Vacuum insulating glass unit with viscous edge seal

Abstract

Vacuum insulating glass (VIG) units, edge seals for VIG units and methods for forming the edge seals are provided. The VIG units include an edge seal that includes a viscous material, which serves to restrict the rate at which gas permeates into a vacuum space defined between the glass sheets of the VIG unit. The edge seals are configured to allow the glass sheets to move laterally relative to one another when the glass sheets experience differential thermal strain and further configured such that viscous shear occurs within at least a portion of the viscous material when there is relative lateral movement between the glass sheets.

1 . An edge seal for a vacuum insulating glass unit comprising a first glass sheet and a second glass sheet with a vacuum space in between at a pressure less than atmospheric pressure, wherein the edge seal is configured to provide a seal for the vacuum space in between the first glass sheet and the second glass sheet, the edge seal comprising:
 (a) a viscous material, wherein the viscous material restricts the rate at which gas permeates into the vacuum; the edge seal being configured to allow the first and second glass sheets to move laterally relative to one another when the first and second glass sheets experience differential thermal strain and further configured such that viscous shear occurs within at least a portion of the viscous material when there is relative lateral movement between the first and second glass sheets; and   (b) at least one barrier configured to constrain the viscous material from entering the vacuum space when the edge seal is placed in a vacuum insulating glass unit.   
     
     
         2 . An edge seal according to  claim 1 , wherein the viscous material has a gas permeability of no greater than 1,000,000 cm 3 ·mm/(m 2 ·barday) for oxygen gas at 20° C., as measured by ASTM D 3985. 
     
     
         3 . An edge seal according to  claim 1 , wherein the viscous material is a Newtonian fluid. 
     
     
         4 . An edge seal according to  claim 1 , wherein the viscous material includes polyisobutene. 
     
     
         5 . An edge seal according to  claim 1 , wherein the viscous material consists essentially of polyisobutene. 
     
     
         6 . An edge seal according to  claim 1 , wherein the barrier is a viscous barrier in contact with the viscous material. 
     
     
         7 . An edge seal according to  claim 1 , wherein the barrier comprises at least one of the first and the second glass sheets.