Microporous noise reduction aerogel coating material

Abstract

The microporous noise-reducing aerogel coating material is prepared from the following raw materials in parts by weight: 100 to 110 parts of tetraethoxysilane, 1 to 2.5 parts of hydrophilic emulsifier, 5 to 10 parts of pore-foaming agent, 0.5 to 2 parts of initiator, 30 to 40 parts of functional monomer, 5 to 10 parts of cross-linking agent and 2 to 3 parts of lipophilic emulsifier. According to the invention, a hierarchical pore structure from micron to nanoscale is constructed in situ through a one-step method. In the gelation and drying processes, the interface of the emulsion drops is used as a template to guide and form a macroporous skeleton; meanwhile, through a sol-gel process of a silicon source and volatile / reactive pore forming of an organic phase, mesoporous and microporous structures are formed in pore walls. And finally, a three-dimensional through'macropore-mesopore-micropore 'hierarchical pore structure is formed.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of environmental protection materials, in particular to a microporous noise reduction aerogel coating material. BACKGROUND

[0002] Porous materials, as a kind of material with unique structure and functional characteristics, have shown wide application prospects in many fields such as adsorption and separation, catalysis, sensing, energy storage and conversion, biomedical engineering and environmental science. Among them, aerogel materials have attracted much attention due to their high porosity, high specific surface area and low thermal conductivity. Although traditional silicate aerogel materials have excellent performance, their inherent brittleness and complex preparation process seriously limit their application in the field of coating.

[0003] In order to overcome these limitations, researchers have developed various methods to prepare polymer and composite materials with hierarchical pore structure. At present, the double emulsion template method provides a way to prepare porous or hollow polymer microspheres, although this method can prepare more complex pore structure, but it usually faces the problems of poor stability, the need for a large amount of emulsifier, difficulty in accurate control of pore structure and possible use of organic solvents.

[0004] Therefore, it is of great significance and necessity to develop a new method that can accurately control the hierarchical pore structure, has a simple and environmentally friendly process, is suitable for coating preparation and can achieve excellent noise reduction performance. SUMMARY

[0005] The purpose of the present application is to provide a microporous noise reduction aerogel coating material.

[0006] To achieve the above purpose, the technical scheme adopted by the present application is as follows: Silicate 100-110, hydrophilic emulsifier 1-2.5, porogen 5-10, initiator 0.5-2, functional monomer 30-40, crosslinking agent 5-10, lipophilic emulsifier 2-3.

[0007] The hydrophilic emulsifier is hexadecyl trimethyl ammonium bromide, the lipophilic emulsifier is Span-80, the porogen is n-hexane, the initiator is ammonium persulfate, the functional monomer is methyl trimethoxysilane, and the crosslinking agent is divinylbenzene.

[0008] The preparation method of the coating material comprises the following steps: (1) Water phase configuration: mix the hydrophilic emulsifier and the initiator, add 200-300 times of deionized water, stir uniformly, add hydrochloric acid, adjust the pH to 2-3, slowly drop the tetraethyl orthosilicate under stirring, continue to react at 60-70℃ for 3-5h, and obtain an acidic silica sol prepolymer solution; (2) Oil phase configuration: mixing pore-forming agent, functional monomer, crosslinking agent, and lipophilic emulsifier, and stirring uniformly; (3) Preparation of primary emulsion: under the condition of high-speed shearing of 10000-15000 rpm, slowly adding the above oil phase into 30-35% by weight of the aqueous phase, and continuously shearing for 5-10 minutes; (4) Preparation of double emulsion: under the condition of low-speed stirring of 500-1000 rpm, slowly adding the above primary emulsion into the remaining aqueous phase, and stirring for 10-20 minutes; (5) Coating: applying the above double emulsion to the substrate by means of blade coating or spray coating, and transferring the coated substrate to a constant-temperature environment at 40-60°C, and reacting for 4-12 hours; (6) Aging: placing the coated substrate in a hexane solution containing trimethylchlorosilane, and aging at room temperature for 20-30 hours; (7) Drying: washing the aged coating with n-hexane, and placing it in a blast drying oven for drying at 60-80°C under normal pressure until constant weight.

[0009] The volume ratio of trimethylchlorosilane to hexane is 1:10-15.

[0010] The substrate is an aluminum alloy, a stone, or a ceramic matrix composite.

[0011] The coating material is particularly suitable for use in aerospace thermal and acoustic insulation components, acoustic wallboards, ceilings, and pipe wells in the field of building.

[0012] The present application adopts a unique silica sol-polymer double-phase composite emulsion system as a pore-forming template, wherein the aqueous phase is a silicate prepolymer solution under acidic catalysis, and the oil phase contains hydrophobic functional monomers, etc., and the emulsification process is optimized to form an extremely stable O / W emulsion template; Unlike the traditional method of using a single emulsifier (such as Span 80), the present application significantly improves the stability of the emulsion through the synergistic effect of the composite emulsion system, and this stability ensures the integrity of the template structure in the subsequent gelation process, laying a foundation for replicating precise multi-level pore structures; Through the hydrophobic modification in the aging process, the hydrophilic Si-OH groups in the gel network are replaced by hydrophobic Si-CH groups. The greatest progress of the present application lies in the ability to construct multi-level pore structures from microns to nanometers in situ by a one-step method. During the gelation and drying process, the interface of the emulsion droplets serves as a template to guide the formation of a macroporous skeleton; at the same time, the sol-gel process of the silicon source and the organic phase form mesoporous and microporous structures inside the pore wall. Finally, a three-dimensional through "macropore-mesopore-micropore" multi-level pore structure is formed. DETAILED DESCRIPTION Embodiment

[0013] A microporous noise reduction aerogel coating material, comprising the following raw materials in parts by weight: Ethyl silicate 100, cetyltrimethylammonium bromide 1, n-hexane 5, ammonium persulfate 0.5, methyltrimethoxysilane 30, divinylbenzene 5, Span-80 3.

[0014] The preparation method of the coating material comprises the following steps: (1) Water phase configuration: mix cetyltrimethylammonium bromide and ammonium persulfate, add 200-300 times of deionized water, stir uniformly, add hydrochloric acid, adjust the pH to 2, slowly add tetraethyl orthosilicate under stirring, continue to react at 60°C for 3h, and obtain an acidic silica sol prepolymer solution; (2) Oil phase configuration: mix n-hexane, methyltrimethoxysilane, divinylbenzene and Span-80, and stir uniformly; (3) Preparation of primary emulsion: slowly add the above oil phase to 30-35% by weight of the water phase under high-speed shearing at 10000 rpm, and continue to shear for 5 minutes; (4) Preparation of double emulsion: slowly add the above primary emulsion to the remaining water phase under low-speed stirring at 500 rpm, and stir for 10 minutes; (5) Coating: apply the above double emulsion to an aluminum alloy substrate by means of scraping or spraying, transfer the coated substrate to a constant temperature environment at 40°C, and react for 4 hours; (6) Aging: place the coated substrate in a hexane solution containing trimethylchlorosilane, and age at room temperature for 20 hours; (7) Drying: rinse the aged coating with n-hexane, and place it in a forced air drying oven at 60°C for drying to constant weight under normal pressure.

[0015] The volume ratio of trimethylchlorosilane to hexane is 1:10. Embodiment

[0016] A microporous noise reduction aerogel coating material, comprising the following raw materials in parts by weight: Ethyl silicate 110, cetyltrimethylammonium bromide 2.5, n-hexane 10, ammonium persulfate 2, methyltrimethoxysilane 40, divinylbenzene 10, Span-80 2.

[0017] The preparation method of the coating material comprises the following steps: (1) Water phase configuration: Mix cetyltrimethylammonium bromide and ammonium persulfate, add 300 times of deionized water, stir uniformly, add hydrochloric acid, adjust pH to 3, slowly add tetraethyl orthosilicate under stirring, continue to react at 70°C for 5h to obtain an acidic silica sol prepolymer solution; (2) Oil phase configuration: Mix n-hexane, methyltrimethoxysilane, divinylbenzene, Span-80 and stir uniformly; (3) Preparation of primary emulsion: Slowly add the above oil phase to 35% by weight of the water phase under high-speed shearing at 15000 rpm, and continue to shear for 10 minutes; (4) Preparation of double emulsion: Slowly add the above primary emulsion to the remaining water phase under low-speed stirring at 1000 rpm, and stir for 20 minutes; (5) Coating: Apply the above double emulsion to an aluminum alloy substrate by means of scraping or spraying, and transfer the coated substrate to a constant temperature environment at 60°C for 12 hours of reaction; (6) Aging: Place the coated substrate in a hexane solution containing trimethylchlorosilane and age at room temperature for 30 hours; (7) Drying: Rinse the aged coating with n-hexane and place it in a forced air drying oven at 60-80°C under normal pressure until constant weight is achieved.

[0018] The volume ratio of trimethylchlorosilane to hexane is 1:15. Control group 1: Traditional silica-based aerogel, sol coating prepared with tetraethyl orthosilicate as a single silicon source. Control group 2: The formulation includes: Tetraethyl orthosilicate 100 parts, potassium persulfate 1-2 parts, styrene 130-15 parts, divinylbenzene 10-15 parts, Span 80 3-5 parts; (1) Under low-speed stirring at 500-1000 rpm, slowly add the water phase (containing potassium persulfate and tetraethyl orthosilicate in water) to the oil phase (containing styrene, divinylbenzene, and Span 80), and maintain stirring until a uniform, viscous emulsion is formed; (2) Polymerization reaction: Transfer the prepared HIPE emulsion to a specific mold and place it in an oven at 60-70°C for 24-48 hours of reaction to completely polymerize the oil phase monomers; (3) Remove the polymerized block from the mold and soak it in ethanol for 3-5 days, replacing the ethanol daily to completely remove moisture and unreacted monomers; (4) Dry. Mechanical property testing is as follows: Performance Indicators Example 1 of the Invention Example 2 of the Invention Control 1 Control 2 Adhesion ASTM D3359 (Crosshatch Method) 5B 5B 0 3 Flexibility (mandrel bend test) No cracks, no flaking No cracks, no flaking Coating shows significant cracking Coating shows slight, but noticeable cracking Nanoindentation Hardness (H) 0.51 GPa 0.58 GPa 0.79 GPa 0.26 GPa Nanoindentation Modulus (E) 7.5 GPa 8.0 GPa 11.5 GPa 4.5 GPa Acoustic performance was tested as follows: Frequency (Hz) Example 1 of the Invention Absorption Coefficient (a) Example 2 of the Invention Absorption Coefficient (a) Control 1 Absorption Coefficient (a) Control 2 Absorption Coefficient (a) 500 0.57 0.44 0.13 0.29 2000 0.88 0.80 0.29 0.61 4000 0.87 0.80 0.45 0.65 The substrate used for the test was an aluminum alloy substrate: dimensions: 150 mm x 150 mm x 1 mm.

Claims

1. A microporous noise-reducing aerogel coating material, characterized in that, The coating material comprises the following raw materials in the following weight parts: tetraethyl orthosilicate 100-110, hydrophilic emulsifier 1-2.5, porogen 5-10, initiator 0.5-2, functional monomer 30-40, crosslinking agent 5-10, lipophilic emulsifier 2-3.

2. The microcellular noise reducing aerogel coating material of claim 1, wherein, The hydrophilic emulsifier is cetyltrimethylammonium bromide, the lipophilic emulsifier is Span-80, the porogen is n-hexane, the initiator is ammonium persulfate, the functional monomer is methyltrimethoxysilane, and the crosslinking agent is divinylbenzene.

3. The micro-porous noise reducing aerogel coating material of claim 1, wherein, The preparation method of the coating material comprises the following steps: (1) water phase configuration: mix the hydrophilic emulsifier and the initiator, add 200-300 times of deionized water, stir uniformly, add hydrochloric acid, adjust the pH to 2-3, slowly drop the tetraethyl orthosilicate under stirring, continue to react at 60-70°C for 3-5h, and obtain an acidic silica sol prepolymer solution; (2) oil phase configuration: mix the porogen, the functional monomer, the crosslinking agent, and the lipophilic emulsifier, and stir uniformly; (3) preparation of primary emulsion: slowly drop the above-mentioned oil phase into 30-35% by weight of the water phase under high-speed shearing of 10000-15000 rpm, and continue to shear for 5-10 minutes; (4) preparation of double emulsion: slowly add the above-mentioned primary emulsion into the remaining water phase under low-speed stirring of 500-1000 rpm, and stir for 10-20 minutes; (5) coating: apply the above-mentioned double emulsion to the substrate by means of scraping or spraying, transfer the coated substrate to a constant temperature environment at 40-60°C, and react for 4-12 hours; (6) aging: place the coated substrate in a hexane solution containing trimethylchlorosilane, and age at room temperature for 20-30 hours; (7) drying: rinse the aged coating with n-hexane, and place it in a blast drying oven, dry at 60-80°C under normal pressure until constant weight.

4. A microporous, noise-reducing aerogel coating material according to claim 3, wherein, The volume ratio of trimethylchlorosilane to hexane is 1:10-15.

5. A microporous, noise-reducing aerogel coating material according to claim 3, wherein, The substrate is an aluminum alloy, a stone material, or a ceramic matrix composite material.

6. The micro-porous noise reducing aerogel coating material of claim 1, wherein, The coating material is particularly suitable for aerospace thermal and acoustic insulation components, acoustic insulation wallboards, ceilings, and pipe wells in the field of building. The coating material is particularly suitable for aerospace thermal and acoustic insulation components, acoustic insulation wallboards, ceilings, and pipe wells in the field of building.