Sound absorption panel and method of making

Claim 1

A method of making a sound absorption panel comprising, assembling a substantially planar sandwich structure of two fiberglass pelts, two non-porous thermoplastic sheets and a paper honeycomb core in the sequence pelt-sheet-core-sheet-pelt; said assembled pelts each having a density in the range of about twelve to about forty Kg/m 3 and incorporating about sixteen to about twenty-five percent by weight of phenolic resin; said assembled sheets being selected from the group consisting of polypropylene, polyethylene, polyvinylchloride, and polyvinylacetate and having a thickness in the range of about 0.013 mm to about 0.102 mm and the assembled honeycomb structure having a thickness in the range of about twenty-five to thirty-eight mm and with the cells of the honeycomb oriented perpendicular to the plane of the sheets; arranging the pelts, sheets and core to have substantially coextensive peripheries and between a pair of planar presses, moving the presses toward each other to compress the pelts to no more than about one-fourth their original thickness without compressing the core, stopping the movement of the presses by means unrelated to the resistance force of the sandwich structure, heating the presses to a temperature of about 450° F. for a period of about one and one-half to about three and one-half minutes to (1) cause the phenolic resin to hold the fibers of the pelts in the compressed condition and (2) melt the thermoplastic and thereby allow passage of gases from the cells of the honeycomb through the pelts; cooling the sandwich to freeze the melted thermoplastic and thereby bond the pelts to the core.

Claim 2

A method of making a sound absorption panel comprising, assembling a substantially planar sandwich structure of two fiberglass pelts, two non-porous thermoplastic sheets and a paper honeycomb core in the sequence pelt-sheet-core-sheet-pelt; said assembled pelts each having a density in the range of about twelve to about forty Kg/m 3 and incorporating about sixteen to about twenty-five percent by weight of phenolic resin; said assembled sheets being selected from the group consisting of polypropylene, polyethylene, polyvinylchloride, and polyvinylacetate and having a thickness in the range of about 0.013 mm to about 0.102 mm and the assembled honeycomb structure having a thickness in the range of about twenty-five to thirty-eight mm and with the cells of the honeycomb oriented perpendicular to the plane of the sheets; arranging the pelts, sheets and core to have substantially coextensive peripheries and between a pair of planar presses, moving the presses toward each other to compress the pelts to no more than about one-fourth their original thickness without compressing the core, stopping the movement of the presses by means unrelated to the resistance force of the sandwich structure, heating the presses to a temperature of about 450° F. for a period of about one and one-half to about three and one-half minutes to (1) cause the phenolic resin to hold the fibers of the pelts in the compressed condition and (2) melt the thermoplastic and thereby allow passage of gases from the cells of the honeycomb through the pelts; cooling the sandwich to freeze the melted thermoplastic and thereby bond the pelts to the core.