Method of manufacturing heat bonded glass fiber insulation boards

DETAILED DESCRIPTION The present invention is directed to a method for producing heat bonded glass fiber insulation boards of various thickness on a commercial basis.
The heat bonded glass fiber insulation boards are low cost, high performance glass fiber insulation boards particularly suited for use in partially evacuated gas-tight envelope insulation structures referred to as vacuum panels.
Preferably, the glass fibers of the glass fiber insulation board of the present invention are formed by chopping continuous or long staple tow glass filaments into discrete lengths suitable for dry laying into thin glass fiber mats and are at least six microns in diameter so that the glass fibers are not respirable.
In a preferred embodiment of the invention, the discrete length glass fibers are dry laid to form thin glass fiber mats having weights between 5 and 50 g/m.
sup.
2.
By dry laying the glass fibers to form light weight, thin glass fiber mats, the glass fibers in the mats predominately lie in and are randomly oriented in planes extending parallel or substantially parallel to the major surfaces of the thin glass fiber mat.
The light weight, thin glass fiber mat is then lapped back and forth upon itself or otherwise layered to form an uncompressed thick glass fiber blanket between 3 and 40 centimeters thick that can be heated and compressed to form a binderless, heat bonded glass fiber insulation board of sufficient density and integrity to withstand one atmosphere of pressure without any significant thickness change (10% or less) in the board.
To form the binderless, heat bonded glass fiber insulation board, the thick glass fiber blanket is heated to a temperature between about 25.
degree.
C.
below and about 20.
degree.
C.
above the strain temperature of the glass fibers, and preferably, to a temperature equal to or about equal to the strain temperature of the glass fibers for a sufficient period of time (e.
g.
up to about 40 to 60 minutes) to form a heat bonded insulation board of the required integrity