U.S. patent application number 09/837910 was filed with the patent office on 2001-10-18 for gel type vapor release device.
Invention is credited to Hurry, Simon, Williams, Jonathan L..
Application Number | 20010030243 09/837910 |
Document ID | / |
Family ID | 11004767 |
Filed Date | 2001-10-18 |
United States Patent
Application |
20010030243 |
Kind Code |
A1 |
Hurry, Simon ; et
al. |
October 18, 2001 |
Gel type vapor release device
Abstract
The present invention is drawn to a device for perfuming ambient
air or closed spaces. The said device comprises water or an
appropriate hydrophilic solvent containing said volatile active
ingredient and an absorbing material chosen from superabsorbents,
starch based systems, chemically modified cellulose and natural gum
and which are capable of forming a gel with water or said
hydrophilic solvent, both components being adapted to be mixed with
each other in order to achieve the diffusion of said volatile
ingredient from the said gel. The components are mixed with each
other to form said gel from which the perfume or a deodorizing or
sanitizing agent, or an insect repellent, diffuses uniformly and
over a prolonged period of time into the surrounding air.
Inventors: |
Hurry, Simon; (Ascot,
GB) ; Williams, Jonathan L.; (London, GB) |
Correspondence
Address: |
WINSTON & STRAWN
200 PARK AVENUE
NEW YORK
NY
10166-4193
US
|
Family ID: |
11004767 |
Appl. No.: |
09/837910 |
Filed: |
April 19, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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09837910 |
Apr 19, 2001 |
|
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PCT/IB99/01721 |
Oct 20, 1999 |
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Current U.S.
Class: |
239/60 ;
239/34 |
Current CPC
Class: |
A61L 9/12 20130101; A61L
9/048 20130101 |
Class at
Publication: |
239/60 ;
239/34 |
International
Class: |
A61L 009/04 |
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) an absorbing material selected from superabsorbent
substances, starch based systems and chemically modified cellulose,
wherein the absorbing material is capable of forming a gel with the
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
or 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 absorbing material
is a superabsorbent substance.
9. The device according to claim 8, 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 of 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 absorbing material
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, preferably
from about 1% to about 6% by weight of the solution.
13. The device according to claim 1, wherein the absorbing material
is a superabsorbent of the sodium polyacrylate/polyacrylic acid
type which is present in an amount of from about 0.1% to about 15%,
preferably of from about 2% to about 5% 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 absorbing material
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 absorbing
material 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
absorbing material with the hydrophilic medium to form the gel.
17. The device according to claim 15, which further comprises a
rupturable or burstable joint or wall common to both compartments,
one of which contains the absorbing material, the other compartment
enclosing the hydrophilic medium comprising the volatile active
ingredient.
18. The device according to claim 15, wherein the compartment
containing the absorbing material has a wall permeable to the
vapors of the active ingredient and which wall can be sealed by an
appropriate removable closure.
19. The device according to claim 1, wherein the gel is present in
the form as obtained after mixing the absorbing material, 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 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 device according to claim 1, wherein the gel resulting from
the admixture of the active ingredient and the absorbing material
has an evaporation surface of from about 10 to about 60 cm.sup.2,
preferably of from about 20 to 40 cm.sup.2.
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. The method according to claim 26, wherein the activation is
carried out by mixing the absorbing material and the hydrophilic
solvent containing the active ingredient.
28. The method according to claim 25, wherein the activation
comprises removing the seal covering the container with the
gel.
29. A gel resulting from the mixing of an absorbing material
selected from superabsorbent substances, starch-based systems and
chemically modified cellulose, 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.
30. The gel according to claim 29, wherein the hydrophilic medium
is water or a water-based solvent and that the absorbing material
is a superabsorbent substance.
31. The gel according to claim 30, wherein the superabsorbent is a
cross-linked sodium polyacrylate/polyacrylic acid polymer.
Description
TECHNICAL FIELD AND PRIOR ART
[0001] 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.
[0002] 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.
[0003] 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.
[0004] 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.
[0005] 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
[0006] 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.
[0007] 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.
[0008] We have found that the diffusion systems according to the
invention provide a very uniform and prolonged diffusion of the
active ingredient.
[0009] 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.
[0010] 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).
[0011] 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.
[0012] 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.
[0013] 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.
[0014] 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.
[0015] 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.
[0016] 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 esters 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.
[0017] 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.
[0018] As a perfume or perfuming ingredient there can be used in
the device of the invention any ingredient or mixture of
ingredients currently used in perfumery. The latter can be made of
discreet chemicals; more often, however, it will be a more or 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.
[0019] 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.
[0020] 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/polyacrylic 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.
[0021] 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.
[0022] 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.
[0023] 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.
[0024] 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.
[0025] The activation of an air-freshening device according to the
present invention can be accomplished in different ways.
[0026] 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.
[0027] 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.
[0028] 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 compartments 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.
[0029] 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.
[0030] In a further preferred embodiment of the air-freshener
device according to the present invention, said device comprises a
reservoir containing an 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.
[0031] 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.
[0032] 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.
[0033] 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.
[0034] 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.
[0035] 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.
[0036] 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.
[0037] 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.
[0038] 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.
[0039] 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.
[0040] 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.
[0041] 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.
[0042] The invention will now be described in further detail by way
of the following examples.
BRIEF DESCRIPTION OF THE DRAWINGS
[0043] FIG. 1 represents the weight loss, as a function of time, of
two gels according to the invention, in comparison with that of a
standard carrageenan gel.
[0044] 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.
[0045] 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.
[0046] 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
[0047] Perfuming compositions were prepared by admixing the
following ingredients, in a variety of proportions within the
ranges indicated.
1 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
[0048] By using anyone of the perfumes thus obtained,
air-fresheners according to the invention were prepared with the
following ingredients, in the proportions indicated:
2 % 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.degree. 5
from D. F. Anstead Ltd. UK
[0049] 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.
[0050] 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.
[0051] 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
[0052] 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.
[0053] 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.
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