JP5589896B2 - Method for producing silicate phosphor particles with coating film - Google Patents

Description

  The present invention relates to a method for producing a silicate phosphor particle with a coating film, and more specifically, the silicate phosphor with a coating film having no reduction in light emission intensity due to the formation of the coating film and having high moisture resistance and water resistance. The present invention relates to a method for producing salt phosphor particles.

As oxide phosphors well known as phosphor materials for white LEDs, for example, composition formula Sr ₃ SiO ₅ : Eu, (Sr, Ba) ₃ SiO ₅ : Eu, (Sr, Ba) ₂ SiO ₄ : Some are composed of a compound phase represented by Eu or the like. These are phosphors used for phosphors for high-intensity white LEDs. Yellow light is emitted by absorbing part of the excitation light from the blue LED, and white light is obtained by mixing with the blue excitation light. ing. Furthermore, (Sr, Ba) ₂ SiO ₄ : Eu used for the phosphor for high color rendering type white LED enhances the color rendering property by coloring green.

  In these alkaline earth silicate phosphors emitting yellow light, alkaline earth components as constituent elements are eluted from the inside of the phosphor by water vapor or water in the air, and hydrates or carbonates are formed on the surface. It is known to deteriorate by this. As described above, the alkaline earth silicate phosphor has a problem that the fluorescent luminance is lowered and the color tone is changed due to the long-term use in the atmosphere and the temperature rise by the excitation light.

  As a measure for improving the moisture resistance of such a phosphor, Patent Document 1 discloses silicone resin, epoxy resin, fluororesin, tetraethoxysilane (TEOS), silica, zinc silicate, silicone oil, aluminum silicate, calcium polyphosphine. A method is disclosed in which a coating film is provided on the surface of oxide phosphor particles using a fate, silicone oil, shilling lease, or the like as a coating material. According to this method, the phosphor provided with the coating film does not decrease the initial light emission intensity, and the moisture resistance is improved. However, although this method is a simple method, there is a problem that it is not easy to uniformly coat the entire surface of fine oxide phosphor particles or to control the thickness of the coating film.

  By the way, a coating film is formed on the surface of the phosphor particles using the moisture resistance improving method as described above, and the phosphor particles with the coating film thus obtained are molded to produce a phosphor element. In order to evaluate water resistance, for example, when a phosphor element was put in a high-temperature humidified atmosphere, it was found that the phosphor surface was eroded and hydrates, sulfates or carbonates were formed, and the light emission characteristics were greatly reduced. . This tendency was found to be remarkable particularly in the case of oxide phosphor particles containing alkaline earth. In this way, when the moisture resistance and water resistance of the phosphor are not improved, when the LED light emitting device produced using the phosphor is used outdoors such as for lighting and automobiles, the LED light emitting device is It will deteriorate immediately.

  Many of the causes that cause such deterioration are not only the material of the coating film but also defects (pinholes, etc.) of the coating film. For example, when a coating film is formed by forming an organic compound film such as tetraethoxysilane on the phosphor particle surface and heat-treating it, defects are formed in the coating film when the organic substance is decomposed by the heat-treatment. The As a result, moisture and moisture enter the inside of the phosphor particles through this defect, so that the phosphor particles themselves deteriorate.

  In order to avoid this problem, the thickness of the coating film is increased. However, in the most common method of hydrolyzing and coating an alkoxysilane, that is, adding an acid-alkali catalyst to water or a non-aqueous solvent to hydrolyze and condense the alkoxysilane, the alkoxysilane is slowly hydrolyzed. Since deposits are deposited on the surface of the phosphor particles through decomposition / condensation reaction, a long time treatment is required to obtain a coating film having a thickness of 50 nm or more. For this reason, since the phosphor particles having poor water resistance are in contact with moisture for a long time, the phosphor particles are deteriorated, and the eluate affects the condensation reaction of the alkoxysilane and gels the entire solution. Will occur.

  Moreover, if the hydrolysis / condensation reaction is not performed in a pH range other than the strong alkali side, elution of the constituent components from the phosphor particles is accelerated. On the other hand, when it is on the strong alkali side, the condensation reaction is promoted, and the alkoxysilane is loosened as coarse particles without being deposited on the particle surface as a coating film. Further, since this method is a treatment in a dilute liquid, only a small amount of coating can be performed per batch, and there is a problem that the production efficiency is inferior.

  Further, as a problem after the coating treatment, there is agglomeration after drying. As described above, the coating is carried out by precipitating the hydrolyzed / condensed product on the particle surface. However, immediately after filtration / drying, the coating films for the active surface may adhere to each other and aggregate. If this is forcibly crushed, the coating film peels off and the uncoated surface is exposed. Aggregated particles have a wide particle size distribution and light emission becomes non-uniform when kneaded into a silicone resin which is a sealing material for device formation, resulting in a decrease in light emission characteristics.

  On the other hand, Patent Document 2 discloses, as a method for producing a phosphor particle having a coating film having high moisture resistance and high water resistance without reducing light intensity, an underlayer of an aluminum organic compound film on the phosphor particle surface. A coating film of a silane organometallic compound condensate having a weight average molecular weight of 5,000 to 20,000 was provided on the underlayer, and this was dried and heat-treated to provide a coating film. Obtaining phosphor particles is described. However, it cannot be said that the phosphor particles obtained by this method have satisfactory moisture resistance and water resistance.

JP 2005-187797 A JP 2011-026535 A

  The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to provide a method for producing silicate phosphor particles having a coating film that does not decrease fluorescence intensity and has high moisture resistance and water resistance. And

  In order to achieve the above object, the present inventors have conducted intensive research on an efficient method for producing phosphor particles having a coating film having high moisture resistance and high water resistance without reducing the fluorescence intensity. As a result, the following knowledge was obtained regarding the cause of the decrease in moisture resistance and water resistance and the means for solving them.

  According to the conventional method described above, in particular, the method of Patent Document 2 described above, moisture resistance and water resistance are improved by providing a coating film on the surface of the phosphor particles. However, if there is only one coating film, moisture resistance and water resistance are insufficient due to defects in the coating film. A defect in the coating film is considered to be caused by a pinhole or the like generated by this gas because a gas is generated when the organic solvent or the like is removed by heat treatment after the particle surface is coated with a coating material. As a means for eliminating such defects in the coating film, it has been found that so-called double coating in which a similar coating film is further provided on the coating film is effective. That is, by repeatedly laminating the same coating film on the coating film, the defects in the coating film become discontinuous, so that the moisture resistance and water resistance are further improved.

  In addition, it was found that when double coating is performed, it is particularly effective if the coating conditions are changed between the first coating film and the second coating film. Specifically, a coating liquid containing a silane organometallic compound is used when forming the first layer coating film, and a coating process is performed with dimethylsiloxane having a Si—OH group at the terminal when the second layer is formed. The reason is to avoid contact with moisture so as not to deteriorate during the treatment of the first layer, and to form a thin coating film in a short time treatment, and to improve the adhesion to particles by drying. Then, by forming a second-layer coating film using dimethylsiloxane having a Si—OH group at the end, it adheres firmly to the first-layer coating film, and defects in the coating film This is because the coating unevenness and the like can be repaired to form a denser coating film.

That is, the method for producing a silicate phosphor particle with a coating film provided by the present invention includes the following first to fifth steps ,
The first step is a step of obtaining a partially hydrolyzed aluminum organometallic compound (a) by adding and mixing an aluminum organometallic compound, tetraethoxysilane and water for hydrolysis in an organic solvent,
In the second step, the silicate phosphor particles and the partially hydrolyzed aluminum organometallic compound (a) obtained in the first step are added and mixed in an organic solvent, vacuum separated by filtration and dried. It is a step of obtaining silicate phosphor particles (A) in which a partially hydrolyzed aluminum organometallic compound is adsorbed as an underlayer,
In the third step, a silane organometallic compound, an aluminum organometallic compound, and water for hydrolysis are added to an organic solvent, and mixed by stirring to obtain a hydrolysis condensate of the silane organometallic compound. A step of concentrating the product to obtain a first coating liquid (b),
In the fourth step, the silicate phosphor particles with an underlayer obtained in the second step (A) and the first coating liquid (b) obtained in the third step are added and mixed in an organic solvent, and vacuum filtration is performed. After that, it is a step of obtaining silicate phosphor particles (B) provided with the first coating film by forming a first coating film by heat treatment at 110 to 350 ° C. in an air atmosphere,
In the fifth step, phosphor particles (B) provided with the first coating film obtained in the fourth step and dimethylsiloxane having a Si-OH group at the end are added and mixed in an organic solvent, and vacuum filtration is performed. Then, it is the process of obtaining the silicate fluorescent substance particle (C) with a coating film by heat-processing at 250-300 degreeC by an atmospheric condition, and forming a 2nd coating film.

  According to the present invention, since a dense and defect-free coating film can be formed on the particle surface, silicate phosphor particles having very high moisture resistance and water resistance can be efficiently produced without reducing fluorescence intensity. Can be manufactured automatically.

  In the present invention, first, a partially hydrolyzed aluminum organic compound is adsorbed on the surface of the phosphor particles serving as the core material. The partially hydrolyzed aluminum organic compound film serves as an underlayer, and improves the adhesion with the first coating film formed thereon, and also protects the particles from moisture contained in the first coating film. Fulfill. In addition, although water for hydrolysis is also added to the aluminum organic compound, since almost all of the added water is consumed in the hydrolysis reaction, the solution and phosphor of the partially hydrolyzed aluminum organic compound Even if the particles are in direct contact, the effect of moisture is very small.

  Next, a first coating film is formed on the base layer using a first coating liquid containing a hydrolysis condensate of a silane organic compound. Although it is already known that the surface of the phosphor particles is coated with the hydrolyzed condensate of this silane organic compound, the coating film alone is not sufficient for phosphors that require extremely high water resistance. When contacted with moisture for a period of time, the phosphor particles will deteriorate. Therefore, in the present invention, the surface of the phosphor particles is double coated by forming a second coating film on the first coating film.

  In forming the second coating film, it is important to use dimethylsiloxane having a Si—OH group at the terminal. The reason is that the first coating film and the second coating film are considered to be adsorbed and laminated by hydrogen bonding of hydroxyl groups, but the first coating film made of a hydrolytic condensate of a silane organometallic compound is heated. Since it is dried, the hydroxyl groups on the film surface are reduced, and there is a concern that hydrogen bonds with the second coating film will be weakened. Therefore, in order to compensate for a decrease in bonding force due to a decrease in hydroxyl groups on the surface of the first coating film, it is important to use dimethylsiloxane having a Si—OH group at the terminal as the second coating film.

The silicate phosphor particles used as the core material in the present invention include at least one selected from strontium (Sr), barium (Ba) and europium (Eu) in addition to silicon (Si) and oxygen (O) as constituent elements. It contains seed elements and has an average particle diameter of D50 of 1 to 30 μm. For example, a silicate phosphor that emits yellow light and includes a compound phase represented by a composition formula of Sr ₃ SiO ₅ : Eu or (Sr, Ba) ₃ SiO ₅ : Eu is preferable.

The composition and emission characteristics of the silicate phosphor emitting yellow light will be described. For example, a silicate phosphor having a composition formula of Sr ₃ SiO ₅ : Eu has an emission spectrum of 540 when excited with light having a wavelength of 430 to 470 nm. It has an emission peak in the wavelength range of ˜610 nm, preferably an emission peak in the wavelength range of 560 to 590 nm. The composition range of Eu as a binder is less than 5 mol%, and the luminance decreases. On the other hand, if it exceeds 20 mol%, sufficient luminance cannot be obtained by concentration quenching. A range is preferred.

A silicate phosphor having a composition formula (Sr, Ba) ₃ SiO ₅ : Eu in which a part of Sr is substituted with Ba has an emission peak in a wavelength range of 565 to 575 nm. The molar ratio of the Ba amount to the total amount of Sr is usually preferably 1% or more, and more preferably in the range of 2 to 10%. Ba normally replaces the Sr original position, but when the ratio of the amount of substitution by Ba increases, the light emission becomes yellowish and the light emission efficiency tends to decrease. In addition, a commercial item can be used for these silicate fluorescent substance.

These silicate phosphors can be produced by a solid phase method as described in JP-A-2006-036943. Sr ₃ SiO ₅ : Eu can also be produced by a method different from the solid phase method described in JP 2010-189583 A. For example, a metal element compound, water-soluble silicon, and a solvent are placed in a sealed container and heated to obtain a silicon-containing gel in which the metal element is uniformly dispersed, and the solvent is removed from the gel to obtain a dry gel. Organic gel is removed by heating the gel in a state, and the obtained composite metal oxide precursor is heat-treated to obtain phosphor particles. The metal element compound as a raw material may be any material that can be dissolved in a solvent, and oxides, hydroxides, acetates, nitrates, carbonates, and sulfates can be used. Water-soluble silicon is made by adding hydrochloric acid and water to a mixture of tetraethoxysilane and propylene glycol.

  Next, the manufacturing method of the silicate fluorescent substance particle with a coating film of the present invention is explained in detail according to a process.

"First step"
The first step is a step of adjusting the partially hydrolyzed aluminum organometallic compound (a) used for forming the underlayer. That is, a partially hydrolyzed aluminum organometallic compound (a) is obtained by adding and mixing an aluminum organometallic compound, tetraethoxysilane, and water for hydrolysis in an organic solvent.

  The aluminum organometallic compound is hydrolyzed by reacting with the adsorbed water on the particle surface and the water mixed as an impurity in the drug, but water is added for more active hydrolysis. Thereby, a part of the functional group of the aluminum organometallic compound is hydrolyzed, and the hydrolyzed functional group is changed to a hydroxyl group. Since the ratio of adsorption to the surface of the phosphor particles increases due to the increase of the hydroxyl groups, the underlayer is formed uniformly and with good adhesion. In addition, the uniformity and adhesion of the underlayer are further improved by mixing 5% by weight of tetraethoxysilane (TEOS) with the aluminum organometallic compound.

  The amount of water to be added is not particularly limited as long as the aluminum organometallic compound is partially hydrolyzed. Preferably, 5 to 10% by weight of water is added to the aluminum organometallic compound. If a large amount of water is added, moisture remains in the liquid and the phosphor particles deteriorate, which is not preferable. The water used for the hydrolysis is preferably ion-exchanged water having a conductivity of 4 μS / cm or less.

  The hydrolysis of the aluminum organometallic compound is desirably performed in an airtight state in a sealed container in order to prevent moisture from entering. Moreover, as preferable reaction conditions, it stirs and mixes for 2 to 10 hours, controlling temperature at 18-40 degreeC. However, if the hydrolysis proceeds too much, the viscosity increases due to condensation and gelation occurs, so the adhesiveness decreases.

The organic solvent used for hydrolysis is not particularly limited, but is represented by the general formula: R ₂ OH (where R represents a monovalent hydrocarbon group having 1 to 6 carbon atoms). Alcohol is preferable, and ethanol or isopropyl alcohol is particularly preferable among them. The addition amount of the organic solvent is preferably about 1: 1 by weight with respect to the aluminum organometallic compound.

  Although it does not specifically limit as said aluminum organometallic compound, The thing compatible with the alcohol of the above-mentioned organic solvent and the high adsorption power to the fluorescent substance particle surface is desirable. Specifically, aluminum chelate compounds containing alkyl groups such as ethyl acetoacetate aluminum diisopropylate, aluminum tris (ethyl acetoacetate), octyl acetoacetate aluminum diisoproprate, aluminum monoacetylacetonate bis (ethyl acetoacetate) Is preferred. Among these, ethyl acetoacetate aluminum diisopropylate having high compatibility with ethanol and isopropyl alcohol is more preferable.

"Second step"
In the second step, the silicate phosphor particles (A) are formed by forming a base layer of the partially hydrolyzed aluminum organometallic compound (a) obtained in the first step on the surface of the silicate phosphor particles. It is a process to obtain. That is, a partially hydrolyzed aluminum organometallic compound is prepared by adding and mixing a silicate phosphor particle and a partially hydrolyzed aluminum organometallic compound (a) in an organic solvent, separating by vacuum filtration and drying. Silicate phosphor particles (A) adsorbed as an underlayer are obtained.

  Specifically, after adding silicate phosphor particles in an organic solvent and dispersing by applying ultrasonic vibration of 28 to 48 kHz for 5 to 30 minutes, the partially hydrolyzed aluminum obtained in the first step The organometallic compound (a) is mixed and dispersed. Instead of the above mixing procedure, a partially hydrolyzed aluminum organometallic compound (a) may be mixed and dispersed in an organic solvent, and then phosphor particles may be added and mixed. Next, by stirring and mixing for 2 to 18 hours, the partially hydrolyzed aluminum organometallic compound (a) is adsorbed on the surface of the phosphor particles.

The blending ratio of the phosphor particles, the organic solvent, and the aluminum organometallic compound (a) is not particularly limited. For example, the weight ratio of the phosphor particles 1 to the organic solvent is 5 to 50. Is preferred. In the mixing and stirring, it is desirable to mix in an airtight state such as in a sealed container in order to prevent moisture from being mixed. As the mixing means, a method using a stirrer such as a stirring blade or a stirrer or a method using an ultrasonic homogenizer can be employed. As the organic solvent, is not particularly limited, as in the case of the first step, the general formula: is preferably an alcohol solvent represented by R 2 _OH, in particular ethanol or isopropyl alcohol is preferred.

  Thereafter, the solid content and the organic solvent are separated by vacuum filtration and dried to obtain silicate phosphor particles (A) in which a partially hydrolyzed aluminum organometallic compound is bonded to the surface as an underlayer. Regarding vacuum filtration, it is preferable to perform filtration at a vacuum degree of 0.05 to 0.1 MPa not only in the second step but also in the fourth and fifth steps. In addition, although the organic solvent can be volatilized and removed by heating instead of the vacuum filtration, vacuum filtration is preferable from the viewpoint of convenience. In addition, when drying after separation of the organic solvent, it is preferable to dry by heating at a temperature higher than 80 ° C., because the adsorbed aluminum organometallic compound is denatured and the adsorptivity with the silane organometallic compound is lowered in a later step. Absent.

  The base layer of the partially hydrolyzed aluminum organometallic compound formed on the surface of the phosphor particles has the effect of improving the uniformity of the coating film formed thereon and the moisture contained in the coating liquid for coating formation. The effect which suppresses the influence of can be fulfilled. The thickness of the underlayer is not particularly limited, and may be thin as long as aggregation between particles and film peeling do not occur during drying.

"Third step"
The third step is a step of preparing the first coating liquid (b), in which a silane organometallic compound, an aluminum organometallic compound, and water for hydrolysis are added to an organic solvent, followed by stirring and mixing to obtain a silane organometallic. After obtaining the hydrolysis condensate of the compound, the hydrolysis condensate is concentrated to obtain the first coating liquid (b).

  Specifically, a silane organometallic compound, an aluminum organometallic compound acting as a catalyst, and water for hydrolysis are added to an organic solvent, and the mixture is stirred and mixed for 18 to 96 hours to hydrolyze the silane organometallic compound. A condensate (b) is produced. Next, the first coating liquid (c) is obtained by concentrating the obtained solution until the liquid amount becomes 80 to 70% with respect to the original weight. In the stirring and mixing, it is desirable to mix in an airtight state such as in a sealed container in order to prevent moisture from being mixed. Further, during the concentration, strong stirring is performed in an open container to volatilize and remove excess solvent, moisture, and unreacted substances. By using the concentrated first coating liquid (b), the obtained first coating film becomes dense, and water resistance and moisture resistance are remarkably improved.

  Regarding the formation of the hydrolyzed condensate of the silane organometallic compound, the hydrolytic condensation reaction proceeds due to the action of the aluminum organometallic compound and water, and the dehydration condensation reaction proceeds gradually over time, and the molecular weight gradually increases. . At this time, if the molecular weight of the hydrolyzed condensate becomes too large, the coverage on the particle surface in the next fourth step is lowered. On the other hand, if the hydrolyzed condensate has a very small molecular weight, the film quality is deteriorated due to volatilization or the like and heat resistance and water resistance cannot be improved by heat treatment in the subsequent fifth step. For this reason, it is preferable to make the weight average molecular weight of the hydrolysis-condensation product of a silane organometallic compound into the range of 5,000-20,000.

  The end point of the hydrolysis condensation reaction can be determined by measuring the viscosity or measuring the NMR of the solution. This is because the degree of progress of the condensation reaction can be grasped by viscosity measurement or NMR measurement. Moreover, the weight average molecular weight of a hydrolysis-condensation product can be measured by a gel permeation chromatograph (GPC) analysis method. A measurement sample is prepared by collecting 2 cc of the hydrolyzed condensate, adding 18 cc of tetrahydrofuran thereto, stirring and filtering.

  Although it does not specifically limit as a silane organometallic compound, Trialkoxysilane is preferable from stability at the time of preparation of a hydrolysis-condensation product (b), coating property, and film quality. Specifically, trialkoxysilane such as methyl-, ethyl-, i-propyl-, i-butyl-, n-propyl-, n-butyl- is preferable. Among these, methyltriethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, and n-propyltrimethoxysilane are preferable, and methyltrimethoxysilane or methyltriethoxysilane is more preferable. That is, since methyltrimethoxysilane and methyltriethoxysilane have an appropriate reaction rate, instability such as a sudden increase in viscosity, formation of precipitates, or clouding even in the production of hydrolysis condensate over a long period of time. It does not occur and it is easy to control to a desired molecular weight.

Although it does not specifically limit as an aluminum organometallic compound, What was illustrated as an aluminum organometallic compound which can be used at the said 1st process is preferable, and especially ethyl acetoacetate aluminum diisopropylate is preferable. The reason why the aluminum organometallic compound is used in the third step is to utilize a function as a dispersant for dispersing the phosphor particles and a catalytic function for promoting and activating the condensation of the silane organometallic compound. As the organic solvent, as in the case of the first step, an alcohol solvent represented by the general formula: R ₂ OH is preferable, and ethanol or isopropyl alcohol is particularly preferable. Moreover, as water for a hydrolysis, the ion exchange water whose electrical conductivity is 4 microsiemens / cm or less is preferable.

  The mixing ratio of the organic solvent, the silane organometallic compound, the aluminum organometallic compound, and the water is, for example, a weight ratio of 0.5 to 1 times the amount of the organic solvent and the aluminum organometallic compound with respect to the silane organometallic compound. It is preferable to make 0.0125 to 0.05 times the amount of water and 0.2 to 0.5 times the amount of water. When the amount of the organic solvent is larger than the above blending ratio, the time required for the concentration step becomes long. Also, when the amount of aluminum organometallic compound exceeds the above blending ratio, the reaction of the silane organometallic compound becomes too active, and the organometallic compound condensate aggregates without adsorbing to the particle surface, forming a coarse precipitate in the solvent. Since it becomes easy to do, it is not preferable.

  In addition, in the hydrolysis condensation reaction in the third step, in order to control the amount of water, attention must be paid to the method of maintaining an airtight state during stirring and mixing and the amount of water contained in the organic solvent. That is, since the silane organometallic compound undergoes a hydrolytic condensation reaction with moisture, the control of the amount of moisture greatly affects the stability of the reaction. The amount of water contained in the organic solvent to be used is preferably 0.2 g / l or less with a Karl Fischer moisture meter.

  The hydrolysis condensation reaction is carried out over a certain period of time so as not to become cloudy or form a precipitate. By carrying out like this, the hydrolysis-condensation product of the weight average molecular weight 5,000-20,000 can be obtained with a sufficient yield. Specific stirring and mixing conditions in the third step are not particularly limited, but it is preferable to satisfy the following requirements.

  That is, it is desirable that the stirring and mixing be performed in an airtight state in a sealed container in order to prevent moisture from entering. The mixing temperature is preferably 18 to 40 ° C, more preferably 18 to 30 ° C, and still more preferably 20 to 25 ° C. When the temperature is lower than 18 ° C., the reaction becomes insufficient. When the temperature is higher than 30 ° C., the reaction becomes too vigorous, and the liquid becomes cloudy or forms a precipitate. As a means for stirring and mixing, a known stirring blade, a method using a stirrer such as a stirrer, an ultrasonic homogenizer, or the like can be used.

  The mixing time is preferably 18 to 96 hours, more preferably 36 to 72 hours. When the mixing time is less than 18 hours, the hydrolysis / condensation reaction is insufficient, and many low molecules are likely to be contained in the hydrolysis-condensation product. For this reason, the resistance to heat or water is inferior and may not function as a good coating film. On the other hand, when the mixing time exceeds 96 hours, the adsorptivity of the formed coating film tends to be inferior, and an uncoated portion tends to be locally generated.

  Concentration of the hydrolysis-condensation product is preferably concentrated until the liquid amount is 80 to 70% by weight percentage with respect to the original weight before the start of the treatment, more preferably 80 to 75%. . When the volatilization amount is small and the weight reduction is not sufficient, the denseness of the first coating film formed with the obtained first coating liquid (b) is not improved. On the other hand, if it is volatilized too much, the liquid viscosity will rise abruptly, so that it cannot be used as a coating liquid.

  After the above concentration, the first coating liquid (b) is obtained by vacuum filtration and separation preferably at a vacuum degree of 0.05 to 0.1 MPa. The hydrolyzed condensate of the silane organometallic compound in the first coating liquid (b) preferably has a weight average molecular weight of 5,000 to 20,000, and more preferably 7,000 to 12,000. If the weight average molecular weight is less than 5,000, the amount of scattering during the heat treatment increases, so that a dense coating film cannot be obtained. On the other hand, when the weight average molecular weight is larger than 20,000, the adsorptivity to the underlayer is lowered, resulting in poor coverage.

"4th process"
In the fourth step, the silicate phosphor particles (A) obtained in the second step, the first coating liquid (b) obtained in the third step, and the organic solvent for dilution are mixed and vacuum filtered. This is a step of obtaining silicate phosphor particles (B) having a first coating film formed on the surface by heat treatment at a temperature of 110 to 350 ° C. in an air atmosphere after separation.

  First, the silicate phosphor particles (A) having an underlayer obtained in the second step are sufficiently dispersed in an organic solvent in advance. That is, when the coating treatment with the first coating liquid (b) is performed in a state where the phosphor particles (A) having the base layer are aggregated, the entire surface of the particles cannot be coated, and moisture resistance and water resistance are improved. Because it does not. By adding an organic solvent for dilution, the viscosity of the first coating liquid (b) whose viscosity has been increased by concentration can be lowered, and the dispersibility of the aggregates can be increased.

  As another diluting effect, the stirring property is improved by lowering the liquid viscosity, and the uniformity of the resulting coating film can be enhanced. For example, when the first coating liquid (b) is mixed with the silicate phosphor particles (A) having the base layer without diluting, the first coating liquid contains moisture, so components are eluted from the phosphor particles. Although the liquid may be gelled by stirring for a short time of about 10 minutes, if it is diluted with an organic solvent in advance, the coating can be satisfactorily performed without gelation even after 60 minutes.

The organic solvent for dilution is not particularly limited, and an alcohol solvent represented by the general formula: R ₂ OH (R represents a monovalent hydrocarbon group having 1 to 6 carbon atoms) is preferable, Ethanol is particularly preferable. This is because dilution with higher alcohol may break the molecular structure of the first coating liquid (b). Moreover, the dilution amount of an organic solvent is a weight ratio, and it is preferable to add 2-50 times amount with respect to a silicate fluorescent substance particle (A).

  Moreover, in order to fully disperse the silicate phosphor particles (A) added to the organic solvent, it is desirable to perform redispersion treatment after the addition to the organic solvent. The redispersion treatment is preferably performed in a short period of time, for example, about 48 minutes at 48 kHz because the underlayer peels off from the silicate phosphor particles (A) for a long time and the effect is reduced.

  The mixing ratio of the silicate phosphor particles (A) and the first coating liquid (b) is preferably 1 to 6 times the coating liquid (c) with respect to the silicate phosphor particles (A) by weight ratio. An amount of ˜6 times is more preferable. If the added amount of the first coating liquid (b) is less than 1-fold amount, the amount of filtration is increased, and waste is increased. If the added amount is more than 6-fold amount, stirring tends to be insufficient, and good coverage is obtained. Since it becomes difficult to form a coating film, it is not preferable.

  The stirring and mixing of the silicate phosphor particles (A) and the first coating liquid (b) may be performed in an airtight state, but can also be performed in an open state in order to volatilize excess organic solvent, and is particularly obtained. There is no difference in film quality. The stirring temperature is preferably 18 to 40 ° C, more preferably 18 to 30 ° C, and particularly preferably 20 to 25 ° C. The stirring time is preferably 0.2 to 2 hours, and more preferably 0.5 to 1 hour. If the stirring time is short, the coating is not sufficient. Conversely, even if stirring is performed for 2 hours or more, no further improvement in the coating property is observed.

  The means for stirring and mixing is not particularly limited, and can be performed by a method using a known stirrer such as a stirring blade or a stirrer, or a method using an ultrasonic homogenizer or the like. In stirring and mixing, it is effective to increase the stirring so that the silicate phosphor particles (A) do not precipitate, in order to achieve uniform coating.

  After completion of the stirring and mixing, solid-liquid separation is performed by vacuum filtration. The degree of vacuum at that time is preferably in the range of 0.05 to 0.1 MPa. The collected phosphor particles are heat-treated at a temperature of 110 to 350 ° C. in an air atmosphere to obtain silicate phosphor particles (B) having a first coating film. The time for the heat treatment is not particularly limited, but is preferably about 0.5 to 18 hours. By this heat treatment, the organic matter in the first coating film is thermally decomposed, and a first coating layer made of an amorphous inorganic compound film mainly composed of Al, Si, and O is formed on the surface of the silicate phosphor particles. Is done.

  The film thickness of the first coating layer formed in the fourth step is preferably about 50 nm. If the film thickness of the first coating layer is too thin than 50 nm, sufficient moisture resistance and water resistance cannot be obtained. Further, in order to form the film thicker than 50 nm, it is necessary to increase the proportion of the first coating liquid (b), or to increase the processing time or increase the processing temperature. However, if the proportion of the first coating liquid (b) is increased, the silicate phosphor particles (B) will be agglomerated and solidified during the heat treatment after filtration, and if the coating treatment time is lengthened, there will be a problem in terms of cost. Increasing the treatment temperature is not preferable because the phosphor particles deteriorate.

  In order to avoid the aggregation and solidification of the silicate phosphor particles (B) during the heat treatment after the filtration, it is effective to wash at the time of filtration. If the washing is neglected, the particles are heated and dried with the first coating liquid accumulated between the particles, so that the agglomeration becomes remarkable. In particular, the smaller the particle size, the stronger the tendency. In order to alleviate such agglomeration and solidification, it is desirable to remove the coating liquid in a free state by washing the filtered phosphor particles with an organic solvent.

  The silicate phosphor particles (B) provided with the first coating film obtained in the fourth step have a certain degree of good moisture resistance and water resistance, but leave few defects in the first coating film. There are many. This defect is caused by thermal decomposition of an organic substance during heat treatment, or due to unevenness of the particle surface or surface condition. If even such a defect remains, moisture enters from the defect and the phosphor is gradually deteriorated, which may cause a problem in long-term reliability.

"5th process"
The fifth step is a step of further forming a second coating film on the first coating film formed in the fourth step, and the silicic acid having the first coating film obtained in the fourth step After mixing the salt phosphor particles (B), dimethylsiloxane having a Si-OH group at the terminal, and an organic solvent for dilution, stirring and mixing, the phosphor particles separated by vacuum filtration are 250 to Heat treatment is performed at a temperature of 300 ° C. to obtain phosphor particles (C) with a coating film.

  As described above, since defects often exist in the first coating film of the silicate phosphor particles (B) obtained in the fourth step, in this fifth step, the first coating film is further formed on the first coating film. Since the defect can be made discontinuous by forming the second coating film and double-coating, it is possible to further improve the moisture resistance and water resistance.

  In the fifth step, it is important to use dimethylsiloxane having a Si—OH group at the terminal. The reason is that in the fourth step, heat treatment is performed at a temperature of 110 ° C. or higher when the first coating film is formed, so that hydroxyl groups on the surface of the first coating film are lost to some extent. In order to firmly adhere the second coating film to the first coating film, it is necessary to use a highly active coating material as the second coating film. A dimethylsiloxane having an OH group is selected.

  That is, according to the examination of the coating materials by the inventors, it has been found that most of the commercially available modified siloxanes undergo thermal decomposition from around 200 ° C., and these cannot be expected to have a coating effect at all when evaluated by a moisture resistance test. . On the other hand, it was found that dimethylsiloxane having a Si—OH group at the terminal can react with the Si—O group on the surface of the first coating film very quickly and can be firmly bonded. In addition, as a specific example of dimethylsiloxane having a Si—OH group at the terminal, for example, KPN3504 manufactured by Shin-Etsu Chemical Co., Ltd. can be preferably used.

  Here, when forming a 2nd coating film using dimethylsiloxane which has a Si-OH group at the terminal, it is necessary to pay attention to the following points. That is, the Si—OH group of dimethylsiloxane reacts with Si—O of the first coating film and bonds strongly, but the surface of the silicate phosphor particle also has Si—O, so the first coating If the formation of the film is incomplete, the Si—OH group of dimethylsiloxane and the Si—O on the surface of the silicate phosphor particles react directly to deteriorate the light emission characteristics. In order to avoid this, it is necessary to finally heat-treat at 110 to 350 ° C. in the previous fourth step to densify and mineralize the first coating film. The —OH group can be bonded only to the first coating film.

  The blending amount of dimethylsiloxane having a Si—OH group at the terminal is preferably 0.05 to 1 times the weight of the silicate phosphor particles (B) obtained in the fourth step. When the blending amount of dimethylsiloxane is less than 0.05 times by weight with respect to the silicate phosphor particles (B), the coating as the second coating film is insufficient. Moreover, when the said compounding quantity of dimethylsiloxane exceeds 1 time amount, since aggregation of the particle | grains after drying will become strong and precipitation will be produced at the time of resin kneading | mixing, it is not preferable.

The dimethylsiloxane and silicate phosphor particles (B) are mixed with an organic solvent in an amount of 2 to 20 times by weight with respect to the silicate phosphor particles (B) for dilution. The obtained mixture is preferably redispersed by applying ultrasonic vibration. The organic solvent for dilution is not particularly limited, and an alcohol solvent represented by the general formula: R ₂ OH (R represents a monovalent hydrocarbon group having 1 to 6 carbon atoms) is preferable, Ethanol and isopropyl alcohol are particularly preferable.

  The dimethylsiloxane and silicate phosphor particles (B) added and mixed in the organic solvent as described above are preferably stirred and mixed in an airtight state, and then solid-liquid separated by vacuum filtration to recover the silicate phosphor particles. . The conditions for stirring and mixing are not particularly limited, but are preferably 0.2 to 2 hours at a temperature of 18 to 40 ° C.

  After the stirring and mixing is completed, solid-liquid separation is performed by vacuum filtration to recover silicate phosphor particles. The recovered silicate phosphor particles can be heat-treated at a temperature of 250 to 300 ° C. in an air atmosphere to form a second coating film on the first coating film of the phosphor particles. This is because when the temperature of the heat treatment is less than 250 ° C., organic residues remain in the second coating film, so that a high-quality film quality cannot be obtained, and when it exceeds 300 ° C., the second coating film is thermally decomposed. The heat treatment time is preferably 0.5 to 2 hours.

  Further, it is said that the phosphor is exposed to about 200 ° C. at maximum due to the heat generation temperature received from the LED. Therefore, when the phosphor in a state where organic matter is mixed in the coating film is kneaded into the LED sealing agent and cured and incorporated on the LED blue element, the organic matter is decomposed when the temperature reaches about 200 ° C. Gas is generated and the LED element is contaminated, and at the same time, the performance of the coating film is lowered. In order to avoid such a situation, in the fifth step, after finally heat-treating at a temperature of 250 to 300 ° C., the obtained silicate phosphor particles with a coating film of the present invention are put in a sealant. Knead and use.

  The coating film composed of the first coating film and the second coating film formed through the first to fifth steps is made of an amorphous inorganic oxide mainly composed of Al, Si, and O, The final film thickness is preferably in the range of 150 to 250 nm. This double-coated coating film significantly improves moisture resistance and water resistance, and sufficient mechanical strength is obtained, so that the coating film is not peeled off or cracked even when the resin is kneaded.

  The silicate phosphor particles with a coating film according to the present invention have a coating film made of an amorphous inorganic compound film mainly composed of Al, Si, and O on the surface. Since the silicate phosphor particles provided with the coating film of the present invention are coated in each optimized process, the fluorescence intensity does not decrease and has high moisture resistance and high water resistance. .

First, Sr ₃ SiO ₅ : Eu was manufactured as silicate phosphor particles. That is, a 3M aqueous solution was prepared using strontium nitrate as the metal element compound, and this solution was mixed with a water-soluble silicon aqueous solution corresponding to 1M silicon to obtain a transparent mixed solution. Put this mixed solution in a polytetrafluoroethylene (PTFE) hydrothermal container (internal volume 100 ml), cover it, place this container in a stainless outer container, and use a torque wrench with a torque of 18 Nm. Tightened and closed the lid. This was put in a dryer at 200 ° C. and allowed to stand for 24 hours, and then allowed to cool to room temperature, then the lid was opened and the inner container was taken out to obtain a solidified hydrous gel.

Next, the solidified hydrous gel was transferred to a beaker and dried at 100 ° C. for about 10 hours to completely remove the solvent, thereby obtaining a dried gel. This dried gel was replaced in a beaker and subjected to a heat treatment at 800 ° C. for 12 hours in a vacuum of 300 Pa to completely remove residual carbon and obtain a precursor. This precursor is put into an alumina crucible of 10 ml size, the crucible is embedded in a 50 ml size alumina crucible filled with graphite powder, covered, and subjected to heat treatment at a heat treatment temperature of 1500 ° C. for 12 hours in an electric furnace. A silicate phosphor of the formula Sr ₃ SiO ₅ : Eu was prepared.

Using the silicate phosphor particles of Sr ₃ SiO ₅ : Eu, a coating film was formed according to the following examples and comparative examples. The organic solvent used in Examples and Comparative Examples was used after removing moisture by putting 500 g of a previously dried molecular sieve (3A) in 10 liters of an organic solvent. The water content in the ethanol and isopropyl alcohol (IPA) used was 0.1 g / l with a Karl Fischer moisture meter. In addition, the film thickness and adhesion of the coating film used for evaluation in Examples and Comparative Examples, electrical conductivity, water resistance (dielectric constant change), moisture resistance (light emission intensity change before and after the moisture resistance test), and coating The measuring method of the light emission intensity change before and after film formation is as follows.

  (1) Film thickness: Using a sample obtained by embedding silicate phosphor particles in an epoxy resin and processing the cross section after curing, the film thickness of the coating film (n = 5) is measured by SEM or TEM observation, and the average film The thickness was determined. Since the coating film can make the contrast due to the difference in composition, the secondary electron image and the reflected electron image can be clearly observed. In addition, when the coating film of the particle | grains obtained in the Example was analyzed by SEM-EDX, since the element of Si and O was detected, it was confirmed that the film observed by shading is due to the coating.

  (2) Adhesiveness of coating film: 10% by weight of a silicate-coated phosphor is added to a silicone resin (manufactured by Toray Dow Co., Ltd., JCR6175A / B), and a stirring mixer (ARV310-LED, manufactured by Sinky Corporation) is used. Vacuum stirring was performed at 1200 rpm for 10 minutes. The obtained resin mixed sample was cured at 150 ° C. for 2 hours, and a TEM cross section was observed. Evaluation of the adhesion of the coating film by TEM cross-sectional observation is as follows: ○ where no separation or void is observed at the interface between the particle and the coating film, and x where peeling or void is observed at the interface between the particle and the coating film. It was.

  (3) Change in conductivity: Silicate phosphor particles were put into water to determine the change in conductivity. That is, when the phosphor particles are inferior in water resistance, components are eluted from the surface of the particles into the water, so that the conductivity increases with the immersion time. Therefore, 0.1 g of phosphor particles was put into 100 ml of warm water at 25 ° C., and the electric conductivity after stirring for 10 minutes was measured, and the difference from the dielectric constant before the addition was determined.

  (4) Change in emission intensity: PL (Photo Luminescence) emission intensity before and after the formation of the coating film of the silicate phosphor particles, and PL emission intensity before and after the moisture resistance test of the silicate phosphor particles with the coating film were measured. The PL emission intensity was obtained from the intensity of the emission spectrum with 450 nm excitation light using a spectrofluorometer FP6500 manufactured by JASCO Corporation. The conditions for the moisture resistance test were 85 ° C. × 85% RH × 250 hours.

[Example 1]
The following 1st-5th processes were implemented and the silicate fluorescent substance particle (C) with a coating film was manufactured. Specifically, in the first step, 80 g of IPA (manufactured by Kanto Chemical Co., Ltd., reagent grade), 95 g of ethyl acetoacetate aluminum diisopropylate (manufactured by Kawaken Fine Chemical Co., Ltd., ALCH S75P: concentration 75% by weight), tetraethoxysilane (TEOS) : Reagent) manufactured by Kanto Chemical Co., Inc. was added and mixed. In this mixed solution, a solution obtained by mixing 10 g of pure water with 10 g of IPA (manufactured by Kanto Chemical Co., Inc., reagent grade) is mixed, and mixed in an airtight container at 23 ° C. for 2 hours to partially hydrolyze an aluminum organometallic compound. (A) was obtained.

Next, in the second step, a base layer was formed on the surface of the phosphor particles using the partially hydrolyzed aluminum organometallic compound (a). That is, 20 g of the above Sr ₃ SiO ₅ : Eu silicate phosphor particles (D50 = 11 μm) are added to 100 g of IPA (manufactured by Kanto Chemical Co., Ltd., reagent grade), and dispersed by treatment with a 28 kHz ultrasonic cleaner for 5 minutes. I let you. 40 g of the partially hydrolyzed aluminum organometallic compound (a) obtained in the first step was added to this dispersion, and the mixture was stirred and mixed at 23 ° C. for 2 hours in a sealed container. Thereafter, solid-liquid separation was performed by vacuum filtration to obtain phosphor particles (A) on which an aluminum organometallic compound was adsorbed as an underlayer.

  In the third step, the first coating liquid (b) was produced. Specifically, 1000 g of methyltrimethoxysilane (manufactured by Toray Dow Corning Co., Ltd., Z-6366), 680 g of ethanol (manufactured by Kanto Chemical Co., Ltd., reagent grade), ethyl acetoacetate aluminum diisopropylate (manufactured by Kawaken Fine Chemical Co., Ltd., ALCH S75P (concentration: 75% by weight) and 320 g of ion-exchanged water were added and stirred vigorously with a stirrer while maintaining the temperature at 23 ° C.

  The stirring and mixing were continued for 72 hours to obtain a hydrolysis condensate of a silane organometallic compound. The viscosity of the hydrolysis condensate at this time was 6 mPa · S. 100 g of this hydrolyzed condensate was taken out, and concentrated with a stirrer in an open container until the liquid amount became 75% of the original weight to obtain a first coating liquid (b).

In the next fourth step, a first coating film was formed on the surface of the Sr ₃ SiO ₅ : Eu silicate phosphor particles (B) with the underlayer using the first coating liquid (b). That is, 20 g of phosphor particles with the underlayer (A) obtained in the second step, 70 g of the first coating liquid (b) obtained in the third step, and 40 g of ethanol were mixed, and 5 with a 48 kHz ultrasonic cleaner. Redispersed for minutes. Next, after stirring and mixing in a sealed container at 23 ° C. for 1 hour, vacuum filtration was performed for solid-liquid separation, and 30 g of IPA alone was passed through the obtained phosphor particles to wash them, followed by vacuum filtration again. The vacuum filtration conditions were all set to a vacuum degree of 0.05 to 0.1 MPa. Thereafter, 10 g of the collected phosphor particles were heat-treated at a temperature of 300 ° C. for 1 hour and dried to obtain phosphor particles (B) provided with the first coating film.

  Finally, silicate phosphor particles (C) with a coating film were produced by double coating in the fifth step. That is, 1.5 g of dimethylsiloxane having a Si—OH group at the end (manufactured by Shin-Etsu Chemical Co., Ltd., KPN3504) and 30 g of ethanol for dilution are added to 5 g of the phosphor particles (B) prepared in the fifth step, and a sealed container The mixture was stirred and mixed at 23 ° C. for 1 hour, and then separated into solid and liquid by vacuum filtration. The obtained phosphor particles were dried at 110 ° C. for 1 hour and then heated and fired at 250 ° C. for 0.5 hour to form a second coating film.

  With respect to the silicate phosphor particles with the coating film (C) thus obtained, the film thickness of the coating film, the adhesion of the coating film, and the water resistance of the silicate phosphor particles are obtained by the above-described methods. Table 1 below shows the evaluation results obtained by measuring the change in light emission intensity before and after the formation of the coating film and the moisture resistance.

[Example 2]
As silicate phosphor particles, instead of Sr ₃ SiO ₅ : Eu in Example 1 above, commercially available (Sr _0.95 , Ba _0.05 ) ₃ SiO ₅ : Eu (Tokyo Chemical Research Institute, D50 = 25 μm) ), The following first to fifth steps were carried out to produce silicate phosphor particles (C) with a coating film.

In the first step, a partially hydrolyzed aluminum organometallic compound (a) was produced in the same manner as in Example 1. In the next second step, 20 g of (Sr _0.95 , Ba _0.05 ) ₃ SiO ₅ : Eu silicate phosphor particles are added to 100 g of IPA (manufactured by Kanto Chemical Co., Ltd., reagent grade), and ultrasonic cleaning at 28 kHz is performed. Redispersed by processing in a vessel for 10 minutes. 40 g of the partially hydrolyzed aluminum organometallic compound obtained in the first step was added to this dispersion, and the mixture was stirred and mixed at 23 ° C. for 4 hours. Thereafter, solid-liquid separation was performed by vacuum filtration, and the phosphor particles (A) adsorbed with a partially hydrolyzed aluminum organometallic compound as an underlayer were collected.

  In the third step, the first coating liquid (b) was prepared in the same manner as in Example 1. In the next fourth step, 70 g of the first coating liquid (b) obtained in the third step and 80 g of ethanol are mixed with 20 g of the phosphor particles with the underlayer (A) obtained in the second step, and the mixture is mixed. After redispersion by treatment with a 48 kHz ultrasonic cleaner for 10 minutes, the mixture was stirred and mixed at 23 ° C. for 1 hour in a sealed container. Next, solid-liquid separation was performed by vacuum filtration, and the obtained phosphor particles were washed, and further 30 g of IPA was passed through, followed by vacuum filtration at a vacuum degree of 0.05 to 0.1 MPa. The obtained phosphor particles were heat-treated at 300 ° C. for 1 hour to obtain phosphor particles (B) having a first coating film.

  In the fifth step, 5 g of the phosphor particles (B) having the first coating film prepared in the fourth step are diluted with 1.5 g of dimethylsiloxane having a Si—OH group at the end (manufactured by Shin-Etsu Chemical Co., Ltd., KPN3504). 30 g of ethanol was added, and the mixture was stirred and mixed at 23 ° C. for 2 hours in a sealed container, and then solid-liquid separated by vacuum filtration. The obtained phosphor particles were dried at 110 ° C. for 1 hour and then heated and fired at 250 ° C. for 0.5 hour to form a second coating film.

  With respect to the silicate phosphor particles with the coating film (C) thus obtained, the film thickness of the coating film, the adhesion of the coating film, and the water resistance of the silicate phosphor particles are obtained by the above-described methods. Table 1 below shows the evaluation results obtained by measuring the change in light emission intensity before and after the formation of the coating film and the moisture resistance.

[Example 3]
Using commercially available Sr ₃ SiO ₅ : Eu (manufactured by Tokyo Chemical Research Laboratories, D50 = 19 μm) as the silicate phosphor particles, carrying out the first to fifth steps under the same conditions as in Example 2 above, A phosphor particle (C) with a coating film was obtained.

  About the obtained silicate phosphor particles with a coating film (C), by the above-described methods, the film thickness of the coating film, the adhesion of the coating film, and the water resistance and moisture resistance of the silicate phosphor particles, And the change of the emitted light intensity before and after coating film formation was measured, and the obtained evaluation results are shown in Table 1 below.

[Comparative Example 1]
With respect to the silicate phosphor Sr ₃ SiO ₅ : Eu (D50 = 11 μm) used in Example 1, the coating film was formed by the above-described methods without performing the first to fifth steps. The thickness, the adhesion of the coating film, and the water resistance and moisture resistance of the silicate phosphor particles were measured, and the obtained evaluation results are shown in Table 1 below.

[Comparative Example 2]
For the silicate phosphor (Sr _0.95 , Ba _0.05 ) ₃ SiO ₅ : Eu (D50 = 25 μm) used in Example 2, the first to fifth steps were not performed and The film thickness of the coating film, the adhesion of the coating film, and the water resistance and moisture resistance of the silicate phosphor particles were measured by the methods described above, and the obtained evaluation results are shown in Table 1 below.

[Comparative Example 3]
Using Sr ₃ SiO ₅ : Eu (D50 = 11 μm) used in Example 1 as silicate phosphor particles, ethyl acetoacetate aluminum diisopropylate (Kawaken Fine Chemicals), which is a component of the first coating liquid in the third step, was used. Coated silicate phosphor particles (C) were prepared in the same manner as in Example 1 except that 6 ml of ammonia water was used instead of ALCH S75P (concentration: 75% by weight).

  About the obtained silicate phosphor particles with a coating film (C), by the above-described methods, the film thickness of the coating film, the adhesion of the coating film, and the water resistance and moisture resistance of the silicate phosphor particles, And the change of the emitted light intensity before and after coating film formation was measured, and the obtained evaluation results are shown in Table 1 below.

  As can be seen from the above results, each of the double-coated coated silicate phosphor particles of Examples 1 to 3 according to the present invention has a uniform and sufficient film thickness of 160 to 250 nm. Thus, the adhesion, water resistance and moisture resistance were extremely high. Further, there was almost no change in the light emission characteristics due to the formation of the coating film, and no decrease in PL emission intensity due to the influence of moisture during the coating treatment was observed.

  On the other hand, in Comparative Examples 1 and 2, it is understood that the water resistance and moisture resistance of the silicate phosphor are very low because the coating treatment of the present invention is not performed. Moreover, since the comparative example 3 does not contain the aluminum organometallic compound required as a catalyst for adjustment of the 1st coating liquid, even if it could form a coating film, it was inferior in water resistance and moisture resistance.

Claims (6)

The manufacturing method of the silicate fluorescent substance particle with a coating film characterized by including the following 1st- 5 processes .
First step: An aluminum organometallic compound, tetraethoxysilane, and water for hydrolysis are added and mixed in an organic solvent to obtain a partially hydrolyzed aluminum organometallic compound (a).
Second step: A part of the silicate phosphor particles and the partially hydrolyzed aluminum organometallic compound (a) obtained in the first step are added and mixed in an organic solvent, vacuum filtered and dried to obtain a part. Silicate phosphor particles (A) in which the hydrolyzed aluminum organometallic compound is adsorbed as an underlayer are obtained.
Third step: A silane organometallic compound, an aluminum organometallic compound, and water for hydrolysis are added to an organic solvent and mixed by stirring to obtain a hydrolyzed condensate of the silane organometallic compound. To obtain a first coating liquid (b).
Fourth step: Underlayer-coated silicate phosphor particles (A) obtained in the second step and the first coating liquid (b) obtained in the third step were added and mixed in an organic solvent, and vacuum filtration separated. Then, the silicate fluorescent substance particle (B) provided with the 1st coating film is obtained by heat-processing at 110-350 degreeC by an atmospheric condition, and forming a 1st coating film.
Fifth step: After adding and mixing phosphor particles (B) provided with the first coating film obtained in the fourth step and dimethylsiloxane having a Si-OH group at the end in an organic solvent, and vacuum filtration separation The silicate phosphor particles (C) with a coating film are obtained by forming a second coating film by heat treatment at 250 to 300 ° C. in an air atmosphere. In the fifth step, the blending amount of dimethylsiloxane having a Si—OH group at the terminal is 0.05 to 1 times the weight of the silicate phosphor particles (B) obtained in the fourth step. The manufacturing method of the silicate fluorescent substance particle with a coating film of Claim 1 characterized by the above-mentioned. In the fifth step, the final thickness of the coating film made of the first coating film and the second coating film is characterized in that in the range of 150 to 250 nm, the coating according to claim 1 or 2 A method for producing a silicate phosphor particle with a film . The coating film according to any one of claims 1 to 3, wherein in the third step, the hydrolysis-condensation product of the silane organometallic compound has a weight average molecular weight of 5,000 to 20,000. Method for producing silicate phosphor particles. The aluminum organometallic compound in the first and third steps is ethyl acetoacetate aluminum diisopropylate, aluminum tris (ethyl acetoacetate), octyl acetoacetate aluminum diisopropylate, aluminum monoacetylacetonate bis (ethyl acetoacetate) It is an aluminum chelate compound containing the selected at least 1 sort (s) of alkyl group, The manufacturing method of the silicate fluorescent substance particle with a coating film in any one of Claims 1-4 characterized by the above-mentioned. The silicate phosphor with a coating film according to claim 1, wherein the silicate phosphor is Sr ₃ SiO ₅ : Eu or (Sr, Ba) ₃ SiO ₅ : Eu. A method for producing body particles.