The present invention relates to a method for sealingly join ^¬ ing a canister containing a propellant with a top cover comprising a valve. Furthermore, the present invention relates to a medicament container for a metered dose inhaler comprising a canister and a top cover.

One frequent manner of administering therapeutic, prophylactic or diagnostic compounds, i.e. drugs and medicaments, to a pa ^¬ tient in connection with the treatment of respiratory and nasal diseases, such as, e.g., asthma or chronic obstructive pulmonary disease (COPD) , involves delivering these compounds to the patient in aerosol formulations. For this purpose, a low boiling point liquid or liquefied gas may advantageously be formulated with the respective compound or compounds and disposed under pressure in a closed canister. The canister is part of a medicament container which also comprises a top cov ^¬ er sealingly connected to the canister. The top cover compris ^¬ es a metering valve by means of which a predetermined quantity of the compound formulation can be metered and the correspond ^¬ ing dose can be dispensed as an inhalable cloud. In this re ^¬ gard, the low boiling point liquid or liquefied gas consti ^¬ tutes a propellant which is capable of expelling the formula ^¬ tion through the metering valve.

In actual use the medicament container is preferably arranged in an inhaler such as a metered dose inhaler (MDI) which provides a channel for guiding the formulation expelled from the metering valve into the mouth and lung of a patient and which is also designed for facilitating actuation of the metering valve. The metering valve may include a valve stem extending from the metering valve and providing a conduit for passing the metered dose out of the medicament container. The inhaler may include a receptacle for receiving the medicament contain- er and a nozzle block which receives the valve stem of the me ^¬ dicament container arranged in the receptacle. A patient may depress the container into the receptacle, thereby actuating the metering valve, in order to dispense a dose of medicament as an inhalable cloud.

Canisters may be joined with corresponding top covers by crimping, as e.g. disclosed in FR 2 698 338 Al which relates to the joining of a can such as an aerosol container and a cover via one or more crimping helices. Each helix has a spi ^¬ ral form and is driven in rotation by a motor. The depth of the spiral varies to realize the various stages of crimping. The turning helices engage with overlapping edges of the con ^¬ tainer and the cover such that convolutions of the helices de ^¬ form the overlapping edges in a way that the edges are folded clockwise or counterclockwise, depending on the perspective, thereby sealingly joining the can and the cover. Ensuring correct folding of the overlapping edges is rather complicated. Moreover, the folding process is rather time consuming.

Nowadays aerosol canisters for use in metered dose inhalers and their covers are typically joined by lateral deformation of only the top cover to enclose a bead of the canister. Can ^¬ isters for medicament container typically comprise a top por ^¬ tion having a bead which circumferentially extends around the cylindrical sidewall of the canister as disclosed for example in WO 2014/204951 Al (see figures 1 and 2) . The top cover has a ferrule which upon crimping abuts the bead. According to the embodiment described in WO 2014/204951 Al an O-ring is addi ^¬ tionally positioned adjacent to the bead and is also enclosed by the crimped ferrule of the top cover.

Crimping of a ferrule onto a bead might in some cases lead to play in between the top cover and the canister as the ferrule does not fully abut and thus fix the bead. Moreover it is an existing need to lower the amount of discard during production of a medicament container thereby decreasing the production costs .

Therefore, it is an object of the present invention to provide a method for sealingly joining a canister with a top cover using a crimping process by which medicament containers may be produced in a less expensive and less energy intensive manner.

This object is achieved by a method for sealingly joining a canister with a top cover comprising the steps of claim 1 as well as by a medicament container according to claim 11. Preferred embodiments of the method and the medicament container are set out in the respective dependent claims.

The present invention provides a method for sealingly joining a canister having a propellant with a top cover comprising a valve, the method comprising the following steps:

providing a canister having a top section with an opening, a cylindrical sidewall defining a longitudinal axis and a bottom wall, wherein the cylindrical sidewall has a reduced diameter section providing a crimping region, the opening comprising an inwardly shaped portion such that an diameter of said opening is smaller than an inner diameter of the reduced diameter section of the said tubular sidewall,

attaching a top cover to the canister, wherein the top cover holds valve components and comprises a ferrule which along the longitudinal axis forms an overlap section for circumferen- tially overlapping with and enclosing the reduced diameter section of the sidewall of the canister thereby defining an overlap region, and

crimping of the ferrule and the sidewall of the canister in the overlap region in a direction lateral to the longitudinal axis so as to secure the top cover to the sidewall of the can ^¬ ister .

The inventors have found that a less expensive medicament con ^¬ tainer can be obtained by using a canister having a reduced diameter section providing a cylindrical crimping region for the crimping process as well as by joining the canister and the top cover by deforming the overlap section of the ferrule of the top cover together with the crimping region of the canister at once upon crimping. In other words, by crimping the ferrule and the sidewall of the canister in the overlap re ^¬ gion, the overlap section of the ferrule of the top cover to ^¬ gether with the crimping region of the canister are deformed and thereby crimped at once.

Surprisingly, the method according to the present invention provides less discard in comparison to the joining process us ^¬ ing a canister having a bead prior to crimping. Furthermore, the stability of the canister during the crimping process is improved such that the wall thickness of the sidewall, in par ^¬ ticular in the crimping region of the canister and the ferrule of the top cover, could be lowered.

In connection with the present invention the term "ferrule" is to be understood as a part of the top cover being deformable for attaching the top cover to the canister. Preferably, the ferrule can be made of stainless steel, aluminium, aluminium alloy or engineering plastic, more preferably stainless steel, aluminium or aluminium alloy. For example an aluminium magnesium alloy can be used, preferably aluminium alloy 5052, i.e. AlMg 2.5. Other possible materials include Al 3003 and Al 3004. The ferrule may be shaped as a castellated ferrule as mentioned in WO 2014/204951 Al . The expression "crimping re ^¬ gion" of the side wall of the canister describes a portion be ^¬ ing deformed by the crimping process. Top covers useful for the invention are e.g. disclosed in doc ^¬ uments GB 2077229 A, WO 01/79079 Al and WO 2014/204951 Al . These documents are incorporated in their entirety into the present application by way of reference.

In a preferred embodiment of the present invention, the fer ^¬ rule and the side wall of the canister are crimped adjacent to the inwardly shaped portion of the opening of the canister such that the crimping region of the side wall forms a circum- ferentially extending bead oriented concentric to the longitu ^¬ dinal axis wherein the overlap section of the ferrule abuts and engages behind the bead. In other words, the ferrule en ^¬ gages behind the bead in a direction along the longitudinal axis towards the bottom wall of the canister. In connection with the present invention it has been found that the inwardly shaped portion of the opening of the canister stiffens the top portion of the canister such that the inwardly shaped portion remains its shape upon crimping whereas the crimping region adjacent to the inwardly shaped portion forms a bead.

According to another embodiment of the present invention the crimping causes deformation of the ferrule and the sidewall of the canister in a direction lateral to the longitudinal axis, wherein the degree of deformation of the crimping region of the sidewall is at least 50 %, preferably at least 80 % of the degree of deformation of the overlap section of the ferrule of said top cover. If the overlap section of the ferrule is de ^¬ formed about 2 mm based on a reduction of the inner diameter of the ferrule, the crimping region of the sidewall of said canister is deformed in an extent of at least 1 mm, preferably at least 1.6 mm based on a reduction of an outer diameter of the crimping region. According to another embodiment of the present invention the standard deviation of the thickness of the crimping region of the crimped sidewall of the canister is below 0.10 mm, more preferably below 0.07 mm, especially preferably below 0.03 mm and most preferably below 0.01 mm. The standard deviation of the thickness of the sidewall of the canister is determined by taking measurements form at least 5 points and preferably from at least 10 points. Thickness of the sidewall can be measured by any suitable method, like measurements with a caliper, preferably a digital caliper or microscopic methods after mak ^¬ ing sections and analyzing the cutting area. Using microscopic methods affords that care is taken to achieve an appropriate cutting site. This can be achieved with embedding the can in a matrix. A low deviation of the thickness of the crimping region as described above avoids cracking of the canister side wall during crimping.

Preferably, the standard deviation of the thickness of the crimped overlap section of the ferrule is below 0.10 mm, more preferably below 0.07 mm, especially preferably below 0.03 mm and most preferably below 0.01 mm. The standard deviation of the thickness of the overlap section of said top cover is de ^¬ termined by taking measurements form at least 5 points and preferably from at least 10 points. Such a low deviation of the thickness of the overlap section avoids cracking of the ferrule during crimping.

In a further embodiment of the present invention, the differ ^¬ ence of an inner diameter of the overlap section of the ferrule and an outer diameter of the crimping region of the side- wall in the crimped overlap region is below 0.30 mm, more preferably below 0.20 mm, especially preferably below 0.10 mm and most preferably below 0.05 mm. Thus, the overlap section of the ferrule fully abuts and encloses the crimping region of the sidewall, thereby fixing the top cover to the canister. According to another embodiment of the present invention the canister and the top cover can be made of a metal, preferably aluminium, aluminium alloy or stainless steel. For example an aluminium magnesium alloy can be used, preferably aluminium alloy 5052, i.e. AlMg 2.5. Other possible materials include Al 3003 and Al 3004. The canister and the top cover can be coated or uncoated. Furthermore, a surface treatment of the canister and/or the top cover may be applied. The coating and/or the surface treatment may be applied by any method known in the art. These methods are e. g. disclosed in documents WO 2009/073012 Al, US 6,596,260, US 6,546,928, US 6,532,955, WO 2011/104539 Al and WO 2011/104541 Al . These documents are in ^¬ corporated in their entirety into the present application by way of reference.

Preferably, the thickness of the sidewall of the canister is in the range of 0.18 to 1.00 mm, preferably of 0.2 to 0.90 mm, more preferably of 0.3 to 0.70 mm. Optionally, the thickness of the ferrule of said top cover is in the range of 0.18 to 1.00 mm, preferably of 0.2 to 0.90 mm, more preferably of 0.3 to 0.70 mm. The thickness of the sidewall of the canister and the ferrule of the top cover can be selected according to specified requirements which are determined based on the pres ^¬ sure being applied to the medicament container by the propel- lant. The thicker the wall the more stable is the medicament container. However, the thicker the wall, the higher is the price of the medicament container. The present method enables that, for a predetermined standard pressure, the wall thick ^¬ ness could be lowered or at a predetermined wall thickness a higher pressure could be achieved.

In a preferred embodiment of the present invention, the top cover comprises a gasket and the gasket is preferably pressed at a pressure in the range of 500 to 5000 N, more preferably of 700 to 4000 N, most preferably of 800 to 3000 N and also most preferably of 900 to 2000 N on the canister during the crimping process. This avoids an uncontrolled leakage of the propellant out of the medicament container.

Preferably, the gasket is made of a rubber, preferably a ther- moset elastomer or a thermoplastic elastomer. In connection with the present invention gaskets may be used that are known from the prior art.

It is also preferred that the bottom wall comprises a central inwardly domed or curved portion. In other words, in a top plan view of the bottom wall, the central domed or curved por ^¬ tion constitutes a concave portion. Preferably, the point of deepest depression of the central domed portion is located at the center of the bottom wall which is positioned on the lon ^¬ gitudinal axis of the canister. It is also preferred for the central domed portion to be rotationally symmetric. In partic ^¬ ular, the central domed portion may have a circular circumference and be symmetric about the center of the corresponding circle .

In connection with the central domed portion the word "central" is intended to indicate that the domed portion is not located at only one border of the bottom wall. Rather, the central domed portion extends over the entire or substantially the entire bottom wall.

In order to maintain the propellant in the liquid state, a considerable pressure must be present in the interior of the canister. Consequently, the canister must be capable of safely withstanding such elevated pressures. Specifically, according to ICAO regulations the burst pressure of the canister must be at least 220 psi, i.e. 15.2 bar. As a safety measure, the bot ^¬ tom wall of the canister is preferably formed into an inwardly domed shape, and the construction of the canister is prefera ^¬ bly chosen such that upon exceeding a particular pressure value somewhat below the admissible 15.2 bar burst pressure the inwardly domed shape is preferably inverted to an outwardly domed shape, thereby increasing the interior volume of the canister and decreasing the interior pressure. This inversion of the inwardly domed bottom also indicates to the user that the interior pressure of the canister is at a dangerous level.

In another preferred embodiment, the sidewall has a wall thickness which is smaller than the wall thickness of the en ^¬ tire bottom wall or at least the central domed portion there ^¬ of. Specifically, the thickness of the bottom wall is prefera ^¬ bly at least 0.05 mm, preferably at least 0.08 mm, especially preferably at least 0.12 mm and most preferably at least 0.14 mm higher than the thickness of the sidewall. Both values con ^¬ cern the highest thickness of the bottom wall and the side- wall, respectively.

In a preferred embodiment the thickness of the bottom wall is in the range of 0.20 to 1.20 mm, preferably the thickness of the bottom wall of said canister is in the range of 0.20 to 1.10 mm, more preferably the thickness of the bottom wall of said canister is in the range of 0.40 to 1.00 mm.

Also preferred is an embodiment according to which the side- wall and the bottom wall are integrally formed in one piece. Such a canister may be produced by deep drawing a cup-shaped component including the sidewall and the bottom wall.

In addition thereto, a further subject matter of the present invention is a medicament container for a metered dose inhal ^¬ er, the medicament container comprising a canister and a top cover which are sealingly joinable by a method according to the present invention. Preferably, the canister may have an outer diameter in the range of about 15 mm to about 28 mm, more preferably about 21.5 mm to about 22.5 mm, a portion having a reduced diameter with an outer diameter in the range of about 13 mm to about 25 mm, more preferably about 19.5 to about 20.5 mm, a total length of about 18 to about 80 mm, more preferably about 60.0 to about 62.5 mm, wherein the portion having a diameter in the range of about 15 mm to about 28 mm, more preferably about 21.5 mm to about 22.5 mm has a height or length in the range of about 10.0 mm to about 70.0 mm, more preferably about 42.0 mm to about 45.0 mm.

The difference in the height or length between the portion having an outer diameter in the range of about 15 mm to about 28 mm, more preferably about 21.5 mm to about 22.5 mm and the portion having a reduced diameter with an outer diameter in the range of about 13 mm to about 25 mm, preferably about 19.0 to about 22.0 mm, more preferably about 19.5 to about 20.5 mm can be formed by a transition portion, wherein the diameter is reduced .

More preferably, the central inwardly domed portion of the bottom wall may have a height of about 2.0 to about 4.0 mm and the opening of the canister being opposite to the bottom wall which is inwardly shaped such that the diameter of said open ^¬ ing has preferably an inner diameter of about 10.0 mm to about 19.0 mm, more preferably about 16.0 mm to about 17.5 mm.

In the following a preferred embodiment of the invention is explained in detail with reference to the drawings. A person skilled in the art understands that this embodiment is only an exemplary realization of the invention and is not to be understood as limiting the claimed scope. In the drawings Figure 1 shows a perspective view of a medicament con ^¬ tainer,

Figure 2 shows a cross sectional view of a canister and a top cover prior to crimping and

Figure 3 shows a cross sectional view of a canister and a top cover after being crimped.

Figure 1 shows a perspective view of a medicament container 1 for a metered dose inhaler (not shown) comprising a canister 2 and a top cover 3 which are sealingly joined together via crimping .

The top cover 3 holds valve components such as a valve 4 by which a propellant containing a medicament and being stored in the medicament container 1 can be dispensed as an aerosol.

Figure 2 shows a crossectional view of the canister 2 and the top cover 3 prior to being crimped together.

The canister 2 has a top section 5 with an opening 6. The canister 2 further comprises a cylindrical sidewall 7 defining a longitudinal axis 8 and a bottom wall 9, positioned opposite the opening 6.

The cylindrical sidewall 7 has a reduced diameter section 10 providing a cylindrical crimping region 11. The opening 6 comprises an inwardly shaped portion 12 such that a diameter Dl of said opening 6 is smaller than an inner diameter D2 of the reduced diameter section 10 of the tubular sidewall 7.

The bottom wall 9 of the canister 2 comprises a central in ^¬ wardly domed portion 13. The central domed portion 13 has a circular circumference and is symmetric about the center of the corresponding circle which is positioned on the longitudi ^¬ nal axis 8. The top cover 3 comprises a ferrule 14 which along the longi ^¬ tudinal axis 8 forms an overlap section 15 for circumferen- tially overlapping with and enclosing the reduced diameter section 10 of the sidewall 7 of the canister 2 thereby defin ^¬ ing an overlap region 16.

The top cover 3 further comprises a gasket 17 which is made of a rubber, preferably a thermoset elastomer or a thermoplastic elastomer. The gasket 17 abuts the top section 5 of the canis ^¬ ter 2 when the top cover 3 is put over the canister 2.

Figure 3 shows a crossectional view of a medicament container

I comprising the canister 2 and the top cover 3 after being crimped together.

The crimping region 11 of the side wall 7 forms a circumferen- tially extending bead 18 oriented concentric to the longitudi ^¬ nal axis 8. The ferrule 14 abuts and engages behind the bead 18 in a direction along the longitudinal axis 8 towards the bottom wall 9 of the canister 2.

The standard deviation of the thickness of the crimping region

II of the crimped sidewall 7 of the canister 2 as well as the standard deviation of the thickness of the crimped overlap section 15 of the ferrule 14 is below 0.07 mm.

The difference of any inner diameter D3 of the overlap section 15 of the ferrule 14 and any corresponding outer diameter D4 of the crimping region 11 of the sidewall 7 in the crimped overlap region 16 along the longitudinal axis 8 is below 0.20 mm.

The canister 2 and the top cover 3 are made of a metal, pref ^¬ erably aluminium, aluminium alloy or stainless steel. In the following a method for sealingly joining the canister 2 and the top cover 3 is explained with reference to the figure 2 and 3 :

In a first step the canister 2 is provided. The canister com ^¬ prises the features as described above with reference to fig ^¬ ure 2.

In a second step the top cover 3 is attached to the canister 2. The ferrule 14 of the top cover 3 forms along the longitu ^¬ dinal axis 8 an overlap section 15 for circumferentially over ^¬ lapping with and enclosing the reduced diameter section 10 of the sidewall 7 of the canister 2 thereby defining an overlap region 16.

In a third step the ferrule 14 and the sidewall 7 of the can ^¬ ister 2 are crimped in the overlap region 16 in a direction lateral to the longitudinal axis 8 so as to secure the top cover to the sidewall 7 of the canister 2. In more detail the ferrule 14 and the side wall 7 of the canister 2 are crimped adjacent to the inwardly shaped portion 12 of the opening 6 of the canister 2 such that the crimping region 11 of the side wall 7 forms a circumferentially extending bead 18 oriented concentric to the longitudinal axis 8, wherein the ferrule 14 abuts and engages behind the bead 18. The degree of defor ^¬ mation of the crimping region 11 of the sidewall 7 caused by the crimping during the third step of the present method is at least 80 % of the degree of deformation of the overlap section 15 of the ferrule 14.

During the third step of crimping the gasket 17 in the top cover 3 is pressed at a pressure in the range of 900 to 2000 N on the canister 2. Based on this pressure and because of the crimp connection described above the canister 2 and the top cover 3 are sealingly joined thereby providing a medicament container 1. A propellant which is filled into the medicament container 1 in a subsequent step does thus not leak.