Method for making PEN/PMMA multilayer optical films
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Abstract
Methods and apparatuses are provided for the manufacture of coextruded polymeric multilayer optical films. The multilayer optical films have an ordered arrangement of layers of two or more materials having particular layer thicknesses and a prescribed layer thickness gradient throughout the multilayer optical stack. The methods and apparatuses described allow improved control over individual layer thicknesses, layer thickness gradients, indices of refraction, interlayer adhesion, and surface characteristics of the optical films. The methods and apparatuses described are useful for making interference polarizers, mirrors, and colored films that are optically effective over diverse portions of the ultraviolet, visible, and infrared spectra.
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Citations
23 Claims
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1-8. -8. (canceled)
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9. A method for making a multilayer optical film comprising alternating layers of a first and second polymer, the first polymer comprising homopolymer polyethylene naphthalate (PEN) and the second polymer comprising polymethyl methacrylate (PMMA), wherein the first and second polymers are coextruded at a melt temperature of about 275°
- C. without substantial degradation of the PMMA.
- View Dependent Claims (10, 11, 12, 13)
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14. A method of making a multilayer optical film, comprising:
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(a) providing at least a first and a second stream of resin, wherein the first stream of resin comprises homopolymer polyethylene naphthalate (PEN) and the second stream of resin comprises polymethyl methacrylate (PMMA), (b) dividing the first and second streams into a plurality of layers such that the layers of the first stream are interleaved with the layers of the second stream to yield a composite stream; and
(c) coextruding the composite stream at a melt temperature of about 275°
C. through a die to form a multilayer web wherein each layer is generally parallel to the major surface of adjacent layers. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23)
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Specification