Sound-insulating laminated structure and method for the production thereof

Abstract

Herein provided is a sound-insulating laminated structure which is excellent in the ability of insulating low frequency sounds whose frequency falls within the range of from 200 to 1000 Hz. The sound-insulating laminated structure comprises a first glass wool layer, a metal foil layer free of any opening and a second glass wool layer. The first and second glass wool layers are ones each prepared by collecting and combining short glass fibers through the application of an uncured thermosetting phenol resin to the short glass fibers to thus give a web of glass wool prepreg and then molding, with heating, the web into a sound-insulating laminated structure having a desired shape.

1 . A method for reducing low frequency sound generated by an electric motor or engine of automobile, the method comprising placing a sound-insulating laminated structure around the electric motor or engine, wherein the sound-insulating laminated structure comprises a first glass wool layer, a metal foil layer free of any opening and a second glass wool layer, wherein the first and second glass wool layers are ones each prepared by collecting and combining short glass fibers through the application of an uncured thermosetting phenol resin to the glass fibers to thus give a web of glass wool prepreg and then molding, with heating, the web into a desired shape, wherein the overall thickness of the structure ranges from 5 to 100 mm, and wherein the low frequency sound ranges from 200 to 1000 Hz. 
     
     
         2 . The method as set forth in  claim 1 , wherein the overall thickness of the structure ranges from 10 to 70 mm. 
     
     
         3 . The method as set forth in  claim 1 , wherein the overall thickness of the structure ranges from 15 to 40 mm. 
     
     
         4 . The method as set forth in  claim 1 , wherein the low frequency sound ranges from 300 to 900 Hz. 
     
     
         5 . The method as set forth in  claim 1 , wherein the low frequency sound ranges from 400 to 900 Hz. 
     
     
         6 . The method as set forth in  claim 1 , wherein the low frequency sound ranges from 400 to 700 Hz. 
     
     
         7 . The method as set forth in  claim 1 , wherein the metal foil layer free of any opening is arranged at a position situating at a distance, from the outermost face of the structure, of 0.1 to 0.5 times the thickness of the structure, in the direction of the thickness thereof. 
     
     
         8 . The method as set forth in  claim 1 , wherein the metal foil layer free of any opening is arranged at a position situating at a distance, from the outermost face of the structure, of 0.15 to 0.45 times the thickness of the structure, in the direction of the thickness thereof. 
     
     
         9 . The method as set forth in  claim 1 , wherein the metal foil layer free of any opening is arranged at a position situating at a distance, from the outermost face of the structure, of 0.2 to 0.4 times the thickness of the structure, in the direction of the thickness thereof. 
     
     
         10 . The method as set forth in  claim 1 , wherein the metal foil layer free of any opening is arranged at a position situating at a distance, from the outermost face of the structure, of 0.3 to 0.4 times the thickness of the structure, in the direction of the thickness thereof. 
     
     
         11 . The method as set forth in  claim 1 , wherein the metal foil layer has a thickness ranging from 20 to 150 μm. 
     
     
         12 . The method as set forth in  claim 1 , wherein the metal foil layer has a thickness ranging from 40 to 120 μm. 
     
     
         13 . The method as set forth in  claim 1 , wherein the metal foil layer has a thickness ranging from 50 to 90 μm. 
     
     
         14 . The method as set forth in  claim 1 , wherein the sound-insulating laminated structure is prepared by the steps of:
 (1) providing a web of glass wool prepreg by collecting and combining short glass fibers through the application of an uncured thermosetting phenol resin to the short glass fibers;   (2) sandwiching a metal foil free of any opening between two layers of the foregoing web to thus form a laminated structure having a three-layer structure; and   (3) pressure-molding the laminated structure prepared in the step (2) with heating.