Abstract:
A delivery system for a shaving aid material includes a hydrophilic foam pad or similar applicator device and shaving aid material disposed in the foam. The foam is attached to the razor cartridge such that during a shaving operation, the foam is squeezed against the user&#39;s skin and the shaving aid material is dispelled from the foam. The shaving aid material is a water soluble composition that may be impregnated into the foam, which may be a nanofoam. A razor cartridge with which the delivery system may be used has a frame that defines a skin-contacting surface, at least one razor blade located in the frame, and the shaving aid delivery system coupled to the skin-contacting surface. A shaving implement having a handle and a razor cartridge attached thereto has the shaving aid delivery system attached to the razor cartridge.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is entitled to the benefit of and incorporates by reference the disclosure of U.S. Provisional Patent Application Ser. No. 60/906,110 filed on Mar. 9, 2007. This application is related to U.S. Provisional Patent Application Ser. No. 60/906,141, filed on Mar. 9, 2007, the disclosure of which is incorporated by reference herein in its entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    This invention relates generally to wet shaving systems and, more particularly, to shaving aid delivery systems that employ a hydrophilic foam as part of the delivery mechanism. 
       BACKGROUND 
       [0003]    Wet shave razor cartridges often employ what is referred to by those skilled in the shaving arts as comfort strips or glide strips. Generally, these strips are positioned on a surface of a razor cartridge that contacts a user&#39;s skin during a shaving operation. As the surface is stroked over the user&#39;s skin, the comfort or glide strips deposit shaving aid material onto the skin. The shaving aid material can be, but is not limited to, a lubricant, a medicament, or combinations thereof and as used herein the term “shaving aid” should be so construed. A problem typical of prior art comfort and glide strips is that their useful life is often shorter than the useful life of the razor blades incorporated into the razor cartridge. 
         [0004]    Comfort strips for enhancing lubricity generally comprise matrix structures having shaving aid material in the form of lubricating polymers incorporated therein so that as the strip is moved across the skin surface, water causes the soluble portions of these polymers to leach from the matrix and be deposited onto the skin. Typically, the shaving aid becomes depleted beyond effective levels after about four or five shaves. 
         [0005]    Both lubricating strips and comfort strips are typically manufactured using injection molding or extrusion techniques. Techniques for fabricating the comfort strips involve the molding or extrusion of the matrix material containing both the soluble polyethylene oxide blends and insoluble polymers and possibly other shaving aid materials. The matrix is generally incapable of releasing the entire soluble portion of the polymer to provide the necessary lubrication. This failure to release all of the soluble portion of the polymer is caused by insufficient exposure time of the shaving aid to water throughout the matrix structure. 
         [0006]    Based on the foregoing, it is a general object of the present invention to provide a structure for a wet shaving system that is capable of providing a sustained, consistent release of shaving aid material from a soluble portion of a polymer to a skin surface during a shaving operation. 
       SUMMARY OF THE INVENTION 
       [0007]    In one aspect, the present invention is directed to a delivery system for a shaving aid material. The system includes a hydrophilic foam pad, strip, sponge, or similar applicator device and shaving aid material disposed in the foam. In preferred embodiments, the foam is attached to the razor cartridge such that during a shaving operation, the foam is squeezed against the user&#39;s skin and the shaving aid material is dispelled from the foam. The shaving aid material is a water soluble composition that provides any number of functions such as lubricity, moisturizing effects, skin-peels, pore cleansing, and the like. Such compositions are typically impregnated into an open-cell structure of the foam or encapsulated in closed cells of the foam. One type of foam useful in practicing the present invention is a nanofoam. As used herein, the term “nanofoam” should be broadly construed to mean foam materials having pore sizes in the nanometer range. 
         [0008]    In another aspect, the present invention is directed to a razor cartridge having a frame that defines a skin-contacting surface, at least one razor blade having an exposed cutting edge located in the frame, and a shaving aid delivery system coupled to the skin-contacting surface and covering at least a portion thereof. The shaving aid delivery system includes a hydrophilic foam having a water soluble shaving aid material disposed therein. The shaving aid material is selectively dispensable from the hydrophilic foam in response to pressure applied to the foam resulting from contact with a user&#39;s skin during a shaving operation. 
         [0009]    In a third aspect, the present invention is directed to a shaving implement having a handle and a razor cartridge attached thereto. A shaving aid delivery system is attached to the razor cartridge. The razor cartridge includes a frame that defines a skin-contacting surface and has at least one razor blade having an exposed cutting edge. The delivery system includes a hydrophilic foam defined by a plurality of struts or walls that define tortuous paths that form a foam strip. Shaving aid material is disposed in the tortuous paths and is dispensable from the foam when the razor cartridge (and the foam) is pressed onto a surface being shaved. The shaving aid material is a water soluble material. 
         [0010]    One advantage of the use of hydrophilic foams as shaving aid delivery devices is that a sustained release of shaving aid can be realized. Because of the hydrophilic nature of the foam, the shaving aid material incorporated therein can be controllably solubilized and released in response to the needs of the user during a shaving operation. 
         [0011]    Another advantage of the use of hydrophilic foams is that the durability and dimensional stability of the foam structure allows the shaving aid dispensing capability of the foam to be maintained over extended numbers of shaves. More specifically, the material from which the foam is manufactured and the particular configuration of the cell structure allows the foam to maintain its structural integrity by, for example, inhibiting the collapse of the cell structure during use. By inhibiting collapse of the cells, shaving aid material (lubricants or the like) can be more efficiently and sufficiently expelled from the foam throughout the useful life of the device into which the foam is incorporated. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is perspective view of a lubricating strip of the present invention for a razor cartridge. 
           [0013]      FIG. 2  is a cross-sectional representation of the lubricating strip of  FIG. 1 . 
           [0014]      FIG. 3  is a side elevation view of the lubricating strip of  FIG. 1  having an adhesive layer disposed thereon. 
           [0015]      FIG. 4  is a cross-sectional representation of foam in which shaving aid material is trapped in the open-cell structure thereof. 
           [0016]      FIG. 5  is a cross-sectional representation of foam in which shaving aid material is trapped in the closed-cell structure thereof. 
           [0017]      FIG. 6  is a cross-sectional representation of foam in which shaving aid material is trapped between lamellae of the foam. 
           [0018]      FIG. 7  is a perspective view of a razor cartridge incorporating the lubricating strip of the present invention. 
           [0019]      FIG. 8  is a perspective view of a razor cartridge coupled to a handle to define a shaving device. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0020]    Referring to  FIG. 1 , a shaving aid material delivery system in the form of a lubricating (or comfort) strip for a razor cartridge is shown generally at  10  and is hereinafter referred to as “strip  10 .” Strip  10  is fabricated from foam and more preferably a nanofoam having a highly reticulated open-cell structure. Strip  10  may also be a nanofoam having a closed-cell structure or a structure having a combination of open cells and closed cells. As indicated above, the term “nanofoam” should be broadly construed to mean foam materials having pore sizes in the nanometer range. As used herein, the term “open-cell” is intended to indicate a structure having a series of interconnected passageways that define a substantially open porosity. As used herein, “highly reticulated” is intended to indicate that the area defined by the cell walls is relatively small compared to the volume of the cells defined by the cell walls. In an open-cell foam structure, the open porosity allows fluid communication to be maintained through substantially all of the cells from one boundary surface of the structure to the same or any other boundary surface of the structure. The strip  10  may be located on a guard structure or surface, a cap structure or surface, or both the guard and cap surfaces of the razor cartridge. In addition, more than one comfort strip can be incorporated into a razor cartridge without departing from the broader aspects of the invention. 
         [0021]    Referring now to  FIG. 2 , the strip  10  is shown as having a series of tortuous paths  12  through which fluid can be transferred. The tortuous paths  12  are defined by walls or “struts”  14  that form the cell structure. Substantially all of the tortuous paths  12  extend from one boundary surface  16  of the strip  10  to the same or another boundary surface, while some tortuous paths  12  extend into the strip from a boundary surface and terminate within the strip. Some tortuous paths  12  may originate and terminate completely within the boundary surfaces  16  to form closed cells  18 . 
         [0022]    The struts  14  impart structure to the strip  10 , and the resiliency of the struts  14  give the strip its foam-like attributes. In particular, the struts  14  that form the tortuous paths  12  can be collapsed upon themselves to allow the strip  10  to be compressed. Upon compression of the strip  10  (e.g., by the application of pressure when pressing the strip onto the surface being shaved), the collapse of the struts  14  reduces the volume of void space defined by each tortuous path  12 . As the volumes of the void spaces are reduced, fluid in the void spaces is forced along the tortuous paths  12  to areas of lower pressure. In general, the area of lower pressure is the area adjacent the boundary surfaces  16  outside the strip  10 . In the preferred embodiments, the fluid in the void space is a shaving aid material. 
         [0023]    The material from which the strip  10  is fabricated is preferably a hydrophilic polyurethane foam. The foam is derived from a prepolymer liquid resin prepared from low molecular weight polyols and polyoxyethylene diols with an isocyanate, particularly toluene diisocyanate. The resulting resin is an alcohol having two or more free isocyanate groups. The free isocyanate groups are hydrolyzed, thereby releasing carbon dioxide gas, which foams the resin. The hydrolysis reaction products react with unhydrolyzed isocyanate to form a second reaction product that cross links with itself and stabilizes the foam structure. Excess water molecules trapped in the struts  14  impart the hydrophilic properties to the foam. 
         [0024]    Upon manufacture, the foam may be mounted to release paper for transport or for storage until the foam is ready to be applied to a shaving device or loaded with shaving aid material. The foam may be mounted to the release paper by dropping the foam onto the paper or by molding the foam directly to the paper. The release paper is a woven or non-woven material. The tack quality of the foam, particularly immediately after its fabrication, is generally sufficient to allow the release paper to be adhered to the foam. 
         [0025]    Referring now to  FIG. 3 , an adhesive  30  is located on a surface of the foam of the strip  10  to mount the strip to a razor cartridge for use. The adhesive  30  is preferably a layer that extends over an area of the strip  10  to facilitate the retaining of the strip on a surface  36  (e.g., the cap surface of the razor cartridge shown at  38 ). The adhesive  30  may be applied to the foam using any suitable technique such as rolling, spraying, or the like. The adhesive  30  may be a polyurethane or similar compound having tack characteristics and being capable of providing a bond between the foam and a surface to which the foam is to be attached. 
         [0026]    Referring now to  FIGS. 4-6 , shaving aid materials that can be used with the strip  10  include, but are not limited to, lubricants, fillers, medicaments, skin-conditioners, vitamins, biocides, pharmaceuticals, humectants, surfactants, and the like. Fragrances and colorants may also be incorporated into the shaving aid materials or into the foam itself. Because of the tortuous nature of the open-cell structure of the foam, outgassing of volatile components incorporated into the foam (e.g., menthol) is minimized. 
         [0027]    A preferred shaving aid material that may be incorporated into the strip  10  is polyethylene oxide, which can include blends of polyethylene oxide whereby polyethylene oxides having different molecular weights are mixed. Any suitable method may be used to impregnate the foam with the polyethylene oxide. During a shaving operation, water trapped in the struts  14  solubilizes the polyethylene oxide and transports it to the skin surface. Although the shaving aid material referred to hereinafter is polyethylene oxide, it should be understood that other shaving aid materials capable of reacting and performing in a similar manner can also be used with the strip  10 . 
         [0028]    The foam from which the strip  10  is formed provides a mechanism that yields a sustained release of shaving aid material over an extended number of shaves. In one embodiment, as shown in  FIG. 4 , polyethylene oxide is shown at  40  and is incorporated into the strip  10  by being located in the tortuous paths  12  between the struts  14 . Surface tension of the polyethylene oxide  40  facilitates the retention of the material in the foam structure of the strip  10 . Upon use of the strip  10  in an aqueous environment, water molecules  44  trapped in the struts  14  migrate to the water of the aqueous environment, thereby solubilizing the polyethylene oxide  40  and facilitating the transport of the polyethylene oxide to the surface being shaved. Transport of the polyethylene oxide  40  is typically effected by a user squeezing the strip  10  or otherwise applying pressure to the strip to drive the water-solubilized polyethylene oxide  40  through the tortuous paths  12  and onto the user&#39;s skin. 
         [0029]    In another embodiment, as shown in  FIG. 5 , the polyethylene oxide  40  (or any other shaving aid material) may be encapsulated directly within the struts  14  that define the tortuous paths  12 . The polyethylene oxide  40  is trapped within the void spaces within the struts  14 , i.e., within closed cell portions of the foam. Upon wetting with water, the polyethylene oxide  40  leaches from the closed cells through the hydrophilic membrane of the strut  14  to the paths  12 , which are in fluid communication with the aqueous environment. Once in the paths  12 , the polyethylene oxide  40  can be transported in the above-described manner to the surface being shaved. 
         [0030]    Referring now to  FIG. 6 , the polyethylene oxide  40  is incorporated directly into lamellae of the hydrophilic foam of the strip  10 . In particular, a substrate layer  50  of foam is used to provide a base layer on which polyethylene oxide  40  is deposited in discrete quantities. A second layer  52  of foam is then deposited over the polyethylene oxide  40  and the exposed portions of the substrate layer  50 . Interfaces  54  are maintained between the substrate layer  50  and the second layer  52  to promote bonding between layers of the foam and to encapsulate the polyethylene oxide  40 . As above, water molecules  44  are present in the foam to facilitate the transport of the polyethylene oxide  40  through the porosity of the foam to the surface being shaved. 
         [0031]    The mechanisms for shaving aid material transfer described with reference to  FIGS. 4-6  can be used in foam individually or in combination with each other. In any embodiment, the struts  14  that define the tortuous paths  12  increase the surface area over which the shaving aid material contacts the water of the aqueous environment. By increasing the surface area over which the shaving aid material contacts the water of the aqueous environment, the water is able to permeate the foam and release the shaving aid material in a consistent manner. 
         [0032]    Referring now to  FIG. 7 , a razor cartridge incorporating the foam delivery system of the present invention is shown generally at  60 . Razor cartridge  60  comprises a frame  61  that defines a skin-contacting surface. The frame  61  includes a guard portion  62 , three blades  64 , and a cap portion  66 . The guard portion  62  is located forward of the blades  64  and in the illustrated embodiment includes a guard bar  68  for stretching a user&#39;s skin prior to the skin contacting the cutting edges defined by the blades  64 . While a guard bar for stretching a user&#39;s skin has been shown and described, the present invention is not limited in this regard as a razor cartridge without a guard bar is also within the scope of the present invention. The cap portion  66  is located aft of the blades  64 . A strip  10  may be located on the guard portion  62  and can be positioned aft of the guard bar  68 . A strip  10  may also be located on the cap portion  66 . In addition, a strip  10  can be located on both the guard portion  62  and the cap portion  66 . Moreover, more than one strip can be incorporated onto one or both of the guard portion  62  and the cap portion  66 . 
         [0033]    As shown in  FIG. 8 , the razor cartridge  60  may be coupled to a handle  80  to define a shaving implement  90 . The razor cartridge  60  can be coupled to the handle  80  in a manner such that the razor cartridge  60  is selectively detachable therefrom, or, in other instances, the razor cartridge may be permanently mounted to the handle as with disposable razors. In either case, the razor cartridge  60  may be pivotally or non-pivotally attached to the handle  80 . In addition, the handle  80  may further include a biasing member that is operable to normally urge the razor cartridge  60  toward a neutral position. 
         [0034]    Referring back to  FIG. 7 , in any embodiment the strips  10  incorporated into the razor cartridge  60  may be similar or identical. Preferably, at least one of the strips  10  is a nanofoam having a highly reticulated open-cell structure defined by the struts and tortuous paths and includes at least one shaving aid material (e.g., polyethylene oxide) that lubricates, medicates, or otherwise advantageously treats the surface being shaved. 
         [0035]    Although this invention has been shown and described with respect to the detailed embodiments thereof, it will be understood by those of skill in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed in the above detailed description, but that the invention will include all embodiments falling within the scope of the appended claims.