Modified copolyesters and improved multilayer reflective films
First Claim
1. A polymer, comprising:
- a copolyester having an intrinsic viscosity of about 0.4 dL/g or greater and comprising glycol subunits and carboxylate subunits, the glycol subunits derived from 70 to 99 mol % C2-C4 diols and about 1 to 30 mol % comonomer glycol subunits derived from 1,6-hexanediol, and the carboxylate subunits being 5 to 99 mol % naphthalate subunits, 1 to 95 mol % terephthalate or isophthalate subunits or mixtures thereof, and 0 to 30 mol % of comonomer carboxylate subunits derived from phthalic acid, t-butyl-isophthalic acid, lower alkyl esters of these acids, or a combination thereof;
wherein at least 0.01 to 2.5 mol % of the combined carboxylate and glycol subunits of the copolyester are derived from compounds having three or more carboxylate, ester, or hydroxy functional groups.
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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.
75 Citations
20 Claims
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1. A polymer, comprising:
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a copolyester having an intrinsic viscosity of about 0.4 dL/g or greater and comprising glycol subunits and carboxylate subunits, the glycol subunits derived from 70 to 99 mol % C2-C4 diols and about 1 to 30 mol % comonomer glycol subunits derived from 1,6-hexanediol, and the carboxylate subunits being 5 to 99 mol % naphthalate subunits, 1 to 95 mol % terephthalate or isophthalate subunits or mixtures thereof, and 0 to 30 mol % of comonomer carboxylate subunits derived from phthalic acid, t-butyl-isophthalic acid, lower alkyl esters of these acids, or a combination thereof;
wherein at least 0.01 to 2.5 mol % of the combined carboxylate and glycol subunits of the copolyester are derived from compounds having three or more carboxylate, ester, or hydroxy functional groups. - View Dependent Claims (15)
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2. 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 pentaerythritol. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. 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 trimellitic acid or an ester thereof. - View Dependent Claims (14, 16, 17, 18, 19, 20)
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Specification