Fluid sprinkling – spraying – and diffusing – Slow diffusers
Reexamination Certificate
2001-04-19
2002-08-20
Douglas, Lisa A. (Department: 3752)
Fluid sprinkling, spraying, and diffusing
Slow diffusers
C239S060000
Reexamination Certificate
active
06435423
ABSTRACT:
TECHNICAL FIELD AND PRIOR ART
The present invention relates to the field of perfumery. It relates, more particularly, to a gel device which allows for an effective and prolonged evaporation of an active volatile substance, like a perfume, an insect repellent or a deodorizing or sanitizing agent.
The use of various devices for the diffusion of volatile compounds, for example perfumes, sanitizing agents, insect repellents, and the like, has become more and more current in recent years. For example, air-freshening devices or deodorizers are currently used in practically all households to mask bad odors or to impart fragrances to the ambient air. The known devices used for the diffusion of volatile compounds into the surroundings make use of various principles. As an example, one can mention here dispersing devices of the spray type, aerosols or mechanical. Other examples include plastic packing elements enclosing the active ingredients in liquid form. Typically, the diffusion of the active ingredient takes place through membranes permeable to the vapors of said ingredient.
One class of systems capable of diffusing active volatile ingredients are solid state devices consisting of solid materials or carriers impregnated with an active ingredient. Such devices may be formed of various materials which are capable of absorbing the ingredient and subsequently releasing it in a more or less controlled manner. Examples of such known materials include gels, such as agar-agar or sodium stearate gels, synthetic polymer resins, or blocks of mineral material, e.g. plaster or silica. It is even possible, for some purposes, to have active ingredients absorbed on paper or cardboard in order to obtain a more or less solid carrier device for diffusing the volatile ingredient thus absorbed. Often, solid devices are designed to be non-wetting, i.e. to be capable of effectively retaining the liquid active volatile material and only allowing the diffusion of the vapors of said material.
In general, diffusing devices are to be activated by the customer. Such devices often comprise a pouch or sachet containing the active ingredient and which is hermetically sealed. In order to release the ingredient, the customer will have to pierce the sachet, make it burst or peel off a certain part of it in order to let the active ingredient escape into the surroundings. Other devices comprise multiple compartments having a rupturable joint between them, at least one of these compartments being of a material which is not permeable to the vapors of the ingredient and the other being permeable. Devices of this kind are activated by applying pressure to the non-permeable compartment, upon which the rupturable joint opens to let the active ingredient flow into the compartment which is permeable to its vapors. A diffusing device of this kind is described in U.S. Pat. No. 4,798,288, for example.
Despite prior known diffusing devices for active volatile ingredients, there is still a need for diffusing devices which are capable of releasing effective amounts of active ingredient into the surroundings, in general closed spaces, and this for a prolonged period of time.
DESCRIPTION OF THE INVENTION
According to the invention this object is attained by a device for the diffusion of a volatile active ingredient, comprising an appropriate hydrophilic medium, said volatile active ingredient and an absorbing material selected from superabsorbent substances, starch based systems and chemically modified cellulose, said absorbing material being capable of forming a gel with said hydrophilic medium susceptible of enclosing said volatile active ingredient within and of permitting the diffusion of said volatile ingredient from the gel upon exposure of the latter to air.
The invention also relates to a method for the diffusion of active volatile substances into ambient air, in particular air in closed spaces, the method comprising exposing a gel resulting from mixing a solution, emulsion or suspension of a volatile active ingredient in an hydrophilic solvent with an absorbing material selected from superabsorbent substances, starch based systems, chemically modified cellulose and natural gums, so as to form said gel, to air.
We have found that the diffusion systems according to the invention provide a very uniform and prolonged diffusion of the active ingredient.
As active ingredient, there can be used for example perfumes, resulting in air-fresheners. Other suitable active ingredients comprise deodorizing or sanitizing agents, or insect repellents, or yet any other volatile materials capable of imparting perceptible and desirable benefits to the quality of the air into which they are diffused.
The absorbing material according to the present invention, intended to be mixed with the hydrophilic medium, preferably an aqueous solution, emulsion or suspension of the volatile active ingredient is preferably a so-called superabsorbent material or substance. These are materials which are capable of absorbing large amounts of water or other hydrophilic media. In the context of the present invention, superabsorbents are organic synthetic polymers containing acrylic acid or methacrylic acid, or a salt thereof, these polymers being capable of absorbing between about 50 and 200 times their own weight of water or hydrophilic solvent. Amongst the most current superabsorbents one can cite the cross-linked sodium polyacrylate/polyacrylic acid polymers. Superabsorbents of this type are commercially available under the names of Salsorb® (Allied Colloids Ltd.) and Cabloc® (Stockhausen GmbH).
The superabsorbents of the invention, which are in the form of a fine powder, should preferably have a particle size from about 50 to about 500 microns in order to provide a smooth gel upon admixture of the components of the diffusion device. Powders with larger or lower particle sizes than those mentioned can also be used, but they will result in coarser, or, respectively finer, gels.
According to the invention, best results were obtained with the commercial cross-linked sodium polyacrylates sold under the tradename of Salsorb®. However, it goes without saying that the present invention is not limited to the above-specified materials. There can also be used other types of superabsorbents, for example polymers of other salts of acrylic acid or methacrylic acid, polyacrylamides, polyacrylic esters, polymethacrylic esters, copolymers of acrylates, methacrylates, acrylic acid or methacrylic acid with vinyl acetate, vinyl alcohol or maleic anhydride, isobutylene-maleic anhydride copolymers, saponified graft polymers of acrylonitrile or graft polymers of starch and acrylic acid.
Yet other absorbing materials which can be used in the present invention are acrylic polymers other than those cited above, e.g. acrylamide polymers, starch based systems, e.g. cellulose, gluten, chemically modified cellulose, e.g. carboxymethylcellulose, or cellulose ethers.
The absorbing material as specified above is mixed with a hydrophilic solvent, preferably water or a water based medium possibly containing a small amount of ethanol or a similar solvent, and the volatile active ingredient. In general, the hydrophilic solvent will contain the volatile active ingredient. To this end, there will in general be used a solution, suspension or emulsion of the active ingredient in said hydrophilic solvent.
The hydrophilic solvent is an essential element of the present invention. Its presence is mandatory to achieve the desired regular and prolonged evaporation of the active ingredient. It can be said that said solvent acts as an evaporation aid. Without the presence of the solvent, the evaporation of the active ingredient generally occurs at such a low rate that an effective working of a device according to the present invention is not assured. A further advantage is that a uniform distribution of the active ingredient in the absorbing material is achieved.
When said solution, suspension or emulsion is prepared, it may be advantageous to use an emulsifying agent, although this is optional. In general,
Hurry Simon
Williams Jonathan L.
Douglas Lisa A.
Firmenich SA
Winston & Strawn
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