Closed-cell tannin-based foams
View Patent ↗Disclosed are foam compositions and processes to form closed-cell tannin-based foams. The foams comprises a continuous polymeric phase defining a plurality of cells, wherein the continuous polymeric phase comprises a tannin-based resin derived from a tannin, a first monomer, and a second monomer, wherein the first monomer comprises formaldehyde, paraformaldehyde, furfural, glyoxal, acetaldehyde, 5-hydroxymethylfurfural, acrolein, levulinate esters, sugars, 2,5-furandicarboxylic acid, 2,5-furandicarboxylic aldehyde, urea, difurfural (DFF), or mixtures thereof, and the second monomer comprises furfuryl alcohol, glycerol, sorbitol, lignin, or mixtures thereof, and wherein the plurality of cells comprises a plurality of open-cells and a plurality of closed-cells with an open-cell content measured according to ASTM D6226-5, of less than 50%. The foam composition also comprises a discontinuous phase disposed in at least a portion of the plurality of closed-cells, the discontinuous phase comprising one or more blowing agents.
1. A foam consisting of:
(a) a continuous polymeric phase defining a plurality of cells, wherein:
the continuous polymeric phase consists of co-reacting components a tannin-based resin derived from a tannin, a furfuryl alcohol, and a first monomer, wherein the first monomer comprises formaldehyde, paraformaldehyde, furfural, glyoxal, acetaldehyde, 5-hydroxymethylfurfural, acrolein, levulinate esters, sugars, 2,5-furandicarboxylic acid, 2,5-furandicarboxylic aldehyde, urea, difurfural (DFF), or mixtures thereof, and
the plurality of cells comprises a plurality of open-cells and a plurality of closed-cells with an open-cell content measured according to ASTM 6226-5, of less than 40%; and
(b) a gas phase comprising one or more blowing agents disposed in at least a portion of the plurality of closed-cells.
2. The foam of claim 1 , wherein the tannin-based resin is derived from a tannin, a first monomer, and furfuryl alcohol present as reactants in a weight ratio in the range of 1:0.01:0.1 to 1:2:5.
3. The foam of claim 1 , wherein the open-cell content measured according to ASTM D6226-5, is less than 20%.
4. The foam of claim 1 , wherein the open-cell content measured according to ASTM D6226-5, is less than 30%.
5. The foam of claim 1 , wherein the foam has a density in the range of 10-500 kg/m 3 .
6. The foam of claim 1 , wherein the foam has a density in the range of 20-100 kg/m 3 .
7. The foam of claim 1 , wherein the cell has an average size of less than 500 microns.
8. The foam of claim 1 , wherein at least one of the one or more blowing agents has a gas phase thermal conductivity of less than or equal to 0.016 W/m·K at 25° C.
9. The foam of claim 1 , wherein at least one of the one or more blowing agents comprises 1,1,1,4,4,4-hexafluoro-2-butene, carbon dioxide, pentane, isopentane, cyclopentane petroleum ether, ether, 1,1-dichloro-1-fluoroethane, 2,2-dichloro-1,1,1-trifluoroethane, 1-chloro-1,1-difluoroethane, 1,1,1,2-tetrafluoroethane, 1,1,1,3,3-pentafluoropropane, 1,1,1,3,3-pentafluorobutane, 2-chloropropane, dichlorodifluoromethane, 1,2-dichloro-1,1,2,2-tetrafluoroethane, trichlorotrifluoroethane, trichloromonofluoromethane, or mixtures thereof.
10. The foam of claim 1 , wherein the foam has a thermal conductivity in the range of 0.015-0.050 W/m·K.
11. The foam of claim 1 , wherein the continuous polymeric phase further comprises one or more additives.
12. The foam of claim 11 , wherein the one or more additives comprises cellulose fiber, bacterial cellulose, sisal fiber, clays, Kaolin-type clay, mica, vermiculite, sepiolite, hydrotalcite and other inorganic platelet materials, glass fibers, polymeric fibers, alumina fibers, aluminosilicate fibers, carbon fibers, carbon nanofibers, poly-1,3-glucan, lyocel fibers, chitosan, boehmite (AlO.OH), zirconium oxide, a polyester polyol, or mixtures thereof.
13. The foam of claim 1 , wherein the tannin is derived from mimosa, acacia, quebracho, pine, spruce, fir, tanoak, oak, birch, maple, eucalyptus, tara, catechu, or mixtures thereof.
14. The foam of claim 1 , wherein the foam has a limiting oxygen index (LOI) of at least 23, measured according to ASTM-D2863.
15. An article comprising the foam of claim 1 .
16. The article of claim 15 comprising a sandwich panel structure, wherein the sandwich panel structure comprises the foam disposed between two similar or dissimilar non-foam materials.
17. The article of claim 16 wherein the non-foam material comprises polymeric fibers.