Systems and methods for coating blades

Abstract

A method of applying a lubricious coating of a material, such as a fluoropolymer, to a cutting edge of a blade includes providing a blade having a cutting edge including a leading end, a first facet, and a second facet adjacent the first facet and the leading end. The method further includes generating a plasma stream and directing the plasma stream toward the cutting edge. The method further includes introducing a fluid stream containing a dispersion including a fluoropolymer into the plasma stream to simultaneously plasma treat the cutting edge and deposit solids of the dispersion onto the cutting edge.

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE This disclosure relates generally to blades and, more particularly, to a method for applying a lubricious coating to the cutting edge of a razor blade. [Background technology]

[0002] Some blades, particularly razor blades, are typically made of a suitable substrate material such as stainless steel, with the cutting edge formed in a wedge-shaped configuration with a tip end and adjacent facets. Hard coatings such as diamond, amorphous diamond, diamond-like carbon (DLC) material, metals, nitrides, carbides, oxides, or ceramics are frequently used to improve strength, corrosion resistance, and shaving ability, and also to allow for a thinner tip while maintaining the required strength, which can reduce the cutting force used during shaving.

[0003] It is well known in the art, for example from U.S. Pat. Nos. 3,743,551 and 3,838,512, that the shaving properties of a razor blade can be improved by applying a lubricious polymeric outer surface coating (e.g., a fluoropolymer such as polytetrafluoroethylene-"PTFE"). Typically, this type of polymeric coating is applied to create a relatively thin layer (e.g., 500 nm or less in thickness) that extends at least over the tip of the blade and preferably over the small flat surface. This layer can be applied using a variety of different techniques, such as spray application, bath dipping, etc. Spray application of a PTFE coating material can require relatively large amounts of expensive PTFE material, since not all of the PTFE material is bonded to the razor blade. Furthermore, it has been disclosed that the application process does not apply a completely uniform layer thickness over the entire desired surface, so that the thickness of the initially applied layer is typically selected to ensure sufficient layer thickness, with the assumption that thickness variations are expected.

[0004] This "relatively" thin layer ensures a sufficient layer thickness, but is not optimal for shaving, i.e., too thick. During the first few strokes of use of a newly coated blade, the shaving process by the user results in the removal of part of the polymer coating (if any initial thickness was left) from the tip. This process of displacing the surface coating is sometimes called "push back" or "peel back" of the coating. After the excess polymer coating is "pushed back" by the user's application of the blade during shaving, a much thinner layer of polymer coating (which can be as thick as one polymer molecule) typically remains on the cutting edge for the entire life of the blade. However, until the initial thickness of the polymer coating is "pushed back," the user may experience some discomfort, known as the first shave effect.

[0005] Attempts to provide thinner coatings to prevent user pushback and avoid this initial discomfort have been disclosed. US Patent No. 5,985,459, US Patent No. 7,247,249 and US Patent No. 10,766,157 disclose methods of treating the cutting edge of a razor blade with a solvent-applied polyfluorocarbon (fluoropolymer) coating that first partially removes a portion of the thick coating, potentially avoiding the discomfort associated with excessively thick coatings. The use of solvents can significantly increase the manufacturing cost of the blade and potentially add additional manufacturing steps. US Patent Application Publication No. 2020 / 0353054 and International Patent Application Publication No. WO2020 / 043476 disclose methods of first physically contacting the thickly applied coating to mechanically remove a portion of it. Again, this is an additional undesirable manufacturing step, and physical contact with the cutting edge can increase the probability of damage to the cutting edge during the manufacturing (coating removal) process. Further additional partial physical removal manufacturing steps are disclosed in US Patent No. 9,943,879 as well as US Patent No. 9,969,094. Co-pending International Patent Application WO2020 / 081763 discloses a method of first applying a thinner fluoropolymer coating to the cutting edge in an attempt to beneficially avoid post-application thinning operations. However, the resulting coating thickness does not approach the truly desired thickness, i.e., the thickness of a single polymer molecule. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] U.S. Patent No. 3,743,551 [Patent Document 2] U.S. Patent No. 3,838,512 [Patent Document 3] U.S. Patent No. 5,985,459 [Patent Document 4] U.S. Patent No. 7,247,249 [Patent Document 5] U.S. Patent No. 10,766,157 [Patent Document 6] U.S. Patent Application Publication No. 2020 / 0353054 [Patent Document 7] International Patent Application Publication No. 2020 / 043476 [Patent Document 8] U.S. Patent No. 9,943,879 [Patent Document 9] U.S. Patent No. 9,969,094 [Patent Document 10] International Patent Application No. 2020 / 081763 Summary of the Invention

[0007] The present disclosure is directed to substantially alleviating the limitations of prior art systems and methods for coating blades. The present disclosure relates to a method for applying a coating of lubricious material, such as a fluoropolymer, to a cutting edge of a blade, and a coating system for providing the same. A blade is provided having a cutting edge including a tip end, a first facet adjacent the tip end, and a second facet. A plasma stream is generated and directed toward the cutting edge. A fluid stream containing a dispersion including a fluoropolymer is introduced into the plasma stream to plasma treat the cutting edge and simultaneously deposit solids of the dispersion on the cutting edge.

[0008] In some aspects, the method further comprises sintering the blade to cause the deposited solids to form a coating of fluoropolymer on the cutting edge.

[0009] In some aspects, the cutting edge defines a central plane, and the systems and methods further include positioning the plasma nozzle at approximately the central plane and generating a plasma stream with the plasma nozzle such that the plasma stream is directed along the central plane. In other aspects, the cutting edge defines a central plane, and the systems and methods further include positioning the plasma nozzle such that the plasma nozzle is angularly offset from the central plane and generating a plasma stream with the plasma nozzle such that the plasma stream is directed toward the first facet. In a further aspect of the preceding aspects, a second plasma nozzle is positioned such that the second plasma nozzle is angularly offset from the central plane and on an opposite side of the central plane from the plasma nozzle, and generating a second plasma stream with the second plasma nozzle such that the second plasma stream of the second plasma nozzle is directed toward the second facet.

[0010] In some aspects, the fluoropolymer is polytetrafluoroethylene.

[0011] In some embodiments, the dispersion is an aqueous dispersion and the polytetrafluoroethylene solids comprise between 1% and 2% of the dispersion.

[0012] In some aspects, the plasma is an atmospheric plasma.

[0013] In some aspects, the blade is a razor blade.

[0014] The above features and advantages further set forth will be more fully understood by reference to the following detailed description when taken in conjunction with the accompanying drawings. [Brief description of the drawings]

[0015] [Figure 1] FIG. 2 is a top front view of a razor assembly including a razor cartridge and a handle.

[0016] [Diagram 2] FIG. 2 is a plan top view of the razor cartridge of FIG. 1.

[0017] [Diagram 3] 2 is a plan top view of an exemplary razor blade for the razor cartridge of FIG. 1.

[0018] [Figure 4] FIG. 5 is a plan side view of the exemplary razor blade of FIG.

[0019] [Diagram 5] FIG. 2 is a schematic diagram of a razor blade cutting edge including a coating.

[0020] [Figure 6] 1 is a schematic plan side view of an exemplary blade coating system;

[0021] [Figure 7] FIG. 2 is a schematic plan side view of another exemplary blade coating system.

[0022] [Figure 8] 1 is a flow chart of a method of applying a fluoropolymer coating to a blade cutting edge.

[0023] [Figure 9] FIG. 2 is a plan top view of a fixture that holds multiple razor blades.

[0024] [Figure 10] FIG. 10 is a side cross-sectional view of the fixture of FIG.

[0025] [Figure 11] FIG. 2 is a plan top view of a coiled razor blade ribbon. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Aspects of the present disclosure include systems and methods for applying a lubricious coating of a material, such as a fluoropolymer, to the cutting edge of a blade. Non-limiting examples of blades can include razor blades (e.g., razor blades for shaving), which can be used individually or as part of a larger system, such as a razor cartridge. With reference to Figures 1 and 2, an exemplary razor cartridge 20 for use in a shaving process is shown to facilitate the description provided herein, although the present disclosure is not limited to this particular razor cartridge embodiment. The razor cartridge 20 is rigidly or pivotally mounted to a handle 22. In some embodiments, the razor cartridge 20 can be a disposable portion of a razor assembly 24 that is separable from the reusable handle 22. In some other embodiments, the razor cartridge 20 and the handle 22 can be combined into a unitary disposable razor assembly 24.

[0027] The razor cartridge 20 includes a body 26 having a front portion 28, a rear portion 30, a first side portion 32, and a second side portion 34. Each of the first side portion 32 and the second side portion 34 extends between the front portion 28 and the rear portion 30. The razor cartridge 20 further includes at least one razor blade 36 mounted within the body 26. The razor blade 36 is disposed rearward of the front portion 28 and forward of the rear portion 30. The razor blade 36 is disposed laterally between the first side portion 32 and the second side portion 34. As used herein, the terms "front" and "rear" are defined in terms of the orientation of the razor blade 36 against the skin of a user when the razor cartridge 20 is used in a conventional manner, e.g., the razor blade 36 would move in a front-to-rear direction relative to a point on the user's skin.

[0028] 3-5, razor blades 36 according to the present disclosure can assume a variety of configurations, each including a body 38 having a width 40 extending between a leading end 42 and a trailing end 44 and a length 46 extending between a first lateral end 48 and a second lateral end 50. The body 38 further includes an upper body surface 52 and a lower body surface 54, which extend widthwise between the leading end 42 and the trailing end 44 and lengthwise between the first lateral end 48 and the second lateral end 50. As shown in FIG. 5, the razor blade 36 includes a leading end 42, a longitudinally extending cutting edge 56 including a first facet 58 and a second facet 60, where the first facet 58 and the second facet 60 are adjacent the leading end 42. The first and second facets 58, 60 converge at the tip end 42 and extend rearwardly to the respective upper and lower body surfaces 52, 54. The razor blade 36 includes a central plane 64 that extends widthwise through the body 38 of the razor blade 36. The cutting edge 56 may be oriented along the central plane 64, for example, as shown in Figures 4 and 5. However, the disclosure is not limited to this particular orientation of the cutting edge 56, and in various embodiments, the cutting edge 56 may be positioned outside (e.g., to one side of) the central plane 64 of the razor blade 36. As will be described in more detail, the razor blade 36 may include one or more apertures 62 configured to function to allow multiple razor blades 36 to be mounted together during manufacturing, for example, in a cartridge. Additionally or alternatively, the one or more apertures may define wash-through ports to facilitate removal of shaving debris. The description of razor blade 36 provided herein is included to facilitate understanding of the present disclosure, but the present disclosure is not limited to this particular razor blade embodiment.

[0029] The razor blade 36 may generally be made from a stainless steel material. In various embodiments, the razor blade 36 may include a coating including one or more materials, such as diamond, amorphous diamond, diamond-like carbon (DLC) material, metals, nitrides, carbides, oxides, ceramics, etc., to improve one or more of the strength, corrosion resistance, and shaving ability of the razor blade 36. The present disclosure is not limited to any particular material or combination of materials for the razor blade 36.

[0030] The razor blade 36 includes a lubricious outer coating 66 disposed on the cutting edge 56 of the razor blade 36. For example, the coating 66 may be disposed on all or a portion of the distal end 42, the first facet 58, and the second facet 60 of the cutting edge 56, as well as on portions of the upper body surface 52 and the lower body surface 54. The coating 66 has a thickness T. In various embodiments, the thickness T of the coating 66 may be substantially constant along the cutting edge 56, while in other embodiments, the thickness T of the coating 66 may vary at different locations along the cutting edge 56.

[0031] Coatings 66 according to the present disclosure can include, but are not limited to, fluoropolymer materials. A particularly useful fluoropolymer material for coating 66 materials is polytetrafluoroethylene ("PTFE"). Other non-limiting examples of coating 66 materials include silicones such as organosiloxane gels, polyethers, and others. The present disclosure is not limited to using any particular type of coating 66 material that provides a material that can be processed in the manner described below. For ease of description of the systems and methods of the present disclosure, the coating 66 material will be described as PTFE. However, as indicated above, the present disclosure is not limited to the use of PTFE-type coating 66 materials.

[0032] 5-7, the present disclosure includes a blade coating system 68 configured to apply a coating 66 to the cutting edge 56 of a razor blade 36. The blade coating system 68 includes at least one plasma generator 70. The plasma generator 70 includes a plasma nozzle 72 configured to direct a plasma stream 74 outwardly therefrom along a plasma stream axis 76. In the schematic diagram, the plasma generator 70 is depicted as being integrated with the plasma nozzle 72. However, in some implementations of the present disclosure, these may be separate, i.e., the plasma generator 70 may be connected to the plasma nozzle 72 by a suitable conduit that allows the plasma to travel to the plasma nozzle 72. The plasma generator 70 may be configured to generate an atmospheric pressure plasma. As used herein, the term "atmospheric pressure plasma" refers to a plasma that is generated from ambient air and has a pressure approximately equal to that of the surrounding atmosphere, and may be contrasted with "low pressure" or "high pressure" plasmas, which may require the use of a pressure vessel (e.g., a "reaction vessel") to maintain a plasma pressure above that of the surrounding atmosphere. For example, the plasma stream 74 may exit the plasma nozzle 72 at a pressure of about 4-6 bar. Atmospheric pressure plasma may be generated by a variety of plasma nozzle configurations, such as, for example, an arc discharge or a corona discharge configuration, and the present disclosure is not limited to any particular plasma nozzle configuration.

[0033] The blade coating system 68 includes at least one spray nozzle 78 configured to discharge a fluid stream 80 outwardly therefrom along a fluid stream axis 82. The spray nozzle 78 is positioned relative to the plasma nozzle 72 such that the fluid stream axis 82 intersects with the plasma stream axis 76 at an angle A1, e.g., an acute angle, preferably in the range of 30-50 degrees, at a location axially downstream from the plasma nozzle 72. The fluid stream 80 should not be wider than the plasma stream 74. The spray nozzle 78 is positioned along the fluid stream axis 82 a distance D1 from the plasma stream axis 76. In various embodiments, the spray nozzle 78 can be mounted to the plasma generator 70, for example, as shown in FIG. 7. However, the present disclosure is not limited to any particular means for positioning the spray nozzle 78 relative to the plasma generator 70.

[0034] In various embodiments, the blade coating system 68 can include a plurality of plasma nozzles 70, such as a first plasma generator 70A and a second plasma generator 70B. The blade coating system 68 can also include a plurality of spray nozzles 78, such as a first spray nozzle 78A and a second spray nozzle 78B, respectively. Each spray nozzle 78, 78A, 78B can be mounted or otherwise positioned relative to a respective plasma generator 70, 70A, 70B, as described above and shown in FIG.

[0035] With reference to Figures 3-11, the present disclosure includes a method 800 for applying a fluoropolymer coating to a blade cutting edge, as shown in the flow chart illustrated in Figure 8. For ease of explanation, the method 800 is described below with reference to the blade coating system 68 of Figures 6 and 7 and the razor blade 36 of Figures 3-5. However, the method 800 can alternatively be performed on other blades and using other blade coating systems.

[0036] In step 802, the razor blades 36 are provided in preparation for applying the coating 66 to the cutting edge 56 of each razor blade 36. In various embodiments, the razor blades 36 to be coated may each be an individual razor blade. In various other embodiments, the razor blades 36 to be coated may not yet be in individual form. As shown in FIGS. 9 and 10, in various embodiments, step 802 may include mounting a plurality of razor blades 36 as a stack 84 in a fixture 86. Mounting the razor blades 36 in the fixture 86 may stack the razor blades 36 in the same orientation with the cutting edges 56 of the razor blades 36 exposed. The fixture 86 may include one or more blade retaining members 88 extending through apertures (e.g., aperture 62) of the razor blades 36 to hold the razor blades 36 in the fixture 86 but allow the razor blades 36 to move relative to one another along the stack axis 90. 11, in various embodiments, a plurality of razor blades 36 can be arranged as an integral razor blade ribbon 92, where the ribbon 92 is coiled. The ribbon 92 can then be cut or otherwise processed to form a plurality of razor blades 36. The present disclosure is not limited to any particular arrangement of the razor blades 36 for future application of the coating 66. The razor blades 36 are coated at ambient conditions, i.e., the blades 36 are not necessarily coated within any (low, medium, high) vacuum chamber or other pressure vessel.

[0037] In step 804, the blade coating system 68 is positioned relative to the razor blade 36. For example, the blade coating system 68 can be positioned relative to an individual razor blade or relative to a plurality of razor blades 36 configured, for example, as a coiled ribbon 92. The blade coating system 68 can be positioned such that the plasma nozzle 72 is positioned a distance D2 from the distal end 42 of the cutting edge 56 of the razor blade 36. The fluid stream axis 82 intersects with the plasma stream axis 76 at an intersection point 65. The spray nozzle 78 is then positioned relative to the plasma nozzle 72 such that the intersection point 65 is a distance D3 from the plasma nozzle 72. As shown in FIG. 6, in various embodiments, the blade coating system 68 can be positioned such that the plasma nozzle 72 is positioned approximately along the central plane 64 of the razor blade 36 such that the plasma stream 74 can be directed along the central plane 64 toward the cutting edge 56. For example, the plasma stream axis 76 of the plasma nozzle 72 can be aligned and substantially parallel to the central plane 64 of the razor blade 36.

[0038] As shown in FIG. 7, in various embodiments, the blade coating system 68 can be positioned such that the plasma nozzle 72 is positioned angularly offset from the central plane 64 of the razor blade 36. For example, the plasma stream axis 76 of the plasma nozzle 72 can form an angle A2 with respect to the central plane 64 of the razor blade 36. The plasma nozzle 72 can be positioned to direct the plasma stream 74 toward one of the first facet 58 or the second facet 60. For example, the plasma nozzle 72 can be positioned such that the plasma stream axis 76 is substantially perpendicular to a surface of one of the first facet 58 or the second facet 60. In an embodiment of the blade coating system 68 having a first plasma nozzle 72A and a second plasma nozzle 72B, the first plasma generator 72A can be directed toward the first facet 58, while the second plasma generator 72B can be directed toward the second facet 60 and positioned on the opposite side of the central plane 64 from the first plasma generator 72A, as shown in FIG. 7. As used herein, the term "substantially" with respect to angular relationships refers to the stated angular relationship plus or minus 10 degrees.

[0039] In step 806, the plasma nozzle 72 generates a plasma stream 74 that is directed toward the cutting edge 56 of the razor blade 36 such that the plasma stream 74 contacts the cutting edge 56. A working gas, such as compressed air or other common industrial gases, such as hydrogen, nitrogen, and / or oxygen, is supplied to the plasma generator 70. By application of a high voltage discharge, the plasma generator 70 creates a highly reactive atmospheric plasma from the working gas and discharges the plasma from the plasma nozzle 72 as a plasma stream 74.

[0040] In various embodiments, the cutting edge 56 of each razor blade 36 may be pretreated to improve bonding between the coating 66 material and the cutting edge 56. An example of how the cutting edge 56 may be pretreated includes applying a plasma stream 74 to the cutting edge 56 in preparation for depositing the coating 66 material on the cutting edge 56. The chemical and physical interaction of the plasma stream 74 with the material of the razor blade 36 at the cutting edge 56 may increase the surface energy of the material of the razor blade 36 at the cutting edge 56. In addition, the plasma stream 74 may remove all or a portion of oxide layers, dust deposits, grease, oil, and / or other contaminants from the cutting edge 56 that may otherwise impede bonding between the coating 66 material and the cutting edge 56. The present disclosure is not limited to plasma pretreatment of the cutting edge 56, and other pretreatment methods, such as chemical pretreatment, may be used.

[0041] In step 808, the fluid stream 80 is introduced into the plasma stream 74 to deposit the coating material 66 on the cutting edge 56 of the razor blade 36. The fluid stream 80 is introduced into the plasma stream 74 by the spray nozzle 78 along a fluid stream axis 82 that intersects the plasma stream axis 76 between the plasma nozzle 72 and the cutting edge 56. The distance D1 between the spray nozzle 78 and the plasma stream axis 76 can be selected such that all or substantially all of the fluid stream 80 is introduced into and carried by the plasma stream 74.

[0042] In various embodiments, the fluid stream 80 includes a dispersion containing a fluoropolymer material that deposits on the cutting edge 56 of the razor blade 36 forming the coating 66. In various embodiments, the dispersion can be an aqueous dispersion including solids of a fluoropolymer material, such as PTFE. In various embodiments, the PTFE solids can be less than 5% of the dispersion, and more preferably between about 1% and 2% of the dispersion. One non-limiting example of a suitable fluoropolymer dispersion is DYNEON PTFE Dispersion TF 5070GZ from 3M, which is a dispersion of PTFE in water, having a solids content of 50%. Another non-limiting example of a suitable fluoropolymer dispersion is DRYFILM LW-2120 from CHEMOURS, which is a dispersion of PTFE in water, having a solids content of 20%. Fluoropolymer dispersions such as the exemplary fluoropolymer dispersions described above can be further diluted (e.g., with water) to obtain a desired solids content of PTFE. In various embodiments, the dispersion can further include a surfactant or "wetting agent." One non-limiting example of a suitable wetting agent is TIONOX 465 from PIGMENTSOLUTION GmbH. In a further embodiment where the coating is a non-fluorinated material such as a siloxane as described above, the siloxane may be in the form of a solution rather than a dispersion.

[0043] Once introduced into the plasma stream 74 by the fluid stream 80, the PTFE dispersion is carried by the plasma stream 74 towards the cutting edge 56. By directing the plasma stream 74 towards the cutting edge 56 and introducing the fluid stream 80 into the plasma stream 74, the blade coating system 68 can simultaneously plasma treat the cutting edge 56 while depositing the PTFE solids of the dispersion onto the cutting edge 56 to form the coating 66. In the context of this disclosure, the term "simultaneously" includes steps occurring in rapid succession, such as the plasma process being followed immediately by the deposition of the solids. However, in various embodiments, the application of the plasma stream 74 to the cutting edge 56 in step 806 can be first applied without the introduction of the fluid stream 80 to pre-treat the cutting edge 56. After pre-treatment of the cutting edge 56, the fluid stream 80 can subsequently be introduced into the plasma stream 74 to deposit the PTFE solids onto the cutting edge 56.

[0044] By spraying the PTFE dispersion into the plasma stream 74, the particle size of the PTFE dispersion directed at the cutting edge 56 can be reduced as compared to conventional methods of spraying a PTFE coating material directly onto the cutting edge of the razor blade. Additionally, the plasma stream 74 can heat both the PTFE dispersion and the cutting edge 56, improving the initial bond between the PTFE solids and the cutting edge 56, providing a photosintering effect that allows the PTFE solids to be more easily concentrated closer to the distal end 42 of the cutting edge 56, and aiding in the evaporation of the carrier fluid of the dispersion. Thus, embodiments of the present disclosure can provide improved bonding between the PTFE solids and the cutting edge 56, and thus a very thin PTFE coating 66 layer that is substantially free of voids (e.g., a "monolayer"). A cutting edge having a void-free coating is desirable (e.g., it is understood that a void-free coating provides a better shaving experience). To improve the bond between the PTFE solids and the cutting edge 56, it may also be necessary to significantly reduce the flow rate of the PTFE dispersion from the spray nozzle 78, as compared to the conventional method of directly spraying the PTFE coating material onto the razor blade edge. As a result, the amount of costly PTFE dispersion required to produce an acceptable coating 66 on each razor blade 36 can be significantly reduced.

[0045] At step 810, the blade coating system 68 may be moved relative to the cutting edge 56 of the razor blade 36 such that a pretreatment or deposition of the coating 66 material may be applied along all or substantially all of the cutting edge 56 from the first side end 48 to the second side end 50 of the razor blade 36 (see FIGS. 3-5). In various embodiments, the blade coating system 68 may include an actuation member (not shown) configured to move the plasma generator 70 and spray nozzle 78 in one or more of an x-direction, a y-direction, or a z-direction relative to the cutting edge 56. In various other embodiments, the razor blade 36 may instead be moved such that the cutting edge 56 moves through the plasma stream 74. The present disclosure is not limited to any particular process or means for moving the blade coating system 68 relative to the cutting edge 56 of the razor blade 36.

[0046] In various embodiments, the heat from the plasma stream 74 in step 808 may be sufficient to sinter the PTFE solids and form the coating 66 on the cutting edge 56. Thus, a separate sintering step may not be necessary to form the coating 66. However, in various other embodiments, a separate sintering step may be used to form the coating 66. In step 812, the razor blade 36, including the PTFE solids deposited on the cutting edge 56, may be subjected to a thermal sintering process. Sintering the razor 36 may include heating the razor blade 36 and the PTFE solids to a predetermined temperature for a period of time sufficient for the razor blade 36 and the PTFE solids to fuse and adhere to the cutting edge 56. EXAMPLES

[0047] The exemplary process utilized plasma equipment provided by PLASMATREAT GmbH. The equipment included a model FG5001 plasma generator 70 remotely connected to a model PFW-10 plasma nozzle 72. The plasma stream 74 was generated from ambient air compressed to 1.2 bar. The plasma generator was set at a frequency of 21 kHz, 260V, and a duty cycle of 100%. The fluid stream 80 was delivered from a model OFT-AGR 09 spray nozzle 78 with nozzle 0,3 provided by Reiter GmbH. The atomization parameters were horn air pressure 0.1 bar and atomization air pressure 1.0 bar. The fluid in the fluid stream was DYNEON PTFE further diluted with 2% solids as previously described, and the flow rate was 100 ml / hr. The plasma nozzle 72 was positioned at a distance D2 of 12 mm from the tip 42 of the cutting edge 56, and the plasma nozzle 72 was positioned such that the plasma stream axis 76 of the plasma nozzle 72 was aligned and substantially parallel to the central plane 64 of the razor blade 36 to be treated. The spray nozzle 78 was then positioned relative to the plasma nozzle 72 such that the intersection point 65 was at a distance D3 of 11.4 mm from the plasma nozzle 72, and at a distance D1 of approximately 18 mm, at an angle A1 of 40 degrees. The plasma stream 74, including the fluid stream 80, had a width of 4 mm. The plasma nozzle 72 moved relative to and along the cutting edge 56 of the razor blade 36 at an effective linear velocity of 125 mm / sec. The PTFE-coated razor blade 36 was then sintered to complete the PTFE coating process. The coated razor blade 36 was assembled into a razor cartridge 20. In sequential single shaving tests with an identical cartridge control, except that it had a blade processed according to the process of WO 2020 / 081763, the razor cartridge 20 having a razor 36 processed according to the exemplary process was found to have less pulling and tweaking, better slippage, comfort, no first shave effect, and was significantly more preferable (at 95% LOC).

[0048] The advantages of this method are: By spraying the PTFE dispersion into the plasma stream 74, the particle size of the PTFE in the dispersion is further reduced, i.e., finer, compared to the as-applied dispersion; the plasma stream 74 cleans, pretreats and activates the cutting edge 56; the plasma stream 74 causes partial melting of the PTFE particles, improving the adhesion of the PTFE to the cutting edge 56 and effectively partially pre-sintering the PTFE; since the PTFE dispersion enters the plasma stream 74 close to the cutting edge 56, it does not undergo excessive thermal degradation; the resulting PTFE coating is thinner than known coatings without the need for any post-processing operations, e.g., chemically or mechanically thinning the coating; the first shave effect is eliminated; since the applied coating is thinner than known coatings (as-applied), the unit consumption of PTFE dispersion (e.g., DYNEON or DRYFILM materials described above) is 20 times less than that of prior art processes; the method does not need to be applied in any vacuum chamber or pressure vessel.

[0049] It should be noted that in the foregoing description and drawings, various connections are described between elements. It should be noted that these connections are general and may be direct or indirect unless otherwise specified, and the specification is not intended to be limiting in this respect. A connection between two or more entities may refer to a direct connection or an indirect connection. An indirect connection may incorporate one or more intervening entities. It should be further noted that various method or process steps for embodiments of the present disclosure are described in the following description and drawings. The specification may present the method and / or process steps as a particular sequence. However, to the extent that the method or process does not depend on the particular sequence of steps described herein, the method or process should not be limited to the particular sequence of steps described. As one of ordinary skill in the art would understand, other sequences of steps are possible. Thus, the particular sequence of steps described herein should not be construed as limiting.

[0050] Furthermore, no element, component, or method step of the present disclosure is intended to be open to the general public, regardless of whether that element, component, or method step is expressly recited in the claims. No claim element herein is to be construed under the provisions of 35 U.S.C. 112(f) unless that element is expressly recited using the phrase "means for." As used herein, the terms "comprises," "comprising," or any other modification thereof, are intended to protect a non-exclusive inclusion such that the process, method, article, or apparatus comprising a list of elements may include other elements not expressly recited or inherent in such process, method, article, or apparatus, rather than including only those elements.

[0051] While various aspects of the disclosure have been disclosed, it will be apparent to one of ordinary skill in the art that many more embodiments and implementations are possible within the scope of the disclosure. For example, the disclosure described herein includes several aspects and embodiments that include specific features. Although these specific features may be described individually, it is within the scope of the disclosure that some or all of these features may be combined with any one of the aspects and remain within the scope of the disclosure. References to "various embodiments," "one embodiment," "embodiment," "exemplary embodiment," and the like indicate that the described embodiment may include a particular feature, structure, or characteristic, but not all embodiments necessarily include the particular feature, structure, or characteristic. Moreover, such phrases do not necessarily refer to the same embodiment. Furthermore, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one of ordinary skill in the art to implement such feature, structure, or characteristic in connection with other embodiments, whether or not expressly described. Accordingly, the disclosure is not to be limited, except in light of the appended claims and their equivalents. [Explanation of symbols]

[0052] 20 Razor Cartridges 22 Handle 24 Razor assembly 26 Main unit 28 Front part 30 Rear part 32 First side part 34 Second side part 36 razor blade 38 Main Body 40 Width 42 Tip end 44 Rear end 46 Length 48 first side edge 50 second side edge 52 Upper body surface 54 Lower body surface 56 Cutting Edge 58 First Facet 60 Second Facet 62 Aperture 64 Center plane 66 Coating 68 Blade Coating System 70 Plasma Generator 70A First Plasma Generator 70B Second Plasma Generator 72 Plasma Nozzle 74 Plasma Nozzle Flow 76 Plasma nozzle flow axis 78 Spray Nozzle 78A First Spray Nozzle 78B Second Spray Nozzle 80 Fluid Stream 82 Fluid Stream Axis 84 Stack 86 Fixtures 88 Retaining member 90 Stack Axis 92 Ribbon T Thickness A1 angle D1 Distance from tip of spray nozzle to intersection 65 D2 Distance from the tip of the plasma nozzle to the tip of the razor blade D3 Distance from the tip of the plasma nozzle to the intersection 65

Claims

1. 1. A method of applying a fluoropolymer coating to a cutting edge of a blade, comprising: providing the blade having the cutting edge including a tip end, a first facet, and a second facet, the first facet and the second facet adjacent the tip end; generating a plasma stream from a plasma nozzle and directing the plasma stream out of the plasma nozzle toward the cutting edge; introducing a fluid stream containing a dispersion comprising the fluoropolymer into the plasma stream downstream of the plasma nozzle to simultaneously plasma treat the cutting edge and deposit solid matter of the dispersion on the cutting edge; A method comprising:

2. The method of claim 1 further comprising sintering the blade to cause the deposited solids to form the fluoropolymer coating on the cutting edge.

3. the cutting edge defines a center plane; 10. The method of claim 1, further comprising positioning a plasma nozzle at approximately the central plane and generating the plasma stream with the plasma nozzle such that the plasma stream is directed along the central plane.

4. the cutting edge defines a central plane; 10. The method of claim 1, further comprising positioning a plasma nozzle such that the plasma nozzle is angularly offset from the central plane and generating the plasma stream with the plasma nozzle such that the plasma stream is directed toward the first facet.

5. 5. The method of claim 4, further comprising: positioning a second plasma nozzle such that the second plasma nozzle is angularly offset from the central plane and on an opposite side of the central plane from the plasma nozzle; and generating a second plasma stream using the second plasma nozzle such that the second plasma stream of the second plasma nozzle is directed toward the second facet.

6. The method of claim 1 wherein the fluoropolymer is polytetrafluoroethylene.

7. 7. The method of claim 6, wherein the dispersion is an aqueous dispersion and the polytetrafluoroethylene solids comprise 1% to 2% of the dispersion.

8. The method of claim 1 , wherein the plasma is an atmospheric plasma.

9. The method of claim 1 , wherein the blade is a razor blade.

10. 1. A blade coating system for applying a fluoropolymer coating to a cutting edge of a blade, comprising: at least one plasma nozzle configured to direct a plasma stream outward from the plasma nozzle along a plasma stream axis toward the cutting edge of the blade; at least one spray nozzle attached to the at least one plasma nozzle and configured to discharge a fluid stream containing a dispersion comprising a fluoropolymer along a fluid stream axis into the plasma stream; A blade coating system comprising:

11. The method described in claim 1, wherein the fluid stream width of the fluid stream is smaller than the plasma stream width of the plasma stream.

12. The method of claim 11, wherein the plasma stream width is 4 mm.

13. The method of claim 11, wherein the plasma stream and the fluid stream intersect at an angle A1 of 30 to 50 degrees at the plasma stream axis.

14. The method described in claim 1, wherein the plasma nozzle is at a distance D3 of 12 mm from the cutting edge.

15. The method of claim 1, wherein the step of generating the plasma stream further includes removing all or part of oxide coatings, dust deposits, grease, oil, and / or other contaminants from the cutting edge.

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