Retarder

US11016231B2 · kind B2 · utility

Assignee

• 3M INNOVATIVE PROPERTIES COMPANY · US

Inventors

• Stephen A. Johnson · Woodbury, US
• Derek W. Patzman · Savage, US
• Richard Y. Liu · Woodbury, US
• Victor Ho · Windom, US
• John F. Van Derlofske, III · Minneapolis, US

Key dates

• Filing date: Nov 19, 2018
• Grant date: May 25, 2021
• Expiry date: Nov 19, 2038

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C08L2205/025
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

A retarder including first and second outer layers and a birefringent layer disposed between and in direct contact with the first and second outer layers is described. The birefringent layer may include a first polyester having greater than 45 mole percent naphthalate units and greater than 45 mole percent ethylene units. Each of the first and second outer layers includes a second polyester which may include 40 to 50 mole percent naphthalate units, at least 25 mole percent ethylene units, and 10 to 25 mole percent of branched or cyclic C4-C10 alkyl units. The retarder has a retardance in a range of 1 micrometer to 100 micrometers.