JP5830823B2 - Razor blade technology - Google Patents

Description

The present disclosure relates generally to razor blades for razor cartridges, and more specifically to a method of manufacturing a razor blade.
(Cross-reference of related applications)
This application claims the benefit of US Provisional Application No. 61 / 225,586, filed July 15, 2009, the entire contents of which are incorporated herein by reference.

  Many modern safety razors include disposable razor cartridges adapted to be selectively coupled to a reusable handle by an intervening coupling structure. The cartridge includes a housing having at least one razor blade having a cutting edge disposed therein. Other modern safety razors include a razor cartridge permanently coupled to the handle that can be discarded as a single unit.

  In the commonly assigned US Pat. No. 6,037,086, the desirability of providing a razor blade assembly including an inter-blade guard joined to a razor blade is disclosed. By providing an inter-blade guard, adjacent cutting edges are spaced sufficiently within their razor cartridges to properly debris from the space between adjacent blades and any respective support structure. At the same time, the inter-blade guard provides a skin engagement / skin support surface between adjacent cutting edges to control skin ridges, improve shaving comfort, cuts and cuts Reduce. The inter-blade guard is mounted on the razor blade in a position generally visible to the user during normal use and handling of the safety razor.

  A razor cartridge that includes a razor blade having a curved portion can have certain advantages, and there are numerous proposals to provide a razor cartridge with such a razor blade. However, such razor cartridges have not been successfully commercialized, or at least not manufactured on a large scale in the mass market like that of razor cartridges. Many manufacturers mimic curved razor blades by mounting a generally flat razor blade on a curved support made of a material that is thicker and softer than typical cured razor blades. U.S. Patent No. 6,053,089 to Jacobson discloses a typical configuration of a blade mounted on a support. The support portion is mounted on the opposite side of the razor blade with respect to the blade guard of the razor blade of Patent Document 1 described above, and is at least partly visible from the user's view during normal use and handling of the safety razor. Hidden.

  Modern safety razors can usually be used and stored by users in varying degrees of humidity or high humidity. During normal use, the razor blade of a razor cartridge is contacted with mildly corrosive materials such as sweat, soap, and components of shaving aids such as shaving foam or gel. Also, the nature and composition of tap water (commonly used for shaving) can also vary from city to city. Considering these ambient conditions, martensitic stainless steel has come to be widely used as a corrosion resistant material for producing a razor blade having a high level of cutting quality.

  On the other hand, the blade-to-blade guard is preferably made of a fully annealed low carbon stainless steel such as grade AISI 301 / DIN 1.4310. This material is selected for several reasons, such as the ease of forming a desired profile, such as that disclosed in the aforementioned US Pat. For ease of assembly, the blade-to-blade guard can be joined to each razor blade by welding, such as laser spot welding.

  Thus, small compositional differences can exist between the razor blade and the inter-blade guard assembled to it. In use, moisture and other components may be trapped and retained between the razor blade and its inter-blade guard. This moisture can act as an electrolyte and therefore the razor blade, the inter-blade guard, and the moisture between them can constitute an electrochemical cell, which is the local electrochemical of the razor blade. May cause mechanical corrosion. Since the blade-to-blade guard is mounted on the razor blade in a position that is visible to the user, any such corrosion is visible to the user and the user may at least think that the appearance is poor, and this corrosion causes the razor blade to An actual or perceived premature failure of a razor cartridge having such a razor blade assembly may be caused. In addition, many modern safety razor cartridges can have an extended useful life when compared to previous razor cartridges. An improved coating on the cutting edge (e.g., hard carbon) can extend the useful life of the cutting edge, and so-called improved lubrication strip composition or configuration can extend the life of the lubricating strip. Modern safety razor cartridges with an extended life are more likely to corrode during their life than conventional razor cartridges.

US Patent No. 7,681,314 (US Patent Application No. 11 / 150,744, US Patent Publication No. 2006/0277759) US Pat. No. 4,586,255

  The present disclosure needs to eliminate or at least substantially reduce the limitations of prior art razor blade assemblies for that purpose.

  The present disclosure in one aspect is directed to a method of manufacturing a razor blade assembly for a razor cartridge, the method comprising a stainless steel elongated strip of a first composition including a leading edge and a first side. And preparing the cutting edge to extend along the leading edge of the elongate strip so as to cause a martensitic transformation to cure the strip. The strip is cut into longitudinally extending portions to provide individual razor blades having a length suitable for use in a razor cartridge housing. A chromium oxide layer is formed on the first side of the razor blade by a thermal oxidation process. The inter-blade guard is permanently joined to the first side of the razor blade. The razor blade and the blade-to-blade guard comprise stainless steels of different compositions, and the chromium oxide layer prevents or delays the appearance of electrochemical corrosion visible to the user on the first side of the razor blade. The razor blade assembly is assembled to the housing to provide a razor cartridge. A predetermined array of closely spaced droplets adapted to inhibit razor blade corrosion can be applied to a portion of the razor blade first side, a portion of the skin engaging surface of the inter-blade guard. This array of droplets penetrates into the gap between the first side and the guard between the blades to further prevent the appearance of electrochemical corrosion on the first side of the razor blade to the user, or Can be delayed. Application of an array of droplets adapted to inhibit razor blade erosion is preferably performed on the assembled razor cartridge. It is preferable to limit the array of droplets to the razor blade assembly and to control it appropriately so that the aforementioned liquid is not unnecessarily applied to the outer surface of the housing, for example.

  These and other advantages of the present disclosure will be apparent to those skilled in the art in light of the following detailed description and drawings.

1 is a cross-sectional view of one embodiment of a razor blade and an inter-blade guard. 1 is a schematic diagram of one embodiment of a process equipment for providing a chromium oxide layer. FIG. FIG. 3 is a schematic cross-sectional view of a razor cartridge including a razor blade and an inter-blade guard. FIG. 2 is a schematic plan view of an apparatus for depositing a liquid corrosion inhibitor on a razor cartridge. 5 is a schematic plan view of the razor cartridge of FIG. 3 after processing in the apparatus of FIG.

  Referring now to the drawings, and in particular to FIG. 1, a cross-sectional view of a razor blade assembly 10 for use with a razor cartridge (100 in FIG. 3) is shown. The razor blade 20 typically includes a stainless steel substrate having a thickness of about 0.05 mm-0.10 mm. Stainless steel typically contains from about 0.4% to 0.7% by weight carbon and from about 12% to 13.5% by weight chromium. Stainless steel is hardened to cause martensitic transformation and the base material is hardened to, for example, 700 HV-850 HV. In the present disclosure, HV refers to hardness measured on a Vickers scale at a load of 1.0 kg. The blade 20 has a cutting edge 22 and a body 24 having a first side 26 and a second side 28. An inter-blade guard 30 is attached to the first side 26 of the razor blade 20. This inter-blade guard includes a surface 36 adapted to contact the user's skin surface during normal use of the razor cartridge. Further desired features and functions of the blade-to-blade guard are disclosed in the aforementioned US Pat.

  The inter-blade guard 30 is preferably made from annealed low carbon austenitic stainless steel, such as grade AISI 301 (DIN 1.4310), preferably in the range of about 0.05 mm-0.076 mm. However, the present disclosure is not limited in this respect, and other materials that can be easily formed into a desired profile and / or that can be easily joined to a razor blade are effectively utilized. Can be used. The inter-blade guard 30 is permanently joined to the razor blade, for example by a well-known laser spot welding process (FIG. 1 shows the weld 32 in cross-section). Other bonding methods may be utilized such as using an appropriate adhesive such as an epoxy (eg, a two-part epoxy) or cyanoacrylate.

The razor blade assembly 10 can also include a support member 40 as is well known in the art.
The razor blade 20 is manufactured as follows. First, a rolled sheet of stainless steel is cut into elongated strips. The strip can be perforated for ease of handling during subsequent processing. If necessary, other pre-cure steps such as scoring may be performed.

  When the desired sequence of pre-hardening steps is complete, the strip is subjected to a hardening process including austenitization of stainless steel. The curing process takes place in a first muffle furnace or tunnel oven. The strip is provided in the form of a coil, unwound and fed into a furnace where the furnace is rapidly raised to a high temperature, for example about 1160 ° C. and maintained at this temperature during the austenitization of the stainless steel. Is done. The strip is then rapidly cooled (e.g., in an ice-box) to a low temperature of, for example, about -70 [deg.] C, causing martensitic transformation of the stainless steel substrate material. Rewind the strip and pass it to the later process. The hardness of the strip thus treated has a hardness of about 700 HV-850 HV.

  Subsequently, the strip is sharpened by known process steps to provide a cutting edge. After the process leading to the cutting edge, the strips can be cut into lengthwise sections, resulting in razor blades having a length suitable for use with a razor cartridge, which can be stacked on top of each other in a suitable carrier. Alternatively, the strip can be rewound for further processing. The razor blade stack (or rewind) is then optionally removed by any one of a number of processes well known in the art to remove residue and other contaminants from the sharpening process. Wash the strip). A coating on the cutting edge which can be a metal (eg titanium, niobium, chromium), ceramic (eg chromium nitride) or hard carbon (eg amorphous diamond or DLC (diamond-like carbon)) or a combination thereof. Apply and apply a further outer layer of a low friction coating of a fluorinated polymer such as PTFE. PTFE is applied by spraying a suspension of PTFE particles in a suitable medium such as water and / or alcohol onto the cutting edge. A razor blade or coiled strip in the carrier is placed on a conveyor to provide a continuous adherent (ie cured) PTFE film, or a second muffle furnace at about 360 ° C. or Pass through a tunnel oven to cure the PTFE. Heating the razor blade to perform the PTFE curing process has the effect of partially annealing the razor blade to a hardness of about 600 HV or higher, for example about 680 HV. The process equipment is shown schematically in FIG. 2 showing stacked blades in a carrier 48 that is conveyed through a furnace 60 on a conveyor 50.

  As mentioned above, modern safety razors are typically used in humid environments and can be stored by users in a humid environment that is subject to change. In use, the razor blade of a razor cartridge is contacted with various mildly corrosive substances at various concentrations, such as sweat, soap, and ingredients for shaving aids such as shaving foam or gel. Further, the typical tap water composition commonly used for shaving can vary from city to city. Furthermore, modern safety razor cartridges can have an extended service life compared to previous razor cartridges. Improved coatings (eg, hard carbon) on the cutting edge can increase the service life of the cutting edge, and so-called lubrication strip composition or configuration can improve the life of the razor cartridge lubrication strip. Modern safety razor cartridges with an extended life are more likely to corrode during their life than conventional razor cartridges.

  In order to increase the corrosion resistance of the razor blade stainless steel material over the range of possible use environments, a chromium oxide layer is formed on the outside (26, 28) by a thermal oxidation process. The razor blade is introduced into an atmosphere of clean dry air from about 160 ° C. to 215 ° C., for example 190 ° C. In brief, the hardening process described above converts some of the chromium and carbon of the stainless steel material into chromium carbide that partially provides the mentioned hardness. Some chromium remains unreacted with carbon and this so-called free chromium on the surface of the stainless steel is oxidized as follows to form a corrosion-resistant chromium oxide layer on the stainless steel substrate.

  A razor blade in the carrier is preferably a third muffle furnace or tunnel oven, preferably arranged in series with the second furnace 60, to benefit from providing the conveyor 50 for the PTFE curing process. Pass 70. The furnace is set to the aforementioned temperature of 160 ° C. to 215 ° C., for example 190 ° C., and dry air 80 with clean atmospheric temperature passes through the furnace muffle tube 82 in the direction shown or in the opposite direction. The aforementioned temperature range is selected to avoid significant further incomplete annealing of any of the razor blades. A chromium oxide layer is formed on the outside of the razor blade.

  The thickness of the chromium oxide layer is preferably controlled to a thickness of about 10 nm to about 15 nm (about 10 to about 150 mm). A thickness of less than about 10 nm is less preferred since the corrosion resistance of the razor blade may not increase as desired. Similarly, a thickness greater than about 15 nm is less preferred because the corrosion resistance of the razor blade does not increase proportionally. Similarly, thicknesses greater than about 15 nm can lead to undesirable color changes on the surface of the razor blade, which can be subjectively perceived by casual viewers. Since color changes can be considered commercially undesirable for razor blades or razor cartridges containing such razor blades, it is preferred that the thickness of the chromium oxide layer does not substantially change the color of the razor blade. Control of the thickness of the chromium oxide layer is primarily achieved by adjusting the time that the strip is in the furnace (eg, by adjusting the conveyor speed) and / or by adjusting the furnace temperature. Second, it can be controlled by adjusting the flow rate of air through the furnace muffle tube.

  In other embodiments, the third furnace can be arranged separately from the second furnace. The third furnace can also be placed in succession with the first furnace and the ice box, in which case an oxide layer is formed on the strip before providing the cutting edge and subsequent coating. As an alternative to the use of a muffle furnace, the third furnace can be a closed furnace, and the entire blade carrier or strip coil can be processed internally in a so-called batch process.

  It is known to provide a chromium oxide layer up to a thickness of about 8 nm (80 cm) by chemical or electrochemical passivation. However, this process can be used today for a variety of reasons, including capital costs, the required chemical use and subsequent environmental impact, and general storage, health and safety issues. Is not desirable.

The corrosion resistance of a strip or a razor blade made from a strip or a razor cartridge containing such a razor blade is evaluated in the following accelerated corrosion test.
a) A strip, or a razor blade made from a strip, or a specimen that can include a portion of a razor cartridge containing such a razor blade, is soaked in 0.2% saline at 60 ° C. for 10 seconds.
b) The specimen is removed from the solution and placed in an oven at 60 ° C., 95% RH (relative humidity) temperature / humidity for 25 minutes.
c) Remove the specimen from the oven and visually inspect up to 2.5 times magnification to compare any corrosion to a predetermined severity rating scale.
d) Repeat steps a) to c) for a total of 15 cycles.

  Referring again to FIG. 1, the razor blade can be joined to a metal support 40 as is well known in the art, for example as disclosed in US Pat. During normal use and handling of safety razors including such razor blades, an interblade guard 30 (as described above) is joined to the side of the razor blades that is visible to the user. As can be seen in FIG. 1, a certain narrow gap 34 exists between the razor blade and the blade-to-blade guard, which traps moisture and / or dilute weakly corrosive substances after use, Moisture and the like can be retained by the capillary effect / surface tension effect. As mentioned above, the stainless steel composition of the razor blade and the inter-blade guard can be slightly different. In the absence of a protective chromium oxide layer on the razor blade that acts as an insulator, the anode and cathode razor blade and the blade-to-blade guard produce an electrochemical cell in which the electrolyte is moisture, etc., and therefore the side razor blade visible to the user Electrochemical corrosion can occur on the top, and undesirably this electrochemical corrosion can be fully visible to the user.

  Referring now to FIG. 3, an exemplary schematic cross-sectional view of a razor cartridge 100 including a razor blade and inter-blade guard assembly 10 is shown. The razor cartridge can generally be as disclosed in the aforementioned US Pat. No. 6,057,086, or can be another type of razor cartridge, but the present disclosure is directed to that type of razor cartridge. It is not limited. A razor cartridge may also include more than two, eg, three, four, or more razor blade assemblies 10, and the present disclosure may include that number of razor blade assemblies 10 within a razor cartridge. It is not limited to. The cartridge includes a housing 110 consisting of a guard 112, a cap 114 and a blade attachment region 116. A (vertical) portion of the blade support 40 is disposed in the slot 126 of the end wall 118 of the housing 110 and provides independent movement of each blade assembly under the forces generated during shaving. The guard and cap can each include an elastomeric element 122 and a lubricating element 124, as are well known in the art. A spring element 130 can be provided, as is well known in the art.

  Referring now to FIG. 4, an apparatus for a further advantageous process for inhibiting corrosion of a razor cartridge razor blade assembly is shown schematically in plan view. This process can be performed in addition to or as an alternative to the thermal oxidation process described above. After assembling a razor cartridge, eg, a razor cartridge as shown in FIG. 3, the razor cartridge 100 is placed on the conveyor 150, preferably in the nest 152 of the conveyor, preferably on the indexing conveyor. The razor cartridge is arranged such that the blade edge of the blade assembly and the inter-blade guard are exposed. While indexing the dwell at position 154, the spray head 160 passes over the cartridge, preferably in a direction transverse to the direction of movement of the conveyor. The spray head 160 is controlled to deposit a predetermined close packed array of liquid rust inhibitor / oil mixture (170 in FIG. 5) on the exposed surface of the razor cartridge blade assembly. With a spray pattern. This spray pattern is limited to the aforementioned surfaces of the blade assembly and is preferably not unnecessarily applied to the outer surface of the housing, for example. In order to achieve proper control of the spray pattern, the spray head is preferably an ink jet spray head modified to spray a predetermined array of rust inhibitor / oil mixture instead of ink. A suitable ink jet spray head is SCANTRUE II provided by TRIDENT. Modifications to the spray head to make it suitable for the aforementioned mixture include replacing the internal seal (eg, an “O” ring) with a seal of VITON material to resist degradation due to contact with the aforementioned mixture. The rust inhibitor / oil mixture is also formulated to have a viscosity approximately equal to that of typical inks used in such ink jet equipment, for example about 7-10 centistokes, both provided by CRODA INC. It preferably contains 10% by volume of a rust inhibitor such as CRODASINIC-O and / or CRODAZOLINE-O, and more preferably contains 5% by volume of each rust inhibitor. More preferably, the mixture further comprises 70% mineral oil, such as Naphtha Hydrogenated Heavy oil, provided by EXXON MOBIL. Preferably, the mixture further comprises 20% mineral spirits, such as, for example, odorless mineral spirits. It is preferred to avoid separation of the rust inhibitor / oil mixture into its components over a long period of time, such as 25 days or more. The rust inhibitor / oil mixture preferably has a sufficiently low surface tension and is less likely to be a ball on the exposed surface of the razor cartridge blade assembly. The spray pattern of the spray head can be programmed by a conventional ink jet spray control device to spray an array of closely packed drops as described above. The spray head passes over each razor cartridge once, twice (ie, by a back-and-forth motion synchronized to each index of the conveyor), or more, depending on the desired amount of adhering mixture. Can be configured. Since the spray head is programmable, razor cartridges with various exposed blade configurations can be accommodated, for example, the exposed configuration can be rectangular, trapezoidal, elliptical, and the like. Thus, the total amount of rust inhibitor / oil mixture applied can be about 2 mg per razor cartridge. Since the rust inhibitor / oil mixture is a liquid, therefore, some of the applied liquid will at least partially flow into the gap 34 between the razor blade and the interblade guard by capillary action. This can delay or prevent the aforementioned moisture and / or dilute weakly corrosive substances from entering the gap and, as a result, delay or prevent the appearance of electrochemical corrosion visible to the user. Also, since the rust inhibitor / oil mixture remains liquid and is less prone to beading, the droplets spread in a short period of time, eventually merging with adjacent droplets and substantially over the applied surface. A continuous film is produced. In the accelerated corrosion test described above, the razor cartridge treated by this apparatus can have a threshold for unacceptable corrosion that is 2-3 times greater than that of an untreated razor cartridge.

  While various embodiments have been described above, it should be understood that these have been presented by way of example, not limitation. For example, modifications or changes may be made within the scope of the appended claims, and the features disclosed in conjunction with any one embodiment may be used alone or with each feature of each other embodiment. They can be used in combination. Accordingly, the breadth and scope of the embodiments should not be limited to any of the above-described exemplary embodiments, but should be determined according to the following claims and their equivalents.

10: Razor blade assembly 20: Razor blade 22: Cutting edge 24: Main body 26: First side 28: Second side 30: Inter-blade guard 32: Welded portion 34: Gap 36: Surface 40: Support member 48: Carrier 50, 150: conveyor 60, 70: muffle furnace (or tunnel oven)
80: Dry air 82: Muffle tube 100: Razor cartridge 110: Housing 112: Guard 114: Cap 116: Blade mounting area 118: End wall 122, 124: Element 126: Slot 130: Spring element 160: Spray head 170: Droplet Array of

Claims (8)

A method of making a razor blade assembly for a razor cartridge, comprising:
a) comprising stainless steel of a first composition, having a first side and a cutting edge extending along its leading edge, and further processed to cause its martensitic transformation to harden the razor blade Preparing a razor blade;
b) providing a chromium oxide layer on the first side by a thermal oxidation process;
c) an interblade guard comprising a surface comprising stainless steel of a second composition and adapted to contact the user's skin surface during normal use of the razor cartridge comprising the razor blade assembly; Permanently bonding to the first side of the razor blade;
Applying an array of closely packed droplets adapted to inhibit corrosion of the razor blade to at least a portion of the first side of the razor blade;
A method comprising the steps of: Further comprising assembling the razor blade assembly into a housing, the resulting assembly including the razor cartridge;
2. The step of applying an array of closely packed droplets adapted to inhibit corrosion of the razor blade is performed after the razor blade is assembled to the housing. The method described in 1.   The chrome oxide layer is between about 10 nm and 15 nm thick, and the chrome oxide layer does not substantially change the color of the first side of the razor blade. The method according to 1. A method of making a razor blade assembly for a razor cartridge, comprising:
a) providing a razor blade comprising stainless steel of a first composition and having a first side and a cutting edge extending along its leading edge;
b) an interblade guard comprising a surface comprising stainless steel of a second composition and adapted to contact the user's skin surface during normal use of the razor cartridge comprising the razor blade assembly; Permanently bonding to the first side of the razor blade;
c) applying to the at least part of the first side of the razor blade a close-packed droplet array adapted to inhibit corrosion of the razor blade. And how to. A housing;
A razor blade assembly including a razor blade having a first side; and an inter-blade guard permanently attached to the first side of the razor blade;
Including
The razor blade includes stainless steel having a first composition, and the inter-blade guard includes stainless steel having a second composition different from the first composition;
The inter-blade guard includes a skin engaging surface adapted to contact a user's skin surface during normal use of the razor cartridge;
The first side of the razor blade includes a chromium oxide layer;
A razor cartridge, further comprising an array of droplets adapted to inhibit corrosion of the razor blade over at least a portion of the first side of the razor blade.   The array of droplets adapted to inhibit corrosion of the razor blade is further over at least a portion of the skin engaging surface of the inter-blade guard. Razor cartridge.   The array of droplets adapted to inhibit corrosion of the razor blade is further in at least a portion of a gap between the first side of the razor blade and the inter-blade guard. The razor cartridge according to claim 5.   6. The chromium oxide layer of claim 5, wherein the chromium oxide layer is between about 10 nm and 15 nm thick and does not substantially change the color of the first side of the razor blade. Razor cartridge.

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