Patent ID: 7700179

Claim:
A continuous web of self-supporting polyvinyl butyral adhesive sheet useful for making a transparent polyvinyl butyral adhesive interlayer comprising: (a) two areas of uniform thickness profile across at least 20% of its width extending from the edges of the web toward the center such that by splitting the web at or near its midpoint between the outer edges, two pieces of sheet can be obtained each having an area of at least 20% uniform thickness, and (b) an area of non-uniform thickness profile wherein the thickness of the web is continuously increasing starting at or near the center of the web and increasing in the direction of both edges to the areas of uniform thickness along the edges of the web, wherein a vertex is formed at each juncture where an area of uniform thickness meets an area of non-uniform thickness, and wherein the vertices are curved such that a sharp edge is not detectable by physical inspection of the vertex.