Patent ID: 9114595
Filing Date: 2015-08-25
Classification: B29C,B29K,B29L,B32B,Y10T

Abstract:
1. A method for producing a poly(vinyl butyral) interlayer comprising: forming a first poly(vinyl butyral) melt, a second poly(vinyl butyral) melt, and a third poly(vinyl butyral) melt; coextruding said first poly(vinyl butyral) melt, said second poly(vinyl butyral) melt, and said third poly(vinyl butyral) melt to form said interlayer comprising, in order, a first low plasticizer content poly(vinyl butyral) layer, a high plasticizer content poly(vinyl butyral) layer with 30 to 100 phr by weight plasticizer, and a second low plasticizer content poly(vinyl butyral), and inducing and controlling melt fracture during coextruding such that both surfaces of said interlayer have an R (i) controlling the temperature of the die lips or lands at the extrusion opening through which interlayer is extruded, or (ii) controlling the rate of cooling of the interlayer immediately after coextrusion; wherein the first low plasticizer content poly(vinyl butyral) layer has a tensile break stress that is at least 15 kilograms per square centimeter greater than the tensile break stress of said high plasticizer content poly(vinyl butyral) layer, and said second low plasticizer content poly(vinyl butyral) layer has a tensile break stress that is at least 15 kilograms per square centimeter greater than the tensile break stress of said high plasticizer content poly(vinyl butyral) layer, and wherein the interlayer has a mottle value of less then 4.