JP2007277566A - Ink composition, ink set and recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-based ink composition recording color having high visibility, brilliant color, separated different light colors, etc., with wide color reproduction range without lowering the chroma and luster, and provide an ink set produced by using the water-based ink composition and an inkjet recording method using the same. <P>SOLUTION: The water-based ink composition contains a combination of at least two kinds of coloring materials selected to reproduce a color having low visibility (e.g. yellow) to a color having high visibility, a color having poor brilliancy (e.g. red) to a color having high brilliancy, and a light color difficult to color discrimination (e.g. light green) to a light color having good color discrimination. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to the CIE 1976 (L ^* a ^* b ^* ) color system a ^* value in the low dot density portion (ie, “light color portion”) and high dot density portion (ie, “dark color portion”). The ratio of the value of b ^* hardly changes depending on the density, and the ratio between the value of a ^{* and} the value of b ^* due to the difference in the recording medium can be reproduced in a color with little density. At least 2 colorants so that the reduction in visibility (high brightness) and the improvement in visibility (low brightness and high saturation) can be achieved simultaneously and efficiently. The present invention relates to a water-based ink composition containing more than one species, an ink set including the water-based ink composition, and an ink jet recording method using them. Note that the expressions “light color part” and “dark color part” express a “light part” and a “dark part” in relative color comparison.

Conventionally, as ink for inkjet recording, a dye-based ink basically composed of a dye and an aqueous medium is known. It has been pointed out that these inks are inferior in light resistance and water resistance of printed matter due to the properties of dyes. Therefore, in order to solve such a problem, an ink using a pigment instead of a dye has been used.

Pigment inks are generally excellent in image fastness of printed matter compared to dye inks, and are used in various applications that take advantage of their characteristics, such as wide format color ink jet recording inks for sign and display markets. . In this color ink jet recording, usually, a three-color ink set including three subtractive primary colors of yellow (Y), magenta (M), and cyan (C) is used, or black is added thereto. Various hues are expressed using a four-color ink set.

However, when recording characters or images using the three-color or four-color ink set, for example, yellow (low brightness and high saturation) with high visibility, clear red (lightness 40 to 50 and high saturation), hue Even if different light green colors (high brightness and high saturation) are to be developed on the recording medium, it is not possible to obtain a desired color sufficiently with only one color ink (that is, one kind of pigment). If you try to reproduce the target color by mixing the inks of the colors, it is not only difficult, but even if it is obtained, the color reproduction range is narrow and the saturation of the printed part (mixed color part) of the secondary color or higher Problems such as lowering occurred. In order to increase the saturation problem, a method of increasing the pigment concentration of each YMC color ink or a method of increasing the amount of YMC ink to be printed on the recording medium is adopted. However, there is a drawback that the hue is changed between the light color portion and the dark color portion (the ratio between the value of a ^{* and} the value of b ^* is deviated), and the hue changes. Further, even if the saturation is simply increased by increasing the pigment concentration as described above, the saturation does not increase so much and the brightness of the “dark portion” or “secondary color” is significantly reduced, which is not effective. In addition, since the brightness of the “light color portion” is remarkably lowered, the graininess is lowered and is not effective. Furthermore, there is a risk of clogging the ink jet printer, which is not effective.

Therefore, the present invention provides a water-based ink composition capable of recording without causing a change in hue between a light color portion and a dark color portion, having a wide color reproduction range, and causing no reduction in saturation. It is an object of the present invention to provide an ink set used and an ink jet recording method using them.

The inventors of the present invention conducted research and research to reproduce highly visible colors, vivid colors, light colors, etc. using various three-color or four-color ink sets. Increasing the shot amount to increase the hue gradually changes, and since the saturation does not increase at the rate of increase in the shot amount and the lightness decreases on the contrary, a particularly mixed color portion is formed. When one water-based ink composition in which each pigment contained in each water-based ink composition used at the time of mixing is used, such a phenomenon can be prevented and the hue of the light color portion and the dark color portion can be prevented. The present invention has been completed by finding that the color can be reproduced with little change.

(1) The aqueous ink composition according to the present invention contains at least two kinds of pigments and water, and is capable of color reproduction with little change in hue between a light color portion and a dark color portion.
(2) The water-based ink composition according to the present invention is the water-based ink composition according to the above (1), wherein the at least two kinds of pigments express colors by dots using the water-based ink composition. The ratio between the a ^* value and b ^* value of the CIE 1976 (L ^* a ^* b ^* ) color system in the low dot density (light color) part and the high dot density (dark color) part depends on the density in the same recording medium. It is characterized by combining approximate colors so as to reduce the changing phenomenon.
That is, when a color is expressed by dots using water-based ink containing at least two kinds of pigments and water, CIE 1976 in a low dot density (light color) portion and a high dot density (dark color) portion on the same recording medium. (L ^* a ^* b ^* ) It is characterized in that approximate colors are combined in order to reduce the phenomenon in which the ratio of the value of a ^* and b ^{* in} the color system changes with density. In addition, the combination of the approximate color here means the combination of the pigment in any one of following (3)-(5), and is specifically as follows.

(3) A water-based ink composition according to the present invention is the water-based ink composition according to the above (1) or (2), and a hue angle defined in a CIE 1976 (L ^* a ^* b ^* ) color system A yellow ink composition having an H ° in the range of about 80 to 110 °, and the at least two kinds of pigments contained therein have a pigment solid content concentration of 3% by weight or more, and the yellow ink The value of L ^{* in} the CIE 1976 (L ^* a ^* b ^* ) color system when the composition was deposited on a dedicated recording medium having a coating layer at 3.8 to 4.2 mg / inch ² (corresponding to Duty 30%) It is a combination of pigment types having a b ^* value of 80 or more and 90 or less.
(4) A water-based ink composition according to the present invention is the water-based ink composition described in (1) or (2) above, and a hue angle defined in the CIE 1976 (L ^* a ^* b ^* ) color system. A magenta ink composition having an H ° of about 330 to 360 °, wherein the at least two types of pigments contained therein have a solid content concentration of 2% or more by weight, and the magenta ink composition CIE 1976 (L ^* a ^* b ^* ) color system L ^* value is 65 when a product is deposited on a dedicated recording medium having a coating layer at 3.8 to 4.2 mg / inch ² (equivalent to Duty 30%). The above is a combination of pigment types having a ^* value of 50 or more.
(5) A water-based ink composition according to the present invention is the water-based ink composition according to the above (1) or (2), and a hue angle defined in a CIE 1976 (L ^* a ^* b ^* ) color system The cyan ink composition has an H ° of about 230 to 260 °, and the at least two pigments contained therein have a solid content concentration of 2% by weight or more, and the cyan ink composition CIE 1976 (L ^* a ^* b ^* ) color system L ^* value is 60 when a product is deposited on a dedicated recording medium having a coating layer at 3.8 to 4.2 mg / inch ² (equivalent to Duty 30%). It is the above, It is characterized by being a combination of pigment types whose a ^* value is −45 or less.

(6) The water-based ink composition according to the present invention is the water-based ink composition according to (1), wherein the at least two kinds of pigments are expressed by dots using the water-based ink composition. It is characterized by combining approximate colors so as to reduce the phenomenon in which the ratio of the value of a ^* and b ^{* in} the CIE 1976 (L ^* a ^* b ^* ) color system in different recording media is reduced. To do. That is, when a color is expressed by dots using an aqueous ink composition containing at least two kinds of pigments and water, the value of a ^* of the CIE 1976 (L ^* a ^* b ^* ) color system and In order to reduce a phenomenon in which the ratio of b ^* values changes, approximate colors are combined. In addition, the combination of the approximate color here means the combination of the pigment in any one of following (7)-(9), and is specifically as follows.

(7) A water-based ink composition according to the present invention is the water-based ink composition according to the above (1) or (6), and a hue angle defined in the CIE 1976 (L ^* a ^* b ^* ) color system a yellow ink composition H ° is in the range of about 80 to 110 °, wherein at least two of the pigment contained therein is calculated from the visible absorption spectrum of the pigment dispersion solution, b ^* of When the value is 55, there is one kind of pigment type Ya whose L ^* value is 95 or more and one kind of pigment kind Yb whose L ^* value is 95 or less.
(8) A water-based ink composition according to the present invention is the water-based ink composition according to the above (1) or (6), and a hue angle defined in the CIE 1976 (L ^* a ^* b ^* ) color system H ° is the magenta ink composition in the range of about three hundred and thirty to three hundred and sixty °, it said at least two kinds of the pigment contained therein is calculated from the visible absorption spectrum of the pigment dispersion solution, a ^* of When the value is 20, there is one kind of pigment type Ma whose L ^* value is 90 or more and one kind of pigment kind Mb whose L ^* value is 90 or less.
(9) A water-based ink composition according to the present invention is the water-based ink composition according to the above (1) or (6), and a hue angle defined in the CIE 1976 (L ^* a ^* b ^* ) color system H ° is the magenta ink composition in the range of about three hundred and thirty to three hundred and sixty °, it said at least two kinds of the pigment contained therein is calculated from the visible absorption spectrum of the pigment dispersion solution, a ^* of When the value is 20, there is one kind of pigment type Ma whose L ^* value is 90 or more and one kind of pigment kind Mb whose L ^* value is 90 or less.

(10) An ink set according to the present invention includes the above-described aqueous ink composition.
(11) An ink cartridge according to the present invention is characterized by containing the above water-based ink composition or the above ink set.
(12) The recording method according to the present invention is characterized by using the above water-based ink composition or an ink set provided with the above water-based ink composition.
(13) The recorded matter according to the present invention is recorded by the recording method described above.

As described in detail above, the present invention contains a combination of at least two types of pigments in the water-based ink composition, so that the hue change between the light color portion and the dark color portion is small, the color reproduction range is wide, and the saturation. An excellent effect is achieved in that the color can be reproduced in a color with improved visibility without causing a decrease in the color.

Hereinafter, the present invention will be described in detail. The present invention reduces the change in hue between the light color portion and the dark color portion, and in the case of yellow, when it is a color reproduction of a relatively low visibility depending on the aqueous ink composition using one kind of pigment. In order to enhance the visibility, or in the case where a color having a high visibility can be reproduced with a water-based ink composition using a single pigment, an aqueous solution using a single pigment is used to further enhance the visibility. Rather than using two or more types of ink compositions to reproduce the color of a printed portion (mixed color portion) of two or more colors, an aqueous ink composition containing a combination of two or more types of pigments is used. In order to obtain a yellow aqueous ink composition with high visibility, for example, C.I. I. Pigment Yellow 73, 74, 93, 94, 95, 97, 98, 108, 109, 113, 117, 120, 128, 129, 138, 151, 153, 154, 156, 173, 180, and C . I. Pigment yellow 24, 65, 87, 110, 116, 139; I. Pigment Orange 31, 36, 42, 43, 51 is used in combination with at least one of them. Preferably, C.I. I. Pigment Yellow 73, 74, 93, 94, 95, 97, 98, 108, 109, 113, 117, 120, 128, 129, 138, 151, 153, 154, 156, 173, 180, and C . I. Pigment yellow 24, 65, 87, 110, 116, 139; I. Pigment Orange 31, 36, 42, 43, 51 is used in combination with at least one of them.

The yellow water-based ink composition having high visibility is a yellow ink composition having a hue angle H ° defined in the CIE 1976 (L ^* a ^* b ^* ) color system of about 80 to 110 °. The at least two types of pigments contained therein are pigment types whose L ^* value is 95 or more when the b ^* value is 55 calculated from the visible light absorption spectrum of the pigment-dispersed aqueous solution. One kind of Ya and one kind of pigment kind Yb whose L ^* value is 95 or less. In the yellow ink composition, the pigment type Ya is, for example, C.I. I. Pigment Yellow 73, 74, 93, 94, 95, 97, 98, 108, 109, 113, 117, 120, 128, 129, 138, 151, 153, 154, 156, 173, 180, The pigment type Yb is, for example, C.I. I. Pigment yellow 24, 65, 87, 110, 116, 139; I. Pigment Orange 31, 36, 42, 43, 51.

The combination ratio of the two varies depending on the degree of improving the visibility and the combination of pigments, but it is preferable to mix the recording medium so that b ^* is −2 to +10, and more preferably 0 to +8. It is preferable to mix as such. In addition, in order to further improve the visibility of normal high-visibility colors, a pigment (combination pigment) that can lower the brightness of pigments that reproduce normal high-visibility colors is used in combination. To do. At that time, the combined pigment is such that the hue angle of the aqueous ink composition using two or more kinds of pigments changes within ± 5% with respect to the hue angle of the aqueous ink composition using only the pigment of the original color. Adjust the amount. For example, C.I. I. For Pigment Yellow 74, C.I. I. Pigment Yellow 110 is used in combination such that the latter is 0.003 to 0.3 with respect to the former 1. By doing in this way, the color reproduction range is wide compared with the case where the color reproduction of the printed part (mixed color part) of two or more colors is performed using the aqueous ink composition separately containing two or more pigments. It is possible to record with a color with reduced saturation and improved visibility. In the present invention, “a color with high visibility” has a saturation / lightness of 1 or more, and the larger the value, the higher the visibility.

In addition to reducing the change in hue between the light color portion and the dark color portion, the present invention reproduces a relatively clear color depending on the aqueous ink composition using one kind of pigment such as red. In order to make it possible to reproduce the color in a clear state when it is difficult, it is not a color reproduction using an aqueous ink composition using one kind of pigment, but a pigment for reproducing the color. For example, C.I. I. Pigment Red 122, C.I. I. A water-based ink composition using a pigment such as CI Pigment Violet 23 is used. The combination ratio of the two varies depending on the combination of pigments, but the latter is preferably 0.03 to 0.1 with respect to the former 1, and more preferably the latter is 0.05 to 0 with respect to the former 1. .1. In addition, C.I. I. Pigment Red 14, 18, 23, 31, 67, 85, 122, 147, 150, 151, 171, 202, 207; I. Pigment Violet 19 or the like may contain C.I. I. At least one of pigment violet 23, 31, 32, 33, 36, 38, 43, 50 and the like can be used in combination.

A water-based ink composition capable of reproducing clear colors is a magenta ink composition having a hue angle H ° defined in the CIE 1976 (L ^* a ^* b ^* ) color system of about 330 to 360 °. When the a ^* value is 20 and the at least two types of pigments contained therein are calculated from the visible light absorption spectrum of the pigment-dispersed aqueous solution, the L ^* value is 90 or more. And one kind of pigment kind Mb whose L ^* value is 90 or less. In the magenta ink composition, the pigment type Ma is, for example, C.I. I. Pigment red 206, 207, 209; I. Pigment Violet 19, and the pigment type Mb is, for example, C.I. I. It is at least one of Pigment Red 122 and 202. Combination ratio between the two varies depending combination of pigments, a ^* is positive, b ^* is in the negative region a ^* / b ^* is set to be the vicinity of -1. By doing so, there is little change in hue between the light color part and the dark color part, and the color reproduction range is wide, and the saturation and glossiness are reduced compared with the case where color reproduction is performed with only a single color. It is possible to record with a color with improved clarity without inviting. In the present invention, the “clear color” is determined to be a color having a saturation / lightness of 1 or more and a higher saturation as the saturation is higher.

In addition to reducing the change in hue between the light color portion and the dark color portion, the present invention has a different hue depending on the water-based ink composition using one kind of pigment such as a light green color having a different hue. If the light green color is difficult to reproduce, use two or more water-based ink compositions that use one type of pigment to reproduce the color of the light green color printed part (mixed color part) with a different hue. And pigments for reproducing the original color, such as C.I. I. Pigment Blue 15: 3, C.I. I. A water-based ink composition is used in combination with Pigment Green 7. In addition, a water-based ink composition that reproduces a light green color having a different hue is cyan having a hue angle H ° defined in the CIE 1976 (L ^* a ^* b ^* ) color system of about 230 to 260 °. When the a ^* value is −30 when the at least two types of pigments contained in the ink composition are calculated from the visible light absorption spectrum of the pigment-dispersed aqueous solution, the value of L ^* is One type of pigment type Ca that is 85 or more and one type of pigment type Cb that has a value of L ^* of 85 or less.

In the cyan ink composition, the pigment species Ca is, for example, C.I. I. Pigment Blue 15: 1, 15: 2, 15: 3, 15: 4, 15: 5, and the pigment type Cb is, for example, C.I. I. Pigment Green 7, 10, 36, 47; C.I. I. Pigment blue 16 and at least one of Mg, Zn, V, Ni, Fe, Co, Ti, Al, and Mn phthalocyanine. The combination ratio of the two varies depending on the combination of the pigments, but the latter is preferably 0.003 to 0.1 with respect to the former 1, and more preferably the latter is 0.05 to 0.1 with respect to the former 1. 0.1. In this way, when a light green color having a different hue is reproduced using an aqueous ink composition containing two or more pigments, the color reproduction range is wide and the saturation is reduced. It is possible to classify the light colors. In the present invention, “light color” means that the saturation / lightness is 1 or less, and the smaller the value, the lighter the color.

As described above, the water-based ink composition of the present invention contains at least two types of pigments, but the pigments to be used are not limited to those described above, and both inorganic pigments and organic pigments are used. be able to. As the inorganic pigment, for example, cobalt oxide, copper oxide, iron oxide and the like can be used. Examples of organic pigments include azo pigments (for example, azo lakes, insoluble azo pigments, or condensed azo pigments), polycyclic pigments (for example, phthalocyanine pigments, quinacridone pigments, thioindigo pigments, etc.), dye chelates (for example, basic compounds) Dye-type chelates, acid dye-type chelates, etc.), nitro pigments, nitroso pigments, aniline black, and the like. Further, the total content of the pigment in the water-based ink composition is preferably 0.1 to 2% by weight, more preferably 1.5%, based on the total weight of the water-based ink composition, from the viewpoints of glossiness and saturation. ~ 2% by weight.

Examples of the pigment for yellow ink include C.I. I. Pigment Yellow 1 (Heiza Yellow), 3 (Heiza Yellow 10G), 12, 13, 14, 17, 24 (Flavantron Yellow), 34, 35, 37, 53, 55, 65, 73, 74, 81, 83, 87, 93, 94, 95, 97, 98, 99, 108 (anthrapyrimidine yellow), 109, 110, 113, 116, 117 (copper complex pigment), 120, 128, 129, 133 (quinophthalone), 138, 139 (Isoindolinone), 147, 151, 153 (nickel complex pigment), 154, 156, 167, 172, 173, 180, and the like.

Examples of pigments for magenta ink include C.I. I. Pigment Red 1 (Para Red), 2, 3 (Toluidine Red), 5 (ITR Red), 7, 9, 10, 11, 12, 14, 17, 18, 23, 30, 31, 38 (Pyrazolone Red), 42 , 67, 88 (thioindigo), 112 (naphthol AS series), 114 (naphthol AS series), 122 (dimethylquinacridone), 123, 144, 147, 149, 150, 151, 166, 168 (antanthrone orange), 170 (Naphthol AS), 171, 175, 176, 177, 178, 179 (Beryllen maroon), 185, 187, 202, 209 (Dichloroquinacridone), 219, 224 (Beryllene), 245 (Naphthol AS), Or C.I. I. Pigment violet 9 (quinacridone), 19, 23 (dioxazine violet), 31, 32, 33, 36, 38, 43, 50 and the like.

Examples of the pigment for cyan ink include C.I. I. Pigment Blue 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 5, 16 (metal-free phthalocyanine), 18 (alkali blue toner), 25, 60 (slen blue), 65 (violanthrone) , 66 (Indigo) and the like.

Examples of organic pigments used in color inks other than magenta, cyan, or yellow ink include C.I. I. Pigment green 7 (phthalocyanine green), 10 (green gold), 36, 37, 47; I. Pigment brown 3, 5, 25, 26; I. Pigment Orange 1, 2, 5, 7, 13, 14, 15, 16, 31, 34, 36, 38, 42, 43, 51 and the like.

The aqueous ink composition of the present invention preferably contains a dispersant from the viewpoint of enhancing the dispersion stability of the pigment. As the dispersant, those similar to those in this type of pigment ink composition can be used without particular limitation, but it is preferable to add at least a surfactant. As the dispersant, those similar to those in this kind of pigment ink composition can be used without particular limitation, and examples thereof include polymer dispersants, cationic surfactants, anionic surfactants, nonionic properties. A surfactant or the like is used. Examples of natural polymer dispersants include proteins such as glue, gelatin, casein and albumin, natural rubbers such as gum arabic and tragacanth, glycoxides such as saponin, alginic acid and propylene glycol alginate, triethanolamine alginate And alginic acid derivatives such as ammonium alginate, and cellulose derivatives such as methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, and ethylhydroxycellulose. Examples of the synthetic polymer dispersant include polyacrylic acid, polymethacrylic acid, acrylic acid-acrylonitrile copolymer, vinyl acetate-acrylic acid ester copolymer, acrylic acid-acrylic acid alkyl ester copolymer, styrene. -Acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-acrylic acid-alkyl acrylate copolymer, styrene-methacrylic acid-alkyl acrylate copolymer, styrene-α-methylstyrene-acrylic acid Copolymer, styrene-α-methylstyrene-acrylic acid-acrylic acid alkyl ester copolymer, styrene-maleic acid copolymer, vinylnaphthalene-maleic acid copolymer, vinyl acetate-ethylene copolymer, vinyl acetate- Fatty acid vinyl ethylene copolymer, vinyl acetate-maleic acid Examples include a steal copolymer, a vinyl acetate-crotonic acid copolymer, and a vinyl acetate acrylic acid copolymer. As these polymer dispersants, those having a molecular weight of 1,000 to 10,000 are preferable.

Examples of the cationic surfactant include ammonium salt of polyoxyethylene alkyl ether sulfate, and examples of the anionic surfactant include sodium dodecylbenzenesulfonate and sodium laurate. Examples of nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene alkyl ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylphenyl ether, polyoxyethylene alkylamine, polyoxyethylene alkylamide, etc. Is mentioned. In the aqueous ink composition, the dispersant is preferably contained in an amount of 0.1 to 10% by weight, more preferably 0.3 to 6% by weight, in terms of solid content, with respect to the pigment.

The water-based ink composition of the present invention preferably contains at least alkylene glycol monoalkyl ether and / or 1,2-alkylene glycol from the viewpoint of increasing wettability to a recording medium and enhancing permeability. The alkylene glycol monoalkyl ether is preferably an ether of an alkylene glycol having 10 or less repeating units and an alcohol having 3 to 10 carbon atoms. The ether of alkylene glycol having 10 or less repeating units and an alcohol having 3 to 10 carbon atoms is preferably di (tri) ethylene glycol monobutyl ether and / or (di) propylene glycol monobutyl ether. Di (tri) ethylene glycol monobutyl ether refers to diethylene glycol monobutyl ether (DEGmBE) and / or triethylene glycol monobutyl ether (TEGmBE). The aqueous ink composition of the present invention preferably contains 20% by weight or less of the di (tri) ethylene glycol monobutyl ether. If it exceeds 20% by weight, it becomes difficult to use due to an increase in viscosity. More preferably, it is 1 to 15% by weight. As a necessary level of permeability for improving print quality, the content is preferably 20% by weight or less. If it exceeds 20% by weight, the effect of improving the printing quality will reach its peak, and the adverse effect of increasing the viscosity will occur. More preferably, it is 0.5 to 10% by weight.

The 1,2-alkylene glycol is a 1,2-alkylene glycol having 4 to 10 carbon atoms, and those having less than 4 carbon atoms have a low effect of improving the permeability, and when the number of carbon atoms exceeds 10, the water-soluble It is difficult to use for water-soluble inks such as the present invention because of its low nature. And it is preferable that content is 15 weight% or less. If it exceeds 15% by weight, it will be difficult to use for inkjet due to the increase in viscosity, and even if it is contained more than that, there will be no effect of improving print quality. However, it is not limited to this for writing instruments. More preferably, it is 1 to 8% by weight. The 1,2-alkylene glycol is preferably 1,2-pentanediol and / or 1,2-hexanediol. The content of 1,2-pentanediol is preferably 3 to 15% by weight. If the amount is less than 3% by weight, the effect of improving the permeability is low, and therefore, bleeding is often generated. When the content exceeds 15% by weight, the water-solubility is low, so that it is difficult to use in the water-soluble ink composition as in the present invention. The amount of 1,2-hexanediol is preferably 0.5 to 10% by weight.

Further, the water-based ink composition of the present invention may contain a surfactant other than the above from the viewpoint of improving the wettability to the recording medium and enhancing the permeability. The surfactant is preferably at least one selected from acetylene glycol surfactants, acetylene alcohol surfactants, and polysiloxane surfactants. As the acetylene glycol surfactant, commercially available ones can be used. For example, Surfynol 82, 440, 465 (both trade names, manufactured by Air Products and Chemicals), Olphine Y, STG, E1010 (both trade names, manufactured by Nissin Chemical Co., Ltd.) and the like can be mentioned, and one or more of these are used. In particular, Surfynol 465 is preferably used. As the acetylene alcohol surfactant, Surfynol 61 (manufactured by Air Products and Chemicals Co., Ltd.) or the like can be used as a commercially available product. In addition, as the polysiloxane surfactant, BYK348 (manufactured by Big Chemie Japan) or the like can be used as a commercially available product. The water-based ink composition of the present invention contains 0.1 to 5% by weight of one or more selected from the acetylene glycol surfactants, acetylene alcohol surfactants, and polysiloxane surfactants. Preferably, if it exceeds 5% by weight, the effect of the print quality will reach its peak, and if it is contained more than that, the viscosity will increase and it will be difficult to use, and the ink will tend to adhere to the tip of the head, and the print will be confused. On the other hand, if it is less than 0.1%, the effect of improving the printing quality is lowered. A more preferred content is 0.15 to 2% by weight.

The water-based ink composition of the present invention includes the acetylene glycol surfactant and / or acetylene alcohol surfactant, di (tri) ethylene glycol monobutyl ether, (di) propylene glycol monobutyl ether, and 1,2-alkylene. It is preferable to contain at least one selected from glycols at the same time. By using them simultaneously, the print quality can be improved. The content of the acetylene glycol surfactant and / or acetylene alcohol surfactant is 0.01 to 0.5% by weight, di (tri) ethylene glycol monobutyl ether, (di) propylene glycol monobutyl ether and 1, The content of one or more selected from 2-alkylene glycol is preferably 1% by weight or more. The acetylene glycol-based surfactant and / or acetylene alcohol-based surfactant has an effect of improving permeability in a small amount. Accordingly, 0.5% by weight or less is sufficient, and one or more selected from di (tri) ethylene glycol monobutyl ether, (di) propylene glycol monobutyl ether and 1,2-alkylene glycol is 1% by weight or more. The print quality is further improved.

The content of the acetylene glycol-based surfactant and / or acetylene alcohol-based surfactant is 0.5% or less, and the content ratio with the 1,2-alkylene glycol (hereinafter simply referred to as a ratio is included) The weight ratio of the quantity) is preferably 1: 0 to 1:10. When 1,2-alkylene glycol exceeds 10 times the amount of acetylene glycol surfactant and / or acetylene alcohol surfactant, the effect of improving the printing quality is peaked, and even if it is contained more than that, the effect is low and the viscosity is reversed. Causes the negative effects of the rise.

The content of the acetylene glycol surfactant and / or the acetylene alcohol surfactant is 0.5% or more, and the ratio with di (tri) ethylene glycol monobutyl ether is 1: 0.01 to 1:50. Preferably there is. From the viewpoint of printing quality, it is preferable to contain up to 50 times the amount of acetylene glycol surfactant and / or acetylene alcohol surfactant. Di (tri) ethylene glycol monobutyl ether is useful for improving the solubility of acetylene glycol surfactants and improving the printing quality. However, when the content exceeds 50 times, the effect reaches its peak, so for inkjet use. It becomes difficult to use.

The ratio of the acetylene glycol surfactant and / or acetylene alcohol surfactant to (di) propylene glycol monobutyl ether is preferably 1: 0.01 to 1:50. (Di) When propylene glycol monobutyl ether exceeds 50 times the amount of acetylene glycol surfactant and / or acetylene alcohol surfactant, the effect of improving the printing quality is peaked, and even if contained more, the effect is low. The adverse effect of viscosity increase and low water solubility make it necessary to contain a dissolution aid. More preferably, it is 0.5 to 5%.

The aqueous ink composition of the invention is characterized in that the pigment is dissolved or dispersed in water without a dispersant. In order to dissolve or disperse in water without this dispersant, water-soluble functional groups such as sulfonic acid groups, carboxyl groups, hydroxyl groups, amino groups or amide groups are introduced directly or through short molecules on the pigment surface. There is a way to do it.

In addition, the water-based ink composition of the present invention is a microcapsule type in which the pigment is included in a polymer. The microcapsule type in which a pigment is included in a polymer includes a method in which a separately polymerized polymer is adsorbed on the surface of the pigment and dispersed, or after being dispersed with a reactive dispersant, the function of the dispersant. There is a method of extending a molecule by further polymerizing using a group.

The polymer containing the pigment is mainly composed of at least one selected from the group consisting of polyacrylate, styrene-acrylic acid copolymer, polystyrene, polyester, polyamide, polyimide, silicon-containing polymer, and sulfur-containing polymer. It is preferable to do. One or more selected from acetylene glycol surfactant and / or acetylene alcohol surfactant used in the present invention, di (tri) ethylene glycol monobutyl ether, (di) propylene glycol monobutyl ether and 1,2-alkylene glycol Since the substance consisting of the above causes an adsorption / desorption reaction with the dispersant used for normal dispersant dispersion, the desorbed dispersant may float in the ink, which may cause a phenomenon in which printing is disturbed. However, it is preferable to carry out suitable dispersion using the above-mentioned polymer because the polymer stably contains a colorant, and hence it is difficult to cause adsorption and desorption.

Furthermore, it is preferable that the colorant including the pigment as a polymer includes the pigment as a copolymer of at least a dispersant having a polymerizable group and a copolymerizable monomer. Here, the dispersant having a polymerizable group has at least a hydrophobic group, a hydrophilic group and a polymerizable group, and the polymerizable group is an acryloyl group, a methacryloyl group, an allyl group or a vinyl group, and is a copolymerizable group. Are also acryloyl group, methallyloyl group, allyl group or vinyl group. As the ink for ink jet recording, it is preferable that the particle diameters are relatively uniform from the viewpoint of clogging and ejection stability. Therefore, the colorant containing the pigment in the polymer is preferably produced by emulsion polymerization. Further, a suitable dispersing agent having as a main component at least one selected from the group consisting of polyacrylic acid ester, styrene-acrylic acid copolymer, polystyrene, polyester, polyamide, polyimide, silicon-containing polymer and sulfur-containing polymer. From the acetylene glycol surfactants and / or acetylene alcohol surfactants, glycol ethers and / or 1,2-alkylene glycols, which are solid polymers and may be used in the present invention. It is preferable because it does not deform even if it contains one or more selected substances, and it is easy to obtain a uniform particle size.

The colorant including the pigment as a polymer is obtained by dispersing the pigment with a dispersant having a polymerizable group and then emulsion-polymerizing in water using a monomer copolymerizable with the dispersant and a polymerization initiator. It is preferable that

In addition, the aqueous ink composition of the present invention can contain a high-boiling organic solvent from the viewpoint of preventing the aqueous ink composition from drying and preventing clogging at the head of the inkjet printer. Examples of the high-boiling organic solvent include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, propylene glycol, butylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, glycerin, and triglyceride. Polyhydric alcohols such as methylolethane and trimethylolpropane; ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, Many such as triethylene glycol monobutyl ether Alkyl ethers of alcohols: urea, 2-pyrrolidone, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, triethanolamine, sugars such as sugar alcohol, etc., and one of these Or 2 or more types are used. The high-boiling organic solvent is preferably contained in the aqueous ink composition in an amount of 0.1 to 30% by weight, more preferably 0.5 to 20% by weight.

In addition to the pigment, the water-based ink composition of the present invention contains a dispersant, a high-boiling organic solvent, a low-boiling organic solvent, and a penetration accelerator as necessary, and water as a balance. The water is preferably pure or ultrapure water such as ion exchange water, ultrafiltration water, reverse osmosis water, or distilled water. In particular, water obtained by sterilizing these waters by irradiation with ultraviolet rays or containing hydrogen peroxide is preferable because generation of mold and bacteria is prevented over a long period of time.

The aqueous ink composition of the present invention includes a fixing agent such as a water-soluble rosin, an antifungal agent / preservative such as sodium benzoate, an antioxidant / ultraviolet absorber such as an allophanate, and a chelating agent, if necessary. , A pH adjusting agent and other additives can be contained, and one or more of these can be used.

The aqueous ink composition of the present invention can be prepared in the same manner as the conventional aqueous pigment ink composition using a conventionally known apparatus such as a ball mill, a sand mill, an attritor, a basket mill, a roll mill, and a jet mill. . In the preparation, it is preferable to remove coarse particles using a centrifuge, a membrane fighter, a mesh filter, or the like.

The ink set of the present invention is a three-color ink set comprising the three subtractive primary colors yellow, magenta and cyan ink, or a four-color ink set obtained by adding black to this. The water-based ink composition of the present invention is provided, or the water-based ink composition of the present invention is provided in place of at least one of the three-color water-based pigment ink compositions of yellow, magenta, and cyan. Is an ink set. The ink set of the present invention comprises the above-described aqueous ink composition of the present invention, so that a color with high visibility, a clear color, a light-colored light color, etc. have a wide color reproduction range, a reduction in saturation, and a glossiness. It is possible to record without incurring a decrease in image quality.

The ink jet recording cartridge of the present invention is characterized by containing the above-mentioned aqueous ink composition or the above ink set by a conventionally known means.

The ink jet recording method of the present invention is characterized by using the ink or ink set of the present invention. For example, when the ink-jet recording method of the present invention reproduces a highly visible color, a clear color, a light-colored light color, etc. on a recording medium, the aqueous ink composition of three colors of yellow, magenta and cyan is used. When the water-based ink composition of the present invention is used in a single color instead of at least one and / or a mixed color portion of a secondary color or more is formed on a recording medium, the three-color water-based ink composition of yellow, magenta and cyan is used. And at least one of the water-based ink compositions of the present invention.

Next, although the pigment dispersion used for the water-based ink composition of the present invention and the preparation method thereof are illustrated, of course, the pigment dispersion used in the present invention is not limited to the following examples.

(Preparation of Dispersion 1) First, C.I. I. Pigment Yellow 74 (manufactured by Clariant) is used. The pigment is mixed with sulfolane, subjected to high-speed shear dispersion with a high-speed mixer, and then gently stirred. After adding sulfamic acid to the dispersion, the mixture is heated to 60 to 200 ° C. and then stirred for 10 hours. Is introduced into the pigment surface. Thereafter, heat treatment is performed to remove the solvent and the remaining sulfolane and sulfamic acid from the pigment slurry. Removal is performed by repeated centrifugation and filtration. The average particle diameter measured by the laser scattering method of the treated pigment thus treated was 100 nm. The surface-treated pigment thus obtained was diluted with water, the pH was adjusted to 9.0 with sodium hydroxide, and a surface-treated pigment dispersion 1 was prepared at a concentration of 20% by weight.

(Preparation of Dispersion 2) C.I. I. Dispersion 2 was prepared using Pigment Yellow 110 (Ciba Geigy).
(Preparation of Dispersion 3) C.I. I. Dispersion 3 was prepared using Pigment Blue 15: 3 (Ciba Geigy).
(Preparation of Dispersion 4) C.I. I. Dispersion 4 was prepared using Pigment Violet 23 (manufactured by Dainichi Seika Co., Ltd.).
(Preparation of Dispersion 5) C.I. I. Dispersion 5 was prepared using Pigment Red 122 (manufactured by Clariant).
(Preparation of Dispersion 6) C.I. I. Dispersion 6 was prepared using Pigment Yellow 180 (manufactured by Clariant).

(Preparation of Dispersion 7) First, a dispersion polymer is prepared. A flask equipped with a stirrer, a reflux tube, a thermometer and a dropping funnel was replaced with nitrogen, charged with 20 g of styrene, 2 g of acrylic acid, and 10 g of butyl methacrylate and heated to 70 ° C., 100 g of styrene, 5 g of acrylic acid, 50 g of butyl methacrylate, azobis Polymerization is carried out while dropping a mixture of 1.5 g of dimethylvaleronitrile into the flask over 3 hours. Next, a mixed liquid of 8 g of azobisisovaleronitrile and 30 g of methyl ethyl ketone is added over 1 hour to accelerate the polymerization. After completion of the reaction, 200 g of methyl ethyl ketone is added to the flask to prepare a dispersed polymer solution. Next, 30 g of this polymer solution, C.I. I. 30 g of Pigment Yellow 74 and 50 g of a 0.1 mol / L aqueous sodium hydroxide solution were stirred with a homogenizer, 500 g of ion-exchanged water was added to the resulting mixture, and the mixture was further stirred, and then methyl ethyl ketone and a part of water were distilled off with an evaporator. Thus, Dispersion 7 which is a polymer-containing pigment was obtained.

(Preparation of Dispersion 8) C.I. I. Dispersion 8 was prepared using Pigment Yellow 110 (Ciba Geigy).
(Preparation of Dispersion 9) C.I. I. Dispersion 9 was prepared using Pigment Blue 15: 3 (manufactured by Clariant).
(Preparation of Dispersion 10) C.I. I. Dispersion 10 was prepared using Pigment Violet 23 (manufactured by Dainichi Seika Co., Ltd.).
(Preparation of Dispersion 11) C.I. I. Dispersion 11 was prepared using Pigment Red 122 (manufactured by Clariant).
(Preparation of Dispersion 12) C.I. I. Dispersion 12 was prepared using Pigment Yellow 180 (Ciba Geigy).

Next, although the Example of this invention is given with a comparative example and this invention is demonstrated concretely, this invention is not limited by the following Examples.

(Preparation Example of Inkjet Ink) Specific examples of compositions suitable for the inkjet recording ink according to the present invention are shown below. The amount added is shown as the amount converted by weight. The added amount of the dispersion is shown as the amount (solid content concentration: the total amount of the pigment and the dispersed polymer surrounding it) converted by weight. The numerical value shown in <> after the dispersion indicates the particle size of the pigment in nm units. In this embodiment, the remaining amount of water is 0.05% for Proxel XL-2 for preventing corrosion of the ink, 0.02% for benzotriazole for preventing corrosion of the inkjet head member, and the ink system. In order to reduce the influence of the metal ions contained therein, 0.04% of EDTA is added to the ion exchange water.

(Example 1) Addition amount (%)
Dispersion 1 <105> 9.5 Dispersion 2 <100> 0.5 DEGmBE 5.0 Orphine E1010 1.0 Glycerin 9.0 1,5-pentanediol 5.0 Triethanolamine 0.8 Water Remaining amount DEGmBE : Diethylene glycol monobutyl ether orphine E1010: Acetylene glycol surfactant (manufactured by Nissin Chemical Industry Co., Ltd.)

(Example 2) Addition amount (%)
Dispersion 3 <85> 4.5 Dispersion 4 <95> 0.3 TEGmBE 10.0 Diprolene glycol 5.0 Surfinol 465 1.2 Triethanolamine 0.9 Water Residual amount DEGmBE: Triethylene glycol monobutyl ether Surfynol 465: Acetylene glycol surfactant (manufactured by Air Products (USA))

(Example 3) Addition amount (%)
Dispersion 5 <90> 8.5 Dispersion 6 <80> 0.5 1,2-hexanediol 10.0 Orphine STG 0.5 Diethylene glycol 7.0 Thiodiglycol 3.5 1,6-hexanediol 0 Triethanolamine 1.0 Potassium hydroxide 0.1 Water Remaining amount Olfin STG: Acetylene glycol surfactant (manufactured by Nissin Chemical Industry Co., Ltd.)

(Example 4) Addition amount (%)
Dispersion 7 <80> 10.0 Dispersion 8 <90> 0.4 TEGmBE 3.0 1,2-pentanediol 5.0 Surfynol 61 0.5 Tetraethylene glycol 9.0 1,5-pentanediol 2 0.0 Dimethyl-2-imidazolidinone 2.0 Sodium benzoate 0.1 Triethanolamine 0.7 Water Residual amount Surfynol 61: Acetylene alcohol-based surfactant (produced by Air Products (USA))

(Example 5) Addition amount (%)
Dispersion 9 <90> 8.0 Dispersion 10 <90> 0.6 BYK348 0.5 DPGmBE 2.0 DEGmBE 7.0 Glycerin 14.0 Triethanolamine 0.9 Water Remaining amount DPGmBE: Dipropylene glycol monobutyl ether BYK348: polysiloxane-based surfactant (by Big Chemie Japan)

(Example 6) Addition amount (%)
Dispersion 11 <95> 8.5 Dispersion 12 <90> 0.5 Orphine E1010 1.0 TEGmBE 6.0 Glycerin 15.0 Thiodiglycol 2.0 1,5-pentanediol 1.0 Triethanolamine 0 .9 Remaining water

Table 1 shows a ^* when the printing duty is changed for the ink compositions shown in Examples 1 to 6 and the ink compositions shown in Comparative Examples 1 to 6 except the even-numbered dispersions in Examples 1 to 6 ^. The rate of change in the value of / b ^* (print duty 50% standard) is shown, and Table 2 shows the ink compositions shown in Examples 1 to 6 and the ink compositions shown in Comparative Examples 1 to 6 as a. ^The rate of change of the value of ^* / b ^* (print duty 50%, Xerox 4024 standard) is shown. As is apparent from the results of Tables 1 and 2, in the present invention, since the change in the value of a ^* / b ^* is small, it can be seen that there is little change in hue in printing of the light color portion and the dark color portion.

Table 3 shows the evaluation result of bleeding when characters are printed as the evaluation result of printing. In Table 3, A is very good, B is good, C is bad, and D is very bad.

As is apparent from the results in Table 3, it can be seen that the print quality is good when the ink for ink jet recording used in the present invention is used. These print evaluations were measured by using an ink jet printer EM-900C manufactured by Seiko Epson Corporation. The papers used for these evaluations are plain papers that are commercially available in Europe, the United States, and Japan, such as Conqueror paper, Faborit paper, Modo Copy paper, Rapid Copy paper, EPSON EPP paper, Xerox 4024 paper, Xerox 10 paper, Neenha Bond. Paper, Rcopyy 6200 paper, Yamayuri paper, Xerox R paper. As described above, according to the present invention, it is possible to provide a high-quality and highly practical ink for ink-jet recording, in which bleeding of a printed image on a recording medium such as paper is reduced.

Further, the ink compositions of Examples 1 to 6 were put in a glass sample bottle and sealed, and left at 60 ° C./week for 1 week, and the generated foreign matter and physical properties (viscosity, surface tension) of the ink composition before and after being left. ) Was investigated. As a result, none of the ink compositions produced foreign matter and hardly changed the physical property values, and had good storage stability.

Further, in the composition of Example 1, other additives (acetylene glycol surfactant, acetylene alcohol surfactant, polysiloxane surfactant, di (tri)) that may be used in the present invention instead of DEGmBE and E1010 Ink compositions prepared using ethylene glycol monobutyl ether, (di) prolene glycol monobutyl ether and one or more substances selected from 1,2-alkylene glycol) are similarly allowed to stand at 60 ° C./1 week. As a result of examining the generated foreign matter, physical properties (viscosity, surface tension) and ejection stability in the ink composition after being left as it was, no foreign matter was generated and the ejection stability was good. The amount of foreign matter generated is the amount of foreign matter after standing at 60 ° C./initial amount of foreign matter, the viscosity is the viscosity after standing at 60 ° C./initial viscosity, and the surface tension is the value of surface tension after standing at 60 ° C./initial surface tension. The ejection stability is A, less than 10 prints where 100 pages are continuously printed on A4 size Xerox P paper using an ink jet printer EM-900C manufactured by Seiko Epson Corporation and no print disturbance occurs. B indicates that there is a disturbance, and C indicates that there is a printing disturbance of 10 or more and less than 100, and D indicates that there is a printing disturbance of 100 or more.

As is clear from the results of Tables 1 to 3, the ink composition according to the present invention has a CIE 1976 (L ^* a ^* b ^* ) color system in the low dot density portion and the high dot density portion on the same recording medium. less that the ratio of the a ^* and b ^* values are changed by their density, also, the ratio of the difference by a ^* and b ^* values of the recording medium is also reduced to vary, a wide color reproduction range Therefore, the ink for ink-jet recording is less likely to cause a decrease in saturation and can provide storage stability and ejection stability. Further, it has excellent effects such as light resistance, gas resistance, colorability, glossiness, and fixability.

Examples of compositions suitable for other ink jet recording inks according to the present invention will be shown. The amount added is shown as the amount converted by weight. The added amount of the dispersion is shown as the amount (pigment solid content concentration: total amount of pigment) converted to weight. The numerical values shown in <> after the dispersion indicate the particle size of the pigment in nm units. In this embodiment, the remaining amount of water is 0.05% for Proxel XL-2 for preventing corrosion of the ink, 0.02% for benzotriazole for preventing corrosion of the inkjet head member, and the ink system. In order to reduce the influence of the metal ions contained therein, 0.04% of EDTA is added to the ion exchange water.

(Example 7) Addition amount (%)
Dispersion 1 <70> 1.5 Dispersion 2 <70> 1.5 Glycerin 15.0 Ethylene glycol 3.0 1,2-hexanediol 5.0 BYK348 0.3 Triethanolamine 0.8 Water Remaining amount BYK348 : Polysiloxane surfactant (BIC Chemie Japan)

(Example 8) As a pigment, C.I. I. Pigment Yellow 74 is 1.5% by weight and C.I. I. Example 7 is the same as Example 7 except that 1.5% by weight of Pigment Yellow 147 is used.

(Example 9) Addition amount (%)
Dispersion 7 <70> 1.5 Dispersion 8 <70> 1.5 Glycerin 15.0 Ethylene glycol 3.0 1,2-hexanediol 5.0 BYK348 0.3 Triethanolamine 0.8 Water Remaining amount

Example 10 As a pigment, C.I. I. Pigment Yellow 74 is 1.5% by weight and C.I. I. Example 9 is the same as Example 9 except that 1.5% by weight of Pigment Yellow 147 was used.

(Comparative Example 7) As a pigment, C.I. I. The same as Example 7 except that 3% by weight of Pigment Yellow 74 was used.

(Comparative Example 8) As a pigment, C.I. I. The same as Example 7 except that 3% by weight of Pigment Yellow 110 was used.

(Comparative Example 9) As a pigment, C.I. I. Example 7 is the same as Example 7 except that 3% by weight of Pigment Yellow 147 is used.

Example 11 As a pigment, C.I. I. Pigment Violet 19 and 1% by weight C.I. I. Example 7 is the same as Example 7 except that 1% by weight of Pigment Red 122 was used.

(Example 12) As a pigment, C.I. I. Pigment Violet 19 and 1% by weight C.I. I. Example 9 is the same as Example 9 except that 1% by weight of Pigment Red 122 was used.

(Example 13) As a pigment, C.I. I. Pigment Violet 19 and 1% by weight C.I. I. Example 7 is the same as Example 7 except that 1% by weight of Pigment Red 202 was used.

(Example 14) As a pigment, C.I. I. Pigment Violet 19 and 1% by weight C.I. I. Example 9 is the same as Example 9 except that 1% by weight of Pigment Red 202 was used.

Example 15 As a pigment, C.I. I. Pigment Red 207 at 1% by weight and C.I. I. Example 7 is the same as Example 7 except that 1% by weight of Pigment Red 122 was used.

(Example 16) As a pigment, C.I. I. Pigment Red 207 at 1% by weight and C.I. I. Example 9 is the same as Example 9 except that 1% by weight of Pigment Red 122 was used.

(Example 17) As a pigment, C.I. I. Pigment Red 209 at 1% by weight and C.I. I. Example 7 is the same as Example 7 except that 1% by weight of Pigment Red 122 was used.

(Example 18) As a pigment, C.I. I. Pigment Red 209 at 1% by weight and C.I. I. Example 9 is the same as Example 9 except that 1% by weight of Pigment Red 122 was used.

(Example 19) As a pigment, C.I. I. Pigment Red 207 at 1% by weight and C.I. I. Example 7 is the same as Example 7 except that 1% by weight of Pigment Red 202 was used.

(Example 20) As a pigment, C.I. I. Pigment Red 207 at 1% by weight and C.I. I. Example 9 is the same as Example 9 except that 1% by weight of Pigment Red 202 was used.

(Example 21) As a pigment, C.I. I. Pigment Red 209 at 1% by weight and C.I. I. Example 7 is the same as Example 7 except that 1% by weight of Pigment Red 202 was used.

(Example 22) As a pigment, C.I. I. Pigment Red 209 at 1% by weight and C.I. I. Example 9 is the same as Example 9 except that 1% by weight of Pigment Red 202 was used.

(Comparative Example 10) C.I. I. The same as Example 7 except that 2% by weight of Pigment Red 122 was used.

(Comparative Example 11) As a pigment, C.I. I. The same as Example 7 except that 2% by weight of Pigment Red 202 was used.

(Comparative Example 12) As a pigment, C.I. I. The same as Example 7 except that 2% by weight of Pigment Red 207 was used.

(Comparative Example 13) As a pigment, C.I. I. The same as Example 7 except that 2% by weight of Pigment Red 209 was used.

L ^* value when the b ^* value is 55 calculated from the visible light absorption spectrum of the pigment-dispersed aqueous solution of the pigment used in the ink compositions shown in Examples 7-10 and Comparative Examples 7-9, The value of L ^* when the value of a ^* is 20, calculated from the visible light absorption spectrum of the pigment-dispersed aqueous solution of the pigment used in the ink compositions shown in Examples 11 to 22 and Comparative Examples 10 to 13, and the above CIE1976 (L ^* a ^* b ^* ) color system at the time of adhering to a dedicated recording medium (PM photographic paper) corresponding to a print duty of 30% using the ink compositions shown in Examples 7 to 22 and Comparative Examples 7 to 13 Table 4 shows L ^* values, a ^* values, and b ^* values.

Table 5 shows the change rate of the value of a ^* / b ^* when the print duty is changed (print duty 50%) for the same recording medium for the ink compositions shown in Examples 7-22 and Comparative Examples 7-13. Table 6 shows the change rate of the value of a ^* / b ^* due to the difference in the recording medium for the ink compositions shown in Examples 7 to 22 and Comparative Examples 7 to 13 (print duty 50%, Xerox 4024 standard). Indicates. As is apparent from the results of Tables 5 and 6, in the present invention, since the change in the value of a ^* / b ^* is small, it can be seen that the hue change between the light color portion and the dark color portion is small.

Table 7 shows the evaluation results of visibility and bleeding. As an example of a plain paper Xerox P, and printing inks of Examples 7 to 10 and Comparative Examples 7-9, respectively 7 mg / inch ² and 9 mg / inch ^2.
Evaluation criteria A: Visibility is good and there is no bleeding.
B: Visibility is good, but there is some bleeding.
C: Visibility is poor and bleeding occurs.
D: Visibility is somewhat good, but there is clearly bleeding.

From the results in Table 7, it can be seen that the low brightness and high b ^* ink of the present invention is superior in order to achieve both improved visibility and prevention of bleeding as shown in Table 4.

Table 8 shows the evaluation results of color clarity and bleeding. As an example of plain paper, Xerox P was mixed with an ink of “Comparative Example 7 and any of Examples 11 to 22” or “Comparative Example 7 and any of Comparative Examples 10 to 13” at a total of 10 mg / inch ^2. Or printed at 12 mg / inch ² .
Evaluation criteria A: Good color clarity and no bleeding.
B: Color clarity is good, but there is some bleeding.
C: Color clarity is somewhat good, but there is bleeding.
D: Color clarity is poor and there is a clear blur.
From the results in Table 8, it can be seen that the high brightness and high a ^* ink of the present invention is superior in order to achieve both improved color clarity and prevention of bleeding as shown in Table 4.

These print evaluations were measured by using an ink jet printer EM-900C manufactured by Seiko Epson Corporation. The paper used for these evaluations is plain paper commercially available in Europe, the United States and Japan, such as Favorit paper, Xerox P paper, Xerox 4024 paper, and Xerox 10 paper. As described above, according to the present invention, it is possible to provide a high-quality and highly practical ink for ink-jet recording, in which bleeding of a printed image on a recording medium such as paper is reduced.

Further, the ink compositions of Examples 7 to 22 were put in a glass sample bottle and sealed, and left at 60 ° C./week for 1 week, and foreign matters and physical properties (viscosity, surface tension) of the ink composition before and after being left. ) Was investigated. As a result, none of the ink compositions produced foreign matter and hardly changed the physical property values, and had good storage stability.

As is clear from the results in Tables 4 to 8, the ink composition according to the present invention has a CIE 1976 (L ^* a ^* b ^* ) color system in the low dot density portion and the high dot density portion on the same recording medium. less that the ratio of the a ^* and b ^* values are changed by their density, also, the ratio of the difference by a ^* and b ^* values of the recording medium is also reduced to vary, a wide color reproduction range Therefore, the ink for ink-jet recording is less likely to cause a decrease in saturation and can provide storage stability and ejection stability. Further, it has excellent effects such as light resistance, gas resistance, colorability, glossiness, and fixability.

Claims (23)

A water-based ink composition containing at least two types of pigments and water, wherein the at least two types of pigments represent a low dot density portion when color is expressed by dots using the water-based ink composition. Approximate colors are used to reduce the phenomenon in which the ratio of the a ^* value and b ^* value of the CIE 1976 (L ^* a ^* b ^* ) color system in the high dot density portion varies with density on the same recording medium. The water-based ink composition according to claim 1, which is a combination. The water-based ink composition is a yellow ink composition having a hue angle H ° defined in the CIE 1976 (L ^* a ^* b ^* ) color system in the range of about 80 to 110 °, and is contained therein. The at least two types of pigments have a pigment solid content concentration of 3% by weight or more, and the yellow ink composition was deposited on a dedicated recording medium having a coating layer at 3.8 to 4.2 mg / inch ² . CIE 1976 (L ^* a ^* b ^* ) color system of time (Duty 30% equivalent) is a combination of pigment types such that the L ^* value is 90 or less and the b ^* value is 80 or more 2. The water-based ink composition according to 1. The at least two kinds of pigments, when the color is expressed by dots using the water-based ink composition, a ^{* of the} CIE 1976 (L ^* a ^* b ^* ) color system in the low dot density portion and the high dot density portion ^. The water-based ink composition according to claim 1, wherein approximate ratios are combined so as to reduce a phenomenon in which the ratio of the value of b and the value of b ^* varies depending on the density on different recording media. The water-based ink composition is a yellow ink composition having a hue angle H ° defined in the CIE 1976 (L ^* a ^* b ^* ) color system in the range of about 80 to 110 ° and contained therein. When the b ^* value is 55 and the at least two kinds of pigments are calculated from the visible light absorption spectrum of the pigment-dispersed aqueous solution, the L ^* value is 95 or more, and the L ^* value is 95 or more ^. The water-based ink composition according to claim 1, wherein the value is one of pigment types Yb having a value of 95 or less. The pigment type Ya is C.I. I. Pigment Yellow 73, 74, 93, 94, 95, 97, 98, 108, 109, 113, 117, 120, 128, 129, 138, 151, 153, 154, 156, 173, 180, The pigment type Yb is C.I. I. Pigment yellow 24, 65, 87, 110, 116, 139; I. The water-based ink composition according to claim 7, which is at least one of pigment oranges 31, 36, 42, 43, and 51. The water-based ink composition according to claim 1, wherein the pigment is dissolved or dispersed in water without a dispersant. The water-based ink composition according to claim 1, wherein the pigment is dispersed by a polymer dispersant having a molecular weight of 1000 to 10,000. The water-based ink composition according to any one of claims 1 to 7, wherein the pigment is a microcapsule type encapsulated with a polymer. The water-based ink composition according to claim 1, wherein at least a surfactant is added to the water-based ink composition. The aqueous ink composition according to claim 9, wherein the surfactant is one or more selected from an acetylene glycol surfactant, an acetylene alcohol surfactant, or a polysiloxane surfactant. The water-based ink composition according to claim 1, wherein at least one of alkylene glycol monoalkyl ether and 1,2-alkylene glycol is added to the water-based ink composition. The water-based ink composition according to claim 11, wherein the alkylene glycol monoalkyl ether is an ether formed from an alkylene glycol having 10 or less repeating units and an alcohol having 3 to 10 carbon atoms. The aqueous ink composition according to claim 11, wherein the alkylene glycol monoalkyl ether is di (tri) ethylene glycol monobutyl ether and / or (di) propylene glycol monobutyl ether. The aqueous ink composition according to claim 11, wherein the 1,2-alkylene glycol is 1,2-hexanediol and / or 1,2-pentadiol. The water-based ink composition includes at least the acetylene glycol surfactant and / or acetylene alcohol surfactant, di (tri) ethylene glycol monobutyl ether, (di) propylene glycol monobutyl ether, and 1,2-alkylene glycol. The water-based ink composition according to any one of claims 9 to 14, wherein one or more selected ones are added simultaneously. The acetylene glycol and / or acetylene alcohol surfactant is 0.01 to 0.5%, and is selected from di (tri) ethylene glycol monobutyl ether, (di) propylene glycol monobutyl ether and 1,2-alkylene glycol. The water-based ink composition according to claim 15, wherein at least one kind is 1% or more. An ink set comprising the water-based ink composition according to any one of claims 1 to 16. An ink set comprising the water-based ink composition according to any one of claims 1 to 16, and at least one of yellow ink, magenta ink, and cyan ink. An ink set comprising the water-based ink composition according to any one of claims 1 to 16, and at least one of red ink and violet ink. An ink set comprising the ink set according to any one of claims 17 to 19 and a black ink. An ink jet recording cartridge comprising the water-based ink composition according to any one of claims 1 to 16 or the ink set according to any one of claims 17 to 20. A recording method using the water-based ink composition according to any one of claims 1 to 16 or the ink set according to any one of claims 17 to 20. A recorded matter recorded by the recording method according to claim 22.