JP2000178491A - Ink set for ink-jet recording and ink-jet recording - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ink set causing a discoloration of image hardly recognizable by human visual observation even if a discoloration in ink occurs with time, providing a color image having an apparently improved light resistance by combining plural inks selected so as to make difference in amount of discoloration ratio in the order of lightness of ink. SOLUTION: This set comprises two or more inks in which the amounts of discoloration ratios of the inks are successively decreased in the order of the ink having high lightness to the ink having low lightness. Preferably the objective set contains (A) a yellow ink, (B) a magenta ink and (C) a cyanic ink. For example, in a case in which the inks contained in the set comprise the component A, the component B and the component C in the order of higher lightness of the inks, the relation of discoloration ratio of the component A > discoloration ratio of the component B > discoloration ratio of the component C is provided. Pigment-based inks comprising pigments as colorants are preferable as the inks. The discoloration ratio is preferably adjusted by regulating the particle diameter of the pigment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink set for ink jet recording capable of realizing an image having excellent light fastness, and an ink jet recording method using the same.

[0002] When the background art color image over time fading may change significantly different from the image the initially obtained image. As one of the methods for making it difficult to recognize the temporal change of an image due to such fading, it is conventionally known to make the fading rates of the respective inks approximately equal. This is because it was considered that each ink faded to the same extent, so that the color image as a whole faded to the same extent, making it difficult to recognize the fading of the entire color image. On the other hand, a color material used for an ink for an ink jet printer generally requires many characteristics. For example, solubility or dispersibility in a solvent is required in order to prevent ejection stability and clogging from an inkjet recording head. In addition, it is required that the head member is not deteriorated, that the recording medium is fixed to the recording paper and that it is colored, and that safety is also required. Under such various restrictions, usable color materials are limited, and it is very difficult to further uniform the fading rates of the inks of the respective colors.

[0003]

SUMMARY OF THE INVENTION The inventors of the present invention have recently proposed a method of providing a difference in the magnitude of the fading rate in the order of the lightness of the ink, without uniformly adjusting the fading rate of each ink in the ink for an ink jet printer. It has been found that by using the combination, it is possible to make it difficult to recognize fading visually from human eyes. Furthermore, the present inventors have found that the above-mentioned advantages can be more effectively enjoyed by attaching ink to a recording medium in the order of decreasing color fading rate. The present invention is based on such findings.

[0004] An ink set for ink jet recording according to the present invention is an ink set comprising two or more inks, in which the magnitude of the fading rate of the ink is sequentially smaller in the order of high brightness to low ink. This is an ink set that has been set. Further, the ink jet recording method of the present invention is a recording method in which ink droplets are ejected and the droplets are attached to a recording medium to perform printing, and the ink of the ink set of the present invention is used as the ink. Including. A method according to a more preferred embodiment is a method in which the ink is deposited on a recording medium in ascending order of color fading rate.

[0005] Even if a color image formed by the ink set for ink jet recording according to the present invention fades with the passage of time, the fading is hardly recognized by human eyes. Therefore, there is obtained an advantage that the light fastness of the obtained image can be apparently improved. Such advantages are prominent in a recording method using an ink jet printer, which is a recording method in which ink particles are directly adhered to a recording material, and more prominent in an ink system in which facial medicine is dispersed.

[0006]

DETAILED DESCRIPTION OF THE INVENTION Ink set An ink set according to the present invention is a combination of two or more inks selected such that the magnitude of the fading rate of the ink decreases in order from the ink having the higher brightness to the ink having the lower brightness. Things. Therefore, for example, when the brightness is La and Lb, respectively.
A, B, and Lc (La>Lb> Lc)
In order to use these inks in combination with the ink set of the present invention when C and C are present, when the fading rates of those inks are Fa, Fb, and Fc, respectively, the fading rate is Fa>Fb> It is necessary to have a relationship of Fc.

It is preferable that the ink set according to the present invention includes at least a yellow ink, a magenta ink, and a cyan ink. The inks included in this ink set are arranged in descending order of brightness of the inks.
In the case of yellow ink, magenta ink, and cyan ink, the fading rate of yellow ink (Y), the fading rate of magenta ink (M), and the fading rate of cyan ink (C) have the following relationship: Y>M> C, that is, the yellow ink, the magenta ink, and the cyan ink need to be in descending order of the fading rate.

When the ink set according to the present invention further includes black ink, if the inks are yellow ink, magenta ink, cyan ink and black ink in descending order of lightness, fading of black ink The ratio (K), the fading ratio of yellow ink (Y), the fading ratio of magenta ink (M), and the fading ratio of cyan ink (C) satisfy the following relationship: Y>M>C> K is necessary.

Further, when the ink set according to the present invention further includes a light magenta ink and / or a light cyan ink in addition to the yellow ink, the magenta ink, and the cyan ink, the lightness of those inks is set in descending order. In the case of yellow ink, light magenta ink, light cyan ink, magenta ink, and cyan ink, the fading rate of yellow ink (Y), the fading rate of light magenta ink (Lm), and the fading rate of light cyan ink (Lc) , Magenta ink fading rate (M), and cyan ink fading rate (C) must satisfy the following relationship: Y>Lm>Lc>M> C.

When the ink set of the present invention further includes black inks, the inks are yellow ink, light magenta ink, light cyan ink, magenta ink, cyan ink, and black ink in order of decreasing brightness. In this case, the fading rate of black ink (K), the fading rate of yellow ink (Y), the fading rate of light magenta ink (Lm), the fading rate of light cyan ink (Lc), and the fading rate of magenta ink (M) ,
And the fading rate (C) of the cyan ink must satisfy the following relationship: Y>Lm>Lc>M>C> K.

The above "light magenta" means light magenta, and the above "light cyan" means light cyan. In the light magenta ink used in the present invention, for example, the content of the colorant (pigment or dye) used for preparing the magenta ink is reduced, or in the case of the pigment ink, the particle size of the pigment is reduced. It can be easily prepared by reducing the size. In the light cyan ink used in the present invention, the content of the colorant (pigment or dye) used for preparing the cyan ink is reduced by a conventional method, or the particle diameter of the pigment is reduced in the case of the pigment ink. Can be easily prepared.

Still further, the ink set according to the present invention comprises:
In addition to the above-mentioned yellow ink, magenta ink, and cyan ink, when the ink further contains orange ink and / or green ink, the yellow ink, orange ink, magenta ink, cyan ink, And for green ink, the fading rate of yellow ink (Y), the fading rate of orange ink (O), the fading rate of magenta ink (M), the fading rate of cyan ink (C), and the fading of green ink The rate (G) must be in the following relationship: Y>O>M>C> G.

In the case where the ink set of the present invention further includes black ink, the ink set includes yellow ink, orange ink, magenta ink, cyan ink, green ink, and black ink in descending order of brightness. Are the fading rate of black ink (K), the fading rate of yellow ink (Y), the fading rate of orange ink (O), the fading rate of magenta ink (M),
It is necessary that the fading rate (C) of the cyan ink and the fading rate (G) of the green ink satisfy the following relationship: Y>O>M>C>G> K.

In this specification, "brightness" means an L ^* a ^* b ^* display system L ^* value specified by the CIE.

Further, in this specification, the term "fading rate (F)" is used.
Is the formula (I): F (%) = (Di-De) / Di × 100 (I) (where Di is the reflection density measured at the beginning of printing, and D
e is the reflection density measured after the light fastness test). The reflection density of the ink can be measured by any conventional spectrophotometer, and the light fastness test can use any conventional test method. In the present invention, the fading rate of each ink can be adjusted by appropriately selecting the type of colorant (pigment or dye) to be used.

According to a preferred embodiment of the present invention, it is preferable to use a pigment-based ink using a pigment as a colorant. In the case of a pigment-based ink, the color fading rate of the ink can be adjusted by controlling the particle size of the pigment used.
That is, by decreasing the particle size of the pigment, the color fading rate of the ink containing the pigment can be increased. Therefore, the color fading rate can be adjusted by appropriately adjusting the particle size. In the present invention, the particle diameter of the pigment can be represented by using the cumulative average diameter as an index. The cumulative average diameter is a diameter at which the cumulative curve becomes 50% when the cumulative curve based on the particle size is determined with the total volume of the target powder aggregate being 100%. This cumulative average diameter is
Sometimes referred to as a center diameter or a media diameter, it is often used as an average particle diameter of a fine particle dispersion such as a pigment dispersion.

In the present invention, any colorant other than the above-mentioned fading rate, ie, an inorganic dye and / or an organic dye, or preferably an inorganic pigment and / or
Alternatively, an organic pigment can be used. As mentioned above, the use of pigments is preferred. As the inorganic pigment, in addition to titanium oxide and iron oxide, carbon black produced by a known method such as a contact method, a furnace method, or a thermal method can be used. Examples of the organic pigment include an azo pigment (including an azo lake, an insoluble azo pigment, a condensed azo pigment, and a chelated azo pigment), a polycyclic pigment (for example, a phthalocyanine pigment, a berylen pigment,
Verinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, or quinophthalone pigments), dye chelates (eg, basic dye chelates, acid dye chelates, etc.), nitro pigments, nitroso pigments, Aniline black or the like can be used.

According to a particularly preferred embodiment of the present invention, C.I. I. Pigment Yellow 74, 1
09, 110 and 138, and as a magenta pigment,
C. I. Pigment Red 122, 202, 209 and C.I. I. Pigment Blue 1
5: 3, 60 and C.I. I. Pigment Black 7 and C.I.
I. Pigment Orange 36 and 43, and C.I. I. Pigment Green 7 and 36 are used. In the present invention, among these pigments, it is preferable to use a pigment having good water affinity.

The average particle size of the pigment is preferably from 0.15 μm to 0.25 μm, and more preferably from 0.15 μm to 0.2 μm.

Hereinafter, the present invention will be described with reference to the case where a pigment ink is used, but the description also applies to a dye ink unless otherwise specified in the following description.

In the present invention, a pigment dispersion obtained by dispersing a pigment with a dispersant is preferably added to the ink. As a preferred dispersant, a known dispersant used for preparing a conventionally known pigment dispersion, for example, a polymer dispersant or a surfactant can be used.

Examples of the polymer dispersant include natural polymer compounds, for example, proteins such as glue, gelatin, casein and albumin; natural gums such as gum arabic and gum tragacanth; glucosides such as savonin; alginic acid and alginic acid Alginic acid derivatives such as propylene glycol ester, triethanolamine alginate, ammonium alginate; methylcellulose,
Examples include cellulose derivatives such as carboxymethylcellulose, hydroxyethylcellulose, and ethylhydroxyethylcellulose.

Further, a synthetic polymer compound can be used as the polymer dispersant. Examples of the synthetic polymer compound include polyvinyl alcohols; polyvinylpyrrolidones; polyacrylic acid, acrylic acid-acrylonitrile copolymer, potassium acrylate-acrylonitrile copolymer, vinyl acetate-acrylic ester copolymer,
Acrylic resin such as acrylic acid-alkyl acrylate copolymer; styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid alkyl acrylate copolymer, styrene-α
-Methylstyrene-acrylic acid copolymer, styrene-α
Styrene-acrylic acid resin such as methylstyrene-acrylic acid-alkyl acrylate copolymer; styrene-maleic acid; styrene-maleic anhydride; vinylnaphthalene-acrylic acid copolymer; vinylnaphthalene-
Maleic acid copolymer; vinyl acetate-ethylene copolymer,
Vinyl acetate-based copolymers such as vinyl acetate-fatty acid vinyl ethylene copolymer, vinyl acetate maleate copolymer, vinyl acetate crotonic acid copolymer, and vinyl acetate acrylic acid copolymer, and salts thereof. it can. Among these, a copolymer of a monomer having a hydrophobic group and a monomer having a hydrophilic group, and a polymer composed of a monomer having both a hydrophobic group and a hydrophilic group are particularly preferable.

Examples of the above salts include salts with diethylamine, ammonia, ethylamine, triethylamine, propylamine, isopropylamine, dipropylamine, butylamine, isobutylamine, triethanolamine, diethanolamine, aminomethylpropanol, morpholine and the like. Can be. The weight average molecular weight of these copolymers is preferably from 3,000 to 30,
000, more preferably 5,000 to 15,000.

Preferred examples of the surfactant as a dispersant include fatty acid salts, higher alkyl dicarboxylates, higher alcohol sulfates, higher alkyl sulfonates, condensates of higher fatty acids and amino acids, and sulfosuccinates. Anionic surfactants such as salts, naphthenates, liquid fatty acid sulfates, and alkyl allyl sulfonates; cationic surfactants such as fatty acid amine salts, quaternary ammonium salts, sulfonium salts, and phosphonium salts; Examples include nonionic surfactants such as ethylene alkyl ethers, polyoxyethylene alkyl esters, sorbitan alkyl esters, and polyoxyethylene sorbitan alkyl esters. The addition amount of these dispersants is preferably in the range of 0.06 to 3 parts by weight, more preferably 0.125 to 3 parts by weight, based on 1 part by weight of the pigment.

According to a preferred embodiment of the present invention, the ink used in the present invention preferably further contains a wetting agent. Preferred examples of the wetting agent include diethylene glycol, polyethylene glycol, polypropylene glycol, ethylene glycol, propylene glycol,
Butylene glycol, triethylene glycol, 1,
2,6-hexanetriol, thioglycol, hexyleneglycol, glycerin, trimethylolethane,
Trimethylolpropane, urea, 2-pyrrolidone, N-
Examples thereof include methyl-2-pyrrolidone and 1,3-dimethyl-2-imidazolidinone. Particularly, those having an ethylene oxide group are preferable, and diethylene glycol is most preferable.

Further, in addition to these wetting agents, it is preferable to further add a low-boiling organic solvent. Preferred examples of the low boiling organic solvent include methanol, ethanol, n
-Propanol, iso-propanol, n-butanol, sec-butanol, tert-butanol, is
o-butanol, n-pentanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether,
Examples thereof include diethylene glycol monoethyl ether, triethylene glycol monomethyl ether, and triethylene glycol monoethyl ether. Particularly, a monohydric alcohol is preferable. The addition amount of these wetting agents is suitably in the range of 0.5 to 40% by weight, preferably 2 to 20% by weight of the ink. The amount of the low boiling organic solvent added is 0.5 to 10% by weight of the ink, preferably 1.5 to 6% by weight.
Is appropriate.

According to a preferred embodiment of the present invention, the ink used in the present invention may contain a surfactant. Examples of preferred surfactants include anionic surfactants (eg, sodium dodecylbenzenesulfonate, sodium laurate, ammonium salts of polyoxyethylene alkyl ether sulfate, etc.), nonionic surfactants (eg, polyoxyethylene Alkyl ether, polyoxyethylene alkyl ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylphenyl ether, polyoxyethylene alkylamine, polyoxyethylene alkylamide, etc.)
These can be used alone or in combination of two or more. Further, acetylene glycol [olefin Y, surfynol 82, 10
4, 440, 465, 485, and TG (all Ai
r Products and Chemicals Inc.]] can also be used.

The ink used in the present invention can contain sugar. Examples of saccharides include monosaccharides, disaccharides, oligosaccharides (including trisaccharides and tetrasaccharides) and polysaccharides, preferably glucose, mannose,
Fructose, ribose, xylose, arabinose,
Examples include galactose, aldonic acid, glucitol, sorbitol, maltose, cellobiose, lactose, sucrose, trehalose, and maltotriose. The polysaccharides include alginic acid, α-
Cyclodextrin, cellulose and the like are included. In addition, examples of derivatives of these saccharides include reducing sugars of the above-mentioned saccharides, for example, sugar alcohols, oxidized sugars (eg, aldonic acid, uronic acid, etc.), amino acids, and thiosugars. Particularly, sugar alcohols are preferable, and specific examples thereof include maltitol and sorbitol. The content of these saccharides is 0.1 to 4 of the ink.
It is preferably about 0% by weight, more preferably 0.5 to 30%.
% By weight.

The ink used in the present invention may include a resin emulsion. The resin emulsion means an emulsion in which the continuous phase is water and the dispersed phase is the following resin component. Examples of the resin component of the dispersed phase include acrylic resins, vinyl acetate resins, styrene-butadiene resins, vinyl chloride resins, acryl-styrene resins, butadiene resins, and styrene resins. According to a preferred embodiment of the present invention, the resin is preferably a polymer having both a hydrophilic part and a hydrophobic part. The particle size of these resin components is not particularly limited as long as an emulsion is formed, but is preferably about 150 nm or less, more preferably about 5 to 100 nm.

These resin emulsions can be obtained by mixing resin particles with water, if necessary, together with a surfactant. For example, an emulsion of an acrylic resin or a styrene-acrylic resin is (meth)
It can be obtained by mixing acrylate or styrene, (meth) acrylate, optionally (meth) acrylic acid, and a surfactant in water. The mixing ratio of the resin component and the surfactant is usually 1
It is preferable that the ratio be about 0: 1 to 5: 1. When the amount of the surfactant is less than the above range, it is difficult to obtain an emulsion, and when the amount exceeds the above range, the water resistance of the ink tends to decrease and the permeability tends to deteriorate.

The surfactant is not particularly limited, but preferred examples include anionic surfactants (eg, sodium dodecylbenzansulfonate, sodium raurylate, ammonium salt of polyoxyethylene alkyl ether sulfate, etc.), and nonionic surfactants. Surfactants (for example, polyoxyethylene alkyl ether, polyoxyethylene alkyl ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylphenyl ether, polyoxyethylene alkylamine,
Such as polyoxyethylene alkylamide),
These can be used alone or in combination of two or more. The proportion of the resin as the disperse phase component and water is suitably from 60 to 400 parts by weight, preferably from 100 to 200 parts by weight, based on 100 parts by weight of the resin.

As such a resin emulsion, known resin emulsions can be used. For example, Japanese Patent Publication No. 62-1426 and Japanese Patent Application Laid-Open No. 3-56573.
JP-A-3-79678, JP-A-3-160068
And the resin emulsions described in JP-A-4-18462 can be used as they are.

It is also possible to use a commercially available resin emulsion, for example, Microgel E-100.
2, E-5002 (styrene-acrylic resin emulsion, manufactured by Nippon Paint Co., Ltd.), Boncoat 4001
(Acrylic resin emulsion, manufactured by Dainippon Ink and Chemicals, Inc.), Boncoat 5454 (styrene-acrylic resin emulsion, manufactured by Dainippon Ink and Chemicals, Inc.), SAE1014 (styrene-acrylic resin emulsion, manufactured by Zeon Corporation) ), Cybinol SK
-200 (acrylic resin emulsion, manufactured by Seiden Chemical Co., Ltd.).

The ink used in the present invention may further contain, if necessary, a pH adjuster, a preservative, and / or a fungicide.

The ink used in the present invention can be produced by dispersing and mixing the above components by an appropriate method. Preferably, the mixture from which the organic solvent and volatile components have been removed is mixed with a suitable disperser (eg, ball mill, sand mill, attritor, roll mill, agitator mill,
It is preferable to add an organic solvent and a volatile component after mixing with a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a jet mill, an ang mill and the like to obtain a homogeneous composition. Thereafter, filtration (preferably reduced pressure or pressure filtration using a metal filter, a membrane filter, or the like) or centrifugal separation is preferably performed to remove coarse particles and foreign substances that cause clogging.

Ink jet recording method In the ink jet recording method according to the present invention, the ink of the ink set of the present invention is used as the ink. In the ink jet recording method according to the present invention, it is preferable that the ink be deposited on the recording medium in the order of decreasing color fading rate.

For example, when the ink jet recording method according to the present invention is performed using at least a yellow ink, a magenta ink, and a cyan ink, the yellow ink, the magenta ink, and the cyan ink are used in the order of increasing lightness of the inks. In some cases, a combination of inks in which the relationship between the fading rate of yellow ink (Y), the fading rate of magenta ink (M), and the fading rate of cyan ink (C) is Y>M> C is selected. Preferably, ink is ejected, followed by magenta ink, followed by cyan ink.

In the ink jet recording method according to the present invention, for example, in addition to the above-mentioned yellow ink, magenta ink and / or cyan ink, one or more of light magenta ink, light cyan ink and / or black ink may be used. In the case of using a combination of the above, the fading rate of the yellow ink (Y) when the inks are yellow ink, light magenta ink, light cyan ink, magenta ink, cyan ink, and black ink in descending order of brightness. ), Fading rate of light magenta ink (Lm), fading rate of light cyan ink (Lc), fading rate of magenta ink (M), fading rate of cyan ink (C), and fading rate of black ink (K) Is: Y>Lm>Lc>M>C> K To select the combination of the ink, preferably the discharge on those recording media in descending order fading rate of the ink.

Further, in the ink jet recording method according to the present invention, for example, one or more of orange ink, green ink and / or black ink in addition to the above-mentioned yellow ink, magenta ink and / or cyan ink. When used in combination, the yellow ink, the orange ink, the magenta ink, the cyan ink, the green ink, and the black ink are the yellow ink, the orange ink, the magenta ink, the cyan ink, the green ink, and the black ink. The relationship between the fading rate of orange ink (O), the fading rate of magenta ink (M), the fading rate of cyan ink (C), the fading rate of green ink (G), and the fading rate of black ink (K) is as follows: Y >O>M>C>G> K, and select the ink combinations. Preferably discharge the fading rate descending order on the recording medium.

In the image obtained by the method of the present invention, the fading of each ink proceeds with time based on the above-mentioned relational expression. However, it is practical to visually recognize the difference in the rate of fading. Since it is impossible or difficult, it is possible to make it difficult to visually recognize the fading of the entire color image. That is, according to the method of the present invention, the light resistance of the obtained image can be apparently improved.

The present invention also provides an ink jet recording head in which nozzles for discharging ink are arranged in order from the ink having a higher fading rate in the moving direction of the recording head. Further, the present invention also provides an ink jet recording apparatus comprising the above ink jet recording head. According to the present invention, there is also provided a recording medium on which recording is performed by the inkjet recording method.

[0043]

EXAMPLES The present invention will be described below in more detail with reference to examples, but these examples do not limit the scope of the present invention. An ink composed of the following components was prepared to prepare a color ink set.

Preparation of Color Ink Set 1 (a) Color ink set 1 was prepared by dispersing the following three pigments in the following amounts in a liquid medium described below. Pigment for cyan ink C.I. I. Pigment Blue 15: 3 2% by weight Pigment for magenta ink C.I. I. Pigment Red 122 3% by weight Pigment for yellow ink C.I. I. Pigment Yellow 742 2% by weight (b) The composition of the liquid medium used to prepare each ink is shown below.

Styrene-acrylic acid copolymer (dispersant) 0.5% by weight Sucrose 0.7% by weight Maltitol 6.3% by weight Ethylene glycol 15% by weight Triethylene glycol monobutyl ether 5% by weight Disodium ethylenediaminetetraacetate (Chelating agent) 0.01% by weight Preservative (Proxel-XLII; manufactured by ICI) 0.3% by weight Pure water

Preparation of Black Ink 1 Black Ink 1 having the following composition was prepared. Carbon black MA7 (manufactured by Mitsubishi Kasei Corporation) 5% by weight Styrene-acrylic acid copolymer (dispersant) 1% by weight Sucrose 0.7% by weight Maltitol 6.3% by weight Glycerin 10% by weight 2-pyrrolidone 2% by weight Surfynol 465 0.5% by weight Potassium hydroxide 0.1% by weight Disodium ethylenediaminetetraacetate (chelating agent) 0.01% by weight Preservative (Proxel-XLII; manufactured by ICI) 0.3% by weight Pure water

Preparation of Color Ink Set 2 (a) Color ink set 2 was prepared by dispersing the following two pigments in the following amounts in a liquid medium described below. Pigment for light cyan ink C.I. I. Pigment Blue 60 0.3% by weight Pigment for light magenta ink C.I. I. Pigment Red 209 0.4% by weight

(B) The composition of the liquid medium used for preparing each ink is shown below. Styrene-acrylic acid copolymer (dispersant) 0.5% by weight Sucrose 0.7% by weight Maltitol 6.3% by weight Ethylene glycol 15% by weight Glycerin 10% by weight Surfynol 465 1% by weight Triethylene glycol monobutyl ether 3 Weight% disodium ethylenediaminetetraacetate (chelating agent) 0.01 weight% preservative (Proxel-XLII; manufactured by ICI) 0.3 weight% pure water

Preparation of Color Ink Set 3 (a) Color ink set 3 was prepared by dispersing the following two pigments in the following amounts in a liquid medium described below. Pigment for green ink C.I. I. Pigment Blue 7 2% by weight Pigment for orange ink C.I. I. Pigment Orange 43 3% by weight

(B) The composition of the liquid medium used for preparing each ink is shown below. Styrene-acrylic acid copolymer (dispersant) 0.5% by weight Sucrose 0.7% by weight Maltitol 6.3% by weight Ethylene glycol 15% by weight Surfinol 465 1% by weight Triethylene glycol monobutyl ether 3% by weight Ethylene diamine 4% Disodium acetate (chelating agent) 0.01% by weight Preservative (Proxel-XLII; manufactured by ICI) 0.3% by weight Pure water

Preparation of Color Ink Set 4 (a) Color ink set 4 was prepared by dispersing the following three pigments in the following amounts in a liquid medium described below. Pigment for cyan ink C.I. I. Pigment Blue 15: 3 2% by weight Pigment for magenta ink C.I. I. Pigment Red 57: 13% by weight Pigment for yellow ink C.I. I. Pigment Yellow 110 2% by weight

(B) The composition of the liquid medium used for preparing each ink is shown below. Styrene-acrylic acid copolymer (dispersant) 0.5% by weight Sucrose 0.7% by weight Maltitol 6.3% by weight Ethylene glycol 15% by weight Triethylene glycol monobutyl ether 5% by weight Disodium ethylenediaminetetraacetate (chelating agent) 0.01% by weight Preservative (Proxel-XLII; manufactured by ICI) 0.3% by weight Pure water

Adjustment and Measurement of Cumulative Average Diameter Each of the inks prepared above is inserted into a roll mill, and the dispersion time is controlled to filter coarse particles having a particle diameter of a certain level or more, thereby obtaining examples and comparative examples described later. An ink having a predetermined cumulative average diameter shown in Examples was obtained. The cumulative average diameter was measured by a laser scattering particle size distribution analyzer (Microtrack 9230 UPA; manufactured by Lees Northrup).

[0054]Fading rate measurement The measurement of the fading rate in the following Examples and Comparative Examples
Use the In-Weatherometer Ci35A (ATLAS)
It was carried out by a light fastness test. Black panel temperature 63
° C, 50% relative humidity, and 340 nm UV irradiance
0.35W / m ²Under the condition of 300 kJ / m²(About 2
38 hours). Measurement of reflection density
Using a GRETAG SPM50 (GRETAG)
Therefore, with the light source D50 and without the light source filter,
Measure reflection density at a viewing angle of 2 ° with standard absolute white,
Formula (I): F (%) = (Di−De) / Di × 100 (I) (wherein, F, Di, and De have the same meanings as described above.)
To calculate the fading rate.

Lightness Measurement The lightness was measured in the same manner using the same apparatus as that for the reflection density measurement.

Example 1 Using an ink jet printer MJ-510C (a printer using three color inks of cyan, magenta and yellow: manufactured by Seiko Epson Corporation), a color ink composed of an ink containing a pigment having the following cumulative average diameter: The set 1 was printed on a print medium exclusively for inkjet (Seiko Epson's exclusive glossy film).

Cumulative average diameter: Cyan pigment: 105 μm Magenta pigment: 65 μm Yellow pigment: 53 μm The relationship between the fading rate of yellow ink (Y), the fading rate of magenta ink (M), and the fading rate of cyan ink (C) is as follows. Y>M> C.

The brightness of each ink was as follows. Lightness: Y: 88 M: 52 C: 46 Printing was performed in such a manner that ink was applied in descending order of the fading rate, that is, yellow ink first, magenta ink first, and cyan ink last.

Example 2 Printing was performed in the same manner as in Example 1 except that the printing sequence was such that cyan ink, magenta ink, and yellow ink were deposited in this order.

Example 3 Using an ink jet printer MJ-930C (a printer using four color inks of cyan, magenta, yellow and black: manufactured by Seiko Epson Corporation), a color ink set 1 having the following cumulative average diameter and black were used. Ink 1 was printed on a print medium exclusively for inkjet (a special glossy film manufactured by Seiko Epson).

Cumulative average diameter: Black pigment: 95 μm Cyan pigment: 105 μm Magenta pigment: 65 μm Yellow pigment: 53 μm Yellow ink fading rate (Y), magenta ink fading rate (M), cyan ink fading rate (C), The relationship between the fading rate (K) of the black ink and the black ink was Y>M>C> K.

The brightness of each ink was as follows. Lightness: Y: 88 M: 52 C: 46 K: 16 In printing, ink is deposited in the descending order of the fading rate of ink, that is, yellow ink, magenta ink, cyan ink, and black ink last. I went to do it.

Example 4 Using an ink jet printer PM-700C (a printer using six color inks of cyan, magenta, yellow, black, light cyan and light magenta: manufactured by Seiko Epson Corporation), a color ink set 1 and black The ink 1 and the color ink set 2 were printed on a print medium exclusively for inkjet (a special gloss film made by Seiko Epson).

Cumulative average diameter: Black pigment: 95 μm Cyan pigment: 105 μm Magenta pigment: 65 μm Yellow pigment: 53 μm Light cyan pigment: 105 μm Light magenta pigment: 65 μm Fading rate of yellow ink (Y), fading rate of light magenta ink (Lm) , Light cyan ink fading rate (L
c), the relationship between the fading rate of the magenta ink (M), the fading rate of the cyan ink (C), and the fading rate of the black ink (K) was Y>Lm>Lc>M>C> K.

The brightness of each ink was as follows. Lightness: Y: 88 Lm: 68 Lc: 63 M: 52 C: 46 K: 16 Printing is performed in descending order of the fading rate of the ink, that is, first, the yellow ink, then the light magenta ink, then the light cyan ink, and then Magenta ink, then cyan ink, and finally black ink.

Example 5 Using the ink jet printer PM-700C, the color ink set 1, the black ink 1 and the color ink set 3 were printed on a print medium exclusively for inkjet (a glossy film made by Seiko Epson).

Cumulative average diameter: Black pigment: 95 μm Cyan pigment: 105 μm Magenta pigment: 65 μm Yellow pigment: 53 μm Green pigment: 100 μm Orange pigment: 88 μm Yellow ink fading rate (Y), orange ink fading rate (O), magenta The relationship between the fading rate of the ink (M), the fading rate of the cyan ink (C), the fading rate of the green ink (G), and the fading rate of the black ink (K) is as follows: Y>O>M>C>G> K Met.

The brightness of each ink was as follows. Lightness: Y: 88 O: 65 M: 52 C: 46 G: 44 K: 16 Printing is performed in descending order of ink fading rate, that is, first yellow ink, then orange ink, then magenta ink, then Cyan ink, green ink, and finally black ink were applied in this order.

Example 6 Using an ink-jet printer MJ-510C, a color ink set 1 having the following cumulative average diameter was used as a print medium exclusively for inkjet (a glossy film made by Seiko Epson).
Printed on.

Cumulative average diameter: Cyan pigment: 30 μm Magenta pigment: 110 μm Yellow pigment: 53 μm The relationship between the fading rate of yellow ink (Y), the fading rate of cyan ink (C), and the fading rate of magenta ink (M) is as follows. It is larger in the order of Y>C> M.

The brightness of each ink was as follows. Lightness: Y: 88 C: 55 M: 42 In addition, printing is performed in descending order of the ink fading rate, that is,
First, yellow ink, then cyan ink, and finally magenta ink.

Comparative Example 1 In the same manner as in Example 2, using the inkjet printer MJ-930C, the color ink set 4 and the black ink 1 having the following cumulative average diameters were printed on a printing medium exclusively for inkjet (a glossy film made by Seiko Epson). .

Cumulative average diameter: black pigment: 95 μm cyan pigment: 105 μm magenta pigment: 51 μm yellow pigment: 115 μm fading rate of magenta ink (M), fading rate of yellow ink (Y), fading rate of cyan ink (C), The relationship between the fading rate (K) of the black ink and the black ink was larger in the order of M>Y>C> K.

The brightness of each ink was as follows. Lightness: M: 70 Y: 68 C: 46 K: 16 Printing is applied in the order of decreasing color fading rate of ink, that is, black ink, then cyan ink, then yellow ink, and finally magenta ink. I went to do it.

In the light resistance evaluation examples 1 to 6 and the comparative example 1, a person image was printed and left outdoors for one month to be exposed to direct sunlight. The determination was made by showing the presence or absence of the deterioration of the person image to 50 people of a wide age group. The determination is performed in the following four stages (A to D), and the results are shown in Table 1. A: Less than 10 people judged to be deteriorated (excellent level). B: 10 or more and less than 25 people were judged to be deteriorated (practical level). C: 25 or more and less than 40 (judgment limit) that the deterioration was judged. D: More than 40 people judged to be deteriorated (defective level).

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Claims (11)

[Claims] 1. An ink set for ink-jet recording comprising two or more inks, wherein the color fading rate of the inks is set to be smaller in order from the ink having the higher brightness to the ink having the lower brightness. 2. The inks are a yellow ink, a magenta ink, and a cyan ink, and the yellow ink, the magenta ink, and the
The ink set for inkjet recording according to claim 1, wherein the ink set is a cyan ink. 3. The ink is a yellow ink, a magenta ink, a cyan ink and a black ink, and the yellow ink, the yellow ink,
The ink set for inkjet recording according to claim 1, wherein the ink set is a magenta ink, a cyan ink, and a black ink. 4. The ink is a yellow ink, a light magenta ink, a light cyan ink, a magenta ink, a cyan ink, and a black ink, and the yellow ink, light magenta ink, light cyan ink, Magenta ink,
2. A cyan ink and a black ink.
2. The ink set for inkjet recording according to item 1. 5. An ink comprising: yellow ink, orange ink, magenta ink, cyan ink, green ink,
2. The ink set for inkjet recording according to claim 1, wherein the ink set is a yellow ink, an orange ink, a magenta ink, a cyan ink, a green ink, and a black ink in descending order of brightness. 6. The ink set for ink jet recording according to claim 1, wherein the ink contains a pigment as a colorant. 7. An ink-jet recording method for ejecting ink droplets and attaching the droplets to a recording medium to perform printing, wherein the ink set according to claim 1 is used as an ink. Ink jet recording method using the above ink. 8. The ink jet recording method according to claim 7, wherein said ink is deposited on a recording medium in order of increasing color fading rate. 9. An ink jet recording head comprising nozzles for discharging ink in order from the ink having a high fading rate in the moving direction of the recording head. 10. An ink jet recording apparatus comprising the ink jet recording head according to claim 9. 11. A recording medium on which recording has been performed by the ink jet recording method according to claim 7.