Multiple layer interlayer resisting defect formation

A polymer interlayer that resists formation of iceflower defects, 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;
• a second poly(vinyl butyral) resin having a second residual hydroxyl content, wherein the difference between the first residual hydroxyl content and the second residual hydroxyl content is at least 2.0 weight percent;
• and
• at least one plasticizer having a refractive index of at least 1.460 selected from dipropylene glycol dibenzoate, tripropylene glycol dibenzoate, polypropylene glycol dibenzoate, isodecyl benzoate, 2-ethylhexyl benzoate, diethylene glycol benzoate, butoxyethyl benzoate, butoxyethyoxyethyl benzoate, butoxyethoxyethoxyethyl benzoate, propylene glycol dibenzoate, 2,2,4-trimethyl-1,3-pentanediol dibenzoate, 2,2,4-trimethyl-1,3-pentanediol benzoate isobutyrate, 1,3-butanediol dibenzoate, diethylene glycol di-o-toluate, triethylene glycol di-o-toluate, dipropylene glycol di-o-toluate, 1,2-octyl dibenzoate, tri-2-ethylhexyl trimellitate, di-2-ethylhexyl terephthalate, bis-phenol A bis(2-ethylhexaonate), di-(butoxyethyl) terephthalate, di-(butoxyethyoxyethyl) terephthalate, and mixtures thereof, wherein the first poly(vinyl butyral) resin, the second poly(vinyl butyral resin) and the at least one plasticizer having a refractive index of at least 1.460 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 ISO 16940) of at least about 0.15, a percent haze of less than 1.0% (as measured by a hazemeter in accordance with ASTM D1003-61 (Re-approved 1977)-Procedure A using Illuminant C, at an observer angle of 2 degrees).

A polymer interlayer that resists formation of iceflower defects, 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;
• a second poly(vinyl butyral) resin having a second residual hydroxyl content, wherein the difference between the first residual hydroxyl content and the second residual hydroxyl content is at least 2.0 weight percent;
• and
• a high refractive index plasticizer having a refractive index of at least about 1.460, wherein the first poly(vinyl butyral) resin, the second poly(vinyl butyral resin) and the high refractive index 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 ISO 16940) of at least about 0.15, a percent haze of less than 1.0% (as measured by a hazemeter in accordance with ASTM D1003-61 (Re-approved 1977)-Procedure A using Illuminant C, at an observer angle of 2 degrees), and wherein the second poly(vinyl butyral) resin is present in amount of from about 5 weight percent to about 45 weight percent.