Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/18—Manufacture of films or sheets
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21S—NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
  • F21S41/00—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps
  • F21S41/30—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps characterised by reflectors
  • F21S41/37—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps characterised by reflectors characterised by their material, surface treatment or coatings
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
  • F21V7/00—Reflectors for light sources
  • F21V7/22—Reflectors for light sources characterised by materials, surface treatments or coatings, e.g. dichroic reflectors
  • F21V7/24—Reflectors for light sources characterised by materials, surface treatments or coatings, e.g. dichroic reflectors characterised by the material
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
  • F21V7/00—Reflectors for light sources
  • F21V7/22—Reflectors for light sources characterised by materials, surface treatments or coatings, e.g. dichroic reflectors
  • F21V7/28—Reflectors for light sources characterised by materials, surface treatments or coatings, e.g. dichroic reflectors characterised by coatings
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
  • G02B1/04—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of organic materials, e.g. plastics
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/02—Diffusing elements; Afocal elements
  • G02B5/0205—Diffusing elements; Afocal elements characterised by the diffusing properties
  • G02B5/0236—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place within the volume of the element
  • G02B5/0247—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place within the volume of the element by means of voids or pores
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/02—Diffusing elements; Afocal elements
  • G02B5/0273—Diffusing elements; Afocal elements characterized by the use
  • G02B5/0284—Diffusing elements; Afocal elements characterized by the use used in reflection
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
  • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
  • G02F1/1333—Constructional arrangements; Manufacturing methods
  • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
  • G02F1/133553—Reflecting elements
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2027/00—Use of polyvinylhalogenides or derivatives thereof as moulding material
  • B29K2027/12—Use of polyvinylhalogenides or derivatives thereof as moulding material containing fluorine
  • B29K2027/18—PTFE, i.e. polytetrafluorethene, e.g. ePTFE, i.e. expanded polytetrafluorethene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2327/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers
  • C08J2327/02—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment
  • C08J2327/12—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
  • C08J2327/18—Homopolymers or copolymers of tetrafluoroethylene
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
  • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
  • G02F1/1333—Constructional arrangements; Manufacturing methods
  • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
  • G02F1/133504—Diffusing, scattering, diffracting elements

Definitions

• the present invention relates to surfaces used to reflect light and particularly to highly light reflectant surfaces for the purpose of enhancing the efficiency of chambers using visible and/or ultraviolet light to impart changes to materials or bodies placed in them 2 Description of Related Art
• photoinduced material changes can be created and controlled through various types of specialized optical equipment
• This equipment although it differs from application to application, shares some common components such as a light source, typically a UV lamp, a reflector to direct and maximize light radiation onto the sample material, and a chamber in which to partially or completely house or contain the photoinduction process
• a light source typically a UV lamp
• a reflector to direct and maximize light radiation onto the sample material
• a chamber in which to partially or completely house or contain the photoinduction process
• the reflector is incorporated into the walls of the chamber
• the nature of the reflectant material may be critical to maximize the efficiency of the system The higher the reflectance of the reflectant material, the more light energy is available to be redirected towards the sample material, where photoinduction is desired to take place
• Another photoinduction application utilizes intense ultraviolet radiation in the presence of an oxidant such as hydrogen peroxide for the purpose of breaking down hazardous molecules into simpler and safer compounds
• This oxidation chamber utilizes a UV reflective surface on the walls parallel to the lamps
• the composition of these panels or coatings is selected for several properties, which include UV reflectivity, corrosion resistance, abrasion resistance, and ease of application and installation
• PTFE polytetrafluoroethylene
• PTFE polytetrafluoroethylene
• reflectance performance is relatively poor except in the 250-350 nanometer regions using relatively thick cross sections
• photoinduction chambers which utilize reflectors other than those mentioned above
• One example is what is commonly known as a "suntanning booth," which directs UV light towards a user's skin to cause pigmentation (color change) of the skin
• Another example is an indoor actinic test chamber for the accelerated testing of UV stability of polymers such as the color stability of plastics
• the present invention is an improved material and method for providing improved reflectivity of UV-Vis light in a photoinduction chamber which incorporates a UV and/or visible lamp
• the invention employs a reflectant material comprising an expanded polytetrafluoroethylene (PTFE) having polymeric nodes interconnected by fibrils defining microporous voids therein
• PTFE polytetrafluoroethylene
• the reflectant material is mounted within the chamber such that light from the lamp strikes and reflects from the reflectant material to provide efficient and effective use of the light within the chamber
• PTFE structure of the reflectant material used in the present invention provides extremely high reflectivity, with significantly better than 95% reflectance of light provided even at relatively thin material cross sections
• the material of the present invention has demonstrated higher diffuse reflectivity than the best diffuse reflective materials presently employed Equally important, the material employed in the present invention demonstrates many other properties that make it particularly desirable for use as a reflectant material in photoinduction cr ambers
• the material is highly flexible, allowing a multiple sided cavity or
• Figure 1 is a scanning electron micrograph (SEM), enlarged 5000 times, showing the surface of a light reflectant material of a commercially available reflective material,
• Figure 7 is a graph plotting the reflectance verses wavelength of various structures of embodiments of the reflectant materials of the present invention.
• Figure 12 is a top plan view of a conventional polished aluminum reflector used in a UV curing lamp system
• PTFE reflectant material Commercially available today is that sold under the trademark SPECTRALON by Labsphere, Inc., of North Sutton, NH
• This material comprises a granular polytetrafluoroethylene material that is lightly packed and then molded into a rigid block
• Figure 1 is a scanning electron micrograph (SEM) of a surface of a 1/2 inch thick reflectant sheet of SPECTRALON material While this material provides good reflectivity of visible and near IR light, its reflectance diminishes in the UV wavelengths below 325 nanometers and it has a number of drawbacks that constrain its use Among the perceived problems with this material are difficulty in processing due to its rigidity, especially where non- planar reflectant surfaces are required, limited range of effective light reflectance across UV-visible and IR light spectrum, relatively thick minimum thicknesses (i e , its effective reflectance diminishes at thicknesses of less than about 4 mm), and less than optimum reflectivity
• This expanded PTFE material comprises a microporous structure of microscopic polymeric fibrils (i e , thread ⁇ like elements) interconnecting polymeric nodes (i e , particles from which fibrils emerge)
• This material 10 comprises polymeric nodes 12 and numerous fibrils 14 extending from the nodes 12
• numerous microporous voids 16 are provided within the material 10
• expansion PTFE it is intended to include any PTFE material having a node and fibril structure, including in the range from a slightly expanded structure having fibrils extending from relatively large nodes of polymeric or other material, to an extremely expanded structure having fibrils merely intersect with one another at nodal points
• the lubricant may then be removed, such as through volatilization, and the dry coherent extrudate sheet is expanded rapidly in at least one direction about 1 1 to 50 times its original length (with about 1 5 to 2 5 times being preferred) Expansion may be accomplished by passing the dry coherent extrudate over a series of rotating heated rollers or heated plates at a temperature of between about 100 and 325°C, such as through the method taught in United States Patent 3,953,566 Alternatively, the extruded sheet may be expanded in the manner described in United States Patent 4 902,423 to Bacino, prior to removal of the lubricant
• the material may be further expanded at a ratio of 1 1 1 to 50 1 (with 5 1 to 35 1 being preferred) to form a final rflicroporous sheet
• the sheet is biaxially or multi-axially expanded so as to increase its strength in both its longitudinal and transverse directions
• the material may be subjected to an amorphous locking step by exposing it to a temperature in excess of 340°C
• This structure exhibits a relatively "fine” structure with fibrils 14 oriented in both x and y directions, and small nodes 12 where the fibrils intersect
• Still another embodiment of the present invention is shown in the SEM of Figure 3
• the expanded PTFE has been expanded in only the longitudinal direction
• the fibrils 14 are oriented predominantly in a longitudinal direction
• the present invention demonstrates extremely high reflectivity When compared to aluminum, the present material of choice for photoinduction chamber reflectors, the reflectant material of the present invention exhibited substantially higher reflectivity Furthermore, the material exhibits a very predictable, flat-line reflective response across a wide spectrum of light
• the present invention may comprise single or multiple layers of expanded PTFE, or may comprise a laminate of one or more layers of expanded PTFE and a backing support material Since the expanded PTFE membrane alone tends to be susceptible to stretching and distortion, for some applications it may be preferred that the membrane be mounted to a support layer, such as through lamination to a flexible woven or non-woven material, that will help maintain the shape of the image layer during use
• a support layer is applied by applying an adhesive material, such as moisture curable polyurethane or solvated polyurethane, to the expanded PTFE membrane and then applying the adhesive-coated expanded PTFE membrane to a flexible backing material (e g , polyester, polypropylene, MYLAR®, KEVLAR®, nylon, etc )
• a flexible backing material e g , polyester, polypropylene, MYLAR®, KEVLAR®, nylon, etc
• the two materials can then be bonded to each other under applied pressure, such as by rolling the material between one or more pairs of nip
• EXAMPLE 2 Another sheet of the present invention was produced in the same manner as Example 1 except for the following differences
• Sample 5 A composite sheet comprising about 150 layers of expanded PTFE sheets with the following properties
• the substrate that is being cured may not be able to withstand the relatively high infrared heat that can be delivered from the UV curing lamps
• EXAMPLE 6 Another application for the inventive material is in an indoor actinic test chamber These photoinduction chambers are utilized to conduct accelerated studies on the affect of UV light on various plastic materials
• a typical chamber 70 is described in ASTM test method D4674 and is shown in Figure 9
• the test chamber 70 is generally constructed of UV reflective aluminum 72 with a clear, chromate conversion coating
• An arched reflector 74 with a radius of 330 mm serves as the chamber roof
• a test drawer 76 made also of reflective aluminum is place 140 mm from the lower edge of a center bulb 78 Samples for evaluation are placed on the sample drawer 76 for a specified amount of exposure time
• the typical source light spectral energy distribution of the indoor accelerated test chamber is shown in Figure 10
• EXAMPLE 7 In another example the inventive material is employed in a UV curing lamp system
• the system used was a model F300 Ultraviolet Lamp System supplied by Fusion Systems Corporation, Rockville, MD
• the system as shown in Figure 11 incorporates a magnetron 80, a polished aluminum waveguide and reflector 82, a electrodeless mercury vapor lamp 84, and a conveyor belt 86
• the photoinduction chamber in this application can be identified as the partially enclosed area beneath the reflector and including the reflector and the portion of the conveyor belt under the reflector
• the system operates as follows
• the magnetron 80 is a diode vacuum tube in which the flow of electrons is controlled by an externally applied magnetic field to generate power at microwave frequencies
• the microwave energy is directed towards the electrodeless mercury vapor lamp 84
• the lamp is a closed quartz tube containing a small amount of mercury and an easily ionized starter gas
• the microwave energy in the form of a high frequency and high intensity electric field excites the gas inside the bulb to extremely high energy levels,
• a test was conducted by first establishing the light output of the system This was accomplished by utilizing a light sensor 94, such as an IL 390B

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• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Optics & Photonics (AREA)
• Chemical & Material Sciences (AREA)
• General Physics & Mathematics (AREA)
• General Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Nonlinear Science (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Mathematical Physics (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Crystallography & Structural Chemistry (AREA)
• Laminated Bodies (AREA)
• Optical Elements Other Than Lenses (AREA)
• Manufacture Of Macromolecular Shaped Articles (AREA)
• Physical Or Chemical Processes And Apparatus (AREA)
• Road Signs Or Road Markings (AREA)
• Vessels And Coating Films For Discharge Lamps (AREA)
• Treatments Of Macromolecular Shaped Articles (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

Country Status (7)

Cited By (2)

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Citations (4)

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• 1995
  • 1995-12-06 US US08/569,411 patent/US5689364A/en not_active Expired - Lifetime
• 1996
  • 1996-10-09 WO PCT/US1996/016142 patent/WO1997020882A1/en not_active Ceased
  • 1996-10-09 JP JP51299597A patent/JP4271727B2/ja not_active Expired - Lifetime
  • 1996-10-09 DE DE69606553T patent/DE69606553T2/de not_active Expired - Lifetime
  • 1996-10-09 CA CA002236803A patent/CA2236803C/en not_active Expired - Lifetime
  • 1996-10-09 AU AU72622/96A patent/AU712860B2/en not_active Expired
  • 1996-10-09 EP EP96934130A patent/EP0865460B1/en not_active Expired - Lifetime

Patent Citations (4)

Non-Patent Citations (2)

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