WO2009072914A1

WO2009072914A1 - Cork-polymer composite (cpc) materials and processes to obtain the same

Info

Publication number: WO2009072914A1
Application number: PCT/PT2008/000051
Authority: WO
Inventors: Emanuel Mouta Fernandes; Vitor Manuel Correlo Da Silva; José António Marchão Das Chagas; Rui Luís Gonçalves dos Reis
Original assignee: Amorim Revestimentos, S.A.
Priority date: 2007-12-04
Filing date: 2008-12-02
Publication date: 2009-06-11
Also published as: PT103898B; PT103898A

Abstract

The present invention refers to the processes for development of cork polymer composites (CPC) using synthetic, recycled or natural based polymers or blends of these with cork particles or cork waste from the industrial process, which can contain other elements, for example additives and/or compatibilizing agents and/or the raw materials being previously functionalized. The components are mixed in the solid form and further processed, for example in a twin-screw extruder, resulting in pellets that will be subject to a subsequent process, for example compression moulding, injection techniques, among others, in order to obtain materials with different properties comparing with current existent cork products, which could contain or not compatibilizing agents and/or other types of additives in order to facilitate the processing, promote better performance properties or give any additional characteristic.

Description

"CORK-POLYMER COMPOSITE (CPC) MATERIALS AND PROCESSES

TO OBTAIN THE SAME"

FIELD OF THE INVENTION

This invention relates to obtaining composite materials from cork with polymer and the methods to obtain the same. More specifically, the invention presents the mixture of at least two constituents, at least one of them being cork, the constituents allowing being pre-functionalized, resulting in cork with polymer composites called as CPC.

STATE OF THE ART

Cork is the outer bark from a tree, which name is cork oak, of the oak's family

(Quercus suber L.) and presents an anisotropic structure, as shown in Figure 1, of low density, with a high coefficient of friction and impermeability. It presents excellent properties of thermal, acoustic and antivibrating insulation, has a Poisson coefficient around zero and low thermal conductivity, among others, that make it a material of choice for several applications like is described in Gibson L.J. and Ashby M. F., (2001) 2nd ed.: Cambridge University Press. 453-467, or more recently by Suva S. P. et al., (2005) International Materials Reviews, 50(6). 345-365.

On the other hand cork can be regarded as a composite material comprising a mixture of polymer constituents such as cellulose, lignin and suberin where each component has a specific function in the final performance of the material.

The cork industry gets a large amount of wastes from several ending stages of processing like the cutting, grinding and sanding, as well as wastes coming from existing products such as agglomerates, insulation, called cork dusts as referred by Gil L.,

(1997). Biomass and Bioenergy, 13(1-2): 59-61, having different particle size and densities with more or less content of impurities according to the quality and operations to which cork was subjected and which final end is mostly the burning, serving as raw material to feed the boilers in industrial processes.

The mixture between cork and other polymeric materials, particularly the bonding thereof, it is a field with potential to be developed. These are two materials which affinity can be substantially increased, either by superficial modification of one of the components or by use of compatibilizing agents.

There are a small number of patented applications as well as studies related to cork composites. It should be highlighted the patent of Schmidt D., (1983), patent US4373718, reporting applications of thermoplastics with cork applied in hand grips for sport materials; in another patent a study with promising results related to morphological and thermal conductivity level of Barlow CY. et al., (1989) Proceedings of the tenth Rise International Symposium, relates to polymer composites with cork waste using only the technique of extrusion, by extrusion of the material to a mould, which is different of guideline presented in this invention; the international patent of Tesch G., (1993) patent WO9324719, describes cork granules forming the visual layer that are compacted with thermoplastic materials under the action of temperature and pressure for insulation applications; in building construction, in laminated floor where the cork of low density is agglomerated with wood particles through synthetic fibres or thermoplastic material (see Thierry M., et al. (2006) patent FR2873953); on furniture (see Jerome M., (1997) FR patent 2741005) where the agglomerated cork is reinforced during the processing with the addition, for example, of cellulose acetate fibres; in the footwear according to Gianfranco L. (1994) patent IT1244750, where the cork is combined with polyurethanes, or moreover in the area of agglomerated composites, according to Gil L. et al., (2005), international patent WO2005003216, which combines waste from the cork stoppers (after its life time) with recycled material from the tetrapak^* packaging and the addition of compatibilizing agents or glue in materials for packaging; also in materials with potential for application to ceilings, coating for walls, doors or walls panels (see Gil L. et al. (1991), patent PT94133). In the process of the cited document, the cork particles are compacted by the effect of temperature and pressure using thermoplastic materials. Besides the advances proposed in this patent to accomplish the process between lh30m and 2h followed by air cooling during 24 h for dimensional stabilisation, such doesn't happen in the present invention.

Despite several differences comparing with previous process, the present invention uses, besides different processing methodologies, much less material processing and stabilization times when it is necessary use compression moulding, due to the achieving of cork pellets with polymer of natural or synthetic origin at an early stage of the process, which are further used in different processes. Another differentiator factor in the present invention and relating to the compression moulding process, it is that the cooling of the moulding occurs within the mould under the action of water or other refrigerant agent, the mould being or not under pressure, which reduces significantly the stabilization time and provides an excellent surface finishing.

In the field of composite materials, a more recent study proposes simple treatments of boiling cork to increase its thermal stability in order to reinforce the matrix of a thermoplastic material, (see Abdallah F.B. et al., (2006) Journal of Reinforced Plastics and Composites 25 (14), pp. 1499-1506) which is not the case in the method described here, or moreover in the patent of Marti J. et al., (2007) patent EP1803694A1, referring to the potential manufacturing of construction materials including in its base composition a complex mixture of non-recyclable materials with polyethylene, paper, polypropylene, among others, where cork could be present or not in a maximum value of 20% , differentiating itself from the purpose of this invention where the matrix from natural or synthetic origin is combined with cork that is regarded as the principal element of reinforcement due to its unique properties mentioned above.

The combination of cork dust from the industrial process, or the dust of end products with cork, or even of cork granulated, with other polymers from natural or synthetic origin presents a set of potentialities combined with the appropriate processing technology, allowing obtaining structural products with more complex geometries resulting in new potential applications.

SUMMARY OF THE INVENTION

The present invention relates to a process of production of cork polymer composites, characterized by comprising the steps of:

- preparation and mixture of raw materials, composition, cooling and,

optionally, followed by

drying, processing, obtaining the cork polymer composite, mould, - cut and finishing,

wherein

in said step of preparation and mixture of raw materials, these are mixed together in the solid form, in a continuous mechanical mixer, producing an homogeneous mixture,

in said step of composition is used one of the techniques of

pultrusion, at a temperature lower than 200 ⁰C, so as to obtain the half- finished, finished or in pellets form product; or extrusion, at a temperature lower than 200 ⁰C, so as to obtain the half- finished, finished or in pellets form product under mechanical action by at least a mono-screw or twin-screw extruder,

in said step of cooling, the material from said at least one extruder is cooled by exposure to an air stream, a water bath or a cooling liquid and the like,

in said step of drying, it is only removed the excess moisture from said composition step,

in said step of processing is used one of the techniques of

co-extrusion;

extrusion;

compression moulding, in which a mould is placed into a hydraulic arm press and heated up to a temperature lower than 200 ⁰C for a time period lower than 20 minutes, followed of hot pressing for a time period lower than

20 minutes at a pressure between about 196 and 2950 Kpa, finishing with water cooling or other cooling liquid, inside the mould and for 1 - 10 minutes; or

injection moulding, in which pellets are collected in a reciprocating screw which produce the melting of pellets which molten material is injected into a mould and then cooled with water, cooling liquid or the like; by multimaterial injection; injection with pre-composition; or co-injection.

On an embodiment of present invention the process of production of cork polymer composites is characterized by said step of cooling comprises at least one area of conveying rolls. On other embodiment the process of production of cork polymer composites is characterized by, in said compression moulding technique of said processing step, the hot pressing is accomplished at a pressure in the range of about 490 to 1770 Kpa.

On a further embodiment the process of production of cork polymer composites is characterized by, in said mould step, said composites with defect being recycled, sent to a granulator or, again, to said step of composition or to said step of pellets production.

On another embodiment of the invention the process of production of cork polymer composites is characterized by, in said cut step, the excess material is re- granulated and sent to the composition step or to the pellets production step.

Still on further embodiment the process of production of cork polymer composites is characterized by, in said processing step, the mould of said moulding technique has a shape similar to a rim and a thickness equal to that of a final board of said composite.

The present invention also relates to a composite of polymer with cork comprising cork dust, granulate or waste and the like, natural, synthetic recycled polymer or mixture thereof, compatibilizing agents and additives characterized by having a composition comprising about

a) 5% -95% by weight of cork dust, granulate or waste or the like;

b) 5% -95% by weight of natural, synthetic recycled polymer or mixture thereof;

c) 0%-20% by weight of at least one type of compatibilizing agent for improving bonding of phases of produced composite; d) 0%-20% by weight of at least one additive for improving the processability, coloration and the like and for providing UV and/or thermal resistance against abrasion or flame.

On an embodiment the composite of polymer with cork is characterized by said cork constituent and/or said polymeric constituent are functionalized.

On other embodiment the composite of polymer with cork is characterized by comprising any external protection agent applied to other biocide, algaecide, fungicide and/or repellent to water type lenhocellulosic materials and the like.

On a further embodiment the composite of polymer with cork is characterized by its faces allow superficial finishing selected from the group comprising varnish and/or paint coating, adding glues, decorative materials, grinding, rolling, drilling and the like.

The process of the present invention is intended for production of finished products of polymer cork composites.

The process of the present invention is further intended for production of products of polymer cork composites comprising thicknesses of at least 0.5 mm.

The process of the present invention comprises applying compatibilizing agents and/or additives at the polymer cork composite surface either in depth or layered.

The polymer cork composite of the invention is intended for ceilings, floors, footers, doors, and partitions insulation applications, in the field of furniture, automobile engines, in the field of footwear, and the like.

BRIEF DESCRIPTION OF FIGURES

The description of present application is supported by following figures: Figure 1 : Cork morphology according the tangential cross section (a) and according the radial cross section (b) (magnification x 300)

Figure 2: Schematic description of the necessary stages to obtaining cork waste based composites, according to the polymer to be used and the envisaged application.

Figure 3: fracture surface using liquid nitrogen showing the adhesion between the two phases of a CPC composed by Cork + PVC (45-55%) after the process of compression moulding under action of temperature and pressure of the pellets. At low magnifications (of x50 (figure a)) there is observed the two phases present in the composite and at higher magnifications (of x700 (figure b)) there is found the adhesion between the two phases.

Figure 4: The table represents the behaviour of water absorption (%) of boards processed by extrusion, followed by compression moulding, of CPC samples: 1 - Sanding Powder + Recycled Polymer (50-50%), 2 - External Powder -I- PE (49- 49%), 3 - External Powder + PP (49-49%), 4 - Board of PP, 5 - External Powder + PE (49-49%) + cork layer (0.5 - lmm) without the addition of glue.

Figure 5: The table presents the composition of each CPC by weight as well as the tensile mechanical properties: each material modulus at 1 % of strain using linear regression, as well as the maximum stress (σ Max) of the composites processed by compression moulding.

Figure 6: Fracture surface after tensile testing of the CPC: Sanding powder -I- PE (50-50%) (magnifications of X 50 and x700).

Figure 7: The table presents the composition of several CPC by weight, with and without compatibilizing agent, and one mixture of pellets of grinding powder with polypropylene and compatibilizing agent (49-49%) mixed with sanding powder with polypropylene (50-50%), as well as the tensile mechanical properties: modulus of each material at 1 % of deformation using linear regression as well as maximum stress (σMax) of the composites processed by compression moulding.

DETAILED DESCRIPTION OF THE INVENTION

This invention aims the development of composites based on cork or cork waste resulting of the process of cork industry with polymers from natural, synthetic or recycled origin, allowing integrate the normal processes of transformation of several companies from the polymer and cork industry. The described method (based on Figure

2) can be developed in a continuous or discontinuous way and has the following stages:

Stage 1: Raw Materials

This stage consists on the selection of raw materials in accordance with the formulation and the stages required.

At this stage the raw materials from natural or synthetic origin can be submitted to a chemical modification by using alkaline or acid treatments, plasma treatments or corona discharge, to improve the surface characteristics. It can be submitted to functionalization processes, for example with amino groups, epoxy, isocyanates, acrylic acid, anhydrides, methacrylate, phenol, melanin, among others, to promote better adhesion between the cork-polymer constituents as it occurs with other lenhocellulosic materials, or further being submitted to simple operations of washing with one or more solvents, and drying of the cork wastes. As an alternate solution to the functionalization, it will be use previously functionalized polymers. The composite formulation can include:

About 5% -95% by weight of powder or granulated cork with different densities or cork dust from the industrial process known as grinding powder, sanding powder, or from technical products such as the floating powder, among others, or from the mixture of more than one variety of cork waste.

About 5% -95% by weight of polymer from natural origin, synthetic or recycled in accordance with the intended application.

About 0%-20% by weight of compatibilizing agents.

Around 0%-20% by weight of other additives.

Stage 2: Mixture of raw materials

At this stage the raw materials are mixed in the solid form, together, in a continuous mechanical mixer, creating a homogeneous mixture that will feed the stage 3.

Stage 3: Composition

For compounding cork-polymer composites using raw materials, previously functionalized or not, two processing techniques can be used in order to obtain the pellets. Both allow, by effect of temperature and shear stress, to obtain a raw material in which the different constituents of the composite are mixed and bonded. In the process of pultrusion it is possible to obtain directly the product on its semi-final or final shape or in the form of pellets to be further used in other processing processes (extrusion, pultrusion, injection moulding and compression moulding). In the case of extrusion, there is a mono- screw or preferably twin-screw extruder and may be co-rotating or preferably counter- rotating disposed horizontally and/or vertically (one or more extrusion machines) in the process. Moreover, during the extrusion process it will be possible to obtain directly the CPC in the semi-final or final shape, allowing in this case being a profile more or less complex according to the geometry of the extruder die, or in the form of pellets which will be used later in other transformation processes. The reactive extrusion can be used to functionalize the raw materials and simultaneously to allow obtaining the different CPC compositions in the form of pellets or in the form of final product.

Stage 4: Cooling

At this stage, the material only from the extruder , in the form of pellets or in the final form of product, is cooled at room temperature or with the use of a air stream and/or with a water bath and going directly to stage 5, followed or not by an area with rolls, preferably placed near to the extruder die.

Stage 5: Pellets Manufacturing

At this stage the extruded material from stage 4 is grained for obtaining CPC pellets, which will be further send directly to other equipment, for example, for an injection moulding machine.

Stage 6: Drying

At this discontinuous stage of the process, the drying of material (pellets) from the extrusion process is used only to remove the moisture in excess. Stage 7-9: Processing

The stages mentioned here correspond to the use of different processing methodologies to transform the CPC in the final product, which means they are subsequent pellets achievement.

In this stage, extrusion or co-extrusion will be used. The extrusion process is described in stage 3 and can only be applied if the polymer selected in stage 1 allows it. Once again the processing temperatures must be lower than the 200⁰C. As in stage 3, the equipment allows the introduction of additives that can be added to confer a specific property to the final product, such as for example, better mechanical properties, fire resistance among others.

In the compression moulding process, a mould with geometry and thickness according to the intended application can be feed manually, by gravity or through a conveyor belt that is feed continuously. The mould may contain or not in one or both sides a release film, for example a Teflon sheet, comprising the pellets mass homogeneously distributed. The mould, with the amount of material needed in its interior, will be placed in a hydraulic arm press and heated to a temperature lower than 200 ⁰C for a period of time lower than 20 minutes for melting and homogenization of pellets mass and subsequently hot pressed for a period lower than 20 minutes

(preferably the pellets mass should be under pressure from the beginning), at a pressure between 196 and 2950 kPa, preferably between 490 and 1770 kPa, followed by cooling with water, or any other coolant liquid, inside the mould and under pressure during 1-10 min, this period of time allowing to reduce the temperature of the material so as to enable unmoulding it without any kind of damage. Finally the pressure is removed and the small contraction that occurs in the sample allows the easy unmoulding of the composite from the system.

During the placement of the pellets inside the mould, granulated cork without addition of glue can be added in one or both faces of the mould and preferably in a single step, before applying temperature for a short period of time on the mass of the pellets (this mass can be pre-heated to promote an increment on thermal conductivity) followed by a small pressing, in order to create a CPC with one or both faces coated with a cork layer or a film without the addition of glue, the cork granules can be replaced by a decorative sheet, for example a sheet of wood, a sheet of agglomerated cork or natural cork among others.

In injection moulding, the pellets are collected through the feeder or hopper, then falling by gravity into a reciprocating screw that promotes, by action of temperature and shear stresses generated by drag, the melting of the pellets obtained in stage 3 or 5. Then the molten material is injected into a mould with the shape of the desired product, the mould allowing being cooled with water or other type of coolant liquid to quickly lower the temperature of the CPC. Also, could be used unconventional techniques such as multimaterial injection moulding, injection moulding with pre-composition, co-injection, where, in all cases, the processing temperatures should not exceed 200 ⁰C, the equipments configuration, such as in the extrusion process, can be in vertical and/or in horizontal position.

Stage 10: CPC composite

In this stage is obtained a composite material with geometry and structural stability (rigid or more flexible), according to the intended application. The developed composites presents a good bonding between its constituents as shown in Figure 3, good corrosion resistance, reduced water absorption and low thermal and electrical conductivity.

Stage 11: Mould

At this stage and in the case of obtaining a CPC with defects resulting from one or more of the previous processing stages, and the constituents could be subjected to more than one thermal cycle, the latter could be sent to a granulator or to stage 3 or 5 and may be added to process in a certain percentage according to desired final mechanical properties.

Stage 12: Cut

At this stage the CPC is cut according to the desired dimensions and shape and in accordance with the processes of stage 7-9. The exceeded material will be re-granulated and sent to stage 3 or S, which may be added in small amounts in the composition of new CPC.

Stage 13: Finishing

At this stage the composite can be submitted to several operations such as laminating, milling, sanding, drilling, application of a coating, paint, varnish or glue, in which can further be applied compounds that promote thermal, abrasion and ultraviolet (UV) resistance, once the constituents in their composition may have a higher or lower number of chromophore groups, and may suffer photo-oxidation. Although cork is a material with good thermal resistance it may be necessary to increase the resistance of the polymer phase. Still at the finishing stage and according to the final product it may be introduced, among others, a biocide, algaecide, fungicide or a repellent to water.

Stage 14: Product

The resulting product of process called CPC is characterized by presenting an excellent appearance, good chemical resistance, the physical properties includes a good dimensional stability, more or less resilience and low thermal and electrical conductivity, good acoustic properties according to the amount by weight of cork introduced in the initial composition, may have several 2D and 3D geometries, such as, for example, a profile, board, among others, according to the stages of processing and final application. The method described in this invention also allow to obtain 100% natural CPC.

The product presents high potential either combined or not with other materials, can be applied as an insulate element in roofs, floors, footers, doors, partitions, in the field of furniture, in joints for automobile engines, in the field of footwear, among others, through the incorporation of cork in polymer materials. This invention is further explained by the following examples, but these should not be considered as limiting the scope of the present invention.

EXAMPLES

Example 1 :

Experimentally, compositions were prepared using just two materials: polymer- residue. Of the tested residues, some of them are cork residues coming from the industrial process, namely sanding powder, or grinding powder residues, or floating powder residues with density of 150 - 400 kg/m³. The polymer used was polyethylene with melting point of 136.6⁰C (determined by Differential Scanning Calorimetry). For all cases, the polymer/cork dust ratio was equally proportional by weight between the two materials (50/50 %). Before starting the compounding process, each composition was placed separately into a mechanical agitator, for 10 minutes, for mixing and homogenizes both constituents. Each composition was placed alternately into a counter- rotating twin-screw extruder with a die of circular geometry, which allowed the composition and posterior production of pellets thereof, obtaining by this way different formulations of cork powder residues composites with polyethylene (CPC) in the pellet shape.

Afterward, a mass of pellets (about 7Og) from each composition was collected and placed into a similar mould with a rim of rectangular geometry (about 20x23 cm²) and 3 mm of thickness, containing on its base a removable cover over which a Teflon unmoulding sheet was placed in both faces comprising the pellets mass uniformly delivered. This system is placed in a hydraulic arm press at a temperature between 140- 170 ⁰C depending on the type of cork residue used in achievement of pellets, for a period of about 8 min to melting and homogenization of the pellets mass, and further pressed for a 2 min period at a pressure of 1.42 MPa followed by cooling with water inside the mould and under pressure for 5 min, this time allowing to take mass to temperatures near to the room temperature. Finally the pressure is removed and the small contraction that occurs on the board allows the easy unmoulding of composite material from the system.

The boards from the cork composites or CPC so obtained present a thickness of 3 ±0.1 mm and show a brownish colour where the cork particles distributed in the entire surface can be seen, with higher or smaller size according to the type of cork residue used. The boards from the different CPC produced formulations are rigid and present a density of about l ±O.l g/cm³, at room temperature present low water absorption as can be seen in Figure 4. Using these boards, tensile test pieces with standard dimensions were prepared and further submitted to traction at a 5 mm/min speed, obtaining the tensile mechanical properties described in Figure 5. The morphology presented in Figure 6 denotes a good adhesion between the CPC constituents.

Example 2:

The same type of cork residues from example 1 were used and mixed with another thermoplastic material, called polypropylene (PP) with a melting point of 153,2

⁰C (determined by Differential Scanning Calorimetry), in a ratio of 50-50%. The composites were processed according the methodology described on example 1. Boards from different formulations of CPC were obtained showing a surface appearance similar to the composites with polyethylene but with mechanical properties slightly different as shown in Figure 7 due to the use of a different thermoplastic material. Example 3:

The same type of sanding powder residue from the previous example was used to compound in a 50-50% ratio by weight with a polymer made up of a blend of several recycled polymers, obtaining the pellets by the same extrusion process described above and subsequently the board by hot pressing at 150 ⁰C followed by water cooling inside the mould as described on example 1. The CPC board is rigid and has a thickness of 3 ±0.1 mm, presents a surface with a mixture of brownish colours combined with small coloured dots due to different recycled thermoplastic used and dispersed in all the board, also being characterized by possessing a density of about l ±O.l g/cm³, presents a low water absorption at room temperature but a slightly higher comparing to the previous examples described on Figure 4. Regarding to mechanical properties, it presents a modulus at 1% of tensile deformation of 312.3 ± 17.8 MPa and an ultimate tensile strength of 8.6±0.6 MPa, presenting a strain at break of 4.1 ±0.3 % .

Example 4:

The same materials from example 2 were used, but this time in a ratio of 49-49% by weight between both to allow the addition of 2% of a compatibilizing agent to facilitate the mixture and promote the adhesion of the polymeric phase with the cork, obtaining pellets and further boards from the different cork composites formulations

(CPC), following the methodology described on example 1 process. The surface aspect of these composites is similar to the ones of examples 1 and 2 processed with PE and PP. The cork based composites (CPC) processed according to this methodology possess a density of l ±O.lg/cm³, present low water absorption at room temperature as presented in Figure 4, but have better tensile mechanical properties as shown in Figure 7. Example 5:

After obtaining the pellets according to the example 1, 37.5 g of pellets from the grinding powder formulation with PP (49-49%) and 2% of compatibilizing agent were removed and mixed with 37.5 g of pellets from the sanding powder formulation with PP

(50-50%), where were further processed by compression moulding as described on example 1. It was obtained a homogeneous and stiff board from composite material, presenting no significant visual differences and intermediate values of mechanical properties, namely tensile, were obtained relatively to the properties initially presented by each pellets quality, as shown in Figure 7.

Example 6:

A composition of cork granules (0.5-1 mm) and a polyhydroxybutyrate (PHB) with a melting point of 170 ⁰C (determined by Differential Scanning Calorimetry) was used and a composite of 50-50% by weight was prepared by process described on example 1, obtaining a 100% natural CPC board of brownish colour showing at the surface only the agglomerate cork particles and very pleasant to touch. Moreover, the boards produced with this cork based composite (CPC) are stiff and present a density of about 0.95 g/cm³. In terms of tensile mechanical properties, they present a modulus at

1 % of strain of 313.3±32.0 MPa and an ultimate tensile strength of 9.5±0.5 MPa, presenting a strain at break of 5.5±0.6% .

Claims

1. Process of production of cork polymer composites, characterized by comprising the steps of:

preparation and mixture of raw materials, composition, cooling and,

optionally, followed by

drying, processing, obtaining the cork polymer composite, - mould, cut and finishing,

wherein

in said step of composition is used one of the techniques of

pultrusion, at a temperature lower than 200 ⁰C, so as to obtain the half-finished, finished or in pellets form product; or extrusion, at a temperature lower than 200 ⁰C, so as to obtain the half-finished, finished or in pellets form product under mechanical action by at least a mono- screw or twin-screw extruder,

in said step of processing is used one of the techniques of

co-extrusion;

extrusion;

compression moulding, in which a mould is placed into a hydraulic arm press and heated up to a temperature lower than 200 ⁰C for a time period lower than 20 minutes, followed of hot pressing for a time period lower than 20 minutes at a pressure between about 196 and 2950 Kpa, finishing with water cooling or other cooling liquid, inside the mould and for 1 - 10 minutes; or

2. Process of production of cork polymer composites, according to claim 1, characterized by said step of cooling comprises at least one area of conveying rolls.

3. Process of production of cork polymer composites, according to claim 1 , characterized by, in said compression moulding technique of said processing step, the hot pressing is accomplished at a pressure in the range of about 490 to 1770 Kpa.

4. Process of production of cork polymer composites, according to claim 1, characterized by, in said mould step, said composites with defect being recycled, sent to a granulator or, again, to said step of composition or to said step of pellets production.

5. Process of production of cork polymer composites, according to claim 1, characterized by, in said cut step, the excess material is re-granulated and sent to the composition step or to the pellets production step.

6. Process of production of cork polymer composites, according to claim 1, characterized by, in said processing step, the mould of said moulding technique has a shape similar to a rim and a thickness equal to that of a final board of said composite.

7. Composite of polymer with cork comprising cork dust, granulate or waste and the like, natural, synthetic recycled polymer or mixture thereof, compatibilizing agents and additives characterized by having a composition comprising about

a) 5% -95% by weight of cork dust, granulate or waste or the like;

b) 5% -95% by weight of natural, synthetic recycled polymer or mixture thereof;

c) 0%-20% by weight of at least one type of compatibilizing agent for improving bonding of phases of produced composite;

d) 0%-20% by weight of at least one additive for improving the processability, coloration and the like and for providing UV and/or thermal resistance against abrasion or flame.

8. Composite of polymer with cork according to claim 7, characterized by said cork constituent and/or said polymeric constituent are functionalized.

9. Composite of polymer with cork according to claims 7 and 8, characterized by comprising any external protection agent applied to other biocide, algaecide, fungicide and/or repellent to water type lenhocellulosic materials and the like.

10. Composite of polymer with cork according to claims 7 to 9, characterized by its faces allow superficial finishing selected from the group comprising varnish and/or paint coating, adding glues, decorative materials, grinding, rolling, drilling and the like.

11. Use of process of claims 1 to 6, characterized by being intended for production of finished products of polymer cork composites.

12. Use of process according to claim 11 , characterized by being intended for production of products of polymer cork composites comprising thickness of at least 0.5 mm.

13. Use of process according to claims 11 and 12, characterized by comprising applying compatibilizing agents and/or additives at the polymer cork composite surface either in depth or layered.

14. Use the polymer cork composite of claims 7 to 10, characterized by being intended for ceilings floors, footers, doors, and partitions insulation applications, in the field of furniture, automobile engines, in the field of footwear, and the like.