GUM-MASSAGING ORAL BRUSH

Abstract: An oral brush is provided that includes an elongated body, a head portion extending from the body, and a plurality of bristles, formed of particular thermoplastic elastomers, extending from the body. In various embodiments, the thermoplastic elastomer has a Shore A hardness of at least 30; the thermoplastic elastomer is selected form the group consisting of polyetheramides, polyesters, styrene-ethylene-butylene-styrene block copolymers, polyurethanes, polyolefin elastomers, and mixtures thereof; and the thermoplastic elastomer has a flexural modulus of at least 5 MPa.

Description: GUM-MASSAGING ORAL BRUSH Background of the Invention The invention relates to oral brushes and bristles for use in oral brushes. Most humans suffer from tooth decay and/or gingivitis caused by bacteria in the mouth. As a result, decreasing the amount of plague in the mouth has long been the target of persons working in the health care field. A common way of minimizing the plague in the mouth is to brush the teeth regularly. However, the benefits of frequent brushing can be accompanied in some instances by deleterious side effects such as irritation, abrasion and even recession of the gums. These side effects may, in part, result from excessive stiffness and/or sharpness of the toothbrush bristles. Another common way of improving oral health is by massaging the gums to stimulate the gingival tissue. Conventional toothbrushes tend to have limited effectiveness for gum-massaging, and thus often a separate gum-massaging procedure, using a gum-massaging tool, is reguired to ensure good oral health. Endeavors have been made to reduce gum irritation and/or provide a gum-massaging effect by replacing some or all of the toothbrush bristles with rubber or synthetic rubber pins. See, e.g., U.S. Patent No. 4,288,883. Summary of the Invention The invention features improved gum-massaging oral brushes which provide good comfort and gum stimulation while also providing good cleaning of the teeth. The invention also features bristles for use in gum-massaging oral brushes. In one aspect, the invention features an oral brush including an elongated body, a head portion extending from the body, and a brush portion including a plurality of bristles formed of a thermoplastic elastomer extending from the body. The thermoplastic elastomer preferably has a Shore A hardness of at least 30; is selected from the group consisting of polyetheramides, polyesters, styrene-ethylene-butylene- styrene block copolymers, styrene-butadiene-styrene block copolymers, styrene-isoprene-styrene block copolymers, polyurethanes, polyolefin elastomers, and mixtures thereof; and has a flexural modulus of at least 5 MPa. Preferred oral brushes further include a plurality of bristles formed of a non-elastomeric material. In preferred embodiments, this material iε selected from nylon, polyamides, polyesters and polybutyleneterephthalate (PBT) . The non-elastomeric bristles may include additives to improve their cleaning ability, e.g., abrasives and polishing agents such as clays, silicas, aluminas, calcium carbonate, calcium or magnesium phosphate compounds, apatites, and mixtures thereof. Preferred oral brushes also include a spacer attached to the base of the head portion. The spacer is formed of a thermoplastic ela&tomer and iε integrally joined to the bristles. Preferably the non¬ elastomeric bristles extend from the head portion through the spacer. In another aspect, the invention features an oral brush including a plurality of bristles formed of a thermoplastic elastomer, and a plurality of bristleε formed of a polyphthalamide. In another aspect, the invention features massaging the gums with one of the bristles described previously. An oral brush, as used herein, is any brush that includes a body having a brush portion designed for insertion into the mouth. The brush portion, includes a plurality of bristlep extending therefrom and being dimensioned to be used to brush tooth surfaces. In another aspect, the invention features an oral brush including multicomponent bristles, preferably comprising a thermoplastic elastomer sheath surrounding a core material comprising a non¬ elastomeric material or a thermoplastic elastomer having a higher hardness than the thermoplastic elastomer sheath. The invention also features methods of making multi-component bristles, e.g., by coextruding a plurality of polymers. By "multicomponent", we mean that the bristles have two or more components; by "coextruded", we mean that at least two of the components are present in the form of substantially separate phases having a distinct interface between them, rather than being intermixed. The bristles are preferably formed by processes which are referred to in the art as "coextrusion" but the term, "multicomponent coextruded", as used herein, encompasses bristles having the structure described above which are manufactured by other processes. The term "thermoplastic elastomer" as used herein, refers to non-vulcanized rubbery polymeric materials which may be processed by conventional plastics processing methods which are well known in the art, such as extrusion or injection molding. In another aspect, the invention features an oral brush including a plurality of bristles formed of a mixture including (a) a non-elastomeric polymer, such as a relatively hard base resin, e.g., Nylon, polypropylene, or polybutylene terephthalate (PBT) and (b) a thermoplastic elastomer such as a polyamide thermoplastic elastomer, a polyester thermoplastic elastomer or other olefinic thermoplastic elastomers. In some embodiments this mixture also contains additives βuch as compatibilizers, abrasives and plasticizers. In yet another aspect of the invention, the invention features an oral brush including a plurality of bristles formed of a mixture including (a) a non¬ elastomeric polymer and (b) a soft (e.g., having a hardness of less than 90 Shore A) vulcanized rubber- type polymer, βuch as natural rubber, crosslinked polybutadiene, crosslinked polyacrylates and the like. In some embodiments this mixture also contains additives such as compatibilizers, abrasives and plasticizers. Other features and advantages of the invention will be apparent from the description of the preferred embodiment thereof, and from the claims. Brief Description of the Drawings Fig. 1 is a perspective view of an oral brush. Fig. 2 is a schematic top plan view of the head of an oral brush according to one embodiment of the invention. Fig. 3 is a schematic top plan view of the head of an oral bruβh according to another embodiment of the invention. Fig. 4 is a cross-sectional top view of a coextruded bristle according to one embodiment of the invention. Fig. 5 is a schematic diagram showing a process according to one embodiment of the invention for forming a coextruded filament. Figs. 6 and 7 are perspective views of oral brushes having bristles molded to a spacer. Description of the Preferred Rι»h^j π »n *- F Referring to Fig. 1, a toothbrush 10 includes a plastic body having a handle 12 and a head 14 attached to a bristle portion 16. The body of the toothbrush is formed by conventional methods well-known in the art. The handle is shaped to be grasped by a hand, but alternatively can be shaped to fit into an electric toothbrush. The configuration of the head can vary and may be rectangular, oval, diamond-shaped, or any other shape, with briβtles which are trimmed flat, serrated, v- βhaped, convex curved, or any other deβired topography, aβ is well known in the art. The shape and size of handle 12 and head 14 can vary and the axes of the handle and head may be on the same or a different plane. It may be desired to provide a larger head than is conventional, in order to provide extra room for the thermoplastic elaβtomer bristles, while still retaining the standard number of nonelastomeric bristles. Brush portion 16 includes a number of nonelastomeric bristles 18 and a number of elastomeric bristles 20. Preferably, as shown in Fig. 2, the non¬ elastomeric bristles extend from the central portion of the head 14 and the elaβtomeric bristles are disposed around the outer perimeter of the head 14, surrounding the non-elastomeric briβtles. Another possible arrangement is shown in Fig. 3. The non-elastomeric bristles are formed of tufts of individual filaments attached to the head in manners known to the art. The elastomeric: bristles are formed of tufts of one or more filaments of thermoplastic elaβtomer. If a single filament is used per tuft, the filament preferably has a diameter that is half that of a standard pre-cored tuft hole, e.g., 33 mil for a 66-mil pre-cored hole, so that the filament can be folded and staple tufted into the hole. Alternatively, some or all of the bristles are formed of a mixture of elastomeric and non¬ elastomeric polymers. The elastomeric material is selected from the group consisting of thermoplastic elastomers and vulcanized rubber-type polymers. In both cases, the ratio of the elaβtomer to the non¬ elastomeric material is preferably from 10:90-90:10. Preferred bristle diameters range from 3-100 mil (tapered or untapered) , depending on the mixture used and elastomer and non-elaβtomeric material chosen as would be understood by one skilled in the art. Suitable filaments formed of a blend of elastomeric and non-elastomeric include, but are not limited to the following: Composition Processing Drawdown Diameter Bend Temp Ratio Recovery 30% Pebax 2533 250°C. 4:1 8 mil 95% 70% Zytel 151L 30% Pebax 2533 250°C. 4:1 7 mil 95% 70% Zytel 151L Such a mixture can be compounded using standard processing procedures such as a single screw or twin screw extruder or dry blending. Suitable thermoplastic elastomers are those which have sufficient stiffness and hardness for effective gum massage and to resist tearing and/or excessive wear during use, while being sufficiently soft to provide comfort and avoid gum irritation during gum massage. Suitable thermoplastic elastomers include polyetheramides, e.g., PEBAX polymere (ELF Atochem) ; polyeβterβ, e.g., HYTREL polymers (DuPont); styrene- ethylene-butylene-βtyrene block copolymers, styrene- ethylene-propylene-βtyrene block copolymers, styrene- butadiene-βtyrene block copolymers, and styrene- iβoprene-βtyrene block copolymers, e.g., KRATON rubbers (Shell); polyurethanes, e.g., PELLETHANE polyurethanes (DOW); polyolefin elastomers, e.g., SANTOPRENE elastomerβ (Advanced Elaβtomer Systems) ; and mixtures thereof. Poly(ether-amide) block copolymers having the general formula where PA=polyamide segment and PE=polyether segment, commercially available under the tradename PEBAX polymers, are particularly preferred. Of these, a copolymer of nylon 12 and poly(tetramethylene glycol) having the general formula O 0 OH -4 r- C ii-f-NYLON 12 -7-C n - 0-(-PTMG-*-0 -j- n H commercially available under the tradename PEBAX MX- 1205 polymer is particularly preferred. Another preferred thermoplastic elaβtomer comprises a blend of a polyamide sold under the tradename PEBAX 2533 and a block copolymer sold under the tradename KRATON G-6713, preferably containing about 90% of the polyamide and 10% of the block copolymer. This blend provides good softnese without tackiness or weakness. If a relatively soft thermoplastic elastomer is used, a relatively large diameter filament may be needed to provide sufficient durability and stiffness. Such large diameter filaments preferably have a diameter leββ than about 200 mil, more preferably 30 to 100 mil. If a harder, stiffer thermoplastic elastomer is used, a smaller diameter filament can be used. Generally, suitable thermoplastic elastomerβ will have a Shore A hardness of at least 30, preferably from about 35 to 55 and a flexural modulus of from about 5 to 100 MPa. Suitable vulcanized rubber type polymers include, but are not limited to, natural rubber, crosslinked polybutadiene, crosβ-linked polyacrylates, and blends thereof. Non-elastomeric bristles 18 may be formed of any material suitable for use in toothbrush bristles. Such materials can also be used as the non-elastomeric component of elastomeric non-elastomeric blend bristles. Preferred materials include nylon 612 and other polyamides. A preferred grade of nylon is available from Whiting Co., Burlington, VT under the tradename WYTEX. Preferred polyamides include polyphthalamideβ sold by Amoco Performance Products, Inc. , under the tradename AMODEL resins. Such polyphthalamides are described in U.S. Patent Nos. 4,603,166, 4,476,280, and 4,617,342, the disclosures of which are incorporated herein by reference. A particularly preferred polyphthalamide is a crystalline polyphthalamide formed by polymerization of terephthalic acid, isophthalic acid and adipic acid with hexamethylene diamine. Other suitable filaments include acetal resins, polyesters, fluoropolymers, polyacrylates, polyβulfones and combinations thereof. Preferred non-elastomeric filaments have a diameter of from about 3 to 10 mil. In an alternate embodiment, the elastomeric bristles include a sheath 30 of thermoplastic elastomer coextruded around a core 32 of a different material, as shown in cross-section in Fig. 4. The sheath to core volume ratio may be from 95:5 to 5:95. Preferably, the core material is a stiff polymer, allowing the outer sheath to be softer and/or allowing the bristleβ to have smaller diameters than would otherwise be posβible (with a thermoplastic elastomer alone) due to the constraints of briβtle durability and strength. If desired the coextruded filaments can have standard bristle diameters, e.g., 5-8 mil. Preferred filament diameters range from 5 to 65 mil, depending on the application in which the bristle is to be used. Suitable core materials include but are not limited to polyamides, e.g., nylons, and polyesterβ, e.g., PBT. Preferred sheath materials include the thermoplastic elastomers discussed above. Softer grades of these elastomers can be used when a stiff core is provided, e.g., the sheath material may have a hardness as low as 3 Shore A. A βuitable method for forming the coextruded filaments is shown in Fig. 5. As shown, the two components are extruded through first and second extruders to form a filament, after which the filament is passed through a water bath, and through a series of godets. The filament is placed under light tension as it travels between two drawing godets which are rotating at different speedβ. The tension applied to the filament is expressed as the "drawdown ratio", which is the speed differential between the two drawing godets. Preferred drawdown ratios are from about 1.0 to 7.0. The filament then passes through a relaxing godet and is collected on a take-up winder. Suitable coextruded filaments include, but are not limited to, the following: Composition Volume Ratio Drawdown Diameter (Sheath/Core) Rat. PEBAX MX1205/ 10:90 4:1 8 mil Nylon 612 PEBAX MX1205/ 50:50 1:1 or 2:1 55 mil Nylon 612 Blend of 90% 10:90 4:1 8 mil PEBAX 2533 and 10% DYNAFLEX or G6712/ Nylon 612 50:50 1:1 or 2:1 55 mil HYTREL 3078/ 10:90 4:1 8 mil Nylon 612 or 50:50 1:1 or 2:1 55 mil In an alternate embodiment, head portion 14 includes bristleβ 20 integrally joined to spacer 40, which is attached to the base of head portion 14, as shown in Fig. 6. Spacer 40 provideβ good adhesion of bristleβ 20 to head portion 14 and provides support to bristleβ 18. The additional support provided by spacer 40 stiffens bristles 18 by decreasing the effective length of the bristles, which allows the incorporation of briβtles having smaller diameters that more eaβily penetrate the interstitial regions of the mouth into the toothbrush. Bristleβ 18 extend from head portion 14 through spacer 40. Spacer 40 is formed of the elastomeric materials listed above and can be formed of the same elastomeric material as used to form the elastomeric bristleβ 20. Spacer 40 and elastomeric bristles 20 at the perimeter of head portion 14 can be molded as one unit. If the bristles 20 and spacer 40 are molded as one unit, their diameter is preferably from about 4 mil to about 200 mil. Elastomeric bristleβ 20 can extend at angles from spacer 40. Alternatively, spacer 40 can be recessed into head 14 such that the bristle receiving surface 46 of spacer 40 iβ substantially contiguous with surface 44 of head portion 14, as shown in Fig. 7. Other embodiments are within the claimβ. For example, if desired, all of the bristleβ may be formed of thermoplastic elaβtomer material. The briβtles may be formed of a blend of thermoplastic elastomerβ. Moreover, the oral bruβh may include elastomeric bristleβ having different relative compoβitionβ, e.g., some of the bristleβ are formed of a first- thermoplastic elastomer or blend of elastomerβ and other briβtles are formed of a different thermoplastic elastomer or blend. Further, the elastomeric briβtleβ may include other polymers, e.g., plasticizers such as oils, waxes or resins to increase softness, or additives, e.g., fillers, antioxidants, UV stabilizers, and abrasiveβ or polishing agents. Suitable poliβhing agents include particles of plastic, particles of walnut βhellβ, particleβ of hardwood, particleβ of corn cob, particleβ of rubber, calcium carbonate, aragonite clay, orthorhombic clays, calcite clay, rhombohedral clays, kaolin clay, bentonite clay, dicalcium phosphate, dicalcium phosphate anhydrous, dicalcium phosphate dihydrate, tricalcium phosphate, calcium pyrophosphate, insoluble sodium metaphosphate, precipitated calcium carbonate, magnesium orthophosphate, trimagnesium phosphate, hydroxyapatites, synthetic apatites, alumina, hydrated alumina, hydrated silica xerogel, metal aluminosilicate complexes, sodium aluminum silicateβ, zirconium silicate, silicon dioxide, and combinations thereof.

Claims: C L A I M S 1. An oral bruβh suitable for massaging the gums, comprising: an elongated body; a head portion extending from βaid body; and a bruβh portion comprising a plurality of briβtleβ extending from βaid head portion, βaid bristles comprising a thermoplastic elastomer having a Shore A hardness of 30 or greater. 2. The oral bruβh of claim 1, wherein βaid thermoplaβtic elaβtomer iβ βelected from the group conβiβting of polyetheramides, polyesters, styrene-ethylene-butylene- styrene block copolymers, styrene-butadiene-styrene block copolymers, styrene-isoprene-styrene block copolymers, polyurethanes, polyolefin elastomerβ, and mixtures thereof. 3. The oral bruβh of claim 1 or 2, wherein βaid thermoplaβtic elastomer has a flexural modulus of at least 5 MPa. 4. The oral brush of claim 1, said oral brush further comprising a spacer attached to a base of said head portion, said spacer comprising said thermoplastic elastomer and integrally joined to said bristleβ. 5. The oral bruβh of claim 1, wherein βaid brush portion further compriβeβ a plurality of briβtleβ formed of a non-elaβtomeric material. 6. The oral bruβh of claim 5, wherein βaid non¬ elastomeric material is selected from nylon and polyamides. 7. The oral bruβh of claim 6, wherein βaid non¬ elastomeric material is a crystalline polyphthalamide formed by polymerization of terephthalic acid, isophthalic acid and adipic acid with hexamethylene diamine. 8. The oral brush of claim 5, wherein said non¬ elastomeric material comprises an abrasive additive. 9. The oral brush of claim 5, further comprising a βpacer attached to a base of βaid head portion, βaid briβtleβ formed of βaid non-elaβtomeric material extending from βaid head portion through βaid βpacer. 10. An oral brush comprising: an elongated body; a head portion extending from said body; and a bruβh portion comprising a plurality of briβtleβ extending from βaid head portion, βaid briβtleβ compriβing a thermoplastic elaβtomer βelected from the group conβiβting of polyetheramides, polyesters, styrene-ethylene-butylene- βtyrene block copolymers, styrene-butadiene-styrene block copolymers, styrene-isoprene-styrene block copolymers, polyurethanes, polyolefin elastomerβ, and mixtures thereof. 11. The oral brush of claim 10, wherein said brush portion further compriseβ a plurality of briβtleβ formed of a non-elastomeric material. 12. The oral bruβh of claim 11, wherein βaid non¬ elastomeric material iβ βelected from polyamides and polyesters. 13. The oral brush of claim 12, wherein said non¬ elastomeric material iβ a crystalline polyamide formed by polymerization of terephthalic acid, isophthalic acid and adipic acid with hexamethylene diamine. 14. The oral brush of claim 11, wherein βaid non¬ elastomeric material compriseβ an abrasive additive. 15. The oral brush of claim 11, said oral brush further comprising a βpacer attached to a base of βaid head portion, βaid bristles formed of said non-elastomeric material extending from said head portion through said spacer. 16. The oral brush of claim 10, wherein βaid thermoplaβtic elaβtomer hae a flexural modulus of at least 5 MPa. 17. The oral brush of claim 10, said oral brush further comprising a βpacer attached to a base of said head portion, said βpacer compriβing βaid thermoplaβtic elaβtomer and integrally joined to βaid bristleβ. 18. An oral brush comprising: an elongated body; a head portion extending from said body; and a brush portion comprising a plurality of bristles extending from βaid head portion, βaid briβtleβ compriβing a thermoplastic elastomer having a flexural modulus of at least 5 MPa. 19. The oral bruβh of claim 18, said oral brush further comprising a spacer attached to a base of βaid head portion, βaid spacer comprising said thermoplastic elastomer and integrally joined to βaid briβtles. 20. An oral brush comprising: an elongated body; a head portion extending from βaid body; and a brush portion compriβing, extending from βaid head portion, a plurality of bristles comprising a thermoplastic elastomer and aplurality of bristleβ comprising a polyphthalamide. 21. The oral brush of claim 20, wherein βaid polyphthalamide iβ formed by polymerization of terephthalic acid, isophthalic acid and adipic acid with hexamethylene diamine. 22. The oral brush of claim 21, wherein said polyphthalamide comprises an abrasive additive. 23. The oral brush of claim 20, said oral brush further compriβing a βpacer attached to a baβe of βaid head portion, βaid βpacer compriβing βaid thermoplaβtic elaβtomer and integrally joined to βaid briβtleβ compriβing said thermoplastic elastomer. 24. The oral brush of claim 23, wherein βaid briβtleβ comprising βaid polyphthalamide extend from βaid head portion through βaid βpacer. 25. A method of massaging the gums comprising contacting the gums with a bristle formed of a thermoplaβtic elaβtomer having a Shore A hardness of at least 3.0. 26. A method of massaging the gums compriβing contacting the gums with a bristle formed of a thermoplastic elaβtomer having a flexural moduluβ of at least 5 MPa. 27. A method of massaging the gums comprising contacting the gums with a bristle formed of a thermoplastic elastomer selected from the group consisting of polyetheramides, polyesters, styrene-ethylene-butylene- styrene block copolymers, styrene-butadiene-styrene block copolymers, styrene-isoprene-styrene block copolymers, polyurethanes, polyolefin elastomers, and mixtures thereof. 28. An oral brush comprising: an elongated body; a head portion extending from said body; and a brush portion comprising a plurality of bristleβ extending from βaid head portion, said bristles comprising a thermoplaβtic elaβtomer sheath, compriβing a thermoplaβtic elaβtomer βelected from the group conβiβting of polyetheramides, polyesters, styrene-ethylene-butylene- styrene block copolymers, styrene-butadiene-βtyrene block copolymers, styrene-isoprene-styrene block copolymers, polyurethanes, polyolefin elastomerβ, and mixtureβ thereof, surrounding a non-thermoplastic elastomer core material. 29. The oral brush of claim 28, wherein said briβtleβ are formed by coextrusion. 30. The oral brush of claim 28, wherein said core material is selected from polyamides and polyesters. 31. The oral brush of claim 28, wherein said briβtleβ have a diameter of from 5 to 8 mil. 32. The oral brush of claim 28, βaid oral bruβh further comprising a βpacer attached to a baβe of βaid head portion, βaid βpacer compriβing βaid thermoplastic elastomer and integrally joined to said bristleβ. 33. A method of making a toothbrush bristle comprising coextruding a plurality of polymere to form an elongated filament having a plurality of βeparate phases. 34. The method of claim 33, wherein one of said polymere compriβeβ a thermoplaβtic elaβtomer. 35. The method of claim 33, wherein said polymers are coextruded in a sheath/core geometry. 36. The method of claim 33, further comprising applying tension to said filament to draw the filament. 37. The method of claim 36, wherein the tension iβ applied at a drawdown ratio of from 1:1 to 7:1. 38. An oral brush comprising: an elongated body; a head portion extending from said body; and a bruβh portion comprising a plurality of bristles extending from said head portion, said briβtleβ comprising a thermoplastic elastomer sheath surrounding a core comprising a thermoplastic elastomer having a higher hardness than said thermoplastic elastomer sheath. 39. An oral brush comprising: an elongated body; a head portion extending from said body; and a brush portion comprising a plurality of briβtleβ extending from βaid head portion, βaid briβtleβ compriβing a blend compriβing an elastomeric polymer and a non-elastomeric polymer. 40. The oral brush of claim 39, said oral bruβh further comprising a spacer attached to a base of said head portion, said spacer comprising said thermoplastic elastomer and integrally joined to said bristleβ. 41. The oral bruβh of claim 39, wherein said elastomeric polymer is selected from the group conβiβting of thermoplaβtic elastomers and vulcanized rubber-type polymers. 42. The oral bruβh of claim 41, wherein βaid elaβtomeric polymer compriβeβ a thermoplaβtic elaβtomer βelected from the group conβisting of polyamide thermoplastic elastomers, polyester thermoplaβtic elastomers, and olefinic thermoplastic elastomers. 43. The oral brush of claim 41, wherein said elastomeric polymer, compriseβ a vulcanized rubber-type polymer βelected from the group conβiβting of natural rubber, cross-linked polybutadiene, and cross-linked polyacrylates and mixtures thereof. 44. The oral bruβh of claim 39, wherein βaid elaβtomeric polymer and said non-elastomeric polymer are provided in a ratio of from 10:90 to 90:10.

Inventors: MASTERMAN CRAIG T, PARK EDWARD HOSUNG, ROBERTS MICHAEL F, SWEENEY PHILIP J, TSENG MINGCHIH M, WITKUS STEPHEN C, MASTERMAN, CRAIG, T., PARK, EDWARD, HOSUNG, ROBERTS, MICHAEL, F., SWEENEY, PHILIP, J., TSENG, MINGCHIH, M., WITKUS, STEPHEN, C.
Applicants: GILLETTE CANADA, MASTERMAN CRAIG T, PARK EDWARD HOSUNG, ROBERTS MICHAEL F, SWEENEY PHILIP J, TSENG MINGCHIH M, WITKUS STEPHEN C, GILLETTE CANADA INC., MASTERMAN, CRAIG, T., PARK, EDWARD, HOSUNG, ROBERTS, MICHAEL, F., SWEENEY, PHILIP, J., TSENG, MINGCHIH, M., WITKUS, STEPHEN, C.
Application year: 1996
Main classification: A46D1
IPC codes: A46B3, A46B9, A46B15, A46D1