Abstract
This paper discusses the insulating and fire properties of rigid PIR/PUR foams from the perspective of facing materials.
The insulating effectiveness of a rigid PIR/PUR foam can be expressed in terms of R value, which is the resistance to heat flow of a given thickness of material. The R value is normally at a peak at the time of manufacture but decreases when air permeates through the foam matrix into the cell gas. The rate of decrease in R value is dependent upon several factors including the cell gas content, cell size and orientation, foam density, the integrity of the bond between foam and facing material, and particularly the permeability of the facing material. Rigid PIR/PUR foams which are protected by facing materials with a low gas permeability maintain their initial high R values. Thus, a good facing material will minimize the rate of R value decrease, pass standard fire tests as a composite material with PIR/PUR foams, provide a good substrate for foam adhesion, allow for the use of nails and/or fasteners during fixing, and be cost effective.
A facer material has been developed based upon polyethyleneterephthalate (PET) substrate which has been vacuum metallized with a thin layer of aluminium on one surface. This is well known to the packaging industry and one of the best gas and moisture barriers on the market. Laminated to rigid PIR/PUR boardstock the vacuum metallized PET has been found to be superior in maintaining R value and fire performance over typically used A1 foil and A1 foil paper laminates.
Get full access to this article
View all access options for this article.