Thermoformable acoustic sheet

Abstract

A thermoformable acoustic sheet formed by a compressed fibrous web includes high melt fibres and adhesive thermoplastic fibres in which the adhesive fibres are at least partially melted so that in the compressed web the adhesive fibres at least partially coat the high melt fibres and reduce the interstitial space in the fibre matrix. Also included are methods of producing a thermoformable acoustic sheet which includes heating a fibre web including high melt and adhesive thermoplastic fibres to at least partially melt the adhesive fibres and compressing the web to form a sheet so that the adhesive fibres at least partially coat the high melt fibres to reduce the interstitial space in the fibre matrix.

1 - 25 . (canceled) 
     
     
         26 . A method of producing a thermoformable acoustic sheet including the steps of heating a fibre web including high melt and adhesive thermoplastic fibres to at least partially melt the adhesive fibres and compressing the web to form a sheet so that the adhesive fibres at least partially coat the high melt fibres and reduce the interstitial space in the fibre matrix. 
     
     
         27 . A method of producing a thermoformable acoustic sheet according to  claim 26  wherein the thermoplastic fibres are treated with an adhesive coating to increase the air flow resistance. 
     
     
         28 . A method of producing a thermoformable acoustic sheet according to  claim 27  wherein the adhesive coating is applied as a powder at a rate of from 10 to 80 g/m 2 . 
     
     
         29 . A method of producing a thermoformable acoustic sheet according to  claim 26  wherein the thermoplastic fibres are treated with a coating formed by one or more further webs of thermoplastic fibres. 
     
     
         30 . A method of producing a thermoformable acoustic sheet according to  claim 27  wherein the fibre web including high melt and adhesive thermoplastic fibres and the coating formed by one or more further webs of thermoplastic fibres are compressed concurrently. 
     
     
         31 . A method of producing a thermoformable acoustic sheet according to  claim 26  wherein the sheet has a total air flow resistance between 275 and 1100 mks Rayls. 
     
     
         32 . A method of producing a thermoformable acoustic sheet according to  claim 31  wherein the sheet has a total air flow resistance between 600 and 1100 mks Rayls. 
     
     
         33 . A method of producing a thermoformable acoustic sheet according to  claim 32  wherein the sheet has a total air flow resistance between 900 and 1000 mks Rayls. 
     
     
         34 . A method of producing a thermoformable acoustic sheet according to  claim 26  wherein the sheet has a low sag modulus at temperatures up to 150° C. 
     
     
         35 . A method of producing a thermoformable acoustic sheet according to  claim 26 , wherein the high melt fibre has a melting point above about 220° C. 
     
     
         36 . A method of producing a thermoformable acoustic sheet according to  claim 26 , wherein the adhesive fibre has a melting point between 100 and 160° C. 
     
     
         37 . A method of producing a thermoformable acoustic sheet according to  claim 36  wherein the adhesive fibre has a melting point between 120 and 150° C. 
     
     
         38 . A method of producing a thermoformable acoustic sheet according to  claim 37  wherein the adhesive fibre has a melting point between 135 and 145° C. 
     
     
         39 . A method of producing a thermoformable acoustic sheet according to claim  2  wherein the high melt fibres are about 6 denier or below. 
     
     
         40 . A method of producing a thermoformable acoustic sheet according to  claim 39  wherein the high melt fibres are about 4 denier or below. 
     
     
         41 . A method of producing a thermoformable acoustic sheet according to  claim 26  wherein the adhesive fibres are about 6 denier or below. 
     
     
         42 . A method of producing a thermoformable acoustic sheet according to  claim 41  wherein the adhesive fibres are about 4 denier or below. 
     
     
         43 . A method of producing a thermoformable acoustic sheet according to  claim 42  wherein the adhesive fibres are about 2 denier. 
     
     
         44 . A method of producing a thermoformable acoustic sheet according to  claim 26  wherein the web of thermoplastic fibres is produced from non-woven vertically aligned high loft thermally bonded fibres. 
     
     
         45 . A method of producing a thermoformable acoustic sheet according to  claim 26  wherein the thermoplastic fibres are selected from polyethylene terephthalate (PET), polyethylene butylphthalate (PBT), polyethylene 1,4-cyclohexanedimethanol (PCT), polylactic acid (PLA) and/or polypropylene (PP). 
     
     
         46 . A method of producing a thermoformable acoustic sheet according to  claim 26  wherein the web of thermoplastic fibres has a web weight of about 1000 g/m 2  or below. 
     
     
         47 . A method of producing a thermoformable acoustic sheet according to  claim 46  wherein the web of thermoplastic fibres has a web weight of about 800 g/m 2  or below. 
     
     
         48 . A method of producing a thermoformable acoustic sheet according to  claim 47  wherein the web of thermoplastic fibres has a web weight of about 600 g/m 2  or below. 
     
     
         49 . A method of producing a thermoformable acoustic sheet according to  claim 48  wherein the web of thermoplastic fibres has a web weight of about 400 g/m 2  or below. 
     
     
         50 . A method of producing a thermoformable acoustic sheet according to  claim 26  wherein the web of thermoplastic fibres have 50% or more of adhesive fibres or adhesive component fibres and is compressed at a temperature between 180-220° C. for a period between 1 and 3 minutes. 
     
     
         51 - 52 . (canceled)