High-thermal-conductivity radiation refrigeration heat dissipation coating for LED (light-emitting diode) illumination module and preparation method thereof

Abstract

The invention belongs to the technical field of coating preparation, and provides a high-thermal-conductivity radiation refrigeration heat dissipation coating for an LED illumination module and a preparation method of the high-thermal-conductivity radiation refrigeration heat dissipation coating. The preparation method comprises the following steps: firstly, cooperatively coating a hexagonal boron nitride sheet with dopamine and tannic acid, and performing in-situ deposition of zinc oxide to obtain a sheet-shaped heat-conducting filler with low interface thermal resistance; secondly, hydrothermally generating magnesium silicate by utilizing the lignocellulose template, locally carbonizing in a nitrogen atmosphere, and grafting aminopropyl silane to form a heat-conducting framework; ytterbium-doped calcium titanate hollow spheres are prepared through a citric acid complexation method, an aluminum oxide-phosphate double-layer shell is constructed, three kinds of functional particles are dispersed with methyl-phenyl siloxane resin, a coupling agent and a low-volatility solvent at a high speed according to a set proportion, and the high-thermal-conductivity radiation refrigeration heat dissipation coating of the LED illumination module is obtained after vacuum defoaming.

Description

Technical Field

[0001] This invention belongs to the field of coating preparation technology, and relates to a high thermal conductivity radiation cooling and heat dissipation coating for LED lighting modules and its preparation method. Background Technology

[0002] As a solid-state light source, LEDs have continuously improved luminous efficiency, but a large portion of their electrical energy still accumulates as heat in the chip junction area. If heat dissipation is not timely, the increased junction temperature will lead to accelerated light decay, color drift, and even failure, thereby shortening the lamp's lifespan and affecting light quality. Existing heat dissipation solutions mainly rely on metal heat sinks, thermal grease, and black coatings. While traditional black paint can improve surface emissivity, it lacks sufficient thermal conductivity. Single-filler thermally conductive coatings (such as aluminum nitride, boron nitride, or aluminum oxide) cannot simultaneously meet the requirements of high thermal conductivity and high emissivity under thin-film conditions due to filling limits, interfacial adhesion, and cost. Some coatings incorporate graphene, carbon nanotubes, or diamond, but dispersion is difficult. Fluorination or chemical vapor deposition are used to achieve low interfacial thermal resistance, but the process requires high vacuum, highly corrosive gases, or high-energy-consuming equipment, posing significant safety and environmental challenges and hindering the adoption of these technologies in the conventional production lines of large-scale lighting companies. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention aims to provide a high thermal conductivity, radiation-induced cooling and heat dissipation coating for LED lighting modules and its preparation method. First, a dopamine-tannic acid bilayer and zinc oxide in-situ deposition technique are used to composite-coat boron nitride sheets, obtaining a thermally conductive unit with low interfacial thermal resistance. Second, magnesium silicate rods are grown using lignocellulose as a template, and after local carbonization in nitrogen, aminopropylsilane is grafted onto them to form longitudinal thermal bridges. Third, ytterbium-doped calcium titanate hollow spheres are prepared using a citric acid complexation method, thereby meeting the needs of actual production.

[0004] To achieve this objective, the present invention adopts the following technical solution:

[0005] In a first aspect, the present invention provides a method for preparing a high thermal conductivity, radiation-induced cooling and heat dissipation coating for LED lighting modules, the method comprising:

[0006] S1, add hexagonal boron nitride flake powder to deionized water for dispersion, add dopamine hydrochloride and Tris buffer, add tannic acid and zinc acetate aqueous solution to obtain modified boron nitride flake powder;

[0007] S2, dispersing lignocellulose powder in deionized water, adding magnesium chloride hexahydrate and sodium silicate nonahydrate sequentially to obtain a slurry, transferring the slurry to a hydrothermal reactor for reaction, filtering and drying the product, then carbonizing it in a nitrogen atmosphere to obtain powder, cooling the powder and adding anhydrous ethanol, adding γ-aminopropyltriethoxysilane to obtain magnesium silicate powder.

[0008] S3, dissolve calcium nitrate tetrahydrate in deionized water, add citric acid to complex, add tetrabutyl titanate and ytterbium nitrate pentahydrate under ice bath conditions to obtain a gel, dry the gel to dehydrate, pre-calcine and keep warm to obtain calcium titanate balls, disperse the calcium titanate balls in deionized water, add aluminum nitrate nonahydrate, filter, dry and calcine, spray with phosphoric acid solution and solidify to obtain calcium titanate hollow ball powder;

[0009] S4, methyl phenyl silicone resin, modified boron nitride flake powder, magnesium silicate powder and calcium titanate hollow sphere powder are mixed with γ-glycidoxypropyltriethoxysilane and dipropylene glycol methyl ether, and after degassing, a high thermal conductivity radiation cooling and heat dissipation coating for LED lighting modules is obtained.

[0010] Specifically, it includes:

[0011] S1. Add hexagonal boron nitride flake powder to deionized water for shear dispersion, add dopamine hydrochloride and Tris buffer, adjust pH to 8.3-8.7, add tannic acid and zinc acetate aqueous solution, adjust pH to 9.5-10.5, filter, wash and dry to obtain modified boron nitride flake powder;

[0012] S2, dispersing lignocellulose powder in deionized water, adding magnesium chloride hexahydrate and sodium silicate nonahydrate sequentially to obtain a slurry, transferring the slurry to a hydrothermal reactor, reacting at the first temperature, filtering and drying the product, then carbonizing it at the second temperature in a nitrogen atmosphere, cooling it, adding the powder to anhydrous ethanol, adding γ-aminopropyltriethoxysilane, refluxing and stirring at the third temperature to obtain magnesium silicate powder.

[0013] S3, dissolve calcium nitrate tetrahydrate in deionized water, heat to the fourth temperature and add citric acid to complex, add tetrabutyl titanate and ytterbium nitrate pentahydrate under ice bath conditions to obtain a gel, dry and dehydrate the gel, place it at the fifth temperature for pre-calcination, heat to the sixth temperature and hold to obtain calcium titanate spheres, disperse the calcium titanate spheres in deionized water, add aluminum nitrate nonahydrate, adjust the pH to 7.8-8.2 and react, filter and dry, calcine at the seventh temperature, spray with phosphoric acid solution and solidify to obtain calcium titanate hollow sphere powder;

[0014] S4, methyl phenyl silicone resin, modified boron nitride flake powder, magnesium silicate powder and calcium titanate hollow sphere powder are mixed with γ-glycidoxypropyltriethoxysilane and dipropylene glycol methyl ether, and after degassing, a high thermal conductivity radiation cooling and heat dissipation coating for LED lighting modules is obtained.

[0015] Boron nitride sheets exhibit chemical inertness. First, in a weakly alkaline Tris medium, the catechol and amine structures of dopamine undergo self-oxidative polymerization to generate a polydopamine film rich in hydroxyl, amine, and pyrrole rings. This film tightly adsorbs onto boron nitride through π-π stacking, while surface functional groups provide coordination sites for subsequent reactions. Tannic acid is then introduced; the multiple ortho- and phenolic hydroxyl groups in tannins can form hydrogen and ester bonds with the amine and phenolic hydroxyl groups on the polydopamine, further constructing a dense, cross-linked polyphenol network and enhancing the shell's mechanical toughness and chemical stability. Adding a zinc complex and adjusting the alkalinity of the system allows the catechol groups within the polydopamine layer to coordinate with zinc ions, leading to the adsorption and localized enrichment of zinc ions. Under alkaline conditions, zinc ions hydrolyze to form zinc hydroxide, which is then dehydrated and converted into nano-zinc oxide, uniformly dotted onto the polyphenol network surface. The zinc oxide nanodots are connected to the polyphenol shell by coordination bonds, reducing the thermal resistance at the filler-resin interface.

[0016] Lignocellulose naturally contains a large number of hydroxyl groups. Under hydrothermal conditions, these hydroxyl groups first coordinate and condense with magnesium ions and silicate ions, rapidly depositing magnesium silicate crystal nuclei on the fiber surface and growing outward along the fiber axis, ultimately forming a continuous inorganic shell while retaining the organic framework inside. The product is then subjected to gentle carbonization in nitrogen, causing the cellulose framework to partially dehydrate, deoxygenate, and rearrange into graphitized carbon microfilaments, which are densely coated by the inorganic shell. The introduction of aminopropylsilane causes the silane hydrocarbon oxygen groups to condense with the hydroxyl groups in the inorganic shell, with the aminopropyl groups extending outward. During subsequent curing, these aminopropyl groups can further condense with the silicone resin, significantly reducing interfacial contact resistance. The magnesium silicate rods possess both longitudinally rigid lattice thermally conductive channels and achieve tight coupling with the resin through the carbon core and silane layer.

[0017] Citric acid simultaneously coordinates calcium and titanate ions to form a homogeneous organometallic gel. Ytterbium ions, incorporated into the gel framework, share sites with the calcium titanate octahedrons. During subsequent thermal decomposition, citric acid cracks, releasing gas and leaving behind a porous carbon skeleton. This is accompanied by phase rearrangement of the calcium titanate crystals, creating a hollow structure within the spherical particles, while the ytterbium ions remain stably within the lattice. Aluminum hydroxide is then deposited in a mildly alkaline aqueous system and calcined at low temperature to form a nanoscale alumina shell, providing mechanical reinforcement and a thermal barrier. A phosphoric acid aqueous solution is then sprayed and solidified, forming a dense coordination layer between the phosphate ions and the alumina surface, blocking moisture and ion erosion. The resulting hollow calcium titanate spheres have an internal heat storage cavity, while the outer double shell provides structural stability and moisture protection. The ytterbium-doped perovskite crystals generate a strong absorption-emission passband in the mid-infrared atmospheric window, enabling them to simultaneously perform radiative cooling within the heat conduction network.

[0018] As a preferred embodiment of the present invention, in S1, the mass ratio of the hexagonal boron nitride flake powder, deionized water, dopamine hydrochloride, Tris buffer, tannic acid, and zinc acetate aqueous solution is (100-110):(2000-2200):(1.8-2.2):(1.8-2.2):(1.8-2.2):(193-235), for example, it can be (100, 101, 102, 103, 104, 105, 106, 107, 108, 109 or 110):(2000, 2020, 2040, 2060, 2080, 2100, 2120, 2140, 2160, 2180 or 2200):(1.8, 1.84). 1.88, 1.92, 1.96, 2.0, 2.04, 2.08, 2.12, 2.16 or 2.2: (1.8, 1.84, 1.88, 1.92, 1.96, 2.0, 2.04, 2.08, 2.12, 2.16 or 2.2): (1.8, 1.84, 1.88, 1.92, 1.96, 2.0, 2.04, 2.08, 2.12, 2.16 or 2.2): (193, 197.2, 201.4, 205.6, 209.8, 214, 218.2, 222.4, 226.6, 230.8 or 235), but not limited to the listed values; other unlisted values ​​within this range also apply.

[0019] In some optional instances, the zinc acetate aqueous solution has a mass fraction of 6-8 wt.%, for example, 6 wt.%, 6.2 wt.%, 6.4 wt.%, 6.6 wt.%, 6.8 wt.%, 7 wt.%, 7.2 wt.%, 7.4 wt.%, 7.6 wt.%, 7.8 wt.%, or 8 wt.%, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0020] As a preferred technical solution of the present invention, in S2, the mass ratio of the lignocellulose powder, magnesium chloride hexahydrate, and sodium silicate nonahydrate is (18-22):(54-66):(36-44), for example, it can be (18, 18.4, 18.8, 19.2, 19.6, 20, 20.4, 20.8, 21.2, 21.6 or 22):(54, 55.2, 56.4, 57.6, 58.8, 60, 61.2, 62.4, 63.6, 64.8 or 66):(36, 36.9, 37.8, 38.7, 39.6, 40.5, 41.4, 42.3, 43.2, 44.1 or 44), but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0021] In some alternative instances, the first temperature is 175-185°C, for example, it can be 175°C, 176°C, 177°C, 178°C, 179°C, 180°C, 181°C, 182°C, 183°C, 184°C or 185°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0022] In some alternative instances, the reaction time at the first temperature is 7-9 hours, for example, 7 hours, 7.2 hours, 7.4 hours, 7.6 hours, 7.8 hours, 8 hours, 8.2 hours, 8.4 hours, 8.6 hours, 8.8 hours, or 9 hours, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0023] In some alternative instances, the second temperature is 290-310°C, for example, it can be 290°C, 292°C, 294°C, 296°C, 298°C, 300°C, 302°C, 304°C, 306°C, 308°C or 310°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0024] In some optional instances, the carbonization time is 0.8-1.2 h, for example, it can be 0.8 h, 0.84 h, 0.88 h, 0.92 h, 0.96 h, 1.0 h, 1.04 h, 1.08 h, 1.12 h, 1.16 h or 1.2 h, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0025] In some alternative instances, the mass ratio of the powder, anhydrous ethanol, and γ-aminopropyltriethoxysilane is 100:(90-100):(1.8-2.2), for example, it can be 100:(90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or 100):(1.8, 1.84, 1.88, 1.92, 1.96, 2.0, 2.04, 2.08, 2.12, 2.16 or 2.2), but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0026] In some optional instances, the third temperature is 55-65°C, for example, it can be 55°C, 56°C, 57°C, 58°C, 59°C, 60°C, 61°C, 62°C, 63°C, 64°C or 65°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0027] In some optional instances, the reflux stirring time is 1.5-2.5 h, for example, it can be 1.5 h, 1.6 h, 1.7 h, 1.8 h, 1.9 h, 2.0 h, 2.1 h, 2.2 h, 2.3 h, 2.4 h or 2.5 h, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0028] In a preferred embodiment of the present invention, in step S3, the mass ratio of calcium nitrate tetrahydrate, citric acid, tetrabutyl titanate, and ytterbium nitrate pentahydrate is (53-65):(104-126):(61-75):(6-8), for example, it can be (53, 54.2, 55.4, 56.6, 57.8, 59, 60.2, 61.4, 62.6, 63.8, or 65):(104, 106.2, 108.4, 110.6). 112.8, 115, 117.2, 119.4, 121.6, 123.8 or 126: (61, 62.4, 63.8, 65.2, 66.6, 68, 69.4, 70.8, 72.2, 73.6 or 75): (6, 6.2, 6.4, 6.6, 6.8, 7.0, 7.2, 7.4, 7.6 or 8), but not limited to the listed values; other unlisted values ​​within this range also apply.

[0029] In some alternative instances, the fourth temperature is 78-82°C, for example, it can be 78°C, 78.4°C, 78.8°C, 79.2°C, 79.6°C, 80°C, 80.4°C, 80.8°C, 81.2°C, 81.6°C, or 82°C, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0030] In some optional instances, the fifth temperature is 280-320°C, for example, it can be 280°C, 284°C, 288°C, 292°C, 296°C, 300°C, 304°C, 308°C, 312°C, 316°C or 320°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0031] In some optional instances, the precalcination time is 1.5-2.5 h, for example, it can be 1.5 h, 1.6 h, 1.7 h, 1.8 h, 1.9 h, 2.0 h, 2.1 h, 2.2 h, 2.3 h, 2.4 h or 2.5 h, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0032] In some optional examples, the phosphoric acid solution has a mass fraction of 85 wt.%.

[0033] In some optional instances, the sixth temperature is 640-660°C, for example, it can be 640°C, 642°C, 644°C, 646°C, 648°C, 650°C, 652°C, 654°C, 656°C, 658°C or 660°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0034] In some optional instances, the holding time at the sixth temperature is 1.5-2.5 hours, for example, it can be 1.5 hours, 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours, 2.0 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours or 2.5 hours, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0035] In some alternative examples, the mass ratio of the calcium titanate balls, aluminum nitrate nonahydrate, and phosphoric acid solution is (95-100):(6-8):(0.4-0.6), for example, it can be (95, 95.5, 96, 96.5, 97, 97.5, 98, 98.5, 99, 99.5 or 100):(6, 6.2, 6.4, 6.6, 6.8, 7.0, 7.2, 7.4, 7.6 or 8):(0.4, 0.42, 0.44, 0.46, 0.48, 0.5, 0.52, 0.54, 0.56, 0.58 or 0.6), but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0036] In some alternative instances, the time for adjusting the pH to 7.8-8.2 and reacting is 0.8-1.2 h, for example, it can be 0.8 h, 0.84 h, 0.88 h, 0.92 h, 0.96 h, 1.0 h, 1.04 h, 1.08 h, 1.12 h, 1.16 h or 1.2 h, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0037] In some optional instances, the seventh temperature is 290-310°C, for example, it can be 290°C, 292°C, 294°C, 296°C, 298°C, 300°C, 302°C, 304°C, 306°C, 308°C or 310°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0038] In some optional instances, the calcination time at the seventh temperature is 1-2 hours, for example, it can be 1 hour, 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours, 1.5 hours, 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours or 2 hours, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0039] In some optional instances, the curing temperature is 115-125°C, for example, 115°C, 116°C, 117°C, 118°C, 119°C, 120°C, 121°C, 122°C, 123°C, 124°C or 125°C, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0040] In some optional instances, the curing time is 1-1.5 hours, for example, 1 hour, 1.05 hours, 1.1 hours, 1.15 hours, 1.2 hours, 1.25 hours, 1.3 hours, 1.35 hours, 1.4 hours, 1.45 hours, or 1.5 hours, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0041] As a preferred embodiment of the present invention, in S4, the mass ratio of the methylphenyl silicone resin, modified boron nitride flake powder, magnesium silicate powder, calcium titanate hollow sphere powder, γ-glycidoxypropyltriethoxysilane, and dipropylene glycol methyl ether is (270-330):(150-185):(200-230):(125-155):(6-8):(80-90), for example, it can be (270, 276, 282, 288, 294, 300, 306, 312, 318, 324 or 330):(150, 153.5, 157, 160.5, 164, 167.5, 171, 1 74.5, 178, 181.5 or 185: (200, 203, 206, 209, 212, 215, 218, 221, 224, 227 or 230): (125, 128, 131, 134, 137, 140, 143, 146, 149, 152 or 155): (6, 6.2, 6.4, 6.6, 6.8, 7.0, 7.2, 7.4, 7.6, 7.8 or 8): (80, 81, 82, 83, 84, 85, 86, 87, 88, 89 or 90), but not limited to the listed values; other unlisted values ​​within this range also apply.

[0042] In a second aspect, the present invention provides a high thermal conductivity radiation cooling and heat dissipation coating for LED lighting modules prepared by the preparation method described in the first aspect.

[0043] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) Through the synergistic effect of modified boron nitride flake powder, magnesium silicate powder and calcium titanate hollow sphere powder, an efficient heat conduction path is constructed. Modified boron nitride provides the dominant heat path, and magnesium silicate and calcium titanate effectively enhance the overall thermal conductivity of the coating by reducing interfacial thermal resistance and optimizing the heat conduction path; (2) The surface infrared emission characteristics of modified boron nitride and magnesium silicate, as well as the porous structure and infrared emission capability of calcium titanate hollow spheres, jointly improve the infrared radiation performance of the coating, especially achieving efficient heat dissipation in the atmospheric window band and achieving passive radiation cooling effect; (3) Methylphenyl silicone resin, as a polysiloxane, has both high thermal stability and excellent UV and humid heat resistance, so that the material can maintain structural integrity and performance stability for a long time under extreme environments such as high temperature and strong light, and improve the uniform dispersion and long-term reliability of the system. Detailed Implementation

[0044] The technical solution of the present invention will be described in detail below with reference to specific embodiments. The embodiments described herein are specific implementations of the present invention and are used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary and should not be construed as limiting the implementation of the present invention or the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the content disclosed in the claims and the specification of this application. These technical solutions include those that make any obvious substitutions and modifications to the embodiments described herein.

[0045] The chemical reagents used in the embodiments and comparative examples of this invention are all commercially available products and have not undergone any further purification treatment.

[0046] Example 1

[0047] This embodiment provides a high thermal conductivity radiation cooling and heat dissipation coating for LED lighting modules and its preparation method. The preparation method specifically includes the following steps:

[0048] S1, 100g of hexagonal boron nitride flake powder was added to 2000g of deionized water for shear dispersion, 1.8g of dopamine hydrochloride and 1.8g of Tris buffer were added to adjust the pH to 8.3, 1.8g of tannic acid and zinc acetate aqueous solution were added to adjust the pH to 9.5, and the mixture was filtered, washed and dried to obtain modified boron nitride flake powder;

[0049] S2, 18g of lignocellulose powder was dispersed in deionized water, and 54g of magnesium chloride hexahydrate and 36g of sodium silicate nonahydrate were added sequentially to obtain a slurry. The slurry was transferred to a hydrothermal reactor and reacted at 175℃ for 7h. The product was filtered, dried, and then carbonized at 290℃ for 0.8h in a nitrogen atmosphere. After cooling, 100g of powder was added to 90g of anhydrous ethanol, and 1.8g of γ-aminopropyltriethoxysilane was added. The mixture was refluxed and stirred at 55℃ for 1.5h to obtain magnesium silicate powder.

[0050] S3, 53g of calcium nitrate tetrahydrate was dissolved in deionized water, heated to 78℃ and 104g of citric acid was added for complexation, 61g of tetrabutyl titanate and 6g of ytterbium pentahydrate were added under ice bath conditions to obtain a gel, the gel was dried and dehydrated, placed at 280℃ for 1.5h for pre-calcination, heated to 640℃ and held for 1.5h to obtain calcium titanate spheres, the calcium titanate spheres were dispersed in deionized water, 6g of aluminum nitrate nonahydrate was added, the pH was adjusted to 7.8 and reacted for 0.8h, filtered and dried, calcined at 290℃ for 1h, 0.4g of 85wt.% phosphoric acid solution was sprayed in and cured at 115℃ for 1h to obtain calcium titanate hollow sphere powder;

[0051] S4, 270g of 60% solid content methyl phenyl silicone resin, 150g of modified boron nitride flake powder, 200g of magnesium silicate powder and 125g of calcium titanate hollow sphere powder, then add 6g of γ-glycidoxypropyltriethoxysilane and 80g of dipropylene glycol methyl ether and mix, after degassing, to obtain a high thermal conductivity radiation cooling and heat dissipation coating for LED lighting modules.

[0052] Example 2

[0053] This embodiment provides a high thermal conductivity radiation cooling and heat dissipation coating for LED lighting modules and its preparation method. The preparation method specifically includes the following steps:

[0054] S1, 105g of hexagonal boron nitride flake powder was added to 2150g of deionized water for shear dispersion, 2.1g of dopamine hydrochloride and 2.1g of Tris buffer were added to adjust the pH to 8.6, 2.1g of tannic acid and zinc acetate aqueous solution were added to adjust the pH to 10.2, and the mixture was filtered, washed and dried to obtain modified boron nitride flake powder;

[0055] S2, 19g of lignocellulose powder was dispersed in deionized water, and 62g of magnesium chloride hexahydrate and 42g of sodium silicate nonahydrate were added sequentially to obtain a slurry. The slurry was transferred to a hydrothermal reactor and reacted at 182℃ for 8.5h. The product was filtered, dried, and then carbonized at 305℃ for 1.1h in a nitrogen atmosphere. After cooling, 100g of the powder was added to 98g of anhydrous ethanol, and 2.1g of γ-aminopropyltriethoxysilane was added. The mixture was refluxed and stirred at 62℃ for 2.2h to obtain magnesium silicate powder.

[0056] S3, dissolve 62g of calcium nitrate tetrahydrate in deionized water, heat to 81℃ and add 120g of citric acid to complex, add 72g of tetrabutyl titanate and 7.5g of ytterbium pentahydrate under ice bath conditions to obtain a gel, dry the gel to remove water, place it at 310℃ for 2.2h for pre-calcination, raise the temperature to 655℃ and hold for 2.2h to obtain calcium titanate spheres, disperse the calcium titanate spheres in deionized water, add 7.5g of aluminum nitrate nonahydrate, adjust the pH to 8.1 and react for 1.1h, filter and dry, calcine at 305℃ for 1.8h, spray in 0.55g of 85wt.% phosphoric acid solution and solidify at 122℃ for 1.3h to obtain calcium titanate hollow sphere powder;

[0057] S4, 310g of 60% solid content methyl phenyl silicone resin, 160g of modified boron nitride flake powder, 220g of magnesium silicate powder and 150g of calcium titanate hollow sphere powder, then add 7.5g of γ-glycidoxypropyltriethoxysilane and 88g of dipropylene glycol methyl ether and mix, after degassing, to obtain a high thermal conductivity radiation cooling and heat dissipation coating for LED lighting modules.

[0058] Example 3

[0059] This embodiment provides a high thermal conductivity radiation cooling and heat dissipation coating for LED lighting modules and its preparation method. The preparation method specifically includes the following steps:

[0060] S1, 108g of hexagonal boron nitride flake powder was added to 2100g of deionized water for shear dispersion, 2.0g of dopamine hydrochloride and 2.0g of Tris buffer were added to adjust the pH to 8.5, 2.0g of tannic acid and zinc acetate aqueous solution were added to adjust the pH to 10.0, and the mixture was filtered, washed and dried to obtain modified boron nitride flake powder;

[0061] S2, 20g of lignocellulose powder was dispersed in deionized water, and 60g of magnesium chloride hexahydrate and 40g of sodium silicate nonahydrate were added sequentially to obtain a slurry. The slurry was transferred to a hydrothermal reactor and reacted at 180℃ for 8h. The product was filtered, dried, and then carbonized at 300℃ for 1.0h in a nitrogen atmosphere. After cooling, 100g of the powder was added to 95g of anhydrous ethanol, and 2.0g of γ-aminopropyltriethoxysilane was added. The mixture was refluxed and stirred at 60℃ for 2.0h to obtain magnesium silicate powder.

[0062] S3, dissolve 60g of calcium nitrate tetrahydrate in deionized water, heat to 80℃ and add 115g of citric acid to complex, add 70g of tetrabutyl titanate and 7g of ytterbium pentahydrate under ice bath conditions to obtain a gel, dry the gel to remove water, place it at 300℃ for 2.0h for pre-calcination, raise the temperature to 650℃ and keep it at 2.0h to obtain calcium titanate spheres, disperse the calcium titanate spheres in deionized water, add 7g of aluminum nitrate nonahydrate, adjust the pH to 8.0 and react for 1.0h, filter and dry, calcine at 300℃ for 1.5h, spray in 0.5g of 85wt.% phosphoric acid solution and cure at 120℃ for 1.2h to obtain calcium titanate hollow sphere powder;

[0063] S4, 300g of 60% solid content methyl phenyl silicone resin, 170g of modified boron nitride flake powder, 210g of magnesium silicate powder and 140g of calcium titanate hollow sphere powder, then add 7g of γ-glycidoxypropyltriethoxysilane and 85g of dipropylene glycol methyl ether and mix, after degassing, to obtain a high thermal conductivity radiation cooling and heat dissipation coating for LED lighting modules.

[0064] Example 4

[0065] This embodiment provides a high thermal conductivity radiation cooling and heat dissipation coating for LED lighting modules and its preparation method. The preparation method specifically includes the following steps:

[0066] S1, 110g of hexagonal boron nitride flake powder was added to 2200g of deionized water for shear dispersion, 2.2g of dopamine hydrochloride and 2.2g of Tris buffer were added to adjust the pH to 8.7, 2.2g of tannic acid and zinc acetate aqueous solution were added to adjust the pH to 10.5, and the mixture was filtered, washed and dried to obtain modified boron nitride flake powder;

[0067] S2, 22g of lignocellulose powder was dispersed in deionized water, and 66g of magnesium chloride hexahydrate and 44g of sodium silicate nonahydrate were added sequentially to obtain a slurry. The slurry was transferred to a hydrothermal reactor and reacted at 185℃ for 9h. The product was filtered, dried, and then carbonized at 310℃ for 1.2h in a nitrogen atmosphere. After cooling, 100g of the powder was added to 100g of anhydrous ethanol, and 2.2g of γ-aminopropyltriethoxysilane was added. The mixture was refluxed and stirred at 65℃ for 2.5h to obtain magnesium silicate powder.

[0068] S3, dissolve 65g of calcium nitrate tetrahydrate in deionized water, heat to 82℃ and add 126g of citric acid to complex, add 75g of tetrabutyl titanate and 8g of ytterbium pentahydrate under ice bath conditions to obtain a gel, dry the gel to dehydrate, place it at 320℃ for 2.5h for pre-calcination, raise the temperature to 660℃ and hold for 2.5h to obtain calcium titanate spheres, disperse the calcium titanate spheres in deionized water, add 8g of aluminum nitrate nonahydrate, adjust the pH to 8.2 and react for 1.2h, filter and dry, calcine at 310℃ for 2h, spray in 0.6g of 85wt.% phosphoric acid solution and cure at 125℃ for 1.5h to obtain calcium titanate hollow sphere powder;

[0069] S4, 330g of 60% solid content methyl phenyl silicone resin, 185g of modified boron nitride flake powder, 230g of magnesium silicate powder and 155g of calcium titanate hollow sphere powder, then add 8g of γ-glycidoxypropyltriethoxysilane and 90g of dipropylene glycol methyl ether and mix, after degassing, to obtain a high thermal conductivity radiation cooling and heat dissipation coating for LED lighting modules.

[0070] Comparative Example 1

[0071] This comparative example provides a high thermal conductivity radiation cooling and heat dissipation coating for LED lighting modules and its preparation method. The difference between this example and Example 1 is that the mass of modified boron nitride powder in S4 is 0, while other process parameters and operating conditions are exactly the same as in Example 1.

[0072] Comparative Example 2

[0073] This comparative example provides a high thermal conductivity radiation cooling and heat dissipation coating for LED lighting modules and its preparation method. The difference between this example and Example 1 is that the mass of magnesium silicate powder in S4 is 0, while other process parameters and operating conditions are exactly the same as in Example 1.

[0074] Comparative Example 3

[0075] This comparative example provides a high thermal conductivity radiation cooling and heat dissipation coating for LED lighting modules and its preparation method. The difference between this example and Example 1 is that the mass of calcium titanate hollow sphere powder in S4 is 0, while other process parameters and operating conditions are exactly the same as in Example 1.

[0076] The test methods for solar reflectivity and hemispherical emissivity are GB / T25261-2018. The test method for atmospheric window (8-13 μm) emissivity is as follows: using a reflectometer, such as the SOC-100 Hemispherical Directional Reflectometer, the infrared emissivity at wavelengths of 8–13 μm is measured; this is the atmospheric window emissivity. The test method for thermal conductivity is ASTM-E1530-06. The test results are shown in Table 1.

[0077] Table 1. Test results of high thermal conductivity radiation cooling and heat dissipation coatings for LED lighting modules in Examples 1-4 and Comparative Examples 1-3

[0078] Solar reflectance (%) Hemispherical emissivity (%) Atmospheric window emissivity (%) Thermal conductivity (W / m·K) Example 1 90 88 90 0.58 Example 2 91 90 92 0.55 Example 3 92 89 91 0.57 Example 4 91 91 91 0.56 Comparative Example 1 84 79 81 0.37 Comparative Example 2 82 80 78 0.42 Comparative Example 3 78 76 75 0.50

[0079] As shown in Table 1, compared to Example 1, the solar reflectance, hemispherical emissivity, atmospheric window (8-13 μm) emissivity, and thermal conductivity of Comparative Example 1 all decreased; the solar reflectance, hemispherical emissivity, atmospheric window (8-13 μm) emissivity, and thermal conductivity of Comparative Example 2 all decreased; and the solar reflectance, hemispherical emissivity, atmospheric window (8-13 μm) emissivity, and thermal conductivity of Comparative Example 3 all decreased. Boron nitride sheets have high in-plane thermal conductivity, enabling the construction of efficient heat conduction channels in the coating. Their sheet-like structure also provides some scattering and infrared emission enhancement. Comparative Example 1 lacks modified boron nitride sheet powder, therefore, the radiative cooling effect and thermal conductivity of Comparative Example 1 decreased. Magnesium silicate rod powder, with its one-dimensional structure, can act as a heat conduction pathway in the coating and contributes to light scattering and infrared emission within a certain wavelength range. Comparative Example 2 lacks magnesium silicate powder, therefore, the radiative cooling effect and thermal conductivity of Comparative Example 2 decreased. Hollow calcium titanate spheres are very beneficial for reducing coating density and improving light scattering (especially sunlight reflection). The difference in refractive index between the inner and outer layers of the hollow particles can provide multiple scattering paths for sunlight, thereby improving reflectivity. In Comparative Example 3, hollow calcium titanate spheres are missing, so the radiative cooling effect of Comparative Example 3 is reduced.

[0080] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a high thermal conductivity, radiation-induced cooling and heat dissipation coating for LED lighting modules, characterized in that, The preparation method includes: S1, add hexagonal boron nitride flake powder to deionized water for dispersion, add dopamine hydrochloride and Tris buffer, add tannic acid and zinc acetate aqueous solution to obtain modified boron nitride flake powder; S2, dispersing lignocellulose powder in deionized water, adding magnesium chloride hexahydrate and sodium silicate nonahydrate sequentially to obtain a slurry, transferring the slurry to a hydrothermal reactor for reaction, filtering and drying the product, then carbonizing it in a nitrogen atmosphere to obtain powder, cooling the powder and adding anhydrous ethanol, adding γ-aminopropyltriethoxysilane to obtain magnesium silicate powder. S3, dissolve calcium nitrate tetrahydrate in deionized water, add citric acid to complex, add tetrabutyl titanate and ytterbium nitrate pentahydrate under ice bath conditions to obtain a gel, dry the gel to dehydrate, pre-calcine and keep warm to obtain calcium titanate balls, disperse the calcium titanate balls in deionized water, add aluminum nitrate nonahydrate, filter, dry and calcine, spray with phosphoric acid solution and solidify to obtain calcium titanate hollow ball powder; S4, methyl phenyl silicone resin, modified boron nitride flake powder, magnesium silicate powder and calcium titanate hollow sphere powder are mixed with γ-glycidoxypropyltriethoxysilane and dipropylene glycol methyl ether, and after degassing, a high thermal conductivity radiation cooling and heat dissipation coating for LED lighting modules is obtained.

2. The method for preparing the high thermal conductivity radiation cooling and heat dissipation coating for LED lighting modules according to claim 1, characterized in that, In S1: The mass ratio of the hexagonal boron nitride flake powder, deionized water, dopamine hydrochloride, Tris buffer, tannic acid and zinc acetate aqueous solution is (100-110): (2000-2200): (1.8-2.2): (1.8-2.2): (1.8-2.2): (193-235).

3. The method for preparing the high thermal conductivity radiation cooling and heat dissipation coating for LED lighting modules according to claim 1, characterized in that, In S1: The zinc acetate aqueous solution has a mass fraction of 6wt.%-8wt.%.

4. The method for preparing the high thermal conductivity radiation cooling and heat dissipation coating for LED lighting modules according to claim 1, characterized in that, In S2: The mass ratio of the lignocellulose powder, magnesium chloride hexahydrate and sodium silicate nonahydrate is (18-22):(54-66):(36-44).

5. The method for preparing the high thermal conductivity radiation cooling and heat dissipation coating for LED lighting modules according to claim 1, characterized in that, In S2: The mass ratio of the powder, anhydrous ethanol and γ-aminopropyltriethoxysilane is 100:(90-100):(1.8-2.2).

6. The method for preparing the high thermal conductivity radiation cooling and heat dissipation coating for LED lighting modules according to claim 1, characterized in that, In S3: The mass ratio of calcium nitrate tetrahydrate, citric acid, tetrabutyl titanate and ytterbium nitrate pentahydrate is (53-65):(104-126):(61-75):(6-8).

7. The method for preparing the high thermal conductivity radiation cooling and heat dissipation coating for LED lighting modules according to claim 1, characterized in that, In S3: The mass ratio of the calcium titanate balls, aluminum nitrate nonahydrate, and phosphoric acid solution is (95-100):(6-8):(0.4-0.6).

8. The method for preparing the high thermal conductivity radiation cooling and heat dissipation coating for LED lighting modules according to claim 1, characterized in that, In S4: The mass ratio of the methylphenyl silicone resin, modified boron nitride flake powder, magnesium silicate powder, calcium titanate hollow sphere powder, γ-glycidoxypropyltriethoxysilane and dipropylene glycol methyl ether is (270-330):(150-185):(200-230):(125-155):(6-8):(80-90).

9. A high thermal conductivity radiation cooling coating for an LED lighting module obtained by the preparation method according to any one of claims 1-8.