Vitreous sheets with synthetic polymer spacer and process for making the same

Claim 1

In a method of manufacturing a hollow panel by uniting vitreous sheets by means of a spacer of synthetic polymeric material located between and adherent to margins of such sheets, the improvement consisting essentially of the steps of (1) laying upon the margin of one of the sheets a hardenable viscoelastic ribbon having cross-sectional dimensions and a viscosity sufficient to maintain the two sheets at at least the required final inter-sheet spacing under the weight of the superimposed sheet when the sheets are disposed horizontally with the ribbon between them, (2) laying the other sheet in generally horizontal position supported by said ribbon, and (3) then subjecting said ribbon to hardening conditions while the sheets are at said final required spacing to convert the ribbon into a spacer having a tensile strength of at least 4 kg/cm 2 , an elongation at break in excess of 50% and a water permeability of the polymeric material less than 0.2 g of water per m 2 of surface per 24 hours per mm of material thickness per cm of Hg pressure, wherein said viscoelastic ribbon is cured in situ at less than 100° C. to form said spacer, and wherein prior to hardening, said viscoelastic ribbon is capable of resisting significant deformation under the forces imposed by the superencumbent vitreous sheet and of resisting any permanent deformation under any forces which may be imposed by the handling of the ribbon before it is laid on one of the vitreous sheets in the panel assembly operation.