Composite particles, method for preparing the same, and method for preparing an LED packaging body

Abstract

The present disclosure provides a composite particle, a preparation method thereof, and a preparation method of an LED encapsulant. The composite particle includes a core and a shell. The core includes a crosslinked product of a stimulus-responsive monomer and a vinyl monomer, and an antioxidant, and the antioxidant is dispersed in the crosslinked product; the shell includes polyacrylate, and the thickness of the shell is 1 to 10 nm; the crosslinked product can undergo isomerization or rupture when irradiated at a wavelength of 200 to 400 nm. The above composite particle can be well-preserved before being used. When it is used, it can undergo isomerization or rupture when irradiated at a wavelength of 200 to 400 nm, and its thin shell also collapses accordingly, exposing the antioxidant, thereby protecting other substances used in common with the composite particle; when used in common with a silica gel glue, it avoids the premature contact of the antioxidant with the metal catalyst in the silica gel glue, rendering it ineffective.

Description

Technical Field

[0001] The present disclosure relates to the technical field of composite particles, and more particularly, to a composite particle, a preparation method thereof, and a method for preparing an LED encapsulation system. Background Art

[0002] Quantum dots have excellent optical properties and are regarded as one of the most promising technologies after the display industry. However, from the perspective of materials, the problem of the instability of quantum dots to water and oxygen hinders their application in actual processes. In recent years, the stability has often been improved by adding antioxidants or encapsulating a barrier layer on the surface of quantum dots. Summary of the Invention

[0003] The purpose of the present disclosure is to provide a composite particle, a preparation method thereof, and a method for preparing an LED encapsulation system, so as to solve the problem that antioxidants in the prior art deactivate the metal catalyst of silicone glue.

[0004] According to a first aspect of the present disclosure, there is provided a composite particle, which includes a core and a shell. The core includes a cross-linked product of a stimulus-responsive monomer and a vinyl monomer, and an antioxidant, and the antioxidant is dispersed in the cross-linked product; the shell includes polyacrylate, and the thickness of the shell is 1 to 10 nm; the cross-linked product can undergo isomerization or rupture when irradiated at a wavelength of 200 to 400 nm.

[0005] Optionally, the stimulus-responsive monomer includes one of azobenzene, o-nitrobenzyl ester, disulfide bond and vinyl, or the stimulus-responsive monomer contains a boron-substituted dipyrromethene structure and vinyl.

[0006] Optionally, the vinyl monomer is selected from at least one of the group consisting of methyl methacrylate, styrene, octadecyl methacrylate, cyclohexyl methacrylate, n-butyl methacrylate, isobornyl methacrylate, methyl acrylate, lauryl methacrylate, ethyl acrylate, vinyl acetate, butyl acrylate, and isooctyl acrylate.

[0007] Optionally, the antioxidant includes one or more of hindered phenols, hindered amines, phosphites, thioesters or thioethers.

[0008] Preferably, the antioxidant is selected from hindered phenol antioxidant 1010, hindered amine antioxidant DNP or phosphite antioxidant 168.

[0009] Optionally, the mass fraction of the antioxidant in the composite particle is 0.1 to 20%.

[0010] Optionally, the molecular weight of the cross-linked product is 10,000 to 5,000,000.

[0011] According to a second aspect of the present disclosure, there is provided a method for preparing the composite particles of any of the above, and the composite particles are prepared by an emulsion method.

[0012] Optionally, water, a first emulsifier, a first vinyl monomer, a co-stabilizer, a stimulus-responsive monomer, and an antioxidant are mixed in a container to perform pre-emulsification to obtain a first emulsion; water, a second emulsifier, and a second vinyl monomer are mixed to perform pre-emulsification to obtain a second emulsion; an initiator is added to the first emulsion, and the mixture is heated and reacted for a first period of time, then the second emulsion is added to the container in multiple portions, and the heating reaction ends after a second period of time; an organic alcohol is added to the container for demulsification, and after separation and purification, low-temperature vacuum drying is performed to obtain the composite particles.

[0013] Optionally, the mass of the second vinyl monomer is 5% to 30% of the mass of the first vinyl monomer.

[0014] According to a third aspect of the present disclosure, there is provided a method for preparing an LED package. The composite particles of any of the above, quantum dots, and silicone glue are mixed and disposed on an LED chip, and then the silicone glue is cured at a high temperature to obtain an intermediate LED package. The intermediate LED package is irradiated with light at 200 to 400 nm for a certain period of time to cause the core of the composite particles to isomerize or rupture, exposing the antioxidant, thereby obtaining the LED package.

[0015] Applying the above technical solution, the above composite particles can be well preserved before being used. When it is used, isomerization or rupture can occur under light irradiation at a wavelength of 200 to 400 nm, and its thin shell also collapses accordingly, exposing the antioxidant, thereby protecting other substances used in common with the composite particles. In particular, the composite particles can be used in common with quantum dots to achieve the protection of quantum dots. When it comes into contact with the silicone glue, the antioxidant is not exposed, avoiding the deactivation effect of the antioxidant on the metal catalyst required for the curing of the silicone glue. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The specification drawings constituting a part of this application are used to provide a further understanding of the present disclosure. The schematic embodiments of the present disclosure and their descriptions are used to explain the present disclosure and do not constitute an improper limitation to the present disclosure. In the drawings:

[0017] Figure 1 It is a schematic structural diagram of the composite particles according to an embodiment of the present disclosure.

[0018] Figure 2 It is a schematic diagram of the structural change of the composite particles according to an embodiment of the present disclosure under stimulus-responsive conditions.

[0019] Figure 3 It is a graph showing the change in the brightness decay of the quantum dot LED packages of some embodiments and comparative examples of the present disclosure.

[0020] Reference numerals: 1: core; 11: cross-linked product; 12: antioxidant; 2: shell. Detailed implementation mode

[0021] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs.

[0022] According to a first aspect of the present disclosure, there is provided a composite particle, which includes a core and a shell. The core includes a cross-linked product of a stimulus-responsive monomer and a vinyl monomer, and an antioxidant, and the antioxidant is dispersed in the cross-linked product; the shell includes polyacrylate, and the thickness of the shell is 1 to 10 nm; the cross-linked product can undergo isomerization or rupture when irradiated at a wavelength of 200 to 400 nm.

[0023] The above composite particles can be well preserved before being used. When it is used, isomerization (isomerization makes the gap between polymer molecules larger, and part of the antioxidant can flow out from the gap) or rupture can occur when irradiated at a wavelength of 200 to 400 nm, and its thin shell also collapses accordingly, exposing the antioxidant, thereby protecting other substances used in common with the composite particle. In particular, the composite particle can be used in common with quantum dots to achieve the protection of quantum dots. When in contact with silicone glue, the antioxidant is not exposed, avoiding the deactivation effect of the antioxidant on the metal catalyst.

[0024] In some embodiments, the size of the above core is 90 to 990 nm or 100 to 900 nm.

[0025] In some embodiments, the stimulus-responsive monomer is selected from those including functional groups such as azobenzene, o-nitrobenzyl ester, disulfide bond, etc. and vinyl, or the stimulus-responsive monomer contains a boron-substituted dipyrromethene structure and vinyl. The azobenzene group is based on isomerization, and the o-nitrobenzyl ester, disulfide bond group, and boron dipyrromethene structure are based on rupture.

[0026] In some embodiments, the vinyl monomer is selected from at least one of the group consisting of methyl methacrylate, styrene, octadecyl methacrylate, cyclohexyl methacrylate, n-butyl methacrylate, isobornyl methacrylate, methyl acrylate, lauryl methacrylate, ethyl acrylate, vinyl acetate, butyl acrylate, and isooctyl acrylate.

[0027] The antioxidants include elements P, S or N. In some embodiments, the antioxidants include one or more of hindered phenols, hindered amines, phosphites, thioesters or thioethers. The hindered phenols can be thiophenols, triazine hindered phenols, isocyanuric acid hindered phenols, etc. The hindered amines can be naphthylamine, diphenylamine, p-diphenylamine, quinoline derivatives, etc. In some preferred embodiments, the antioxidants are selected from hindered phenol antioxidant 1010, hindered amine antioxidant DNP or phosphite antioxidant 168.

[0028] In some embodiments, the mass fraction of the antioxidant in the composite particles is 0.1 - 20%, preferably 5% - 10%.

[0029] In some embodiments, the molecular weight of the cross-linked product is 10,000 - 5,000,000, preferably 50,000 - 500,000.

[0030] In some embodiments, the size of the composite particles is 10 - 1000 nanometers or 100 - 1000 nanometers. In some embodiments, the shape of the composite particles is spherical.

[0031] According to the second aspect of the present disclosure, there is provided a method for preparing the composite particles as described above, and the composite particles are prepared by an emulsion method.

[0032] In some embodiments, water, a first emulsifier, a first vinyl monomer, a co-stabilizer, a stimulus-responsive monomer and an antioxidant are mixed in a container to obtain a first emulsion by pre-emulsification; water, a second emulsifier and a second vinyl monomer are mixed to obtain a second emulsion by pre-emulsification; an initiator is added to the first emulsion, heated and reacted for a first time, then the second emulsion is added to the container in multiple portions, and the heating reaction ends after a second time; organic alcohol is added to the container for demulsification, and after separation and purification, low-temperature vacuum drying is carried out to obtain the composite particles.

[0033] In some embodiments, water and the first emulsifier are first stirred at a stirring speed of 100 - 1000 rpm for a time T1, and then the first vinyl monomer, the co-stabilizer, the stimulus-responsive monomer and the antioxidant are added and stirred for a time T2 to obtain the first emulsion, where T1 or T2 is 1 - 120 minutes.

[0034] The first vinyl monomer and the second vinyl monomer are the same or different. In some embodiments, the organic alcohol is ethanol.

[0035] In some embodiments, the emulsifier is selected from at least one of anionic emulsifiers, cationic emulsifiers, amphoteric emulsifiers and non-ionic emulsifiers.

[0036] In some embodiments, the mass of water is 100% - 1000% of the mass of the first vinyl monomer, the mass of the first emulsifier is 0.1% - 20% of the mass of water, the mass of the co-stabilizer is 0.01% - 1% of the mass of the first vinyl monomer, the mass of the stimulus-responsive monomer is 0.5% - 10% of the mass of the first vinyl monomer, and the mass of the antioxidant is 0.05% - 15% of the mass of the first vinyl monomer.

[0037] In some embodiments, the co-stabilizer is a long-chain fatty alcohol or a long-chain alkane, and the number of carbon atoms is not less than 16. In some embodiments, the number of carbon atoms of the co-stabilizer is less than or equal to 22. In some embodiments, the co-stabilizer is n-hexadecane.

[0038] In some embodiments, the temperature during the first heating reaction is selected from 20°C - 95°C, and the reaction time is 2h - 12h.

[0039] In some embodiments, the second emulsion is added using a feeder and is added within 5 - 120 minutes.

[0040] In some embodiments, the temperature during the second heating reaction is selected from 20°C - 95°C, and the reaction time is 0.5h - 24h.

[0041] In some embodiments, the mass of the second vinyl monomer is 5% - 30% of the mass of the first vinyl monomer. This further ensures that the shell polymer can cover the core, avoiding direct contact between the antioxidant and the silicone glue, and also preventing the antioxidant from being too thick to be exposed.

[0042] In some embodiments, the conditions for low-temperature vacuum drying are that the temperature is selected from 20°C - 80°C, the vacuum time is 0.5h - 12h, and the vacuum degree is less than -0.01 MPa.

[0043] In some embodiments, the product after low-temperature vacuum drying is pulverized, such as by grinding, to prepare composite particles with small sizes.

[0044] According to the third aspect of the present disclosure, a method for preparing an LED package is provided. The above composite particles, quantum dots, and silicone glue are mixed and disposed on an LED chip, and then the silicone glue is cured at a high temperature to obtain an intermediate LED package. The intermediate LED package is irradiated with light of 200 - 400 nm for a certain time, causing the core of the composite particles to isomerize or rupture, exposing the antioxidant, and obtaining the LED package.

[0045] The above preparation method avoids direct contact between the antioxidant and the silicone glue of the encapsulant, preventing the poisoning of the metal catalyst in the silicone glue. Since the thin shell of the composite particles has no cross-linked monomers, the shell layer will collapse and deform after the internal structure of the core changes or ruptures, and the exposed antioxidant can protect the quantum dots.

[0046] In some embodiments, the irradiation intensity is 0 to 800 mw / cm 2 , and the irradiation time is 5 min to 120 min.

[0047] Hereinafter, the embodiments will be described in more detail with reference to specific embodiments. However, they are exemplary examples of the present disclosure, and the present disclosure is not limited thereto.

[0048] Example 1

[0049] Weigh 0.8 g of sodium dodecylbenzenesulfonate and dissolve it in 100 g of water. After stirring at a stirring speed of 500 rpm for 30 min, an aqueous solution of emulsifier is obtained. Weigh 9 g of methyl methacrylate, 9 g of styrene, 0.02 g of n-hexadecane, 1.2 g of bisacrylcystamine (containing disulfide bond) and antioxidant 1010 of hindered phenol type in turn. After mutual dissolution, add them to the aqueous solution of emulsifier and continue stirring for 30 min to obtain the first emulsion.

[0050] Weigh 0.06 g of sodium dodecylbenzenesulfonate and dissolve it in 7 g of water. After stirring at a stirring speed of 500 rpm for 30 min, an aqueous solution of emulsifier is obtained. Weigh 0.6 g of butyl acrylate and 0.6 g of styrene and add them to the aqueous solution of emulsifier, and continue stirring for 30 min to obtain the second emulsion.

[0051] Weigh 0.5 g of potassium persulfate and add it to the first emulsion; after purging with nitrogen to remove oxygen, react at 70 °C, 500 rpm and under nitrogen protection for 4 h. Inject the second emulsion into the first emulsion at a rate of 0.27 mL / min and continue to react for 4 h.

[0052] After the reaction is completed, add 10 g of ethanol for demulsification, centrifuge at 8000 rpm for 10 min to obtain a precipitate, vacuum dry it at 70 °C for 12 h, take it out and grind it into powder to obtain powder composite particles.

[0053] Weigh 80 parts by mass of thermosetting methyl-phenyl silicone resin, uniformly mix 40 ppm of Karstedt catalyst (platinum catalyst), 19 parts by mass of quantum dot powder and 1 part by mass of functional particle powder, and place them in a vacuum stirring degassing machine. Under the conditions of a revolution speed of 600 rpm and a rotation speed of 500 rpm, vacuum stir and degas for 5 min to 10 min to obtain a mixed glue.

[0054] Use a dispensing machine to pour the mixed glue into the encapsulation cavity of the LED bracket, and place the LED bracket in an oven at 150 °C and bake for 2 h.

[0055] After curing, the LED chip is at 200mW / cm 2Irradiate it under a 365 nm ultraviolet lamp for 30 min. After that, take it out and place it in an oven at 65 °C and RH95% for aging. Take out the chip regularly and test its optical performance with an integrating sphere. Taking the first test point as 100%, the brightness data measured after aging is divided by the first test point to obtain the brightness percentage. Generally, for LED aging, the brightness attenuation is observed, which basically corresponds to the decrease in quantum dot efficiency.

[0056] Example 2

[0057] Weigh 0.8 g of sodium dodecylbenzenesulfonate and dissolve it in 100 g of water. After stirring at a stirring speed of 500 rpm for 30 min, an aqueous solution of emulsifier is obtained. Weigh 9 g of methyl methacrylate, 9 g of styrene, 0.02 g of n-hexadecane, 1.2 g of ((diazene-1,2-diylbis(4,1-phenylene))bis(oxy))bis(propane-3,1-diyl)bis(2-methylacrylate) and hindered phenol antioxidant 1010 in sequence. After mutual dissolution, add them to the aqueous solution of emulsifier and continue stirring for 30 min to obtain the first emulsion.

[0058] Weigh 0.06 g of sodium dodecylbenzenesulfonate and dissolve it in 7 g of water. After stirring at a stirring speed of 500 rpm for 30 min, an aqueous solution of emulsifier is obtained. Weigh 0.6 g of butyl acrylate and 0.6 g of styrene and add them to the aqueous solution of emulsifier, and continue stirring for 30 min to obtain the second emulsion.

[0059] Weigh 0.5 g of potassium persulfate and add it to the first emulsion; after purging with nitrogen to remove oxygen, react at 70 °C, 500 rpm and under nitrogen protection for 4 h. Inject the second emulsion into the first emulsion at a rate of 0.27 mL / min and continue to react for 4 h.

[0060] After the reaction is completed, add 10 g of ethanol to demulsify, centrifuge at 8000 rpm for 10 min to obtain a precipitate, dry it in vacuum at 70 °C for 12 h, take it out and grind it into powder to obtain powder-state composite particles.

[0061] Weigh 80 parts by mass of thermosetting methyl-phenyl silicone resin, uniformly mix 40 ppm of Karstedt catalyst (platinum catalyst) with 19 parts by mass of quantum dot powder and 1 part by mass of functional particle powder, and place them in a vacuum stirring degassing machine. Under the conditions of a revolution speed of 600 rpm and a rotation speed of 500 rpm, carry out vacuum stirring and degassing for 5 min to 10 min to obtain a mixed glue.

[0062] Use a dispensing machine to pour the mixed glue into the encapsulation cavity of the LED bracket, and place the LED bracket in an oven and bake it at 150 °C for 2 h.

[0063] After curing, place the LED chip at 200 mW / cm 2Irradiate it under a 365 nm ultraviolet lamp for 30 min. After that, take it out and place it in an oven at 65 °C and RH95% for aging. Take out the chip regularly and test its optical performance with an integrating sphere.

[0064] Comparative Example 1

[0065] Prepare the powdery composite particles in the same way as in Example 1.

[0066] Weigh 80 parts by mass of thermosetting methyl-phenyl silicone resin, 19 parts by mass of quantum dot powder and 1 part of powdery composite particles, mix them evenly, and place them in a vacuum stirring and degassing machine. Under the conditions of a revolution speed of 600 rpm and a rotation speed of 500 rpm, carry out vacuum stirring and degassing for 5 min - 10 min to obtain a mixed glue.

[0067] Use a dispensing machine to pour the mixed glue into the encapsulation cavity of the LED bracket, and place the LED bracket in an oven at 150 °C for baking for 2 h.

[0068] After the curing is completed, take it out and place it in an oven at 65 °C and RH95% for aging. Take out the chip regularly and test its optical performance with an integrating sphere.

[0069] Comparative Example 2

[0070] Weigh 80 parts by mass of thermosetting methyl-phenyl silicone resin, 40 ppm of Karstedt catalyst (platinum catalyst), 19 parts by mass of quantum dot powder and 1 part of hindered phenol antioxidant 1010, mix them evenly, and place them in a vacuum stirring and degassing machine. Under the conditions of a revolution speed of 600 rpm and a rotation speed of 500 rpm, carry out vacuum stirring and degassing for 5 min - 10 min to obtain a mixed glue.

[0071] Use a dispensing machine to pour the mixed glue into the encapsulation cavity of the LED bracket, and place the LED bracket in an oven at 150 °C for baking for 2 h.

[0072] After the curing is completed, take it out and place it in an oven at 65 °C and RH95% for aging. Take out the chip regularly and test its optical performance with an integrating sphere.

[0073] Comparative Example 3

[0074] Weigh 80 parts by mass of thermosetting methyl-phenyl silicone resin, 40 ppm of Karstedt catalyst (platinum catalyst) and 20 parts by mass of hindered phenol antioxidant 1010, mix them evenly, and place them in a vacuum stirring and degassing machine. Under the conditions of a revolution speed of 600 rpm and a rotation speed of 500 rpm, carry out vacuum stirring and degassing for 5 min - 10 min to obtain a mixed glue.

[0075] Use a dispensing machine to pour the mixed glue into the encapsulation cavity of the LED bracket, and place the LED bracket in an oven at 150 °C for baking for 2 h.

[0076] After the curing is completed, the LED chip is irradiated under a 365 nm ultraviolet lamp with a power of 200 mW / cm 2 for 30 min. After that, it is taken out and placed in an oven at 65 °C and RH95% for aging. The chip is taken out regularly and its optical performance is tested with an integrating sphere.

[0077] See Figure 3 for the aging test results of each example and comparative example. Figure 3 From the analysis of the test results, it can be seen that the LED chip prepared by the method of Example 1 has good stability, and its brightness attenuation remains within 5% after aging for 1000 h, indicating that after ultraviolet response stimulation, the composite particles of the powder release antioxidants, which can well maintain the stability of quantum dots. The composite particles prepared by the method of Example 2 represent that the structure of the composite particles is isomerized after ultraviolet response stimulation, and part of the antioxidant is exposed, protecting the quantum dots to a certain extent. Therefore, the brightness attenuation of its LED chip remains within 7.5% after aging for 1000 h. In Comparative Example 1, without ultraviolet stimulation, the antioxidant cannot be released, and its performance is close to that of Comparative Example 3 without adding antioxidants. In Comparative Example 2, antioxidants are directly added to the formula, resulting in the inability of the silicone resin to cure and the loss of its oxygen and water barrier capabilities, showing the worst performance.

[0078] The above are only the preferred embodiments of the present disclosure and are not used to limit the present disclosure. For those skilled in the art, the present disclosure can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A composite particle, characterized in that: The composite particles include a core and a shell, wherein the core includes a cross-linked product of a stimulus-responsive monomer and a vinyl monomer, and an antioxidant, wherein the antioxidant is dispersed in the cross-linked product; the shell includes polyacrylate, and the thickness of the shell is 1 to 10 nm; the cross-linked product is isomerized or ruptured when irradiated at a wavelength of 200 to 400 nm, and upon isomerization, the stimulus-responsive monomer includes azobenzene and vinyl.

2. The composite particle according to claim 1, characterized in that Based on the rupture, the stimulus responsive monomer includes o-nitrobenzyl ester, one of disulfide bonds and a vinyl group, or the stimulus responsive monomer contains a boron-substituted dipyrromethene structure and a vinyl group.

3. The composite particle according to claim 1, characterized in that The vinyl monomer is at least one selected from the group consisting of methyl methacrylate, styrene, octadecyl methacrylate, cyclohexyl methacrylate, n-butyl methacrylate, isobornyl methacrylate, methyl acrylate, lauryl methacrylate, ethyl acrylate, vinyl acetate, butyl acrylate, and isooctyl acrylate.

4. The composite particle according to claim 1, characterized in that The antioxidant includes one or more of hindered phenols, hindered amines, phosphites, thioesters or thioethers.

5. The composite particle according to claim 1, characterized in that The antioxidant is selected from hindered phenol antioxidant 1010, hindered amine antioxidant DNP or phosphite antioxidant 168.

6. The composite particle according to claim 1, characterized in that The mass fraction of the antioxidant in the composite particles is 0.1-20%.

7. The composite particle according to claim 1, characterized in that The molecular weight of the cross-linked product is 10,000 to 5,000,000.

8. A method for preparing composite particles according to any one of claims 1 to 7, characterized in that: The composite particles are prepared by an emulsion method.

9. The method for preparing composite particles according to claim 8, characterized in that: Water, a first emulsifier, a first vinyl monomer, a stabilizer, the stimulus-responsive monomer and the antioxidant are mixed in a container and pre-emulsified to obtain a first emulsion; water, a second emulsifier and a second vinyl monomer are mixed and pre-emulsified to obtain a second emulsion; an initiator is added to the first emulsion, heated to react for a first time, and then the second emulsion is added to the container in multiple times, and the heating reaction ends for a second time; an organic alcohol is added to the container to break the emulsion, and after separation and purification, low-temperature vacuum drying is performed to obtain the composite particles.

10. The method for preparing composite particles according to claim 9, characterized in that: The mass of the second vinyl monomer is 5% to 30% of the mass of the first vinyl monomer.

11. A method for preparing an LED package, characterized in that: The composite particles, quantum dots and silicone glue as described in any one of claims 1 to 7 are mixed and arranged on an LED chip, and then the silicone glue is cured at high temperature to obtain an intermediate LED package. The intermediate LED package is irradiated under 200-400nm light for a certain period of time to isomerize or rupture the cores of the composite particles and expose the antioxidant to obtain the LED package.

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