EP2303525B1

EP2303525B1 - Razor blade technology

Info

Publication number: EP2303525B1
Application number: EP09751358.4A
Authority: EP
Inventors: Gordon Krauss
Original assignee: Edgewell Personal Care Brands LLC
Current assignee: Edgewell Personal Care Brands LLC
Priority date: 2008-05-20
Filing date: 2009-05-19
Publication date: 2016-11-30
Anticipated expiration: 2029-05-19
Also published as: WO2009143130A2; WO2009143130A3; EP2303525A2; PL2303525T3; EP2303525A4

Description

Background

1. Technical Field

This disclosure relates to razor blades, and more particularly to methods of treating cutting edges of razor blades. 2. Background
Many razor blades for wet shaving razors have their cutting edges treated with a coating such as polytetrafluoroethylene (PTFE) in order to reduce the cutting force required to use the razor blade. A typical PTFE coating is disclosed for example in U.S. -A-3,774,703 . However, in many instances, the coating applied is too thick for optimal shaving comfort, especially during the first shave. The thick coating on the cutting edge is peeled back during shaving, especially during this first shave. The consequently thinner PFTE coating yields an increased shave performance for the razor blade after the first shave. Accordingly, efforts have been directed towards reliably and reproducibly thinning the blade coating to simulate the effects of the peeled back coating. Examples of methods to achieve a peeled back coating include U.S. -A- 5,985,459 . and US-B-7,247,249 .
US-A-2007/0062047 discloses a razor blade having a cutting edge comprising a polymer film (e.g. PTFE) that can be discontinuous. The film can be a plurality of elongated stripes that extend perpendicular to the cutting edge or can be other patterns provided the pattern allows space for the skin bulge between the coating and the blade.
It is believed the PTFE coating on the cutting edge of a razor blade acts as a hydrophobic layer between the cutting edge and the hair being cut and also between the cutting edge and the skin surface the cutting edge is passing over. In a normal wet shaving operation the inherent hydrophobic nature of the PTFE coating causes a film-like array of water droplets of a microscopic scale to form and be retained on the cutting edge. This film-like array enhances the affect of the normally lubricious PTFE coating to further reduce the aforementioned cutting force.

SUMMARY:

The present disclosure has for its objective to eliminate, or at least substantially alleviate the limitations of the prior art razor blades.
According to the invention, this problem is solved by the subject matter of claim 1. Individual embodiments are the subject matter of the dependent claims.
By applying a surface texture to the cutting edge of a razor blade and/or skin engaging surfaces of the razor cartridge it is possible to lower the friction between these surfaces and corresponding skin and hair surfaces. Furthermore, by applying a suitable coating to the textured surface it is possible to increase the hydrophobicity of the surface.
Surface texturing can be achieved by modification of a surface in an organized pattern or by random roughening of the surface. Surface texturing can be by subtraction from the surface or addition thereto or combinations thereof. Examples of subtraction processes include laser etching. Examples of addition processes include deposition of a material by a sputtering or other suitable vacuum deposition process. Surface texturing can be applied to the substrate of the cutting edge of a razor blade that is then over-coated with a suitable hard coating, such as alpha-diamond or DLC (diamond-like carbon), both being well known in the art. Surface texturing can also be applied to the outer surface of a hard coating applied to the substrate. Surface texturing can also be applied to the outer surface of a lubricious coating applied to the substrate or to the hard coating. Surface texturing can also be applied to the skin engaging surfaces of the razor cartridge housing.
One advantage of the present disclosure lies in that the cutting edge thus textured has increased hydrophobicity and decreased friction relative to the hair being cut during a normal shaving operation thus decreasing the force required to cut the hair resulting in a more comfortable shave for the user.
The above features and advantages of the present disclosure will be more fully understood with reference to the following detailed description when taken in conjunction with the accompanying drawings.

Brief Description of the Drawings:

Fig. 1 is a plan view of an exemplary textured surface of the present disclosure.
Fig. 2 is a plan view of another embodiment of a textured surface of the present disclosure.
Fig. 3A is a plan view of a further embodiment of a textured surface of the present disclosure.
Fig. 3B is a plan view of a yet further embodiment of a textured surface of the present disclosure.
Fig. 4 is a perspective view of an exemplary razor cartridge.
Fig. 5 is a schematic sectional view of the cutting edge portion of a razor blade of the razor cartridge of Fig. 4.

Detailed Description:

Referring now to the drawings and in particular Fig. 4, an exemplary razor cartridge 10 is depicted. The cartridge includes a frame 20 having a skin engaging guard surface 30 adapted to engage the skin surface being shaved in advance of one or more razor blades 50 mounted in the frame 20. Each razor blade 50 includes a cutting edge 60. The frame 20 also includes a skin engaging cap surface 40 adapted to engage the skin surface being shaved after the cutting edges 60 of the one or more razor blades 50. Fig. 5 depicts an enlarged schematic sectional view of the cutting edge portion of the razor blade 50. The razor blade 50 includes a substrate 70 that has a tip 72 and adjacent facets 74 and one or more coatings 80 that are well known in the art such as alpha-diamond or DLC and can have an outer coating 82 of PTFE.
Referring now to Figs. 1 and 2, enlarged views of exemplary textured surfaces 100, 200 respectively are depicted. The surface can be a skin engaging surface of the cartridge frame or the cutting edge of the razor blade. The texture can include combinations of regular shapes such as cylindrical 110 and other polygonal shaped elements 120 as depicted in Fig. 1. The texture can also include random combinations of irregular or random shapes 210 as depicted in Fig. 2. The elements can protrude from or be recessed in the respective surface. Element spacing is at least 10 nm, e.g. at least 50 nm or 100 nm and can be up to about 1 micron or more. Element height is at least 5nm, e.g. at least 10 nm or 25 nm and can be up to 0.1 microns (100 nm). The elements can have a constant cross section along their respective height or can be tapered. Surface texturing can be by subtraction from the surface or addition thereto or combinations thereof. Examples of subtraction processes include laser etching or laser ablation. Examples of addition processes include deposition of a material by a sputtering or other suitable vacuum deposition process. Surface texturing can be applied to the substrate of the cutting edge of a razor blade that is then over-coated with a suitable hard coating, such as alpha-diamond or DLC (dianrond-like carbon), both being well known in the art. Surface texturing can also be applied to the outer surface of a hard coating applied to the substrate. Surface texturing can also be applied to the outer surface of a lubricious coating applied to the substrate or to the hard coating. Surface texturing can also be applied to skin engaging surfaces, e.g. 30, 40 of the razor cartridge housing.
Referring now to Figs. 3A and 3B, further embodiments of a textured surface 300 is depicted. The texture is achieved by a regular or irregular series of elongated elements 310 applied to the surface. The elements can be grooves achieved by e.g. laser ablation or can be deposited by e.g. sputtering a suitable material. The grooves preferably extend parallel to the cutting edge of the razor blade (as depicted in Fig. 3B) or another direction that is not in the direction of movement of the razor blade or the razor cartridge against the skin surface being shaved (as depicted in Fig. 3A). Surface texturing can extend over substantially the entire surface having such a texture (as depicted in Fig. 3A) or can extend over portions of the entire surface having such a texture (as depicted in Fig. 3B). Surface texturing including a series of elongated elements can also be applied to the skin engaging surfaces of the razor cartridge housing. Fig. 5 shows a schematic sectional view of the cutting edge portion of a razor blade having a surface texture on the substrate 70, the layer of one or more coatings 80 and the outer coating 82 of PTFE. However, the surface texturing can be omitted from one or more surfaces, e.g. the surfaces of the substrate.
Surface texturing can also be by combinations of the aforementioned features adjacent to or superimposed on one another.
While various embodiments have been described above, it should be understood that they have been presented by way of example only, and not limitation. For instance, modifications or changes as can be made within the scope of the attached claims and features disclosed in connection with any one embodiment can be used alone or in combination with each feature of the respective other embodiments. Thus, the breadth and scope of any embodiment should not be limited by any of the above described exemplary embodiments, but should be defined only in accordance, with the following claims.

Claims

A razor blade, comprising:
- a substrate (70) with a cutting edge (60) defined by a tip and adjacent facets (74),

- a layer (80) of a coating on the cutting edge (60),

- characterized in that one of the cutting edge (60) and the layer (80) of a coating includes a textured surface including a pattern of elements (110,120,210,310) having a height at least about 5 nm.
The razor blade of claim 1, wherein the pattern of elements (110,120,210,310) is one of a random pattern and a regular pattern, and combinations thereof.
The razor blade of claim 2, wherein the pattern of elements (310) includes a series of elongated elements.
The razor blade of claim 3, wherein the elongated elements (301) extend in a direction parallel to the cutting edge (60).
The razor blade of claim 3, wherein the elongated elements (310) extend in a direction that is not in a direction of movement of the razor blade against a skin surface being shaved.
The razor blade of any of claims 2 to 5, wherein each element (110,120,210,310) of the pattern of elements is spaced at least 10 nm from the next adjacent element.
The razor blade of any of claims 1 to 6, wherein the cutting edge includes an outer layer (82) of polytetrafluoroethylene.