| EP3253836A1 | 2017-12-13 | |||
| EP0888601A1 | 1999-01-07 | |||
| DE29803159U1 | 1998-04-23 | |||
| KR20130079908A | 2013-07-11 | |||
| JP2004347706A | 2004-12-09 | |||
| US20150060320A1 | 2015-03-05 | |||
| US20140069587A1 | 2014-03-13 | |||
| EP2847257A1 | 2015-03-18 |
| CLAIMS 1. A label made of polymer material comprising a front surface and a rear surface, wherein said rear surface has discrete portions of adhesive arranged at a minimum distance from one another greater than or equal to 0.5 mm. 2. The label according to claim 1 , wherein said polymer material of the label is selected from: olefin polymers, polystyrene, PET, rPET, polyethylene (PE), PVC, polylactic acid, biopolymers and combinations thereof. 3. The label according to claim 1 or 2, wherein the adhesive comprises an acrylic polymer, preferably having “wash-off” properties such as to produce a detachment of a paper label within 3 minutes from a support made of coated paper having a density of 80 g/m2 by washing it with a solution of 2% NaOH at 75°C, such wash-off properties being measured with the FTM26 method. 4. The label according to any of claims 1 to 3, wherein the minimum distance between the discrete portions of adhesive is comprised between 0.75 mm and 5 mm, preferably between 0.75 mm and 3 mm, preferably between 0.75 mm and 2 mm, preferably between 0.75 and 1.5 mm, preferably between 0.8 and 1.2 mm, preferably between 0.8 and 0.9 mm, preferably between 0.85 and 0.9 mm, preferably between 0.8 and 1.2 mm, preferably between 0.9 and 1.1 mm, preferably between 0.9 and 1.0 mm. 5. The label according to any of claims 1 to 4, wherein the portions of adhesive have a shape selected from among a circle shape, an oval shape, a rhomboidal shape, a square shape, a rectangular shape, a trapezoidal shape, a parallelepiped shape, a star shape, a drop shape, a half-moon shape, a written-text shape, a drawing shape or a combination of such shapes. 6. A film made of polymer material comprising a front surface and a rear surface, wherein said rear surface has discrete portions of adhesive arranged at a minimum distance from one another greater than or equal to 0.5 mm, preferably comprised between 0.75 mm and 5 mm, preferably between 0.75 mm and 3 mm, preferably between 0.75 mm and 2 mm, preferably between 0.75 and 1.5 mm, preferably between 0.8 and 1.2 mm, preferably between 0.8 and 0.9 mm, preferably between 0.85 and 0.9 mm, preferably between 0.8 and 1.2 mm, preferably between 0.9 and 1.1 mm, preferably between 0.9 and 1.0 mm. 7. A use of the film made of polymer material according to claim 6 for preparing a plurality of labels according to any of claims 1 to 5, through die-cutting into the desired shape. 8. A method for removing an adhesive label from an item intended to be recycled comprising: a) providing an item to be recycled, wherein the item has an adhesive label attached thereto, wherein said label comprises a front surface and a rear surface in contact with the item, wherein said rear surface has discrete portions of adhesive arranged at a minimum distance from one another that is greater than or equal to 0.5 mm, preferably comprised between 0.75 mm and 5 mm, preferably between 0.75 mm and 3 mm, preferably between 0.75 mm and 2 mm, preferably between 0.75 and 1.5 mm, preferably between 0.8 and 1.2 mm, preferably between 0.8 and 0.9 mm, preferably between 0.85 and 0.9 mm, preferably between 0.8 and 1.2 mm, preferably between 0.9 and 1.1 mm, preferably between 0.9 and 1.0 mm; b) subjecting the item to be recycled to washing with a basic solution or with water for a time less than or equal to 2 hours. 9. The method according to claim 8, wherein said item to be recycled is an item made of polymer, glass or metal material. 10. The method according to claim 8 or 9, wherein the basic solution is an aqueous solution of NaOH, KOH, LiOH, MgOH, CaOH or mixtures thereof. 11. The method according to any of claims 8 to 10, wherein the washing with basic solution or water is performed for a time less than or equal to 2 hours, preferably less than or equal to 1 hour, more preferably between 1 minute and 1 hour. 12. The method according to any of claims 8 to 11, wherein the washing with basic solution or water is performed for a time comprised between 1 minute and 30 minutes, preferably between 1 minute and 20 minutes, more preferably between 1 minute and 10 minutes, even more preferably for a time equal to 1-8 minutes, preferably 1-5 minutes, more preferably 1- 4 minutes. 13. The method according to any of claims 8 to 12, wherein the washing with water or basic solution is performed at a temperature comprised between 20°C and 100°C, preferably between 25 and 80°C, more preferably between 35 and 50°C or between 70 and 100°C, even more preferably between 70 and 80°C. 14. The method according to any of claims 8 to 13, wherein prior to step b) the item to be recycled is ground and the fragments obtained from grinding are subjected to step b). |
“METHOD FOR REMOVING PLASTIC LABELS FROM AN ITEM”
DESCRIPTION
FIELD OF THE INVENTION
The present invention relates to a method for removing a label made of polymer material from an item, e.g. from a container made of plastic, glass or another material, for the purpose of promoting the recyclability of the material of the container.
PRIOR ART
The use of polymer materials for packaging products of any kind, e.g. edible products such as food and drink, products for personal care such as detergents, soaps, shampoo, conditioner, creams, perfumes, etc., is increasingly common thanks to the impact resistance, transparency and lightness properties of plastics with respect to other materials such as glass and metal. In particular, thermoplastic polymers, such as polyethylene terephthalate (PET), are still very commonly used in the packaging industry. To most plastic packaging an adhesive label is applied which bears a drawing, some writing, the brand of the manufacturer and/or of the product and any information relating to the packaging product. The label may be paper or, more often, polymer material such as polyethylene, polypropylene, polyester, polyethylene terephthalate, polystyrene, polyvinyl chloride. The label adheres to the package by means of a pressure-sensitive adhesive (PSA) which is typically acrylic based.
As plastic packaging is still very common, the problem exists of having to recycle such materials efficiently and with contained costs.
The final consumer of products normally places the plastic packaging into the containers for separate collection of plastic without removing the label. Recycling centres therefore have to remove the labels, e.g. through washing, thus increasing the recycling efficiency of the plastic material that constitutes the packaging. The separation of the label from the package is important as it is typically made of a different material from that of the packaging to which it is applied. For example, the label may be made of paper or a polymer material different from the one used for the package.
If the label were not removed, the material (e.g. plastic or glass) of the containers would be mixed with the adhesive and the material of the label, with consequent recycling process efficiency problems.
It is therefore important for the label to be detached quickly and completely from the packaging which is then recycled with known processes.
In the case of paper labels, there are solutions already available for removing them easily, based on the use of adhesives that can be detached from the item in contact with basic solutions in just a few minutes (e.g. in 3 minutes). However, this result is obtained especially thanks to the fact that the paper, being porous, enables the penetration of the alkaline washing solution through its entire surface, so that the solution comes into contact with the adhesive, making the detachment process very efficient and quick.
If, instead, the label is made of polymer material, it is not impregnated with alkaline solution as the polymer material is not porous like paper and is, thus, very often impermeable to liquids. The alkaline solution can therefore only penetrate through the exposed section of adhesive which is located between the label and the packaging, a section which however represents a negligible surface area. The consequence is that the label detachment reaction takes a very long time, a lot more than the typical 3 minutes for paper labels.
Various methods for removing plastic labels are also known. Some of these methods are based on the properties of the polymer that constitutes the label, which enable the label to be removed very quickly. For example, EP0951004 and US6680097 describe shrinkable polymer labels that are elongated in at least one direction prior to their application to the packaging. With the effect of the heat or when it comes into contact with the hot removal solution, the label returns to its original shape, i.e. to the shape prior to the elongation, mechanically facilitating its detachment from the packaging.
Other known method are, for example, described in WO2014/039796 and W02005/085381.
WO201 4/039796 proposes the grinding of the packaging with the label and subsequently the removal of the label from the fragments of product through washing with a hot alkaline solution and strong agitation. The contact surface between the alkaline solution and the adhesive thus becomes very high and this facilitates the removal of the label. W02005/085381 discloses a method in which, on the adhesive of the label, channels are created with a thickness no greater than 15 pm, a width no greater than 250 pm and a distance between adjacent channels comprised between 10 pm and 10 mm. In addition to the formation of channels on the adhesive, it is also envisaged that, on the entire surface of the adhesive or on a part of it, an agent is applied which modifies the adhesive, e.g. a paint.
Both the channels and the agent modifying the adhesive have the aim of promoting the removal of the label during the recycling of the packaging. In fact, the channels should facilitate the entry of the basic solution whereas the modifying agent has the aim of lowering the level of adhesion of the adhesive to the packaging and promoting the entry of the basic solution through the empty spaces that are formed if the modifying agent is applied to the adhesive partially.
However, the solution described in W02005/085381 has some drawbacks due, in the first place, to the reduced width of the channels which does not enable the entry of a suitable quantity of basic removal solution. In the second place, the method of this publication envisages the formation of channels by means of an embossing roller, but this solution is difficult in practice as well as having serious reproducibility and quality problems. Furthermore, the method of W02005/085381 envisages the addition of an agent that modifies the adhesive, therefore a further step that implies wasted time and an increase in the costs of the label.
From the example present in W02005/085381 it is possible to deduce that the configuration of label proposed enables removal in 3 minutes if the front layer is made of regenerated cellulose, whereas 8 minutes are required in the event in which the front layer is made of BOPP (biaxially- oriented polypropylene). For the removal a 2% NaOFI solution containing 0.1% of P3 Stabilon Plus, a washing additive sold by Ecolab, and a temperature of 80°C are used.
In order to overcome the known drawbacks, the Applicant has developed a label made of polymer material characterised by particular ease of removal and a method for removing such label from a support that enables the detachment of the label made of polymer material from polymer or glass supports in less than 3 minutes, therefore representing an improvement with respect to W02005/085381.
SUMMARY OF THE INVENTION
The present invention relates to a method for removing an adhesive label from an item intended to be recycled, wherein the label attached to the item to be recycled comprises a front surface and a rear surface, in contact with the item, on which there are discrete portions of adhesive, wherein such discrete portions of adhesive are arranged at a minimum distance from one another equal to 0.5 mm.
The method envisages subjecting the item to be recycled, possibly following the grinding of the item with the label, to washing with water or with a basic solution for a time less than or equal to 2 hours for obtaining the complete detachment of the label from the item, preferably by heating to a temperature greater than room temperature (23-25°C).
The invention also relates to a label made of polymer material comprising a front surface and a rear surface, intended to come into contact with an item, on which there are discrete portions of adhesive, wherein such discrete portions of adhesive are arranged at a minimum distance from one another greater than or equal to 0.5 mm.
The invention also relates to a film made of polymer material comprising a front surface and a rear surface, intended to come into contact with an item, on which there are discrete portions of adhesive, wherein such discrete portions of adhesive are arranged at a minimum distance from one another greater than or equal to 0.5 mm. From the polymer film, a plurality of labels according to the invention can be obtained, having different shapes and sizes by die cutting the film.
BRIEF DESCRIPTION OF THE FIGURES
Figure 1 shows an example of a label according to the method of the present invention, schematically representing, not to scale, discrete portions of adhesive in the shape of rhombuses arranged at a minimum mutual distance greater than or equal to 0.5 mm;
Figure 2a shows an example of a label according to the method of the present invention, schematically representing, not to scale, discrete portions of adhesive in the shape of circles arranged at a minimum mutual distance greater than or equal to 0.5 mm;
Figure 2b shows a longitudinal section view of the label of Fig. 2a according to the invention;
Figure 2c shows a hypothetical longitudinal section view of the label of Fig. 2a, if it were obtained through the method described in W02005/085381, i.e. through the application of adhesive to the entire surface of the label and subsequent processing with an embossing roller to obtain the desired circular shape;
Figure 3 shows a microscopic photograph of a label according to the method of the present invention, where the diameter of the discrete portions of adhesive and the minimum distance between them have been measured. DETAILED DESCRIPTION OF THE INVENTION
The method for removing an adhesive label from an item intended to be recycled comprises: a) providing an item to be recycled, wherein the item has an adhesive label attached thereto, wherein said label has a front surface and a rear surface in contact with the item, wherein said rear surface has discrete portions of adhesive arranged at a minimum distance from one another that is greater than or equal to 0.5 mm; b) subjecting the item to be recycled to washing with a basic solution or with water for a time less than or equal to 2 hours.
The item on which the label is applied is packaging, a package, a bottle, a container or a sachet and it is made of polymer material, glass, metal or metal alloys. Preferably, the item is packaging, e.g. a bottle, for edible liquids, such as water, juice, soft drinks, etc., or it is a container for products intended for personal care or for the home, such as for example bottles for detergents, tubes for creams, shampoo, conditioner, etc.
The item to be recycled is an item made of polymer material or glass or metal.
The polymer material of the item can for example be polyethylene terephthalate (PET), recycled polyethylene terephthalate (rPET), high density polyethylene (HDPE), polyvinyl chloride (PVC), low density polyethylene (LDPE), polypropylene (PP), polystyrene (PS), polylactic acid (PLA), biopolymers, cellulose, polyester, recycled polyester or mixtures thereof.
The metal can be, for example, aluminium.
The polymer material of the label according to the invention is selected from olefin polymers, polystyrene, PET, rPET, polyethylene (PE), PVC, polylactic acid, biopolymers and combinations thereof. The label comprises a front surface which remains visible when the label is applied to the item and a rear surface which comes into contact with the item through the adhesive applied thereto.
The adhesive is a pressure-sensitive adhesive (PSA) comprising an acrylic polymer. Preferably, the acrylic polymer has “wash-off” properties such as to produce a detachment of a paper label within 3 minutes from a support made of coated paper having a density of 80 g/m 2 by washing it with a 2% NaOH solution at 75°C.
The wash-off properties defined herein are measured with the FTM26 method of the European association of the self-adhesive label industry - FINAT -www.finat.com.
The discrete portions of adhesive are applied to the rear surface of the label, i.e. they are distributed on the rear surface at a minimum distance between one another greater than or equal to 0.5 mm. Preferably, the minimum distance between the discrete portions of adhesive is comprised between 0.75 mm and 5 mm, preferably between 0.75 mm and 3 mm, preferably between 0.75 mm and 2 mm, preferably between 0.75 and 1.5 mm, preferably between 0.8 and 1.2 mm, preferably between 0.8 and 0.9 mm, preferably between 0.85 and 0.9 mm, preferably between 0.8 and 1.2 mm, preferably between 0.9 and 1.1 mm, preferably between 0.9 and 1.0 mm. In other words, the discrete portions of adhesive present on the rear surface of the label are positioned at a minimum mutual distance greater than or equal to 0.5 mm. Preferably, the discrete portions of adhesive are positioned at a minimum mutual distance comprised between 0.75 mm and 5 mm, preferably between 0.75 mm and 3 mm, preferably between 0.75 mm and 2 mm, preferably between 0.75 and 1.5 mm, preferably between 0.8 and 1.2 mm, preferably between 0.8 and 0.9 mm, preferably between 0.85 and 0.9 mm, preferably between 0.8 and 1.2 mm, preferably between 0.9 and 1.1 mm, preferably between 0.9 and 1.0 mm.
The discrete portions of adhesive are positioned on the rear surface through a two-dimensional distribution on the plane of the rear surface. The discrete portions of adhesive are positioned on the rear surface so as to maintain the minimum distance indicated and create, with their arrangement, a plurality of empty portions or interwoven bands, i.e. free from adhesive. The bands free from adhesive are portions of label, in particular of rear surface of the label, where the adhesive is not present and they enter into direct contact with the item. The adhesion of the label onto the item is guaranteed by the discrete portions of adhesive present on the surface.
“Minimum distance” means the distance between the two most proximal points of at least two discrete portions of adhesive.
The discrete portions of adhesive can have a variety of shapes. By way of example, they may be a circle shape, an oval shape, a rhomboidal shape, a square shape, a rectangular shape, a trapezoidal shape, a parallelepiped shape or a combination of these shapes. Other possible shapes are a star shape, a drop shape, a half-moon shape, a written-text shape, a drawing shape or a combination of these shapes. Figure 1 shows a representation, not to scale, of an embodiment of the label of the method of the invention, indicated with number 1 , in which the back of the same 2 is indicated, i.e. the rear surface, intended to come into contact with the item. On such surface, the portions of adhesive 3 can be seen, which have a rhomboid shape. Between the portions of adhesive, there are portions free from adhesive 4, i.e. empty, where the label is visible. These portions have a band or channel shape. The discrete portions of adhesive are arranged on the surface at a minimum (mutual) distance from one another greater than or equal to 0.5 mm even if the figure is not to scale.
Figure 2a shows a further representation, not to scale, of an embodiment of the label of the method of the invention, indicated with number 1 , in which the back of the same 2 is indicated, i.e. the rear surface, intended to come into contact with the item. On such surface, the portions of adhesive 3 can be seen, which have a circular shape. Between the portions of adhesive, there are portions free from adhesive 4, i.e. empty, where the label is visible. The discrete portions of adhesive are arranged on the surface at a minimum (mutual) distance from one another greater than or equal to 0.5 mm even if the figure is not to scale.
The label of the invention is prepared, in the desired form, by cutting a polymer film.
The film made of polymer material comprises a front surface and a rear surface, intended to come into contact with an item, on which there are discrete portions of adhesive, wherein such portions of adhesive are arranged at a minimum distance from one another greater than or equal to 0.5 mm.
The discrete portions of adhesive are applied to the rear surface of the film through known techniques in the sector, e.g. through screen printing, which consists of spreading the adhesive onto a mesh whose pattern bears the desired drawing, e.g. the rhombus shape of the embodiment of label shown in figure 1. The adhesive is then pushed through the frame onto the rear surface of the label.
At industrial level it may be particularly advantageous to use rotary screen printing for spreading the adhesive and creating the desired shape.
After the screen print application of the adhesive, the adhesive is dried and/or cross linked by heating, e.g. in an oven or through other techniques such as for example UV radiation. After this, the film made of polymer material is cut so as to create a plurality of labels of the invention of the desired shape.
The screen print application of the adhesive is undoubtedly more advantageous with respect to the use of an embossing roller after the adhesive has been spread onto the surface, as happens in W02005/085381. The advantages are connected with the fact that in the case of the present method the drawing is created at the start, whereas in the case of the prior art it is impressed a posteriori onto the adhesive. Furthermore, with the method of the invention the drawing is created prior to subjecting the adhesive to drying in the oven, whereas in the case of the prior art, the drawing is applied onto an adhesive that is already dry and possibly cross linked. In this way, the drawing created through the method of the present invention has a much more stable structure with respect to a drawing created with the embossing roller of the prior art.
The method described by the prior art, therefore, has various disadvantages. The first is that the embossing roller impresses a drawing into the adhesive displacing the masses, thus generating areas with more adhesive and areas with less adhesive, but never areas free from adhesive. The differences between the method of the present invention and the method of W02005/085381 are highlighted by figures 2b and 2c.
Figure 2b represents a longitudinal cross section of the label 1 according to the embodiment of the invention shown in figure 2a. It is clear that the portions without adhesive (channels or bands) 4 are clean and totally free from adhesive.
In the case of the prior art, instead, the label 5 according to W02005/085381 is shown in Fig. 2c as a longitudinal section. Following the application of the embossing roller, as envisaged by the prior art, channels 6 are formed on the adhesive in which there is always a thickness of adhesive and domes of adhesive 7. It is clear how this implies a different efficiency in the detachment process. In the realisation of the prior art the label has a larger adhesive surface (the channels are also adhesive) and the water that crosses the channels is engaged to interact not only with the really adhesive zones but also with the adhesive mass present in the channels themselves. All this implies greater inefficiency of the wash off process.
The second disadvantage is connected with the fact that the roller exercises its action on an adhesive already spread and therefore already dried and possibly cross linked. The adhesive in this final form is much more resilient and it may be possible that after the passage of the roller it tends to recover its initial shape. We can hypothesise that after the passage of the roller the domes 7 of figure 2c tend to flatten and the channels 6 to increase in thickness. Vice versa, with the method of the present invention the adhesive is provided with screen printing precision according to the predefined drawing and thus fixed through the subsequent hot drying passage.
The third disadvantage is connected with the maintenance of the system. The embossing cylinder, constantly in contact with the adhesive, will tend to repeatedly get dirty with consequent productivity problems, need for maintenance and especially, sub-optimal results in terms of quality and cleaning of the drawing of the adhesive.
In step b) in which the item bearing the adhesive label is subjected to washing in water or in a basic solution, the water is water with ions or deionized water.
The basic solution is preferably an aqueous solution of NaOH, KOH, LiOH, MgOH, CaOH or mixtures thereof.
The concentration of the basic solution is comprised between 1 and 5% by weight of base. For example, the basic solution is an NaOH solution with a concentration comprised between 1 and 5% by weight, preferably 2% by weight.
The basic solution or water is applied to the item bearing the label for a time less than or equal to 2 hours, preferably less than or equal to 1 hour, more preferably between 1 minute and 1 hour. In one embodiment the water or basic solution is applied to the item for a time comprised between 1 minute and 30 minutes, preferably between 1 minute and 20 minutes, more preferably between 1 minute and 10 minutes. In a preferred embodiment, the water or basic solution is applied for a time equal to 1-8 minutes, preferably 1-5 minutes, more preferably 1-4 minutes.
The labelled item is subjected to washing with water or with basic solution by dipping the item in the solution or in the water. The water or basic solution is applied to the item at a temperature comprised between 20°C and 100°C, preferably between 25 and 80°C, preferably between 35 and 50°C or between 70 and 100°C, preferably between 70 and 80°C.
In one embodiment the basic solution is an aqueous solution of NaOH at a concentration between 1 and 5% by weight applied to the labelled item for a time less than or equal to 5 minutes, preferably less than or equal to 4 minutes, at a temperature between 70 and 100°C, preferably between 70 and 80°C.
In one embodiment, the water is applied to the labelled item for a time less than or equal to 1 hour, preferably less than or equal to 10 minutes, more preferably comprised between 1 and 4 minutes, even more preferably between 2 and 4 minutes, at a temperature between 70 and 100°C, preferably between 70 and 80°C.
Step b) of washing with water or with basic solution leads to the complete removal of the polymer label and of the adhesive very quickly in the event of hot application, e.g. in less than the 8 minutes of the prior art, as demonstrated by the experiments included herein.
This is due to the presence of portions of adhesive placed at a minimum distance between the discrete portions of adhesive greater than or equal to 0.5 mm on the rear surface of the label in contact with the item. Furthermore, by using an adhesive with wash-off properties as indicated above, a synergistic effect is obtained which determines the good performance of the method of the present invention, as demonstrated by the experiments reported herein.
In one embodiment of the invention, prior to step b) the item to be recycled is ground and then the fragments obtained by the grinding are subjected to step b) described above.
The method of the present invention enables good removal results to be obtained in times of less than or equal to 2 hours, preferably less than or equal to 1 hour, preferably in a few minutes, even with water. This enables the removal of the plastic labels to be made more ecological and less expensive, preventing the use of basic solutions that require specific disposal or recycling processes.
EXAMPLE 16 g of WR40 adhesive, a water based acrylic adhesive, were applied to a polypropylene film with a thickness of 60 pm.
The wash-off properties of the WR40 adhesive were tested by spreading effective 16 g of adhesive per m 2 on a film of coated paper with a weight of 80 g/m 2 . The resulting adhesive film of coated paper was cut into labels 5.5 X 8.0 cm, applied to glass bottles and left to adhere for 24 hours.
The bottles were then subjected to the FTM26 test of the FINAT at the temperature of 75°C in a 2% NaOFI solution.
The coated paper labels were detached from the bottles after an average of 20 s in the bath of alkaline solution.
The application of the WR40 adhesive on the polypropylene film was performed in two ways:
1) application of a uniform layer; 2) application of portions of adhesive wherein the adhesive was distributed in circular portions of diameter about 1.0-1.3 mm and spaced out from one another by 0.8-0.9 mm (see Fig 3).
The two samples obtained according to points 1) and 2) were converted into labels of dimensions 5.5X8.0 cm.
The labels were applied respectively to glass bottles and FIDPE bottles and left to adhere for 24 hours. Then, the two types of bottles were subjected to dipping in baths of water and basic water, respectively, at different temperatures according to the diagram provided below:
5 Table 1
The results of table 1 clearly show that both with a glass item and with a PE item, the removal of the label according to the present invention takes place in times of less than 4 minutes in the event of a hot solution, both 10 aqueous and basic.
In the event of removal at room temperature, both with water and with basic solution, the times are longer but they are still much shorter with respect to the label with a uniform layer of adhesive.
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