Thermal and acoustical wall paneling composed of a plurality of superimposed layers are well known in the art. An example of such an insulation panel is exemplified in U.S. Pat. No. 3,879,910, which is incorporated by reference herein. Insulation panels of this type are typically prefabricated to dimensions that make them manageable during manufacture, shipping and installation. In use, the panels are generally placed end-on-end, to cover the desired surface.
As disclosed in the foregoing patent, the layers of such an insulation panel can include a sound-absorbing lead sheet, several layers of heat-absorbing or heat-reflective material, and a facing for maintaining the rigidity of the panel. It is no coincidence that lead is used as the sound-absorbing layer. Conventional wisdom has long held that the higher the density of the sound-absorbing member, the better the acoustical properties of the panel. Because lead is well known for its large density, it is frequently used as the preferred sound-absorbing material in the insulating industry today.
However, while lead is preferred, there are, unfortunately, many hazards now known to be associated with it. Thus, many safety guidelines and environmental controls that have been implemented to protect workers and users from coming in contact with the material and prevent water supplies from becoming contaminated with lead or lead byproducts. Despite these guidelines and controls, there continues to be a great deal of debate surrounding the harmful effects of lead on humans and the environment.
An additional problem in using lead is its expense. The numerous safety guidelines and environmental controls associated with the use of lead, result in an increase in the cost of products that contain it. In addition, the manufacturing, the shipping and the installation costs associated with it are significantly greater due to its weight.
Finally, because lead is considered a hazardous material, its disposal costs are high. Unfortunately, substitute materials for lead in the area of sound reflection are few. Conventional wisdom in this area has directed the industry away from synthetic materials and towards high density metallic sound reflecting materials.