Method and apparatus for adhesive application to barrier sheet

A process for applying an adhesive material onto a sheet substrate comprising the steps of:

• a) providing an adhesive material having viscosity of at least about 10,000 centipoise at 250° F. as measured by Brookfield Rheometer (RVDVII+) using Spindle #29 at 2 rpm;
• b) applying said adhesive to a multitude of cavities formed on a surface of a first tool with a coater unit having at least one adhesive material applicator in close proximity to the surface;
• and c) transferring the adhesive material at a thickness of at least 2 mil from the surface of the first tool to said substrate supported on a surface of a second tool and pressed against the surface of the first tool.