which ink is ejected by applying thermal energy to the ink. In particular, in the present invention, an ink jet recording method using thermal energy can be preferably used.

<Ink cartridge>
As an ink cartridge suitable for recording using the ink of the present invention, an ink cartridge provided with an ink containing portion for containing such ink can be mentioned.

<Recording unit>
A recording unit suitable for performing recording using the ink of the present invention includes a recording unit including an ink storage portion for storing the ink and a recording head for discharging the ink. In particular, a recording unit in which the recording head ejects ink by applying thermal energy corresponding to the recording signal to the ink can be preferably used. In particular, in the present invention, it is preferable to use a recording head having a heat generating part wetted surface containing a metal and / or a metal oxide. Specific examples of the metal and / or metal oxide constituting the heat generating part wetted surface include, for example, metals such as Ta, Zr, Ti, Ni, and Al, and oxides of these metals. .

<Inkjet recording apparatus>
An ink jet recording apparatus suitable for performing recording using the ink of the present invention includes an ink jet recording apparatus provided with an ink containing portion for containing the ink and a recording head for discharging the ink. In particular, there is an ink jet recording apparatus that ejects ink by applying thermal energy corresponding to a recording signal to ink inside a recording head having an ink storage portion that stores the ink.

  Below, the schematic structure of the mechanism part of an inkjet recording device is demonstrated. The ink jet recording apparatus is composed of a paper feed unit, a transport unit, a carriage unit, a paper discharge unit, a cleaning unit, and an exterior unit that protects these parts and provides design properties in accordance with the role of each mechanism.

  FIG. 1 is a perspective view of the ink jet recording apparatus. 2 and 3 are diagrams for explaining the internal mechanism of the ink jet recording apparatus. FIG. 2 is a perspective view from the upper right part, and FIG. 3 is a side sectional view of the ink jet recording apparatus.

  When paper is fed, only a predetermined number of recording media are fed to a nip portion composed of a paper feed roller M2080 and a separation roller M2041 in a paper feed unit including a paper feed tray M2060. The recording medium is separated at the nip portion, and only the uppermost recording medium is conveyed. The recording medium conveyed to the conveyance unit is guided by the pinch roller holder M3000 and the paper guide flapper M3030, and conveyed to the roller pair of the conveyance roller M3060 and the pinch roller M3070. The roller pair of the conveyance roller M3060 and the pinch roller M3070 is rotated by driving of the LF motor E0002, and the recording medium is conveyed on the platen M3040 by this rotation.

  When forming an image on a recording medium, the carriage unit arranges a recording head H1001 (FIG. 4; a detailed configuration will be described later) at a position where a target image is formed, and follows a signal from the electric board E0014. Ink is ejected onto the recording medium. An image is formed on the recording medium by alternately repeating main scanning in which the carriage M4000 scans in the column direction while performing recording by the recording head H1001 and sub-scanning in which the recording medium is conveyed in the row direction by the conveyance roller M3060. The recording medium on which the image is formed is conveyed in a state sandwiched between the nips of the first paper discharge roller M3110 and the spur M3120 at the paper discharge unit, and is discharged to the paper discharge tray M3160.

  The cleaning unit cleans the recording head H1001 before and after forming an image. When the pump M5000 is operated with the cap M5010 capping the ejection port of the recording head H1001, unnecessary ink or the like is sucked from the ejection port of the recording head H1001. In addition, by sucking ink remaining in the cap M5010 with the cap M5010 open, sticking due to the remaining ink and other problems do not occur.

(Configuration of recording head)
The configuration of the head cartridge H1000 will be described. The head cartridge H1000 has a recording head H1001, means for mounting the ink cartridge H1900, and means for supplying ink from the ink cartridge H1900 to the recording head, and is detachably mounted on the carriage M4000.

  FIG. 4 is a diagram showing how the ink cartridge H1900 is mounted on the head cartridge H1000. The ink jet recording apparatus forms an image with yellow, magenta, cyan, black, light magenta, light cyan, and green inks. Therefore, the ink cartridge H1900 is also prepared for seven colors independently. In the above, the ink of the present invention is used as at least one ink. As shown in FIG. 4, each ink cartridge is detachable from the head cartridge H1000. The ink cartridge H1900 can be attached and detached even when the head cartridge H1000 is mounted on the carriage M4000.

  FIG. 5 is an exploded perspective view of the head cartridge H1000. The head cartridge H1000 includes a recording element substrate, a plate, an electric wiring substrate H1300, a cartridge holder H1500, a flow path forming member H1600, a filter H1700, a seal rubber H1800, and the like. The recording element substrate is composed of a first recording element substrate H1100 and a second recording element substrate H1101, and the plate is composed of a first plate H1200 and a second plate H1400.

  The first recording element substrate H1100 and the second recording element substrate H1101 are Si substrates, and a plurality of recording elements (nozzles) for ejecting ink are formed on one side thereof by a photolithography technique. Electric wiring such as Al for supplying electric power to each recording element is formed by a film forming technique, and a plurality of ink flow paths corresponding to individual recording elements are formed by a photolithography technique. Further, an ink supply port for supplying ink to the plurality of ink flow paths is formed to open on the back surface.

  FIG. 6 is an enlarged front view illustrating the configuration of the first recording element substrate H1100 and the second recording element substrate H1101. H2000 to H2600 are arrays of printing elements corresponding to different ink colors (hereinafter also referred to as nozzle arrays). On the first recording element substrate H1100, nozzle rows for three colors, a nozzle row H2000 for yellow ink, a nozzle row H2100 for magenta ink, and a nozzle row H2200 for cyan ink, are formed. On the second recording element substrate H1101, nozzle rows for four colors, a light cyan ink nozzle row H2300, a black ink nozzle row H2400, a green ink nozzle row H2500, and a light magenta ink nozzle row H2600, are formed. ing.

Each nozzle row is composed of 768 nozzles arranged at an interval of 1200 dpi (dot / inch; reference value) in the conveyance direction (sub-scanning direction) of the recording medium, and ejects about 2 picoliters of ink. The opening area at each discharge port is set to about 100 μm ² .

  Hereinafter, a description will be given with reference to FIGS. The first recording element substrate H1100 and the second recording element substrate H1101 are bonded and fixed to the first plate H1200. Here, an ink supply port H1201 for supplying ink to the first recording element substrate H1100 and the second recording element substrate H1101 is formed. Further, a second plate H1400 having an opening is bonded and fixed to the first plate H1200. The second plate H1400 holds the electrical wiring substrate H1300 so that the electrical wiring substrate H1300 is electrically connected to the first recording element substrate H1100 and the second recording element substrate H1101.

  The electrical wiring substrate H1300 applies an electrical signal for ejecting ink from each nozzle formed on the first recording element substrate H1100 and the second recording element substrate H1101. The electric wiring board H1300 is arranged on the electric wiring corresponding to the first recording element substrate H1100 and the second recording element substrate H1101, and an external part for receiving an electric signal from the ink jet recording apparatus. And a signal input terminal H1301. The external signal input terminal H1301 is positioned and fixed on the back side of the cartridge holder H1500.

  A flow path forming member H1600 is fixed to the cartridge holder H1500 that holds the ink cartridge H1900, for example, by ultrasonic welding, and forms an ink flow path H1501 that communicates from the ink cartridge H1900 to the first plate H1200. A filter H1700 is provided at the ink cartridge side end of the ink flow path H1501 that engages with the ink cartridge H1900, and can prevent dust from entering from the outside. Further, a seal rubber H1800 is attached to the engaging portion with the ink cartridge H1900 so that the ink can be prevented from evaporating from the engaging portion.

  Furthermore, as described above, the head cartridge H1000 is configured by bonding the cartridge holder portion and the recording head portion H1001 by bonding or the like. The cartridge holder portion includes a cartridge holder H1500, a flow path forming member H1600, a filter H1700, and a seal rubber H1800. The recording head portion H1001 includes a first recording element substrate H1100, a second recording element substrate H1101, a first plate H1200, an electric wiring substrate H1300, and a second plate H1400.

  Here, as an embodiment of the recording head, a thermal ink jet recording head that performs recording using an electrothermal transducer (recording element) that generates thermal energy for causing ink to cause film boiling in accordance with an electrical signal. Said. About this typical structure and principle, for example, what is performed using the basic principle disclosed in US Pat. Nos. 4,723,129 and 4,740,796 is preferable. . This method can be applied to both a so-called on-demand type and a continuous type.

  The thermal ink jet method is particularly effective when applied to an on-demand type. In the case of the on-demand type, at least one drive that applies a rapid temperature rise exceeding nucleate boiling corresponding to the recording information to the electrothermal transducer disposed corresponding to the liquid flow path holding the ink Apply a signal. As a result, thermal energy is generated in the electrothermal transducer, and film boiling occurs in the ink. As a result, bubbles in the ink corresponding to the drive signal on a one-to-one basis can be formed. At least one droplet is formed by ejecting ink through the ejection port by the growth and contraction of the bubbles. It is more preferable that the driving signal has a pulse shape, since the bubble grows and contracts immediately and appropriately, so that ink discharge with particularly excellent response can be achieved.

  The ink of the present invention is not limited to the thermal ink jet method, and can be preferably used in an ink jet recording apparatus using mechanical energy as described below. An ink jet recording apparatus having such a configuration includes a nozzle forming substrate having a plurality of nozzles, a pressure generating element made of a piezoelectric material and a conductive material disposed to face the nozzles, and ink filling the periphery of the pressure generating element. Become. Then, the pressure generating element is displaced by the applied voltage, and ink is ejected from the nozzle.

  As described above, the ink jet recording apparatus is not limited to one in which the recording head and the ink cartridge are separated from each other. Further, the ink cartridge is integrated with the recording head in a separable or non-separable manner and mounted on the carriage, and is provided at a fixed portion of the ink jet recording apparatus via an ink supply member such as a tube. An ink may be supplied to the recording head. Further, when the ink cartridge is provided with a configuration for applying a preferable negative pressure to the recording head, the following configuration can be adopted. That is, a mode in which an absorber is disposed in the ink storage portion of the ink cartridge, or a mode in which a flexible ink storage bag and a spring portion that applies a biasing force in the direction of expanding the inner volume of the flexible ink storage bag are provided. It can be. In addition to the serial type recording method described above, the ink jet recording apparatus may also take the form of a line printer in which recording elements are aligned over a range corresponding to the entire width of the recording medium.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail using an Example and a comparative example, this invention is not limited at all by the following Example, unless the summary is exceeded. In the following description, “parts” and “%” are based on mass unless otherwise specified.

<Synthesis of coloring materials>
(Exemplary Compound 1)
Exemplified Compound 1 synthesized according to the method described in JP-T-2005-533900 was used as the first coloring material.

(Exemplary Compound 2)
Exemplary compound 2 represented by the following structural formula was used as the first coloring material.

(Exemplary Compound 3 and Exemplary Compound 4)
Exemplified Compound 3 and Exemplified Compound 4 respectively synthesized by the method described in JP-A-2006-143898 were used as the second color material.

<Preparation of ink>
Each component having the composition shown in Table 3 below was mixed and sufficiently stirred. Thereafter, pressure filtration was performed with a filter having a pore size of 0.2 μm to prepare inks of Examples and Comparative Examples.

<Production of glossy paper>
By applying a resin composition containing 70 parts of low density polyethylene, 20 parts of high density polyethylene, and 10 parts of titanium oxide to both sides of a base paper having a basis weight of 155 g / m ² , the resin composition is 25 g / m ^2. A support coated with was prepared. Then, an ink receiving layer mainly composed of alumina hydrate and polyvinyl alcohol was formed on the obtained support. In this way, a gap type ink receiving layer was provided, and the JAPAN TAPPI paper pulp test method no. A recording medium (glossy paper) having a surface pH of 5.0 after 3 minutes measured according to 49-1.

<Evaluation>
The inks of Examples and Comparative Examples obtained above were each mounted on an ink jet recording apparatus (trade name: PIXUS iP8600) using thermal energy. The recording conditions were a temperature of 23 ° C., a relative humidity of 55%, a recording density of 2400 dpi × 1200 dpi, and a discharge amount of 2.5 pL. Then, on the recording medium (glossy paper) obtained above and the plain paper (product name: office planner; manufactured by Canon), each image with the recording duty changed from 0% to 100% in 10% increments, respectively. A formed recording was obtained. Further, the obtained recorded matter was naturally dried at a temperature of 23 ° C. and a relative humidity of 55% for 24 hours to obtain a recorded matter for evaluation. For each recorded matter obtained, the optical density measurement of each image formed on glossy paper and plain paper and the evaluation of the fastness (light resistance, ozone resistance) of the image formed on the glossy paper by the method described below. Went.

[Optical density]
The portion of the image having a recording duty of 100% in the recorded matter obtained above was evaluated by measuring the optical density using a spectrophotometer (trade name: Spectrolino; manufactured by Gretag Macbeth). The evaluation criteria of the optical density are as follows, and the evaluation results obtained are shown in Table 4. In the evaluation criteria for each of the following recording media, A and B are acceptable levels for the magenta optical density, and are in a range where it can be evaluated that the color tone is good. Since the evaluation criterion C is low as the optical density of magenta, the image looks thin, the color developability is inferior, and is an unacceptable level.

(Evaluation criteria for optical density on glossy paper)
A: Optical density is 2.0 or more B: Optical density is 1.5 or more and less than 2.0 C: Optical density is less than 1.5
(Evaluation criteria for optical density in plain paper)
A: Optical density is 1.30 or more B: Optical density is 1.25 or more and less than 1.30 C: Optical density is less than 1.25

[Robustness of image: Light resistance]
The portion in which the recording duty was 50% of the image of the recorded matter obtained by using the glossy paper in the above, L ^* in the L ^* a ^* b ^* display system defined by the CIE (Commission Internationale de l'Eclairage), a ^*, and b ^* was measured (referred to as “Lab value before light resistance test”). Further, this recorded material was 168 hours at an irradiation intensity of 100 kilolux, a relative humidity of 60%, an internal temperature of 24 ° C. and a relative humidity of 60% using a Super Xenon Tester (trade name: SX-75; manufactured by Suga Test Instruments). Exposed. After completion of the light resistance test, L ^* , a ^* , and b ^* were measured for an image portion having a recording duty of 50% in the recorded matter (referred to as “Lab value after light resistance test”). L ^* , a ^* , and b ^* were measured using a spectrophotometer (Spectorolino; manufactured by Gretag Macbeth) under the conditions of a light source: D50 and a visual field: 2 °. From the obtained Lab value before the light resistance test and the Lab value after the light resistance test, the color difference (ΔE) was calculated based on the following formula (B) to evaluate the light resistance. The evaluation criteria of light resistance are as follows, and the evaluation results obtained thereby are shown in Table 4. In the following evaluation criteria, A and B are acceptable levels, and C is an unacceptable level because the degree of image fading after the light resistance test is large.

(Evaluation criteria for light resistance)
A: ΔE is less than 17 B: ΔE is 17 or more and less than 20 C: ΔE is 20 or more

[Image robustness: ozone resistance]
The portion in which the recording duty was 50% of the image in the recorded product obtained by using a glossy paper above, L ^* in the L ^* a ^* b ^* display system defined by the CIE (Commission Internationale de l'Eclairage), a ^*, and b ^* was measured (“Lab value before ozone resistance test”). Furthermore, this recorded matter was exposed for 4 hours at an ozone gas concentration of 10 ppm, a relative humidity of 60%, and an internal temperature of 24 ° C. using an ozone test apparatus (trade name: OMS-H; manufactured by Suga Test Instruments). After completion of the ozone resistance test, L ^* , a ^* , and b ^* were measured for the portion of the image with a recording duty of 50% in the recorded matter (referred to as “Lab value after the ozone resistance test”). L ^* , a ^* , and b ^* were measured using a spectrophotometer (Spectorolino; manufactured by Gretag Macbeth) under the conditions of a light source: D50 and a visual field: 2 °. From the obtained Lab value before the ozone resistance test and the Lab value after the ozone resistance test, the color difference (ΔE) was calculated based on the following formula (C) to evaluate the ozone resistance. The evaluation criteria of ozone resistance are as follows, and the obtained evaluation results are shown in Table 4. In the following evaluation criteria, A and B are acceptable levels, and C is an unacceptable level because the degree of image fading after the ozone resistance test is large.

(Evaluation criteria for ozone resistance)
A: ΔE is less than 5 B: ΔE is 5 or more and less than 10 C: ΔE is 10 or more

It is a perspective view of an inkjet recording device. It is a perspective view of the mechanism part of an inkjet recording device. It is sectional drawing of an inkjet recording device. FIG. 6 is a perspective view illustrating a state where an ink cartridge is mounted on the head cartridge. It is a disassembled perspective view of a head cartridge. FIG. 6 is a front view showing a recording element substrate in the head cartridge.

Explanation of symbols

M2041: separation roller M2060: paper feed tray M2080: paper feed roller M3000: pinch roller holder M3030: paper guide flapper M3040: platen M3060: transport roller M3070: pinch roller M3110: paper discharge roller M3120: spur M3160: paper discharge tray M4000: Carriage M5000: Pump M5010: Cap M7030: Access cover E0002: LF motor E0014: Electric substrate H1000: Head cartridge H1001: Recording head H1100: First recording element substrate H1101: Second recording element substrate H1200: First plate H1201 : Ink supply port H1300: Electric wiring board H1301: External signal input terminal H1400: Second plate H1500: Cartridge holder H150 : Ink flow path H1600: flow path forming member H1700: filter H1800: seal rubber H1900: ink cartridge H2000: yellow nozzle row H2100: magenta nozzle row H2200: cyan nozzle row H2300: light cyan nozzle row H2400: black nozzle row H2500: green nozzle Row H2600: Light magenta nozzle row

Claims (6)

An ink-jet ink containing at least two colorants, a first colorant and a second colorant,
The first colorant is a metal chelate compound represented by the following formula (I) or a salt thereof, and / or a compound represented by the following general formula (II),
An ink-jet ink, wherein the second color material is a compound represented by the following general formula (III).

(In the general formula (II), each M is independently a hydrogen atom, an alkali metal, ammonium, or organic ammonium.)

(In General Formula (III), R ₂ , R ₃ , R ₄ , and R ₅ are each independently an alkyl group, and M is each independently a hydrogen atom, an alkali metal, ammonium, or organic ammonium. )   The content (% by mass) of the first color material in the ink is 0.1 to 5.0 by mass ratio with respect to the content (% by mass) of the second color material in the ink. The inkjet ink according to claim 1.   3. An ink jet recording method in which ink is ejected by an ink jet method to perform recording on a recording medium, wherein the ink is the ink jet ink according to claim 1 or 2.   An ink cartridge comprising an ink containing portion for containing ink, wherein the ink is an ink jet ink according to claim 1 or 2.   3. A recording unit comprising an ink containing portion for containing ink and a recording head for ejecting ink, wherein the ink is the ink jet ink according to claim 1 or 2.   3. An ink jet recording apparatus comprising an ink containing portion for containing ink and a recording head for ejecting ink, wherein the ink is the ink jet ink according to claim 1 or 2. apparatus.

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