JP2010132909A - Ink set, recording method and recorded matter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a black ink composition for prevention of golden gloss, obtaining recorded matter in which golden gloss is prevented or restrained, and to provide an ink set containing the ink composition, a recording method and recorded matter using the ink set. <P>SOLUTION: The black ink composition for prevention of golden gloss comprises (1) water, (2) carbon black and (3) a fine particle emulsion, wherein (A) the content of the carbon black is less than 0.4 wt.%, and (B) the content of the fine particle emulsion is 20 times or more the content of the carbon black. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a black ink composition, an ink set containing the black ink composition, a recording method using the ink set, and a recorded matter obtained by the method. According to the black ink composition of the present invention, it is possible to effectively suppress the occurrence of golden gloss in the recorded matter.

  Depending on the ink jet recording method or the like, an ink set containing two or more types of black inks having different carbon black concentrations may be used for the purpose of obtaining a good black-and-white monochrome image or gray scale. For example, a two-color ink set composed of black ink and light black ink may be used as a black-and-white monochrome image recording ink set. Also, in the color recording ink set, in order to meet the demand for high quality of the achromatic portion (black, gray and white portions) of the color image, 4 consisting of black ink, cyan ink, magenta ink and yellow ink is used. A color ink set (or a 6-color ink set obtained by adding a light cyan ink and a light magenta ink to them) and a light black ink may be further added to form a 5-color ink set (or a 7-color ink set). The light black ink has a carbon black concentration lower than that of the black ink, and is used for the purpose of improving the color reproducibility with respect to the dark color such as the shadow portion and the gray gradation as described above.

For example, by using three types of black inks having different carbon black concentrations, the stability of gray balance and metamerism are dramatically improved. The effect is particularly great in terms of gray balance.
That is, when gray balance is output with only one type or two types of black ink, graininess in a high tone region (bright region) becomes a problem. As a means for eliminating this graininess, for example, there is a method of outputting a high tone achromatic region by mixing cyan ink, magenta ink, and yellow ink. However, if a method of outputting an achromatic color region with a plurality of types of chromatic colors is adopted, very high technology is required for management of output colors, and there is a risk that output colors may vary.

  There are various factors in the variation in the output color, and one of them is variation in ink weight among cyan ink (light cyan ink), magenta ink (light magenta ink), and yellow ink. That is, when the ink weight varies, the output color varies. For example, when the discharge amount of cyan ink increases by 10% and the discharge amount of yellow ink decreases by 10%, the overall output color shifts to the bluish side. Of course, ink jet printers are always designed to produce exactly the same output. However, since ink is a liquid, it is affected by changes in the external environment. For example, the viscosity of the ink changes due to a temperature change. In an ink jet system that discharges ink by applying pressure from an ink jet head, the ink discharge amount naturally changes when the viscosity of the ink liquid changes. In order to reduce these effects, for example, an inkjet printer has a temperature correction function at the time of output to the head drive, but it is actually difficult to completely eliminate even a slight change in ink weight. There is the possibility of slight ink weight changes. Furthermore, in addition to the change in output color due to temperature, humidity can also be a factor, and the recording medium (inkjet media) is also a factor in subtle color changes under the influence of these environments.

  The above-mentioned drawback in the method of outputting a high tone area (bright area) with a plurality of kinds of chromatic colors is solved by using a third black ink having a low carbon black density. That is, when the third black ink having a low carbon black density is used, even if variations in the ink discharge amount occur, it is not affected by the change in the hue of the achromatic color, and as a result, the hue is stabilized. Become.

  Black ink is the color with the highest dot visibility. In order to reduce the dot visibility in, for example, a high tone region, it is necessary to reduce the concentration of carbon black contained in the ink. On the other hand, it is also necessary to keep the carbon black concentration above a certain level in order to express “blackness” firmly. For this purpose, it is necessary to use ink having a density at which dots cannot be seen (or difficult to see) and ink having a carbon black density to express blackness firmly. From this point of view, it is difficult to express intermediate gradations using only two types of black ink, so that intermediate density ink is required. As described above, an ink set having three or more types of black ink including a black ink having a low carbon black density and an intermediate density ink is very significant.

However, few examples are currently known in which the effects and drawbacks of recording using an ink set having two or more types of black ink were studied and the results reported.
For example, JP-A-6-226998 (Patent Document 1) describes an image recording apparatus and a recording head that use a plurality of types of ink compositions having different concentrations. However, Japanese Patent Laid-Open No. 6-226998 only describes a recording apparatus having black, yellow, magenta, and cyan having two to four different densities.
Japanese Patent Application Laid-Open No. 11-320924 (Patent Document 2) describes an image recording apparatus using a plurality of types of black ink compositions having different carbon black concentrations in combination with a set of color ink compositions, and a control method therefor. Has been. However, the technique described in Japanese Patent Application Laid-Open No. 11-320924 is intended to form a monochrome high gradation image separately from a color image on the same recording medium. Only the use of a plurality of types of black ink compositions is described.

JP-A-6-226998 Japanese Patent Laid-Open No. 11-320924

Under such circumstances, the present inventor has been studying the effects and disadvantages of recording using an ink set having two or more (particularly three) black ink compositions. When recording with a thin black ink composition, when a fluorescent lamp or external light is reflected on the recorded image in the recorded image, the reflected light has a problem of generating a gloss like gold. I found it. The inventor named this phenomenon "golden gloss". In other words, the golden gloss refers to an area recorded with a thin black ink composition when an observer's observation angle or a light source irradiation angle is changed with respect to a recorded image printed on a recording medium. This is a phenomenon in which the portion glitters in gold, and when golden gloss occurs, it is very difficult to determine even the color tone of the recorded matter and the contour of the image.
Therefore, the present inventor has intensively studied means for preventing or suppressing the occurrence of the golden gloss, and by effectively adding the fine particle emulsion to the ink composition in a certain amount or more, the occurrence of the golden gloss is virtually eliminated. I found that I can do it. The present invention is based on these findings.
Accordingly, an object of the present invention is to provide a black ink composition that prevents or suppresses the occurrence of golden gloss and an ink set that prevents or suppresses the occurrence of golden gloss.

The inventor has further studied the effects and drawbacks of recording using an ink set having two or more (particularly three) black ink compositions. It has been found that when recording is performed using the black ink composition for gradation, there is a problem that a portion where gray brightness is shifted in the recorded image is generated. The present inventor named this phenomenon as phase shift. The phase shift is one of the areas recorded with the black ink composition for intermediate gradation when the observer's observation angle or the light source irradiation angle is changed with respect to the recorded image printed on the recording medium. This is a phenomenon in which the lightness of the gray is shifted at the portion, and is observed to be shifted to the black or white side from the original gray. When a phase shift occurs, it becomes very difficult to discriminate even the contour of the image due to a shift in the brightness of the recorded matter.
Therefore, the present inventor has intensively studied means for preventing or suppressing the occurrence of the phase shift, and virtually eliminates the occurrence of the phase shift by adding the fine particle emulsion to the ink composition at a specific amount or more. I found that I can do it.
Accordingly, another object of the present invention is to provide an ink set that prevents or suppresses the occurrence of golden gloss and prevents or suppresses the occurrence of a phase shift.

  According to the present invention, there is provided a black ink composition comprising (1) water, (2) carbon black, and (3) a fine particle emulsion, wherein (A) the content of the carbon black is 0.00. It can be solved by the black ink composition, which is less than 4% by weight and (B) the solid content of the fine particle emulsion is 20 times or more of the content of carbon black.

According to a preferred aspect of the present invention, the carbon black content is 0.01% by weight or more.
According to another preferred embodiment of the present invention, the fine particle emulsion contains a polyalkylene emulsion and / or an ethylenically unsaturated carboxylic acid monomer and another monomer copolymerizable therewith, containing an alcoholic hydroxyl group. It contains an emulsion containing a pH-adjusted resin whose pH is adjusted with an inorganic base as a resin component, a copolymer having an acid value of 40 or less obtained by polymerization in the presence of a water-soluble polymer compound or a copolymerizable surfactant. .
According to another preferred embodiment of the present invention, the inorganic base used for the preparation of the pH adjusting resin is an alkali metal hydroxide or an alkaline earth metal hydroxide.
According to another preferred embodiment of the present invention, the alcoholic hydroxyl group-containing water-soluble polymer compound used for the preparation of the pH adjusting resin is a vinyl alcohol polymer.
According to still another preferred embodiment of the present invention, the ethylenically unsaturated carboxylic acid monomer used for the preparation of the pH adjusting resin is acrylic acid or methacrylic acid.
According to still another preferred embodiment of the present invention, the monomer copolymerizable with the ethylenically unsaturated carboxylic acid monomer used for the preparation of the pH adjusting resin is an ethylenically unsaturated carboxylic acid ester monomer. It is.
According to still another preferred embodiment of the present invention, the pH of the emulsion containing the pH adjusting resin as a resin component is 8 to 11 (more preferably 9 to 11).
According to still another preferred embodiment of the present invention, the content of the pH adjusting resin is 0.01% by weight to 10% by weight with respect to the total weight of the black ink composition.

According to a preferred embodiment of the present invention, the solid content of the polyalkylene type emulsion is 0.5% by weight to 10% by weight with respect to the total weight of the black ink composition.
According to a preferred embodiment of the present invention, the polyalkylene type emulsion is a polyethylene type emulsion or a polypropylene type emulsion.
According to another preferred embodiment of the present invention, the total content of the pH adjusting resin and the polyalkylene type emulsion solid content is 0.5 wt% to 20 wt% with respect to the total weight of the black ink composition. is there.
According to another preferred embodiment of the present invention, the black ink composition further comprises a complementary colorant.
The black ink composition of the present invention is preferably for inkjet recording.

The present invention also relates to an ink set including the black ink composition and a dark black ink composition having a carbon black concentration higher than that of the black ink composition. The ink set preferably has a carbon black content of 0.4% to 1.5% by weight (preferably 0.4 to 1% by weight and / or 1%) based on the total weight of the black ink composition. -1.5 wt.%) And a dark black ink composition having a carbon black content of 1.5 wt.% To 10 wt.% Relative to the total weight of the black ink composition. including.
Furthermore, the present invention relates to an ink set in which the above-described black ink composition for halftone contains a fine particle emulsion, and the solid content of the fine particle emulsion is at least twice the carbon black content. The ink set preferably includes, as the fine particle emulsion, an emulsion having the polyalkylene emulsion and / or the pH adjusting resin as a resin component.
Furthermore, the present invention is a recording method for performing recording by ejecting droplets of an ink composition and attaching the droplets to a recording medium, wherein the ink set is used. Related.
The present invention also relates to a recorded image recorded by the recording method.

It is a graph which shows typically the field where golden gloss (GG) occurs, and the field where phase shift occurs when gray scale is printed using three kinds of black ink compositions.

  As described above, “golden gloss” (hereinafter sometimes abbreviated as GG) means changing the observation angle of the observer with respect to the recorded image printed on the recording medium, When the irradiation angle is changed, this is a phenomenon in which a part of the area recorded with the thin black ink composition glitters in gold. According to the inventor's research, golden gloss occurs only in certain areas. When this golden gloss occurs, it becomes impossible to determine the color tone of the recorded matter not only in the generating area but also in the neighboring area, and it becomes very difficult to determine the contour of the recorded image.

  An area where golden gloss occurs will be described with reference to FIG. As schematically shown in FIG. 1, by changing the usage ratios of the dark black ink composition K1, the intermediate gradation black ink composition K2, and the thin black ink composition K3, a gray color from black to white can be obtained. A scale can be created appropriately. As described above, when the three types of black ink compositions K1, K2, and K3 are used, the gray balance stability and metamerism can be drastically improved as described above. However, as shown in the “GG generation region” (that is, the golden gloss generation region) in FIG. 1, the golden gloss is generated mainly in the region recorded by the thin black ink composition K3.

The “GG generation region” extends from about 90 to about 160 with a gray level of about 100 to about 140 as the center (where gray level 0 is absolute black and gray level 255 is absolute white). To do). In addition, the brightness range of the “GG generation region” ranges from about 50 to about 60 as a central region and ranges from about 40 to about 70.
When recording a black-and-white monochrome image using two or more kinds of black ink compositions, the black ink composition used for recording the GG generation region is usually carbon black and the total weight of the black ink composition. Is a relatively thin black ink composition having a concentration of less than 0.4% by weight (particularly, an amount of 0.01% by weight or more and less than 0.4% by weight).

  The present invention solves the phenomenon found by the present inventors that occurs when a plurality of black ink compositions are used, and in an ink set including a plurality of black ink compositions, the total weight of the composition To further eliminate or suppress golden gloss in a black ink composition containing carbon black in an amount of less than 0.4% by weight (particularly, an amount of 0.01% by weight or more and less than 0.4% by weight). Provided is a black ink composition capable of containing a fine particle emulsion and obtaining a recorded image in which the generation of GG is prevented or reduced by containing the fine particle emulsion in a specific amount or more.

  On the other hand, as described above, the phase shift means that the black ink composition for intermediate gradation is obtained by changing the observation angle of the observer or the irradiation angle of the light source with respect to the recorded image printed on the recording medium. This is a phenomenon in which the gray brightness is shifted in a part of the area recorded in the above and is observed shifted to the black side or the white side from the original gray. When the phase shift occurs, the area looks lighter gray than the original gray, looks dark gray, or becomes completely black, so that it is very difficult to discriminate even the contour of the image. Such a phenomenon is particularly likely to occur when recording on a glossy recording medium such as a glossy tone or a semi-glossy tone, and is relatively difficult to occur with a matte tone recording medium.

The region where the phase shift occurs is a region recorded mainly by the black ink composition K2 for intermediate gradation, as shown in "Phase shift generation region" in FIG. The “phase shift occurrence region” extends from about 30 to about 60 with a gray level of about 35 to about 55 as the center (here, gray level 0 is absolute black and gray level 255 is absolute white). And). Further, the brightness range of the “phase shift generation region” ranges from about 25 to about 30 as a central region and ranges from about 20 to about 35.
When recording a black-and-white monochrome image using two or more kinds of black ink compositions, the black ink composition used for recording the phase shift occurrence region is usually carbon black as a whole of the black ink composition. It is a black ink composition for midtones having an amount of 0.4 wt% to 1.5 wt% based on the weight.

  In another aspect, the present invention solves a plurality of phenomena found by the present inventors (that is, golden gloss and phase shift) that occur when a plurality of black ink compositions are used. In an ink set including an ink composition, (1) carbon black in an amount of less than 0.4 wt% (particularly, an amount of 0.01 wt% or more and less than 0.4 wt%) with respect to the total weight of the composition In order to eliminate or suppress the golden gloss, the black ink composition further containing a fine particle emulsion, and more than a specific amount of the fine particle emulsion, and (2) with respect to the total weight of the composition Fine particles are added to the black ink composition containing carbon black in an amount of 0.4 wt% to 1.5 wt% in order to further eliminate or suppress phase shift. Is contained Marujon, moreover, by incorporating the fine particle emulsion in a specific amount or more, to provide an ink set capable of obtaining recorded images of being prevented or reduced at the same time the occurrence of golden gloss and phase shift.

The fine particle emulsion contained in the black ink composition for preventing golden gloss of the present invention is an aqueous dispersion in which the dispersion medium is water and the dispersoid is polymer fine particles. The minimum film-forming temperature (MFT) of the polymer fine particles contained in the fine particle emulsion is not particularly limited, but is preferably 25 ° C. or less, more preferably 0 to 25 ° C., and further preferably 10 to 20 ° C. . MFT is measured according to JIS K 6800. By printing on a recording medium using the ink composition according to the present invention containing an emulsion having an MFT in the above range, a protective film covering the printing surface at room temperature is automatically formed.
The solid content concentration of the fine particle emulsion in the black ink composition for preventing golden gloss can be any concentration as long as it is 20 times or more of the carbon black concentration. It is 0.2-20 weight% with respect to a weight, Preferably it is 0.5-15 weight%, More preferably, it is 1-8 weight%.

On the other hand, when the ink set of the present invention contains a black ink composition for preventing phase shift, the fine particle emulsion contained in the black ink composition for preventing phase shift also has a dispersion medium of water and a dispersoid. It is an aqueous dispersion which is a polymer fine particle. The minimum film-forming temperature (MFT) of the polymer fine particles contained in the fine particle emulsion is not particularly limited, but is preferably 25 ° C. or less, more preferably 0 to 25 ° C., and further preferably 10 to 20 ° C. .
The solid content concentration of the fine particle emulsion in the black ink composition for preventing phase shift can be any concentration as long as it is at least twice the carbon black concentration. It is 0.8-10 weight% with respect to a weight, Preferably it is 1-8 weight%, More preferably, it is 1.5-5 weight%.

The glass transition temperature (Tg) of the polymer fine particles contained in the fine particle emulsion is preferably −15 to 10 ° C. from the viewpoint of adjusting the MFT of the emulsion within the above range, and is −5 to 5 ° C. More preferably it is. Tg is measured according to JIS K 6900.
Examples of other methods for adjusting the MFT of the emulsion within the above range include a method using a commercially available MFT depressant.

  The polymer fine particles preferably have an average particle diameter of 5 to 200 nm, and more preferably 5 to 100 nm, from the viewpoint of dispersion stability in the ink composition.

The polymer fine particles preferably have a hydrophilic portion and a hydrophobic portion.
Further, the polymer fine particles may have a single-phase structure, a multi-phase structure (core-shell structure), or the like. The core-shell structure may be a structure in which two or more different types of polymers are present in phase separation. For example, the shell part completely covers the core part, and the shell part covers a part of the core part. Structure in which a part of the shell polymer forms a domain or the like in the core polymer, one or more layers between the core and the shell, and three or more layers including layers having different compositions It may be a structure.

  When the polymer fine particle having the core-shell structure is used, it is preferable that the core part is made of a polymer having an epoxy group and the shell part is made of a polymer having a carboxyl group. By including such polymer fine particles in the ink composition, when the protective film is formed, the epoxy group of the core portion and the carboxyl group of the shell portion are combined to form a network structure. The strength of the film can be improved.

  The polymer fine particles have a structure derived from an unsaturated vinyl monomer having a carboxyl group in an amount of 1 to 10% by weight, and preferably have two or more polymerizable double bonds, more preferably three or more. What has the structure (structure derived from a crosslinkable monomer) bridge | crosslinked by the crosslinkable monomer is 0.2 to 4 weight%. By including such polymer fine particles in the ink composition, the surface of the nozzle plate is hardly wetted by the ink, so that the flight of the ink droplets can be prevented and the ejection stability can be further improved. Can do.

  Examples of the unsaturated vinyl monomer having a carboxyl group include acrylic acid, methacrylic acid, itaconic acid, fumaric acid and maleic acid, and methacrylic acid is particularly preferable.

  Examples of the crosslinkable monomer include polyethylene glycol acrylate, triethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,6-butylene glycol diacrylate, 1,6-hexanediol diacrylate, and neopentyl glycol diacrylate. Acrylate, 1,9-nonanediol diacrylate, polypropylene glycol diacrylate, 2,2′-bis (4-acryloxypropyloxyphenyl) propane, 2,2-bis (4-acryloxydiethoxyphenyl) propane, etc. Diacrylate compounds; triacrylate compounds such as trimethylolpropane triacrylate, trimethylolethane triacrylate, tetramethylolmethane triacrylate; ditrimethyloltetraacrylate Tetraacrylate compounds such as relate, tetramethylolmethane tetraacrylate, pentaerythritol tetraacrylate; hexaacrylate compounds such as dipentaerythritol hexaacrylate; ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, 1 , 3-butylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, dipropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, polybutylene glycol dimethacrylate, 2 , 2'-bis (4-methacrylic Dimethacrylate compounds such as carboxymethyl diethoxy phenyl) propane; can be mentioned methylol Levis acrylamide, divinyl benzene and the like; trimethylolpropane dimethacrylate, trimethacrylate compounds such as trimethylol ethane trimethacrylate.

  The polymer fine particles are contained in the ink composition according to the present invention as the emulsion, and the emulsion can be produced by a known emulsion polymerization. For example, the emulsion of the polymer fine particles is produced by emulsion polymerization of an unsaturated vinyl monomer in water in the presence of a surfactant (emulsifier), a polymerization catalyst, a polymerization initiator, a molecular weight modifier, a neutralizing agent, and the like. Is done.

  Examples of the unsaturated vinyl monomer (monomers constituting the polymer fine particles) include acrylic acid ester monomers, methacrylic acid ester monomers, aromatic vinyl monomers, vinyl ester monomers, vinyl generally used in emulsion polymerization. Cyanide monomers, halogenated monomers, olefin monomers, diene monomers and the like can be mentioned. Specifically, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-amyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, decyl acrylate, dodecyl acrylate, octadecyl Acrylic esters such as acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, glycidyl acrylate; methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, 2-ethylhexylme Methacrylates such as acrylate, octyl methacrylate, decyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, glycidyl methacrylate; vinyl esters such as vinyl acetate; vinyl cyanides such as acrylonitrile; vinylidene chloride Halogenated monomers such as vinyl chloride; aromatic vinyl monomers such as styrene, 2-methylstyrene vinyl toluene, tert-butyl styrene, chlorostyrene, vinyl anisole, vinyl naphthalene; ethylene, propylene, isopropylene, etc. Olefins; Dienes such as butadiene and chloroprene; Vinyl monomers such as vinyl ether, vinyl ketone and vinyl pyrrolidone It can be given over class.

  Examples of the surfactant include an anionic surfactant (sodium dodecylbenzenesulfonate, sodium laurate, ammonium salt of polyoxyethylene alkyl ether sulfate, etc.) and a nonionic surfactant (polyoxyethylene alkyl ether, Polyoxyethylene alkyl ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylphenyl ether, polyoxyethylene alkylamine, polyoxyethylene alkylamide, etc.), and one or more of these may be used. Can do. Further, acetylene glycol [olefin Y and surfinol 82, 104, 440, 465, and 485 (all manufactured by Air Products and Chemicals Inc.)] can also be used.

  At the time of production of the emulsion (the polymer fine particles), from the viewpoint of improving printing stability, the emulsion polymerization is selected from the group consisting of acrylamides and hydroxyl group-containing monomers in addition to the unsaturated vinyl monomer. It is preferable to mix 1 type (s) or 2 or more types. Examples of the acrylamides include acrylamide and N, N′-dimethylacrylamide. In use, one or more of these can be used. Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, and the like, and one or more of these can be used.

In addition, when the polymer fine particle having the core-shell structure is used, an emulsion containing the fine polymer particle is, for example, a method disclosed in JP-A-4-76004 (multistage emulsion polymerization of the unsaturated vinyl monomer). ) And the like.
As described above, it is preferable that the core-shell polymer fine particles are made of a polymer having an epoxy group in the core part. However, as an introduction method of the epoxy group into the core part, for example, unsaturated having an epoxy group A method of copolymerizing vinyl monomers glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, etc. with other unsaturated vinyl monomers, or preparing one core portion (core particle) by polymerizing one or more unsaturated vinyl monomers And a method of simultaneously adding an epoxy compound and combining them. In particular, the former method is preferable in terms of ease of polymerization, polymerization stability, and the like.

  In the black ink composition for preventing golden gloss of the present invention, the solid content of the fine particle emulsion is 20 times or more the content of the carbon black. The upper limit is not particularly limited, but if it is 50 times or more the content of the carbon black, ejection failure may occur. When the content of the fine particle emulsion is less than 20 times the content of the carbon black, the golden gloss cannot be sufficiently suppressed.

  Further, when the ink set of the present invention contains a black ink composition for preventing phase shift, the solid content of the fine particle emulsion in the black ink composition for preventing phase shift is 2 of the content of the carbon black. More than double the amount. The upper limit is not particularly limited, but if it is 10 times or more the content of the carbon black, ejection failure may occur. When the content of the fine particle emulsion is less than twice the content of the carbon black, the phase shift cannot be sufficiently suppressed.

  Examples of the resin component of the fine particle emulsion include, for example, an ethylenically unsaturated carboxylic acid monomer and other monomers copolymerizable therewith, an alcoholic hydroxyl group-containing water-soluble polymer compound or a copolymerizable surfactant. A pH-adjusted resin produced by adjusting the pH of a copolymer having an acid value of 40 or less (hereinafter referred to as “alkali-soluble copolymer”) obtained by polymerization in the presence of an agent with an inorganic base Can do.

  In the black ink composition for preventing golden gloss of the present invention, the content of the pH adjusting resin may be 0.01 to 10% by weight with respect to the total weight of the black ink composition. 5 to 5% by weight, more preferably 1 to 3% by weight. However, when the pH adjusting resin content is 5% by weight or more, although there is an effect in suppressing the generation of GG, the color of the printed matter may change immediately after printing.

  Further, when the ink set of the present invention contains a black ink composition for preventing phase shift, in the black ink composition for preventing phase shift, the content of the pH adjusting resin is similarly the total weight of the black ink composition. Can be about 0.01 to about 10% by weight, preferably about 0.05 to about 5% by weight, more preferably about 0.1 to about 1% by weight.

  The alcoholic hydroxyl group-containing water-soluble polymer compound used for producing the alkali-soluble copolymer includes, for example, 5 to 25 alcoholic hydroxyl groups per 1,000 molecular weights of the water-soluble polymer compound. For example, vinyl alcohol polymers such as polyvinyl alcohol and various modified products thereof; saponified products of copolymers of vinyl acetate and acrylic acid, methacrylic acid or maleic anhydride; alkyl cellulose, hydroxyalkyl cellulose, Examples thereof include cellulose derivatives such as alkylhydroxyalkyl cellulose; starch derivatives such as alkyl starch, carboxymethyl starch and oxidized starch; gum arabic, tragacanth gum; polyalkylene glycol and the like. Of these, vinyl alcohol polymers are preferred from the viewpoint of easy availability of industrially stable products.

The weight average molecular weight of the alcoholic hydroxyl group-containing water-soluble polymer compound is not particularly limited, but is usually 1,000 to 500,000, preferably 2,000 to 300,000. When the molecular weight is less than 1,000, the dispersion stabilizing effect may be lowered. On the other hand, when the molecular weight is more than 500,000, the viscosity when polymerized in the presence of the polymer compound becomes high and the polymerization becomes difficult. Sometimes.
The amount of the alcoholic hydroxyl group-containing water-soluble polymer compound used in the production of the alkali-soluble copolymer is usually 0.05 to 20 parts by weight, preferably 1 to 100 parts by weight of the monomer. 10 parts by weight. If the amount is less than 0.05 parts by weight, the dispersion stabilizing effect is lowered, so that aggregates are generated at the time of polymerization. Conversely, if the amount is more than 20 parts by weight, the viscosity at the time of polymerization becomes high and the polymerization may be difficult. .

  In the production of an alkali-soluble copolymer, it is preferable not to use a surfactant that is usually used in emulsion polymerization. However, when a surfactant is used in combination, the amount of the surfactant is an alkali-soluble copolymer. The amount is usually less than 0.05 parts by weight with respect to 100 parts by weight of all the monomers used for the synthesis. When the amount of the surfactant is increased, the obtained image tends to be inferior in water resistance.

The ethylenically unsaturated carboxylic acid monomer used for the production of the alkali-soluble copolymer is not particularly limited, and examples thereof include ethylenically unsaturated monocarboxylic acid monomers such as acrylic acid and methacrylic acid; itaconic acid and maleic acid. Ethylenically unsaturated polyvalent carboxylic acid monomers such as acid, fumaric acid and butenetricarboxylic acid; ethylenically unsaturated polyvalent carboxylic acid moieties such as monobutyl fumarate, monobutyl maleate and mono-2-hydroxypropyl maleate And ester monomers; polyhydric carboxylic acid anhydrides such as maleic anhydride and citraconic anhydride; and the like. These monomers can be used individually or in combination of 2 or more types. Of these ethylenically unsaturated acid monomers, ethylenically unsaturated monocarboxylic acids such as (meth) acrylic acid are preferred, and methacrylic acid is more preferred.
The amount of the ethylenically unsaturated carboxylic acid monomer used is an amount calculated such that the acid value of the alkali-soluble copolymer is 40 or less, preferably 10 to 40, more preferably 30 to 40. When this amount is converted and the acid value of the alkali-soluble copolymer exceeds 40 or less than 10, the quality of the obtained image may be inferior.

  Other monomers that can be used for the production of the alkali-soluble copolymer and copolymerizable with the ethylenically unsaturated carboxylic acid monomer are not particularly limited. For example, styrene, α-methylstyrene, vinyl Aromatic vinyl monomers such as toluene and chlorostyrene; methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, (meth ) Acrylic acid-n-amyl, (meth) acrylic acid isoamyl, (meth) acrylic acid-n-hexyl, (meth) acrylic acid-2-ethylhexyl, (meth) acrylic acid-n-octyl, (meth) acrylic acid Ethylenically unsaturated carboxylic acids such as 2-hydroxyethyl, hydroxypropyl (meth) acrylate, and glycidyl (meth) acrylate Ester monomers; ethylenically unsaturated nitrile monomers such as (meth) acrylonitrile; ethylenically unsaturated glycidyl ether monomers such as allyl glycidyl ether; (meth) acrylamide, N-methylol (meth) acrylamide, N -Ethylenically unsaturated amide monomers such as butoxymethyl (meth) acrylamide; conjugated diene monomers such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene And carboxylic acid vinyl esters such as vinyl acetate. These monomers can be used alone or in combination of two or more. Among them, an ethylenically unsaturated carboxylic acid ester monomer is preferable, and methyl methacrylate and ethyl acrylate are more preferable in terms of excellent light resistance and gloss of the obtained image.

  The alkali-soluble copolymer can be obtained by polymerizing the monomer mixture, preferably in an aqueous medium, in the presence of an alcoholic hydroxyl group-containing water-soluble polymer compound. At this time, the alcoholic hydroxyl group-containing water-soluble polymer compound and the monomer mixture are added all at once to the reactor before the polymerization is started, or a part is charged before the polymerization is started, and after the polymerization is started. The remaining portion can be added in portions, or the remaining portion can be added continuously. In the case of divided addition or continuous addition, the addition amount can be made uniform or constant, and can be changed according to the progress of polymerization.

  Even if the alcoholic hydroxyl group-containing water-soluble polymer compound and the monomer mixture are added separately, the monomer obtained by mixing the alcoholic hydroxyl group-containing water-soluble polymer compound, the monomer mixture and water It may be added in the form of a dispersion. When the alcoholic hydroxyl group-containing water-soluble polymer compound and the monomer are added separately, it is desirable that the addition of both be started almost simultaneously. If only the monomer mixture is added in a large amount first, agglomerates are likely to be generated. Conversely, if only a large amount of the alcoholic hydroxyl group-containing water-soluble polymer compound is added in advance, the polymerization system will thicken. Or problems such as the occurrence of aggregates are likely to occur. The addition of both does not necessarily have to be the same, but it is desirable that the addition be almost the same.

Among the methods of adding the alcoholic hydroxyl group-containing water-soluble polymer compound and the monomer mixture, the alcoholic hydroxyl group-containing water-soluble polymer compound is mixed with the monomer mixture and water to disperse, and the polymerization is started in the reactor. The addition method is preferable because the chain distribution of the ethylenically unsaturated acid monomer in the polymer chain of the alkali-soluble copolymer becomes uniform.
The alkali-soluble copolymer used for the production of the pH adjusting resin is obtained by polymerizing an ethylenically unsaturated carboxylic acid monomer and other monomers copolymerizable therewith in the presence of a copolymerizable surfactant ( Preferably, it can be produced by emulsion polymerization.

  The copolymerizable surfactant used for producing the alkali-soluble copolymer is a surfactant having one or more polymerizable vinyl groups in the molecule. Specific examples thereof include propenyl-2-ethylhexyl sulfosuccinate sodium salt, (meth) acrylic acid polyoxyethylene sulfate ester, polyoxyethylene alkylpropenyl ether sulfate ammonium salt, (meth) acrylic acid polyoxyethylene ester phosphate ester, etc. Nonionic polymerizable surfactants such as polyoxyethylene alkylbenzene ether (meth) acrylic acid ester and polyoxyethylene alkyl ether (meth) acrylic acid ester. Among these copolymerizable surfactants, polyoxyethylene alkylpropenyl ether ammonium sulfate is preferable because of its excellent balance between the emulsifying and dispersing performance of the monomer and the copolymerizability with the monomer.

  The amount of the copolymerizable surfactant is usually 0.01 to 5.0 parts by weight, preferably 0.05 to 100 parts by weight of all monomers used for the synthesis of the alkali-soluble copolymer. -5.0 weight part, More preferably, it is 0.1-3.0 weight part. If it is less than 0.01 part by weight, the emulsion stability becomes low, and a large amount of aggregates may be generated during the polymerization. On the other hand, when the amount exceeds 5.0 parts by weight, the problem that the pH-adjusting resin composition tends to foam may occur. In the polymerization of the alkali-soluble copolymer, it is preferable not to use a non-polymerizable surfactant. However, when a non-polymerizable surfactant is used in combination, the amount of the non-polymerizable surfactant is the amount of the alkali-soluble copolymer. The amount is usually less than 0.05 parts by weight with respect to 100 parts by weight of all monomers used for the synthesis of the polymer. When the amount of the non-polymerizable surfactant is increased, the obtained image tends to be inferior in water resistance.

  The polymerization initiator that can be used for the production of the alkali-soluble copolymer is not particularly limited. Specific examples include inorganic peroxides such as sodium persulfate, potassium persulfate, ammonium persulfate, potassium perphosphate, and hydrogen peroxide; diisopropylbenzene hydroperoxide, cumene hydroperoxide, t-butyl hydroperoxide, 1 , 1,3,3-tetramethylbutyl hydroperoxide, di-t-butyl peroxide, isobutyryl peroxide, benzoyl peroxide, and the like; azobisisobutyronitrile, azobis-2,4- Examples include azo compounds such as dimethylvaleronitrile and methyl azobisisobutyrate. These polymerization initiators can be used alone or in combination of two or more. Of these, persulfates such as potassium persulfate and ammonium persulfate are preferable.

The amount of the polymerization initiator used varies depending on the type, but is preferably 0.5 to 5 parts by weight with respect to 100 parts by weight of the total monomer mixture used in the production of the aqueous dispersion of the alkali-soluble copolymer. More preferably, it is 0.8-4 weight part.
Moreover, these polymerization initiators can also be used as a redox polymerization initiator in combination with a reducing agent.
The reducing agent of the redox polymerization initiator is not particularly limited. Specific examples thereof include compounds containing metal ions in a reduced state such as ferrous sulfate and cuprous naphthenate; sulfones such as sodium methanesulfonate. Acid compounds; amine compounds such as dimethylaniline; and the like.
These reducing agents can be used alone or in combination of two or more.
Although the usage-amount of a reducing agent changes with reducing agents, it is preferable that it is 0.03-10 weight part with respect to 1 weight part of polymerization initiators.

  In order to adjust the weight average molecular weight of the alkali-soluble copolymer, a chain transfer agent can be used at the time of polymerization, if necessary. Examples of chain transfer agents include mercaptans such as t-dodecyl mercaptan and n-dodecyl mercaptan; α-methylstyrene dimer; sulfides such as dimethylxanthogen disulfide and diisopropylxanthogen disulfide; 2-methyl-3-butynenitrile, 3- Nitrile compounds such as pentenenitrile; thioglycolic acid esters such as methyl thioglycolate, propyl thioglycolate, and octyl thioglycolate; β-mercaptopropionic acid esters such as methyl β-mercaptopropionate and octyl β-mercaptopropionate; These can be used alone or in combination of two or more. Of these chain transfer agents, thioglycolate is preferable, and octyl thioglycolate is more preferable.

When a chain transfer agent is used, the addition amount is usually 0.1 to 5 parts by weight, preferably 0.5 to 4 parts per 100 parts by weight of the monomer used for the production of the alkali-soluble copolymer. Parts by weight. When the amount of the chain transfer agent used is too small, the viscosity after neutralization becomes high and handling may be difficult, and when too large, the molecular weight may be remarkably lowered. The method for adding the chain transfer agent is not particularly limited, and the whole amount may be added all at once, or may be added to the polymerization system intermittently or continuously in small amounts.
The polymerization temperature when producing the alkali-soluble copolymer is usually 0 to 100 ° C, preferably 30 to 90 ° C. The polymerization conversion is usually 90% by weight or more, preferably 95% by weight or more.

The neutralization degree in the neutralized product of the alkali-soluble copolymer used in the present invention (the molar equivalent of the inorganic base relative to the molar equivalent of the ethylenically unsaturated carboxylic acid monomer) is not particularly limited, but the neutralization degree is usually 70% or more, preferably 95% or more.
The inorganic base used to neutralize the alkali-soluble copolymer is not particularly limited, and examples thereof include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide; calcium hydroxide and magnesium hydroxide. Examples thereof include hydroxides of alkaline earth metals such as these, and these can be used alone or in combination of two or more. Of these inorganic bases, sodium hydroxide is preferred. Ammonia may be used as the inorganic base, but it may cause a decrease in ink aging stability (for example, pH reduction) and ejection stability.

Among the above-mentioned alkali-soluble copolymers used in the present invention, those obtained by polymerization in the presence of an alcoholic hydroxyl group-containing water-soluble polymer compound can be obtained when the pH-adjusted resin composition is stored for a long time. It is preferable in that it hardly changes in viscosity and is excellent in its dot reproducibility.
The weight average molecular weight of the pH adjusting resin used in the present invention is not particularly limited, but if it is too large (for example, more than 50,000), the viscosity of the pH adjusting resin emulsion becomes high and the handling thereof is difficult. It can be difficult. On the other hand, if it is too low (for example, less than 8,000), the abrasion resistance may deteriorate. The weight average molecular weight of the pH adjusting resin is, for example, preferably 8,000 or more, more preferably 9,000 to 100,000, and still more preferably 10,000 to 50,000.
The glass transition temperature of the pH adjusting resin used in the present invention can be arbitrarily set, but is preferably 5 to 50 ° C., more preferably 20 to 40 ° C. When the glass transition temperature of the pH adjusting resin is within this range, an image excellent in bending resistance and blocking resistance can be obtained. In addition, even if the glass transition temperature of the pH adjusting resin used in the present invention is somewhat high, the film forming temperature of the ink composition of the present invention is generally kept low.

  The solid content concentration of the pH adjusting resin used in the black ink composition for preventing golden gloss of the present invention can be 10% by weight or less, preferably 0.5 to 8%, based on the total weight of the black ink composition. The resin emulsion is usually used in the form of an aqueous emulsion.

  When the ink set of the present invention contains a black ink composition for preventing phase shift, the solid content concentration of the pH adjusting resin used in the black ink composition for preventing phase shift is based on the total weight of the black ink composition. The content of the resin emulsion is usually 0.1 to 8% by weight, more preferably 0.1 to 8% by weight, and more preferably 0.3 to 5% by weight. Usually, the resin emulsion is used in the state of an aqueous emulsion.

The pH-adjusting resin emulsion used in the present invention preferably has a pH of 8 to 11, and more preferably has a pH of 9 to 11. If the pH is less than 8, there may be a problem in ejection stability, and if it exceeds 11, there may be a problem in dispersion stability.
The amount of the alkali-soluble copolymer used in the pH-adjusting resin used in the present invention is preferably 2 to 200 parts by weight, more preferably 5 to 150 parts by weight, particularly preferably 10 to 100 parts by weight of the colorant. ~ 100 parts by weight.

As described above, the black ink composition for preventing golden gloss and the black ink composition for preventing phase shift (when the ink set of the present invention includes the black ink composition for preventing phase shift) of the present invention includes the fine particle emulsion described above. As such, a polyalkylene emulsion can be used.
In the black ink composition for preventing golden gloss and the black ink composition for preventing phase shift of the present invention (when included in the ink set of the present invention), the solid content of the polyalkylene emulsion is determined as follows. It can be 10% by weight or less, preferably 0.5 to 8% by weight, more preferably 1 to 5% by weight.
The black ink composition for preventing golden gloss and the black ink composition for preventing phase shift (when included in the ink set of the present invention) of the present invention are preferably an emulsion containing the pH adjusting resin as a resin component and / or the aforementioned It contains a polyalkylene type emulsion, more preferably both an emulsion containing the pH adjusting resin as a resin component and the polyalkylene type emulsion. The total content of the pH adjusting resin and the solid content of the polyalkylene type emulsion is preferably 0.5% by weight to 20% by weight with respect to the total weight of the black ink composition.

  Further, the black ink composition for preventing golden gloss and the black ink composition for preventing phase shift (when included in the ink set of the present invention) of the present invention may contain other resin components depending on circumstances. The other resin component means a resin component usually used in the production of a black ink composition. For example, a resin-based dispersant such as polyvinyl alcohols, polyvinyl pyrrolidones, polyacrylic acid, acrylic acid-acrylonitrile copolymer. Polymers, acrylic resins such as potassium acrylate-acrylonitrile copolymer, vinyl acetate-acrylic acid ester copolymer, acrylic acid-acrylic acid ester copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid Styrene-acrylic such as copolymer, styrene-methacrylic acid-acrylic acid ester copolymer, styrene-α-methylstyrene-acrylic acid copolymer, styrene-α-methylstyrene-acrylic acid-acrylic acid ester copolymer Resin, styrene-maleic acid copolymer, styrene-maleic anhydride Rain acid copolymer, vinyl naphthalene-acrylic acid copolymer, vinyl naphthalene-maleic acid copolymer, vinyl acetate-ethylene copolymer, vinyl acetate-fatty acid vinyl ethylene copolymer, vinyl acetate-maleic acid ester copolymer Polymers, vinyl acetate copolymers such as vinyl acetate-crotonic acid copolymer, vinyl acetate-acrylic acid copolymer and their salts, and resin surfactants such as polyoxyethylene alkyl ether, polyoxy Examples thereof include ethylene alkyl esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl amines, polyoxyethylene alkyl amides, and the like.

  Carbon black used in the black ink composition for preventing golden gloss and the black ink composition for preventing phase shift (when included in the ink set of the present invention) of the present invention includes, in addition to titanium oxide and iron oxide, a contact method, Carbon black produced by a known method such as a furnace method or a thermal method can be used. Specifically, as carbon black, No. manufactured by Mitsubishi Chemical Corporation. 2300, no. 900, HCF88, No. 33, no. 40, no. 45, no. 52, MA7, MA8, MA100, No2200B, etc. are Raven5750, Raven5250, Raven5000, Raven3500, Raven1255, Raven700, etc. manufactured by Colombia, Regal400R, Regal330R, Regal660R, onchalM900 , Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400, etc. are available from Degussa Color Black FW1, Color Black FW2, Color Black FW18, Color Black FW18, Color Black FW200, Col. S150, Color Black S160, Color Black S170, Printex 35, Printex U, Printex V, Printex 140U, Special Black 6, Special Black 5, Special Black 5A, Special Black 4S, etc. Absent.

  In the present invention, carbon black whose surface is oxidized can be used together with the pH adjusting resin. In this case, it is not necessary to use the above dispersant. The oxidation treatment can be performed by a known method. By the oxidation treatment, hydrophilic groups such as a carbonyl group, a carboxyl group, a hydroxyl group, and a sulfone group can be introduced on the surface of the carbon black.

The particle size of the carbon black is not particularly limited, but is preferably 10 μm or less, more preferably 0.1 μm or less.
In the ink set according to the present invention, the carbon black contained in each black ink composition may be the same or different.

In the black ink composition for preventing golden gloss of the present invention, the carbon black content is an amount that can be used for recording in the GG generation region, and specifically, 0% relative to the total weight of the black ink composition. Less than 4% by weight, in particular from 0.01% to less than 0.4% by weight, preferably from 0.05% to 0.3% by weight, more preferably from 0.1% to 0.25%. % By weight.
Further, when the ink set of the present invention includes a black ink composition for preventing phase shift, the carbon black content in the black ink composition for preventing phase shift can be used for recording a phase shift occurrence region. In particular, the amount is 0.4 wt% to 1.5 wt%, more preferably 0.5 wt% to 1.2 wt%, particularly 0 wt%, based on the total weight of the black ink composition. .6 wt% to 1.0 wt%.

  In addition, the black ink composition for preventing golden gloss and the black ink composition for preventing phase shift (when included in the ink set of the present invention) of the present invention have a color characteristic inherent to carbon black ( A colorant for complementary color for achromatic coloring of reddishness in a deep color part or in particular yellowishness in a light color part can also be contained. The complementary colorant means a colorant to be contained in the black ink composition in order to reduce or eliminate the band color generated in the recorded image by the black ink and obtain an achromatic image. Pigment Blue 60 (C.I.PB60), Color Index / Pigment Blue 15: 3, and Color Index / Pigment Blue 15: 4.

  The pigment blue 60 is preferably used in a black ink composition having a carbon black content of 0.01 to 1% by weight, and the content thereof is not particularly limited. The amount is preferably 0.01 to 0.5% by weight based on the total weight. The pigment blue 15: 3 and the pigment blue 15: 4 are preferably used in a black ink composition having a carbon black content of 1 to 10% by weight, and the content thereof is not particularly limited, For example, the amount is preferably 0.1 to 5 weights with respect to the total weight of the black ink composition.

  The black ink composition for preventing golden gloss of the present invention is a black ink composition having a low carbon black content, contains a fine particle emulsion (for example, pH adjusting resin and / or polyalkylene type emulsion), and particularly Except for containing an excessive amount of fine particle emulsion, can be prepared as a water-based ink containing the same components as those of a conventionally known black ink composition. Moreover, it can utilize as conventionally well-known various inks for recording methods, Preferably it can utilize as ink for inkjet recording.

  Further, when the ink set of the present invention contains a black ink composition for preventing phase shift, the black ink composition for preventing phase shift is a black ink composition for intermediate gradation, a fine particle emulsion (for example, pH adjustment). Resin and / or polyalkylene type emulsion) and, in particular, except for containing an excessive amount of the fine particle emulsion, it contains the same compounding components as the conventionally known black ink composition. It can be prepared as a water-based ink. Moreover, it can utilize as conventionally well-known various inks for recording methods, Preferably it can utilize as ink for inkjet recording.

  In the following, the ink set of the present invention is for inkjet recording, and the black ink composition for preventing golden gloss of the present invention and each ink composition contained in the ink set (particularly, included in the ink set of the present invention). The case where the black ink composition for preventing phase shift) is a water-based ink composition will be briefly described.

  In the black ink composition for preventing golden gloss of the present invention and / or the black ink composition in the ink set (particularly, the black ink composition for preventing phase shift that may be contained in the ink set of the present invention), carbon Black is preferably added to the ink composition, for example, as a pigment dispersion dispersed in an aqueous medium with a dispersant. As the dispersant used for preparing the pigment dispersion, a dispersant generally used for preparing the pigment dispersion, for example, a polymer dispersant or a surfactant can be used.

  The amount of the dispersant contained in the black ink composition for preventing golden gloss and / or the ink composition in the ink set of the present invention (particularly, the black ink composition for preventing phase shift) is not particularly limited. However, it is preferably in the range of 0.01 to 10% by weight, more preferably 0.1 to 5% by weight. When the content of the dispersant is less than 0.01% by weight, a sufficient surface-active effect cannot be obtained. When the content exceeds 10% by weight, ejection failure due to crystal precipitation, liquid crystal formation, or pigment stability decrease is caused. In some cases,

As the dispersant, besides a conventional surfactant, a dispersant commonly used for preparing a pigment dispersion, for example, a polymer dispersant can be suitably used. It will be apparent to those skilled in the art that the dispersant contained in the pigment dispersion will also function as a dispersant and a surfactant for the black ink composition.
As a more preferable dispersant, a polymer dispersant, particularly a resin dispersant can be used.
Preferred examples of the polymer dispersant include natural polymers. Specific examples thereof include proteins such as glue, gelatin, gazein, or albumin, natural gums such as gum arabic or tragacanth, glucosides such as saponin, alginic acid, or propylene glycol alginate, triethanolamine alginate, or Examples thereof include alginic acid derivatives such as ammonium alginate, cellulose derivatives such as methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, and ethylhydroxycellulose.

A preferred example of the polymer dispersant is a synthetic polymer. Specific examples thereof include polyvinyl alcohols, polyvinyl pyrrolidones, polyacrylic acid, acrylic acid-acrylonitrile copolymer, acrylate-acrylonitrile copolymer, vinyl acetate-acrylic ester copolymer, or acrylic acid. -Acrylic resin such as acrylic ester copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid-acrylic ester copolymer, styrene-α-methylstyrene-acrylic acid Copolymers or styrene-acrylic resins such as styrene-α-methylstyrene-acrylic acid-acrylic acid ester copolymers, styrene-maleic acid copolymers, styrene-maleic anhydride copolymers, isobutylene-maleic acid resins , Rosin-modified maleic resin, vinyl naphthalene -Acrylic acid copolymer, vinyl naphthalene-maleic acid copolymer, or vinyl acetate-ethylene copolymer, vinyl acetate-fatty acid vinyl ethylene copolymer, vinyl acetate-maleic acid ester copolymer, vinyl acetate-croton Mention may be made of acid copolymers or vinyl acetate copolymers such as vinyl acetate-acrylic acid copolymers and their salts.
Among these, a styrene-acrylic acid copolymer, a styrene-methacrylic acid copolymer, an acrylic acid-acrylic acid ester copolymer, and a styrene-maleic anhydride copolymer are preferable as the dispersant.

  Moreover, as a resin dispersing agent, a commercially available thing can be used, As the specific example, Johnson polymer company make, Jonkrill 68 (molecular weight 10000, acid value 195), Jonkrill 61J (molecular weight 10000, acid) 195), joncryl 680 (molecular weight 3900, acid value 215), joncryl 682 (molecular weight 1600, acid value 235), joncryl 550 (molecular weight 7500, acid value 200), joncryl 555 (molecular weight 5000, acid value 200) ), Joncryl 586 (molecular weight 3100, acid value 105), Joncryl 683 (molecular weight 7300, acid value 150), Joncryl B-36 (molecular weight 6800, acid value 250), and the like.

  The black ink composition for preventing golden gloss and / or the ink composition in the ink set of the present invention (particularly, the black ink composition for preventing phase shift) may contain a surfactant. Specific examples of the surfactant include an anionic surfactant (for example, sodium dodecylbenzenesulfonate, sodium laurate, or ammonium salt of polyoxyethylene alkyl ether sulfate), a nonionic surfactant (for example, polyoxyethylene). Ethylene alkyl ether, polyoxyethylene alkyl ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylphenyl ether, polyoxyethylene alkylamine, or polyoxyethylene alkylamide), amphoteric surfactants (for example, N, N- Dimethyl-N-alkyl-N-carboxymethylammonium betaine, N, N-dialkylaminoalkylenecarboxylate, N, N, N-trialkyl-N-sulfoalkyleneammonium In, N, N-dialkyl-N, N-bispolyoxyethyleneammonium sulfate betaine, or 2-alkyl-1-carboxymethyl-1-hydroxyethylimidazolinium betaine). Or two or more types can be used in combination.

〔式中、０≦ｍ＋ｎ≦５０であり、Ｒ¹、Ｒ²、Ｒ³、及びＲ⁴はそれぞれ独立してアルキル基、好ましくは炭素数６以下のアルキル基である〕で表わされる化合物を挙げることができる。 The black ink composition for preventing golden gloss and / or the ink composition in the ink set of the present invention (particularly, the black ink composition for preventing phase shift) preferably contains an acetylene glycol surfactant. By this addition, the penetrability of the black ink composition into the recording medium can be improved, and recording with less bleeding can be expected on various recording media. Preferable specific examples of the acetylene glycol surfactant used in the black ink composition used in the present invention include the general formula (1):

[Wherein, 0 ≦ m + n ≦ 50, and R ¹ , R ² , R ³ , and R ⁴ are each independently an alkyl group, preferably an alkyl group having 6 or less carbon atoms]. be able to.

  Among the compounds represented by the general formula (1), 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3 is particularly preferable. , 6-diol, 3,5-dimethyl-1-hexyne-3ol, and the like. Commercially available products can also be used as the acetylene glycol surfactant represented by the general formula (1), and specific examples thereof include Surfynol 104, 82, 465, 485, or TG (all are Air Products). and Olfin STG, Olfin E1010 (all are trade names manufactured by Nissin Chemical Co., Ltd.).

（式中、Ｒ¹¹〜Ｒ¹⁷は、独立して、Ｃ_1-6アルキル基を表し、ｊ及びｋは、独立して、１以上の整数を表し、ＥＯはエチレンオキシ基を表し、ＰＯはプロピレンオキシ基を表し、ｓ及びｔは０以上の整数を表すが、但しｓ＋ｔは１以上の整数を表し、ＥＯ及びＰＯは、［ ］内においてその順序は問わず、ランダムであってもブロックであってもよい）で表されるシリコーン系界面活性剤を含むのが好ましい。この添加によってブラックインク組成物の記録媒体への浸透性を向上することができる。 The black ink composition for preventing golden gloss and / or the ink composition in the ink set of the present invention (in particular, the black ink composition for preventing phase shift) has the general formula (2):

Wherein R ^{11 to} R ¹⁷ independently represent a C _1-6 alkyl group, j and k independently represent an integer of 1 or more, EO represents an ethyleneoxy group, and PO represents Represents a propyleneoxy group, s and t represent an integer of 0 or more, provided that s + t represents an integer of 1 or more, and EO and PO are in any order within [], even if they are random. It may be preferable to include a silicone surfactant represented by This addition can improve the penetrability of the black ink composition into the recording medium.

A preferable compound in the silicone surfactant represented by the general formula (2) is that in the general formula (2), R ^{11 to} R ¹⁷ are independently a C _1-6 alkyl group, more preferably methyl. J and k are independently an integer of 1 or more, more preferably 1 to 2, and s and t represent an integer of 0 or more, provided that s + t is an integer of 1 or more, more preferably s + t is a compound of 2-4.

A particularly preferable compound in the silicone surfactant represented by the general formula (2) is a compound in which j and k are the same number in the formula (2), and 1 to 3, particularly 1 or 2. In the more preferable compound represented by the general formula (2), R ^{11 to} R ¹⁷ all represent a methyl group, j represents 1, k represents 1, u represents 1, and s represents It is a compound that represents an integer of 1 or more, particularly an integer of 1 to 5, and t represents 0.

  The amount of the silicone surfactant represented by the general formula (2) may be appropriately determined, but is preferably 0.03 to 3% by weight based on the total weight of the black ink composition used in the present invention. More preferably, it is about 0.1 to 2 weight%, More preferably, it is about 0.3 to 1 weight%.

  The silicone-based surfactant represented by the general formula (2) is commercially available and can be used. For example, a silicone surfactant BYK-347 or BYK-348 commercially available from Big Chemie Japan Co., Ltd. can be used.

  The amount of the surfactant contained in the black ink composition for preventing golden gloss and / or the ink composition in the ink set of the present invention (particularly, the black ink composition for preventing phase shift) is not particularly limited. However, it is preferably in the range of 0.01 to 10% by weight, more preferably 0.1 to 5% by weight. When the surfactant content is less than 0.01% by weight, a sufficient surfactant effect cannot be obtained. When the surfactant content exceeds 10% by weight, ejection failure due to crystal precipitation, liquid crystal formation, or pigment stability decrease is caused. Cases that cause it are recognized.

Further, the black ink composition for preventing golden gloss and / or the ink composition in the ink set of the present invention (in particular, the black ink composition for preventing phase shift) is a wetting agent, a drying speed adjusting agent, and / or a stable agent. As the agent, a water-soluble organic solvent can be contained. The content of the water-soluble organic solvent added to each black ink composition is preferably about 0.5 to 40% by weight, more preferably 2 to 30% by weight, based on the total weight of the black ink composition. It is.
As the water-soluble organic solvent, a water-soluble organic solvent blended in an ordinary aqueous pigment ink composition can be used. Specifically, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol Polyhydric alcohols such as polypropylene glycol, propylene glycol, dipropylene glycol, butylene glycol, 1,2,6-hexanetriol, thioglycol, hexylene glycol, glycerin, trimethylolethane, or trimethylolpropane; ethylene glycol mono Ethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl Alkyl ethers of polyhydric alcohols such as ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, or triethylene glycol monobutyl ether; or 2-pyrrolidone, N-methyl-2-pyrrolidone, 1,3- Mention may be made of dimethyl-2-imidazolidinone or triethanolamine.

  In addition, the black ink composition for preventing golden gloss and / or the ink composition in the ink set of the present invention (in particular, the black ink composition for preventing phase shift that may be contained in the ink set of the present invention) is antiseptic. It is preferable to further contain an agent, a metal ion scavenger, and / or a rust inhibitor. Here, the preservative is preferably one or more compounds selected from the group consisting of alkylisothiazolones, chloroalkylisothiazolones, benzisothiazolones, bromonitroalcohols, oxazolidine compounds, and chloroxylenol, and the metal ion scavenger is ethylenediamine. Tetraacetate is preferable, and dicyclohexylammonium nitrate and / or benzotriazole is preferably used as the rust inhibitor.

In addition, the black ink composition for preventing golden gloss and / or the ink composition in the ink set of the present invention (in particular, the black ink composition for preventing phase shift) ensures storage stability, prevents clogging, and discharge stability. For the purpose of ensuring stability and leaving stability, wetting agents, moisturizing agents, dissolution aids, penetration control agents, viscosity modifiers, pH modifiers, dissolution aids, antioxidants, antifungal agents, corrosion inhibitors, Various other additives can be added.
In addition, the number of carbons such as ethanol, methanol, butanol, propanol, or isopropanol as a component that improves the solubility of the ink component, further improves the permeability to a recording medium such as paper, or prevents nozzle clogging. Examples thereof include 1 to 4 alkyl alcohols, formamide, acetamide, dimethyl sulfoxide, sorbite, sorbitan, acetin, diacetin, triacetin, sulfolane and the like, which can be appropriately selected and used.

In addition, pH adjusters, amines such as diethanolamine, triethanolamine, propanolamine, morpholine and their modified products, inorganic hydroxides such as potassium hydroxide, sodium hydroxide, lithium hydroxide, ammonium hydroxide, quaternary Examples thereof include ammonium salts (such as tetramethylammonium), carbonates such as potassium carbonate, sodium carbonate, and lithium carbonate, and phosphates.
Other additives include ureas such as urea, thiourea and tetramethylurea, allophanates such as allophanate and methylallohanate, biurets such as biuret, dimethylbiuret and tetramethylbiuret, and L-ascorbic acid and its salts Commercially available antioxidants, ultraviolet absorbers and the like can also be used.

Further, the golden gloss preventing black ink composition and / or the ink composition in the ink set of the present invention (particularly, the black ink composition for preventing phase shift) preferably has a surface tension of 45 mN / m or less. More preferably, it is the range of 25-45 mN / m. When the surface tension exceeds 45 mN / m, the drying property of the printing is deteriorated, bleeding is likely to occur, and color bleeding is generated, so that it is difficult to obtain a good recorded image. Also, when the surface tension is less than 25 mN / m, the periphery of the nozzles of the printer head is likely to get wet, so that problems such as a flying curve of ink droplets are likely to occur. The surface tension can be measured by a commonly used surface tension meter.
The surface tension of the ink can be set within the above range by adjusting the type and composition ratio of each component constituting the ink.
The black ink composition for preventing golden gloss contained in the ink set for inkjet recording of the present invention and the ink composition in the ink set (particularly, the black ink composition for preventing phase shift) can be prepared by ordinary methods. it can.
The ink set of the present invention can be a black-and-white monochrome recording ink set or a color recording ink set.

Furthermore, the black ink composition for preventing golden gloss and / or the ink composition in the ink set of the present invention (particularly, the black ink composition for preventing phase shift) may contain a tertiary amine as a pH adjuster. preferable.
The tertiary amine that can be added to the black ink composition for preventing golden gloss and / or the ink composition in the ink set of the present invention (in particular, the black ink composition for preventing phase shift) includes trimethylamine, triethylamine, Examples include ethanolamine, dimethylethanolamine, diethylethanolamine, triisopropenolamine, and butyldiethanolamine. These may be used alone or in combination. The addition amount of these tertiary amines to the black ink composition for preventing golden gloss of the present invention and / or the ink composition in the ink set (in particular, the black ink composition for preventing phase shift) is 0.1 to 10 % By weight, more preferably 0.5 to 5% by weight.

Further, the black ink composition for preventing golden gloss and / or the ink composition in the ink set of the present invention (in particular, the black ink composition for preventing phase shift) has a penetration enhancer, sugar, and / or alginic acid derivative. Can also be included.
Examples of the penetration enhancer include alkyl ether derivatives of polyhydric alcohols having 3 or more carbon atoms, such as diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, propylene glycol monobutyl ether, or dipropylene glycol monobutyl ether. 1 type, or 2 or more types of these can be used.
Examples of sugars include monosaccharides, disaccharides, oligosaccharides (including trisaccharides and tetrasaccharides) and polysaccharides, preferably glucose, mannose, fructose, ribose, xylose, arabinose, galactose, aldonic acid. , Glucitol, (sorbitol), maltose, cellobiose, lactose, sucrose, trehalose, maltotriose, and the like. Here, the polysaccharide means a saccharide in a broad sense, and is used to include a substance that exists widely in nature, such as alginic acid, α-cyclodextrin, and cellulose. In addition, the derivatives of these saccharides include reducing sugars of the saccharides described above (for example, sugar alcohol (general formula HOCH ₂ (CHOH) _n CH ₂ OH (where n represents an integer of 2 to 5)). ), Oxidized sugars (for example, aldonic acid, uronic acid, etc.), amino acids, thio sugars, etc. Particularly preferred are sugar alcohols, and specific examples include maltitol, sorbit, etc. Moreover, HS-500 or HS-300 (manufactured by Hayashibara Biochemical Laboratories) etc. can be used as a commercial product, and the addition amount of these sugars is preferably about 0.1 to 40% by weight, more preferably 1 to 30% by weight. %.

Preferable examples of the alginic acid derivative include alginic acid alkali metal salts (for example, sodium salt and potassium salt), alginic acid organic salts (for example, triethanolamine salt), and alginic acid ammonium salt. The amount of the alginic acid derivative added to the black ink composition is preferably about 0.01 to 1% by weight, more preferably about 0.05 to 0.5% by weight.
The reason why a good image can be obtained by adding an alginic acid derivative is not clear, but the polyvalent metal salt present in the reaction solution reacts with the alginic acid derivative in the black ink composition, and changes the dispersion state of the colorant. This is thought to be due to the accelerated fixing of the colorant to the recording medium.
In addition to the black ink composition for preventing golden gloss and / or the ink composition in the ink set of the present invention (particularly, the black ink composition for preventing phase shift), a preservative and a fungicidal agent may be used as necessary. And / or a phosphorus-based antioxidant or the like may be added.

  The black ink composition for preventing golden gloss and / or the ink composition in the ink set of the present invention (in particular, the black ink composition for preventing phase shift) can be prepared by a conventional method. It can be produced by dispersing and mixing the components in a suitable manner. Preferably, first, a pigment, a polymer dispersant, and ion exchange water are appropriately dispersed (for example, a ball mill, a sand mill, an attritor, a roll mill, an agitator mill, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a jet mill, an ang mill). Etc.) to prepare a uniform pigment dispersion. Next, the fine particle emulsion (especially pH-adjusted resin emulsion, polyalkylene type emulsion), ion-exchanged water, water-soluble organic solvent, preservative, and / or antifungal agent, etc. are sufficiently stirred at room temperature to prepare an ink solvent. To prepare. The pigment dispersion is gradually added dropwise to a state where the ink solvent is stirred by a suitable dispersing machine, and the ink solvent is sufficiently stirred. After sufficiently stirring, the target black ink composition can be obtained by performing filtration in order to remove coarse particles and foreign matters that cause clogging. In addition, the said polyalkylene type emulsion can use a commercially available thing. For example, AQ593, AQ513, or PEM-17 marketed by Big Chemie Japan can be used.

  The black ink composition for preventing golden gloss according to the present invention includes at least one black ink composition having a carbon black concentration higher than that of the black ink composition for preventing golden gloss, preferably 2 in addition to the black ink composition for preventing golden gloss. It can be used for an ink set containing more than one species. The present invention also relates to the ink set including the black ink composition for preventing golden gloss. The ink set of the present invention can be an ink set for monochrome recording or an ink set for color recording.

  The monochrome recording ink set of the present invention includes a black ink composition for preventing golden gloss and a black ink composition having a carbon black concentration higher than that of the black ink composition for preventing golden gloss. When the ink set for monochrome recording of the present invention comprises, for example, two types of black ink composition, it contains the black ink composition for preventing golden gloss and a black ink composition having a high density (normal carbon black concentration). Further, in the case of comprising three types of black ink compositions, the black ink composition for preventing golden gloss, the black ink composition for intermediate gradation (particularly, the black ink composition for intermediate gradation for preventing phase shift) and dark black Each of the black inks contains an ink composition and, optionally, each contains a suitable complementary colorant. Alternatively, the ink set for monochrome recording of the present invention includes, for example, the black ink composition for preventing golden gloss, at least one black ink composition having a carbon black concentration higher than that of the black ink composition for preventing golden gloss, and complementary colors. Can be printed, for example, a combination of light magenta and light cyan, a combination of light magenta, light cyan, and yellow.

  In addition, the type and number of the ink composition constituting the color recording ink set of the present invention is not particularly limited as long as it includes the golden gloss prevention black ink composition of the present invention as an ink set member, Typical ink sets according to the present invention include, for example, a five-color ink set consisting of a yellow ink composition, a cyan ink composition, a magenta ink composition, a golden ink for preventing golden gloss, and a dark black ink composition; 7-color ink set obtained by adding a light cyan ink composition and a light magenta ink composition to the 5-color ink set; an 8-color ink set obtained by adding a dark yellow ink composition to the 7-color ink set; Red ink composition, green ink composition, and blue ink composition are added to 8-color ink set; an 8-color ink set obtained by adding an orange ink composition, a green ink composition, and a blue ink composition to the 5-color ink set; and an orange ink composition, green An ink composition and an eight-color ink set to which a violet ink composition is added; and a black ink composition for intermediate gradation (in particular, a black ink composition for intermediate gradation for preventing phase shift) to each of the ink sets described above An ink set comprising:

  The “light magenta” and “light cyan” ink compositions are generally colorant concentrations of the magenta ink composition and the cyan ink composition, respectively, for the purpose of improving the image quality of the recorded image by density modulation. Is an ink composition having a reduced viscosity. The “dark yellow” ink composition is a yellow ink that uses a color material (pigment) having lightness and saturation lower than those of the yellow ink composition for the purpose of improving color reproducibility for dark colors such as shadow portions. It is a composition. In addition, each ink composition of “red”, “orange”, “green”, “blue”, and “violet” is used as an element constituting an intermediate color of yellow, magenta, and cyan in order to improve the color reproduction range. It is the ink composition used.

The ink set of the present invention is configured in the same manner as a conventionally known ink set except that it contains the black ink composition for preventing golden gloss of the present invention (and possibly the black ink composition for preventing phase shift). It can be used as various known inks for recording methods. A preferred ink set is water-based, and particularly an ink set for inkjet recording.
The recording method of the present invention is a recording method for performing recording by discharging a droplet of an ink composition and attaching the droplet to a recording medium, and uses the ink set of the present invention. Here, in the recording method, an ink cartridge containing the ink set of the present invention (an ink cartridge containing each black ink composition individually) is mounted on a known ink jet recording apparatus and recorded on a recording medium. By doing so, it can be suitably performed.
Here, as the ink jet recording apparatus, an electrostrictive element that can vibrate based on an electric signal is mounted, and the ink included in the ink set according to the present invention can be ejected by the vibration of the electrostrictive element. An ink jet recording apparatus constructed as described above is preferable.
Further, as the ink cartridge (accommodating case) for accommodating the ink set, a known cartridge can be suitably used.
Further, the recorded image of the present invention is recorded by the recording method of the present invention, and therefore, the occurrence of golden gloss is well suppressed. In addition, when an ink set including the black ink composition for preventing phase shift is used, both the occurrence of golden gloss and the occurrence of phase shift can be satisfactorily suppressed at the same time.

The black ink composition for preventing golden gloss of the present invention (and optionally the black ink composition for preventing phase shift) can be used in any recording method, for example, aqueous gravure ink, aqueous flexographic ink, or particularly inkjet. It can be suitably used as an aqueous recording ink. It can also be used as a water-based paint.
The black ink composition for preventing golden gloss (and optionally the black ink composition for preventing phase shift) of the present invention is used as a recording medium with the colorant (particularly, pigment) contained in the black ink composition and a fine particle emulsion [ In particular, the resin component of the pH adjusting resin and the polyalkylene type emulsion] is substantially left on the surface, but it is particularly preferable to use it for a recording medium that substantially absorbs the liquid component of the black ink composition. In such a recording medium, for example, the average pore diameter on the surface is smaller than the average particle diameter of the pigment. A preferable recording medium is a recording medium including an ink receiving layer having an average pore diameter smaller than the average particle diameter of the pigment.

As a preferred recording medium, a recording medium in which an ink receiving layer containing a porous pigment is provided on a substrate can be used. The ink receiving layer may be the uppermost layer of the recording medium, or may be an intermediate layer having, for example, a glossy layer thereon. As such a recording medium, a so-called absorption type (also referred to as a void type) recording medium containing a porous pigment and a binder resin in the ink receiving layer, and casein, modified polyvinyl alcohol (in the ink receiving layer) PVA), gelatin, or a so-called swelling type recording medium further containing a resin such as modified urethane is known, and the black ink composition for preventing golden gloss according to the present invention (and the black for preventing phase shift used in some cases). The ink composition can be used for any recording medium.
Examples of the porous pigment contained in the ink receiving layer of the absorption-type recording medium include silica-based such as precipitation method, gel type, or gas-phase method, alumina hydrate such as pseudoboehmite, and silica / alumina hybrid sol. , Smectite clay, calcium carbonate, calcium sulfate, barium sulfate, titanium dioxide, kaolin, clay, talc, magnesium silicate, calcium silicate, and the like, and one or more of these can be used.

  Further, the binder resin contained in the ink receiving layer of the absorption type recording medium is not particularly limited as long as it is a compound that has a binding ability and can increase the strength of the ink receiving layer. For example, polyvinyl alcohol Silanol-modified polyvinyl alcohol, cellulose derivatives such as vinyl acetate, starch, carboxymethyl cellulose, casein, gelatin, conjugated diene copolymer latex such as styrene-butadiene copolymer, vinyl copolymer such as ethylene-vinyl acetate copolymer, etc. An acrylic copolymer latex such as a polymer latex and a polymer of acrylic acid and methacrylic acid can be used.

The ink receiving layer may be a fixing agent, a fluorescent whitening agent, a water-proofing agent, a fungicide, if necessary, in the case of an ink receiving layer of an absorption type recording medium or an ink receiving layer of a swelling type recording medium. Various additives such as an agent, an antiseptic, a dispersant, a surfactant, a thickener, a pH adjuster, an antifoaming agent, and / or a water retention agent can also be contained.
Examples of the substrate on which each of the ink receiving layers is provided include paper (including sized paper); resin-coated paper obtained by coating polyethylene, polypropylene, or polyester on paper; baryta paper; polyethylene terephthalate, polyethylene, or polypropylene. And a thermoplastic resin film such as synthetic paper; a sheet-like material formed of synthetic fibers.

The recording medium of a particularly preferred embodiment is a recording medium having the base material and the ink receiving layer as the uppermost layer provided thereon, and the base material and the ink receiving layer also have the following physical properties, for example. What has is preferable.
The substrate is preferably paper (containing wood pulp), and the basis weight thereof is preferably 100 to 350 g / m ² , more preferably 180 to 260 g / m ² . The thickness is preferably 100 to 400 μm, more preferably 180 to 260 μm. The ink receiving layer contains 50-60% by weight of wet silica gel as the porous pigment in terms of solid content, based on the weight of the entire ink receiving layer, and 30-30% polyvinyl alcohol as the binder resin. A content of 40% by weight is preferred from the standpoints of ink absorptivity and printing fastness. The coating amount of the ink receiving layer is preferably 5 to 50 g / m ² in terms of solid content from the viewpoint of ink absorbability. The thickness of the ink receiving layer itself is preferably 10 to 40 μm, more preferably 20 to 30 μm.
The recording medium on which the black ink composition for preventing golden gloss (and optionally the black ink composition for preventing phase shift) of the present invention has an average pore diameter of 50 nm on the surface of the recording medium (particularly, the ink receiving layer). Or less, more preferably 30 nm or less. When the average pore diameter exceeds 300 nm, the pigment may penetrate into the ink receiving layer and color developability may deteriorate.

  The black ink composition for preventing golden gloss of the present invention is generally used as a thin black ink for printing a light gray region in combination with one or more dark black ink compositions having different concentrations as described above. Not only can it be used, it can also be used as a clear ink. Examples of the use as a clear ink include an application for reducing variation in the amount of resin component applied in a recorded image.

Hereinafter, the present invention will be described more specifically with reference to examples, but these do not limit the scope of the present invention. In the examples, “%” and “parts” are based on weight unless otherwise specified. Moreover, the acid value of the copolymer obtained by the following preparation examples was measured according to JIS K0070.
(Preparation Example 1)
<< Preparation of pH-adjusted resin emulsion A >>
Dispersion of monomer mixture by stirring and mixing 60 parts of ethyl methacrylate, 36 parts of methyl methacrylate, 4 parts of methacrylic acid, 3 parts of octyl thioglycolate as molecular weight regulator, 1 part of polyvinyl alcohol and 280 parts of ion-exchanged water A product was prepared.
In another reactor equipped with a stirrer, 130 parts of ion-exchanged water and 2 parts of potassium persulfate were charged, the temperature was raised to 80 ° C., and the dispersion of the monomer mixture was continuously added over 4 hours for polymerization. . After completion of the continuous addition, a post-reaction was performed at 80 ° C. for 30 minutes. The polymerization conversion rate was 99% or more.
Next, 10% aqueous sodium hydroxide solution in an amount corresponding to the charged methacrylic acid and an equimolar amount of sodium hydroxide was added to the reactor, followed by heat treatment at 80 ° C. for 1 hour, and then an appropriate amount of ion-exchanged water was added. In addition, a pH-adjusted resin emulsion A having a solid content concentration of 15% was obtained. The acid value of this pH-adjusted resin emulsion A was 30.

(Examples 1-4 and Comparative Examples 1-2)
(1) Preparation of Black Ink Composition Regarding the eight types of black ink compositions shown in Table 1 below, each compounding component was mixed, and glass beads (diameter = 1.7 mm; mixture) in a sand mill (manufactured by Yaskawa Seisakusho). And 1.5 times the amount (weight)] of the mixture were dispersed for 2 hours to obtain 8 types of black ink compositions. That is, one type of dark black ink composition K1, one type of black ink composition K2 for intermediate gradation, and six types of thin black ink compositions (Examples 1-4 and Comparative Examples 1-2) were obtained. . As the water-soluble resin shown in Table 1 below, a styrene-acrylic acid copolymer (molecular weight = 15000; acid value = 100) was used. AQ593 is a polypropylene type emulsion (manufactured by Big Chemie Japan Co., Ltd.), AQ513 is a polyethylene type emulsion (manufactured by Big Chemie Japan Co., Ltd.), and HS500 is a solvent mainly composed of sugar (Hayashibara Shoji). Surfynol 465 is an acetylene glycol surfactant, BYK348 is a silicone surfactant, and Proxel GXL is a preservative (manufactured by Avicia). In Table 1, the unit is% by weight, and each ink contains pure water in addition to 100% by weight as a whole.

前記表２に記載のライトシアンインク組成物、ライトマゼンタインク組成物及びイエローインク組成物としてはインクカートリッジ（商品名「ＭＣ５ＣＬ０１」；セイコーエプソン株式会社製）に充填されているそれぞれの色のインク組成物を抜き出して評価に用いた。
マゼンタインク室に充填した６種類の薄いブラックインク組成物毎に形成された６種類のインクセットに関して、専用記録媒体（ＭＣ写真用紙；セイコーエプソン株式会社製）にそれぞれ白から黒へのグレーの階調パターン（グレースケール）を、階調を区切らずに、無段階で出力した。出力は各インクの吐出量を分配して行った。 (2) Recording method Eight types of black ink compositions prepared in the preceding item (1) are used in a black ink chamber (dark black ink composition K1) and cyan ink in a dedicated cartridge of an ink jet printer (MC2000; manufactured by Seiko Epson Corporation). The chamber (black ink composition K2 for intermediate gradation) and the magenta ink chamber (six kinds of thin black ink compositions prepared in Examples 1 to 4 or Comparative Examples 1 to 2) were filled respectively. Similarly, a light cyan ink composition, a light magenta ink composition, and a yellow ink composition were filled in the ink chambers shown in Table 2, respectively.

The light cyan ink composition, light magenta ink composition, and yellow ink composition shown in Table 2 are ink compositions of respective colors filled in an ink cartridge (trade name “MC5CL01”; manufactured by Seiko Epson Corporation). Was extracted and used for evaluation.
For the six types of ink sets formed for each of the six types of thin black ink compositions filled in the magenta ink chamber, each of the dedicated recording media (MC photo paper; manufactured by Seiko Epson Corporation) has a gray level from white to black. The tone pattern (grayscale) was output steplessly without dividing the gradation. The output was performed by distributing the discharge amount of each ink.

(3) Confirmation evaluation of golden gloss Evaluation of golden gloss was performed by five observers. The recorded matter that was output was placed on a desk 1.5 m directly below the fluorescent lamp, which is room light, and an observer stood beside the desk. The observer observed the printed matter by moving the line of sight at various viewing angles from the right end to the left end of the printed matter so as not to interrupt the light from an upright state. The observation results are shown in Table 3 below. In the recorded matter in which the golden gloss is generated, when observed with a line of sight at a certain angle, in the black output color in the range around the gray level 140, the light of the fluorescent lamp is strongly reflected in the gold color. I can see it. In Table 3, the denominator indicates the number of all observers (5 persons), and the numerator indicates the number of persons who have confirmed the golden gloss.

(Examples 5-11 and Comparative Examples 3-4)
(1) Preparation of Black Ink Composition With respect to the 11 types of black ink compositions shown in Table 4 below, each compounding component was mixed and glass beads [diameter = 1.7 mm; mixture in a sand mill (manufactured by Yaskawa Seisakusho)] 11 times the amount (weight)] of the mixture was dispersed for 2 hours to obtain 11 types of black ink compositions. That is, one type of dark black ink composition K1, one type of thin black ink composition K3, and nine types of black ink compositions for intermediate gradation (Examples 5 to 11 and Comparative Examples 3 to 4) were obtained. . As a water-soluble resin described in Table 4 below, a styrene-acrylic acid copolymer (molecular weight = 15000; acid value = 100) was used. AQ593 is a polypropylene type emulsion (manufactured by Big Chemie Japan Co., Ltd.), AQ513 is a polyethylene type emulsion (manufactured by Big Chemie Japan Co., Ltd.), and Lacstar 3307B is a fine particle emulsion of a styrene-butadiene copolymer. , Lacstar 3307B and styrene-butadiene-methacrylic acid resin (MBS resin) are listed in the table as solid contents, HS500 is a solvent (Hayashibara Corporation) mainly composed of sugar, and Surfynol 465 is acetylene. It is a glycol-based surfactant, BYK348 is a silicone-based surfactant, and Proxel GXL is a preservative (manufactured by Avicia). In Table 4, the unit is% by weight, and each ink contains pure water with 100% by weight as a whole.

前記表５に記載のライトシアンインク組成物、ライトマゼンタインク組成物及びイエローインク組成物としてはインクカートリッジ（商品名「ＭＣ５ＣＬ０１」；セイコーエプソン株式会社製）に充填されているそれぞれの色のインク組成物を抜き出して評価に用いた。
シアンインク室に充填した９種類の中間階調用ブラックインク組成物毎に形成された９種類のインクセットに関して、専用記録媒体（ＭＣ写真用紙；セイコーエプソン株式会社製）にそれぞれ白から黒へのグレーの階調パターン（グレースケール）を、階調を区切らずに、無段階で出力した。出力は各インクの吐出量を分配して行った。 (2) Recording Method The eleven types of black ink compositions prepared in the preceding item (1) are used in a black ink chamber (dark black ink composition K1) and cyan ink in a dedicated cartridge of an ink jet printer (MC2000; manufactured by Seiko Epson Corporation). The chamber (9 types of black ink compositions for intermediate gradation prepared in Examples 5 to 11 or Comparative Examples 3 to 4) and the magenta ink chamber (thin black ink composition K3) were filled, respectively. Similarly, a light cyan ink composition, a light magenta ink composition, and a yellow ink composition were also filled in the ink chambers shown in Table 5, respectively.

The light cyan ink composition, light magenta ink composition, and yellow ink composition listed in Table 5 are ink compositions of respective colors filled in an ink cartridge (trade name “MC5CL01”; manufactured by Seiko Epson Corporation). Was extracted and used for evaluation.
For the nine types of ink sets formed for each of the nine types of black ink compositions for mid-tone filled in the cyan ink chamber, each of the dedicated recording media (MC photo paper; manufactured by Seiko Epson Corporation) has a gray color from white to black. The gradation pattern (grayscale) was output steplessly without dividing the gradation. The output was performed by distributing the discharge amount of each ink.

(3) Confirmation evaluation of phase shift Evaluation of the phase shift was performed by five observers. The recorded matter that was output was placed on a desk 1.5 m directly below the fluorescent lamp, which is room light, and an observer stood beside the desk. The observer observed the printed matter by moving the line of sight at various viewing angles from the right end to the left end of the printed matter so as not to interrupt the light from an upright state. The observation results are shown in Table 6 below. In a recorded matter in which a phase shift has occurred, when observed with a line of sight at a certain angle, the light from the fluorescent lamp is strongly reflected in white in the black output color in the gray level range of 40 to 60. , It looks like it was flipped. In Table 6, the denominator indicates the number of all observers (5 persons), and the numerator indicates the number of persons who have confirmed the phase shift.

(The invention's effect)
According to the black ink composition for preventing golden gloss of the present invention, the occurrence of golden gloss is satisfactorily eliminated or suppressed in a recorded image. According to the ink set containing the black ink composition for preventing golden gloss of the present invention, the occurrence of golden gloss can be satisfactorily eliminated or suppressed, and a good black-and-white monochrome image and gray scale can be obtained. Also in the ink set for use, it is possible to achieve high quality in the achromatic portion of the color image.
Further, when the ink set according to the present invention includes a black ink composition for preventing phase shift, occurrence of both golden gloss and phase shift is satisfactorily eliminated or suppressed, and a good black-and-white monochrome image or gray scale is obtained. In addition, even in the color recording ink set, it is possible to achieve higher quality of the achromatic portion of the color image.

Claims (19)

A black ink composition comprising (1) water, (2) carbon black, and (3) a fine particle emulsion,
(A) The carbon black content is less than 0.4 wt%,
(B) The black ink composition, wherein the solid content of the fine particle emulsion is at least 20 times the content of carbon black.   The black ink composition according to claim 1, wherein a content of the carbon black is 0.01% by weight or more.   As the fine particle emulsion, a polyalkylene type emulsion and / or an ethylenically unsaturated carboxylic acid monomer and other monomers copolymerizable therewith, an alcoholic hydroxyl group-containing water-soluble polymer compound or copolymerizable surface activity 3. The black ink according to claim 1, comprising an emulsion containing a copolymer having an acid value of 40 or less obtained by polymerization in the presence of an agent, the resin component of which is a pH-adjusted resin whose pH is adjusted with an inorganic base. Composition.   The black ink composition according to claim 3, wherein the inorganic base used for the preparation of the pH adjusting resin is an alkali metal hydroxide or an alkaline earth metal hydroxide.   The black ink composition according to claim 3 or 4, wherein the alcoholic hydroxyl group-containing water-soluble polymer compound used for the preparation of the pH adjusting resin is a vinyl alcohol polymer.   The ink composition according to any one of claims 3 to 5, wherein the ethylenically unsaturated carboxylic acid monomer used for the preparation of the pH adjusting resin is acrylic acid or methacrylic acid.   The monomer copolymerizable with the ethylenically unsaturated carboxylic acid monomer used for the preparation of the pH adjusting resin is an ethylenically unsaturated carboxylic acid ester monomer. The black ink composition according to item.   The black ink composition according to any one of claims 3 to 7, wherein the pH of the emulsion containing the pH adjusting resin as a resin component is 8 to 11.   The ink composition according to any one of claims 3 to 8, wherein the polyalkylene emulsion is a polyethylene emulsion or a polypropylene emulsion.   10. The total content of the pH adjusting resin and the polyalkylene type emulsion solid content is 0.5 wt% to 20 wt% with respect to the total weight of the black ink composition. The black ink composition according to item.   Furthermore, the black ink composition as described in any one of Claims 1-10 containing the coloring agent for complementary colors.   The black ink composition according to any one of claims 1 to 11, which is an ink composition for inkjet recording.   An ink set comprising the black ink composition according to any one of claims 1 to 12 and a dark black ink composition having a carbon black concentration higher than that of the black ink composition.   The black ink composition according to any one of claims 1 to 12, wherein the carbon black content is 0.4% by weight to 1.5% by weight with respect to the total weight of the black ink composition. The ink set according to claim 13, comprising a black ink composition, a dark black ink composition having a carbon black content of 1.5 wt% to 10 wt% based on the total weight of the black ink composition.   The black ink composition for intermediate gradation is a black ink composition having a carbon black content of 0.4 to 1% by weight and / or a black ink composition having a carbon black content of 1 to 1.5% by weight. The ink set described in 1.   The ink set according to claim 14 or 15, wherein the black ink composition for intermediate gradation contains a fine particle emulsion, and the solid content of the fine particle emulsion is at least twice the carbon black content.   As the fine particle emulsion, a polyalkylene type emulsion and / or an ethylenically unsaturated carboxylic acid monomer and other monomers copolymerizable therewith, an alcoholic hydroxyl group-containing water-soluble polymer compound or copolymerizable surface activity The ink set according to claim 16, comprising an emulsion comprising a copolymer having a acid value of 40 or less obtained by polymerization in the presence of an agent, the resin component of which is a pH-adjusted resin whose pH is adjusted with an inorganic base.   A recording method for performing recording by discharging droplets of an ink composition and attaching the droplets to a recording medium, wherein the ink set according to any one of claims 13 to 17 is used. Recording method.   A recorded matter recorded by the recording method according to claim 18.

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