Acoustic absorber with barrier facing

Abstract

An acoustic absorber includes a core of acoustically absorbing material having two major surfaces, and a facing for covering the core on at least one major surface. The facing comprises a porous flash spun plexifilamentary film-fibril sheet having a coherent surface and comprising a plurality of pores having a pore diameter between about 100 nm and about 20,000 nm and a mean pore diameter of less than about 20,000 nm. The use of the facing improves the acoustic absorption of ambient sound at a frequency below about 1200 Hz. The facing provides a barrier to moisture and particles including microorganisms so that the absorber is suitable for use in environments in which cleanliness is critical.

1 . An acoustically absorbing article comprising:
 a core of acoustically absorbing material having two major surfaces; and   a facing for covering the core on at least one major surface, the facing comprising a porous flash spun plexifilamentary film-fibril sheet having a coherent surface, having a basis weight of no greater than about 140 g/m 2  and comprising a plurality of pores having a pore diameter between about 100 nm and about 20,000 nm and a mean pore diameter of less than about 20,000 nm.   
   
   
       2 . The article of  claim 1 , wherein the core of acoustically absorbing material has a noise reduction coefficient of at between about 0.3 and about 0.9 and the acoustically absorbing material is selected from the group consisting of fibrous batting, foam, honeycomb, air space, perforated material and the combination of the above. 
   
   
       3 . The article of  claim 1 , wherein the facing has a plurality of pores having a pore diameter between about 100 nm and about 20,000 nm and a mean pore diameter of less than about 5,000 nm. 
   
   
       4 . The article of  claim 1 , wherein the facing has a plurality of pores having a pore diameter between about 100 nm and about 20,000 nm and a mean pore diameter of less than about 2,000 nm. 
   
   
       5 . The article of  claim 1 , wherein the facing comprises a polymer selected from the group consisting of polyethylene and polypropylene. 
   
   
       6 . The article of  claim 1 , wherein the facing has a thickness of not more than about 1 mm and the core has a thickness of at least about 5 mm. 
   
   
       7 . The article of  claim 1 , wherein the facing has a Parker surface smoothness not less than 6 micrometers. 
   
   
       8 . The article of  claim 1 , wherein the facing comprises a graphical image printed thereon. 
   
   
       9 . The article of  claim 1 , wherein the facing has a tensile strength of at least about 20 N/2.54 cm. 
   
   
       10 . The article of  claim 1 , wherein the facing is free of nutrients that support growth of microorganisms. 
   
   
       11 . The article of  claim 1 , wherein the facing has a log reduction value of at least about 4. 
   
   
       12 . The article of  claim 1 , wherein the acoustic absorption of the article at a frequency below about 1200 Hz is at least about 5% higher than the acoustic absorption of the article without the facing. 
   
   
       13 . The article of  claim 1 , wherein the facing is further perforated with holes projecting completely through the facing. 
   
   
       14 . The article of  claim 13 , wherein the hole diameter is less than 1 mm. 
   
   
       15 . The article of  claim 1 , wherein the facing further comprises a coating selected from the group consisting of metallized layer, antistatic layer, pigmented layer, gloss, antibacterial layer and photoreactive layer. 
   
   
       16 . The article of  claim 1 , further comprising an adhesive layer located between the facing and at least one major surface of the core. 
   
   
       17 . An assembly comprising:
 a) a core of acoustically absorbing material having two major surfaces;   b) a facing for covering the core on at least one major surface, the facing comprising a porous flash spun plexifilamentary film-fibril sheet having a coherent surface, having a basis weight of no greater than about 140 g/m 2  and comprising a plurality of pores having a pore diameter between about 100 nm and about 20,000 nm and a mean pore diameter of less than about 20,000 nm; and   c) a sound permeable rigid casing for encasing the core and facing on at least one major surface.   
   
   
       18 . The assembly of  claim 17 , wherein the sound permeable rigid casing is selected from the group consisting of perforated metal, perforated plastic, and perforated solid filled resin material. 
   
   
       19 . The assembly of  claim 17 , wherein the acoustic absorption of the assembly at a frequency below about 1200 Hz is at least about 5% higher than the acoustic absorption of the assembly without the facing. 
   
   
       20 . An acoustically absorbing partition comprising:
 a core of acoustically absorbing material having two major surfaces; and   a facing for covering the core on at least one major surface, the facing comprising a porous flash spun plexifilamentary film-fibril sheet having a coherent surface, having a basis weight of no greater than about 140 g/m 2  and comprising a plurality of pores having a pore diameter between about 100 nm and about 20,000 nm and a mean pore diameter of less than about 20,000 nm.   
   
   
       21 . The partition of  claim 20 , wherein the acoustic absorption of the partition at a frequency below about 1200 Hz is at least about 5% higher than the acoustic absorption of the partition without the facing. 
   
   
       22 . An acoustically absorbing architectural surface covering comprising:
 a core of acoustically absorbing material having two major surfaces; and   a facing for covering the core on at least one major surface, the facing comprising a porous flash spun plexifilamentary film-fibril sheet having a coherent surface, having a basis weight of no greater than about 140 g/m 2  and comprising a plurality of pores having a pore diameter between about 100 nm and about 20,000 nm and a mean pore diameter of less than about 20,000 nm.   
   
   
       23 . The covering of  claim 22 , wherein the acoustic absorption of the covering at a frequency below about 1200 Hz is at least about 5% higher than the acoustic absorption of the covering without the facing. 
   
   
       24 . A method of improving acoustic absorption in an environment comprising:
 (a) providing an acoustically absorptive article comprising a core of acoustically absorptive material covered by a facing of porous flash spun plexifilamentary film-fibril sheet having a coherent surface, having a basis weight of no greater than about 140 g/m 2  and comprising a plurality of pores having a pore diameter between about 100 nm and about 20,000 nm and a mean pore diameter of less than about 20,000 nm; and   (b) positioning the article within the environment to cause ambient sound to be absorbed by the article.