WO2011128746A2

WO2011128746A2 - Product moulded with a mixed heterogeneous polymeric material, relative mix of heterogeneous polymeric material and relative moulding process

Info

Publication number: WO2011128746A2
Application number: PCT/IB2011/000743
Authority: WO
Inventors: Matteo Silvan
Original assignee: Matteo Silvan
Priority date: 2010-04-12
Filing date: 2011-04-06
Publication date: 2011-10-20
Also published as: WO2011128746A3; ITFI20100063A1

Abstract

The present invention relates to a moulded product comprising mixed heterogeneous polymeric material characterised in that it comprises at least two areas distinguishable by at least one mutually different characteristic. In particular, this at least one characteristic is variable from an outer area to an inner area of the thickness and through it, a plurality of diversified layers can substantially be defined. The product is moulded with a mix comprising at least a plurality of the following components, preferably all: PET, PELD, PEHD, PP, PA, ABS, PS, PVC, copolymers.

Description

Product moulded with a mixed heterogeneous polymeric material, related mix of heterogeneous polymeric material and related moulding process

DESCRIPTION The present invention relates to a moulded product made of a mixed heterogeneous polymeric material. The present invention was devised with particular reference to products obtained by moulding heterogeneous polymeric material that is at least partly recycled, more preferably totally recycled. However, it may also be applied to products obtained with non recycled material. If the material is recycled polymeric material, the presence of non polymeric materials, such as paper, wood, metals, dirt, rocks, organic residues, etc., may not be excluded.

The present invention also relates to a mixture of heterogeneous polymeric material for the obtainment of this product and to a related moulding process.

It should be noted that the present invention is applicable to any type of product, of any shape and size. Some non exhaustive examples of application are: pallets, crates, containers and vases, elements for road paving, sewer components, railway sleepers, etc.

The present invention stems from the observation that 50% - 75% of the cost of most of the products on the market today in any industry is conditioned by the raw materials used.

The present invention also stems from the observation that the waste/by-products of polymeric materials, generally highly heterogeneous and with the presence of many types of inert materials, which cannot be processed and are incompatible and not selectable, while non-toxic are, at present, substantially unused. Their disposal takes place only in landfills, by incineration, or by production of solid fuel. Yet these waste/by-products amount to about 2,000,000 Tonnes/year in Italy alone. They are raw materials derived from petroleum, subtracted from the production cycle, with still 75% of the original mechanical characteristics, which in any case are destroyed, with dangerous emissions because of the presence of chlorides/chlorinated compounds from which various types of dioxins are derived, due to incineration at 900°C/1, 000°C and with the emission of C02.

One of the general objects of the present invention is to provide a product comprising heterogeneous polymeric material, for example recycled material, able to provide mechanical performance that is comparable to or better than the corresponding traditional products.

An additional general object of the present invention is to provide a product that is easy and economical to manufacture. In particular, in the case of use of recycled materials, a product whose final cost is lower than that of the corresponding traditional products.

According to a first aspect, the invention relates to a moulded product according to claim 1, i.e. a moulded product containing mixed heterogeneous polymeric material characterized in that it comprises at least two areas distinguishable by at least one mutually different feature.

It should be noted that "heterogeneous" polymeric material means any material comprising a plurality of mutually different polymers (plastic materials) , for example thermoplastic and/or thermosetting, chemically bonded and/or not chemically bonded, etc.

Lastly, it should be noted that a "mixed" material is a material in which the various polymers are mixed together randomly, as may take place for example by grinding the various polymers and mixing them before melting them and injecting them into a mould to obtain a product .

Lastly, a "moulded" product is one whose shape is obtained by means of a mould.

As will be noted, the fact that the product is moulded with a mixture of polymers makes its manufacture very simple and immediate. However, it is necessary to compensate for its heterogeneity, and in this regard it has been intuited that the best solution does not consist so much of implementing a homogeneity process as would seem logical, but rather to control heterogeneity to obtain the desired characteristics of the final product. In particular, the choice of predetermined areas with different characteristics enables, for example, to obtain a specific structural strength, or a particularly attractive surface finish. For example, preferably the characteristic is diversified between an outer area and an inner area in reference to at least one line of thickness of the product .

According to the more easily obtainable embodiments, the at least two areas comprise at least two substantial layers of material.

These layers may have a sharp demarcation line between them, or have a demarcation line that is only ideal because of the progressive change of the at least one characteristic in the passage from one layer to the other. To understand both cases, we speak of "substantial" layers.

Advantageously, the characteristics of the layers are more easily controllable than those of more limited areas, and hence are more easily obtainable with an industrial process.

In general, it is preferable that the at least one different characteristic be at least one among: different composition of the material, different porosity, at least one different property due to the presence of inert materials.

The term "inert" materials here means non polymeric materials, such as rocks, dirt, wood, rags, etc. They can be buried in the heterogeneous polymeric material, which thus serves as a matrix. Their presence is due, for example, to the origin of the polymeric material for recycling.

Preferably, the different composition of the material is due to a different composition of this mixed heterogeneous polymeric material along this at least one thickness, however, additionally or alternatively, there may be at least one layer of mixed heterogeneous polymeric material and at least one layer of material that is different from the mixed heterogeneous polymeric material, such as a coating of virgin finishing material.

For example, the composition is different because of the different percentage of thermoplastic polymers. In this case, it is preferable that the percentage of thermoplastic polymers be greater in proximity and/or at the outer surface of the product. They serve as bonding materials and they enable to "hold together" the whole structure of the product, which otherwise would come apart, for example because of a lack of a chemical bond between other components, the inert ones among them. Among the preferred thermoplastic materials for accumulation in proximity and/or at the outer surface of the product, are included polyolefins. Here, their percentage and/or the percentage of other thermoplastic polymers is preferably greater than or equal to 60%.

In the case of the porosity and of the inert materials, instead, it is possible for example to make their size and/or percentage change from one area to the other. Since they are responsible for a degradation in the structural characteristics of the product, it has been intuited that the best position for most of them, and/or for the part with greater dimension, is at the core of the product. In this way, among other matters, the inert materials are held together by the nobler outer part and do not cause the crumbling of the product . If the mixed heterogeneous polymeric material comprises components that are not chemically bonded together, they preferably include at least one thermoplastic polymer and one thermosetting polymer and still more preferably at least one plurality of the following compounds, preferably all the following compounds: PET, PELD, PEHD, PP, PA, ABS, PS, PVC, copolymers.

According to a second aspect, the invention comprises a mix of recycled polymeric material as claimed in claim 16, i.e. a mix of recycled polymeric material to be used for the moulding of products, characterised in that it comprises at least a plurality, preferably all of the following components: PET, PELD, PEHD, PP, PA, ABS, PS, PVC, copolymers.

According to a third aspect, the present invention comprises a moulding process as claimed in claim 17, i.e. a moulding process for the manufacture of a product comprising mixed heterogeneous polymeric material, characterised in that it comprises the steps of: - preparing a mix of heterogeneous plastic material

- bringing the mix to the molten state

- injecting the molten material into at least one mould until it is filled - at least partly blocking the sliding of at least one area of this molten material relative to the mould during the filling operation.

According to the simplest embodiments, this blocking is achieved by cooling, for example obtained adopting at least one mould whose heat transmission capacity is greater than steel, preferably with a heat exchange coefficient equal to or greater than 150Kcal/h/mt/ °C .

Among the preferred materials for the mould, we include aluminium alloy. According to a preferred general characteristic of the present invention, a first step of filling the mould takes place at a first injection pressure, and a second step of filling the mould takes place at a second injection pressure, different from the first injection pressure.

This promotes the compacting of the heterogeneous polymeric material, and hence the creation of a non- chemical bond between the parts that cannot be chemically bonded to each other. It is observed that the best results are obtained when the second pressure is greater than the first pressure and preferably the latter is applied when the at least one outer layer of this molten material has reduced at least in part, or has lost, its ability to slide relative to the mould, in other words it is preferably applied in association with the aforementioned cooling.

According to another preferred general characteristic of the present invention, gases inside the mould are eliminated during the filling step and very good structural and finishing characteristics are thus obtained. Preferably, at least one portion of gas is eliminated from the molten material even before it is injected into the mould. In other words, it is possible to speak of de-gassing along the entire injection path, including the mould. Since, as stated, the present invention presents its best advantages in association with the recovery of recycled materials, according to the preferred embodiments of the moulding process, the following steps are carried out: - preparing a first mix of material originating from non-separate urban waste collection

- preparing a second mix of material originating from construction site waste and commonly known as "pulper"

- preparing a third mix of material originating from industrial production waste and commonly known as

"polylaminates"

- mixing together the first, the second and the third mix to obtain the mix of heterogeneous plastic material to be injected into the mould. It seems preferable, to obtain excellent results, to monitor the sources of supply of the aforementioned three mixes to ensure that

- the first mix comprises

35-55% PELD

• 20-40% PEHD, PP, ABS . Nylon, PS, PET • 0-10% organic material

• 0-15% of inert materials

• 0-10% paper, cardboard

• 0-10% of PVC. · 0-10% residual moisture

• 0-5% others

- the second mix comprises

• 20-40% paper, cardboard

• 10-20% aluminium film · 35-55% films made of polyolefins, Nylon PET, copolymers

• 0-10% metals

• 0-10% moisture -the third mix comprises PEHD, PP, PET, EVA, EAA, EVOH .

It is also noted that the mix of heterogeneous polymeric material to be injected into the mould that assures the best performance results has been devised; in particular, it is a mix with the following composition of the three above ones:

• 20-50% first mix (urban) ;

• 10-40% second mix (pulper) ;

• 20-60% third mix (polylaminates ) .

In particular, if products with more attractive superficial appearance are to be obtained, it is preferable to adopt the following percentages: 30% first mix (urban) ;

• 20% second mix (pulper) ;

• 50% third mix (polylaminates) .

Whilst for "coarser" products, the following percentages can be adopted:

• 40% first mix (urban) ;

• 30% second mix (pulper) ;

• 30% third mix (polylaminates) .

According to a fourth aspect, the present invention comprises a product made of polymeric material as claimed in claim 31, i.e. a product made of polymeric material, characterised in that it comprises a matrix of heterogeneous polymeric material composed of a plurality of polymeric components, of the porosities and of the inert materials distributed in the matrix, where porosities, inert materials and matrix components are substantially ordered according to predetermined areas based on their characteristics.

Further characteristics and advantages of the present invention shall become more readily apparent from the following detailed description of preferred embodiments thereof, made with reference to the accompanying drawings and provided purely by way of non limiting indication. In these drawings: - figure 1 schematically represents a perspective view of a moulded product according to the present invention;

- figure 2 is a schematic front elevation view according to the plane section II of figure 1 of the product of figure 1; - figure 3 is a schematic view identical to figure 2, where the structure of the material is represented differently by way of example;

- figure 4 schematically shows a view like the one in figure 2 of an alternative embodiment of a product according to the present invention; figure 5 schematically shows a plant for the manufacture of a product according to the present invention . In the remainder of the present description, reference shall be made, for the sake of simplicity, to a product of elementary shape, in particular to bar 1 shown in figure 1, however it must be understood that the present invention is applicable to any shape of moulded product.

The bar 1 is entirely made of mixed heterogeneous polymeric material, for example according to the method illustrated below.

Imagining sectioning the bar 1, according to the plane II, its internal structure, shown in figure 2 is made evident .

The inner structure in particular comprises porosities 5, schematically represented for the sake of simplicity with circles, and inert materials 10, schematically shown for the sake of simplicity with rods, immersed in a matrix 15 of polymeric material. Naturally, those skilled in the art will understand that this representation is purely by way of example, and the shape of the porosities and of the inert materials may vary even considerably from what is illustrated.

It is immediately apparent that proceeding from the outer surface 20 towards the centre 21 of the bar 1, i.e. according to a thickness line, for example the line indicated as S, different concentrations and dimensions both of the porosity and of the inert materials are encountered, where the term "concentration" means the percentage of space occupied (in the case of porosity it is more correct to say the percentage of empty space) relative to the matrix 15.

For example, taking into consideration the outer area 25 and the inner area 26 of the section, it is observed that the dimensions of the porosity and of the inert materials, as well as their concentration, increase passing from the outer area 25 to the inner area 26.

Additionally or alternatively to the four variable characteristics described above, it is observed that another variable characteristic is preferably the composition of the material. In the example of figure 2, the matrix of polymeric material 15 comprises a higher percentage of thermoplastic polymers in the outer area 25 than in the inner area 26. In particular, it has been found particularly interesting to have a percentage of polyolefins in proximity to or at the outer surface 20 that is greater than or equal to 60%, where preferably a percentage up to, or equal to, 35% is low density.

In general, those skilled in the art can understand that the matrix 15 can comprise any mix of polymeric materials, however the present invention was devised with particular reference to the simultaneous presence of at least one thermoplastic polymer and of at least one thermosetting polymer. Still more specifically, the matrix 15 comprises according to the present invention a plurality of components, preferably all, among: PET, PELD, PEHD, PP, PA, ABS, PS, PVC, copolymers.

In the example of figure 2, this structure is met starting from any point of the outer surface 20 and proceeding inwards; for this reason, it is possible to identify at least ideally a succession of layers 30, each with at least one different characteristic with respect to the adjacent layers, as shown in figure 3. In the illustrated example, the border between each layer 30 and the subsequent one is purely ideally, however, the possibility of sharp border is not excluded, this depending on the production process. In general, since both cases are to be included, we speak, as stated previously, of "substantial" layers.

Those skilled in the art shall not, moreover, exclude the possibility for the product 1 to have the aforementioned variation of at least one characteristic along a single thickness line or in predetermined thickness lines, as for example could occur substantially in the case of panels or other products with one or two dimensions greatly exceeding the others. In this case, for example, it is preferable to achieve this variability at least starting from a greater surface area and proceeding towards the interior of the product.

With reference to figure 4, an alternative embodiment of the invention 40 is shown that differs from the one shown in figure 2 in that it comprises a core 45 made of mixed heterogeneous polymeric material and a substantial outer coating layer 50 made of homogeneous polymeric material. Preferably, the core 45 comprises porosities, inert materials and matrix, preferably like the ones of the bar 1 of figure 2, but porosities, inert materials and matrix composition may be totally random, in which case the core 45 can be considered a single substantial layer. The outer material 50 can be, for example, a virgin material, whilst the core 45 can be a recycled material. For the purposes of the present invention, the presence of this coating layer 50 is considered a variation in material composition relative to the core 45. Those skill in the art will understand that although the present example indicates five characteristics that may vary passing from the exterior to the interior of the product 1 or of the product 40 along their thickness, and specifically dimension and concentration of porosities and inert materials and composition of the material, the present invention is not limited to them, contemplating for example also a single variable characteristic, and/or characteristics of a different nature from the one described and/or illustrated. In this regard, it should be noted that the absence of inert materials is not excluded.

With reference now to figure 5, a production plant is shown for the manufacture for example of the product 1 or of other products according to the present invention .

The plant 60 comprises three distinct material transfer areas 62, 63, 64.

These three areas feed material to a mixing/extrusion section 70 where the material is mixed and brought to melting temperature.

The mixing/extrusion section is in contact with an injection section 75, preferably comprising a subsection for the accumulation of the molten material 76. The injection section can be coupled to a moulding section 80 that comprises at least one mould 81 for the manufacture of at least one product, for example the bar 1 of figure 1. The mould 81 is preferably made of a material with high cooling coefficient, such as an aluminium alloy, and/or is cooled artificially, for example by air or water circulation.

A moulding process according to the present inve that uses the plant 60, is described below. In the first area 62 is collected a first mix of material originating from non-separate urban waste collection. This mix contains heterogeneous polymeric material and generally other non polymeric components. It is accepted in the area 62 only if it has the following composition:

• 35-55% low density PELD - polyolefins (for example dirty flexible film - bags - shopping bags etc . ) . · 20-40% of PEHD, PP, ABS, Nylon, PS, PET, (for example bottles, jerry cans, trays made of PS foam, laminates, etc.)

• 0-10% of organic material (for example food residues) . · 0-15% of inert materials (for example metals, wood, rocks, dirt, rags, etc.)

• 0-10% of paper, cardboard, etc.

• 0-10% of PVC (flexible gaskets, windows and doors, etc. ) · 0-10% residual moisture, always present in these kinds of waste

• 0-5% others.

In the second area 63, a second mix of material is collected, originating from construction site waste and commonly known as "pulper". With respect to the material originating from urban waste collection, the pulper is washed, i.e. it does not contain any organic residues like food scraps. This mix is accepted in the area 63 only if it has the following composition:

20-40% of paper, cardboard. 10-20% aluminium film (barrier)

• 35-55% polyolefins, Nylon, PET, copolymer film

• 0-10% metals, in general aluminium/iron

• 0-10% moisture. In the third area 64, a third mix of material is collected, originating from industrial production waste and commonly known as "polylaminates" . These are substantially virgin products, i.e. they have never been used. They are recovered from filming, screen- printing, coupling processes and more in general they are used in the fields of food packaging, pharmaceutics, cosmetics, pesticides/fungicides, catering, etc. In general, they are films of different natures coupled together, for example it is common to find 4 coupled films, respectively made of polymer, paper, cardboard, aluminium. In addition to the film, inks for silkscreen printing and adhesives are also present. In general, they comprise one, preferably more than one, still more preferably all, of: PEHD, PP, PET, EVA, EAA, EVOH.

From each area is drawn a predetermined quantity of related material that is mixed with the predetermined quantities drawn from the other areas and it is blended to form a mix for moulding that preferably comprises · 20-50% first mix (urban)

• 10-40% second mix (pulper)

• 20-60% third mix (polylaminates )

The moulding mix is molten and blended inside the extrusion section, where it also undergoes a first gas elimination operation, called de-gassing.

At this point, the molten and partially de-gassed mix is injected into the mould 81 at a first pressure (low pressure), preferably between 30 and 80 bar. Still more preferably, at a pressure progressively increasing inside this range. In this step, it is preferably to inject up to 95% of the mass necessary to fill the mould.

During the mould filling operation, a second elimination of the gas produced is carried out, for example providing preferably laminar vents in the mould and still more preferably placing the interior of the mould in a vacuum relative to the exterior to attract the gases outside through the laminar vents.

In this low pressure injection step, the molten mass comes in contact with the walls of the mould and undergoes a slow-down in the sliding, and gradual solidification, of the outer layer 30 of the product 1. This causes far more polymers, thermoplastics, and particularly polyolefins to accumulate in the outer layer 30 of the product 1, than in the inner layers. Consequently, the final product has a sort of nobler shell on its exterior and a less noble core in its interior. The material of this shell is well bonded chemically and does not crumble.

The last part of molten mass, preferably about 5% of the volume of the mould, is injected at a higher pressure, for example between 100 and 140 bar. Still more preferably, the pressure has a parabolic final growth .

Lastly, the injection channel of the mould is shut off with a special disjunction valve, which is the subject of another patent application, and the mould thus closed is brought to a cooling area.

The end result is a moulded product 1 that in addition to the outer shell ennobled by the aforementioned massive presence of polyolefins, also has a good superficial finishing and a possible concentration and dimension of the porosities and of the inert materials within its thickness as substantially described above. Naturally, the embodiments and the variants described and illustrated hitherto are purely by way of example and those skilled in the art, to meet specific and contingent needs, may make numerous modifications and variants, such as the combination of these embodiments and variants, all contained within the scope of protection of the present invention as defined by the claims that follow.

Claims

1. Moulded product comprising mixed heterogeneous polymeric material (15) characterised in that it comprises at least two areas (25, 26) distinguishable by at least one mutually different characteristic.

2. Product as claimed in claim 1, characterised in that said at least two areas (25, 26) comprise an outer area (25) and an inner area (26) in reference to at least one thickness line (S) of said product.

3. Product as claimed in any of the previous claims, characterised in that said at least two areas (25, 26) comprise at least two substantial layers of material (30, 50, 45) .

4. Product as claimed in any of the preceding claims, characterised in that the at least one different characteristic is at least one among: different composition of the material, different porosity, at least one different property due to the presence of inert materials.

5. Product as claimed in claim 4, characterised in that the different composition of the material is due to a different composition of said mixed heterogeneous polymeric material (30) along said at least one thickness line (s) and/or to the presence of at least one substantial layer of mixed heterogeneous polymeric material (45) and of at least one substantial layer of material (50) different from the mixed heterogeneous polymeric material.

6. Product as claimed in claim 5, characterised in that said composition is different because of the different percentage of thermoplastic polymers.

7. Product as claimed in claim 6, characterised in that the percentage of thermoplastic polymers is higher in proximity and/or at the outer surface (20) of the product.

8. Product as claimed in claim 6 or 7, characterised in that the percentage of polyolefins is higher in proximity and/or at the outer surface (20) of the product.

9. Product as claimed in claim 6, 7 or 8, characterised in that the percentage of polyolefins and/or of other thermoplastic polymers in proximity and/or at the outer surface (20) of the product is greater than or equal to 60%.

10. Product as claimed in claim 4, characterised in that at least the dimension and/or percentage of the porosity (5) changes .

11. Product as claimed in claim 4, characterised in that at least the dimensions and/or percentage of inert materials change ( 10 ) .

12. Product as claimed in any one of the preceding claims, characterised in that the mixed heterogeneous polymeric material comprises components that are not chemically bonded to each other.

13. Product as claimed in claim 12, characterised in that said components comprise at least one thermoplastic polymer and one thermosetting polymer.

14. Product as claimed in claim 13, characterised in that said components comprise at least a plurality of the following, preferably all of the following: PET, PELD, PEHD, PP, PA, ABS, PS, PVC, copolymers.

15. Product as claimed in any one of the preceding claim, characterised in that it comprises recycled polymeric material .

16. Mix of recycled polymeric material for the moulding of products, characterised in that it comprises at least a plurality of the following components, preferably all: PET, PELD, PEHD, PP, PA, ABS, PS, PVC, copolymers.

17. Moulding process for the manufacture of a product comprising mixed heterogeneous polymeric material, characterised in that it comprises the steps of:

- preparing a mix of heterogeneous plastic material - bringing the mix to the molten state

- injecting the molten material into at least one mould (81) until it is filled

- at least partly blocking the sliding of at least one layer (30) of said molten material relative to the mould during the filling operation.

18. Process as claimed in claim 17, characterised in that said blocking is obtained by cooling.

19. Method as claimed in claim 18, characterised in that said cooling is obtained at least adopting at least one mould with a higher heat transmission coefficient than steel .

20. Moulding process as claimed in claim 19, characterised in that the mould (81) is at least partially made of aluminium alloy^

21. Moulding process as claimed in claim 17, 18, 19 or 20, characterised in that a first step of filling the mould (81) takes place at a first injection pressure, and a second step of filling the mould (81) takes place at a second injection pressure that is different from the first injection pressure.

22. Moulding process as claimed in claim 21, characterised in that the second pressure is greater than the first pressure and it is applied when the at least one outer layer (30) of said molten material has reduced at least in part, or has lost, its ability to slide relative to the mould (81) .

23. Moulding process as claimed in claim 22, characterised in that the second pressure is applied when said at least one layer (30) substantially no longer slides relative to the mould (81) .

24. Process as claimed in any of the claims from 17 to 23, characterised in that during the filling of the mould (81) there is also an elimination of the gases from the interior of the mould (81) .

25. Process as claimed in claim 24, characterised in that at least one portion of gas is eliminated from the molten material even before it is injected into the mould (81) .

26. Method as claimed in any of the claims from 17 to 25 characterised in that it comprises the following steps:

- preparing a first mix of material originating from non- separate urban waste collection (62);

- preparing a second mix of material originating from construction site waste and commonly known as "pulper" (63) ; preparing a third mix of material originating from industrial production waste and commonly known as "polylaminates" (64);

- mixing together the first, the second and the third mix to obtain the mix of heterogeneous plastic material to be injected into the mould (81).

27. Process as claimed in claim 26, characterised in that:

- the first mix (62) comprises

• 35-55% PELD

• 20-40% PEHD, PP, ABS . Nylon, PS, PET

0-10% organic material • 0-15% of inert materials

• 0-10% paper, cardboard

• 0-10% of PVC

• 0-10% residual moisture · 0-5% others

- the second mix (63) comprises

• 20-40% paper, cardboard

• 10-20% aluminium film

• 35-55% films made of polyolefins, Nylon PET, copolymers

• 0-10% metals

• 0-10% moisture

-the third mix (64) comprises

PEHD, PP, PET, EVA, EAA, EVOH.

28. Process as claimed in claim 26 or 27, characterised in that the mix of heterogeneous polymeric material to be injected into the mould has the following composition:

• 20-50% first mix (62);

• 10-40% second mix (63); · 20-60% third mix (64);

29. Process as claimed in claim 28, characterised in that the mix of heterogeneous polymeric material to be injected into the mould has the following composition:

• 30% first mix (62) ; · 20% second mix (63); 50% third mix (64) ;

30. Process as claimed in claim 28, characterised in that the mix of heterogeneous polymeric material to be injected into the mould has the following composition: · 40% first mix (62) ;

• 30% second mix (63);

• 30% third mix (64 ) .

31. Product made of polymeric material, characterised in that it comprises a matrix of heterogeneous polymeric material composed by a plurality of polymeric components, of porosities and of inert materials distributed in the matrix, where porosities, inert materials and matrix components are substantially ordered according to predetermined areas based on their characteristics.