Poly(vinyl acetal) resin compositions, layers, and interlayers having enhanced optical properties

Abstract

Resin compositions, layers, and interlayers comprising two or more thermoplastic polymers and at least one RI balancing agent for adjusting the refractive index of at least one of the resins or layers is provided. Such compositions, layers, and interlayers exhibit enhanced optical properties while retaining other properties, such as impact resistance and acoustic performance.

What is claimed is: 
     
         1 . An interlayer comprising:
 a first resin layer, wherein said first resin layer comprises a first poly(vinyl acetal) resin and a first plasticizer, and wherein said first poly(vinyl acetal) resin has a first refractive index;   a second resin layer adjacent to said first resin layer, wherein said second resin layer comprises a second poly(vinyl acetal) resin and a second plasticizer, and wherein said second poly(vinyl acetal) resin has a second refractive index,   a third resin layer adjacent to said second resin layer, wherein said third resin layer comprises a third poly(vinyl acetal) resin and a third plasticizer, and wherein said third poly(vinyl acetal) resin has a third refractive index,   wherein at least one of said first poly(vinyl acetal) resin, said second poly(vinyl acetal) resin, and said third poly(vinyl acetal) resin comprises residues of an aldehyde having a refractive index of at least 1.421;   wherein the difference between the amount of said second plasticizer and amount of at least one of said first plasticizer and said third plasticizer is at least 8 parts per hundred parts of resin, and   wherein the absolute value of the difference between said second refractive index and at least one of said first refractive index and said third refractive index is not more than 0.010.   
     
     
         2 . The interlayer of  claim 1 , wherein the difference between the amount of said second plasticizer and the amount of at least one of said first plasticizer and said third plasticizer is at least 10 parts per hundred parts of resin. 
     
     
         3 . The interlayer of  claim 1 , wherein the absolute value of the difference between said second refractive index and at least one of said first refractive index and said third refractive index is not more than 0.008. 
     
     
         4 . The interlayer of  claim 1 , wherein the difference between the residual hydroxyl content of said second poly(vinyl acetal) resin and the residual hydroxyl content of at least one of said first poly(vinyl acetal) resin and said third poly(vinyl acetal) resin is at least 2 weight percent and wherein at least one of said first, said second, and said third resin layers has a glass transition temperature less than 25° C. 
     
     
         5 . The interlayer of  claim 1 , wherein at least one of said first, said second, and said third resin layers further comprises at least one aldehyde having a refractive index of less than 1.421. 
     
     
         6 . The interlayer of  claim 1 , wherein said residues of said aldehyde having a refractive index of at least 1.421 is at least about 0.5 weight percent, based on the total weight of aldehyde residues of said first, said second, or said third poly(vinyl acetal) resin. 
     
     
         7 . The interlayer of  claim 1 , wherein at least one of said first, said second and said third poly(vinyl acetal) resins has a residual acetate content of at least 5 weight percent. 
     
     
         8 . The interlayer of  claim 1 , wherein at least one of said first, said second, and said third poly(vinyl acetal) resins has a residual hydroxyl content of at least 16 weight percent and at least one of said first, said second, and said third poly(vinyl acetal) resins has a residual hydroxyl content of not more than 15 weight percent, wherein the difference between the glass transition temperature of said first resin layer and said second resin layer or the difference between the glass transition temperature of said second resin layer and said third resin layer is at least 3° C. 
     
     
         9 . An interlayer comprising:
 a first resin layer, wherein said first resin layer comprises a first poly(vinyl acetal) resin and a first plasticizer, and wherein said first poly(vinyl acetal) resin has a first refractive index; and   a second resin layer adjacent to said first resin layer, wherein said second resin layer comprises a second poly(vinyl acetal) resin and a second plasticizer, and wherein said second poly(vinyl acetal) resin has a second refractive index,   a third resin layer adjacent to said second resin layer, wherein said third resin layer comprises a third poly(vinyl acetal) resin and a third plasticizer, and wherein said third poly(vinyl acetal) resin has a third refractive index,   wherein at least one of said first poly(vinyl acetal) resin, said second poly(vinyl acetal) resin, and said third poly(vinyl acetal) resin comprises residues of an aldehyde having a refractive index of at least 1.421;   wherein each of said first and said third poly(vinyl acetal) resins has a residual hydroxyl content of at least 16 weight percent and said second poly(vinyl acetal) resin has a residual hydroxyl content of not more than 15 weight percent, wherein the difference between the glass transition temperatures of said first and third resin layers and said second resin layer is at least 3° C., and   wherein the difference between the residual hydroxyl content of said first and third poly(vinyl acetal) resins and said second poly(vinyl acetal) resin is at least 2 weight percent,   and wherein said second resin layer has a glass transition temperature less than 25° C.   
     
     
         10 . The interlayer of  claim 9 , wherein the difference between the amount of said second plasticizer and at least one of said first plasticizer and said third plasticizer is at least 10 parts per hundred parts of resin. 
     
     
         11 . The interlayer of  claim 9 , wherein at least one of said first, said second, and said third resin layers further comprises at least one aldehyde having a refractive index of less than 1.421. 
     
     
         12 . The interlayer of  claim 9 , wherein at least one of said first, said second and said third poly(vinyl acetal) resins has a residual acetate content of at least 5 weight percent. 
     
     
         13 . The interlayer of  claim 9 , wherein the absolute value of the difference between said second refractive index and at least one of said first refractive index and said third refractive index is not more than 0.010. 
     
     
         14 . The interlayer of  claim 9 , wherein the absolute value of the difference between said second refractive index and at least one of said first refractive index and said third refractive index is not more than 0.008. 
     
     
         15 . An interlayer comprising:
 a first resin layer, wherein said first resin layer comprises a first poly(vinyl acetal) resin and a first plasticizer, and wherein said first poly(vinyl acetal) resin has a first refractive index; and   a second resin layer adjacent to said first resin layer, wherein said second resin layer comprises a second poly(vinyl acetal) resin and a second plasticizer, and wherein said second poly(vinyl acetal) resin has a second refractive index,   a third resin layer adjacent to said second resin layer, wherein said third resin layer comprises a third poly(vinyl acetal) resin and a third plasticizer, and wherein said third poly(vinyl acetal) resin has a third refractive index,   wherein at least one of said first poly(vinyl acetal) resin, said second poly(vinyl acetal) resin, and said third poly(vinyl acetal) resin comprises residues of an aldehyde having a refractive index of at least 1.421;   wherein said second poly(vinyl acetal) resin has a residual hydroxyl content of at least 16 weight percent and each of said first and third poly(vinyl acetal) resins has a residual hydroxyl content of not more than 15 weight percent, wherein the difference between the glass transition temperatures of said first and third resin layers and said second resin layer is at least 3° C., and   wherein the difference between the residual hydroxyl content of said first and third poly(vinyl acetal) resins and said second poly(vinyl acetal) resin is at least 2 weight percent.   
     
     
         16 . The interlayer of  claim 15 , wherein the difference between the amount of said second plasticizer and at least one of said first plasticizer and said third plasticizer is at least 10 parts per hundred parts of resin. 
     
     
         17 . The interlayer of  claim 15 , wherein at least one of said first, said second, and said third resin layers further comprises at least one aldehyde having a refractive index of less than 1.421. 
     
     
         18 . The interlayer of  claim 15 , wherein at least one of said first, said second and said third poly(vinyl acetal) resins has a residual acetate content of at least 5 weight percent. 
     
     
         19 . The interlayer of  claim 15 , wherein the absolute value of the difference between said second refractive index and at least one of said first refractive index and said third refractive index is not more than 0.010. 
     
     
         20 . The interlayer of  claim 15 , wherein the absolute value of the difference between said second refractive index and at least one of said first refractive index and said third refractive index is not more than 0.008.