JP2003089761A - Fluorescent material ink for ink jet printer, method for forming fluorescent material image and ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare a fluorescent material ink without showing unevenness in an obtained fluorescent light-generating image on forming the fluorescent light-generating image by irradiating the image of the fluorescent material ink with an excitation light and excellent in reproducibility of the image, and to provide a method for forming the image and an ink jet printer. SOLUTION: The fluorescent material ink for the ink jet printer is obtained by mixing >=2 kinds inorganic fluorescent materials.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phosphor ink for an inkjet printer using an inorganic phosphor, a phosphor image forming method, and an inkjet printer.

[0002]

2. Description of the Related Art In recent years, fluorescent images have been widely used for various purposes such as advertisement and store interiors. For example, when an outdoor advertisement or the like is manufactured using a phosphor ink, light resistance is important, and an inorganic phosphor is used in such an application.

When an inkjet printer is used to form an image using an inorganic phosphor, if two or more kinds of phosphors are printed separately, the phosphor printed first will be covered by the phosphor printed later, resulting in When irradiated with ultraviolet excitation light such as black light, there is a problem in that desired reproducible emission in the visible region cannot be obtained, and white fluorescence in particular cannot be obtained.

Japanese Patent Laid-Open No. 2000-256591 discloses a phosphor ink suitable for an ink jet recording system using an inorganic phosphor, but a phosphor prepared by previously mixing two or more kinds of inorganic phosphors. There is no mention of obtaining a fluorescent color image using ink.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above problems that occur when a fluorescent image is formed using an ink jet printer, and when the fluorescent image is obtained by irradiating the excitation light of an inorganic phosphor, the desired visible image is obtained. An object of the present invention is to provide a phosphor ink capable of obtaining an image with good reproducibility, a fluorescent image forming method using the phosphor ink, and an inkjet printer used in the fluorescent image forming method.

[0006]

The above object of the present invention can be achieved by the following constitutions.

1. A phosphor ink for an ink jet printer, which is characterized by mixing two or more kinds of inorganic phosphors.

2. The phosphor ink for an inkjet printer according to the item 1, which is a white phosphor ink.

3. 2 by inkjet printer
A fluorescent image forming method comprising forming a fluorescent image by discharging in advance a mixture of at least one kind of inorganic fluorescent material.

4. An inkjet printer equipped with a phosphor ink containing an inorganic phosphor, wherein two or more kinds of inorganic phosphors are ejected in a premixed state.

The present invention will be described in detail below. [Phosphor ink] The phosphor ink according to the present invention may be produced by dispersing a mixture of a plurality of kinds of inorganic phosphors described below in a dispersion medium, and the plurality of kinds of inorganic phosphors in the dispersion medium, respectively. It is also possible to disperse and prepare a plurality of types of phosphor ink and mix them to produce the desired phosphor ink.

<Inorganic Phosphor and Manufacturing Method Thereof> In the inorganic phosphor of the present invention, the average particle diameter is preferably 1.0 μm or less, more preferably 0.8 μm or less, and 0.5 μm.
The following is particularly preferable, and 0.3 μm or less is most preferable. In addition, the particle size referred to here means a sphere-converted particle size. The sphere-converted particle size is a particle size represented by the particle size of the sphere, assuming a sphere having the same volume as the volume of the particle.

The particle size distribution of the inorganic phosphor is preferably narrow. Specifically, the value of the coefficient of variation [%] defined by the following formula is preferably 100% or less, and 5
It is more preferably 0% or less.

Coefficient of variation [%] = (standard deviation of particle size distribution /
In the phosphor ink of the present invention, the solid content concentration of the contained inorganic phosphor is not particularly limited, but is 1 to 50% by mass, preferably 5 to 30% by mass, more preferably 15% by mass. Is about 25% by mass.

The inorganic phosphor composition contained in the phosphor ink of the present invention is not particularly limited, and inorganic phosphors having any known composition can be selected according to the excitation light wavelength of the intended fluorescent image, the emission color, or the like. Can be used.

The composition of the inorganic phosphor is, for example, JP-A Nos. 50-6410, 61-65226 and 64-2.
2987, 64-60671, and JP-A-1-168.
Inorganic phosphors described in Japanese Patent No. 911 etc. can be used as appropriate, but as the crystal matrix thereof, Y ₂ O ₂ can be used.
Metal oxides typified by S, Zn ₂ SiO ₄ , Ca ₅ (PO ₄ ) ₃ Cl, sulfides typified by ZnS, SrS, CaS, Ce, Pr, Nd, Pm, Sm, Eu, G
A combination of rare earth metal ions such as d, Tb, Dy, Ho, Er, Tm, and Yb and metal ions such as Ag, Al, Mn, and Sb as an activator or a coactivator is used.

Particularly preferred examples of the crystal matrix are listed below. ZnS, SrS, GaS, (Zn, Cd) S, Sr
Ga ₂ S ₄ , YO ₃ , Y ₂ O ₂ S, Y ₂ O ₃ , Y ₂ SiO ₃ , S
nO ₂ , Y ₃ Al ₅ O ₁₂ , Zn ₂ SiO ₄ , Sr ₄ Al
₁₄ O ₂₅ , CeMgAl ₁₀ O ₁₉ , BaAl ₁₂ O ₁₉ , BaM
gAl ₁₀ O ₁₇ , BaMgAl ₁₄ O ₂₃ , Ba ₂ Mg ₂ Al _{12
O 22, Ba 2 Mg 4 Al} 8 O 18, Ba 3 Mg 5 Al 18 O 3 5,
(Ba, Sr, Mg) O.aAl ₂ O ₃ , (Ba, Sr)
(Mg, Mn) AlO, (Ba, Sr, Ca) (Mg,
Zn, Mn) Al ₁₀ O ₁₇ , Sr ₂ P ₂ O ₇ , (La, C
e) PO ₄ , Ca ₁₀ (PO ₄ ) ₆ (F, Cl) ₂ , (Sr,
Ca, Ba, Mg) ₁₀ (PO ₄ ) ₆ Cl ₂ , GdMgB ₅ O
₁₀ and (Y, Gd) BO _{3 and the} like. The crystal matrix and the activator or co-activator are not particularly limited in the composition of the elements, and those partially substituted with a homologous element can be used, and those that emit visible light by absorbing the blue to ultraviolet region. Any combination can be used, and it is particularly preferable to use an inorganic oxide phosphor or an inorganic halide phosphor.

The inorganic phosphors for each color used in the present invention are shown below, but the present invention is not limited to these compounds.

<Blue light emitting inorganic fluorescent compound> (BL-1) Sr ₂ P ₂ O ₇ : Sn ⁴⁺ (BL-2) Sr ₄ Al ₁₄ O ₂₅ : Eu ²⁺ (BL-3) BaMgAl ₁₀ O ₁₇ : Eu ²⁺ (BL-
_{4) SrGa 2 S 4: Ce} 3+ (BL-5) CaGa 2 S 4: Ce 3+ (BL-6) (Ba, Sr) (Mg, Mn) Al 10 O
₁₇ : Eu ²⁺ (BL-7) (Sr, Ca, Ba, Mg) ₁₀ (P
O ₄ ) ₆ Cl ₂ : Eu ²⁺ (BL-8) BaAl ₂ Si ₂ O ₈ : Eu ²⁺ (BL-9) Sr ₅ (PO ₄ ) ₃ Cl: Eu ²⁺ (BL-10) Sr ₂ P ₂ O ₇ : Eu ²⁺ (BL-11) Sr (H ₂ PO ₄ ) ₂ : Eu ²⁺ <green light emitting inorganic fluorescent compound> (GF-1) (BaMg) Al ₁₆ O ₂₇ : Eu ²⁺ , Mn
²⁺ (GF-2) Sr ₄ Al ₁₄ O ₂₅ : Eu ²⁺ (GF-3) (Sr, Ba) Al ₂ Si ₂ O ₈ : Eu ²⁺ (GF-4) (Ba, Mg) ₂ SiO ₄ : Eu ²⁺ (GF-5) Y ₂ SiO ₅ : Ce ³⁺ , Tb ³⁺ (GF-6) Sr ₂ P ₂ O ₇ -Sr ₂ B ₂ O ₅ : Eu ²⁺ (GF-7) (Ba) , Ca, Mg) ₅ (PO4 _{) 3} C
l: Eu ²⁺ (GF-8) Sr ₂ Si ₃ O ₈ -2SrCl ₂ : Eu ²⁺ (GF-9) Zr ₂ SiO ₄ , MgAl ₁₁ O ₁₉ : C
e ³⁺ , Tb ³⁺ (GF-10) Ba ₂ SiO ₄ : Eu ²⁺ (GF-11) Ca ₂ Y ₈ (SiO ₄ ) ₆ O ₂ : Tb ³⁺ (GF-12) Y ₃ Al ₅ O ₁₂ : Tb ³⁺ (GF-13) La ₃ Ga ₅ SiO ₁₄ : Tb ³⁺ <Red-emitting inorganic fluorescent compound> (RL-1) Y ₂ O ₂ S: Eu ³⁺ (RL-2) (Ba, Mg ) ₂ SiO ₄ : Eu ³⁺ (RL-3) (Ba, Mg) Al ₁₆ O ₂₇ : Eu ³⁺ (RL-4) (Ba, Ca, Mg) ₅ (PO ₄ ) ₃ C
l: Eu ³⁺ (RL-5) YVO ₄ : Eu ³⁺ (RL-6) CaS: Eu ³⁺ (RL-7) YAlO ₃ : Eu ³⁺ (RL-8) Ca ₂ Y _{8 (} SiO ₄ ). ₆ O ₂ : Eu ³⁺ (RL-9) LiY ₉ (SiO ₄ ) ₆ O ₂ : Eu ³⁺ (RL-10) YVO ₄ : Eu ³⁺ Bi ²⁺ (RL-11) Gd ₂ O ₂ S: ^{Eu 3+ (RL-12) CaS} : Eu 3+ Cl - (RL-13) (CaMg) 3 (PO 4) 2: Sn 2+ after, say blue, green, red B, G, also R.

In addition to the above compounds, there are inorganic phosphors used in three-wavelength fluorescent lamps, calcium halophosphate, and the like.

The method for producing the inorganic phosphor contained in the phosphor ink of the present invention is not particularly limited, and as a method for synthesizing without lowering the luminous efficiency, for example, a method for synthesizing a composite metal oxide, spray pyrolysis. Various publicly known manufacturing methods such as a method can be applied. As a method for synthesizing the composite metal oxide, a solid phase method in which powdery oxides of two or more kinds of metals are mixed and subjected to high-temperature heat treatment, and a precursor of the composite metal oxide is synthesized from a solution in which raw materials are dissolved Then, a liquid phase method in which the precursor thus obtained is separated, and the resulting precursor is subjected to an oxidation treatment is exemplified.

The liquid phase method represents a general reaction method in a liquid phase such as a coprecipitation method, a reaction crystallization method and a sol-gel method.
In the present invention, the precursor can be appropriately selected, but it is particularly preferable to synthesize the precursor by the sol-gel method.

Here, a method for producing an inorganic phosphor by the sol-gel method will be specifically described. The sol-gel method is, for example, an element (metal) used as a matrix or an activator or a co-activator, for example, a metal alkoxide (for example, Si (OCH ₃ ) ₄ etc.) or a metal complex (for example, Eu ³⁺
(CH ₃ COCH═C (O ⁻ ) CH ₃ ) ₃ etc.) or a double alkoxide (for example, Al (OBu) ₃ in 2-butanol solution prepared by adding a simple metal to an organic solvent solution thereof, to which metallic magnesium is added. Made by Mg [Al (OBu)
₃ ] ₂ ), etc.), a metal halide, and a metal salt of an organic acid are mixed in a reaction vessel in a necessary amount, and thermally or chemically hydrolyzed and polycondensed to synthesize.

Any solvent may be used when the sol-gel method is applied as long as the reaction raw materials are dissolved, but ethanol is preferable from the viewpoint of environment. The reaction initiator may be an acid or a base, but a base is preferred from the viewpoint of hydrolysis rate. As the type of base, NaO is used if the reaction starts.
Although general ones such as H and ammonia can be used, ammonia is preferable from the viewpoint of easy removal. As a method of mixing the reaction initiator, it may be added to the mother liquor in advance, may be added at the same time as the raw material, or may be added to the raw material in advance. The method of addition is preferred. When using a plurality of reaction raw materials, the order of addition of the raw materials may be the same or different,
Depending on the activity, the proper order can be assembled appropriately,
A double alkoxide may be formed depending on the case.

Any solvent may be used when the coprecipitation method or the reaction crystallization method is applied as long as the reaction raw materials are dissolved, but water is preferable from the viewpoint of easy control of the supersaturation degree. When using a plurality of reaction raw materials, the order of adding the raw materials may be the same or different, and an appropriate order can be appropriately assembled depending on the activity. When synthesizing precursors by liquid phase method, temperature, addition speed, stirring speed, pH during the reaction
Etc. may be controlled, and ultrasonic waves may be applied during the reaction. A surfactant or a polymer may be added to control the particle size. It is also one of the preferred embodiments that the liquid is concentrated or aged as necessary after the addition of the raw materials.

After synthesizing the precursor by the liquid phase method, if necessary, various steps such as filtration, washing, drying, calcination, dispersion and the like may be carried out, or classification may be carried out. Although any known method may be used as the firing method, it is preferable to use a rotary kiln. The firing temperature and time may be adjusted so that each phosphor has the highest performance, and the atmosphere may also be an oxidizing gas, a reducing gas, a sulfurizing gas, an inert gas or the like depending on the composition.

The dispersing method is, for example, a high speed stirring impeller type dispersing machine, a colloid mill, a roller mill, a ball mill, a vibrating ball mill, an attritor mill, a planetary ball mill, a sand mill, and the like. ) And a shearing force, or a dry type disperser such as a cutter mill, a hammer mill and a jet mill, an ultrasonic disperser, a high pressure homogenizer and the like. Among these, in the present invention, it is particularly preferable to use a wet media type disperser that uses a medium, and it is more preferable to use a continuous type wet media type disperser capable of continuously performing dispersion treatment. A mode in which a plurality of continuous wet media type dispersers are connected in series is also applicable. As used herein, "continuously dispersible treatment" means that at least the inorganic phosphor and the dispersing medium are dispersed in the disperser while being supplied to the disperser without interruption at a constant amount ratio per hour, and are produced in the disperser. It refers to a form in which the dispersed product is extruded into the collection container and discharged from the disperser without interruption. In the method for producing an inorganic phosphor of the present invention, when a wet media type disperser using a medium (media) as a dispersion treatment step is used, the dispersion chamber container (vessel) can be appropriately selected from a vertical type and a horizontal type. Is.

<Dispersion Medium, Additive> As the dispersion medium of the phosphor ink for producing the fluorescent image of the present invention, water, various organic solvents, or a mixture thereof may be used according to its use. be able to. Further, in that case, it is possible to use various binders and surfactants as required.

In the phosphor ink for producing a fluorescent image of the present invention, an electric conductivity adjusting agent can be used. For example, an inorganic salt such as potassium chloride, ammonium chloride, sodium sulfate, sodium nitrate, sodium chloride, or triethanolamine. Aqueous amines and the like.

In the fluorescent ink for producing a fluorescent image of the present invention, the viscosity is further increased depending on the ejection stability, compatibility with print heads and ink cartridges, storage stability, image storability, and other purposes for improving various performances. An adjusting agent, a specific resistance adjusting agent, a film forming agent, an ultraviolet absorber, an antioxidant, an anti-fading agent, a rust preventive, a preservative and the like can be added.

[Fluorescent Image Forming Method, Inkjet Printer] A fluorescent image forming method using the phosphor ink and an inkjet printer used in the fluorescent image forming method will be described. The inkjet head of the inkjet printer used in the present invention may be an on-demand system or a continuous system. Also,
As a discharge method, an electro-mechanical conversion method (for example, a single cavity type, a double cavity type, a bender type, a piston type, a shear mode type, a shared wall type, etc.), an electric-heat conversion method (for example, a thermal inkjet type) , Bubble jet (registered trademark) type, electrostatic attraction method (for example, electric field control type, slit jet type, etc.), discharge method (for example, spark jet type, etc.), and the like. Any of the ejection methods may be used.

The excitation light used as the light source of the fluorescence image is not particularly limited as long as the visibility of the fluorescence image is good, but a light source with a wavelength of 254 nm and a wavelength of 365 which are used relatively often are used.
It is preferable to apply a black light having a wavelength of about 405 nm, and purplish blue having a wavelength of about 405 nm may be applied to the excitation light depending on the phosphor.

The place where the fluorescence image of the present invention is used is indoors,
It can be used outdoors or in any environment such as around water,
An environment where there is a small amount of ambient light, such as daylight, or where excitation light can be actively emitted is preferable.
For example, if it is indoors, underground or a place where external light is less incident, and if it is outdoors, safety display, road display, advertisement, fleet marking and the like can be mentioned. The "daylight" in the present invention mainly means sunlight, fluorescent lamps, etc., and collectively refers to visible light and a slight amount of ultraviolet rays contained therein.

The white fluorescence described in claim 2 of the present invention means theoretically the white point of the CIE chromaticity diagram described in, for example, the Color Science Handbook (edited by the Japan Color Association), that is, the CIE in FIG. Issuance color corresponding to the white point P in the chromaticity diagram,
Practically, it means the emission color of B light source, C light source, E light source, etc., which is internationally recognized as a standard illumination light source.

It should be noted that x and y in FIG. 1 are coordinates of the chromaticity diagram, x is a horizontal axis coordinate, y is a vertical axis coordinate, A is a spectrum locus (μm), and the coordinates of the white point P are. Theoretically x
= Y = 0.33.

[0036]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Example 1 << Synthesis of Inorganic Phosphor 1 (Sr ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu ²⁺ ) >> In the production of the inorganic phosphor 1, the primary particles were prepared by the liquid phase method flow as shown below. Was produced. Strontium carbonate, sodium hydrogen phosphate, and europium chloride were each dissolved in pure water, and these were dropped into water containing ammonia with stirring at a rate of about 1 ml / min to obtain a precipitate. The obtained precipitate was collected by filtration and dried at room temperature.

The dried product was heat-treated at 1200 ° C. for 2 hours in an N ₂ atmosphere containing 5% by mass of H ₂ to obtain an inorganic phosphor 1.

<< Inorganic phosphor 2 (Ba ₂ SiO ₄ : Eu ²⁺ )
Synthesis of tetraethoxysilane 1.34 × 10 ^-1 mol
And europium (trivalent) acetylacetonate complex 1.
A solution of 00 × 10 ^-2 mol dissolved in 300 ml of ethanol was used as solution A, and this solution A was added with ammonia 5.00
× 10 ^-2 mol of added water - ethanol (1: 1,40
0 ml) was added dropwise with stirring at a rate of about 1 ml / min to prepare a sol. The obtained sol was concentrated to about 1/15 with an evaporator, and 500 ml of a 0.33 mol / L barium nitrate salt aqueous solution was added thereto to cause gelation,
A wet gel (1) was obtained.

The wet gel (1) obtained was placed in a closed container,
It was aged at 90 ° C. for 10 hours. Filter paper (Advantec
5A) was collected by filtration and dried at 50 ° C. for 10 hours. A sintering inhibitor (aluminum oxide C, manufactured by Aerosil Co., Ltd.) was mixed with the dried precursor in an amount of 1% by mass based on the mass of the precursor, and the mixture was mixed in an atmosphere of N ₂ containing 5% by mass of H ₂ to 1000
Inorganic phosphor 2 was obtained by heat treatment for 2 hours at ℃.

<< Inorganic phosphor 3 (YVO ₄ : Eu ³⁺ B
Synthesis of i ²⁺ ) >> In the production of the inorganic phosphor 3, primary particles were produced by a liquid phase method flow as shown below.

(Preparation of solution A) The following raw materials were accurately weighed, mixed and dissolved.

[0043] _{Y (CH 3 COCHCOCH 3) 3} · 3H 2 O 40.9g Eu (CH 3 COCHCOCH 3) 3 ( Preparation of solution B) 2.43 g EtOH 800 ml following ingredients were accurately weighed, mixed, dissolving .

VO (CH ₃ COCHCOCH ₃ ) ₂ 26.5 g MeOH 1000 ml (Preparation of solution C) The following raw materials were accurately weighed, mixed and dissolved.

Bi (NO ₃ ) ₃ 0.97 g H ₂ O 810 ml Liquid A and liquid B are mixed at 60 ° C. 10m of C liquid to the liquid
A sol was prepared by adding at a rate of 1 / min with stirring. After that, it is aged at 60 ° C for 10 hours, and then filtered (Adv
antec 5A) and collected by filtration at 50 ° C.
And dried for 10 hours. A sintering inhibitor (aluminum oxide C, manufactured by Aerosil Co., Ltd.) is mixed with the precursor obtained by drying in an amount of 1% by mass of the mass of the precursor, and N ₂ containing 5% by mass of H ₂ is mixed.
Inorganic phosphor 3 was obtained by heat treatment at 1200 ° C. for 2 hours in the atmosphere.

<< Preparation of Phosphor Ink >> (Preparation of B Phosphor Ink) The following composition was sand mill dispersed to obtain an inorganic phosphor-containing dispersion. For the dispersion, a bead mill disperser (VMA-GETZM) was used after obtaining a coarse dispersion through a preliminary dispersion process.
A solid fine particle dispersion was prepared using DISPERMATT SL-C5 manufactured by ANN. In the bead mill dispersion, zirconia beads having an average particle size of 0.3 mm were used, and the filling rate of the beads was 80% by mass.

Inorganic phosphor 1 20 g Nonipol 400 (manufactured by Sanyo Kasei Co., Ltd.) 5 g Joncyl62 (manufactured by Johnson Polymer Co., molecular weight 8500) 2 g acetylenic glycol 1 g ion-exchanged water 50 g While stirring 35 g of this dispersion liquid, diethylene glycol 8 g, 1 , 5-Pentanediol (7 g) and ion-exchanged water (50 g) were added dropwise over 30 minutes to obtain a B phosphor ink.

(Preparation of G phosphor ink) A G phosphor ink was prepared in the same manner as the B phosphor ink except that 20 g of the inorganic phosphor 2 was used instead of the inorganic phosphor 1.

(Preparation of R phosphor ink) An R phosphor ink was prepared in the same manner as the B phosphor ink except that 20 g of the inorganic phosphor 3 was used instead of the inorganic phosphor 1.

(Preparation of White Phosphor Ink) B phosphor ink, G phosphor ink, and R phosphor ink were weighed in appropriate amounts, and the emission wavelength was CIExy when black light (peak wavelength 365 nm) was irradiated as excitation light. A white phosphor ink was prepared by mixing in advance so as to have a value as close as possible to the coordinate x = y = 0.33 (white fluorescence theoretical value) in the chromaticity diagram.

<< Preparation of Samples 1 and 2 >> MC manufactured by Epson Corporation
Printing was performed on a black paper (plain paper) with 1 cm square by using a -2000 inkjet printer. Sample 1 was prepared by printing using the above phosphor white ink,
Sample 2 was prepared by superimposing printing of three color inks of B, G, and R phosphors. When the B, G, and R phosphor three-color inks are overlaid and printed, the phosphor inks of the respective colors are preliminarily set so as to have the same mixing ratio of the B, G, and R phosphor three-color inks of the white phosphor ink. The discharge amount of was adjusted and printing was performed.

<< Evaluation Method >> Continuous printing of Samples 1 and 2
The emission wavelength when black light (peak wavelength 365 nm) was irradiated as excitation light on the obtained printed image was measured 100 times, and the average value of the coordinates x and y of each CIE chromaticity diagram and the coordinate x, Variation of y (standard deviation)
Was calculated and the results are shown in Table 1. The following measuring method was used for measuring the emission wavelength. The measurement was performed in a dark room.

Type of measurement method Single beam Type of color matching function X ₁₀ Y ₁₀ Z ₁₀ color system (10 degree field of view) Standard type of light Black light (FL40SBLB-A manufactured by Toshiba Lighting & Technology Corporation) Illumination and light reception Geometric conditions 0-45 3 Stimulus value calculation method W10 measuring instrument MCPD-1000 (manufactured by Otsuka Electronics) Effective wavelength 400-700 nm

[0054]

[Table 1]

From Table 1, the fluorescent image using the white phosphor ink according to the present invention can stably obtain a high-quality image with no variation in the emission color, but the three color inks B, G and R are superposed. It can be seen that in printing, there is a large variation in the emission color of the fluorescent image, and it is not practical.

Example 2 (Preparation of Y Phosphor Ink) G phosphor ink and R phosphor ink were weighed in appropriate amounts and irradiated with black light (peak wavelength 365 μm) as excitation light, the emission wavelength was CIE xy chromaticity. In the figure, coordinates (x, y) = (0.40,
The Y phosphor ink was prepared by premixing so as to have a value as close as possible to 0.53).

<< Preparation of Samples 3 and 4 >> MC manufactured by Epson Corporation
Using the -2000 ink jet printer, black paper (plain paper) was printed with the above Y phosphor ink to prepare sample 3, and G and R two-color phosphor ink was superimposed and printed to prepare sample 4. Further, in each of the above-mentioned samples, the printing was performed at 1 cm square. In the case of overlapping printing of the G and R two-color phosphor inks, the ejection amount of each color phosphor ink is adjusted in advance so as to be the same as the mixing ratio of the G and R two-color phosphor inks of the Y phosphor ink. Was printed.

<Evaluation Method> By the same method as in Example 1, the average value of the coordinates x and y and the variation (standard deviation) of the coordinates x and y in the CIE chromaticity diagram were calculated, and the results are shown in Table 2. .

[0059]

[Table 2]

From Table 2, the fluorescent emission image using the Y phosphor ink according to the present invention is stable and a high-quality image can be obtained stably, but in the superposition printing of the G and R two-color phosphor inks. It can be seen that the fluorescence emission image has a large variation and is not practical.

Example 3 (Preparation of M phosphor ink) B phosphor ink and R phosphor ink were weighed in appropriate amounts and irradiated with black light (peak wavelength 365 μm) as excitation light, the emission wavelength was CIE xy chromaticity. In the figure, coordinates (x, y) = (0.35,
0.15) was mixed in advance so as to have a value as close as possible to 0.15) to prepare an M phosphor ink.

<< Preparation of Samples 5 and 6 >> MC manufactured by Epson Corporation
Using the -2000 inkjet printer, printing was performed on the black paper (plain paper) with the above-mentioned M phosphor ink to prepare sample 5, and B and R two-color phosphor ink was superimposed and printed to prepare sample 6. Further, in each of the above-mentioned samples, the printing was performed at 1 cm square. In the case of overlapping printing of the B and R two-color phosphor inks, the ejection amount of each color phosphor ink is adjusted in advance so that the mixture ratio of the B and R two-color phosphor inks of the M phosphor ink is the same. Was printed.

<< Evaluation Method >> By the same method as in Example 1, the average value of the coordinates x and y and the variation (standard deviation) of the coordinates x and y in the CIE chromaticity diagram were calculated, and the results are shown in Table 3. .

[0064]

[Table 3]

From Table 3, the fluorescent emission image using the Y phosphor ink according to the present invention is stable and a high-quality image can be obtained stably. However, in the superposition printing of the G and R two-color phosphor inks. It can be seen that the fluorescence emission image has a large variation and is not practical.

Example 4 (Preparation of C phosphor ink) An appropriate amount of each of B phosphor ink and G phosphor ink was weighed and irradiated with black light (peak wavelength 365 μm) as excitation light, the emission wavelength was CIE xy chromaticity. In the figure, coordinates (x, y) = (0.10,
C phosphor ink was prepared by premixing so as to have a value as close as possible to 0.40).

<< Preparation of Samples 7 and 8 >> MC manufactured by Epson Corporation
Using a -2000 inkjet printer, printing was performed on the black paper (plain paper) with the C phosphor ink described above to prepare Sample 7, and B and G two-color phosphor inks were superimposed and printed to prepare Sample 8. Further, in each of the above-mentioned samples, the printing was performed at 1 cm square. In the case of overlapping printing of the B and G two-color phosphor inks, the discharge amount of each color phosphor ink is adjusted in advance so that the mixing ratio of the C and C two-color phosphor inks is the same. Was printed.

<< Evaluation Method >> By the same method as in Example 1, the average value of the coordinates x and y and the variation (standard deviation) of the coordinates x and y in the CIE chromaticity diagram were calculated, and the results are shown in Table 4. .

[0069]

[Table 4]

From Table 4, the fluorescent emission image using the C phosphor ink according to the present invention is stable and a high-quality image can be obtained stably, but in the superposition printing of the B and G two-color phosphor inks. It can be seen that the fluorescence emission image has a large variation and is not practical.

[0071]

As demonstrated by the examples, according to the phosphor ink, the image forming method and the ink jet printer of the present invention, when an image of the phosphor ink is irradiated with excitation light to form a fluorescence emission image, It has excellent effects such as no variation in the fluorescence emission image and excellent image reproducibility.

[Brief description of drawings]

FIG. 1 is a CIE xy chromaticity diagram.

[Explanation of symbols]

x, y coordinates of chromaticity diagram A spectrum locus (μm) P white point

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Naohiro Okada             Konica Stock Market, 1 Sakura-cho, Hino City, Tokyo             In-house (72) Inventor Hideki Hoshino             Konica Stock Market, 1 Sakura-cho, Hino City, Tokyo             In-house (72) Inventor Tokiko Ohara             Konica Stock Market, 1 Sakura-cho, Hino City, Tokyo             In-house F-term (reference) 2C056 FC02                 2H086 BA01 BA02 BA53 BA55                 4J039 BE01 EA18 EA28 GA24

Claims (4)

[Claims] 1. A phosphor ink for an ink jet printer, which comprises mixing two or more kinds of inorganic phosphors. 2. The phosphor ink for an inkjet printer according to claim 1, which is a white phosphor ink. 3. A fluorescent image forming method, which comprises ejecting a mixture of two or more kinds of inorganic phosphors in advance with an inkjet printer to form a fluorescent image. 4. An inkjet printer equipped with a phosphor ink containing an inorganic phosphor, wherein two or more kinds of inorganic phosphors are ejected in a premixed state.