Composite hydrophobic ardealite water-based building thermal insulation coating and preparation method thereof

Abstract

This invention specifically relates to a composite hydrophobic phosphogypsum water-based building thermal insulation coating and its preparation method. The thermal insulation coating is a water-based emulsion comprising polymer particles with a core and a shell structure. The core structure includes hydrophobically modified phosphogypsum, a hydrophobic flame retardant, and an aerogel; the shell structure is a silicone-acrylic resin binder. This invention uses a vertical mill air jet milling process to modify the size of the powder and hydrophobically modify the surface of the phosphogypsum powder. It then combines the phosphogypsum powder with the hydrophobic flame retardant and aerogel to obtain a hydrophobic spherical particle core. This core is then mixed with silicone-acrylic resin monomers and polymerized using an emulsion method to obtain a spherical emulsion polymer coated with silicone-acrylic resin. The resulting thermal insulation coating has strong adhesion, water resistance, and high-temperature resistance. The overall bonding improves the coating's thermal insulation, flame retardant, and high-temperature and high-humidity resistance properties. It can be used for wall insulation and fireproofing projects in high-humidity and large-temperature-difference scenarios such as building exterior walls, cold storage facilities, corrugated steel roofs, machinery and equipment, chemical plants, underground pipe corridors, and coastal buildings.

Description

Technical Field

[0001] This invention relates to a building insulation material, specifically to a composite hydrophobic phosphogypsum water-based building insulation coating and its preparation method. Background Technology

[0002] Phosphogypsum is a major byproduct of the phosphate chemical industry, with huge annual emissions. Long-term stockpiling leads to land occupation and heavy metal leachate pollution (such as F in phosphogypsum). - Phosphogypsum, whose main component is CaSO4·2H2O, is a Class A non-combustible material (GB 8624-2012) after being converted into β-hemihydrate gypsum. Its production energy consumption is only 1 / 4 that of cement, and carbon emissions are reduced by 60%. Alumina waste contains Al2O3 (≥60%) and is used in building coatings. Compared to traditional insulation materials (such as polystyrene boards) which have flammability and high carbon emissions, phosphogypsum has broad application prospects in building insulation materials.

[0003] However, the soluble P2O5 in phosphogypsum causes the coating to absorb moisture and soften, F - (0.1%–0.5%) Corrosion of metal keel. The usual way to improve the above defects is to wash the phosphogypsum with water to remove the corrosive fluorine-containing impurities, and calcine it to prepare stable β-hemihydrate gypsum, which has flame retardant effect and increases porosity by 50%–60%, giving it lightweight and porous properties.

[0004] Phospholipid-based materials have low compressive strength, typically <2MPa, making it difficult to meet the strength requirements for exterior walls of high-rise buildings. They are usually bonded to organic adhesives or cement to improve strength.

[0005] Invention CN114989656A discloses a heat-insulating slurry for building energy-saving coatings. The heat-insulating slurry comprises phosphogypsum, silica aerogel wet material, and water. The heat-insulating slurry is mixed with film-forming substances such as acrylic acid and fillers to prepare a building energy-saving coating. However, the aforementioned heat-insulating slurry and fillers have poor bonding performance with the film-forming substances and high water absorption, resulting in poor storage stability and water resistance of the coating. Furthermore, acrylic coatings themselves exhibit hot-sticking and cold-brittleness phenomena, limiting their application in certain environments, especially extreme environments such as high-temperature and high-humidity, and high-temperature-difference scenarios. Therefore, there is an urgent need for a multifunctional composite material that combines lightweight, heat insulation, flame retardancy, and water resistance. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention proposes a phosphogypsum composite hydrophobic and flame-retardant thermal insulation material and its preparation method, which can have multiple functions such as lightweight, thermal insulation, flame retardancy, and water resistance in extreme environments.

[0007] This invention is achieved through the following scheme:

[0008] A composite hydrophobic phosphogypsum water-based building thermal insulation coating, wherein the thermal insulation coating is a water-based emulsion, wherein the water-based emulsion comprises polymer microparticles with a core layer and a shell layer structure dispersed in water, wherein the core layer structure comprises hydrophobically modified phosphogypsum, hydrophobic flame retardant and silica aerogel; the shell layer structure is a silicone acrylic resin adhesive; and the mass ratio of the core layer to the shell layer of the polymer microparticles is 5-8:7-10.

[0009] Furthermore, the particle size of the polymer microparticles is 1-5 μm; the solid content of the aqueous emulsion is 40-60 wt%; and the mass ratio of the core layer hydrophobic modified phosphogypsum, hydrophobic flame retardant and silica aerogel is 3-5:1-2:1.

[0010] Furthermore, the preparation method of the hydrophobically modified phosphogypsum includes the following steps:

[0011] 1) Remove impurities from phosphogypsum to obtain pretreated phosphogypsum;

[0012] 2) The pretreated phosphogypsum is treated together with a surface modifier and a solvent by vertical milling / air jet milling and dried to obtain hydrophobic modified phosphogypsum; the surface modifier is a silane coupling agent, stearic acid or an organic carboxylate.

[0013] Furthermore, the pretreated phosphogypsum in step 1) meets or exceeds the grade II standard of GB / T 23456-2018 for phosphogypsum; and the D50 particle size of the hydrophobic modified phosphogypsum after treatment by vertical mill / air jet mill in step 2) is 200-400 nm.

[0014] Further, in step 2), the amount of surface modifier used is 1-6 wt% of the pretreated phosphogypsum; the mass ratio of surface modifier to solvent is 1:6-8; the solvent is ethanol; the drying temperature is 60-80℃; and the silane coupling agent is KH550, KH570, KH560 or KH590.

[0015] Furthermore, the hydrophobic flame retardant is expanded graphite and / or organosilicon resin, and the volume-to-mass ratio of the expanded graphite is 300-400 mL / g; the thermal insulation coating also contains auxiliary materials, which are at least one of nano-titanium dioxide and anti-aging agent; the amount of auxiliary materials added is 1-3 wt% of silicone-acrylic resin.

[0016] Furthermore, the preparation method of the composite hydrophobic phosphogypsum thermal insulation coating includes the following steps:

[0017] (3) The hydrophobic modified phosphogypsum, hydrophobic flame retardant and silica aerogel were vertically / air-flow milled to obtain composite hydrophobic modified phosphogypsum particles.

[0018] (4) The product obtained in step (1) is ultrasonically dispersed and mixed with the monomer of silicone-acrylic resin. Under stirring conditions, it is slowly added dropwise to water containing surfactant and co-solvent. Then, an initiator is slowly added to carry out the polymerization reaction. After the reaction, a thermal insulation coating containing phosphogypsum composite hydrophobic flame retardant polymer particles with core-shell structure is obtained.

[0019] Furthermore, in step (1), the particle size of the composite hydrophobic modified phosphogypsum particles after vertical mill / air jet milling is 400nm-800nm; in step (2), the monomers of the silicone-acrylic resin are organosilicon monomers and acrylic monomers containing unsaturated double bonds; the ultrasonic dispersion conditions are 30-50kHz, 10-30min.

[0020] Further, in step (2), the organosilicon monomer containing unsaturated double bonds is a vinyl-terminated silicone oil SHYH-VI401 or KH-Vi series; any one or more of the following acrylic monomers: methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, tert-butyl methacrylate, isobutyl methacrylate, isobornyl methacrylate, or lauryl methacrylate; the emulsifier includes anionic and nonionic emulsifiers, the anionic emulsifier being sodium dodecyl sulfate or sodium dodecylbenzene sulfonate; the nonionic emulsifier is fatty alcohol polyoxyethylene ether or fatty alcohol ether phosphate; the initiator includes AIBN, BPO, or ammonium persulfate; and the cosolvent is dipropylene glycol or propylene glycol propyl ether.

[0021] Further, in step (2), the mass ratio of organosilicon monomers containing unsaturated double bonds to acrylic monomers is 1-3:6-8; the amounts of initiator, emulsifier, and cosolvent are 0.5-1.5%, 5-10%, and 3-6% of the total mass of monomers in the silicone-acrylic resin, respectively; the mass ratio of anionic emulsifier to nonionic emulsifier is 1-2:6-10; the polymerization reaction temperature is 50-60℃, and the time is 1-3h; the vinyl content is 0.5-1wt%.

[0022] The vertical air jet mill combines a fluidized bed with a vertical classifier. Materials are pulverized within the fluidized bed by supersonic airflow impact, reducing equipment wear and improving product purity. The vertical classifier wheel precisely classifies particles using centrifugal force, eliminating the need for compressed air seals and preventing large particle leakage, resulting in high classification efficiency. It can produce multiple particle size ranges simultaneously, with a narrow particle size distribution and a minimum particle size (D50) as low as 0.2 micrometers, offering significant advantages over ball milling or grinding in powder processing.

[0023] Beneficial effects:

[0024] 1. This invention employs a vertical mill air jet milling process to modify the size of the powder and modify the surface of the phosphogypsum powder. The phosphogypsum powder is then composited with a hydrophobic flame retardant and aerogel to obtain a hydrophobic spherical particle core. This core is then mixed with monomers of silicone-acrylic resin and polymerized using an emulsion method to obtain a spherical emulsion polymer with a silicone-acrylic resin coating. The process is appropriate and the concept is novel, improving the dispersibility of phosphogypsum and simultaneously enhancing its adhesion to organic binders after hydrophobic modification.

[0025] 2. This invention employs coating and emulsion polymerization technology to prepare a core-shell structured coating emulsion. The inner layer is a composite hydrophobic modified phosphogypsum, enhancing compatibility with the intermediate flame retardant and aerogel layers. The outermost layer is coated with a silicone acrylic resin adhesive. Through a synergistic strategy of hydrophobic modified phosphogypsum, hydrophobic flame retardant compounding, and aerogel reinforcement, a core skeleton with lightweight, heat insulation, flame retardancy, and water resistance is designed. The outer adhesive is a high-temperature resistant and aging-resistant silicone acrylic resin, suitable for building and industrial insulation in extreme environments (such as high humidity and high temperature difference scenarios). The combination of the inner and outer layers synergistically improves the coating's heat insulation, flame retardancy, and high temperature and humidity resistance. It can be used for wall insulation and fireproofing projects in high humidity and large temperature difference scenarios such as building exterior walls, cold storage, corrugated steel roofs, machinery and equipment, chemical plants, underground pipe corridors, and coastal buildings. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 The flowchart illustrates the preparation of a composite hydrophobic phosphogypsum waterborne building insulation coating according to the present invention.

[0028] Figure 2 This is a schematic diagram of the process for preparing composite hydrophobic phosphogypsum waterborne building insulation coating by emulsion polymerization according to the present invention.

[0029] Figure 3 The particle size distribution of the water-based thermal insulation coating obtained in Example 1 is shown in the diagram. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1

[0032] This embodiment describes a method for preparing a composite hydrophobic phosphogypsum water-based building insulation coating, such as... Figure 1 As shown, it includes the following steps:

[0033] (1) Phosphogypsum is washed with lime milk, washed with water, and then dried to obtain pretreated phosphogypsum; the specific method can be found in patent CN103708750A, which will not be elaborated here. The obtained pretreated phosphogypsum meets the grade II or above index of phosphogypsum in GB / T 23456-2018, with calcium sulfate dihydrate on a dry basis ≥80%, P2O5 ≤0.3%, water-soluble fluoride ions ≤0.2%, water-soluble sodium oxide ≤0.1%, and chloride ions ≤0.04%, and can be used as building material gypsum;

[0034] (2) 20g of pretreated phosphogypsum was treated together with silane coupling agent KH550 and solvent by vertical milling / air jet milling. The volume ratio of silane coupling agent to ethanol was 1:7. The phosphogypsum was dried at 70℃ to obtain hydrophobic modified phosphogypsum. The amount of silane coupling agent was 4wt% of the pretreated phosphogypsum. The D50 particle size of the obtained hydrophobic modified phosphogypsum was 300nm.

[0035] (3) The hydrophobic modified phosphogypsum, hydrophobic flame retardant expanded graphite and silica aerogel were mixed in a mass ratio of 4:1.5:1 and then air-milled. 1 wt% of silane coupling agent was added to the material to be milled to obtain composite hydrophobic modified phosphogypsum particles with a particle size of 600 nm.

[0036] (4) A schematic diagram of the process for preparing composite hydrophobic phosphogypsum waterborne building insulation coating by emulsion polymerization is shown below. Figure 2 As shown; the product obtained in step (3) was ultrasonically dispersed and mixed with the monomer of silicone-acrylic resin at a mass ratio of 7:8. The ultrasonic dispersion conditions were 40 kHz for 20 min. Under stirring at 1000 rpm, it was slowly added dropwise to water containing surfactant and co-solvent, and an initiator was slowly added to carry out the polymerization reaction. After the reaction, a water-based emulsion thermal insulation coating of core-shell structured phosphogypsum composite hydrophobic flame retardant was obtained. The solid content of the water-based emulsion was 55 wt%, the particle size of the polymer particles was 3 μm, and the particle size distribution was as shown. Figure 3 As shown.

[0037] The monomers of the silicone-acrylic resin are a mixture of vinyl-terminated silicone oil SHYH-VI401, methyl methacrylate, and lauryl methacrylate in a mass ratio of 3:2:3; the vinyl content of the vinyl-terminated silicone oil is 0.8 wt%; the acrylic monomer emulsifier is a mixture of sodium dodecyl sulfate and fatty alcohol ether phosphate in a mass ratio of 1.5:7; the initiator includes potassium persulfate; and the cosolvent is dipropylene glycol.

[0038] The amounts of the initiator, emulsifier, and cosolvent are 0.5-1.5%, 5-10%, and 3-6% of the total monomer mass of the silicone-acrylic resin, respectively. The polymerization reaction temperature is 55°C and the time is 2 hours. A water-based thermal insulation coating is obtained, wherein the particle size of the polymer microparticle emulsion is 3 μm and the solid content of the water-based emulsion is 55 wt%.

[0039] After the water-based thermal insulation coating film obtained in this embodiment is cured, its performance is tested:

[0040] The water absorption rate of the coating after soaking for 72 hours was 2.8% (test standard ASTM D1653);

[0041] Vertical burning test self-extinguishing time ≤3s, no dripping (UL94 standard);

[0042] The thermal conductivity is 0.043 W / (m·K) (test standard ASTM C518);

[0043] Freeze-thaw resistance of architectural coatings: No powdering, cracking or peeling after 50 cycles at -20℃ to 50℃ (JG / T25-1999).

[0044] Example 2

[0045] This embodiment describes a method for preparing a composite hydrophobic phosphogypsum water-based building thermal insulation coating, comprising the following steps:

[0046] (1) Phosphogypsum is washed with lime milk, washed with water, and then dried to obtain pretreated phosphogypsum; the specific method can be found in patent CN103708750A, which will not be elaborated here. The obtained pretreated phosphogypsum meets the grade II or above index of phosphogypsum in GB / T 23456-2018, with calcium sulfate dihydrate on a dry basis ≥80%, P2O5 ≤0.3%, water-soluble fluoride ions ≤0.2%, water-soluble sodium oxide ≤0.1%, and chloride ions ≤0.04%, and can be used as building material gypsum;

[0047] (2) 20g of pretreated phosphogypsum was treated together with an ethanol solution of silane coupling agent KH560 by vertical milling / air jet milling, with a volume ratio of silane coupling agent to ethanol of 1:6; dried at 60℃ to obtain hydrophobic modified phosphogypsum; the amount of silane coupling agent was 1-6wt% of the pretreated phosphogypsum; the D50 particle size of the obtained hydrophobic modified phosphogypsum was 200nm.

[0048] (3) The hydrophobic modified phosphogypsum, hydrophobic flame retardant expanded graphite and heat insulation material silica aerogel are mixed in a mass ratio of 3:1:1 and then air-milled. 0.5-2% of silane coupling agent is added to the material to be milled to obtain composite hydrophobic modified phosphogypsum particles with a particle size of 500nm.

[0049] (4) The product obtained in step (3) is ultrasonically dispersed and mixed with the monomer of silicone acrylic resin at a mass ratio of 5:7. The ultrasonic dispersion conditions are 30 kHz and 30 min. Under the stirring condition of 1200 rpm, it is slowly added dropwise to water containing surfactant and cosolvent, and the initiator is slowly added to carry out the polymerization reaction at a temperature of 50 ℃ for 3 h. After the reaction, a core-shell structured composite hydrophobic phosphogypsum waterborne building thermal insulation coating is obtained. The solid content of the waterborne emulsion is 50 wt%, and the particle size of the polymer particles is 3 μm.

[0050] The monomers of the silicone-acrylic resin are vinyl-terminated silicone oil SHYH-VI401, a mixture of methyl methacrylate and ethyl methacrylate in a mass ratio of 2:3:3; the vinyl content of the vinyl silicone oil SHYH-VI401 is 0.5 wt%; the emulsifier is sodium dodecyl sulfate and fatty alcohol polyoxyethylene ether in a mass ratio of 1:6; the initiator includes ammonium persulfate; the cosolvent is dipropylene glycol; and the amounts of initiator, emulsifier, and cosolvent are 1%, 5%, and 3% of the total mass of the monomers of the silicone-acrylic resin, respectively.

[0051] Example 3

[0052] This embodiment describes a method for preparing a composite hydrophobic phosphogypsum water-based building thermal insulation coating, comprising the following steps:

[0053] (1) The phosphogypsum is acid-washed, water-washed, dried, and ball-milled to obtain pretreated phosphogypsum; the pretreated phosphogypsum meets or exceeds the grade II index of phosphogypsum in GB / T23456-2018.

[0054] (2) 20g of pretreated phosphogypsum was treated together with an ethanol solution of silane coupling agent KH590 by vertical milling / air jet milling, with a volume ratio of silane coupling agent to ethanol of 1:6; dried at 60℃ to obtain hydrophobic modified phosphogypsum; the amount of silane coupling agent was 1-6wt% of the pretreated phosphogypsum; the D50 particle size of the obtained hydrophobic modified phosphogypsum was 400nm.

[0055] (3) The hydrophobic modified phosphogypsum, hydrophobic flame retardant organosilicon resin and heat insulation material silica aerogel were mixed in a mass ratio of 5:2:1 and then air-milled. 0.5% of silane coupling agent was added to the material to be milled to obtain composite hydrophobic modified phosphogypsum particles with a particle size of 800nm.

[0056] (4) The product obtained in step (3) is ultrasonically dispersed and mixed with the monomer of silicone acrylic resin at a mass ratio of 8:10. The ultrasonic dispersion conditions are 50 kHz for 10 min. Under the stirring condition of 700 r / min, it is slowly added dropwise to water containing surfactant and cosolvent, and the initiator is slowly added to carry out the polymerization reaction at a temperature of 50 °C for 3 h. After the reaction, a core-shell structured composite hydrophobic phosphogypsum waterborne building thermal insulation coating is obtained. The solid content of the waterborne emulsion is 45 wt%, and the particle size of the polymer particles is 5 μm.

[0057] The monomers of the silicone-acrylic resin are a mixture of vinyl-terminated silicone oil KH-Vi series, butyl methacrylate, and 2-ethylhexyl methacrylate in a mass ratio of 3:4:4; the vinyl content of the vinyl-terminated silicone oil KH-Vi series is 1 wt%; the emulsifier is a mixture of sodium dodecylbenzenesulfonate and fatty alcohol ether phosphate in a mass ratio of 1:10; the initiator includes AIBN and BPO; the cosolvent is propylene glycol propyl ether; the amounts of the initiator, emulsifier, and cosolvent are 1.5%, 10%, and 6% of the total mass of the monomers of the silicone-acrylic resin, respectively.

[0058] Example 4

[0059] This embodiment describes a method for preparing a composite hydrophobic phosphogypsum water-based building thermal insulation coating, comprising the following steps:

[0060] (1) The phosphogypsum is acid-washed, water-washed, dried, and ball-milled to obtain pretreated phosphogypsum; the pretreated phosphogypsum meets or exceeds the grade II index of phosphogypsum in GB / T23456-2018.

[0061] (2) 20g of pretreated phosphogypsum was treated together with an ethanol solution of silane coupling agent KH590 by vertical milling / air jet milling, with a volume ratio of silane coupling agent to ethanol of 1:8; dried at 60℃ to obtain hydrophobic modified phosphogypsum; the amount of silane coupling agent was 1-6wt% of the pretreated phosphogypsum; the D50 particle size of the obtained hydrophobic modified phosphogypsum was 200nm.

[0062] (3) The hydrophobic modified phosphogypsum, hydrophobic flame retardant expanded graphite and heat insulation material silica aerogel were mixed in a mass ratio of 4:2:1 and then air-milled. 2% of silane coupling agent was added to the material to be milled to obtain composite hydrophobic modified phosphogypsum particles with a particle size of 400nm.

[0063] (4) The product obtained in step (3) is ultrasonically dispersed and mixed with the monomer of silicone acrylic resin at a mass ratio of 7:9. The ultrasonic dispersion conditions are 50 kHz and 10 min. Under the stirring condition of 900 r / min, it is slowly added dropwise to water containing surfactant and cosolvent, and the initiator is slowly added to carry out the polymerization reaction at a temperature of 50-60℃ for 1-3 h. After the reaction, a core-shell structured composite hydrophobic phosphogypsum waterborne building thermal insulation coating is obtained. The solid content of the waterborne emulsion is 60 wt%, and the particle size of the polymer particles is 1 μm.

[0064] The monomers of the silicone-acrylic resin are a mixture of vinyl-terminated silicone oil SHYH-VI401 and tert-butyl methacrylate and isobutyl methacrylate in a mass ratio of 2:3:4; the vinyl content of the vinyl-terminated silicone oil SHYH-VI401 is 0.1-1 wt%; the emulsifier is a mixture of sodium dodecyl sulfate and fatty alcohol polyoxyethylene ether in a 2:7 ratio; the initiator includes AIBN; the cosolvent is dipropylene glycol; and the amounts of initiator, emulsifier, and cosolvent are 1%, 5%, and 3% of the total mass of the monomers of the silicone-acrylic resin, respectively.

[0065] Example 5

[0066] This embodiment describes a method for preparing a composite hydrophobic phosphogypsum water-based building thermal insulation coating, comprising the following steps:

[0067] (1) The phosphogypsum is acid-washed, water-washed, dried, and ball-milled to obtain pretreated phosphogypsum; the pretreated phosphogypsum meets or exceeds the grade II index of phosphogypsum in GB / T23456-2018.

[0068] (2) 20g of pretreated phosphogypsum was treated together with an ethanol solution of stearic acid by vertical milling / air jet milling, with a volume ratio of stearic acid to ethanol of 1:6-8; dried at 60℃ to obtain hydrophobic modified phosphogypsum; the amount of stearic acid used was 1-6wt% of the pretreated phosphogypsum; the D50 particle size of the obtained hydrophobic modified phosphogypsum was 200-400nm.

[0069] (3) The hydrophobic modified phosphogypsum, hydrophobic flame retardant expanded graphite and heat insulation material silica aerogel are mixed in a mass ratio of 3:1:1 and then air-milled. 0.5-2% of silane coupling agent is added to the material to be milled to obtain composite hydrophobic modified phosphogypsum particles with a particle size of 800nm.

[0070] (4) The product obtained in step (3) is ultrasonically dispersed and mixed with the monomer of silicone acrylic resin at a mass ratio of 5:7. The ultrasonic dispersion conditions are 30 kHz and 30 min. Under the stirring condition of 800 rpm, it is slowly added dropwise to water containing surfactant, cosolvent and excipient titanium dioxide, and the initiator is slowly added to carry out the polymerization reaction. The polymerization reaction temperature is 55℃ and the time is 2 h. After the reaction, core-shell structured composite hydrophobic phosphogypsum waterborne building thermal insulation coating latex particles are obtained. The solid content of the waterborne emulsion is 40 wt%, and the particle size of the polymer particles is 5 μm.

[0071] The monomers of the silicone-acrylic resin are vinyl-terminated silicone oil SHYH-VI401, acrylic monomers isobornyl methacrylate and lauryl methacrylate in a mass ratio of 1:3:3; the vinyl content of the vinyl-terminated silicone oil SHYH-VI401 is 0.5wt%; the emulsifier is a mixture of sodium dodecyl sulfate and fatty alcohol ether phosphate in a mass ratio of 1:6; the initiator is ammonium persulfate; the cosolvent is propylene glycol propyl ether; and the amounts of the initiator, emulsifier, cosolvent, and excipients are 1%, 5%, 3%, and 2% of the total mass of the monomers of the silicone-acrylic resin, respectively.

[0072] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A composite hydrophobic phosphogypsum water-based building insulation coating, characterized in that, The water-based building insulation coating is a water-based emulsion, wherein the water-based emulsion consists of polymer microparticles with a core layer and a shell layer structure dispersed in water. The core layer structure includes hydrophobically modified phosphogypsum, hydrophobic flame retardant, and silica aerogel; the shell layer structure is a silicone-acrylic resin adhesive; the mass ratio of the core layer to the shell layer of the polymer microparticles is 5-8:7-10; and the hydrophobic flame retardant is expanded graphite and / or organosilicon resin. The preparation method of the hydrophobically modified phosphogypsum includes the following steps: 1) Remove impurities from phosphogypsum to obtain pretreated phosphogypsum; 2) The pretreated phosphogypsum is treated together with a surface modifier and a solvent by vertical milling / air jet milling and then dried to obtain hydrophobic modified phosphogypsum; the surface modifier is a silane coupling agent, stearic acid or an organic carboxylate. The monomers of the silicone-acrylic resin are organosilicon monomers containing unsaturated double bonds and acrylic monomers; the organosilicon monomers containing unsaturated double bonds are vinyl-terminated silicone oils SHYH-VI401 or KH-Vi series; and the acrylic monomers are any one or more of methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, tert-butyl methacrylate, isobutyl methacrylate, isobornyl methacrylate, or lauryl methacrylate. The mass ratio of organosilicon monomers containing unsaturated double bonds to acrylic monomers is 1-3:6-8.

2. The composite hydrophobic phosphogypsum water-based building insulation coating according to claim 1, characterized in that: The polymer microparticles have a particle size of 1-5 μm; the solid content of the aqueous emulsion is 40-60 wt%; and the mass ratio of the core layer hydrophobic modified phosphogypsum, hydrophobic flame retardant and silica aerogel is 3-5:1-2:

1.

3. The composite hydrophobic phosphogypsum water-based building insulation coating according to claim 1, characterized in that, The pretreated phosphogypsum in step 1) meets the grade II or above index of phosphogypsum in GB / T 23456-2018; the D50 particle size of the hydrophobic modified phosphogypsum after treatment by vertical mill / air jet mill in step 2) is 200-400nm.

4. The composite hydrophobic phosphogypsum water-based building insulation coating according to claim 3, characterized in that: The amount of surface modifier used in step 2) is 1-6 wt% of the pretreated phosphogypsum; the mass ratio of surface modifier to solvent is 1:6-8; the solvent is ethanol; the drying temperature is 60-80℃; and the silane coupling agent is KH550, KH570, KH560 or KH590.

5. The composite hydrophobic phosphogypsum water-based building insulation coating according to any one of claims 1-4, characterized in that: The volume-to-mass ratio of the expanded graphite is 300-400 mL / g; the thermal insulation coating also contains auxiliary materials, which are at least one of nano-titanium dioxide and anti-aging agent; the amount of auxiliary materials added is 1-3 wt% of silicone-acrylic resin.

6. The preparation method of the composite hydrophobic phosphogypsum water-based building thermal insulation coating according to any one of claims 1-5, characterized in that: Includes the following steps: (1) Hydrophobic modified phosphogypsum, hydrophobic flame retardant and silica aerogel were vertically milled / air-flow milled to obtain composite hydrophobic modified phosphogypsum particles; (2) The product obtained in step (1) is ultrasonically dispersed and mixed with the monomer of silicone acrylic resin. Under stirring conditions, it is slowly added dropwise to water containing emulsifier and cosolvent. Then, an initiator is slowly added to carry out the polymerization reaction. After the reaction, a thermal insulation coating containing phosphogypsum composite hydrophobic flame retardant polymer particles with core-shell structure is obtained.

7. The preparation method of the composite hydrophobic phosphogypsum water-based building thermal insulation coating according to claim 6, characterized in that: In step (1), the particle size of the composite hydrophobic modified phosphogypsum particles after vertical milling / air jet milling is 400nm-800nm; the ultrasonic dispersion conditions are 30-50kHz, 10-30min.

8. The preparation method of the composite hydrophobic phosphogypsum water-based building thermal insulation coating according to claim 6, characterized in that: In step (2), the emulsifier includes anionic emulsifier and nonionic emulsifier. The anionic emulsifier is sodium dodecyl sulfate or sodium dodecylbenzene sulfonate; the nonionic emulsifier is fatty alcohol polyoxyethylene ether or fatty alcohol ether phosphate; the initiator includes AIBN, BPO or ammonium persulfate; and the cosolvent is dipropylene glycol or propylene glycol propyl ether.

9. The preparation method of the composite hydrophobic phosphogypsum water-based building thermal insulation coating according to claim 6, characterized in that: In step (2), the amounts of initiator, emulsifier, and cosolvent are 0.5-1.5%, 5-10%, and 3-6% of the total mass of the monomers of silicone-acrylic resin, respectively; the mass ratio of anionic emulsifier to nonionic emulsifier is 1-2:6-10; the polymerization reaction temperature is 50-60℃ and the time is 1-3h; the vinyl content is 0.5-1wt%.

Images