JP2008037976A - Ink for ink jet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive magenta-based ink for ink jets having high saturation and density of a magenta-based image formed of a pigment-based ink for the ink jets, easily regulating a delicate color tone, having excellent water resistance of the image and good jetting stability without especially printing deflection and carrying out printing with an ink-jet type printer. <P>SOLUTION: The ink for ink jets comprises resin fine particles (A) dyed with a fluorescent dye and having 50-130 nm average particle diameter and quinacridone-based pigment fine particles (B) having 50-130 nm average particle diameter. The ink is characterized in that the color tone of the (A) is any of yellow, yellow orange, orange, red orange, red, pink, cerise, rose and magenta or a mixed color thereof. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention comprises resin fine particles dyed with a fluorescent dye having a specific color tone having a specific average particle size, and quinacridone pigment fine particles having a specific average particle size, and has an image density and image saturation. For magenta ink jets that can be printed with an ink jet printer that is high, easy to adjust delicate colors, inexpensive, excellent in water resistance of images, excellent in ejection stability, and especially free of printing distortion It relates to ink.

  Conventionally, inks used in ink jet recording systems have been mainly used in which various water-soluble dyes are dissolved in water alone or in a solvent composed of water and a water-soluble solvent, and various additives are added as necessary.

  However, when printing is performed using such a dye-based ink, the water resistance of the recorded image on the recording material is poor, and if the water is spilled, the problem of bleeding of the dye in the recorded portion easily occurs, Since the light resistance is poor, there is a problem that when the recording portion is exposed to light, a change in color tone or a decrease in density occurs.

  In order to improve the above-mentioned problems of dye-based inks, it is known to apply so-called pigment-based inks using carbon black or various organic pigments instead of dyes as colorants to inkjet recording systems.

When printing is performed using pigment-based ink, the ink dried on the recording material is a pigment as a colorant. Good properties.
In addition, since pigments are less reactive to light than dyes, the light resistance of pigment-based inks is superior to that of dye-based inks.

Such pigment-based inks are generally produced by adding various additives as necessary to a pigment dispersion prepared by dispersing a mixture of a pigment, a liquid medium and a dispersant using a dispersing machine such as a ball mill or a sand mill. However, the pigment dispersion used in the ink for ink jet recording usually has a particle size level of 200 nm or less in order to prevent nozzle clogging in a printing apparatus (ink jet printer), sharpness of a printed image, secondary color reproducibility, and transparency. It is necessary to finely disperse the pigment particles in the pigment dispersion. Furthermore, it is known that if the particle size is reduced to a level of 100 nm or less, the image saturation increases and an image with high transparency can be formed.
However, with quinacridone pigments that have been mainly used in the past, the image saturation increases to some extent by making the particles fine, but it does not reach the saturation of the magenta image formed with dye ink. It was.

As an attempt to improve the image saturation of the magenta color pigment ink, there is a document described in Patent Document 1 (Japanese Patent Laid-Open No. 10-298467) as a document disclosing a seemingly similar technique to the present invention.
In the technology described in the publication, it is proposed to use, as ink, an aqueous suspension in which a mixed color material obtained by mixing a color material having no fluorescence and a color material having fluorescence in a specific weight ratio is adsorbed to polymer particles. Has been.
According to the publication, it is said that the water resistance of the printed matter can be improved and the print quality of the print density, color tone, and saturation can be improved. However, the implementation of increasing the print density and improving the brightness of the image. Although described in the examples, the image saturation improvement effect is not described in the examples, and it is not clear whether the image saturation is improved by the present invention.
In addition, the printing density is increased because the amount of the mixed color material adsorbed on the polymer particles (mixed color material introduction amount) is larger in the example than in the comparative example, which is natural.
Accordingly, by using, as an ink, an aqueous suspension in which a mixed color material obtained by blending a color material having no fluorescence and a color material having fluorescence in a specific weight ratio is adsorbed on polymer particles in the publication. The claim that saturation and print density are to be improved should be considered unproven.
Further, in this publication, when adjusting the color tone of a magenta image that slightly changes due to differences in ink formulation such as pigment concentration, penetrant addition amount, wetting agent addition amount, and the type of ink receptor such as paper, In order to adjust the color tone, a water-based suspension in which a mixed color material having a composition in which the weight ratio of a color material having no fluorescence and a color material having fluorescence is changed is adsorbed to polymer particles is manufactured each time. In addition, it is necessary to select an optimum color from among the aqueous suspensions, which is very complicated and expensive.

Japanese Patent Laid-Open No. 10-298467

  The present invention has been made in view of the above-described problems, and the saturation and density of a magenta color image formed with a pigment-based inkjet ink is high, and delicate color tone adjustment is easy and inexpensive. Another object of the present invention is to provide a magenta ink jet ink that is excellent in water resistance of an image, has good ejection stability, and has no printing distortion, and can be printed by an ink jet printer.

  In order to solve the above problems, the magenta inkjet ink according to the present invention includes at least a resin fine particle dyed with a fluorescent dye having a specific color tone having a specific average particle size, and a specific average particle size. By using a magenta color inkjet ink comprising quinacridone pigment fine particles, the saturation and density of the magenta color image are high, the subtle color tone adjustment is easy, and the water resistance of the image is high. The present invention can provide a magenta ink jet ink that is excellent in ink jetting, has good ejection stability, and has no printing bending, and can be printed by an ink jet printer.

That is, the said subject is solved by the structure of (1)-(23) of this invention shown below.
(1) “Ink-jet ink containing resin fine particles (A) dyed with a fluorescent dye and having an average particle size of 50 to 130 nm and quinacridone pigment fine particles (B) having an average particle size of 50 to 130 nm, Ink-jet ink characterized in that the color tone of (A) is any one of yellow, yellow-orange, orange, red-orange, red, pink, cerise, rose, magenta, or a mixed color thereof.
(2) “The ink-jet ink according to item (1), wherein the weight ratio (A / B) between (A) and (B) is in the range of 1/2 to 8/1”. ,
(3) “Ink for inkjet according to item (1) or (2), wherein the standard deviation of particle diameter of (A) is 40 nm or less”,
(4) "Any of the above items (1) to (3), wherein the constituent monomer of (A) is at least one of styrene, acrylonitrile, acrylic acid, and methacrylic acid" Ink-jet ink as described in "
(5) In the inkjet according to any one of (1) to (4), wherein (B) is at least one of quinacridone, dimethylquinacridone, and dichloroquinacridone. ink",
(6) “Ink-jet ink according to any one of (1) to (5) above, which comprises 5 to 20% by weight of (A) and (B) in total” ,
(7) "The inkjet ink according to any one of (1) to (6) above, wherein (B) is dispersed with a dispersant";
(8) "The inkjet ink according to item (7), wherein the dispersant is a nonionic surfactant";
(9) “The inkjet ink according to item (8), wherein the nonionic surfactant is POE naphthyl ether”;
(10) "The inkjet ink according to item (9), wherein the POE naphthyl ether has an EO molar number in the range of 12 to 60",
(11) “The inkjet ink according to item (7), wherein the dispersant is an anionic surfactant”;
(12) “Ink jet ink according to item (11), wherein the anionic surfactant is an alkali salt of POE naphthyl ether phosphate”;
(13) wherein the POE naphthyl ether phosphate alkali salt has an EO mole number in the range of 5 to 60, and the alkali species is at least one of Li, Na and K; Ink-jet ink according to item 12),
(14) The items (1) to (13), wherein the weight ratio (B / dispersant) between the (B) and the dispersant is in the range of 1/1 to 1 / 0.1. Ink-jet ink according to any one of items
(15) "Ink cartridge containing the ink-jet ink according to any one of (1) to (14)",
(16) “The ink cartridge according to item (15), which is detachable from the image forming apparatus”,
(17) "An image forming body in which an image is formed on a receptor using the ink jet ink according to any one of (1) to (14)",
(18) "An image forming method characterized in that an image is formed on a receptor using the inkjet ink according to any one of (1) to (14)",
(19) "The ink cartridge according to item (16), wherein the image forming apparatus is an ink jet printer",
(20) “Image formation according to item (18), wherein the inkjet ink according to any one of items (1) to (14) is discharged from an inkjet printer to a receiver. Method",
(21) "The image forming method according to (20), wherein the inkjet printer is a piezo inkjet printer",
(22) “The image forming method according to (20), wherein the ink jet printer is a thermal ink jet printer”,
(23) “The image forming body according to item (17), wherein the receptor is paper”.

  The ink-jet ink of the present invention has an excellent effect that the image density and the image saturation are high, the printing is not bent, and the ejection stability is excellent.

Hereinafter, the present invention will be described in detail.
According to the items (1) to (6), the saturation and density of the magenta color image are high, the subtle color tone adjustment is easy and inexpensive, the water resistance of the image is excellent, and the ejection stability is high. It is possible to provide a magenta color ink-jet ink that is good and that can be printed with an ink jet printer that is not particularly bent.

In the inkjet ink of item (1), the color tone of (A) is any one of yellow, yellow-orange, orange, red-orange, red, pink, cerise, rose, magenta, or a mixed color thereof. Even if the image density is high, the color becomes turbid, and a magenta color image with high saturation cannot be obtained. Specifically, the wavelength of the light of the color tone is preferably 580 nm or more, more preferably 590 nm or more and 650 nm or less.
Moreover, it is preferable that the average particle diameter of (A) is 50-130 nm. If it is less than 50 nm, the fluorescence intensity decreases, so that the saturation of the image is lowered, and if it exceeds 130 nm, the ejection stability of the ink is deteriorated.
The average particle size of (B) is preferably 50 to 130 nm. If it is less than 50 nm, dispersion is difficult and the storage stability of the ink is poor. If it exceeds 130 nm, the ejection stability of the ink is deteriorated.
(B) is inexpensive because it can be obtained simply by dispersing quinacridone pigments such as quinacridone, dimethylquinacridone, dichloroquinacridone, etc. by a conventional method, and the color tone of the ink can be adjusted by adding (A) and (B) to the ink. It is very easy to complete by changing the amount.

In the inkjet ink of item (2), the weight ratio (A / B) of (A) and (B) is preferably in the range of 1/2 to 8/1.
When the ratio of (B) is higher than 1/2, the effect of improving the image saturation is reduced. When the ratio of (A) is higher than 8/1, the image density is lowered and the fluorescence is too strong. As a result, the color tone becomes unnatural.

In the inkjet ink of item (3), the standard deviation of the particle diameter of (A) is preferably 40 nm or less.
When the standard deviation exceeds 40 nm, the number of coarse particles increases, and the ink ejection stability deteriorates.

In the inkjet ink of item (4), the constituent monomer (A) is preferably at least one of styrene, acrylonitrile, acrylic acid, and methacrylic acid.
Polymers composed of the above monomers have good dyeing properties of fluorescent dyes and can increase the image density.

In the inkjet ink of item (5), (B) is preferably at least one of quinacridone, dimethylquinacridone, and dichloroquinacridone.
Quinacridone pigments other than those described above are expensive and cannot obtain a good magenta color tone.

  In the inkjet ink of item (6), (A) and (B) preferably comprise 5 to 20% by weight in total. If it is less than 5% by weight, the image density is insufficient, and if it is more than 20% by weight, nozzle clogging tends to occur.

  In the ink-jet ink of item (7), it is preferable that (B) is dispersed with a dispersing agent because it is a low-cost ink. A so-called self-dispersing pigment (surface-treated pigment) that has a water dispersibility-imparting group on the pigment surface and can stably maintain a dispersed state without a dispersant does not reduce the cost.

  In the ink-jet ink of item (8), (B) is low cost that it is dispersed with a nonionic surfactant, and is stable in storage even when mixed with various additives used in ink preparation. This is preferable because a good ink is obtained.

  In the ink-jet inks of the items (9) and (10), (B) is POE naphthyl ether, more preferably the POE naphthyl ether has an EO molar number in the range of 12-60. In the POE naphthyl ether, the presence of a naphthyl group strongly adsorbs the quinacridone to improve the dispersion stability. When the EO mole number of the POE naphthyl ether is less than 12, the dispersion stability is lowered, and when it exceeds 60, the viscosity of the ink is increased.

  In the ink-jet ink of item (11), it is preferable that (B) is dispersed with an anionic surfactant because the ink is low in cost and has good dispersion stability.

In the inkjet inks according to the items (12) and (13), (B) is an alkali salt of POE naphthyl ether phosphate, more preferably, the OE mole number of the alkali salt of the POE naphthyl ether phosphate is 5 to 60. Preferably, the alkali species is at least one of Li, Na, and K.
The alkali salt of POE naphthyl ether phosphate is strongly adsorbed to quinacridone due to the presence of the naphthyl group, and the dispersion stability is improved. In addition, the presence of the alkali salt portion of the phosphate reaggregates the dispersed pigment particles. Is prevented and the dispersion stability is improved.
When the number of EO moles of the alkali salt of the POE naphthyl ether phosphate is less than 5, the dispersion stability is lowered, and when it exceeds 60, the viscosity of the ink is increased.
When the alkali species of the alkali salt of the POE naphthyl ether phosphate is at least one of Li, Na, and K, the cost is low and the storage stability is good even when mixed with various additives used in ink preparation. Since it becomes an ink, it is preferable.

  In the inkjet ink of item (14), the weight ratio (B / dispersant) of (B) to the dispersant is preferably in the range of 1/1 to 1 / 0.1. When the weight ratio of the dispersant is higher than 1/1, the viscosity of the ink is increased and the storage stability of the ink is deteriorated. Further, when the weight ratio of the dispersant is lower than 1 / 0.1, the dispersion stability is lowered.

In order to prepare (A) of the present invention, a known method, for example, a method disclosed in Examples described in JP-A No. 2001-181544 may be used.
To prepare (B) of the present invention, a quinacridone pigment is dispersed with a dispersant such as a surfactant disclosed in the present invention. Specifically, after premixing the quinacridone pigment powder, water and a dispersant, it may be dispersed to a specific average particle size by a known method using a dispersing machine such as a sand mill or dyno mill.
The thus obtained (A) and (B) are mixed at a predetermined ratio, and water, a water-soluble organic solvent, and if necessary, a surfactant, an antiseptic and the like are added to prepare an inkjet ink.

As the surfactant, an anionic, nonionic, cationic or amphoteric surfactant can be used.
Anionic surfactants include fatty acid salts, alkyl sulfate salts, alkyl aryl sulfonates, alkyl naphthalene sulfonates, dialkyl sulfonates, dialkyl sulfosuccinates, alkyl diaryl ether disulfonates, alkyl phosphates, Examples include polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl aryl ether sulfate, naphthalenesulfonic acid formalin condensate, polyoxyethylene alkyl phosphate ester salt, glycerol borate fatty acid ester, polyoxyethylene glycerol fatty acid ester, etc. The
Nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene alkyl aryl ether, polyoxyethylene oxypropylene block copolymer, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, glycerin fatty acid ester And polyoxyethylene fatty acid ester, polyoxyethylene alkylamine, fluorine-based, silicon-based and the like.
Examples of the cationic surfactant include alkylamine salts, quaternary ammonium salts, alkylpyridinium salts, alkylimidazolium salts and the like.
Examples of amphoteric surfactants include alkylbetaines, alkylamine oxides, phosphadylcholines, and the like.

In the inkjet ink of the present invention, the water can be pure water such as ion exchange water, ultrafiltration water, reverse osmosis water, distilled water, or ultrapure water.
In addition, the use of water sterilized by ultraviolet irradiation or addition of hydrogen peroxide is preferable because generation of mold and bacteria can be prevented when the ink is stored for a long period of time.

Examples of the water-soluble organic solvent contained in the inkjet ink in the present invention include carbon such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, and tert-butyl alcohol. 1 to 4 alkyl alcohols; amides such as dimethylformamide and dimethylacetamide; ketones or ketone alcohols such as acetone, methyl ethyl ketone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; ethylene glycol, propylene glycol, 1, 2-propanediol, 1,2-butanediol, 1,3-butanediol, 3-methyl-1,3-butanediol, 1,4-butanediol, diethylene glycol, trie Polyhydric alcohols such as lenglycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol and glycerin; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; ethylene glycol monomethyl (or ethyl) ether, diethylene glycol Lower alkyl ethers of polyhydric alcohols such as methyl (or ethyl) ether and triethylene glycol monomethyl (or ethyl) ether; alkanolamines such as monoethanolamine, diethanolamine and triethanolamine; N-methyl-2-pyrrolidone; Examples include 2-pyrrolidone and 1,3-dimethyl-2-imidazolidinone.
In addition, the content of the water-soluble organic solvent in the ink jet ink is preferably 50% by weight or less in consideration of environmental properties and the like.

  In addition to the water-soluble organic solvent, a pH adjuster, preservative, resin, and the like may be used as necessary for the inkjet ink in the present invention.

Examples of the means for printing using the inkjet ink of the present invention include a printing method using an inkjet printer (inkjet printer) having a continuous jet type or on-demand type recording head. Note that examples of the on-demand type include a piezo method and a thermal ink jet method.
Further, the present invention relates to the configuration of an ink cartridge containing the ink composition of the present invention, the configuration of an ink jet printing apparatus that performs recording by discharging the ink composition of the present invention, and the image forming method in the printing apparatus. By referring to known techniques in the technical field, such as those disclosed in Japanese Patent Application Laid-Open No. 2000-198958, it can be easily implemented.
In addition, the average particle diameter and particle diameter standard deviation in this invention are measured using Nikkiso Co., Ltd. Microtrac UPA.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples at all. In addition, the number of parts in an Example represents a weight part.

(Example 1)
A 2 L flask was equipped with a condenser, a thermometer, a 500 ml separatory funnel for introducing monomers and a stirrer, and set in a water bath.
Next, 440 ml of water, 8.5 g of Na dodecylbenzenesulfonate, and 7 g of nonionic surfactant Emulgen LS-110 (manufactured by Kao Corporation) were placed in the flask, and the internal temperature was raised to 80 ° C. . Next, after charging 2.1 g of potassium persulfate into the heated contents, 140 g of acrylonitrile, 120 g of styrene, and 13 g of acrylic acid were mixed and stirred into the flask while stirring the monomer solution into the flask. The solution was added dropwise over 3 hours, and the polymerization was completed in 4 hours.
200 g of water, 0.3 g of Rhodamine F3B (“BANISOL RED 560” manufactured by BASF), 2.0 g of Rhodamine F4G (“BANISOL RED 485” manufactured by BASF), and a special polycarboxylic acid were obtained. Type polymer surfactant (“Demol EP” manufactured by Kao Corporation) was added under stirring at room temperature, mixed uniformly, then gradually heated, and dyed at 85 ° C. for 1 hour. Then, a bright pink fine particle dispersion having an average particle diameter of 58 nm and a particle diameter standard deviation of 31 nm was obtained.
The fine particle dispersion was adjusted to moisture to obtain a fluorescent fine particle dispersion (a) having a solid concentration of 40%.

Next, after premixing the mixture having the following constitution, it was circulated and dispersed for 20 hours in a disk type bead mill (Shinmaru Enterprises KDL type, media: 0.3 mmφ zirconia ball used), and a pigment having an average particle diameter of 63.5 nm A dispersion (a) was obtained.
Pigment Red 122 (= Dimethylquinacridone) 150 parts (Ciba Specialty Chemicals, Irgaphora Magenta DMQ)
POE (n = 40) β naphthyl ether 37.5 parts distilled water 812.5 parts

Using the fluorescent fine particle dispersion (a) and the pigment dispersion (a) obtained by the above method, an ink liquid was prepared according to the following ink formulation 1, stirred for 30 minutes, and then filtered through a membrane filter having a pore diameter of 0.8 μm. The inkjet ink (a) of the present invention was obtained by vacuum degassing.
(Ink formula 1)
Fluorescent fine particle dispersion liquid (a) 30 parts Pigment dispersion liquid (a) 33.3 parts Glycerin 20 parts 2-ethyl-1.3-hexanediol 2 parts PEG fluorinated alkyl monoether 2 parts (Zonyl FS300 manufactured by DuPont)
1-amino-2-ethyl-2.3-propanediol 1 part distilled water 11.7 parts

(Example 2)
In Example 1, in place of 0.3 g of rhodamine F3B (“Banisol Red 560” manufactured by BASF) and 2.0 g of Rhodamine F4G (“Vanisol Red 485” manufactured by BASF), Kayacryl Brilliant Yellow F2G (Nippon Kayaku) The average particle size was the same as in Example 1 except that 20 g of Basic Yellow 40) was used and the amount of the special polycarboxylic acid type polymer surfactant (“Demol EP” manufactured by Kao Corporation) was 21 g. A clear yellow fine particle dispersion having a diameter of 122 nm and a particle diameter standard deviation of 38 nm was obtained.
The fine particle dispersion was adjusted to moisture to obtain a fluorescent fine particle dispersion (b) having a solid concentration of 40%.

Using the pigment dispersion liquid (a) and the fluorescent fine particle dispersion liquid (b) of Example 1, prepare an ink liquid according to the following ink formulation 2, stir for 30 minutes, filter through a membrane filter with a pore size of 0.8 μm, and remove the vacuum. The ink (b) for inkjet according to the present invention was obtained.
(Ink formula 2)
Fluorescent fine particle dispersion (b) 8 parts Pigment dispersion (a) 33.3 parts Glycerin 20 parts 2-Ethyl-1.3-hexanediol 2 parts PEG fluorinated alkyl monoether 2 parts (DuPont ZONYL FS300)
1-amino-2-ethyl-2,3-propanediol 1 part distilled water 33.7 parts

(Example 3)
In Example 1, instead of the pigment dispersion (a), a mixture having the following constitution was premixed, and then a disk type bead mill (Shinmaru Enterprises KDL type, media: 0.3 mmφ zirconia ball used) for 20 hours. The mixture was circulated and dispersed to obtain a pigment dispersion (b) having an average particle size of 83.2 nm.
150 parts of Pigment Violet 19 (= Kinacridon) (Fastogen Super Red 7061B conc, manufactured by Dainippon Ink, Inc.)
POE (n = 10) β naphthyl ether phosphate K 37.5 parts Distilled water 812.5 parts

Using the fluorescent fine particle dispersion liquid (a) and the pigment dispersion liquid (b) of Example 1, an ink liquid was prepared according to the following ink formulation 3, stirred for 30 minutes, filtered through a membrane filter having a pore size of 0.8 μm, and vacuumed By deaeration, an ink-jet ink (c) of the present invention was obtained.
(Ink formula 3)
Fluorescent fine particle dispersion (a) 30 parts Pigment dispersion (b) 12 parts Glycerin 20 parts 2-Ethyl-1.3-hexanediol 2 parts PEG fluorinated alkyl monoether 2 parts (ZONYL FS300 manufactured by DuPont)
1-amino-2-ethyl-2,3-propanediol 1 part

(Comparative Example 1)
The same procedure as in Example 1 was conducted except that a green fluorescent fine particle dispersion (Lumicol NKW-3202W average particle size = 100 nm) was used instead of the fluorescent fine particle dispersion (a) of Example 1. Ink jet ink (d) was obtained.

(Comparative Example 2)
Instead of the fluorescent fine particle dispersion (a) of Example 1, a pink fluorescent fine particle dispersion (Lumicol NKW-C2117E average particle size = 400 nm manufactured by Nippon Fluorochemicals Inc.) was used in the same manner as in Example 1. Inkjet ink (e) was obtained.

(Comparative Example 3)
When preparing the pigment dispersion liquid (a) of Example 1, the circulation dispersion time was 10 hours to prepare a pigment dispersion liquid (c) having an average particle diameter of 156.2 nm, and the pigment dispersion liquid (a) was replaced with the pigment dispersion liquid. An inkjet ink (f) was obtained in the same manner as in Example 1 except that the liquid (c) was used.

(Comparative Example 4)
In the preparation of the fluorescent fine particle dispersion liquid (a) of Example 1, the monomer liquid was dropped into the flask from the separatory funnel with stirring. A fluorescent fine particle dispersion (c) was obtained.
The average particle size of the fluorescent fine particle dispersion (c) was 126 nm, and the standard deviation of particle size was 52 nm.
An inkjet ink (g) was obtained in the same manner as in Example 1 except that the fluorescent fine particle dispersion (c) was used instead of the fluorescent fine particle dispersion (a).

(Comparative Example 5)
Ink jet ink (h) in the same manner as in Example 1, except that the amount of the fluorescent fine particle dispersion (a) used in Example 1 was 5 parts and the amount of the pigment dispersion (a) used was 40 parts. Got.

(Comparative Example 6)
Ink jet ink (i) in the same manner as in Example 1, except that the amount of the fluorescent fine particle dispersion (a) used was 30 parts and the amount of the pigment dispersion (a) used was 8 parts in Example 1. Got.

The inkjet inks (a) to (i) thus obtained were printed on plain paper (X-4024) with a piezoelectric inkjet printer EM-930C manufactured by EPSON and a thermal inkjet printer Desk Jet 880C manufactured by HP. ), But all were able to be printed without any problems.
Next, a plain paper print image with EM-930C was measured with an Xrite densitometer to measure the image density and calculate the image saturation. The results are shown in Table 2.
In Table 2, the saturation of the image refers to the distance from the origin on the chromaticity diagram obtained by performing colorimetry of the solid image of the image sample with an Xrite densitometer and plotting it on the chromaticity diagram. More specifically, the a and b values on the chromaticity diagram were as follows.

  Next, 200 sheets of a solid image test pattern with an area ratio of 5% were continuously printed on A4 size plain paper with an inkjet printer EM-930C and an inkjet printer Desk Jet 880C. Observed with a magnifying glass, the number of white stripes or low-density stripes due to print bending was confirmed. The results are shown in Table 2.

Claims (23)

An ink-jet ink comprising resin fine particles (A) dyed with a fluorescent dye and having an average particle diameter of 50 to 130 nm and quinacridone pigment fine particles (B) having an average particle diameter of 50 to 130 nm, An ink-jet ink characterized by having a color tone of yellow, yellow-orange, orange, red-orange, red, pink, cerise, rose, magenta, or a mixed color thereof. 2. The ink-jet ink according to claim 1, wherein the weight ratio (A / B) of (A) to (B) is in the range of 1/2 to 8/1. The inkjet ink according to claim 1 or 2, wherein the standard deviation of the particle diameter of (A) is 40 nm or less. The inkjet ink according to any one of claims 1 to 3, wherein the constituent monomer (A) is at least one of styrene, acrylonitrile, acrylic acid, and methacrylic acid. The ink-jet ink according to any one of claims 1 to 4, wherein (B) is at least one of quinacridone, dimethylquinacridone, and dichloroquinacridone. 6. The ink-jet ink according to claim 1, comprising 5 to 20% by weight in total of (A) and (B). The inkjet ink according to claim 1, wherein (B) is dispersed with a dispersant. The inkjet ink according to claim 7, wherein the dispersant is a nonionic surfactant. The inkjet ink according to claim 8, wherein the nonionic surfactant is POE naphthyl ether. 10. The inkjet ink according to claim 9, wherein the POE naphthyl ether has an EO molar number in the range of 12 to 60. 11. The inkjet ink according to claim 7, wherein the dispersant is an anionic surfactant. The inkjet ink according to claim 11, wherein the anionic surfactant is an alkali salt of POE naphthyl ether phosphate. The inkjet according to claim 12, wherein the POE naphthyl ether phosphate alkali salt has an EO molar number in the range of 5 to 60, and the alkali species is at least one of Li, Na, and K. For ink. 14. The inkjet ink according to claim 1, wherein a weight ratio (B / dispersant) between the (B) and the dispersant is in a range of 1/1 to 1 / 0.1. An ink cartridge containing the ink-jet ink according to any one of claims 1 to 14. The ink cartridge according to claim 15, wherein the ink cartridge is detachable from the image forming apparatus. An image forming body, wherein an image is formed on a receptor using the ink-jet ink according to claim 1. An image forming method, wherein an image is formed on a receptor using the ink jet ink according to claim 1. The ink cartridge according to claim 16, wherein the image forming apparatus is an ink jet printer. The image forming method according to claim 18, wherein the inkjet ink according to claim 1 is ejected from an inkjet printer to a receiver. 21. The image forming method according to claim 20, wherein the ink jet printer is a piezo ink jet printer. 21. The image forming method according to claim 20, wherein the ink jet printer is a thermal ink jet printer. The image forming body according to claim 17, wherein the receiver is paper.