Cutlery – Razors – Combined
Reexamination Certificate
2000-02-18
2001-10-16
Payer, Hwei-Siu (Department: 3724)
Cutlery
Razors
Combined
C030S081000, C030S050000, C424S073000
Reexamination Certificate
active
06301785
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a shaving aid strip (or composite) for a razor cartridge.
It is now well known that shaving comfort can be enhanced by affixing to a razor cartridge a shaving aid composite, also known as a lubricating strip, which continuously releases a shaving aid, typically a lubricant, during the shaving process. See, for example, U.S. Pat. No. 4,170,821 and GB 2,024,082. The shaving aid strip generally comprises a water-insoluble polymer matrix, typically polystyrene, and a water-soluble shaving aid, typically polyethylene oxide, which leaches out of the strip during shaving to enhance shave comfort.
Unfortunately, conventional shaving aid strips suffer from the disadvantage that they release an insufficient amount of the shaving aid, particularly after the first four or five shaves where release of the shaving aid may drop off to negligible quantities. In addition, the amount of shaving aid that may be included in the shaving aid strip may be limited because high levels of shaving aid are difficult to process and can adversely affect the structural integrity of the strip. Accordingly, recent efforts have been made to improve shaving aid strips so as to enhance and prolong release of the shaving aid.
Such efforts have resulted in improved shaving aid strips which include the following features: incorporation of a low molecular weight release enhancing agent, such as polyethylene glycol, into the matrix (U.S. Pat. No. 5,113,585); the use of ethylene vinyl acetate copolymer as the matrix material (U.S. Pat. No. 5,349,750); incorporation of a compatibilizer material such as polyethylene oxide-polypropylene oxide copolymer (e.g. Poloxamer 182) (U.S. Pat. No. 5,454,164); incorporation of a water-swellable polymer such as Salsorb 84, a cross-linked polyacrylic (U.S. Pat. No. 5,626,154); coextrusion of a core comprising a water-leachable shaving aid within a sheath of water-insoluble polymer, wherein the sheath has a plurality of openings to facilitate release of the shaving aid (WO 96/13360, which corresponds to U.S. Ser. No. 08/497,194); and coextrusion of adjacent shaving aid portions (U.S. Pat. No. 5,956,848). Also known are shaving aid strips which include an essential oil (U.S. Pat. No. 5,095,619) or a non-volatile cooling agent (U.S. Pat. No. 5,713,131), and injection molded strips which include a plasticizer (U.S. Pat. No. 4,850,106). All of the aforementioned patents or published applications are incorporated herein by reference.
SUMMARY OF THE INVENTION
The present invention is directed to a solid polymeric shaving aid strip for a razor cartridge. The shaving aid strip comprises a lubricious water-soluble polymer and a polycaprolactone. Preferably, the strip may also optionally contain a water-insoluble polymer, which serves as a matrix in which the water-soluble polymer is incorporated (or dispersed). It has been found that polycaprolactone improves the fabrication of the shaving aid strip, provides smoother strip surfaces and permits the inclusion of greater amounts of water-soluble polymer in the strip. It has also been found that a shaving aid strip which contains polycaprolactone releases more shaving aid during use and has better structural integrity and less swelling. The present invention is also directed to a razor cartridge which includes the aforementioned shaving aid strip.
The razor cartridge will comprise a blade (one or more) and a skin-engaging portion in proximity to the blade, wherein the skin engaging portion includes the shaving aid strip. The shaving aid strip contacts the skin during shaving and releases shaving aid onto the skin. The shaving aid strip is typically located at the rear (or cap) portion of the cartridge (i.e. behind the blade or blades), but may also be located at the front (or guard) portion of the cartridge (i.e. in front of the blade or blades), or a shaving aid strip may be placed at both positions on the cartridge. The razor cartridge is generally affixed to a handle for use in shaving. The razor cartridge may be designed to be removably affixed to a handle in the case of razor systems in which the handle is reused and the cartridge is disposed of after one or more uses. Or the razor cartridge may be permanently affixed to a handle (or integral with the handle) in the case of disposable razors in which the handle and cartridge are disposed of together as a unit after one or more uses. The term razor cartridge is thus intended to apply to both types of cartridge.
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patent: 693528 (1996-01-01), None
patent: 8-280952 (1996-10-01), None
patent: WO 96/13360 (1996-05-01), None
TONE® Polymers, Union Carbide brochure, © 1990, 1994.
Kwiecien Michael J.
Ndou Thilivhali T.
Payer Hwei-Siu
The Gillette Company
Williams Stephan P.
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