Patent ID: 6352761
Filing Date: 2002-03-05
Classification: A61B,A61N,B32B,C08G,G02B,Y10S,Y10T

Abstract:
A multilayered polymer film, comprising:a plurality of first optical layers comprising a first copolyester, the first copolyester being semicrystalline and birefringent, the first copolyester comprising carboxylate subunits and glycol subunits, wherein 70 to 100 mol % of the carboxylate subunits are first carboxylate subunits, 0 to 30 mol % of the carboxylate subunits are first comonomer carboxylate subunits, 70 to 100 mol % of the glycol subunits are first glycol subunits, and 0 to 30 mol % of the glycol subunits are first comonomer glycol subunits, and wherein at least 2.5 mol % of the combined carboxylate and glycol subunits of the first copolyester are first comonomer carboxylate subunits, first comonomer glycol subunits, or a combination thereof; and a plurality of second optical layers comprising a second copolyester having an in-plane birefringence of about 0.04 or less, at 632.8 nm, after the multilayered polymer film has been formed, the second copolyester comprising carboxylate subunits and glycol subunits, the carboxylate subunits comprising 20 to 100 mol % second carboxylate subunits and 0 to 80 mol % second comonomer carboxylate subunits, the glycol subunits comprising 40 to 100 mol % second glycol subunits and 0 to 60 mol % second comonomer glycol subunits, wherein 10 mol % or more of the combined carboxylate and glycol subunits of the second copolyester are second comonomer carboxylate subunits, second comonomer glycol subunits, or a combination thereof, wherein 0.01 to 2.5 mol % of the combined carboxylate and glycol subunits of the second copolyester are second comonomer carboxylate subunits derived from compounds having three or more carboxylate or ester functionalities, second comonomer glycol subunits derived from compounds having three or more hydroxy functionalities, or a combination thereof.