Patent Application
20090223057
1. Technical Field
This invention relates to shaving devices in general, and to shaving aids used with shaving devices in a wet environment in particular.
2. Background Information
Modern safety razors include a plurality of blades disposed within a cartridge that is pivotally or rigidly mounted on a handle. Some safety razors have a disposable cartridge for use with a reusable handle, while others have a handle and cartridge that are combined into a unitary disposable. Although a variety of razor cartridge configurations exist, most include a frame made of a rigid plastic that includes a seat and a cap. Cartridges often include a guard disposed forward of the blades. The guard and the cap orient the position of the person's skin relative to the blades to optimize the shaving action of the blade. Some cartridges include a shaving aid strip (sometimes referred to as a “comfort strip”) comprised of shaving aids (e.g., lubricating agents, drag reducing agents, depilatory agents, cleaning agents, medicinal agents, etc.) to enhance the shaving process. Other shaving systems, such as the Intuition®, utilize a body of shaving aid material disposed entirely around a razor cartridge. The terms “forward” and “aft”, as used herein, define relative position between features of the safety razor (i.e., razor assembly). A feature “forward” of the razor blades, for example, is positioned so that the surface to be shaved encounters the feature before it encounters the razor blades, if the razor assembly is being stroked in its intended cutting direction (e.g., the guard is forward of the razor blades). A feature “aft” of the razor blades is positioned so that the surface to be shaved encounters the feature after it encounters the razor blades, if the razor assembly is being stroked in its intended cutting direction (e.g., the cap is disposed aft of the razor blades).
The comfort and performance provided by a particular razor are critical to the commercial success of the razor. Improvements that benefit razor comfort, performance, and ease of use, however significant or subtle, can have a decided impact on the commercial success of a razor. For example, the usable life of a cartridge is often limited by the usable life of the shaving aid strip. Once the shaving aid strip is consumed, it is generally believed that the razor must also be in need of replacement. In fact, razor blades within currently available razor assemblies are very often still fit for use after the shaving aid strip has been consumed.
It is known that shaving aid strips may be formed into a solid comprising at least one water-soluble polymeric component, such as polyethylene oxide, and a water-insoluble polymeric matrix comprising, for example, polystyrene. Upon exposure to water, the water-soluble shaving aid leaches from the composite onto the skin, thereby depositing the materials that facilitate the shaving process. This type of shaving aid strip works well until the water-soluble shaving aid material is substantially depleted, after which time the water-insoluble polymeric matrix is left to contact the user's skin with little or no assistance from the water-soluble materials. The result is a less than desirable shave experience.
In addition to providing a less than desirable usable life, shaving aid materials that include a relatively high molecular weight polymeric material as a matrix (e.g., polystyrene) also require processing temperatures that cause degradation of shaving aid materials such as polyethylene oxide and functional additives such as plasticizers, moisturizers, perfumes, and vitamins. Common processing temperatures for the extrusion of prior art shaving strips are often approximately 200° C. Efforts have been made to reduce the processing temperatures by manufacturing the shaving strips in, for example, a core-sheath configuration. For example, U.S. Pat. No. 6,298,558 to Tseng, discloses extrusion temperatures as low as 130° C. However, degradation of the shaving aid materials at even these reduced temperatures still occurs.
What is needed, therefore, is a razor shaving aid material that will last for an extended period of time, one that will provide a desirable shaving experience, and one that can be manufactured at temperatures low enough to avoid appreciable thermal degradations of ingredients.
It is, therefore, an object of the present invention to provide a razor assembly cartridge that provides a desirable perception of quality.
According to the present invention, a shaving aid material is provided that includes a water-soluble lubricious shaving aid in combination with a water-insoluble erodable medium. In some embodiments, the shaving aid material further includes a water-soluble thermoplastic polymer, and may also include a plasticizer. Optional additional ingredients include emulsifiers, surfactants, skin conditioners, fragrances, depilatory agents, cleaning agents, medicinal agents, etc., as will be described below.
Referring to
The shaving aid material is a composite that includes a water-soluble lubricious shaving aid in combination with a water-insoluble erodable medium. In some embodiments, the shaving aid material further includes a water-soluble thermoplastic polymer, and may also include a plasticizer. Optional additional ingredients include emulsifiers, surfactants, skin conditioners, fragrances, depilatory agents, cleaning agents, medicinal agents, etc., as will be described below.
An acceptable water-soluble shaving aid is polyethylene oxide (“PEO”). PEOs are commercially available, for example, from The Dow Chemical Company under the trademark Polyox® in a variety of different molecular weights including POLYOX WSR coagulant, POLYOX WSR N-750, etc. Those skilled in the art will appreciate that a PEO useful as a shaving aid may in fact be a mixture of different types of PEO (e.g., high molecular weight PEO in combination with low molecular weight PEO). In addition to PEO, or in some instances in place of PEO, the water-soluble shaving aid may include one or more of the following constituents: (A) a lubricating agent for reducing the frictional forces between the razor and the skin, e.g., a micro-encapsulated silicone oil; (B) an agent that reduces the drag between the razor parts and the shaver's face, e.g., a natural polysaccharide derived from plant materials such as guar gum; (C) an agent which modifies the chemical structure of the hair to allow the razor blade to pass through the whiskers very easily, e.g., a depilatory agent; (D) a cleaning agent which allows the whiskers and skin debris to be washed more easily from the razor parts during shaving, e.g., a silicone polyethylene oxide block copolymer and detergent such as sodium lauryl sulphate; (E) a medicinal agent for killing bacteria, or repairing skin damage and abrasions; (F) a cosmetic agent for softening, smoothing, conditioning or improving the skin; (G) a blood coagulant for the suppression of bleeding that may occur from nicks and cuts; and (H) an astringent for constricting blood vessels thereby stemming the flow of bodily fluids such as lymph, which may exude from skin which has been irritated during shaving. The water-soluble shaving aid may include constituents that by themselves are partially or completely water-insoluble, but in combination with other shaving aid constituents are water-soluble to an acceptable degree.
An acceptable erodable medium is one that may be described as being malleable at normal ambient temperatures, has a melting point above approximately 45° C. (113° F.), a relatively low viscosity when melted (e.g., below about 1000 centipoise; in contrast to a polymeric material that has a high viscosity once its temperature is raised above its glass transition temperature), is hydrophobic or water-insoluble, and has a molecular weight below about 25,000. In preferred embodiments, the erodable medium comprises an amphipathic material; i.e., a material comprised of molecules having a hydrophobic end and a hydrophilic end. Amphipathic materials have a “polar” nature that improves their compatibility with a “polar” material like PEO, and allows the materials to be more intimately mixed together; i.e., the nature of the amphipathic material is such that the PEO is at least partially miscible with the amphipathic material and thereby at least partially soluble with the erodable medium, which lowers the melt viscosity of the PEO and thereby creates a solution of PEO in “wax-like” material. This is in contrast to conventional shaving aid materials that include composites formed from a mixture of water-soluble shaving aid (e.g., PEO) and water-insoluble matrix material (e.g., polystyrene, polypropylene, etc.). In such prior art shaving aid materials, the solubility parameters of PEO and the water-insoluble polymer make them substantially incompatible with one another. The water-insoluble polymer does not bond with the PEO in the conventional shaving aid material, but rather remains independent and acts as a matrix to support the PEO.
The compatibility of the water-soluble material and the water-insoluble erodable medium within the present shaving aid material favorably influences the longevity of the shaving aid material. When a conventional shaving aid material is exposed to water, the water-soluble PEO leaches out of the water-insoluble polymer matrix, and the water-insoluble polymer matrix is left behind. In fact, the water soluble shaving aid material(s) usually leaches out from the matrix of the conventional shaving aid faster than desired. The remaining polymer matrix may erode on the user's skin during shaving, but it will not perform acceptably as a shaving aid material. In contrast, the intimately mixed water-soluble shaving aid and water-insoluble erodable medium of the present invention (which water-soluble shaving aid is at least partially miscible and therefore at least partially in solution with the water-insoluble erodable medium) are applied to the user's skin surface in combination. Some of the water-soluble shaving aid that is not in solution with the water-insoluble erodable medium (i.e., “free” water-soluble shaving aid) may be applied to the user's skin independent of the erodable medium. The shaving aid that is in solution, however, erodes in combination with water-insoluble erodable material. As a result: 1) the erosion of the water-insoluble erodable material is facilitated and the combination of the two provides a significantly better quality shaving aid material than, for example, the polymeric matrix that remains when using conventional shaving aid materials; and 2) the longevity of the present invention shaving aid material is substantially better than that of conventional shaving aid materials. The erosion mechanism of the present invention shaving aid material is also favorable relative to prior art shaving aid materials that utilize a water-soluble polymeric matrix in combination with a water-soluble shaving aid such as PEO.
The amphipathic materials include fatty alcohols and fatty acids. Fatty alcohols are aliphatic alcohols derived from natural fats and oils, originating in plants, but also synthesized in animals and algae. Smaller molecule fatty alcohols are used in cosmetics and food, and as industrial solvents. Due to their amphipathic nature, fatty alcohols behave as nonionic surfactants. They find use as emulsifiers, emollients and thickeners in the cosmetics and food industries. Fatty alcohols are a common component of waxes, mostly as esters with fatty acids but also as alcohols themselves. Fatty acids may be described as a group of chemical compounds characterized by a chain made up of carbon and hydrogen atoms and having a carboxylic acid (COOH) group on one end of the molecule. They differ from each other in the number of carbon atoms and the number and location of double bonds in the chain. When they exist unattached to the other compounds, they are called free fatty acids.
Amphipathic materials that can act as a surfactant typically have both lyophilic and lyophobic groups (properties) in the same molecule. These materials may also be referred to as being amphiphilic.
Examples of acceptable water-insoluble erodable mediums include stearic acid, palmitic acid, 12-hydroxystearic acid, stearyl alcohol (also referred to as octadecanol), cetyl alcohol (also referred to as hexadecanol), behenyl alcohol, cetearyl alcohol, arachidyl alcohol, C20-40 and C30-50 linear alcohols from New Phase Technologies under the trade name Performacol, paraffin wax alone or in combination with microcrystalline waxes; natural waxes including beeswax, carnauba wax, candelilla, and soy wax; silicone waxes such as C30-45 alkyl methicone such as Dow Corning AMS-C30, Dow Corning 2503 Cosmetic Wax, Dow Corning Silky Wax; specialty waxes such as Emulium Kappa from Gatefosse; wax esters such as Synchrowaxes from Croda; hydrogenated castor oils such as Castorwax and esters such as gylceryl mono-hydroxystearate (e.g., NatureChem GMHS, from CasChem); and polyethyle waxes such as Polywax 400, Polywax 850, and Polywax 1000 offered by Baker Petrolite Polymers.
In some embodiments, the present invention shaving aid material further includes a water-soluble thermoplastic polymer. The main function of the water soluble thermoplastic polymer is to enhance the tensile strength of the material. Secondary functions are to increase the erodability of the material. Examples of useful polymers are Hydroxypropyl cellulose (e.g., Klucel from Aqualon), Polyvinylpyrrolidone (e.g., PVP from ISP) and Polyvinylpyrrolidone/Vinyl Acetate copolymers (e.g., Plasdone from ISP) and Poly(2-ethyl-2-oxazoline) (e.g., Aquazol from Polymer Chemistry Innovations, Inc.); hydroxypropyl starch; Grain Processing Zeina B860.
In some embodiments, the present invention shaving aid further includes one or more plasticizers as processing aids to improve the flexibility of the material. Examples are isostearic acid, Triacetin, and liquid fatty alcohols such as oleyl alcohol, isostearyl alcohol.
As stated above, the configuration of the shaving aid manner, its place of application to the razor cartridge, the manner of attachment and/or other means and method of incorporation may vary widely to fit particular design requirements.
The following shaving aid material formulations represent examples of the present invention shaving aid material, and the present invention is not limited to these examples. The following groups can be generally described as follows. Group 1 examples include at least a fatty alcohol, thermoplastic polymer, PEO and, optionally, an emulsifier. Group 1 includes examples A, B, C, D, E and K. Group 2 examples include at least a fatty alcohol, an emulsifier, and PEO. Group 2 includes examples F, G, H, and L. Group 3 examples include at least a fatty alcohol (or fatty acid) and PEO. Group 3 includes examples I and J. Group 4 examples include at least a fatty alcohol (or fatty acid), PEO and an anionic surfactant. Group 4 includes examples M, N, and O. Group 5 examples include at least a fatty alcohol, a cationic surfactant, and PEO. Group 5 includes example P.
In Example A, the shaving aid material was formed from an erodable medium (Stearyl alcohol, Glyceryl Hydroxystearate), water-soluble shaving aid (Polyox Coagulant, Polyox N-10), Isostearic acid, and Hydroxypropyl cellulose in the percentages provided below in Table 1.
The materials were processed in a Sigma blade mixer. The Stearyl alcohol, Glyceryl hydroxystearate, and Isostearic acid were heated to about 225° F. until melted. The Hydroxypropyl cellulose was added and mixed until dissolved, and the Polyox materials were subsequently stirred into the mixture. The materials was subsequently poured onto release paper and pressed. The material was subsequently tested for performance.
In Examples B-D, the shaving aid material was formed from an erodable medium (Stearyl alcohol), water-soluble shaving aid (Polyox coagulant, Polyox N-10), PVP/VA copolymer, and Hydroxypropyl cellulose in the percentages provided below in Table 2.
The shaving aid materials in Examples B-D were processed in similar manner to that described above for Example A.
In Example E, the shaving aid material was formed from an erodable medium (Stearyl alcohol), water-soluble shaving aid (Polyox coagulant), PVP/VA copolymer, Isostearic acid, and Glycerol triacetate in the percentages provided below in Table 3.
The materials for the shaving aid material in Example E were processed in a double arm mixer. The Stearyl alcohol, Glyceryl hydroxystearate, Isostearic acid, and Glycerol triacetate were heated to about 185° F. until melted, and the PVP/VA copolymer was added. The temperature of the mixture was increased to approximately 285° F. until the PVP/VA copolymer was completely dissolved, and the Polyox was stirred into the mixture. The material was subsequently poured onto release paper and pressed. The material was then tested for performance.
In Examples F-H, the shaving aid material was formed from an erodable medium (Stearyl alcohol), water-soluble shaving aid (Polyox coagulant), Polyderm PPI-CO-200, Triacetin, and Macadamia nut oil in the percentages provided below in Table 4.
The materials for the shaving aid material in Examples F-H were processed in a double arm mixer. The Stearyl alcohol, polyderm, and triacetin were heated to about 165° F. The Polyox and macadamia nut oil were subsequently stirred into the mixture, and the temperature was raised to 185° F. As the mixing continued, the material thickened and much of the Polyox dissolved.
In Example I, a shaving aid material comprising 50% stearyl alcohol and 50% PEO was mixed. In Example J, a shaving aid material comprising 50% stearic acid, and 50% PEO coagulant was mixed. In both examples, the shaving aid materials were injection molded at temperatures at a maximum temperature of 80° C. and a pressure of 36,000.
In Example K, the shaving aid material was formed from an erodable medium (Stearyl alcohol, Glyceryl hydroxystearate), water-soluble shaving aid (Polyox coagulant), Isostearic acid, Glycerol triacetate, and PVP/VA copolymer in the percentages provided below in Table 5.
In Example K, the shaving aid materials were mixed and injection molded at temperatures in the range of about 140° F.-160° F.
In Example L, a shaving aid material was prepared comprising 25% stearyl alcohol, 61% C20-40 pareth-40 (Performathox 480 from New Phase Technology) and 15% Polyox coagulant was prepared by melting the mixture to about 90° C. and pouring into a mold.
In Examples M and N, the following ingredients were heated, mixed and injection molded into shaving strips:
Example O was was extruded which contained 85% of a commercial mixture of disodium lauryl sulfosuccinate, sodium cocoyl isethionate, cetearyl alcohol, triticum vulgare (wheat) starch, glyceryl stearate, paraffin, titanium dioxide (Zetasap ST 5251 from Zschimmer & Schwarz) and 15% PEO coagulant.
Although this invention has been shown and described with respect to the detailed embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail thereof may be made without departing from the spirit and scope of the invention.
This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/034,633, filed on Mar. 7, 2008, the contents of which are incorporated by reference herein in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61034633 | Mar 2008 | US |
