Multilayer interlayer having sound damping properties over a broad temperature range

A polymer interlayer having improved sound insulation, the polymer interlayer comprising:

• at least one soft layer wherein the soft layer comprises a blend of two or more poly(vinyl butyral) resins comprising:
• a first poly(vinyl butyral) resin having a first residual hydroxyl content and a first glass transition temperature (Tg);
• a second poly(vinyl butyral) resin having a second residual hydroxyl content and a second glass transition temperature (Tg),
• wherein the difference between the first residual hydroxyl content and the second residual hydroxyl content is at least 1.0 weight percent;
• wherein the difference between the first glass transition temperature (Tg) and the second glass transition temperature (Tg) is at least 1.5° C.;
• and
• a plasticizer, wherein the first poly(vinyl butyral) resin, the second poly(vinyl butyral) resin and the plasticizer are mixed and melt-extruded to form the at least one soft layer;
• at least one stiffer layer comprising a third poly(vinyl butyral) resin having a third residual hydroxyl content;
• and
• a plasticizer,
• wherein the polymer interlayer has a damping loss factor (η) (as measured by Mechanical Impedance Measurement according to ISO 16940) of at least about 0.16 measured at two or more different temperatures selected from 10° C., 20° C. and 30° C., and wherein the second poly(vinyl butyral) resin is present in an amount of from about 5 weight percent to about 50 weight percent.

A polymer interlayer having improved sound insulation, the polymer interlayer comprising:

• at least one soft layer wherein the soft layer comprises a blend of two or more poly(vinyl butyral) resins comprising:
• a first poly(vinyl butyral) resin having a first residual hydroxyl content and a first glass transition temperature (Tg);
• a second poly(vinyl butyral) resin having a second residual hydroxyl content and a second glass transition temperature (Tg),
• wherein the difference between the first residual hydroxyl content and the second residual hydroxyl content is at least 1.0 weight percent,
• wherein the difference between the first glass transition temperature (Tg) and the second glass transition temperature (Tg) is at least 1.5° C.;
• and
• a plasticizer, wherein the first poly(vinyl butyral) resin, the second poly(vinyl butyral) resin and the plasticizer are mixed and melt-extruded to form the at least one soft layer;
• at least one stiffer layer comprising a third poly(vinyl butyral) resin having a third residual hydroxyl content;
• and
• a plasticizer,
• wherein each plasticized resin in the soft layer of the polymer interlayer has a glass transition temperature (Tg) less than 20.0° C.