Multiple layer interlayers having enhanced properties
Multiple layer interlayers comprising pairs of alternating polymer layers are provided, along with methods of making and using the same. Multiple layer interlayers according to embodiments of the present invention may include more than three polymer layers and may exhibit desirable acoustic and optical properties, which may make them suitable for use in various types of multiple layer panels, including safety glass for automotive and architectural applications.
1. A multiple layer interlayer comprising:
at least 3 pairs of alternating polymer layers, wherein each of said pairs of alternating polymer layers comprises
a first polymer layer comprising a first polyvinyl butyral) resin and at least one plasticizer; and
a second polymer layer adjacent to said first polymer layer, wherein said second polymer layer comprises a second poly(vinyl acetal) resin and at least one plasticizer;
wherein, for at least one of said pairs, said first poly(vinyl butyral) resin has a residual hydroxyl content that is at least 2 weight percent different than the residual hydroxyl content of said second poly(vinyl acetal) resin and/or wherein said first poly(vinyl acetal) resin has a residual acetate content that is at least 2 weight percent different than the residual acetate content of said second poly(vinyl acetal) resin;
wherein the said second polymer layer has a thickness greater than 50 microns; and
wherein said interlayer has a sound transmission loss of at least 35 dB, measured according to ASTM E90 (2009) at a temperature of 20° C. and a frequency of 3150 Hz, with a test panel having a length of 80 centimeters and a width of 50 centimeters, formed from two clear glass panels each having a thickness of 2.3 mm.
2. The multiple layer interlayer of claim 1 , wherein said residual hydroxyl content of said first poly(vinyl acetal) resin is at least 2 weight percent higher than said residual hydroxyl content of said second poly(vinyl acetal) resin.
3. The multiple layer interlayer of claim 1 , wherein said first poly(vinyl acetal) resin has a residual acetate content that is not more than 4 weight percent different than the residual acetate content of said second poly(vinyl acetal) resin and/or wherein said residual hydroxyl content of said first poly(vinyl acetal) resin is at least 5 weight percent different than said residual hydroxyl content of said second poly(vinyl acetal) resin.
4. The multiple layer interlayer of claim 1 , further comprising a cap polymer layer adjacent to one of said second polymer layers of one of said pairs of alternating polymer layers, wherein said one of said second polymer layers that is adjacent to said cap layer has a glass transition temperature, and wherein said cap layer has a glass transition temperature that is at least 3° C. different than said glass transition temperature of said one of said second polymer layers that is adjacent to said cap layer.
5. The multiple layer interlayer of claim 1 , wherein, for all of said pairs, said first poly(vinyl acetal) resin has a residual hydroxyl content that is at least 2 weight percent different than the residual hydroxyl content of said second poly(vinyl acetal) resin and/or wherein said first poly(vinyl acetal) resin has a residual acetate content that is at least 2 weight percent different than the residual acetate content of said second poly(vinyl acetal) resin.
6. The multiple layer interlayer of claim 1 , wherein, for at least one of said pairs, the difference in plasticizer content between said pair is at least about 10 phr.
7. The multiple layer interlayer of claim 1 , wherein, for at least one of said pairs, said glass transition temperature of at least one of said layers is not more than 20° C.
8. A multiple layer interlayer comprising:
at least 3 pairs of alternating polymer layers, wherein each of said pairs of alternating polymer layers comprises
a first polymer layer comprising a first poly(vinyl butyral) resin and at least one plasticizer; and
a second polymer layer adjacent to said first polymer layer, wherein said second polymer layer comprises a second polyvinyl butyral) resin and at least one plasticizer;
and a cap polymer layer adjacent to one of said second polymer layers of one of said pairs of alternating polymer layers, wherein said one of said second polymer layers that is adjacent to said cap layer has a glass transition temperature, and wherein said cap layer has a glass transition temperature that is at least 3° C. different than said glass transition temperature of said one of said second polymer layers that is adjacent to said cap layer;
wherein, for at least one of said pairs, said first poly(vinyl butyral) resin has a residual hydroxyl content that is at least 2 weight percent different than the residual hydroxyl content of said second poly(vinyl acetal) resin and/or wherein said first poly(vinyl acetal) resin has a residual acetate content that is at least 2 weight percent different than the residual acetate content of said second poly(vinyl acetal) resin;
wherein the said second polymer layer has a thickness greater than 50 microns; and
wherein said interlayer has a sound transmission loss of at least 35 dB, measured according to ASTM E90 (2009) at a temperature of 20° C. and a frequency of 3150 Hz, with a test panel having a length of 80 centimeters and a width of 50 centimeters, formed from two clear glass panels each having a thickness of 2.3 mm.
9. The multiple layer interlayer of claim 8 , wherein said residual hydroxyl content of said first poly(vinyl acetal) resin is at least 2 weight percent higher than said residual hydroxyl content of said second poly(vinyl acetal) resin.
10. The multiple layer interlayer of claim 8 , wherein said first poly(vinyl acetal) resin has a residual acetate content that is not more than 4 weight percent different than the residual acetate content of said second poly(vinyl acetal) resin and/or wherein said residual hydroxyl content of said first poly(vinyl acetal) resin is at least 5 weight percent different than said residual hydroxyl content of said second poly(vinyl acetal) resin.
11. The multiple layer interlayer of claim 8 , wherein, for all of said pairs, said first poly(vinyl acetal) resin has a residual hydroxyl content that is at least 2 weight percent different than the residual hydroxyl content of said second poly(vinyl acetal) resin and/or wherein said first poly(vinyl acetal) resin has a residual acetate content that is at least 2 weight percent different than the residual acetate content of said second poly(vinyl acetal) resin.
12. The multiple layer interlayer of claim 8 , wherein, for at least one of said pairs, the difference in plasticizer content between said pair is at least about 10 phr.
13. The multiple layer interlayer of claim 8 , wherein, for at least one of said pairs, said glass transition temperature of at least one of said layers is not more than 20° C.