WO2005003216A1

WO2005003216A1 - Process for production of composite agglomerates and products obtained through the process

Info

Publication number: WO2005003216A1
Application number: PCT/PT2004/000018
Authority: WO
Inventors: Luís Manuel DA COSTA CABRAL E GIL; Paulo José CORTICO DA SILVA
Original assignee: Sociedade Nacional De Corticas, S.A.
Priority date: 2003-07-03
Filing date: 2004-07-02
Publication date: 2005-01-13
Also published as: PT102992A

Abstract

The present invention refers to a process for production of composite agglomerates which include in their composition a set of fibres and particles obtained from the fragmentation and/or grinding of waste material, for example, waste material from packages consisting of laminate of one or more metallic layers, one or more paper/cardboard layers and one or more plastic film layers, or similar materials and cork particles, optionally also with inclusion of other materials, preferably without the addition of external binders, but optionally with the incorporation of glues, through pressing and heating during a period of time long enough to get an agglomeration and for the agglomerate to get hard. This invention is preferably applied to waste from used packages but can also be applied to industrial waste. This invention refers also to the new products obtained through this process.

Description

DESCRIPTION

"PROCESS FOR PRODUCTION OF COMPOSITE AGGLOMERATES AND PRODUCTS OBTAINED THROUGH THE PROCESS"

The present invention refers to a process for production of composite agglomerates and in particular a process for the good use of waste materials and cork stoppers .

As waste materials the process of the invention refers, in particular, to residues of beverage packages, namely waste material constituted by laminate of one or more metallic layers, one or more paper/cardboard layers and one or more plastic film layers, or similar materials. This invention also refers to the good use of the residues of the production of these two types of packing materials, i.e., industrial waste of the production of packages of laminate material or similar materials and of the production of cork stoppers.

The most representative laminate packing material is the Tetrapak ^® packing material, which is a complex material that can get different shapes, being usually used as package for beverages for human consumption, for example, milk, juice, wine, dairy cream, etc. and that, as of now, will be designated as Tetrapak-type material or "tetrapak" .

The cork stoppers are generally used to seal alcoholic beverages, either still or sparkling wines, and can be manufactured from natural or agglomerated cork or composed of an agglomerated body and natural cork discs.

The Tetrapak-type material has had, so far, two kinds of post-usage application. The former has to do with its separation into the different components, having the paper fibre obtained been used in the paper recycling industry and the metallic film been directed to specific good uses of similar materials, and lastly the plastic fraction can have an energetic good use or through the current systems of plastic recycling. This separation is, however, complex and expensive to a certain degree. The latter has to do with the production of agglomerates of Tetrapak-type particles, after their fragmentation, through processes known to the experts in the field, being obtained agglomerate plates, somehow stiff, currently used in temporary constructions and in tiles for flooring and / or various partitions and panels and applications of not very high added value .

With regard to the cork stoppers used, it is known that the operation of extraction of the natural or agglomerated corks from the bottlenecks has to be carried out through mechanical devices, the corkscrews, which always cause bigger or smaller deformations that make it impossible to re-use the extracted cork. Besides the uncorking operation, also their adaptation to the bottleneck shape with areas which get wet, or not, through the sealed liquids, makes it so that during their recovery after extraction, the corks lose their regular cylindrical shape, becoming sometimes "twisted" and with trunk-like shapes. Besides these two aspects, it also happens that the corks generally get at least partially soaked in the liquid which they sealed, in the area in contact with it, and they are sometimes in contact with unclean environments, with dirt, moulds, etc. in the spots exposed (upper top) . Thus, the fact that, after extraction from the bottlenecks, the corks show perforations and/or side decay, loose their cylindrical shape and get contaminated, makes it impossible for them to be used again as a seal .

Presently, the only industrial method there is to re-use them is their collecting and subsequent grinding for the manufacture of granulates, and subsequently various cork agglomerates, through methods which are known to the art of processing used corks. In parallel there exists a method also patented, not yet commercially exploited (PT 102013) , which refers to the good use/recycling of natural or agglomerated cork stoppers after uncorking to be used in ways other than sealing, involving the preparation of corks, their gluing top to top, the roughing down / wearing of the rods obtained and eventual finishing operations, products being obtained which are destined to various applications such as pens, pencils, ballpoint pens, handles for cutlery, razor blades, tools and others.

In what concerns cork agglomerates, there exist various types of cork agglomerates in the market . The composite agglomerates are constituted through agglutination of cork particles with different binders (polyurethane, melamine, rubber, etc) from which we obtain products (generally flexible) as diverse as agglomerated cork stoppers, floor and wall coverings, gaskets, etc. The non-composite agglomerates are obtained by means of agglutination of the cork, the binders being the chemical components themselves through the action of overheated steam and pressure, thus being obtained

The expanded cork agglomerate usually used for thermal, sound and vibration insulation.

Besides these cork products industrially produced, there are also those concerning the Portuguese patents PT 88239 and PT 94133, presented here as reference. In the first case some chemical components of cork are chemically depolymerised and then polymerised in the agglomerating operation, acting as natural glues and originating stiff cork agglomerates. In the second case, the cork particles are mixed with thermoplastic particles, which work as binding material in the agglomerating operation, originating stiff composites for various applications. As for the state of the art concerning the object of the present invention, one can still refer to the European patent EP 1048424, which concerns an agglomerate composed of wood particles or fibres and cork particles, but with the use of binders for the agglomerating operation.

There is no reference in the art to agglomerates of cork and Tetrapak-type material. A detailed description of the invention will now be given in a more comprehensive way, which should be regarded as being merely illustrative; the alterations and changes obvious to the experts in the field can also be considered as being within the scope of the invention.

With regard to these methods and to the materials known in the art, it was with surprise that one realized that it was possible to produce interesting composite materials based on urban waste or on industrial Tetrapak- type waste and cork, preferably without the use of additional binders, and possessing a range of characteristics with interest for several applications. As an option, other materials can also be included in the formulations, and/or during the pressing operation a surface (or both) of the agglomerate obtained can be covered with a film of another material, adhering to it.

In a manner of substantiation preferred by the present invention, empty used Tetrapak^® packages, derived from packages of various food products such as milk, juice, etc., were washed and then ground in a mill with rotary knives or similar, until one obtains a material melted into a soft fibrous form and/or under the shape of particles. To this material a certain amount of cork granulate is added, preferably of not very large grain size, from cork dust to a grain size of 1-2 mm, but it can reach higher values. One blends these two materials in a mechanical blender, usually a blender with

Rotary blades, with an adequate rotary speed and for a period of time, which enables a good homogenisation of the blended material. As an option, other materials can also be added, such as agro-industrial waste, in a relative quantity depending on their characteristics. This material is then poured into a mould, pressed and heated in an oven, or rather placed in a press with heated plates (with heating systems known to the experts in the field, like electricity, steam) , with a retention frame, in a layer the thickness of which depends on its formulation, time and pressing temperature. The pressure exerted and the temperature used can vary usually within the range of 5-30 Kgf/cm2, more preferably about 10 Kfg/cm2 and about 100 - 140° C, but, preferably, in the range of 110 -130° C. The closing time of the press, when using a press with heated plates, can generally vary from 5-20 minutes, more preferably, from 5-15 minutes. When using moulds, the agglomerates obtained are left to cool down to room temperature and taken out of the mould. Optionally, at the time of the blending of the cork grains with the Tetrapak- type material particles/fibres, a binder can de added, being its polymerising conditions also conditioning for the operational agglomerating conditions. Also optionally, before the introduction of the layer of mixture to be agglomerated being distributed, one can put in the lower and/or also in the upper part a layer of covering material film (with a decorative and/or protective interest) , for example, cork sheets, wood sheets, etc, which will adhere, after pressing, to the composite obtained in the pressing/agglomerating operation itself. In case the composites do not undergo this latter operation, these can, after being cooled down and stabilized, be covered with films of the mentioned kind by subsequent gluing. The products obtained can also be submitted to finishing operations such as, for example, painting, varnishing, engraving, etc., applied through methods common in the art. There is still the possibility, after the pressing operation and before the cooling down, of moulding the plates obtained in different shapes within the limits of elasticity and breaking point of the material .

The method of the present invention shows as an advantage the following aspects

It enables the usage and valuation of waste materials, although virgin raw-materials can obviously be also used; It uses methods common in the art and can very well be adapted in similar industrial facilities;

The compositions allowed by the process comprise ranges of the cork field: Tetrapak-type material which, on varying in any proportion, give origin to composites with very differentiated characteristics, for multiple applications (higher percentage of cork for more insulating applications, higher percentage of Tetrapak-type material for characteristics of higher stiffness and mechanical resistance) ;

It is possible to incorporate other materials besides cork and the covering with protection/decoration films, thus widening the potential of the products;

The materials produced can replace existing ones, total or partially;

If materials originating from waste are used, the value of the raw-material is very low, with intrinsic economic advantages;

Pieces moulded in different shapes can also be obtained.

Next, some examples of ways of substantiation of the present invention are shown, which should not be regarded as limitations to the same, but only as more concrete ways of exemplifying for better understanding of the present invention. All changes, which are obvious to an expert in the field, are also within the scope of the present invention.

Examples 1 - 21

In the following examples various formulations and operational conditions were used in accordance with Chart no 1. All agglomeration essays were carried out in a JAV press with heated plates (electrical resistance) , with plates in 20 x 20 cm and a metallic frame to accommodate the material to be agglomerated. The mixing was carried out in a JAV blender with horizontal rotary blades, at a rotary speed of about 150 rpm. Some of the parameters which were common to all examples and which are not referred in Chart 1 were :

Pressure = about 10 kgf / cm2 Cork grain size = 1-2 mm Height of the layer of material before pressing = 3 cm Mixing time = 10 min Apparent density of the cork granulate = 50 kg / m3 Apparent density of the ground Tetrapak-type material = 140 kg/m3 Apparent density of the mixture of 50% volume cork / 50% volume "tetrapak" = 102 kg / m3

Apparent density of the mixture 75% volume "tetrapak" / 25% volume cork = 125 kg / m3

CHART 1

The agglomerates in examples 1-21, except that in example 5, were physical-mechanically characterized, according to standardized methods, next described in short, the values of which are summed up in Chart 1.

Thus, the various essays of physical-mechanical characterization of the composites, after previous conditioning at 23 ± 5° C and 50 + 5% HR, during a minimum of 48 h, were carried out in accordance with the procedures defined in the following standards, being always used three beakers in each determination and the results shown being averages of the three values obtained:

❖ Bending test - EN 12089 (distance between supports 125 mm; beakers 175 x 30 mm) ; ❖ Tensile test - NP 2372 (beakers 100 x 50 mm) ; ❖ Apparent density - NP 2372 (beakers 100 x 50 mm) ; ^♦♦^♦ Compression-recovery test - NP 2372 (beakers 100 x 50 mm; indenter diameter 28.7 mm, initial charge 450 g; compression charge 45.5 kg) ❖ Resistance to boiling water - NP 2372 (full immersion; 3 hours) CHART 2

On analysing the results it is verified that these new cork / Tetrapak-type agglomerates show values of shear strength to tension superior (in the range of about 3000 - 7000 kPa) to the traditional composite cork agglomerates ( > 200 to kPa to > 600 kPa according to standard NP - 2372) , showing also superior average values of density, but showing recovery values inferior to the cork gaskets ( > 90% of the initial thickness according to standard NP - 1777) , presenting higher stiffness (also indicated by the shear strength to tension) . If these results are compared to those shown by other competitor products, such as the cork particles agglomerates, the average values of which can be taken, for example, from The Encyclopaedia of Wood, Sterling Publishing, New York, 1989 (Chart 22 - 4) , it is verified that the values of the shear strength to bending are within the values shown by the low density agglomerates, but in what concerns the shear strength to tension these results are similar or superior to those of the low density agglomerates or even to those of high density, depending on the direction.

As an example, essays of thermal conductivity were also carried out for some materials in Chart 1. Thus, the coefficient (λ) of thermal conductivity was measured by using the flux-meter method, with an ANACOM TCA8 device. The formulations in examples 9, 11 and 15 in Chart 1 were tested, plates having been cut in 20 x 20 cm, being these plates stacked to obtain a plate thick enough for the essay. The results were: Chart 3

Examples 22 - 25

The experimental conditions referred for the set of examples 1 - 21 were used, except that polyurethane-type glue was added in a proportion of 10% in weight in relation to the total mass of particles to be agglomerated. The mixture was carried out with 5 minutes only with the particles, more 5 minutes with the glue.

Chart 4

The results obtained in the physical-mechanical characterization effected, as well as in the set of tests referred before, are shown in Chart 5.

Chart

In the first two cases the agglomerates in examples 22 and 23 had better physical-mechanical characteristics and superior density, except at the compression-recovery level, than those equivalent without glue in the first set of products. The examples 24 and 25 showed smaller values of shear strength to tension when compared to the former equivalent ones and, since they contained a larger amount of Tetrapak-type material, they can indicate a smaller mixture and blending of this material with the glue. Nevertheless, generally speaking, the order of magnitude of the characteristics of the agglomerates with glue and without glue is similar.

Example 26

Agglomerate was manufactured under the same conditions as those defined for example 8, except that before the introduction of the material to be agglomerated and after the introduction of the same, films of 2mm-thick cork agglomerate were placed (grain size of about 5 mm) , so as to cover the upper and lower parts of the composite. At the end, the film adhered to the material without the need of an extra operation. This essay was intended only to evaluate this possibility; the product was not characterized from a physical-mechanical point of view. Example 27

An agglomerate was manufactured under the same conditions as those defined for example 8; a plate was obtained, removed under heat after pressing and "wrapped" on a cylindrical mould, where it cooled down to room temperature giving origin to a semi-tubular shape piece.

Claims

1. Process for the production of composite agglomerates which include in their composition a set of fibres and particles derived from the fragmentation and/or grinding of waste material and, additionally, cork particles, characterized by the involvement of the following experimental steps and conditions: a) Washing and drying of the waste material; b) Subsequent grinding of the waste material in a mill or similar until a melted material under a loose fibriform shape and/or particles in the 0.5 - 5 mm range are obtained; c) Grinding of the cork waste in a mill until a cork granulate with a grain size from cork dust to 0.5 - 5mm material is obtained, but which can reach higher values; d) Addition to the ground waste material obtained under b) of a certain amount of cork granulate obtained under a) ; e) Mixture of these two materials in a mechanical mixer, under an adequate rotary speed and for a long enough period of time until a good homogenisation of the material mixed is obtained; f) Introduction of this material in a mould, pressed and heated in an oven or, preferably, placed in press with heated plates with a retention frame, and pressed with a layer the thickness of which depends on its formulation, time and pressing temperature; g) Pressing under a pressure matching the formulation, being this pressure 5 to 30 Kg f/ cm2 , preferably 10 Kfg / cm2 under a temperature of 100 to 140 ° C, preferably from 110 to 130° C and for a period of time of 5 to 20 minutes, preferably 5 to 15 minutes, so that a good agglomeration is obtained; h) Cooling down to room temperature of the agglomerates obtained and their removal from the mould or frame .

2. Process in accordance with claim 1, characterized by the fact that the waste material is constituted by laminate packing material of one or more metallic layers, one or more paper/cardboard layers and one or more plastic film outer layers, by industrial waste of the same material, by agro-industrial waste or by similar materials .

3. Process in accordance with claim 1, characterized by the fact that the cork particles are obtained from cork stoppers, industrial waste from the manufacture of cork stoppers, commercial granulated cork or others .

4. Process in accordance with claims 1 to 3 , characterized by the fact that it is carried out without the addition of external binders.

5. Process in accordance with claims 1 to 3 , characterized by the fact that external binders are added, for example, polyurethane-type glues, urea-formaldehyde, melamine, phenolic glues, etc.

6. Process in accordance with claims 1 and 3, characterized by the fact that step a) can be optional if the waste material is constituted by waste from the manufacture of packing material constituted by laminate of one or more metallic layers, one or more paper/cardboard layers and one or more plastic film layers.

7. Process in accordance with claim 1, characterized by the fact that, before step f) , a film of covering material is placed in the upper and/or lower part, which after the pressing operation will adhere to the composite formed in the pressing/agglomerating operation itself .

8. Process in accordance with claim 1, characterized by the fact that, after step h) , the composites are covered with covering films by subsequent gluing and the products of the process are still subject to finishing operations such as, for example, painting, varnishing, engraving, etc.

9. Process in accordance with claim 1, characterized by the fact that, after step g) , the plates are taken out still hot and placed in contact with different moulds where they cool down and acquire the shape of the same .

10. Products obtained through the process claimed in the previous claims .