阅读说明：本技术 剃刀刀片涂层 (Razor blade coating ) 是由 A·西奥兹奥斯 K·马弗罗伊德 于 2020-10-26 设计创作，主要内容包括：用于手持式剃刀的剃刀刀片,所述剃刀刀片包含终止于基板边缘部分中的不锈钢剃刀刀片基板,其中所述基板边缘部分具有连续锥形几何形状,其中两个基板侧面朝向基板边缘汇聚；并且其中至少所述基板边缘具备包含元素钛、硼和碳的硬涂层。(A razor blade for a hand held razor comprising a stainless steel razor blade substrate terminating in a substrate edge portion, wherein the substrate edge portion has a continuously tapered geometry with two substrate sides converging toward a substrate edge; and wherein at least the substrate edge is provided with a hard coating comprising the elements titanium, boron and carbon.)

1. A razor blade for a hand held razor comprising a stainless steel razor blade substrate terminating in a substrate edge portion, wherein the substrate edge portion has a continuously tapered geometry with two substrate sides converging toward a substrate edge; and is

Wherein at least the substrate edge is provided with a hard coating comprising the elements titanium, boron and carbon.

2. The razor blade of claim 1 wherein an adhesion promoting coating is deposited on at least the substrate edge to provide a first coated substrate edge and the hard coating is deposited on at least the first coated substrate edge.

3. The razor blade of claim 1 or 2 wherein said hard coating comprises titanium carbide and titanium boride.

4. The razor blade of any one of claims 1 to 3 wherein said hard coating comprises at least 70 at%, more specifically at least about 80 at%, and specifically at least about 90 at% of said elements titanium, boron and carbon.

5. The razor blade of claim 1 wherein said hard coating comprises a dispersion based on TiB₂Carbon in the matrix.

6. The razor blade of any one of claims 1 to 4 wherein the atomic ratio between boron and titanium in the hard coating is between 2.3:1 and 1.2:1, more specifically between about 2.1:1 and about 1.4:1, and specifically between about 2.0 and about 1.5: 1.

7. The razor blade of any one of claims 1 to 5 wherein said hard coating comprises between 2 and 25 at% carbon, more particularly between about 4 and about 18 at% carbon, and particularly between about 5 and about 9 at% carbon.

8. The razor blade of any one of claims 1 to 6 wherein said hard coating layer is comprised of a single layer comprising titanium, boron and carbon; or wherein the hard coating is comprised of a plurality of sub-layers, wherein a first set of sub-layers comprises titanium and boron and a second set of sub-layers comprises titanium and carbon.

9. The razor blade of claim 7 wherein said plurality of sublayers form an alternating arrangement of layers comprising titanium carbide and layers comprising titanium boride.

10. The razor blade of claim 7 or 8 wherein said plurality of sub-layers comprises between 3 and 20 sub-layers, more particularly between about 4 and about 15 sub-layers, and particularly between about 6 and about 12 sub-layers.

11. The razor blade of any one of claims 1 to 9 wherein said hard coating has a thickness of between 10 and 500nm, more particularly between about 50 and about 300nm, and specifically between about 80 and about 250 nm.

12. The razor blade of any one of claims 2 to 10, wherein said adhesion promoting coating comprises at least 70 at%, more specifically at least about 80 at%, and specifically at least about 90 at% Ti, Cr, or TiC.

13. The razor blade of any one of claims 2 to 11 wherein the adhesion promoting coating has a thickness of between 10 and 100nm, more specifically between about 10 and about 50nm, and specifically between about 10 and about 35 nm.

14. The razor blade of any one of claims 2 to 12 wherein the thickness ratio between said hard coating and said adhesion promoting coating is between 20:1 and 5:1, more specifically between about 14:1 and about 6:1, and specifically between about 12:1 and about 8: 1.

15. The razor blade of any one of claims 1 to 13, wherein a cross section of a blade edge portion has a substantially symmetrical tapered geometry terminating in a blade tip, wherein said cross section has a central longitudinal axis originating from said blade tip, and a thickness of said blade edge portion is between 1.5 μ ι η and 2.4 μ ι η measured at a distance of 5 μ ι η from said blade tip along said central longitudinal axis.

16. A razor cartridge comprising one or more razor blades according to any one of claims 1 to 15.

Technical Field

This application claims the benefit of european patent application EP19212307.3 filed on 28.11.2019, the content of which is incorporated herein by reference.

The present inventive concept relates to razor blades and more particularly to razor blade edges and razor blade coatings.

Background

In accordance with the prior art, razor blades have been provided. The razor blade is suitably placed in a razor cartridge, providing the ultimate function of cutting hair or shaving. The shape of the razor blades and the coating of the razor blades play an important role in the quality of the shave.

Razor blades are generally described by describing aspects of the cutting edge of the blade. The cutting edge of a blade is generally described as terminating in an edge portion which in turn terminates in the final edge of the blade (or simply, the blade edge). The edge portion of the blade typically has a continuously tapered geometry wherein the two lateral blade edges converge and form the blade edge. Considering the cross section of the edge portion of the blade, the blade edge is also referred to as the blade tip. If the edge portion and blade edge are shaped to be robust, the razor blade will experience less wear and exhibit a longer useful life. However, this blade profile will also produce a large cutting force that adversely affects shaving comfort. A thinner profile will result in less cutting force but will also increase the risk of fracture or damage and thus a shorter service life. The profile of the edges and edge portions of the razor blades is therefore based on a compromise between cutting force, shaving comfort and the desired service life.

The edges and edge portions of the blades may be multi-layered in that the corresponding portions of the substrate of the blades (typically a stainless steel substrate that undergoes grinding to form a continuous tapered geometry, with the two substrate sides converging toward the substrate edge) may be coated with various coatings to improve cutting performance and shaving experience. Specifically, the edge of the blade may be coated to provide increased hardness, which in turn increases the life expectancy of the blade.

However, providing a coating on the razor blade edge is a challenge for a variety of reasons. First, because the substrate edge has a very specific geometry, it is difficult to deposit a coating on the substrate edge that will serve as a suitable coating by improving the cutting performance and durability of the razor blade edge. Second, razor blades are a large consumer commodity, and therefore coatings must be applied consistently and at high yield between products, which requires coatings that are compatible with a very reliable process. Third, and perhaps most importantly, the edge of the razor blade must be very thin, and the thickness of the blade edge is typically only a few microns. This lack of material thickness can have a number of consequences in designing blade coatings: first, the experience of conventional process coatings cannot be easily transferred to razor blades. Conventional industrial process coatings are typically several microns (typically up to 15 μm) in thickness, and such bulky coatings cannot be easily applied to the edges of a filament razor blade. However, the bulk of industrial process coatings provides compressive stress resistance, thus avoiding the initiation and propagation of fractures in the coating. The bulkiness itself also provides a degree of inherent fracture toughness, as a larger volume also means more sites in the coating material that can act as energy absorbing points, which would otherwise generate lattice dislocation motion and crack propagation. Finally, the edge of the razor blade is so thin compared to conventional industrial process coatings that the deformation of the razor blade edge during the cutting action of the blade is not negligible and the stresses induced in the hard coating exceed comparable stresses in conventional industrial process coatings. In sum, the design of razor blade coatings is subject to a unique set of design considerations that are not shared with other coating applications. Thus, disadvantageously, it is not a straightforward practice to apply conventional industrial process coatings to razor blades. In fact, it is necessary to thoroughly investigate whether potential candidate coatings are suitable for use as razor blade coatings.

Attempts have been made to coat razor blades or to modify such coatings in the prior art. For example, WO 2006/027016 a1 discloses a razor blade coating comprising chromium and carbon. More recently, WO 2016/015771 a1 discloses a razor blade comprising a reinforcement coating comprising titanium and boron. This application reports having TiB content as compared to similar inserts coated with chromium and carbon_xThe coated razor blade maintains its cutting ability, shape and integrity during the cutting operation in a more efficient manner.

However, despite advances in improving the hard coating of razor blades, there is still a need to further improve the durability of the blades, particularly for blade designs having particularly thin blade edges and low cutting forces.

Disclosure of Invention

The present inventors have conducted extensive studies to identify coatings that are suitable for application in razor blades and that have sufficient hardness, but elasticity and fracture toughness to provide improved wear and degradation resistance to the razor blade during use.

In one aspect, the present disclosure is directed to a razor blade for a hand held razor comprising a stainless steel razor blade substrate terminating in a substrate edge portion. The substrate edge portion may have a continuous tapered geometry, wherein the two substrate sides converge towards the substrate edge. At least the substrate edge may be provided with a hard coating comprising the elements titanium, boron and carbon.

In some embodiments, the hard coating is disposed directly on the edge of the substrate. Alternatively, a hard coating comprising the elements titanium, boron and carbon may be provided indirectly on the substrate edge. In particular, in some embodiments, an adhesion promoting coating is deposited at least on the substrate edge to provide a first coated substrate edge, and a hard coating comprising the elements titanium, boron, and carbon is deposited at least on the first coated substrate edge.

In some embodiments, the hard coating may comprise titanium carbide and titanium boride. In some embodiments, the hard coating may further comprise boron carbide.

In some embodiments, the hard coating may comprise at least 70 at%, more specifically at least 80 at%, and specifically at least 90 at% elemental titanium, boron, and carbon. In particular, the hard coating 11, 21 may comprise between 90 at% and 100 at% of the elements titanium, boron and carbon. More specifically, the hard coating 11, 21 may comprise at least 95 at% elemental titanium, boron, and carbon. Thus, the hard coating 11, 21 may comprise between 95 at% and 100 at% of the elements titanium, boron and carbon. More specifically, in some embodiments, the hard coating may consist essentially of the elements titanium, boron, and carbon. In other embodiments, other elements may be present as impurities, and in particular, they may be present in trace amounts.

In some embodiments, the atomic ratio between boron and titanium may be between 2.3:1 and 1.2:1, more specifically between 2.1:1 and 1.4:1, and specifically between 2.0 and 1.5: 1.

In some embodiments, the hard coating may comprise between 2 and 25 at% carbon, more specifically between 4 and 18 at% carbon, and specifically between 5 and 9 at% carbon.

In some embodiments, the hard coating may be comprised of a single layer comprising titanium, boron, and carbon.

In some embodiments, the hard coating may be comprised of a plurality of sublayers, wherein a first set of sublayers comprises titanium and boron and a second set of sublayers comprises titanium and carbon. In some embodiments, the plurality of sub-layers may form an alternating arrangement of layers comprising titanium carbide and layers comprising titanium boride. In some embodiments, the plurality of sub-layers may include between 3 and 20 sub-layers, more specifically between 4 and 15 sub-layers, and specifically between 6 and 12 sub-layers.

In some embodiments, the thickness of the hard coating may be between 10 and 500nm, more specifically between 50 and 300nm, and specifically between 80 and 250 nm. The thickness of the coating can be determined by measuring the thickness of the hard coating on the edge of the coated substrate.

In some embodiments, the adhesion promoting first coating may comprise at least 70 at%, more specifically at least 80 at%, and specifically at least 90 at% Ti, Cr, or TiC.

In some embodiments, the thickness of the adhesion promoting coating may be between 10 and 100nm, more specifically between 10 and 50nm, and specifically between 10 and 35 nm. The thickness of the adhesion promoting coating can be determined by measuring the thickness of the adhesion promoting coating on the edge of the first coated substrate.

In some embodiments, the thickness ratio between the hard coating and the adhesion promoting coating can be between 20:1 and 5:1, more specifically between 14:1 and 6:1, and specifically between 12:1 and 8: 1. The thickness of the coating can be determined by measuring the thickness of the hard coating on the edge of the coated substrate. The thickness of the adhesion promoting coating can be determined by measuring the thickness of the adhesion promoting coating on the edge of the first coated substrate.

In some embodiments, the cross-section of the blade edge portion may have a substantially symmetrical tapered geometry terminating at the blade tip, and the cross-section may have a central longitudinal axis originating from the blade tip. The blade edge portion may have a thickness of between 1.5 μm and 2.4 μm measured at a distance of 5 μm from the blade tip along the central longitudinal axis.

In another aspect, the present disclosure is directed to a razor cartridge comprising one or more razor blades as described in the above aspects.

Drawings

Fig. 1 is a schematic cross-sectional view of an edge portion of a razor blade.

Fig. 2a, 2b and 2c show representative XPS measurements of hard coatings containing titanium, boron and carbon.

Fig. 3 is a schematic cross-sectional view of an edge portion of a razor blade including an adhesion promoting coating.

Detailed Description

Hereinafter, specific embodiments of the present disclosure will be given. The terms or words used in the specification and claims of the present disclosure should not be construed restrictively to have only common language or dictionary meanings, but should be construed to have common technical meanings as determined in the related art unless otherwise specifically defined in the following description. Detailed description specific embodiments and drawings of the present disclosure will be better described with reference to these specific embodiments and drawings, but it should be understood that the disclosure presented is not limited to these specific embodiments and drawings. Features and advantages of the present disclosure will be readily apparent from the following description of some embodiments thereof, provided as non-limiting examples, and the accompanying drawings.

In one aspect, the present disclosure is directed to a razor blade for a hand held razor. Razor blades are primarily composed of a stainless steel substrate that has been subjected to grinding to form an edge in the substrate. More specifically, the substrate is shaped such that it terminates in a substrate edge portion having substrate sides that converge toward the substrate edge.

Fig. 1 shows an exemplary representation of a substrate edge portion 10. The substrate edge portion 10 has a continuously tapered geometry, wherein the two substrate sides 10a, 10b converge towards the substrate edge 10 c. The continuous tapered geometry of the cross-sectional shape of the substrate edge portion 10 may be straight, angled, arcuate, or any combination thereof. Further, the cross-sectional shape may be symmetrical or asymmetrical with respect to the central longitudinal axis. Fig. 1 shows an exemplary cross-sectional shape of the substrate edge portion 10 that is symmetrical about a central longitudinal axis (not shown) and continuously tapers in a linear fashion toward the substrate edge 10 c.

According to the present disclosure, at least the substrate edge 10c is provided with a hard coating 11 comprising the elements titanium, boron and carbon. When referring to the substrate edge 10c provided with the hard coating 11, it is understood that such reference refers not only to the strict geometric edge of the substrate body, but also to the edge thereof which is subjected to the cutting operation. Thus, the term substrate edge 10c is also intended to cover those portions of the substrate sides 10a, 10b which are immediately adjacent to the strict geometric edge of the substrate edge portion 10. In an exemplary embodiment, the area forming the substrate edge 10c extends along the central longitudinal axis of the substrate edge portion 10 away from the strict geometric edge of the substrate edge portion by the following distance: 5 μm or less, 10 μm or less, 15 μm or less, 25 μm or less, 50 μm or less, 75 μm or less, 100 μm or less, 125 μm or less, 150 μm or less, 175 μm or less, or 200 μm or less.

As schematically shown in fig. 1, the hard coating 11 may be provided not only on the substrate edge 10c, but additionally also on the substrate sides 10a, 10b of the substrate edge portion 10. The hard coating 11 may be intentionally extended to (or beyond) the substrate sides 10a, 10b to improve razor blade performance, or it may be a byproduct of the coating technique employed. The hard coating 11 may generally follow the surface and contour of the underlying substrate edge portion 10. Thus, as shown in fig. 1, the hard coat layer 11 may form a blade edge 11 c. However, the hard coat layer 11 need not be uniform in itself, e.g., having a uniform thickness and/or composition.

The hard coating 11 comprises the elements titanium, boron and carbon. When referring to the elements titanium, boron and carbon, it is understood that these elements may be present in any form, for example in their elemental form or chemically bonded in an intermetallic phase, in particular in borides or carbides. When referring to a hard coating, it is to be understood that such a coating may be harder than the coated substrate portion and/or that the coated substrate portion may be hardened in its entirety as compared to the uncoated substrate portion. For the purposes of this disclosure, any coating comprising the elements titanium, boron and carbon may be considered a hard coating 11. However, it is also possible to determine the hardness of the hard coat layer 11 or hard coat coated substrate by using a nanoindenter, as described in more detail in the examples.

The method of determining the presence of the elements titanium, boron and carbon in the hard coat layer 11 is not particularly limited. For example, these elements can be detected by chemical analysis of the blade edges using various common surface analysis methods (e.g., X-ray photoelectron Spectroscopy (XPS), Auger Electron Spectroscopy (AES)), which can provide quantitative and qualitative information about the elements, respectively. Fig. 2a to 2c show exemplary results of XPS measurement of the hard coat layer 11 containing titanium, boron and carbon. As shown in fig. 2a, the presence of titanium can be determined by measuring the presence of a titanium 2p XPS peak at about 454 eV. As shown in fig. 2b, the presence of boron can be determined by measuring the presence of the boron 1s XPS peak at about 188 eV. As shown in fig. 2c, the presence of carbon can be determined by measuring the presence of a carbon 1s XPS peak at about 283 eV. Of course, other characteristic XPS peaks may also be used.

The substrate of the razor blade may comprise stainless steel. The choice of stainless steel is not particularly limited. Particularly suitable stainless steels may comprise iron as the main alloying element and comprise 0.3 to 0.9 wt.% carbon, specifically 0.49 to 0.75 wt.% carbon; 10 to 18% by weight of chromium, in particular 12.7 to 14.5% by weight of chromium; 0.3 to 1.4 wt.% manganese, specifically 0.45 to 1.05 wt.% manganese; 0.1% to 0.8% silicon, specifically 0.20 to 0.65% by weight silicon; and 0.6 to 2.0 wt% molybdenum, specifically 0.85 to 1.50 wt% molybdenum. In some embodiments, the stainless steel may consist essentially of the elements described above, and in particular, may not contain more than 3 wt.%, in particular 2 wt.%, of other elements.

In some embodiments, such as shown in FIG. 1, the hard coating 11 may be disposed directly on the substrate edge portion 10. In some embodiments, the hard coating 11 may be deposited on the substrate edge portion 10.

In some embodiments, it may be advantageous for the razor blade to further comprise an adhesion promoting coating to promote secure attachment of the hard coating 11 to the substrate edge portion. In particular, in some embodiments, an adhesion promoting coating is deposited at least on the substrate edge 10c to provide a first coated substrate edge, and the hard coating 11 comprising the elements titanium, boron and carbon is deposited at least on the first coated substrate edge.

An exemplary embodiment comprising an adhesion promoting coating is shown in fig. 3. Fig. 3 shows an exemplary representation of a substrate edge portion 20. The substrate edge portion 20, including the substrate edge itself, is coated with an adhesion promoting coating 22. The adhesion promoting coating 22 is then coated with the hard coating 21. The adhesion promoting coating 22 may be provided not only on the substrate edge 10c but additionally on the substrate sides 10a, 10b of the substrate edge portion 10.

The type of adhesion promoting coating 22 is not particularly limited. In some embodiments, the adhesion promoting first coating 22 may comprise at least 70 at%, more specifically at least 80 at%, and specifically at least 90 at% Ti, Cr, or TiC.

In some embodiments, the thickness of the adhesion promoting coating 22 may be between 10 and 100nm, more specifically between 10 and 50nm, and specifically between 10 and 35 nm.

In some embodiments, the hard coating 11, 21 may comprise titanium carbide and titanium boride. In some embodiments, the hard coating 11, 21 may further comprise boron carbide. Such carbides and borides are typically formed when the elements titanium, boron and carbon are deposited by thin film deposition techniques such as Physical Vapor Deposition (PVD), Chemical Vapor Deposition (CVD) and related techniques. In some embodiments, the hard coating 11, 21 may comprise a TiB-based₂And carbon is dispersed within the matrix. In some embodiments, the dispersed carbon may form local bonds with titanium and boron, respectively. In some embodiments, the dispersed carbon may not form local bonds with titanium and boron, respectively.

While the hard coating 11, 21 may contain primarily the elements titanium, boron, and carbides, it is understood that the hard coating 11, 21 may also contain other elements. Other elements may be present as impurities, possibly due to ingress of elements from the blade substrate, or intentionally added to fine tune certain properties. In some embodiments, the hard coating 11, 21 may comprise at least 70 at%, more specifically at least 80 at%, and specifically at least 90 at% of the elements titanium, boron, and carbon. In particular, the hard coating 11, 21 may comprise between 90 at% and 100 at% of the elements titanium, boron and carbon. More specifically, the hard coating 11, 21 may comprise at least 95 at% elemental titanium, boron, and carbon. Thus, the hard coating 11, 21 may comprise between 95 at% and 100 at% of the elements titanium, boron and carbon. More specifically, in some embodiments, the hard coating may consist essentially of the elements titanium, boron, and carbon. In other embodiments, other elements may be present as impurities, and in particular, they may be present in trace amounts.

In some embodiments, the hard coating 11, 21 may further comprise a lubricating phase, such as molybdenum disulfide (MoS)₂). These coating additives may provide a lower coefficient of friction and may be co-sputtered with the hard coating 11, 21. In this way, a lubricating phase may be provided throughout the coating volume, reducing the coefficient of friction and maintaining the hardness of the razor blade at a higher level even after initial surface wear. In addition, the cutting force generated by a razor blade with a multiphase coating may be reduced during shaving compared to the cutting force generated by a razor blade with the same coating but without the lubricating phase.

Although the hard coating 11, 21 comprising titanium, boron and carbon generally has an improved wear resistance due to a very suitable combination of hardness, fracture toughness inhibiting fracture initiation and propagation, and compressive stress resistance inhibiting fracture propagation, the inventors have surprisingly found that a suitable adjustment of the atomic ratio of titanium, boron and carbon may further improve the wear resistance of the razor blade.

Thus, in some embodiments, the atomic ratio between boron and titanium may be between 2.3:1 and 1.2: 1. The method of determining the atomic ratio is not particularly limited, and may be performed, for example, by energy dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS), Auger Electron Spectroscopy (AES), X-ray fluorescence (XRF), and Secondary Ion Mass Spectroscopy (SIMS). In some embodiments, an atomic ratio between boron and titanium of between 2.3 and 1.2:1, more specifically between 2.1 and 1.4:1, and specifically between 2.0 and 1.5:1 may be advantageous.

In some embodiments, the hard coating 11, 21 may comprise between t 2 and 25 at% carbon. The method of determining the amount of carbon in the coating is not particularly limited and may be performed by the same method as outlined above for the atomic ratio between boron and titanium. In some embodiments, it may be advantageous for the hard coating 11, 21 to comprise between 4 and 18 at% carbon, more particularly between 4.5 and 14 at% carbon, and specifically between 5 and 9 at% carbon.

In some embodiments, it may be advantageous for the atomic ratio between boron and titanium in the hard coating 11, 21 to be between 2.1 and 1.4:1, and for the hard coating 11, 21 to contain between 4 and 18 at% carbon.

In some embodiments, it may be advantageous for the atomic ratio between boron and titanium in the hard coating 11, 21 to be between 2.1 and 1.4:1, and for the hard coating 11, 21 to contain between 4.5 and 14 at% carbon, and specifically between 5 and 9 at% carbon.

In some embodiments, it may be advantageous for the atomic ratio between boron and titanium in the hard coating 11, 21 to be between 1.9 and 1.4:1, and in particular between 2.0 and 1.5:1, and for the hard coating 11, 21 to comprise between 4 and 18 at% carbon.

In some embodiments, it may be advantageous for the atomic ratio between boron and titanium in the hard coating 11, 21 to be between 1.9 and 1.4:1, and specifically between 2.0 and 1.5: 1; the hard coat layer 11, 21 comprises 4.5 and 14 at% carbon, and specifically between 5 and 9 at% carbon; and the hard coating 11, 21 comprises at least 70 at%, more specifically at least 80 at%, and specifically at least 90 at% of the elements titanium, boron and carbon.

The deposition method suitable for depositing the hard coating 11, 21 allows for a variety of designs of the hard coating 11, 21. Thus, in some embodiments, the hard coating 11, 21 may be composed of a single layer comprising titanium, boron, and carbon. In some embodiments, the hard coating 11, 21 may be composed of a plurality of sub-layers, wherein a first set of sub-layers comprises titanium and boron, and a second set of sub-layers comprises titanium and carbon. In some embodiments, the plurality of sub-layers may form an alternating arrangement of layers comprising titanium carbide and layers comprising titanium boride. In some embodiments, the plurality of sub-layers may include between 3 and 20 sub-layers, more specifically between 4 and 15 sub-layers, and specifically between 6 and 12 sub-layers. In some embodiments, the sub-layer comprising titanium carbide may have a thickness of 1 to 4nm, specifically 2 to 3nm, and the sub-layer comprising titanium boride may have a thickness of 0.5 to 2nm, specifically 0.8 to 1.3 nm.

In some embodiments, the thickness of the hard coat layer 11, 21 may be between 10 and 500nm, more specifically between 50 and 300nm, and specifically between 80 and 250 nm.

In some embodiments, the thickness ratio between the hard coating 11, 21 and the adhesion promoting coating 22 may be between 20:1 and 5:1, more specifically between 14:1 and 6:1, and specifically between 12:1 and 8: 1.

The razor blade may further comprise other coatings. In one embodiment, the razor blade further comprises an outer layer disposed on the hard coating 11, 21. The outer layer may be a lubricating layer, which may comprise a fluoropolymer, specifically Polytetrafluoroethylene (PTFE). The lubricating layer is used to reduce friction during shaving. In other embodiments, other hydrophilic coatings, such as silicon-based lubricants, such as Polydimethylsiloxane (PDMS) or lubricious coatings comprising polyethylene glycol (PEG), may also be applied to provide a lubricious effect. In another embodiment, the razor blade further comprises a chromium-containing top coat disposed on the hard coat 16. In the case where both the chromium-containing top coat and the lubricating layer are used, the lubricating layer is provided on the chromium-containing top coat, and the chromium-containing top coat is provided on the hard coats 11, 21.

As explained above, the improved wear resistance due to the extremely suitable combination of hardness, fracture toughness and compressive stress resistance makes the hard coatings 11, 21 particularly suitable for relatively thin insert edge designs. Thus, in some embodiments, a cross-section of a razor blade edge portion has a substantially symmetrical tapered geometry terminating in a blade tip, wherein the cross-section has a central longitudinal axis originating from the blade tip, and wherein the thickness of the blade edge portion is between 1.5 μm and 2.4 μm, specifically 1.57 to 2.35 μm, measured at a distance of 5 μm from the blade tip along the central longitudinal axis. In some embodiments, the edge portion of the blade has a thickness of between 4.6 μm and 6.8 μm, specifically 4.62 to 6.74 μm, measured at a distance of 20 μm from the blade tip along the central longitudinal axis. In some embodiments, the edge portion of the blade has a thickness of between 10.3 μm and 14.4 μm, specifically 10.32 to 14.35 μm, measured at a distance of 50 μm from the blade tip along the central longitudinal axis. In some embodiments, the thickness of the edge portion of the blade is between 19.8 μm and 27.6 μm, specifically 19.82 to 27.52 μm, measured at a distance of 100 μm from the blade tip along the central longitudinal axis.

The razor blades described above may be manufactured by any suitable means. More specifically, the preparation and grinding of the blade substrate may be carried out by any suitable means, for example as disclosed in US 2017/136641a1, which is incorporated by reference in its entirety.

The coating may also be applied by any suitable means. Both the hard coating 16 and the adhesion promoting coating 18 may be deposited using thin film deposition techniques such as Physical Vapor Deposition (PVD) and Chemical Vapor Deposition (CVD), respectively. Specifically, in the PVD family of technologies, DC sputtering, RF sputtering, closed magnetic field unbalanced magnetron sputtering (CFUMS), ion beam sputtering, cathodic arc deposition, and high power pulsed magnetron sputtering (HiPIMS) can be employed using sintered TiBC targets in an Ar atmosphere. It is also possible to use in an Ar atmosphere or TiB₂Co-sputtering TiB₂And a TiC sintered target and a C target in an Ar atmosphere to provide the hard coat layer 16. Hard coat layer 16 may also be on Ar/CH₄Use of TiB in an atmosphere₂And (4) coating deposition. Examples of CVD techniques for producing hard coat layer 16 include low pressure CVD (lpcvd), atmospheric pressure CVD (apcvd), Atomic Layer Deposition (ALD), and metal organic CVD (mocvd) using precursors. Exemplary deposition processes are described in US 2018/215056 a1 and US 10,442,098B 2, both of which are incorporated by reference in their entirety. In some cases, in an industrial mass production environment, some statistical variability may be introduced into the chemical composition of the hard coating 11, 21 for the method selected for depositing the hard coating 11, 21. Thus, in some embodiments, it may be advantageous for the atomic percentages and ratios indicated elsewhere in this specification to refer to the average of measurements from multiple measurements, e.g., the average of 5 measurements.

The outer coating, e.g., a lubricious coating, can also be applied by any suitable means. Methods of manufacture are well known to the skilled person.

In another aspect, the present disclosure is directed to a razor cartridge comprising one or more razor blades as described in the above aspects.

Hereinafter, an exemplary method of making a razor blade coating according to the first aspect of the present disclosure will be described in more detail:

after loading the blade bayonet onto the rotating fixture of the deposition chamber, the chamber was evacuated to 10 deg.f^-5Base pressure of torr. Ar gas is then inserted into the chamber at a pressure of up to 8 mTorr (8X 10)^-3Tray). Rotation of the blade bayonet was started at a constant speed of 6rpm and the target was operated under control of a DC current of 0.2 amps. A DC voltage of 200-600V was applied to the stainless steel blade for 4 minutes to perform the sputter etch step. In another embodiment, a pulsed DC voltage of 100-600V was applied to the stainless steel blade for 4 minutes to perform the sputter etch step.

Subsequently, after the sputter etch step was completed, an adhesion promoting interlayer was deposited, and the chamber pressure was adjusted to 3 mtorr. The sandwich target was operated under control of a DC current of 3-10 amps while a DC voltage of 0-100V was applied to the rotating blade. The deposition time is adjusted to deposit an interlayer of 5-50nm prior to depositing the hard coat layer. In another embodiment, a pulsed DC voltage of 0-100V may be applied during interlayer deposition.

After the interlayer is deposited, a film of the TiBC compound is deposited on top of it to form a hard coat. TiB₂And C target are operated simultaneously. Can be controlled by changing the C target current from, for example, 1 amp to 7 amps while maintaining TiB₂The target current is constant to control the relative amount of C deposited. During deposition, a DC bias voltage of 0-600V is applied to the rotating blade.

Finally, on top of the hard coating, a top layer of Cr can be deposited on a Cr target at a current of 3 amps and a bias voltage of 0-450V.

As explained above, in some embodiments, either of the hard coatings 11, 21 or the adhesion promoting coating 22 may be disposed not only on the substrate edge 10c, but additionally may also be disposed on the substrate sides 10a, 10b of the substrate edge portion 10.

Examples of the invention

TiBC hardcoats of various compositions (examples 1 to 5) were deposited on stainless steel blade substrates following the fabrication procedure outlined above. Can be changed by changing the C target current while maintaining TiB₂The target current was constant to change the relative composition of the TiBC hard coating. All other parameters and conditions remained unchanged. During deposition, a DC bias voltage of 0-600V is applied to the rotating blade. The resulting chemical composition of the obtained hard coat layer was analyzed by XPS. The results are shown in table 1 below:

table 1:

thus, adjusting the C target current produces a co-sputtered TiB containing the following C concentrations₂C hard coating:

table 2:

examples of the invention	Carbon target Current (Ampere)	Carbon concentration (%)
			Comparative example	0	0
Example 1	0.3	2.4
			Example 2	1	5.5
Example 3	2	8.1
			Example 4	5	17.2
Example 5	7	21.2

Representative samples of TiBC hardcoats obtained using the above process parameters were subjected to nanoindentation testing. Briefly, the procedure for performing the nanoindentation test was as follows: in the nanoindentation process, a hard tip whose properties (mechanical properties, geometry, tip radius, etc.) are known is penetrated through a hard coating sample to be analyzed. In the present case, a Berkovich tip was used for the indentation test. The load applied by the indenter tip increases as the tip penetrates further into the sample until a penetration depth of 50-100nm is reached. At this point, the load is held constant for a period of time, and then the ram is removed. The area of residual indentation in the sample was measured. Hardness H is defined as the maximum load P_maxDividing by the residual indentation area a:

the following results were obtained:

table 3:

examples of the invention	Carbon concentration (%)	Hardness (GPa)
			Comparative example	0	15.13
Example 1	2.4	15.69
			Example 2	5.5	17.14
Example 3	8.1	17.75
			Example 4	17.2	17.15
Example 5	21.2	16.94

As can be seen from table 3 above, the hard coating layer containing Ti and B provided a hardness of 15.13GPa (comparative example). If carbon is dispersed in TiB₂In the matrix, then the hardness was improved in all cases (comparative examples versus examples 1 to 5). Furthermore, it has surprisingly been found that the hardness is not randomly dispersed in the TiB₂The amount of carbon in the matrix varies linearly but has an optimum at a specific C concentration (examples 2, 3 and 4).

In addition, razor blades coated with a TiBC hard coating were evaluatedThe blade edge of (a) is deteriorated. In particular, razor blades prepared as described for the comparative examples had conventional TiB as compared to razor blades prepared as described for optimal examples 3 and 4 with TiBC hard coatings₂And (3) hard coating. The evaluation was performed as follows:

a load cell was used to make 20 consecutive cuts on the moving felt for 10 blades in each sample batch to measure the load on the blades in the cutting operation. It has been found that the load range for the last 20 th cut TiBC coated blade is at least equal to that with the comparative TiB₂Loading of the hard coated blade. This indicates that the TiBC coated blade maintained its cutting ability (i.e., shape and integrity) during the cutting operation. In addition, damage to the blade edge after 20 cuts during the above test was evaluated by means of an optical microscope. Damage to the blade edge is quantified in terms of the area of missing material (i.e., material that has been broken and removed from the edge). The results are reported in table 4 below.

Table 4:

with TiB having comparative example₂The coated blades of examples 3 and 4 exhibited up to a 50% reduction in missing material area compared to the coated blades. Also, the missing length of the blade edge is significantly improved. The above shows that coating the razor edge with a TiBC coating can improve wear resistance and deterioration resistance during use.

Although the embodiments of the present disclosure have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications and changes are possible. It is also to be understood that such modifications and alterations are incorporated within the scope of this disclosure and the appended claims.