COLOR CHANGING MATERIAL

Abstract

Disclosed is a photochromic material that includes a first polymeric layer having a photochromic compound that is capable of being activated in response to a stimulus. The first polymeric layer is configured such that the activated photochromic compound becomes inactivated within 10 minutes, preferably within 5 minutes, most preferably within 1 minute, in the absence of said stimulus.

Claims

1. A photochromic material comprising a first polymeric layer comprising a photochromic compound that is capable of being activated in response to a stimulus, wherein the first polymeric layer is configured such that the activated photochromic compound becomes inactivated within 10 minutes in the absence of said stimulus.

2. The photochromic material of claim 1, wherein the first polymeric layer comprises a polyolefin polymer or co-polymer thereof or a polyurethane polymer or co-polymer thereof, or blends thereof.

3. The photochromic material of claim 2, wherein the polyolefin polymer or co-polymer thereof is polyethylene or polypropylene.

4. (canceled)

5. (canceled)

6. The photochromic material of claim 1, wherein the photochromic compound in the first polymeric layer is a chromene, a spiroxazine, a spiropyran, a fulgide, a fulgimide, an anil, a perimidinespirocyclohexadienones, a stilbene, a thioindigoid, an azo dye, or a diarylethene, or any combination thereof.

7. The photochromic material of claim 1, wherein the first polymeric layer is configured to have a first color when the photochromic compound is in its inactive form and a second color when the photochromic compound is in its active form, wherein the first and second colors are different.

8. The photochromic material of claim 7, wherein the first color and second colors are each optically clear, red, orange, yellow, green, blue, violet, white, black, or any shade or variation or combination thereof.

9. The photochromic material of claim 8, wherein the first color is optically clear.

10. The photochromic material of claim 1, wherein the stimulus is electromagnetic radiation.

11. The photochromic material of claim 10, wherein the electromagnetic radiation is ultraviolet light or visible light.

12. The photochromic material of claim 1, wherein the photochromic material is in contact with or adhered to a substrate.

13. The photochromic material of claim 12, wherein the substrate is a second polymeric layer.

14. The photochromic material of claim 11, wherein the second polymeric layer comprises a polycarbonate polymer or copolymer thereof, a polysulphone polymer or co-polymer thereof, a cyclo olefin polymer or co-polymer thereof, a thermoplastic polyurethane polymer or co-polymer thereof, a thermoplastic polyolefin polymer or co-polymer thereof, a polystyrene polymer or co-polymer thereof, a poly(methyl)methacrylate polymer or co-polymer thereof, or any blends thereof.

15. The photochromic material of claim 14, wherein the second polymeric layer comprises a polycarbonate polymer or co-polymer thereof.

16. The photochromic material of claim 15, wherein the second polymeric layer comprises a polymeric blend comprising said polycarbonate polymer and a polyester polymer.

17. The photochromic material of claim 16, wherein the second polymeric layer comprises a bisphenol A-sebacic acid co-polymer.

18. The photochromic material of claim 11, wherein the second polymeric layer does not include a photochromic compound.

19. The photochromic material of claim 11, wherein the second polymeric layer comprises a second photochromic compound selected from a chromene, a spiroxazine, a spiropyran, a fulgide, a fulgimide, an anil, a perimidinespirocyclohexadienones, a stilbene, a thioindigoid, an azo dye, or a diarylethene, or any combination thereof.

20. The photochromic material of claim 11, wherein the second polymeric layer comprises a non-photochromic dye, an irreversible photochromic compound, or pigment.

21-24. (canceled)

25. A photochromic material comprising: (i) a first polymeric layer comprising a first photochromic compound that is capable of being activated in response to a first stimulus, wherein the first polymeric layer is configured to change from color 1 to color 2 upon exposure to the first stimulus and back to color 1 upon removal of the first stimulus, wherein color 1 and color 2 are different; and (ii) a second polymeric layer comprising one or more additional compounds, wherein at least one of the additional compounds is a second photochromic compound, a thermochromic compound, an electrochromic compound, a permanent dye, pigment, an irreversible photochromic compound, or any combination thereof, wherein the first polymeric layer is coupled to the second polymeric layer.

26-57. (canceled)

58. An article of manufacture or surface comprising the photochromic material of claim 1, wherein the article of manufacture or surface is paint, wallpaper, floor or roof tile, an appliance, a table, an automotive part, an outdoor surface, a sporting equipment, or eyewear.

59. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] FIG. 1 is an illustration of a polymeric matrix that includes free-volume or space for a photochromic compound or dye to change its shape from an inactivated form to an activated form in response to light such as ultraviolet light.

[0041] FIG. 2 is an illustration of various applications for the multi-layered photochromic material of the present invention.

[0042] FIG. 3 are thermochromic polymers that can be used with the multi-layered photochromic material of the present invention.

[0043] FIG. 4 is an illustration of a process for making a PC-PE laminate structure resulting in an optically clear fused PC-PE film.

[0044] FIG. 5 is an illustration of a color wheel.

[0045] FIG. 6A is a cross-sectional views of a bi-layer photochromic material of the present invention.

[0046] FIG. 6B is a cross-sectional views of a bi-layer photochromic material with a substrate.

[0047] FIG. 6C is a cross-sectional views of a bi-layer photochromic material of the present invention with adhesive.

[0048] FIG. 6D is a cross-sectional views of a bi-layer photochromic material of the present invention with adhesive and substrate.

[0049] FIG. 6E is a cross-sectional views of a multilayer photochromic material of the present invention which may include a protective layer as well.

[0050] FIG. 7 is a schematic of a design of a polycarbonate-polyethylene (PC-PE) laminate with more layers of different polymers for additional properties.

[0051] FIG. 8 is an illustration of a tri-layered photochromic material of the present invention.

[0052] FIG. 9 is an illustration of a bi-layered photochromic material of the present invention.

[0053] FIG. 10 is an illustration of a bi-layered photochromic material of the present invention that includes an electrochromic layer.

[0054] FIG. 11 is an illustration of a mono-layered photochromic material of the present invention.

[0055] FIG. 12A is a graph of wavelength in nanometers versus percent transmittance of a material of the present invention that includes a high flow ductile (HFD) polycarbonate polymer and 500 ppm of dye-2197.

[0056] FIG. 12B is a graph of wavelength in nanometers versus percent transmittance of a material of the present invention that includes a HFD polycarbonate polymer and 500 ppm of Storm Purple.

[0057] FIG. 12C is a graph of wavelength in nanometers versus percent transmittance of a material of the present invention that includes a HFD polycarbonate polymer and 500 ppm of Sea Green.

[0058] FIG. 12D is a graph of wavelength in nanometers versus percent transmittance of a material of the present invention that includes a HFD polycarbonate polymer and 500 ppm of dye 2039.

[0059] FIG. 13A are images of a HFD film with spiroxazine dye and a commercial polyurethane coating after UV exposure

[0060] FIG. 13B is the HFD film with spiroxazine dye and the commercial polyurethane coating after 10-20 seconds.

[0061] FIG. 14A is an image of extruded high density polyethylene polymer (HDPE) with Sea Green dye after exposure to room light.

[0062] FIG. 14B is an image of extruded high density polyethylene polymer (HDPE) with Sea Green dye before exposure to room light.

[0063] FIG. 15A is a graph of wavelength in nanometers versus percent transmittance of a material of the present invention that includes a HDPE polymer and 1500 ppm of Sea Green dye.

[0064] FIG. 15B is a graph of wavelength in nanometers versus percent transmittance of a material of the present invention that includes a HDPE polymer and 500 ppm of Sea Green dye.

[0065] FIG. 15C is a graph of wavelength in nanometers versus percent transmittance of a material of the present invention that includes a HDPE polymer and 250 ppm of Sea Green dye.

[0066] FIG. 15D is a graph of wavelength in nanometers versus percent transmittance of a material of the present invention that includes a HDPE polymer and 125 ppm of Sea Green dye.

[0067] FIG. 16A is a graph of wavelength in nanometers versus percent transmittance of a commercial lens.

[0068] FIG. 16B is a graph of wavelength in nanometers versus percent transmittance of a commercial polyurethane coating.

[0069] FIG. 16C a graph of wavelength in nanometers versus percent transmittance of a material of the present invention that includes a HDPE polymer and 1500 ppm of Sea Green dye.

[0070] FIG. 16D a graph of wavelength in nanometers versus percent transmittance of a material of the present invention that includes a polycarbonate/polyethylene (HFD/HDPE) laminate and 1500 ppm of Sea Green dye.

DETAILED DESCRIPTION OF THE INVENTION

[0071] While previous attempts have been made to produce photochromic materials in response to external stimuli, the materials either (1) lacked sufficient response or switch times to change colors in response to or in the absence of a given stimulus or (2) were limited in the types of colors and stimuli that could be produced under given conditions.

[0072] As discussed above, the photochromic materials of the present invention offer solutions to these problems. One solution is a photochromic material that can be configured to rapidly change colors from a first color to a second color in response to the stimulus and then back to the first once the stimulus is removed. In particular aspects, the material can have fast-switching back properties (e.g., dye that has been activated in response to a given stimulus can switch back to its inactivated state in the absence of said stimulus within 10 minutes, preferably within 5 minutes, and more preferably within 4, 3, 2, 1, or less minutes). By way of example, a photochromic material can be structured to include a thermoplastic polymeric-based layer having at least one photochromic compound dispersed or solubilized throughout the matrix or positioned in a targeted area or areas of the matrix. This allows for the layer to change colors from color 1 to color 2 in response to a given stimulus (e.g., electromagnetic radiation) and back in the absence of said stimulus in a responsive or short time period, with the switch back occurring within 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, or less minutes. Another advantage of the invention is that by incorporating the fast-switching back layers (e.g., a skin layer) into a multilayer material (e.g., a lens) the desired effect of changing color in response to the stimulus and rapidly switching back when the stimulus is removed is achieved without the cost and inefficiencies associated with impregnating a polymer matrix such as polycarbonate lenses with a dye.

[0073] Another solution is the creation of a multi-layer material having individual photochromic layers that can change colors in response to given stimuli and quickly switches back when the stimuli are removed. In some embodiments, at least one of the layers does not change color in response to a given stimuli. In either instance, both solutions can be incorporated into a wide array of products, articles of manufacture, and applications in which color change is desired. By way of another example, a bi-layered material (or 3, 4, 5, 6, 7, 8, 9, 10, or more layers) can be structured such that one of the layers of the present invention includes a thermoplastic polymeric-based layer having at least one photochromic compound dispersed or solubilized throughout the matrix. This allows for the first layer to change colors from color 1 to color 2 in response to a given stimulus (e.g., electromagnetic radiation). The second layer of the present invention can be designed such that it changes colors (e.g., color 3 to color 4) in response to another stimulus (e.g., heat or electrical stimulus). Such a set-up could allow for a change in color from color 1 (e.g., optically clear) to color 2 (e.g., green) in response to sunlight. The second layer can have an initial non-stimulated color (i.e., color 3e.g., optically clear) that shifts to color 4 (e.g., red) in response to a certain heat level (e.g., greater than 30 C.). Thus, this non-limiting multi-layered material could change colors from optically clear to green in response to sunlight. Then, if the material is further subjected to a temperature of at least 30 C., the second layer could change its color from optically clear to red, thereby causing a color shift in the multi-layered material from green to yellow (red+green=yellow). If sunlight is removed but the heat stimulus remains, then the material could shift its color from yellow to red. Reducing the temperature of the material to less than 30 C. could cause the material to revert back to being optically clear. This type of multi-layered material could be applied to, for example, a white surface (e.g., a wall that is painted white). Thus, the wall would have a white appearance in the absence of sunlight at a room temperature of less than 30 C. If sunlight were to hit the wall, then the color of the wall would appear to shift from white to green. If the temperature of the room rises to at least 30 C., then the wall would appear to shift from green to yellow. If sunlight is removed from the wall (e.g., at night) but the temperature of the room is at least 30 C., then the wall would appear to have a red color. If the temperature of the room goes below 30 C., then the wall would again appear white. FIG. 2 provides a non-limiting illustration of the various set-ups and applications for use of the multi-layered color changing materials of the present invention.

[0074] These and other non-limiting aspects of the present invention are discussed in detail in the following sections.

A. Fast-Switching Back Color Changing Layers

[0075] In one instance of the present invention, there is disclosed a color changing material that can include a polymer or polymer blend (e.g., first polymer layer, film, and/or laminate) that is workable at a temperature that allows retention of the structural integrity of a photochromic dye and that also produces a polymeric matrix or layer having more free volume. While it was expected that photochromic dyes would switch quickly to an active state (e.g., colored state), it was unexpected and surprisingly found that the resulting film or layer had the ability to allow the activated dyes to switch back to their respective inactivated forms quickly (i.e., the film or layer had has fast-switching back properties such that a dye having been activated in response to a given stimulus switched back to its inactivated state in the absence of said stimulus within 10 minutes, preferably within 5 minutes, and more preferably within 4, 3, 2, 1, or less minutes). By comparison, conventional materials having such dyes (e.g., polycarbonate lenses having dyes impregnated into the top surface) switch back to their inactive form in the absence of a given stimulus in longer periods of time (i.e., greater than 10 minutes after a stimulus has been removed).

[0076] Polymers that are used to create such a polymeric layers or films include polyolefins (e.g., polypropylene, polyethylene, ethylene-propylene copolymers, propylene-butene copolymers, ethylene-propylene-butylene terpolymers, or blends thereof). Non-limiting examples include crystalline polypropylene, crystalline propylene-ethylene block or random copolymer, low density polyethylene, high density polyethylene, linear low density polyethylene, ultra-high molecular weight polyethylene, ethylene-propylene random copolymer, ethylene-propylene-diene copolymer, and the like. In particular aspects, the polyolefin can be modified with at least one functional group selected from a carboxyl, an acid anhydride, an epoxy groups or mixtures containing at least one of the foregoing functional groups. Polyolefins are commercially available from a wide range of sources, one of which is SABIC, which offers a variety of HDPE, LDPE, LLDPE, PP polymers, co-polymers, and blends thereof in a variety of grades, all of which are incorporated in the present application by reference. Polyolefins can be produced by Ziegler-Nana catalyst, metallocene catalyst, or any other suitable means known to those of skill in the art.

[0077] However, and in addition to said polyolefins, other polymers that can be used include polystyrenes, poly(methyl)methacrylates, polycarbonate copolymers (e.g, bisphenol A and sebacic acid based copolymers, etc.), polycarbonate blends (e.g., polycarbonate/polyester blends etc.), polyvinyl acetate, polyvinyl butyral, polyethylene terephthalate (PET), nylon, etc. Additionally, polymers obtained from one or more monomers selected from alkyl carbonates, multifunctional acrylates, multifunctional methacrylates, cellulose acetates, cellulose triacetates, cellulose acetate propionate, nitrocellulose, cellulose acetate balynete, vinyl alcohol, vinyl chloride, vinylidene chloride, diacylidene pentaerythritol, etc.

[0078] The resulting fast-switching back photochromic layers or films of the present invention have more free volume (see, e.g., FIG. 1) as compared to other polymers (e.g., thermoset or some polycarbonate polymers). Examples of products having such thermoset or polycarbonate polymer matrices lacking sufficient void space include automotive headlamp lenses, lighting lenses, sunglass lenses, eyeglass lenses, swimming goggles and SCUBA masks, safety glasses/goggles/visors including visors in sporting helmets/masks, windscreens in motorized vehicles (e.g., motorcycles, ATVs, golf carts), electronic display screens (e.g., e-ink, LCD, CRT, plasma screens), etc. Therefore, films or layers of such polymers and matrices having more free volume have not typically been used in such products. In the context of the present invention, however, it was surprisingly discovered that such films or layers due to their increased void space (See, FIG. 1) had the ability to allow photochromic compounds or dyes to quickly switch from an activated state (activated by a given stimulus) to an inactivated state (in the absence of said stimulus) in response to electromagnetic radiation (e.g., less than 10 minutes, 5 minutes or less, and 1 minute or less). The films of the present invention can therefore be beneficial to the aforementioned products to provide said products with color changing capabilities that can quickly change back to their beginning or inactivated color-state in the absence of a given stimulus. Still further, these films of the present invention can also be used with the more rigid substrates (e.g., wood, glass, cloth, paint, polymers and matrices (e.g., polycarbonates).

[0079] Notably, when the fast-switching back color changing layers of the present invention are used with such products or rigid substrates, the products or substrates have color changing capabilities without compromising the impact strength and/or optical clarity of the given product or substrate.

B. Additional Color Changing Layers

[0080] In addition to the fast-switching color changing layers discussed above in section A, additional color changing layers can be used in the context of the present invention. These additional layers can be used with the fast-switching color changing layers in Section A to obtain stacks or laminates of color changing layers to produce a material that is capable of changing various colors in response to a given stimuli. Alternatively, these additional layers can be used without the fast-switching color changing layers in Section A to obtain stacks or laminates of color changing layers to produce a material that is capable of changing various colors in response to a given stimuli.

[0081] In one instance, the additional color changing layers can include thermoplastic polymers which can become pliable or moldable above a specific temperature, and return back to a more solid state upon cooling. There are a wide range of various thermoplastic polymers, and blends thereof, that can be used to make a color changing layer or material of the present invention. Some non-limiting examples include polyolefins (e.g., polypropylene, polyethylene, ethylene-propylene copolymers, propylene-butene copolymers, ethylene-propylene-butylene terpolymers, or blends thereof), polystyrenes, poly(methyl)methacrylates, polycarbonate copolymers (e.g, bisphenol A and sebacic acid based copolymers, etc.), polycarbonate blends (e.g., polycarbonate/polyester blends etc.), polyvinyl acetate, polyvinyl butyral, polyethylene terephthalate (PET), polyurethane, nylon, and blends and co-polymers thereof etc. Additionally, polymers obtained from one or more monomers selected from alkyl carbonates, multifunctional acrylates, multifunctional methacrylates, cellulose acetates, cellulose triacetates, cellulose acetate propionate, nitrocellulose, cellulose acetate balynete, vinyl alcohol, vinyl chloride, vinylidene chloride, diacylidene pentaerythritol, and blends and co-polymers thereof.

[0082] In a preferred embodiment of the present invention, polycarbonates (PCs) are used in combination with the fast-switching color changing layers in Section A. PCs include a particular class of thermoplastic polymers that are commercially available from a wide variety of sources (e.g., Sabic Innovative Plastics (Lexan)). In a particularly preferred embodiment, Lexan can be used in the context of the present invention. PCs typically have high impact-resistance and are highly transparent to visible light, with light transmission properties that exceed many types of glass products. Preferred examples of PCs include dimethyl cyclohexyl bisphenol or high-flow ductile (HFD) polycarbonates (e.g., bisphenol-A polycarbonate, sebacic acid copolymer). Generally, polycarbonates are polymers that include repeating carbonate groups (O(CO)O). A well-known PC is bisphenol-A polymer, which has the following formula (I):

##STR00001##

However, all types of polycarbonates, co-polymers, and blends thereof are contemplated in the context of the present invention. By way of example, and in addition to the dimethyl cyclohexyl bisphenol and high-flow ductile (HFD) polycarbonates (e.g., bisphenol-A polycarbonate, sebacic acid copolymer) mentioned above, WO 2013/152292 (the contents of which are incorporated into the present specification by reference) provides a wide range of PCs that can be used. In particular, polycarbonates can include polymers having repeating structural carbonate units of formula (II):

##STR00002##

in which at least 60% of the total number of R.sup.1 groups contain aromatic moieties and the balance thereof are aliphatic, alicyclic, or aromatic. In an embodiment, each R.sup.1 is a C.sub.6-30 aromatic group, that contains at least one aromatic moiety.

C. Photochromic/Thermochromic/Electrochromic Compounds

[0083] Photochromic, thermochromic, and electrochromic compounds can be used with the fast-switching color changing layers of section A or the additional color changing layers of section B. In particular, such materials can be incorporated into these layers to provide the color-changing capabilities to said layers to obtain a desired color changing effect in response to a selected stimulus or selected stimuli (e.g., electromagnetic radiation, heat, electricity, or combinations thereof). Non-limiting examples of these materials are provided below.

[0084] 1. Photochromic Compounds

[0085] Photochromism typically refers to compounds that undergo a photochemical reaction where an absorption band in the visible part of the electromagnetic spectrum changes in strength or wavelength. This change results in the compound changing color (e.g., from water white to colored). In many cases, an absorbance band is present in only one form. The degree of change required for a photochemical reaction to be dubbed photochromic is that which appears visibly dramatic by visual inspection. Therefore, while the trans-cis isomerization of azobenzene is considered a photochromic reaction, the analogous reaction of stilbene is not. Given that photochromism is a species of a photochemical reaction, almost any photochemical reaction type may be used to produce photochromism with appropriate molecular design. Some of the most common processes involved in photochromism are pericyclic reactions, cis-trans isomerizations, intramolecular hydrogen transfer, intramolecular group transfers, dissociation processes and electron transfers (oxidation-reduction).

[0086] Another feature of photochromism is two states of the molecule should be thermally stable under ambient conditions for a reasonable time. For instance, nitrospiropyran (which back-isomerizes in the dark over 10 minutes at room temperature) is considered photochromic. All photochromic molecules back-isomerize to their more stable form at some rate, and this back-isomerization is accelerated by heating. There is therefore a close relationship between photochromic and thermochromic compounds. The timescale of thermal back-isomerization is important for applications, and may be molecularly engineered. Photochromic compounds considered to be thermally stable include some diarylethenes, which do not back isomerize even after heating at 80 C for 3 months.

[0087] Photochromic chromophores are dyes and operate according to well-known reactions. Molecular engineering to fine-tune their properties can be achieved relatively easily using known design models, quantum mechanics calculations, and experimentation. In particular, the tuning of absorbance bands to particular parts of the spectrum and the engineering of thermal stability have received much attention.

[0088] In the context of the present invention, a photochromic compound or dye refers to a molecule that can exhibit change in color under the influence of certain frequencies of light. By way of example, a photochromic compound or dye can change shape under the influence of light by absorbing said light, thereby resulting in a shift in the color of the compound (i.e., color change). The shift can be from a colorless or clear state to a colored state or from a first color to a second color or from a colored state to a colorless or clear state. Such compounds or dyes can also switch back from their activated state to their inactivated state by removal of the said light radiation and under the influence of temperature. Non-limiting examples of photochromic compounds or dyes that can be used in the context of the present invention (i.e. switches back and forth between an activated and inactivated state) include chromenes, spiroxazines, spiropyrans, fulgides, fulgimides, anils, perimidinespirocyclohexadienones, stilbenes, thioindigoids, azo dyes, a diarylethenes, napthopyrans, etc., or any combination thereof. In particular aspects, such dyes or molecules can be obtained from Vivimed Labs Europe Ltd. under the trade name ReversacolTM Photochromic Dyes, which offers a variety of dyes that can be activated in response to ultraviolet light spectrum. Some compounds or dyes cannot or are sufficiently slow to switch back to their inactivated state and thus are considered irreversible photochromic compounds.

[0089] Photochromic dyes can have the trivial names of Storm Purple, Aqua Green, Sea Green, Plum Red, Berry Red, Corn Yellow, Oxford Blue and the like. Corn Yellow and Berry Red are benzopyran compounds, while Storm Purple, Aqua Green, Sea Green, and Plum Red are spiro-oxazines. Generic structures of the spiro-oxazine dyes are represented by the formulas (II) to (IV):

##STR00003##

[0090] Naphthopyran dyes can be represented by the general formula (V):

##STR00004##

[0091] 2. Thermochromic Compounds

[0092] In the context of the present invention, thermochromic compounds include organic compounds or pigments that effectuate a reversible color change when a specific temperature threshold is crossed. Thermochromic pigments can include three main components: (i) an electron donating coloring organic compound, (ii) an electron accepting compound and (iii) a solvent reaction medium determining the temperature for the coloring reaction to occur. One example of a commercially available, reversible thermochromic pigment is ChromaZone Thermobatch Concentrates available from Thermographic Measurements Co. Ltd. Thermochromic pigments and the mechanism bringing about the temperature triggered color change are well-known in the art and are for example described in U.S. Pat. Nos. 4,826,550 and 5,197,958. Other examples of thermochromic pigments are described in U.S. Patent Application Publication No. 2008/0234644A1. Alternatively, the thermosensitive pigment may be of a microcapsule type which is known in the art of thermosensitive pigments.

[0093] 3. Electrochromic Compounds

[0094] Electrochromism is the phenomenon displayed by some chemical compounds that have a reversibly changeable color when a voltage is applied. The electrochromic material may not have a color in the absence of an electric field and then may display a certain color when an electric field is applied, for example, by an external source. Alternatively, the electrochromic material may have a color in the absence of an electric field and then may display no color when an electric field is applied. Examples of electrochromic materials include conjugated polymers, organic compounds such as pyridine, aminoquinone, and azine compounds, and inorganic compounds such as tungsten oxides, molybdenum oxides, and the like. Typically, these electro-optic changes occur in the visible region of the spectrum with the material switching colors upon a change in applied potential. Conjugated polymers are particularly useful in the context of the present invention due to their color tunability, high optical contrasts, fast switching speeds, and processability. FIG. 3 provides an illustration of various polymers that can be used in the context of the present invention, and their respective color changes in response to an electrical stimulus.

D. Permanent Colorants and Dyes

[0095] Colorants such as pigments can be used to impart a permanent color to a given layer of the multi-layered color changing materials of the present invention. By way of example, a transparent polymeric or non-polymeric layer can be given a permanent color by using a permanent pigment such that the layer does not exhibit reversible color shifting characteristics in response to a given stimulus such as light, heat, or electricity. Alternatively, such colorants can be used in combination with the aforementioned photochromic, thermochromic, and electrochromic materials such that the layer has a particular hue due to the colorant, but shifts color or increases the intensity of the hue in response to a given stimulus such as light, heat, or electricity. Non-limiting examples of pigments that can be used in any of the layers of the color changing materials of the present invention include metal-based pigments (e.g., cadmium pigments (e.g., cadmium yellow, cadmium red, cadmium green, cadmium orange, cadmium sulfoselenide), chromium pigments (e.g., chrome yellow and chrome green), cobalt pigments (e.g., cobalt violet, cobalt blue, cerulean blue, aureolin (cobalt yellow)), copper pigments (e.g., azurite, Han purple, Han blue, Egyptian blue, Malachite, Paris green, Phthalocyanine Blue BN, Phthalocyanine Green G, verdigris, viridian), iron oxide pigments (e.g., sanguine, caput mortuum, oxide red, red ochre, Venetian red, Prussian blue), lead pigments (e.g., lead white, cremnitz white, Naples yellow, red lead), manganese pigments (e.g., manganese violet), mercury pigments (e.g., vermilion), titanium pigments (e.g., titanium yellow, titanium beige, titanium white, titanium black), and (zinc pigments (e.g., zinc white, zinc ferrite)), or any combinations thereof. Non-limiting examples of other pigments include carbon pigments (e.g., carbon black, ivory black), clay earth pigments or iron oxides (e.g., yellow ochre, raw sienna, burnt sienna, raw umber, burnt umber), and ultramarine pigments (e.g., ultramarine or ultramarine green shade).

[0096] Organic compounds (e.g., synthetic or natural dyes) and irreversible photochromic compounds that impart permanent color to one or more layers can be used in combination with the photochromic, thermochromic and/or electrochromic materials. Non-limiting examples or permanent organic dyes include phthalones, pryophthalone dyes, perylene dyes etc., or any combination thereof. A non-limiting example of the perylene dye is anthra[2,1,9-def:6,5,10-def]diisoquinoline-1,3,8,10(2H,9H)-tetrone, 2,9-bis(2-ethylhexyl)-5,6,12,13-tetrakis(4-nonylphenoxy) (Chemical Abstract No. 1210881-03-0). These dyes and other dyes are described in U.S. Pat. No. 8,304,647 to Bhaumik et al. can be used as a non-photochromic dye. Non-limiting examples of pyrophthalone dyes is 1H-indene-1,3(2H)-dione, 4,5,6,7-tetrachloro-2-(2-pyridinyl) (CAS No. 343232-69-9). This dye and other dyes described in U.S. Patent Application Publication No. 2014-0357768 to Sharma et al. can be used as a non-photochromic dye. Non-limiting examples of irreversible photochromic compounds are commercially available from Olikrom Smart Pigments (France) and Sky-Rad Ltd. (Israel).

E. Methods of Making Photochromic Materials

[0097] The single or multi-layered color changing materials of the present invention can be made by straightforward and cost-efficient steps that are performed under conditions that reduce or prevent damage to the photochromic, electrochromic, or thermochromic materials.

[0098] 1. Making the Single Layered Photochromic Materials

[0099] A photochromic material can be made by the non-limiting procedure of combining a photochromic compound or dye material with a polymeric solution or oligomeric solution or mixture, casting or extruding a film therefrom, and, if required, at least partially setting the film. Polymer powder can be used (e.g., in Kg scale), and photochromic dye can be used in ppm level (see, e.g., Tables 6 & 7 below). Processing temperatures can range from 150-250 C.). The resulting polymeric film includes a polymer with a more void space when compared to the other layers. The thickness of this film can be modified as needed. In preferred aspects, the thickness of this film ranges from 10 m to 4 mm. In some embodiments, the photochromic dye, electrochromic material or thermochromic material and/or additional compounds are delivered to specific portions of the resulting polymeric film (for example, in the center of the film, around the exterior portions of the film, or dispersed throughout the film).

[0100] 2. Making the Multi-Layered Photochromic Materials

[0101] The multi-layered color changing materials of the present invention can be made by straightforward and cost-efficient steps that are performed under conditions that reduce or prevent damage to the photochromic, electrochromic, or thermochromic materials. In particular, there are two alternatives, a lamination process and a co-extrusion process, which are illustrated in FIG. 4. In some embodiments, the photochromic dye, electrochromic material or thermochromic material and/or additional compounds are delivered to specific portions of the resulting polymeric layers (for example, in the center of the layer, around the exterior portions of the film, or dispersed throughout the layers).

[0102] The lamination process 40 can include the following steps: [0103] (a) obtaining a first polymeric film 42 that includes a thermoplastic polymer or copolymer or a polymeric blend of said polymer or copolymer. Such films are commercially available (e.g., SABIC) or can be easily prepared by processes disclosed in this specification and those known in the art. In preferred aspects, the thickness of this film can range from 10 m to 4 mm. The film can include a photochromic compound such that the film is capable of reversibly changing from color 1 to color 2 in response to electromagnetic radiation. Such films can be prepared by using the following non-limiting procedure: combining a photochromic compound or dye material with a polymeric solution or oligomeric solution or mixture, casting or extruding a film therefrom, and, if required, at least partially setting the film. Polymer powder can be used (e.g., in Kg scale), and photochromic dye can be used in ppm level (see, e.g., Tables 6 & 7 below). Processing temperatures can range from 150-250 C.). [0104] (b) obtaining a second polymeric or non-polymeric film or layer 44. This film or layer can also include a photochromic compound or can include a thermochromic or electrochromic material or combinations thereof that allow this layer to reversibly change from color 3 to color 4 in response to a stimulus (e.g., electromagnetic radiation, heat, or electricity). The thickness of this film can be modified as needed to match the optical clarity of the first film or the optical parameters desired for a given application. In preferred aspects, the thickness of this film ranges from 10 m to 4 mm. Such films can be prepared by using the following non-limiting procedure: combining a photochromic compound or dye material with a polymeric solution or oligomeric solution or mixture, casting or extruding a film therefrom, and, if required, at least partially setting the film. Polymer powder can be used (e.g., in Kg scale), and photochromic dye can be used in ppm level (see, e.g., Tables 6 & 7 below). Processing temperatures can range from 150-250 C.). [0105] (c) pressing the first film 42 and second film 44 together such that the first and second films adhere to one another and form color changing material 46. The following conditions can be used to obtain sufficient adhesion of these films: temperature range for lamination can be 100 to 250 C., and pressure range for lamination can be 50 to 200 psi.

[0106] For the co-extrusion process, the following steps can be used: [0107] (a) extruding in a first extruder a first composition comprising the thermoplastic polymer or copolymer or polymeric blend thereof and a photochromic compound. [0108] (b) simultaneously or substantially simultaneously extruding in a second extruder a second composition comprising a thermoplastic or a non-thermoplastic polymer and optionally a photochromic, thermochromic, or electrochromic material or combinations thereof. [0109] (c) introducing the extruded first composition 42 and second composition 44 into a die such that the first and second compositions contact one another to form the multi-layered material of the present invention. The resulting thicknesses of each of the first and second layers preferably range from 10 m to 4 mm. [0110] (d) solidifying both the first and second layers (e.g., by cooling) thereby forming a self-supporting multi-layer film 46 of the present invention. [0111] (e) optionally heat treating the photochromic material at a temperature range of 100 to 200 C.

[0112] The polymers used in the first and second layers or films along with the photochromic, thermochromic, and electrochromic materials can be used in amounts (or ratios) such that the resulting film or layer (or the entire multi-layered material) exhibits desired optical properties without and in the presence of a given stimulus. For example, the amount and types of photochromic/thermochromic/electrochromic materials can be selected such that the resulting individual films or the entire material may be clear or colorless in the absence of a given stimulus (e.g., electromagnetic radiation) and may exhibit a desired resultant color in the presence of the stimulus. The precise amount of the photochromic/thermochromic/electrochromic materials that may be utilized is not critical provided that a sufficient amount is used to produce the desired effect. The particular amounts may depend on a variety of art-recognized factors, such as but not limited to, the absorption characteristics of the chromic materials, the color and intensity of the color desired upon activation, and the method used to incorporate the chromic materials into the polymeric layers of the present invention. Although not limiting herein, according to various non-limiting embodiments disclosed herein, the amount of the photochromic/electrochromic/thermochromic materials incorporated into the polymeric layers of the present invention can range from 0.01 to 20 weight percent (e.g., from 0.05 to 15, or from 0.1 to 5 weight percent), based on the total weight of each layer into which the chromic material is incorporated.

[0113] Similarly, each layer can be further colored with pigments to create opaque or permanently colored translucent layers. Similarly, additives can be added to the multi-layered color changing materials of the present invention. For instances, additives can be added to any of the layers of the materials of the present invention to achieve a desired effect. The amounts of such additives can range from 0.001 to 40 wt. %. In addition to the pigments, non-limiting examples of such additives include plasticizers, ultraviolet absorbing compounds, optical brighteners, ultraviolet stabilizing agents, heat stabilizers, diffusers, mold releasing agents, antioxidants, antifogging agents, clarifiers, nucleating agents, phosphites or phosphonites or both, light stabilizers, singlet oxygen quenchers, processing aids, antistatic agents, fillers or reinforcing materials, or any combination thereof. Non-limiting examples of ultraviolet light absorbing compounds include those capable of absorbing ultraviolet A light comprising a wavelength of 315 to 400 nm (e.g., avobenzone (Parsol 1789, AbcamBiochemicals, USA), bisdisulizole disodium (Neo Heliopan AP, Symrise, Germany), diethylamino hydroxybenzoyl hexyl benzoate (Uvinul A Plus, BASF), ecamsule (Mexoryl SX, L'Oreal, France), or methyl anthranilate, or any combination thereof) or those that are capable of absorbing ultraviolet B light comprising a wavelength of 280 to 315 nm (e.g., 4-aminobenzoic acid (PABA), cinoxate, ethylhexyl triazone (Uvinul T 150, BASF), homosalate, 4-methylbenzylidene camphor (Parsol 5000), octyl methoxycinnamate (octinoxate), octyl salicylate (octisalate), padimate O (Escalol 507, Ashland Inc., USA), phenylbenzimidazole sulfonic acid (ensulizole), polysilicone-15 (Parsol SLX), trolamine salicylate, or any combination thereof), or those that are capable of absorbing ultraviolet A and B light comprising a wavelength of 280 to 400 nm (e.g., bemotrizinol (Tinosorb S, BASF), benzophenones 1 through 12, dioxybenzone, drometrizole trisiloxane (Mexoryl XL), iscotrizinol (Uvasorb HEB, 3V Sigma, Italy), octocrylene, oxybenzone (Eusolex 4360, Merck KGaA, Germany), or sulisobenzone, or any combination thereof). Such additives can be compounded into a masterbatch with the desired polymeric resin.

F. Tuning

[0114] Each layer of the color changing material of the present invention can be designed such that it's resting or non-stimulated state is optically clear or is colored (either transparently, translucently or opaquely colored). For an optically clear resting state, optically clear polymers, including those described throughout the specification (e.g., polyolefins, polycarbonates, etc.), can be used. For a colored resting state, pigments and other dyes can be incorporated into the layer to produce a desired color. Also, opaque polymers can be used to produce a desired colored resting state.

[0115] Further, each layer of the color changing material can include various photochromic, thermochromic, or electrochromic materials, or combinations thereof. These combinations can produce different colors and color intensities (see FIG. 5, which is a standard color wheel that can be used to design the various colors produced for a given color changing material of the present invention). For example, a combination of photochromic material that turns blue in response to visible light (blue photochromic material) with photochromic material that turns yellow in response to visible light (yellow photochromic material) can produce an overall green color in the presence of visible light. Even further, varying the amounts or ratios of one material over another can produce various shades or tints of colors (e.g., a 2:1 ratio of blue photochromic material over yellow photochromic material would result in a more blue-green color. By comparison, a ratio of 1:2 of blue photochromic material over yellow photochromic material would result in a more yellow-green color).

[0116] Also, the thickness of each layer of the color changing material of the present invention can be varied to obtain a desired time-period in which the color change occurs. The thickness can also be varied to obtain a desired color intensity or shade of color. For instance, if the thickness of a given layer is increased, then it could take a longer period of time for a given stimulus to reach a responsive material (e.g., photochromic, thermochromic, or electrochromic material), thereby causing an increase in the time-period in which the color change occurs. Further, the longer travel time could result in a reduced or filtered stimulus reaching the responsive material, which could affect color intensity or shade. By comparison, if the thickness of the layer is decreased, then the color intensity or shade could be increased and the time-period of the color change decreasedthere is less polymeric or non-polymeric material in the layer to inhibit or limit a given stimulus reaching a responsive material (e.g., photochromic, thermochromic, or electrochromic material). Notably, the thickness of the top or outermost layer can affect all of the layers below this outermost layer by acting as an overall stimulus filter for the lower-level layers.

[0117] Additionally, the positioning of photochromic, thermochromic, or electrochromic responsive material in a given layer can be used to obtain a desired color intensity or time-period for the color change. Similar to the thickness of layers, the positioning of the responsive material within a layer can either increase or decrease the travel time that a given stimulus takes to reach the responsive material. Further, the stimulus can be stronger or weaker depending on the positioning of the responsive material in the layer (e.g., the material used to make the layerpolymeric material, non-polymeric material, additives, etc.can act as a filter for the stimulus by diffracting or absorbing the stimulus). Positioning of the responsive material within a desired portion of the layer may impart color to the desired portion while leaving other portions or the layer or photochromic material unchanged in color upon exposure to a stimulus. A non-limiting example includes inclusion of the responsive material in the center of a layer so that upon exposure of the photochromic material to a stimulus only the center of the photochromic material changes color. Upon removal of the stimulus the center of the photochromic material quickly returns to the original color.

[0118] Therefore, desired time-periods for color changes as well as desired colors and color intensities can be produced in the context of the present invention by: (1) combining various photochromic, thermochromic, or electrochromic materials in single layers or stacking multiple layers onto one another; (2) varying the concentrations/amounts/ratios of photochromic, thermochromic, or electrochromic materials used in the layers; (3) varying the thicknesses of the photochromic and non-photochromic layer(s); (4) varying the position or location (e.g., depth within layer or one side of the layer, etc.) of the photochromic, thermochromic, or electrochromic materials; and (5) using non-photochromic layers that have resting or set or permanent colors. By varying these features, the color changing materials of the present invention can be tuned to have a desired color or color intensity at desired time-periods.

[0119] The colors that can be produced are wide ranging. The color wheel in FIG. 5 provides non-limiting examples such as primary colors (e.g., red, blue, yellow), secondary colors (e.g., orange, green, purple), and various tertiary colors (yellow-orange, red-orange, red-purple, blue-purple, blue-green, and yellow-green). Secondary colors can be formed by mixing two primary colors. Tertiary colors can be formed by mixing primary and secondary colors. Various color shades can be produced by combing various colors from the color wheel. Additionally, various tints of each color can be produced by adding white to a given color. Various shades can be produced by adding black to a given color. The tones of each color can be modified by adding gray to a given color.

G. Multi-Layered Photochromic Material

[0120] Referring to FIG. 6A, the multi-layered photochromic material 60 of the present invention can take a variety of forms. The multi-layered photochromic material can include one or more photochromic dyes where at least one of the photochromic dyes is capable of switching back upon removal of the stimulus in a rapid manner (e.g., less than 10 minutes, 5 minutes or 1 minute). Further, it can be designed such that it is transparent, optically clear, translucent or opaque prior to being subjected to electromagnetic/thermal/electric stimuli. In preferred aspects, said material 60 is optically clear or transparent or translucent prior to being subjected to stimuli. FIG. 6A illustrates a cross-section view of a bilayer material 60 that includes a first layer or film 61 in contact with a second thermoplastic polymeric layer or film 62. Contact refers to at least a portion of a surface of the first film 61 contacting at least a portion of a surface of the second film 62. In preferred aspects, at least 10, 20, 30, 40, or up to 50% of the surfaces of the first and second films can be in contact with one another. The first layer 61 can be polymeric or non-polymeric layer. This layer 61 can provide support for the thermoplastic layer 62. The second layer 62 can include free volume or spaces 63 within the polymeric matrix. The free volume or spaces 63 can be modified by selection of a particular polymer or modifying the amounts of polymers in instances where a blend of polymers is used. This free volume or spaces 63 allows photochromic compounds 64 to efficiently change shape from an inactivated state to an activated state in response to electromagnetic radiation with rapid return to the original color upon removal of the stimulus (e.g., fast-switching back to original color within 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, minutes or less once the stimulus is removed). Further, and although not shown, the first layer 61 can also include photochromic compounds 64 or thermochromic or electrochromic material. Similarly, the second layer 62 can also include thermochromic or electrochromic material.

[0121] Referring to FIG. 6B, a substrate 65 can be used to support the bilayer material 60. The substrate can be in direct contact with the second layer 62 or can be in direct contact with the first layer 61 or can be separated with additional layers between said first or second layers 61 and 62. The substrate 65 can be additional polymeric layers, non-polymeric layers, articles of manufacture (e.g., glass, monitors, furniture, buildings, walls, etc.). The multi-layered color fast color changing material 60 can be affixed to the substrate with an adhesive or attachment devices (e.g., nails, screws, clips, etc.).

[0122] Referring to FIGS. 6C and 6D, the first layer 61 can be adhered to the second layer 62 with an adhesive 66. Non-limiting examples of such adhesives include polyvinyl acetate (PVA), polyvinyl butyral (PVB), and others known in the art.

[0123] Referring to FIG. 6E, the photochromic material 60 can be a multi-layered material in which the first and second layers 61 and 62 can be attached to third 67 and fourth 68 layers. Although not shown, additional layers (e.g., 5, 6, 7, 8, or more) can be used, and the additional layers 67 and 68 can be attached to the first layer 61 or the second layer 62 or both the first and second layers 61 and 62. These additional layers can be polycarbonate layers, less rigid polymeric layers, non-polymeric layers (e.g., glass, metal, ceramic, etc.). Additional non-limiting examples of layers 67 and 68 include abrasion resistant films and coating (e.g., organosilanes, organosiloxanes, silica, titania, zirconia), UV-shielding coatings or films, anti-reflective coatings or films, oxygen barrier-coatings or films, conventional photochromic coatings, polarizing coating or films, anti-static coatings or films, oleophobic/hydrophobic or anti-soil or anti-fouling coatings or films, anti-fogging films, etc. In some embodiments, the photochromic material is used for outdoor applications and a light stabilized external layer can include additives described herein that are able to reduce photobleaching or fading of the photochromic dye. In some instances, one or more top layers can be used to inhibit gas migration into the layer (e.g., an oxygen barrier layer).

[0124] By way of example, and with reference to FIG. 7, a multi-layered photochromic material 70 is illustrated. In FIG. 7, a first layer 72 can include a polymeric layer that has good barrier properties and scratch resistance (for example, a polymer made from a methacryloyloxyethyl benzyl dimethylammonium chloride (DMBC)). This layer can inhibit oxygen from entering the other layers so that the mechanical and fatigue properties of the photochromic mechanical are not diminished. A second layer 74 can include a polymer and a dye (for example, a polycarbonate (PC) resin and a dye. A commercially available polycarbonate resin is XYLEXTM (SABIC Innovative Plastics). Layer 74 can be a fast fading layer, but have properties that are resistant to acids (for example, body lotions). A third layer 76 can include a polymer blend and a dye. Layer 76 can be a polypropylene (PP) and polyethylene (PE) blend. The fourth layer, layer 78, can be a polycarbonate layer and a dye. Layer 78 can also have fast fading properties when light exposure is removed and have better adhesive properties than layer 76. The combination of layers 72, 74, 76 and 78 control color fading. This set-up can control the rate of color change in response to electromagnetic radiation with the combination of dyes as well as provide a material that has optical clarity and sufficient barrier and scratch resistant properties.

[0125] Referring to FIG. 8, a non-limiting tri-layered color changing (photochromic) material 80 of the present invention is affixed to an interior wall 82 that is painted white (e.g., a wall in a home or apartment or office space, etc.). A thermochromic layer 84 is directly attached (e.g., with a transparent adhesive) to the surface of the interior wall. The thermochromic layer 84 is a polymeric layer having a thermochromic material incorporated therein and is designed to have a green color at temperatures of equal to or less than 30 C. and to be colorless at temperatures greater than 30 C. An electrochromic layer 86 is disposed onto the thermochromic layer 84 (e.g., by co-extrusion or lamination). The electrochromic layer 86 is a polymeric layer having an electrochromic material incorporated therein and is designed to have a colorless state in the absence of an electrical stimulus (e.g., the material 80 can be wired to a wall switch) and a red color in the presence of an electrical stimulus). A photochromic layer 88 is disposed onto the electrochromic layer 86 (e.g., by co-extrusion or lamination). The photochromic layer 88 is a thermoplastic polymeric layer having a photochromic material incorporated therein and is designed to have a colorless state in the absence of visible light (e.g., sunlight or non-natural visible light) and a blue color in the presence of visible light. Thus, the tri-layered color material 80 could be used in the following manner. The color of the wall will appear green when the temperature is equal to or less than 30 C., without the electrical stimulus and in low light level conditions. Increases the light in the room (e.g., turning on a lamp or more light filtering in from the sun such as morning to afternoon light) would allow the photochromic layer 88 to be stimulated towards the color blue, thus creating a more blue-green color for the wall. If the temperature in the room rises to greater than 30 C. (while in the presence of light), then the color of the wall turn towards blue. If an electrical stimulus is then applied (e.g., turning on a wall-switch), the electrochromic layer 86 will go from colorless to red, thus creating a purple color on the wall. Then reducing the light level in the room will push the color of the wall towards red. Cooling the room down to 30 C. or less will then push the color of the wall to orange. Turning off the wall switch will then return the color of the wall to green.

[0126] FIG. 9 provides another non-limiting embodiment of the present invention. In particular, a bi-layered photochromic material 90 of the present invention is affixed to an interior wall 82 that is painted white (e.g., a wall in a home or apartment or office space, etc.). The material 90 includes a first photochromic layer 92 that is directly attached (e.g., with a transparent adhesive) to a surface of the interior wall. This first layer 92 includes a photochromic compound that is activated by visible light, which allows the first layer 92 to shift from a colorless transparent state to yellow in the presence of visible light (e.g., house lamp, sunlight, etc.). A second photochromic layer 94 is disposed onto a surface of the first photochromic layer 92 (e.g., by co-extrusion or lamination). The second layer 94 is designed to have a transparent colorless state in the absence of UV light and a blue color in the presence of UV light. Notably, both layers 92 and 94 can each individually be thermoplastic or thermoset polymeric layers. Thus, the bi-layered color material 90 could be used in the following manner. The color of the wall will appear white in the absence of sunlight and in the absence of a non-natural visible light source (e.g., at nighttime). In the presence of sunlight in which UV light has not been filtered out (e.g., by a window), the color of the wall will begin to shift from white to green due to UV light from the sun activating the photochromic compound in layer 94 and visible light from the sun activating the photochromic compound in layer 92 (blue+yellow=green). Then if a non-natural visible light source (e.g., incandescent, fluorescent, LED light source, etc.) is turned on (e.g., from a lamp), the color of the wall will shift to a yellow-green color due to additional visible light stimulation. If sunlight is then removed (e.g., closing blinds or curtains in a room or as day turns to night), the color of the wall will shift towards yellow via deactivation of the photochromic compound in layer 94. Then, if the non-natural visible light source is removed (e.g., lamp is turned off), the color of the wall will shift from yellow back to white via deactivation of the photochromic compound in layer 92. The same type of effect could also be achieved by mixing different photochromic compounds in a single layer (see FIG. 10).

[0127] FIG. 10 is a non-limiting bi-layer photochromic material 100 of the present invention. The material 100 includes a first electrochromic layer 102 that is directly attached (e.g., with a transparent adhesive) to a surface of an interior wall 82 that is painted white. This first layer 102 includes an electrochromic compound that is activated by electricity, which allows the layer 102 to shift from a colorless transparent state to red in the presence of electricity (e.g., it can be coupled to a wall switch in a house). A second photochromic layer 104 is disposed onto a surface of the first photochromic layer 102 (e.g., by co-extrusion or lamination). The second layer 104 includes a first photochromic compound 106 that is activated by UV light (e.g., activation causing a color change from colorless to blue) and a second photochromic compound 108 that is activated by visible light (e.g., activation causing a color change from colorless to yellow). The compounds 106 and 108 are dispersed throughout the second layer 104. The second layer 104 is designed to have a transparent colorless state in the absence of UV and visible light, a color of blue in the presence of UV light and the absence of visible light, a color of yellow in the presence of visible light and in the absence of UV light, and a color of green in the presence of both UV and visible light (e.g., light from the sun). The intensity of the color shifts can be modified by varying the amount of photochromic (as well as electrochromic and thermochromic compounds) in a given layer. This photochromic material 100 can change colors by including and excluding the various stimuli needed to change the colors of the layers of the material 100, similar to the embodiments discussed above.

[0128] FIG. 11 is a mono-layer photochromic material 110 of the present invention. It is similar to the embodiment in FIG. 10, except that it no longer includes the electrochromic layer 102.

H. Applications for the Photochromic Materials

[0129] The photochromic materials of the present invention can be used in a wide variety of applications. For instance, and as exhibited in the examples, the materials have sufficient optical properties and strength such that they can be used in optical applications such as Examples of photochromic materials of the present invention include, but are not limited to, optical elements, displays, windows (or transparencies), mirrors, and liquid crystal cells. As used herein the term optical means pertaining to or associated with light and/or vision. The optical elements according to the present invention may include, without limitation, ophthalmic elements, display elements, windows, mirrors, and liquid crystal cell elements. As used herein the term ophthalmic means pertaining to or associated with the eye and vision. Non-limiting examples of ophthalmic elements include corrective and non-corrective lenses, including single vision or multi-vision lenses, which may be either segmented or non-segmented multi-vision lenses (such as, but not limited to, bifocal lenses, trifocal lenses and progressive lenses), as well as other elements used to correct, protect, or enhance (cosmetically or otherwise) vision, including without limitation, magnifying lenses, protective lenses, visors, goggles, as well as, lenses for optical instruments (for example, cameras and telescopes). As used herein the term display means the visible or machine-readable representation of information in words, numbers, symbols, designs or drawings. Non-limiting examples of display elements include screens, monitors, and security elements, such as security marks. As used herein the term window means an aperture adapted to permit the transmission of radiation there-through. Non-limiting examples of windows include automotive and aircraft transparencies, windshields, filters, shutters, and optical switches. As used herein the term mirror means a surface that specularly reflects a large fraction of incident light. As used herein the term liquid crystal cell refers to a structure containing a liquid crystal material that is capable of being ordered. One non-limiting example of a liquid crystal cell element is a liquid crystal display.

[0130] Still further, however, the multi-layer materials of the present invention can be used in contexts where optically clear materials are not needed or desired. For example, the photochromic materials can be used as paint, wallpaper, tiles, appliances, tables, automotive industry (e.g., door panels, roof panels, seating surfaces, tires, rims, wheels, paint, etc.), outdoor surfaces (e.g., concrete, bridges, sport courts, flooring, building surfaces, roofs, windows, street signs, etc.), sporting events (e.g., color of playing surfaces, goal posts, helmets, uniforms, equipment, etc.), etc.

EXAMPLES

[0131] The present invention will be described in greater detail by way of specific examples. The following examples are offered for illustrative purposes only, and are not intended to limit the invention in any manner. Those of skill in the art will readily recognize a variety of noncritical parameters which can be changed or modified to yield essentially the same results.

Example 1

Materials and Methods

[0132] Photochromic Dyes:

[0133] The photochromic dyes that were obtained from Vivimed Labs Europe Ltd., under the trade name ReversacolTM. The specific dyes are identified below in Tables 8 and 9.

[0134] Extrusion Conditions:

[0135] Polyethylene was pre-blended with selected additives and photochromic dyes as noted below in Table 8. The pre-blended polyethylene powder was extruded by using a shift screw extruder under the conditions identified in Table 1.

TABLE-US-00001 TABLE 1 (Compounding conditions for polyethylene and photochromic dye (additive)) Extruder Type Coperion Twin Barrel Size mm Screw Design None Shift Screw Die mm 2.3 Zone 1 Temp C. 30 Zone 2 Temp C. 50 Zone 3 Temp C. 70 Zone 4 Temp C. 100 Zone 5 Temp C. 170 Zone 6 Temp C. 170 Zone 7 Temp C. 170 Zone 8 Temp C. 170 Zone 9 Temp C. 170 Zone 10 Temp C. 170 Zone 11 Temp C. 170 Zone 12 Temp C. 170 Screw Speed rpm 300 Throughput kg/hr 18 Torque % 40 Vacuum 1 MPa 0.08 Side Feeder 1 Speed rpm 0

[0136] Similarly, polycarbonate (and its copolymers/blends) was pre-blended with other additives and photochromic dye. Then the pre-blended polycarbonate powder was extruded by using a shift screw extruder. The compounding conditions are provided in Table 2.

TABLE-US-00002 TABLE 2 (Compounding conditions for polycarbonate and photochromic dye (additive)) Extruder Type TEM-37BS Barrel Size mm 1000 Screw Design None S-1 Die mm 3 Zone 1 Temp C. 50 Zone 2 Temp C. 100 Zone 3 Temp C. 120 Zone 4 Temp C. 200 Zone 5 Temp C. 230 Zone 6 Temp C. 230 Zone 7 Temp C. 230 Zone 8 Temp C. 230 Zone 9 Temp C. 230 Zone 10 Temp C. 230 Die Temp C. 170 Screw Speed rpm 300 Throughput kg/hr 40 Torque % 65 Vacuum 1 MPa 0.08 Side Feeder 1 Speed rpm 250

[0137] PC-PE Films:

[0138] A film laminator from Oasys Technologies Ltd. (ModelOLA6H; 240 Vac, 30 Hz, 2.5 KVA) was utilized for fusing or laminating the polycarbonate (or copolymers/blends) film with the polyethylene (or PP/PE, etc.) film. The polycarbonate (or copolymer/blends) films were made using the conditions in Table 3. The conditions to make the polyethylene film are listed in Table 4. The lamination conditions for fusing/laminating the two films together are listed Table 5. The formulation/composition of the polymeric films viz. HDPE & polycarbonate based have been listed in Table 8 & 9.

TABLE-US-00003 TABLE 3 (Conditions for polycarbonate (copolymers/blends) film) Step Temp ( C.) Press (psi) Time (sec) 1 205 50 1 2 185 100 240 3 185 100 1 4 185 100 1 5 185 100-200

TABLE-US-00004 TABLE 4 (Conditions for polyethylene film) Step Temp ( C.) Press (psi) Time (sec) 1 150 50 1 2 150 100 120 3 150 100 1 4 150 100 1 5 150 100-200

TABLE-US-00005 TABLE 5 (Laminating conditions for polycarbonate (copolymers/blends) and polyethylene fused film) Step Temp ( C.) Press (psi) Time (sec) 1 205 50 1 2 185 200 240 3 185 100 1 4 185 200 1 5 185 200

[0139] Solvent Cast Films:

[0140] Solvent cast films were prepared by dissolving the polymer in toluene until a clear polymer/toluene solution was obtained. The solution was poured into a flat surface and allowed to evaporate slowly under ambient conditions overnight (about 10 hours) to obtain a clear film. Solvent cast films with dye were prepared in a similar manner with the dye being added to the polymer/toluene solution. The formulation/composition of the polymeric films are listed in Table 10.

[0141] PE Films:

[0142] A Fritsch, Pulverisetter 14 (Germany) was utilized for cryo-grinding polyethylene with dye to a powder. The powder was then made into a film using an Oasys Technologies, OLA6H laminator under isothermal conditions of 150 C., under a pressure ramp from 50 to 150 psi for a time period of 2 minutes. The formulations/compositions of the polyethylene and dyes are listed in Table 11.

[0143] Lamination of Bi-Layer Films.

[0144] A PC film (HFD 8089) without dye was made using the conditions listed in Table 3. COC films with and without dye (formulations #11 and #16 in Table 10, respectively) were made using the solvent cast method described above. An LDPE film with photochromic dye formulation (#17 in Table 11) was made into a film using the Oasys Technologies OLA6H laminator. The Oasys Technologies, OLA6H laminator was utilized to fuse or laminate the films together under isothermal conditions of 150 C., under a pressure ramp from 50 to 150 psi for a time period of 3 minutes. The films, composition of the films and the laminate properties are listed in Table 6.

TABLE-US-00006 TABLE 6 Composition of # Films* Laminate Layers Laminate Property 20 PC/COC HFD 8089 and COC-16 Clear, colorless (storm purple) 21 COC/LDPE COC-11; LDPE-17 Clear, colorless (storm purple) *PC and HFD is polycarbonate; COC is cyclic olefin copolymer, and LDPE is low density polyethlene.

[0145] Lamination of Tri-Layer Films.

[0146] The Oasys Technologies, OLA6H laminator was utilized to make tri-layer laminates from COC film with dye (#12 (photochromic), #13 (non-photochromic), and #14 (non-photochromic), Table 10), PE (LDPE) film with photochromic dye (#17, Table 11), PE (HDPE) film with photochromic sea green dye (#18, Table 11) and polycarbonate (HFD) film with non-photochromic dyes (#15-16, Table 10) films under isothermal conditions of 165 C., under a pressure ramp from 50 to 150 psi for a time period of 4 minutes. The composition of the films and the laminate properties are listed in Table 7. The original color of the laminates was red.

TABLE-US-00007 TABLE 7 (Tri-layer laminates) PC Films PE Film COC Film Compo- Compo- Compo- sition sition sition Laminate # (Table 10) (Table 11) (Table 10) Film Order* Property 22 #15; #16 #12 PC-15/ Clear, COC-12/PC-16 Red Color 23 #17 #13; #14 COC-13/ Partially LDPE-17/COC-14 Opaque, Red Color 24 #15; #16 #18 PC-15/ Partially HDPE-18/PC-16 Opaque, Red Color *PC is polycarbonate; COC is cyclic olefin copolymer, LDPE is low density polyethylene, and HDPE is high density polyethylene.

[0147] Testing Materials and Protocols:

[0148] An Atlas Suntest CPS with 11500 W air-cooled xenon lamp, 560 cm.sup.2 exposure area, with direct setting and control of irradiance in the wavelength range of 300-800 nm/Lux; or 300-400 nm/340 nm was used. A Gregtage Macbeth Color-eye 7000A X-rite Spectrometer for L,a,b measurements over a time scale was used.

[0149] Samples were exposed to Suntester for 30 to 60 seconds. The spectral data was recorded immediately. Light absorbances values along with light percent transmittance, % T, were measured. The data was recorded over a span of 2-3 minutes with 10 second intervals. Reference value is light transmittance of an unexposed sample.

TABLE-US-00008 TABLE 8 (Formulation/composition of polyethylene (HDPE- B5823*) and Sea Green (Vivimed dyes)) Amount Photochromic Amount Amount # Polymer (Kg) Dye (ppm) (g) 1 HDPE 1 Sea green 1500 1.5 2 HDPE 1 Sea green 500 0.5 3 HDPE 1 Sea green 250 0.25 4 HDPE 1 Sea green 125 0.125 5 HDPE 1 Sea green 75 0.075 6 HDPE 1 2039 (Slow fading) 75 0.075 *High density polyethylene (HDPE).

TABLE-US-00009 TABLE 9 (Formulation/composition of polycarbonate (HFD-8089*), LDPE** with Vivimed dyes) Amount Photochromic Amount Amount # Polymer (Kg) Dye (ppm) (g) 1 HFD 1 Sea green 500 0.5 8089 2 HFD 1 Sea green 250 0.25 8089 3 HFD 1 Sea green 75 0.075 8089 4 HFD 1 Storm purple 500 0.5 8089 5 HFD 1 Storm purple 75 0.075 8089 6 HFD 1 2039 (slow fading) 500 0.5 8089 7 HFD 1 2197 (slow fading) 500 0.5 8089 8 HFD 1 Sea green + 500 + 10 g 0.5 8089 Irganox 1098 9 LDPE 1 Storm purple 800 0.8 10 LDPE 0.8 Aqua green 500 0.5 *HFD is a bisphenol-A polycarbonate, sebacic acid copolymer and provides for relatively more void space in the matrix for the photochromic dyes to switch or change their respective chemical structures in response to light or heat. The processing temperature is lower than bisphenol-A polycarbonate and thus, the photochromic dye does not undergo any thermal degradation. **Low Density Polyethylene (LDPE).

TABLE-US-00010 TABLE 10 (Formulation/composition of polycarbonate and COC films and dyes) Amount Amount Solvent # Polymer (mg) Dye (mg) (10 mL) 11 COC* 500 Toluene 12 COC 500 Storm Purple 0.2 Toluene 13 COC 500 **CAS 343232-69-9 20 Toluene 14 COC 500 **CAS 1210881-03-0 2 Toluene 15 HFD 500 **CAS 343232-69-9 20 Dichloro- 8089 methane 16 HFD 500 **CAS 1210881-03-0 2 Dichloro- 8089 methane *Cyclic olefin copolymer, TOPAS 5013 (Topas Advanced Polymers, Germany). **Non-photochromic dyes

TABLE-US-00011 TABLE 11 (Formulation/composition of LDPE and HDPE Films with Photochromic dyes) Amount Photochromic Amount Amount # Polymer (Kg) Dye (ppm) (g) 17 LDPE 1 Storm purple 800 0.8 18 HDPE 1 Sea Green 75 0.075

Example 2

Results

[0150] Polycarbonate with Vivimed photochromic dyes. The processed samples of polycarbonate (HFD) with various Vivimed photochromic dyes (Table 7) were irradiated with UV to study the photochromic performance of the HFD part (FIGS. 12A-D). FIG. 12A is a graph of wavelength in nanometers versus percent transmittance of a material of the present invention that includes a high flow ductile (HFD) polycarbonate polymer and 500 ppm of dye-2197. FIG. 12B is a graph of wavelength in nanometers versus percent transmittance of a material of the present invention that includes a HFD polycarbonate polymer and 500 ppm of Storm Purple. FIG. 12C is a graph of wavelength in nanometers versus percent transmittance of a material of the present invention that includes a HFD polycarbonate polymer and 500 ppm of Sea Green. FIG. 12D is a graph of wavelength in nanometers versus percent transmittance of a material of the present invention that includes the HFD polycarbonate polymer and 500 ppm of dye 2039. In each figure data line 120 is the unexposed sample (100% transmittance) and is used as the reference. Data lines 122 are data recorded after exposure to the Suntester. In each of the samples, a good intensity of color developed in the HFD matrix with the photochromic dye.

[0151] In addition to the good intensity of color, the HFD matrix with photochromic dye showed a fast fading of the dye color ranging between 15 and 60 seconds. FIG. 13A is an image of the HFD matrix of the present invention (right sample) and a commercial polyurethane coating (left sample) that has been exposed to light. FIG. 13B is the same samples after 10 to 20 seconds. As seen in FIG. 13B both samples turned colorless after about 10-20 seconds. The remnant color was very faint after about 60 seconds. Thus, the fading rate of the photochromic dye in HFD (solvent-cast film) was found to be comparable with the commercial polyurethane coatings.

[0152] Polyethylene with Dyes.

[0153] HDPE samples made with Sea Green (Table 8). Upon exposure to room light, some of the samples turned blue. These kinds of observations are due to the absorption pattern of the photochromic dye used. FIGS. 14A and B depict images of pellets of the HDPE matrix with Sea Green dye. FIG. 14A is an image of the bags before exposure to fluorescent light. FIG. 14B is an image of the bags after exposure to fluorescent light. As shown in FIG. 14B, pellets in three of the bags turned blue upon exposure to room light. Thus, it was realized that the choice of dyes would be based on the requirement for the respective application.

[0154] The various compositions of HDPE with Sea Green (Table 8) were studied for the effect of dye concentration on color intensity on UV exposure. FIG. 15A is a graph of wavelength in nanometers versus percent transmittance of a material of the present invention that includes a HDPE polymer and 1500 ppm of Sea Green dye. FIG. 15B is a graph of wavelength in nanometers versus percent transmittance of a material of the present invention that includes a HDPE polymer and 500 ppm of Sea Green dye. FIG. 15C is a graph of wavelength in nanometers versus percent transmittance of a material of the present invention that includes a HDPE polymer and 250 ppm of Sea Green dye. FIG. 15D is a graph of wavelength in nanometers versus percent transmittance of a material of the present invention that includes a HDPE polymer and 125 ppm of Sea Green dye. It was realized that with higher concentration of the dye, the color intensified. In each figure data line 150 is the unexposed sample (100% transmittance) and is used as the reference. Data lines 152 are data recorded after exposure to the Suntester. In each of the samples, a good intensity of color developed in the HDPE matrix with the photochromic dye. As shown in FIGS. 15A-15D, the amount of transmittance can be changed based on the amount of dye present in the polymer matrix.

[0155] Comparative Materials and Materials of the Present Invention.

[0156] The transmittance of visible light in colorless and colored states was measured for a commercial product (FIG. 16A), an experimental grade coating (FIG. 16B) and samples of films of the present invention (FIGS. 16C and 16D). FIG. 16C is a sample of HDPE and Sea Green dye (Table 8, #1) laminate. FIG. 16D is a sample of HFD-HDPE (Sea green, 1500 ppm) laminate. In each figure data line 160 is the unexposed sample (100% transmittance) and is used as the reference. Data lines 162 are data recorded after exposure to the Suntester. By comparison, samples of HDPE with Sea Green dye (FIG. 16C) and HFD-HDPE Laminate with Sea Green dye (FIG. 16D) showed fading speed of dye comparable to the comparative samples (FIGS. 16A and 16B). This confirms that optically clear polycarbonate-based lenses (thermoplastic) can be prepared via a one-step extrusion method which reduces the complexity of currently existing methods of making photochromic lenses (e.g., coatings, surface impregnations, etc.).

[0157] Color Changing Laminates.

[0158] Samples with photochromic dyes, non-photochromic dyes and both were irradiated with room light and ultra violet light and the change in color was determined. Initially all the trilaminates (as listed in Table 7) are red in color due to red non-photochromic dyes; UV light was produced with UV torch model LABINO UV-375 with a peak wavelength of 375 nm

[0159] Red laminate #22 (HFD-15/COC-12/HFD-16), has the COC film with the photochromic storm purple dye (COC-12) between the permanently colored HFD film layers (Films #15-16). The laminate #22 was positioned with film HFD-16 (perylene dye) facing towards the light, and was irradiated with room light. No color change was observed. Upon irradiation of the red Laminate #22 with UV light, the color of the laminate turned from red to greyish blue. The color change was due to the COC-photochromic dye film between the two polycarbonate films.

[0160] Red Laminate #23 (COC-13/LDPE-17/COC-14) has the LDPE film with the photochromic storm purple dye (LDPE-17) between the COC films with non-photochromic dye (COC-13 and COC-14). The laminate was positioned so that the perylene based COC film layer (COC-14) faced towards the light. Irradiation with room light produced no color change (i.e., the laminate remained red). Upon irradiation with UV light the color of the laminate turned from red to greyish blue. The color change was due to the LDPE-17-photochromic dye film between the two cyclic-olefin films.

[0161] Laminate #24 (HFD-15/HDPE-18/HFD-16) has the HDPE film with the sea green photochromic dye (HDPE-18) between two polycarbonate films with non-photochromic dyes (HFD-15 and HFD-16). The laminate was positioned so that the perylene based PC film layer (HFD-16) faced towards the light. Upon irradiation with room fluorescent light no color change was observed (i.e., the laminate remained red). Upon irradiation with UV light, the color of the laminate turned from red to ocean blue. The color change was due to the HDFE-18 photochromic dye film between the two polycarbonate films (HFD-15 and HFD-16).