NZ296324A - Skin engaging member for razor blade cartridge assembly containing shaving aid - Google Patents

Abstract

This invention relates to an improved skin engaging member (64) for use in razor blade cartridge assemblies and shaving systems of the wet shave type. In accordance with one aspect of the invention, there is provided a two-component, control-release shaving device consisting of (a) a sheath layer (72) made from thermoplastic resins with openings therein and (b) a core region (70) containing internal shaving aids. Potentially, the device can maintain surface appearance, control-release the shaving aids, minimize the degradation of the shaving aids, and prevent the shaving aids from being trapped in a strip. Furthermore, the addition of low-melt additives to the shaving aids becomes feasible and the compatibility between the shaving aids and the shaving aid carrier such as polystyrene in the lubricating strip composite becomes less critical.

Description

New Zealand No. 296324 International No. PCT/US95/13713 TO BE ENTERED AFTER ACCEPTANCE AND PUBLICATION Priority dates: 31.10.1994;30.06.1995; Complete Specification Filed: 24.10.1995 Classification:(6) B26B21/44 Publication date: 24 September 1998 Journal No.: 1432 new zealand patents act 1953 COMPLETE SPECIFICATION Title of Invention: Skin engaging member Name, address and nationality of applicant(s) as in international application form: THE GILLETTE COMPANY, Prudential Tower Building, 800 Boylston Street, Boston, Massachusetts 02199, United States of America 29 6 ? 2 4 O 96/13360 PCT/US95/13713 - 1 SKIN ENGAGING MEMBER This invention relates to an improved skin engaging member for use in razor blade cartridge assemblies and shaving systems of the 5 wet shave type. The present invention resides broadly in providing the skin engaging cap and/or guard surfaces with configurations which deliver a shaving aid as the razor is dragged across the skin. Suitable shaving aids include 10 lubricants, whisker softeners, razor cleaners, medicinal agents, cosmetic agents or combinations thereof. This invention also relates to a novel method of manufacturing the skin engaging member of the present invention. 15 In shaving systems of the wet shave type, factors such as the frictional drag of the razor across the skin, the force needed to sever hairs, and irritation of pre-existing skin damage can create a degree of shaving 2 0 discomfort. Discomfort, and other problems accompanying wet shaving systems, can be alleviated by the application of shaving aids to the skin. Shaving aids may be applied prior to, during, or after Bhaving. A number of problems 25 accompany the use of pre- and post-applied shaving aids. Pre-applied-shaving aids can evaporate or can be carried away from the site 29 6 3 of application by repeated strokes of the razor. Post-applied-shaving aids are not present on the skin during shaving and thus their application may be too late to prevent an unwanted affect.

Both pre-applied and post-applied shaving aids add additional steps to the shaving process.

Proposals have been made to incorporate a shaving aid, e.g. lubricant, whisker softener, razor cleanser, medicinal 10 agent, cosmetic agent or combination thereof, into a razor, e.g. by depositing a shaving aid in a recess on the razor, by incorporating a shaving aid directly into one or more molded polymeric components o£ the razor, by adhesively 15 securing a shaving aid composite to the razor, and by use of a mechanical connection between a shaving aid composite and the razor. A water-soluble shaving aid, e.g. polyethylene oxide, has been mixed with water insoluble matrix 20 material, e.g., a polystyrene polymer, to form an insoluble polymer/soluble shaving aid composite as in U.S. Patent Nos. 4,170,821 to Booth and 5,113,585 to Rogers. The composite has been mounted on razor and shaving cartridge 25 structures, adjacent the shaving edge or edges, of single or multiple blade shaving systems.

Upon exposure to water, the water-soluble shaving aid leaches from the composite onto the skin. These composites tend to release large 30 amounts of shaving aid in the first few shaves and dramatically less shaving aid in subsequent Bhaves. Furthermore, extruded composites with relatively large amounts of shaving aid (up to 80% by weight) and relatively low amounts of 3 5 water insoluble matrix material (as lit'tle as 20% by weight) are relatively weak and have a tendency towards mechanical failure, amended sheet ipea/ep 29632 both in assembly and in use. Increased mechanical strength can be obtained with increased amounts of the insoluble matrix material. However, such increase reduces the 5 releasability of the shaving aid material.

Commercial lubricating strips, especially those with high levels of polyethylene oxide lubricant, like those described in U.S. Patent Nob. 4,170,821 to Booth 10 and 5,113,585 to Rogers, tend to deteriorate after use. Leach rate varies during the course of shaving and typically about 50% of the polyethylene oxide is trapped in the strip. The selection of the polyethylene oxide carrier 15 (i.e., the non-water soluble matrix material) is limited to a carrier that has a low melting or softening temperature and is at least, partially miscible with polyethyleneoxide. In addition, because the strip is made at a high temperature 20 of approximately 180°C., additives such as. fragrances and plasticizera are- difficult to incorporate in the strips.

U.S. Patent No. 4,872,263 to: Etheredge, XII, issued.October 10,-1989, 25 discloses a lubricating device comprised of a porous matrix impregnated with a particular acid soap. The impregnated matrix is covered with a water insoluble perforated sheet material in an effort to prevent the lubricant from eroding too 3 0 quickly and to provide a smooth "massaging11 effect on the skin. These lubricating devices have not met with commercial success. These lubricating devices are expensive to manufacture due to the additional assembly required of the 35 sheet-over-matrix design. They also tend to swell and delaminate when affixed to the razor cartridge with glue. Furthermore, the soft amended sheet ipea/ep porous matrix does not lend itself to economical mechanical means of affofing the* strip to the razor cartridgs.

The object of the present invention is to provide a system that overcomes at least some uf the above disadvantages or at least provides the public with a useful choice.

We have demonstrated that it is 5 feasible to produce a two-component, controlled-release shaving device consisting of an outer surface layer with, openings and an internal shaving aid-containing layer. The potential advantages tof using the device are to 1) maintain a uniform surface appearance, 2) achieve near zero-order release profile of the shaving aid after 1-4 shaves, 3) minimize material degradation, 4) minimize shaving aid material trapped in the device, 5) provide a 15 shaving aid device which is easy to manufacture and/or 6) to provide a shaving aid device which is easily integrated with a razor cartridge system. These and other objects of the present invention will be evident from the following. 2 0 In accordance with one aspect of the invention, there is provided a two-component, controlled-release skin engaging member consisting of (a) a sheath made from thermoplastic resins with openings therein and (b) a core 25 containing shaving aids. The skin engaging member can be in the form of a strip, a razor guard, a razor cap, a razor platform or a razor housing made (1) by coextrusion or two-color (i.e. two component) molding, or (2) by extrud-30 ing or molding the surface layer and shaving aids separately and then assembly later. Potentially, the device can maintain surface appear-ranee, control-release the shaving aid, minimize the degradation of the shaving aid, and prevent 35 the shaving aid from being trapped in the skin engaging member. Furthermore, the addition of low-melt additives to the shaving aid becomes 296324 feasible and the compatibility between the shaving aid and the shaving aid carrier, such as polystyrene in the lubricating strip composite, becomes less critical.

FIG. 1 is a perspective view o£ a razor unit in accordance with the invention; FIG. 2 is a sectional view taken along the line 2-2 of FIG. 1> FIG. 3 is a sectional view of another 10 razor unit in accordance with the present invention; FIG. 4 is an enlarged perspective view of a skin engaging member of the present invention; FIG. 5 is sectional view taken along the line 5-5 of FIG. 4; FIG. 6 is a sectional view of the skin engaging member 42 found in FIG. 2; FIG. 7 is a schematic cross-section 20 diagram of an extrusion die suitable for manufacturing the skin engaging member of FIG. 3; FIGS. 8-11 are enlarged perspective views of alternate skin engaging members 25 according to the present invention; FIG. 12 is a plot of shaving aid release versus the number of theoretical shaves, comparing a conventional lubricating strip with a lubricating strip according to the present 30 invention.

Referring to the drawings, the Bhaving unit 10 shown in FIGS. 1 and 2 includes base or platform member 12 molded of high impact polystyrene that includes integral coupling 35 groove structure 14 for attachment to a razor handle and guard structure 16 that defines a transversely extending anterior skin engaging amended sheet ipea/ep 2963 2 surface 18. On the upper surface of platform 12 are disposed steel leading blade 20 having a sharpened edge 22/ steel following blade 24 having sharpened edge 26, and aluminum spacer 5 member 28 that maintains blades 20 and 24 in spaced relation. Cap member 30 is molded of high impact polystyrene and has body portion 32 that defines the posterior skin engaging surface 34 that extends transversely between forwardly 10 projecting end walls 36 and has a front edge 38 that is disposed rearwardly of blade edge 26. Integral rivet portions 40 extend downwardly from transversely extending body portion 32 and pass through holes in blades 20 and 24, spacer 15 28, and platform 12 to secure cap 30, blades 20, 24 and spacer 28 on platform 12. Adhesively affixed to skin engaging surface 34 is skin engaging member 42.

The shaving unit 50 shown in FIG. 3 is 20 of the type shown in Jacobson U.S. Patent 4,586,255, incorporated herein by reference, and includes body 52 with front portion 54 and rear portion 56. Resiliently secured in body 52 are guard member 58, leading blade unit 60 and 25 trailing blade unit 62. A shaving aid composite in the form of elongated insert member 64 is frictionally locked in opening 66 of rear portion 56.

FIGS. 4-6 and 8-11 generally depict 30 variations on the present invention. As used herein, the term "core" refers to an internal portion of a skin engaging member as examined at the cross-section. The core typically runs throughout the skin engaging member along an 35 axis. The axis need not be the central axis.

The FIGS, designate the core as 70. Embodiments of the present invention have at least one core. amended sheet ipea/ep 7 - As used herein, the term "sheath" refers to an outer coating layer (s) over the core 70. The FIGS, designate the sheath as 72.

The two-component, controlled-release 5 skin engaging member of the present invention consists of an outer sheath which surrounds an internal core, wherein said core contains shaving aid such as water soluble polymers and additives. The skin engaging surface 74 can be 10 an insoluble layer with built-in openings, or a soft layer such as a commercial strip (polyethylene oxide/polystyrene) which will become porous during use.

Referring again to the drawings, and 15 in particular to FIGS. 3-5, there is shown an elongated skin engaging member 64. The member 64 has a skin engaging surface 74 and an elongated insert member 76. The insert member 76 is designed to frictionally lock in an 20 opening 66 as shown in FIG. 3. The skin . engaging member further comprises a shaving aid-containing core 70 which is surrounded by a sheath 72. The sheath includes at. least one opening to release shaving: aid. to. the skin. 25 Preferably, the sheath includes from about 3 to about 30 holes> most preferably 10-15 holes, evenly distributed along the skin engaging surface 74. Hole diameters vary depending on the particular shaving aid selected: however, 30 we have observed best results with hole diameters of from about 0.D20 to about 0.040 inches. Preferably, the hole diameter is about 0.035 inches. It should be noted that the holes need not be circular in shape and that 35 any shape hole would suffice. See for example FIGS. 7-11. The hole area along amended sheet :?ea/ep O n Q r, t : £ ^ 0 0 L 4 the skin engaging surface is important.

Preferably, the hole area is from about 0.0005 to about 0.0250 square inches. When a high level of polyethylene oxide lubricant is 5 utilized in the core, a hole area of about 0.0125 square inches is preferred. Many shaving aids tend to swell upon contact with water. By binding these swelling shaving aids within an insoluble matrix material, the degree of swell 10 can be modified to prevent aesthetically unpleasant results. The most preferred hole pattern is found in FIGS. 4-5.

The shaving aid is selected from the group consisting of polyethylene oxide, polyvinyl pyrrolidone, polyacrylamide, hydroxypropyl cellulose; polyvinyl imidazoline, polyethylene glycol, poly vinyl alcohol,. polyhydroxyethylmethacrylate, silicone copolymers, sucrose stearate,- vitamin E, soaps, 20 surfactants, panthenol, aloe, plasticizers, such as polyethylene glycol; beard softeners; additional lubricants, such as silicone oil, Teflon® polytetrafluoroethylene powders (manufactured by DuPont)-, and waxes; essential 25 oils such as menthol, camphor, eugenol, eucalyptol, safrol and methyl salicylate; tackifiers such as Hercules Regalrez 1094 and 1126; non-volatile cooling agents, inclusion complexes of skin-soothing agents with 30 cyclodextrins; fragrances; antipruritic/counterirritant materials; antimicrobial/keratolytic materials such as Resorcinol; anti-inflammatory agents such as Candilla wax and glycyrrhetinic acid; astringeixts such as zinc sulfate; surfactants such as pluronic and iconol materials; compatibilizers such as styrene-b-EO copolymers; *.v?fnd5d sheet 296 and combinations thereof. These shaving aids may release from the surface to provide improved shaving. These components can be dispersed throughout the core and, additionally, the outer 5 sheath may also contain small amounts of these shaving aids.

Preferably, said shaving aid is a water soluble or water miscible material; however, non-water soluble additives can also be 10 incorporated as long as they can be carried out with a water soluble core component.

The preferred shaving aid will comprise a lubricious water-soluble polymer.

Such water-soluble polymer will preferably 15 comprise at least 50%, more preferably at least 60%, by weight of the core. The more preferred water-soluble polymers are the polyethylene oxides generally known as POLYOX (available from Union Carbide Corporation) or ALXOX (available 20 from Meisei Chemical Works, Kyoto, Japan) .

These polyethylene oxides will preferably have molecular weights of about 100,000 to 6 million, most preferably about 300,000 to 5 million. The most preferred polyethylene oxide comprises a 25 blend of about 40 to 80% of polyethylene oxide having an average molecular weight of about 5 million (e.g. POLYOX COAGULANT) and about 60 to 20% of polyethylene oxide having an average molecular weight of about 300,000 (e.g. POLYOX 30 WSR-N-750) . The polyethylene oxide blend may also advantageously contain up to about 10% by weight of a low molecular weight (i.e.

MW<10,000) polyethylene glycol Buch as PEG-100.

The shaving aid may also advantageous-35 ly comprise a non-volatile cooling agent or an inclusion complex of a skin-soothing agent with amended sheet |c:r^jrD ■ ?q r 9 - 10 - ~ a cyclodextrin, preferably in amounts up to about 25%, most preferably 10 to 20%, by weight of the core.

By non-volatile cooling agent is meant 5 an agent which has a physiological cooling effect on the skin and which is appreciably less volatile than menthol. Preferably, the nonvolatile cooling agent will be one which when subjected to thermogravimetric analysis (e.g. 10 using a 951 Thermogravimetric Analyzer from Dupont with a 20°C. temperature rise per minute) will retain at least 50% o£ its initial weight at a temperature of 160°C., more preferably at least 80% of its initial weight at a temperature 15 of 160°C., and most preferably at least 50% of its initial weight at a temperature of 175°C.

Suitable cooling agents which can be utilized include non-volatile menthol analogs such aB menthyl lactate, menthyl ethoxyacetate, 20 menthone glycerinacetal, 3-/-menthoxypropane-l,2-diol, ethyl /-menthyl carbonate, (IS,3S,4R)-p-menth-8-en-3-ol, menthyl pyrrolidone carboxylate, N-substituted-p-menthane^3---carboxamides (as described in U.S. 4,136,163, 25 which is incorporated herein by reference) including, for example, N-ethyl-p-xnenthane-3-carboxamide, acyclic carboxamides of the formula R1 2 1 RJ C* CONR'R" where R' and R", when taken separately, are each hydrogen, C^-Cg alkyl or C^-Cg hydroxyalkyl and 35 provide a total of no more than 8 carbon atoms, with the proviso that when R' is hydrogen R" may AMENDED SHEET ic.r.1 'CO t . 2963 also be alkylcarboxyalkyl of up to 6 carbon atoms; A' and R", when taken together, represent an alkylene group of up to 6 carbon atoms thereby forming a nitrogen heterocycle, the alkylene chain being optionally interrupted by oxygen; R3 is hydrogen or C^-Cg alkyl; and R2 and R3 ara each alkyl (such acyclic carboxamides being described in U.S. 4,153,679, which is incorporated herein by reference) including, for example, N, 2,3-trimethyl-2-isopropylbutanamide, and ketal coolants (as described in WO 93/23005, which is incorporated herein by reference) including, for example, /-menthon-/d-isomenthon glycerin ketal.

Suitable skin-soothing agents which can be utilized in the cyclodextrin inclusion complex include menthol, camphor, eugenol, eucalyptol, safrol, methyl salicylate, and the aforedescribed menthol analogs. Any suitable cyclodextrin may be utilized to form the inclusion complex including alpha-cyclodextrin, beta-cyclodextrin, gamma - cyclodextrin and modified cyclodextrins such as hydroxypropyl-beta-cyclodextrin, methyl-beta-cyclodextrin, and acetyl-beta-cyclodextrin. The preferred cyclodextrins are beta-cyclodextrin and gamma-cyclodextrin.

When the shaving aid comprises a cyclodextrin inclusion complex, the core may also advantageously comprise up to about 10%, preferably about 2 to 7%, by weight of a displacing agent which displaces the skin-soothing agent from the inclusion complex upon contact with water, thereby enhancing the release of the skin-soothing agent from the core material during use. The displacing agent is a material which is capable of forming a more amended sheet mr a /rrr» 296 stable complex witb the cyclodextrin than the complex formed with the skin-soothing agent and, thus, displaces the skin-soothing agent from the complex when the shaving aid is contacted with 5 water. Suitable displacing agents include surfactants, benzoic acids, and certain amines (e.g. urea).

Further details with respect to the aforementioned cooling agents, cyclodextrin 10 inclusion complexes and displacing agents may be found in the following U.S. patent applications No. 08/496,860 entitled Shaving Aid Composite With An Inclusion Complex Of A Skin-Soothing Agent And A Cyclodextrin, filed on June 30, 15 1995; and No. 08/497,193 entitled Shaving Aid Composite With A Non-Volatile Cooling Agent, filed on June 30, 1995.

The core includes from about 0% to about 50% by weight, preferably from 0% to about 20 20%, of a water-insoluble matrix material and from about 50% to about 100% by weight, preferably from about 80% to about 100%,- of the shaving aid. Suitable water-insoluble polymers for the matrix include, for example, nylon, 25 ethylene vinyl acetate (EVA), polyethylene, polypropylene, polyurethane, polystyrene, polystyrene-butadiene, polyacetal, polyphenol/polystyrene blends (such as NOREL brand polymer), and combinations thereof. 3 0 The sheath must have sufficient mechanical strength and rigidity to provide adequate mechanical strength to the entire skin engaging member, both as initially produced and after a significant amount of water soluble 3 5 material has ' been leached out of the amended sheet ipea/ep - skin engaging member. Preferably the sheath will comprise at least 35%, most preferably at least 40%, by weight of a water-insoluble polymer, particularly a thermoplastic resin.

Thermoplastic resins suitable for use in the sheath include polystyrene, high impact polystyrene (polystyrene-butadiene), polypropylene, filled polypropylene, polyethylene, nylon, ethylene vinyl acetate and 10 blends such as 70% nylon/30% polyethylene oxide, 60% polystyrene/40% polyethylene oxide. The preferred resins are high impact polystyrene, polystyrene, ethylene vinyl acetate (EVA) and combinations thereof. In addition to the water-15 insoluble polymer, the sheath may also comprise some water-soluble polymer, such as polyethylene oxide, but generally no more than about 65% by weight, preferably less than 60% by weight, in order to maintain the structural integrity of 20 the sheath. Optionally, the sheath can include additives such as lubricants or plas&icizers, fillers such as CaC03» and colorants such as Ti02.

In one embodiment of the present 25 invention a wear indicating effect is produced when the sheath and the core are made of disparately colored materials (e.g. white colored sheath and blue colored core). The core leaches out of the skin engaging member 30 through use. With sufficient use, a colored region within the core leaches out. By examining the release holes along the skin engaging surface, the user is provided with an indication that the shaving unit and/or skin 35 engaging surface have reached their effective life. In a preferred embodiment, the core amended sheet . —— f /CD ^063 2 4 consists of polyethylene oxide/polystyrene blend which is colored with Indigotine, FD&C #2 dye and the sheath consists of nylon and/or polystyrene which has been colored white.

According to the present invention, the skin engaging members may be affixed by adhesive such as Loctite Super Bonder 499, by mechanical locking mechanism, by thermal welds or by a combination thereof. 10 The skin engaging member can be a strip made by two-color (two-component) molding or coextruding, or by extruding or molding the surface layer and the shaving aids separately and then assembly later. The skin engaging 15 member can then be glued or snapped onto a razor cartridge. The skin engaging member can also be a razor cap, platform, or housing made by two-color molding. For example, 1) a surface with holes can be made by molding or two-color 20 molding, and 2) a surface with channels cam be made by molding. Extrusion and coextrusion processes are preferred as they require less capital and skilled labor. When the skin engaging member is coextruded, holes must be 25 made in the skin engaging surface. The holes are placed in the sheath by any of the following processes: drilling, laser, water jet, embossing or puncturing. The core and the sheath should be processed at different barrel 3 0 temperatures to minimize material degradation. To easily incorporate functional additives including liquids and powders into the core, a twin-screw extruder should be considered as an alternative to the single-screw extruder used in 35 the extrusion and coextrusion processes. Optimally the sheath will have a hard to moderately hard surface. amended sheet 1 fc.-r- /j^p 296324 The preferred skin engaging member is produced by a coextrusion process -whereby a sheath is present on at least the skin engaging surface 74. The nature and relative portions of the 5 sheath and core polymeric materials are such that the skin engaging member has adequate mechanical strength, both as initially produced and after a significant amount of water soluble material has been leached out, the quantity o£ the water-10 soluble material being sufficient to provide effective shaving assistance, such as lubrication, for the entire expected life of the blade or blades. The function of the sheath is not only to provide additional rigidity but to meter the 15 shaving aid. In conventional skin engaging members, Buch as those described din. U.S. Pat. Nos. 5,063,667; 5,095,619; and 5,113,585, a significant amount of shaving aid is trapped within the insoluble matrix. By increasing the shaving aid 20 concentration in the core, diffusion is increased and more efficient delivery is achieved. Furthermore, if an insoluble matrix is "added to the core, it also provides some additional mechanical strength.

Figure 7 is a schematic cross section diagram down the length of a two-component extruder (or coextruder) suitable for manufacturing the skin engaging member of the present invention. Core material 80 is fed into the intrusion die 81 by sua 30 extrusion screw, hot melt or other suitable means. In the core inlet port 82 the tight core orifice 83 encounters the sheath material 86, which has been fed into sheath inlet port 84, wherein the core becomes encapsulated by the sheath material when 35 viewed in a transverse cross section to the flow of the die material. The encapsulated core then proceeds to the die outlet 85 wherein the AMENDED SHEET ipea/ep 29 C continuous skin engaging members can be cured and/or drawn down to provide the appropriate dimensions. For general discussion of coextrusion technology see Levi, Plastics Extrusion Technology Handbook. Industrial Press Inc., pages 168-188 (1981). After the continuous skin engaging members are produced, the strand is sent for further processing where it is typically drawn down to the correct size and cut to length suitable for implant into the body of a razor blade cartridge. This cutting can be achieved by knife edge cutting, lasers or water jet. The Bkin engaging surfaces of the present invention typically are rectangular in shape with a width of fr-jm about 0.05 inches to about 0.1 inches and a length of about 1.2 inches.

The two-component extruder allows the core material to be processed at a relatively low temperature to reduce material degradation. For example, polyethylene oxide can be processed at a temperature lower than that required by conventional strips, i.e. polyethylene oxide in insoluble matrix lubricating strips. Shaving aids can be made from water soluble polymers such as polyethylene oxide, polyethylene glycol, and polyvinyl alcohol, etc. Additives such as perfume, moisturizers, Vitamin E, and plasticizers etc. can easily be added to the shaving aid. Additives can also be water-insoluble materials as long as they can be carried out through the surface openings. The core containing shaving aid can be molded or extruded, although the extrusion process is preferred.

Leach rates of the shaving aids depend on the thickness of the surface, the number and the shape of the openings, and the surface amended sheet IPEA/EP 296 » • 17 structures (porous or non-porous). The surface layer can also he made to be removable so that the shaving aids can be added to the device during use. embodiments to be part of the present invention. For example, non-rectangular skin engaging surface areas may be utilized (such as ovals) and non-flat surface patterns could be utilized.

These and other equivalent embodiments are also contemplated by the present invention. The present invention and the manner of making and using the same should be evident from the following examples.

EXAMPLES 1-8 layer) such as those found in Table 1 are co-extruded into a device with a cross-section as in Figure 7 at approximately the temperatures 20 found in the table. Typical finished width is 1/8 of an inch after a draw down of less than 2%. These devices require no additional assembly. The coextrusion line includes two 3/4" HBI Systems 90 extruders (mfg. by Haake), 25 and a coextrusion die. The sheath or outer layer of the coextruded skin engaging member was made from a mixture at barrel temperature as shown and the core containing shaving aid was made from the material shown. The hole pattern 3 0 is cut with a 0.030 inch diameter drill in the pattern of FIG 4. The finished strips are cut 1.25 inches long with a knife edge cutter resulting in 13 holes per strip.

Applicant considers equivalent Core containing shaving aid (inner Typical Processing Conditions Temperature (C): zone Extruder 1 (inner) Extruder 2 (outer) Rotor Speed: Extruder 1 Extruder 2 Line Speed: 1.

Outer layer Inner layer 2.

Outer Layer 130 150 42 RPM 48 RPM 180 180 180 180 180 180 180 approximately 15 to 20 ft/min Table 1 50% 40% % 88% % 2% high impact polystyrene (Mobil 4324) polyethylene oxide blend: 3 parts POLYOX WSR Coagulant (MW 5,000,000) 2 part POLYOX WSR N-750 (MW 300,000) (Both mfg by Union CarbS.de Corp. Danbury, CT) Polyethylene Glycol MW=4500 (Dow 4500) polyethylene oxide blend: 3 parts POLYOX WSR Coagulant (MW 5,000,000) 2 part POLYOX WSR N-750 (MW 300,000) (Both mfg by Union Carbide Corp. Danbury, CT) Polyethylene Glycol MW=4500 (Dow 4500) Green colorant 40% high impact polystyrene (Mobil 4324) 50% polyethylene oxide blend: 3 parts POLYOX WSR Coagulant (MW 5,000,000) Inner layer Table 1 (cont.) 2 part POLYOX WSR N-750 (MW 300,000) (Both mfg by Union Carbide Corp. Danbury, CT) 10% Polyethylene Glycol MW=4500 (Dow 4500) 88% polyethylene oxide blend: 3 parts POLYOX WSR Coagulant (MW 5,000,000) 2 part POLYOX WSR N-750 (MW 300,000) (Both mfg by Union Carbide Corp. Danbury, CT) 10% Polyethylene Glycol MW=4500 (Dow 4500) 2% Green colorant V© 9\ W U) © Outer layer Inner layer Outer layer Inner layer 37% high impact polystyrene (Mobil 4324) 53% polyethylene oxide blend: 3 parts POLYOX WSR Coagulant (MW 5,000,000) 2 part POLYOX WSR N-750 (MW 300,000) (Both mfg by Union Carbide Corp. Danbury, CT) 10% Polyethylene Glycol MW=4500 (Dow 4500) 90% polyethylene oxide blend: 3 parts POLYOX WSR Coagulant (MW 5,000,000) 2 part POLYOX WSR N-750 (MW 300,000) (Both mfg by Union Carbide Corp. Danbury, CT) 10% Polyethylene Glycol MW=4500 (Dow 4500) % high impact polystyrene (Mobil 4324) 50% polyethylene oxide blend: 3 parts POLYOX WSR Coagulant (MW 5,000,000) 2 part POLYOX WSR N-750 (MW 300,000) (Both mfg by Union Carbide Corp. Danbury, CT) 8% Polyethylene Glycol MW=4500 (Dow 4500) 7% Salsorb 88, cross-linked sodium polyacrylates 88% polyethylene oxide blend: 3 parts POLYOX WSR Coagulant (MW 5,000,000) 2 part POLYOX WSR N-750 (MW 300,000) (Both mfg by Union Carbide Corp. Danbury, CT) ID I (Allied) 13 |ro VO t/l I—* w -J u CM • 9 % 2% Table 1 (cont.) Polyethylene Glycol MW=4500 (Dow 4500) Green colorant SO C\ 1-* w U) C\ o Outer layer Inner layer Outer layer Inner layer 33% high impact polystyrene (Mobil 4324) 56% polyethylene oxide blend: 3 parts POLYOX WSR Coagulant (MW 5,000,000) 2 part POLYOX WSR N-750 (MW 300,000) (Both mfg by Union Carbide Corp. Danbury, CT) 7% Polyethylene Glycol MW=4500 (Dow 4500) 4% Salsorb 88, cross-linked sodium polyacrylates 90% polyethylene oxide blend: 3 parts POLYOX WSR Coagulant (MW 5,000,000) 2 part POLYOX WSR N-750 (MW 300,000) (Both mfg by Union Carbide Corp. Danbury, CT) 10% Polyethylene Glycol MW=4500 (Dow 4500) 40% high impact polystyrene (Mobil 4324) 50% polyethylene oxide blend: 3 parts POLYOX WSR Coagulant (MW 5.000,000) 2 part POLYOX WSR N-750 (MW 300,uOO) (Both mfg by Union Carbide Corp. Danbury, CT) 10% Polyethylene Glycol MW=4500 (Dow 4500) 73% polyethylene oxide blend: 3 parts POLYOX WSR Coagulant (MW 5,000,000) 2 part POLYOX WSR N-750 (MW 300,000) (Both mfg by Union Carbide Corp. Danbury, CT) 10% Polyethylene Glycol MW=4500 (Dow 4500) 15% Menthone glycerinacetal (Frescolat MGA) 2% Green colorant (Allied) O 1 vo u Outer layer Inner layer Outer layer Inner layer Table 1 (cont.) 40% high impact polystyrene (Mobil 4324) 50% polyethylene oxide blend: 3 parts POLYOX WSR Coagulant (MW 5,000,000) 2 part POLYOX WSR N-750 (MW 300,000) (Both mfg by Union Carbide Corp. Danbury, CT) 10% Polyethylene Glycol MW=4500 (Dow 4500) 78% polyethylene oxide blend: 3 parts POLYOX WSR Coagulant (MW 5,000,000) 2 part POLYOX WSR N-750 (MW 300,000) (Both mfg by Union Carbide Corp. Danbury, CT) 10% Polyethylene Glycol MW=4500 (Dow 4500) 10% N-ethyl-p-menthane-3-earboxamide (WS-3) 2% Green colorant 40% high impact polystyrene (Mobil 4324) 50% polyethylene oxide blend: 3 parts POLYOX WSR Coagulant (MW 5,000,000) 2 part POLYOX WSR N-750 (MW 300,000) (Both mfg by Union Carbide Corp. Danbury, CT) 10% Polyethylene Glycol MW=4500 (Dow 4500) 73% polyethylene oxide blend: 3 parts POLYOX WSR Coagulant (MW 5,000,000) 2 part POLYOX WSR N-750 (MW 300,000) (Both mfg by Union Carbide Corp. Danbury, CT) 10% Polyethylene Glycol MW=4500 (Dow 4500) 15% 7-cyclodextrin/menthol inclusion complex 2% Green colorant EXAMPLES 9 ft 10 Control: A conventional lubricating strip, similar in external dimensions to FIGS. 4-5, was prepared according to the general method described in US Pat. No. 5,113,585 to Rogers, The formulation for the strip is as follows: 9. 33.5% 55^ % 1.5% high impact polystyrene (Mobil 4324) polyethylene oxide blend: 3 parts POLYOX WSR Coagulant (MW 5,000,000) 2 part POLYOX WSR N-750 (MW 300,000) (Both mfg by Union Carbide Corp. Danbury, CT) Polyethylene Glycol MW=4500 (Dow 4500) Misc. additives and colorants m ■— 2 -u 0 mo> x m Present Invention: A lubricating strip according to the present invention was prepared according to the « general method described :J.n Examples 1-8. The formulation for the strip is as follows: k> .

Outer layer 33.5% 55% % 1.5% high impact polystyrene (Mobil 4324) polyethylene oxide blend: 3 parts POLYOX WSR Coagulant (MW 5,000,000) 2 part POLYOX WSR N-750 (MW 300,000) (Both mfg by Union Carbide Corp. Danbury, CT) Polyethylene Glycol MW=4500 (Dow 4500) Misc. additives and colorants KJ Inner layer 85% polyethylene oxide blend: 3 parts POLYOX WSR Coagulant (MW 5,000,000) ro > # V© C\ EXAMPLES 9 & 10 (cont.) jjj C\ o 2 part POLYOX WSR N-750 (MW 300,000) (Both mfg by Union Carbide Corp. Danbury, CT) 5% Polyvinyl alcohol 8% Polyethylene Glycol MW=4500 (Dow 4500) 2% Misc. additives and colorants The weight loss (dry) of the cartridge was monitored over the course of several simulated in vitro shave tests. We believe that these in vitro tests correlate Well with average in vivo shaves. The results are plotted as FIG 12. The plot shows that in Example 10 therapeutic levels of Itibricant continue to be delivered in a near zero-order release profile after the fourth shave. However, very low levels are provided in i Example 9 (control). K u l q ro § <o vo I or> s Os( ro - 24 2963

Claims (16)

1. A skin engaging member for use in a wet shaving system comprising: an elongated sheath comprised of a 5 water insoluble polymer, said sheath having a skin engaging surface extending along an outer surface thereof, and a core extending axially throughout said sheath, said core containing a shaving aid 10 which comprises a water soluble polymer, wherein said sheath and core are extruded or molded and said sheath has at least one opening in said skin engaging surface through which said shaving aid is released during shaving. 15

2. The skin engaging member of claim 1, wherein said sheath comprises at least 35% water insoluble polymer and said core comprises at least 50% water soluble polymer.

3. The skin engaging member of claim 2, 20 wherein said water insoluble polymer comprises polystyrene, high impact polystyrene, polypropylene, filled polypropylene, polyethylene, nylon, or ethylene vinyl acetate.

4. The skin engaging member of claim 3, 25 wherein said core additionally comprises about 0 to 20% of water insoluble matrix.

5. The skin engaging member of claim 4, wherein said water insoluble matrix comprises nylon, ethylene vinyl acetate, polyethylene, 30 polypropylene, polyurethane, polystyrene, polystyrene-butadiene, polyacetal, or polyphenol/polystyrene blends.

6. The skin engaging member of claim 5, wherein said sheath additionally comprises less 35 than 60% of water soluble polymer.

7. The skin engaging member of claim 1, 2, 4, 5 or £, wherein said water soluble polymer amended sheet ipea/ep 296 3 24 comprises polyethylene oxide.

8. The skin engaging member of claim 3, wherein said water soluble polymer comprises polyethylene oxide. 5

9. The skin engaging member of claim 3 or 8, wherein said sheath and said core are disparately colored.

10. The skin engaging member of claim 8, wherein said at least one opening comprises a 10 plurality of openings with an area of about 0.0005 to about 0.0250 square inches.

11. The skin engaging member of claim 8, wherein said at least one opening comprises about 3 to about 30 holes having a diameter of 15 about 0.020 to about 0.040 inches.

12. The skin engaging member of claim 8, wherein said core comprises up to 25% by weight of a non-volatile cooling agent or an inclusion complex of a skin-soothing agent with a 20 cyclodextrin.

13. The skin engaging member of claim 12, wherein said non-volatile cooling agent is selected from menthyl lactate/ menthyl ethoxyacetate, menthone glycerinacetal, 3-1- 25 menthoxypropane-1,2-diol, ethyl /-menthyl carbonate, (IS, 3S, 4R) -p-menth-8-en-3-ol, menthyl pyrrolidone carboxylate, N-ethyl-p-menthane-3-carboxamide, and N,2,3-trimethyl-2-isopropylbutanamide and wherein said skin-30 soothing agent iB selected from menthol, camphor, eugenol, eucalyptol, safrol, methyl salicylate and the aforesaid non-volatile cooling agents.

14. The skin engaging member of claim 1, 35 wherein said shaving aid comprises polyethylene oxide, polyvinyl pyrrolidone, polyacrylamide, hydroxypropyl cellulose, polyvinyl imidazoline. =/w=u sheet 4 'trrr' - 26 - polyethylene glycol, polyvinyl alcohol, Q ^ polyhydroxyethylmethacrylate, silicone £» ^ copolymers/ sucrose stearate, vitamin E, soaps, surfactants, panthenol, aloe, plasticizer, beard 5 softeners, lubricants, polytetrafluoroethylene powders, waxes, menthol, eugenol, eucalyptol, safrol, methyl salicylate, tackifiers, nonvolatile cooling agentB, inclusion complexes of t • skin-soothing agents with cyclodextrins, 10 fragrances, antipruri tic/counter-irritant materials, antimicrobial/keratolytic materials, anti-inflammatory agents, astringents, or compatibilizers.

15. A wet shaving system comprising a 15 blade member and an external skin engaging member adjacent said blade member, said skin engaging member comprising: an elongated sheath comprising a water insoluble polymer, said shsath having a skin 20 engaging surface extending along an outer surface thereof, and a core extending axially throughout said sheath, said core containing a shaving aid which comprises a water soluble polymer, 25 wherein said sheath and core are extruded or molded and said sheath has at least one opening in said skin engaging surface through which said shaving aid is released during shaving.

16. The wet shaving system of claim 15, 3 0 wherein said skin engaging member is as defined in any one of claims 2 to 14. 1 7. A skin engaging member substantially as herein described with reference to . figures 4 and 5 or any one of figures 6, 8, 9, 10, or 11 of the accompanying /drawings. °\ Luf. >$18. A wet shaving system substantially as herein described with reference to figures 1, 2 and 6 or 2 in combination with any one of figures 4, 8, 9, 10 or 11 of ljj| the accompanying drawings. dZj 1 9. An extruder for manufacturing a skin engaging member substantially as herein described with reference to figure 7 of the accompanying drawings.