Patent ID: 7854993

Claim:
A polymer interlayer comprising: a first polymer sheet comprising a plasticized poly(vinyl butyral); a second polymer sheet comprising a plasticized poly(vinyl butyral), wherein said second polymer sheet is in direct contact with said first polymer sheet; a third polymer sheet comprising a plasticized poly(vinyl butyral), wherein said third polymer sheet is in direct contact with said second polymer sheet; wherein the amount of plasticizer in said plasticized poly(vinyl butyral) of said second polymer sheet is at least 12 parts per hundred greater than the amount of plasticizer in either said plasticized poly(vinyl butyral) of said first polymer sheet or said plasticized poly(vinyl butyral) of said third polymer sheet; wherein said second polymer sheet has a residual hydroxyl content per weight percentage that is at least 2% lower than the residual hydroxyl content per weight percentage of either said first polymer sheet or said third polymer sheet; and, wherein said first polymer sheet and said second polymer sheet each have a residual acetate content of less than 5 mol percent.