ES2406109T3 - Apparatus for spraying liquids, and disposable containers and liners suitable for use with it - Google Patents

Abstract

Method of preparing a batch of paint, the method comprising: (a) providing a measuring vessel (70) having a lower end, an open upper end, a flange (72) at the open upper end, and markings (74) that allow the volume of the contents of the measuring vessel (70) to be determined; characterized by (b) providing a liner (75) having a base (78), an open end and a flange (77) at its open end corresponding in shape to the flange (72) of the measuring vessel (70) so that a depot batch can be mixed in the measuring vessel (70) without coming into contact with it, where the shape of the liner (75) makes the liner (75) unable to stand, without being supported, outside the measuring vessel (70); and (c) placing the liner (75) inside the measuring vessel (70), whereby the marks (74) of the measuring vessel (75) are positioned so that the space occupied by the base (78) of the liner (75) in the measuring vessel (70), and thus the measuring vessel (70) can be used to prepare a batch of paint.

Description

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

The present invention relates to an apparatus for spraying liquids (for example, spray guns) and, more especially, to a method of preparing a batch of paint and a paint preparation system for preparing a batch of paint.

There are many uses, in many different fields, for disposable containers. For example, many products are packaged in disposable containers (for example, bags) either before or after purchase. When the disposable container is a plastic bag, it will be reused frequently by the buyer as a disposable liner for another receptacle, for example a garbage can. In some cases, disposable liners will

10 specifically produced for use in other reusable receptacles: in those cases, the liner may be intended to aid in the removal of the contents of the receptacle (as in the case of a liner in a garbage can); to protect the receptacle or its contents; or to facilitate, or even eliminate, the cleaning of the receptacle.

The use of a liner in a receptacle in which a glue-like substance is mixed or contained for use

or plaster can be particularly advantageous in terms of facilitating cleaning of the receptacle after use and

15 to prevent substances in the receptacle from becoming contaminated by the remains of other substances (see documents US-A-5 400 916 and 3 157 902). Receptacles in which paints are mixed or contained for use, for example, should be cleaned to ensure that the color or quality of the paint is not altered by traces of other substances: this is particularly important, as explained above. , when a vehicle is being repainted and the paint is required to match an existing one. To avoid contamination problems

20 When mixing paints, it is common practice in vehicle body shops to use disposable waxed 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 provision of a disposable container that, for use, is located in a receptacle similar to a reusable frame.

In the field of spray guns, it has been proposed for various reasons that a liner should be used

25 disposable in the gun tank (see documents US-A-3 211 324, 3 255 972, 4 151 929, 4 951 875, 5 143 294 and 5 248 089, and document EP-A-0 678 334 ). Liquid spray guns (for example, paints, garden chemicals, etc.) are generally well known and typically comprise a reservoir containing a liquid to be dispensed, and a spray nozzle through which it is dispensed the liquid under pressure, under the control of a firing mechanism. The liquid can be fed from the tank by gravity

30 and / or can be carried in a stream of pressurized fluid, for example air or water, which is supplied to the gun from an external source.

When a user wishes to change the liquid in the tank of a spray gun, it is usually necessary to clean the gun very carefully to ensure that no trace of old liquid remains in the gun contaminating the new liquid. This applies particularly to paint spray guns because no trace of an old batch of paint that remains in a gun can affect the color of a new batch of paint to the point that the new batch of paint becomes Useless. This can cause problems especially in vehicle body shops where it is often required that the paint applied to a vehicle exactly matches the existing paint job. Alternatively, if paint residues have been allowed to dry inside the gun, they may flake and contaminate the new batch of paint. 40 However, cleaning spray guns is a comparatively complex and time-consuming operation. In addition, in the case of paint spray guns, the cleaning operation involves the use of comparatively large amounts of solvents which, for environmental reasons, should be handled and disposed of carefully. This, in turn, can substantially increase the cost of a paint operation. It has already been suggested (see, for example, EP-A-0 678 334 mentioned above) that the use of a

A disposable liner in the paint reservoir (ie, the paint can) of a spray gun can simplify the cleaning of the gun and reduce the amount of solvent required.

The present invention provides a method of preparing a batch of paint as defined in claim 1. Preferred features of the method are the subject of subordinate claims 2 to 6.

The present invention also provides a paint preparation system for preparing a batch of paint 50 as defined in claim 7.

The term "vacuum thermoforming / forming" as used herein means a process by which a sheet of material is heated to a softened condition and converted into a required shape, defined by a mold, while in that softened condition. It includes the case in which the application of a differential air pressure is used to help convert the material as required and, in particular, includes the case in

55 which produces a vacuum on one side of the material to help convert it into the required form (also known simply as "vacuum forming").

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

5 The term "paint" is used here to include all forms of paint-like coating materials that can be applied to a surface using a spray gun, regardless of whether they are intended to color the surface. The term includes, for example, primers, base coatings, lacquers and similar materials.

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

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

Figure 2 shows the components of an alternative form of paint deposit not belonging to the invention for the gun of Figure 1, in an exploded condition; 15 Figure 3 shows the paint tank of Figure 2 in a condition assembled with an adapter for connecting the 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 that is attached to a spray gun; Figure 6 shows the paint reservoir of Figure 4 in use in a spray gun;

20 Figure 7 shows components of the paint reservoir of Figure 4 which is removed after use; Figure 8 is similar to Figure 2, but shows a modified form of paint deposit not belonging to the invention;

Figure 9 shows a longitudinal cross section through an alternative form of cover not belonging to the invention 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 not belonging to the invention;

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 paint deposit not belonging to the invention:

Figure 13 shows the gun of Figure 12 with a modified form of paint deposit not belonging to the invention;

Figure 14 illustrates a modification of the gun tank of Figure 13 not belonging to the invention; Figure 15 is a view similar to Figure 3 of an alternative form of paint deposit not belonging to the invention;

Figures 16 and 17 show modified forms of a component of Figure 15 not belonging to the invention; Figure 18 illustrates the use of a support for the paint reservoir of Figure 15 not belonging to the invention; Figure 19 is a perspective view of a liner / container not belonging to the invention; Figure 20 is a similar view but showing the liner / container in the process of collapsing for removal; Figure 21 (a) to (c) is a diagrammatic illustration of a method of producing a liner for the deposits of

40 painting of figures 2 to 4, and 10; Figure 22 illustrates a modification of the method of Figure 21; Figure 23 shows a paint mixing jug according to the invention; and Figure 24 shows a liner according to the invention for use with the jug of Figure 23.

Figure 1 of the drawings illustrates a typical prior art paint spray gun 1 of the gravity feed 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 a trigger 5 which is pivotally mounted on the sides of the gun. The paint tank 5 or paint can 6 containing paint (or similar material) to be discharged by the gun is located in the upper part of the body 2 and communicates with an internal passage (not visible) for compressed air that extends to through the gun from a connector 7 at the lower end of the handle 3 to the nozzle 4. In use, the connector 7 is connected to a source of compressed air (not shown) so that when the user pulls the trigger 5, it supplies compressed air to the nozzle 4 through the gun and it drags and atomizes the paint that is

10 being supplied by gravity from the canister 6. The paint is then discharged as a spray through the nozzle 4 together with the compressed air.

The paint that is contained in the canister 6 is frequently mixed by hand (for which a separate receptacle, for example a jar is required) and poured into the canister. To ensure that there are no unwanted particles in the paint, which would spoil 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 positioned on the open end of the canister. The filter 9 is shown as a known type of disposable conical filter having 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 removed and discarded and the canister lid 8 is replaced. If filter 9 is a reusable filter, then, like the gun, it must be thoroughly cleaned before it is used with

20 a different liquid (for example, a paint of a different color or a liquid having a different chemical composition).

Figure 2 illustrates the components of an alternative form of paint can 11 not belonging to the invention that can be used in the gun 1 of Figure 1 (or any similar gun) instead of the canister 6. The alternative form of the paint can 11 is shown assembled in figure 3 and (in cross section) in figure 4.

25 The paint can 11 comprises an open container 12 comparable in size with a conventional paint can of a manual spray gun, which has an air passage hole 12A at its base and is provided with a disposable liner 13. The liner 13 corresponds in shape to the interior of the container 12 (and fits tightly therein) and has a narrow flange 14 at the open end that sits on the upper edge of the container. The container 12 also has a disposable lid 15 which makes a push adjustment in the

30 open end of the liner 13. The cover 15 has a central opening 16 (Figure 4) from which a connecting tube 17 extends, at its end, with outward extensions 18 forming a part of a bayonet connection. The opening 16 is covered by a filter mesh 19 which can make a push fit in the opening or can be an integral part of the lid 15. The lid 15 is firmly held in place on the container 12 by an annular collar 20 which is screwed into the container, above the lid.

35 The paint can 11 is attached to the spray gun 1 through 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 that, at one end 22, is integrally formed with the other part of the bayonet connection for attachment to the connector tube 17 of the paint can 11. At the other end 23, the adapter is shaped to match the standard hold of the spray gun paint can (typically a

40 screw thread).

The liner 13 of the paint can 11, as already mentioned, corresponds in shape to the interior 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 above, the coating is self-supporting but is also collapsible and preferably has a comparatively rigid base 13A and comparatively thin side walls 13B, so that when

45 collapses, it is in the longitudinal direction by virtue of the collapsing side walls instead of the base. In addition, the lining 13 does not have folds, corrugations, seams, joints or reinforcements, nor does it have any groove in the internal joint of the side walls 13B with the base 13A. Such a liner will be described in greater detail later with reference to Figures 19 and 20. Also, a thermoforming process by which such a liner can be produced is described later.

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 with a capacity of 250, 500 or 800 ml could typically be used, although other sizes could be used if required. The cover 15 is also formed of a plastic material, for example, polyethylene or polypropylene and can be formed by any molding process

55 by injection. The cover can be translucent or opaque and can be colored. The collar 20 may be a molded plastic component or it may be a mechanized metal component (eg, aluminum). The adapter 21 can be a machined metal component and can be formed, for example, of aluminum and anodized.

To use the paint can 11, the adapter 21 is attached (at the end 23) to the spray gun and is

Leave in position. Then, with the paint can 11 disassembled as shown in Figure 2, the liner 13 is pushed into the container 12. Paint is then placed in the container, the lid 15 is pushed into place and the collar is screwed tightly 20 to keep the cover in position. The upper portion of the liner 13 is then trapped between the lid 15 and the container 12 and the liner flange 14 is trapped between the upper edge of the container and the collar 20, as shown in Figure 4. Advantageously, the Cover 15 is formed with beards (not visible) on its surface to attach and secure the upper part of the liner. The spray gun 1 is then reversed from its normal operating position so that the end of the connector tube 17 can be attached to the adapter 21 as illustrated in Figure 5, after which the gun can be returned to its normal position (illustrated in Figure 6) and is prepared to be used in the usual way. When he retires

10 paint inside the liner 13, the sides of the liner collapse as a result of the reduced pressure inside the liner. The base of the liner, which is more rigid, retains its shape so that the liner tends to collapse in the longitudinal direction instead of in the transverse direction, thereby reducing the possibility of paint bags being trapped in the liner.

The user can choose to evacuate the air inside the liner 13 before operating the spray gun 1

15 although not essential. However, the range of angles in which the gun will operate satisfactorily increases since there is no risk of air entering the gun from the paint can 11. To evacuate the air inside the liner 13, the trigger must be operated. 5 of the gun while the gun is still in the position shown in Figure 5.

After use, when the gun needs to be cleaned, the gun can be reinvested and trigger 5 can be operated

20 briefly to allow the paint inside the gun to return to the liner of the canister 11. The canister 11 is then removed from the gun by separating the connector tube 17 from the adapter 21 (which remains in the gun). The collar 20 is removed from the container 12 and then the lid 15 is removed, carrying with it the collapsed liner 13, as shown in Figure 7. The lid (including the filter 19) and the liner are discarded, leaving the container 12 and collar 20 clean and ready for reuse with a new liner and cover. Only the gun itself needs to be cleaned, giving

25 resulted in a substantial reduction in the amount of solvent used. The risk of unused paint spilling from canister 11 is also substantially reduced because the liner 13 is removed and discarded with the lid 15 in place. In addition, because the liner is discarded in a collapsed condition, the amount of space required for the collection of liners used is minimized.

Because the liner 13, as described above, is precisely fitted inside the container 12 and

30 has a smooth internal surface, it is possible to mix paint in the container 12 itself instead of 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. That possibility does not exist when a gravity feed gun with a conventional paint can is used, as shown in 6 in Figure 1, because the latter opens at both ends. The possibility of lining 13 being perforated or being minimized is minimized.

35 damaged by the mixing instrument due, firstly, to the fact that the liner fits exactly inside the container 12 and, secondly, because the self-supporting nature of the liner (described above) means that it is less likely to be dragged inside the bowl during the mixing procedure. 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) that allow the volume of the contents of the container to be determined. The

40 general shape of the container 12 and, in particular, the fact that it is flat and stable when in the orientation shown in Figure 2 makes it particularly suitable for use as a mixing receptacle, as does the fact that be translucent as already described. However, if the container 12 were opaque, it could be formed with grooves in the side walls, through which the liner 13 could be seen to allow the user of the spray gun to evaluate the amount of paint in the canister 11 in any moment.

45 When mixing paint 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. However, the mesh 19 can be omitted if the paint is textured or if it is mixed in a separate receptacle and drained when transferred to the coated container 12 or if the presence of contaminants in the paint is unimportant.

Although the collar 20 of the paint can 11 is described above as an independent tool, it could be combined

50 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 liner 13 to which it could be connected by an articulation joint 26, as illustrated in Figure 8. In that case, there is no need for the lid to fit inside the mouth of the liner to ensure that the lid and the liner will be removed together from the container after use; however, that would still be necessary if the cover were required to remain in place.

55 in the lining after use. Still as another alternative, the collar 20 could be replaced by a band secured around the top of the boat 11 to hold the cover 15 and the liner 13 in place. The band could be secured to canister 11 and, for example, could be formed of rubber or be part of a metal clamp arrangement of the type used to secure the upper parts of the jars and bottles.

If a more positive coupling is required between the cover 15 of Figures 2 to 4 and the liner 13, the cover could make an automatic fastening adjustment with the liner instead of a push adjustment as shown. For example, the liner could be formed with an internal circumferential nerve positioned to engage in a corresponding groove on the adjacent surface of the cover.

Still as an additional alternative, the push-on cover 15 could be replaced by a cover 27

5 having the shape shown in Figure 9. The cover 27 also makes a push fit inside the liner, but is generally conical in shape and at its upper end 28 its shape corresponds to the end of the connector tube 17 of Figures 2 a 4, so that it will be attached to the same adapter 21. The cover 27 has an outwardly extending flange 29 that will sit on top of the liner flange 14, and a shaped portion 29A that will engage the inner surface of the liner. The configuration of the shaped portion 29A allows the cover 27

10 is pushed into the mouth of the liner and also provides a recess 29B in which the edge of the liner can contract, so that the lid is located securely. However, the shape of the configured portion illustrated in Figure 9 is not essential and alternatives could be used including, for example, beards as described above with reference to the cover 15 of Figure 4. The cover 27 is held in place. in the container by a screwed collar, similar to collar 20, which will sit on top of the flange 29 of the

15 cover. 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 connection Bayonet In that case, the internal conformation of the tubular part of the lid must ensure that the filter remains in position when the spray gun is in use.

20 The components of an alternative form of paint can 30 not belonging to the invention are illustrated in Figure 10. The canister 30, like the canister 11 of Figure 2, comprises a container 12 and a liner 13. However, in this case, the canister 19 of the canister 11 is formed as an independent tool 31 having a diameter corresponding to the of the container 12 and which includes a circumferential seal gasket 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 makes an adjustment of

25 screwed onto 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 attached to the same adapter 21. The canister 30 is assembled by pushing the liner 13 inside the container 12 and then after the paint has been placed in the container, placing the filter 31 on top of the container and securing it in position by screwing the lid 33. The flange 14 of the liner 13 and the sealing gasket 32 of the filter 31 are both trapped then between

30 the lid 33 and the container 12 as illustrated in Figure 11, thus preventing paint leakage from the canister 30 at this location 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 covers of the containers 11, 30 with screw threads so that they can fit directly into the standard paint can holder on the spray gun 1.

35 Figure 12 illustrates an alternative spray gun not belonging to the invention in which the standard paint can 6 is retained from the spray gun 1 (see Figure 1) and is provided with a liner 35 that fits inside the can and, preferably, extends in the connection with the gun body 2 to form a liquid-tight seal with the latter, for example by the use of a flexible (not visible) O-ring between the gun and the liner . In this case, the liner 35 does not collapse when the paint is removed from inside the can and can

40 formed of a more rigid material to help position it inside the boat 6. Once in position, the liner 35 is held in place by the cover 8 which is screwed into a flange 36 extending outwardly at the end lining open. The canister 6 of Fig. 12 is additionally provided with a filter 37 which is generally conical in shape and completely formed of mesh material and which, in use, is positioned inside the liner 35. The filter 37, like the liner 35, has a flange 38 extending outwardly that is

45 above the flange 36 of the liner and is also held in place by the lid 8 of the canister 6.

The canister 6 of figure 12, unlike canister 11 of figure 3, is intended to be filled with paint while it is attached to the spray gun 1. The liner 35 and the filter 37 are placed in position, the paint is poured to the boat and the lid fits. During this operation, there is no risk of the filter shifting and, because the filter is completely formed of mesh material, the user is always able to see the level of paint while the paint is being poured into the can . The gun 1 is then ready for use. All the paint dispensed by the gun passes through the filter 37 and, consequently, there is no need for the paint to seep when it is being poured into the canister 6. After use, the unscrewed cap 8 must allow them to be removed. the filter 37 and the liner 35. The liner 35 is discarded and the filter 37 is also discarded or cleaned, depending on whether or not it is disposable. The use of the liner 35 again reduces the amount of solvent required to clean the gun 1, being possible a

55 additional reduction by 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 illustrated in Figure 13, the liner 35 and the filter 37 combine to form a single

unit 39. In this case, the filter with the liner is discarded.

In each of the arrangements shown in Figures 12 and 13, the 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 conventional lid 8 of the canister 6 with a disposable lid, of so that cover 8, liner 35 and filter 37 can be discarded together.

The disposable unit 39 of Figure 13 could be modified so that it would replace the paint can 6 of the spray gun 1 instead of fitting into 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. However, because it is sealed, the outlet end 51 of the cartridge must be punctured and a vent is provided, for example at the other end 52 of the cartridge, to allow paint to flow into the gun. The outlet end 51 of the cartridge 50 could be pierced, for example, by the user before the cartridge (with the top of the outlet end) is attached to the gun (inverted). Alternatively, the gun 1 could be modified so that the outlet end 51 is automatically pierced when the cartridge 50 is attached to the gun. A vent at the other end 52 of the cartridge 50 could then be formed after the cartridge has been attached to the gun by punching that end of the cartridge manually or, for example, by holding a separate cover 53 that is designed to pierce the cartridge when it is placed in position. Alternatively, a vent could be formed in the cartridge that simply needs to be opened when the gun is ready for use.

After use, the cartridge 50 is removed from the gun and discarded. Because the cartridge 50 contains a filter, it is not necessary for the supplier to filter the paint before it is loaded into the cartridge. However, if the paint is previously filtered, then the filter in the cartridge 50 can be omitted.

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

The container 41 of Figure 15 can be any conventional 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, of 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 volume of the content to be determined of the container. An air passage hole 44 is formed in the base of the container, together with some means to close the air passage hole when desired. These means can take the form of a strip of adhesive tape (not shown) that is detached to open the hole 44 and can be reattached to close the hole when required. Alternatively, a flip closure or some simple manually operated valve mechanism can be provided. The container 41 has an external screw thread at its open end, for securing the lid 42 which is generally similar to the lid 33 of Figure 10 and is configured equally, at its upper end 42A, for attachment to a gun spray (if necessary by means of a suitable adapter). The lid 42 may be formed of 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 can be an independent tool, be secured at its periphery between the lid 42 and the container 41 or it can be formed integrally With the cover.

To use the canister 40, the cover 42 and the filter mesh 45 are removed from the container 41 which is then filled with paint (taking care that the air passage hole 44 in the base of the container is closed). It is unnecessary to drain the paint when it is placed in the container 41 and, as described above, it is possible to mix the paint in the container, thus avoiding the need for a separate receptacle for that purpose. The cover 42 and the mesh 45 are put back into position in the container 41, the cover 42 is fastened to the spray gun (inverted) 1 which then returns to its normal position, and the air passage hole 44 is opened at the base of the container. Spray gun 1 can now be used as usual. At the end of the spraying operation, the air passage 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 reinvested and the trigger 5 of the gun can be operated to allow excess paint remaining in the gun to return to the canister. In any case, if enough paint remains in the canister 40, the canister could be resealed (rather than discarded) and used again.

Advantageously, the container 41 of the canister is formed so that it can collapse after use. In some cases, it may be possible that the cover 42 is also collapsible.

Alternatively, cover 42 could be a reusable component and would be cleaned 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 the container is attached to the lid 42. The filter mesh 45 could be a disposable or reusable component. As an additional alternative, the container 41 and the lid 42 could be supplied together as a cartridge sealed by a removable cover, at the upper end 42A of the lid, which would be removed before the cartridge is attached to the gun. In that way, the cartridge is similar to the cartridge 50 of Figure 14.

Thanks to an appropriate selection of the dimensions of the cover 42 of the paint can 40, it is possible that

5 use a 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 that a range of filters 45 with different mesh sizes be provided so that the user can select the mesh size that best suits the type of paint being used. It is not essential that the filter mesh 45 have the shape and / or location shown in Figure 15; it could have, for example, a conical shape like the one shown in the

10 figure 16 and / or could be located at the outlet of the cover 42, as shown in figure 17. Alternatively, the filter 45 can be omitted if the paint is filtered before it is placed in the container 41 or if the presence of Paint contaminants is not important.

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

15 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 that the paint / coating material be contained within a sealed collapsible liner inside the cartridge That may be desirable, for example, if it is necessary that the paint / coating material be kept isolated, for example, from air or light, until it has been sprayed onto the surface to be coated. The air passage hole 44 in the container 41 can

20 then remain open all the time or can be omitted if the container 41 itself is not air tight.

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 does not tip over. A suitable support 50 shown in Figure 18 comprises a container portion 51 that is similar to the container 41, but slightly larger than this, and is provided with an enlarged base 52. The container 41 is placed in the container portion 51 to ensure that it remains

25 erect while it is being filled and / or attached 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 ducts air) to spray substances such as garden chemicals. The description also applies to suction feed guns, that is, guns in which the liquid outlet of the reservoir is located at the top of the reservoir when the gun is in use and liquid is drawn from the reservoir through a tube supply by the action of compressed air or other pressurized fluid flowing through the gun. In that case, when a liner for the deposit is provided, the construction of the liner and / or the supply tube should be such that the liner can collapse without blocking the supply tube. For example, a short supply tube can be used as long as all the air escapes from the liner 35 before the gun is used. Alternatively, a flexible supply tube could be used that will collapse with the liner. As an additional alternative, a modified liner that does not have a rigid base could be used, so that the liner collapses in a different way from that of liner 13 in Figure 2. Since the reservoir of a suction feed gun is not It reverses during use, as in a gravity feed gun, it is possible to omit the air passage hole in the tank, provided that the connection between the tank and the gun allows

40 that the air enters the space between the reservoir and the liner.

Returning now to the paint can 11 of Figure 2, the liner 13 will now be described in greater detail, together with a method with which it can be produced. The liner 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 shape of the liner is dictated by the internal shape of the container 12. The comparatively rigid base 45 13A is circular and the liner 13, like the inside of the container 12, is generally cylindrical but narrows inward slightly from the mouth towards the base 13A . The flange portion 14, like the base, is also comparatively rigid but the side walls 13B are flexible and, as already described, can be made to collapse. However, the liner 13 is able to stand, without being supported, on the base 13A with the side walls 13B extended and upright as shown in Figure 19. When the liner 13 collapses, the

50 comparatively rigid base 13A retains its shape, but moves towards the flange portion 14 of the liner as a result of the collapse of the side walls 13B, as illustrated in Figure 20. The side walls 13B collapse in a manner similar to a plastic bag without breaking (for example, by breakage, tearing or cracking).

In one form, the liner has a height of about 110 mm, a diameter at its base 13A of about 78 mm

55 and a diameter in its mouth (excluding the flange portion 14) of about 86 mm. The base has a thickness of about 400 μm, the flange portion 14 has a thickness of about 900 μm and the side walls 13B have a thickness of about 150 μm. In another form, the liner has the same height and the same diameters as its base and mouth, but the base has a thickness of about 300 μm, the flange portion has a thickness of about 200 μm and the side walls 13B they have a thickness in the range of 50 to 250 μm.

A method of producing a liner as shown in Figure 19 will now be described with reference to Figure 21 (a) (c).

A sheet 60 of low density polyethylene (LDPE), approximately 250 x 225 mm and 0.5 mm thick, is

5 clamped on its periphery in the molding frame 61 of a vacuum forming machine. The LDPE material is commercially available, for example, by Plastech Extrusions Ltd. of Widnes, Cheshire, England, and the vacuum forming machine used was the "FLB 725" model of C.R. Clarke and Company Limited of Ammanford, Carmarthenshire, Wales. However, it will be appreciated that any suitable plastic material could be used and that the method could be carried out using any thermoforming / forming machine in

10 empty.

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

15 transparent.

The heater bank 62 was then removed and the mold plate 63 was moved upwardly from beneath the sheet 60, bringing the mold 64 into contact with the sheet to deform the latter in an upward direction. At this time, the machine's vacuum pump was connected to remove air from below the sheet 60. The upward movement of the mold plate 63 continued until the plate reached the top of its

20 stroke, when 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 mold plate sealed against the frame 61 and the pressure difference created between the upper and lower sides of the sheet 60 caused the latter (which was already in contact with the upper part of the mold 64) move down in contact with the sides of the mold (figure 21 25 (c)). The mold plate 63 then moved beyond the cooled sheet 60, leaving a molded portion 65 with the desired shape of the liner 13 and without any crease, corrugation, seam, joint or reinforcement, or any groove in the internal junction of the side walls 13B with base 13A. After removal of the frame 61, the sheet 60 was cut around the mouth of the molded portion 65 to form the flange 14 of the liner 13. The width of the flange 14 is determined by the location at which the sheet 60 is trimmed in this stage and can be adjusted according

30 is required.

The procedure described above was found to produce a molded portion 65 (and, therefore, a liner 13) in which that part of the plastic sheet 60 that was in contact with the sides of the mold 64 during the forming process was substantially thinner than the part that was in contact with the upper part of the mold. The process differs from a conventional vacuum forming procedure that would aim to eliminate, to the extent possible, any difference in thickness in the molded portion 65 and, to that end, would include the additional step of applying air pressure to the bottom of the heated sheet 60, after step (a) of Figure 21, to make the sheet adopt a dome shape before the mold plate 63 is sealed against the frame 61: the thickness of the sheet would then be comparatively uniform when moving in contact with the mold 64 in the step (c) of Figure 21. In general, in the procedure illustrated in Figure 21,

40 for a given size of the sheet 60, it has been found that the size of the mold 64 affects the thickness of the sides of the resulting liner 13 more than the base. In other words, if the size of the mold 64 is increased, the thickness of the base of the resulting liner 13 will be approximately the same, but the sides of the liner will be much thinner. On the other hand, if the mold size is reduced, it can be found that a point is reached where longitudinal folds appear on the sides of the liner 13.

45 If a further reduction of the thickness of the sheet 60 is required at the place where it contacts the sides of the mold 64 in the passage (c) of Figure 21, the sheet 60 can be located between two thin metal plates 66 (Figure 22) when it is held in the frame 61 of the forming machine, each metal plate 66 having a hole 67 in the location of the mold 64 and larger than the largest cross-section of the mold. The plates 66 are also held in the frame 61 and the procedure of Figure 21 is repeated. The effect of the

50 plates 66 is that only the central portion of the sheet 60 is directly exposed to the heaters 62 and is shed in the mold 64 when the latter has moved up (in this case, through the holes 67 of the plates 66 ). In this way, less amount of sheet 60 is used in the formation of molded portion 65 and the resulting liner 13 will have a slightly thinner base 13A and flange 14 and substantially thinner side walls 13B. It is also possible to obtain a comparable result using only the top plate

55 66 shown in Figure 22.

As a modification of the procedure illustrated in Figure 22, the plastic sheet 60 can be in the form of a circular disk of material that is held at its periphery between the two plates 66. Depending on the size of the

disc, the attached periphery can then form the flange 14 of the liner 13 and there may not be any excess material to be cut.

It has been found that the liner 13 produced by a process as described with reference to Figures 21 and 22 will collapse as described with reference to Figure 20 when used in the reservoir 11 of the spray gun of Figure 2. The liner 13 can also be collapsed by hand by pushing the base 13A of the liner toward the flange 14. It has been found that the liner is typically capable of standing without being supported on its base 13A and this feature, although not essential for use of the liner in the tank 11 of the spray gun, it can be useful for storage purposes. The liner has no crease, corrugation, seam, joint or reinforcement and no groove in the internal junction of the side walls 13B with the base 13A; consequently, there is no internal place where the material can be trapped inside the liner. The base 13A of the liner will, of course, occupy some space in the base of the container 12 of the spray gun tank 11 and the marks on the wall of the container 12 need to be positioned to take this fact into account.

Although the liner 13 of Figure 19 has been described for use specifically in the paint can 11 of Figure 2, the same article or a similar article can be used in other ways (subject, if necessary, to appropriate dimensional changes). For example, an article of the type illustrated in Figure 19 can also be used as a liner in many different receptacle shapes of a spray gun reservoir. Frequently, it is desirable to provide a receptacle with a disposable liner, for example to keep the receptacle clean, facilitate cleaning or protect the receptacle or its contents. A liner of the type illustrated in Figure 19 can be used for any of those purposes and is especially useful in receptacles in which substances are mixed together because there is no place inside the liner where material can be trapped and remain Unmixed.

An article of the type illustrated in Figure 19 can be used, for example, as a liner in a receptacle intended to mix paint in a vehicle body shop, in which case it will provide an attractive alternative to the disposable beverage cups that are employed. frequently for that purpose. Before painting the repaired portion of a vehicle in a body shop, the repairman must mix a lot of paint of the required color that matches the color of the surrounding portion of the vehicle. The various components of a batch of paint should be accurately measured, either by volume or by weight, in a suitable receptacle in which they are carefully mixed with each other before use. If mixing is less than careful or if the receptacle is not absolutely clean, the color / quality of the paint lot (and, consequently, the quality of repair) may be affected.

To allow for convenient, but effective mixing of paint, a liner of the type illustrated in Figure 19 can be used with a measuring vessel 70 according to the invention, as shown in Figure 23. The measuring vessel 70 It is jug-shaped with a spout 71 in a shaped flange 72 and a handle

73. The jug is provided with marks 74 on the side walls, allowing the volume of the contents of the jug to be determined. Using the method already described with reference to Figure 21, liners of the type shown in Fig. 19 can be produced to precisely fit inside the jar 70 and, using such a liner, the various components of a batch of paint can be assembled and Mix together in the jar 70 without really coming into contact with the latter.

A liner 75 suitable for use in the jar 70 is illustrated in Figure 24. The liner 75 has a shape corresponding to the inside of the jar 70 and is generally similar to the liner 13 illustrated in Figure 19 except that the portion 14 of thicker flange extending outward from the latter and the side walls 76 of the liner 75 include a shaped flange 77 corresponding to the flange 72 and the pouring spout 71 of the jug. Because the liner 75 fits exactly inside the jar 70, the possibility that it will be pierced by the mixing instrument when the paint is mixing in the jar is minimized. In addition, because there is no place inside the liner where the material can become trapped, there is no barrier to the effective mixing of all the material measured in the jar. When the paint has been mixed and transferred from the jug 70 (for example, to the spray can of paint), the liner 75 is removed, preferably collapsed as shown in Figure 20, and discarded, leaving the jar 70 clean and ready for another use.

Because the base 78 of the liner 75 will occupy some space in the bottom of the jar 70, the marks 74 on the side walls of the jar are positioned to account for that fact. It may also be desirable, depending on the shape of the jug 70, to provide an extension at the top of the liner 75 that can be folded over the flange 72 of the jug. Alternatively or in addition, it may be desirable to seal the liner 75 against the jug 70 during use, for example by providing some form of conformation in the liner and the jug so that they can automatically fasten with one another on the flanges 77, 72.

Although it is desirable that the liner 75 of the jug 70 should be collapsible so that it occupies less space after use, this is not absolutely essential. In addition, since the shape of the liner 75 is determined by the shape of the interior of the receptacle 70 in which it is to be used, the liner is not able to stand, without being

supported, outside the receptacle.

As an additional alternative not belonging to the invention, 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 with a plastic bag, the container it will remain upright, without support, while it is being filled and also after. The container can be of any appropriate size and can be used to contain many different types of objects, including, for example, powders and liquids or simply as an alternative to plastic / paper bags provided to customers by retailers. In each case, the container has the advantage that there is no internal place where material can be trapped inside the container. Depending on the contents of the container, it may be desirable to be able to close the mouth of the container, in which case

10 some appropriate form of closure can be provided. The closure can take the form, for example, of an internal nerve inside the container about one half of the mouth and a conjugate groove also inside the container about the other half of the mouth into which the nerve to close the container. The flexibility of the walls 13B of the container additionally allows the walls to be pressed around the contents, thus reducing the air space inside the container, if required.

15 After use, when it is required to discard the container, the side walls 13B can be collapsed manually by pushing the flange 14 towards the base so that the container (now in the form illustrated in Figure 20) requires less space for removal. As already mentioned, the side walls 13B collapse in a manner similar to a plastic bag without breaking (for example, by breakage, tearing or cracking).

20 It will be appreciated that there are many other possible uses for articles of the type shown in Figure 19. Such a liner could be used, for example, simply as a garbage bin liner where it would offer the advantage of having a better fit inside. of the bucket than a conventional bag-shaped liner and of being easier to handle when removed from the bucket because it will remain upright on the base 13A. Similar linings could be used in cauldrons or other containers for materials that harden relatively quickly (e.g. glue,

25 wax or plaster): in some cases, material such as plaster is actually sold with a mixing cauldron, in which case a supply of liners could be included in the package. In some circumstances, it may be appropriate to have a plurality of liners, stacked inside each other, in position within a receptacle, so that when a liner is removed, the next one is already in position. Furthermore, since the receptacle is intended to contain a liner, it is not essential that the receptacle walls be solid; the receptacle could have, for example, the

30 shape of a frame to contain the lining.

In general, 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 extent that they can collapse as described to facilitate removal of the liner / container; typically, the thickness of the side walls 13B is less than half the thickness of the base

35 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 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 liner of Figure 24). If no flange 14 is required, the sheet 60 of Figure 21 (c), of course, would be cut immediately next to the mouth of the molded portion 65. It has been found that it can

40 retain the self-supporting nature of the liner / container even if the flange portion 14 is omitted.

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

45 It will also be appreciated that the procedure illustrated in Figures 21 and 22 is not restricted to the production of liners for use in the paint cans of the spray guns and can be adapted to produce liners / containers for other purposes. It will be appreciated that the process requires that the mold 64 have a slightly narrowed shape, the major cross section being at the lower end (as seen in Figures 21 and 22) to allow the sheet 60 to be removed when the forming operation is complete. When the procedure is

50 used to produce a liner that is required to fit inside a container, that, in turn, requires that the container should be internally narrowed similarly. The 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 some cases, it may be desirable to use a material in the form of a laminate. For certain applications such as food packaging, plastic with

55 low gas permeability. However, for most applications, polyolefins such as polyethylene or polypropylene are preferred, since these are relatively inexpensive, easily thermoformable and inert to most aqueous and organic fluids.

Claims (7)

1. Method of preparing a batch of paint, comprising the method:

(to)

providing a measuring vessel (70) having a lower end, an open upper end, a flange (72) at the open upper end, and markings (74) that allow the volume of the measuring vessel contents to be determined ( 70);

characterized by

(b)

providing a liner (75) having a base (78), an open end and a flange (77) at its open end corresponding in shape to the flange (72) of the measuring vessel (70) so that a batch of paint can be mixed in the measuring vessel (70) without coming into contact with it, where the shape of the liner (75) makes the liner (75) unable to stand, without being supported, outside the vessel measurement (70); Y

(C)

place the liner (75) inside the measuring vessel (70), bringing the marks (74) of the measuring vessel

(75) are positioned so that the space occupied by the base (78) of the liner (75) in the measuring vessel (70) is taken into account, and thus the measuring vessel (70) can be used to prepare a batch Of paint.

2.

 Method according to claim 1, in which there are no places within the liner (75) in which material can be trapped.

3.

 Method according to claim 1 or claim 2, wherein the liner (75) is removable and can be discarded after use.

Four.

 Method according to any preceding claim, in which the liner (75) can be collapsed.

5.

Method according to any preceding claim, wherein the liner (75) can be folded over the flange (72) of the measuring vessel (70).

6.

 Method according to any preceding claim, wherein the liner (75) is sealed to the measuring vessel (70) during use.

7.

 Paint preparation system to prepare a batch of paint, including the system:

(to)

a measuring vessel (70) having a lower end, an open upper end, a flange (72) at the open upper end, and markings (74) that allow the volume of the measuring vessel contents (70) to be determined ;

characterized by

(b)

a liner (75) adapted to be placed inside the measuring vessel (70), the liner (75) having a base (78), an open end and a flange (77) at its open end corresponding in shape to the flange ( 72) of the measuring vessel (70) so that a batch of paint can be mixed in the measuring vessel (70) without coming into contact with it, where the shape of the liner (75) makes it unable to hold standing without being supported outside the measuring vessel (70); and where

(C)

the marks (74) of the measuring vessel (70) take into account the space occupied by the base of the liner (75) in the measuring vessel (70), whereby the measuring vessel (70) can be used to prepare A lot of paint.