A high refractive index LED packaging material and preparation method thereof

Abstract

The invention discloses a high-refractive-index LED packaging material and a preparation method thereof. The invention first performs hydroxylation modification on silicon nitride whiskers to increase the number of active hydroxyl groups on the surface of the silicon nitride whiskers, and then grafts polyethyleneimine on the surface of the silicon nitride whiskers through the action of a crosslinking agent, epichlorohydrin. The polyethyleneimine contains a flexible alkyl long-chain structure, which is introduced into the packaging material to improve the toughness of the material. Meanwhile, the polyethyleneimine contains a large number of amino groups, a part of which reacts with subsequent carbon disulfide, and another part of which reacts with active groups in epoxy resin, thereby improving the crosslinking degree of the packaging material and further improving the mechanical properties of the packaging material. Meanwhile, dithioamino groups are introduced into the surface of the silicon nitride whiskers, and the refractive index of the packaging material is improved by introducing sulfur elements.

Description

Technical Field

[0001] The invention relates to the technical field of packaging materials, and in particular to a high-refractive-index LED packaging material and a preparation method thereof. Background Art

[0002] Epoxy resin is a polymer material widely used in the field of electrical and electronic engineering. It has the characteristics of high bonding strength, small shrinkage and excellent electrical insulation performance. Its good heat resistance and high mechanical strength basically meet the special requirements of electrical and electronic component applications. However, epoxy resin material itself has inherent disadvantages of brittleness, large internal stress and insufficient toughness. In terms of LED packaging material application, the product has poor toughness and low refractive index, which limits its application in LED packaging materials.

[0003] At present, the industry has adopted a variety of approaches to modify epoxy resin. The more common method is to add nanoparticles, but the dispersion of nanoparticles is difficult, which limits the effect of nanoparticles. Chinese patent document CN202110730926.6 discloses a packaging material with the introduction of nano-zinc oxide protection and its preparation method and application. The introduced nano-zinc oxide absorbs high-energy ultraviolet rays to protect the inner layer of titanium dioxide. In addition, the addition of anti-reflective resin increases the transmittance of the film to light in other bands and improves the light utilization rate. However, the refractive index of the prepared packaging material is not high and the toughness is insufficient, and further improvement is still needed. Summary of the invention

[0004] In view of the deficiencies of the prior art, the purpose of the present invention is to provide a high refractive index LED packaging material and a preparation method thereof, so as to solve the technical problems of low refractive index and poor mechanical properties of the existing LED packaging materials.

[0005] In order to achieve the above object, the present invention adopts the following technical scheme:

[0006] A method for preparing a high refractive index LED packaging material comprises the following steps:

[0007] (1) dispersing silicon nitride whiskers in a nitric acid solution, heating and stirring to react, and after the reaction is completed, washing and drying the reaction product to obtain hydroxylated silicon nitride whiskers;

[0008] (2) dispersing hydroxylated silicon nitride whiskers in deionized water, adjusting the pH of the solution to 3-5, then adding polyethyleneimine and epichlorohydrin thereto, heating and stirring to react, and after the reaction is completed, washing and drying the reaction product to obtain amino-modified silicon nitride whiskers;

[0009] (3) dispersing the amino-modified silicon nitride whiskers in deionized water, adjusting the pH of the solution to 9-10, and then adding carbon disulfide thereto, sealing and stirring the reaction at room temperature for 2-4 hours, and after the reaction is completed, washing and drying the reaction product to obtain dithioamino-modified silicon nitride whiskers;

[0010] (4) adding the dithioamino-modified silicon nitride whiskers to the nano zirconium oxide dispersion, stirring at room temperature for 4-6 hours, and then filtering, washing, and drying to obtain modified silicon nitride whiskers loaded with zirconium oxide;

[0011] (5) Dispersing the modified silicon nitride whiskers loaded with zirconium oxide in an organic solvent, then adding epoxy resin, 4-methylhexahydrophthalic anhydride and tetrabutylammonium bromide, mixing evenly, and removing the organic solvent by vacuum distillation to carry out a curing reaction. After the reaction is completed, a high refractive index LED packaging material is obtained.

[0012] Preferably, in step (1), the mass fraction of the nitric acid solution is 40-60%.

[0013] Preferably, in step (1), the heating and stirring reaction temperature is 80-90° C., and the heating and stirring reaction time is 3-5 h.

[0014] Preferably, in step (2), the mass ratio of hydroxylated silicon nitride whiskers, polyethyleneimine and epichlorohydrin is 8-12:4-6:3-4.

[0015] Preferably, in step (2), the heating and stirring temperature is 50-80° C., and the heating and stirring time is 3-4 h.

[0016] Preferably, in step (3), the mass ratio of amino-modified silicon nitride whiskers to carbon disulfide is 6-10:2-4.

[0017] Preferably, in step (4), the mass ratio of dithioamino-modified silicon nitride whiskers to the nano-zirconia dispersion is 4-6:100, and the mass fraction of the nano-zirconia dispersion is 1-3%.

[0018] Preferably, in step (5), the mass ratio of the modified silicon nitride whiskers loaded with zirconium oxide, the epoxy resin, the 4-methylhexahydrophthalic anhydride and the tetrabutylammonium bromide is 5-10:100:20-30:1-3.

[0019] Preferably, in step (5), the curing conditions are: first curing at 60-80°C for 1-2 hours, and then curing at 100-120°C for 3-4 hours.

[0020] The present invention also provides a high-refractive-index LED packaging material prepared by the above preparation method.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The present invention first performs hydroxylation modification on silicon nitride whiskers to increase the number of active hydroxyl groups on the surface of silicon nitride whiskers, and then grafts polyethyleneimine onto the surface of silicon nitride whiskers through the action of a crosslinking agent, epichlorohydrin. Polyethyleneimine contains a flexible long-chain alkyl structure, which is introduced into the packaging material to improve the toughness of the material. Polyethyleneimine also contains a large number of amino groups, a portion of which reacts with subsequent carbon disulfide, and another portion of the amino groups reacts with active groups in the epoxy resin, thereby improving the crosslinking degree of the packaging material and thereby improving the mechanical properties of the packaging material.

[0023] (2) The present invention utilizes amino groups to react with carbon disulfide to introduce dithioamino groups into the surface of silicon nitride whiskers. By introducing sulfur, the refractive index of the packaging material is increased. At the same time, the dithioamino groups are electronegative. Through the interaction between charges, the positively charged nano-zirconia is evenly dispersed on the surface of the modified silicon nitride whiskers, thereby improving the problem of uneven dispersion of nano-zirconia and further increasing the refractive index of the packaging material. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below through specific preferred embodiments, but the present invention is not limited to the following embodiments.

[0025] It should be noted that, unless otherwise specified, the chemical reagents involved in the present invention were purchased through commercial channels.

[0026] The silicon nitride whiskers used in the present invention were purchased from Qinghe County Andy Metal Materials Co., Ltd., and the crystal form was α-Si3N4;

[0027] Polyethyleneimine was purchased from Hubei Xinyuhong Biopharmaceutical Technology Co., Ltd. with a molecular weight of 10,000;

[0028] The particle size of nano zirconium oxide is 20-40nm;

[0029] The epoxy resin model is E44, purchased from Wanqing Chemical Technology Co., Ltd., with a transmittance of 80.16% and a refractive index of 1.538.

[0030] Example 1

[0031] A method for preparing a high refractive index LED packaging material comprises the following steps:

[0032] (1) dispersing 10 g of silicon nitride whiskers in 200 mL of a 40 wt% nitric acid solution, heating and stirring at 80° C. for 5 h, and after the reaction is completed, washing and drying the reaction product to obtain hydroxylated silicon nitride whiskers;

[0033] (2) 8 g of hydroxylated silicon nitride whiskers were dispersed in 150 mL of deionized water, the pH of the solution was adjusted to 3, and then 4 g of polyethyleneimine and 3 g of epichlorohydrin were added thereto, and the mixture was heated and stirred at 50° C. for 4 h. After the reaction was completed, the reaction product was washed and dried to obtain amino-modified silicon nitride whiskers;

[0034] (3) 6 g of amino-modified silicon nitride whiskers were dispersed in 100 mL of deionized water, the pH of the solution was adjusted to 9, and then 2 g of carbon disulfide was added thereto. The mixture was sealed and stirred for reaction at room temperature for 2 h. After the reaction was completed, the reaction product was washed and dried to obtain dithioamino-modified silicon nitride whiskers;

[0035] (4) adding 4 g of dithioamino-modified silicon nitride whiskers to 100 g of 1 wt% nano zirconium oxide dispersion, stirring at room temperature for 4 h, and then filtering, washing, and drying to obtain zirconium oxide-loaded modified silicon nitride whiskers;

[0036] (5) Disperse 5 g of modified silicon nitride whiskers loaded with zirconium oxide in 250 mL of an organic solvent, xylene, and then add 100 g of epoxy resin, 20 g of 4-methylhexahydrophthalic anhydride, and 1 g of tetrabutylammonium bromide. After mixing evenly, remove the organic solvent by distillation under reduced pressure. First, cure at 60°C for 2 h, and then cure at 100°C for 3 h. After the reaction is completed, a high refractive index LED packaging material is obtained.

[0037] Example 2

[0038] A method for preparing a high refractive index LED packaging material comprises the following steps:

[0039] (1) dispersing 10 g of silicon nitride whiskers in 200 mL of a 60 wt % nitric acid solution, heating and stirring at 90° C. for 3 h, and after the reaction is completed, washing and drying the reaction product to obtain hydroxylated silicon nitride whiskers;

[0040] (2) dispersing 12 g of hydroxylated silicon nitride whiskers in 150 mL of deionized water, adjusting the pH of the solution to 4, then adding 6 g of polyethyleneimine and 4 g of epichlorohydrin thereto, heating and stirring at 80° C. for 3 h, and after the reaction is completed, washing and drying the reaction product to obtain amino-modified silicon nitride whiskers;

[0041] (3) dispersing 10 g of amino-modified silicon nitride whiskers in 100 mL of deionized water, adjusting the pH of the solution to 9, and then adding 4 g of carbon disulfide thereto, sealing and stirring the reaction at room temperature for 4 h, and after the reaction is completed, washing and drying the reaction product to obtain dithioamino-modified silicon nitride whiskers;

[0042] (4) adding 6 g of dithioamino-modified silicon nitride whiskers to 100 g of a 3 wt % nano zirconium oxide dispersion, stirring at room temperature for 4 h, and then filtering, washing, and drying to obtain zirconium oxide-loaded modified silicon nitride whiskers;

[0043] (5) 10 g of modified silicon nitride whiskers loaded with zirconium oxide were dispersed in 250 mL of an organic solvent, xylene, and then 100 g of epoxy resin, 30 g of 4-methylhexahydrophthalic anhydride, and 3 g of tetrabutylammonium bromide were added. After mixing evenly, the organic solvent was removed by distillation under reduced pressure. The mixture was first cured at 80°C for 1 h and then cured at 120°C for 4 h. After the reaction was completed, a high refractive index LED packaging material was obtained.

[0044] Example 3

[0045] A method for preparing a high refractive index LED packaging material comprises the following steps:

[0046] (1) dispersing 10 g of silicon nitride whiskers in 200 mL of a 50 wt% nitric acid solution, heating and stirring at 80° C. for 4 h, and after the reaction is completed, washing and drying the reaction product to obtain hydroxylated silicon nitride whiskers;

[0047] (2) dispersing 10 g of hydroxylated silicon nitride whiskers in 150 mL of deionized water, adjusting the pH of the solution to 4, then adding 5 g of polyethyleneimine and 4 g of epichlorohydrin thereto, heating and stirring at 60° C. for 4 h, and after the reaction is completed, washing and drying the reaction product to obtain amino-modified silicon nitride whiskers;

[0048] (3) 8 g of amino-modified silicon nitride whiskers were dispersed in 100 mL of deionized water, the pH of the solution was adjusted to 10, and then 3 g of carbon disulfide was added thereto. The mixture was sealed and stirred for reaction at room temperature for 4 h. After the reaction was completed, the reaction product was washed and dried to obtain dithioamino-modified silicon nitride whiskers;

[0049] (4) adding 5 g of dithioamino-modified silicon nitride whiskers to 100 g of a 2 wt % nano zirconium oxide dispersion, stirring at room temperature for 4 h, and then filtering, washing, and drying to obtain zirconium oxide-loaded modified silicon nitride whiskers;

[0050] (5) 8 g of modified silicon nitride whiskers loaded with zirconium oxide were dispersed in 250 mL of an organic solvent, xylene, and then 100 g of epoxy resin, 25 g of 4-methylhexahydrophthalic anhydride and 2 g of tetrabutylammonium bromide were added. After mixing evenly, the organic solvent was removed by distillation under reduced pressure. The mixture was first cured at 70°C for 1 h and then cured at 100°C for 4 h. After the reaction was completed, a high refractive index LED packaging material was obtained.

[0051] Comparative Example 1

[0052] A method for preparing an LED packaging material comprises the following steps:

[0053] 6 g of silicon nitride whiskers and 2 g of nano zirconium oxide were dispersed in 250 mL of an organic solvent, xylene. Then 100 g of epoxy resin, 25 g of 4-methylhexahydrophthalic anhydride and 2 g of tetrabutylammonium bromide were added. After mixing evenly, the organic solvent was removed by distillation under reduced pressure. The mixture was first cured at 70 ° C for 1 h and then cured at 100 ° C for 4 h. After the reaction was completed, the LED packaging material was obtained.

[0054] Comparative Example 2

[0055] A method for preparing an LED packaging material comprises the following steps:

[0056] (1) dispersing 10 g of silicon nitride whiskers in 200 mL of a 50 wt% nitric acid solution, heating and stirring at 80° C. for 4 h, and after the reaction is completed, washing and drying the reaction product to obtain hydroxylated silicon nitride whiskers;

[0057] (2) dispersing 10 g of hydroxylated silicon nitride whiskers in 150 mL of deionized water, adjusting the pH of the solution to 4, then adding 5 g of polyethyleneimine and 4 g of epichlorohydrin thereto, heating and stirring at 60° C. for 4 h, and after the reaction is completed, washing and drying the reaction product to obtain amino-modified silicon nitride whiskers;

[0058] (3) 6 g of amino-modified silicon nitride whiskers and 2 g of nano-zirconium oxide were dispersed in 250 mL of an organic solvent, xylene, and then 100 g of epoxy resin, 25 g of 4-methylhexahydrophthalic anhydride and 2 g of tetrabutylammonium bromide were added. After mixing evenly, the organic solvent was removed by distillation under reduced pressure. The mixture was first cured at 70°C for 1 h and then cured at 100°C for 4 h. After the reaction was completed, an LED packaging material was obtained.

[0059] The LED packaging materials prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to performance tests, and the specific steps were as follows:

[0060] Refractive index test: Use a WYW-2 Abbe refractometer to test the refractive index of the sample at a wavelength of 589nm at room temperature, and take the average value for the test at three different positions;

[0061] Tensile strength test: The reference standard is ASTM D638-08, and the test is carried out using the RGM-3030 electronic universal testing machine of Shenzhen Ruige Instrument Co., Ltd. The tensile rate is 10mm / min, and the average value is taken after 3 tests; the test results are shown in the following table:

[0062] Refractive index Tensile strength(MPa) Example 1 1.934 4.8 Example 2 1.941 4.9 Example 3 1.936 4.8 Comparative Example 1 1.709 3.5 Comparative Example 2 1.852 4.4

[0063] Finally, it should be noted that the above embodiments do not limit the present invention in any form. For those skilled in the art, some modifications and improvements can be made to the present invention. Therefore, any modification or improvement made without departing from the spirit of the present invention belongs to the scope of protection claimed in the present invention.

Claims

1. A method for preparing a high refractive index LED packaging material, characterized in that: The steps include: (1) dispersing silicon nitride whiskers in a nitric acid solution, heating and stirring to react, and after the reaction is completed, washing and drying the reaction product to obtain hydroxylated silicon nitride whiskers; (2) dispersing hydroxylated silicon nitride whiskers in deionized water, adjusting the pH of the solution to 3-5, then adding polyethyleneimine and epichlorohydrin thereto, heating and stirring to react, and after the reaction is completed, washing and drying the reaction product to obtain amino-modified silicon nitride whiskers; (3) dispersing the amino-modified silicon nitride whiskers in deionized water, adjusting the pH of the solution to 9-10, and then adding carbon disulfide thereto, sealing and stirring the reaction at room temperature for 2-4 hours, and after the reaction is completed, washing and drying the reaction product to obtain dithioamino-modified silicon nitride whiskers; (4) adding the dithioamino-modified silicon nitride whiskers to the nano zirconium oxide dispersion, stirring at room temperature for 4-6 hours, and then filtering, washing, and drying to obtain modified silicon nitride whiskers loaded with zirconium oxide; (5) Dispersing the modified silicon nitride whiskers loaded with zirconium oxide in an organic solvent, then adding epoxy resin, 4-methylhexahydrophthalic anhydride and tetrabutylammonium bromide, mixing evenly, and removing the organic solvent by vacuum distillation to carry out a curing reaction. After the reaction is completed, a high refractive index LED packaging material is obtained.

2. The preparation method according to claim 1, characterized in that: In step (1), the mass fraction of the nitric acid solution is 40-60%.

3. The preparation method according to claim 1, characterized in that: In step (1), the heating and stirring reaction temperature is 80-90° C., and the heating and stirring reaction time is 3-5 h.

4. The preparation method according to claim 1, characterized in that: In step (2), the mass ratio of hydroxylated silicon nitride whiskers, polyethyleneimine and epichlorohydrin is 8-12:4-6:3-4.

5. The preparation method according to claim 1, characterized in that: In step (2), the heating and stirring temperature is 50-80° C., and the heating and stirring time is 3-4 h.

6. The preparation method according to claim 1, characterized in that: In step (3), the mass ratio of amino-modified silicon nitride whiskers to carbon disulfide is 6-10:2-4.

7. The preparation method according to claim 1, characterized in that: In step (4), the mass ratio of dithioamino-modified silicon nitride whiskers to nano-zirconia dispersion is 4-6:100, and the mass fraction of the nano-zirconia dispersion is 1-3%.

8. The preparation method according to claim 1, characterized in that: In step (5), the mass ratio of the modified silicon nitride whisker loaded with zirconium oxide, epoxy resin, 4-methylhexahydrophthalic anhydride and tetrabutylammonium bromide is 5-10:100:20-30:1-3.

9. The preparation method according to claim 1, characterized in that: In step (5), the curing conditions are: first curing at 60-80°C for 1-2 hours, and then curing at 100-120°C for 3-4 hours.

10. The high refractive index LED packaging material prepared by the preparation method according to any one of claims 1 to 9.