EP0429951B1 - Cleaning method for paint containers of synthetic material for multiple use as well as a pileable bucket - Google Patents

Abstract

The invention relates to a method for cleaning reusable containers containing paint residues. In this method, the paint residues contained in the containers are subjected to a drying treatment, in particular a microwave treatment. Subsequently, a cold treatment takes place. The paint residues which are dried by the drying treatment and made brittle by the cold treatment are largely released from the container by mechanical deformation of the containers and removed from the container. Subsequently, a wet cleaning of the containers takes place. Finally the containers are dried. <IMAGE>

Description

The following relates to a method for cleaning reusable plastic containers for paints and a stackable bucket to which the method can be applied.

Because of the ever increasing amount of rubbish, great efforts are being made to keep the packaging material of consumer goods as small as possible in various ways and to make it environmentally friendly in its way. For example, attempts have recently been made to replace the plastic buckets used today for packaging paints with cardboard buckets. However, such containers, which are more environmentally friendly than plastic containers because of the cardboard used, have not been successful in practice. In addition, they are sent to the garbage after emptying. Since there are regular paint residues in such buckets that can contain solvents, the effect of the more environmentally friendly material of the cardboard is at least partly reduced by the less environmentally compatible color residues. In order to remove color residues from containers, it is known to embrittle the color residues in the container by inflating a refrigerant, in particular liquid nitrogen, so that they either flake off by themselves from the walls of the container or can be easily removed by mechanical means, for example a hammer and chisel (DE-A1-25 39 499; DE-A1-37 33 891; DE-A1-32 12 171). It is also known to remove the color residues in a container by spraying on a solvent from the container wall (EP-A1-0 261 469).

From GB-A-2 028 257 a stackable bucket is known which has a bucket wall which opens slightly conically from the bottom of the bucket to the edge of the lid and opposite ribs which are formed on the bucket wall and run parallel to the bucket axis for fastening a pivotable carrying handle.

The invention has for its object to provide a method for cleaning reusable plastic containers for paints, which leads to a lower environmental impact than the previously conventional method with containers that can only be used once, and to provide a stackable bucket to which the method can be advantageously used .

• a) Die Farbrückstände im Behälter werden einer thermischen Trocknungsbehandlung unterworfen.
• b) Unmittelbar an die Trocknungsbehandlung schließt sich eine Kältebehandlung an.
• c) Die durch die Kältebehandlung versprödeten Farbrückstände werden durch mechanische Verformung der Behälter weitgehend vom Behälter gelöst und aus dem Behälter entfernt.
• d) Die weitgehend von Farbrückständen gereinigten Behälter werden unter Verwendung von Wasser nachgereinigt.
• e) Nach der Naßreinigung werden die Behälter getrocknet.

The invention thus relates to a method for cleaning empty containers containing paint residues, in particular buckets, made of elastic, heat and cold-stable plastic, which is characterized by the following process steps:

• a) The color residues in the container are subjected to a thermal drying treatment.
• b) A cold treatment follows immediately after the drying treatment.
• c) The color residues embrittled by the cold treatment are largely detached from the container by mechanical deformation of the container and removed from the container.
• d) The containers largely cleaned of paint residues are cleaned using water.
• e) After the wet cleaning, the containers are dried.

The use of elastic plastic containers, which should also have a certain heat and cold stability, makes it possible to remove the color residues in the containers in an environmentally friendly manner, because no environmentally harmful alkalis or the like are used for the drying and cold treatment, such as it is required for other reusable containers, for example bottles for drinks. In addition, the color residues resulting from this cleaning are dry and can therefore be ground according to an embodiment of the invention and used again in the manufacture of paints. Since only minimal color residues are removed during the subsequent cleaning with water, the water is hardly contaminated by these color residues, so that it can be used for a large number of containers until it is saturated to such an extent that it is no longer usable.

According to a further embodiment of the invention, prior to the thermal drying treatment, the containers are inspected and sorted according to recyclable and non-recyclable containers, only the recyclable containers being fed to the cleaning process. This configuration is based on economic considerations. However, if the economic considerations are to take a back seat to the ecological considerations, the non-recyclable containers can be cleaned in the same way. These cleaned, non-recyclable containers can then be granulated and used for the production of new plastic products like other containers that were not recognized as non-recyclable during the initial inspection, but only recognized as non-recyclable during the final inspection.

Microwave treatment has proven particularly effective for thermal drying treatment proven. In this way it is prevented that a skin is formed on the color residues which prevents the moisture from escaping from the color residues. Another advantage is that the plastic is not heat loaded by the microwave. The plastic therefore only needs to have low heat stability. Otherwise, the skilled worker is familiar with the means with which he makes plastic heat and cold stable. More important for the quality of the reusable container than its certain heat and cold stability is its UV stability, so that it does not become brittle over time and break during mechanical deformation. It should also contain a lubricant, such as talc, so that the paint residues can be easily removed from its surface.

The cold treatment of the embrittled paint residues is preferably carried out by blowing up a refrigerant, in particular liquid nitrogen.

The containers should be cleaned with water under high pressure and / or with brushes, because in this way even the smallest residues can be removed from the container very quickly. Hydroxyethyl cellulose should be added to the cleaning agent, the concentration of which should be 0.05 ppm to 10 ppm, preferably 0.1 ppm.

Since the color residues often contain organic components, such as glue, care must be taken to ensure that the container intended for refilling is sterile so that bacteria remaining in the container after cleaning do not render the newly filled color unusable. It is therefore provided according to a further embodiment of the invention that disinfection takes place after the containers have dried.

The device-related aspect of the object on which the invention is based is achieved by a stackable bucket which consists of an elastically deformable material and a bucket wall which is weakly conically opening from the bottom of the bucket to the edge of the lid, with molded ribs on the outside of the bucket wall, which are provided in the area of the lid edge Recess and which have a support foot with a notch in their lower area, wherein when stacking the recess of the one bucket is engaged with the notch in the support foot of the bucket above it, and in addition the ribs are slit longitudinally and undercut, so that they are a snap lock for form the facing ends of the handle.

On the one hand, such a bucket is easy to manufacture in terms of production technology, since the ribs can be produced in one piece with the rest of the bucket housing. In addition, the design of the ribs has the advantage that the carrying handle ends can be simply pushed in for transporting the filled buckets and can be locked by axial pulling, and on the other hand, loosening the carrying handle ends is easily possible by a blow to the carrying handle before carrying out the method according to the invention. In addition, the cutouts or notches in the ribs increase the manageability of the buckets, since, due to the wide contact surface of the notches in the cutouts in the edge of the lid, the buckets to be stacked one above the other can be easily assigned.

The fact that the notch is trapezoidal has a self-centering effect when stacking the buckets.

The invention is explained in more detail below with reference to a drawing.

Fig. 1

einen Schnitt durch einen für die Druchführung des erfindungsgemäßen Verfahrens geeigneten Eimer,

Fig. 2

einen Schnitt entland der Linie AA in Fig. 1,

Fig. 3

ein Detail einer Ansicht des in Fig. 1 dargestellten Eimers und

Fig. 4

den Prozeßablauf des erfindungsgemäßen Verfahrens.

Show:

Fig. 1

2 shows a section through a bucket suitable for carrying out the method according to the invention,

Fig. 2

a section along the line AA in Fig. 1,

Fig. 3

a detail of a view of the bucket shown in Fig. 1 and

Fig. 4

the process flow of the method according to the invention.

To carry out the method according to the invention, containers, in particular buckets, made of elastic plastic are used, which have a certain heat and cold stability. A lubricant should be added to the plastic material, which ensures that the adhesion to its surface is as low as possible. If the container is a bucket, it is advisable to provide a carrying strap as a disposable item as the carrying means, which can be easily attached to and detached from suitable fastening elements on the container. The container including its fasteners should be made entirely of plastic.

Referring to Fig. 1, a stackable bucket is shown, which consists of a bucket bottom 1 and a lid edge 3a, between which the bucket wall 2 increases conically to the lid edge 3a.

The inclination of the bucket wall 2 with respect to the vertical is 3 degrees in this exemplary embodiment.

Furthermore, a fastening means 5 is provided on the outer wall 2 of the bucket, into which one end of a carrying handle 4 intervenes for the bucket.

The fastener for the other end of the handle 4 is located on the opposite side, not shown, of the bucket. Formed in one piece on the fastening means 5 for the end of the carrying handle 4 is a rib 6, one half of which is shown in FIG. 1, and which extends along the longitudinal axis of the bucket from the edge of the lid. The lower end of the rib 6 is formed by a support foot 7. The edge of the lid 3b of another bucket is shown in dashed lines in FIG. 1 and forms a stack with the bucket described. The distance between the lid edges 3a, 3b in the bucket stack is determined by the length of the rib 6, the support foot 7 of the rib 6 of the upper bucket being supported on the lid edge 3b of the lower bucket.

As shown in FIGS. 2 and 3, by supporting the support foot 7a of the upper bucket on the lid edge 3b of the lower bucket, an annular-gap-shaped air space with the thickness d is formed between the bucket walls 2a, 2b of the two buckets.

The rib 6a or 6b shown in detail in FIG. 3 has a longitudinal slot which opens in the direction of the respective bucket bottom. In the direction of the edge of the lid, the longitudinal slot opens into a snap lock 5a, 5b. The rib 6, 6b is undercut in the area of the snap closure 5a, 5b.

As shown in the section in FIG. 2, the rib 6a, 6b has a trapezoidal notch 7a, 7b in the lower region of the support foot, while the rib 6a, 6b is provided with a recess 8a, 8b in the upper region. The recess 8b of the upper bucket is in engagement with the trapezoidal notch 7a of the upper bucket.

When the buckets are stacked, they are placed on top of one another before the residual paint is removed so that the ribs are in each case in an alignment line and the trapezoidal notches 7a of the upper bucket engage with the cutout 8b in the lid edge 3b of the lower bucket. Due to the conicity of the bucket walls, a narrow, annular-gap-shaped air space is formed, through which the air can reach the residual paint on the bottom 1a, 1b of the respective bucket and the paint that is still on the bottom of the bucket dries faster.

The handle 4 of the respective bucket can either remain on the bucket without the handles of the individual buckets hindering each other, or can be removed in a simple manner before stacking the buckets by the ends of the handle by a light punch on the handle of the Carrier bracket can be released from their fasteners against the holding force of the snap lock and then the temple ends can be pushed out of the longitudinally slotted area of the ribs.

Because the ribs are undercut in the area of the snap closure 5a, 5b, it is also possible to use brackets which are spherically reinforced in the area of their mutually facing ends. The spherical reinforcements lie between the rib and the bucket wall with little play, so that lateral displacement of the handle is largely prevented.

4, the containers intended for cleaning are first subjected to an inspection. The carrying straps and any labels stuck on are removed from the container by hand. As tear-resistant labels should be attached as possible, which can then be attached to a Have the handle removed from the container. During the inspection, the containers are sorted according to non-reusable and reusable containers. The non-recyclable containers are removed from the process. The recyclable containers are sorted by color. The containers of one color are fed to the further process, while the containers of the other colors are first fed to a waiting station.

The further treated containers are then subjected to a thermal treatment, firstly a heat treatment, in particular using a microwave. The moisture contained in the color residues is expelled. During the subsequent cold treatment, in particular with inflated liquid nitrogen, the color residues become brittle. This can lead to the removal of color residues from the container. In any case, the color residues are removed from the container during the subsequent mechanical treatment. During the mechanical treatment, the elastic container is deformed (tumbled) so that the brittle color residues separate from the wall of the container. The color residues that have been loosened and removed from the container are removed from the process. They can be ground and used in the manufacture of paints.

The cleaned containers are then subjected to wet cleaning. With water under high pressure and / or brushes, any color residues remaining in the container are removed from the container. Hydroxyethyl cellulose is added to the cleaning agent at a concentration of 0.05 to 10 ppm. Since there are only slight color residues, the contamination of the water by the color residues is low, so that the water remains usable for a long time. It can also be reprocessed by filtering out the color residues from the water. The Filtered-out color residues can be dried, especially with a microwave, and recycled.

The containers are preferably disinfected with a disinfectant or by irradiation, preferably immediately after wet cleaning, in order to make them bacteria-free on the inside. The cleaned and disinfected containers are then dried, for example by blowing hot air. However, the reverse order is also conceivable.

At the end of the process, the containers are inspected again. Unusable containers are sorted out while the usable containers are being refilled. The unusable containers can be granulated. The granulate can then be used in the production of new containers or other plastic products.

Claims (11)

1. A method of cleaning emptied containers, more particularly buckets, made of resilient plastics stable under heat and cold and containing paint residues, having the following method steps:

   a) the paint residues in the container are subjected to a thermal drying treatment;

   b) the drying treatment is immediately followed by a refrigerating treatment;

   c) paint residues embrittled by the refrigerating treatments are substantially released from the container by the mechanical deformation thereof and removed from the container;

   d) the containers are substantially cleaned as paint residues are after-cleaned, using water;

   e) after wet cleaning the containers are dried.
2. A method according to claim 1, characterized in that prior to the thermal drying treatment the containers are sorted into reusable and non-reusable containers, of which only the reusable containers are supplied to the cleaning process.
3. A method according to claims 1 or 2, characterized in that the thermal drying treatment is performed by microwave.
4. A method according to one of claims 1 to 3, characterized in that refrigerating treatment is performed by the blowing-on of a refrigerant, more particularly liquid nitrogen.
5. A method according to one of claims 1 to 4, characterized in that the paint residues released from the container are ground and used in the manufacture of paints.
6. A method according to one of claims 1 to 5, characterized in that the wet cleaning is performed by high pressure and/or by means of brushes.
7. A method according to claim 6, characterized in that in the wet drying, hydroxyethyl cellulose is added to the cleaning agent in a concentration of 0.05 ppm to 10 ppm, preferably 0.1 ppm.
8. A method according to one of claims 1 to 7, characterized in that the cleaned containers are sterilized.
9. A method according to one of claims 6 to 8, characterized in that sterilization is performed immediately following wet cleaning.
10. A method according to one of claims 1 to 9, characterized in that the cleaned and dried containers are subjected to an inspection in dependence on whose result the unusable containers are granulated.
11. A stackable bucket of resiliently deformable material, more particularly for the storage of latex paints, having a bucket wall (2) opening slightly conically from the bucket bottom (1) to the cover edge (3a) and also having opposite ribs (6) formed on the bucket wall and extending parallel with the plane of the bucket for the attachment of a pivotable handle (4), characterized in that the ribs have a supporting base (7, 7a), the ribs (6, 6a, 6b) having in the zone of their supporting base (7, 7a) a trapezoidal notch which is formed between the bucket wall and the rib and engages with a recess (8a, 8b) in the cover edge (3a, 3b) of the subjacent bucket in the stack, the longitudinally slotted and undercut ribs (6a, 6b) forming a snap closure for the ends of the handle pointing towards one another.

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