BE1019961A3 - PRESSURE VESSEL AND SPRAYER THAT IS CARRIED OUT AS SUCH PRESSURE VESSEL. - Google Patents

Abstract

Pressure vessel (1) with two separate compartments (2, 3) is formed by an outer sleeve (4) in which an inner bag (5) is provided, the bag (5) being filled or intended to be filled with a product (9), wherein the pressure vessel (1) is also provided with a valve (7), the outer sleeve (4) and the inner bag (5) being gas-tightly connected to the valve (7), the bag (5) is made of an elastic and extensible material such that the bag (5) can stretch into an elongated state when the bag (5) is filled with the product (9) or when the bag (5) is inflated with air or a other gas.

Description

Pressure vessel and spray can that is designed as such a pressure vessel.

The present invention relates to a pressure vessel.

More specifically, the invention relates to a pressure vessel of the type with two separate compartments, wherein a first compartment is formed by an external sleeve, in which an internal bag is provided to form a second compartment, the bag being filled with a product or intended to be filled with a product, wherein the pressure vessel is also provided with a valve for supplying product to and discharging product from the bag and wherein, both the external canister and the internal bag are connected by means of a gas-tight connection to the valve are connected.

Such pressure vessels of this type with two separate compartments are already known, for example used in the more recent spray cans of a type also known under the English names 'piston can', 'can in can', bag on valve ',' bag in valve can ', etc ....

Such known pressure vessels with two compartments offer a number of advantages over other known pressure vessels with only one compartment, which are also often used in aerosol cans, in which pressure vessels with only one compartment of propellant gas and product are stored in the same compartment.

A first advantage of such a known pressure vessel with two compartments is that the product and the propellant gas are each separately in one of the compartments, separated from each other by the aforementioned inner bag, so that no mixing of product and propellant gas occurs, so that the product lasts longer can remain stable and the product can simply be stored in the bag without having to take into account and possibly have to change its composition because of possible interactions with the propellant gas.

Another advantage of the known two-compartment pressure vessels is that, by storing the product in an internal bag that has been pressurized by a propellant in the second compartment, the product can be recovered for 99%, while in the known pressure vessels with only one compartment, usually after use, until about 5% of the product remains in the compartment.

The known pressure vessels with two compartments, for example for use in the aforementioned known spray cans, are also more environmentally friendly, since the propellant gas does not leave the pressure vessel.

Moreover, compressed air can usually be used as propellant gas, so that even after use and / or the destruction of the pressure vessel no propellant gases are released that are harmful to the environment.

Furthermore, the operation of a pressure vessel with two compartments is less noisy and such pressure vessel with two compartments can be used without problems at any angle, even upside down, which is not the case with the known pressure vessels with only one compartment, often used in certain aerosol cans, since in such a pressure vessel a suction tube for suction of product is usually provided which, for proper operation, must always be submerged in the product with its open end.

Another advantage of the known two-compartment pressure vessels is that their development is much simpler, since the same propellant can always be used to expel numerous products, both more liquid and more viscose products, whereby it is sufficient to make adjustments to the head with valve of the pressure vessel in order, for example, to change the flow opening, or, for example, to obtain different outflow rates and / or spray images in the spray head that is placed on the valve.

In addition to these numerous advantages of the pressure vessels with two compartments over the pressure vessels with only one compartment, there are also a number of disadvantages or there are also a number of aspects of the known pressure vessels with two compartments which can be improved.

A first drawback of the known two-compartment pressure vessels is that when the volume of product to be stored in the inner canister is changed, the volume of the inner bag must be adjusted by changing the shape or dimensions of the bag.

Such a change in the volume of product to be stored in the internal canister may be necessary, for example, when the volume of the external canister of the pressure vessel is changed, but just as well, such a change in the volume of product to be stored may be desired with unchanged volume and / or unaltered shape of the outer sleeve.

This means that with such a change in the volume of product to be stored or with a change in the type of product to be stored in the pressure vessel, important changes must usually also be made to the production lines for the manufacture of the pressure vessels and for filling of the pressure vessels or a completely different production line must be used, which entails a huge economic loss, loss of time and / or production loss.

Moreover, when fine-tuning and testing a new production line or a change to a production line for the pressure vessels, a lot of material is lost and a lot of waste is created.

Furthermore, the valves of the pressure vessels are produced with specially designed machines, after which they are integrated into other high-tech machines in a subsequent production step or during filling in a pressure vessel.

Such high-tech machines can be based, for example, on so-called known 'Form, Fill and Seal' machines, which are furthermore specially adapted to the needs of a certain type of pressure vessel with two compartments.

A drawback of the known two-compartment pressure vessels is therefore that, depending on the application, a different internal bag must be fitted on such a valve, which is a complicated and expensive affair and in which many adjustments to production lines and to specialized machines are required each time.

Yet another drawback of the known two-compartment pressure vessels is that their inner bags are made of a laminated material, with delamination often occurring after some time due to contact with the product.

Another drawback of the known two-compartment pressure vessels has to do with a problem in filling the bag in such pressure vessel with product.

During this filling, the product must after all be pressed under high pressure through the valve into the second compartment which is formed by the bag.

A part of the product often enters the first compartment, in other words the part of the pressure vessel between the inner bag and the outer sleeve, via the available space between the head of the valve and the seal of the inner bag around this valve.

This portion of the product may, for example, cause corrosion to the outer canister, for example because the product is chemically aggressive, so that this outer canister may fail not least because of the high pressures present in the pressure vessel after the filling of the pressure vessel with product and propellant gas, so that potentially dangerous situations can arise.

In order to avoid this, the valve housing of the valve is usually shrunk under very great force into a valve dish of the valve, whereby large tensions are introduced into the materials, which in turn gives rise to the breaking of the valve housing from the valve which with the external bus is connected and the like.

Another drawback of the known two-compartment pressure vessels is that in the event of a severe impact on the pressure vessel, for example by dropping the pressure vessel or the like, the inner bag in the pressure vessel can easily tear or break off.

The present invention therefore has for its object to provide a solution to the aforementioned and any other disadvantages.

To this end the invention relates to a pressure vessel of the type with two separate compartments, wherein a first compartment is formed by an external sleeve, in which an internal bag is provided to form a second compartment, the bag being filled with a product or intended to to be filled with a product, wherein the pressure vessel is also provided with a valve for supplying product to and discharging product from the bag and wherein, both the external sleeve and the internal bag are connected to the valve by means of a gas-tight connection and wherein the bag is made of an elastic and extensible material such that the bag can stretch into an elongated state when the bag is filled with the product or when the bag is inflated with air or other gas.

A first important advantage of such a pressure vessel according to the invention is that the inner bag can be used to store different volumes of product without having to change anything.

As a result, the same inner bag can be used for a whole range of products and in different volumes, so that in total only a few different standard sizes of the inner bags have to be manufactured, for example in accordance with small, medium and large pressure vessels.

Another advantage of such a pressure vessel according to the invention is that the production process and the filling of the pressure vessels becomes much simpler and can proceed faster.

After all, the same pressure vessel can always be used for a large number of different applications or products, so that production lines and machines in the production lines, as well as filling machines and the like, no longer have to be adapted in function of the different applications or products or no separate production lines or separate filling machines or the like must be provided for different applications or products.

The manufacture of the valves of pressure vessels according to the invention, as well as the application of an internal bag to the valves and the integration of the valves in the pressure vessel is also a lot easier with such a pressure vessel according to the invention than with the known pressure vessels with two compartments.

After all, the same kind of internal bag can be used for many different applications and products, so that fewer adjustments are needed.

Another advantage of a pressure vessel according to the invention is that it is much more resistant to an impact, for example as a result of the pressure vessel dropping.

Because the inner bag is very flexible, this bag will yield somewhat when impacted and is therefore less inclined to tear than in the known pressure vessels with two compartments.

Another reason why the pressure vessel 1 according to the invention is more resistant to an impact is due to the fact that the bottom of the extensible inner bag 5 can hit the bottom 23 of the outer sleeve 4 in the event of an impact, thereby supporting the bag 5 is against the bottom 23 and there is less chance of the bag 5 tearing under the weight of the product 9 present in the inner bag 5.

Furthermore, a pressure vessel according to the invention still has all the advantages of the pressure vessels with two compartments, most of which were listed in the introduction.

According to a preferred embodiment of a pressure vessel according to the invention, the inner bag is made of one layer of material.

Such an embodiment of a pressure vessel according to the invention naturally offers the advantage that no de-lamination can occur.

The invention also relates to a spray can which comprises a pressure vessel, as described above, or which is designed as such a pressure vessel.

The advantages of such an aerosol can according to the invention result directly from the above-described advantages of the pressure vessel, so that no further comments are needed.

With the insight to better demonstrate the features of the invention, a few preferred embodiments of a pressure vessel according to the invention, each of which is embodied as an aerosol according to the invention, with reference to the accompanying drawings, are described below. wherein: Figure 1 shows a perspective view of a pressure vessel according to the invention before the valve and the inner bag are mounted in the outer sleeve; figure 2 schematically and in perspective shows the pressure vessel from figure 1 after mounting the valve and the inner bag in the outer sleeve and after filling the bag with product; figure 3 represents a section according to the section indicated with III-III in figure 1 of a first possible embodiment in unfilled state; figure 4, analogous to figure 3, represents a cross-section of another possible embodiment of a pressure vessel according to the invention, but this time in the filled state; and, figures 5 and 6 again show a cross-section analogous to figures 3 and 4 for yet other embodiments of a pressure vessel according to the invention, again in the empty state and the filled state, respectively.

The pressure vessel 1 according to the invention shown in figures 1 and 2 is a pressure vessel 1 of the type with two separate compartments 2 and 3.

The pressure vessel 1 is in this case designed as an aerosol can 1, for which the invention is intended in the first instance, but it is not excluded that a similar technology according to the invention, as described in this text, can also be applied to pressure vessels other than these for aerosol cans 1, such as, for example, with larger pressure vessels for storing chemical products or the like.

A first compartment 2 is herein formed by the space which is bounded between an outer sleeve 4 and an inner bag 5 and which, depending on the embodiment, may also be also bounded by a portion 6 (see, for example, the embodiment of Figure 4) of a valve 7 extending between the inner bag 5 and the outer sleeve 4.

The second compartment 3 is formed by the space in the bag 5 bounded by the wall of the bag 5 and by portions 8 of the valve 7.

The intention is to store a product 9 in the inner bag 5 by feeding it along the valve 7 in order to later, during the use of the product 9, discharge it again via this valve 7.

The second compartment 3 can, if necessary, be evacuated, for example at the moment that the inner bag 5 with the valve 7 is mounted in the outer sleeve 4 to form the pressure vessel 1 or at a later time, such as, for example, just before the filling the pressure vessel 1 with product 9.

The outer sleeve 4, as well as the inner bag 5, are each connected to the valve 7 by means of a gas-tight connection.

In the embodiment of figures 1 to 3 this is achieved by the same, joint gas-tight connection 10.

Hereby a circumferential edge 11 is clamped at an opening 12 in the bag 5 between the valve 7 and a circumferential edge 13 on the outer sleeve 4 to form the aforementioned joint gas-tight connection 10.

Figure 3 shows in more detail how the valve 7 and the aforementioned gas-tight connection 10 are constructed.

The valve 7 is first of all a check valve 7 with a valve 14 which is arranged for reciprocating movement in a passage 15 of a valve housing 16 between a position in which the passage 15 is closed and a position in which the passage 15 is open.

The valve housing 16 is provided with a circular valve plate 17 which extends radially from the valve housing 16 and which is provided on the outer edge 18 with an upright collar 19 with a folded edge 20.

In the passage 15 there is also provided a spring 21 which presses the valve 14 clampingly between the valve housing 16 and a sealing rubber 22 which rests against the valve plate 17, so that in the normal condition, in which no product 9 is blown into the bag 5 under pressure or the valve 14 is not pushed away by an external force of the sealing rubber 22, the valve 14 is in a position in which the passage 15 is closed.

In the shown embodiment of Figure 3, the aforementioned folded edge 20 of the valve dish 17 is inserted with the aforementioned circumferential edge 11 at the opening 12 in the bag 5, in which case this circumferential edge 11 is partially rolled up in order to circumvent the circumferential cavity in the folded edge 20 to be filled with the material of the bag 5.

Figure 3 shows the position not yet assembled, but it is of course intended that in the aforementioned folded-over edge 20 of the valve plate 17 the circumferential edge 13 is also inserted on the outer sleeve 4 in order to clamp the edge 11 on the bag 5 between the folded edge 20 of the valve plate 17 and the circumferential edge 13 on the outer sleeve 4 to form the joint gas-tight connection 10.

It is furthermore intended to fill the first compartment 2 with a propellant gas, which can for instance be done by providing an additional valve 24 in the bottom 23 of the outer canister 4 along which such propellant gas can be introduced into the first compartment 2, but in other ways are not excluded for this.

The so-called "Under-The-Cup" process, for example, is such an alternative method of filling.

Hereby the propellant gas is introduced between the folded edge 20 of the valve plate 17 and the circumferential edge 13 on the outer sleeve 4, whereafter the gas-tight connection 10 is established by the folded edge 20 of the valve plate 17 together with the edge 11 on the pressing and shrinking the bag 5 onto the circumferential edge 13 of the outer sleeve 4.

This crimping (or so-called "clinching") to form a gas-tight connection 10 can be done by deforming the upright collar 19 during the assembly to a controlled extent, for instance such that the upright collar 19 is partially folded under the circumferential edge 13. This method of crimping is also referred to as "internal clinching" in English.

Another way of crimping to form the gas-tight connection 10 may be to roll the folded edge 20 of the valve plate 17 around the circumferential edge 13 on the outer sleeve 4. This method of crimping is also referred to as "external". called clinching.

For rolling the edge 20 on the valve plate 17 around the circumferential edge 13 of the outer sleeve 4, valves 7 have already been designed in the industry with an "extended" edge 20.

Such valves 7 with "extended" edge 20 can, for example, be gas-tightly shrunk onto aerosols made from polyethylene terephthalate (PET aerosols).

The propellant gas can be any gas, for example some inert gas, but preferably according to the invention a gas is used which has the least possible impact on the environment, such as, for example, air.

Of course, the propellant gas is intended to exert a pressure on the bag 5 such that when the valve 14 is activated by a user to a state where the passage 15 in the valve 7 is no longer closed, the product 9 in the bag 5 can flow out of the bag under the pressure supplied by the propellant gas.

In order to completely or sufficiently empty the bag 5, especially with viscous products 9, an outflow pipe 25 (also referred to as "flowtube" in English) can be provided on the valve housing 16 in order to extend the passage 15 in the valve housing 16.

In the manufacture of the extensible bag 5, this bag 5 can also be provided on the inside with flow-promoting means 26 which keep the bag 5 slightly open when emptying the pressure vessel 1 and thus offer a sufficiently large opening to allow the flow of product 9 up to the flow rate. to ensure that the opened valve 7 is opened and therefore to be able to empty the bag 5 completely or at least to the desired extent.

Such flow-promoting means 26 can for instance be formed by a few vertical ribs 26 or local elevations or thickenings 26 more or less equally distributed over the inner surface of the bag 5.

Characteristic of a pressure vessel 1 according to the invention is the fact that the bag 5 is made of an elastic, extensible and preferably gas-tight material, such that the bag 5 can stretch from an unstretched state, as shown in figures 1, 3 and 5, to an expanded state, as shown in Figures 2, 4 and 6, when the bag is filled with the product 9 or when the bag 5 is inflated with air or other gas.

As already explained in the introduction, it is because of this elasticity of the bag 5 that a pressure vessel 1 according to the invention offers numerous advantages over the existing pressure vessels with two compartments 2 and 3, for example because the volume of product 9 in the bag 5 can be easily adapted without having to use another bag 5 for this purpose, with many advantages in terms of the production of such a pressure vessel 1 as a result or, for example, because such a bag 5 is much less susceptible to being damaged in the event of an impact on the pressure vessel 1 and so on.

According to a preferred embodiment of a pressure vessel 1 according to the invention, the bag 5 is made of a material that is stretchable such that the volume occupied by the bag 5 in the stretched state is substantially larger than in the non-stretched state.

For example, the volume that the bag 5 can take for a long time in the stretched state without tearing or being damaged is at least double the maximum volume that the bag 5 can take up when the bag 5 is not stretched, but most preferably the volume is that the bag 5 can take up in the stretched state without noticeably weakening at least three times or more times of the maximum volume that the bag 5 can take up when the bag 5 is not stretched.

Furthermore, according to the invention, it is important that the material from which the bag 5 is made automatically resumes its original shape and dimensions or at least approximately even after the bag 5 has been stretched for a long time.

Another preferred feature of the present invention is to manufacture the bag from at least one of the following materials: - a natural rubber (latex); - a synthetic rubber; - a silicone rubber; a plastic, - a mixture of a natural rubber and one or more plastics; - an elastomer; - a thermoplastic elastomer; - a polyurethane; - a hybrid material; - a nano-structured material; - an LLDPE (Linear Low Density Polyethylene); or - a biopolymer.

More preferably, according to the invention, the bag 5 is made from one layer of material, such that the bag 5 is not subject to the delamination phenomenon mentioned in the introduction, which exists with the bags 5 of the known pressure vessels 1 with two compartments 2 and 3 , which are made from several layers.

According to another preferred embodiment of a pressure vessel according to the invention, the bag 5 is made of a material that is gas-tight and / or impermeable to the product 9 in the elongated state.

Expressed in less absolute terms, this means that according to the invention the bag 5 in the stretched state must be impermeable to such an extent that a gas in the first compartment 2 under the pressures present in the pressure vessel 1, not or only in an application acceptable may be permeable to a certain extent, so that penetration into the second compartment 3 with product 9 of the propellant gas into the compartment 2 is avoided as much as possible.

Similarly, under the conditions of use, the material is preferably as low as possible for product 9, in order to prevent the escape of product 9 from the bag 5 to the first compartment 2 as much as possible or is only permitted to a very limited extent.

For example, a certain maximum permeability limit for the material can be set under the aforementioned conditions and for both the propellant gas and the product 9.

According to an even more preferred embodiment of a pressure vessel 1 according to the invention, the bag 5 is made of a biodegradable material.

Of course, this choice is very interesting, since such a pressure vessel 1 according to this embodiment is even less environmentally harmful than a pressure vessel 1 according to the invention in which the bag 5 is not biodegradable, but which even in this less environmentally friendly embodiment already yields important ecological advantages since no propellant gas from the pressure vessel 1 is released during use.

Figure 4 shows another embodiment of a pressure vessel 1 according to the invention, in which this time the outer sleeve 4 and the bag 5 are each connected to the valve 7 by a separate gas-tight connection, more particularly by a first gas-tight connection 27 between the sleeve 4 and the valve 7 and a second gas-tight connection 28 between the bag 5 and the valve 7.

To form the second gas-tight connection 28, the aforementioned circumferential edge 11 of the bag 5 is clamped between the valve plate 17 and a projection 29 which extends radially to the valve housing 16 at some distance below the valve plate 17.

The first gas-tight connection 27 between the outer sleeve 4 and the valve 7 is provided, as in the previous embodiment, on the folded edge 20 of the valve plate 17, the circumferential edge 13 of the outer sleeve 4 being clamped in the folded edge 20.

As shown in more detail in Figure 5, a separate sealing rubber 30 can be provided for this purpose in the folded edge 20 in order to obtain a good seal.

An advantage of this embodiment of a pressure vessel 1 according to the invention consists in that the bag 5 and the valve 7 can be assembled in advance and that it is sufficient to retrofit this combination of bag 5 and valve 7 into an external sleeve 4, the ultimately specific shape of the external bushing 4 plays little or no role.

As a result, one type of such combination of bag 5 and valve 7 or only a limited number of such combinations of bag 5 and valve 7 is sufficient to produce a wide variety of pressure vessels 1, thereby also greatly reducing production time and production cost.

The embodiment of a pressure vessel 2, shown in Figure 5, is analogous to that of Figure 4, although the second gas-tight connection between the bag 5 and the valve 7 has been realized in a somewhat modified form.

In particular, the clamping of the circumferential and rolled-up edge 11 to the opening 12 in the bag 5 is realized at some radial distance D from the valve housing 16, at the location of a notch 31 in the radial projection 29 on the valve housing 16 and a notch 32 in the valve disc 17.

In this way the opening 12 on the bag 5 is formed by the circumferential edge 11 somewhat larger than in the previous embodiment.

In the embodiment of Fig. 5, further passage channels 33 are provided in the projection 29 on the valve housing 16, more particularly in the part of the projection 29 which is situated between the second gas-tight connection 28 and the wall 34 of the valve housing 16 from which the projection 29 extends radially.

A major advantage of this embodiment according to Figure 5 of a pressure vessel 1 according to the invention is that during filling of the bag 5 with product 9, the product 9 can be supplied both through the passage 15 which can be closed directly via the valve 14, as via the feed-through channels 33 in the projection 29, as a result of which the filling of the bag 5 with product can take place at a much larger flow rate, which entails an enormous gain in time, especially in mass production.

Figure 6 shows yet another embodiment of a pressure vessel 1 according to the invention.

Here, as in the previous embodiments of Figures 4 and 5, the outer sleeve 4 and the bag 5 are each connected to the valve 7 by a separate gas-tight connection 27 and 28.

The first gas-tight connection 27 between the bushing 4 and the valve 7 is here unchanged, while the second gas-tight connection 28 is realized between the projection 29 on the valve housing 16 and a separately mountable piece 35 on the valve 7 and no longer between the projection 29 and the valve disc 17 as in the previous cases.

This piece 35 in this case consists of a cylindrical element 35 with an internal opening 36 corresponding to the cylindrical outer wall 34 of the valve housing 16, the diameter of this opening 36 being widened at one end.

In the wall 34, clamping means 37 are also provided in this wall 34, which in this case are designed to be compressible and which are temporarily pressed in when the piece 35 is displaced over the valve housing 16 until these clamping means 37 can spring out again with a sufficiently large displacement of the piece 35 over the valve housing 16 towards the projection 29, so that an extension thereof is possible in the widening of the opening 36 and thus the piece 35 becomes stuck between the clamping means 37 and the projection 29 with the circumferential edge 11 attached to the bag 5 is also clamped between the projection 29 and the piece 35 to form the gas-tight seal 28.

Of course, many alternative embodiments for the clamping means 37 are possible without departing from the scope of the invention.

For example, the clamping means 37 may equally well consist of protrusions 37 on the valve housing 16 which cannot be pressed in, but which are fixedly connected to the valve housing 16 or simply form part of it, and wherein the separately mountable piece 35 is brought in place by the pressing forcefully over the protrusions 37 in the direction of the protrusion 29, whereby the protrusions 37 end up in the widening of the opening 36.

The connection between the separately mountable piece 35 and the valve housing 16 can also be realized differently, without necessarily also using clamping means 37.

In this case, for example, parts of the piece 35 and the valve housing 16 can be fused together, for example by applying certain types of welding methods, such as, for example, ultrasonic welding, induction welding and so on.

With this embodiment of a pressure vessel 1 according to the invention, an easily assembled whole is obtained, wherein in a very flexible manner all kinds of different types of bags 5, for example bags 5 with an adapted shape or volume or bags 5 made from an adapted material as a function of the application can be mounted on the valve 7 without any problems.

In the embodiments discussed above, the gas-tight connections 10, 27 and 28 between the valve 7 and the canister 4 or the bag 5 are realized directly on the valve 7, but in other embodiments this can equally well be realized by making use of intermediate elements without departing from the scope of the invention.

The present invention is by no means limited to the exemplary embodiment and shown in the figures of a pressure vessel 1 according to the invention, whether or not designed as a spray can according to the invention, but a pressure vessel 1, as well as a spray can according to the invention, can shapes and dimensions and in various ways are achieved without departing from the scope of the invention.

Claims (20)

A pressure vessel (1) of the type with two separate compartments (2,3), wherein a first compartment (2) is formed by an outer sleeve (4), in which an inner bag (5) is provided to form a second compartment (3), wherein the bag is filled with a product (9) or is intended to be filled with a product (9), the pressure vessel (1) also being provided with a valve (7) for supplying product ( 9) to and removal of product (9) from the bag (5) and wherein, both the outer sleeve (4) and the inner bag (5) by means of a gas-tight connection (10,27,28) on the valve are connected, characterized in that the bag (5) is made of an elastic and extensible material, such that the bag (5) can stretch into an elongated state when the bag (5) is filled with the product (9) or when the bag (5) is inflated with air or another gas. Pressure vessel (1) according to claim 1, characterized in that the bag (5) is made of a material that is stretchable in such a way that the volume taken up by the bag (5) in the stretched state is at least double the maximum volume that the bag bag (5) can take if the bag (5) is not stretched. Pressure vessel (1) according to claim 1 or 2, characterized in that the bag (5) is made of a material that is gas-tight and / or impermeable to the product (9) in the stretched state. Pressure vessel (1) according to one of the preceding claims, characterized in that the bag (5) is made from a biodegradable material. Pressure vessel (1) according to one of the preceding claims, characterized in that the bag (5) is made from one layer of material. Pressure vessel (1) according to one of the preceding claims, characterized in that the bag (5) is made from at least one of the following materials: - a natural rubber (latex); - a synthetic rubber; - a silicone rubber; - a plastic; - a mixture of a natural rubber and one or more plastics; - an elastomer; - a thermoplastic elastomer; - a polyurethane; - a hybrid material; - a nano-structured material; - an LLDPE (Linear Low Density Polyethylene); or - a biopolymer. Pressure vessel (1) according to one of the preceding claims, characterized in that the outer sleeve (4) and the bag (5) are each connected to the valve (7) by a separate gas-tight connection (27,28) by a first gas-tight connection (27) between the can (4) and the valve (7) and a second gas-tight connection (28) between the bag (5) and the valve (7). Pressure vessel (1) according to one of claims 1 to 6, characterized in that the outer sleeve (4) and the bag (5) are connected to the valve (7) by the same, joint gas-tight connection (10). Pressure vessel (1) according to claim 8, characterized in that a circumferential edge (11) at an opening (12) in the bag (5) is clamped between the valve (7) and a circumferential edge (13) on the outer sleeve (4) to form the aforementioned joint gas-tight connection (10). Pressure vessel (1) according to one of the preceding claims, characterized in that the valve (7) is a non-return valve (7) with a valve (14) which is movably arranged back and forth in a passage (15) of a valve housing ( 16) between a position in which the passage (15) is closed and a position in which the passage (15) is open and in which the valve housing (16) is also provided with a circular valve dish (17) extending radially from the valve housing (16) ) and on the outer edge (18) is provided with an upstanding collar (19) with a folded edge (20). Pressure vessel (1) according to claim 10, characterized in that the gas-tight connection (27) between the outer sleeve (4) and the valve (7) is provided on the folded edge (20) of the valve plate (17), wherein circumferential edge (13) of the outer sleeve (4) is clamped in the folded edge (20). Pressure vessel (1) according to claim 11, characterized in that to form the gas-tight connection (27) between the outer sleeve (4) and the valve (7), the upright collar (19) of the valve plate (17) is partially below the circumferential edge (13) on the outer sleeve (4) is pleated. Pressure vessel (1) according to claim 11, characterized in that to form the gas-tight connection (27) between the outer sleeve (4) and the valve (7), the folded edge (20) of the valve plate (17) is rolled around the circumferential edge (13) on the outer sleeve (4). Pressure vessel (1) according to claims 8 and 10, characterized in that a circumferential edge (11) is introduced into the bag (5) at the opening (12) of the valve dish (17) above, as well as a circumferential edge (13) on the outer sleeve (4) and wherein the edge (11) is clamped on the bag (5) between the folded edge (20) of the valve disc (17) and the circumferential edge (13) on the external sleeve (4) for forming the joint gas-tight connection (10). Pressure vessel (1) according to claims 7 and 10, characterized in that to form the second gas-tight connection (28) a circumferential edge (11) of the bag (5) is clamped between a projection (29) which extends radially to the the valve housing (16) and the valve dish (17). Pressure vessel (1) according to claim 15, characterized in that the above-mentioned projection (29) is provided with one or more feed-through channels (33), in particular in a part of the projection (29) which is situated between the second gas-tight connection ( 28) and a wall (34) of the valve housing (16) from which the projection (29) extends radially. Pressure vessel (1) according to one of claims 10 to 16, characterized in that an outflow pipe (25) is provided on the valve housing (16) in line with the passage (15) in the valve housing (16). Pressure vessel (1) according to one of the preceding claims, characterized in that the bag (5) is provided with flow-promoting means (26) consisting of a few vertical ribs (26) or local elevations or thickenings (26) provided on the inner surface of the bag (5). Spray can, characterized in that it comprises a pressure vessel (1) according to one of the preceding claims. Spray can according to claim 19, characterized in that it is designed as a pressure vessel (1) according to one of claims 1 to 18.