AEROSOL DISPENSER AND METHOD FOR ITS MANUFACTURE

Abstract: There is provided an aerosol dispenser comprising a body (1), a closure (2) sealed to the body (1) and provided with means (7) for dispensing material from the interior of the dispenser, characterised in that the closure (2) welds to the body (1) by a metal to metal laser weld. There is also provided a method of assembling an aerosol dispenser comprising a metal body (1) and a metal closure (2) provided with means (7) for dispensing material from the interior of the dispenser, characterised by laser welding (18) the closure (2) to the body (1) to form a metal to metal seal.

Description: AEROSOL DISPENSER AND METHOD FOR ITS MANUFACTURE This invention relates to an aerosol dispenser, i.e. a dispenser from which a material can be dispensed in aerosol form. It is particularly, though not exclusively, concerned with metered dose medicament aerosols, for example metered dose inhalers. The upper portion of one known dispenser is shown in vertical section in Figure 1 of the accompanying drawings. This comprises a metal can body 1 and a metal closure 2 having a flange 3 the lower end of which is crimped around an upper wall portion 4 of the can body 1. The closure 2 has a downwardly opening annular channel 5 within which is received a sealing gasket 6. The upper edge of the wall portion 4 of the can body 1 is in sealing engagement with the gasket 6. The dispenser is provided with a valve arrangement 7, the purpose of which is to enable metered doses of a material held under pressure within the can body 1 to be dispensed. Most of the details of this are not relevant to the present invention, and, furthermore, they are conventional. For the purposes of the present discussion it is sufficient to note that the valve arrangement 7 includes a metering chamber 8, within which a dose is held prior to being dispensed, and a hollow stem 9 which is longitudinally movable with respect to the chamber 8. The stem has a transfer port 10 and an outlet 11. When the stem is depressed from the position shown, the dose passes from the chamber 8 through the port 10 into the stem, and from there it passes out through the outlet 11. The stem 9 is in slidably sealing engagement with an aperture formed in the centre of a sealing ring 12. French Patent Application No. 2543923 describes an aerosol dispenser similar to that described with reference to Figure 1 , comprising a body having a dome shaped upper part welded to the main body portion, and a valve supporting closure which is crimped to the top edge of the dome in a conventional manner. Although not specifically shown, in order to ensure an adequate seal between closure and dome it is necessary to incorporate a gasket within the crimped fastening. Although the materials used for gaskets in aerosol dispensers are carefully chosen when medical applications are involved, to be as inert as possible, it is nevertheless recognised that it is desirable to reduce the amount of gasket material which can come into contact with the material to be dispensed. The largest gasket area in Figure 1 is that presented by the gasket 6, and it would therefore be particularly desirable to eliminate gasket 6. Such elimination also potentially offers the prospect of a cheaper dispenser than Figure 1 , by virtue of the fact that it uses one less component. It is also desirable to ensure that the aerosol dispenser is as nearly leak- proof as possible. In particular, it is desirable to prevent the leakage of moisture into the container where it can interfere with the integrity of any aerosol formulation contained therein. The gasket 6, though found in practice to give a good performance in this respect, does offer a potential leakage path extending circumferentially around the container. For that reason also, it would be desirable to eliminate the gasket and provide a seal between the body 1 and closure 2 which offered no such potential leakage path. According to one aspect of the present invention there is provided an aerosol dispenser comprising a body, a closure sealed to the body and provided with means for dispensing material from the interior of the dispenser, characterised in that the closure welds to the body by a metal to metal laser weld. Preferably, the metal-to-metal laser weld is between annular flanges on the body and closure extending circumferentially about the axis of the body and closure. In one aspect, the flanges are outwardly directed and flat. In another aspect, the flanges are axially directed and cylindrical. Preferably, the flanges are welded, rolled and crimped together. Preferably, one of the flanges is of greater width than the other and wherein the outer edge portion of the wider flange forms a "U" within which the outer edge portion of the narrower flange is located, both edge portions extending generally parallel to the adjacent wall of the body. In one aspect, the body is provided with a valve arrangement. In another aspect, the closure is provided with a valve arrangement. According to another aspect of the present information there is provided a method of assembling an aerosol dispenser comprising a metal body and a metal closure provided with means for dispensing material from the interior of the dispenser, characterised by laser welding the closure to the body to form a metal to metal seal. Preferably, the closure, which comprises an annular flange extending circumferentially about its axis, is positioned at the open end of and co- axially with the body, which comprises a complementary annular flange extending circumferentially about its axis, such that the flanges are parallel and in contact with each other. Preferably, the flanges are welded together by means of a laser beam which is brought into communication with the flanges and moved circumferentially along the flanges to create a substantially continuous weld between the flanges until a complete revolution about the axis of the closure and body has been performed. In one aspect, the flanges are outwardly directed and flat. Preferably, the flanges are bent to lie in a substantially axial direction after the flanges have been welded together. In another aspect, the flanges are axially directed and cylindrical. Preferably, one of the flanges is of greater width than the other, and after the flanges have been welded together the wider flange is rolled and crimped around the other flange. Preferably, the flanges are rolled and crimped after they have been welded together. Preferably the laser welding is conducted by means of a laser source having a maximum average power of from 10W to 200W, and a maximum peak power of from 1 kW to 10kW. More preferably, the laser source has a pulse width of from 0.5 to 20 microseconds and a maximum pulse energy of from 10 to 100 Joules. According to another aspect of the present invention there is provided an aerosol dispenser as described above which is charged with an aerosol suspension. The aerosol suspension preferably comprises medicament and a propellant. The medicament is preferably selected from the group consisting of albuterol, salmeterol, fluticasone propionate and beclomethasone dipropionate and salts or solvates thereof and any mixtures thereof. The propellant is preferably based on alternative propellants such as HFA- 134a (1 ,1 ,1 ,2-tetrafluoroethane) and HFA-227 (1 ,1 ,1 ,2,3,3,3- heptafluoropropane) which are being developed to replace those conventional propellants thought to contribute to atmospheric ozone depletion. Further characteristics of the invention will become apparent from the following description and accompanying drawings, wherein: Figure 1 is a vertical section through a prior art aerosol dispenser; Figure 2 is a vertical section through an embodiment of the invention; Figure 3 shows the embodiment of the invention as shown in Figure 2 together with part of one form of laser welding apparatus (shown diagrammatically); Figure 4 is a vertical section through a second embodiment of the invention, together with part of a laser welding head (shown diagrammatically); Figure 5 shows a detail of a modification of the embodiment of Figure 4; Figure 6 shows a further embodiment of the invention; and Figures 7a to 7c show successive steps in assembling the embodiment of Figure 6. In Figure 2, the same numerals are used as in Figure 1 for the corresponding parts. It will be seen that the metal body 1 terminates at its upper end in an outwardly directed, planar, annular flange 14, and that the circumferentially outer portion of the metal closure 2 is likewise in the form of a planar, annular flange 15. The flanges 14 and 15 are laser welded together along their mating surfaces 16 by a metal to metal weld. Laser welding enables only very localised heating to be produced in the region of the weld itself. This may enable the can to be filled before the closure is secured thereto (the alternative being to fill the can through the valve arrangement) since it reduces the risk of the medicament being undesirably heated. The laser source can be any source suitable for laser welding. Typically the maximum average power is from 10W to 200W, preferably from 25W to 100W and the maximum peak power is from 10kW to 1 kW, preferably from 5kW to 3kW. The pulse width is typically from 0.5 to 20 microseconds, and the maximum pulse energy from 100 to 10 Joules, preferably from 50 to 25 Joules. Advantages of the use of laser welding in the fabrication of the dispenser of the invention include precisely controllable low weld energy enabling the weld to be formed in a precise manner without affecting any of the other parts of the dispenser. Laser welds are furthermore clean and may be engineered to be hermetic in nature. Also, since laser output is typically very stable it is possible to achieve consistent weld repeatability. A procedure will now be mentioned with reference to Figure 3 for forming the weld between the flanges 14 and 15. As depicted in Figure 3, a laser source 17 is rotated such that a laser beam 18 is directed circumferentially along the flanges until a complete revolution has been performed. In an alternative process, the laser source 17 is fixedly mounted and the container is rotated relative thereto such that the desired contact of the laser beam 18 with the flanges 14,15 is achieved. When the flanges 14 and 15 have the form shown in Figure 2, the contents of the dispenser, being under pressure, exert a peel force on the weld between the flanges. A welded joint is relatively weak under a peel force, though nevertheless strong enough to withstand any force to which it is reasonably likely to be exposed. If, however, it is desired to avoid exposing the welded join to a peel force, the flanges can alternatively have the shape in Figure 4 wherein the flanges are axially directed and cylindrical. To achieve this, either the flanges may be welded in the form shown in Figure 2, and then bent through 90°, or they may be bent first and welded afterwards. In the latter case, the weld may be formed as shown in Figure 4 in which a ferrule 2 is inserted into a cylindrical body 1. The ferrule flange 15 is slightly splayed to aid insertion, alignment and to promote an interference (or at least a transition) fit at the top periphery. This fit between the flanges 14 and 15 at the top is necessary because the presence of any gap therebetween will undesirably permit the laser to beam into the body 1 rather than contacting and heating the flange 14,15 edge metal. A laser beam is directed at the peripheral joint of the body 1 and ferrule 2. The body 1 and ferrule 2 assembly can be spun in the presence of a stationary laser beam, or alternatively, the laser beam may be rotated around a stationary assembly. Welding continues until a continuous peripheral weld is completed. An alternative to the flange shape of Figure 4 as a way of avoiding subjecting the weld joint to a shear force is shown in Figure 5, in which the flanges are welded in the shape shown in Figure 2, and then bent downwardly. Correctly carried out laser welding should give a completely leakproof seal between the flanges. However, it is possible as a precaution to further seal the flanges together by having interengaging U-shaped portions on the body and closure. This is shown in Figure 6 and Figures 7a to 7c which show successive steps in sealing the closure to the body to form the construction shown in Figure 6. The laser weld is formed after the closure 2 and body 1 have been formed as shown in Figure 7a and assembled with one another, but before the rolling and crimping operations of Figures 7a and 7c have been carried out. Whilst Figures 1 to 7c particularly describe embodiments in which a valved ferrule is weldable to a metal can body other variations are possible. In particular, embodiments are envisaged in which a valved can body is weldable to a base ferrule. The base ferrule may be either dome shaped or essentially flat. The dispenser herein is suitable for dispensing medicament, particularly for the treatment of respiratory disorders. Appropriate medicaments may thus be selected from, for example, analgesics, e.g., codeine, dihydromorphine, ergotamine, fentanyl or morphine; anginal preparations, e.g., diltiazem; antiallergics, e.g., cromoglycate, ketotifen or nedocromil; antiinfectives e.g., cephalosporins, penicillins, streptomycin, sulphonamides, tetracyclines and pentamidine; antihistamines, e.g., methapyriiene; anti- infiammatories, e.g., beclomethasone dipropionate, fluticasone propionate, flunisolide, budesonide, rofleponide, mometasone furoate or triamcinolone acetonide; antitussives, e.g., noscapine; bronchodilators, e.g., albuterol, salmeterol, ephedrine, adrenaline, fenoterol, formoterol, isoprenaline, metaproterenol, phenylephrine, phenylpropanolamine, pirbuterol, reproterol, rimiterol, terbutaline, isoetharine, tulobuterol, or (-)-4-amino-3,5-dichloro-α-[[[6-[2-(2- pyridinyl)ethoxy] hexyljmethyl] benzenemethanol; diuretics, e.g., amiloride; anticholinergics, e.g., ipratropium, tiotropium, atropine or oxitropium; hormones, e.g., cortisone, hydrocortisone or prednisolone; xanthines, e.g., aminophylline, choline theophyllinate, lysine theophyllinate or theophylline; therapeutic proteins and peptides, e.g., insulin or glucagon. It will be clear to a person skilled in the art that, where appropriate, the medicaments may be used in the form of salts, (e.g., as alkali metal or amine salts or as acid addition salts) or as esters (e.g., lower alkyl esters) or as solvates (e.g., hydrates) to optimise the activity and/or stability of the medicament. Preferred medicaments are selected from albuterol, salmeterol, fluticasone propionate and beclometasone dipropionate and salts or solvates thereof, e.g., the sulphate of albuterol and the xinafoate of salmeterol. Medicaments can also be delivered in combinations. Preferred formulations containing combinations of active ingredients contain salbutamol (e.g., as the free base or the sulphate salt) or salmeterol (e.g., as the xinafoate salt) in combination with an antiinflammatory steroid such as a beclomethasone ester (e.g., the dipropionate) or a fluticasone ester (e.g., the propionate). It will be understood that the present disclosure is for the purpose of illustration only and the invention extends to modifications, variations and improvements thereto. The application of which this description and claims form part may be used as a basis for priority in respect of any subsequent application. The claims of such subsequent application may be directed to any feature or combination of features described therein. They may take the form of product, method or use claims and may include, by way of example and without limitation, one or more of the following claims:

Claims: CLAIMS 1. An aerosol dispenser comprising a body (1 ), a closure (2) sealed to the body (1 ) and provided with means (7) for dispensing material from the interior of the dispenser, characterised in that the closure (2) welds to the body (1 ) by a metal-to-metal laser weld. 2. An aerosol dispenser according to claim 1 , wherein the metal-to-metal laser weld is between annular flanges (14, 15) on the body (1 ) and closure (2) extending circumferentially about the axis of the body (1 ) and closure (2). 3. An aerosol dispenser according to claim 2, wherein the flanges (14, 15) are outwardly directed and flat. 4. An aerosol dispenser according to claim 2, wherein the flanges (14, 15) are axially directed and cylindrical. 5. An aerosol dispenser according to any of claims 2 to 4, wherein the flanges (14, 15) are welded, rolled and crimped together. 6. An aerosol dispenser according to any of claims 2 to 4, wherein one of the flanges (15) is of greater width than the other (14), and wherein the outer edge portion of the wider flange (15) forms a "U" within which the outer edge portion of the narrower flange (14) is located, both edge portions extending generally parallel to the adjacent wall of the body (1 ). 7. An aerosol dispenser according to any of claims 1 to 6, wherein the body (1) is provided with a valve arrangement (7). 8. An aerosol dispenser according to any of claims 1 to 6, wherein the closure (2) is provided with a valve arrangement (7). 9. A method of assembling an aerosol dispenser comprising a metal body (1 ) and a metal closure (2) provided with means (7) for dispensing material from the interior of the dispenser, characterised by laser welding the closure (2) to the body (1 ) to form a metal-to-metal seal. 10. A method of assembling an aerosol dispenser according to claim 9, wherein the closure (2), which comprises an annular flange (15) extending circumferentially about its axis, is positioned at the open end of and co- axialiy with the body (1 ), which comprises a complementary annular flange (14) extending circumferentially about its axis, such that the flanges (14, 15) are parallel and in contact with each other. 11. A method of assembling an aerosol dispenser according to claim 10, wherein the flanges (14, 15) are welded together by means of a laser beam (17) which is brought into communication with the flanges (14, 15) and moved circumferentially along the flanges (14, 15) to create a substantially continuous weld between the flanges (14, 15) until a complete revolution about the axis of the closure (2) and body (1 ) has been performed. 12. A method of assembling an aerosol dispenser according to claim 11 , wherein the flanges (14, 15) are outwardly directed and flat. 13. A method of assembling an aerosol dispenser according to claim 12 wherein the flanges (14, 15) are bent to lie in a substantially axial direction after the flanges (14, 15) have been welded together. 14. A method of assembling an aerosol dispenser according to claim 11 , wherein the flanges (14, 15) are axially directed and cylindrical. 15. A method of assembling an aerosol dispenser according to any of claims 10 to 14, wherein one of the flanges (15) is of greater width than the other (14), and after the flanges (14, 15) have been welded together the wider flange (15) is rolled and crimped around the other flange (14). 16. A method of assembling an aerosol dispenser according to any of claims 10 to 15, wherein the flanges (14, 15) are rolled and crimped after they have been welded together. 17. A method of assembling an aerosol dispenser according to any of claims 10 to 16, wherein the laser welding is conducted by means of a laser source having a maximum average power of from 10W to 200W, and a maximum peak power of from 1kW to 10kW. 18. A method of assembling an aerosol dispenser according to claim 17, wherein the laser source has a pulse width of from 0.5 to 20 microseconds and a maximum pulse energy of from 10 to 100 Joules. 19. An aerosol dispenser according to any of claims 1 to 8, wherein the dispenser is charged with an aerosol suspension. 20. An aerosol dispenser according to claim 19, wherein the aerosol suspension comprises medicament and a propellant. 21. An aerosol dispenser according to claim 20, wherein the medicament is selected from the group consisting of albuterol, salmeterol, fluticasone propionate and beclomethasone dipropionate and salts or solvates thereof and any mixtures thereof. 22. An aerosol dispenser according to either of claims 20 to 21 , wherein the propellant is selected from the group consisting of 1 ,1 ,1 ,2- tetrafluoroethane and 1 ,1 ,1 ,2,3,3,3-heptafluoropropane.

Inventors: MAGUIRE-TAYLOR ANTHONY JOHN, MAGUIRE-TAYLOR, ANTHONY, JOHN
Applicants: GLAXO GROUP LTD, MAGUIRE TAYLOR ANTHONY JOHN, GLAXO GROUP LIMITED, MAGUIRE-TAYLOR, ANTHONY, JOHN
Application year: 1999
Main classification: B65D83
IPC codes: B23K26, B23K33, B65D83