摘要:
A reflective film includes microlayers arranged into optical repeat units, each optical repeat unit including a negatively birefringent microlayer. The microlayers are tailored to provide the film with on-axis polarizing properties, such that normally incident light polarized along a block axis is substantially reflected and normally incident light polarized along a pass axis is substantially transmitted. On-axis transmission for the block axis may be 70%. The microlayers also provide the film with angularly dependent polarizing properties: p-polarized light incident in a block plane of incidence is substantially reflected at near-normal angles but substantially transmitted at an oblique angle. The film transmits unpolarized light incident in this plane more strongly at the oblique angle than at normal. The films can be used in direct-lit backlights, luminaires, and similar lighting systems for flux leveling to promote spatial brightness uniformity.
摘要:
An optical stack (400) having a plurality of alternating polymeric layers (401, 402) is described. The alternating layers may be alternating birefringent (syndiotactic polystyrene, sPS) and isotropic (CoPENa) layers, or alternating positively and negatively birefringent layers. Birefringent layers are made using polymers which form optically symmetrical crystallites upon stretching of the polymer. The optical stack has a large refractive index difference in the x-direction (the stretching direction) and small refractive index differences in the y- and z-directions (the non-stretching directions). The optical stack can be made using standard film tentering methods and may be a multilayer reflective polarizer.
摘要:
An optical stack (400) having a plurality of alternating polymeric layers (401, 402) is described. The alternating layers may be alternating birefringent (syndiotactic polystyrene, sPS) and isotropic (CoPENa) layers, or alternating positively and negatively birefringent layers. Birefringent layers are made using polymers which form optically symmetrical crystallites upon stretching of the polymer. The optical stack has a large refractive index difference in the x-direction (the stretching direction) and small refractive index differences in the y- and z-directions (the non-stretching directions). The optical stack can be made using standard film tentering methods and may be a multilayer reflective polarizer.
摘要:
In one embodiment, the invention provides a polyethylene terephthalate film comprising a biaxially oriented and birefringent film polyethylene terephthalate film having at least one layer having a thickness of from 10 mils (0.25 mm) to 25 mils (0.64 mm), wherein the film is formed from a polyethylene terephthalate resin comprising the reaction product of dimethyl terephthalate, terephthalic acid, or a combination thereof ethylene glycol, a diol or triol monomer other than ethylene glycol and from 0.9 to 3 mol percent of a sulfonate monomer having an inorganic counterion based on 100 mol percent dimethyl terephthalate, terephthalic acid, or a combination thereof.
摘要:
Multilayer optical film that can be used as a reflective polarizer or mirror is disclosed. The multilayer optical film comprises alternating optical layers of polyesters such as PET and PEN, copolymerized with 4,4′-biphenyl dicarboxylate. The multilayer optical film exhibits a high ratio of in-plane to out-of-plane birefringence.
摘要:
Multilayer optical film that can be used as a reflective polarizer or mirror is disclosed. The multilayer optical film comprises alternating optical layers of polyesters such as PET and PEN, copolymerized with 4,4′-biphenyl dicarboxylate. The multilayer optical film exhibits a high ratio of in-plane to out-of-plane birefringence.
摘要:
The present invention relates to multilayer optical films and birefringent copolyester films. The birefringent copolyester optical layer or birefringent copolyester film comprises a major amount of naphthalate units, ethylene units, and a minor amount of branched or cyclic C4 to C10 alkyl units. Also described are certain copolyester polymeric materials further comprising subunits of a phthalate ionomer such as dimethyl sulfosodium isophthtalate ionomer.
摘要:
A reflective film includes interior layers that selectively reflect light by constructive or destructive interference, the layers extending from a first to a second zone of the film. The interior layers include a first set of layers composed of a first material and a second set of layers composed of a different second material. The first and second sets of layers are both birefringent in the first zone, but at least some of the layers have reduced birefringence in the second zone. The reduced birefringence produces a second reflective characteristic in the second zone that differs from a first reflective characteristic in the first zone, this difference not being substantially attributable to any thickness difference between the first and second zones. The film may also incorporate absorbing agents to assist in the manufacture or processing of the film. Related methods and articles are also disclosed.
摘要:
A reflective film includes interior layers that selectively reflect light by constructive or destructive interference, the layers extending from a first to a second zone of the film. The interior layers include a first set of layers composed of a first material and a second set of layers composed of a different second material. The first and second sets of layers are both birefringent in the first zone, but at least some of the layers have reduced birefringence in the second zone. The reduced birefringence produces a second reflective characteristic in the second zone that differs from a first reflective characteristic in the first zone, this difference not being substantially attributable to any thickness difference between the first and second zones. The film may also incorporate absorbing agents to assist in the manufacture or processing of the film.
摘要:
Presently described are multilayer optical films, oriented polyester films, negatively birefringent copolyester polymers, fluorene monomers, and polyester polymers prepared from such fluorene monomers. In one embodiment, the multilayer optical film comprises at least one first birefringent optical layer; and at least one second optical layer having a lower birefringence than the first optical layer; wherein at least one of the optical layers comprises a negatively birefringent polyester polymer comprising a backbone and repeat units comprising at least one pendent aromatic group that is conformationally locked relative to the backbone.