Film coating method of silicate fluorescent powder

Abstract

The invention belongs to the technical field of fluorescent powder, and particularly relates to a coating method of silicate fluorescent powder. Comprising the following steps: (1) stirring and mixing silicate fluorescent powder, methyl silicone oil and a diol solvent I in proportion, pouring out supernatant after the mixture is settled, drying and sieving to obtain first powder; (2) adding the first powder into a diol solvent II, dropwise adding one or more of octyltrimethoxysilane, dodecyltrimethoxysilane, hexadecyltrimethoxysilane and 3-epoxypropyltrimethoxysilane for several times under a stirring condition, continuously stirring for 1-3 hours after dropwise adding is finished, and pouring away supernatant liquid after sedimentation, so as to obtain first powder; and drying and sieving. According to the coating method, a layer of transparent hydrophobic oil film can be formed on the surface of the fluorescent powder, so that the luminous decay of the fluorescent powder is reduced under the condition that the luminous efficiency of the silicate fluorescent powder is maintained.

Description

Technical Field

[0001] The invention belongs to the technical field of fluorescent powders and relates to a coating method, in particular to a coating method for silicate fluorescent powders. Background Art

[0002] With the rapid development of LED technology, silicate phosphors have attracted extensive attention due to their excellent fluorescence properties. Silicate phosphors have the advantages of high fluorescence intensity, long afterglow time and no radioactivity, which makes them show good application prospects in the fields of lighting and display. However, despite their superior performance, silicate phosphors still face many challenges in practical applications.

[0003] First, the poor dispersibility of silicate phosphors results in uneven bonding between the phosphors and the matrix material when preparing LED devices, which affects the luminous efficiency and stability of the LED. In addition, silicate phosphors have poor water resistance and are prone to performance degradation in humid environments, which in turn affects the service life and reliability of LEDs. Summary of the invention

[0004] In view of the above shortcomings of the prior art, the present invention aims to provide a coating method for silicate phosphors.

[0005] To achieve the above objectives, the technical solutions adopted are:

[0006] A method for coating silicate phosphors comprises the following steps:

[0007] (1) mixing silicate phosphor, methyl silicone oil and glycol solvent in a certain proportion, discarding the upper clear liquid after settling, drying and sieving to obtain a first powder;

[0008] (2) Add the first powder to the diol solvent 2, and add one or more of octyltrimethoxysilane (OTMS), dodecyltrimethoxysilane (DTMS), hexadecyltrimethoxysilane (HDTMS), and 3-epoxypropyltrimethoxysilane (GPTMS) dropwise in multiple times under stirring conditions. After the addition is completed, continue stirring for 1-3 hours, pour off the supernatant after sedimentation, and sieve after drying.

[0009] Preferably, the chemical formula of the silicate phosphor is (BaSrCa) 1.9 SiO4:0.1Eu 2+ .

[0010] Preferably, in step (1), the mixing ratio of the silicate phosphor, methyl silicone oil and glycol solvent 1 is (400-500) g: (4-6) ml: (1200-1500) ml.

[0011] Preferably, the diol solvent one or the diol solvent two is at least one of diols having a carbon number greater than or equal to 2 and less than 20, more preferably butanediol.

[0012] More preferably, in step (1), the stirring time is 0.5-1.5 hours.

[0013] Preferably, in step (1), the mixture is baked in a muffle furnace at 200-300° C. for 15-20 hours, and then passed through a 200-mesh vibrating sieve to obtain the first powder.

[0014] Preferably, in step (2), the mixing ratio of the first powder, at least one of octyltrimethoxysilane (OTMS), dodecyltrimethoxysilane (DTMS), hexadecyltrimethoxysilane (HDTMS), 3-epoxypropyltrimethoxysilane (GPTMS), and the diol solvent 2 is (400-500) g: (20-50) ml: (1500-3000) ml.

[0015] Preferably, in step (2), the mixture is baked at 150° C. for 15-20 hours and then passed through a 200-mesh vibrating sieve.

[0016] Compared with the prior art, the beneficial effect of the present invention is that: the present invention provides a method for coating silicate phosphors, which can form a transparent hydrophobic oil film on the surface of the phosphors, and this oil film can improve the dispersibility and water resistance of the silicate phosphors, so that the silicate phosphors can reduce the light decay of the phosphors while maintaining the luminous efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the SEM spectrum of the silicate phosphor before coating in Example 5;

[0018] Figure 2 This is the SEM spectrum of the silicate phosphor after coating in Example 5. DETAILED DESCRIPTION

[0019] The present invention is described below in conjunction with examples, which are only used to explain the present invention and are not used to limit the scope of the present invention.

[0020] Example 1

[0021] (1) 450 g silicate phosphor (chemical formula of silicate phosphor is (BaSrCa) 1.9 SiO4:0.1Eu 2+ ), 5 ml of methyl silicone oil and 1300 ml of butanediol were added into a beaker, stirred and mixed for 1 hour, allowed to settle, the supernatant was discarded, and the mixture was dried in a muffle furnace at 250° C. for 18 hours. After drying, the mixture was passed through a 200-mesh vibrating sieve to obtain the first powder.

[0022] (2) 450 g of the first powder was added to 1500 ml of butanediol, and 35 ml of octyltrimethoxysilane (OTMS) was added dropwise under stirring. After the addition was completed, stirring was continued for 2 hours, and the mixture was allowed to settle. The supernatant was discarded and dried at 150° C. for 18 hours. After drying, the mixture was passed through a 200-mesh vibrating sieve.

[0023] Example 2

[0024] (1) 450 g silicate phosphor (chemical formula of silicate phosphor is (BaSrCa) 1.9 SiO4:0.1Eu 2+ ), 5 ml of methyl silicone oil and 1300 ml of butanediol were added into a beaker, stirred and mixed for 1 hour, allowed to settle, the supernatant was discarded, and the mixture was dried in a muffle furnace at 250° C. for 18 hours. After drying, the mixture was passed through a 200-mesh vibrating sieve to obtain the first powder.

[0025] (2) 450 g of the first powder was added to 1500 ml of butanediol, and 35 ml of dodecyltrimethoxysilane (DTMS) was added dropwise under stirring. After the addition was completed, stirring was continued for 2 hours, and the mixture was allowed to settle. The supernatant was discarded and dried at 150° C. for 18 hours. After drying, the mixture was passed through a 200-mesh vibrating sieve.

[0026] Example 3

[0027] (1) 450 g silicate phosphor (chemical formula of silicate phosphor is (BaSrCa) 1.9 SiO4:0.1Eu 2+ ), 5 ml of methyl silicone oil and 1300 ml of butanediol were added into a beaker, stirred and mixed for 1 hour, allowed to settle, the supernatant was discarded, and the mixture was dried in a muffle furnace at 250° C. for 18 hours. After drying, the mixture was passed through a 200-mesh vibrating sieve to obtain the first powder.

[0028] (2) 450 g of the first powder was added to 1500 ml of butanediol, and 35 ml of hexadecyltrimethoxysilane (HDTMS) was added dropwise under stirring. After the addition was completed, stirring was continued for 2 hours, and the mixture was allowed to settle. The supernatant was discarded and dried at 150° C. for 18 hours. After drying, the mixture was passed through a 200-mesh vibrating sieve.

[0029] Example 4

[0030] (1) 450 g silicate phosphor (chemical formula of silicate phosphor is (BaSrCa) 1.9 SiO4:0.1Eu 2+ ), 5 ml of methyl silicone oil and 1300 ml of butanediol were added into a beaker, stirred and mixed for 1 hour, allowed to settle, the supernatant was discarded, and the mixture was dried in a muffle furnace at 250° C. for 18 hours. After drying, the mixture was passed through a 200-mesh vibrating sieve to obtain the first powder.

[0031] (2) 450 g of the first powder was added to 1500 ml of butanediol, and 35 ml of 3-epoxypropyltrimethoxysilane (GPTMS) was added dropwise under stirring. After the addition was completed, stirring was continued for 2 hours, and the mixture was allowed to settle. The supernatant was discarded and dried at 150° C. for 18 hours. After drying, the mixture was passed through a 200-mesh vibrating sieve.

[0032] Example 5

[0033] (1) 450 g silicate phosphor (chemical formula of silicate phosphor is (BaSrCa) 1.9 SiO4:0.1Eu 2+ ), 5 ml of methyl silicone oil and 1300 ml of butanediol were added into a beaker, stirred and mixed for 1 hour, allowed to settle, the supernatant was discarded, and the mixture was dried in a muffle furnace at 250° C. for 18 hours. After drying, the mixture was passed through a 200-mesh vibrating sieve to obtain the first powder.

[0034] (2) Add 450 g of the first powder to 1500 ml of butanediol, and dropwise add 8 ml of OTMS, 9 ml of DTMS, 9 ml of HDTMS and 9 ml of GPTMS mixed solution under stirring. After the addition is completed, continue stirring for 2 hours, allow to settle, pour off the supernatant, and bake at 150°C for 18 hours. After drying, pass through a 200-mesh vibrating sieve.

[0035] Comparative Example 1

[0036] 450g silicate phosphor (chemical formula of silicate phosphor is (BaSrCa) 1.9 SiO4:0.1Eu 2+ ), 5 ml of methyl silicone oil and 1300 ml of butanediol were added into a beaker, stirred and mixed for 1 hour, allowed to settle, the supernatant was discarded, and the mixture was dried in a muffle furnace at 250°C for 18 hours. After drying, the mixture was passed through a 200-mesh vibrating sieve.

[0037] Comparative Example 2

[0038] 450g silicate phosphor (chemical formula of silicate phosphor is (BaSrCa) 1.9 SiO4:0.1Eu 2+ ) was added to 1500 ml of butanediol, and a mixed solution of 8 ml of OTMS, 9 ml of DTMS, 9 ml of HDTMS and 9 ml of GPTMS was added dropwise under stirring. After the addition was completed, stirring was continued for 2 hours, and the mixture was allowed to settle. The supernatant was discarded and dried at 150°C for 18 hours. After drying, the mixture was passed through a 200-mesh vibrating sieve.

[0039] test

[0040] The silicate phosphor before coating and the silicate phosphor after coating in Example 5 were analyzed by SEM spectra. Figure 1 and 2As shown, after the product is magnified 500 times and observed, there is a transparent film on the surface of the coated silicate phosphor product.

[0041] The coated silicate phosphors of Examples 1-5, the phosphors of Comparative Examples 1-2 and the uncoated phosphors were tested for luminescence performance and aging performance. The test results are shown in Tables 1 and 2.

[0042] Table 1. Luminescence properties of Examples 1-5, Comparative Examples 1-2 and uncoated phosphors

[0043]

[0044] Table 2. Aging performance test data of coated silicate phosphors and uncoated phosphors in Examples 1-5

[0045]

[0046] As can be seen from Table 1, the brightness of the coated samples of Examples 1-5 and the brightness of the coated samples of Comparative Examples 1-2 are basically equivalent to the brightness of the uncoated silicate phosphor. It can be seen that this coating method does not affect the luminous intensity of the silicate phosphor. As can be seen from Table 2, after the coated samples of Examples 1-5, the coated samples of Comparative Examples 1-2 and the uncoated samples were subjected to 1000h aging test, the luminous performance attenuation rate of the coated samples of Examples 1-5 was lower than that of the Comparative Examples 1-2 and the uncoated samples, and the coated samples had better aging resistance. This proves that only when methyl silicone oil and silane coupling agent are coated at the same time can the anti-aging performance of the phosphor be better improved.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for coating silicate phosphors, characterized in that: The following steps are involved: (1) mixing silicate phosphor, methyl silicone oil and glycol solvent in a certain proportion, discarding the upper clear liquid after settling, drying and sieving to obtain a first powder; (2) Add the first powder to the diol solvent 2, and add one or more of octyltrimethoxysilane, dodecyltrimethoxysilane, hexadecyltrimethoxysilane, and 3-epoxypropyltrimethoxysilane dropwise under stirring. After the addition is completed, continue stirring for 1-3 hours. After sedimentation, pour off the supernatant, dry and sieve.

2. The coating method of silicate phosphor according to claim 1, characterized in that: The chemical formula of the silicate phosphor is (BaSrCa) 1.9 SiO4:0.1Eu 2+ .

3. The coating method of silicate phosphor according to claim 1 or 2, characterized in that: In step (1), the mixing ratio of the silicate phosphor, methyl silicone oil and glycol solvent 1 is (400-500) g: (4-6) ml: (1200-1500) ml.

4. The coating method of silicate phosphor according to claim 3, characterized in that: The diol solvent 1 or the diol solvent 2 is at least one of diols having carbon atoms greater than or equal to 2 and less than 20.

5. The coating method of silicate phosphor according to claim 1, characterized in that: In step (1), the stirring time is 0.5-1.5 hours.

6. The coating method of silicate phosphor according to claim 1, characterized in that: In step (1), the powder is dried in a muffle furnace at 200-300° C. for 15-20 hours, and then passed through a 200-mesh vibration sieve to obtain a first powder.

7. The coating method of silicate phosphor according to claim 1 or 2, characterized in that: In step (2), the mixing ratio of the first powder, at least one of octyltrimethoxysilane, dodecyltrimethoxysilane, hexadecyltrimethoxysilane, 3-epoxypropyltrimethoxysilane, and the diol solvent 2 is (400-500) g: (20-50) ml: (1500-3000) ml.

8. The coating method of silicate phosphor according to claim 7, characterized in that: In step (2), the mixture is dried at 150° C. for 15-20 hours and then passed through a 200-mesh vibrating sieve.

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