AU667816B2 - Improvements in or relating to razor blades - Google Patents

Abstract

A razor blade includes a substrate (50) with a wedge-shaped edge at a distance of forty micrometers from the sharpened tip (52), and a layer of diamond or diamond-like material (60) defined by facets (66, 68) that have an included angle of less than seventeen degrees that has a thickness of at least twelve hundred angstroms from the sharpened tip (52) of said substrate (50) to a distance of forty micrometer from the sharpened tip (52), and an ultimate tip defined by facets (62, 64) that have lengths of at least about 0.1 micrometer and define an included angle of at least sixty degrees, and that defines a tip radius of less than about 400 angstroms, an aspect ratio in the range of 1:1-3:1, a hardness of at least thirteen gigapascals and an L5 wet wool felt cutter force of less than 0.8 kilogram.

Description

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Cii r.~l-*-~ci--rrT~L7J OPI DATE 25/01/93 AOJP DATE 25/03/93 APPLN. D 21927/92 PCT NUMBER PCT/US92/04932 1111111 1111111111111111111111 1111 ll AU9221927 (51) International Patent Classification 5 (11) International Publication Number: WO 93/00204 B26B 21/54, C23C 14/32 Al (43) International Publication Date: 7 January 1993 (07.01.93) (21) International Application Number: PCT/US92/04932 (74) Agents: GALLOWAY, Peter, D. et al.; Ladas Parry, 26 West 61 Street, New York, NY 10023 (US).

(22) International Filing Date: II June 1992 (11.06.92) (81) Designated States: AT, AU, BB, BG, BR, CA, CH, CS, Priority data: DE, DK, ES, FI, GB, HU, JP, KP, KR, LK, LU, MG, 719,793 24 June 1991 (24.06.91) US MN, MW, NL, NO, PL, RO, RU, SD, SE, European pa- 792,427 15 November 1991 (15.11.91) US tent (AT, BE, CH, DE, DK, ES, FR, GB, GR, IT, LU, MC, NL, SE), OAPI patent (BF, BJ, CF, CG, CI, CM, GA, GN, ML, MR, SN, TD, TG).

(71) Applicant: THE GILLETTE COMPANY [US/US]; Prudential Tower Building, Boston, MA 02199 (US).

Published (72) Inventors: PARENT, Robert 69 Hawthorne Street, With international search report.

Westwood, MA 02090 MADEIRA, John Amanda Road, Assonet, MA 02702 HAHN, Steve, Syng-Hi 7 Trinity Court, Wellesley Hills, MA 02181 CHOU, Chong-Ping, Peter 8 Carol Lane, Lexington, MA 02173 BROOKS, Lamar, Eugene 57 Temple Road, Wellesley, MA 02181 (US).

P16 (54)Title: IMPROVEMENTS IN OR RELATING TO RAZOR BLADES (57) Abstract A razor blade includes a substrate (50) with a wedge-shaped edge I 64 at a distance of forty micrometers from the sharpened tip and a layer of diamond or diamond-like material (60) defined by facets (66, 68) a that have an included angle of less than seventeen degrees that has a thickness of at least twelve hundred angstroms from the sharpened tip 52 (52) of said substrate (50) to a distance of forty micrometer from the b sharpened tip and an ultimate tip defined by facets (62, 64) that 68 have lengths of at least about 0.1 micrometer and define an included 66 angle of at least sixty degrees, and that defines a tip radius of less than about 400 angstroms, an aspect ratio in the range of 1:1-3:1, a hardness of at least thirteen gigapascals and an L5 wet wool felt cutter force of less than 0.8 kilogram, S56 72 50 58

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WO 93/00204 PCT/US92/04932 1 IMPROVEMENTS IN OR RELATING TO RAZOR BLADES This invention relates to improved razors and razor blades and to processes for producing razor blades or similar cutting tools with sharp and durable cutting edges. A razor blade typically is formed of a suitable substrate material such as metal or ceramic and an edge is formed with wedge-shape configuration with an ultimate edge or tip that has a radius of less than about 1,000 angstroms. During use, a razor blade is held in the razor at an angle of approximately 25", and with the wedge-shaped edge in contact with the skin, it is moved over the face so that when the edge encounters a beard hair, it enters and severs it by progressive penetration, aided by a wedging action. It is believed that the cut portion of the hair (which on average is about 100 micrometers in diameter) remains pressed in contact with the blade facets remote from the facial skin surface for a penetration up to only about half the hair diameter. Beyond this, the hair can bend and contract away from the blade to relieve the (i wedging forces. The resistance to penetration through reaction between hair and blade facets therefore occurs only over about the first sixty micrometers of the blade tip back from the edge and the geometry of the blade tip in this region is regarded as being the most important from the cutting point of view.

It is believed that a reduction in the 1*

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rr ll i 2 included angle of the facets would correspondingly reduce the resistance to continued penetration of the blade tip into the hair. However, when the included angle is reduced too much, the strength of the blade tip is inadequate to withstand the resultant bending forces on the edge during the cutting process and the tip deforms plastically (or fractures in a brittle fashion, dependent on the mechanical properties of the material from which it is made) and so sustains permanent damage, which impairs its subsequent cutting performance, i.e. the edge becomes "blunt" or "dull". As shaving action is severe and blade edge damage frequently results, and to enhance shavability, the use of one or more layers of supplemental coating material has been proposed for shave facilitation, and/or to increase the hardness, strength and/or corrosion resistance of the shaving edge. A number of such coating materials have been proposed, such as polymeric materials, metals and alloys, as well as other materials including diamond and diamond-like carbon (DLC) material. Diamond and diamond-like carbon (DLC) materials may be characterized as having substantial sp 3 carbon bonding; a mass density greater than grams/cm 3 and a Raman peak at about 1331 cm- 1 (diamond) or about 1550 cm- 1

(DLC).

Each such layer or layers of supplemental material desirably provides characteristics such as improved shavability, improved hardness, edge strength and/or corrosion resistance i 'I I while not adversely affecting the geometry and cutting effectiveness of the shaving edge.

According to a preferred embodiment of the invention, there is provided a process S 20 for forming a razor blade including mechanically abrading a substrate to form a wedge- 1 shaped sharpened edge thereon, said wedge-shaped sharpened edge including a tip having an included angle of less than 300 and a tip radius of less than 1200 A (angstroms), and forming a layer of diamond or diamond-like carbon material on said sharpened edge of i said substrate, wherein said forming step includes positioning said substrate and a solid S 25 target member in a chamber, and sputtering said solid target member to generate carbon atoms for forming said layer of diamond or diamond-like carbon material on said sharpened edge of said substrate from said carbon atoms while applying an RF bias to said substrate, said layer of diamond or diamond-like carbon material forming an ultimate tip having a radius of less than about 400 A (angstroms) and an aspect ratio of 1:1 3:1.

According to another embodiment of the invention, there is provided a razor blade including a substrate having a wedge-shaped sharpened edge formed thereon, the wedgeshaped sharpened edge including a tip having an included angle of less than 300 and a tip radius of less than 1200 A (angstroms), and a layer of diamond or diamond-like carbon material formed on the sharpened edge of the substrate, wherein the layer of diamond or diamond-like carbon material includes an ultimate tip having a radius of less than about 400 A (angstroms) and an aspect ratio ranging from about 1:1 3:1.

[N:\LIBZ]00471 :.IEAR ,i II 3 The tip of the wedge-shaped sharpened edge may have an included angle of less than 17° and a tip radius the estimated radius of the larger circle that may be positioned within the ultimate tip of the edge when such ultimate tip is viewed under a scanning electron microscope at magnifications of at least 25,000) of less than 400 A (angstroms).

The layer of diamond or diamond-like carbon material may be formed to a thickness of about 1200 A (angstroms) or less from the tip of said sharpened edge to a distance located about 40 u.m 100 I.m from the tip and may include an ultimate tip defined by two facets each having a length of at least about 0.1 micrometer and defining an included angle of at least 600. The diamond or diamond-like carbon (DLC) material may have a hardness of at least thirteen gigapascals, a substantially sp3 carbon bonding characteristic, a mass density greater than 1.5 grams/cm 3 and a Raman peak at about 1331 cm- 1 (diamond) or about 1550 cm- 1 (DLC); and the blade edge has excellent edge strength as evidenced by an L5 wet wool felt cutter force of less than 0.8 kilogram, and a negligible dry wool felt cutter edge damage (less than fifty small damage regions (each such small damage region being of less than twenty micrometer dimension and less than ten micrometer depth) and no damage regions of large dimension or depth) as microscopically assessed.

S 0 The process may include the step of depositing a layer of material on the wedgeshaped sharpened edge to a thickness of about 300 A (angstroms) or less prior to depositing the layer of diamond or diamond-like carbon material.

The process may include the step of depositing an adherent polymer coating on the layer of diamond or diamond-like carbon material.

According to another embodiment of the invention, there is provided a shaving unit including a support structure defining spaced-apart, skin-engaging surfaces, and at least one razor blade structure mounted to said support structure and being disposed between said skin-engaging surfaces, said razor blade structure including a substrate having a wedge-shaped sharpened edge thereon, said wedge-shaped sharpened edge defining a tip, said sharpened edge having a layer of diamond or diamond-like carbon material formed on said sharpened edge, said layer of diamond or diamond-like carbon material forming an ultimate tip having a radius of less than about 400 A (angstroms) and an aspect ratio ranging from about 1:1 3:1 and, having a thickness of about 1200 A (angstroms) or less from said tip to a distance located about 40 p.m 100 pm from said tip.

According to a still further embodiment of the invention, there is provided a shaving unit including a support structure defining spaced-apart, skin-engaging surfaces, and at least one razor blade structure mounted to said support structure and being disposed between said skin-engaging surfaces, said razor blade structure including a substrate having a wedge-shaped sharpened edge thereon, said wedge-shaped sharpened edge defining a tip having an included angle of less ihan 30°, said sharpened edge having a B layer of diamond or diamond-like carbon material formed on said sharpened edge, said A 'T j T nT'o i 5: i layer of diamond or diamond-like carbon material forming an ultimate tip having a radius of less than about 400 A (angstroms) and an aspect ratio ranging from about 1:1 3:1 and, having a thickness of about 1200 A (angstroms) or less from said tip to a distance located about 40 ±m 100 pim from said tip.

The shaving unit may be of the disposable cartridge type adapted for coupling to and uncoupling from a razor handle or may be integral with a handle so that the complete razor is discarded as a unit when the blade or blades become dull. The front and rear skin-engaging surfaces cooperate with the blade edge (or edges) to define the shaving geometry. Particularly preferred shaving units are of the types shown in US Patenw 3,876,563 and in US Patent 4,586,255.

Other features and advantages of the invention will be seen as the following description of particular embodiments progresses, in conjunction with the drawings, in which: i .I RA4 '3 OU ~Ulllp--~ E--4lpr* rarr~ L1=~ ~pl) p~ WO 93/00204 PCT/US92/04932 Fig. 1 is a perspective view of a shaving unit in accordance with the invention; Fig. 2 is a perspective view of another shaving unit in accordance with the invention; Fig. 3 is a diagrammatic view illustrating one example of razor blade edge geometry in accordance with the invention; Fig. 4 is a diagrammatic view of apparatus for the practice of the invention; and Figs. 5 and 6 are Raman spectra of DLC material deposited with the apparatus of Fig. 4.

Description of Particular Embodiments With reference to Fig. 1, shaving unit includes structure for attachment to a razor handle, and a platform member 12 molded of high-impact polystyrene that includes structure defining forward, transversely-extending skin engaging surface 14.

Mounted on platform member 12 are leading blade 16 having sharpened edge 18 and following blade having sharpened edge 22. Cap member 24 of molded high-impact polystyrene has structure defining skinengaging surface 26 that is disposed rearwardly of blade edge 22, and affixed to cap member 24 is shaving aid composite 28.

The shaving unit 30 shown in Fig. 2 is of the type shown in Jacobson U.S. Patent 4,586,255 and includes molded body 32 with front portion 34 and rear portion 36. Resiliently secured in body 32 are guard member 38, leading blade unit 40 and trailing blade unit 42. Each blade unit 40, 42 includes a blade member 44 that has a sharpened edge 46. A shaving aid composite 48 is frictionally secured in a recess in rear portion 36.

A diagrammatic view of the edge region of the blades 16, 20 and 44 is shown in Fig. 3. The blade includes stainless steel body portion 50 with a wedge-shaped sharpened edge formed in a sequence of -i WO 93/00204 PCT/US92/04932 edge forming honing operations that forms a tip portion 52 that has a radius typically less than 500 angstroms with facets 54 and 56 that diverge at an angle of about 13*. Deposited on tip 52 and facets 54, 56 is interlayer 58 of molybdenum that has a thickness of about 300 angstroms. Deposited on molybdenum interlayer 58 is outer layer 60 of diamond-like carbon (DLC) that has a thickness of about 2,000 angstroms, with facets 62, 64 that have lengths of about one-quarter micrometer each and define an included angle of about 80', facets 62, 64 merging with main facet surfaces 66, 68 that are disposed at an included angle of about 13" and an aspect ratio (the ratio of the distance from DLC tip 70 to stainless steel tip 52 and the width of the DLC coating 60 at tip 52) of about 1.7.

Deposited on layer 60 is an adherent telomer layer 72 that has a substantial as deposited thickness but is reduced to monolayer thickness during initial shaving.

Apparatus for processing blades of the type shown in Fig. 3 is diagrammatically illustrated in Fig. 4. That apparatus includes a DC planar magnetron sputtering system manufactured by Vac Tec Systems of Boulder, Colorado that has stainless steel chamber 74 with wall structure 80, door 82 and base structure 84 in which is formed port 86 coupled to a suitable vacuum system (not shown). Mounted in chamber 74 is carousel support 88 with upstanding support member 90 on which is disposed a stack of razor blades 92 with their sharpened edges 94 in alignment and facing outwardly from support 90. Also disposed in chamber 74 are support structure 76 for target member 96 of molybdenum (99.99% pure) and support structure 78 for target member 98 of graphite (99.999% pure). Targets 96 and 98 are vertically disposed plates, each about twelve centimeters wide WO 93/00204 PCT/US92/04932 7 and about thirty-seven centimeters long. Support structures 76, 78 and 88 are electrically isolated from chamber 74 and electrical connections are provided to connect blade stack 92 to RF power supply 100 through switch 102 and to DC power supply 104 through switch 106; and targets 96 and 98 are connected through switches 108, 110, respectively, to DC magnetron power supply 112. Shutter structures 114 and 116 are disposed adjacent targets 96, 98, respectively, for movement between an open position and a position obscuring its adjacent target.

Carousel 88 supports the blade stack 92 with the blade edges 94 spaced about seven centimeters from the opposed target plate 96, 98 and is rotatable about a vertical axis between a first position in which blade stack 92 is in opposed alignment with molybdenum target 96 (Fig. 4) and a second position in which blade stacy: 92 is in opposed alignment with graphite target 98.

In a particular processing sequence, a stack of blades 92 (thirty centimeters high) is secured on support 90 (together with three polished stainless steel blade bodies disposed parallel to the target); chamber 74 is evacuated; the targets 96, 98 are cleaned by DC sputtering for five minutes; switch 102 is then closed and the blades 92 are RF cleaned in an argon environment for three minutes at a pressure of ten millitorr, an argon flow of 200 sccm and a power of 1.5 kilowatts; the argon flow is then reduced to 150 sccm at a pressure of 4.5 millitorr in chamber 74; switch 106 is closed to apply a DC bias of -50 volts on blades 92; switch 108 is closed to sputter target 96 at one kilowatt power; and shutter 114 in front of molybdenum target 96 is opened; for twenty-eight seconds to deposit a molybdenum layer 58 of about 300 angstroms thickness on the blade edges 94. Shutter 114 is then closed, switches 106 and 108 A A C'^ WO 93/00204 PCT/US92/04932 are opened, and carousel 88 is rotated 90' to juxtapose blade stack 92 with graphite target 98.

Pressure in chamber 74 is reduced to two millitorr with an argon flow of 150 sccm; switch 110 is closed to sputter graphite target 98 at 500 watts; switch 102 is closed to apply a 13.56 MHz RF bias of one thousand watts (-440 volts DC self bias voltage) on blades 92, and concurrently shutter 116 is opened for twenty minutes to deposit a DLC layer 60 of about two thousand angstroms thickness on molybdenum layer 58.

The DLC coating 60 had a radius at tip 70 of about 250 Angstroms that is defined by facets 62, 64 that have an included angle of about 80', an aspect ratio of about 1.7:1, and a hardness (as measured on the planar surface of an adjacent stainless steel blade body with a Nanoindenter X instrument to a depth of five hundred angstroms) of about seventeen gigapascals (the stainless steel blade body having a hardness of about eight gigapascals). As illustrated in Fig. 5, Raman spectroscopy of the coating material deposited in this process shows a broad Raman peak 120 at about 1400-1500 cm 1 wave number, a spectrum typical of DLC structure.

A coating 72 of polytetrafluoroethylene telomer is then applied to the DLC-coated edges of the blades. The process involves heating the blades in a neutral atmosphere of argon and providing on the cutting edges of the blades an adherent and frictionreducing polymer coating of solid PTFE. Coatings 58 and 60 were firmly adherent to the blade body 50 and S*provided low wet wool felt cutter force (the lowest of the first five cuts with wet wool felt (L5) being about 0.45 kilogram), and withstood repeated applications of wet wool felt cutter forces (the lowest cutter force of the 496-500 cuts being about 0.65 kilogram), indicating that the DLC coating 60 is substantially unaffected by exposure to the severe WO 93/00204 PCT/US92/04932 conditions of this felt cutter test and remains firmly adhered to the blade body 50. Edge damage and delamination after ten cuts with dry wool felt as determined by microscopic assessment was substantially less than commercial chrome-platinum coated blades, there being less than four small edge damage regions (each such small damage region being of less than twenty micrometer dimension and less than ten micrometer depth) and no damage regions of larger dimension or depth. Resulting blade elements 44 were assembled in cartridge units 30 of the type shown in Fig. 2 and shaved with excellent shaving results.

In another particular processing sequence, a stack of blades 92 (thirty centimeters high) is secured on support 90 (together with three polished stainless steel blade bodies disposed parallel to the target); chamber 74 is evacuated; the targets 96, 98 are cleaned by DC sputtering for five minutes; switch 102 is then closed and the blades 92 are RF cleaned in an argon environment for two and a quarter minutes at a pressure of ten millitorr, an argon flow of 200 sccm and a power of 1.5 kilowatts; the argon flow is then reduced to 150 sccm at a pressure of six millitorr in chamber 74; switch 106 is closed to apply a DC bias of -50 volts on blades 92; shutter 114 in front of molybdenum target 96 is opened; and switch 108 is closed to sputter target 96 at one kilowatt power for thirty-two seconds to deposit a molybdenum layer 58 of about 300 angstroms thickness on the blade edges 94. Shutter 114 is then closed, switches 106 and 108 are opened, and carousel 88 is rotated 900 to juxtapose blade stack 92 with graphite target 98. Pressure in chamber 74 is reduced to two millitorr with an argon flow of 150 sccm; switch 110 is closed to sputter graphite target 98 at 500 watts; switch 102 is closed to apply a 13.56 MHz RF bias of c Alt i WO 93/00204 PCT/US92/04932 320 watts (-220 volts DC self bias voltage) on blades 92, and concurrently shutter 116 is opened for seven minutes to deposit a DLC layer 60 of about 900 angstroms thickness on molybdenum layer 58. The DLC coating 60 had a tip radius of about 300 Angstroms, an aspect ratio of 1.6:1, and a hardness (as measured on the planar surface of an adjacent stainless steel blade body as measured with a Nanoindenter X instrument) of about thirteen gigapascals.

A coating 72 of polytetrafluoroethylene telomer is then applied to the DLC-coated edges of the blades in accordance with the teaching of U.S.

Patent No. 3,518,110. The process involved heating the blades in a neutral atmosphere of argon and providing on the cutting edges of the blades an adherent and friction-reducing polymer coating of solid PTFE. Coatings 58 and 60 were firmly adherent to the blade body 50, provided low wet wool felt cutter force (the lowest of the first five cuts with wet wool felt (L5) being about 0.6 kilogram), and withstood repeated applications of wet wool felt cutter forces (the lowest cutter force of the 496-500 cuts being about 0.76 kilogram), indicating that the DLC coating 60 is substantially unaffected by exposure to the severe conditions of this felt cutter test and remains firmly adhered to the blade body Edge damage and delamination after ten cuts with dry wool felt as determined by microscopic assessment was substantially less than commercial chrome-platinum coated blades, there being less than four small edge damage regions (each such small damage region being of less than twenty micrometer dimension and less than ten micrometer depth) and no damage regions of larger dimension or depth. Resulting blade elements 44 were assembled in cartridge units 30 of the type shown in Fig. 2 and shaved with excellent shaving results. A4 ii WO 93/00204 PCT/US92/04932 In another processing sequence, chamber 74 is evacuated; the targets 96, 98 are cleaned by DC sputtering for five minutes; switch 102 is then closed and the blades 92 are RF cleaned in an argon environment for two and a quarter minutes at a pressure of ten millitorr, an argon flow of 200 sccm and a power of 1.5 kilowatts; the argon flow is then reduced to 150 sccm at a pressure of six millitorr in chamber 74; switch 106 is closed to apply a DC bias of -50 volts on blades 92; shutter 114 in front of molybdenum target 96 is opened; and switch 108 is closed to sputter target 96 at one kilowatt power for thirty-two seconds to deposit a molybdenum layer 58 of about 300 angstroms thickness on the blade edges 94. Shutter 114 is then closed, switches 106 and 108 are opened, and carousel 88 is rotated 90' to juxtapose blade stack 92 with graphite target 98.

Pressure in chamber 74 is reduced to two millitorr with an argon flow of 150 seem; switch 110 is closed to sputter graphite target 98 at 500 watts; switch 102 is closed to apply a 13.56 MHz RF bias of 320 watts (-220 volts DC self bias voltage) on blades 92, and concurrently shutter 116 is opened for five minutes to deposit a DLC layer 60 of about 600 angstroms thickness on molybdenum layer 58. The DLC coating 60 had a tip radius of about 400 Angstroms, an aspect ratio of 1.7:1, and a hardness (as measured on the planar surface of an adjacent stainless steel blade body as measured with a Nanoindenter X instrument) of about thirteen gigapascals. As illustrated in Fig. 6, Raman spectroscopy of the coating material 60 deposited in this process shows a broad Raman peak 122 at about 1543 cm 1 wave number, a spectrum typical of DLC structure.

A telomer coating 72 was applied to the blade edges with a nitrogen atmosphere. The resulting coatings 58 and 60 were firmly adherent t'i f^A z WO 93/00204 PCT/US92/04932 the blade body 50, provided low wet wool felt cutter force (the lowest of the first five cuts with wet wool felt (L5) being about 0.6 kilogram), and withstood repeated applications of wet wool felt cutter forces (the lowest cutter force of the 496-500 cuts being about 0.76 kilogram), indicatin that the DLC coating 60 is substantially unaffected by exposure to the severe conditions of this felt cutter test and remains firmly adhered to the blade body Edge damage and delamination after ten cuts with dry wool felt as determined by microscopic assessment was substantially less thun commercial chrome-platinum coated blades, there being less than five small edge damage regions (each such small damage region being of less than twenty micrometer dimension and less than ten micrometer depth) and no damage regions of larger dimension or depth. Resulting blade elements 44 were assembled in cartridge units 30 of the type shown in Fig. 2 and shaved with excellent shaving results.

While particular embodiments of the invention has been shown and described, various modifications will be apparent to those skilled in the art, and therefore, it is not intended that the invention be limited to the disclosed embodiments, or to details thereof, and departures may be made therefrom within the spirit and scope of the invention.

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Claims (17)

1. A process for forming a razor blade including mechanically abrading a substrate to form a wedge-shaped sharpened edge thereon, said wedge-shaped sharpened edge including a tip having an included angle of less than 30° and a tip radius of less than 1200 A (angstroms), and forming a layer of diamond or diamond-like carbon material on said sharpened edge of said substrate, wherein said forming step includes positioning said substrate and a solid target member in a chamber, and sputtering said solid target member to generate carbon atoms for forming said layet of diamond or diamond-li. carbon material on said sharpened edge of said substrate from said carbon atoms while applying an RF bias to said substrate, said layer of diamond or diamond-like carbon material forming an ultimate tip having a radius of less than about 400 A (angstroms) and an aspect ratio of 1:1 3:1.

2. A process for forming a razor blade according to claim 1, wherein said tip of said wedge-shaped sharpened edge has as included angle of less than 17° and a tip radius of less than 403 A (angstroms).

3. A process for forming a razor blade according to any one of claims 1 and 2, wherein said layer of diamond or diamond-like carbon material is formed to a thickness of about 1200 A (angstroms) or less from said tip of said sharpened edge to a distance located about 40 itm 100 jim from said tip. 20 4. A process for forming a razor blade according to any one of claims 1 3, wherein a shutter is located in alignment between said solid target member and said substrate in an inert gas environment, said sputtering step including applying electrical energy to said solid target member and opening said shutter for a predetermined period of time while applying said RF bias to said substrate to forrm said layer of diamond or 25 diamond-like material.

5. A process for forming a razor blade according to any one of claims 1 4, wherein said solid target member is a high purity graphite target.

6. A process for forming a razor blade according to any one of claims 1 wherein said ultimate tip is defined by two facets each having a length of at least about 0.1 micromieter and defining an included angle of at least

7. A process for forming a razor blade according to any one of claims 1 6, further including the step of depositing a layer of material on said wedge-shaped sharpened edge to a thickness of about 300 A (angstroms) or less prior to depositing said layer of diamond or diamond-li'ce carbon material.

8. A process for forming a razor blade according to any one of claims 1 7, further including the step of depositing an adherent polymer coating on said layer of diamond or diamond-like carbon material.

9. A razor blade including a substrate having a wedge-shaped sharpened edge formed thereon, said wedge-shaped sharpened edge inchlding a tip having an included ~1~21~ R angle of less than 300 and a tip radius of less than 1200 A (angstroms), and a layer of ce I[N:\LIBZ]00471:EAR L i j 14 diamond or diamond-like carbon material formed on said sharpened edge of said substrate, wherein said layer of diamond or diamond-like carbon material includes an ultimate tip having a radius of less than about 400 A (angstroms) and an aspect ratio ranging from about 1:1 3:1.

10. A razor blade according to claim 9, wherein said tip of said wedge-shaped sharpened edge has an included angle equal to or less than 17° at a distance located about um 100 |im from said tip.

11. A razor blade according to any one of claims 9 and 10, wherein said layer of diamond or diamond-like carbon material has a thickness of about 1200 A (angstroms) or less from the tip of said sharpened edge of said substrate to a distance located about im 100 u.m from said substrate tip.

12. A razor blade according to any one of claims 9 11, wherein said ultimate tip is defined by facets having a length of at least about 0.1 micrometer and an included angle of at least

13. A razor blade according to any one of claims 9 12, further including a layer of material having a thickness of about 300 A (angstroms) or less deposited between said wedge-shaped sharpened edge and said layer of diamond or diamond-like carbon material.

14. A razor blade according to any one of claims 9 13, wherein said diamond or diamond-like carbon (DLC) material has a hardness of at least thirteen gigapascal, a substantially sp3 carbon bonding characteristic, a mass density greater than grams/cm 3 and a Raman peak at about 1331 cm- 1 (diamond) or about 1550 cm- 1 (DLC). A razor blade according to any one of claims 9 14, further including a layer of adherent polymer on said layer of diamond or diamond-like carbon material.

16. A shaving unit including a support structure defining spaced-apart, skin- engaging surfaces, and at least one razor blade ,structure mounted to said support structure and being disposed between said skin-engaging surfaces, said razor blade structure including a substrate having a wedge-shaped sharpened edge thereon, said wedge-shaped sharpened edge defining a tip having an included angle of less than 30°, said sharpened edge having a layer of diamond or diamond-like carbon material formed on said sharpened edge, said layer of diamond or diamond-like carbon material forming an ultimate tip having a radius of less than about 400 A (angstroms) and an aspect ratio ranging from about 1:1 3:1 and, having a thickness of about 1200 A (angstroms) or less from said tip to a distance located about 40 tim 100 utm from said tip.

17. A shaving unit according to claim 16, further including two razor blade structures each blade structure including a substrate having a wedge-shaped sharpened edge thereon, each said wedge-shaped sharpened edge being disposed parallel to one another between said skin-engaging surfaces.

18. A process for forming a razor blade substantially as hereinbefore described with reference to the accompanying drawings. 42 O/W W ,IlRnnrA7ln'im L

19. A razor blade substantially as hereinbefore described with reference to the accompanying drawings. A shaving unit substantially as hereinbefore described with reference to the accompanying drawings. Dated 1 December, 1995 The Gillette Company Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON I 1 I 1~1 I I I I c I I I I II 1 I I I I [N:\LIBZ]00471:EAR L.