The Dow Chemical Company

Minnesota Mining and Manufacturing Company

3m Innovative Properties

Walter J Schrenk

John Allen Wheatley

Ralph E Ayres

Ranganath K Shastri

Ravi Ramanathan

Victor S Chang

Kenneth J Cleereman

Ray A Lewis

Herbert C Roehrs

Mark Alan Barger

Charles B Arends

David M Wisniewski

Jeffrey Nicholas Bremmer

Virgil W Coomer

Larry J Laursen

Conrad F Balazs

Daniel J Gosen

Stephen E Bales

Charles A Langhoff

William E Shrum

Grant W Cheney

Turner Alfrey, Jr

Ralph F Ayres

A birefringent interference polarizer which may be fabricated from readily available materials using established coextrusion techniques is provided. The polarizer has a level of light absorption near zero and can be fabricated to polarize and reflect light of specific wavelengths while transmitting light of other wavelengths. The polarizer includes multiple alternating oriented layers of at least first and second polymeric materials having respective nonzero stress optical coefficients which are sufficiently different to produce a refractive index mismatch between the first and second polymeric materials in a first plane which is different from the refractive index mismatch between the first and second polymeric materials in a second plane normal to the first plane. The refractive index mismatch in the first plane is preferably at least 0.03.

Birefringent interference polarization

Birefringent interference polarizer

Methods and apparatus are provided for making multilayer plastic articles. Initially, two or more streams of diverse thermoplastic materials are provided. Layers are formed from these streams and are arranged in a layered first composite stream. The first composite stream may be directly formed into a desired configuration by a molding process or may be manipulated to form a second composite stream having an increased number of layers before being formed into the desired configuration. The resulting articles are comprised of a number of discrete and substantially continuous layers.

Method and apparatus for producing multilayer plastic articles

A formable multilayer reflective polymeric body which has a substantially uniform broad bandwidth reflectance over substantially the entire range of the visible spectrum to provide a substantially uniform reflective appearance is provided. The body includes at least first and second diverse polymeric materials, the body comprising a sufficient number of alternating layers of the first and second polymeric materials such that at least 40% of visible light incident on the body is reflected. A substantial majority of the individual layers of the body have optical thicknesses in the range where the sum of the optical thicknesses in a repeating unit of the polymeric materials is greater than about 190 nm, and the first and second polymeric materials differ from each other in refractive index by at least about 0.03.

Formable reflective multilayer body

An all-polymeric ultraviolet light reflective film which is lower in cost than previously used reflector materials, is weather resistant, and which does not absorb significant amounts of solar ultraviolet energy is provided. The film includes a sufficient number of alternating layers of at least first and second diverse polymeric materials which have an average percent transmission of greater than about 50% between wavelengths of 300-400 nm. A substantial majority of the individual layers of the film have optical thicknesses in the range where the sum of the optical thicknesses in a repeating unit of the polymeric materials is between about 0.15 .mu.m to about 0.228 .mu.m, and the first and second polymeric materials differ from each other in refractive index by at least about 0.03 in the wavelength range of from about 300-400 nm. The reflective film is useful as a reflective material in solar detoxification systems, as a protective material in indoor and outdoor lighting systems, as a UV mirror in the fields of medical imaging, astronomical telescopes, and microscopy or in chemical reactions using UV radiation.

All-polymeric ultraviolet light reflecting film

A blow molded multilayer plastic article having a large number of layers is formed. First and second diverse thermoplastic streams are extruded into a coextrusion feedblock. In the feedblock the streams are divided into multiple streams and arranged into a first composite stream having a substantially uniform distribution of the layers. The first stream is fed into an interfacial surface generator in which the stream is manipulated to form a second composite stream having even more layers of substantially uniform thickness. This second stream is then formed into a preform such as by injection molding and this preform is blow molded. The second composite stream and preform are formed so that the layers of first and second materials lie generally parallel to a critical surface and possess substantial uniformity when blow molded.

Method for producing blow molded multilayer plastic articles

Methods and apparatus for generating, and then precisely controlling, layer thickness gradients in multilayered polymeric reflective bodies are provided. The creation of such gradients is useful in tailoring multilayer bodies to reflect and/or transmit desired wavelengths of light. Both thermal and mechanical methods, as well as combinations thereof, are used.

Layer thickness gradient control in multilayer polymeric bodies

Methods and apparatus are provided for making multilayer plastic articles. Initially, two or more streams diverse thermoplastic materials are provided. Layers are foraged from these streams and are arranged in a layered first composite stream. The first composite stream may be directly formed into a desired configuration by a molding process or may be manipulated to form a second composite stream having an increased number of layers before being formed into the desired configuration. The resulting articles are comprised of a number of discrete and substantially continuous layers.

The present invention provides a two-component infrared reflecting film which reflects light in the infrared region of the spectrum while suppressing second, third and fourth order reflections in the visible spectrum. The film comprises alternating layers of first (A) and second (B) diverse polymeric materials having a six layer alternating repeat unit with relative optical thicknesses of about .778A.111B.111A.778B.111A.111B. The polymeric materials differ from each other in refractive index by at least about 0.03.

Two component infrared reflecting film

A method for the production of a lamellar reflective polymeric body is provided and includes the steps of providing a first stream of a first heat plastified polymeric material and a second stream of a second heat plastified polymeric material, and encapsulating discrete portions of the first polymeric material in the second polymeric material by coextruding the polymeric materials to form a plurality of ribbon-like layers of the first polymeric material within a matrix of the second polymeric material to form the reflective polymeric body. The layers of the first polymeric material are arranged to have their major interfaces aligned substantially parallel to the major surfaces of the body such that at least 30% of light incident on the body is reflected. The ribbon-like layers may be further divided into a series of platelet-like layers to produce layers which are discontinuous in all major planar dimensions by passing the ribbon-like layers through a reciprocating feed plate or valve.

Method of producing a lamellar polymeric body

A multilayered reflective body which is thermoformable and capable of being fabricated into films, sheets and a variety of parts while maintaining a uniform reflective appearance is provided. The reflective polymeric body includes at least first and second diverse polymeric materials of a sufficient number of alternating layers of the first and second polymeric materials such that at least 30% of the light incident on the body is reflected. A substantial majority of the individual layers of the body have an optical thickness of not more than 0.09 micrometers or not less than 0.45 micrometers, and adjacent layers of the first and second polymeric materials differ from each other in refractive index by at least about 0.1. The reflective body may be fabricated into sheets, mirrors, noncorroding metallic appearing articles and parts, reflectors, reflective lenses, and the like.

Optically dissimilar composition for polymeric reflective bodies

A process and apparatus for the coextrusion of a multilayer polymeric body is provided which incorporates protective boundary layers into the body, protecting the layers from instability and breakup during layer formation and multiplication. The process includes the steps of providing at least first and second streams of heat plastified extrudable thermoplastic material which are combined to form a composite stream having the first substreams and second substreams interdigitated. A third stream of heat plastified thermoplastic material is supplied to the exterior surfaces of the composite stream to form protective boundary layers adjacent the walls of the coextrusion apparatus through which the heat plastified polymer streams pass. Layer instability and breakup are avoided using process conditions which would otherwise adversely affect the optical and/or mechanical properties of the articles which are formed.

Growing community of inventors

Midland, MI, United States of America

Walter J Schrenk