CN110467913A - A kind of method for coating of big granularity LED fluorescent powder - Google Patents

Abstract

The present invention relates to a coating method for large-size LED phosphors, which comprises the following steps: (a) soaking the phosphors with acid solution, and washing the phosphors with hot water for several times after pouring out the acid solution, until the conductivity of the cleaning solution < 5mS/cm, drying to obtain the treated phosphor; (b) dissolving the first silica gel and the second silica gel in an organic solvent respectively to form the first silica gel solution and the second silica gel solution; dissolving the first silica gel and the second silica gel in a volume ratio 1: 2.8~3.2 are mixed to obtain a coating liquid; the first silica gel and the second silica gel can be co-cured, and their refractive indices are independent of each other ≥ 1.54; (c) under the condition of constant stirring, to the The treated phosphor powder is added to the coating solution, and after suction filtration, the filter residue is dried and cured. The same-sex repulsive force is generated between the phosphor and the encapsulating silica gel, which reduces the deceleration speed of the phosphor; the coating layer and the phosphor form a whole, thereby reducing the density of the entire phosphor.

Description

A kind of coating method of large particle size LED phosphor

technical field

The invention belongs to the technical field of LED phosphors, and particularly relates to a coating method for large-granularity LED phosphors.

Background technique

With the development of the LED lighting industry, the luminous efficiency and life of LED light sources have become the biggest competition point for various manufacturers. Since the invention of white LEDs at the end of the 20th century, the luminous efficiency of white LEDs has been achieved by Nichia Chemical in 2006. 100 lm/w In 2008 (just two years later), Cree Corporation of the United States achieved 157lm/w white light in the laboratory; subsequently, various LED light source manufacturers chased after each other, and the light efficiency and life of the light source became the quality of the light source important sign. So far, there are not a few manufacturers that can achieve 200lm/w in the market.

The light efficiency of the LED light source mainly depends on two factors: one is the blue light chip, and the other is the phosphor. As a powder crystal, the crystallinity and the particle size of the crystal determine the luminous brightness of the powder. The better the crystallinity, the larger the crystal particle, and the greater the luminous brightness of the phosphor. When encapsulated in the LED, the LRED light source has The light efficiency will also be higher, but the large particle size phosphors tend to settle too quickly in LED packaging applications, causing aperture problems. In particular, some luminescent phosphors with high material density, such as lutetium aluminum garnet, are used in high-power LED light sources and are essential high-quality luminescent materials for green light. How to solve the settlement problem of such materials has become an important technical difficulty in the LED phosphor industry.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a coating method for large-granularity LED phosphors in order to overcome the deficiencies of the prior art.

In order to achieve the above purpose, the technical scheme adopted in the present invention is: a coating method for large-granularity LED phosphor, which comprises the following steps:

(a) Soak the phosphor powder with acid solution, wash the phosphor powder with hot water for several times after removing the acid solution, until the conductivity of the cleaning solution is less than 5mS/cm, and then dry the phosphor powder;

(b) Dissolving the first silica gel and the second silica gel in an organic solvent respectively to form a first silica gel solution and a second silica gel solution; mixing the first silica gel and the second silica gel in a volume ratio of 1:2.8 to 3.2 to obtain a coating solution ; The first silica gel and the second silica gel can be co-cured, and their refractive indices are independently ≥1.54;

(c) Under the condition of constant stirring, add the treated phosphor powder to the coating liquid, and then dry and solidify the filter residue after suction filtration.

Optimally, in step (a), the acid solution is a hydrochloric acid solution with a mass concentration of 5-15%.

Further, in step (a), first wash the phosphor powder with hot water for several times until the conductivity of the cleaning solution is less than or equal to 10mS/cm, add ammonia solution with a concentration of 5% to neutralize it to neutrality, and then wash the phosphor powder with hot water for many times. time to solution conductivity <5mS/cm.

Preferably, in step (b), the first silica gel and the second silica gel are DOW CORNING OE-6650A and DOW CORNING OE-6650B, respectively.

Further, in step (b), the volume ratio of the first silica gel and the second silica gel is 1:3.

Optimally, in step (c), the concentration of the treated phosphor in the coating solution is ≤0.5 g/ml.

Further, in step (c), the drying temperature is 120-160°C.

Due to the application of the above technical solutions, the present invention has the following advantages compared with the prior art: the coating method of the large-size LED phosphor of the present invention is to coat the surface of the cleaned phosphor with a high refractive index first silica gel and a second Two silica gels are used for curing, which can change the surface properties (such as surface polarity and surface tension) of the phosphor powder crystals, so that the same-sex repulsive force is generated between the phosphor powder and the encapsulation silica gel, which reduces the speed of the phosphor powder; The surface of the phosphor is coated with an organic layer, so that the coating layer and the phosphor form a whole, thereby reducing the density of the entire phosphor.

Description of drawings

FIG. 1 is a schematic diagram of the use effect of the existing large-grained LED phosphor.

FIG. 2 is a schematic diagram of the use effect of the coating method of the large particle size LED phosphor of the present invention.

Detailed ways

The coating method for large-grained LED phosphors of the present invention includes the following steps: (a) soaking the phosphors with acid solution, and then washing the phosphors with hot water for several times after the acid solution is removed, until the conductivity of the cleaning solution is less than 5mS/cm , drying to obtain the treated phosphor; (b) dissolving the first silica gel and the second silica gel in an organic solvent to form the first silica gel solution and the second silica gel solution; the first silica gel and the second silica gel are in a volume ratio of 1:2.8 ~3.2 Mixing to obtain a coating liquid; the first silica gel and the second silica gel can be co-cured, and their refractive indices are independent of each other ≥1.54; (c) under the condition of constant stirring, add the coating liquid to the The treated phosphor powder is added to the medium, and after suction filtration, the filter residue is dried and cured. By coating the surface of the cleaned phosphor with the first silica gel and the second silica gel with high refractive index for curing, the surface properties (such as surface polarity and surface tension) of the phosphor powder crystal can be changed, so that the phosphor powder and the The same-sex repulsive force is generated between the silica gels used for encapsulation, which reduces the reduction speed of the phosphor; and an organic layer is coated on the surface of the phosphor, so that the coating layer and the phosphor form a whole, thereby reducing the density of the entire phosphor. The above phosphors are usually Y ₃ Al ₅ O ₁₂ : Ce, Lu ₃ Al ₅ O ₁₂ : Ce or CaAlSiN ₃ : Eu

The above coating method can not only solve the problem of sedimentation of large particle size and high density luminescent materials, but also reduce the amount of large particle size and high density phosphor materials in LED packaging (that is, the phosphor powder has good dispersion performance, and at the same time greatly reduces the amount of phosphor materials used in LED packaging. Increase the anti-settling of large particle size and high density phosphors, so as not to affect the light efficiency of the LED light source (the principle of LED light emission is that the blue light emitted by the blue crystal is divided into two parts, one part will excite the red phosphor and the green phosphor to emit red light And green light, another part of the blue light will be combined with the red light and green light emitted by the phosphor according to the principle of three primary colors, emitting white light), reducing the usage of large-grained and high-density phosphors). This is because: taking the green lutetium aluminum garnet phosphor (referred to as Gal or LuAG in the industry) as an example, as shown in Figures 1 and 2, when the phosphor does not have an anti-settling layer (ie, is not coated), the phosphor particles The sedimentation rate is very fast. Before the silica gel is completely cured, the phosphor powder settles more at the bottom. On the one hand, it will block the blue light emitted by the wafer. On the other hand, the green light emitted will be more absorbed by the red light, that is, It is said that the blue light that should excite the red phosphor to emit light is partially blocked and lost, and the red phosphor instead absorbs the light of the green phosphor (the absorption spectrum of the red phosphor is a broad spectrum containing green light), thereby increasing the amount of green phosphor. .

In step (a), the acid solution is usually a hydrochloric acid solution with a mass concentration of 5 to 15%. In step (a), first wash the phosphor powder with hot water for several times until the conductivity of the cleaning solution is ≤10mS/cm, add ammonia solution with a concentration of 5% to neutralize it to neutrality, and then wash the phosphor powder with hot water for many times to the solution. Conductivity <5mS/cm. In step (b), the first silica gel and the second silica gel are preferably DOW CORNING OE-6650A and DOW CORNING OE-6650B respectively; the volume ratio of the first silica gel and the second silica gel is preferably 1. :3. In step (c), the concentration of the treated phosphor in the coating solution is ≤0.5 g/ml. In step (c), the drying temperature is 120-160°C.

The preferred embodiments of the present invention will be described in detail below in conjunction with:

Example 1

The present embodiment provides a coating method for large-granularity LED phosphors, which includes the following steps:

(a) Surface cleaning of phosphors: soak the phosphors (Y ₃ Al ₅ O ₁₂ : Ce phosphors with a particle size D50 of 18 μm) with a hydrochloric acid solution with a mass concentration of 10% for half an hour, stir for another half an hour, and let stand for a while. After the phosphor powder is completely precipitated, pour off the hydrochloric acid solution; wash with hot water at 80~100°C for several times until the conductivity of the solution is less than 10mS/cm; add a small amount of 5% ammonia solution to neutralize to neutrality, and test the pH =7; continue to wash with hot water at 80~100°C for several times until the conductivity of the solution is less than 5mS/cm; after precipitation, bake in an oven at 120°C for 3 hours to treat the phosphor;

(b) Mixing of coating liquid (ie coating liquid): the selected coating material is high refractive index AB silica gel, DOW CORNINGOE-6650A (first silica gel) and DOW CORNING OE-6650B (second silica gel); 1ml of the first silica gel was added with 500ml of ethanol to form the first silica gel solution, and 1ml of the second silica gel was added to 500ml of ethanol to form the second silica gel solution. The above two silica gel solutions were placed in a beaker in a volume ratio of 1:3 for mixing, and half of the solution was stirred. hour to get coating solution;

(c) Add 50g of treated phosphor powder to 100ml of coating solution (note that the phosphor powder is slowly dispersed into the coating solution), stir for half an hour; after suction filtration, dry the filter residue (ie phosphor powder) at 150°C for 3 hours ( To promote the curing of AB silica gel) can be.

Encapsulate the above-mentioned coated phosphor and uncoated phosphor, and under the condition of the same LED light efficiency, the usage amount of the coated phosphor (relative to the usage amount of the uncoated phosphor) is reduced The percentage is 4%.

Example 2

This embodiment provides a coating method for large-size LED phosphors, which is basically the same as that in Embodiment 1, except that in step (a), the particle size D50 of the phosphor used is 23 μm, and the final coated The percentage reduction in phosphor usage is 5%.

Example 3

This embodiment provides a coating method for large-size LED phosphors, which is basically the same as that in Embodiment 1, except that in step (a), the particle size D50 of the phosphor used is 30 μm, and the final coated The percentage reduction in phosphor usage is 6%.

Example 4

This embodiment provides a method for coating a large-size LED phosphor, which is basically the same as that in Embodiment 1, except that in step (a), the phosphor used is Lu ₃ Al ₅ O ₁₂ : Ce, The percentage of reduction in the amount of phosphor powder used after the final coating is 3%.

Example 5

This embodiment provides a coating method for large-size LED phosphor, which is basically the same as that in Embodiment 4, except that in step (a), the particle size D50 of the phosphor used is 20 μm, and the final coated The percentage reduction in phosphor usage is 5%.

Example 6

This embodiment provides a coating method for large-size LED phosphors, which is basically the same as that in Embodiment 4, except that in step (a), the particle size D50 of the phosphor powder used is 25 μm, and the final coated The percentage reduction in phosphor usage is 6%.

Example 7

This embodiment provides a coating method for large-size LED phosphors, which is basically the same as that in Embodiment 1, except that in step (a), the phosphor used is CaAlSiN ₃ : Eu, and after the final coating The percentage of phosphor usage reduction is 2.5%.

Example 8

This embodiment provides a coating method for large-size LED phosphor, which is basically the same as that in Embodiment 7, except that in step (a), the particle size D50 of the phosphor used is 22 μm, and the final coated The percentage reduction in phosphor usage is 4%.

Example 9

This embodiment provides a coating method for large-size LED phosphors, which is basically the same as that in Embodiment 7, except that in step (a), the particle size D50 of the phosphor used is 26 μm, and the final coated The percentage reduction in phosphor usage is 5%.

Example 10

This embodiment provides a coating method for large-size LED phosphors, which is basically the same as that in Embodiment 1, except that: in step (c), only 10g of treated phosphors are added to 100ml of coating solution; The percentage of reduction in the usage of the coated phosphor is 3.5%.

Example 11

This embodiment provides a coating method for large-size LED phosphors, which is basically the same as that in Embodiment 1, except that in step (b), two kinds of silica gel solutions are taken in a volume ratio of 1:2.8; The percentage of reduction in the usage of the coated phosphor is 3.9%.

Example 12

This embodiment provides a coating method for large-size LED phosphors, which is basically the same as that in Embodiment 1, except that in step (b), two kinds of silica gel solutions are taken in a volume ratio of 1:3.2; The percentage of reduction in the usage of the coated phosphor is 4.1%.

Example 13

This embodiment provides a coating method for large-size LED phosphors, which is basically the same as that in Embodiment 1, except that in step (b), 2ml of the first silica gel and 500ml of ethanol are added to form the second silica gel respectively. Corresponding to the silica gel solution, the percentage of reduction in the amount of phosphor powder used after the final coating is 4.2%.

Example 14

This embodiment provides a coating method for large-sized LED phosphors, which is basically the same as that in Embodiment 1, except that: in step (b), 3 ml of the first silica gel and 500 ml of the second silica gel are added to 500 ml of ethanol respectively to form Corresponding to the silica gel solution, the percentage of reduction in the amount of phosphor powder used after the final coating is 4.5%.

Comparative Example 1

This example provides a coating method for large-size LED phosphors, which is basically the same as that in Example 1, except that step (a) is not performed, and the percentage of the final coating phosphor usage reduction is: 1%.

Comparative Example 2

This example provides a coating method for large-size LED phosphors, which is basically the same as that in Example 1, except that step (a) is not carried out, the aqueous ammonia solution is not added to neutrality, and the conductivity of the solution is not adjusted. <5mS/cm, the percentage of phosphor powder usage reduction after final coating is 1.5%.

Comparative Example 3

This example provides a coating method for large particle size LED phosphors, which is basically the same as that in Example 1, except that in step (c), the phosphor powder is treated in excess, reaching 60 g, and the final coated phosphor powder The percentage reduction in usage is 2.0%.

The above-mentioned embodiments are only to illustrate the technical concept and characteristics of the present invention, and their purpose is to enable those who are familiar with the art to understand the content of the present invention and implement them accordingly, and cannot limit the scope of protection of the present invention with this. Equivalent changes or modifications made in the spirit and spirit should all be included within the protection scope of the present invention.

Claims (7)

1. a coating method of large-granularity LED phosphor, is characterized in that, it comprises the following steps: (a) Soak the phosphor powder with acid solution, wash the phosphor powder with hot water for several times after removing the acid solution, until the conductivity of the cleaning solution is less than 5mS/cm, and then dry the phosphor powder; (b) Dissolving the first silica gel and the second silica gel in an organic solvent respectively to form a first silica gel solution and a second silica gel solution; mixing the first silica gel and the second silica gel in a volume ratio of 1:2.8 to 3.2 to obtain a coating solution ; The first silica gel and the second silica gel can be co-cured, and their refractive indices are independently ≥1.54; (c) Under the condition of constant stirring, add the treated phosphor powder to the coating liquid, and then dry and solidify the filter residue after suction filtration. 2 . The method for coating large-sized LED phosphors according to claim 1 , wherein in step (a), the acid solution is a hydrochloric acid solution with a mass concentration of 5-15%. 3 . 3. The method for coating large-sized LED phosphors according to claim 1 or 2, wherein in step (a), first wash the phosphors with hot water for several times until the conductivity of the cleaning solution is ≤10mS/cm, and add Neutralize the ammonia solution with a concentration of 5% to neutrality, and then wash the phosphor with hot water for several times until the conductivity of the solution is less than 5mS/cm. 4 . The method for coating large-size LED phosphors according to claim 1 , wherein in step (b), the first silica gel and the second silica gel are DOW CORNING OE-6650A and DOW CORNING OE respectively. 5 . -6650B. 5 . The method for coating large-sized LED phosphors according to claim 4 , wherein in step (b), the volume ratio of the first silica gel and the second silica gel is 1:3. 6 . 6 . The method for coating large-sized LED phosphors according to claim 1 , wherein in step (c), the concentration of the treated phosphors in the coating solution is ≤0.5 g/ml. 7 . 7 . The method for coating large-size LED phosphors according to claim 1 or 6 , wherein in step (c), the drying temperature is 120-160° C. 8 .