AU686480B2

AU686480B2 - Skin engaging member

Info

Publication number: AU686480B2
Application number: AU40092/95A
Authority: AU
Inventors: Frank E Badin; Lee K Lim; Thilivali T Ndou; Brian A Rogers; Mingchih Michael Tseng; Yuling Yin
Original assignee: Gillette Co LLC
Current assignee: Gillette Co LLC
Priority date: 1994-10-31
Filing date: 1995-10-24
Publication date: 1998-02-05
Anticipated expiration: 2015-10-24
Also published as: ES2132745T3; CN1167457A; MA23705A1; IL115690A; IL115690A0; TR199501342A2; CN1104312C; EG20594A; WO1996013360A1; PL180436B1; ATE178253T1; PL319976A1; AU4009295A; EP0790883B1; JP4011108B2; DE69508784D1; DE69508784T2; MX9703127A; JPH10507950A; BR9509453A

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

SKIN ENGAGING MEMBER This invention relates to an improved skin engaging member for use in razor blade cartridge assemblies and shaving systems of the 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 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. 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 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 shaving. A number of problems accompany the use of pre- and post-applied shaving aids. Pre-applied-shaving aids can evaporate or can be carried away from the site PC17US95/13713

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 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 of the razor, by adhesively 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 non-water-soluble 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 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 amounts of shaving aid in the first few shaves and dramatically less shaving aid in subsequent shaves. Furthermore, extruded composites with relatively large amounts of shaving agent material (up to 80% by weight) and relatively low amounts of water insoluble matrix material

(as little as 20% by weight) are relatively weak and have a tendency towards mechanical failure, 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 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 Nos. 4,170,821 to Booth 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 Polyox carrier (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 polyetheneoxide. In addition, because the strip is made at a high temperature of approximately 180°C, additives such as fragrances and plasticizers are difficult to incorporate in the strips.

U.S. Patent No. 4,872,263 to Etheredge, III, issued October 10, 1989, 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 quickly and to provide a smooth "massaging" 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 sheet-over-matrix design. They also tend to swell and delaminate when affixed to the razor cartridge with glue. Furthermore, the soft porous matrix does not lend itself to economical mechanical means of affixing the strip to the razor cartridge.

We have demonstrated that it is 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 of using the device are to 1) maintain a uniform surface appearance, 2) achieve near zero-order release of the shaving aid after 1-4 shaves, 3) minimize material degradation, 4) minimize shaving aid material trapped in the device, 5) provide a 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. In accordance with one aspect of the invention, there is provided a two-component, controlled-release shaving device consisting of (a) a sheath layer made from thermoplastic resins with openings therein and (b) a core region containing internal shaving aids. The device 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 extruding or molding the surface layer and shaving aids separately and then assembly later. 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 carrie, such as polystyrene in the lubricating strip composite, becomes less critical. FIG. 1 is a perspective view of 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 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 3-3 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 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 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 invention.

Referring to the drawings, the shaving unit 10 shown in FIGS. 1 and 2 includes base or platform member 12 molded of high impact polystyrene that includes integral coupling groove structure 14 for attachment to a razor handle and guard structure 16 that defines a transversely extending anterior skin engaging 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 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 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 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 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 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 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 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 element. As used herein, the term "sheath" refers to an outer coating layer(s) over the core material 70. The FIGS, designate sheaths as 72. The two-component, controlled-release shaving device of the present invention consists of an outer sheath which surrounds an internal core, wherein said core contains shaving aids such as water soluble polymers and additives. The skin engaging surface 74 can be 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 in particular to FIG. 3, there is shown an elongated skin engaging member 64. The member 64 has a skin engaging surface 74 and an elongated insert element 76. The insert member 76 is designed to frictionally lock in an opening as shown in FIG. 3. The skin engaging member further comprises a shaving aid- containing core material 70 which is surrounded by a sheath material. The sheath material includes at least one hole to release additive to the skin. 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, we have observed best results with hole diameters of from about 0.020 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 any shape hole would suffice. See for example FIGS. 7-11. The pore area along the skin engaging surface is important. Preferably, the pore area is from about 0.0005 to about 0.0250 square inches. When a high level of polyethylene oxide lubricant is utilized in the core, a pore 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 can be modified to prevent aesthetically unpleasant results. The most preferred hole pattern is found in FIGS. 4-5.

Shaving aid materials are selected from the group consisting of polyethylene oxide, polyvinyl pyrrolideone, polyacrylamide, hydroxypropyl cellulose, polyvinyl imidazoline, polyethylene glycol, poly vinyl alcohol, polyhydroxyethylmethacrylate, silicone copolymers, sucrose stearate, vitamin E, soaps, 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 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 cyclodextrins; fragrances; antipruritic/counterirritant materials; antimicrobial/keratolytic materials such as Resorcinol; anti-inflammatory agents such as Candilla wax and glycyrrhetinic acid; astringents such as zinc sulfate; surfactants such as pluronic and iconol materials; compatibilizers such as styrene-b-EO copolymers; 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 sheath may also contain small amounts of these shaving aids.

Preferably, said shaving aid is a water soluble or water iscible material; however, non-water soluble additives can also be 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 comprise at least 50%, more preferably at least 60%, by weight of the core material. The more preferred water-soluble polymers are the polyethylene oxides generally known as POLYOX (available from Union Carbide Corporation) or ALKOX (available 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 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 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 such as PEG-100. The shaving aid may also advantageous¬ ly comprise a non-volatile cooling agent or an inclusion complex of a skin-soothing agent with a cyclodextrin, preferably in amounts up to about 25%, most preferably 10 to 20%, by weight of the core material.

By non-volatile cooling agent is meant an agent which has a physiological cooling effect on the skin and which is appreciably less volatile than menthol. Preferably, the non¬ volatile cooling agent will be one which when subjected to thermogravimetric analysis (e.g. using a 951 Thermogravimetric Analyzer from

Dupont with a 20°C. temperature rise per minute) will retain at least 50% of its initial weight at a temperature of 160°C, more preferably at least 80% of its initial weight at a temperature 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 as menthyl lactate, menthyl ethoxyacetate, xnenthone 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, which is incorporated herein by reference) including, for example, N-ethyl-p-menthane-3- carboxamide, acyclic carboxamides of the formula

R¹

I R² C* CONR'R'

where R' and R", when taken separately, are each hydrogen, ^-Cg alkyl or C₁-C₈ hydroxyalkyl and provide a total of no more than 8 carbon atoms, with the proviso that when R' is hydrogen R" may also be alkylcarboxyalkyl of up to 6 carbon atoms; R' 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; R¹ is hydrogen or C-^-Cr_j alkyl; and R² and ^J are each C^-Cg 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 material 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 stable complex with 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 water. Suitable displacing agents include surfactants, benzoic acids, and certain amines (e.g. urea) .

Further details with respect to the aforementioned cooling agents, cyclodextrin inclusion complexes and displacing agents may be found in the following copending U.S. patent applications, the disclosures of which are incorporated herein by reference: Docket No. 7995 entitled Shaving Aid Composite With An Inclusion Complex Of A Skin-Soothing Agent And A Cyclodextrin, filed on June 30, 1995; and Docket No. 7996 entitled Shaving Aid Composite With A Non-Volatile Cooling Agent, filed on June 30, 1995. The core material includes from about

0% to about 50% by weight, preferably from 0% to about 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 material. Suitable water-insoluble matrix materials include, for example, nylon, ethylene vinyl acetate (EVA) , polyethylene, polypropylene, polyurethane, polystyrene, polystyrene-butadiene, polyacetal, polyphenol/polystyrene blends (such as NOREL brand polymer), and combinations thereof.

The sheath material 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 insoluble material has been leached out of the skin engaging member. Preferably the sheath region will comprise at least 35%, most preferably at least 40%, by weight of a water- insoluble polymer, particularly a thermoplastic resin. Sheath material suitable for use in the present invention include polystyrene, high impact polystyrene (polystyrene-butadiene) , polypropylene, filled polypropylene, polyethylene, nylon, and blends such as 70% nylon/30% polyethylene oxide, 60% polystyrene/40% polyethylene oxide. The preferred sheath materials are high impact polystyrene, polystyrene, ethylene vinyl acetate (EVA) and combinations thereof. In addition to the water-insoluble polymer, the sheath region 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 the sheath region. Optionally, the sheath material can include additives such as lubricants or plasticizers, fillers such as CaC0₃, and colorants such as τio₂. In one embodiment of the present invention a wear indicating effect is produced when the sheath material and the core material are made of disparately colored materials (e.g. white colored sheath and blue colored core) . The core material leaches out of the skin engaging member 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 engaging surface have reached their effective life. In a preferred embodiment, the core material consists of polyethylene oxide/polystyrene mixture which is white in color and the sheath consists of nylon and/or styrene which has been colored with Indigotine, FD&C #2 dye.

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.

The device 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 device can then be glued or snapped onto a razor cartridge. The device 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 molding, and 2) a surface with channels can be made by molding. Extrusion and coextrusion processes are preferred as they require less capital and skilled labor. When the strip is coextruded, holes must be 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. Shaving aids and the surface layer should be processed at different barrel temperatures to minimize material degradation. To easily incorporate functional additives including liquids and powders into shaving aids, a twin-screw extruder should be considered as an alternative to the single-screw extruder used in the extrusion and coextrusion processes.

Optimal sheath materials have a hard to moderately hard surface. 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 sheath and core polymeric materials being 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 of the water-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 material is not only to provide additional rigidity but to meter the shaving aid. In conventional skin engaging members, such as those described in U.S. Pat. Nos. 5,063,667; 5,095,619; and 5,113,585, a significant amount of shaving aid material is trapped within the insoluble matrix. By increasing the shaving aid concentration, diffusion is increased and more efficient delivery is achieved. Furthermore, if an insoluble matrix is added to the core material, it also provides some additional mechanical strength.

Figure 7 is a schematic cross section diagram down the length of an extruder suitable for manufacturing the skin engaging member of the present invention. Core material is fed into the intrusion die 51 by an extrusion screw, hot melt or other suitable means. In the core inlet port 52 the tight core orifice 53 encounters the sheath material wherein the core becomes encapsulated by the sheath material when viewed in a transverse cross section to the flow of the die material. The encapsulated core then proceeds to the die outlet 55 wherein the 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), incorporated herein by reference. 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 skin engaging surfaces of the present invention typically are rectangular in shape with a width of from about 0.05 inches to about 0.1 inches and a length of about 1.2 inches.

The two-component device allows shaving aids 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 aids. Additives can also be water- insoluble materials as long as they can be carried out through the surface openings. The shaving aids 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 structures (porous or non-porous) . The surface layer can also be made to be removable so that the shaving aids can be added to the device during use. Applicant considers equivalent 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

Shaving aids 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 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) , and a coextrusion die. The surface layer of the coextruded device was made from a mixture at barrel temperature as shown and the shaving aid was made from the material shown. The hole pattern 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. Typical Processing Conditions

Temperature (C) : zone 1 2 3 4 5

Extruder 1 (inner) 130 180 180 180 180

Extruder 2 (outer) 150 180 180 180 180

Rotor Speed: Extruder 1 42 RPM Extruder 2 48 RPM

Line Speed: approximately 15 to 20 ft/min

Table 1

00

Outer layer 50% high impact polystyrene (Mobil 4324) I 40% 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)

Inner layer 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

2. Outer Layer 40% high impact polystyrene (Mobil 4324) 50% polyethylene oxide blend:

3 parts POLYOX WSR Coagulant (MW 5,000,000)

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)

Inner layer 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

Outer 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) VO

Inner layer 90% polyethylene oxide blend: I

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)

Outer layer 35% 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 polyacrylateβ (Allied)

Inner layer 88% polyethylene oxide blend:

(Both mfg by Union Carbide Corp. Danbury, CT)

Table 1 (cont.)

10% Polyethylene Glycol MW=4500 (Dow 4500) 2% Green colorant

5. Outer 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 (Allied) Inner layer 90% polyethylene oxide blend:

3 parts POLYOX WSR Coagulant (MW 5,000,000)

10% Polyethylene Glycol MW=4500 (Dow 4500)

Outer layer 40% high impact polystyrene (Mobil 4324) w

50% polyethylene oxide blend:

3 parts POLYOX WSR Coagulant (MW 5,000,000) '

10% Polyethylene Glycol MW=4500 (Dow 4500)

Inner layer 73% polyethylene oxide blend:

(Both mfg by Union Carbide Corp. Danbury, CT)

10% Polyethylene Glycol MW=4500 (Dow 4500)

15% Menthone glycerinacetal (Frescolat MGA)

2% Green colorant

Table 1 (cont.)

Outer layer 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)

Inner layer 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-carboxamide (WS-3)

2% Green colorant

I

8. Outer layer 40% high impact polystyrene (Mobil 4324) t 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)

Inner layer 73% polyethylene oxide blend:

(Both mfg by Union Carbide Corp. Danbury, CT)

10% Polyethylene Glycol MW=4500 (Dow 4500)

15% γ-cyclodextrin/menthol inclusion complex

2% Green colorant

EXAMPLES 9 & 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% high impact polystyrene (Mobil 4324)

55% 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) 1.5% Misc. additives and colorants

Present Invention: '

A lubricating strip according to the present invention was prepared according to the ^M general method described in Examples 1-5. The formulation for the strip is as follows: '

10. O Ouutteerr llaayyeerr 3 333..55%% high impact polystyrene (Mobil 4324) 55% polyethylene oxide blend:

3 parts POLYOX WSR Coagulant (MW 5,000,000)

10% Polyethylene Glycol MW=4500 (Dow 4500) 1.5% Misc. additives and colorants

Inner layer 85% polyethylene oxide blend:

3 parts POLYOX WSR Coagulant (MW 5,000,000)

EXAMPLES 9 & 10 (cont.)

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 lubricant continue to be delivered in a near zero- order release profile after the fourth shave. However, very low levels are provided in ι Example 9 (control) . _>

OJ I

Claims

C L A I M S

1. A skin engaging member for use in a shaving system of the wet shave type comprising: an elongated sheath region comprised of a thermoplastic resin; and a shaving aid containing core region extending axially throughout said sheath region, wherein said sheath region further comprises a plurality of openings which facilitate the release of shaving aid during shaving.

2. A skin engaging member according to claim 1, wherein said sheath region further comprises an elongated skin engaging surface extending along at least one outer surface of said sheath region.

3. A skin engaging member according to claim 2, wherein said shaving aid comprises a material selected from the group consisting of polyethylene oxide, polyvinyl pyrrolidone, polyacrylamide, hydroxypropyl cellulose, polyvinyl imidazoline, polyethylene glycol, polyvinyl alcohol, polyhydroxyethylmethacrylate, silicone copolymers, sucrose stearate, vitamin E, soaps, surfactants, panthenol, aloe, essential oils, plasticizers, beard softeners; additional lubricants, polytetrafluoroethylene powders, waxes; menthol, eugenol, eucalyptol, safrol and methyl salicylate; tackifiers; non¬ volatile cooling agents; inclusion complexes of skin-soothing agents with cyclodextrins; fragrances; antipruritic/counterirritant materials; antimicrobial/keratolytic materials; anti-inflammatory agents; astringents; compatibilizers and combinations thereof. 4. A skin engaging member according to claim 3, wherein said core region includes from 0% to about 50% (wt) of a water insoluble matrix material selected from the group consisting of nylon, ethylene vinyl acetate, polyethylene, polypropylene, polyurethane, polystyrene, polystyrene-butadiene, polyacetal, polyphenol/polystyrene blends, and combinations thereof.

5. A skin engaging member according to claim 4, wherein said openings have a pore area of from about 0.0005 to about 0.0250 square inches.

6. A skin engaging member according to claim 5, comprising from about 3 to about 30 circular holes having a diameter of from about 0.020 to about 0.040 inches. 7. A skin engaging member according to claim 6, wherein said sheath region comprises a thermoplastic resin selected from the group consisting of polystyrene, high impact polystyrene, polypropylene, filled polypropylene, polyethylene, nylon, and blends thereof.

8. A skin engaging member according to claim 7, wherein said sheath region comprises thermoplastic resin selected from the group consisting of high impact polystyrene, polystyrene, ethylene vinyl acetate and combinations thereof.

9. A skin engaging member according to claim 8, wherein said sheath region and said core region are made from materials having different colors, such that the absence of the core color provides the user with an indication of essential life of the razor onto which said skin engaging member is affixed. 10. A shaving system of the wet shave type comprising a blade member, and structure defining an external skin engaging member adjacent the shaving edge of said blade member, said skin engaging member, being as defined in any one of claims 1 to 9.

11. A shaving system according to claim 10, wherein said core region comprises up to 25% by weight of a non-volatile cooling agent.

12. A shaving system according to claim 11, wherein said cooling agent is selected from menthyl lactate, menthyl ethoxyacetate, menthone glycerinacetal, 3-/-menthoxypropane-l,2-diol, ethyl /-menthyl carbonate, (1S,3S,4R) -p-menth-8- en-3-ol, menthyl pyrrolidone carboxylate, N- ethyl-p-menthane-3-carboxamide, and N,2,3- trimethy1-2-isopropylbutanamide. 13. A shaving system according to claim

10, wherein said core region comprises up to 25% by weight of an inclusion complex of a skin- soothing agent with a cyclodextrin.

14. A shaving system according to claim 13, wherein said skin-soothing agent is selected from menthol, camphor, menthyl lactate, menthyl ethoxyacetate, menthone glycerinacetal, 3 -1- 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.

15. A shaving system according to claim

13. wherein said core region additionally comprises up to about 10% by weight of a displacing agent which displaces the skin- soothing agent from the inclusion complex upon contact with water.

16. A shaving system according to claim 10, 11 or 13, wherein said sheath region comprises at least 35% by weight of polystyrene or high impact polystyrene and said core region comprises at least 50% by weight of polyethylene oxide.