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CN-122011904-A - Radiation refrigeration coating material and preparation method of radiation refrigeration double-layer coating

CN122011904ACN 122011904 ACN122011904 ACN 122011904ACN-122011904-A

Abstract

The invention provides a radiation refrigeration coating material and a preparation method of a radiation refrigeration double-layer coating. The radiation refrigeration coating material is composed of a bottom layer material and an upper layer material, wherein the bottom layer material and the upper layer material both comprise reflective filler, resin and other raw materials, and the two raw materials are respectively mixed at high speed, melted and extruded by double screws, finely ground, screened, cooled and packaged to obtain the bottom layer powder coating and the upper layer powder coating. When the coating is used, the two coatings are sprayed on the surface of a grounded metal workpiece through an electrostatic spray gun in sequence, and then the surface is heated and solidified to form a radiation refrigeration double-layer coating, wherein the radiation refrigeration double-layer coating has a reflectivity of up to 90.5% in a solar spectrum band of 0.3-2.5 mu m, and simultaneously has an emissivity of up to 96.5% in an atmospheric infrared window band of 8-13 mu m. The outdoor actual measurement result shows that the temperature of the inner surface of the electric cabinet sprayed with the coating can be reduced by 21.3 ℃ at most compared with untreated equipment under the condition of strong solar irradiation of about 900W/m <2 >, and the high-efficiency daytime radiation refrigeration can be realized without energy consumption.

Inventors

  • ZHAO BIN
  • JIN CHENG
  • PEI GANG
  • NI JIAHAO

Assignees

  • 中国科学技术大学

Dates

Publication Date
20260512
Application Date
20260326

Claims (10)

  1. 1. The radiation refrigeration coating material is characterized by comprising a bottom layer material and an upper layer material, wherein the raw materials of the bottom layer material and the upper layer material respectively comprise 40-70% of reflective filler, 25-60% of resin, 0-20% of curing agent, 0.5-1% of brightening agent, 0-1% of flatting agent, 0-1% of degasifying agent and 0.5-1% of auxiliary agent; the resin is one of polyester resin, hydroxy acrylic resin, polyvinylidene fluoride, polymethylpentene and fluorinated ethylene propylene copolymer; the curing agent is one of triglycidyl isocyanurate, beta-hydroxyalkylamide and blocked isocyanate; The brightening agent is one of polyacrylate, silicon-containing acrylate and perfluoroalkoxy resin; The leveling agent is one of fatty acid organic polymer and polyethylene-vinyl acetate; The degasifying agent is benzoin; The auxiliary agent is one of polyethylene wax, silicon micropowder and fluorinated wax; the reflective filler of the bottom layer material is nano titanium dioxide powder; the reflective filler of the upper layer material is at least one of nano zirconium dioxide powder, boron nitride nanosheets, nano aluminum oxide powder and barium sulfate powder; Mixing the raw materials of the bottom layer material at high speed, carrying out double-screw melt extrusion, pressing into brittle flakes by a cooling roller, finely grinding and screening the brittle flakes, cooling and packaging to obtain the bottom layer powder coating; Mixing the raw materials of the upper layer material at high speed, carrying out double-screw melt extrusion, pressing into brittle flakes by a cooling roller, finely grinding and screening the brittle flakes, cooling and packaging to obtain the upper layer powder coating; When the coating is used, the bottom powder coating and the upper powder coating are sprayed on the surface of the grounded metal workpiece through the electrostatic spray gun in sequence to be heated and cured to form a radiation refrigeration double-layer coating; The average particle diameter D50 of the bottom powder coating is controlled to be between 20 and 30 mu m, the content of fine powder with the particle diameter of less than 10 mu m is not higher than 10 percent, the content of coarse particles with the particle diameter of more than 50 mu m is not higher than 5 percent, the bottom powder is not agglomerated and not adhered under the storage and transportation environment of normal temperature to 40 ℃, and the gel time is 40 to 80s measured on a hot plate with the temperature of 180 to 330 ℃; the average particle diameter D50 of the upper layer powder coating is controlled to be between 20 and 30 mu m, the content of fine powder with the particle diameter of less than 10 mu m is not more than 8 percent, the content of coarse particles with the particle diameter of more than 50 mu m is not more than 5 percent, the upper layer powder is not agglomerated and not adhered in a storage and transportation environment with the temperature of between normal temperature and 40 ℃, and the gel time is 80 to 100 seconds as measured on a hot plate with the temperature of between 180 and 330 ℃.
  2. 2. The radiation refrigeration double-layer coating material of claim 1 is characterized in that the particle size of the nano titanium dioxide powder is 150-500 nm, the particle sizes of the nano zirconium dioxide powder and the nano aluminum oxide powder are 200-700 nm, the sheet diameter of the boron nitride nano sheet is 1-3 mu m, and the particle size of the barium sulfate powder is 1-2 mu m.
  3. 3. The radiation refrigeration double-layer coating material of claim 1, wherein the extrusion temperature of the twin-screw melt extrusion is 100-330 ℃.
  4. 4. The radiation refrigeration double-layer coating material according to claim 1, wherein the fine grinding and screening process conditions are that fine grinding is carried out in a high-speed pulverizer at a rotating speed of 20000-26000 rpm and a feeding speed of 20-50 kg/h under the condition that the temperature of cold air is less than or equal to 15 ℃, and screening is carried out in a totally-enclosed vibrating screen or rotary screen under the conditions that the mesh number of the screen is 160-200 meshes, the screen is continuously screened, and a material receiving system is sealed and moisture-proof.
  5. 5. A method for preparing a radiation refrigeration double-layer coating by using the radiation refrigeration coating material as claimed in claim 1, which is characterized by comprising the following operation steps: (1) Pretreating the surface of the treated metal workpiece, thoroughly removing greasy dirt and oxide skin on the surface of the metal workpiece through degreasing and rust removal, fully washing and drying, and grounding the clean metal workpiece; (2) The method comprises the steps of respectively conveying a bottom powder coating and an upper powder coating to different electrostatic spray guns by compressed air, spraying the bottom powder coating to the surface of a grounded metal workpiece by the spray guns, heating and shaping for the first time, and obtaining a bottom layer on the surface of the metal workpiece; (3) Spraying the upper layer powder coating on the surface of the bottom layer through a spray gun, heating and shaping for the second time to obtain an upper layer on the surface of the bottom layer, and solidifying and shaping the bottom layer and the upper layer to obtain a radiation refrigeration double-layer coating, wherein the thickness of the radiation refrigeration double-layer coating is 150-300 microns; The weighted average reflectivity of the radiation refrigeration double-layer coating in a solar radiation wave band of 0.3-2.5 mu m is larger than 0.90, the average emissivity of the radiation refrigeration double-layer coating in an atmospheric window wave band of 8-13 mu m is larger than 0.96, the adhesive force of the coating is tested according to GB/T9286, the cross-cut test is less than or equal to 1 level, the salt fog resistance of the coating is tested according to GB/T1771, the one-way corrosion spreading width at a marking line of neutral salt fog 1000 h is less than or equal to 2.0mm, the artificial weather aging resistance of the coating is tested according to GB/T1865, the exposure time is 500h, the color change level of the coating is less than or equal to 2 levels, and the abnormal phenomena such as pulverization, foaming, cracking and peeling are avoided.
  6. 6. The method of claim 5, wherein the electrostatic spraying process is carried out under the same conditions in the step (2) and the step (3), the spraying voltage is 60-90 kv, the atomization air pressure is 0.2-0.8 atm, the distance between the spray gun and the spray gun is 100-300 mm, and the moving speed of the spray gun is 0.1-0.5 m/s.
  7. 7. The method of claim 5, wherein in the step (2), the temperature of the oven for the first heating and shaping is 100-350 ℃ and the baking time is 1-3 minutes.
  8. 8. The method of claim 5, wherein in the step (2), the thickness of the bottom layer is 100-200 μm.
  9. 9. The method of claim 5, wherein in the step (3), the temperature of the oven for the second heating and shaping is 100-350 ℃ and the baking time is 10-15 minutes.
  10. 10. The method of claim 5, wherein in step (3), the thickness of the upper layer is 50-100 μm.

Description

Radiation refrigeration coating material and preparation method of radiation refrigeration double-layer coating Technical Field The invention belongs to the technical field of powder coating and radiation cooling materials, and particularly relates to a radiation refrigeration coating material and a preparation method for preparing a radiation refrigeration double-layer coating on a large scale based on electrostatic spraying. Background Global warming results in extremely high Wen Tianqi frequency, which poses a serious threat to the stable operation of outdoor power facilities. The radiation refrigeration technology has remarkable application potential as a passive cooling means without external energy input. The technology realizes continuous cooling by efficiently reflecting sunlight (wave band 0.3-2.5 μm) and mainly utilizing an atmospheric window (8-13 μm) to release heat to a low-temperature cosmic space in an infrared radiation mode. However, researches and applications of the radiation refrigeration technology are focused on the building energy-saving field, so as to reduce building energy consumption, and researches on heat dissipation management of outdoor power equipment are relatively deficient. The two have obvious differences in technical paths that radiation refrigeration coatings commonly used in the building field are mostly applied to cement-based surfaces, and excellent refrigeration performance can be realized by means of high-volume filler concentration, but the strategy is difficult to directly migrate to the scene of electric equipment. The reason is that the adhesion of the metal shell to the coating is poor and the coating needs to withstand various extreme weather conditions during long-term outdoor exposure. In addition, existing brush-coating type radiation refrigeration coatings generally rely on organic solvent to disperse fillers, and also present the risk of environmental pollution. Therefore, the radiation refrigeration coating material which has strong binding force with the metal matrix, is environment-friendly, has low cost and is suitable for large-scale preparation is developed, and has important value for improving the heat management capability of outdoor electric power facilities. Disclosure of Invention The invention provides a radiation refrigeration coating material for solving the problem that the existing radiation refrigeration technology is difficult to be directly applied to the surface of a metal shell of an outdoor electric power facility, and simultaneously provides a preparation method for manufacturing a radiation refrigeration double-layer coating based on the radiation refrigeration coating material. The radiation refrigeration coating material consists of a bottom layer material and an upper layer material, wherein the raw materials of the bottom layer material and the upper layer material respectively comprise 40-70% of reflective filler, 25-60% of resin, 0-20% of curing agent, 0.5-1% of brightening agent, 0-1% of flatting agent, 0-1% of degasifying agent and 0.5-1% of auxiliary agent; the resin is one of polyester resin, hydroxy acrylic resin, polyvinylidene fluoride, polymethylpentene and fluorinated ethylene propylene copolymer; the curing agent is one of triglycidyl isocyanurate, beta-hydroxyalkylamide and blocked isocyanate; The brightening agent is one of polyacrylate, silicon-containing acrylate and perfluoroalkoxy resin; The leveling agent is one of fatty acid organic polymer and polyethylene-vinyl acetate; The degasifying agent is benzoin; The auxiliary agent is one of polyethylene wax, silicon micropowder and fluorinated wax; the reflective filler of the bottom layer material is nano titanium dioxide powder; the reflective filler of the upper layer material is at least one of nano zirconium dioxide powder, boron nitride nanosheets, nano aluminum oxide powder and barium sulfate powder; Mixing the raw materials of the bottom layer material at high speed, carrying out double-screw melt extrusion, pressing into brittle flakes by a cooling roller, finely grinding and screening the brittle flakes, cooling and packaging to obtain the bottom layer powder coating; Mixing the raw materials of the upper layer material at high speed, carrying out double-screw melt extrusion, pressing into brittle flakes by a cooling roller, finely grinding and screening the brittle flakes, cooling and packaging to obtain the upper layer powder coating; When the coating is used, the bottom powder coating and the upper powder coating are sprayed onto the surface of a grounded metal workpiece through an electrostatic spray gun in sequence to be heated and cured to form a radiation refrigeration double-layer coating, and the schematic diagram of the radiation refrigeration double-layer coating is shown in (a) in fig. 1; The average particle diameter D50 of the bottom powder coating is controlled to be between 20 and 30 mu m, the content of fine powder with the particle di