FR2736566A1 - Adhesive label cleaning and removal from polyvinyl chloride bottles - Google Patents

Abstract

Procedure for cleaning and removal of adhesive labels from plastic flasks (R) partic. bottles prior to recycling comprises: (i) subjecting them to a thermal shock by exposure to jets of steam to soften the plastic and unstick the labels; where: (a) prior to this the bottles are held by the neck and crushed to obtain a flattened bottle (R') of similar height to the original; (b) this is cut longitudinally into strips (R''); and (c) the strips are finally subjected to a second thermal shock in cold air. Also claimed is the equipment.

Description

PROCESS AND INSTALLATION FOR CLEANING AND CLEANING
OF THEIR ADHESIVE LABELS OF THE BOTTLES IN MATERIAL
PLASTIC, FOR THEIR RECYCLING
The present invention relates to a method and an installation for cleaning and ridding their adhesive labels of plastic bottles such as bottles, for the purpose of recycling said plastic material.

 The process and installation of the present invention are particularly but not exclusively intended for the treatment of polyvinyl chloride (PVC) bottles.

 Document WO-A-94/22602 describes in the name of the applicant a method and an installation of this type.

 The process essentially consists in subjecting the bottles to thermal shock by exposing their walls to jets of water vapor, which has the effect of suddenly softening the plastic material by causing the labels to peel off.

 This process is entirely satisfactory since almost all of the treated bottles are stripped of their labels at the end of this treatment.

 However, recycling the plastic material, for example by grinding, can only be rationally envisaged if the entire bottle is clean, both inside and out.

 It is easily understood that the thermal shock with water vapor achieves at the same time the cleaning of the external wall of the bottle.

 It is proposed in the aforementioned document to carry out the cleaning of the bottle by drilling the plastic material and introducing steam into the container. However, this drilling requires having to "clamp" the bottle so that this operation is carried out under the best conditions, which complicates the structure of the installation. Furthermore, it has been found that moisture remains inside the bottle, even after subsequent drying.

 Document US-A4 599 131 describes an apparatus for ridding plastic bottles of their labels. This device includes a series of heated rollers between which the bottles are engaged. The rollers crush the bottles like a pancake while peeling off the label. Downstream there are rotating brushes which completely remove the label from the bottle and clean up the adhesive residue.

 This process applies to the removal of badly positioned labels on bottles, and cleaning of the inside of the bottles is not mentioned.

 The object of the present invention is to propose a method and an installation for treating plastic bottles, in particular bottles, with a view to recycling the plastic material, which makes it possible to obtain a dry, clean bottle, free of its labels, directly usable for recycling plastic.

 Another object of the invention is to achieve the aforementioned objective within a single installation, that is to say without prior cleaning of the bottles.

 Yet another object of the invention is to implement these operations in a simple manner, without excessive consumption of energy.

 The process of the invention is of the type according to which said bottles are subjected to a thermal shock by exposing their wall to jets of water vapor, which has the effect of suddenly softening the plastic material by causing the release of their label. .

It is remarkable by the fact that, prior to this step:
- While grasping said bottles at their neck, they are crushed so as to obtain modified flat bottles and height substantially equivalent to that of the original bottles, then cuts are made in the direction of their height, from the neck to their base, so as to obtain articles formed of plastic strips,
and in that after said step:
- The articles formed from strips are subjected to a second thermal shock by directing cold air thereon.

 By crushing and cutting the bottles, the steam treatment will not only remove the labels but also the internal and external cleaning of their walls. In addition, their drainage is facilitated by the constitution of the bottle in the form of strips.

 Furthermore, the treatment with a second thermal shock realizes the complete drying of the bottles, while ridding them of any label debris which could have remained stuck thereon.

According to other advantageous but non-limiting characteristics of the process:
- the bottles are seized in the area of their neck located above the area for receiving a closure cap;
- The process begins with a first step which consists in subjecting the uncrushed and uncut bottles to a treatment with hot air;
- This treatment includes the step of directing hot air jets on the bottles;
the step according to which the articles formed of strips are subjected to a second thermal shock is followed by a treatment of these with a current of hot air;
- While maintaining the vials gripped at their neck, a cut is made of said neck in the receiving area of the closure cap, this cutting being performed substantially in the longitudinal direction of the bottle.

 The invention relates to an installation for cleaning and ridding their adhesive labels of plastic bottles, such as bottles, with a view to recycling the plastic material. It is of the type which comprises mobile endless conveyor means intended to receive the containers, these conveyor means being arranged inside an enclosure which comprises means for spraying water vapor onto the wall of the containers.

 It is characterized by the fact that it comprises, upstream of said means for spraying water vapor onto the walls of the containers, means capable of crushing said bottles in order to obtain modified flat bottles and of height substantially equivalent to that of the bottles. original, as well as means capable of making cuts therefrom, from their neck to their base, so as to obtain bottles formed from plastic strips.

According to other advantageous but non-limiting characteristics of the installation:
- The conveyor means consist of an endless chain or belt with superimposed strands, which includes clamps for hooking said bottles, arranged so that they generally stand vertically;
- It includes, upstream of the crushing means, hot air treatment means;
- It comprises downstream means for spraying water vapor, means for treating with cold air, so as to subject them to a second thermal shock.

Other characteristics and advantages of the present invention will appear on reading the description of certain preferred embodiments, made with reference to the accompanying drawings in which:
- Figure 1 is a schematic general view of an installation according to the invention, integrated within a processing and recycling unit;
- Figure 2 is a simplified view, partially in vertical section, of a feeding station in bottles, equipped with means for turning the bottles incorrectly positioned;
- Figure 3 is a view of the means for hanging bottles on an endless conveyor;
- Figure 4 is a simplified view of a station for treating vials with hot air;
- Figure 5 is a view of a subsequent hot air treatment station;
- Figure 6 is a perspective view of two bottles treatment stations, respectively crushing and cutting thereof;
- Figure 7 is a diagram intended to show how the treatment of the bottles is carried out with water vapor.

 An installation according to the invention is shown diagrammatically in FIG. 1, where the various stations which compose it are integrated into a general unit for cleaning and recycling plastic bottles.

 These bottles are intended to undergo various operations at the level of stations referenced A to I, the plastic products being, at the end of the treatment, capable of being ground to be recycled.

The different positions of the installation are as follows:
- A: vials loading station
- B: hot air treatment station
- C: treatment station using hot air jets
- D: bottle crushing station
- E: bottle cutting station
- F: steam treatment station
- G: cold air treatment station
- H: hot air treatment station
- I: container disposal station
The installation according to the invention comprises an enclosure L, for example of metallic material such as stainless steel, which contains the various stations mentioned above.

 Inside the enclosure is provided a mobile endless conveyor 1 whose two strands are superimposed and which is driven, in the direction of arrow f by means of rollers 10, 11, 12 and 13, one of which at the less is driving. Its movement is continuous, at slow and uniform speed.

 In a particularly advantageous manner, this conveyor is formed from a belt or a chain and is equipped with means 14 capable of gripping and hanging the bottles to be treated at their neck. These are for example pliers such as those described in FIG. 7 of document WO-A-94/22602.

 The installation is equipped with means, not shown, of a type known per se, which make it possible to open and then close the clamps at the level of stations A and I so as to attach the bottles therein and release them respectively.

 Between these stations, the clamps are closed and retain the bottles on the conveyor 1.

 The first station in the installation is the bottle loading station A.

It can be a manual station, operators carrying out themselves the attachment of the bottles on the conveyor.

 The loading station illustrated in Figure 2 is an automated station. It includes a hopper 20 for receiving the bottles which are deposited therein in bulk. The bottom of the hopper opens onto a frustoconical duct which is connected to a sheath 22. This sheath is provided with an annular suction system 23 associated with a pump, the function of which is to suck one by one the bottles present in the hopper. They are then accumulated at the level of a second sheath 25 which leads to a system for detecting and turning over the bottles.

 The role of this system is to position all of the bottles so that they face the neck down. This system includes a sensor 26 able to identify the positioning of the bottle at the end of the sheath 25. Plumb with the sheath 25 is provided a rotary reversing device 27 with a horizontal axis which is provided with a sleeve arranged in the axis of the sheath 25 for the reception of a bottle.

 If the sensor 26 has determined that a bottle has turned the neck upwards, it then actuates a flap 28 for closing the turning device and also causes the rotation of this latter device over 1800. The bottle is then turned over and the hatch 28 is open. It then falls by gravity into a corridor 290 which is delimited laterally by a vertical partition 29 and a conveyor 29 "with an endless moving belt whose drive rollers are arranged vertically. This corridor is delimited at its bottom by a piece 29 ′ of generally frustoconical cross section in which the neck of the bottle engages, in order to partially emerge therefrom.

 Corridor 290 extends above and perpendicularly to the upper point of the conveyor 1. Starting the conveyor 29 "makes it possible to move the bottles R one by one so as to bring them closer to the conveyor so that they can be gripped by the clamps 14 which equip the conveyor, this is the situation illustrated in FIG. 3.

 The bottles are therefore gripped in such a way that they extend perpendicular to the strand of the conveyor while being pinched at their neck.

 Preferably, the bottles are pinched in the region of the neck which is located just below the zone for receiving a closure cap.

 The hot air treatment station B is formed by two parallel plates 3 between which the bottles R circulate in place on the lower strand of the conveyor. These plates are provided with means making it possible to diffuse hot air towards the containers, for example by convection. Just downstream from this station is the hot air treatment station C, which includes, as shown in FIG. 5, nozzles 30 for spraying pressurized hot air (AC) towards the containers R.

 The station D located immediately downstream comprises means capable of crushing the bottles R to obtain modified flat bottles R 'of height substantially equivalent to that of the original bottle. These means consist of conveyors 40 and 40 ′ with conveyor belts arranged on either side of the lower strand of the conveyor and between which the bottles R are caused to be moved.

 As shown in Figure 6, these conveyors 40 and 40 'have drive rollers 41, 42, 41', 42 'arranged vertically. Their direction of rotation symbolized by the arrows g and h are of course opposite. They each have a vertical metal bar 43, 43 ′, intended to bring the conveyor belts closer to one another in order to crush the bottles.

 The entry zone between the conveyors is convergent, which causes the bottles to be gradually crushed.

 At the exit from this station, the modified (crushed) bottles R ′ are returned to the level of the cutting station E which comprises two adjacent rotary rollers 5 and 5 ′, of vertical axis. Their respective directions of rotation are opposite as shown by the arrows k and l. The roller 5 'is provided with knives 50' arranged along its generatrices so that during the passage of the modified bottle R 'between the two rollers, the knives make cuts in the wall of the bottle, from below the clamp of the bottle to its base.

The steam treatment station F comprises a series of steam projection nozzles 6 in the direction of the crushed and cut containers. Finally, the posts
G and H respectively comprise a fan 7 and 8 intended to direct cold and then hot air over the bottles.

 Station I is used for manual or automated evacuation of treated containers.

 We will now describe how the process of the present invention is implemented.

 The bottles R to be treated, stored in the hopper 20 are directed by the means of FIG. 2 in the direction of the upper strand of the conveyor 1 and are fixed there by means of clamps 14.

 At station B, the bottles are subjected to hot air so that they tend to soften and deform. The air is for example at a temperature of the order of 70 to 80. At this stage, the labels retained on the bottles by means of a few dots of glue already tend to peel off.

 This action is completed by the jets of hot compressed air (AC) at station C.

 However, despite this preliminary treatment, a large number of bottles remain which still have at least strips of labels on their walls.

 The bottles are then crushed at the level of the station D and are then cut over their entire height by the knives 50 'of the stations E. At this level, the fractions still in place of labels on the walls of the bottles are detached by gravity due to the cutouts that have been formed on the sides of the vials.

 The projection of jets of steam V by means of the nozzles 6 in the direction of the crushed and cut bottles R "has the effect that the strips L of plastic thus formed twist and deform, which makes it possible to clean by means of the steam on both their outer and inner sides. In addition, spraying these items R "with water vapor causes a thermal shock on them, the temperature change being so abrupt that the plastic material softens practically instantaneously and causes the labels still in place on the articles to come off, whether they are made of paper or made of a plastic film.

 At this stage the vast majority of articles are clean and free of their labels.

 They undergo at station G a new thermal shock to a current of cold air generated by the fan 7 so that the plastic material solidifies instantly.

 Scraps of labels, possibly still retained on the articles, come off and fall by gravity. In addition, this cold air flow makes it possible to expel a very large part of the moisture still in place on the walls of the containers. Finally, the hot air drying station H makes it possible to obtain a plastic product ready to be ground with a view to recycling the plastic material.

 In the event that the bottles are treated while they still have a closure cap, it will be noted that it is possible to provide means which act at the level of the neck of the bottles and above the clips 14 so as to cut out this upper neck portion by cutting at the same time the plug which is in place. These means may consist of one or more rotary blades of horizontal axis which cut the upper part of the neck in the longitudinal direction.

 These means are arranged not only to cut the plugs (if they are present), but also to systematically eliminate the collars on the necks.

 Finally, in the event that the bottles to be treated are of the type that can be crushed after emptying their contents and replacing the stopper, we can then provide means for piercing this stopper and blowing inside the container pressurized air to return it to its original shape. The bottle thus prepared can then be treated in the manner described above.

 Moreover, it is possible to provide such a prior reshaping of all the bottles - compacted or not; with or without cap - before cutting the neck.

 Preferably, the blown air is at a temperature of the order of 70 "C.

 As appears from the description which has just been made, the process and the installation of the present invention make it possible to completely clean and rid the plastic bottles of the labels which they carry, so as to be able to recycle said plastic material, this in a particularly rational and economical way.

 This treatment applies to PVC containers, but also to various other plastic materials, in particular polyethylene.

 Advantageously, the installation is equipped with a shape recognition system - of known type - which, in the first instance, will reject all the bottles which are not made of PVC or polyethylene.

 On leaving the machine, the treated bottles will pass individually in front of an optical reader, driving a conveyor, which will then direct them towards the crusher intended for them.

 The installation will also sort and separate the bottles according to the families to which they belong, so that the preliminary sorting operations are no longer necessary upstream.

Claims (10)

 1. Method for cleaning and removing from their adhesive labels plastic bottles (R), such as bottles, with a view to recycling said plastic material, according to which said bottles are subjected to thermal shock by exposing their walls to jets of water vapor, which has the effect of suddenly softening the plastic by causing the label to peel off,  characterized in that, prior to this step:  - while grasping said bottles (R) at their neck, they are crushed so as to obtain modified bottles (R ') flat and of height substantially equivalent to that of the original bottles, then cuts are made therein the direction of their height, from the neck to their base, so as to obtain articles (R ") formed of plastic strips,  and in that after said step:  - The articles (R ") formed of strips (L) are subjected to a second thermal shock by directing cold air thereon.  2. Method according to claim 1, characterized in that said vials (R) are grasped in the region of their neck located above the region for receiving a closure cap.  3. Method according to claim 1 or 2, characterized in that it begins with a first step which consists in subjecting the bottles (R) not crushed and not cut to a treatment with hot air.  4. Method according to claim 3, characterized in that said treatment comprises the step of directing on the bottles (R) jets of hot air.  5. Method according to one of claims 1 to 4, characterized in that the step according to which the articles (R ") formed of strips (L) are subjected to a second thermal shock is followed by a treatment of these- this by a current of hot air.  6. Method according to one of claims 3 to 5 when it is dependent on claim 2, characterized in that, while maintaining the bottles (R) gripped at their neck, a cut is made of said neck in the area receiving the closure cap, this cut being made substantially in the longitudinal direction of the bottle.  7. Installation for cleaning and removing from their adhesive labels plastic bottles (R) such as bottles, with a view to recycling said plastic material, which comprises mobile endless conveyor means (1) intended to receive the containers ( R), these conveyor means being arranged inside an enclosure (M) which comprises means (6) for spraying water vapor onto the wall of the containers (R), characterized in that it comprises, upstream of said spraying means (6) of water vapor on the walls of the containers (R), means (40, 40 ') capable of crushing said flasks (R) to obtain flat modified flasks (R') and of height substantially equivalent to that of the original bottles, as well as means (5, 5 ') capable of making cuts therefrom, from their neck to their base, so as to obtain bottles (R ") formed of plastic straps.  8. Installation according to claim 7, characterized in that the conveyor means consist of an endless chain or belt (1) which comprises clamps (14) for the attachment of said bottles (R), arranged so that they generally stand vertically.  9. Installation according to claim 7 or 8, characterized in that it comprises, upstream of the crushing means (40, 40 ') means (3, 30) of hot air treatment.  10. Installation according to one of claims 7 to 9, characterized in that it comprises downstream means (6) for spraying water vapor, means (7) for treating with cold air, so to subject them to a second thermal shock.