Modified copolyesters and improved multilayer reflective films
First Claim
1. A multilayered polymer film, comprising:
- a plurality of first optical layers comprising a birefringent first copolyester; 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, wherein the second copolyester comprises carboxylate subunits derived from t-butylisophthalic acid or an ester thereof.
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Abstract
A multilayered polymer film includes a first set of optical layers and a second set of optical layers. The first set of optical layers is made from a polyester which is often birefringent. The polyesters of the first set of optical layers typically have a composition in which 70-100 mol % of the carboxylate subunits are first carboxylate subunits and 0-30 mol % are comonomer carboxylate subunits and 70 to 100 mol % of the glycol subunits are first glycol subunits and 0 to 30 mol % of the glycol subunits are comonomer glycol subunits, where at least 0.5 mol % of the combined carboxylate and glycol subunits are comonomer carboxylate or comonomer glycol subunits. The multilayered polymer film may be used to form, for example, a reflective polarizer or a mirror.
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Citations
25 Claims
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1. A multilayered polymer film, comprising:
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a plurality of first optical layers comprising a birefringent first copolyester; 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, wherein the second copolyester comprises carboxylate subunits derived from t-butylisophthalic acid or an ester thereof. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A multilayered polymer film, comprising:
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a plurality of first optical layers comprising a birefringent first copolyester; 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, wherein the second copolyester comprises glycol subunits derived from trimethylol propane. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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Specification