Method of Manufacturing of Aerogel Composites

Abstract

Aerogel composite materials having a lofty fibrous batting reinforcement preferably in combination with one or both of individual short randomly oriented microfibers and conductive layers exhibit improved performance in one or all of flexibility, drape, durability, resistance to sintering, x-y thermal conductivity, x-y electrical conductivity, RFI-EMI attenuation, and/or burn-through resistance.

1 - 10 . (canceled) 
   
   
       11 . A method of preparing a composite article, which comprises:
 mixing a gel precursor to a lofty fibrous batting to form a mixture;   transitioning the mixture from sol state to gel state to obtain a gel; and   drying the gel to obtain the article wherein a continuous aerogel is through the batting.   
   
   
       12 . The method of claim  1  wherein the gel precursor is obtained by acidifying a water soluble, basic metal oxide precursor in water and optionally removing any salt by-products. 
   
   
       13 . The method of claim  1  wherein the gel precursor is obtained from the group consisting of oxides of silicon, aluminum, titanium, zirconium, hafnium, yttrium, vanadium and a combination thereof. 
   
   
       14 . The method of claim  1  wherein the gel precursor is obtained from the group consisting of tetraethoxysilane, tetramethoxysilane, tetra-n-propoxy-silane, aluminum isopropoxide, aluminum sec-butoxide, cerium isopropoxide, hafnium tert-butoxide, magnesium aluminum isopropoxide, yttrium isopropoxide, titanium isopropoxide and zirconium isopropoxide. 
   
   
       15 . The method of claim  1  wherein the gel precursor is a hydrolyzed or partially hydrolyzed silica precursor. 
   
   
       16 . The method of claim  1  wherein the gel precursor is obtained from the group consisting of polyacrylates, polystyrenes, polyacrylonitriles, polyurethanes, polyimides, polyfurfural alcohol, phenol furfural alcohol, melamine formaldehyde, resorcinol formaldehyde, cresol formaldehyde, phenol formaldehyde, polyvinyl alcohol dialdehyde, polycyanurates, polyacrylamides, epoxies, agar, agarose and a combination thereof. 
   
   
       17 . The method of claim  1  wherein the density of the batting is between 0.001 to 0.26 g/cc. 
   
   
       18 . The method of claim  1  further comprising the step of mixing microfibers with the gel precursor. 
   
   
       19 . The method of claim  1  wherein the batting may be formed from the group consisting of fiberglass, quartz, polyester, polyethylene, polypropylene, polybenzimidazole, polyphenylenebenzo-bisoxasole, polyetheretherketone, polyarylate, polyacrylate, polytetrafluoroethylene, poly-metaphenylene diamine, poly-paraphenylene terephthalamide, ultra high molecular weight polyethylene, novoloid resins, polyacrylonitrile, polyacrylonitrile/carbon and carbon. 
   
   
       20 . The method of claim  1  further comprising the step of modification of the surface of the gels. 
   
   
       21 . The method of claim  10  wherein surface hydroxyl groups of the gel are converted to tri-methylsilylethers. 
   
   
       22 . The method of claim  2  wherein the water is exchanged with a polar solvent. 
   
   
       23 . The method of claim  1  wherein the gel is dried by supercritical extraction. 
   
   
       24 . The method of  claim 12  wherein the gel is dried below the critical point of the solvent. 
   
   
       25 . The method of claim  10  wherein the gel is dried below the critical point of the solvent. 
   
   
       26 . The method of claim  1  wherein the batting comprising a conductive layer. 
   
   
       27 . The method of claim  1  wherein the batting comprising a metal. 
   
   
       28 . The method of claim  1  further comprising the step of adding dopants to the mixture. 
   
   
       29 . The method of  claim 18  wherein the dopants are selected from the group consisting of carbon black, titania, iron oxides, silicon carbide, molybdenum silicide, manganese oxides and polydialkylsiloxanes. 
   
   
       30 . The method of claim  1  wherein the mixing is performed in a solvent selected from the group consisting of lower alcohols with 1 to 6 carbons, ethyl acetate, ethyl acetoacetate, acetone, dichloromethane and the like.