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Title:
IMPROVED FILLING OF LIQUIDS INTO POLYURETHANE SPRAY CANS
Document Type and Number:
WIPO Patent Application WO/2020/127997
Kind Code:
A1
Abstract:
Described is a filling station for filling liquids for a polyurethane (PU) foam composition into a spray can whereby at least one filling head (3) of the filling station is provided with an unscrewable outer head (2) having a removable nozzle (1) therein. Further described is a method for the filling, by means of the filling station, of at least one liquid for a polyurethane (PU) foam composition into a spray can whereby at least one liquid filling is introduced into the spray can through the filling head (3) provided with the unscrewable outer head (2) with removable nozzle (1).

Inventors:
PAUWELS BEN (BE)
VERVOORT BART (BE)
DIRCKX VEERLE (BE)
GEBOES PETER (BE)
BRUGGEMAN PETER (BE)
VAN GORP JO (BE)
DE BACKER WIM (BE)
Application Number:
PCT/EP2019/086724
Publication Date:
June 25, 2020
Filing Date:
December 20, 2019
Export Citation:
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Assignee:
SOUDAL (BE)
International Classes:
B65B31/00; B05B9/04; B05B9/08; B65D83/42; B65D83/48
Domestic Patent References:
WO2015043854A12015-04-02
WO2011151295A12011-12-08
WO2016120336A12016-08-04
WO1998043894A11998-10-08
WO2011151296A22011-12-08
WO2015043854A12015-04-02
WO2009004097A12009-01-08
WO2003062092A12003-07-31
WO2015032963A12015-03-12
WO2012052449A22012-04-26
WO2009004097A12009-01-08
WO2011151295A12011-12-08
Foreign References:
DE3134182A11983-03-17
US20100024910A12010-02-04
EP2392407A12011-12-07
US20170304851A12017-10-26
JP2002166201A2002-06-11
US20150274404A12015-10-01
EP2371738A12011-10-05
US1959694A1934-05-22
DE29623308U11998-02-12
DE3208969A11983-09-22
DE69218221T21997-08-14
US5271537A1993-12-21
EP2576080A12013-04-10
EP2371738A12011-10-05
US20100024910A12010-02-04
US20120291898A12012-11-22
US9909290B22018-03-06
US5014887A1991-05-14
US5215225A1993-06-01
US5549226A1996-08-27
US6058960A2000-05-09
BE20185924U
US10106309B22018-10-23
Attorney, Agent or Firm:
GEVERS PATENTS (BE)
Download PDF:
Claims:
CLAIMS

1. A filling station for filling liquids for a polyurethane (PU) foam composition into a spray can, through the filling opening before closing the can by means of a valve, whereby at least one filling head (3) of the filling station is provided with an unscrewable outer head (2) having a removable nozzle (1 ) therein.

2. The filling station according to claim 1 whereby the outlet side of the outer head (2) is provided with a constriction and the nozzle (1 ) is provided with a laterally flared widening that is adapted to be blocked by the constriction in the outer head.

3. The filling station according to claim 1 or 2 whereby the nozzle (1 ) is provided with a pattern of small channels for guiding the liquid through the nozzle.

4. The filling station according to the preceding claim whereby the small channels are implemented in parallel.

5. The filling station according to any one of claims 3-4 whereby the small channels have a length-to-diameter (L/D) ratio of at least 5.

6. The filling station according to any one of the preceding claims whereby the nozzle (1 ) is manufactured by additive manufacturing, preferably using 3D printing.

7. The filling station according to any one of the preceding claims whereby the nozzle (1 ) is manufactured from a material selected from metal and plastic, preferably plastic.

8. The filling station according to any one of the preceding claims whereby the filling head (3) comprises an obturator (4) for opening and closing the liquid supply.

9. The filling station according to the preceding claim whereby the filling head (3) further comprises an outlet chamber (5) between the obturator (4) and the nozzle (1 ).

10. The filling station according to the preceding claim whereby the volume of the outlet chamber (5) is larger with the obturator closed (4) than with the obturator open.

1 1 . The filling station according to any one of the preceding claims whereby at least two and preferably all of the filling heads (3) for filling the polyol composition for the PU foam composition are provided with the outer head (2) with the removable nozzle (1 ).

12. The filling station according to any one of the preceding claims whereby at least one of the filling heads (3) for filling the isocyanate composition for the PU foam composition is provided with the outer head (2) with the removable nozzle (1 ), preferably all of the filling heads (3) for filling the isocyanate composition.

13. A method, using a filling station according to any one of the preceding claims, for filling at least one liquid for a polyurethane (PU) foam composition into a spray can through the filling opening before closing the can by means of a valve, whereby at least one liquid filling is introduced into the spray can through the filling head (3) that is provided with the unscrewable outer head (2) with the removable nozzle.

14. The method according to the preceding claim whereby the filling head (3) comprises an obturator (4) upstream of the nozzle (1 ), which closes the liquid supply after filling the at least one liquid filling and opens it again before filling the next specimen of the at least one liquid filling.

15. The method according to the preceding claim whereby the obturator (4) closes during the removal of the filling head (3) from the spray can after filling the at least one liquid filling, and opens again during the positioning of the filling head (3) onto the next spray can for filling the next specimen of the at least one liquid filling.

16. The method according to any one of claims 14-15 whereby the filling head (3) further comprises an outlet chamber (5) between the obturator (4) and the nozzle (1 ), and whereby closing the obturator (4) increases the volume of the outlet chamber (5).

17. The method according to any one of claims 13-16 whereby the nozzle (1 ), in case of wear and/or narrowing and/or obstruction of openings in the nozzle, is removed from the outer head and is replaced with a clean specimen of the nozzle.

18. The method according to the preceding claim whereby the clean specimen of the nozzle (1 ) is a newly manufactured specimen of the nozzle.

19. The method according to any one of claims 17-18 whereby the clean specimen is placed into the outlet of the outer head by positioning the nozzle into the outlet of the outer head.

20. The method according to any one of claims 13-19 whereby the nozzle (1 ) is removed from the outer head by unscrewing the outer head from the filling head and by subsequently pressing the nozzle up from out of the outer head in the direction opposite to the flow direction of the liquid through the nozzle.

21 . The method according to any one of claims 13-20 whereby the removable nozzle (1 ) is removed after use and is not re-used for the same function.

22. The method according to any one of claims 13-21 whereby two or more filling heads are provided for filling the polyol composition and whereby at least part of the polyol composition to be filled into a same spray can is filled through the filling head (3) provided with the outer head with removable nozzle, and preferably the entire amount of polyol composition is filled through a filling head (3) provided with the outer head with removable nozzle.

23. The method according to any one of claims 13-22 whereby two or more filling heads are provided for filling the isocyanate composition and whereby at least part of the filling of the isocyanate composition is filled through the filling head (3) provided with the outer head with removable nozzle, and preferably the entire amount of isocyanate composition is filled through a filling head (3) provided with the outer head with removable nozzle.

24. The method according to any one of claims 13-23 further comprising the step of closing the filled spray can by securing a valve with a valve collar onto the filling opening of the spray can.

25. The method according to the preceding claim further comprising the step of injecting at least one propellant gas into the spray can, preferably through the opened valve.

26. The method according to any one of claims 24-25 further comprising the step of shaking the spray can.

27. The method according to any one of claims 24-26 whereby the valve is a valve for gun foam.

28. The method according to the preceding claim further comprising the step of attaching an applicator for handheld operation suitable for a spray can with gun foam.

29. The method according to claim 27 further comprising the step of attaching a gun coupling piece onto the valve collar, preferably a gun coupling piece with a protective cover.

30. The method according to the preceding claim whereby the gun coupling piece is suitable for attaching an applicator for handheld operation.

31. The method according to any one of claims 24-26 whereby the valve is a valve for handheld operation.

32. The method according to the preceding claim further comprising, after the injection of propellant gas, the step of arranging a protective cap onto the spray can head, preferably a protective cap containing an accessory item, preferably the accessory item being at least one plastic glove, more preferably at least one pair of plastic gloves.

Description:
Improved filling of liquids into polyurethane spray cans

SCOPE OF THE INVENTION

The present invention relates to the pressurized filling of spray cans or pressure containers. More in particular, the invention relates to injecting liquids into spray cans, before closing the can by means of a valve, in which, eventually, a composition for forming a polyurethane (PU) foam will be packaged.

BACKGROUND OF THE INVENTION

Polyurethane foam has many applications, especially in the construction industry. It is frequently used as a mounting material and as an insulation material, and often also for filling up and/or sealing holes and cracks. It is easily applicable from a pressurized spray can, easily adheres to most surfaces, and in many cases is even paintable. Shortly after application, a solid foam is formed that may be cut, so that excess volume may easily be removed.

Most spray cans containing PU foam contain a so- called“single component” PU foam (1 k PU foam), but the family also comprises the so-called 2k and 1.5k versions.

In order to eventually obtain a foaming product, three components are required: the polyol mixture, the isocyanate, and the propellant gas. The polyol mixture and the isocyanate are the necessary ingredients for obtaining a polyurethane plastic. These two components are liquid under ambient conditions. The propellant gas ensures that the polyurethane foams and is driven out of the spray can. It does not take part in the reaction but does contribute to influencing the physical properties of the liquid in the spray can, such as its viscosity.

In the case of 1 k PU, all of these components are already present, fully mixed, in one and the same spray can. The 2k PU systems comprise 2 pressurized containers, one containing the polyol mixture and the other containing the isocyanate, and, using pressure from propellant gas in each of the containers, these components are first combined and mixed before the mixture is expelled immediately afterwards. In the case of 1 .5k systems, a smaller container is arranged inside the spray can, which contains a reagent, usually a fast-reacting polyol. Before using the spray can. the small container first needs to be opened or“activated” by the user, for instance by moving a rotary knob at the bottom of the spray can, releasing the contents of the smaller container. By shaking the whole, the contents of the small container may be mixed with the contents in the spray can around the small container, and the contents of the small container is allowed to react with the latter. Such an activating system is for instance described in WO 2016/120336 A1 .

In the case of 1 k PU foam spray cans, the polyol mixture and the isocyanate react in the spray can immediately after filling, thereby forming the pre-polymer. The ratio in which these components are mixed, usually with an excess of isocyanate component, and the nature of the components themselves, are responsible for the eventual properties of the final product. After being sprayed from the spray can, the pre-polymer will foam, and the foamed pre-polymer will react with moisture from the ambient air and possibly also from the substrate with which it is put into contact. This final reaction with moisture is what causes the fresh foam to set and to foam even further due to the formation of CO2. In the case of 2k and 1 .5k PU foam, the final setting is much less, or even barely, dependent on a reaction with moisture from the environment.

1 k PU foam, especially, is nowadays used by both professionals and DIYers alike, and has become a toolbox staple, in addition to silicone sealant and contact adhesive. The packaging, and in particular the development of the valve, have played a major role in this breakthrough and the acceptance of 1 k PU foam as a“practical and effortless” product. For intensive applications, directed mainly toward professionals, it is popular to use a dosing gun or spray-gun, or another device that handles well and usually also allows precise dosage and application, so that even narrow seams can easily be filled without too much waste. Cans or containers for such use are therefore provided with a specially adapted gun coupling piece or ring, which is placed around the valve onto the spray can, and is intended to enable a coupling with the spray-gun or other device, which is usually intended for applying the contents of the can where needed. The gun coupling piece usually also comprises a protective cover that, as a seal over the valve of the container, protects the valve, and should be removed before use in order to liberate the valve. The spray-gun may then be screwed onto the ring or onto the gun coupling piece, which is placed onto the can, threadedly or by means of a snap fit system, causing the valve to be simultaneously pressed into its open position, thus immediately readying the spray-gun for use. A suitable and very easy-to-use“Click & Fix” system of a ring and matching spray-gun is described in WO 98/43894 and WO 201 1/151296 A2. A threaded system is for instance described in US 5,271 ,537 and in EP 2576080.

Containers with polyurethane foam intended for the DIY are usually not provided with a ring for screwing or snap-fitting a spray- gun onto them. The valve is usually freely accessible, and may itself be internally or externally threaded, allowing an applicator tube, sold separately or supplied together with the container, to be twisted or screwed onto it, or attached to it in any other suitable way, which is provided with a lever which when pressed tilts the valve and thus allows the valve to be manually opened, and, when released, to be closed again. For this application, the valve should therefore be freely accessible, and it is common for the container for the DIY market segment to be provided with a protective cap which is removably attached to the container, and which thus protects the valve until the time of use. A suitable protective cap is for instance described in EP 2371738 A1 .

The pressure containers or spray cans themselves are usually made of metal, and are usually cylindrical in shape. The bottom is usually formed by a plate, arranged by means of a flange onto the cylinder, and is usually inwardly concave, to be better able to resist the internal pressures while maintaining the ability for the container to be placed upright onto a flat surface. The top is usually provided with a container head, which is also arranged onto the cylinder by means of a flange, and which is usually convex, for the same reasons of a higher resistance to pressure. A filling opening is provided, usually in a central position in the cylinder head.

Filling containers with liquids is a technique used in many industries, such as in the distribution of milk and juices, usually in containers that are not pressurized, or in cosmetics, perfumes or other personal care products. These cases often concern highly fluid and non-viscous liquids, which may readily be introduced through the valve into the already closed spray can.

US 2010/0024910 A1 describes a filling nozzle for a filling station of beverages into containers, whereby the filling nozzle is provided with a very precisely implemented flow straightening plate, allowing the prevention of dripping after the filling, and allowing the liquid streams to always and reliably converge again downstream so as to obtain one stable outflow, without any air being entrained. The outlet openings of the fine holes in the flow straightening plate are specifically aligned and are further provided with a chamfered end so as to achieve the converging of the liquid streams after leaving the nozzle, within a large range of flow rates and with different foodstuffs such as water, tomato juice and corn potage. The flow straightening plate is provided with very special and precise features as to its upper and lower surfaces and the number, positioning and orientation of the fine holes through it, and is therefore manufactured separately from the much less precise filling nozzle into which the plate is mounted. Potential blocking issues are prevented by a suitable selection of the dimensions of the fine holes through the flow straightening plate. The document is not concerned with the replacement of the nozzle in case of problems.

US 2012/0291898 A1 describes an apparatus for quickly filling into containers a precisely measured amount of liquids such as milk and juices, whereby foaming, in particular, is to be avoided, but dripping should also be avoided if possible. The apparatus is provided with a sealing element characterized by two positions. In the first position, only the central part of the nozzle is opened so that, initially, a small amount of liquid enters the container and covers the bottom. The sealing element opens further into its second position with full opening of the nozzle, whereby the filling continues at a higher rate without foaming or splashing. Likewise, while closing the nozzle, the first position is again temporarily employed, so that foaming and splashing are avoided at the end of the filling step as well. This document, like the one described above, is not concerned with the replacement of the nozzle in case of problems.

US 9909290 B2 and the corresponding WO 2015/043854 A1 describe an apparatus for filling free-flowing products, in particular foodstuffs such as milk, fruit juices, sauces and yogurt, without splashing or dripping into cardboard or plastic containers that are non- rotationally symmetrical, but, for instance, comprise rectangular surfaces, and that are closed afterwards by means of a welding operation. The document teaches to adjust, by means of carefully selected number, shape and orientation of the small channels in the nozzle, which is preferably made of stainless steel, the shape of the liquid flow to the surfaces of the packaging. The document is not concerned with replacing the nozzle in case of problems.

Filling a polyurethane foam composition, however, poses additional problems.

During the packaging, the empty container is usually filled through this central filling opening in the head, and this opening is subsequently closed off by securing or“crimping” the valve onto the edge or rim of the filling opening. Many of the components are liquids under atmospheric conditions, and may therefore be filled into the container through the large filling opening, usually an opening of 1 inch in diameter, before closing the can by means of the valve. The propellant gasses intended to provide the higher pressure may then subsequently be introduced into the container after this has been closed off with the valve, through the valve. This often-used method is called“filling under pressure”. The pressure in the can is then further increased after closing the container and injecting the propellant gasses, because an exothermic chemical reaction takes place between the components, in particular after the shaking of the container. The filling of the liquids into the spray can through the central filling opening in the head is usually carried out in a filling station, whereby the empty spray can is put into place into a carousel, and by rotating the carousel in a step-by-step manner, with each step assumes the next place in the filling station. Above several of those places in the carousel, a filling head is mounted, which is lowered onto the spray can. By pressing the filling head further down, the outside of the filling head, with the outer head at its bottom resting on the edge of the filling opening, is pushed upward relative to the central part of the filling head, which is moving further downwards, so that the obturator in the filling head is opened and the liquid may pass through the central part of the outer head into the spray can.

Once the predetermined amount of liquid has been injected, the filling head is raised again. The edge of the filling head with the outer head is pressed by a spring downward again relative to the rest of the filling head which moves further upward, and the obturator in the filling head closes again. The spray can then is detached and released from the filling head, and becomes once again available for being brought to its next position in the carousel.

Due to the high velocity at which it flows through the obturator in the filling head, the liquid receives a strong turbulence the moment that it enters the space of the filling head downstream from the obturator. If the liquid would still flow turbulently at the moment of its release into the spray can, this would lead to uncontrolled splashing and spraying. The liquid therefore risks to partially end up where it does not belong, which would lead to a loss of liquid and to a soiling of the spray can and of the filling station, which, due to the reactive nature of the liquid, is highly undesirable.

In order to break the turbulence before the liquid is released into the spray can, the liquid, upon leaving the space in the outer head downstream from the obturator, is forced to flow through an integrated part of the outer head forming a nozzle. In order to obtain the desired laminar flow when entering the spray can, this nozzle is characterized by a plurality of elongated and narrow channels, usually a series of holes having small diameters, drilled through the bottom wall of the outer head, whereby that wall is given substantial thickness to ensure a high L/D ratio of the liquid channels through the nozzle, so that, owing to the surface tension of the liquid, a capillary action is generated that keeps the liquid inside the small channels and lowers the risk of leaking. Moreover, the small channels through the nozzle at the edge of the nozzle are preferably drilled at an angle, so as to keep the liquid flows apart during filling and to spray part of the liquid against the inner wall of the spray can, further lowering the risk of leaking and/or splashing. This, however, limits the number of holes that may be drilled, and thus has a limiting and therefore detrimental effect on the achievable dosing speed and the pressure buildup in the filling head.

Manufacturing an outer head with an integrated nozzle as described herein is therefore a complex affair. A large number of holes having a small diameter but great depth need to be drilled through the bottom wall of the outer head, which places high demands on the choice of material of the bottom wall of the outer head and of the drill, especially in view of a rapid dissipation of the heat that is unavoidably released during said drilling. Manufacturing such an outer head is therefore a time-consuming and painstaking matter.

The fine channels in the nozzle also give raise to various operational issues during packaging of PU foam compositions.

For one, given the high viscosity of the liquids to be filled, they are susceptible to strong erosion due to the rather high speeds with which the liquid are made to flow through them. The walls between two adjacent channels are very thin in places, and when they are eliminated or damaged by erosion, a larger channel is created, which is more susceptible to cause unwanted turbulent flow and dripping of liquid from the filling head after closing the obturator in the filling head. Those drops will then end up outside of the spray can, or on the carousel of the filling station. Due to the reactive nature of the liquids for PU foam, such soiling renders the spray can unusable or hinders the proper functioning of the filling station.

Furthermore, the fine channels in the nozzle easily become blocked, or may become constricted, when small solid dust particles are present in the liquid, or when crystals and/or solid dust particles are formed, as may occur in the case of an isocyanate liquid. Moreover, an isocyanate liquid is susceptible to polymerization and even to crosslinking and to the formation of a tacky solid substance upon contact with a compound with which it can react. And there are many such compounds, even including water or moisture. When some of the channels become blocked, the liquid velocities in the other channels will further increase, subjecting them to higher erosion. Through a constricted channel the liquid flows with less force, so that drops are more easily formed at the end of the liquid outflow from the nozzle, whereby that drop may remain clinging at the nozzle and not be released until the filling head is no longer above the filling opening of the spray can, again leading to soiling.

It is therefore necessary to replace the outer head with integrated nozzle regularly, and to remove the blockages or constrictions in the small channels. We have found that the soiling in the small channels may be difficult to remove and usually is also very hard, so that the constricted and/or blocked channels have to be drilled out again. This drilling is an additional cause of erosion, in this case of a mechanical nature, so that the small channels will widen even more quickly, leading to the above-mentioned problems.

As a result of this, the outer head with a nozzle, even if cleaned regularly, also needs to be replaced very regularly with a new specimen, and due to the high cost of manufacturing, this replacement represents a major part of the maintenance efforts and the associated costs.

Hence, there remains a need for a filling station and a method for introducing liquids into a spray can for PU foam whereby this maintenance of the outer head with nozzle can be made easier and less laborious.

The present invention aims to avoid or at least alleviate the problems described above and/or to provide improvements in general.

SUMMARY OF THE INVENTION

According to the invention, a method and a filling station are provided as defined in each of the appended claims. In an embodiment, the present invention provides for a filling station for filling liquids for a polyurethane (PU) foam composition into a spray can, through the filling opening before closing the can by means of a valve, whereby at least one filling head of the filling station is provided with an unscrewable outer head containing a removable nozzle therein.

In an embodiment, the present invention provides for a method for filling, using a filling station according to the present invention, of at least one liquid for a polyurethane (PU) foam composition into a spray can through the filling opening before closing the can by means of a valve, whereby at least one liquid filling is introduced into the spray can through the filling head, which is provided with the unscrewable outer head with the removable nozzle.

We have found that providing a removable nozzle makes it easier, in case of problems with the nozzle, to remove the problematic nozzle from the outer head and to replace it with a problem-free specimen. It suffices, after shutting down the filling station, to unscrew the outer head from the filling head, to replace the removable nozzle with a clean or new specimen, and to screw the outer head back onto the filling head. We have found that this setup allows a much simpler and quicker replacement of the nozzle than is possible with the known outer heads and nozzles.

The applicants prefer that the screwed-on outer head has only two parts, i.e. only the outer head itself with its threaded connection onto the filling head, and preferably made of metal, and the removable nozzle, which is attached in the outer head but which is easily removable therefrom, preferably by simply pushing it out. This offers the advantage that the replacement of the nozzle may be carried out in a very simple and quick manner, so that the filling station only needs to be out of service for a very short time to allow this intervention, and may be started up again very quickly. A further advantage is that no additional parts are involved in this intervention, which could become damaged or be lost in or during the intervention. Thus, only one replacement part needs to be kept in stock, namely the nozzle, possibly with a smaller additional stack of the outer head in case that, this too, would have been damaged and would need replacement. We have further found that the removable nozzle is much easier to manufacture, using a much simpler method, than similar arrangements known from the current state of the art. We have found that this allows the cost of the nozzle to be lowered significantly, preferably to the point that the cost of a new specimen becomes so low that the expenses saved by the cleaning and reuse of an already used specimen are insufficient to justify the risk of a possible malfunction of a reused specimen, after a shorter time of reuse than after the first use, or possibly even immediately upon reuse, for instance as a consequence of excess erosion or damage during cleaning.

BRIEF DESCRIPTION OF THE DRAWINGS

Figures 1 and 2 respectively show a bottom view and a cross-section of a removable nozzle according to the present invention.

Figures 3 and 4 respectively show a bottom view and a cross-section of an outer head with removable nozzle according to the present invention.

Figures 5, 6 and 7 respectively show a cross-section, a bottom view and a side view of an outer head according to the present invention.

Figure 8 shows a cross-section of a filling head with an outer head and nozzle according to the present invention.

DETAILED DESCRIPTION

The present invention will hereafter be described in particular embodiments and with possible reference to certain drawings, but the invention is not limited thereto, but is limited only by the claims. The possible drawings are only schematic and are non-limiting. In the drawings, some of the elements may be exaggerated and not drawn to scale for illustrative purposes. The dimensions, including relative dimensions, therefore do not necessarily correspond to the way the invention is implemented in practice.

Furthermore, the terms first, second, third and the like, in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. These terms are interchangeable under appropriate circumstances and the embodiments of the invention can appear in other sequences than those described or illustrated herein.

Moreover, the terms top, bottom, over, under and the like in the description and the claims are used for descriptive purposes and not necessarily for indicating relative positions. The terms so used are interchangeable under appropriate circumstances and the embodiments of the invention may appear in other sequences than those described or illustrated herein.

The term“comprising”, used in the claims, should not be interpreted as restricting to the means listed in context therewith. It does not exclude the presence of other elements or steps. It should be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression“a device comprising means A and B” should not be limited to an object consisting solely of components A and B. It means that with respect to the present invention, A and B are the only relevant components of the device. Correspondingly, the terms “comprising” or “including” also encompass the more limited terms“consisting essentially of” and“consisting of”.

Unless stated otherwise, all ranges indicated in this document also include the extremes, and all values for ingredients and components of compositions are expressed in weight percentages or weight % of every ingredient of the composition.

The expressions “weight percent”, “weight %”, “percent weight”, and variations thereof, denote the concentrations of a substance as the weight of that substance divided by the total weight of the composition and multiplied by 100, unless stated otherwise. The same, mutatis mutandis, applies to“ppm” or“ppm weight” or“weight ppm”, only then by a factor of 1 million (1000000). In this document, “percent”, “%”, “%wt”, are intended as synonyms of “weight percent”.

It should also be understood that, as used in the present patent document and the appended claims, the singular“a” and“an” and“the” also refer to the plural, unless the context clearly indicates otherwise. Thus, for instance, reference to a composition comprising“a substance” also includes a composition having two or more substances therein. It should also be understood that the term“or” is usually employed in its sense of “and/or”, unless the context clearly indicates otherwise.

Moreover, any substance may be discussed mutually interchangeably in the present document by reference to its chemical formula, chemical name, abbreviation, etc....

In the context of the present invention, the terms spray can and pressure container are used interchangeably and are considered synonyms of each other. With the term“container” or“can” may in the context of the present invention not necessarily always be meant a spray can or a pressure container, but these terms should indeed include spray cans and pressure containers.

The pressure containers or spray cans themselves are usually made of metal, and are usually cylindrical in shape. The bottom is usually formed by a plate, arranged onto the cylinder by means of a flange, and is usually concave, the better to be able to resist the internal pressures while maintaining the ability of the container to be placed upright onto a flat surface. The top is usually provided with a container head, which is also arranged onto the cylinder by means of a flange, and which is usually convex, for the same reasons of a higher resistance to pressure. A filling opening is provided, usually in a central position in the cylinder head.

During packaging, the empty container is usually filled through this central filling opening in the head, and this opening is subsequently closed off by securing or“crimping” the valve onto the edge of the filling opening. Many of the components may be filled into the container under atmospheric pressure, and the components intended to provide the higher pressure may then subsequently be introduced into the container after it has been closed off with the valve. This method is called“filling under pressure”. The pressure in the can is then further increased after closing the container and injecting the propellant gasses, because an exothermic chemical reaction takes place between the components, in particular after shaking the container. The propellant gasses could also be introduced at the time of filling of the container, as a sufficiently cold liquid, which may subsequently evaporate after the container is closed. This latter method is however used less and less often, because it usually leads to higher emissions of propellant gasses, with adverse economic and ecological consequences.

The valve for spray cans containing PU foam is characterized, as described above, by a much wider passage than the one on spray cans having a less viscous content, to allow a sufficiently rapid discharge. This wider passage also brings advantages when introducing the propellant gas.

Spray cans containing PU foam are usually much larger than those containing the less viscous compositions listed hereinabove. A spray can containing PU foam often has a content of 1000 ml, while spray cans for other applications are often much smaller, at most 400 ml and often no more than 200 or as little as 150 ml. Usually, the pressure in the spray can containing PU foam is significantly higher than in the other spray cans, mainly because of the higher viscosity of the composition in the can. The amount of propellant gas to be introduced is therefore significantly higher in spray cans containing PU foam than in most other spray cans containing a less viscous contents. The wider passage through the stem of the valve for PU foam offers the advantage that it allows this larger amount of propellant gas to still be introduced quickly, even only through the valve stem, so that the filling step of propellant gas does not, or only rarely, limit the throughput speed of the filling machine.

At room temperature, the pressure in a filled and ready-to-use spray can or container containing 1 k PU foam is typically about 5 bar gauge. The containers are usually capable of not deforming permanently up to a pressure of 18 bar gauge, and are designed not to burst up to a pressure of below 21 ,6 bar gauge. The valve is usually designed to withstand a pressure of at least 22 bar gauge. Other containers exist which are merely capable of remaining intact up to a pressure of 12 or 15 bar gauge.

In an embodiment of the filling station according to the present invention, the outlet side of the outer head is provided with a constriction and the nozzle is provided with a laterally flared widening that is adapted to be blocked by the constriction in the outer head. This offers the advantage that the nozzle is kept in place in the outer head by gravity and by the pressure of the liquid upstream of the nozzle.

In an embodiment of the filling station according to the present invention, the nozzle is provided with a pattern of small channels for guiding the liquid through the nozzle. These channels offer the advantage that the flow of liquid upon leaving the outer head with the nozzle is mainly laminar, and leaves the nozzle with some force. This lowers the risk for a part of the liquid to remain hanging from the nozzle and then, by dripping off later, ending up in places where it is unwanted. This lowers the risk of unwanted soiling of the spray can and/or of the filling station and/or the conveyor belt. An additional advantage is that these channels bring about a higher liquid pressure upstream of the nozzle, so that the latter is better held in place.

In an embodiment of the present invention, the small channels through the nozzle are implemented in parallel. This offers the advantage that more channels may be provided than if at least part of the small channels have to be provided at an angle. This nozzle design offers a larger flow-through area, which allows a higher dosing speed, so that the production rate may be higher, especially in the case of more viscous liquids.

In an embodiment of the filling station according to the present invention whereby the nozzle is provided with a pattern of small channels for guiding the liquid through the nozzle, the small channels have a length/diameter (L/D) ratio of at least 5, preferably at least 6, 7, 8, 9, 10 or 1 1 . This is even better for ensuring a laminar flow of liquid through the nozzle, and thus for lowering the risk even further of soiling of the spray can and/or the filling station and/or the conveyor belt. Moreover, it offers the liquid meniscus forming in a channel a larger surface to adhere to and less contact with the ambient air, so that the meniscus is stronger and there is less risk that the meniscus would break and liquid would move throughout the air in the channel, whereby this liquid could leak from the channel at an undesired moment.

In an embodiment of the filling station according to the present invention, the nozzle is manufactured by additive manufacturing, preferably using 3D printing. The applicants have found that additive manufacturing is a highly suitable method for manufacturing the removable nozzle, a.o. because of the complexity of the nozzle. To allow a certain amount of liquid to be quickly introduced into the spray can, the applicants provide in the nozzle as many channels as possible. As a result of this, the walls between adjacent channels are preferably very thin. If the nozzle would be manufactured using more conventional techniques, and the small channels would be drilled, these thin walls would be the most vulnerable element, because the high localized generation of heat during the drilling could raise the temperature of the material in that thin wall to above its yield point, and the wall could break down. With additive manufacturing, there is much less local generation of heat. The applicants have found that the removable nozzle may be manufactured much more quickly and with higher precision by means of additive manufacturing, so that both the quality and the cost are more favorable.

In an embodiment of the filling station according to the present invention, the nozzle is manufactured from a material selected from metal and plastic, preferably plastic, for instance a thermoplastic plastic, more preferably a photopolymer. The applicants have found that plastic as a material for the removable nozzle offers the advantage that it is more elastic than metal, making it easier to place the nozzle into the space provided thereto in the outer head, simply using manual force, without requiring additional power, while still allowing a proper sealing to be obtained between the contact surfaces of the nozzle and the outer head. Moreover, plastic offers the advantage that the forces required to remove the used nozzle again from the outer head remain limited, so that also this operation may easily be carried out, usually using only manual force.

In an embodiment of the filling station according to the present invention, the filling head, upstream of the nozzle, comprises an obturator for opening and closing the liquid supply. This offers the advantage of a lower risk of liquid still exiting the filling head after the filling head is removed from the spray can, and thus of unwanted soiling of the spray can, the filling station and/or the conveyor belt for the spray cans.

In an embodiment of the filling station according to the present invention whereby the filling head comprises an obturator upstream of the nozzle, the filling head further comprises an outlet chamber in between the obturator and the nozzle.

In the filling station according to the present invention, the empty spray can is placed into a carousel, and by rotating the carousel in a step-by-step manner, that spray can will each time assume the next place in the filling station. Above several of those places in the carousel, a filling head is mounted, which is lowered onto the spray can. By pressing the filling head further down, the outside of the filling head, with the bottom of the outer head resting on the edge of the filling opening, is pushed upward relative to the central part of the filling head, which is moving further downwards, so that the obturator in the filling head is opened and the liquid may pass through the central part of the outer head and through the nozzle into the spray can.

After the predetermined amount of liquid, the so- called“liquid filling”, has been injected, the filling head is raised again. The outside of the filling head is then pressed downward again, preferably by a spring, relative to the rest of the filling head, and the obturator in the filling head closes again. The spray can is detached from the filling head, and is then once again available for being brought to its next position in the carousel.

During the filling of liquids into the spray can, the liquid flowing through the obturator in the filling head locally reaches high speeds, causing turbulence. In order to allow the liquid to settle somewhat again, the applicants prefer to provide an outlet chamber in the filling head.

Due to the high velocity at which it flows through the obturator in the filling head, the liquid picks up a strong turbulence when it enters the space of the outer head downstream from the obturator. If the liquid would still flow turbulently at the moment of its release into the spray can, this would lead to uncontrolled splashing and spraying. The liquid therefore risks to partially end up where it does not belong, which would lead to a loss of liquid and to soiling of the spray can and of the filling station, which, due to the reactive nature of the liquid, is highly undesirable.

In order to break the turbulence before the liquid is released into the spray can, the liquid, upon leaving the space in the outer head downstream from the obturator, is forced to flow through the nozzle. In order to obtain the desired laminar flow, this nozzle is usually characterized by a plurality of elongated and narrow channels.

In an embodiment of the filling station according to the present invention whereby the filling head comprises the outlet chamber, the volume of the outlet chamber is larger with the obturator closed than with the obturator open. This offers the advantage that upon closing the obturator, the liquid is retracted into the outlet chamber, so that the liquid present in the small channels of the nozzle is also retracted over a certain distance. A drop of liquid that would still be present at the end of a channel would then also be retracted into the channel. There is consequently a much lower risk for such a drop of liquid to remain hanging after the removal of the filling head with nozzle from the spray can, and to leak out at an undesired moment to an undesired location in the filling station.

In an embodiment of the present invention, the small channels through the nozzle have the diameter that yields the maximum total flow area through the nozzle without leading to drops of liquid leaking at the bottom of the nozzle. The applicants have found that this maximum diameter may readily be determined empirically and that it is also dependent on the properties of the liquid to be filled through the nozzle.

The retracted liquid column in the channel in the nozzle then forms a meniscus. The intention is that this meniscus, as a result of the surface tension of the liquid and the adhesion forces between the liquid and the material of the nozzle, remains firmly in place, so that no liquid leaks from the nozzle. The applicants have found that it is very easy to determine empirically, given the properties of the liquid and of the material of the nozzle, what is the best diameter for the small channels through the nozzle, which is provided for that specific liquid, to limit the risk of unwanted leaking yet at the same time offer the largest possible flow area so that the highest possible amount of liquid may be pushed through the nozzle in the shortest possible time, but with laminar flow.

In an embodiment of the filling station according to the present invention, at least two and preferably all of the filling heads for filling the polyol composition for the PU foam composition are provided with the outer head with the removable nozzle. This offers the advantage that the desired technical effects of the present invention are obtained in several places in the filling station, and are preferably achieved at all of the filling heads for the polyol composition of the specific filling station. The applicants usually provide three filling heads for polyol composition per filling station, so that the total amount of polyol composition required for one spray can, may be particioned over multiple filling heads, so that the filling takes place more rapidly and more spray cans may be filled per unit of time.

In an embodiment of the filling station according to the present invention, at least one of the filling heads for filling the isocyanate composition for the PU foam composition is provided with the outer head with the removable nozzle, and preferably all of the filling heads for filling the isocyanate composition are provided with the outer head having the removable nozzle. The advantage of the present invention is thereby also achieved when filling the isocyanate composition, and preferably across the entire filling station.

In an embodiment of the method according to the present invention, the filling head comprises an obturator upstream of the nozzle and the obturator closes off the liquid supply after filling at least one liquid filling, and the obturator reopens before filling the next specimen of the at least one liquid filling. This offers the advantage that the risk of leaking of liquid from the filling head between two filling operations is reduced, and hence also the risk of soiling of the spray can at the outside and/or of the filling station and/or of the conveyor belt for the spray cans.

In an embodiment of the method according to the present invention, the obturator closes during the removal of the filling head of the spray can after filling the at least one liquid filling and the obturator opens again during the positioning of the filling head onto the next spray can before filling the next specimen of the at least one liquid filling. The applicants find this a highly suitable embodiment for limiting the risk of leakage while still achieving as high a production rate as possible, because this offers the longest possible time for getting the liquid filling into the spray can.

In an embodiment of the method according to the present invention, the filling head further comprises an outlet chamber between the obturator and the nozzle, and the volume of the outlet chamber increases when closing the obturator. This offers the advantage described above that the liquid in the outlet chamber, and hence also the liquid in the small channels of the nozzle, is retracted, and the risk of undesired leakage is thereby further reduced.

In an embodiment of the method according to the present invention, in case of wear and/or narrowing and/or obstruction of openings in the nozzle, the nozzle is removed from the filling head and replaced by a clean specimen of the nozzle. This offers the advantage that when the nozzle functions less than optimally, for at least one of the reasons mentioned above, the problem may easily be resolved, and the operation of the filling station may swiftly resume without issue. This further offers the advantage of requiring fewer replacement parts, because all parts of the filling head, except for the removable nozzle, may immediately be placed back and therefore no large stock of spare parts is to be kept, apart from the removable nozzle.

In an embodiment of the method according to the present invention, the clean specimen of the nozzle is a newly manufactured specimen of the nozzle. The applicants have found that the costs of a new specimen of the nozzle may be kept so low that cleaning and/or repairing the used nozzle may no longer be justified, and replacement with a new specimen would be preferred.

In an embodiment of the method according to the present invention, the clean specimen of the nozzle is arranged in the outlet of the outer head by positioning the nozzle into the outlet of the outer head, preferably by lightly pressing it into that position. The applicants have found that the nozzle may be manufactured with suitable precision so that it may be secured by simply placing it, preferably lightly pressing it into the outlet of the outer head, and a proper sealing may thereby be achieved between the surfaces of the nozzle and of the outer head that come into contact with each other.

In an embodiment of the method according to the present invention, the nozzle is removed from the outer head by unscrewing the outer head from the filling head in the filling station and by subsequently pressing the nozzle up from out of the outer head in the direction opposite to the flow direction of the liquid through the nozzle. This method works best when the outer head and the nozzle are provided with the constriction and the laterally flared widening described elsewhere in this document. The applicants prefer this method and arrangement because in this way, the liquid pressure during the filling helps to keep the nozzle in its place in the outer head.

In an embodiment of the method according to the present invention, the removable nozzle is removed after use and is not re-used for the same function. The applicants have found that the advantage of reuse after cleaning and/or repair usually does not make up for the risk of problems during the filling process that may occur in the case of reuse due to a faulty nozzle.

In an embodiment of the method according to the present invention, two or more filling heads are provided for filling the polyol composition and at least part of the polyol composition to be filled into a same spray can is filled through the filling head provided with the outer head having the removable nozzle, and preferably the entire amount of polyol composition is filled through a filling head provided with the outer head with the removable nozzle. In this way, the advantages of the present invention are achieved at the multiple filling heads, preferably three filling heads, used in a same filling station for introducing the amount of polyol composition into the spray can.

In an embodiment of the method according to the present invention, two or more filling heads are provided for filling the isocyanate composition, preferably three filling heads, and at least part of the filling of the isocyanate composition is filled through a filling head provided with the outer head with removable nozzle, and preferably the entire amount of isocyanate composition is filled through a filling head provided with the outer head with removable nozzle. This offers the advantage that the desired effects brought by the present invention are achieved when filling the isocyanate composition, and preferably together with the filling of the polyol composition, and more preferably over the entire filling station.

In an embodiment of the method according to the present invention, the method further comprises the step of closing the filled spray can by securing a valve with a valve collar onto the filling opening of the spray can. The spray can is thereby closed so that nothing may enter the can unwantedly anymore, such as moisture from the air, with which the isocyanate groups in the spray can could react.

The container valve or“valve” usually consists of a valve bowl or “valve cup”, i.e., a round metal cup, which is secured or “crimped” along its perimeter onto the central filling opening of the container or spray can, usually icomplemented by means of a rubber seal, usually an O-ring, to prevent leakage of spray can contents via this crimped valve collar.

In the conventional valve, the valve cup supports a central rubber seal, known as“grommet” or“valve rubber”, through which a hollow and usually plastic stem of a valve is inserted. The stem is usually stiff and has a central duct that, just before the stem at its lower end terminates in a blind flange, transitions laterally into one or more, usually four, lateral openings. In a resting state, the rubber gasket pulls the blind flange against the bottom of the gasket, thereby sealing the openings. The valve is designed to be opened by pushing the stem down relative to the gasket or cup, whereby the gasket is usually elastically deformed and whereby at least one of the lateral openings in the stem of the valve becomes available for passing the container contents.

Because the rubber of the gasket of the conventional valve, in particular when powdered carbon is used as filler in the rubber, allows the diffusion of water, which may then react with the still available isocyanate groups in het prepolymer in the container to form a tacky solid substance, the conventional valve has the disadvantage that the blind flange of the valve may over time adhere to the rubber, especially if the container is for some time in a horizontal position. This may already occur when the container is left lying on its side for a period of only 3 to 6 weeks. Due to this adherence, it may become impossible to open the can and extrude the substance. Another disadvantage is that the rubber of the valve seal also allows the diffusion of propellant gasses to outside the container, so that the container may after a while have lost part, or sometimes even all of its pressure. For these reasons, other types of valves were developed that are not allowed to comprise a rubber gasket as described for the conventional valve. Such container valves may also be referred to as "feststof" valves, and suitable variants thereof are for instance described in WO 2009/004097, US 5,014,887, WO 03/062092, or US 5215225, US 5549226 and US 6058960. These valves have no rubber seal, or only a rubber seal at the outside of the valve, that does not contact the contents of the container. These“feststof” valves may therefore be characterized in that the materials of the valve parts that come into contact with the contents of the spray can are virtually impermeable to water and/or propellant gasses, usually materials that are more solid than rubber (“feststof”). The valves may for instance be provided with one or even more than one metal spring, being a coiled spring or a leaf spring or a combination thereof. The spring or springs may be arranged and adjusted in such a way that the valve may be opened more easily than a conventional valve, and therefore offers further improved ergonomics to the user, as well as an improved capacity for aiming and dosing. The springs may also lead to a quicker closure of the valve when compared to the conventional valve. A valve with an internal coiled spring is for instance described in WO 2015/032963 A1 and in US 5,014,887. Valves with external coiled springs may be found as part of the family of the valves MIKAVent PU- RF, available from Mikropakk. Valves with a leaf spring may be found in US 6058960, WO 03/062092 and WO 2009/004097.

Just like conventional valves, these “feststof” valves usually also have a valve cup and a stem. The valve cup of such valves may still be susceptible to deformation. These valves are usually provided with at least one surface for sealing at the outside of the stem of the valve, suitable for forming a seal when contacted with a gun adapter, a dosing gun, or a handheld applicator. These sealing surfaces may consist of strips for improving the sealing action, and these strips may be provided in suitable locations at the outside of the valve. Examples of such strips are described in US 5014887, US 6058960 and in WO 2009/004097.

For safety reasons, containers that are ready for the market are therefore always provided with a protective cap, which is to shield the container valve, and more specifically the valve stem, against damage, tearing or contact, and against shifting relative to the valve plate, and thus for safety reasons and to protect against accidental spilling. The containers for handheld use are typically provided without a gun coupling piece, i.e. with the valve fully accessible. For that reason, such containers are conventionally provided with a separate protective cap that is usually snapped onto the flange around the container head. Containers for professional use, i.e., for use combined with, for instance, a gun, are provided with a gun coupling piece, which is typically snapped onto the flange around the valve plate. Access to the valve stem through this first coupling piece is then typically blocked by means of a separate protective cover, which may for instance snap onto the upper edge of the gun coupling piece, which may suitably be adapted for snapping the cover on, such as by providing a small collar.

In an embodiment of the method according to the present invention, the method further comprises the step of injecting at least one propellant gas into the spray can, preferably through the opened valve. The applicants prefer this method of “filling under pressure” because it limits the possibility of the contents of the can coming into contact with a large amount of moisture from the air, and also because this method is ecologically and economically more acceptable is because less propellant gas is lost to the environment. A highly suitable method for injecting propellant gas into a spray can for PU foam is described in the patent application with reference BE 2018/5924.

In an embodiment of the method according to the present invention, the method further comprises the step of shaking the spray can. In this way, the reaction between the polyol composition and the isocyanate composition to form a prepolymer is promoted.

In an embodiment of the method according to the present invention, the valve is a valve for gun foam. This offers the advantage that, using a suitable tool, the spray can may be suitable for use with a dosing gun, but also, with adequate selection of the tool, for handheld use, i.e. with an applicator for handheld operation, as described below.

In an embodiment of the method according to the present invention whereby the spray can is closed off with a valve for gun foam, the method further comprises the step of attaching an applicator for handheld operation suitable for a spray can with gun foam. An applicator for handheld operation suitable for a spray can with a valve for gun foam is for instance described in WO 2012/052449 A2 and US 10106309 B2. This offers the advantage that in the production line of PU spray cans, only a single supply line needs to be provided, whereby a valve for gun foam may be arranged onto each spray can, but whereby a part of this production may be equipped for handheld use, i.e. aiming more at DIYers or the more occasional users.

In an embodiment of the method according to the present invention whereby the spray can is closed off with a valve for gun foam, the method further comprises the step of attaching a gun coupling piece onto the valve collar, preferably a gun coupling piece with a protective cover. This prepares the spray can for use as gun foam, i.e. using a dosing gun. The protective cover offers the advantage that the valve of the spray can is protected during handling between the production line and the site where it is to be used, until right before being coupled with a dosing gun. A suitable gun coupling piece with a protective cover capable of being broken off is for instance described in WO 2009/004097 A1 . A suitable gun coupling piece where the protective cover is not only removable, but may also be reattached after a first use, is described in WO 201 1/151295 A1 . The latter offers the advantage that the valve may also be protected between an earlier use and a later reuse of the same spray can.

In an embodiment of the method according to the present invention, the gun coupling piece is suitable for attaching an applicator for handheld operation. A gun coupling piece with a protective cover suitable for attaching an applicator for handheld operation is for instance described in WO 201 1 /151295 A1 . The gun coupling piece from WO 201 1/151295 A1 offers the additional advantage that the logistical supply chain only needs to handle a single form of spray can in order to supply both the professional user, who prefers to work with a dosing gun, and DIYers, who prefer handheld operation.

In an embodiment of the method according to the present invention, the valve is a valve for handheld operation. This offers the advantage that, using a suitable tool, the spray can suitable is for use with handheld operation, such as after attaching onto the valve an applicator tube or an applicator for handheld operation with a lever, as already described above. In an embodiment of the method according to the present invention, the method further comprises, after the injection of propellant gas, the step of arranging a protective cap onto the spray can head, preferably a protective cap containing an accessory item, preferably the accessory item comprising at least one plastic glove, more preferably at least one pair of plastic gloves. A suitable protective cap is for instance described in EP 2371738 A1 . This protective cap aims to protect the valve on the spray can during handling between the production line and the site where it is to be used by the user.

EXAMPLES

Figures 1 and 2 respectively show a bottom view and a cross-section of a removable nozzle 1 according to the present invention. The cross-section in Figure 2 was taken along the lines ll-ll in Figure 1 .

Figures 3 and 4 respectively show a bottom view and a cross-section of an outer head 2 with removable nozzle 1 according to the present invention. The cross-section in Figure 4 was taken along the lines IV-IV in Figure 3.

Figures 5, 6 and 7 respectively show a cross- section, a bottom view and a side view of an outer head 2 according to the present invention.

Figure 8 shows a cross-section of a filling head 3 with outer head 2 and nozzle 1 according to the present invention. The Figure also shows the obturator 4, formed by a cone 6, of which the top extends into a bolt with which that cone 6 is screwed into the upper part 7 of the filling head, and of which the side wall is provided with a gasket 8 at the bottom, with which the cone 6 fits against a seat 10 in the lower part 9 of the filling head. While the lower part 9, onto which the outer head 2 is screwed, rests on the filling opening of the spray can, which is not shown, the upper part 7 may move further down, causing the obturator 4 to open, as a result of the cone 6 with its gasket 8 becoming detached from its seat 10. When the upper part 7 of the filling head is raised again after the liquid filling, the cone 6, too, raises again, while the lower part 9 of the filling head is pushed down by the coiled spring 1 1 and still remains on the spray can. The side wall of the cone 6 then again rests with its gasket 8 against its seat 10 in the lower part of the filling head. When the filling head 3 is then further raised, the lower part 9 of the filling head, too, raises with it, so that the outer head 2 is detached from the spray can and the nozzle 1 is removed from the filling opening. All of this preferably takes place in one smooth movement.

It is clear from Figure 8 that when closing the obturator 4 by moving the cone 6 upward relative to the outer head 2 and nozzle 1 , the volume of the outlet chamber 5 increases, so that any liquid present in the small channels in the nozzle 1 is pulled up, lowering the risk of leakage from the nozzle 1 .

Having fully described the present invention, it will be clear to the person skilled in the art that the invention may be carried out using a wide range of parameters within what is claimed, without thereby departing from the scope of the invention, as defined by the claims.