An employee of Delafield, Wis.-based Envelop LLC, Robert Jones, has been issued U.S. patent No. 8,182,887 for a “Vacuum Insulating Glass (VIG) Unit with Viscous Edge Seal.” According to the company, the VIG units include two spaced-apart glass sheets with a vacuum in between an array of spacers maintains separation of the sheets, and the units have a low permeability edge seal.

Edge seals covered by the new patent include a low permeability fluid that spans the edges of the glass sheets. The fluid undergoes viscous shear to accommodate differential thermal expansion and contraction between the glass sheets while generating minimal stress, according to the company. As a result, the design places no restriction on glass size. Tempered, laminated and coated glass can be used without damage because high temperatures are not needed for assembly.

The patent was first filed on March 14, 2011 and suggests there are “serious unresolved performance and reliability problems that continue to hamper development of commercially viable VIG units.”

Additionally, the patent says edge seal failure and fractures of non-ductile glass sheets are the most common performance issues.

“The patent record reveals an ongoing intensive effort to solve this problem by employing more flexible edge seal designs,” according to the patent. “The effort is spurred by a quest to capitalize on market demand for more energy efficient buildings. The demand is driven by a pressing need to forestall the mounting dangers of global warming by reducing greenhouse gas emissions.”


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