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Sustained release air freshening device

Sustained release air freshening device description/claims

This is a Continuation of U.S. application Ser. No. 10/967,448 filed on Oct. 18, 2004.

1. Field of the Invention

This invention relates to a device that provides controlled release of a fragrant or deodorizing substance: the fragrant or deodorizing substance being solublized in a carrier solvent within a polymeric matrix. The device can be mounted in almost any location but it is primarily intended for use inside an automobile by hanging from a rearview mirror or adhering to a window or another substantially flat surface. The device can be transparent so as to be inconspicuous or to permit viewing of an image bearing layer or may be colored by methods known to those skilled in the art.

2. Problems in the Art

Modification of the odor of the surrounding air has long been accomplished through the use of fragrant materials or deodorizing agents to mask and even neutralize offending odors. Malodor has been shown to cause nausea, headaches, coughing, irritation of mucous membranes, and shortness of breath. The need for odor modification is greatest in locations with an increased likelihood of offending odors, such as restrooms and kitchens, and in confined locations where people spend a considerable amount of time, such as an office or in an automobile.

Numerous methods to combat malodor in automobiles are documented in the patent literature. U.S. Pat. No. 4,814,212, Automobile Air Freshener Unit, by Spector (Mar. 21, 1989), describes adhesively attaching a framed replaceable gel air freshener to a car window. However, the Spector invention fails to provide any control over the rate of release and the device not a multi-laminate multi-layer device which possesses the advantages of such a system. Similar devices may be hung from rear view mirrors and can employ paper or cardboard substrates as fragrance reservoirs. Product use recommendations for such air fresheners provide an impractical procedure involving the gradual removal of the protective barrier film in order to manually regulate the rate of fragrance release over the period of use.

Air fresheners that attach to or are inserted into air filters are described in U.S. Pat. No. 3,577,710, Air-Treatment Apparatus, by Feldman (May 4, 1971); U.S. Pat. No. 3,902,877, Container for Air Treating Agent, by Swaim (Jun. 7, 1977); U.S. Pat. No. 4,563,333, Deodorizing Fitting for Air Filters, by Ward (Jan. 5, 1986); and Japanese Patent JPO 04151438, Method and Apparatus for Generating Perfume, by Toshio (May 25, 1992). None of the aforementioned inventions are intended for use in the passenger compartment of an automobile.

Air fresheners that are intended for use in the passenger compartment of an automobile and attachable to the air vents are described in U.S. Pat. No. 5,269,723, Vehicle Air Freshener, by Bender (Dec. 14, 1993); U.S. Pat. No. 5,865,372, Air Freshener for Vehicle, by Ceresko (Feb. 2, 1999); U.S. Pat. No. 6,103,201, Propellar Air Freshener, by Green (Aug. 15, 2000); U.S. Pat. No. 6,123,906, Air Freshening Device for Automobiles, by Blount (Mar. 6, 2001); and U.S. Pat. No. 6,416,043, Louver Air Freshener, by Eisenbaum (Jul. 9, 2002). While the aforementioned devices are suitable for use in an automobile, they do not have a rate controlling mechanism and are only mountable on the vent louvers of the automobile air system.

Air fresheners that are intended for use in the passenger compartment of an automobile, possessing a features to provide limited control over the rate of release of the fragrance, are described in U.S. Pat. No. 4,686,353, Aroma-Generating Automobile Cigarette Lighter, by Spector (Aug. 11, 1987); U.S. Pat. No. 5,373,581, Automobile Plug-In Air Freshener With Rotatable Switch And Vaporizer, by Smith (Dec. 13, 1994); U.S. Pat. No. 5,394,506, Fragrance Dispenser For An Automobile, by Stein (Feb. 28, 1995); U.S. Pat. No. 5,788,931, Air Freshener For Motor Vehicles, by Quintana (Aug. 4, 1998); U.S. Pat. No. 6,021,254, Timed Electric Vehicular Air Freshener, by Hunter (Feb. 1, 2000); and U.S. Patent Application 2002/0176704, Air Freshener For Motor Vehicles, by Roe (Nov. 28, 2002). All of die aforementioned inventions utilize automobile DC socket cigarette lighter to heat a substrate and release a fragrance. U.S. Pat. No. 6,021,254 adds a timer that allows the invention to release fragrance at timed intervals. U.S. Patent Application 2002/176704 allows the user to modify the rate of release by varying the current supplied to a light bulb acting as the heating element for the device. All of the above inventions require active rate control measures on behalf of the user and still provide insufficient control over the release of a fragrance to avoid a fragrance spike early in the life cycle of the fragrance containing substrate. Additionally, the all of the devices occupy a DC socket, a useful automobile appliance, and detract from the aesthetics of the automobile interior.

These prior methods, while useful, fall short of meeting consumer expectations. The most significant problem is the inability of prior devices to regulate the release of the fragrance to achieve a constant release rate. While there have been devices which have made gains in this area through the use of reservoirs surrounded by a rate controlling membrane, none have been entirely successful. Additionally, the duration of such devices is extremely limited, requiring frequent replacement. U.S. Pat. No. 4,874,129 by DiSapio et al. utilizes a multi-layer multi-laminate silicone based device to achieve it's goal of regulating the release of the fragrance. The '129 patent, unlike the present invention, requires layers comprised of adhesives to bind additional layers to the reservoir, uses silicone based oligomers, does not use an additional layer similar to the reservoir to diffuse the fragrance/solvent mix into before release and does not mention doping such a layer to facilitate diffusion, does not modify the cross-link density in order to modify the release rate, and the photo-cure polymer cannot be cured to produce an adhesive cure at desired areas on the surface.

In the published unexamined Japanese Patent Application No. 2000086781 by Takashi et al., the patentee describes photopolymerizing a resin of urethane acrylate oligomer, single organic-function (meta)acrylate, polyfunctional (meta)acrylate, a perfume component, and a photopolymerization initiator to achieve a film which stores perfume. However, the invention described in the Takashi application utilizes urethane acrylates modified to create flexible linkages and blended with other monomers. The present invention does not require modified urethane acrylates and is not blended with other monomers. The present invention utilizes a polybutadiene backbone not described in the Takashi application.

The Takashi device also requires low cross-link densities and low viscosities in order to apply the resin as a coating on sheets while the UV curable, oligomeric composition of the present invention has a significantly higher viscosity. The significantly higher viscosity and cross-link density of the present invention also produces a device which resists shrinkage and cracking thus increasing the useful life of the product by delaying the degradation of the device.

The invention is directed to the use of an improved means for distributing a fragrance by employing an oligomeric system made by the Michael addition of β-dicarbonyl donor compounds with mixtures of hydroxyl-functional acrylates and multifunctional acrylates receptor compounds to store and release a fragrant material in a controlled fashion over an extended period of time. The novel UV curable, liquid oligomeric composition (derived from the reaction of the Michael addition product and the isocyanate capped polybutadiene) incorporates a butadiene backbone in the UV curable, oligomeric composition. The UV curable, oligomeric composition can be cured in the presence of a fragrance and optional carrier solvent for the fragrance. It is the cured residue of the UV curable, oligomeric composition that is utilized in various applications as a controlled release air freshener.

The presence of the isocyanate capped polybutadiene makes the UV curable, liquid oligomeric composition more accepting of fragrance based materials and helps to overcome the deficiencies in typical UV curable materials. These deficiencies are typically observed as shrinkage, brittleness, and cracking. The presence of the polybutadiene helps to greatly enhance the flexibility of the system allowing for thick films, e.g. about 60 mil, of fragrance containing UV curable, oligomeric composition to be cast and cured. These materials are more amenable to loss of the fragrance while still exhibiting plasticity. In addition, shrinkage of the system and the corresponding cracking that is present in typical UV curable materials is significantly reduced or in many cases eliminated.

The UV curable, oligomeric composition produces unique gel systems when radiation cured in combination with fragrances. Said fragrance gels have been shown to hold fragrance molecules and their excipient or carrier solvents at high levels, i.e. up to 60% by mass and preferably from 30% to 50% by mass, and to release said fragrances in a regulated or controlled fashion over several weeks. These materials are capable of forming fragrance containing films, but show substantial shrinkage during the fragrance release cycle in comparison with fragrance containing films prepared using the UV curable, liquid oligomer systems taught in this invention. The UV curable, liquid oligomeric composition of the present invention can be selectively cured to produce adhesive surface areas by either modulating the radiation or inhibiting the cure. Cure inhibition can be achieved within, the UV curable, oligomeric composition through selectively choosing a fragrance that will inhibit the cure thus create pockets of low and high cross-link density.

On cure, the fragrance, excipient, matrix gel system contains swelled polybutadiene domains carrying the incorporated fragrance and it's solvent. In the subject system, the most effective solvents are those which have a high polarity as well as hydrophobiscity. An example of this would be the hexane glycols. While not wishing to be bound by theory it is believed that the systems readily compatibilize with the polybutadiene segments through their aliphatic constituents, while their hydroxyl constituents bond with the polar fragrance molecules. Diffusion of the solvent to the gel surface also results in a migration of the fragrance to the surface since it is dragged along through the polar interactions. Evaporation of solvent at the gel surface decreases surface polarity and increases the ease of fragrance molecule volatilization.

The invention is preferably a multi-layered multi-laminate which uses the preferred gel or UV cured, oligomeric composition as a reservoir impregnated with a fragrant oil and a suitable carrier solvent to aid diffusion. Diffusion to the surface of the gel is controlled by areas of high and low cross-link density that impede the movement of the solvent and subsequent transport of the fragrant oil. The ability to create a selectively adhesive gel allows the potential elimination of adhesives to bond additional layers directly to the gel. This additional layer acts to further control diffusion and thus regulate the release of the fragrance to achieve a release of fragrance which is both prolonged and consistent over time. This additional layer acts to further control diffusion and thus regulate the release of the fragrance to achieve a release which is both prolonged and consistent over time. If an adhesive were required this could prevent the use of a second gel layer as a regulator. Similar systems using appropriate adhesives with or without channels to permit solvent migration are anticipated by this invention.

One advantage of the present invention is that it can be clear and transparent. Other commercially available fragrance storing compositions are typically opaque. Those commercially available fragrance storing compositions that tend to be somewhat transparent tend to have a yellow tint. Image bearing layers can be included in the device to display logos, messages, pictures, or aesthetically pleasing designs. Additionally, layers which can receive ink from a printer may also be affixed, thus allowing the consumer to personalize their own air freshener. The device may be selectively cut and shaped into aesthetically pleasing two or three dimensional forms. The present invention also minimizes shrinkage, thus inhibiting the cracking and splitting seen in other gel air fresheners due to the relatively high viscosity of the UV curable, oligomeric composition and its higher cross-link density.

The device may be mounted several different ways depending upon the environment and preference of the user. In one embodiment it may be hung from a mirror with either a gel reservoir or a paper blotter reservoir. In another embodiment the device is mounted to a window using a layer that can cling to the window using static cling. In yet another embodiment the device is adhesively attached to the window or another sufficiently flat surface within an automobile.

• Provisional Patent
• Utility Patent

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