Apparatus for spraying liquids, and disposable containers and liners suitable for use therewith

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DESCRIPTION

Apparatus for spraying liquids, and inner liners and disposable containers suitable for use with these

The present invention relates to a gravity fed spray gun comprising a fluid reservoir and method for providing said gravity fed spray gun.

There are many uses, in many different technical fields, for disposable containers. For example, many goods are packaged in disposable containers (for example, bags) before or after purchase. When the disposable container is a plastic bag, the buyer will often reuse it as a disposable inner liner for another receptacle, for example a garbage can. In some cases, disposable inner liners are manufactured specifically for use in other reusable receptacles: in those cases, the inner liner may be intended to aid in the removal of the contents of the receptacle (as in the case of an inner liner in a bucket of The trash); to protect the receptacle or its contents; or to facilitate, or even eliminate, the cleaning of the receptacle.

The use of an inner liner in a receptacle in which a glue-like substance, paint

or plaster mixed or contained for use may be particularly advantageous, from the point of view of facilitating cleaning of the receptacle after use and preventing substances in the receptacle from being contaminated by the remains of other substances. The receptacles in which paints are mixed or contained for use, for example, must be clean to ensure that the color or quality of the paint is not altered by traces of other substances: this is particularly important, as explained previously, when a vehicle is being repainted and the paint is required to match the existing one. To avoid contamination problems when mixing paints, the implementation in vehicle repair shops is often to use disposable wax paper cups as mixing containers, particularly when only a small amount of paint is required. An alternative approach, proposed in US-A-4,383,635, involves the disposition of a disposable container which, for use, is located in a reusable receptacle similar to a frame.

In the technical field of spray guns, it has been proposed, for various reasons, that a disposable inner liner should be used in the gun tank (see US-A-3,211,324, 3,255,972, 4,151,929 , 4,951,875 and 5,143,294, and EP-A-0 678 334). Generally, guns for spraying liquids (eg, paints, garden chemicals, etc.) are well known and typically comprise a reservoir in which a liquid to be distributed is contained, and a spray nozzle through which distributes the liquid, under pressure, under the control of a trigger mechanism. The liquid can be fed from the tank by gravity and / or it can be carried in a stream of pressurized fluid, for example air or water, which is supplied to the gun from an external source.

In US 3 432 104 or US 5 248 089, spray guns comprising a tank with an inner liner have also been described.

When a user wishes to change the liquid in the tank of a spray gun, it is usually necessary to clean the gun very thoroughly to ensure that no trace of the old liquid that contaminates the new liquid is kept in the gun. This applies particularly to paint spray guns since any trace of an old dose of paint held in a gun can affect the color of a new dose of paint, to the point that the new dose of paint becomes useless. This can cause problems especially in repair shops for vehicles in which the paint applied to a vehicle is often required to match exactly the existing paint. Alternatively, if paint residues have been allowed to dry inside the gun, they can peel and contaminate the new paint dose. Cleaning spray guns is, however, a relatively complex and time-consuming operation. In addition, in the case of paint spray guns, the cleaning operation involves the use of relatively large amounts of solvents that, for environmental reasons, should be handled and disposed of carefully. This, in turn, can be substantially added to the cost of a painting operation. It has already been suggested (see, for example, EP-A-0 678 334 mentioned above) that the use of a disposable inner liner in the paint tank (i.e., the paint can) of a spray gun can simplify Cleaning the gun and reduce the required amount of solvent.

The present invention relates to a gravity fed spray gun as defined in claims 1-4 and to a method of providing a gravity fed spray gun as defined in claims 5-12.

A container is described which is economical enough to be disposable and which can preferably be crushed when it is to be discarded but which, however, is relatively easy to handle and fill when used. More especially, such a container is described which is suitable for use as an inner liner in another receptacle. The request also refers to allowing simplification of cleaning of

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spray guns and similar devices, and thus allow the time and expenses associated with such operation to be reduced.

A container is described comprising side walls and a relatively rigid thermoformed / vacuum formed base from a plastic material; in which the side walls are thin compared to the base and can be crushed, but the container is capable of being straight, without support, on the base with the extended and vertical side walls.

More especially, a container is described, comprising a base, and side walls extending from the base; in which the base and the side walls are thermoformed / vacuum formed together from a plastic material, such that the base is relatively rigid and the side walls are thin compared to the base and can be crushed, but the container is able to be straight, without support, on the base with extended and vertical side walls.

A container can be used as an inner liner for a receptacle, said liner having a shape that corresponds to the inside of the receptacle. As a modification, the invention also describes, in combination with a receptacle, a disposable inner liner that fits inside the receptacle and has a shape corresponding to the inside thereof, wherein said liner is thermoformed / vacuum formed from a material plastic. The inner lining can be crushed.

A gravity-fed spray gun comprising a fluid reservoir is described; a removable inner liner, which can be crushed, having a shape corresponding to the inside of the reservoir, and is a tight fit within it, and a spray nozzle for distributing fluid from within the inner liner, in which said liner is crushed when fluid is removed from the inside during gun operation.

Also, a gravity-fed spray gun, comprising a fluid reservoir having a removable lid located in an opening in the reservoir; a removable inner lining located inside the tank and secured thereto, by the lid, on the periphery of the opening; and a spray nozzle for distributing fluid from within the inner lining; wherein said coating can be removed from the tank together with the lid.

Also described is a gravity-fed spray gun comprising a fluid reservoir having a removable lid located in an opening thereof, and a spray nozzle for distributing fluid extracted from within the reservoir through an outlet in the lid; wherein said reservoir can be disassembled from the gun and is capable of being straight on its own to allow fluid to be loaded into the reservoir through the opening.

In addition, a spray gun comprising a fluid reservoir is described; and a spray nozzle for distributing fluid from within the reservoir; the tank comprising a self-supporting container that can be disassembled from the gun and that can be crushed for disposal.

A fluid reservoir for attachment to a spray gun is described, said reservoir having a removable cover that is located in an opening of the reservoir and in which a fluid outlet for the reservoir is formed; the tank including a removable inner liner, which can be crushed, having a shape corresponding to the tank, and is a tight fit therein; wherein said lining is secured to the tank by the lid on the periphery of the opening and can be removed from the tank together with the lid. A fluid reservoir for fixing to a spray gun is described, said reservoir having a removable cover that is located in an opening of the reservoir and in which a fluid outlet for the reservoir is formed, the fluid outlet for fixing to the spray gun; and an air discharge, which can be closed, at the end of the tank, away from the lid.

An inner liner is described for use in the tank of a spray gun, said liner being formed from a plastic material and a tight fit within the reservoir; the inner lining having a relatively rigid base, and side walls that are thin compared to the base and that can be crushed.

A spray gun comprising a fluid reservoir is described, and a spray nozzle for distributing fluid from within the reservoir, said reservoir having a removable cover and including a removable, generally conical, grid filter secured in the reservoir by the lid.

A gravity-fed spray gun comprising a fluid reservoir and a spray nozzle for distributing fluid from within the reservoir is described, said reservoir having a removable cover and a removable inner liner secured in the reservoir by the lid.

The term "vacuum thermoforming / shaping", as used herein, means a method by which a sheet of material is heated to a softened state and shaped into a required shape, defined by a mold, while in said softened state. It includes the case in which

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it uses the application of a differential air pressure to help shape the material in the required form and, in particular, includes the case where there is a vacuum on one side of the material to help shape it in the required form (also known simply as "vacuum forming").

The term "that can be crushed", as used herein with reference to the side walls of a container / inner liner according to the invention, indicates that the side walls can be distorted so that, by the application of moderate pressure (for example, manual pressure), the rim of the container can be pushed towards the base of the container, without breaking said walls.

The term "paint" is used herein to include all forms of coating material as a paint that can be applied to a surface using a spray gun, whether or not it is intended to color the surface. The term includes, for example, primers, basecoats, varnishes and similar materials.

By way of example only, embodiments of the invention will be described with reference to the drawings to be

they accompany, in which: Figure 1 is a perspective view of a spray gun of the prior art, shown partially disassembled, so that it can be filled with paint;

Figure 2 shows the components of an alternative form of paint deposit for the gun of Figure 1, in

an exploded state; Figure 3 shows the paint tank of Figure 2, in an assembled state, with an adapter for connecting said tank to a spray gun;

Figure 4 shows a longitudinal cross section through the paint reservoir and the adapter of Figure 3; Figure 5 shows the paint reservoir of Figure 4 when attached to a spray gun; Figure 6 shows the paint tank of Figure 4 when used on a spray gun; Figure 7 shows components of the paint reservoir of Figure 4 that are disassembled after use;

Figure 8 is similar to Figure 2, but shows a modified form of paint deposit; Figure 9 shows a longitudinal cross-section through an alternative cover form for the paint tanks of Figures 2 to 4, and 8;

Figure 10 is similar to Figure 2, but shows another modified form of paint deposit; Figure 11 shows part of a longitudinal cross section through the paint reservoir of Figure 10; Figure 12 shows a spray gun similar to that of Figure 1, but with an alternative form of deposit

Of paint; Figure 13 shows the gun of Figure 12 with a modified form of paint reservoir; Figure 14 illustrates a modification of the gun reservoir of Figure 13; Figure 15 is a view, similar to Figure 3, of an alternative form of paint deposit; Figures 16 and 17 show modified forms of a component of Figure 15; Figure 18 illustrates the use of a support for the paint reservoir of Figure 15; Figure 19 is a perspective view of an inner liner / container according to the invention; Figure 20 is a similar view, but showing the inner liner / container in the process of being crushed to

its elimination;

Figures 21 (a) to 21 (c) are diagrammatic illustrations of a method for manufacturing an interior coating for the paint deposits of Figures 2 to 4, and 10; Figure 22 illustrates a modification of the method of Figure 21; Figure 23 shows a graduated jug of paint mixture; and Figure 24 shows an inner liner for use with the graduated jug of Figure 23.

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Figure 1 of the drawings illustrates a paint spray gun 1 typical of the prior art of the gravity fed type. The gun 1 comprises a body 2, a handle 3 extending downwardly from the rear end of the body, and a spray nozzle 4 at the front end of the body. The gun is manually operated by means of a trigger 5 which is pivotally mounted on the sides thereof. The paint tank, or paint can, 6 containing paint (or similar material) to be discharged by the gun, is located on top of the body 2 and is in communication with an internal passage passage (not visible) for air compressed, which extends through the gun from a connector 7 at the lower end of the handle 3 to the nozzle 4. When used, the connector 7 is connected to a source of compressed air (not shown) so that when the user pulls the trigger 5, compressed air is supplied through the gun to the nozzle 4 and drags and atomizes paint that it is being supplied by gravity from the canister 6. The paint is then discharged through the nozzle 4 with the compressed air, as a sprayed substance.

The paint that is contained in the canister 6 is often mixed by hand (for which an independent receptacle, for example a jug is required), and is poured into the canister. To ensure that there are no unwanted particles in the paint, which would deteriorate the finish of the painted surface, the paint is usually poured into the canister 6 through a filter. Figure 1 shows the lid 8 of the canister 6 removed for this purpose, and a conical filter 9 about to be located at the open end of the canister. The filter 9 is shown as being a known type of disposable conical filter, which has solid sides and a portion of filter mesh 10 at the pointed end of the cone. When the canister 6 has been filled with paint, the filter 9 is disassembled and discarded, and the canister lid 8 is replaced. If the filter 9 is a reusable filter, then, similar to the gun, it should be thoroughly cleaned before it is used with a different liquid (for example, a paint of a different color or a liquid that has a different chemical composition) .

Figure 2 illustrates the components of an alternative form of paint can 11 that can be used with the gun 1 of Figure 1 (or any similar gun) instead of the canister 6. The alternative form of paint can 11 is shown mounted in figure 3 and (in cross section) in figure 4.

The paint can 11 comprises an open container 12, comparable in size to a usual paint can of a hand spray gun, which has a hole 12A for air at its base and provided with a disposable inner liner 13. The inner lining 13 corresponds in shape to the inside (and is a tight fit therein) of the container 12 and has a narrow flange 14 at the open end that sits on the upper edge of said container. The container 12 also has a disposable lid 15 which is a push fit at the open end of the inner liner 13. The lid 15 has a central opening 16 (Figure 4) from which a connector tube 17 provided, at its end, extends. , of outward extensions 18 that form a part of a bayonet connection. The opening 16 is covered by a filter mesh 19 that can be adjusted by pushing into the opening or can be an integral part of the lid 15. The lid 15 is held firmly in place on the container 12 by means of an annular collar 20 that is screwed into said container, on top of said lid.

The paint can 11 is fixed to the spray gun 1 thanks to the use of an adapter 21 shown, separated from the paint can, in figure 3 and (in cross section) in figure 4. The adapter 21 is a tubular component which, at one end 22, is formed internally with the other part of the bayonet connection for fixing to the connector tube 17 of the paint can 11. At the other end 23, the adapter is shaped to match the standard fixing element of the paint can of the spray gun (typically a screw thread).

The inner lining 13 of the paint can 11, as already mentioned, corresponds in shape to the inside of the container 12 and has a narrow flange 14 at the open end that sits on the upper edge of the container. As described below, the inner liner is self-supporting, but it can also be crushed and preferably has a relatively rigid base 13A and relatively thin side walls 13B so that, when crushed, it is in the longitudinal direction in which it is crushed, by the side walls, instead of the base. In addition, the inner lining 13 does not have creases, corrugations, seams, connections or reinforcements, and neither grooves in the internal junction of the side walls 13B with the base 13A. Such an inner liner will be described in more detail below with reference to Figures 19 and 20. A thermoforming process, by which such inner liner can be manufactured, is also described below.

The container 12 of the paint can 11 is formed from a plastic material, for example polyethylene or polypropylene, and can be translucent (as shown in Figure 2) or opaque, and of any suitable size. For use with a paint spray gun, containers that typically have a capacity of 250, 500 or 800 ml could be used, although other sizes could be used, if required. The cover 15 is also formed from a plastic material, for example, polyethylene or polypropylene, and may be formed by an injection molding process. The lid may be translucent or opaque and may be colored. The collar 20 may be a molded plastic component, or it may be a machined metal component (eg aluminum). The adapter 21 can be a machined metal component and can be shaped, for example, from aluminum and be anodized.

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To use the paint can 11, the adapter 21 is fixed (at the end 23) to the spray gun and left in position. Next, with the paint can 11 removed as shown in Figure 2, the inner lining 13 is pushed into the container 12. Next, the paint is introduced into the container, the lid 15 is pushed into place and The collar 20 is fixed with screws tightly to keep the lid in position. The upper portion of the inner liner 13 is then trapped between the lid 15 and the container 12, and the rim 14 of the inner liner is caught between the upper edge of the container and the collar 20, as shown in Figure 4. Advantageously, the cover 15 is formed with protruding elements (not visible) on its surface to be applied to the upper part of the inner lining and hold it. The spray gun 1 is then reversed from its normal operating position so that the end of the connector tube 17 can be fixed to the adapter 21, as illustrated in Figure 5, after which the gun can be returned to its position normal (illustrated in figure 6) and is available for use in the usual way. As the paint is removed from within the inner liner 13, the sides of said liner are crushed as a result of the lower pressure inside the inner liner. The base of the inner lining, being more rigid, retains its shape so that the inner lining tends to crush in the longitudinal direction instead of the transverse one, thereby reducing the possibility of trapped paint pockets in the inner lining. .

The user can choose to evacuate the air from inside the inner liner 13 before operating the spray gun 1, although this is not essential. However, the range of angles in which the gun will operate satisfactorily is increased, since there is no risk of air entering the gun from the paint can

eleven. To evacuate the air from inside the inner lining 13, the trigger 5 of the gun should be operated while it is still in the position shown in Figure 5.

After use, when the gun is to be cleaned, the gun can be reversed again and the trigger 5 can be operated briefly to allow the paint inside the gun to drain back into the inner liner in the canister 11 The canister 11 is disassembled from the gun then separating the connector tube 17 from the adapter 21 (which is held on the gun). The collar 20 is removed from the container 12, and then the lid 15 is removed, carrying with it the crushed inner liner 13, as shown in Figure 7. The lid (including the filter 19) and the inner liner are discarded, leaving container 12 and collar 20 clean and ready for reuse with a new inner liner and lid. Only the gun itself has to be cleaned, resulting in a substantial reduction in the amount of solvent used. The risk of spillage of unused paint from the canister 11 is also substantially reduced, since the inner liner 13 is removed and discarded with the lid 15 in place. In addition, since the inner liner is discarded in a crushed state, the amount of space required to collect used inner liners is minimized.

Since the inner lining 13, as described above, is a precise fit within the container 12 and has a uniform internal surface, it is possible to mix paint in the container 12 itself rather than in a separate receptacle. In this way, cleaning of an independent mixing receptacle can be eliminated to achieve a further reduction in the amount of solvent used. This possibility does not exist when a gravity-fed gun with a usual paint can is used, as shown in 6 in Figure 1, since the latter is open at both ends. The possibility that the mixing utensil punctures or damages the inner lining 13 is minimized, firstly since the inner lining fits within the container 12 accurately and, secondly, since the self-supporting nature of the inner lining (described in continued) means that it is less likely to be dragged spinning inside the container during the mixing process. To facilitate the use of the container 12 as a mixing receptacle, the side walls of the container may be provided with marks 25 (Figures 2 and 3), which allows determining the volume of the contents of said container. The general shape of the container 12 and, in particular, the fact that it is flat and stable when it is in the orientation shown in Figure 2, makes it particularly suitable for use as a mixing receptacle, such as the fact that it is translucent as already described. If, however, the container 12 is opaque, it could be formed with grooves in the side walls, through which the inner lining 13 could be seen to allow the user of the spray gun to evaluate the amount of paint in the Boat 11 at all times.

When paint is mixed in the container 12, the inclusion of the filter mesh 19 in the lid 15 of the container prevents unwanted particles in the paint from entering the spray gun. The mesh 19 can be omitted, however, if the paint is textured, or if it is mixed in a separate receptacle and filtered when it is transferred to the coated container 12 or if the presence of impurities in the paint is not important.

Although the collar 20 of the paint can 11 has been described above as being an independent article, it could be combined with the cover 15, in which case it would also be disposable. As an additional alternative, the cover 15 (with the connecting tube 17 and the mesh 19) could be formed as an integral part of the inner lining 13, to which it could be connected by an articulated connection 26, as illustrated in Figure 8. In that case, there is no need for the lid to fit inside the mouth of the inner liner to ensure that the lid and the inner liner will be disassembled together from the container after use: however, that would still be necessary if required. that the lid remains in place in the inner liner after use. As another additional alternative, collar 20 could be replaced by a band secured around the top

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of canister 11 to keep lid 15 and inner liner 13 in place. The band could be secured to the canister 11 and could be formed, for example, from rubber or be part of a firm metal fastening arrangement of the type used to secure the upper parts of jars and bottles.

If a more positive application is required between the lid 15 of Figures 2 to 4 and the inner liner 13, the lid could be an elastic jump adjustment with the inner liner, rather than a push fit, as shown. The inner lining could be shaped, for example, with an inner circumferential rib located to be applied in a corresponding groove on the adjacent surface of the lid.

As a further alternative, the inward push cover 15 could be replaced by a cover 27 with the shape shown in Figure 9. The cover 27 is also a push fit within the inner liner, but is generally conical in shape and its upper end 28, corresponds in shape with the end of the connector tube 17 of Figures 2 to 4, so that it will be applied to the same adapter 21. The cover 27 has an outwardly extending flange 29 that will seat over the upper portion of the inner liner 14, and a shaped portion 29A that will be applied to the inner surface of the inner liner. The shape of the shaped portion 29A allows the lid 27 to be pushed into the mouth of the inner liner and also provides a recess 29B in which the edge of the inner liner can be contracted so that the lid is securely located. The shape of the shaped portion, illustrated in Figure 9, is not essential, however, and alternatives could be used that include, for example, protruding elements, as described above with reference to the cover 15 of Figure 4. The lid 27 is held in place on the container by a threaded collar, similar to the collar 20, which will sit on top of the flange 29 of the lid. The cover 27 can incorporate a filter similar to the filter 19 of Figures 2 to 5. Alternatively, in each case, the filter can generally have a cylindrical shape so that it can be inserted into the tubular part of the cover from the end adjacent to the bayonet connection. In that case, the internal shaped element of the tubular part of the lid should ensure that the filter is held in position when the spray gun is being used.

The components of an alternative form of paint can 30 are illustrated in Figure 10. Can 30, similar to can 11 of Figure 2, comprises a container 12 and an inner liner 13. In this case, however, the filter 19 of canister 11 is formed as an independent article 31 that has a diameter corresponding to that of container 12 and that includes a circumferential seal 32. In addition, the lid 15 and the collar 20 of the canister of Figure 2 are replaced by a generally conical lid 33 which is a threaded fit in the container and which, at its upper end has a tubular extension 34 similar to the connector tube 17 of Figure 3, so that it will be applied on the same adapter 21. The canister 30 is mounted by pushing the inner liner 13 into the container 12 and then, after paint has been introduced into the container, placing the filter 31 on the top of the container and securing it in position by fixing it with screws of the cover 33. The flange 14 of the inner liner 13 and the sealing gasket 32 ​​of the filter 31 are both then trapped between the lid 33 and the container 12, as illustrated in Figure 11, thus preventing paint leakage from the canister 30 in this position when the canister has been secured to a spray gun and is inverted for use.

The adapter 21 could be dispensed with by forming the ends of the tubular parts 17, 34 of the lids of the containers 11, 30 with screw threads so that they can be applied directly to the fixing element of the standard paint can on the spray gun 1.

Figure 12 illustrates an alternative spray gun that is not in accordance with the invention in which the standard paint can 6 of the spray gun 1 (see Figure 1) is retained and is provided with an inner liner 35 that fits within the canister and preferably extends into the connection with the body 2 of the gun to form a liquid tight seal with the latter, for example, thanks to the use of a flexible O-ring (not visible) between the gun and the inner lining. In this case, the inner lining 35 does not crush when the paint is removed from inside the can and can be formed from a more rigid material to aid its positioning within the can 6. Once in position, the inner liner 35 is held in place by the cover 8 which is fixed with screws on a flange 36 extending outwardly at the open end of the inner liner. The canister 6 of Figure 12 is additionally provided with a filter 37 which is generally conical in shape and is completely formed of mesh material and which, when used, is located within the inner liner 35. The filter 37, similar to the inner lining 35, has an outwardly extending flange 38 that is located on the top of the inner liner 36 and is also held in place by the lid 8 of the canister 6.

The canister 6 of Fig. 12, unlike the canister 11 of Fig. 3, is intended to be filled with paint while it is fixed to the spray gun 1. The inner liner 35 and the filter 37 are placed in position, paint is poured in the boat, and the lid fits. During this operation, there is no risk that the filter will be dislodged and, since the filter is formed entirely of mesh material, the user can always see the level of the paint while it is being poured into the can. The gun 1 is then available for use. All the paint distributed by the gun passes through the filter 37 and there is no need, therefore, for the paint to be filtered when it is being poured into the canister 6. After use, the cover 8 is unscrewed to allow the filter 37 and the inner liner 35 to be disassembled. The inner liner 35 is discarded and the filter 37 is also discarded or cleaned, depending on whether or not it is disposable. The use of inner lining 35 reduces

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again the amount of solvent required to clean the gun 1, an additional reduction being possible thanks to the use of a disposable filter 37.

The filter 37 may have any suitable shape and may have, for example, grooved sides to increase the effective surface area of ​​the filter.

In a modified arrangement that is not in accordance with the invention illustrated in Figure 13, the inner liner 35 and the filter 37 are combined to form a single unit 39. In this case, the filter is discarded with the inner liner.

In each of the arrangements shown in Figures 12 and 13, the inner liner 35 and the filter 37 can be removed from the canister 6 with the lid 8. In that case, it is possible to replace the usual lid 8 of the canister 6 with a lid disposable, so that the lid 8, the inner lining 35 and the filter 37 can be discarded together.

The disposable unit 39 of Figure 13 could be modified so that the paint can 6 of the spray gun 1 was replaced, instead of being fitted inside the paint can. In that case, the unit 39 could be supplied as a sealed cartridge 50 already filled with paint as illustrated in Figure 14. Externally, the cartridge 50 is similar to the paint can 6 and can be connected to the gun 1 in the same way . Since it is sealed, however, the outlet end 51 of the cartridge must be perforated and an air discharge arranged, for example at the other end 52 of the cartridge, to allow the paint to enter the gun. The user could pierce, for example, the outlet end 51 of the cartridge 50 before the cartridge (with the highest outlet end) is fixed to the gun (inverted). Alternatively, the gun 1 could be modified so that the outlet end 51 was automatically pierced when the cartridge 50 is attached to the gun. An air discharge could then be formed at the other end 52 of the cartridge 50 after having fixed the cartridge to the gun by manually piercing said end of the cartridge or, for example, by fixing a separate cover 53 that is designed to pierce the cartridge when It is placed in position. Alternatively, an air discharge, which simply has to be opened when the gun is available for use, could be preformed in the cartridge.

After use, the cartridge 50 is removed from the gun and discarded. Since the cartridge 50 contains a filter, there is no need for the supplier to filter the paint before it is loaded into the cartridge. If, however, the paint is prefiltered, then the filter in the cartridge 50 can be omitted.

Figure 15 illustrates an alternative form of paint can 40 for a spray gun 1 which is not in accordance with the invention, which is completely disposable. Paint can 40 is similar, generally, to can 30 shown in Figure 10 except that the container 12 is replaced by a disposable container 41, described below, and the inner liner 13 is omitted.

The container 41 of Figure 15 can be any usual disposable container suitable for holding paint and for attachment to the lid 42 of the paint can. The container 41 may be formed, for example, from a thin, preferably translucent plastic material (as shown), so that the contents of the container are visible and preferably have marks 43 on the side walls to allow the determination of the volume of the contents of the container. An air hole 44 is formed in the base of the container, along with some means to close the air hole when desired. Said means may be in the form of a strip of adhesive tape (not shown) that is detached again to open the hole 44 and can be re-adhered to close the hole when required. Alternatively, a top closure can be provided that is removed at once

or some simple manually operated valve mechanism. The container 41 has an external screw thread at its open end, for fixing the cover 42, which is generally similar to the lid 33 of Figure 10 and is also shaped, at its upper end 42A, for fixing to a spray gun (if necessary by means of a suitable adapter). The lid 42 may be formed from the same material as the container 41 and, as shown, may also be translucent. A flat filter mesh 45, which is also disposable, extends through the mouth of the container 41. The mesh 45 may be a separate article, which is maintained at its periphery between the lid 42 and the container 41, or it may be formed integrally with the lid.

To use the canister 40, the lid 42 and the filter mesh 45 are removed from the container 41 which is then filled with paint (taking care that the hole 44 for the air in the base of the container is closed). It is not necessary to filter the paint when it is introduced into the container 41 and, as described above, it is possible to mix the paint in the container, thereby avoiding the need for an independent receptacle with that objective. The lid 42 and the mesh 45 are then put back into position on the container 41, the lid 42 is fixed to the spray gun (inverted) 1 which is then returned to its normal position, and the hole 44 is opened for the air in the base of the container. Spray gun 1 can now be used as usual. At the end of the spraying operation, the air hole 44 is closed again, the canister 40 is separated from the gun 1 and can then be discarded leaving only the gun to be cleaned. Before the canister 40 is separated, the spray gun 1 can be reverted and the trigger 5 of the gun actuated to allow the excess paint held in the gun to drain back into the canister. In any case, if sufficient paint is maintained in the canister 40, said canister could be resealed (instead of being discarded) and used again.

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Advantageously, the container 41 of the canister is shaped so that it can be crushed after use. In some cases, it may be possible that the lid 42 can also be crushed.

Alternatively, the cover 42 could be a reusable component and would be cleaned together with the gun. With such an arrangement, it is possible that the disposable container 41 is supplied as a cartridge already filled with paint and sealed by a cover that would simply be removed before attaching the container to the lid 42. The filter mesh 45 could be a component disposable or reusable one. As an additional alternative, the container 41 and the lid 42 could be supplied together as a sealed cartridge by a removable cover, at the upper end 42A of the lid, which would be removed before attaching the cartridge to the gun. Thus, the cartridge is similar to the cartridge 50 of Figure 14.

Through an appropriate selection of the dimensions of the lid 42 of the paint can 40, it is possible to use a single lid 42 with containers 41 of different sizes. The user would then select, in each case, the container 41 containing the most suitable amount of paint. It may also be desirable to provide a range of filters 45 having different mesh sizes so that the user can select the mesh size that is most suitable for the type of paint being used. It is not essential that the filter mesh 45 have the shape and / or position shown in Figure 15: it could have, for example, a conical shape, as shown in Figure 16, and / or it could be located at the outlet of cover 42, as shown in figure 17. Alternatively, the filter 45 can be omitted if the paint is filtered before it is introduced into the container 41, or if the presence of impurities in the paint is not important.

The cover 42 does not have to have the exact shape shown in Figure 15 and could be replaced, for example, by a push-in cover in combination with a threaded collar, as shown in Figure 2.

When the container 41 (with or without the lid 42) is supplied as a cartridge containing paint (or other coating material) it may be desirable, in some cases, for the paint / coating material to be contained in a sealed inner liner, that can be crushed inside the cartridge. This may be desirable, for example, if it is necessary to keep the paint / coating material isolated, for example from air or light, until they have been sprayed onto the surface to be coated. The air hole 44 in the container 41 can then be kept open all the time, or it can be omitted if the container 41 itself is not airtight.

Depending on the shape of the container 41, it may be desirable to provide a support on which the container can be placed to ensure that it will not tip over. A suitable support 50, shown in Figure 18, comprises a portion 51 of the container that is similar in shape to container 41, but is slightly larger than it, and is provided with an enlarged base 52. The container 41 is placed in the part 51 of the container to ensure that it remains vertical while it is being filled and / or fixed to the spray gun 1.

Although the above description refers to a paint spray gun, it should be understood that it also applies to other types of spray guns including, for example, guns of the type that are attached to flexible water pipes (instead of to supply pipes air) to spray substances such as garden chemicals. The description also applies to guns powered by aspiration, that is, guns in which the liquid outlet from the reservoir is located at the top of the tank when the gun is being used and liquid is withdrawn from the tank through a tube of supply by the action of compressed air or other pressurized fluid circulating through the gun. In that case, when the tank is provided with an inner liner, the construction of the inner liner and / or the supply tube should be such that the inner liner can be crushed without blocking the supply tube. For example, a short supply tube can be used as long as all air is removed from the inner liner before using the gun. Alternatively, a flexible supply tube could be used, which would be crushed with the inner liner. As a further alternative, a modified inner liner that does not have a rigid base could be used, so that the inner liner is crushed differently from the inner liner 13 of Figure 2. Since the tank of a suction-fed gun is not reversed during use, such as a gravity-fed gun, it is possible to omit the air hole in the tank, provided that the connection between the tank and the gun allows it to enter air in the space between the tank and the inner lining.

Turning now to the paint can 11 of Figure 2, the inner lining 13 will be described in greater detail below, together with a method by which it can be manufactured. The inner lining, shown in isolation in Figures 19 and 20, is preferably transparent and thermoformed from a single piece of plastic material, preferably polyethylene or polypropylene. The internal shape of the container 12 imposes the shape of the inner lining. The relatively rigid base 13A is circular and the inner lining 13, similar to the inside of the container 12, is generally cylindrical, but tilts slightly inwardly from the mouth towards the base 13A. The flange portion 14, similar to the base, is also relatively rigid but the side walls 13B are flexible and, as already described, they can be made to crush. However, the inner lining 13 is capable of being straight, without support, on the base 13A with the side walls 13B extended and vertical as shown in Figure 19. When the inner lining 13 is crushed, the relatively rigid base 13A retains its shape but approaches the portion of the flange 14 of the inner liner as a result of the crushing of the side walls 13B, as illustrated in Figure 20. The side walls 13B are crushed, similar to a plastic bag, without breaking (for example, by separation, tearing or cracking).

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In one form, the inner liner has a height of approximately 110 mm, a diameter at its base 13A of approximately 78 mm and a diameter at its mouth (excluding the portion of the flange 14) of approximately 86 mm. The base is about 400 µm thick, the flange portion 14 is about 900 µm thick, and the side walls 13B are about 150 µm thick. In another form, the inner lining has the same height and the same diameters at its base and its mouth, but the base is about 300 µm thick, the flange portion is about 200 µm thick, and the side walls 13B they have a thickness in the range from 50 to 250 µm.

A method of manufacturing an inner liner, as shown in Figure 19, will be described below with reference to Figures 21 (a) to 21 (c).

A sheet 60 of low density polyethylene (LDPE), approximately 250 x 225 mm and 0.5 mm thick, was tightened by its periphery in the molding frame 61 of a vacuum forming machine. The LDPE material is commercially available, for example, from the firm Plastech Extrusions Ltd. of Widnes, Cheshire, England, and the vacuum forming machine used was the "FLB 725" model of the CR Clarke and Company Limited of Ammanford, Carmarthenshire, Wales. It will be appreciated, however, that any suitable plastic material could be used and that the method could be carried out using any suitable vacuum thermoforming / forming machine.

After the sheet 60 was placed in position, the heater bank 62 of the vacuum forming machine was moved to a position above the sheet (as shown in Figure 21 (a)), and the sheet was heated to a soft, flexible state, suitable for vacuum forming. The fact that the sheet reached the appropriate temperature could be seen by the change in its appearance from milky to transparent.

The heater bank 62 was then disassembled and the thick plate 63 of the mold was displaced upwardly from beneath the sheet 60, leading the mold 64 to contact the sheet to deform it in an upward direction. At that time, the machine's vacuum pump was turned on to extract air from under sheet 60. The upward movement of the thick plate 63 of the mold continued until said plate reached the upper part of its stroke, in which it was sealed against the frame 61 that holds the sheet 60 (Figure 21 (b)). The mold 64 had a shape corresponding to the internal shape of the container 12 of the paint can 11 of the spray gun.

The operation of the vacuum pump continued with the thick plate of the mold sealed against the frame 61 and the pressure difference created between the upper and lower sides of the sheet 60 made the latter (which was already in contact with the upper part of the mold 64) will come down to contact the sides of the mold (figure 21 (c)). The thick plate 63 of the mold was then removed from the cooled sheet 60, leaving a molded portion 65 with the desired shape of the inner liner 13 and without any crease, corrugation, seam, connection or reinforcement, or some groove in the internal joint of the side walls 13B with the base 13A. Following its disassembly of the frame 61, the sheet 60 was cut around the mouth of the molded portion 65 to form the flange 14 of the inner liner 13. The width of the flange 14 is determined by the position in which the sheet 60 is trimmed at this stage, and can be adjusted as required.

The process described above was found to produce a molded portion 65 (and, consequently, an inner liner 13) in which part of the plastic sheet 60 that had been in contact with the sides of the mold 64 during the forming process was substantially thinner than the part that had been in contact with the upper part of the mold. The process differs from a usual vacuum forming procedure that would aim to eliminate, as much as possible, any difference in thickness in the molded portion 65 and, for this purpose, would include the additional step of applying air pressure to the part of below the heated sheet 60, after step (a) of Figure 21, to cause the sheet to take a dome shape before the thick plate 63 of the mold is sealed against the frame 61: the thickness of the sheet would then be relatively uniform when it comes into contact with the mold 64 in step (c) of Figure 21. Generally, in the procedure illustrated in Figure 21, for a given sheet size 60, the size From mold 64 it has been found that it affects the thickness of the sides of the resulting inner liner 13 rather than the base. In other words, if the size of the mold 64 is increased, the thickness of the base of the resulting inner liner 13 will be approximately the same, but the sides of the inner liner will be much thinner. On the other hand, if the size of the mold is reduced, it can be discovered that a point is reached where longitudinal folds appear on the sides of the inner lining 13.

If a further reduction of the thickness of the sheet 60 is required in case you contact the sides of the mold 64 in the step (c) of Figure 21, the sheet 60 may be located between two thin metal plates 66 (Figure 22 ) when it is tightened in the frame 61 of the forming machine, each metal plate 66 having a hole 67 in a mold position 64 and a size larger than the largest cross-section of the mold. The plates 66 are also tightened in the frame 61 and the procedure of Figure 21 is repeated below. The effect of the plates 66 is that only the central portion of the sheet 60 is directly exposed to the heaters 62 and is extracted on the mold 64 when the latter has been displaced upwards (in this case, through the holes 67 in the plates 66). Thus, somewhat less of the sheet 60 is used in the formation of the molded portion 65 and the resulting inner liner 13 will have a base 13A and a shoulder 14 slightly

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thinner and substantially thinner side walls 13B. It is also possible to obtain a comparable result using only the upper plate 66 shown in Figure 22.

As a modification of the procedure illustrated in Figure 22, the plastic sheet 60 may be in the form of a disk of material that is pressed in its periphery between the two plates 66. Depending on the size of the disk, the tight periphery may then form the flange 14 of inner liner 13 and there may be no excess material to be trimmed.

It has been found that an inner liner 13 manufactured by a procedure such as that described with reference to Figures 21 and 22 will be crushed as described with reference to Figure 20 when used in the reservoir 11 of the spray gun of Figure 2 The inner liner 13 can also be crushed by hand by pushing the base 13A of said liner towards the flange 14. It has been found that the inner liner is typically capable of being straight, unsupported, on its base 13A and this characteristic, although not essential for the use of the inner liner in the tank 11 of the spray gun, may be useful for storage targets The inner lining has no folds, corrugations, seams, connections or reinforcements, and no grooves in the internal junction of the side walls 13B with the base 13A: consequently, there are no internal places where material can be trapped inside the inner liner . The base 13A of the inner lining will, of course, occupy a certain space in the base of the container 12 of the tank 11 of the spray gun and the marks on the wall of the container 12 have to be located to take this fact into account.

Although the inner lining 13 of Figure 19 has been described for use specifically in the paint can 11 of Figure 2, the same or a similar article can be used in other ways (in short, if necessary for appropriate dimensional changes ). For example, an article of the type illustrated in Figure 19 can also be used as an inner liner in many different receptacle forms of a spray gun reservoir. It is often desirable to provide a receptacle with a disposable inner liner, for example to keep the receptacle clean, in order to facilitate cleaning, or to protect the receptacle or its contents. An inner liner of the type illustrated in Fig. 19 can be used for any of these purposes and is especially useful in receptacles in which substances are mixed with each other since there are no places on the inside of the liner where material and Stay unmixed.

An article of the type illustrated in Figure 19 can be used, for example, as an inner liner in a receptacle intended to mix paint in a vehicle repair shop, in which case it will provide an attractive alternative to disposable beverage cups that often used for that purpose. Before painting the repaired part of a vehicle in a repair shop, the repair operator must mix a dose of paint of the required color, which matches the color of the surrounding part of the vehicle. The various components for a dose of paint should be measured accurately, in volume or weight, in a suitable container in which they are thoroughly mixed with each other before being used. If the mixture does not become thorough, or if the receptacle is not absolutely clean, the color / quality of the paint dose (and, consequently, the quality of the repair) may be affected.

To allow the paint mixing to be carried out conveniently, but effectively, an inner liner, of the type illustrated in Figure 19, can be used with a measuring vessel 70, as shown in Figure 23. The container Measuring 70 is in the form of a graduated jug with a mouth 71 in a shaped flange 72 and a handle 73. The graduated jug is provided with marks 74 on the side walls, which allow the volume of the content of the graduated jug to be determined. Using the method already described with reference to Figure 21, inner liners of the type shown in Fig. 19 can be manufactured to precisely fit inside the graduated jar 70 and, using said inner liner, the various components for a dose of Paint can be mounted and mixed with each other in the 70 degree jug without really coming into contact with the latter.

An inner liner 75 suitable for use in the graduated jug 70 is illustrated in Figure 24. The inner lining 75 has a shape corresponding to the inside of the graduated jug 70 and is generally similar to the inner lining 13 illustrated in Figure 19 except that the thicker portion of the flange 14, extending outwardly, of the latter it is omitted and the side walls 76 of the inner liner 75 include a shaped flange 77 corresponding to the flange 72 and the mouth 71 of the graduated jug. Since the inner lining 75 fits exactly inside the graduated jar 70, the possibility of being punctured by the mixing utensil when painting in the graduated jar is being mixed is minimized. In addition, since there are no places within the inner lining where material can be trapped, there is no barrier to the effective mixing of all the material that is measured inside the graduated jar. When the paint has been mixed and transferred from the graduated jug 70 (for example, to the paint can of a spray gun), the inner liner 75, preferably crushed as shown in Figure 20, is removed and discarded, leaving The graduated jug 70 is clean and available for additional use.

Since the base 78 of the inner lining 75 will occupy a certain amount of space in the lower part of the graduated jar 70, the marks 74 on the side walls of the graduated jar may have to be located to take this fact into account. It may also be desirable, depending on the shape of the graduated jar 70,

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arranging an extension in the upper part of the inner lining 75 that can be folded back over the flange 72 of the graduated jug. Alternatively, or in addition, it may be desirable to seal the inner liner 75 to the graduated jar 70 during use, for example by providing some form of shaped element on the inner liner and the graduated jar, so that they can be adjusted by elastic jump with each other. on flanges 77, 72.

Although it is desirable that the inner liner 75 of the graduated jug 70 could be crushed so that it occupies less space after use, this is not absolutely essential. In addition, since the shape of the inner liner 75 is determined by the shape of the interior of the receptacle 70 in which it is to be used, there may be cases where the inner liner is not capable of being straight, unsupported, on the outside of the receptacle.

As an additional alternative, an article of the type shown in Figure 19 can simply be used as a container, in which case it has the advantage that, although the walls 13B are comparable in flexibility to a plastic bag, the container will be straight upright , without support, while it is being filled and also later. The container can be of any appropriate size and can be used to contain many different types of items, including, for example, powders and liquids, or simply as an alternative to the plastic / paper bags that retail merchants provide to customers. . In each case, the container has the advantage that there are no internal places where material can be trapped inside the container. Depending on the contents of the container, it may be desirable to be able to close your mouth, in which case some appropriate form of closure may be provided. The closure may, for example, have the shape of an internal rib on the inside of the container around the middle of the mouth, and a groove coinciding also on the inside of the container around the other half of the mouth, into the which can be pressed the nerve to close the container. The flexibility of the walls 13B of the container further allows the walls to be pressed down around the contents, thereby reducing the empty space inside the container, if required.

After use, when it is required to discard the container, the side walls 13B can be crushed by hand pushing the flange 14 towards the base, so that the container (in this case in the manner illustrated in Figure 20) requires less space for removal As already mentioned, the side walls 13B are crushed similarly to a plastic bag without breaking (for example, by separation, tearing or cracking).

It will be appreciated that there are many different possible uses for items of the type shown in Figure 19. Such an inner liner could be used, for example, simply as an inner liner for a garbage can in which it would have the advantage of being a better fit inside the cube than a usual inner lining in the form of a bag, and if it is easier to handle when it is removed from the cube since it will be straight upright on the base 13A. Similar inner liners could also be used in buckets or other containers for materials that harden relatively quickly (eg glue, wax or plaster): in some cases, a material such as plaster is actually sold together with a mixing bucket, in which case A supply of interior liners could be included in the package. In some circumstances, it may be appropriate to have a plurality of inner liners, stacked inside each other, in position in a receptacle, so that when an inner liner is removed, the next one is already in position. In addition, since the receptacle is intended to contain an inner liner, it is not essential that the walls of the receptacle be solid: the receptacle could, for example, have the shape of a frame to contain the inner liner.

Generally, in an article of the type shown in Figure 19, the base 13A is typically at least 25 µm thick, more typically at least 100 µm thick. The side walls 13B are thin compared to the base 13A, to the point that they can be crushed, as described, to facilitate the removal of the inner liner / container: typically, the thickness of the side walls 13B is less than the half of the thickness of the base 13A and may be less than one fifth of the thickness of the base. Depending on the materials used, and the intended use of the inner liner / container, the side walls 13A will usually be less than 250 µm thick.

For certain uses of an article of the type shown in Figure 19, the flange portion 14 may not be essential and may be omitted (as in the inner lining of Figure 24). If no flange 14 is required, the sheet 60 of Figure 21 (c) would, of course, be cut immediately adjacent to the mouth of the molded portion 65. It has been found that the self-supporting nature of the inner liner / container can be retained even if the flange portion 14 is omitted.

It should also be noted that the base 13A of a container / inner liner of the type shown in Figure 19 does not have to be circular, but could have another shape, for example rectangular or triangular. In the case of an inner liner for a receptacle, that shape may be imposed by the shape of the receptacle, particularly if the inner liner is required to fit within the latter. In some cases, the base does not have to be rigid.

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It will also be appreciated that the procedure illustrated in Figures 21 and 22 is not restricted to the manufacture of interior coatings for use in spray guns paint cans and can be adapted to manufacture interior coatings / containers with other purposes. It will be appreciated that the process requires that the mold 64 have a slightly inclined shape, the largest cross section being at the lower end 5 (as seen in Figures 21 and 22) to allow the sheet 60 to be disassembled when the operation of the training. When the procedure is used to manufacture an inner liner that is required to fit inside a container, this, in turn, requires that the container must be internally inclined in a similar manner. The inner liner / container may be formed from any suitable thermoplastic material capable of forming a thin film that is impermeable to the materials it is intended to contain. In

10 In some cases, it may be desirable to use a material in the form of a laminate. For certain applications, such as food packaging, plastics with low gas permeability may be preferred. For most applications, however, polyolefins such as polyethylene or polypropylene are preferred, since they are relatively inexpensive, can be easily thermoformed and inert to most aqueous and organic fluids.

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