Abstract:
A sealing device for sealing the surface of contents of a container comprises a disc-like member having a central portion and a flexible perimeter and having a centrally located upstanding hollow handle having a purge valve at the upper end thereof. The purge valve has a closed position for preventing egress of air upwardly through said hollow handle and an open position to permit free passage of air therethrough. The disc-like member is contoured to correspond with the shape of the interior plan of the container.

Description:
FIELD OF INVENTION 
     The invention relates to a device for providing a seal in a container such that the seal substantially eliminates contact between the contents of the container and the surrounding air regardless of the height to which the container is filled. More particularly, the invention relates to a sealing device which prevents the formation of a skin on the surface of paint stored within a paint can. 
     BACKGROUND OR INVENTION 
     It is a common experience among people familiar with painting that after placing the lid back on a partially used paint can and then re-opening it at a later date, a skin has formed on the surface of the stored paint. The removal of the skin is a difficult and messy task which often produces unsatisfactory results. 
     Often the skin will break-up and leave particles within the can which tend to mar the surface of the item or wall being painted. 
     The formation of the skin is caused by the reaction between the paint and the surrounding air. Even when a paint can is tightly sealed using the lid provided with the can an amount of air, such amount depending upon the amount of paint that remains in the can, is still trapped within the container. As a result, so long as such air is trapped within the can, an undesirable skin will form. 
     Previous devices have attempted to solve the above problem by isolating the paint within the can from any surrounding air. Examples of such devices are disclosed in the following U.S. Pat. Nos. 4,682,705; 2,828,886; 2,556,195; 4,625,883; 3,266,662 and 4,874,108. 
     These previous devices generally suffer from several problems. First, the devices disclosed are generally complex in construction. As a result of such complexity, their production is an expensive undertaking. Secondly, insertion of several of the previously known devices causes an amount of air to be trapped within the can between the sealing device and the contents of the container. Thirdly, such known devices do not permit easy removal from the contents of the container as a suction will be created when attempting to remove such devices from the surface of the contents. 
     SUMMARY OF INVENTION 
     The disadvantages of the prior art may be overcome by a sealing device which is inserted within the can and placed directly upon the surface of the paint as well as in sealing engagement with the internal wall of the can thereby substantially eliminating any contact between the paint and the surrounding air. A valve releases the trapped air for full contact of the sealing device with the contents and easy removal therefrom. 
     It is therefore desirable to provide a sealing device which substantially eliminates all contact between the contents of a container and the surrounding air regardless of the height to which the container is filled. 
     It is further desirable to provide a sealing device which is simple in design thereby allowing for relatively inexpensive mode of construction, in particular such that the device may be formed by a single injection molding. 
     It is further desirable to provide a sealing device which contains a centrally located purge valve to release air from being trapped between the device and the contents of the container during insertion of the device. 
     It is further desirable to provide a sealing device for use within a paint can which substantially eliminates all contact between the air and the paint thereby preventing the formation of a skin on the surface of the paint. 
     According to one aspect of the invention, there is provided a sealing device for sealing the surface of contents of a container. The device comprises 
     a disc-like member having a central portion and a flexible perimeter and having a centrally located upstanding hollow handle having a purge valve at the upper end thereof. The purge valve has a closed position for preventing egress of air upwardly through said hollow handle and an open position to permit free passage of air therethrough. The disc-like member is contoured to correspond with the shape of the interior plan of the container. 
     In a further aspect of the invention, when the device is urged towards the surface of the contents of the container air trapped therebetween will escape through the purge valve until said device is in intimate contact with the surface, sealing same. When the device is urged away from the surface and the valve is in an open position air will ingress therebetween permitting free removal of the device from the surface. 
     In a further aspect of the invention, the interior of the handle is contoured to receive a like handle for storing like devices in a nested condition. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     In the drawings which illustrate the embodiment of the invention: 
     FIG. 1 is a perspective view of the top of the preferred embodiment of the invention; 
     FIG. 2 is a sectional view of the embodiment of FIG. 1 along the lines 2--2; 
     FIG. 3 is a partial sectional view of the embodiment of FIG. 1 being installed in a paint can; 
     FIG. 4 is a side sectional view of the embodiment of FIG. 1 installed on a paint surface; 
     FIG. 5 is a perspective view of the bottom surface of the embodiment of FIG. 1; 
     FIG. 6 is a sectional view of the embodiment of FIG. 1 along the lines 6--6 in FIG. 5; 
     FIG. 7 is a perspective view of the handle of the embodiment of FIG. 1 with the valve in a closed condition; 
     FIG. 8 is a perspective view of the handle of the embodiment of FIG. 1 with the valve in an open condition; 
     FIG. 9 is perspective view of a second embodiment of the valve stem of the present invention; 
     FIG. 10 is a perspective view of a third embodiment of the valve stem of the present invention; and 
     FIG. 11 is a sectional view of the valve stem of the embodiment of FIG. 10 illustrating the device in a stacked relation. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As shown in FIGS. 1 and 2, the sealing device 1 of the present invention, comprises a generally disc-like member having a rigid central portion 10 with integrally formed flexible perimeter 12. Also formed integrally with the disc is handle 14 and purge valve 16. 
     Referring to FIGS. 7 and 8, handle 14 is centrally located and extends upwardly. Handle 14 has a central internal channel 15. At the upper end of channel 15 is purge valve 16. Purge valve 16 is formed by opposed lip formations 17 and 19 which are biased in a closed position forming a substantially air tight seal. The valve 16 will permit air to pass upwardly through the channel 15. However, when handle 14 is pinched or squeezed, an open passage is formed allowing air to freely pass in either direction. 
     Perimeter 12 of the device is flexible. As shown particularly in FIG. 2 the flexibility of the perimeter 12 is facilitated by a thinning of the material. Such thinning of the material can take the form of a sharp transition point 18 between the rigid portion 10 and the perimeter 12. Alternatively, a gradual thinning of the material from the vicinity of the handle to the edge of the perimeter 20 will also produce satisfactory results. 
     As illustrated in FIG. 3 and 4, the sealing device 1 has a diameter equal to or slightly larger than the diameter of the container or paint can 22. As a result the device provides an effective seal along the interior circumference, between edge 20 and the internal wall of the container or paint can 22. 
     The purge valve 16 is located within the handle 14. When pinched, purge valve 16 permits a flow of air from the lower surface of the device 26 through the handle 14. 
     In a preferred embodiment of the invention, the lower surface of the device 26 contains a series of radial channels or indentations 30 extending from near the edge 20 to the entry of the purge valve 16. (see FIG. 5) 
     In use, the device 1 is inserted into the container or paint can. The flexibility of the perimeter portion of the device permits entry of the device 1 over the lip 21 of the container or paint can 22. The device 1 is urged downwardly towards the surface 28 of the paint. The channels 30 direct the flow of air from beneath the device towards the purge valve 16, as illustrated in FIG. 3. 
     By only allowing flow of air, the purge valve 16 allows the air trapped between the lower surface 26 and the surface of the contents 28 to escape until the device 1 is in substantial contact with the contents. 
     To remove the device 1 from contact with the contents, handle 14 is squeezed creating an open passage from the atmosphere to between the device 1 and surface of the contents 28. Handle 14 is lifted upwardly allowing air to pass permitting device 1 to be freely removed from the surface of the contents 28 without creating a suction effect. 
     The simple and unitary structure of the device allows a simple mode of construction, preferably by injection molding. The choice of a material for construction should be of the type which is non-reactive with paint or the contents being stored in the container, as will be readily apparent to a person skilled in the art. However, nylon 6, 612 or 6--6 is a suitable material for use with most household paints. Suitable nylon materials are available under the trademarks ZYTEL and HYTREL, both available from Du Pont Co. 
     The device of the preferred embodiment can be molded from a single injection molding process. The flowable nylon material is injected into the mold at the top of the handle 14. The thickness of the wall of handle 14 becomes important depending upon the type of material which is injected to form the device 1. Certain materials, after curing will be stiffer than other materials making squeezing of the handle 14 difficult and sometimes impossible. Accordingly, the thickness of the wall of handle 14 should be minimized to permit sqeezability of the handle to open the purge valve 16. 
     Referring to FIG. 9, a second embodiment of the purge valve is disclosed. The handle 114 has an H-shape cross-section to minimize the thickness of the walls 118 maintaining the flexibility thereof. Opening 116 is molded directly to cavity 115. The width of opening 116 which is formed in the mold should be approximately the same size as the shrinkage of the molded material such that after the molded part is ejected from the mold and is allowed to cool, the part will shrink to substantially close the opening 116. 
     When removing the device 1 from the paint can, the handle 114 is squeezed as indicated by the arrows allowing air to pass therethrough. 
     Referring to FIGS. 10 and 11, a third embodiment of the purge valve is disclosed. Purge valve 214 is frustoconical in shape. The upper surface has a central portion which is thinned along a portion of a diameter as illustrated in FIG. 11. A V-shaped groove is formed which is directed downwardly. A cutting tool is used to sever along the diameter to form opposed lip formations 217 and 219. 
     Lip formations are normally in a closed condition but will permit air to pass in a downward direction. The device 1 is installed in a manner as described above. To remove the device 1 from a paint can, the user pulls on handle 214. Valve 216 is biased to allow air to pass in a downward direction minimizing the suction effect allowing the device to be removed from the surface of the paint. 
     In FIG. 11, the channel 215 is enlarged to receive a like handle permitting like devices 1 to be stacked or nested. A large number of like devices may be packaged and stored in an efficient manner using a minimum of space. 
     It is to be understood that the scope of the present invention is not to be limited to the specific embodiments described above. The invention may be practised other than as particularly described and still be within the scope of the accompanying claims.