Patent Application
20070287028
In the drawings, the same or similar reference numbers identify similar elements.
Preferably, the plastic substrate 22 is transparent. However, it may in some instances be translucent, opaque or a combination of these. The plastic substrate 22 can be formed of a variety of different thermoplastic or thermoset polymeric resins known to those skilled in the art. These polymeric resins include, but are not limited to, polycarbonate, acrylic, polyacrylate, polyester, polysulfone, polyurethane, silicone, epoxy, polyamide, polyalkylenes, acrylonitrile-butadiene-styrene (ABS) as well has copolymers, blends, and mixtures thereof. The plastic substrate 22 may further include various additives such as colorants, Theological control agents, mold release agent, antioxidants, ultraviolet absorbing (UVA) molecules, and infrared (IR) absorbing or reflecting pigments, among others.
The luminescent layer 24 comprises a phosphorescent or fluorescent ink that is capable of producing luminescence after absorbing radiant energy or other type of energy. The luminescent layer 24 may be a band, strip, border, or decorative pattern applied by screen printing, inkjet printing, mask & spray, or any other technique known to those skilled in the art. The luminescent layer 24 may be cured by air drying, UV absorption, thermal absorption, condensation addition, thermally driven entanglement, or cross-linking induced by cationic or anionic species.
The phosphorescent or fluorescent ink is preferably formed of a polymeric binder or resin and a phosphorescent pigment, a fluorescent dye, a fluorescent pigment, or a mixture of both, dispersed in a carrier liquid. The carrier liquid may comprise a single solvent or a mixture of solvents. Other additives, such as rheological control agents, antioxidants, surfactants, and biocides, among others, may also be present in the ink.
The polymeric binder of the phosphorescent or fluorescent ink may be any polymer suitable for adhering to the plastic substrate (base layer) 22 or a plastic film (further discussed below) used in the formation of the self-illuminating glazing panel. Examples of polymeric binders or resins include, but are not limited to polycarbonate, acrylic, polyacrylate, polyester, polysulfone, polyurethane, silicone, epoxy, polyamide, polyalkylenes, acrylonitrile-butadiene-styrene (ABS) as well has copolymers, blends, and mixtures thereof. Preferably, the polymeric binder in the phosphorescent or fluorescent ink is substantially similar to the polymeric resin present in any ink or coating used to form an optional functional layer in the self-illuminating glazing panel, as discussed below.
Phosphorescent pigments include, but are not limited to strontium oxide aluminates, sulphides of calcium, strontium, zinc, or barium doped with copper, bismuth, or manganese, and radioisotopes, such as Radium or Tritium. A specific example of a phosphorescent pigment is strontium oxide aluminate available as LumiNova® from Nemoto & Co. Ltd. (Tokyo, Japan).
Suitable fluorescent dyes include, but are not limited to, sodium fluorescein, rhodamine, fluoresceine, resorcinolphthalein, and conjugated derivatives of stilbene and benzimidazole. Fluorescent pigments include, but are not limited to, organic pigments and minerals that absorb short wavelengths and long wavelengths of light. Examples of long wavelength absorbing fluorescent minerals include agate (white-blue), magnesite (white-blue), calcite (red), fluorite (yellow), and scapolite (pink). Examples of short wavelength absorbing fluorescent minerals include ruby (red), halite (red), gypsum (yellow), diamond, and adamite (green). A specific example of an organic fluorescent pigment is the aldazine pigment (yellow) available as Lumogen® Yellow S 0790 from BASF (Germany).
Phosphorescence is a form of photoluminescence stimulated by the absorption of light in the UV-Vis-NIR spectral region. Phosphorescent pigments absorb light at wavelengths represented by this spectral region, which is then remitted slowly over time, typically as photons of longer wavelengths of light. Phosphorescent pigments are known to “glow in the dark” releasing the absorbed light over minutes or hours after the light source has been removed. When phosphorescent pigments are integrated with a self-illuminating glazing panel of a vehicle, the excitation light source may typically be the headlights of other vehicles, as well as streetlights and other light sources external to the vehicle.
The phosphorescent effect is highly dependent upon the selection of the pigments, the light absorption properties of the self-illuminating glazing panel, and the intensity of the light absorbed. The type of pigment selected, preferably, absorbs light in a portion of the spectral region that is substantially different than the portion of the region being effectively filtered or absorbed by the plastic substrate, plastic film, or weatherable layer. For example, polycarbonate is an effective filter of any UV radiation having a wavelength below about 380 nanometers. In addition, the photolytic degradation of polycarbonate upon exposure to UV radiation exhibiting a wavelength of 290 to 340 nanometers, requires the weatherable layer to absorb or reflect these wavelengths of light, thereby, protecting the underlying plastic panel and plastic film. Thus, in this specific case, it would be preferred that the phosphorescent pigments present in the luminescent layer absorb a wavelength of light that is greater than about 380 nanometers.
The luminescent layer may be comprised of a mixture of phosphorescent and fluorescent pigments. In this embodiment, the light absorbed and re-emitted by the fluorescent pigments occurs over a very rapid time frame with respect to the time frame over which light is re-emitted by the phosphorescent pigments. This rapid re-emission of fluorescent light causes the self-illuminating glazing panel to “glow”.
Fluorescence is a form of photoluminescence that occurs on a substantially faster time scale than phosphorescence. In fluorescence, the emitted light is always of a longer wavelength than the excitation or incident light. The emission of fluorescent light continues to occur as long as the external light source is present. If the exciting radiation is stopped, then the occurrence of fluorescence ceases. A more thorough molecular treatment of both phosphorescence and fluorescence is available to those skilled in the art in the form of a Jablonski Energy Diagram. Similar to phosphorescence, the fluorescent effect is highly dependent upon the selection of the pigments, the light absorption properties of the self-illuminating glazing panel, and the intensity of the light absorbed. The fluorescent pigment utilized in the luminescent layer of a self-illuminating panel preferably absorbs light in a portion of the spectral region different from the portion of the region that is filtered or absorbed by the plastic substrate, plastic film, or the weatherable layer.
The use of phosphorescent pigments is preferable over the use of fluorescent pigments due to the associated longer timeframe for emitting light.
An optional functional layer 26 may be placed onto the surface of the luminescent layer 24. This optional functional layer 26 may provide multiple functionality to the self-illuminating glazing panel 18. For example, the functional layer 26 may comprise a decorative layer, such as a black-out or fade-out layer in order to hide the bonding system used to adhere the panel to the vehicle. Other functionalities provided by the optional functional layer 26 may include, but are not be limited to, logos, defrosters or heater grids, antennas, solar control, electroluminescence, conductive films, photochromic films, or electrochromic films. The optional functional layer 26 may cure by air drying, UV absorption, thermal absorption, condensation addition, thermally driven entanglement, or cross-linking induced by cationic or anionic species.
The weatherable layer 28, which protects the self-illuminating glazing panel from environmental elements, such as UV radiation and moisture, may comprise silicones, polyurethanes, acrylics, polyesters, epoxies, and mixtures or copolymers thereof. It will be apparent to one skilled in the art that the weatherable layer 28 may include other suitable materials that impart weatherability to the self-illuminating glazing panel. Weatherable layer 28 may be extruded, cast as thin films, or applied as a discrete coating. The weatherable layer 28 may be a single layer or a combination of multiple sub-layers 27. A specific example of a weatherable layer 28 comprising multiple sub-layers 27 includes a combination of an acrylic primer (SHP401, GE Silicones, Waterford, N.Y.) and a silicone hard-coat (AS4000, GE Silicones). The weatherable layer 28 may further comprise additional additives including colorants (tints), rheological control agents, antioxidants, ultraviolet absorbing (UVA) molecules, and IR absorbing or reflecting pigments, among others. Due to the decreased amount of UV radiation impinging on the surface of the window facing the interior of the car, the weatherable layer 28′ present on the interior side of the self-illuminating glazing panel is optional.
The weatherable layer 28 may be applied by dip coating, flow coating, spray coating, curtain coating, or any other techniques known to those skilled in the art. The thickness of the weatherable layer 28 may range from about 2 micrometers to several mils (1 mil=25.4 micrometers), with about 6 micrometers to 1 mil being preferred. The weatherable layer 28 may cure by air drying, UV absorption, thermal absorption, condensation addition, thermally driven entanglement, or cross-linking induced by cationic or anionic species.
The abrasion resistant layer 29 may comprise a single layer or multiple sub-layers 30. The abrasion resistant layer 29 may be comprised of aluminum oxide, barium fluoride, boron nitride, hafnium oxide, lanthanum fluoride, magnesium fluoride, magnesium oxide, scandium oxide, silicon monoxide, silicon dioxide, silicon nitride, silicon oxy-nitride, silicon oxy-carbide, hydrogenated silicon oxy-carbide, silicon carbide, tantalum oxide, titanium oxide, tin oxide, indium tin oxide, yttrium oxide, zinc oxide, zinc selenide, zinc sulfide, zirconium oxide, zirconium titanate, or a mixture or blend thereof. Preferably, the abrasion resistant layer 29 is comprised of a composition of SiOx or SiOxCyHz depending upon the amount of carbon and hydrogen atoms that remain in the deposited layer. In this regard, the abrasion resistant layer 29 resembles a “glass-like” coating.
The abrasion resistant layer 29 may be applied by any suitable technique known to those skilled in the art including techniques involving the deposition of a film from reactive species, such as but not limited to those employed in vacuum-assisted deposition processes. Examples of suitable coating processes include, but are not limited to, plasma-enhanced chemical vapor deposition (PECVD), expanding thermal plasma PECVD, plasma polymerization. photochemical vapor deposition, ion beam deposition, ion plating deposition, cathodic arc deposition, sputtering, evaporation, hollow-cathode activated deposition, magnetron activated deposition, activated reactive evaporation, thermal chemical vapor deposition, and any known sol-gel coating process. The thickness of the abrasion layer 29 may range from about 1 micrometer to 1 mil with about 3 micrometers to 10 micrometers being preferred. Optionally, a similar abrasion layer 29′ may be applied to the interior of the glazing panel.
The weatherable layer 28 and abrasion resistant layer 29 may be combined to form a layered glazing system. Examples of layered glazing systems, include but are not limited to the acrylic/silicone/“glass-like” systems offered by Exatec LLC (Wixom, Mich.) as Exatec® 500, Exatec® 900, and Exatec® 900vt glazing systems.
Another embodiment of the present invention includes the incorporation of a decorative film as part of the various layers in the self-illuminating glazing panel using film insert molding (FIM) techniques. This decorated film may comprise a plastic film along with the luminescent layer and any optional functional layers. In forming the panel, the decorated film is placed onto tooling of an injection mold with the luminescent and optional functional layers facing away from the surface of the tooling and toward the cavity defined by the mold. A plastic resin is then injected into the mold to encapsulate the luminescent layer and any optional functional layer between the plastic resin and the film.
In a preferred embodiment, the luminescent layer 24 is printed by a screen printing process. In the screen printing process, a fine mesh screen equipped with a stencil according to the desired shape of the luminescent layer 24, is placed parallel with the plastic substrate 22. The screen is then deposited with luminescent ink, followed by forcing of the luminescent ink through the openings of the stencil on the screen using a squeegee that is drawn across the surface of the screen. After the squeegee passes the stencil region, the tension of the stretched screen along with the off-contact distance between the screen and the plastic substrate 22 allows the screen to separate from the surface of the substrate leaving the luminescent layer 24 deposited onto the surface of the substrate. It will be apparent to those skilled in the art that other techniques such as inkjet printing or mask and spray may also be used for providing the luminescent layer 24 onto the plastic substrate 22.
At step 44, any optional functional layers 26 are applied over the luminescent layer 24. A functional layer 28 can be applied by screen printing, inkjet printing, mask & spray, spray coating, or any other techniques known to those skilled in the art. At step 45, the weatherable layer 28 is applied to the glazing panel. The weatherable layer 28 may be applied by dip coating, flow coating, spray coating, curtain coating, or any other techniques known to those skilled in the art. At step 46, the abrasion layer 29 is applied to the glazing panel. The abrasion layer 29 is applied by any suitable technique known to those skilled in the art, including techniques involving the deposition of a film from a reactive species, e.g., vacuum-assisted deposition processes. At step 47, both a final inspection and finishing of the self-illuminating glazing panel 18 are carried out. The finishing of the self-illuminating glazing panel may include, but need not be limited to, such operations as the sanding or milling of panel edges, the attachment of positioning clips, spacers, or fasteners, the application of an adhesive primer and adhesive, or the cutting of holes for attachments, such as wipers.
At step 53, the decorated, plastic film is placed into the cavity of a mold and the plastic substrate 22 is back molded onto the film, thereby encapsulating the luminescent layer 24 and any optional functional layers 36. This molding process is known to those skilled in the art as film insert molding (FIM). At step 54, the molded plastic substrate 22 is removed from the mold, inspected, and any preliminary processing is carried out such as cleaning, which includes the elimination of static electrical charges. At step 55, the weatherable layer 28 is applied to the glazing panel. The weatherable layer 28 may be applied by dip coating, flow coating, spray coating, curtain coating, or any other technique known to those skilled in the art. At step 56, the abrasion resistant layer 29 is applied to the glazing panel. The abrasion resistant layer 29 may be applied by any suitable technique known to those skilled in the art including but not limited to techniques involving the deposition of a film from a reactive species, e.g., a vacuum-assisted deposition process. At step 57, both a final inspection and finishing of the self-illuminating glazing panel 18 are carried out.
In as much as the foregoing disclosure is intended to enable one skilled in the pertinent art to practice the present invention, it should not be construed to be limited thereby, but should be construed to include such aforementioned obvious variations and be limited only by the spirit and scope of the following claims.
