BRPI1104689B1 - MECHANICAL RECYCLING OF MULTILAYER PACKAGING - Google Patents

Abstract

mechanical recycling of multilayer packaging. the present invention presents an alternative for recycling laminated multilayer packaging containing mainly aluminum, PET (polyethylene terephthalate) and PE (polyethylene). this type of packaging has the only alternative, so far, incineration with energy use. the incineration of multilayer packaging, in addition to being carried out only in some countries, generates a multitude of polluting gases. the amount of discarded multilayer packaging is very large since they are widely used as packaging for coffee, snacks, cookies, chocolates, pet foods and many other foods. there are many benefits achieved using this type of packaging with several different polymers (and other materials), as it makes it possible to obtain a material with excellent properties, such as gas barrier, water vapor, components that give flavor to the food and light, combined with great mechanical resistance. however, recycling of this type of material becomes very difficult, in addition to being very difficult to separate and classify these films, as there are many types and all are very similar visually, it is also very difficult to process them, as they are usually composed of polymers incompatible for recycling by extrusion. the present invention proposes the recycling of this type of packaging through the preparation of composite materials using plastic matrix, with excellent mechanical characteristics, through the processes of grinding, extrusion and injection.

Description

MECHANICAL RECYCLING OF MULTILAYER PACKAGING Introduction

The present invention presents an alternative for recycling laminated multilayer packaging containing aluminum, PET and PE. This type of packaging has the only alternative, so far, incineration with energy use. The incineration of multilayer packaging, in addition to being carried out only in some countries, generates a multitude of polluting gases. In Brazil, these packages do not present any type of recycling or reuse, being then accumulated in the industries or discarded inconsequentially in the dumps. The amount of discarded multilayer packaging is very large since they are widely used as packaging for coffee, snacks, cookies, chocolates, PET foods and many other foods. There are many benefits achieved using this type of packaging with several different polymers (and other materials), as it makes it possible to obtain a material with excellent properties, such as gas barrier, water vapor, components that give flavor to the food and light, combined with great mechanical resistance. However, recycling this type of material becomes very difficult, in addition to being very difficult to separate and classify these films, as there are many types and all are very similar visually, it is also very difficult to process them, as they are usually composed of polymers incompatible for recycling by extrusion.

The presence of other materials, such as aluminum, cardboard, paints, is also a problem in the recycling of multilayer plastic packaging, as well as the chemical incompatibility of the resins that make up the different plastic materials. In general, the smaller the number of polymeric components and the complexity of the packaging system, the greater its recycling value, as a consequence of the reduction of the technological steps and resources spent in the cleaning and separation processes of the materials that make up the packaging (delamination). The recyclability of plastic packaging is intrinsically related to the economic feasibility of implementing certain recycling routes, which means that these packaging of more complex (multilayer) formulations are discarded.

The purpose of this invention is the mechanical recycling of multilayer packaging most used commercially, prepared by the lamination process, containing an aluminum foil between layers of PET and polyethylene. The invention consists of the preparation of composite materials using a post-consumer high density polyethylene (HDPE) matrix and the

2/8 multilayer packaging used as reinforcement in this material. With this, the invention provides not only the recycling of multilayer packaging, but also HDPE, one of the most used plastics worldwide.

Composites are prepared through the injection process, where the pieces are molded into the desired shape, which makes it possible to use the material developed in several areas, from the manufacture of household items such as: buckets, basins, clothespins; like the manufacture of bumper cars.

For the development process of composites it is necessary that the multilayer packaging and the HDPEpc (post-consumer high density polyethylene) are crushed (together) in a knife mill and then better mixed through extrusion at the temperature above the melting of the HDPEpc.

The insertion of multilayer material in a polyethylene matrix makes it possible to obtain a new material with excellent mechanical properties: high elasticity and impact resistance. These characteristics are due to the presence of aluminum and PET in the final material that act as a barrier to the propagation of cracks, and also the presence of low density polyethylene - LDPE which acts as an impact energy absorber and contributes to increase elasticity. Thus, the presence of different materials in multilayer packaging, which was seen as the main obstacle in recycling them, becomes a great ally in obtaining a material with properties superior to the properties of many materials already on the market.

One of the great advantages in the preparation of composites is the flexibility in relation to the HDPE / reinforcement composition, which can reach up to 50% of multilayer material in the polyethylene matrix, enabling the manufacture of materials with different final mechanical properties, linked to their composition.

However, one of the main advantages of this process is its economic viability, considering that the mechanical recycling process is by far the most economically viable, when compared to other recycling processes: chemical and energy.

State of the art

Multilayer packaging is currently abandoned in dumps or in industries, only in some European countries this material is destined for energy recycling, that is, burning.

The present invention presents a totally innovative technology for the destination of

3/8 post-consumer multi-layer packaging and industrial waste and also for post-consumer polyethylene, with the manufacture of a highly resistant material with wide application.

In the search for priority, several products were found with a certain similarity, but none that could harm the novelty criterion of the present invention.

WO 2002/026244 is a composite material with a glass fiber reinforced polyester resin matrix. The technology now proposed differs in the type of matrix (post-consumer polyethylene) and mainly in the type of reinforcement, the new technology proposes the use of a reinforcement material that has different components (polyethylene-PE, polyethylene terephthalate-PET and aluminum), what makes it possible to obtain products with excellent mechanical properties; in addition to being a disposal material, which makes the product economically attractive.

WO 2006/060888 relates to the recycling of plastic materials that contain oil residues. It differs from the technology proposed by the type of recycled material and also the recycling proposed in the above patent does not use the addition of reinforcement material, many studies show that recycling without the addition of reinforcement generates materials with poor mechanical characteristics, that is, low tensile strength , flexion and impact, being able to fracture easily, besides presenting low thermal stability.

In addition, the present invention differs from the recycling of Tetra Pak packaging (www.tetrapak.com.br) in the type of recycled material, long-life packaging contains paper, polyethylene and aluminum, whereas multilayer packaging contains PET, polyethylene and aluminum, because the big complication in recycling this type of packaging is PET that has a high melting point, which makes it difficult to recycle by extrusion, however in the patent now proposed that high melting point of PET makes it perform the function of material reinforcement in the product developed, as it does not melt during the extrusion and injection process. Another point where the invention differs from the recycling of Tetra Pak packaging is the separation of the layers (delamination) used in the recycling process of long-life packaging, in the proposed invention the recycling of multilayer packaging does not need this delamination step, the packaging is processed with all components, which reduces costs in the recycling process.

Description of the Figures

For a better understanding of the object of the present invention, the following

4/8 following figures:

Figure 1. Tensile strength test: tensile strength for composites

HDPE / multilayer

Figure 2. Elongation at break for HDPE / multilayer composites Figure 3. Elasticity module for HDPE / multilayer composites; Figure 4. Impact resistance for HDPE / multilayer composites.

Detailed Description of the Invention

The present invention brings as an innovation the use of a material accumulated in industries and dumps until today. The invention is attractive not only because it is ecologically correct, but also because it can be a product with great potential for application, from the manufacture of household utensils such as: buckets, basins, clothespins; such as the manufacture of bumpers for cars, since the material obtained has high impact resistance and excellent properties related to traction and flexion.

Preparation of Composites

To prepare the composites, the materials (laminated multilayer packaging and post-consumer HDPE high density polyethylene) were washed and dried in an oven at 80 ° C for 12 hours. Then ground in a knife mill, Brand RONI, Model NFA 1533, Brazil.

Extrusion

The composites were processed in a mono-screw extruder Wortex Model WE X30, Brazil, with 5 heating zones and L / D = 32. The processing temperatures were 120 ° C, 130 ° C, 150 ° C, 180 ° C and 185 ° C in the first, second, third, fourth and fifth heating zones, respectively. The rotation speed was 102 rpm. Residence time of 90 seconds. After extrusion, the material was crushed (in the form of pellets) in a Picotador Primotécnica Modelo PGS 50, Series PGS 1/1, Brazil.

Injection

The specimens for the mechanical tests were prepared from the extruded and crushed composites. An ARBURG injector, 221 K 250 - 75, Germany, was used in the preparation of the specimens. The injection temperature was 180 ° C, injection pressure 1500 bar, discharge pressure 700 bar. The notation adopted in this text used for the different formulations of the injected composites was: PE for the matrix of HDPEpc, and multi for the multilayer packaging, the indices 10, 20, 30, 40 and 50 indicate the

5/8 percentage of multilayer packaging in the composite. So, as an example, the notation

PE / MultilO means a composite obtained with 10% by weight of multilayer packaging in a polyethylene matrix.

Characterization Techniques

For the analysis of the materials the following techniques were used:

- FTIR-ATR analysis: multilayer films were characterized by spectroscopy in the infrared region with total attenuated horizontal reflectance, using an infrared spectrophotometer with Fourier Bomem transform, model MB-100.

- Scanning electron microscopy: the morphological analysis of the composites was performed on the specimens submitted to impact resistance tests, using scanning electron microscopy using a Shimadzu brand, model SS-550, coupled to an energy analysis system. X-ray dispersive (EDS).

- Tensile strength: the tensile tests were performed on a universal testing machine - EMIC DL 2000 with a 5000 N load cell, claw speed of 50 mm / min, according to the ASTM D - 638 standard. For each formulation 8 tests were carried out.

- Flexural strength: in the flexion test, ASTM D - 790-00, method A, 3-point mode was followed. Eight tests were carried out for each sample, using EMIC DL 2000 equipment, a 5000 N load cell, with a distance between the supports of 63 mm and a speed of 20 mm / min.

- Resistance to the Izod Impact: for the Impact tests the specimens were notched and the tests carried out according to the ASTM D 256-00 standard, method A. Five tests were carried out for each sample in an EMIC -Al equipment, with pendulum of 2.7 J.

- Water absorption: the water absorption measures for the composites were based on the ASTM D570-98 standard, immersion time of 3 weeks and temperature of 25 +/- 2oC.

Results

For the preparation of the composites, laminated packaging containing aluminum foil (8 pm) was used between a layer of printed PET (12 pm) and a mixture (70/30) of PELBD - low density linear polyethylene and PELB - low polyethylene density (41 pm). The packaging was obtained by the lamination process, using adhesives based on polyurethane and ethyl acetate solvent. The mass percentage of each material was determined by gravimetry: 19% PET, 47% PE and 34% Al.

Figures 1, 2 and 3 show the results obtained from the

6/8 tensile strength for composite materials. Figure 1 shows the values for the stress at break. A decrease in stress values at maximum strength is observed with the addition of multilayer, and this decrease is more evident in the composite with 50% reinforcement. In the results obtained for the variation of the elongation at break (%) (Figure 2) there is a decrease for the composite prepared with 10% multilayer, from this formulation an increase in elongation can be observed with the addition of the multilayer film. The addition of filler (aluminum and PET) causes an increase in the stiffness of the composites compared to the pure polymer, so for the composite with 10% multilayer there is an increase in tension and a decrease in elongation at break. For composites with larger amounts of multilayer, the presence of low density polyethylene and linear low density polyethylene from the packaging reduces the stiffness of the composites. As a result of this result, the values of elastic modulus (Figure 3) have significantly increased for the composite with 10% multilayer when compared to the pure matrix, and decreased with the increase in the amount of reinforcement in the composite. This fact indicates that it is possible to obtain a more elastic material with the addition of large percentages of multilayer films in HDPE matrix. These results are explained by the presence of different types of polyethylene in multilayer packaging that have very different mechanical properties. Thus, low values of tension and elastic modulus and high values of elongation presented by LDPE and PELBD make the composites less rigid with the increase in the amount of reinforcement.

The orientation of the polymer chains has a strong effect on the mechanical properties of the polymer. Materials made with highly oriented HDPE, for example, are approximately ten times more resistant than those made from non-oriented polymer, as the orientation increases the packaging of the chains and consequently increases the rigidity of the polymer. When compared to HDPE, PELBD has lower tensile strength and hardness, as the branching content increases, but exhibits greater resistance to impact and tearing (suitable for obtaining films). However, flexion-related properties are not as affected as those related to traction and impact.

The results of impact resistance are shown in Figure 4, where a significant increase in resistance values can be observed in all formulations, and is directly related to the amount of reinforcement material added. The presence

7/8 Aluminum and PET in the reinforcement have a synergistic effect and serve as a barrier to the propagation of cracks. The presence of LDPE also contributes to the increase in impact resistance by acting as an impact energy absorber. With this it was possible to obtain a final material with mechanical properties totally different from those of the initial PE, for example, the significant increase in impact resistance makes this composite suitable for use in situations where this property is necessary, such as bumpers of vehicles.

The morphological analysis of the fracture surface obtained from the impact resistance test indicates the presence of PET and aluminum films. During the grinding, extrusion and injection processes, the separation between PET and Al / PE occurs and in the extrusion stage with PE fusion, it separates from aluminum, so in all mixtures in the composites, the multilayer films appear separate .

Other tests carried out to characterize the material reveal a product with good thermal stability and low water absorption. Environmental degradation tests prove the obtaining of a material of high resistance in the long term, that is, the material maintains its mechanical characteristics even when exposed to the environment (rain, sun, wind) for a prolonged time, which enhances its application in products that demand high mechanical resistance and durability.

The tests were performed with HDPE matrix, however, excellent mechanical characteristics can be achieved using also polypropylene (PP) as a matrix in composites with multilayer packaging.

Conclusion

The process developed, in addition to presenting a solution to a major environmental problem caused by the accumulation of multilayered packaging in dumps and in industries, also makes it possible to obtain a product with potential for application in different branches of industry. In addition, the manufacturing process of the material developed is relatively simple, fast and because it uses post-consumer products or industrial waste as raw material, it becomes extremely attractive from an economic point of view.

Multilayer packaging materials are composed of different resins that are difficult to separate and have the only alternative, so far, incineration with energy use, which generates solid and gaseous waste. This work proposes an alternative for the recycling of this type of material, presented as a result a product

8/8 with excellent mechanical properties and easy application.

The destination given to multilayer packaging of industrial waste as well as domestic waste, so far, is incineration with energy utilization carried out in some European countries, which generates solid and gaseous waste. In Brazil, these packages are stored in industries or thrown in dumps. In the future, with the implementation of this invention and the production of composites, it can be sold from household utensils such as: buckets, basins, clothespins for clotheslines; such as the manufacture of bumpers for cars, since the material obtained has high impact resistance and excellent properties related to traction and flexion.

The present technology has a good chance of success if adopted on an industrial scale. Partly because of the low cost of the machinery used, partly because of its innovative and ecologically correct character; and potentially represents the creation of jobs in associations and cooperatives created to supply the recyclable material industries, from waste pickers to the people involved in sorting the material.

The high strength of the developed material allows its application in the automobile industry, in the production of bumpers, for example, which is a part that requires great impact resistance, as well as the production of internal parts for vehicles. The material can also be applied in civil construction, in the manufacture of tiles, floors, hoses and tubes. Parts for domestic use such as: buckets, basins, fasteners, can also be manufactured from the developed material.

The excellent mechanical characteristic of the material makes it possible to use it in the manufacture of pallets to replace wooden pallets, as it has less weight and does not need to undergo phytosanitary treatment processes. The material also has advantages over the plastic pallets already found on the market, since the cost of the recycled product is much lower, in addition to being more attractive from an ecological point of view.

The excellent characteristics of the composite material discussed previously, such as: impact resistance, elongation, low water absorption and high thermal stability, make it possible to use it to replace PE or PP in the industry in general. Except for the food industry, as it is a material developed from industrial waste or discarded packaging (post-consumption). Thus, the invention now proposed, in addition to presenting a solution to a major environmental problem, is also economically viable and attractive, as it has characteristics that enable its application in several segments.

Claims (3)

1. MECHANICAL RECYCLING OF MULTILAYER PACKAGES containing aluminum, PET and polyethylene in the preparation of composite materials with a polyethylene or polypropylene matrix and multilayer packaging as reinforcement filler, characterized by the following steps: a) wash and dry the packaging; b) grind the packages and the PE or PP matrix in a knife mill; c) Extrude the packages and the matrix of PE or PP in the temperature range of 120 to 180 ° C; d) Form the composite material obtained in step (c) through the injection process. 2. MECHANICAL RECYCLING OF MULTILAYER PACKAGING, according to claim 1, characterized by the manufacture of the composite with a polyethylene (PE) or polypropylene (PP) matrix in the amounts of 10 to 50% load of multilayer packaging. 3. MECHANICAL RECYCLING OF MULTILAYER PACKAGING, according to claim 1, characterized by the replacement of PE or PP in the manufacture of plastic parts in industry in general.