Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Biocides; animal or insect repellents or attractants
Reexamination Certificate
1995-10-25
2002-11-05
Levy, Neil S. (Department: 1616)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Biocides; animal or insect repellents or attractants
C424S405000, C424S409000, C424S543000, C424S548000, C424S581000, C424SDIG001, C424S076300, C424S078090, C524S010000, C524S702000, C524S704000, C524S803000, C523S122000, C514S918000, C514S919000, C514S920000
Reexamination Certificate
active
06475504
ABSTRACT:
This invention deals with pest repellent compositions and articles and a method for preparing both the compositions and the articles.
More specifically, this invention deals with poly(vinyl alcohol) hydrogels containing freezing point depressants, pest repellents, water and plasticizers which are capable of being formed into various configurations and shapes.
BACKGROUND OF THE INVENTION
Means and methods for repelling pests using certain forms of dispensers for the controlled release of repelling materials using volatile liquids such as perfumes, deodorants and biologically active compositions are well known.
Thus, such well known means and methods include an article comprising a reservoir of volatile liquid material enclosed within either a rigid or flexible container wherein at least a portion of the wall of the container is porous to the volatile liquid; the use of a dispenser which comprises a matrix, such as a film formed from a natural or synthetic organic polymer that is impregnated with the material to be released; the use of gels or waxes formed from a natural or synthetic organic polymer, and the like.
Such gel dispensers can be found in, for example, U.S. Pat. No. 4,888,364, issued Dec. 19, 1989 to Graiver, et al in which there is disclosed a free standing dispenser for the controlled release of volatile liquid materials such as perfumes and fragrances. The poly(vinyl alcohol) hydrogels used therein are described as those comprising a continuous phase of a solubilized poly(vinyl alcohol), a dispersed phase comprising a polyelectrolyte and an aqueous solution of the volatile liquid that is distributed between said continuous and dispersed phases. It is claimed that these dispensers remain dry to the touch throughout the useful life of the dispenser.
In another gel dispenser, disclosed in U.S. Pat. No. 4,891,388, which issued Jan. 2, 1990, to Graiver, et al, there is shown a method of preparing the gel dispenser, which method comprises forming a first solution by heating a mixture comprising poly(vinyl alcohol) and water and/or dimethyl sulfoxide under atmospheric pressure, adding a second solution comprising a volatile liquid material and a monohydric alcohol in a solvent that is miscible with the first solution under conditions that avoid precipitation of poly(vinyl alcohol), and then, cooling the resultant solution to below room temperature to form the gel. It appears that this disclosure provides the procedure for the preparation of the gel dispenser of the '364 patent.
Further, there is an identical disclosure in U.S. Pat. No. 4,891,389, which issued on Jan. 2, 1990 to Gravier. This patent is a divisional of the '364 patent and the disclosure is identical with the '364 patent.
The novelty in the aforementioned patents is the use of a polyelectrolyte with a certain poly(vinyl alcohol) hydrogel to provide compositions which are free standing. The poly(vinyl alcohol) materials used in those compositions and articles is that found in U.S. Pat. No. 4,663,358, which issued May 5, 1987 to Hyon, et al.
The U.S. Pat. No. 4,663,358 discloses the preparation of the hydrogels that have been found useful herein and that patent is incorporated herein by reference for what it teaches about the preparation of high strength poly(vinyl alcohol) hydrogels.
It should be understood by those skilled in the art that the inventor herein is relying on the general disclosure of the Hyon, et al patent and that a new and novel method for preparing the hydrogels of the instant invention is set forth and claimed herein.
THE INVENTION
The invention disclosed and described herein is a method for the formation of unique poly(vinyl alcohol) hydrogel compositions and unique odor-providing solid pest repellent compositions and their uses.
More specifically, one aspect of this invention deals with a process for preparing a solid pest repellent article capable of emitting a pest repelling odor. The process comprises (I) contacting a freezing point depressant for water with water and homogenizing the resulting solution at a temperature of 20° F. to 50° F. Thereafter, step (II) comprises heating the solution from (I) to a temperature of about 80° to about 100° C. and then (III) adding a high strength poly(vinyl alcohol) polymer and homogenizing once again. Step (IV) then comprises heating the solution of (III) until the solution is clear and essentially free of gel particles. It is at this point that one or more pest repellents can be added to the composition of (IV), and then in a step (V), the composition is further homogenized. Finally, in step (VI), the composition from (V) is frozen at a temperature of 0° C. or below for at least two hours to form a high strength poly(vinyl alcohol) hydrogel article. The freezing time can be less than two hours, but the articles will not be as strong or as tough. The frozen composition is then allowed to return to room temperature to provide the articles of this invention.
In another aspect of this invention, there is provided a composition comprising in combination a blend of a high strength poly(vinyl alcohol) hydrogel, water, at least one pest repellent, and, a water soluble, non-volatile, freezing point depressant for the water, which depressant does not de-stabilize the composition. The freezing point depressants are selected from a group consisting essentially of (a) inorganic salts, (b) organic solids, and (c) organic liquids.
And finally, a third aspect of this invention is an article or articles comprising solid pest repellents capable of emitting a pest repelling odor which comprises a combination of a high strength poly(vinyl alcohol) hydrogel, water, at least one pest repellent and a water soluble, non-volatile, freezing point depressant for the water wherein the freezing point depressant is selected from the group consisting essentially of (a) inorganic salts, (b) organic solids and, (c) organic liquids.
Turning first to the method by which the unique poly(vinyl alcohol) hydrogels are prepared, there is provided in step (I) a contact between one or more freezing point depressants for the water used in this method, and the water.
Such freezing point depressants are selected from water soluble, non-volatile, inorganic salts, water soluble, non-volatile, organic solids, and water soluble, non-volatile, organic liquids.
As can be observed, such depressants must be water soluble materials that can lower the freezing point of water and which will not de-stabilize the poly(vinyl alcohol) hydrogel when they are in contact. Using these freezing point lowering additives allows the preparation of the unique form of the poly(vinyl alcohol) hydrogel which is part of the invention herein.
Examples of inorganic salts that are useful in this invention include, generally, divalent metallic salts such as magnesium or calcium, for example calcium chloride (CaCl
2
) and magnesium chloride (MgCl
2
). However, salts such a monovalent metallic salts of sodium, potassium, thallium, and lithium are not useful in the stabilizing of the poly(vinyl alcohol) hydrogels and are often used to break apart (solubilize) such materials, and are therefore, not part of this invention. An easy method to determine the usefulness of the inorganic salts is to test the ability of the salt to precipitate and/or solubilize the poly(vinyl alcohol) hydrogel. If the poly(vinyl alcohol) hydrogel precipitates or goes into solution, then the salt is not useful herein. Also, divalent transient metallic salts such as titanium, zirconium, copper, and cobalt can create complexes with the poly(vinyl alcohol) polymers resulting in water-insoluble, non-reversible gel formation and therefore, these materials are not useful in this invention. Further, trivalent metallic salts of boron, aluminum and the like are known to crosslink or complex with poly(vinyl alcohol) polymers also resulting in water insoluble gels, and therefore, these materials should also be avoided for use in this invention.
With regard to the organic water soluble materials, it should be noted that the materials, in order to
Levy Neil S.
McKellar Robert L.
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