JP2003261869A - Luminous particles, manufacturing method therefor and use of the luminous particles - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide new luminous particles coated with uniform and dense silica equal to an uncoated article in initial luminocity in addition to the enhancement of humidity resistance and excellent in the dispersibility/moldability generating no blocking of particles. <P>SOLUTION: The luminous particles are coated with a thin silica film (first film) having a refractive index of 1.435 or more and further coated with a silica film (second film) with a refractive index of 1.45 or more derived from a polysilazane so as to coat the first film. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a luminescent particle having excellent moisture resistance by surface treatment and having excellent dispersibility without causing a decrease in initial luminescence light intensity, and a method for producing the same.

[0002]

2. Description of the Related Art Luminescent particles are used in various applications such as flat panel displays, electronic devices, lighting equipment, ornaments such as watches and fashion, and cathode ray tubes.
The luminescent particles referred to in the present invention include fluorescent particles, phosphorescent particles, phosphorescent particles and the like. Examples of stimulation methods (excitation energy sources) for light emission include ultraviolet rays, electron beams, X-rays / radiation, electric fields, and chemical reactions. As the phosphor, zinc sulfide (Zn
S), calcium sulfide (CaS) and strontium sulfide (SrS) as base materials, and various activators and co-activators such as copper, silver and manganese for the purpose of multicoloring and high brightness. Has been added.

In order to put these luminescent particles into practical use, it is important to provide a technique of extending the life, increasing the brightness and imparting high dispersibility.

Particularly from the viewpoint of extending the service life, it is essential to improve the moisture resistance. Luminescent particles generally have poor moisture resistance,
Not only the contact with water but also the contact with water vapor in the atmosphere has a serious adverse effect on the light emission characteristics.
Therefore, when used for a long time in a highly humid place, the luminosity of the luminescence is drastically reduced due to the absorption of moisture. Further, if light emission is continued in a moisture-absorbed state, the light emitting surface is rapidly blackened and the brightness is lowered. Especially in electroluminescence (EL), for example, in the case of a ZnS-based phosphor, Zn is reduced and precipitated, or the binder is carbonized in the vicinity of the transparent electrode due to a kind of chemical reaction caused by moisture and electric energy that have penetrated into the light-emitting layer. To do

The conventional technique for making this moisture resistant will be described by taking the case of electroluminescence (EL) as an example.

The EL luminescent particles are generally used as a dispersion type EL device, and the basic structure thereof is a luminescent layer formed by dispersing the luminescent particles in an organic binder having a high dielectric constant such as cyanoethyl cellulose. , Is laminated on a dielectric layer (insulating layer) for increasing the withstand voltage of the element and ensuring stable operation, and further provided with electrodes (at least one of which is a transparent electrode) for applying a voltage on both surfaces thereof.

Therefore, for moisture resistance, it has been attempted to sheet the element with a moisture-proof film such as trifluoromonochloroethylene polymer, but the element becomes thicker and more expensive, and further includes a dark border and a release layer. There are problems such as.

Attempts have also been made to coat the luminescent material itself to improve its moisture resistance. JP-A-4-178
In Japanese Patent No. 486, the phosphor surface is coated with a phosphate of a metal such as magnesium, calcium or strontium,
Then, a method for producing a water-resistant phosphor by rapid heating by plasma treatment is disclosed. However, in the case of coating with these phosphates, the salt is simply deposited, and the coating state cannot be said to be uniform at all. Of course, there is no compactness, so that a complicated and costly process such as plasma process is required. Moreover, in order to obtain a uniform film without pinholes by the plasma treatment, the particles are inevitably adhered to each other, resulting in poor dispersibility and moldability.

In Japanese Patent Application Laid-Open No. 4-230996, the phosphorescence particles are heated in the range of 25 ° C. to 170 ° C. and coated with an oxide by the CVD method in the presence of an oxide precursor material. Luminescent phosphorescent particles and methods of making the same are disclosed. But CVD
In order to coat the oxide uniformly by the method, expensive equipment is required, which is not economical. Further, since it takes a long processing time, interparticle sticking is likely to occur, and the tendency becomes stronger in low temperature CVD. Therefore, when the phosphor particles are crushed or dispersed in an organic binder, pinholes in the coating film are generated and oxides are peeled off, resulting in poor moldability.

The sticking of the light-emitting particles to each other causes problems such as hindering the formation of a thin light-emitting layer, non-uniform light output, and poor dispersibility at the time of manufacturing the EL element, resulting in sedimentation. Japanese Unexamined Patent Publication No. 8-236274 discloses coating phosphor particles with a ceramic coating derived from polysilazane. Specifically, zinc sulfide powder is turbid in a polysilazane solution and dried with a spray dryer to obtain coated particles. Polysilazane causes mass increase when silica is converted, and volume shrinkage is small, so cracks are less likely to occur even in thick films.However, when directly coating zinc sulfide, which is the base material, the adhesion of the polysilazane film to the base material is poor and it is uniform. In addition, it is not possible to obtain a good coating, and interparticle adhesion tends to occur. As a result, pinholes in the coating film occur and the coating film peels off when the phosphor particles are crushed or dispersed in an organic binder, resulting in poor moldability. As a result, the improvement in moisture resistance is insufficient.

The present inventor has previously improved the moisture resistance by coating with a specific dense and uniform thin film silica, or by further nitriding or fluorinating the surface thereof. Disclosed are luminescent particles having a small decrease in luminescence intensity and excellent dispersibility. However, improvement in moisture resistance is still required. Although the moisture resistance improves as the silica content increases, an excessive increase in the content causes a decrease in the initial luminance. Also, of course, an increase in silica content means an increase in film thickness,
When the film thickness is 0.5 μm or more, the film shrinks during drying,
Easy to crack.

Therefore, in the coating of the phosphor particles, not only the degree of improvement in moisture resistance but also sufficient moisture resistance is imparted even in a thin film in which cracks are hard to occur, or cracks are generated even in a thick film. There is no need for a coating method, and it does not cause a decrease in initial luminescence light intensity, there is no need for crushing because there is no sticking of particles, coating adhesion and particle dispersibility are excellent, and moldability is excellent. It is necessary and none has ever met all of these.

[0013]

DISCLOSURE OF THE INVENTION In addition to improving moisture resistance, the present invention has an initial luminescence light intensity equivalent to that of an uncoated product, good adhesion of a film (film), and dispersibility without particle adhesion. An object of the present invention is to provide new luminescent particles which are excellent in moldability and which are uniform and coated with a silica thin film.

[0014]

Means for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the present inventor has formed a film (first film) with a dense thin film silica having a refractive index of 1.435 or more, and the first film. Further, the phosphor particles coated with a dense silica film having a refractive index of 1.45 or more derived from polysilazane (second coating) have moisture resistance improved, and the initial luminescence luminous intensity is equal to that of the uncoated product. In addition, they have found that they have good film adhesion and excellent dispersibility and moldability without particle adhesion, and have completed the present invention. The luminescent particles referred to here are
It contains fluorescent, phosphorescent, or phosphorescent particles. Surprisingly, when only the first coating was applied, or when only the second coating was applied to the surface of the phosphor particles, an improvement in moisture resistance that could never be obtained was observed.

In the present invention, the "coating" includes not only a film covering the entire surface, but also a film formed partially.

That is, the present invention relates to the following items. 1) A thin film silica having a refractive index of 1.435 or more is coated (first coating), and a polysilazane-derived silica film having a refractive index of 1.45 or more is further coated (second coating) on the first coating. 2) The thickness of the silica film of the first coating and the second coating is 0.0
2 to 1 μm of the luminescent particles described in 1 above, 3) the luminescent particle of 1 or 2 above in which the polysilazane is perhydropolysilazane, 4) the number average molecular weight of the polysilazane is 100 to 500
The phosphor particles according to the above 3, which is in the range of 00, 5) A silica film having a first coating film thickness of 0.01 to 0.5 μm and a second coating film thickness of 0.01 to 0.5 μm. 5. The coated phosphor particles according to any one of 1 to 4 above, 6) having a film thickness of 0.01 to 0.5 μm, a refractive index of 1.45 or more, and an infrared absorption spectrum thereof. 1150 to 1250 cm ^-1 and 1000 to 1100
The ratio I of the absorption peak intensity at cm ⁻¹ (I = I ₁ / I ₂ : I ₁ is the absorbance of the absorption peak at 1150 to 1250 cm ⁻¹ , I ₂
Is the absorbance of the absorption peak at 1000 to 1100 cm ^-1 ) is less than 0.2, and the phosphor particle according to any one of 1 to 5 above, which is coated with a silica film (second coating) derived from polysilazane, 7). The film thickness is 0.01 to 0.5 μm, the refractive index is 1.435 or more, and the infrared absorption spectrum thereof is 1150 to 1250 cm ⁻¹ and 1000 to 110.
The ratio I (I = I ₁ / I ₂ : I ₁ of the absorption peak intensities at 0 cm ⁻¹ )
Is the absorbance of the absorption peak at 1150 to 1250 cm ⁻¹ , I
₂ is the absorbance of the absorption peak at 1000 to 1100 cm ^-1 )
7. The phosphor particle according to any one of 1 to 6 above, which is coated with a silica film (first coating) having a value of 0.2 or more; 8) Any of above 1 to 7, wherein the outermost surface is hydrophobized. 9) 1) Silica acid containing no organic group and halogen, or a silicic acid precursor capable of forming the silicic acid, and 2) water, 3) alkali, and 4) a composition for forming a silica film containing at least an organic solvent. Step of contacting the object with the phosphor particles, then 1)
A method for producing phosphor particles, comprising the step of bringing the phosphor particles into contact with a composition for forming a silica film containing at least polysilazane and 2) an organic solvent, 3) an amine and / or a metal ion catalyst, 10) 1) an organic group And a step of bringing phosphor particles into contact with a silica coating forming composition containing at least silicic acid containing no halogen or silicic acid or a silicic acid precursor capable of forming the silicic acid and 2) water, 3) alkali, and 4) organic solvent, and then 1 ) Polysilazane and 2) Organic solvent, 3) A step of bringing the phosphor particles into contact with a composition for forming a silica film containing at least an amine and / or a metal ion catalyst and bringing them into contact with water vapor, 11. ) The polysilazane has a number average molecular weight of 100 to 50.
9. The method for producing phosphor particles according to the above 9 or 10, which is polysilazane, 12) 1) Silicic acid containing no organic group and halogen, or a silicic acid precursor capable of producing the silicic acid, and 2) water, 3)
In the step of bringing the phosphor particles into contact with the composition for forming a silica coating film containing at least an alkali, 4) an organic solvent, the water / organic solvent ratio (based on the charging capacity) is set to 0.1.
10 to 10 and a silicic acid concentration of 0.0001 to 5 mol / liter are used, and the surface of the phosphor particles is selectively coated with silica by the contact, and then dried to give the first coating. 13. The method for producing the phosphor particle according to any one of 9 to 11 above, 13) The phosphor particle according to any one of 1 to 8 above, wherein the light emission of the phosphor particle is fluorescence, 14) Luminescence 13. The method for producing a phosphor particle according to any one of 9 to 12 above, wherein the emission of the body particle is fluorescence. 15) A dispersion type using the phosphor particle according to any one of 1 to 8 above. Light emitting device, 16) Dispersion type electroluminescence device using the light emitting particle according to any one of 1 to 8 above, 17) Light emitting particle is zinc sulfide (ZnS), calcium sulfide (CaS), strontium sulfide. 18. The luminescent particles as described in any one of 1 to 8 above, wherein 18 or more are selected from the group consisting of um (SrS) as a raw material, and the luminescent particles are zinc sulfide (ZnS) and calcium sulfide ( CaS), strontium sulfide (SrS) 1 or more types selected from a raw material, The manufacturing method of the luminescent particle in any one of said 9 thru | or 12 characterized by the above-mentioned.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in more detail, but the present invention is not limited thereto.

First, the luminescent particles that can be used in the present invention (the luminescent particles referred to herein are fluorescent, phosphorescent,
Alternatively, it contains phosphorescent particles. ) Is not particularly limited, but usually
Zinc sulfide (ZnS), calcium sulfide (CaS), strontium sulfide (SrS) and other sulfides, Y ₂ O ₂ S, L
An oxysulfide such as n ₂ O ₂ S (Ln is at least one selected from the group consisting of Y, Gd and La), MGa ₂ S ₄ (M is S
at least one selected from the group of r, Ca, Ba and Mg), etc., (Ba, Eu) O
There is a material in which an aluminate compound such as MgO · 5Al ₂ O _{3 is used} as a base material. Further, for example, in a zinc sulfide-based electroluminescent material, copper sulfide (CuS), zinc selenide (ZnSe) and cadmium sulfide (CdS) are used.
And a solid solution of the zinc sulfide crystal structure. Further, various activators or co-activators such as copper, silver and manganese may be added for the purpose of increasing the number of colors and increasing the brightness. For example, in a zinc sulfide-based electroluminescent material, Cu
Those containing and I emit blue green, those containing Cu and Al emit green, and those containing Cu, Mn and Cl emit yellow orange.

Next, the silica coating of the present invention and the method for producing the same will be described.

(First coating) The silica-coated phosphor particles of the present invention are 1150 to 1250 cm ^-1 and 1000 to 1100.
cm ratio of the absorption peak intensity of the infrared absorption spectrum in _{^{-1 I (I = I 1 /}} I 2: I 1 is 1150～1250Cm ^-1
Of the absorption peak due to Si-OH, I ₂ of 100
The absorption peak of Si—O—Si at ⁰ to 1100 cm ⁻¹ is 0.2 or more, and the refractive index is 1.43.
It has a silica coating (first coating) of 5 or more. This first coating is a dense thin-film silica that adheres well to the complicated particle shape of the light-emitting body that is the base material, and has good adhesion and coating properties even at an extremely thin film thickness. The term "dense" as used herein means that the formed silica film has a high density, is uniform, and has no pinholes or cracks.

The first coating film of the present invention has a role of 1) as a hydrophilic undercoat layer for ensuring the adhesion of the second coating film, which will be described later. By using a thin film silica that exhibits sufficient adhesion to the coating and has 2) denseness, it is possible to synergistically improve moisture resistance with the second coating having a small thickness. Usually, a silica coating obtained by firing by a sol-gel method or the like or a CVD method has a thickness of 1150 to 1250 cm ^-1 and 1000.
The absorption peak intensity ratio I of the infrared absorption spectrum at ˜1100 cm ⁻¹ is generally less than 0.2. And I
It is known that the value of is generally changed by firing to change the chemical bond or the functional group, and the hydrophilicity and oil absorption of the silica film are changed. Further, the silica film obtained without firing by the usual sol-gel method has a refractive index of less than 1.435 and a low denseness. Here, it is generally said that the denseness and the refractive index of the silica film have a positive correlation. (For example,
C. JEFFERY Brinker, SOL-GEL
SCIENCE, 581-583, ACADEMIC
(PRESS (1990)) Further, if the coating film contains an alkali metal such as sodium, the silica film may be dissolved under a hot and humid atmosphere. A silica coating having an extremely low content of alkali metal can be used.
This means that there is almost no deterioration of the coating film when it is brought into contact with water vapor in low temperature ceramicization of the second coating film, which will be described later, and it can be suitably used.

The silica-coated phosphor particles of the present invention contain silicic acid containing no organic group and halogen or a precursor capable of forming the silicic acid, and water, an alkali and an organic solvent.
The water / organic solvent ratio is in the range of 0.1 to 10 by volume,
And a method of contacting the phosphor particles with a composition for forming a silica film having a silicon concentration in the range of 0.0001 to 5 mol / liter to selectively deposit dense thin film silica on the surface of the phosphor particles. It is a silica-coated phosphor particle.

Particularly, 1150 to 1250 cm ^-1 and 100
The ratio I (I = I ₁ / I ₂ : I ₁ of the absorption peak intensities of the infrared absorption spectrum at ^{0 to} 1100 cm ⁻¹ is 1150 to ₁
Absorbance of absorption peak by Si-OH at 250 cm ^-1 ,
I ₂ is a silica-coated luminescent material coated with dense thin film silica having an absorption peak of Si—O—Si of 1000 to 1100 cm ⁻¹ of 0.2 or more and a refractive index of 1.435 or more. It is a particle.

The silicic acid containing no organic group and halogen used in the composition for forming a silica film in the present invention is, for example, a chemical dictionary (Kyoritsu Shuppan Co., Ltd., published on March 15, 1969, No. 7 edition). The orthosilicic acid H ₄ SiO ₄ and its polymer, metasilicic acid H ₂ Si shown in the section “Silicic acid”.
O ₃ , mesosilicate H ₂ SiO ₅ , mesotrisilicate H ₄ Si ₃ O ₈ and mesotetrasilicate H ₆ Si ₄ O ₁₁ are shown.

The composition for forming a silica film is, for example, tetraalkoxysilane (Si (OR) ₄ , where R is a hydrocarbon group, especially a C ₁ -C ₆ aliphatic group), specifically tetramethoxysilane, Tetraethoxysilane, tetra-n-propoxysilane, tetraisopropoxysilane, tetra-n-
It can be obtained by adding water, an alkali and an organic solvent to a precursor capable of forming silicic acid containing no organic group and halogen such as butoxysilane, stirring the mixture and proceeding with the hydrolysis reaction. This method is preferable because it is easy to handle or operate and is practical. Among them, tetraethoxysilane is a preferable material.

A hydrocarbon group represented by the formula X _n Si (OH) _4-n (wherein X is a hydrocarbon group, halogen, hydrogen, n is an integer of 1, 2 or 3), a halogen or A compound having a hydrophobic group such as hydrogen is different from the silicic acid used in the present invention. Therefore, trialkoxyalkylsilanes, dialkoxyalkyldialkylsilanes, trialkoxysilanes, dialkoxysilanes, etc. are not suitable as precursors capable of producing silicic acid containing no organic groups and halogens.

Further, water, an alkali and an organic solvent are added to the tetrahalogenated silane for hydrolysis, a method of adding an alkali and an organic solvent to the water glass, or the water glass is treated with a cation exchange resin. A silica film-forming composition containing silicic acid containing no organic group and halogen can also be obtained by using a method of adding an alkali and an organic solvent. The tetraalkoxysilane, tetrahalogenated silane, and water glass used as the raw material of silicic acid containing no organic group and halogen are not particularly limited, and may be those generally used industrially or as a reagent, but preferably higher. Those with a purity are suitable. Further, the composition for forming a silica film of the present composition may contain an unreacted material of the above-mentioned raw material of silicic acid.

The amount of silicic acid containing no organic group and halogen is not particularly limited, but the concentration of silicon atoms is preferably in the range of 0.0001 to 5 mol / liter. The range is more preferably 0.001 to 5 mol / liter.
If the silicon concentration is less than 0.0001 mol / liter, the rate of formation of the silica coating is very slow and not practical. If it exceeds 5 mol / liter, silica particles may be formed in the composition without forming a film.

The silicon concentration can be calculated from the amount of silicic acid raw material added, for example, tetraethoxysilane, but it can also be measured by atomic absorption spectrometry of the composition. For the measurement, it is preferable to use a spectrum of silicon having a wavelength of 251.6 nm as an analysis line and use a frame made of acetylene / nitrous oxide.

The water used in the composition for forming a silica film is not particularly limited, and ion-exchanged water, distilled water, tap water, etc. can be used, but water obtained by removing particles by filtration or the like is preferable. . If particles are contained in water, they are mixed as impurities in the product, which is not preferable.

Water has a volume ratio of water / organic solvent of 0.1 to 0.1.
Preference is given to using amounts in the range of 10. If the volume ratio of water / organic solvent is out of this range, film formation may not be possible or the film formation rate may be extremely reduced. More preferably, the volume ratio of water / organic solvent is in the range of 0.1 to 0.5. The type of alkali used is not limited as long as the water / organic solvent ratio is 0.1 to 0.5 by volume. When the water / organic solvent ratio is 0.5 or more, it is preferable to form a film by using an alkali containing no alkali metal, such as ammonia, ammonium hydrogen carbonate, or ammonium carbonate.

In the present invention, the alkali used in the silica film forming composition is not particularly limited. For example, inorganic alkalis such as ammonia, sodium hydroxide, potassium hydroxide; ammonium carbonate, ammonium hydrogen carbonate,
Inorganic alkali salts such as sodium carbonate and sodium hydrogen carbonate; organic alkalis such as monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, pyridine, aniline, choline, tetramethylammonium hydroxide and guanidine; ammonium formate, acetic acid Organic acid alkali salts such as ammonium, monomethylamine formate, dimethylamine acetate, pyridine lactate, guanidinoacetic acid and aniline acetate can be used.

Of these, ammonia, ammonium carbonate, ammonium hydrogen carbonate,
Particularly preferred are ammonium formate, ammonium acetate, sodium carbonate and sodium hydrogen carbonate. The alkali used in the composition for forming a silica film can be used alone or in combination of two or more selected from the above group.

The purity of the alkali used in the present invention is not particularly limited. It may be one that is widely used in industry or as a reagent, but one having a higher purity is preferable.

In the present invention, the addition amount of the alkali for forming the film is, for example, in the case of sodium carbonate, 0.002 mol /
A film can be formed by adding a minute amount of about 1 liter, but 1 mol /
It does not matter if a large amount of liter is added. However, if a solid alkali is added in an amount exceeding the solubility,
It is not preferable because it is mixed as an impurity in the phosphor particles.

By using an alkali which does not contain an alkali metal as a main component, silica-coated luminescent particles having a low alkali metal content can be prepared. Among them, ammonia, ammonium carbonate, and ammonium hydrogencarbonate are particularly preferable from the viewpoint of film forming speed and easy removal of residues.

The organic solvent used in the silica film forming composition of the present invention is preferably one in which the silica film forming composition forms a uniform solution. For example, alcohols such as methanol, ethanol, propanol, and pentanol; ethers and acetals such as tetrahydrofuran and 1,4-dioxane; ketones such as acetone, diacetone alcohol, and methyl ethyl ketone; ethylene glycol, propylene glycol, diethylene glycol, and the like. A polyhydric alcohol derivative or the like can be used. Among these, alcohols are preferably used from the viewpoint of reaction rate control, and ethanol is particularly preferable. As the organic solvent, one kind or a mixture of two or more kinds selected from the above group can be used.

The purity of the organic solvent used in the composition for forming a silica film is not particularly limited, and may be one that is widely used industrially or as a reagent, but one having a higher purity is preferable. .

A general solution preparation method can be applied to the preparation of the silica film forming composition. For example, a method in which a predetermined amount of alkali and water are added to an organic solvent and stirred and then tetraethoxysilane is added and stirred, but the order of mixing these may be any, and a film can be formed. is there. When water and tetraethoxysilane are mixed, it is preferable to dilute both with an organic solvent from the viewpoint of controllability of the reaction.

If necessary, a leveling agent, a defoaming agent, an antistatic agent, an ultraviolet absorber, a pH adjusting agent, a dispersant,
A surface modifier, anti-flow agent, etc. may be added.

The silica film-forming composition thus prepared is a stable composition, and substantially no deposition or precipitation occurs until it is brought into contact with the phosphor particles. After contacting the composition with the phosphor particles, silica begins to selectively deposit on the surface of the phosphor particles.

In the present invention, the phosphor particles are immersed in the composition for forming a silica film and kept at a predetermined temperature to selectively deposit silica on the surface of the phosphor particles to form a silica film. Can be made. It is possible to prepare a composition for film formation in advance and then add phosphor particles to form a silica film, or to suspend phosphor particles in a solvent in advance and then add other raw material components to form a film. A method of forming the composition and forming a silica film may be used. That is, the order of adding the raw material of the composition for forming a film and the phosphor particles is not particularly limited, and the silica film can be formed regardless of which order comes first.

Among these methods, a suspension containing luminescent particles, water, an organic solvent and an alkali is prepared, and then tetraalkoxysilane diluted with an organic solvent is added dropwise thereto at a constant rate to obtain a more dense structure. It is preferable since a good silica film can be formed and an industrially useful continuous process can be constructed.

Since the silica coating grows by depositing on the surface of the phosphor particles, the film thickness can be increased by increasing the film formation time. Needless to say, when the silicic acid in the film-forming composition is mostly consumed by the film formation, the film formation rate decreases, but by continuously adding silicic acid corresponding to the consumption amount, practical use continues. The silica film can be formed at a uniform film forming rate. In particular, the luminescent material is kept for a predetermined time in a film-forming composition containing silicic acid corresponding to a desired silica film thickness to form a silica film to consume the silicic acid, and the silica-coated luminescent material particles are taken out of the system. After that, by additionally adding silicic acid corresponding to the consumption amount, the composition can be subsequently used for forming a film on the next phosphor particles,
A continuous process with high economic efficiency and productivity can be constructed.

Further, in the case of a method of preparing a suspension containing phosphor particles, water, an organic solvent and an alkali, and then adding tetraalkoxysilane diluted with the organic solvent thereto at a constant rate, a desired method is used. By adding a solution of tetraalkoxysilane corresponding to the silica film thickness diluted in an organic solvent at a constant rate corresponding to the hydrolysis rate of tetraalkoxylane, the tetraalkoxysilane is completely consumed and the desired film thickness is obtained. It is possible to form a dense silica film having, and take out the generated silica-coated phosphor particles to the outside of the system to obtain a high-purity product having no residual unreacted tetraalkoxysilane. Of course, the solvent after taking out the silica-coated phosphor particles can be recycled for the next film formation, and a process with high economy and productivity can be constructed.

The temperature for forming the silica coating is not particularly limited, but is preferably in the range of 10 to 100 ° C, more preferably 20 to 50 ° C. The higher the temperature, the higher the film formation rate, but if it is too high, the components in the composition volatilize,
It becomes difficult to keep the solution composition constant, and if the temperature is too low, the film formation rate becomes slow, which is not practical.

In order to increase the silica film formation rate, it is effective to increase the temperature during film formation. In this case, it is preferable to use an alkali and an organic solvent that are hard to volatilize and decompose at the film forming temperature.

The pH at the time of film formation may be alkaline. However, in the case of forming a silica coating on a luminescent material whose solubility increases depending on pH, the p
It is preferable to control H. Preferred pH is 8-13
And more preferably 9-12. The pH can be controlled by adjusting the addition amount according to the alkaline species.

After forming the film, the solid-liquid separation can be carried out to isolate the silica-coated luminescent particles. As a method for isolation, a general separation method such as filtration, centrifugal sedimentation, and centrifugation can be used.

By sufficiently drying after solid / liquid separation, it is possible to obtain silica-coated luminescent particles having a high initial luminescence intensity without being affected by exposure to an aqueous environment in spite of wet coating. The drying method is warm air drying,
A general drying method such as vacuum drying or spray drying can be used. In order to reduce the influence of loss on drying on the initial luminescence intensity and moisture resistance of the coated luminescent material, the preferred drying method is vacuum drying, in which case 50 to
Dry for 1 to 5 hours at 150 ° C. at 5 kPa or less.

The silica-coated phosphor particles of the present invention have a very good shape following property of the silica coating, and all the primary particles of the phosphor particles as the base material are coated with a dense silica film, Strong adhesion.

The silica film obtained by the above method is 115
The ratio of the absorption peak intensity of the infrared absorption spectrum in 0～1250Cm ^-1 and 1000~1100cm ^-1 I (I = I
₁ / I ₂ : I ₁ is 1150 to 1250 cm ⁻¹ Si—OH
Absorbance of the absorption peak, I ₂ of 1000 to 1100
The absorbance of the absorption peak due to Si-O-Si at cm- ¹ ) is 0.2 or more, and the refractive index is 1.435 or more. That is, since it retains the chemical bond or the functional group of the silica film obtained when it is not baked by the conventional sol-gel method, it has specific physical properties different from those of the silica film obtained by baking, such as hydrophilicity and lipophilicity. in spite of,
It is a dense and practical silica coating.

Furthermore, the silica coating film of the present invention is suitable for covering the complicated shape of the phosphor particles of the base material. In the neutralization deposition method from sodium silicate, the silica particles form a film by being deposited on the phosphor particles, whereas in the method of the present invention, a dense silica film is formed on the phosphor particle surface of the base material,
It is selectively and three-dimensionally deposited and grown.
Even with a thin coating of about m, the shape following property is good and a uniform coating can be formed. Further, by limiting the type of alkali of the composition for forming a silica film, it is possible to obtain a silica film having an extremely low content of alkali metals such as sodium, so that the silica film does not dissolve even in a high temperature and high humidity atmosphere and the silica film does not dissolve. It has the characteristic that the physical properties of the coating do not change.

(Second Coating) Next, the dense silica coating (second coating) derived from polysilazane will be described. The silica second coating film of the present invention is formed by using polysilazane. The thickness of such a silica film is 0.01 to
It is preferably about 0.5 μm, more preferably 0.0
It is preferably about 5 to 0.25 μm. With such a film thickness, the function as a moisture resistant film becomes sufficient,
Moreover, it is possible to obtain a light-emitting particle having good dispersibility without causing a decrease in initial luminescence light intensity. Film thickness 0.0
If it is less than 1 μm, the function as a moisture resistant film is insufficient,
When it is 0.5 μm or more, the initial luminous intensity is lowered and the dispersibility may be impaired.

The silica coating by the sol-gel method for obtaining a silica film by a typical wet surface treatment and the above-mentioned first coating have a large mass loss due to the elimination of hydroxy groups and alkoxy groups at the time of silica conversion. , Large volume shrinkage,
If the film thickness is 0.5 μm or more, cracks are likely to occur.

On the other hand, in the case of silica conversion using polysilazane, due to the reaction mechanism described later, a mass increase occurs at the time of silica conversion, volume shrinkage is small, and it is difficult to generate cracks at a relatively low temperature during silica film conversion. Become.

[0057] The second coating, the refractive index to form a 1.45 or more dense film, among others the ratio of the absorption peak intensity of the infrared absorption spectrum in 1150～1250Cm ^-1 and 1000~1100cm ^-1 I (I = I ₁ / I ₂ : I ₁ is 115
Absorbance of the absorption peak by Si-OH of 0~1250cm ^-1, Si-O-S of I ₂ is 1000～1100Cm ^-1
It is preferable that the absorption peak of i is less than 0.2. The refractive index is the value of fused silica glass (density 2.2 g /
cm ³ and a refractive index of 1.46), and a SiO ₂ film is substantially formed.

The polysilazane used in the present invention is silicon-
It is a polymer with nitrogen bond, Si-N, Si-H,
It is a ceramic precursor inorganic polymer of SiO ₂ composed of N—H and the like. For example, the general formula 1 disclosed in JP-A-8-236274 (wherein R ¹ , R ² , and R ³ are each independently a hydrogen atom, an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group, or these In addition to the above groups, the group which is directly bonded to silicon is carbon, an alkylsilyl group, an alkylamino group, an alkoxy group or a metal atom, provided that at least one of R ¹ , R ² and R ³ is a hydrogen atom. A compound having a main skeleton composed of a unit represented by

[0059]

[Chemical 1]

In the present invention, perhydropolysilazane in which the side chains are all hydrogen is preferable from the viewpoint of the function of the ceramic film as a moisture resistant film and the hardness. The polysilazane having an organic group in its side chain has poor density because the organic group remains after curing. The method for producing perhydropolysilazane is described, for example, in Japanese Examined Patent Publication No. 63-16325, D.
Seyferth et al. Communication of Am. Cer. Soc., C-13,
Reported in January 1983. Perhydropolysilazane is presumed to have a linear structure and a ring structure centered on a 6- and 8-membered ring. The number average molecular weight (Mn) is 100 to 50,000. If the molecular weight of the polysilazane used is too small, the yield upon curing will be low, which is not practical. On the other hand, if the molecular weight is too large, the stability of the solution is low and a dense film cannot be obtained. For these reasons, the molecular weight of the polysilazane used is a number average molecular weight and the lower limit is 100, preferably 300, more preferably 5
00. The upper limit is 50,000, preferably 20,000, and more preferably 10,000.

These are polysilazane (SiH) diluted with xylene in a solution state dissolved in an organic solvent.
₂ NH) n (manufactured by Tonen Corporation), poly (1,1-dimethylsilazane) telomer (manufactured by Asmax Corporation), perhydrosilazane (manufactured by Clariant Japan Co., Ltd.)
Etc. can be used.

Examples of the solvent include aliphatic hydrocarbons, alicyclic hydrocarbons, hydrocarbon solvents of aromatic hydrocarbons, halogenated hydrocarbons such as halogenated methane, halogenated ethane and halogenated benzenes, aliphatic ethers and fats. Ethers such as cyclic ethers can be used. Preferred solvents are halogenated hydrocarbons such as methylene chloride, chloroform, carbon tetrachloride, bromoform, ethylene chloride, ethylidene chloride, trichloroethane and tetrachloroethane, ethyl ether,
Ethers such as isopropyl ether, ethylbutyl ether, dibutyl ether, 1,2-dioxyethane, dioxane, dimethyldioxane, tetrahydrofuran, tetrahydropyran, cellosolve acetate, carbitol acetate, pentanehexane, isohexane,
Methyl pentane, heptane, isoheptane, octane,
Hydrocarbons such as isooctane, cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, benzene, toluene, xylene and ethylbenzene. Among these, xylene and dibutyl ether are particularly preferable from the viewpoint of solubility, stability, and uniform coating property.

When these solvents are used, two or more kinds of solvents may be mixed in order to adjust the solubility of polysilazane and the evaporation rate of the solvent. The amount (proportion) of the solvent used is selected according to the coating method used so as to improve workability, and is also selected according to the required film thickness. Also, it varies depending on the average molecular weight of polysilazane, the molecular weight distribution, and its structure. The solvent can be mixed up to about 99.99% by mass, and preferably the solid content concentration can be mixed within the range of 0.1 to 50% by mass. The solid content concentration is 0.
If it is less than 1% by mass, the rate of formation of the silica coating is very slow and not practical. On the other hand, if it exceeds 50% by mass, silica particles may be formed in the composition without forming a film, which is not preferable.

As described above, polysilazane is a ceramic precursor polymer, and in order to form a silica film using this, polysilazane is fired in the air at 400 ° C. or higher, and SiO ₂ is converted by, for example, the reaction shown in (Formula 2). It is usually carried out, but in the case of a coated luminescent material, if the temperature is 400 ° C. or higher, the localization of the activator and the co-activator causes a decrease in the initial luminescence light intensity, which is not preferable.

[0065]

[Chemical 2]

On the other hand, the wet coating of polysilazane was combined with steam oxidation in the presence of a catalyst to obtain 10
A dense silica film can be obtained even at 0 ° C. or lower, and it can be formed on a substrate having low heat resistance such as the present coated light-emitting body as described above, and therefore does not cause a decrease in initial luminescence light intensity.

In particular, a polysilazane containing no carbon (C) component forms a dense film having good wettability (easiness to adapt) to the underlying first coating. In addition, the problem of shrinkage of the film and residual carbon does not occur during thermal decomposition such as a sol-gel film using an alcoside system, and cracking does not occur.

As the catalyst, an amine or metal ion catalyst can be used, and both may be used in combination. The type of amine is not particularly limited, and examples thereof include triethylamine, trimethylamine, diethylamine, monoethanolamine, diethanolamine, triethanolamine, n-exylamine, n-butylamine,
Amines such as tri-n-butylamine, guanidine, piguanine, and imidazole can be used. Among them, trimethylamine and triethylamine are preferable in terms of solubility, uniform coverage and low temperature curability. The concentration in the composition for forming a silica film is 0.1 to 10% by mass, preferably 1 to 8% by mass, and more preferably 1 to 5% by mass. If it is 0.1 mass% or less, the conversion rate to silica is slow and it is not economical, and if it is 10 mass% or more, the silica conversion rate becomes too fast and the uniform film property is impaired, or the phosphor particles are fixed to each other to cause dispersibility. Damages. For example, a composition obtained by adding triethylamine to polysilazane is applied to the luminescent particles and then contacted by spraying or impregnation.
A dense silica coating is formed by keeping the temperature at 80 ° C. and 80% RH for about 3 hours. In addition, Mn is 100 in the vapor (non-phase) of the aqueous solution containing trimethylamine.
25 luminescent particles coated with up to 50,000 polysilazanes
A dense silica coating film is formed by maintaining the substrate in a gas phase at 2 ° C. for about 2 minutes and then maintaining it at 95 ° C. and 80% RH for about 3 hours.

When a metal ion is used as a catalyst, examples of the metal include Ag, Au, Pd and Ni. Among them, Pd is preferable in terms of uniform coverage and low temperature curability. The concentration in the composition for forming a silica film is 0.1 to 10% by mass, preferably 1 to 5% by mass, more preferably 1 to 3% by mass.
It is% by mass. If it is 0.1 mass% or less, the conversion rate to silica is slow and it is not economical, and if it is 5 mass% or more, the silica conversion rate becomes too fast and the uniform film property is impaired, or the phosphor particles are fixed to each other to cause dispersibility. Damages. For example, a dense silica coating can also be obtained by coating a composition obtained by adding Pd to polysilazane having an Mn of 100 to 50,000, contacting the luminescent particles by spraying or impregnation, drying, and baking at a low temperature of 100 to 350 ° C. .

The silica film forming composition may further contain a leveling agent, an antifoaming agent, an antistatic agent, an ultraviolet absorber, a pH adjusting agent, a dispersant, a surface modifying agent, a flow preventive agent, etc., if necessary. May be added.

Further, when the first coating is not provided, that is, when the uncoated luminescent particles are directly coated with the silica coating derived from polysilazane, the adhesion with the particles is insufficient and a uniform coating state cannot be obtained, resulting in moisture resistance. No improvement was observed. That is, due to the presence of the first coating, sufficient adhesion of the second coating derived from polysilazane can be secured, and synergistic moisture resistance can be improved even in the second coating having a small thickness.

The surface of the silica-coated phosphor particles of the present invention may be hydrophobized. To make the surface hydrophobic, it is possible to coat the surface thereof with an organosiloxane or a silicone resin. Examples of organosiloxanes and silicone resins include methylhydrogenpolysiloxane, dimethylpolysiloxane, methylphenylpolysiloxane, biphenylpolysiloxane, alkyl-modified silicone-alkoxy-modified silicone, trimethylsiloxysilicic acid, acrylic silicone, and silicone resin. Further, these organosiloxanes, silicone resins and silane coupling agents, aluminum coupling agents and the like can be used at the same time.
Preferred organosiloxanes and silicone resins are methyl hydrogen polysiloxane and dimethyl polysiloxane.

These coating treatments may be carried out by a wet method, a dry method, a mechanochemical method or the like. Due to this hydrophobization, the moisture resistance of the luminescent material can be further enhanced. The amount of these coatings is 0.1 to 5% by mass, preferably 0.1 to 2% by mass, based on the coated phosphor particles. If it is 0.1% by mass or less, the hydrophobicity is low, and if it is 5% by mass or more, the initial luminescence light intensity may be lowered, which is not preferable.

The primary particle size of the silica-coated phosphor particles of the present invention is not particularly limited, but is preferably 0.1.
-100 μm, preferably 1-80 μm, more preferably 1-50 μm. If the primary particle size is larger than 100 μm, it may be difficult to form a thin luminous body layer in electroluminescence, and the distribution of the luminous body may become uneven. If the primary particles are less than 0.1 μm, the particles tend to coagulate and flowability tends to decrease, which is not preferable.

The "primary particles" in the present invention are those defined by "Powder" published by Teruichiro Kubo et al., P. 56-66, 1979.

The particle size of the luminescent particles is ultrafine particles (particle size 0.5 μm or less) obtained by the sol-gel method or particle size 0.5 to 0.5.
Those having a thickness of about 100 μm can be preferably used.

In the present invention, the film thickness and the refractive index of the silica film can be measured by using the silica film formed on the silicon wafer which is simultaneously immersed in the system when synthesizing the silica-coated luminescent particles. The same silica coating as on the phosphor particles is formed on this silicon wafer.
The refractive index of the silica film is measured by an ellipsometer (ULVAC
Made; LASER ELLIPSOMETER ESM
-1A). A step gauge can be used to measure the film thickness.

Transmission infrared absorption spectrum of silica film of silica-coated phosphor particles (FT-IR-8000 manufactured by JASCO Corporation)
Can be measured using the KBr method. The primary particle diameter and the silica film thickness of the silica-coated luminescent particles can be determined from a transmission electron microscope image or a scanning electron microscope image.

The structures of the first and second coatings in the present invention can be confirmed by surface analysis by X-ray diffraction and EPMA (electron probe microanalysis) to confirm the surface layer structure and surface element distribution at a depth of about 1 μm.

[0080]

EXAMPLES Examples of the present invention will be described in detail below. However, the present invention is not limited to these examples.

The initial luminescence photometric measurement, the moisture resistance test, the dispersibility test, the refractive index measurement, the silica film thickness measurement, and the infrared absorption spectrum measurement used in the examples were carried out by the following methods.

(Measurement of initial electroluminescence photometry) 50 parts by mass of luminescent particles are used as cyanoethyl cellulose 1
Dispersion 1 is obtained by mixing 5 parts by mass and 35 parts by mass of dimethylformamide. After forming an insulating layer consisting of barium titanate and cyanoethyl cellulose on the aluminum back electrode, the dispersion 1 is applied with an automatic coater to a thickness of 50 μm, dried, and then sandwiched with an ITO (indium tin oxide) transparent electrode to form a dispersion type. An EL (electroluminescence) element was constructed. Relative humidity 10%, temperature 25 ° C, voltage 100V,
The luminous intensity at a frequency of 400 Hz was measured. The relative value (IBe) of the luminous intensity of the coated luminous particles of each example was calculated with the luminous intensity of the uncoated treated luminous particles being 100.

(Electroluminescence Moisture Resistance Test)
Dispersion 1 is obtained by mixing 50 parts by mass of the phosphor particles with 15 parts by mass of cyanoethyl cellulose and 35 parts by mass of dimethylformamide. After forming an insulator layer consisting of barium titanate and cyanoethyl cellulose on the aluminum back electrode,
Dispersion 1 was applied with an automatic coating machine to a thickness of 50 μm, dried with a warm air dryer at 80 ° C. for 1 hr, and sandwiched with ITO transparent electrodes to form a dispersion type EL device. The residual rate (RBe) of the luminous intensity in 100 hours continuous light emission at a relative humidity of 90%, a temperature of 40 ° C., a voltage of 100 V, and a frequency of 400 Hz was determined.

(Dispersibility Test) Dispersion 1 was obtained by mixing 50 parts by mass of the phosphor particles with 15 parts by mass of cyanoethyl cellulose and 35 parts by mass of dimethylformamide. Dispersion 1 was placed in a settling tube and allowed to stand, and the state of the luminescent particles settling was visually observed to evaluate the degree of dispersion.

Judgment of the degree of dispersion was made according to the following criteria.

--2 in case of sedimentation immediately after standing, 1 after standing
The case of sedimentation after time is -1, the case of sedimentation after 3 hours of standing is 0, the case of sedimentation after 9 hours of standing is +1, and the case of not sedimenting even one day after standing is +2.

(Measurement of Refractive Index) Silica Coated An ellipsometer (ULVAC) was used by using a silica film formed on a silicon wafer immersed in the system when synthesizing phosphor particles.
Manufactured by LASSERELLIPSOMETER ESM
-1A).

(Measurement of Film Thickness) Silica Coated A silica film formed on a silicon wafer immersed in the system when synthesizing phosphor particles was used to measure a step difference meter (DEK manufactured by SLOAN, DEK).
TAK3030). A step blank is formed by covering a part of the silicon wafer with tape and peeling off the part. The step between the silica coating and the blank is measured. Further, the silica coated phosphor particles themselves are observed with a transmission electron microscope (JEM2010 manufactured by JEOL Ltd., accelerating voltage 200V), and the silica coating on the particle surface (the base material is recognized to cover the base material). The thickness can be also measured by observing the thickness of the film portion having a thin contrast), and a value that substantially matches the value measured by the step gauge can be obtained.

(IR spectrum measurement) The transmission infrared absorption spectrum (FT-IR-8000 manufactured by JASCO Corporation) of the silica film of the silica-coated light emitting particles was measured by the KBr method (light emitting particles and powders of KBr were mixed). The ratio was measured using a luminescent particle / KBr mass ratio of 1/32. 1150-1250
cm ^-1 and calculates the absorbance of the absorption peak than the transmittance of the infrared absorption spectrum in 1000~1100cm ^-1, the ratio of the absorption peak intensity _{I (I = I 1 / I} 2: I 1 is 1150～
Absorbance of absorption peak at 1250 cm ^-1 , I ₂ is 1000
The absorbance of the absorption peak at ˜1100 cm ⁻¹ ) is determined.

(Example 1) (Synthesis of first coating) Deionized water (440 m) was added to a 5 L reactor.
L, 1860 mL of ethanol (manufactured by Junsei Chemical Co., Ltd.) and 40 ml of 25 mass% ammonia water (manufactured by Taisei Kako Co., Ltd.) were mixed, and phosphor particles (manufactured by HANEYWELL) were mixed therein.
LUMILUX BlueEL (registered trademark): ZnS-based electroluminescent particles; average particle diameter D ₅₀ 25 μ
m) 200 g was dispersed to prepare a suspension 1. next,
20 mL of tetraethoxysilane (made by Nacalai Tesque),
Solution 1 was prepared by mixing 250 mL of ethanol.

Solution 1 was added to Suspension 1 stirred with a magnetic stirrer at a constant rate over 12 hours, and then aged for 12 hours. The film formation and aging were performed at 25 ° C. After that, the solid content is separated by centrifugal filtration, and ethanol 2
After rinsing with 00 ml, the wet solid content was collected. The wet solid content was vacuum dried at 80 ° C. for 12 hours to obtain phosphor particles having a silica first coating.

(Synthesis of Second Coating) 1600 g of xylene (manufactured by Wako Pure Chemical Industries, Ltd.) and 6 g of triethylamine (manufactured by Wako Pure Chemical Industries, Ltd.) were mixed in a 5 L reactor, and the silica first coating as described above was mixed therein. The suspension 2 was prepared by dispersing 160 g of the phosphor particles subjected to the above. Next, perhydropolysilazane (NL-1 manufactured by Clariant Japan Co., Ltd.)
10-2; 20 g of xylene solution containing 20% by mass of oxide perhydropolysilazane) and 160 g of dehydrated xylene (manufactured by Wako Pure Chemical Industries, Ltd.) were mixed to prepare solution 2.

The solution 2 was added to the suspension 2 stirred with a magnetic stirrer at a constant rate over 20 hours and then aged for 12 hours. The film formation and aging were performed at 45 ° C. Then, the solid content was separated by centrifugal filtration, and the wet solid content was collected. Vacuum dry the wet solids at 80 ° C for 12 hours,
After further treatment for 12 hours in an atmosphere of 95 ° C. and 80% RH, vacuum drying was performed at 95 ° C. for 1 hour to obtain silica-coated phosphor particles 1 having a second silica coating.

(Example 2) (Synthesis of first coating) Deionized water (440 m) was added to a 5 L reactor.
L, 1860 mL of ethanol (manufactured by Junsei Chemical Co., Ltd.) and 40 ml of 25 mass% ammonia water (manufactured by Taisei Kako Co., Ltd.) were mixed, and phosphor particles (manufactured by HANEYWELL) were mixed therein.
200 g of LUMILUX Blue EL: ZnS electroluminescent particles) was dispersed to prepare a suspension 3. Next, 4 mL of tetraethoxysilane (manufactured by Nacalai Tesque) and 50 mL of ethanol were mixed to prepare a solution 3.

The solution 3 was added to the suspension 3 stirred with a magnetic stirrer at a constant rate over 2.5 hours and then aged for 12 hours. The film formation and aging were performed at 25 ° C. After that, the solid content is separated by centrifugal filtration, and ethanol 2
After rinsing with 00 ml, the wet solid content was collected. The wet solid content was vacuum dried at 80 ° C. for 12 hours to obtain phosphor particles having a silica first coating.

(Synthesis of Second Coating) 1600 g of xylene (manufactured by Wako Pure Chemical Industries, Ltd.) and 6 g of triethylamine (manufactured by Wako Pure Chemical Industries, Ltd.) were mixed in a 5 L reactor, and the silica first coating as described above was mixed therein. The suspension 4 was prepared by dispersing 160 g of the phosphor particles subjected to the above. Next, perhydropolysilazane (NL-1 manufactured by Clariant Japan Co., Ltd.)
10-2; 20 g of a xylene solution containing 20% by mass of oxide perhydropolysilazane) and 160 g of dehydrated xylene (manufactured by Wako Pure Chemical Industries, Ltd.) were mixed to prepare a solution 4.

Solution 4 was added to Suspension 4 stirred with a magnetic stirrer at a constant rate over 20 hours, and then aged for 12 hours. The film formation and aging were performed at 45 ° C. Then, the solid content was separated by centrifugal filtration, and the wet solid content was collected. Vacuum dry the wet solids at 80 ° C for 12 hours,
After further treatment for 12 hours in an atmosphere of 95 ° C. and 80% RH, vacuum drying was performed at 95 ° C. for 1 hour to obtain silica-coated phosphor particles 2 having a second silica coating.

(Example 3) (Synthesis of first coating) 440 m of deionized water was added to a 5 L reactor.
L, 1860 mL of ethanol (manufactured by Junsei Chemical Co., Ltd.) and 40 ml of 25 mass% ammonia water (manufactured by Taisei Kako Co., Ltd.) were mixed, and phosphor particles (manufactured by HANEYWELL) were mixed therein.
200 g of LUMILUX Blue EL: ZnS electroluminescent particles) was dispersed to prepare a suspension 5. Next, 20 mL of tetraethoxysilane (manufactured by Nacalai Tesque) and 250 mL of ethanol are mixed to obtain solution 5
Was prepared.

Solution 5 was added to suspension 5 stirred with a magnetic stirrer at a constant rate over 12 hours, and then aged for 12 hours. The film formation and aging were performed at 25 ° C. After that, the solid content is separated by centrifugal filtration, and ethanol 2
After rinsing with 00 ml, the wet solid content was collected. The wet solid content was vacuum dried at 80 ° C. for 12 hours to obtain phosphor particles having a silica first coating.

(Synthesis of Second Coating) 1600 g of xylene (manufactured by Wako Pure Chemical Industries, Ltd.) and 6 g of triethylamine (manufactured by Wako Pure Chemical Industries, Ltd.) were mixed in a 5 L reactor, and the silica first coating as described above was mixed therein. The suspension 6 was prepared by dispersing 160 g of the phosphor particles subjected to the above. Next, perhydropolysilazane (NL-1 manufactured by Clariant Japan Co., Ltd.)
10-2; 5 g of a xylene solution containing 20% by mass of oxide perhydropolysilazane) and 40 g of dehydrated xylene (manufactured by Wako Pure Chemical Industries, Ltd.) were mixed to prepare a solution 6.

The solution 6 was added to the suspension 6 stirred with a magnetic stirrer at a constant rate for 5 hours.
Aged for 12 hours. The film formation and aging were performed at 45 ° C. Then, the solid content was separated by centrifugal filtration, and the wet solid content was collected. The wet solid content is vacuum dried at 80 ° C. for 12 hours, and further 9
After treatment for 12 hours in an atmosphere of 5 ° C. and 80% RH, 95
The silica-coated phosphor particles 3 having the second silica coating were obtained by vacuum drying at 1 ° C. for 1 hr.

(Comparative Example 1) Uncoated phosphor particles (Example 1)
The same LUMILUX BlueEL used in
The particle itself was designated as Comparative Control Particle 1.

Comparative Example 2 Silica first-coated phosphor particles (without silica second coating) were prepared in the same manner as in Example 1 except that the second silica coating was not applied.
This was designated as Comparative Control Particle 2.

(Comparative Example 3) Silica first-coated phosphor particles (silica first particles) were prepared in the same manner as in Example 1 except that the amount of tetraethoxysilane was 40 ml and the silica second coating was not applied. (No double coating) was obtained, which was designated as Comparative Control Particle 3.

Comparative Example 4 A silica-coated phosphor obtained by directly applying a silica coating derived from polysilazane to phosphor particles by the same method as in Example 1 except that the silica first coating is not applied. Particles were obtained and designated as Comparative Control Particle 4. In this case, since the coating has poor adhesion and uniform coverage, the surface treatment state of the comparative control particles has many fine silica particles, and in addition to the surface of the luminescent particles, the formation of single silica particles is not possible. Admitted.

The transmission infrared absorption spectra of the silica-coated phosphor particles obtained in Examples 1 to 3 and the comparative control particles of Comparative Examples 2 to 4 were measured by the KBr method. ~ 1100 cm ^-1 Si-O-
Absorption due to Si stretching vibration was observed, 2800-300
No absorption due to C—H stretching vibration was observed at 0 cm ⁻¹ within the detection limit, and the formed film was identified as silica.

Further, Table 1 shows the results of measuring the silica film thickness of the silica first coating and the second coating, the absorption peak intensity ratio I of the infrared absorption spectrum, and the refractive index. Since the refractive index was close to the value of fused silica glass (density 2.2 g / cm ³ , refractive index 1.46), it was confirmed that the composition of the coating was substantially SiO ₂ .

Table 2 shows the results of evaluation of the initial electroluminescence light intensity (IBe), electroluminescence humidity resistance (RBe) and dispersity of the phosphor particles of Examples 1 to 3 and Comparative Examples 1 to 4.

[0109]

[Table 1]

[0110]

[Table 2]

[0111]

INDUSTRIAL APPLICABILITY The present invention is excellent in moisture resistance, has the same initial luminescence light intensity as the uncoated product, and has a dense film.
The present invention provides a silica-coated luminescent particle having good adhesion and excellent dispersibility and moldability without particle sticking, and the luminescent particle can be used for a dispersion-type luminescent layer of an electroluminescence device.

[0112]

[Brief description of drawings]

FIG. 1 is an infrared absorption spectrum of a phosphor particle having a silica first coating produced in Example 1.

2 is an infrared absorption spectrum of the phosphor particles having a second silica coating formed in Example 1. FIG.

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Claims (18)

[Claims] 1. A thin film silica having a refractive index of 1.435 or more (first coating) is coated, and a polysilazane-derived silica film having a refractive index of 1.45 or more is coated on the first coating (second coating). Coated phosphor particles. 2. The film thickness of the silica film of the first coating and the second coating is
The phosphor particles according to claim 1, which have a diameter of 0.02 to 1 µm. 3. The phosphor particles according to claim 1, wherein the polysilazane is perhydropolysilazane. 4. The number average molecular weight of polysilazane is 100 to 100.
The phosphor particles according to claim 3, which are in the range of 50,000. 5. The thickness of the first coating is 0.01 to 0.5 μm,
The phosphor particles according to any one of claims 1 to 4, which are coated with a silica film having a film thickness of the second film of 0.01 to 0.5 µm. 6. A film thickness of 0.01 to 0.5 μm, a refractive index of which is 1.45 or more, and an infrared absorption spectrum of 1150 to 1250 cm ⁻¹ and 1000 to ¹
The ratio I of absorption peak intensities at 100 cm ⁻¹ (I = I ₁ / I ₂ :
I ₁ is the absorbance of the absorption peak of 1150~1250cm ^-1, I ₂ is the absorbance of the absorption peak of 1000～1100Cm ^-1) is less than 0.2, coated with silica membranes from polysilazane (second film) The phosphor particles according to any one of claims 1 to 5. 7. A film thickness of 0.01 to 0.5 μm, a refractive index of which is 1.435 or more, and an infrared absorption spectrum of 1150 to 1250 cm ⁻¹ and 1000 to
Ratio I of absorption peak intensities at 1100 cm ⁻¹ (I = I ₁ /
I _2: I ₁ is the absorbance of the absorption peak of 1150~1250cm ^-1, wherein I ₂ is the absorbance of the absorption peak of 1000～1100Cm ^-1) is covered with the silica film is 0.2 or more (first coating) Item 7. The luminescent particle according to any one of items 1 to 6. 8. The luminescent particles according to claim 1, wherein the outermost surface is hydrophobized. 9. A silicic acid containing no organic group and halogen, or a silicic acid precursor capable of forming the silicic acid, and 2) water.
3) a step of bringing the phosphor particles into contact with a silica film-forming composition containing at least an alkali, 4) an organic solvent, and then containing 1) polysilazane and 2) an organic solvent, 3) an amine and / or a metal ion catalyst. A method for producing phosphor particles, which comprises a step of bringing phosphor particles into contact with the composition for forming a silica film. 10. A silicic acid containing no organic group and halogen or a silicic acid precursor capable of forming the silicic acid, and 2) water.
3) a step of bringing the phosphor particles into contact with a silica film-forming composition containing at least an alkali, 4) an organic solvent, and then containing 1) polysilazane and 2) an organic solvent, 3) an amine and / or a metal ion catalyst. A method for producing phosphor particles, which comprises the step of bringing phosphor particles into contact with the composition for forming a silica film and bringing them into contact with water vapor. 11. A polysilazane having a number average molecular weight of 100.
10. The polysilazane of -50000.
A method for producing the described phosphor particles. 12. A silicic acid containing no organic group and halogen, or a silicic acid precursor capable of forming the silicic acid, and 2).
In the step of bringing the phosphor particles into contact with the composition for silica film formation containing at least water, 3) alkali, and 4) organic solvent, the water / organic solvent ratio (based on the charging capacity) is in the range of 0.1 to 10. And a silicic acid concentration in the range of 0.0001 to 5 mol / liter, the surface of the phosphor particles is selectively coated with silica by the contact, and then the first coating is applied by drying. The method for producing phosphor particles according to any one of claims 9 to 11. 13. The light emission of the phosphor particles is fluorescence.
9. The phosphor particles according to any one of 8 to 8. 14. The method for producing a phosphor particle according to claim 9, wherein the emission of the phosphor particle is fluorescence. 15. A dispersion type light emitting device using the phosphor particles according to claim 1. Description: 16. A dispersion type electroluminescence device using the phosphor particles according to claim 1. Description: 17. The phosphor particles are zinc sulfide (ZnS), calcium sulfide (CaS), strontium sulfide (SrS).
The phosphor particles according to any one of claims 1 to 8, wherein at least one selected from the above is used as a raw material. 18. The phosphor particles are zinc sulfide (ZnS), calcium sulfide (CaS), strontium sulfide (SrS).
13. The method for producing phosphor particles according to claim 9, wherein at least one selected from the above is used as a raw material.