Cutlery – Razors – Combined
Reexamination Certificate
2000-06-28
2002-06-18
Payer, Hwei-Siu (Department: 3724)
Cutlery
Razors
Combined
Reexamination Certificate
active
06405438
ABSTRACT:
BACKGROUND OF INVENTION
1. Field of Invention
The present invention relates to the field of shaving by mechanical means using a discardable razor; it relates more particularly to an auxiliary shaving article in the form of a strip and referred to as a “strip”, which is fixed on the shaving head, preferably in the vicinity of the shaving blades, and which contains at least one shaving-assistance component that is soluble in water.
2. Description of the Related Art
When the razor is used, the user dips the shaving head in hot water, thereby making a portion of the shaving-assistance components) accessible and leachable, which components come into contact with the skin on each pass of the razor.
In U.S. Pat. No. 4,170,821 to Booth, the auxiliary shaving article proposed is combined with a micro-encapsulating or micro-porous water-soluble solid structure for retaining the shaving-assistance component which can be selected from a list of substances comprising a lubricant for reducing the effect of friction between the razor and the skin, an agent for reducing rubbing between the razor and the skin, an agent suitable for modifying hair structure, a cleansing agent, a pharmaceutical agent, a cosmetic agent, and a coagulation agent. As an example of a lubricant for reducing the effect of friction between the razor and the skin, U.S. Pat. No. 4,170,821 cites a micro-encapsulated silicone-based oil, and as an example of an agent for reducing rubbing between the razor and the skin, that document cites an oxide of polyethylene having molecular weight lying in the range 100,000 to 6,000,000, a non-ionic polyacrylamide, and a natural polysaccharide derived from plant matter such as guar gum.
In document EP-B-0 1 184 440, provision is made to form an auxiliary shaving article in the form of a strip by extruding a mixture of water soluble and insoluble polymer materials. That document gives a list of water soluble polymers comprising polyethylene oxide, poly-vinylpyrrolidone, polyacrylamides, hydroxypropyl-cellulose, polyvinylimidazoline, and hydroxyethyl poly-methacrylate. In a particular embodiment, the mixture for forming said strip by extrusion is made up of 20% by weight water insoluble polystyrene and 80% by weight of a mixture of polyethylene oxide comprising 60% “coagulating polyox” polyethylene oxide of molecular mass equal to 5,000,000, and 40% “WSR N-750 polyox” polyethylene oxide of molecular mass equal to 300,000. No explanation is given in that document concerning the advantage of mixing those two types of polyethylene oxide together, other than for obtaining a mean molecular weight of about 3.5 million for the polyethylene oxide in the final mixture.
In document EP-B-0 550 605, the mixture for forming the auxiliary shaving article by extrusion in the form of a strip contains, in addition to the water soluble and insoluble materials, an agent of low molecular weight for amplifying the release of the water soluble polymer material making up the shaving-assistance component. Amongst all of the possible examples, that document cites polyethylene oxide as a shaving-assistance component which can be leached by water, and polyethylene glycol as an agent for amplifying release. In characteristic manner, according to that document EP-B-0 550 605, the mixture for forming the auxiliary shaving article by extrusion in the form of a strip comprises 20% to 60% by weight of insoluble polymer material that forms the matrix of the strip, 20% to 75% by weight of water soluble polymer material that constitutes the water-leachable shaving-assistance component, and 5% to 20% by weight of agent for amplifying release. In all of the examples cited in that document, exactly the same mixture of two types of polyethylene oxide is to be found as already described in prior document EP-B-0 184 440, i.e. 60% by weight of coagulating polyox and 40% by weight of WSR N-750 polyox. In the examples cited, the agent for amplifying release is a polyethylene glycol of molecular weight lying in the range 4,500 to 20,000. The intended purpose of having the release-amplifying agent present is to make it possible to maintain a sufficient quantity of insoluble polymer for retaining sufficient mechanical strength in the extruded strip both on initial manufacture and assembly, and after a significant quantity of water soluble material has already been leached, while still making it possible for a sufficient quantity of water soluble shaving component to be released to provide effective shaving assistance throughout the total useful lifetime intended for the blade or blades.
In that document EP-B-0 550 605, no explanation is given concerning the reasons which enable certain specified agents of low molecular weight to amplify release of the shaving-assistance component, i.e. ethylene glycol, methoxy polyethylene glycol, methyl-cellulose, and carboxypolymethylene. It should be observed that those four examples are the only examples mentioned in that document, and that they all relate to the above-mentioned mixture of polyethylene oxide and the added polyethylene glycol. It should be recalled that polyethylene oxide and polyethylene glycol have the same general formula, differing only in method of manufacture and mean molecular weight. The term “polyethylene glycol” is used to designate a compound whose molecular weight is generally less than 20,000. The term “polyethylene oxide” is used to designate a compound whose main molecular weight is greater than 100,000, it being understood that a very wide variety of products are available on the market, having the general formula of polyethylene oxide, with mean molecular weights lying in the range 100,000 to 8,000,000.
Thus, according to the Applicant, it can be thought that polyethylene glycol is used in document EP B 0 550 605 also as a shaving-assistance component, in addition to the low molecular weight polyethylene oxide (WSR N-750 polyox) so as to obtain sufficient release of shaving-assistance components during the lifetime of the discardable shaving head.
Thus, present trends in this field are towards releasing a large amount of shaving-assistance soluble component, in particular polyethylene oxide which is preferably associated with polyethylene glycol. Nevertheless, because a large amount is released, the component remains present on surfaces of the skin that have already been shaved, and can form a film by drying out. To avoid that drawback, it is necessary for the user to wash after shaving. However, depending on the quality of the water available, this removal is not always satisfactory and a sticky feeling can remain on the skin. If all or some of the soluble component remains on the skin, that can be a source of irritation, particularly for sensitive skins.
To mitigate those drawbacks, proposals have already been made in document EP-B-0 321 679, for a solution that is different in principle since it avoids the use of a soluble polymer by proposing to implement a xerophilic gel as the anti-friction agent which, while absorbing water as a dispersing agent, becomes transformed into a lyophilic gel having very great aptitude for sliding on the skin of the user, with a coefficient of friction &mgr; of less than 0.25. By adding the dispersion agent, e.g. water, the xerophilic gel becomes transformed once more into a lyophilic gel by swelling, with its outside surface becoming slippery and presenting a low coefficient of friction. During this stage, the colloidal substance forming the-lattice of the lyophilic gel does not pass into solution, thereby making it possible to avoid forming on the skin a film constituted by a shaving-assistance component extracted from the strip, as was the case in the previously-cited documents.
Nevertheless, according to the teaching of that document EP-B-0 321 679, it is necessary to put the coating that forms the xerophilic gel on a support strip in order to constitute the anti-friction strip proper for placing on the shaving head. The materials recommended for forming the xerophilic gel do not withstand temperatures that would make it poss
Duez Jose
Rebaudieres Jean
Payer Hwei-Siu
Pennie & Edmonds LLP
Societe BIC
LandOfFree
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