THEREOF

DESCRIPTION

Field of the invention

The present invention relates to the technical field of flexible hoses, and in particular it relates to a flexible hose for transporting fluids having at least one layer of plasticised PVC, polar polymeric material, and at least one layer of apolar polymeric material mutually coupled to each other, as well as a method for the manufacture thereof.

Definitions

In the present document, the term "matrix" and its derivatives is used to indicate a polymeric material suitable to provide the molecular structure of the finished product.

In the present document, the term "TPE matrix" and its derivatives is used to indicate any resin or mixture of resins containing or consisting of elastomeric thermoplastic polymers.

In the present document, the term "TPU matrix" and its derivatives is used to indicate any resin or mixture of resins containing or consisting of polyurethane thermoplastic polymers.

In the present document, the term "plasticised PVC" and its derivatives refers to a PVC material containing at least one plasticising agent, generally in a weight percentage with respect to the total weight of the PVC material comprised between 15% and 70%.

In the present document, the expression "% by weight" referring to one or more components in a composition of interest is used to indicate the percentage of the dry weight of such one or more components with respect to the total dry weight of the composition.

In the present document, the term "plasticising agent" and its derivatives is used to indicate a compound or a mixture of compounds which can increase the flexibility, processability and extension of the polymer in which it is incorporated. A plasticising agent may reduce the viscosity of the mixture, lower the phase transition temperatures of the second order, and the elastic modulus of the product.

In the present document, the term "stabilising agent" and its derivatives is used to indicate a compound or a mixture of compounds which can intercept small molecules resulting from the degradation of the polymer, for example HCI, to form a more stable intermediate compound. In the present document, the term "pigmenting agent" and its derivatives is used to indicate a substance which, when added to a compound, confers a characteristic colouration thereto.

In the present document, by the term "filler" and its derivatives is used to indicate solid materials made of particles or fibrous, substantially chemically inert, with the function of fillers.

In the present document, the expression "compatible materials" or its derivatives is used to indicate materials chemically/physically compatible with each other, that is materials that, once coupled, form a joint suitable to support the transfer of tractive or shearing forces through the contact surface.

In the present document, the term "compatibilising" and its derivatives is used to indicate the addition of a particular substance or compound to a TPE matrix so as to make the aforementioned TPE matrix and a second material coupled by coextrusion and/or extrusion compatible.

In the present document, the terms "polar/apolar" and their derivatives refer to the adhesion/non-adhesion tendency relating to polymers.

State of the Art

Hoses entirely made of superimposed layers of plasticised PVC are known.

However, such known hoses contain a plasticising agent which tends to migrate over time, thus making the hose rigid and subject to surface breakage. Furthermore, in the event of a PVC layer at contact with liquids, the plasticising agent may migrate into the transported liquid, making it hazardous for human ingestion.

Hoses made of materials comprising at least one layer of plasticised PVC, a polar polymer, and at least one other layer made of TPE, an apolar polymer, coupled to each other are known.

Given that it is known that once coupled polar and apolar polymers tend to delaminate, surface treatments, typically on the apolar materials, are used so as to improve the adhesion between the two types of polymers.

For example, surface chemical treatments on apolar materials having a negative environmental impact are known. Furthermore, they are susceptible of making the hose unsuitable for contact with food substances.

In addition, surface treatments by means of open flame, or high voltage currents, or plasma technology, which however damage the material in terms of functionality and wholeness, are known.

Likewise, the use of hot glues, which - besides being complex to use - however adversely affect the hose manufacturing process.

Summary of the invention

An object of the present invention is to overcome the drawbacks illustrated above by providing a highly efficient and relatively economic flexible hose.

Another object of the invention is to provide a flexible hose that can be obtained in a simple and quick fashion.

Another object of the invention is to provide a flexible hose highly durable over time.

Another object of the invention is to provide a flexible hose that does not contaminate the transported liquid.

These and other objects that will be more apparent hereinafter, are attained by a flexible hose and/or a manufacturing method thereof as described, illustrated and/or claimed herein.

The flexible hose 1 according to the present invention may be useful for transporting any fluid, in particular any liquid for example drinking water.

In particular, the flexible hose 1 may be a flexible irrigation hose or a garden hose for transporting drinking water.

The flexible hose 1 may comprise one first layer 20 and one second layer 10 coupled to each other, as illustrated in particular in FIG. 1.

The first layer 20 may be made of plasticised PVC material, polar polymeric material.

The plasticised PVC material may essentially comprise, in a per se known manner:

- a PVC matrix, for example PVC in suspension, preferably having a factor K according to DIN 53726 comprised between 70 and 100;

- at least one plasticising agent, preferably of the type devoid of phthalates, for example DOTP;

- at least one stabilising agent, for example of the Ca-Zn, Ba-Zn, Ca-organic type;

- possibly one or more additives, for example at least one filler, at least one co stabilising additive, one or more pigments, one or more antioxidants, one or more lubricants, hydrotalcite, one or more UV absorbers, one or more flame retardants.

Suitably, the PVC matrix may be present in the plasticised PVC material in a weight percentage comprised between 20% and 80% with respect to the total weight of the plasticised PVC material, preferably comprised between 30% and 70% with respect to the total weight of the plasticised PVC material, and even more preferably comprised between 40% and 60% with respect to the total weight of the plasticised PVC material.

The at least one plasticising agent may be included in the plasticised PVC material in a weight percentage comprised between 20% and 50% with respect to the total weight of the plasticised PVC material, preferably comprised between 25% and 45% with respect to the total weight of the plasticised PVC material, and even more preferably comprised between 30% and 40% with respect to the total weight of the plasticised PVC material.

In a per se known manner, the at least one stabilising agent of the Ca - Zn type may include calcium stearate, zinc stearate and stearic acid.

Suitably, the least one stabilising agent may be present in the plasticised PVC material in a weight percentage comprised between 0.1 % and 5 % with respect to the total weight of the plasticised PVC material, preferably comprised between 0.1% and 2% with respect to the total weight of the plasticised PVC material, and even more preferably comprised between 0.1% and 2% with respect to the total weight of the plasticised PVC material.

Advantageously, the at least one filler can for example be calcium carbonate.

If present, the at least one filler may be present in the plasticised PVC material in a percentage comprised between 5% and 50% with respect to the total weight of the plasticised PVC material, and preferably comprised between 10% and 20% with respect to the total weight of the plasticised PVC material.

Possibly, the at least one co-stabilising additive may consist of epoxidized soybean oil.

If present, the at least one co-stabilising additive may be present in the plasticised PVC material in a percentage comprised between 0.1% to 3% with respect to the total weight of the plasticised PVC material.

On the other hand, the at least one antioxidant agent may be butylhydroxytoluene, for example of the phenolic or phosphite type.

If present, the at least one antioxidant agent may be present in the plasticised PVC material in a percentage comprised between 0.1% to 2% with respect to the total weight of the plasticised PVC material.

Preferably, the Shore A hardness of the plasticised PVC material, measured according to the UNI EN ISO 868 standard, may be comprised between 50 Sh A and 90 Sh A, and preferably between 60 Sh A and 85 Sh A.

Advantageously, the elongation at break of the plasticised PVC material measured according to the UNI EN ISO 527 standard may be comprised between 350% and 600%.

Suitably, the tensile strength of the plasticised PVC material measured according to the UNI EN ISO 527 standard may be comprised between 12.5 and 17.5 MPa.

For example, the layer 20 may be made of a plasticised PVC material consisting of:

- matrix PVC-S, K 70 100.00 phr;

- plasticising agent, DOTP 58.50 phr;

- stabilising agent, Ca-Zn 1.10 phr;

- co-stabilising agent, epoxidized soybean oil 3.50 phr;

- filler, calcium carbonate 58.00 phr;

- pigment, titanium dioxide R-103 (Dupont) 2.00 phr

The Shore A hardness of such plasticised PVC material measured according to the ISO 868 (48h, 15”) standard may be 79 Sh A.

In order to prevent the plasticising agent present in the plasticised PVC from migrating into the transported fluid, a layer 10, designed to come into contact with the transported fluid, may be formed inside the layer 20.

The second the layer 10 may be made of a second apolar polymeric material consisting of:

(A) from 35% to 75% by weight of an apolar polymeric matrix of the thermoplastic elastomer type, which for example may be TPE-V (EPDM or NBR-based), TPE-S, TPE-O, TPE-E, TPE-A;

(B) From 2% to 50% by weight of a compatibilising agent, such as for example TPU or EAA (Ethylene and Acrylic Acid);

(C) from 0 (that is not present) to 55 % by weight of at least one plasticising agent;

(D) from 0 (that is not present) to 15 % by weight of at least one additive.

The sum of components from (A) to (D) will be equal to 100%. The % by weight specified above is used to indicate the total weight of the mixture of components (A) to (D).

The apolar polymeric matrix (A) may be a copolymer of ethylene with alpha-olefins, for example an Exact™ plastometerfrom ExxonMobil.

The apolar polymeric matrix (A) may consist of repeated units of isotactic propylene with random distribution of ethylene produced using the metallocene catalyst technology, for example Vistamaxx™ high-performance polymer from ExxonMobil.

The presence of the compatibilising agent (B) in the apolar polymeric material will increase the polarisation of the latter, increasing the surface adhesive strength thereof and allowing the coupling of the plasticised PVC material and the apolar polymeric material.

Suitably, the compatibilising agent (B) may be compatible with the apolar polymeric matrix and with the plasticised PVC material.

Advantageously, the plasticising agent (C) may be per se known, for example paraffinic or naphthenic or aromatic oil or of plant origin.

Preferably, the plasticising agent (C) may be present in the apolar polymeric material in a percentage by weight with respect to the total weight of the latter comprised between 0.1% and 40%, and even more preferably comprised between 0.5% and 35%.

Generally, the additive (D) may be present in the apolar polymeric material in a percentage by weight with respect to the total weight of the latter comprised between 0.1% and 12%, and preferably comprised between 0.5% and 10%.

Preferably, the additive (D) may be a stabilising/co-stabilising agent, a pigmenting agent (master based on organic pigments), a filler (calcium carbonate or talc), a release agent (octadecanamide/erucamide).

A mixture of organophosphite and phenolic antioxidant, for example IRGANOX B-225, may be used as stabilising/co-stabilising agent, amounting to 2% to 10% by weight.

In particular, talc can be used as filler, for example amounting to 0.1% - 1% by weight.

Octadecanamide can be used as release agent, for example amounting to 0.1% - 1% by weight.

Preferably, the apolar polymeric material may have a Shore A hardness measured according to the UNI EN ISO 868 standard comprised between 60 Sh A and 90 Sh A.

In addition, the apolar polymeric material may have an elongation at break measured in compliance with ISO 527 standard comprised between 500% and 750%.

Furthermore, the tensile strength measured according to the ISO 527 standard may be comprised between 10 and 15 MPa.

According to a preferred but non-exclusive embodiment, the layer 10 may be made of an apolar polymeric material whose matrix (A) is TPE-S consisting of:

(Al) from 60% to 90% by weight of SEBS; (A2) from 10% to 40% by weight of PP; wherein the sum of components (Al) to (A2) is 100%.

A possible formulation of the apolar polymeric material forming the layer 10 may be:

(Al) from 30% to 50% by weight of SEBS;

(A2) from 5% to 25% by weight of PP;

(B) from 30% to 50% by weight of TPU;

(C) from 0% to 55% by weight of paraffinic oil;

(D) from 0% to 0.5% by weight of talc (filler);

(D) from 0% to 0.5% by weight of octadecanamide (release agent);

(D) from 0.1% to 0.5% by weight of a mixture of organophosphite and phenolic antioxidant.

Another possible formulation of the apolar polymeric material forming the layer 10 may be:

(Al) from 30% to 50% by weight of SEBS;

(A2) from 5% to 25% by weight of PP;

(B) from 2% to 10% by weight of EAA;

(C) from 0% to 50% by weight of paraffinic oil;

(D) from 0% to 0.5% by weight of a mixture of organophosphite and phenolic antioxidant.

According to a first embodiment, illustrated in particular in FIG. 1A, the layer 10 may be a bearing sublayer having a thickness equal to 1 mm - 2 mm and the layer 20 may be a cover layer having a thickness of 1 mm - 2 mm too. In particular, the latter can be grasped by a user.

According to a second embodiment, illustrated in particular in FIG. IB, the layer 10 may be a film having a thickness equal to 0.1 mm - 0.5 mm arranged inside the layer 20 having a thickness of 1 mm - 2 mm.

Likewise, a further third layer 30 of plasticised PVC, superimposed on the first layer 20, which can be grasped by a user may be provided for.

In both the illustrated examples, the layer 10 may be at contact with the fluid to be transported, that is it may be substantially the innermost coating of the hose 1. This will prevent any plasticising agent migrated from PVC from passing into the transported liquid.

Suitably, a reinforcement layer 40 made of PET yarn, interposed between the layer 10 and the first layer 20, in the first described example , or between the latter and the third layer 30, in the second described example, may be provided for.

In particular, the yarn can be a layer of cross-hatched knitted textile reinforcement layer with a linear density according to the BISFA standard chapter 6, equal to 1050 - 1200 dtex, a breaking force according to the BISFA standard chapter 7 equal to 80 - 100 N, a breaking at elongation according to the BISFA standard Chapter 7 equal to 8 - 15 %.

The presence of the reinforcement layer 40 in the first described example, will make the flexible hose 1 resistant to the pressure of the transported water, interfering in a minimum part in the adhesion between the layer 10 and the layer 20 already having an excellent degree of adhesion.

Such hose will have particular resistance to abrasion due to the presence of an outer layer made of resistant material, such as for example plasticised PVC.

According to the first described example, the layer 10 may be obtained by means of a screw extruder 1001 in which the temperature in the cylinder may be comprised between 170°C and 194°C, while the temperature of the head 1001' may be comprised between 180°C and 218°C.

The extruder 1001 may have a flow rate equal to 70 g/m.

In particular, the extruder 1001 may have a ratio between the length and the diameter equal to 24:1, with a diameter equal to 80 mm or 100 mm.

In addition, the screw may have a 2.5:1 or 3:1 compression ratio.

In addition, the screw may be of the standard type with 4 or 5 areas, may have a 3.5:1 compression ratio, as well as an at least 25 L/D (thread length/outer diameter) ratio.

The layer 20 may be extruded by means of an extruder 1002.

In particular, the temperature in the cylinder of the extruder 1002 may be comprised between 155°C and 170°C and it may have a flow rate equal to 56 g/m.

From a manufacturing point of view, as shown in particular in FIG. 4A, the hose 1 may be obtained by means of the production line 1000 by extruding the apolar material in the first extruder 1001 to form the layer 10.

The tubular semi-finished product will then be cooled for a period of time preferably equal to about 15 - 25 s, even more preferably 20 s, by submersion into a tank 4001, for example measuring 300 cm - 400 cm, with water at a temperature of 12°C - 20°C, more preferably 15°C - 17°C, for example 16°C. More particularly, the length of the tank 40 may be such that the hose section which is submerged thereinto instant by instant is about 350 cm.

Preferably, the tank 4001 may be arranged sequentially to the extruder 1001, at a minimum distance therefrom.

The reinforcement layer 40 may be obtained above the layer 10 by means of a knitting machine 2000 to form a cross-hatching or a knitting comprising 25-30 meshes per linear decimetre.

The semi-finished product thus obtained may be subjected to subsequent heating, by insertion into a furnace 5000 comprising subsequent contiguous sections, for example 3-7, preferably 5, to subject the semi-finished product to different temperatures for an overall period of time equal to 4 to 6 seconds.

For example, in the case of a 5-zone furnace with a power equal to 20 kW, the zones may each have a length equal to about 280 mm and the heating may be carried out by means of four infrared resistors surrounding the inner chamber of the oven.

The latter may for example have a circular cross-section, with a diameter equal to 70 mm.

Such progressive temperatures may for example be equal to 350 - 370°C, for example 360°C, in the first two sections, 390 - 410°C, for example 400°C, in the third section, 410 - 430°C, for example 420°C, in the fourth and fifth sections.

In this manner, the surface of the layer 10 and the yarn layer 40 may adhere thanks to the activation of the layer 10 and to a shrinkage, for example equal to 6 - 10%, preferably 8%, suffered by the reinforcement layer 40.

Subsequently, a polar coating layer 20 may be extruded onto the obtained semi finished product by means of the extruder 1002.

A step of cooling for a period of time preferably equal to about 15 - 25 s, even more preferably 20 s, by submersion into a tank 4002, for example measuring 300 cm - 400 cm, with water at a temperature of 12 °C - 20 °C, more preferably 15 °C - 17 °C, for example 16 °C may follow. More particularly, the length of the tank may be such that the hose section which is submerged thereinto instant by instant is about 350 cm.

Preferably, the tank 4002 may be arranged sequentially to the extruder 1002, at a minimum distance from the latter.

According to the second described example, the layers 10 and 20 may be obtained by means of co-extrusion. In particular, a first and a second screw extruder 101, 102 for extruding the apolar layer 10 and the polar layer 20, respectively, may be provided for.

In particular, the extruder 101 may have a ratio between the length and the diameter equal to 24:1, with a diameter equal to 45 mm.

In addition, the screw may have a 2.5:1 or 3:1 compression ratio.

In addition, the screw may be of the standard type with 4 or 5 areas, may have a 3.5:1 compression ratio, as well as an at least 25 L/D (thread length/outer diameter) ratio.

In this manner, the screws of the first and of the second extruder will have a configuration such to extrude respectively the polar layer 20 and the apolar layer 10 with different thicknesses, so that the latter, when coupled - by means of co-extrusion - to the first polar layer 20, is a mere inner coating thereof.

Furthermore, the hose 1 may have an inner diameter equal to 10-16 mm and an outer diameter equal to 16-23 mm.

It is clear that the screw extruders may be single or dual screws without departing from the scope of protection of the attached claims.

In particular, the temperature in the cylinder of the extruder 102 may be comprised between 175°C and 195°C, while the temperature of the head be comprised between 175°C and 216°C.

Furthermore, the temperature in the cylinder of the extruder 101 may be comprised between 170°C and 194°C, while the temperature of the head may be comprised between 180°C and 218°C.

In addition, the extruders 101 and 102 may also have an overall flow rate equal to 70 g/m.

Such temperature ranges will allow to maintain the properties of the materials obtained through co-extrusion substantially intact.

From a manufacturing point of view, as shown in particular in FIG. 4B, the hose 1 may be obtained by means of the production line 100 by extruding the polar material in the extruder 102 to obtain the layer 20, by extruding the apolar material in the extruder 101 to obtain the layer 10 and by co-extruding them to obtain the superimposition of the apolar layer 10 and the polar layer 20.

To this end, in a per se known manner, the extruder 101 may be connected fluidically to the head 102' of the extruder 102. Such tubular semi-finished product will then be cooled for a period of time preferably equal to about 15 - 25 s, even more preferably 20 s, by submersion into a tank 401, for example measuring 300 cm - 400 cm, with water at a temperature of 12°C - 20°C, more preferably 15°C - 17°C, for example 16°C. More particularly, the length of the tank 401 may be such that the hose section which is submerged thereinto instant by instant is about 350 cm.

Preferably, the tank 401 may be arranged sequentially to the extruders 101 and 102, at a minimum distance therefrom.

The reinforcement layer 40 may be obtained above the layer 20 by means of a knitting machine 200 to form a cross-hatching or a knitting comprising 25-30 meshes per linear decimetre.

The semi-finished product thus obtained may be subjected to subsequent heating, by insertion into a furnace 500 comprising subsequent contiguous sections, for example 3-7, preferably 5, to subject the semi-finished product to different temperatures for an overall period of time equal to 4 to 6 seconds.

For example, in the case of a 5-zone furnace with a power equal to 20 kW, the zones may each have a length equal to about 280 mm and the heating may be carried out by means of four infrared resistors surrounding the inner chamber of the oven.

The latter may for example have a circular cross-section, with a diameter equal to 70 mm.

Such progressive temperatures may for example be equal to 350 - 370°C, for example 360°C, in the first two sections, 390 - 410°C, for example 400°C, in the third section, 410 - 430°C, for example 420°C, in the fourth and fifth sections.

In this manner, the surface of the layer 20 and the yarn layer 40 may adhere thanks to the activation of the layer 20 and to a shrinkage, for example equal to 6 - 10%, preferably 8%, suffered by the reinforcement layer 40.

Subsequently, a further polar coating layer 30 may be extruded onto the obtained semi-finished product by means of the third extruder 103.

In particular, the temperature in the cylinder of the extruder 103 may be comprised between 155°C and 170°C and it may have a flow rate equal to 56 g/m.

A step of cooling for a period of time preferably equal to about 15 - 25 s, even more preferably 20 s, by submersion into a tank 402, for example measuring 300 cm - 400 cm, with water at a temperature of 12°C - 20°C, more preferably 15°C - 17°C, for example 16°C may follow. More particularly, the length of the tank may be such that the hose section which is submerged thereinto instant by instant is about 350 cm.

Preferably, the tank 402 may be arranged sequentially to the extruder 103, at a minimum distance from the latter.

The above will be described in greater detail with reference to the following examples which, in any case, shall not be deemed to limit the scope of protection of the invention.

Examples

Example 1 - Examples of formulation of the apolar polymeric material

FIRST FORMULATION

A first sample of apolar polymeric material (Cl) was made using the NILFEX SHA80EC006 material with TPE-S (A) and TPU (B)-based formulation, having the following formulation:

Such formulation exploits the presence of TPU to compatibilise the apolar layer 10 and it is particularly suitable for the production of hoses intended for contact with liquid foodstuffs, for example drinking water, thanks to the presence of SEBS in the layer at contact with the liquid.

SECOND FORMULATION

A further sample of apolar polymeric material having the following formulation was made: The compatibilising agent (B) of this formulation exploits the chemical nature of the resin to facilitate the adhesion between the polar layer 20 made of plasticised PVC and the apolar layer 10.

Example 2: mechonicol properties of the apolar material - first formulation The formulation according to sample Cl was tested for the following mechanical properties:

Example 3 - Examples of formulation and mechanical properties of the plasticised

PVC material

FIRST FORMULATION A first sample (C2) made of phthalate-free plasticised PVC material (TCA/TT 085 B1 CRYSTAL 30 manufactured by Sovere S.p.A.) was produced, with the formulation below:

- PVC-S matrix, K 70 63.71 %;

- plasticising agent, DOTP 33.13 %;

- stabilising agent, Ca-Zn 0.61 %;

- co-stabilising agent, epoxidized soybean oil 2.35 %;

- pigment, black 0.20 %.

The mechanical properties of this sample are as follows:

SECOND FORMULATION

Furthermore, a second sample (C3) made of phthalate-free plasticised PVC material was produced, with the formulation below:

- PVC-S matrix, K 70 49.96 %;

- plasticising agent, DOTP 32.47 %;

- stabilising agent, Ca-Zn 0.47 %;

- co-stabilising agent, epoxidized soybean oil 1.00 %;

- filler, calcium carbonate 15.99 %;

- pigment, black 0.11 %.

The mechanical properties of this sample are as follows:

Example 4A - adhesiveness of the apolar layer and the polar layer

In order to evaluate the mechanical adhesion between the layers of a flexible hose, the aforementioned compounds Cl and C2 were co-extruded to obtain a sample of flexible hose consisting of 0.3 mm inner layer 10 and a 1 mm outer layer 20. An adhesion test according to the EN ISO 8033 standard (peeling test) was carried out on this flexible hose sample.

The mechanical adhesion measured by the peeling test revealed an adhesiveness between the PVC layer (20) and the TPE-S film (10) of 15.5 - 18.4 N/cm.

Example 4B - adhesiveness of the apolar layer and the polar layer

In order to evaluate the mechanical adhesion between the layer 10 made with the compound Cl and the layer 20 made with the compound C3, the adhesion test was carried out on the hose 1, obtained by means of subsequent extrusion of the layers 10 and 20, according to the EN ISO 8033 standard.

The mechanical adhesion measured by the peeling test revealed an adhesiveness between the PVC layer (20) and the TPE-S layer (10) of 10.0 - 12.5 N/cm.

Example 5A - Abrasion resistance

In order to evaluate the abrasion resistance of the hose sample 1 of example 4A above, an abrasion test was carried out on a piece of hose having a length of 1 m, filled with water at a 3-bar internal pressure.

Such hose was dragged on an outdoor floor at room temperature.

In particular, the dragging speed is 2000 m/h, the weight per meter of the water- filled hose is equal to 160 g/m and the covered dragging distance equal to 1000 m.

The sample was then inspected visually by comparing the degree of abrasion with the degrees of abrasion shown in the key of FIG. 2, in which the identified acceptance limit is equal to 4.

The abrasion test was carried out before and after accelerated ageing of the sample, keeping the sample at 80°C for 4 - 8 and 168 hours in an oven at room pressure.

In particular, FIG. 3A shows the hose subjected to the abrasion test after 4 hours at 80°C, while FIG. 3B shows the hose subjected to the abrasion test after 8 hours the accelerated ageing of the sample.

Both results show that the sample has a degree of abrasiveness equal to 5, therefore definable 'non-abraded' according to the key of FIG. 2.

Example 5B - Abrasion resistance

In order to evaluate the abrasion resistance of the flexible hose 1, carried out by means of successive extrusion of the layers 10 and 20, in which the layer 10 is made of the material of the sample Cl and the layer 20 is made of the material of the sample C3, the abrasion test was carried out on a hose having a length of about 1 m, filled with water a 3- bar internal pressure.

Such hose was dragged on an outdoor floor at room temperature.

In particular, the dragging speed is 2000 m/h, the weight per meter of the water- filled hose is equal to 160 g/m and the covered dragging distance equal to 1000 m.

The sample was then inspected visually by comparing the degree of abrasion with the degrees of abrasion shown in the key of FIG. 2, in which the identified acceptance limit is equal to 4.

The abrasion test was carried out before and after accelerated ageing of the sample, keeping it at 80°C for 4 - 8 and 168 hours.

In particular, FIG. 3C shows the hose subjected to the abrasion test 4 hours at 80°C, while FIG. 3D shows the hose subjected to the abrasion test after 8 hours of accelerated ageing of the sample.

Both results show that the sample has a degree of abrasiveness equal to 5, therefore definable 'non-abraded' according to the key of FIG. 2.

Example 6 - bacteriostatic behaviour of the apolar polymeric material

In order to evaluate the bacteriostatic behaviour, i.e. the ability to oppose bacterial growth, of the apolar compound, the microbiological test - method in the attached table - bacterial resistance according to the ASTM E 2149 -IB and ISO 22196:2011 standards, was carried out on sample Cl.

In particular, sample Cl was maintained, respectively at the 2 methods indicated above, at an incubation temperature of 30°C and 37°C for 24 hours, with consequent search for the E. coli - ATCC 25922 bacteria.

Such test found a high resistance of the compound to bacterial growth, giving the following results:

Example 7 - migration tendency of the components of the apolar polymeric material

In order to evaluate the migration tendency of the components of the apolar polymeric material, i.e. the tendency thereof to disperse in aqueous solution at contact, the migration test was carried out on sample Cl, according to the UNI EN 1186-1:2003 and UNI EN 1186-9:2003 standards.

The following table shows the results obtained on 3 samples obtained by means of the formulation of sample Cl, submerged in water, at a test temperature of 23°C at an initial time i _nitiai t and a final time _fmai t after 72 hours.

Such test detected a high resistance of the compound to migration, with ensuing possible use thereof at contact with drinking water.

In this table, the migration value in the indicated simulant (drinking water) is expressed in the amount of substances migrated globally in the simulant unit or per surface. The limits indicated for contact with drinking water by EU Regulation 10/2011 are respectively 10 mg/dm2 and 60 mg per kg of simulant.