Patent Application
20100011588
This invention relates to razor cartridges, and more particularly to a lubricating strip or cap composed of shaving aids for a razor cartridge.
A wet shave razor cartridge is typically composed of a number of sharp blades, a fin guard and at least one shaving aid composite. The shaving aid composite is also sometimes known in the art as a lubricating strip, which continuously releases a shaving aid, typically a lubricant, during the shaving process. Lubricating strips are described in U.S. Pat. No. 6,301,785, U.S. Pat. No. 4,170,821 and GB Patent No. 2,024,082. The shaving aid strip is generally composed of a water-insoluble polymer matrix, typically, polystyrene, and a water-soluble shaving aid, typically polyethylene oxide, which leaches out of the strip during shaving to enhance shave comfort. Increasing the release of lubricant further improves the wet shave experience. This increase has been realized by modifying the shaving aid strip chemistry or formulation. For instance, the use of a certain portion of low molecular weight polyethylene oxide (as described in U.S. Pat. No. 5,113,585), or incorporating a small amount of polycaprolactone (as described in U.S. Pat. No. 6,301,785), without adversely affecting the structural integrity of the strip. It also has been known that a lubricating strip plays a very significant role in reduction of cartridge drag and decrease of hair pulling/tugging, and ultimately provides many benefits such as a safe, comfortable, and smooth shave.
It is also known in the art that a good shave (e.g. comfort and less-irritation) may generally be achieved through either a sophisticated design of a cartridge and handle, or by employing more blades (e.g. 3, 4 and 5 blades) to increase shaving efficiency, or by a significant reduction of blades' hair cutting force via strengthening of the blade edge, optimizing the blade edge profile, or applying a thin lubricious polymer coating on the blade edge. Thus, blades have been made sharper and stronger and slimmer to achieve low cutting force of the blade on a user's skin. Such blades are described in U.S. Pat. Nos. 6,866,894 and 6,684,513, wherein the dimensions of a sharp, slim blade are described.
However, as blades have become sharper, some users have realized adverse affects in that their skin is very sensitive to extremely sharp blades due to their type of skin or their facial contour/curvature, and hence, discomfort, irritation or even nicks and cuts, have been increasingly realized with these sharper, slimmer, and stronger blades.
Thus there is a need to improve the current shaving experience being realized with these sharper, slimmer and stronger blades.
The invention provides a razor cartridge including a plurality of blades and at least one lubricating body, where the body has a maximum height greater than or equal to a maximum blade plane height of said plurality of blades. The lubricating body can be a lubricating strip or a cap or a coated cap, and may be any shape. The blades may be any type and may be of mixed types. For instance, the blades may include low cutting force (sharp) blades. The blades may be at the same height or at different heights. The lubricating body maximum height may be greater than or equal to a height of a blade or blades most proximal to said lubricating body.
In another embodiment of the present invention, a razor cartridge includes a plurality of blades and at least one lubricating body having a strip exposure greater than or equal to about −0.10 millimeters, about 0.00 mm and about 0.10 mm or between about −0.10 mm and about 0.00 mm. The razor cartridge may include a strip angle greater than or equal to zero degrees or between between about 0 degrees and about 10 degrees. The lubricating body is a strip or a cap and of any shape. The blades may be of any type of mixed type and may be at the same heights or a different heights. In one aspect, the lubricating body may be in contact with fluid. In certain embodiments, the strip exposure may be relative to a blade or blades, of the plurality of blades, most proximal to said lubricating body.
In yet another embodiment, the razor cartridge includes a plurality of blades at least one lubricating body having a strip exposure greater than or equal to −0.10 millimeters and a strip angle greater than or equal to zero degrees during shaving.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described below. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.
Other features and advantages of the invention will be apparent from the following detailed description, and from the claims.
While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as forming the present invention, it is believed that the invention will be better understood from the following description which is taken in conjunction with the accompanying drawings in which like designations are used to designate substantially identical elements, and in which:
a are side views of a mushroom shaped lubricating strip relative to the blades showing the lubricating strip exposure in accordance with the present invention.
One significant area that has been not been developed in the prior art is the interaction between the multiple blades and the lubricating strip or cap, and the combined geometry optimization of low cutting force (sharper, slimmer, stronger) blades' edge profile relative to the lubricating strip or cap.
The invention discloses a novel geometry for a lubricating body such as a strip or cap (composed of shaving aids) taking into consideration their shape, materials and placement along with their interaction with multiple sharp blades for improved shaving attributes in a wet shaving system.
The term “geometry” in the present invention signifies both the placement of the strip or cap relative to the blade plane of the razor cartridge and the shape or form or materials of the strip or cap.
A shaving aid is a generic term signifying chemicals within a lubrastrip or those chemicals coated on or embedded in cap. These chemicals may benefit wet shaving users as they are released during shaving.
In the present invention, the lubricating body, strips, caps, or lubricious caps, that are composed of shaving aids are important components of the razor cartridge because generally they play many roles for wet shaving. Firstly, the strip or cap is capable of delivering lubricant onto a user's skin surface while shaving to reduce drag and achieve a smooth shave, while also possibly releasing other chemical ingredients to benefit the skin. Secondly, the strip or cap assists with skin management by slightly stretching the skin to achieve more efficient and closer shave. Thirdly, either functions as a wear-indicator if a color strip is incorporated on its top surface, which signals it soon might be time for a new cartridge. Lastly, the lubricating strip or cap acts as a shoulder to share some of the load from the total pressure exerted by a user on the cartridge.
The cap additionally provides safety for a user while shaving primarily so that the rearmost blades will not cut the user's skin.
The novel aspects of the present invention, therefore, will apply equivalently to both the lubricating strip or the cap and the terms “strip” and “cap” may be used interchangeably in the following description.
Since the “geometry” of the strip or cap is an important aspect in the present invention, the following terms will be important aspects to the present invention and will be described in more detail with regard to the figures below. These terms are: Strip Exposure, Strip Height or Strip Plane (or Maximum Strip Height), Strip Angle, and Blade Plane Height (or Maximum Blade Plane Height).
In the prior art, as shown in
A strip exposure 16 is generally defined as the distance between a maximum height 18 of lubricating strip 14 and the blade plane 15 or the maximum height of the blades, though it can vary depending upon the type of strip 14 or the surface profile of the strip. In the case of a mushroom shape surface, however, such as the type shown in
The optimized geometry with the most appropriate formulation and process (whether it be extrusion, molding or calendaring) will reduce the blade load to achieve the most comfortable shave but without sacrificing closeness. In the present invention, the interaction and synergistic effect between the blades and the geometry optimization of the lubricating strip will be described.
As depicted in
The strip exposure 16 in the embodiment shown in
In
As depicted in
In the embodiment shown in
Therefore, taking into consideration both embodiments of
Thus, for the mushroom shape strip or cap, as long as the blade plane 15 is at or below maximum strip height 18, a strip exposure 16 is formed as provided by the present invention. Hence, a blade plane 15 falling anywhere in between height 18 and height 17 or below height 17 is generally considered to form a strip exposure 16 within the scope of the present invention. It should also be noted that the typical height differential of upper and lower lobes in a mushroom shaped strip or cap is about 200 μm to 250 μm.
In addition to the mushroom shapes shown in
With a rectangular or flat strip or cap of the type indicated in Table 1 above, the strip exposure 16 is the distance between the maximum height of the lubricating strip or strip plane 18 and the blade plane 15 as shown in
If the strip surface is flat but has a slope against blade plane as shown in
Additionally, in accordance with the present invention,
The present invention may also apply to a razor cartridge having both a cap and a strip or any number of caps or strips (not shown). In the case where both a cap and a strip are present, it may be that only the strip has a strip exposure in the range of about −0.10 mm to about +0.10 mm and desirably about 0.00 mm to about 0.05 mm of the present invention and the cap does not, or where the cap only has a strip exposure of the present invention and the strip does not, or where both have a strip exposure as provided by the present invention. The present invention may also apply to a razor cartridge having a strip but no cap, or having a cap but no strip, where in either of the latter instances, there is still a strip exposure as provided by the present invention.
As mentioned above, in the present invention, the lubricating strip (or cap) may have a strip exposure 16 ranging from about −0.10 mm to about 0.10 mm and desirably may have a strip exposure from about 0.00 mm to about 0.05 mm. It has been determined that lubricating strips with strip exposures that are slightly negative, zero or greater than zero (e.g., a positive value), or where the strip plane is just slightly below, at or higher than the blade plane, directly improve comfort-related shaving attributes such as comfort during and after shaving without loss of any other shaving attribute such as overall performance, freedom from nicks and closeness, and in some instances, there may be an indirect improvement, such as with shaving closeness. Therefore, even a very small height change in the strip exposure provides a noticed benefit to the user in terms of shaving attributes.
This results because despite being only a slight change in strip exposure, the new geometry may significantly reduce the blade force load, especially for those blades which are more proximal to the strip and additionally, may also affect load distribution. In a five blade razor cartridge, for instance, the most proximal blades affected may be the last 2 or 3 blades. In some instances, up to a 30% reduction in blade force load may be appreciated. This in turn leads to the improved shaving attributes. Accordingly, it is the geometry of the strip which may translate directly into improved shaving attributes such as comfort and closeness, etc.
Referring now to
In the present invention, the lubricating strip 14 may have a relative strip angle that ranges from about 0 degrees to about 10 degrees, (or about 5.0±5.0 degrees), and desirably may have a strip angle that ranges from about 1 degree to about 7 degrees (or about 4.0±3.0 degrees). On the contrary, the prior art strip angle 22, as shown in
It should be noted that the strip angle differs from what is known as the tilt angle of the strip. The tilt angle is the angle at which the strip sits in the cartridge and is defined as the angle between the blade edge plane 15 and a strip surface plane 82. For instance, referring back to
A typical shaving aid found in a lubricating strip or lubricious coated cap or cap for instance, may include polyethylene oxide (PEO) as the main lubricant, polystyrene (PS) as a matrix and other minor ingredients, such as polycaprolactone, aloe vera, vitamin E, mineral oil/baby oil, colorant and possibly other natural ingredients such as apricot or walnut shell powders. PEO/PS based strips may be produced by extrusion. The addition of polycaprolactone may improve the fabrication of the lubricating strip while also easily controlling the strip exposure with small deviations and furthermore may provide smoother strip surfaces as well as enhance the release of PEO during use.
It is contemplated in the present invention that the lubricating materials for the strip or cap may also include polymers such as polyurethane, polyvinylpyrorridone (PVP), nylon, polyethylene, polypropylene, poly(methyl methacrylate), polytetrafluoroethylene, poly(acrylonitrile, butadiene, styrene), and others. Additionally, the lubricating strip could even be comprised of metal, alloys or wood. The lubricating strip could also be rubber, such as silicone and other elastomers. Plastic or rubber strips may be made by extrusion, molding, or calendaring.
It is further contemplated in the present invention that the shaving aid composite may contain more than one lubricating strip; there may be two, three or even more strips, with similar or varying shapes and/or any combination thereof. And as mentioned above, some of these lubricating strips contain a lubricant in the entire strip body while others may have a lubricious layer only on the surface of strip. The top surface of the lubricating strip or cap may or may not be uniform in the present invention.
Thus, one further aspect of this invention is directed towards optimizing the geometries mentioned above (strip exposure and/or strip angle and placement) for different types of lubricating strips for use with a wet shave razor having multiple blades.
As mentioned above, shaving tests have shown that a wide variety of types of strips with a “high strip” or “high cap” (e.g., having a strip exposure as defined above in accordance with the present invention), particularly a positive strip exposure relative to the blades, provide improved shaving benefits, attributes such as better overall performance, comfort during shaving, freedom from nicks, closeness and comfort after shaving, without sacrificing one or the other. One of these advantageous lubricating strips may be an aluminum type strip made by electrical discharge machining. A chromium coating is sputtered on the top surface of an aluminum strip followed by a very thin coating of PTFE applied on the top of chromium. Such a lubricating strip therefore consists of an aluminum base and a chromium interlayer and a polytetrafluoroethylene (PTFE) top layer and is considered a non-leachable lubricating strip. Such a non-leachable strip of the present invention may obtain optimized strip exposure values on average, in the ranges mentioned above of about 0.00 mm to about 0.10 mm, and desirably about 0.00 mm to about 0.05 mm to provide improved shaving attributes.
In accordance with a further aspect of the present invention, the lubricating strip or cap geometry and materials necessarily takes into account the fact that a lubricating strip or the lubricating material on a cap may wear off as the user shaves with the razor cartridge. Thus, it is beneficial to provide a stable geometric relationship between the strip plane and blade plane such that the variation in shaving benefits that one would expect as the strip wears during use is reduced significantly or basically eliminated.
One factor to consider with regard to the strip geometry is that a taller or high lubricating strip may be taller than a shorter lubricating strip not only because it is set higher than the blade plane but because it is perhaps formed with more lubricant on top than a shorter strip. On average though, the taller the strip, the faster the strip wears. Nevertheless, the taller strip will still be more effective at reducing blade force load and possibly load distribution than a shorter strip regardless of its composition, which in turn provides better shaving benefits, such as comfort during and after shaving, etc. without sacrificing any shaving performance.
Another factor to consider with regard to the strip geometry and materials is that a lubricating strip typically swells when it comes into contact with fluid such as water (e.g., during shaving). In general, swelling will make the lubricating strip slightly taller. A lubricating strip or cap 14 which when dry may be positioned below the blade plane, but when wet (e.g., during shaving) may rise or swell above the blade plane as shown in
Swelling, which makes the lubricating strip slightly taller, is beneficial as discussed above, but will also increase the wear rate of the strip since a swollen strip will wear faster than an unswollen strip. To offset the swelling, the addition of an oil (such as mineral oil or baby oil) may play a role in reducing the swelling of the strip so as to provide an appropriate wear rate. The addition of about 1 percent of baby oil in a typical lubricating strip may provide appropriate geometry relative to the blades during the course of shaving history.
Yet another factor to consider related to the strip geometry and materials is that some razor cartridges have mixed blade heights and/or mixed blade types.
With regard to mixed blade heights, the plurality of blades in the present invention may be arranged with any combination of varying blade plane heights. Referring to
In
The razor system of the present invention may have a strip arranged relative to a razor cartridge where all the blades are of the same type, e.g., all are sharper and slimmer than a traditional razor blade, or of mixed types, sharpness, slimness, strength, etc. Sharp, slim blades are described in U.S. Pat. Nos. 6,866,894 and 6,684,513. A typical thickness of a stainless steel blade substrate may be about 75 μm. A cutting edge formed with a wedge-shaped configuration may have an ultimate tip radius of about 200 to about 300 angstroms, where the cutting edge may be coated with a diamond-like carbon hard layer, a chromium overcoat layer and a very thin polytetrafluoroethylene (PTFE) outer layer.
Thus, in yet another embodiment of the present invention (not shown) the strip may be combined with some blades that are sharp and slim but others that are normal or traditional, e.g. four sharp blades and one normal blade. Tests have substantially determined that higher strip exposures with the sharper/slimmer blades provided the best shaving attributes, comfort and closeness. Accordingly, even though the sharper/slimmer blades provide closeness attributes, the discomfort, irritation, and other negative affects associated with having a majority of sharper/slimmer blades in a cartridge may be minimized or diminished significantly through the geometry of the lubricating strip or cap while also still providing the closeness shaving attribute abd without sacrificing other shaving attributes. Formulation and fabrication processes (e.g., extrusion or molding) may also play a role because they may indirectly affect the strip geometry by varying the wearing and swelling rates when the strip gets wet during shaving.
It should also be noted therefore, that while improved results in comfort and closeness are seen with a higher strip and the sharper/slimmer blades, effectively, regardless of the type, height, or combination thereof of the blades in the cartridge, the fact that there is a strip exposure within the ranges described above, improved shaving attributes are provided. This follows for the strip angle as well.
Such shaving improvements related to lubricating strip exposure have been verified in both manual and power wet shave razor systems having multiple blades.
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”.
All documents cited in the Detailed Description of the Invention are, in relevant part, incorporated herein by reference; the citation of any document is not to be construed as an admission that it is prior art with respect to the present invention. To the extent that any meaning or definition of a term in this written document conflicts with any meaning or definition of the term in a document incorporated by reference, the meaning or definition assigned to the term in this written 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.
