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Patent Abstract
A non-aqueous, single phase, non-thickened liquid air freshener
or insecticidal composition having a flashpoint of greater than
about 62.degree. C. is provided. The composition contains: a) a
polar solvent; b) up to about 10 wt % of a non-polar aliphatic hydrocarbon
solvent; and c) a fragrance or an insecticide. The composition may
be dispensed from a device having a chamber with at least one wall
made of a material which enables a vapor of the composition to diffuse
out of the chamber.
Patent Claims
I claim:
1. A non-aqueous, single phase, non-thickened liquid air freshener
or insecticidal composition having a flashpoint greater than about
62.degree. C. comprising: a) a polar solvent; b) up to about 10
wt % of a non-polar aliphatic hydrocarbon solvent; and c) a fragrance
or an insecticide.
2. The composition according to claim 1, wherein the composition
is an air freshener and comprises a fragrance.
3. The composition according to claim 1, wherein the polar solvent
has an evaporation rate less than about 100 and the non-polar solvent
has an evaporation rate less than about 16.
4. The composition according to claim 1, wherein the polar solvent
comprises a glycol ether.
5. The composition according to claim 4, wherein the polar solvent
is selected from the group consisting of a (C.sub.1-4 alkyl)glycol(C.sub.1-4
alkyl) ether, a di(C.sub.1-4 alkyl)glycol(C.sub.1-4 alkyl)ether,
a (C.sub.1-4 alkyl)glycol di(C.sub.1-4 alkyl)ether, a di(C.sub.1-4
alkyl)glycol di(C.sub.1-4 alkyl)ether and a tri(C.sub.1-4 alkyl)glycol(C1-4
alkyl) ether.
6. The composition according to claim 4, wherein the polar solvent
is selected from the group consisting of 3-butoxypropan-2-ol, propylene
glycol monomethyl ether, tripropylene glycol methyl ether, dipropylene
glycol methyl ether, dipropylene glycol dimethyl ether, dipropylene
glycol n-propyl ether, dipropylene glycol mono n-butyl ether, tripropylene
glycol mono n-butyl ether and propylene glycol n-butyl ether.
7. The composition according to claim 1, wherein the non-polar
solvent is a C.sub.10-18 alkane or a cycloparaffinic hydrocarbon.
8. The composition according to claim 1, wherein a weight ratio
of the polar solvent to the non-polar solvent is about 1:1 to about
6:1.
9. The composition according to claim 8, wherein the weight ratio
is about 2:1 to about 5:1.
10. An air freshener or insecticidal device comprising a chamber
containing a composition according to claim 1, wherein the chamber
comprises at least one wall comprising a material which enables
a vapor of the composition to diffuse out of the chamber.
11. The device according to claim 10, wherein the wall comprises
a polyethylene.
12. The device according to claim 10, wherein the wall has a thickness
of about 20 to about 100 micrometers.
Patent Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of International Application
No. PCT/GB01/00304, filed Jan. 26, 2001, which was published in
the English language on Aug. 9, 2001, under International Publication
No. WO 01/56619 A1 and the disclosure of which is incorporated herein
by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to liquid air freshener and
insecticidal compositions. particularly those which can be evaporated
from a container through a wall such as a membrane.
[0003] Air freshener and insecticidal compositions are well-known.
These are used to fragrance or deodorize an environment or to control
insects. Such compositions have traditionally been in solid form,
but now may be in liquid, including thickened liquid or gelled,
form. The liquid is generally held in a chamber.
[0004] The chamber may have a wicking arrangement such that the
composition is evaporated from a wall which is in the form of a
porous surface. Alternatively, the chamber may have at least one
wall of a material that is permeable to the vapors of the composition,
thereby allowing controlled release of the vapors over a period
of time. Such an arrangement is described in U.S. Pat. No. 4,534,509,
in which the fragrance is enclosed in an impermeable bag with a
weak seal along one edge, which prevents escape of the vapors as
long as the package is sealed. This is then contained within a larger
pouch of a suitable permeable membrane When sufficient pressure
is applied by the user, the weak seal ruptures and the volatile
composition flows from the inner pouch into the outer permeable
pouch, thereby allowing release of the vapors.
[0005] An alternative arrangement is described in U.S. Pat. No.
4,634,614 in which the permeable wall is covered with a thin layer
of paper coated with a polymer sheet to which adheres a protective
sheet which is impermeable to the vapors of the composition. The
paper layer tears when subjected to a peeling force such that the
protective layer is readily removed and the volatile substance is
covered only by a layer of material which is permeable to the vapors,
thereby allowing release of the vapors.
[0006] A similar arrangement is described in International Patent
Publication WO 98/23304 which comprises a membrane laminate having
a plurality of layers. The outer layers of the laminate are impermeable
to the composition and its vapors, and thus prevent escape of the
vapors as long as the package is sealed. Upon opening, delamination
occurs at the interface between two selected layers of the laminate,
such that the composition is covered only by a layer of the material
which is permeable to the vapors of the composition.
[0007] In such devices severe constraints are placed on the composition
contained within the chamber. In particular, it must be able to
evaporate satisfactorily through the wall relatively constantly
throughout the life of the device. The device must also be storable
for a long time without the composition affecting the properties
of the wall or other parts of the chamber. Furthermore, the rate
of evaporation of the composition must be controllable by the manufacturer
such that a suitable lifetime of the device can be provided, which
is generally of the order of about 45 days. It is desirable that
after approximately this period, a suitable end of life indicator
is provided so that the consumer can see when it is appropriate
to buy a new device or refill composition for such a device. Suitable
indication means are, for example, a significant visible reduction
in the amount of the composition in the device, a change in color
of the composition, or a change in form of the composition, for
example from a liquid to a non-flowing gel.
[0008] In prior art devices of the type in which a composition
is always in contact with the wall of a chamber and evaporates out
of the chamber through said wall, there is a relatively small amount,
for example about 3 g, of the composition present. In order to provide
effective fragrancing for a lifetime of about 45 days, the composition
must have a high concentration of fragrance with consequently only
a small amount of solvent present. The solvent is chosen such as
to aid diffusion of the fragrance through the wall of the chamber.
A non-polar solvent is generally used since such a solvent has good
diffusion properties through such walls.
[0009] It is now desired to produce such devices which may contain
a greater quantity of liquid composition since some consumers regard
this as beneficial. In order to obtain appropriate fragrancing or
insecticidal properties under ambient conditions (i.e. at room temperature),
it is not possible simply to increase the amount of composition
present because this will increase the lifetime of the device. This
may not be desirable when a lifetime of about 45 days is required.
Furthermore, relatively constant fragrancing throughout the lifetime
of device may not be achievable. Additionally, and more importantly,
using a larger amount of the composition in the chamber will increase
the amount of non-polar solvent present in the chamber. It has been
found that such a quantity of non-polar solvent is sufficient to
damage the wall during storage or use of the device, which will
mean that the device will not function properly once it is opened
or has been used for a short time. For example, if the wall is of
the laminated membrane type, the membrane may suffer delamination.
[0010] It is not possible simply to replace the non-polar solvent
with a polar solvent. Polar solvents are known to have poorer evaporation
characteristics through membranes, and in particular will not normally
pass through membrane walls of the type used in air freshener or
insecticidal devices.
[0011] It is also desirable that a suitable end-of-life indication
be provided for devices of this type so that the consumer can see
when it is appropriate to buy a new device or refill composition
for such a device. Suitable indication means include the visible
absence of any composition in the device. Thus, it is particularly
desirable for the composition to be formulated such that no residue
of the solvent remains. The end-of-life indication is then simply
when all of the solvent of the composition has disappeared, i.e.
has evaporated out of the device.
BRIEF SUMMARY OF THE INVENTION
[0012] A non-aqueous, single phase, non-thickened liquid air freshener
or insecticidal composition having a flash point of greater than
about 62.degree. C. is provided. The composition comprises:
[0013] a) a polar solvent;
[0014] b) up to about 10 wt % of a non-polar aliphatic hydrocarbon
solvent; and
[0015] c) a fragrance or an insecticide.
DETAILED DESCRIPTION OF THE INVENTION
[0016] A composition has been discovered which can be used in larger
quantities in an air freshener or insecticidal device which has
the appropriate evaporation characteristics through a wall membrane,
and which does not destroy or damage the wall during storage or
use of the device. Particularly, by using a mixture of a particular
polar solvent and a particular non-polar solvent, the evaporation
characteristics of the composition can easily be controlled by the
manufacturer by altering the relative proportions of the two components
and by an appropriate choice of each component. In particular, in
the present invention the amount of non-polar solvent in the composition
is not too high and thus the membrane wall is not damaged or destroyed.
[0017] It is known that the polar solvent by itself does not easily
pass through the permeable membrane walls of the types used in air
fresheners and insecticide devices and therefore does not provide
adequate evaporation characteristics. It has surprisingly been found
that when it is used in conjunction with the non-polar solvent,
the polar solvent will have appropriate characteristics to dissolve
and evaporate with the fragrance or insecticide and will not damage
or destroy the membrane wall. Therefore, using a combination of
a polar solvent and a non-polar solvent will provide the composition
with appropriate characteristics for use in an air freshening or
insecticidal device having a wall through which the composition
diffuses.
[0018] The polar solvent may be chosen from a wide range of solvents,
such as glycol ethers. Desirably the glycol ether is a (C.sub.1-4
alkyl)glycol(C.sub.1-4 alkyl) ether, di(C.sub.1-4 alkyl)glycol(C.sub.14
alkyl)ether, (C.sub.1-4 alkyl)glycol di(C.sub.1-4 alkyl)ether, di(C.sub.1-4
alkyl)glycol di(C.sub.1-4 alkyl)ether or tri(C.sub.1-4 alkyl)glycol(C.sub.1-4
alkyl) ether. The alkyl groups may have 1, 2, 3 or 4 carbon atoms
and may be, for example, methyl, ethyl, n-propyl, i-propyl, n-butyl,
i-butyl, s-butyl or t-butyl groups.
[0019] For example, the polar solvent may be 3-butoxypropan-2-ol,
commercially available as Dowanol PnB.TM.; propylene glycol monomethyl
ether, commercially available as Dowanol PM.TM.; tripropylene glycol
methyl ether, commercially available as Dowanol TPM.TM.; dipropylene
glycol methyl ether, commercially available as Dowanol DPM.TM.;
dipropylene glycol dimethyl ether, commercially available as Proglyde.TM.
DMM; dipropylene glycol n-propyl ether, commercially available as
Dowanol DPnP.TM.; dipropylene glycol mono n-butyl ether, commercially
available as Dowanol DPnB.TM.; tripropylene glycol mono n-butyl
ether, commercially available as Dowanol TPnB.TM.; or propylene
glycol n-butyl ether.
[0020] A single polar solvent, or a mixture of two or more polar
solvents, may be used.
[0021] The non-polar aliphatic hydrocarbon solvent may also be
chosen from a wide variety of such solvents. Examples are linear,
cyclic or branched hydrocarbons, including cycloparaffinic hydrocarbons.
Preferred hydrocarbons are linear or branched alkanes such as C.sub.8-18
alkanes, preferably C.sub.9-16 alkanes, more preferably C.sub.9-12
alkanes or C.sub.11-15 alkanes. A single non-polar solvent, or a
mixture of two or more non-polar solvents, may be used. Often, however,
a mixture of hydrocarbons is used since it is not necessary to use
a single hydrocarbon and separation of different hydrocarbons is
costly.
[0022] Preferred non-polar solvents are mixtures of C.sub.9-12
and C.sub.11-15 alkanes such as those commercially available as
Isopar G.TM., Isopar H.TM., Isopar J.TM., Isopar K.TM., Isopar M.TM.,
Isopar L.TM. and Isopar MB.TM., as well as mixtures of C.sub.3-16
alkanes such as those commercially available as Isopar p.TM., and
distillates commercially available as Isopar V.TM.. Other preferred
non-polar solvents are aliphatic hydrocarbons commercially available
as Norpar 12.TM. and Norpar 15.TM., and cycloparaffinic hydrocarbons
commercially available as Exxsol D60.TM., Exxsol D80.TM., Exxsol
D 100.TM., Exxsol D220.TM., Exxsol D230.TM., Exxsol D100s.TM., Exxsol
D110.TM., Exxsol D120.TM. and Exxsol D140.TM..
[0023] The composition has a flash point of greater than about
62.degree. C., preferably greater than about 70.degree. C. This
is to ensure that the composition is not a fire hazard in use. Individual
components of the composition may have flash points of less than
these temperatures, so long as the final composition meets this
requirement. Desirably the flash point of each component is as high
as possible. A correlation has been found between the flash point
of a compound and its rate of evaporation relative to n-butyl acetate.
Evaporation rates can be expressed on a scale in which n-butyl acetate
has an evaporation rate of 100. A higher value means that the compound
has a greater rate of evaporation, and a lower flash point. In general,
the evaporation rate of the polar solvent for use in the composition
is preferably less than about 100. The evaporation rate of the non-polar
aliphatic hydrocarbon solvent in the combination is preferably less
than about 16.
[0024] The composition desirably comprises at least about 15 wt
% of the polar solvent, preferably about 15 to about 40 wt %, more
preferably about 15 to about 30 wt % of the polar solvent based
on the total weight of the composition. The composition comprises
less than about 10 wt % of the non-polar aliphatic hydrocarbon solvent,
preferably about 1 to about 10 wt %, more preferably about 3 to
about 8 wt %, most preferably about 4 to about 7 wt %, based on
the total weight of the composition. The weight ratio of the polar
solvent to the non-polar solvent is desirably about 1:1 to about
6:1, more preferably about 2:1 to 5:1, and most preferably about
3:1 to about 4:1. The amounts of each component and the weight ratio
are, of course, chosen to provide a composition with appropriate
characteristics.
[0025] The composition also comprises a fragrance when it is to
be an air freshener composition, or an insecticide when it is to
be an insecticidal composition. Air freshener fragrances are well-known
to those skilled in the art. Any air freshener fragrance or fragrance
composition compatible with the membrane may be used. Some fragrance
compositions also contain a polar or non-polar solvent falling within
the definitions set out above, or compounds which have an air freshening
or deodorizing effect but which also act as such a solvent Any such
solvent or compounds in the fragrance composition which is added
to the final composition is to be taken into account when calculating
how much polar solvent or non-polar solvent is present in the final
composition. In particular, it is important for the total content
of non-polar aliphatic hydrocarbon solvent in the composition to
be less than about 10 wt %. Any suitable insecticide can be used.
[0026] The fragrance is desirably present in an amount of about
50 to 80 wt % of the total composition, preferably about 60 to 75
wt %.
[0027] The composition may also comprise one or more optional components
which are conventionally used in the art. For example, a dye or
ultra-violet absorbing agent, such as dihydroxybenzophenone, may
be included to stabilize the fragrance or dye if necessary.
[0028] The amount of composition which can be contained in the
device is not limited. However, since the composition is compatible
with membrane wall, a larger amount of composition can be held in
the device than has previously been feasible. For example, about
5g to about 50 g of composition can be used, preferably about 5
g to about 20 g, more preferably about 8 to about 10 g.
[0029] An air freshener or insecticidal device is also provided
which comprises a chamber containing a composition as defined above,
said chamber having at least one wall of a material which enables
the vapors of the composition to diffuse into the environment in
which the device is placed.
[0030] The wall is permeable such that it allows the fragrance
or insecticide to diffuse into the environment. It may be made of
any suitable material, for example polyethylene or paper. The wall
may have another layer laminated to either or both surfaces thereof,
for example a layer or layers made of a polymer such as polyethylene.
The wall may, in particular, be that described in U.S. Pat. No.
4,634,614. Alternatively the wall may be that described in WO 98/23304.
In the latter document there is described a wall in the form of
a permeable polyethylene membrane. The wall preferably is thin so
as to allow a suitable release rate of the composition. For example,
the wall may have a thickness of about 20 to about 100 micrometers,
preferably about 30 to about 70 micrometers, more preferably about
40 to about 60 micrometers.
[0031] In order to prevent the device from releasing fragrance
or insecticide before it is used, the wall may be covered by an
impermeable sheet which is removed before the device is used. For
example, the sheet may simply be peeled off the wall or otherwise
removed and discarded. The sheet may be made of, for example, a
laminate such as polyethylene laminated with a metal such as aluminum.
In WO 98/23304, the impermeable sheet is a laminate of polyethylene
and ethylene-vinyl alcohol copolymer. Alternatively, a number of
vents may be provided to allow for an adjustable release of the
fragrance or insecticide.
[0032] This invention will best be further understood in connection
with the following, non-limiting Examples.
EXAMPLE 1
[0033] Compositions containing a single polar or non-polar solvent
or comprising a polar solvent and a non-polar solvent were tested
in an air freshener device to determine their weight loss through
a membrane over time.
[0034] The solvents chosen were as follows:
1 Non-Polar Solvents (commercially available from Exxon) 1. Isopar
M .TM. a mixture of C.sub.11-15 iso-alkanes having a flash- point
of 79.degree. C. and an evaporation rate of <1. 2. Isopar L .TM.
a mixture of C.sub.11-15 iso-alkanes having a flash- point of 67.degree.
C. and an evaporation rate of 3. 3. Isopar P .TM. a mixture of C.sub.13-16
iso-alkanes having a flash- point of 109.degree. C. and an evaporation
rate of <1. 4. Norpar 12 .TM. a mixture of aliphatic hydrocarbons
derived from petroleum having a flashpoint of >66.degree. C.
and an evaporation rate of 1. 5. Exxsol D60 .TM. a mixture of aliphatic
cycloparaffinic hydro- carbons having a flashpoint of 63.degree.
C. and an evaporation rate of 2.5. 6. Exxsol D80 .TM. a mixture
of aliphatic cycloparaffinic hydro- carbons having a flashpoint
of 75.degree. C. and an evaporation rate of <1. Polar Solvents
(commercially available from Dow Chemicals) A. Dowanol PnB .TM.
3-butoxypropan-2-ol having a flashpoint of 63.degree. C. and an
evaporation rate of 7. B. Dowanol PM .TM. propylene glycol monomethyl
ether having a flashpoint of 31.degree. C. and an evaporation rate
of 70. C. Dowanol DPM .TM. dipropylene glycol methyl ether having
a flash- point of 75.degree. C. and an evaporation rate of 3. D.
Proglyde DMM .TM. dipropylene glycol dimethyl ether having a flash-
point of 65.degree. C. and an evaporation rate of 80.
[0035] The above evaporation rates were determined relative to
n-butylacetate which has an evaporation rate of 100; the value for
Proglyde DMM.TM. was calculated as the product of the molecular
weight and the vapor pressure (mm Hg at 20.degree. C.). A high flashpoint
generally gives a low evaporation rate.
[0036] The above solvents were used singly or combined in weight
ratios of 75:25, 50:50 and 25:75. 8 g of each of the compositions
was sealed in thermoformed reservoirs having a membrane laminate
of linear low density polyethylene and aluminum as described in
WO 98/23304 on one side thereof. The devices were activated by peeling
back the aluminum laminate layer to expose the membrane. The devices
were stored at ambient conditions and the weight loss monitored
over 15 days.
[0037] The following tables set out the weight loss percentages
over time:
2 8 days 1 days 5 days Non-polar Solvents 1. Isopar M 14% 19% 24%
2. Isopar L 34% 45% 60% 3. Isopar P 2% 3% 3% 4. Norpar 12 35% 44%
55% 5. Exxsol D60 57% 68% 79% Polar Solvents A. Dowanol PnB 7% 9%
11% B. Dowanol PM 2% 2% 2.5% C. Dowanol DPM 2% 3% 3.5% D. Proglyde
DMM 20% 25% 31% Combi- nation Polar/ Mixtures 75:25 Mixtures 50:50
Mixtures 25:75 Non- 8 11 15 8 11 15 8 11 15 Polar days days days
days days days days days days A:1 28% 35% 42% 16% 20% 26% A:2 29%
37% 45% 38% 48% 60% 34% 47% 60% A:3 45% 59% 75% 11% 15% 20% 8% 10%
12% A:4 50% 63% 74% 52% 66% 78% 27% 33% 40% A:5 56% 67% 77% 42%
54% 66% 28% 32% 38% A:6 59% 73% 86% 32% 40% 50% 24% 30% 37% B:1
25% 31% 39% 29% 38% 49% 20% 26% 33% B:2 46% 57% 70% 48% 63% 77%
30% 34% 38% B:3 12% 16% 20% 12% 17% 21% 11% 16% 20% B:4 46% 58%
70% 69% 83% 95% 25% 29% 31% B:5 69% 81% 89% 72% 85% 89% 33% 38%
41% B:6 46% 54% 61% 51% 62% 75% 31% 39% 46% C:1 23% 30% 38% 28%
34% 42% C:2 58% 70% 85% 36% 47% 56% 19% 23% 29% C:3 12% 17% 21%
12% 16% 20% 8% 10% 12% C:4 50% 63% 73% 45% 53% 62% 26% 33% 40% C:5
40% 51% 60% 63% 78% 86% 50% 52% 56% C:6 32% 40% 50% 30% 38% 47%
19% 22% 28% D:1 28% 36% 46% 41% 52% 66% 20% 27% 33% D:2 47% 57%
69% 42% 59% 78% 46% 51% 58% D:3 21% 28% 36% D:4 57% 66% 73% 59%
75% 88% 40% 45% 48% D:5 69% 81% 89% 68% 85% 95% 44% 58% 71% D:6
44% 53% 62% 48% 62% 76% 40% 52% 68%
[0038] It can be seen that the weight loss can be controlled by
choosing appropriate solvents and by choosing appropriate ratios
of the two solvents.
EXAMPLE 2
[0039] A composition containing a fragrance was prepared to provide
a composition for use in a membrane/liquid reservoir system having
a fill weight of 9 g.
3 Component Weight Percent Exxsol D60 .TM. 6 Proglyde DMM .TM.
24 Citrus fragrance 68 2,4-dihydroxybenzophenone 2 (u.v. absorber)
[0040] The fragrance contained some polar solvent, namely 0.3%
dipropylene glycol, 9.2% butoxypropanol and 0.9% triethyl citrate.
The composition was sealed in the same device as used in Example
1, except that the membrane thickness was reduced from 60 micrometers
to 40 micrometers.
[0041] It will be appreciated by those skilled in the art that
changes could be made to the embodiments described above without
departing from the broad inventive concept thereof. It is understood,
therefore, that this invention is not limited to the particular
embodiments disclosed, but it is intended to cover modifications
within the spirit and scope of the present invention as defined
by the appended claims.
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