WO2006079361A1

WO2006079361A1 - Razor blade, razor head, shaver and method for manufacturing a razor blade

Info

Publication number: WO2006079361A1
Application number: PCT/EP2005/001526
Authority: WO
Inventors: Vassilis Papachristos; Michalis Karoussis; Dimitris Pissimissis; Cédric Ducros; Frédéric Sanchette
Original assignee: BIC Violex SA
Current assignee: BIC Violex SA
Priority date: 2005-01-27
Filing date: 2005-01-27
Publication date: 2006-08-03
Anticipated expiration: 2007-07-27

Abstract

A razor blade comprising a razor blade edge (1), said razor blade edge comprising: a substrate (2), and a coating (6), deposited on said substrate, said coating comprising a plurality of superimposed sets of layers (7,8), said sets each comprising at least a first layer and a second layer, said first layer being mainly metallic. Said second layer is mainly metallic. Said first layer is different from said second layer.

Description

Razor blade, razor head, shaver and method for manufacturing a razor blade

FIELD OF THE INVENTION The invention relates to razor blades , razor heads , shavers and methods for manufacturing razor blades . BACKGROUND OF THE INVENTION

In particular, the invention is related to a razor blade comprising a razor blade edge, said razor blade edge comprising: a substrate, and a coating, deposited on said substrate, said coating comprising a plurality of superimposed sets of layers , each of said sets comprising at least a first layer and a second layer, said first layer being mainly metallic . Such razor blades have been studied for some time, and provide interesting strength properties , due to the particular structure of their coatings , which comprise alternating layers .

SUMMARY OF THE INVENTION

It is an obj ect of the present invention to provide a new razor blade comprising a razor blade edge with improved combined hardness, wear resistance, strength, durability and shaving performance .

To this end, the invention provides a razor blade as previously defined, wherein said second layer is mainly metallic, and wherein said first layer is different from said second layer .

These particular razor blades provide improved combined hardness , wear resistance, strength, durability and shaving performance . In particular embodiments of the razor blade according to the invention, one might also use one or more of the following features : said first layer mainly comprises a first metal ; - said first layer further comprises a first component, said first component being different from said first metal ; said first component comprises a third metal, different from said first metal ; - said first component comprises carbon ; said first layer is made of a solid solution of carbon in said first metal; said first layer is made of a carbide of said first metal ; - said first layer is made of a mixture of a solid solution of carbon in said first metal and of a carbide of said first metal ; said first component comprises nitrogen ; - said first layer is made of a solid solution of nitrogen in said first metal; said first layer is made of a nitride of said first metal ; said first layer is made of a mixture of a solid solution of nitrogen in said first metal and of a nitride of said first metal ; said first layer comprises at least 50% of said first metal ; said first metal is taken in the following first list for the first metal : chromium, molybdenum, niobium, tungsten, titanium, vanadium, zirconium, platinum, aluminium and copper ; said second layer mainly comprises a second metal ; said second layer further comprises a second component, said second component being different from said second metal ; said second component comprises a fourth metal, different from said second metal ; said second component comprises carbon ; - said second layer is made of a solid solution of carbon in said second metal ; said second layer is made of a carbide of said second metal ; said second layer is made of a mixture of a solid solution of carbon in said second metal and of a carbide of said second metal ; said second component comprises nitrogen ; said second layer is made of a solid solution of nitrogen in said second metal ; - said second layer is made of a nitride of said second metal ;

- said second layer is made of a mixture of a solid solution of nitrogen in said second metal and of . a nitride of said second metal ; - said second layer comprises at least 50% of said second metal ; said second metal is taken in the following second list for the second metal : chromium, molybdenum, niobium, tungsten, titanium, vanadium, zirconium, platinum, aluminium and copper ; said first metal is different from said second metal ; each set is made of only two layers ; the razor blade further comprises an interlayer between said substrate and said coating ; the razor blade further comprises a polymer coating over said coating ; the razor blade further comprises a top layer over said coating . - the razor blade further comprises a polymer coating over said top layer . said razor blade edge comprises two sides converging towards a cutting tip .

According to another aspect, the invention is related to a razor head comprising such a razor blade .

According to another aspect, the invention is related to a shaver comprising such a razor blade .

According to another aspect, the invention is related to a shaver comprising such a razor head. According to another aspect, the invention is related to a method for manufacturing a razor blade comprising a razor blade edge, said razor blade edge comprising: a substrate, and - a coating, said coating comprising a plurality of superimposed sets of layers , each of said sets comprising at least a first layer and a second layer, said first layer being mainly metallic, said second layer being mainly metallic, said first layer being different from said second layer, said method comprising a step (a) wherein said coating is deposited on said substrate .

In particular embodiments of this method, one might also use one or more of the following features : during step (a) , said substrate is moved alternately in front of a first source comprising a first metal and a second source comprising a second metal, and wherein said first and second sources are operated to form a first layer comprising at least said first metal and a second layer comprising at least said second metal, respectively, of said coating ; - said first source comprises a first compound of said first metal and wherein, during step (a) , said first source is operated to form a first layer comprising said first compound in said coating ; said second source comprises a second compound of said second metal and wherein, during step (a) , said second source is operated to form a second layer comprising said second compound in said coating ; during step (a) , said first source is operated in an atmosphere comprising at least one material reactable with said first metal to form a first layer comprising a first compound of said first metal and said material . during step (a) , said second source is operated in an atmosphere comprising at least one material reactable with said second metal to form a second layer comprising a second compound of said second metal and said material . during step (a) , said first source is operated in an atmosphere comprising at least one material reactable with said first compound to form a first layer comprising a compound of said first compound of said first metal and said material . during step (a) , said second source is operated in an atmosphere comprising at least one material reactable with said second compound to form a second layer comprising a compound of said second compound of said second metal and said material . said first and second sources are sputter targets, and said first and second sources are operated by bombardment of argon ions to release said first metal and said second metal, respectively ; - the method further includes a step (b) of depositing an interlayer between said substrate and said coating ; the method further includes a step (c) of depositing a polymer layer over said coating ; - the method further includes a step (d) of depositing a top layer over said coating ; the method further includes a step (e) of depositing a polymer layer over said top layer .

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the invention will be apparent from the following description, drawings and claims .

On the drawings : - Fig . 1 is a view of a first embodiment of a razor blade edge,

Fig . 2 is a view of a second embodiment of a razor blade edge,

Fig . 3 is a view of a third embodiment of a razor blade edge,

Fig . 4 is a view of an apparatus suitable for obtaining a blade edge according to any of Fig . 1 to 3 , and

Fig . 5 is a schematic view of a shaver . On the drawings, corresponding or similar elements have the same reference numbers . MORE DETAILED DESCRIPTION

Fig. 1 is a sectional view of the edge 1 of a razor blade for a shaver . The razor blade edge is formed from a razor blade edge substrate 2 , of for example stainless steel, ceramic, or other suitable material . The razor blade edge substrate 2 might have previously been submitted to shaping operations, such as grinding operations, in order to provide the shape of a tip, of included angle about 10° to 50° , which is located at the junction of two adj acent sides 4 and 5 , which are for example straight as schematically shown on Fig . 1, or exhibit a gothic arch configuration . The sides 4 , 5 and tip 3 of the razor blade edge substrate 2 are covered by a coating β which is made of a plurality of superimposed sets of at least two different alternating layers 7 , 8. Each layer can be between 0.5 and 10 nm thick and more preferably between 2 nm and 5 nm. The coating 6 can be as thin as about 20 to 200 nm thick and yet provide strength, hardness, durability and shaving performance similar or better than those of previous coatings . The coating 6 could be further covered by a PTFE overcoat layer 9 , or another similar coating having lubricating properties .

According to the invention, both of first and second layers 7 , 8 of each set will mainly be metallic, said first and second layers being different . The materials contained respectively in said first and second layers could be different, or these materials could be identical, but the composition of said first and second layers could be different . By "different" composition, it is understood that the content of at least one of the materials of said first layer is different by at least 10%, and more preferably at least 50% from the content of the same material in the second layer . Otherwise, the layers could be different by the physical state of compounds in respectively said first and second layers . For example, said first layer could be a mixture of chromium and chromium nitride, and said second layer could be a solid solution of chromium in nitrogen. Thus , first and second layers could be different even with the same material components in the same proportions, when the physical states of the two layers are different .

By "mainly", it is understood that at least 50% of each layer, and preferably at least 60%, and more preferably at least 75% of the layer is metallic . The percentages are given in atomic percents .

According to a first example, each set comprises a first layer 7 of a first metal, said first metal being taken in the list Chromium (Cr) , Tungsten (W) , Titanium (Ti ) , Vanadium (V) , Aluminium (Al) , Zirconium ( Zr) , Niobium (Nb) , Molybdenum (Mo) , Copper (Cu) or Platinium (Pt) . Each set also comprises a second layer 8 of a second metal taken in the preceding list . According to a first type of coating, the first metal taken for forming the first layer 7 and the second metal taken in the second layer 8 are different .

According to a second example, the first layer 7 is still a metal, while the second layer 8 is a metal compound, the metals still being taken in the above list, the second metal of the second layer 8 being the same or different from the first metal of the first layer 7.

The metal compound forming the second layer could be a mixture of the second metal with a fourth metal, taken in the above list . It could also be a mixture of the second metal with carbon, such as a carbide of the second metal, a solid solution of carbon in the second metal, or a mixture of at least two of the second metal, the fourth metal, a carbide of the second metal and a solid solution of carbon in the second metal . It could also be a mixture of the second metal with nitrogen, such as a nitride of the second metal, a solid solution of nitrogen in the second metal, or a mixture of at least two of the second metal, the fourth metal , a nitride of the second metal and a solid solution of nitrogen in the second metal .

In case of metal carbides , nitrides , solid solutions of carbon or nitrogen in metal, these compounds could be formed as compounds of the second metal alone, or as compounds of a mixture of second and fourth metals .

It will be apparent that the preceding description of possible embodiments for the second layer could be taken as well as possible embodiments for the fist layer, with a first metal (and possibly a third metal) in place of the second metal (and the possibly fourth metal) , as long as the first and second layers are different, as herein described. In each set, the first layer 7 and the second layer 8 could be of the same thickness, or of different thicknesses . Also, first and second layers of two adj acent sets could have the same or different thicknesses .

When crystalline first and second layers 7 , 8 are formed, a coherent super lattice structure may be obtained by the repetition of the sets of layers . Such super lattice coatings form hard coatings , with their hardness depending of the thickness period, the properties of the individual layers , and of course the parameters of the used deposition method . Such super lattice coatings can also exhibit reduced internal stresses of the whole coating when compared to single layers of the same constituents .

A second embodiment is shown schematically on Fig .

2. As compared with the razor blade described with respect to Fig . 1 , an interlayer 10 is deposited between the razor blade edge substrate and the coating 6. The interlayer 10 is for example 10 to 50 nm thick and is made for example of a material or a mixture of the materials taken in the above list . This interlayer could be totally metallic, or a compound of a metal of the above list . If it includes more than one component, the content of at least one of the components could increase, as the distance from the surface of the razor blade edge substrate increases, for example so as to form a smooth transition between the interlayer 10 and the first layer 7 of the adj acent set of the coating 6. A third embodiment is shown schematically on Fig .

3. As compared with the coatings β described with respect to Fig . 1, a top layer 11 is deposited between the coating 6 and the PTFE overcoat layer 9. The top layer 11 is for example 5 to 30 nm thick and is made for example of a metal or a mixture of the metals taken in the above list, or a metallic compound . If it includes more than one component, it could include a decreasing content of at least one component, as the distance from the surface of the razor blade edge substrate increases, for example so as to form a smooth transition between the ultimate layer of the coating β and the adj acent PTFE overcoat layer 9.

Of course, the embodiments of Fig . 2 and Fig. 3 could be combined in order to obtain a razor blade comprising a razor blade edge substrate coated with an interlayer 10 , coating 6, a top layer 11 and PTFE overcoat layer 9.

All coatings could be deposited by a PVD method, such as, for example, magnetron sputtering . Alternately, other suitable techniques could be used. For example, Fig. 4 shows an apparatus that could be used for the deposition . An enclosure 12 comprises two sources, for example first and second sputter targets 13, 14 , facing each other . The first target 13 comprises a first metal to be deposited. The second sputter target 14 comprises a second metal .

The first target 13 could be made of said first metal, or of a compound of said first metal, such as for example a solid solution of carbon in said first metal .

The second target 14 could be made of said second metal, or of a compound of said second metal, such as for example a nitride of said second metal . The second metal could be the same as the first metal .

Each of the first and second sputter targets 13, 14 can be supported by a respective first and second magnetic device 23 , 24 for example of the type comprising two side magnets 23b, 23c, and a central magnet 23a of opposite polarity, as shown in detail for first magnetic device 23. For example, the second magnetic device 24 can be of opposite polarity, the central magnet 24a being of the same polarity as side magnets 23b and 23c, and the side magnets 24b and 24c being of the opposite polarity of the central magnet 24a . The above description is purely exemplary, and more than two targets could be used. Each sputter target 13, 14 can be operated by applying a DC current and voltage to the sputter target . A gas source (not shown) delivers argon gas to form an atmosphere in the enclosure . Argon ions Ar+ impinging on the targets will release the metals of the target into the enclosure . If the enclosure contains N2 or a carbon-containing gas the released material might at least partially react with the N₂ or carbon-containing gas in order to form a nitrogen compound or a carbon compound, respectively.

The razor blade substrates are stacked in bayonets of a rotating carousel 17 which can be moved so that the edge of the razor blade substrates are subsequently displaced in the vicinity of the four matter sources . The released material and/or compounds deposit on the razor blade edge substrates .

A voltage bias of up to 1000 V can be applied on the razor blades in a DC mode or pulsed DC mode .

For applying an interlayer or a top layer, the sputter targets comprising the metal (s ) to be part of the interlayer or top layer are operated . By changing the N- containing or C-containing gas flow rate into the enclosure, the concentration of nitrogen or carbon, respectively, in the interlayer or top layer can be varied .

In general, the values of the applied current or power intensities on the targets , the relative speed of the blades with respect to the targets , the bias voltage applied and the N-containing or C-containing gas partial flow will define the properties of the coating.

Of course, only an exemplary deposition method is given here . Another in-line PVD apparatus could be used, wherein the razor blade substrates are stacked in a razor blade holder that is moved back and forth along a linear track passing in front of two or more sputter targets of the above-mentioned type .

Prior to the deposition of the coating, a sputter etching step could be applied in order to clean the tip of the blade substrates . Another sputter-etching step could again be applied after the deposition of the coating 6 or top layer 11, when appropriate, and before the application of PTFE .

Other deposition methods are believed to be of possible use in order to obtain razor blades as exemplified on Fig . 1 to 3 , and including for example RF sputtering, ion plating, ion beam assisted deposition, or other deposition methods .

After the coatings 6, and possibly 10 and 11 have been applied, a PTFE overcoat layer 9 can be applied, for example by spraying PTFE on the coated blade, or by other suitable method .

As shown on Fig . 5, the obtained blades could be mounted in a razor head containing one, two, three or more blades . The razor head could be held fixedly or removably on a razor handle 16 in order to form a shaver 18.

One exemplary detailed embodiment is described below with reference to Fig . 4 :

After loading the blade bayonets containing the blade substrates into the enclosure 12 it is evacuated down to a base pressure . A sputter-etching step is performed :

Ar gas is inserted into the chamber up to a suitable pressure and both Cr 13 and Ti 14 targets are operated under DC current control . A DC voltage is applied on the moving stainless steel blades for 4 minutes .

After the end of sputter etching step the enclosure pressure is adj usted for deposition . Cr and Ti targets operate simultaneously, with the current being 3 Amps on both . A DC voltage of 450 V is applied on the rotating blades . Adj usting the deposition time a Cr/Ti nanolayered film 60 nm thick is deposited on the blade substrate . The ratio of the layer thickness dCr/dTi in this nanolayered structure is 1 , 5 for the selected conditions and the bilayer period is 4 nm. On top of the Cr/Ti film a fluoropolymer final layer (PTFE) of 500 nm is deposited, mainly to provide a lower friction of the blade surface .

Results of standard in-house tests used for investigation of blade cutting performance and strength, showed an improvement for blades coated with the new Cr/Ti film as compared with standard production blades . In a series of trials, a specific test involving the repeating cutting action of the blade on a moving felt using a load cell for measuring the load on the blade for each cut, resulted in load ranges for the first 10 cuts that were 5% lower than the load range of blades with standard production coatings . This result shows that the blades with the Cr/Ti coating preserve their cutting ability ( i . e . shape and integrity) in a more effective manner during cutting action . The damages imposed on the blade edge after 10 cuts during the above described test was also evaluated with the aid of an optical microscope . The damage on the blade edge was quantified in terms of area of missing materials (i . e . material that has been broken and removed from the edge ) . Cr/Ti coated blades resulted in an 80% decrease of the missing material area as compared with blades with standard production coatings . This result shows the increased durability of the blades with the new Cr/Ti coating .

Shaving test in a panel experienced in shaving performance evaluation has shown that the shavers comprising the new blades have performed better than current production shavers in comfort, closeness , irritation, number of nicks/cuts and overall opinion .

Claims

1. A razor blade comprising a razor blade edge, said razor blade edge comprising : a substrate, and a coating, deposited on said substrate, said coating comprising a plurality of superimposed sets of layers, each of said sets comprising at least a first layer and a second layer, said first layer being mainly metallic, wherein said second layer is mainly metallic, and said first layer is different from said second layer .

2. Razor blade according to claim 1, wherein said first layer mainly comprises a first metal .

3. Razor blade according to claim 2 wherein said first layer further comprises a first component, said first component being different from said first metal .

4. Razor blade according to claim 3 , wherein said first component comprises a third metal, different from said first metal .

5. Razor blade according to claim 3, wherein said first component comprises carbon .

6. Razor blade according to claim 5, wherein said first layer is made of a solid solution of carbon in said first metal .

7. Razor blade according to claim 5, wherein said first layer is made of a carbide of said first metal .

8. Razor blade according to claim 5, wherein said first layer is made of a mixture of a solid solution of carbon in said first metal and of a carbide of said first metal .

9. Razor blade according to claim 3 , wherein said first component comprises nitrogen .

10. Razor blade according to claim 9, wherein said first layer is made of a solid solution of nitrogen in said first metal .

11. Razor blade according to claim 9, wherein said first layer is made of a nitride of said first metal .

12. Razor blade according to claim 9, wherein said first layer is made of a mixture of a solid solution of nitrogen in said first metal and of a nitride of said first metal .

13. Razor blade according to any of claims 3 to 12 , wherein said first layer comprises at least 50% of said first metal .

14. Razor blade according to any of claims 1 to 13 , wherein said first metal is taken in the following first list for the first metal : chromium, molybdenum, niobium, tungsten, titanium, vanadium, zirconium, platinum, aluminium and copper .

15. Razor blade according to any of the proceeding claims , wherein said second layer mainly comprises a second metal .

16. Razor blade according to claim 15, wherein said second layer further comprises a second component, said second component being different from said second metal .

17. Razor blade according to claim 16, wherein said second component comprises a fourth metal, different from said second metal .

18. Razor blade according to claim 16, wherein said second component comprises carbon .

19. Razor blade according to claim 18, wherein said second layer is made of a solid solution of carbon in said second metal .

20. Razor blade according to claim 18 , wherein said second layer is made of a carbide of said second metal .

21. Razor blade according to claim 18 , wherein said second layer is made of a mixture of a solid solution of carbon in said second metal and of a carbide of said second metal .

22. Razor blade according to claim 16, wherein said second component comprises nitrogen .

23. Razor blade according to claim 22 , wherein said second layer is made of a solid solution of nitrogen in said second metal .

24. Razor blade according to claim 22 , wherein said second layer is made of a nitride of said second metal .

25. Razor blade according to claim 22 , wherein said second layer is made of a mixture of a solid solution of nitrogen in said second metal and of a nitride of said second metal .

26. Razor blade according to any of claims 16 to 25, wherein said second layer comprises at least 50% of said second metal .

27. Razor blade according to any of claims 15 to 26, wherein said second metal is taken in the following second list for the second metal : chromium, molybdenum, niobium, tungsten, titanium, vanadium, zirconium, platinum, aluminium and copper .

28. Razor blade according to any of claims 15 to 27 , wherein said first metal is different from said second metal .

29. Razor blade according to any of the preceding claims, wherein each set is made of only two layers .

30. Razor blade according to any of the preceding claims further comprising an interlayer between said substrate and said coating .

31. Razor blade according to any of the preceding claims further comprising a polymer coating over said coating .

32. Razor blade according to any of claims 1 to 30 further comprising a top layer over said coating.

33. Razor blade according to claim 32 further comprising a polymer coating over said top layer.

34. Razor blade according to any of the preceding claims, wherein said razor blade edge comprises two sides converging towards a cutting tip .

35. Razor head comprising a razor blade according to any of the preceding claims .

36. Shaver comprising a razor blade according to any of claims 1 to 34.

37. Shaver comprising a razor head according to claim 35.

38. Method for manufacturing a razor blade comprising a razor blade edge, said razor blade edge comprising : - a substrate, and a coating, said coating comprising a plurality of superimposed sets of layers, said sets each comprising at least a first layer and a second layer, said first layer being mainly metallic, said second layer being mainly metallic, said first layer being different from said second layer, said method comprising a step (a) wherein said coating is deposited on said substrate .

39. Method according to claim 38 wherein, during step (a) , said substrate is moved alternately in front of a first source comprising a first metal and a second source comprising a second metal, and wherein said first and second sources are operated to form a first layer comprising at least said first metal and a second layer comprising at least said second metal, respectively, of said coating.

40. Method according to claim 39, wherein said first source comprises a first compound of said first metal and wherein, during step (a) , said first source is operated to form a first layer comprising said first compound in said coating .

41. Method according to claim 39 or 40, wherein said second source comprises a second compound of said second metal and wherein, during step (a) , said second source is operated to form a second layer comprising said second compound in said coating .

42.Method according to claim 39, wherein during step (a) , said first source is operated in an atmosphere comprising at least one material reactable with said first metal to form a first layer comprising a first compound of said first metal and said material .

43. Method according to claims 39 or 40, wherein during step (a) , said second source is operated in an atmosphere comprising at least one material reactable with said second metal to form a second layer comprising a second compound of said second metal and said material .

44. Method according to claims 40 or 41 , wherein during step (a) , said first source is operated in an atmosphere comprising at least one material reactable with said first compound to form a first layer comprising a compound of said first compound of said first metal and said material .

45.Method according to claim 41, wherein during step (a) , said second source is operated in an atmosphere comprising at least one material reactable with said second compound to form a second layer comprising a compound of said second compound of said second metal and said material .

46.Method according to any of claims 39 to 45, wherein said first and second sources are sputter targets, and wherein said first and second sources are operated by bombardment of argon ions to release said first metal and said second metal, respectively .

47. Method according to any of claims 38 to 46, further including a step (b) or depositing an interlayer between said substrate and said coating .

48. Method according to any of claims 38 to 47 further including a step (c) or depositing a polymer layer over said coating .

49.Method according to any of claims 38 to 47 further including a step (d) of depositing a top layer over said coating.

50.Method according to claim 49 further including a step (e) of depositing a polymer layer over said top layer .