Abstract:
A wet shaving cartridge is provided having a housing having a guard located at a front end of the housing and a cap located at a rear end of the housing. The cartridge further has two or more elongate blades located between the guard and cap and extending in a direction substantially parallel to a length of the guard, wherein edges of the respective blades lie in a shaving plane extending between the guard and the cap. A shaving aid retention member is located in the cap. The retention member has a base arranged to receive a shaving aid and a front wall located at a side of the retention member adjacent the blades. The front wall extends from the base of the retention member towards the shaving plane.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a wet shaving razor cartridge having a retention member for receiving a shaving aid, the retention member having a front wall, the front wall extending from a base of the retention member towards a shaving plane of the razor cartridge. 
     BACKGROUND OF THE INVENTION 
     Wet shaving razors have evolved over the years to include a multiplicity of blades, guards and caps with lubricant strips, all with the goal of increasing the closeness of a shave while also providing a comfortable shaving experience. 
     In razor cartridges manufactured and sold by The Gillette Company, a lubricating strip is typically provided at the back of the cartridge, after the blades. Such a lubricating strip may comprise skin conditioning agents that improve the appearance and sensation encountered by the shaver upon completion of the shaving stroke. The lubricating strip may comprise a shaving enhancement product such as a lubricant. Razor cartridges comprising lubricating strips formed of polystyrene (PS) porous rigid matrices containing poly-ethyleneoxide (PEO) are known. These lubricating strips are typically snap-fit directly into the frame of the cartridge. 
     The rigid structure of the PS serves to provide a skin supporting surface at the back of the razor cartridge to prevent skin from being pushed low onto and between the blades. However, over time, the PEO leaches out of the PS matrix leaving behind just the matrix. The porous structure that is left behind can result in an uncomfortable shave due to the lack of lubrication and the scratchy sensation the matrix causes when brushed against skin. Further, the size of the matrix typically varies significantly through the course of multiple shaves—initially increasing in volume as the lubricating strip is exposed to water and subsequently reducing in size as the PEO leaches out. This variation in size can affect the general dynamics of the shave when the razor cartridge is used such that after a number of shaves, the razor cartridge is not as comfortable to use. 
     The present invention seeks to provide an alternative means of placing shaving aid on a razor cartridge while additionally providing more consistent dynamics in the shave. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a wet shaving cartridge comprising a) a housing having a guard located at a front end of the housing and a cap located at a rear end of the housing, b) one or more elongate blades located between the guard and cap and extending in a direction substantially parallel to a length of the guard, wherein edges of the respective blades lie in a shaving plane extending between the guard and the cap, a shaving aid retention member located in the cap, the retention member having a base arranged to receive a shaving aid and a front wall located at a side of the retention member adjacent the blades, the front wall extending from the base of the retention member towards the shaving plane. 
     The retention member provides a platform on which shaving aid can be located. This allows for flexibility in the type/form of shaving aid. When in use, it is anticipated that the quantity of shaving aid provided on a razor cartridge will decrease. The front wall of the retention member provides a minimum amount of consistency in terms of blade geometry. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the invention will hereinafter be described, by way of example, with reference to the accompanying drawings, in which: 
         FIG. 1  is a front view of one possible embodiment of a wet shaving razor. 
         FIG. 2  is a schematic cross-sectional side-view through x-x of a possible embodiment of the razor cartridge shown in  FIG. 1 . 
         FIG. 3  is a cross-sectional view of an alternative embodiment of the razor cartridge shown in  FIG. 2 . 
         FIG. 4  is a perspective view of an embodiment of a retention member as shown in the razor cartridges of  FIGS. 1 to 3 . 
         FIGS. 5  ( a ), ( b ) and  6  ( a ), ( b ), ( c ) show alternative embodiments of the retention member shown in  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention is applicable to razor cartridges in general that are used in a wet shaving system. 
       FIG. 1  shows a wet shaving razor  10  formed of a razor cartridge  12  attached to a handle  14 . The razor cartridge  12  is formed of a housing  16  having a front wall  18 , a rear wall  20  and first and second opposing side walls  22 ,  24  disposed transverse to and between the front wall  18  and rear wall  20 . Two of more blades  26  with sharp cutting edges  28  are mounted within the housing  16  and extend between the first and second opposing side walls  22 ,  24 . The tangent between cutting edges  28  of the first  62  and last  64  blade defines a shaving plane A (shown in  FIGS. 2 and 3 ) between the guard and the cap. Four blades are shown in the embodiment of  FIG. 1 , however, it will be understood that more or fewer blades may be mounted within the housing  16 . 
     The razor cartridge  12  further has a guard  30  located ahead of the blades and a cap  32  located after the blades. In the embodiment shown, the guard is disposed on the front wall of the housing and the cap is disposed on the rear wall of the housing. However, it will be appreciated that in an alternative embodiment, the guard may be formed separately to the housing and mounted directly to the razor handle  14 , or formed as an entirely separate component and located between the handle and razor cartridge. 
       FIG. 2  shows a schematic cross-sectional side view through x-x of the razor cartridge of  FIG. 1 . The cap  32  is formed of a retention member  34  on which a shaving aid  35  may be disposed. The retention member  34  has a base  36  and a front wall  38  located at a side of the retention member adjacent the blades. In the embodiment shown in  FIG. 2 , the retention member  34  is shown to be a single L-shaped structure for receiving a shaving aid. However, it will be appreciated that that the retention member  34  could be formed in segments to result in two or more retention members, still having a base  36  and front wall  38 . The retention member  34  is shown in embodiments to be a separate article located within the housing  16 . However, it will be appreciated that the retention member  34  may be formed integrally with the housing  16  in alternative embodiments. 
     The position of an edge  40  of the front wall  38  relative to the shaving plane controls the amount of skin bulge that will be possible between the last blade  64  and the front wall  38 . In embodiments, the edge  40  may be a distance, d, between 0, 0.05, 0.1, 0.15, 0.2 and 0.3, 0.35, 0.4 mm below the shaving plane A, while still reducing the amount of discomfort that may be caused to a user of the razor cartridge through skin bulge following the last blade  64 .  FIG. 2  shows an embodiment where d is 0 and the edge  40  lies in the shaving plane, A.  FIG. 3  shows an embodiment where d is approximately 0.4 mm and the edge  40  lies beneath the shaving plane. 
     Referring now to  FIG. 3 , the height, h, of the front wall  38  is determined by a depth of the razor cartridge. In embodiments, the height, h, is between 0.5, 1, or 1.5 and 2, 2.5, or 3 mm. The effect on skin bulge is also determined, in part, by the proximity of the edge  40  of the front wall  38  to the edge  28  of the last blade  64 . In embodiments, the edge may be a distance, y, between 0.4, 0.5, 0.6 to 0.7, 0.8, 0.9 mm away from the edge  68  of the last blade  64 . 
     A shaving aid  35  is disposed on the retention member  34 , as shown in  FIGS. 2 and 3 . The shaving aid  35  may be a pre- or post-shaving aid intended to, for example, improve the appearance and sensation encountered by the shaver upon completion of a shaving stroke. By way of example, the shaving aid may be hydrophobic oil or a lipid based material (that is delivered to the surface being shaved by direct abrasion with the surface) or a hydrophilic water soluble material (that is delivered by dissolution). Shaving aids which can be used include those disclosed in U.S. Pat. Nos. 7,069,658, 6,944,952, 6,594,904, 6,182,365, 6,185,822, 6,298,558 and 5,113,585. 
     Use of the retention member  34  increases the flexibility in choice of shaving aid  35  that can be placed on the razor cartridge. For example, in some razor cartridges currently on the market, the chemistry has to be impregnated in a structured matrix, for example, poly-ethyleneoxide in a polystyrene matrix or a sponge. In the embodiment described herein, the retention member  34  provides the structure and a greater variety of chemical substances can be deposited on the base  36  of the retention member  34 . In embodiments, the shaving aid is in a solid or semi-solid state and is preferably a material that can be poured onto the retention member and subsequently set, a material that can be pressed onto the retention member, or a material that can be prefabricated and bonded to the retention member. 
     In an embodiment, shown in  FIG. 3 , the shaving aid  35  may be thicker than the height of the front wall  38  such that a top surface  52  of the shaving aid  35  protrudes above the edge  40  of the front wall  38  of the retention member  34 . In the embodiment shown in  FIG. 2 , the top surface  52  is in line with the edge of the front wall. For certain shaving aid materials, for example, PEO, it is likely that when the shaving aid interacts with water, it may increase in volume, thus causing the top surface  52  of the shaving aid to rise from its original position. In all embodiments, it is expected that as the razor cartridge is used repeatedly, shaving aid will be deposited on the surface being shaved and the volume of the shaving aid will decrease. 
     Regardless of the initial position of the top surface  52  of the shaving aid, as it recedes beneath the level of the edge  40  of the front wall  38 , the front wall  38  maintains geometry with the blades, limiting the amount of skin bulge between the final blade and the retention member. 
     The base  36  of the retention member  34  has a generally rectangular or oval shape, and extends generally across the width, w (shown in  FIG. 1 ), of the razor cartridge. In the embodiments shown in  FIGS. 2 and 3 , the front wall  38  and base  36  of the retention member  34  are shown to be perpendicular to one another. However, it will be appreciated that the front wall  38  could be set at a different angle relative to the base  36 . Furthermore, the base  36  is shown to be substantially parallel to a top surface  58  of the razor cartridge. However, it will be appreciated that the base could be set at an angle relative to the top surface  52  of the shaving aid. 
     To retain the shaving aid  35  in position on the retention member  34 , the retention member  34  may have side walls  61 ,  63  as shown in  FIG. 4  and/or a back wall  66 , shown in  FIGS. 5(   a ) and ( b ). To ensure that, during use, it is possible to deposit the shaving aid on skin, the height of the side walls  61 ,  63  is less than that of the front wall  38 .  FIG. 6(   c ) shows side walls having gradually decreasing heights from a front end  70  of the retention member to a rear end  72  of the retention member  34 . The side walls could have a straight top edge, be curved, or reduce in height in a stepped manor. Alternatively, the side walls may extend only partway along the sides of the retention member, as shown in  FIG. 4 . The back wall  66  is shown in  FIG. 5(   b ) to be approximately half the height of the front wall  38  to enable contact between the shaving aid and the surface being shaved even after the shaving aid begins to recede. 
     Alternatively and/or additionally, (as shown in  FIGS. 6(   a ),  6 ( b ) and  6 ( c )) the base of the retention member may be provided with depressions ( 80 ), ridges ( 82 ), projections ( 84 ) or grooves ( 86 ) to retain positioning of a shaving aid that is subsequently located in the retention member. For example,  FIGS. 5(   a ) and  5 ( b ) show embodiments where the base  36  has one or more depressions  80  that extend part or all the way through the base  36 . The shaving aid may be pressed or allowed to set into the depressions  80  such that the depressions  80  provide an anchor. This is particularly useful when the shaving aid is made wet or heated as the shaving aid may become slippery or soft. Alternatively, to anchor the shaving aid, the base of the retention member may be provided with projections or grooves on which the shaving aid can either be set or pressed. For example,  FIGS. 6(   a ),  6 ( b ) and  6 ( c ) shows embodiments where the base  36  of retention member  34  is provided with spikes  84  or ridges  82  on which the shaving aid may be pressed or set. 
     The retention member may be made of semi-rigid polymeric material having a Shore A hardness of about 50, 60 or 70 to about 90, 110 or 120. In some embodiments, the retention member may be molded from the same material as the housing, for example, Noryl™ (a blend of polyphenylene oxide (PPO) and polystyrene). Alternatively, the retention member may be formed of thermoplastic elastomers (TPEs) or rubbers, examples of which include, but are not limited to: silicones, natural rubber, butyl rubber, nitrile rubber, styrene butadiene rubber, styrene butadiene, styrene (SBS) TPEs, styrene ethylene butadiene styrene (SEBS) TPEs. The retention member is made of material that is sufficiently wear resistant that even after multiple uses, the front wall of the retention member retains its initial geometry relative to the shaving plane. 
     At least the front wall of the retention member is formed of a material that is non-erodable under normal shaving conditions. Non-erodable materials include those that do not erode or deform under normal shaving conditions, such as being placed in a warm water bath (at 50° C.) for 1 minute, followed by being rubbed on a 5″×2″ strip of full grain leather 20 times with 2 PSI of pressure applied to the sample material, including non-soluble materials where less than 5% by weight of the sample dissolves in a 100 ml 25° C. water bath under no agitation. Water-insoluble materials are detailed in U.S. Pat. No. 6,449,839. 
     In embodiments, as shown in  FIGS. 2 and 3 , the edge  40  of the front wall has a rounded profile to avoid discomfort to a person using the razor cartridge, particularly as the top surface of the shaving aid recedes beneath the level of the edge of the front wall. 
     As shown in  FIG. 1 , the wet shaving razor cartridges of the present invention may be mounted on a handle  14  with the intention that the entire razor should be discarded when the sharp edges  28  of the blades  26  have become dull. Alternatively, the wet shaving cartridges of the present invention may be detachably mounted to a handle  14  so that the cartridge may be replaced on the handle  14  when the blade edges  28  have lost the sharpness required for efficient shaving. In typical cartridges, the blades  26  are usually carried by the housing  12 , which is generally a molded plastic frame, and the blades  26  may then be supported to move within the frame, either independently of each other or in unison, under forces imparted on the blades  26  by the skin during shaving. In one embodiment, for support within the housing, the blades  26  are mounted fixedly within slots in a blade retaining member. In another instance, the blades may be floatably mounted within the housing. Here, the plurality of blades is supported by one or more spring loaded blade retaining members where such blades are permitted to respond to the forces encountered during shaving. 
     In each embodiment of the invention, the level of comfort obtained with any given wet shaving razor cartridge is influenced strongly by the shaving geometry, which is the relative positioning of the skin contacting components. Important parameters of the shaving geometry include the blade exposure which is the distance by which the tip of the blade edge projects above, or is retracted below, a plane which is tangential to the skin contacting parts next in front and next behind the blade edge, the blade tangent angle (also known as the blade shaving angle) which is the angle at which the plane of the blade is inclined to a plane which is tangential to the guard and the cap surfaces (the tangent plane), and the blade span which is the distance by which the blade edge is spaced from the skin contacting element immediately in front of the blade edge, as seen in a plane which is tangential to the blade edge and the skin contacting element in front of it. A progressive blade exposure may be used in the present invention as detailed in U.S. Pat. No. 6,212,777. 
     The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as “40 mm” is intended to mean “about 40 mm.” 
     Every document cited herein, including any cross referenced or related patent or application, is hereby incorporated herein by reference in its entirety unless expressly excluded or otherwise limited. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein or that it alone, or in any combination with any other reference or references, teaches, suggests or discloses any such invention. Further, to the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern. 
     While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.