Patent Description:
In the present document, the expression "textile reinforcement layer" or "reinforcement layer" or its derivatives is used to indicate a layer consisting of at least one textile yarn arranged on the underlying layer. The "reinforcement layer" is arranged on the load-bearing layer so as to leave portions thereof - generally square, rectangular or rhomboidal-shaped - vacant.

In the present document, the expression "cross-hatched textile layer" or "cross-hatched layer" or "cross-hatching" or its derivatives is used to indicate a layer consisting of at least two yarns or groups of yarns spiral-wound on the load-bearing layer with opposite inclinations and mutually superimposed but not connected. Therefore, a cross-hatching consists of two or more superimposed spirallings.

In the present document, the expression "knitted textile layer" or "knitted layer" or "knitting" or its derivatives is used to indicate a layer consisting of at least two yarns or groups of yarns deposited on the load-bearing layer and connected together to form a plurality of chain stitches, known as "tricot" type stitches.

In the present document, the expression "compatible materials" or its derivatives is used to indicate materials which have mutual chemical and/or physical compatibility, that is materials which, once coupled, give rise to a joint suitable to withstand the transfer of tensile or shear forces through the contact surface. Thus, the maximum compatibility will be observed in identical materials or materials having matrices of the same base.

In the present document, the expression "matrix" of a polymeric material or its derivatives is used to indicate a polymer capable of providing the molecular structure of the finished product.

In the present document, the expression "polymeric material" or its derivatives is used to indicate both the single polymer and a mixture of polymers, for example a blend or a compound.

It is known for example from documents <CIT>, <CIT> and <CIT> that reinforced flexible hoses essentially consist of two parts, a tubular part made of polymeric material and a part made of yarn which forms the reinforcement. Generally, the tubular part consists of two or more layers made of polymeric material, between which the reinforcement yarn is arranged.

Usually, the reinforcement yarn is made of a material incompatible with the polymeric material which forms the part made of polymer. In turn, the materials forming the layers of the polymeric part are not always compatible with each other, a condition necessary for the recyclability of the flexible hose.

However, even in the case of compatible materials of the polymeric part, the incompatibility between the latter and the yarn material requires an operation for separating the two parts for hose recyclability purposes.

This operation is long, expensive and difficult to carry out, which makes recycling of the flexible hose economically inconvenient, even at industrial level as recycling of production waste.

Furthermore, it is basically impossible to separate the yarn from the tubular part of the hose at <NUM>%, this resulting in the fact that the granule of recycled material always contains a more or less high percentage of impurities. As clear, this has a negative impact on the mechanical properties of the hose made of this material.

From <CIT> flexible hose is known made of compatible materials.

The object of the present invention is to overcome the drawbacks outlined above by providing a reinforced flexible hose that is highly effective and relatively cost-effective.

A further object of the present invention is to provide a reinforced flexible hose that is easily recyclable.

A further object of the present invention is to provide a reinforced flexible hose which, once suitably recycled, provides a novel flexible tube having mechanical properties comparable to the original one.

These and other objects which will be more apparent hereinafter, are attained by a method for manufacturing a recycled reinforced flexible hose according to claim <NUM> and by a recycled flexible hose according to claim <NUM>.

Further characteristics and advantages of the invention will be more apparent in light of the detailed description of some preferred but non-exclusive embodiments of the invention, illustrated by way of non-limiting example with reference to the attached drawings, wherein:
<FIG> is a schematic view of a line for the production of the reinforced flexible hose <NUM>.

With reference to the mentioned figures, herein described is a flexible garden hose <NUM> for irrigating flowers, plants or the like. Such hoses are, in a per se known manner, suitable to be connected to a domestic water mains by means of a special fitting, so that the hose transports drinking water from the appliance of the domestic water mains, for example a tap, to the point to be irrigated, for example a garden, a flowerbed or the like.

Although hereinafter reference will always be made to a garden hose, it is clear that the hose according to the invention may be used for any purpose without departing from the scope of protection of the attached claims.

The hose <NUM> includes one or more inner load-bearing layers <NUM>, one or more outer covering layers <NUM> and one or more textile reinforcement layers <NUM> interposed between them.

The inner <NUM> and outer <NUM> layers are made of respective compatible polymeric materials, and preferably they will be made of the same polymeric material.

These polymeric materials are of the thermoplastic elastomeric type, for example TPV, TPE-S, TPE-O or TPE-A.

Preferably, the material of the inner and outer layers <NUM>, <NUM> may be a TPV compound having an EPDM matrix, for example consisting of a mixture of EPDM, polypropylene and paraffinic oil, or a SEBS-based TPE-S compound, for example consisting of a mixture of SEBS, polypropylene and paraffinic oil.

Suitably, the overall Shore A hardness measured according to ISO <NUM>:<NUM> of the materials of the inner and outer layers <NUM>, <NUM> may be comprised between <NUM> ShA and <NUM> ShA in the case of the aforementioned EPDM-based compound and between <NUM> ShA and <NUM> ShA in the case of the aforementioned SEBS-based compound.

If there is a difference between the Shore A hardness of the materials of the inner and outer layers <NUM>, <NUM>, the overall hardness may be measured from the average hardness of the two materials that form such layers, weighted with respect to the weight of the individual layer with respect to the total weight of the layers.

Furthermore, advantageously, the overall melt flow index measured according to ISO <NUM> - <NUM> - <NUM> of the materials of the inner layer <NUM> or of that of the outer layer <NUM> may be comprised between <NUM>/<NUM> and <NUM>/<NUM> in the case of the aforementioned EPDM-based compound and according to ISO <NUM> - <NUM> - <NUM> of the materials of the inner and outer layers <NUM>, <NUM> may be comprised between <NUM>/<NUM> and <NUM>/<NUM> in the case of the aforementioned SEBS-based compound.

On the other hand, the reinforcement layer <NUM> may be made of a fibrous polymeric material and is compatible with the aforementioned materials.

For example, in the case of inner and outer layers <NUM>, <NUM> made of TPV, TPE-S or TPE-O, the reinforcement layer <NUM> may be made of polypropylene, whereas in the case of inner and outer layers <NUM>, <NUM> made of TPE-A, the reinforcement layer <NUM> may be made of polyamide. Suitably, the reinforcement layer <NUM> may have any configuration, for example knitted or braided.

In a per se known manner, as particularly illustrated in <FIG>, the hose <NUM> may be produced by extruding the first polymeric material in a first extruder <NUM> to obtain the inner layer <NUM>, subsequently obtaining the reinforcement layer on the latter in a knitting machine, cross-hatching machine or spiralling machine <NUM> and then by co-extruding the covering layer <NUM> on the output semi-finished product by means of the extruder <NUM>.

Thanks to the compatibility between the aforementioned polymeric materials, the flexible hose <NUM> is ground in a shredder <NUM> of the per se known type, for example TRM <NUM> marketed by CMG Spa, without previously separating the polymeric part of the hose consisting of the inner and outer layers <NUM>, <NUM> and the reinforcement layer <NUM>.

This allows to obtain a ground mixture <NUM> consisting of the materials of the layers <NUM>, <NUM> and <NUM>, which are mutually compatible. Suitably, the flakes may be generally polygonalshaped, for example square or rectangular-shaped, with a greater diagonal dm comprised between <NUM> and <NUM>.

The Shore A hardness measured according to ISO <NUM>: <NUM> of the ground mixture <NUM> may be greater than the overall one of the materials of the inner and outer layers <NUM>, <NUM> of <NUM> Sh A - <NUM> Sh A, and preferably of <NUM> Sh A - <NUM> Sh A.

In a preferred but non-exclusive embodiment of the invention, in the aforementioned example of inner and outer layers <NUM>, <NUM> made of EPDM-based TPV including polypropylene and reinforcement layer <NUM> made of polypropylene, the ground mixture <NUM> will include EPDM and polypropylene, the latter in a greater amount than the amount of polypropylene of virgin TPV.

In this case, the weighted average of the Shore A hardness measured according to ISO <NUM>:<NUM> of the materials that form the inner and outer layers <NUM>, <NUM> may be comprised between <NUM> Sh A and <NUM> Sh A, while the Shore A hardness measured according to ISO <NUM>:<NUM> of the ground mixture <NUM> may be comprised between <NUM> Sh A and <NUM> Sh A.

Still in this case, the melt flow index measured according to ISO <NUM> - <NUM> - <NUM> of the ground mixture <NUM> may be higher than that of the materials of the inner and outer layers <NUM>, <NUM> of <NUM>/<NUM> - <NUM>/<NUM>.

For example, the melt flow index measured according to ISO <NUM> - <NUM> - <NUM> of each of the materials of the inner and outer layers <NUM>, <NUM> may be comprised between <NUM>/<NUM> and <NUM>/<NUM>, whereas the melt flow index measured according to ISO <NUM> - <NUM> - <NUM> of the ground mixture <NUM> can be comprised between <NUM>/<NUM> and <NUM>/<NUM>.

In a further preferred but non-exclusive embodiment of the invention, with inner and outer layers <NUM>, <NUM> made of SEBS-based TPE-S -including polypropylene and reinforcement layer <NUM> made of polypropylene, the ground mixture <NUM> will include SEBS and polypropylene, the latter in a greater amount than the amount of polypropylene of virgin TPE-S.

As schematically illustrated in <FIG>, the ground mixture <NUM> is used as a raw material for making a novel reinforced flexible hose for transporting fluids. Possibly, to this end the ground mixture <NUM> may be suitably added, for example by adding paraffinic oil thereto.

The invention is a method for recycling the production waste of a flexible hose, for example a flexible hose production line in which the discarded flexible hoses are recycled and transformed into raw material for novel hoses.

The ground mixture <NUM> is, as illustrated in <FIG>, cut with blended compatible virgin material <NUM>.

The by weight ratio between the ground mixture <NUM> and the compatible virgin material <NUM> is comprised between <NUM>:<NUM> and <NUM>:<NUM>. Beyond this by weight ratio, the mechanical properties of the polymer obtained would not be suitable for making a flexible hose of the type described above.

In view of the fact that the average industrially acceptable production waste for a flexible hose production line is at most <NUM>%, obtaining a by weight ratio with high amounts of ground mixture <NUM> will require to accumulate a large amount of production waste over several working days.

This obviously requires adequate management of production waste and storage space at the production site.

Therefore, preferably, the by weight ratio between the ground mixture <NUM> and the compatible virgin material <NUM> may be comprised between <NUM>:<NUM> and <NUM>:<NUM>.

This allows to periodically recycle - for example every half working day or at the end of the working day - the production waste of one working day at most without requiring accumulation of production waste and relative management.

The combination of the virgin material <NUM> and the ground mixture <NUM> may form the first polymeric material, as illustrated in <FIG>, and/or the second polymeric material without departing from the scope of protection of the attached claims. In other words, the combination of the virgin material <NUM> and the ground mixture <NUM> may be used to obtain the load-bearing or covering layer of the hose.

In the aforementioned example, in which the virgin material <NUM> is virgin TPV, the ground mixture <NUM> may derive from the grinding of the production waste of TPV hoses as described above.

In order to repeat the aforementioned cycle in a circular economy logic, the novel hose may include a reinforcement layer made of compatible material, for example polypropylene.

The aforementioned characteristics will allow to obtain a fully and easily recyclable hose, simply by inserting it into a shredder <NUM> without a prior operation of separating the reinforcement layer from the rest of the hose.

The obtained ground mixture is used for making new hoses. As clear, this lowers both the costs and the environmental impact entailed in manufacturing the hose.

The invention will be clearer in the light of the following examples.

<NUM> samples measuring <NUM> of hose were prepared using the following raw materials:.

The hoses were made in a per se known manner by extruding the inner and the outer layer by means of an extruder of the per se known type and by forming - on the inner layer - a knitted layer with chain stitches of the tricot type of the NTS® (Samples <NUM> and <NUM>) or DCT® (Samples <NUM> and <NUM>) type by means of a knitting machine of the per se known type.

The percentage weighted distribution in the four samples is:.

The overall Shore A hardness of the materials that form the aforementioned samples <NUM> - <NUM> was measured according to the ISO <NUM>:<NUM> standard by means of a Shore durometer of the ATS FAAR Shore A type.

The overall hardness was measured by calculating the weighted average of the Shore A hardness of the inner layer made of Santoprene® <NUM>-<NUM> (Hardness ShA: <NUM>) and that of the outer layer made of Santoprene® <NUM>-<NUM> (Hardness ShA: <NUM>), both obviously measured according to the aforementioned standard.

The results are reported in table below.

The MFI of the materials that form the tubular layers of the aforementioned samples <NUM> - <NUM> (Santoprene® <NUM>-<NUM> e Santoprene® <NUM>-<NUM>) was measured according to the ISO <NUM> - <NUM> - <NUM> standard using a melt flow tester of the Instron® CEAST Melt Flow Tester MF30 type.

Each of the aforementioned <NUM> samples of hoses was inserted as is into a TRM <NUM> type shredder marketed by CMG Spa and ground, without prior separation of the reinforcement layer from those made of polymeric material. The flakes of the mixture thus obtained were selected using a <NUM> mesh sieve.

For each of the mixtures deriving from the grinding of the aforementioned samples, the Shore A hardness was measured according to the ISO <NUM>:<NUM> standard using the same shore durometer mentioned above.

It is therefore clear that once mixed with the polymeric materials, the polypropylene yarn of the various hose samples significantly increased the Shore A hardness of the mixture.

For each of the mixtures deriving from the grinding of the aforementioned samples, the MFI was measured according to the ISO <NUM> - <NUM> - <NUM> standard using the same melt flow tester mentioned above.

It is therefore clear that once mixed with the polymeric materials, the polypropylene yarn of the various hose samples significantly increased the MFI of the mixture.

The mixtures obtained from the aforementioned <NUM> samples were mixed with virgin Santoprene® <NUM>-<NUM> granules in a <NUM>:<NUM> ratio. Such mixtures of virgin and ground material were extruded to obtain respective load-bearing layers of new samples of <NUM> hoses. Each of these load-bearing layers was inserted into the knitting machine to obtain the aforementioned polypropylene reinforcement layer, and Santoprene® <NUM>-<NUM> was subsequently extruded on the semi-finished products exiting from the knitting machine to obtain the covering layer. The weighted distribution of the new hose samples is the same as that of the aforementioned samples <NUM> - <NUM>.

Basically, <NUM> hose samples were obtained similar to the starting samples both from a quality and mechanical point of view.

In order to ascertain how the mechanical properties of a polymeric material change as the by weight ratio between the ground mixture and the virgin material varies, various samples consisting of Santoprene® <NUM>-<NUM> and the "Sample Mix <NUM>" (SAMP MIX <NUM>) mentioned above were prepared in ratios ranging from <NUM>:<NUM> to <NUM>:<NUM>, as reported in the table below.

The Shore A hardness according to the ISO <NUM>:<NUM> standard using a shore durometer of the ATS FAAR Shore A type, the MFI according to the ISO <NUM> - <NUM> - <NUM> standard using a melt flow tester of the Instron® CEAST Melt Flow Tester MF30 type and the tensile strength according to the ISO <NUM>/ISO <NUM>-<NUM>:<NUM> standard using a dynamometer of the Galdabini brand, Sun <NUM> Model equipped with 25kN load cell and strain gauge with a maximum speed of <NUM>/min were measured for each sample.

The tests show that there is a substantial drop in the mechanical properties of interest as the percentage of SAMP MIX <NUM> increases, showing the greatest difference at <NUM>% of ground mixture.

Claim 1:
A method for making a recycled flexible hose for transporting fluids, the method comprising the steps of:
- providing a ground mixture (<NUM>) obtained by grinding a reinforced flexible hose which includes:
- at least one first load-bearing layer (<NUM>) made of a first polymeric material;
- at least one second covering layer (<NUM>) arranged externally to said at least one first load-bearing layer (<NUM>) made of a second polymeric material;
- at least one reinforcement layer (<NUM>) interposed between said at least one first and one second layer (<NUM>, <NUM>) made of a third polymeric material;
wherein said first and second polymeric material are thermoplastic elastomers, said third polymeric material being a thermoplastic polymeric material;
wherein said first, second and third polymeric material are mutually compatible, so that the flexible hose can be ground without separation between said at least one first and one second layer (<NUM>, <NUM>) and said at least one reinforcement layer (<NUM>);
- extruding a fourth polymeric material comprising said ground mixture (<NUM>) to obtain at least one first layer of the recycled flexible hose;
wherein said fourth polymeric material comprises said ground mixture (<NUM>) and at least one fifth polymeric material (<NUM>) compatible therewith, said fifth polymeric material being a virgin thermoplastic elastomer;
wherein said fourth polymeric material has a weight ratio between said ground mixture (<NUM>) and said at least one fifth polymeric material (<NUM>) comprised between <NUM>:<NUM> and <NUM>:<NUM>.