Shaving article with surface modification

Abstract

A method of making a shaving article comprising a substrate comprising stainless steel; and an external polymer coating comprising polymer brushes, the method comprising the steps of: providing said substrate; providing a initiating species comprising an anchor group that is chemically reactive with surface moieties on the substrate, and a polymerization initiator group; reacting said anchor group with said surface moieties of the substrate; providing monomers reactive for polymerization with the polymerization initiator; and polymerizing the monomers with the initiator group of the initiating species.

Claims

1. A method of making a shaving article comprising: a substrate comprising stainless steel; and a polymer coating comprising polymer brushes, the method comprising the steps of: a. providing said substrate; b. providing an initiating species comprising an anchor group that is chemically reactive with surface moieties on the substrate, and a polymerization initiator group, the polymerization initiator group is an alkyl halide; c. reacting said anchor group with said surface moieties of the substrate; d. providing monomers reactive for polymerization with the polymerization initiator; and e. polymerizing the monomers with the initiator group of the initiating species.

2. The method of claim 1 wherein the substrate in step a. comprises hydroxy groups or oxo groups.

3. The method of claim 2 including the step of treating the substrate to increase the surface density of hydroxy groups and/or oxo groups prior to step c.

4. The method of claim 1, wherein the anchor group is selected from the group consisting of acrylate groups, hydroxy groups, silane groups, and phosphonic acid groups.

5. The method of claim 4, wherein the silane group is selected from the group consisting of alkoxylsilane groups and halide silane groups.

6. The method of claim 1, wherein the anchor group is an alkoxysilane group having the formula Si(OR).sub.3, where R is a lower alkyl group.

7. The method of claim 1, wherein the halide is selected from the group consisting of Br and Cl.

8. The method of claim 1, wherein the initiating species comprises 2-bromo-2-methyl-N-(3-(triethoxysilyl)propyl) propanamide.

9. The method of claim 1, wherein polymerization step e. involves atom transfer radical polymerization.

10. The method of claim 1, wherein in steps d. and e. a block copolymer is generated, said block copolymer preferably having a proximal hydrophobic block and a distal hydrophilic block.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The features and advantages of the invention will be appreciated upon reference to the following drawings, in which:

(2) FIG. 1 is a graphic of cutting force associated with a variety of coated razor blades.

(3) FIG. 2 is a graphic of coefficient of friction development for steel blades during cutting cycles.

(4) FIG. 3 is a front schematic view of a wet razor having a cartridge unit and a handle.

(5) FIG. 3a is a rear schematic view of the wet razor of claim 1.

(6) FIG. 4 is a close-up schematic view of elements of a blade edge of the present invention.

(7) FIG. 5 is a close-up schematic view of the blade of FIG. 3 having polymer brush layer grafted thereon.

(8) FIG. 6 is a schematic view of a substrate having polymer brushes grafted therefrom.

DETAILED DESCRIPTION OF THE INVENTION

(9) The following is a description of aspects and features of the invention, given by way of example only and with reference to the drawings.

EXAMPLES

(10) The following examples demonstrate, by way of illustration only, polymer brush systems grafted from stainless steel substrates.

(11) Stainless steel substrates were stainless steel sheet (thickness 5 mm, Fe/Cr-13, AEB-L grade) laser cut into 1010 mm squares.

(12) In examples 1, 2 and 3 below, polymer brushes incorporating monomers of pentafluoropropyl acrylate (PFA), heptadecafluorodecyl acrylate (HFA), and 2-(2-methoxyethoxy)ethyl methacrylate (MEO.sub.2MA) are demonstrated.

(13) In examples 4 and 5, addition of bi-layer copolymer brushes is demonstrated by grafting of 2-(2-methoxyethoxy)ethyl methacrylate (MEO.sub.2MA) from the products of examples 1 and 2.

(14) Substrate Preparation

(15) Four 10105 mm blocks of stainless steel were polished and cleaned. They were then exposed for 25 minutes in a UV-Ozone cleaner to remove the hydrocarbon contaminants and increase the surface hydroxy group concentration, with which the initiator species can subsequently react.

(16) Thereafter the stainless-steel samples were functionalised with BTPAm initiator as follows. 3 parts by volume of initiator was added to 10 parts by volume methanol and was dispersed by stirring for 2 min, followed by the addition of 87 parts by volume deionized water. The mixture was stirred at 40 C. until the cloudy solution turned transparent (about one hour). The transparent solution was then cooled to room temperature.

(17) The well-cleaned stainless-steel substrates were then immersed into the initiator solution at ambient temperature for 30 min to immobilise the initiator. The stainless-steel substrates were taken out from the initiator solution and dried under a pressurised stream of N.sub.2, followed by 60 min of curing at 60 C. in an oven. After curing, the samples were rinsed with methanol and water, being dried with N.sub.2.

Example 1P(HFA) Brush Synthesis

(18) A 50 ml flask was charged with a stir bar and the monomer heptadecafluorodecyl acrylate (HFA) (6 ml, 9.82 g, 19.0 mmol) was measured into the flask. To this 18 ml of DMF was added along with a TDA ligand (0.301 ml, 304.5 mg, 0.94 mmol). Once this had fully dispersed after a minute or so of stirring FeBr.sub.3 (11.9 mg, 0.04 mmol), the deactivator, was inserted. The flask was sealed, stirred at 110 C., and purged with nitrogen for 30 minutes. After the 30 minutes FeBr.sub.2 (65.7 mg, 0.305 mmol) was added to the flask and then it was resealed and left to purge for a further 30 minutes.

(19) During degassing of the reagents, the BTPAm-functionalized substrates were placed into test tubes ensuring that the polished and functionalized side faced upwards. These tubes were sealed and placed in a reaction station. Several evacuation and nitrogen refilling cycles were performed finally leaving the tubes under nitrogen, ensuring all tubes contained an inert atmosphere.

(20) Once degassed the heated reagent mixture solution was withdrawn into a nitrogen purged syringe and 2 ml was carefully injected into each the tubes containing the initiated substrate and heat at 110 C. was applied.

(21) Following polymerization, the lid was opened from the tube and the solution was carefully poured away to stop the reaction and the sample was removed ensuring minimal contact with the upwards facing grafted surface.

(22) Each sample was rinsed copiously and with hot -trifluorotoluene and sonicated in the same before being blown dry under a N.sub.2 flow.

(23) In this manner, a semi-fluorinated layer was successfully added to the substrate to mimic a PTFE coating and to form a corrosion resistant layer acting to drive water away from the metal surface.

Example 2P(PFA) Brush Synthesis

(24) The synthesis reaction was carried out as with example 1 P(HFA) except with altered volumes for the monomer and solvent respectively as follows; pentafluoropropyl acrylate (PFA) (2.91 ml, 3.84 g, 19.0 mmol) and DMF (21.09 ml).

(25) In this manner, a semi-fluorinated layer was successfully added to the substrate to mimic a PTFE coating and to form a corrosion resistant layer acting to drive water away from the metal surface.

Example 3P(MEO.SUB.2.MA) Brush Synthesis

(26) The addition of a P(MEO.sub.2MA) polymer chain was carried out using the same procedure for examples 1 and 2.

(27) This was used as a hydrophilic, water-swellable layer believed to result in high load bearing characteristics leading to a reduction of friction.

Examples 4P(PFA-b-MEO2MA) Block Copolymer Brush Synthesis

(28) The addition of a second polymer block comprising P(MEO.sub.2MA) was carried out using the same procedure for the single block synthesis of example 3 except the substrates were pre-grafted with P(PFA) as in example 1.

Example 5P(HFA-b-MEO2MA) Block Copolymer Brush Synthesis

(29) The addition of a second polymer block comprising P(MEO.sub.2MA) was carried out using the same procedure for the single block synthesis of example 3 except the substrates were pre-grafted with P(HFA) as in example 2.

Comparative Example

(30) In order to compare the grafted fluorinated layers on SS to an industry standard PTFE coating, stainless steel substrates were prepared using the same pre-functionalisation procedure were coated with PTFE. Polished stainless-steel blocks were sprayed with an aqueous dispersion of PTFE. This was subject to ionising radiation in the presence of oxygen to remove excess PTFE. The layer was then sintered between 305 C. and 470 C.

(31) Contact angle measurements of the modified substrates were taken using the Sessile drop method. The contact angle measurements indicated successful modification of the surface, as shown in table 1.

(32) TABLE-US-00001 TABLE 1 Example Sample Contact angle () / SS-(UVO) 15.0 / SS-BTPAm 59.2 1 SS-P(PFA) 98.3 2 SS-P(HFA) 119.2 3 SS-P(MEO.sub.2MA) 52.6 4 SS-P(PFA-b-MEO.sub.2MA) 23.0 5 SS-P(HFA-b-MEO.sub.2MA) 46.9 Comparative SS-PTFE.sup.a 118.3 SS = Stainless Steel

(33) It is clear that attachment P(PFA) and P(HFA) to the surface had occurred due to the highly hydrophobic values measured at 98.3 and 119.2 respectively. Decreased contact angles of 23.0 for the P(PFA-b-MEO.sub.2MA) and 46.9 for the P(PFA-b-MEO.sub.2MA) indicate a hydrophilic exterior. Example 3 with a single block of P(MEO.sub.2MA) on the initiated stainless steel gave a contact angle of 52.6 and so was also hydrophilic. The PTFE coated sample exhibited a contact angle of 118.3, indicating that P(HFA)(119.2) was able to display a similar degree of hydrophobicity to PTFE.

Application to Blades

(34) Using the same techniques as discussed in examples 1 to 5 above, polymer brushes were grafted from stainless steel razor blade substrates. Razor blades with the following polymer brushes were tested: block copolymer TFA and PMO; PFA and PMO; PFS and PMO; HFA-PMO; PMO; PFS; PFA; TFA; and HFA.

(35) FIG. 1 shows the cutting force results for the treated razor as compared to the uncoated stainless-steel substrate and an industry standard applied PTFE. As can be seen from the figure, all treated blades showed a reduced cutting force as compared to the uncoated stainless steel, with polymer brushes of HFA performing comparably well with the standard PTFE.

(36) The cutter force can be measured by a method including the steps of providing a blade having an edge; providing a fiber mount for holding the fiber; providing a sensor connected to the fiber mount; moving the blade toward the fiber and cutting the fiber; and measuring the cutting force on the fiber with the sensor. Such a test is described in patent publication US 2011/0214493, the content of which is hereby incorporated by reference.

(37) FIG. 2 shows the results of sustained friction tests for stainless steel substrates coated with conventional PTFE coating and stainless-steel substrates coated with polymer brushes of P(HFA), while wet and at room temperature, and using Microtribometry. In the tests 50 loading and unloading cycles were inflicted upon the substrates.

(38) As can be seen from FIG. 2, the coefficient of friction of the conventional PTFE coated substrate quickly increases suggesting loss or damage to the lubricating PTFE coating with each testing cycle. This is in contrast to the SS-P(HFA) substrate, which maintains a low coefficient of friction for a greater number of testing cycles.

(39) As discussed previously, the present invention is applicable to shaving articles. Preferred shaving articles may be cutting elements, in particular razor blades of wet shave razors or cutter elements of electric dry razors. Other preferred shaving articles may be non-cutting elements, in particular blade clips in a wet shaver or outer or inner surfaces of a foil disposed in an electric dry shaver.

(40) Referring to FIG. 3, a front view of a wet razor 20 generally includes a shaving or cartridge unit 22 attached to a handle 24 with the shaving unit 22 having one or more blades 21 (e.g., 5 blades shown) each with a sharpened edge 21a and comprising stainless steel. A cap 23 and guard 25 may also be included in the shaving unit 22, the cap 23 preferably including a lubricating strip or shaving aid composite 23a affixed thereon. The shaving unit 22 also includes a frame or housing 26, preferably made of hard plastic. In this particular shaving unit 22, there is also present a lubricating ring 28 disposed around the periphery of the shaving unit 22. The lubricating ring 28 may generally be comprised of water soluble and water insoluble polymers. The cartridge unit 22 may be adapted for coupling and uncoupling from the razor handle 24 such that a new cartridge unit 22 may be coupled to the handle when the blades become dull or may be integral with a handle 24 so that the complete razor 10 is discarded when the blades become dull.

(41) FIG. 3a depicts the opposite or rear side of the razor 20 showing the back side of the frame 26 along with a blade support unit 27 which preferably may be a metal or plastic unit used to support the individual blades. The blade support 27 may preferably be disposed within an aperture of the frame 26 after the blades 21 are inserted therein and held in by a pair of blade clips 29 on either end of the support 27. Also shown in FIG. 2a is a cartridge connecting structure 30 which is a structure that connects the cartridge unit 22 to the handle 24. The structure 30 may be part of the handle 24 or may be part of the cartridge unit 22.

(42) While a specific embodiment of a razor is depicted in FIGS. 3 and 3a, any razor construction type is contemplated in the present invention.

(43) In accordance with the invention, the razor blade edges 21a, razor blades 21, blade clips 29, and/or blade support 27 comprise stainless steel substrates, and a coating of polymer brushes grafted from one or more portions of the surfaces of those shaving articles, in accordance with the invention.

(44) Referring to FIG. 4, there is a razor blade edge 21a. The razor blade edge 21a includes a blade body 51, two bevels 56 for each of two flanks 53 which intersect at tip 54 forming the blade edge 21a.

(45) A diagrammatic view of a blade region 60 or sharpened substrate, and in particular the blade body region 51 and blade edge 21a of blade edge 21 of FIG. 3, is shown in FIG. 4.

(46) Grafted from the body 51 and flanks 53 of substrate 52 is a polymer brush layer 62, 64. In FIG. 5 the polymer brush layer 62, 64 may be deposited directly onto the substrate as shown or may be deposited on top of one or more other layers already deposited on the substrate 22, such as one or more interlayers, one or more adhesion layers and/or one or more overcoat layers (not shown). For example, the stainless steel based or core of the substrate may be coated with layers of inorganic materials for hardness and corrosion resistance, such as diamond, amorphous diamond, diamond-like carbon (DLC) material, nitrides, carbides, oxides, and ceramics in general, which may form part or all of an intermediate layer, upon which the polymer brush layer is provided.

(47) The present invention further contemplates that the polymer brushes in addition to, or alternatively to, being bound to razor blade surfaces are also provided on any other razor components, such as on the blade clips 29. The clips 29 are generally made of a metal. The metal may be comprised of stainless steel, but may also be aluminum. The shaving benefits of glide, comfort, cleanliness etc. along the shave path may be augmented by adding the polymer brushes (e.g., a lubricious polymer brushes or antibacterial brushes) on the upper surface of the clips 29 which are generally disposed on the left and right sides of the cartridge.

(48) The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as 40 mm is intended to mean about 40 mm.

(49) Every document cited herein, including any cross referenced or related patent or application and any patent application or patent to which this application claims priority or benefit thereof, is hereby incorporated herein by reference in its entirety unless expressly excluded or otherwise limited. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein or that it alone, or in any combination with any other reference or references, teaches, suggests or discloses any such invention. Further, to the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern.

(50) While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.