Dispenser for a product of a liquid to pasty consistency comprising a safety device

A pressurized container (1) containing a fluid product to be dispensed and a propellant gas. The container includes a valve for dispensing the product that includes a heat-sensitive safety device (D) for opening the valve and causing the inside of the container to permanently communicate with the atmosphere when the temperature inside the container exceeds a predetermined threshold temperature. The safety device (D) includes a stopper (106) made of a material that is thermodeformable at the threshold temperature. The stopper closes an orifice (105) in an actuating stem of the valve when the threshold temperature is not exceeded, and opens the orifice when the threshold temperature is exceeded.

The present invention relates to a pressurized container containing a fluid 
product to be dispensed and also a propellant gas, this container being 
provided with a safety device preventing the risks of excessive pressures 
when the ambient temperature rises. The object of the invention is, more 
particularly, the use of a container made of a metallic or plastic 
material provided with such a safety device. 
Generally, pressurized containers of this kind are used in different fields 
of application and contain, for example, cosmetic products, industrial 
products or household products. These products are not always used in 
ideal conditions. Indeed it happens rather frequently that such a product 
is stored and/or used at high temperatures, for example, in full sunlight. 
It is known that with an increase in the ambient temperature the internal 
pressure in a pressurized container increases substantially, in particular 
when it contains a liquefied propellant gas. In extreme conditions, there 
is the risk that the excessive pressure produced by high temperatures will 
then cause the container to burst and thus cause injuries to the user. 
Generally, the pressurized container presently used for the dispensing of a 
fluid product are constituted by an aluminium can or a tin can. These 
metal cans are not sensitive to heat. The pressurized cans made of a 
plastic material are at present not used, because it is also known that 
the plastic materials intended for these cans do not withstand high 
temperatures. Indeed, these plastic materials start to soften above a 
critical threshold temperature (in particular upwards from 50.degree. C.). 
When it is intended to replace a metal container by a plastic container, a 
certain number of precautions have therefore to be taken. To avoid any 
risk of deterioration of the container, it is necessary, for example, to 
depressurize the container before the inside of the container accidentally 
reaches the critical temperature, this depressurization having to be 
effected at a specified temperature in an extremely reliable and 
reproducible manner. 
A container comprising a safety device which ensures this depressurization 
has already been proposed, for example, in our FR-A-2685303. This device 
is provided with a wall having an orifice closed by an elastomeric 
stopper, the exposure to atmospheric pressure being effected by means of a 
fixed element, by rupture of a fragile zone of the stopper, this zone 
being disposed in the container and being displaced solely under the 
effect of the internal pressure. However, tests have shown that it is 
difficult to control in a reliable manner the conditions of the rupture of 
the fragile zone. Moreover, the assembly of such a container entails 
additional manufacturing costs which are relatively high. 
Moreover, U.S. Pat. No. 4,407,432 discloses a pressurized container which 
has a device for exposure to atmospheric pressure and a push button 
mounted on a dispensing valve, this container increasing in volume when a 
predetermined threshold temperature has been reached. This container is 
mounted in a frame, so that due to the increase in volume of the 
container, pressure is exerted on the push button producing the ejection 
of the product through the valve in the direction towards the push button. 
The push button includes a dispensing conduit and a duct for exposure to 
the atmospheric pressure, obturated by a thermofusible stopper. When the 
critical temperature is reached, this button melts and produces the 
depressurization of the container. The container mounted in the frame has 
the drawback of being bulky, inconvenient and expensive. 
SUMMARY OF THE INVENTIONS 
In searching for a safety device that is very reliable and easy to use, the 
Applicant has found that by using a valve provided with a safety device 
having a stopper made of a material which is thermodeformable, even 
thermofusible, at a specified threshold temperature, it was possible, 
surprisingly, to control with great reliability the accidental excessive 
pressure in a pressurized container, which pressure is produced by 
excessive heat. Moreover, the solution proposed by the present invention 
is simple to obtain and is economically advantageous. 
Thus it is the object of the present invention to provide a pressurized 
container containing a fluid product to be dispensed and also a propellant 
gas, this container being provided with a heat-sensitive safety device. 
Thus the present invention provides a pressurized container containing a 
fluid product to be dispensed and a propellant gas, this container being 
provided with a valve for dispensing the product, this valve being fitted 
with a heat-sensitive device capable of causing the valve to open and of 
causing the inside of the container to permanently communicate with the 
atmosphere when the temperature inside the container exceeds a 
predetermined threshold temperature. 
Generally, the container comprises a bottom and, if applicable, a fastening 
cup which is mounted on the end opposite to the bottom and is intended to 
fix the dispensing valve on the container. 
Advantageously, the safety device is constituted by a stopper (or a 
partition) made of a material that is thermodeformable at and above the 
threshold temperature, this stopper (or the partition) (i) normally 
obturating, at the ambient temperature, an orifice which causes the inside 
of the container to communicate with the atmosphere, and (ii) releasing 
this orifice when the threshold temperature has been exceeded. 
This orifice is, in particular, arranged in the wall of an actuating stem 
slidably mounted in the valve, actuation of this stem being capable of 
causing the ejection of a dose of the product. More precisely, the orifice 
is formed in that portion of the valve stem which is accommodated inside 
the valve body. The actuation of the valve is preferably effected by axial 
depression of the actuating stem. However, it is also possible to choose a 
stem capable of being actuated by lateral rocking. In accordance with the 
invention, the orifice may be arranged either at the bottom of the stem or 
in its side wall. 
Advantageously, the diameter of the orifice may vary between 0.1 mm and 2.5 
mm. This orifice is obturated by a stopper of a material which is 
thermodeformable, or even thermofusible. 
Thus, when the container is exposed to heat, the internal temperature of 
the container rises, entailing an increase in the internal pressure. When 
the threshold temperature has been reached or exceeded, the 
thermodeformable material softens or is liquefied and unblocks the passage 
between the inside of the container and the atmosphere. The safety device 
of the invention then becomes operational. Under the thrust of the 
internal pressure, the propellant gas and/or the product escape into the 
atmosphere via the valve stem until the container has been completely 
depressurized. 
In accordance with the above two embodiments, the thermodeformable material 
is advantageously chosen from materials having a softening point, even a 
melting point, comprised in the range extending from 45.degree. C. to 
85.degree. C. Below this temperature this material is solid, capable of 
securely adhering to the wall surrounding the orifice. Preferably, this 
thermodeformable material is a thermofusible material. More precisely it 
is chosen from materials whose softening point or melting point is below 
that constituting the wall of the container. 
Advantageously, the thermodeformable or thermofusible material is chosen 
from metal alloys, polymers, waxes, paraffins and their associations. In 
particular, this material may be chosen from the polymers of the vinyl 
ethylene/acetate copolymer-type; polymers and two-constituent epoxy resins 
having a vitreous transition temperature comprised between 20.degree. C. 
and 85.degree. C., and preferably between 45.degree. C. and 80.degree. C.; 
resins which are cross-linkable under the effect of an ultraviolet source; 
synthetic waxes such as "Dapral W440" and "Dapral W447" sold by the 
AKZO-NOBEL Company or "Cire [wax] BJ" sold by the HOECHST Company; natural 
waxes such as beeswax, carnauba wax or candellia wax; paraffins having a 
melting point comprised between 60.degree. C. and 80.degree. C.; Wood 
alloy (50% Bi, 25% Pb, 12.5% Sn and 12.5% Cd); Lipowitz alloy (50% Bi, 
26.7% Pb, 13.3% Sn and 10% Cd); eutectics such as the binary eutectic of 
In (67%) and Bi (33%), the ternary eutectic of In (51%), Bi (32.5%) and Sn 
(16.5%) and the quaternary eutectic of Bi (49.5%), Pb (17.5% ), Sn (11.6%) 
and In (21.3%). 
According to another variant of the embodiments, the stopper may be 
constituted by a membrane obturating the internal passage of the valve 
stem, and capable of softening when the internal temperature of the 
container exceeds the threshold temperature. The increase in temperature 
entails in this case an increase in the internal pressure in the 
container, producing the deformation and the displacement of the membrane, 
a perforator being provided so as to pierce the membrane when this 
displacement occurs. Advantageously, this perforator has a hollow internal 
passage one of whose ends communicates with the outside of the container. 
After the membrane has been pierced by the perforator, the pressurized gas 
passes through the orifice thus created, then escapes into the atmosphere 
via the internal passage of the perforator. 
Irrespective of the particular embodiment, the container may advantageously 
be made of a plastic material, such as, for example, PET 
(polyethylene-terephthalate), PEN (polyethylene-naphthalate) or PMP 
(polymethyl pentene), but it can also be made of aluminium, of tin, or of 
glass.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In FIG. 1 there will be seen a partial longitudinal section of a 
cylindrical container 1 elongated along a longitudinal axis A, comprising 
a neck 2 on which a conventional metal valve carrier cup 3 is fixed by 
crimping or flanging. This container contains a liquid product to be 
dispensed, and a pressurized propellant gas. At its center, the cup 3 has 
a recess 8 for receiving a valve 4. This recess 8 is radially delimited by 
a cylindrical wall 10 of revolution round axis A. This wall 10 is extended 
in an upper wall 11, generally planar and perpendicular to the axis A, 
traversed at its center by a passage 12. The cup 3 may be produced by 
cutting out and stamping a metal disk. 
The valve 4 has a valve body 9 and an actuating stem 7 capable of being 
displaced in this body along this axis A. The stem 7 passes through the 
passage 12 of the cup 3. A dispensing duct 7a is arranged in the stem 7 
for passing outwardly the product to be dispensed. This duct 7a, provided 
at its lower portion with an orifice 5 obturated by a stopper 6, is a 
blind passage extending along the direction of the axis A and connected to 
a radial duct 7b passing through the wall of the stem 7. The blind duct 7a 
opens out in the emergent end 13 of the stem 7 situated outside the 
container. When the valve is in its rest position, the radial duct 7b 
opens out at its outer end opposite an annular gasket 14, or in its 
dispensing position in a valve chamber 15 inside the valve body 9. 
The stem is provided with a radial projection 16 bearing in the closed 
position of the valve on the gasket 14. At the edge turned towards the 
container, this projection 16 bears resiliently against an end 17a of a 
helical spring 17 constituting resilient restoring means. 
The valve body 9 is substantially cylindrical and has an open bottom 18 
connected to a tube 19 capable of causing the valve chamber 15 to 
communicate with the product contained in the container 1. This bottom 
supports the other end 17b of the spring 17 with fins 21. 
On the end away from the bottom, the body 9 has, moreover, an external 
annular bead 20 engaged in the recess 8 of the cup 3 and in a leakproof 
bearing contact with the circumference of the gasket 14. The annular 
gasket 14 bears against the wall 11 of the cup and at its circumference 
comes into contact with the wall 10. The fit between the gasket 14 and the 
stem 7 is tight, so as to ensure the leakproof sliding of the latter. 
The bottom of the stem 7 is closed by the stopper 6. This stopper is made 
of a thermodeformable or thermofusible material, for example, polyethylene 
terephtalate. The rest of the stem 7 is made of a rigid plastic material, 
for example, polypropylene. 
The opening of this valve is effected in the conventional manner by 
depressing the stem. During this depression, the radial duct 7b is 
unblocked, and the product flows under the thrust of the propellant gas 
through the axial passage 7a via the valve chamber 15. 
The stopper 6 constitutes a safety device D in accordance with the 
invention which functions as follows. In fact, when the inside of the 
container reaches a high temperature, for example, 60.degree. C., the 
material of the stopper 6 melts. The bottom of the stem 7 is then released 
and the pressurized propellant gas can escape through the axial duct 7a 
until the gas has been completely discharged. 
FIG. 2 shows a variant of the embodiment of the safety device of FIG. 1. 
The parts that are identical or perform a similar function bear the same 
reference numerals as those of FIG. 1, increased by 100. The description 
of the identical parts will only be briefly repeated. 
Thus, FIG. 2 shows a valve 104 crimped in a cup 3. As compared with FIG. 1, 
it is only the actuating stem 107 that is different from the stem 7 of 
FIG. 1. It carries a closed bottom 107c moulded integrally with the rest 
of the stem. In the vicinity of this bottom 107c, a lateral orifice 105 is 
provided in the wall of the stem communicating with a blind axial passage 
107a of the stem. 
The orifice 105 is closed by a stopper 106 made of a thermodeformable or 
thermofusible material in a way similar to the stopper 6 of the embodiment 
of FIG. 1. This stopper 106 constitutes a safety device D in accordance 
with the invention which functions in a way similar to that of FIG. 1. 
The valve 204 represented in FIG. 3 has a safety device D, where, as 
compared with the embodiment of FIG. 1, the stopper 6 has been replaced by 
a membrane 206 closing an axial duct 207a of the stem 207. 
The membrane 206 is made of a thin thermodeformable sheet, for example, of 
polyethylene terephthalate, whose softening point is approximately 
65.degree. C. In the vicinity of this membrane, the stem 207 has a hollow 
perforator 220 whose tip 221 is directed towards the membrane. The inside 
222 of this perforator 220 communicates with the axial duct 207a of the 
stem 207. 
The safety device D of FIG. 3 functions as follows. When a threshold 
temperature, for example 65.degree. C., has been exceeded inside the 
container, the membrane 206 is subjected to elongation and advances under 
the effect of the pressure in the direction towards the perforator 220, as 
represented by a dotted line. The perforator pierces the membrane 206, and 
the pressurized propellant gas escapes from the container until the 
container has been completely depressurized via the hollow perforator. 
The distance between the membrane 206 and the tip 221 has been calculated 
in such a way that the elongation of the membrane should be sufficient to 
bring it into contact with the tip 221.