Inorganic block luminescent material and preparation method thereof

Abstract

The invention discloses an inorganic block luminescent material and a preparation method thereof, and relates to the technical field of light sources for illumination and display. The material comprises an inorganic matrix, fluorescent powder dispersed inside and a substrate at the bottom. The preparation method comprises the following steps: firstly, mixing an inorganic silica gel solution and a curing agent solution; adding fluorescent powder into the mixed solution, and stirring; dropwise adding the mixed solution to the center of a substrate, and placing the substrate on a rotary table for rotation; then a hot-air blower is adopted for heating, and preliminary shaping of the block luminescent material is achieved; and putting the mixture into a muffle furnace for heating, and carrying out heat preservation to finally obtain the inorganic block luminescent material. The inorganic silica gel packaged block luminescent material is prepared by innovatively adopting a secondary process of preforming and firing, and the inorganic silica gel packaged block luminescent material has higher luminescent efficiency, better luminescent stability and simple preparation process, and is suitable for industrialization.

Description

Technical Field

[0001] The invention relates to the technical field of light sources for lighting and display, and in particular to an inorganic bulk luminescent material and a preparation method thereof. Background Art

[0002] Fluorescent conversion materials are the core light-emitting components of semiconductor lighting (including LED lighting and laser lighting). Among them, organic silica gel encapsulated phosphors are difficult to achieve high-power applications due to their low thermal conductivity. Therefore, some new packaging forms are needed, such as glass, ceramics, single crystal and other bulk materials. However, the preparation process of the above bulk luminescent materials is relatively complicated and difficult to achieve industrialization. It is necessary to find new phosphor packaging forms.

[0003] Inorganic silica gel, whose main component is silicon dioxide, has significantly better water resistance and heat resistance than organic coatings. This inorganic silica gel coating is dense and hard, does not generate static electricity, and various dust in the air is difficult to adhere. Compared with the thermal conductivity of organic silica gel of 0.5W / m·K, the thermal conductivity of inorganic silica gel is about 1.4W / m·K, and the heat dissipation performance is improved by more than 3 times, which can better conduct heat and ensure the stable operation of the phosphor. Another point is that the refractive index of inorganic silica gel is 1.43~1.45, which is relatively matched with the refractive index of 1.7 of phosphor, and can achieve higher quantum efficiency than bulk materials such as glass. In addition, the firing temperature of inorganic silica gel is relatively low, and the preparation process is simpler and more efficient than other inorganic bulk luminescent materials.

[0004] Therefore, it is crucial to prepare inorganic silica gel-encapsulated bulk luminescent materials with stable luminescent properties and uniform distribution of phosphors. Summary of the invention

[0005] In view of this, the present invention discloses an inorganic bulk luminescent material and a preparation method thereof to meet the demand of semiconductor lighting for fluorescent conversion materials with high light color quality and low manufacturing cost.

[0006] An inorganic bulk luminescent material includes an inorganic matrix, phosphors dispersed inside, and a substrate at the bottom. The preparation method includes the following steps:

[0007] Step 1: Mixing the inorganic silica gel solution and the curing agent solution;

[0008] Step 2: Add the phosphor to the mixed solution obtained in step 1 and stir;

[0009] Step 3: Drop the mixed solution obtained in step 2 on the center of the substrate, and then place it on a rotating table for rotation;

[0010] Step 4: Use a hot air blower to heat and achieve preliminary shaping of the block luminescent material;

[0011] Step 5: Place the bulk luminescent material obtained in step 4 into a muffle furnace for heating and heat preservation to finally obtain an inorganic bulk luminescent material.

[0012] Preferably, in step 1, the inorganic silica gel solution is an anhydrous silica solution, and the silica content is 20-30wt%; the curing agent solvent is a lithium silicate aqueous solution, and the lithium silicate content is 1.5-3.0wt%; the mass ratio of the inorganic silica gel solution to the curing agent solution is: 1:1-1:1.2.

[0013] Preferably, in step 2, the phosphor is Ce-doped YAG yellow powder or LuAG green powder, and the amount of the phosphor added is 3.0-6.0 wt % of the amount of the inorganic silica gel solution and the curing agent solution added.

[0014] Preferably, in step 2, the stirring rate is 60-70 r / min and the stirring time is 30 min.

[0015] Preferably, in step 3, the amount of the mixed solution added is 1-4 mL; the substrate is an aluminum substrate with a size of φ30-60 mm.

[0016] Preferably, in step 3, the rotation speed of the rotating table is 60-70 r / min, and the rotation time is 30 min.

[0017] Preferably, in step 4, the heating temperature of the hot air blower is 120-150° C., and the heating time is 2 minutes.

[0018] Preferably, in step 5, the heating temperature of the muffle furnace is 180-200° C., and the insulation time is 10 min.

[0019] Preferably, the quantum efficiency of the inorganic bulk luminescent material is 95-98% of that of the phosphor, and the light decay at 150° C. is 0.9-8.1%.

[0020] Compared with the prior art, the inorganic bulk luminescent material and the preparation method thereof disclosed in the present invention have the following advantages:

[0021] (1) The preparation method of the present invention is simple and controllable, and innovatively adopts a secondary process of preforming and firing to prepare a bulk luminescent material encapsulated by inorganic silica gel, which significantly improves the quantum efficiency of the luminescent material.

[0022] (2) Compared with the existing silica gel encapsulated phosphor, the thermal conductivity is increased by nearly 3 times, so the luminous performance is better. Generally, the light decay at 150°C is about 15%, while the temperature-induced luminous decay of the present invention is lower, reaching 8% (YAG) and LuAG reaching 0.9%.

[0023] (3) The preparation process provided by the present invention has a simple process and is suitable for industrialization. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of a method for preparing an inorganic bulk luminescent material disclosed in the present invention.

[0025] Figure 2 The temperature-dependent fluorescence spectra of Example 1, Example 2 and Comparative Example 1 of the present invention are shown. DETAILED DESCRIPTION

[0026] The raw materials and reagents used in the following examples are all commercially available products. The phosphor is commercial Ce:YAG or Ce:LuAG, wherein the doping concentration of Ce is 0.5-1.0 mol.%.

[0027] Example 1

[0028] An inorganic bulk luminescent material comprises an inorganic matrix, phosphors dispersed inside, and a substrate at the bottom.

[0029] like Figure 1 As shown, the preparation method includes the following steps.

[0030] Step 1: solution mixing, that is, mixing an inorganic silica gel solution and a curing agent solution. The inorganic silica gel solution is an anhydrous silica solution with a silica content of 20wt%; the curing agent solvent is a lithium silicate solution with a lithium silicate content of 1.5wt%; the mass ratio of the inorganic silica gel solution to the curing agent solution is 1:1;

[0031] Step 2: Mixing and stirring, that is, adding phosphor to the mixed solution obtained in step 1 and stirring. The phosphor is Ce-doped LuAG green powder, and the amount of phosphor added is 6.0wt% of the amount of inorganic silica gel solution and curing agent solution added; the stirring rate is 60r / min, and the stirring time is 30min;

[0032] Step 3: coating, that is, drop the mixed solution obtained in step 2 on the center of the substrate, and then place it on a rotating table for rotation. The amount of mixed solution added is 4 mL; the substrate is an aluminum substrate with a size of φ60 mm; the rotating table speed is 60 r / min, and the rotation time is 30 min;

[0033] Step 4: pre-forming by heating, that is, using a hot air blower to heat the block luminescent material to achieve preliminary shaping. The heating temperature of the hot air blower is 150°C and the heating time is 2 minutes.

[0034] Step 5: Firing, that is, placing the bulk luminescent material obtained in step 5 into a muffle furnace for heating and heat preservation, the heating temperature is 200° C., and the heat preservation time is 10 minutes, and finally an inorganic bulk luminescent material is obtained.

[0035] like Figure 2 As shown, the above inorganic bulk luminescent material was placed in a quantum efficiency test system for testing, and its quantum efficiency retained 98% of the original powder; the above inorganic bulk luminescent material was placed in a fluorescence spectrometer for testing. Compared with the luminescence intensity at 25°C, the material can still maintain 99.1% at 150°C, and the luminescence attenuation is 0.9%, with high luminescence efficiency and stable luminescence performance.

[0036] Example 2

[0037] An inorganic bulk luminescent material comprises an inorganic matrix, phosphors dispersed inside, and a substrate at the bottom.

[0038] like Figure 1 As shown, the preparation method includes the following steps.

[0039] Step 1: solution mixing, that is, mixing an inorganic silica gel solution and a curing agent solution. The inorganic silica gel solution is an anhydrous silica solution with a silica content of 30wt%; the curing agent solvent is a lithium silicate solution with a lithium silicate content of 3.0wt%; the mass ratio of the inorganic silica gel solution to the curing agent solution is 1:1.2;

[0040] Step 2: Mixing and stirring, that is, adding phosphor to the mixed solution obtained in step 1 and stirring. The phosphor is Ce-doped YAG yellow powder, and the amount of phosphor added is 3.0wt% of the amount of inorganic silica gel solution and curing agent solution added; the stirring rate is 70r / min, and the stirring time is 30min;

[0041] Step 3: coating, that is, drop the mixed solution obtained in step 2 on the center of the substrate, and then put it on a rotating table for rotation. The amount of mixed solution added is 1mL; the substrate is an aluminum substrate with a size of φ30mm; the rotating table speed is 70r / min, and the rotation time is 30min;

[0042] Step 4: Pre-molding by heating, that is, using a hot air blower to heat and achieve the initial shaping of the block luminescent material. The heating temperature of the hot air blower is 120°C and the heating time is 2 minutes;

[0043] Step 5: Firing, that is, placing the bulk luminescent material obtained in step 5 into a muffle furnace for heating and heat preservation, the heating temperature is 180° C., and the heat preservation time is 10 minutes, so as to finally obtain the inorganic bulk luminescent material.

[0044] like Figure 2As shown, the above inorganic bulk luminescent material was placed in a quantum efficiency test system for testing, and its quantum efficiency retained 95% of the original powder; the above inorganic bulk luminescent material was placed in a fluorescence spectrometer for testing. Compared with the luminescence intensity at 25°C, the material can still maintain 91.9% at 150°C, and the luminescence attenuation is 8.1%, with high luminescence efficiency and stable luminescence performance.

[0045] Comparative Example 1

[0046] An inorganic bulk luminescent material comprises an inorganic matrix, phosphors dispersed inside, and a substrate at the bottom.

[0047] like Figure 1 As shown, the preparation method includes the following steps.

[0048] Step 1: solution mixing, that is, mixing an inorganic silica gel solution and a curing agent solution. The inorganic silica gel solution is an anhydrous silica solution with a silica content of 30wt.%; the curing agent solvent is a lithium silicate solution with a lithium silicate content of 3.0wt%; the mass ratio of the inorganic silica gel solution to the curing agent solution is 1:1.2;

[0049] Step 2: Mixing and stirring, that is, adding phosphor to the mixed solution obtained in step 1 and stirring. The phosphor is Ce-doped YAG yellow powder, and the amount of phosphor added is 3.0wt% of the amount of inorganic silica gel solution and curing agent solution added; the stirring rate is 70r / min, and the stirring time is 30min;

[0050] Step 3: coating, that is, drop the mixed solution obtained in step 2 on the center of the substrate, and then put it on a rotating table for rotation. The amount of mixed solution added is 1mL; the substrate is an aluminum substrate with a size of φ30mm; the rotating table speed is 70r / min, and the rotation time is 30min;

[0051] Step 4: Pre-molding by heating, that is, using a hot air blower to heat and achieve the initial shaping of the block luminescent material. The heating temperature of the hot air blower is 120°C and the heating time is 2 minutes;

[0052] Step 5: Firing, that is, placing the bulk luminescent material obtained in step 5 into a muffle furnace for heating and heat preservation, the heating temperature is 200° C., and the heat preservation time is 10 minutes, and finally an inorganic bulk luminescent material is obtained.

[0053] like Figure 2As shown, the above inorganic bulk luminescent material was put into the quantum efficiency test system for testing, and its quantum efficiency retained 81.3% of the original powder; the above inorganic bulk luminescent material was put into the fluorescence spectrometer for testing, and compared with the luminescence intensity at 25°C, the material was only 85.5% at 150°C, and the luminescence attenuation was 14.5%. This is mainly due to the high secondary sintering temperature, which destroyed the bonding characteristics between the inorganic encapsulation material and the luminescent particles, and the poor heat dissipation performance. This leads to low efficiency of the luminescent material and unstable luminescence performance.

[0054] Comparative Example 2

[0055] An inorganic bulk luminescent material comprises an inorganic matrix, phosphors dispersed inside, and a substrate at the bottom.

[0056] like Figure 1 As shown, the preparation method includes the following steps.

[0057] Step 1: solution mixing, that is, mixing an inorganic silica gel solution and a curing agent solution. The inorganic silica gel solution is an anhydrous silica solution with a silica content of 20wt%; the curing agent solvent is a lithium silicate solution with a lithium silicate content of 1.5wt%; the mass ratio of the inorganic silica gel solution to the curing agent solution is 1:1;

[0058] Step 2: Mixing and stirring, that is, adding phosphor to the mixed solution obtained in step 1 and stirring. The phosphor is Ce-doped LuAG green powder, and the amount of phosphor added is 6.0wt% of the amount of inorganic silica gel solution and curing agent solution added; the stirring rate is 60r / min, and the stirring time is 30min;

[0059] Step 3: coating, that is, drop the mixed solution obtained in step 2 on the center of the substrate, and then put it on a rotating table for rotation. The amount of mixed solution added is 4mL; the substrate is an aluminum substrate with a size of φ60mm; the rotating table speed is 80r / min, and the rotation time is 30min;

[0060] Step 4: Pre-molding by heating, that is, using a hot air blower to heat and achieve the initial shaping of the block luminescent material. The heating temperature of the hot air blower is 110°C and the heating time is 2 minutes;

[0061] Step 5: Firing, that is, placing the bulk luminescent material obtained in step 5 into a muffle furnace for heating and heat preservation, the heating temperature is 200° C., and the heat preservation time is 10 minutes, and finally an inorganic bulk luminescent material is obtained.

[0062] The surface of the inorganic bulk luminescent material cracked. On the one hand, the rotation speed of the rotating table was too fast during the preforming stage, which caused uneven distribution of the phosphor and resulted in defects after sintering. In addition, the temperature of the hot air blower was not high enough to achieve the preforming of the bulk material, resulting in the final product being broken after sintering.

[0063] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A method for preparing an inorganic bulk luminescent material, characterized in that: It includes the following steps: Step 1: Mixing the inorganic silica gel solution and the curing agent solution; Step 2: Add the phosphor to the mixed solution obtained in step 1 and stir; Step 3: Drop the mixed solution obtained in step 2 on the center of the substrate, and then place it on a rotating table for rotation; Step 4: Use a hot air blower to heat and achieve preliminary shaping of the block luminescent material; Step 5: Place the bulk luminescent material obtained in step 4 into a muffle furnace for heating and heat preservation to finally obtain an inorganic bulk luminescent material.

2. The method for preparing an inorganic bulk luminescent material according to claim 1, characterized in that: In step 1, the inorganic silica gel solution is an anhydrous silica solution, and the content of silica is 20-30wt%; the curing agent solvent is a lithium silicate aqueous solution, and the content of lithium silicate is 1.5-3.0wt%; the mass ratio of the inorganic silica gel solution to the curing agent solution is: 1:1-1:1.

2.

3. The method for preparing an inorganic bulk luminescent material according to claim 1, characterized in that: In step 2, the phosphor is Ce-doped YAG yellow powder or LuAG green powder, and the amount of the phosphor added is 3.0-6.0 wt % of the amount of the inorganic silica gel solution and the curing agent solution added.

4. The method for preparing an inorganic bulk luminescent material according to claim 1, characterized in that: In step 2, the stirring rate is 60-70 r / min and the stirring time is 30 min.

5. The method for preparing an inorganic bulk luminescent material according to claim 1, characterized in that: In step 3, the amount of the mixed solution added is 1 to 4 mL; the substrate is an aluminum substrate with a size of φ30 to 60 mm.

6. The method for preparing an inorganic bulk luminescent material according to claim 1, characterized in that: In step 3, the rotation speed of the rotating table is 60-70 r / min, and the rotation time is 30 min.

7. The method for preparing an inorganic bulk luminescent material according to claim 1, characterized in that: In step 4, the heating temperature of the hot air blower is 120-150° C., and the heating time is 2 min.

8. The method for preparing an inorganic bulk luminescent material according to claim 1, characterized in that: In step 5, the heating temperature of the muffle furnace is 180-200° C., and the insulation time is 10 min.

9. An inorganic bulk luminescent material obtained by the preparation method according to any one of claims 1 to 8, characterized in that: The invention comprises an inorganic matrix, fluorescent powder dispersed inside and a substrate at the bottom, wherein the quantum efficiency of the inorganic bulk luminescent material is 95-98% of that of the fluorescent powder, and the light decay at 150° C. is 0.9-8.1%.

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