U.S. patent number RE39,204 [Application Number 10/325,906] was granted by the patent office on 2006-07-25 for gel type vapor release device.
This patent grant is currently assigned to Firmenich SA. Invention is credited to Simon Hurry, Jonathan L. Williams.
United States Patent |
RE39,204 |
Hurry , et al. |
July 25, 2006 |
**Please see images for:
( Certificate of Correction ) ** |
Gel type vapor release device
Abstract
.[.The present invention is drawn to a device for perfuming
ambient air or closed spaces..]. .Iadd.An active volatile
substance, like a perfume, an insect repellent or a deodorizing or
sanitizing agent, is evaporated from a device. .Iaddend.The
.[.said.]. device comprises water or an appropriate hydrophilic
solvent containing .[.said volatile.]. .Iadd.the .Iaddend.active
.[.ingredient and an absorbing material chosen from
superabsorbents, starch based systems, chemically modified
cellulose and natural gum and.]. .Iadd.volatile substance and a
superabsorbent substance .Iaddend.which .[.are.]. .Iadd.is
.Iaddend.capable of forming a gel with water or .[.said.].
.Iadd.the .Iaddend.hydrophilic solvent, both components being
adapted to be mixed with each other in order to achieve the
diffusion of .[.said.]. .Iadd.the active .Iaddend.volatile
.[.ingredient.]. .Iadd.substance .Iaddend.from the .[.said.]. gel.
The components are mixed with each other to form .[.said.].
.Iadd.the .Iaddend.gel from which the .[.perfume or a deodorizing
or sanitizing agent, or an insect repellent,.]. .Iadd.active
volatile substance .Iaddend.diffuses uniformly and over a prolonged
period of time into the surrounding air.
Inventors: |
Hurry; Simon (Ascot,
GB), Williams; Jonathan L. (London, GB) |
Assignee: |
Firmenich SA (Geneva,
CH)
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Family
ID: |
11004767 |
Appl.
No.: |
10/325,906 |
Filed: |
December 23, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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PCT/IB99/01721 |
Oct 20, 1999 |
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Reissue of: |
09837910 |
Apr 19, 2001 |
06435423 |
Aug 20, 2002 |
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Foreign Application Priority Data
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Oct 22, 1998 [WO] |
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PCT/IB98/01700 |
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Current U.S.
Class: |
239/34;
239/60 |
Current CPC
Class: |
A61L
9/048 (20130101); A61L 9/12 (20130101) |
Current International
Class: |
A24F
25/00 (20060101); A61L 9/00 (20060101) |
Field of
Search: |
;239/34,44,45,47,60,145,309 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0 835 666 |
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Apr 1998 |
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EP |
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2 635 955 |
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Mar 1990 |
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FR |
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WO 98/18503 |
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May 1998 |
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WO |
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Primary Examiner: Evans; Robin O.
Attorney, Agent or Firm: Winston & Strawn LLP
Parent Case Text
This application is a continuation of International Application No.
PCT/IB99/01721 filed Oct. 20, 1999, the content of which is
expressly incorporated herein by reference thereto.
Claims
What is claimed is:
1. A device for the diffusion of a volatile active ingredient,
which device comprises a container that includes therein: a) an
appropriate hydrophilic medium; b) the volatile active ingredient;
and c) a superabsorbent substance, wherein the superabsorbent
substance is capable of forming a gel with said hydrophilic medium
and is susceptible of enclosing the volatile active ingredient
within the gel as well as capable of permitting diffusion of the
volatile ingredient from the gel upon exposure of the latter to
air.
2. The device according to claim 1, wherein the hydrophilic medium
is water or a water based solvent.
3. The device according to claim 2, wherein the medium forms a
solution, emulsion or suspension with the volatile ingredient.
4. The device according to claim 3, wherein the solution, emulsion
of suspension of the volatile active ingredient comprises an
emulsifying agent.
5. The device according to claim 4, wherein the emulsifying agent
is a nonionic surfactant, present in an amount of about up to 10%
by weight, relative to the total weight of the solution, emulsion
or suspension.
6. The device according to claim 5, wherein the volatile active
ingredient is present in the solution, emulsion or suspension in an
amount of from about 0.1% to about 15% by weight of the
solution.
7. The device according to claim 1, wherein the volatile active
ingredient is a perfume, an insect repellent or a deodorizing or
sanitizing agent.
8. The device according to claim 1, wherein the gel resulting from
the admixture of the active ingredient and the superabsorbent
substance has an evaporation surface of from about 10 to about 60
cm.sup.2.
9. The device according to claim 1, wherein the superabsorbent
substance is a polymer of acrylic acid, methacrylic acid or a salt
thereof, a polyacrylamide, a polyacrylic ester, a polymethacrylic
ester, a copolymer or acrylates, methacrylates, acrylic acid or
methacrylic acid with vinyl acetate, vinyl alcohol or maleic
anhydride, an isobutylene-maleic anhydride copolymer, a saponified
graft polymer or acrylonitrile or graft polymers of starch and
acrylic acid.
10. The device according to claim 9, wherein the superabsorbent
substance is a cross-linked sodium polyacrylate/polyacrylic acid
polymer.
11. The device according to claim 10, wherein the superabsorbent is
a powder having a particle size of from about 50 to about 500
microns.
12. The device according to claim 3, wherein the superabsorbent
substance is a sodium polyacrylate/polyacrylic acid superabsorbent
material and the amount of active ingredient in the solution,
emulsion or suspension is from about 0.1% to about 10% by weight of
the solution.
13. The device according to claim 1, wherein the superabsorbent
substance is a superabsorbent of the sodium
polyacrylate/polyacrylic acid type which is present in an amount of
from about 0.1% to about 15% by weight, relative to the total
weight of the gel obtained after admixture of the ingredients.
14. The device according to claim 1, wherein the superabsorbent
substance absorbs 50 to 200 times its weight in water and contains
from about 0.01% to about 1% by weight of a water-soluble dye.
15. The device according to claim 1, wherein the container is
composed of two compartments.
16. The device according to claim 15, wherein the superabsorbent
substance and hydrophilic medium containing the volatile ingredient
are stored in the separate compartments and further comprising
means associated with the compartments to allow admixture of the
superabsorbent substance with the hydrophilic medium to form the
gel.
17. A device according to claim 15, which further comprises a
rupturable or burstable joint or wall common to both containers,
one of which contains the superabsorbent substance, the other
compartment enclosing the hydrophilic medium comprising the
volatile active ingredient.
18. The device according to claim 15, wherein the compartment
containing the superabsorbent substance has a wall permeable to the
vapors of the active ingredient and which wall can be sealed by an
appropriate removable closure.
19. A device according to claim 1, wherein the gel is present in
the form as obtained after mixing the superabsorbent substance, the
hydrophilic medium and the volatile active ingredient.
20. The device according to claim 19, which further comprises a
reservoir containing an appropriate hydrophilic solvent and wherein
the gel is located in the upper part of the reservoir, means being
provided to ensure supply of the hydrophilic solvent to gel so as
to maintain the latter moistened.
21. The device according to claim 20, which further comprises a
wick to ensure the supply of hydrophilic solvent to the gel.
22. The device according to claim 21, wherein .[.hat.]. the wick is
formed of an organic inorganic material.
23. The device according to claim 22, wherein .Iadd.the
.Iaddend.wick is made of polyester surrounded by perforated
polypropylene.
24. The device according to claim 20, wherein the container
containing the gel is covered by a material which is permeable to
the vapors of the active ingredient and which can be sealed by an
appropriate removable closure.
25. The method according to claim 8, wherein the activation
comprises removing the seal covering the container with the
gel.
26. A method for the diffusion of active volatile substances into
the surroundings, in particular into closed spaces, which comprises
activating the device of claim 1 and exposing the gel to the
surrounding air to release the vaporizable substances.
27. A method according to claim 26, wherein the activation is
carried out by mixing the superabsorbent substance and the
hydrophilic solvent containing the active ingredient.
28. A gel resulting from the mixing of a superabsorbent substance
with a hydrophilic medium, and an active volatile ingredient
selected from perfumes, insect repellents or deodorizing or
sanitizing agents; wherein the gel is susceptible of enclosing the
volatile active ingredient within the gel as well as capable of
permitting diffusion of the volatile ingredient from the gel upon
exposure of the latter to air.
29. The device according to claim 8, wherein the gel has an
evaporation surface of from about 20 to 40 cm.sup.2.
30. The gel according to claim 28, wherein the hydrophilic medium
is water or a water-based solvent.
31. The gel according to claim 30, wherein the superabsorbent
substance is a cross-linked sodium polyacrylate/polyacrylic acid
polymer.
32. The device according to claim 12, wherein the amount of active
ingredient in the solution, emulsion or suspension is from about 1%
to about 6% by weight of the solution.
33. The device according to claim 13, wherein the superabsorbent
substance is present in an amount of from about 2% to about 5% by
weight, relative to the total weight of the gel obtained after
admixture of the ingredients.
Description
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 compartments, 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 an 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.RTM.
(Allied Colloids, Ltd.) and Cabloc.RTM. (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.RTM.. 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, a surfactant will be used as emulsifying
agent. Systems have been prepared and found to function
satisfactorily without the use of a surfactant, where the active
volatile ingredient, e.g. perfume, and the water are held in
suspension by the gelled structure. Where surfactants are used,
nonionic surfactants are preferred. Examples of this class of
surfactants include ethoxylated sorbitan ethers which are available
under the trade names Span.RTM. (origin: ICI) and Brij.RTM.
(origin: ICI). Ethoxylated saturated fatty esters like those sold
under the names of Cremophor.RTM. (origin: BASF) and Lutensol.RTM.
(origin: BASF) can also be used. Further examples of appropriate
nonionic surfactants include alcohol ethoxylates, polyethylene
glycol esters and ethylene oxide/propylene oxide copolymers. These
surfactants can be present in the aqueous solution, emulsion or
suspension of the active ingredient in concentrations varying from
0 to 10% by weight, preferably from 1 to 3% by weight, relative to
the total weight of said resulting solution, emulsion or
suspension.
As mentioned above, the active ingredient which will be diffused by
the device of the invention can typically be a perfuming
ingredient, a deodorizing or sanitizing agent or an insect
repellent.
As a perfume or perfuming ingredient there can be used in the
device of the invention any ingredient of mixture of ingredients
currently used in perfumery. The latter can be made of discreet
chemicals; more often, however, it will be a more of less complex
mixture of volatile ingredients of natural or synthetic origin. The
nature of these ingredients can be found in specialized books of
perfumery, e.g. in S. Arctander (Perfume and Flavor Chemicals,
Montclair, N.J., USA 1969) or similar textbooks of reference, and a
more detailed description thereof is not warranted here.
Although special mention has been made hereinabove of the perfuming
effect that can be exerted by the invention device, the same
principles apply to the manufacture of analogous devices for the
diffusion of deodorizing or sanitizing vapors, the perfume base
being then replaced by a deodorizing composition, a bactericide, an
insecticide, an insect repellent or even an insect attractant. By
the term "sanitizing vapors", we refer here not only to the vapors
of those substances which can enhance the degree of acceptance of
surrounding air to the observer, but also to those substances which
can exert an attractant or repellent effect towards certain species
of insects, for instance towards houseflies or mosquitoes, or else,
which can have bactericide or bacteriostatic activity. It goes
without saying that mixtures of such agents can also be used.
The above-identified compounds will be admixed with the water or an
appropriate hydrophilic solvent in a quantity which can range, for
all types of gels, from about 0.1% to about 15% by weight of the
resulting solution, emulsion or suspension, preferably about 1 to
6% by weight. Upon use of superabsorbents, these values may
slightly differ from those above which are valid for conventional
absorbing media. We found that the incorporation of larger amounts
of active ingredient is possible. For superabsorbents of the sodium
polyacrylate/polyacylic acid polymer type, values from about 0.1%
to about 20% by weight of active ingredient in the solution,
emulsion or suspension can be attained, the preferred range being
from about 1% to about 6% by weight. It is clear that in cases
where small amounts, such as for example 0.1%, are used, there will
often be observed only a minor effect and the lifetime of the
device will be considerably short. The upper limit for the amount
of active ingredient that can be used, on the other hand, shall be
determined by the ability of the absorbing material to absorb the
solution.
The absorbing material and the solution, emulsion or suspension
containing the active ingredient will be mixed together in order to
form the gel device capable of releasing the ingredient. When a
superabsorbent is used as absorbing material, it will be present in
an amount of from about 0.1% to about 15%, preferably from about 2%
to 5% relative to the total weight of the resulting gel, the
balance being the weight of the solution, emulsion or suspension
containing the ingredient.
The gel obtained after mixing the absorbing material with the
hydrophilic solution, suspension or emulsion containing the active
ingredient, diffuses the active ingredient uniformly and over a
prolonged period of several weeks, unlike prior known diffusion
devices. Moreover, the device can also provide a use-up cue when
all the active ingredient is exhausted and the absorbing material
is formed of a superabsorbent substance. Such superabsorbent
materials (which before mixing are in the form of a fine powder),
do in fact shrink from the gel form into a conglomerate of the
originally present particles upon exhaustion of the volatile active
ingredient. The appearance of these materials can then be described
as being that of wet opaque crystals sticking to each other and the
used-up article therefore is easily distinguishable from the gel
originally obtained upon mixing the components mentioned
before.
The end point cue is even more visible when a water-soluble dye is
incorporated into the dry superabsorbent, i.e. before mixing the
latter with the solution, emulsion or suspension of the volatile
ingredient in the hydrophilic medium. Before activation of the
device, the dye is not distinguishable from the superabsorbent
powder. Yet, when the superabsorbent containing the dye is mixed
with the solution, emulsion or suspension of the active ingredient,
the dye colors, as a consequence of the presence of water and the
distribution of the dye in the gel, thus giving the user a clear
indication that the diffusion device is now activated. The presence
of the dye also facilitates the recognition of the end point of the
device, due to the change between the original gel and the
particles forming upon exhaustion of the diffusion device. A
further advantage of the presence of the dye is that the user can
follow the mixing or activation process of the device of the
invention with his eyes thanks to the color appearance. Only quite
low amounts of dye are necessary to obtain the desired effects, and
typical concentrations are from about 0.01% to about 1%, preferably
0.1% by weight, relative to the weight of the superabsorbent.
An advantage of the device according to the invention is that,
after exhaustion, it can be easily replenished simply by adding a
fresh emulsion or solution containing an active ingredient to the
used up material. The device will then function practically as good
as a device which has been activated for the first time.
The activation of an air-freshening device according to the present
invention can be accomplished in different ways.
In one embodiment of a device of the invention, the absorbing
material and the solution, emulsion or suspension containing the
active ingredient are separated from each other. The customer,
after buying these two components, activates the device simply by
mixing the components, resulting in an air-freshener which gives
the described prolonged diffusion of active ingredients.
Air-freshening devices according to a further embodiment of the
present invention already contain the gel resulting after admixture
of the absorbing material and the solution, emulsion or suspension
containing the active ingredient. The container in which the gel is
found is sealed, in order not to allow diffusion of the active
ingredient into the surroundings. The customer will then activate
the device simply by opening the container, after which the active
ingredient will evaporate. This embodiment is possible because the
gels obtained after mixing of the above-mentioned ingredients are
perfectly stable for a period of several months and can hence be
stored.
According to a preferred embodiment of the invention, the diffusing
device shall comprise separate compartments for the absorbing
material and for the hydrophilic medium containing the volatile
active ingredient, means being provided to permit the activation or
mixing step being carried out by the user himself. The two
above-mentioned components can e.g. be in the form of two closed,
separate and preferably transparent containers, each containing one
of the components. The user can then open both containers and
activate the diffusion device by mixing the components. In a
preferred embodiment, the components will be arranged in a packing
having at least two components and a rupturable joint or wall
common to both compartments. The components are each separately
lodged in one of the said compartments. The two components can then
be mixed by rupturing or bursting the joint or wall, for example by
applying pressure to at least one of the compartments. The two
components can subsequently be easily mixed by shaking the package.
A top layer or closure covering at least a part of the compartment
will then be removed to allow the diffusion of the active
ingredient into the surrounding air. A package of this type, used
for a different purpose, is described for example in U.S. Pat. No.
4,798,288, the content of which is hereby included by reference.
The person skilled in the art of air-fresheners will appreciate
that many other types of commonly used air-freshener packages will
fulfill the objective of the invention.
In another preferred embodiment of the invention, at least a part
of the wall of the compartment containing the absorbing material is
permeable to the vapors of the active ingredient, closure being
then not necessary. When the joint between the compartments is
broken, the solution, emulsion or suspension containing the active
ingredient will flow into the compartment containing the absorbing
material, forming a gel. The active ingredient can then diffuse
into the surrounding air through the walls of the compartment, the
removing of a top layer or closure not being necessary in this
particular case.
In a further preferred embodiment of the air-freshener device
according to the present invention, said device comprises a
reservoir containing as appropriate hydrophilic solvent. The gel is
located in the upper part of said reservoir. Means are provided to
ensure an appropriate supply of a hydrophilic solvent to the gel.
As hydrophilic solvent, there will be used the same liquids as for
the preparation of the solution, emulsion or suspension containing
the active ingredient. The most preferred hydrophilic solvent is
water.
By this, the gel will remain completely moistened by the liquid
throughout its whole lifetime, i.e. until all active compound has
evaporated. As mentioned above, it was found that the hydrophilic
solvent, in particular water, acts as an evaporation aid for the
active ingredient. There is observed a lower evaporation rate for
said active ingredient if the gel is not properly moistened,
respectively hydrated, by a hydrophilic solvent, even if there
remains an amount of active ingredient in the gel which should not
yet give rise to said lower evaporation rate. By keeping the gel
sufficiently moistened, an efficient and complete evaporation of
the active ingredient is ensured, resulting in a prolonged lifetime
of the air-freshener.
Devices for providing an appropriate supply of hydrophilic solvent
to the gel are known to a person skilled in the art. For example,
one possibility is to provide said supply by capillary action.
Simple capillaries or small tubes, made from, for example, glass or
plastics, often give sufficient results. The best results, however,
were obtained by using a wick. Of course, the material and
dimensions of such wick must be chosen in a way that a sufficient
amount of solvent is supplied to the gel to keep it entirely
moistened. The necessary amount depends on the amount of gel and
its absorbing properties.
A large number of organic and inorganic materials can be used for
the wick. Examples for appropriate inorganic materials include
porous porcelain material, glass fiber, or asbestos, in combination
with a suitable binder such as, for example, gypsum or bentonite.
It is also possible to prepare wicks from powdered mineral
materials, such as, for example, clay, talc, kieselguhr, alumina,
silica or the like, singly or in combination with, for example,
wood flour, carbon powder, or activated carbon, using an
appropriate glue. Organic materials include felt, cotton, pulp,
woven and non-woven cotton fibers, woven and non-woven synthetic
fibers, and porous polymeric foams and sponges.
We could obtain particularly advantageous results with a wick
consisting of a polyester filling surrounded by perforated
polypropylene. Such a material is commercially available at
Baumgartner Papier SA, Switzerland.
The wick must be able to transport the hydrophilic solvent, in
general water, at least as quick to the gel as the solvent
evaporates from the surface of the gel.
As mentioned above, in this embodiment of an air-freshener
according to the present invention, the gel will be in a container
adjacent to the reservoir and connected to it by an appropriate
supply, preferable a wick. It is preferred when the gel sits on a
piece of absorbing material connected to the wick, like thick,
absorbent paper, for example filter paper, in order to ensure a
regular distribution of the solvent in the gel.
The container which takes up the gel is covered by a material which
is permeable to the vapors of the active ingredient, in order to
prevent the gel from falling out. To this end, a mesh may be
used.
The material permeable for the vapors is sealed by an appropriate
closure which can easily be removed by the customer after purchase,
in order to activate the air-freshening device according to the
present invention.
In this preferred embodiment of an air-freshener according to the
present invention, it is possible to simply add new water to the
reservoir once it is empty, as long as there remains active
ingredient in the gel. By this, it is for example possible to
incorporate larger amounts of fragrance in the gel and provide
air-freshening device with a prolonged lifetime in which the
reservoir simply has to be refilled from time to time by the
customer to keep the device working.
After activation, the gel of the diffusion device of the invention
should preferably have an evaporation surface of from about 10 to
about 60 cm.sup.2, preferably of from about 20 to about 40
cm.sup.2, in order to allow an effective diffusion of the active
ingredient.
The device of the present invention allows a linear and effective
release of fragrance, with only low amounts of fragrance remaining
in the gel after exhaustion of the perfume or the other active
ingredient.
The invention will now be described in further detail by way of the
following examples.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 represents the weight loss, as a function of time, of two
gels according to the invention, in comparsion with that of a
standard carrageenan gel.
FIG. 2 shows the amount of fragrance emitted by a wick-type
air-freshener according to the invention, compared to the amount of
the same fragrance emitted by a polyurethane pre-polymer
water-based gel, as a function of time.
FIG. 3 shows the results obtained from a panel testing the
intensity of the fragrance emitted from the two above-identified
gels, as a function of time.
FIG. 4 shows one embodiment of a wick-type air-freshener according
to the present invention. A reservoir 1 filled with a liquid,
preferably water, a wick 2 providing means to feed the liquid to
the gel 4 located in the upper part of the device and keeps it
moistened. The gel sits on a piece of filter paper 3 or other
material capable of absorbing the liquid and ensuring regular
moistening of the gel.
EMBODIMENTS OF THE INVENTION
EXAMPLE 1
Perfuming compositions were prepared by admixing the following
ingredients, in a variety of proportions within the ranges
indicated.
TABLE-US-00001 Range of concentrations Ingredients % by weight
Dipropylene glycol 50-70 Isobornyl acetate 5-20 Terpineol 1-5
Eucalyptus oil 0.2-3 Methyl nonyl aldehyde 0.2-3 Dihydromyrcenol
1-8 Terpinyl acetate 0.5-5
By using anyone of the perfumes thus obtained, air-fresheners
according to the invention were prepared with the following
ingredients, in the proportions indicated:
TABLE-US-00002 % by weight of gel Ingredient Gel 1 Gel 2 Gel 3
Deionised water 92 89 95 Perfume 3 6 3 Non-ionic surfactant 3 3 --
Salsorb .RTM. 2 2 2 Water soluble dye* trace trace -- *D&C
Green N* 5 from D. F. Anstead Ltd. UK
Typically, the Salsorb.RTM. containing 0.1% of its weight of water
soluble dye uniformly distributed within was added to the
previously prepared emulsion of the perfume (3% of total emulsion)
in the water containing the surfactant (3% of total emulsion),
which had been placed in a glass container, for example a small
bottle or flask of appropriate size. Upon admixture, a very soft
gel immediately formed which remained firmly in the flask even if
the latter was turned upside down.
Similar gels could be obtained in plastic containers of any desired
form, which, upon setting of the gel, could be covered with a grid
permitting evaporation of the perfume contained in the gel.
FIG. 1 shows the evolution in time of the weight loss suffered by
two gels according to the invention (gels 1 and 2 above) as the
perfume evaporates, in comparison to the behaviour of a standard
air-freshener available on the market and based on a standard
carrageenan gel containing 3% by weight of perfume. It is apparent
from this figure that the gels of the invention consistently
release a larger amount of perfume/water over the same period of
time. Intensity testing of the gel and headspace analysis
consistently shows the fragrancing to be more intense and with
improved release of fragrance components, compared to standard
gels.
EXAMPLE 2
Perfuming compositions according to those described in Example 1
were used to prepare a wick-type air-freshener with a water
reservoir and Salsorb.RTM. as absorbing material. There were used
80 g of gel in which there were incorporated 5 g of perfume. 2% by
weight of Salsorb.RTM. were used. The level of fragrance emanating
from the wick system over 4 weeks was compared to the fragrance
level emanating from a standard polyurethane pre-polymer
water-based gel containing the same fragrance in an identical
amount, by a headspace analysis of the SPME (Solid-Phase Micro
Extraction) type. The results are shown in FIG. 2, which clearly
illustrates that the wick-type air-freshener according to the
present invention releases an almost constant amount of fragrance
during the 4 weeks. The polyurethane pre-polymer based
air-freshener releases a too large amount of fragrance in the
beginning, which amount fastly drops to low levels after some
weeks.
These results were confirmed by a semi-expert panel which rated the
intensity of the fragrance emitted by both devices after 1, 2, 3
and 4 weeks on a scale from 1 to 7. The results are shown in FIG.
3. The panel results clearly confirmed that the polyurethane type
air-freshener gives an intense odor shortly after it activation,
which however drops steadily with time. The wick-type air-freshener
according to the present invention, on the contrary, gives a
practically constant odor over 4 weeks.
* * * * *