Process for the production of tubes of plastic material reinforced with armour

Abstract

It is disclosed a process for the production of tubes of plastic material reinforced with armour comprising at least one dipping step into a first polymer blend of a first forming means and at least one dipping step into a second polymer blend of a second forming means in order to obtain a first sheath of plastic material and a second sheath of plastic material, respectively, which are subsequently assembled together with a perforated armour arranged therebetween for obtaining an assembly, wherein said assembly is subjected to hot lamination and subsequent cooling; the tube of plastic material reinforced with armour thus obtained and related applications in the medical- surgical and biomedical field are also disclosed.

Description

[0001] Title: Process for the production of tubes of plastic material reinforced with armour

[0002] DESCRIPTION

[0003] Field of application

[0004] The present application is directed to the field of tubes of plastic material reinforced with armour or armored tubes.

[0005] In particular, the present application relates to a process for the production of tubes of plastic material reinforced with armour and to tubes thus obtainable, as well as to their applications in the medical- surgical and biomedical fields.

[0006] Prior art

[0007] Armoured tubes are characterized by a metal core immersed inside the wall of the tube; based on the type of armour that will be used the so- called braided tubes or coiled tubes can be obtained.

[0008] The braided tubes are characterized by the presence of a metal mesh (or a tangle of meshes), generally of stainless steel, which gives the tube mechanical performances that are not obtainable with tubes without metal mesh: internal pressure resistance, torsional resistance and resistance to the phenomenon called “kinking” significantly increase if inside the wall of the tube a metal mesh is inserted. Moreover, the presence of a metal mesh allows drastically reducing the thickness of the wall of the tube, with the consequent possibility of having a smaller external diameter (less bulk and invasiveness) and a greater internal diameter (greater flow rate).

[0009] “Kinking phenomenon” means the phenomenon that leads to a reduction in the flow rate of a tube (liters / minute) further to a bending of the tube. If a metal spiral or coil is inserted instead of a metal mesh, then the tube is called coiled tube. The coiled tubes are characterised by an excellent bending resistance (or kinking phenomenon), low wall thickness (high internal diameter and small external diameter) and an excellent resistance to external and internal pressure.

[0010] In the fields in which the tube must undergo extreme bending or must resist internal depression or pressure, external pressure or depression, or it is necessary to minimize the size of the tube (smaller external diameter) or optimizing the output (flow rate) of the tube (greater internal diameter), the use of coil-armoured tubes is required (coiled tubes).

[0011] Similar applications can be provided for tubes reinforced with a metal mesh (braided tubes).

[0012] Both the industrial field, more generally, and the medical field benefit from this technology (in particular the technology of the coiled tubes) for the most technical applications that require particularly extreme performance.

[0013] In particular, in the fields of medical devices, coiled tube technology is used in minimally invasive surgery. Indeed, the blood circuit has curves that could not be travelled by a conventional tube, i.e. one without armour, whereas by using an armoured tube it is possible to reach points where extreme flexibility and at the same time resistance to the kinking phenomenon are essential for the success of the surgical intervention.

[0014] Macro areas of the medical field, such as ECC (extra corporeal circulation), ECMO (extracorporeal membrane oxygenation) and in general minimally invasive interventions (use of catheters and microcatheters), require the use of armoured tubes, for instance coiled tubes, in order to ensure the required flexibility, the minimum size, the maximum flow rate and at the same time resistance to the kinking phenomenon.

[0015] The production of coiled tubes has been happening for about 50 years and are mainly made of PVC.

[0016] Over the last 15-20 years, there have been attempts at a regulatory level, to limit the use of PVC both in the industrial field, more generally, and in the medical field since PVC is listed among the toxic substances that the European Union has decided to ban from the market by 2030.

[0017] The need to provide a tube of plastic material reinforced with armour, as well as said armoured tube, which overcomes the above mentioned limits with reference to the prior art is therefore particularly felt in the field.

[0018] As a result, the technical problem underlying the present invention is to provide a tube reinforced with armour made of an impeccable material from the point of view of compatibility with applications in the medical- surgical and biomedical fields, or more generally in which the release of toxic substances into the fluids in contact with it during the application of choice is minimized, and that it also has high resistance to internal or external pressure, resistance to torsion and resistance to the “kinking” phenomenon without causing an enlargement of the external diameter or a narrowing of the internal diameter of the tube.

[0019] Summary of the invention

[0020] The present invention solves the above technical problem through the process for the production of tubes of plastic material reinforced with armour comprises the following steps: a) providing a first forming means (otherwise identifiable as internal former, since it is adapted to the formation of the internal wall of the tube) and a second forming means (otherwise identifiable as external former, since it is adapted to the formation of the internal wall of the tube), wherein said first forming means (or internal former) and said second forming means (or external former) have a longitudinal extension and are adapted to be set in rotation about a longitudinal axis, said first forming means extending along a longitudinal axis of first forming means and having a section of first forming means having a width of first forming means and said second forming means extending along a longitudinal axis of second forming means and having section of second forming means having a width of second forming means, said width of first forming means being less than said width of second forming means; b) immersing said first forming means into a first polymer blend comprising a first polymeric material and a first solvent, said first polymeric material being dissolved in said first solvent, so as to bring said first forming means into contact with said first polymer blend, and subsequently extracting the first forming means from said first polymer blend, wherein during dipping and extraction the first forming means is set in rotation, determining the adhesion of a first thin layer of said first polymer blend on said first forming means; c) drying or letting dry said first thin layer of first polymer blend, thus obtaining a first sheath of plastic material and tubular in shape; d) immersing said second forming means into a second polymer blend comprising a second polymeric material and a second solvent, said second polymeric material being dissolved in said second solvent, so as to bring said second forming means into contact with said second polymer blend, and subsequently extracting the second forming means from said second polymer blend, wherein during dipping and extraction the second forming means is set in rotation, determining the adhesion of a second thin layer of said second polymer blend on said second forming means; e) drying or letting dry said second thin layer of second polymer blend, thus obtaining a second sheath of plastic material and tubular in shape; f) performing an assembly step, arranging a perforated armour between said first sheath of plastic material and said second sheath of plastic material and obtaining a tubular- shaped assembly comprising a first sheath of plastic material, a second sheath of plastic material and a perforated armour arranged therebetween, said perforated armour being provided with through-holes; g) subjecting said tubular- shaped assembly to a moisture removal operation; h) once moisture removal step g) has been performed, heating said tubular-shaped assembly to the point of at least partial fusion of said first sheath of plastic material and / or of said second sheath of plastic material, so as to let a portion of said first sheath of plastic material and / or of said second sheath of plastic material flow through the through-holes of said perforated armour; and i) cooling said tubular- shaped assembly, thus obtaining a tube of plastic material reinforced with armour.

[0021] Preferably, the first polymer blend corresponds to the second polymer blend or the first polymeric material of said first polymer blend corresponds to the second polymeric material of said second polymer blend.

[0022] In particular, in the tube of plastic material reinforced with armour obtained in cooling step i) said plastic material is monolithic, i.e. actually made as a single piece, and said perforated armour is completely immersed in said plastic material.

[0023] Preferably, the perforated armour is a net (or mesh), a spring (or spiral), a perforated hypotube or any combination thereof.

[0024] According to the present invention, the expression “perforated armour” indicates an armour whose structure is made of a net, a coil or a perforated hypotube, i.e. having holes or openings from side to side throughout its development, in other words said holes or openings correspond to the free through-spaces and delimited by the meshes of the net or by the coils of the spring or by the structure of the hypotube, which is commonly seamless.

[0025] In other words, as it will be seen hereinafter, the term “perforated armour” indicates a reinforcement, an armour or any component of a tubular nature, possibly of metal material, which has holes or perforated through-areas, such as to allow the sheath or polymeric layer which tops the armour to come into contact with the underlying sheath or polymeric layer.

[0026] Said perforated armour may be a spring or wired coil. In this case, the area that allows the contact between the outside and the inside is represented by the space between two subsequent coils.

[0027] Alternatively, in the case of a net, made up of wires braided and / or welded to each other, the perforated through-area that allows the contact between the outside and the inside is represented by polygons or quadrilaterals formed by the intersection of wires.

[0028] Finally, in the case of hypotubes the area that allows the contact between the outside and the inside is represented by the through-holes or through-slots, which are optionally obtained by laser cutting and / or die cutting.

[0029] In particular, the net or spring that constitutes the perforated armour itself may develop into a plurality of wires or in a single wire seamlessly, respectively.

[0030] Therefore, according to a first embodiment, the net that constitutes the perforated armour itself develops into a plurality of wires joined together so as to form the net’s meshes. More specifically, the wires of said plurality of wires are joined together through welding and / or turn up to be braided with each other to form the net’s meshes.

[0031] Preferably, the net is constituted by a plurality of metal or polymeric wires (for instance of nylon), more preferably welded and / or braided together.

[0032] According to an alternative embodiment, the spiral or spring which constitutes the perforated armour itself develops in a single wire seamlessly and wrapped up on itself, so as to form the coils of the spring.

[0033] Preferably, the spring (or spiral) is metallic, more preferably it is constituted by a single metal wire.

[0034] Advantageously, said first polymeric material and said second polymeric material are arranged to minimize the release of toxic substances into the fluids with which the reinforced tube comes into contact under normal environmental conditions of application and, in particular, they are impeccable from the point of view of compatibility with applications in the medical- surgical and biomedical fields.

[0035] Preferably, said first polymeric material and said second polymeric material are not polyvinyl chloride (PVC) or in any case the first and second polymer blend are free from polyvinyl chloride (PVC).

[0036] Preferably, said first and said second polymeric materials may be selected from silicone, SEBS, polyisoprene or a thermoplastic elastomer.

[0037] More preferably, said first and said second polymeric materials are a thermoplastic elastomer, in a wholly preferred way said thermoplastic elastomer is a thermoplastic polyurethane (TPU) or a polymer blend comprising thermoplastic polyurethane.

[0038] Still more preferably, the thermoplastic polyurethane may be aromatic polyurethane or aliphatic polyurethane.

[0039] Advantageously, polyurethane is particularly preferable especially for applications in the field of medical devices, since polyurethane has a very high biocompatibility, thanks to the absence of plasticizers and / or phthalates that can be released into the body during use of the medical device.

[0040] Furthermore, polyurethane is particularly suitable for the processes that are carried out during the aforementioned assembly step f) and has a mechanical resistance greater than all of the other elastomerized polymers.

[0041] Equally advantageously, the reinforced tube of plastic material obtainable through the process according to the present invention has a high resistance to internal or external pressure, resistance to torsion and resistance to the phenomenon of “kinking”, without causing an enlargement of the external diameter or a narrowing of the internal diameter of the tube.

[0042] In other words, with the same internal and external diameters, a tube made through the process of the present invention has improved mechanical properties compared to a tube made of the same plastic material, but without armour, and even compared to a tube made of the same plastic material and produced by extrusion or moulding.

[0043] Indeed, the process according to the present invention allows making the various components useful for the execution of assembly step f) with high precision.

[0044] Therefore, consistently, the process according to the present invention does not use extrusion processes in order to ensure the maximum precision of the semi-finished products useful for the execution of assembly step f) and necessary for the production of the reinforced tube of plastic material thus obtained. Preferably, the solvent in said polymer blend is tetrahydro furan.

[0045] Advantageously, the solvent-based blend can be formulated in such a way that it can be used in a dipping process, i.e. during dipping steps b) and d), which allows obtaining thin layers of polyurethane quantified in a way proportionate to the result and the required application.

[0046] More preferably, the solvent in said polymer blend is THF, still more preferably anhydrous THF, in particular anhydrous THF > 99.9% inhibitor-free.

[0047] Said solvent has features which make it preferable for applications in the medical- surgical and biomedical fields, so as not to leave potentially toxic residues in the semi-finished products produced.

[0048] Moreover, thanks to the dipping process and advantageously with respect to alternative technologies known in the field which involve heating the polymer blend for making and forming the tube, the process of the invention allows avoiding the formation of carbon black spots since the polymeric material does not degrade and there is no thermal or mechanical stress.

[0049] Preferably, dipping step b) and / or step d) may be repeated at least twice, respectively.

[0050] Specifically, when dipping step b) and / or step d) are repeated at least twice, each dipping step is separated from the subsequent dipping step by an intermediate rest step performed for a pre-set time and at room temperature.

[0051] In other words, according to a specific embodiment and as it will be seen hereinafter with reference to the detailed description and to the figures, it is possible to immerse a first sheath of plastic material into the first polymeric solution for a plurality of times, so as to obtain a first multi-layered and tubular- shaped sheath of plastic material. Analogously, it is possible to immerse the second sheath of plastic material into the second polymeric solution for a plurality of times, so as to obtain a second multi-layered and tubular- shaped sheath of plastic material.

[0052] It is thus possible to make semi-finished products, i.e. the tubularshaped assembly obtainable during assembly step f), with a pre-fixed internal diameter, which does not vary according to the just described embodiment since it is consistent with the width of the cross section of the internal former, but different form the external diameter, determined by a different overall wall thickness.

[0053] According to a specific embodiment, it is possible to make the internal sheath by a plurality of dipping steps b) and to make the external sheath by performing a plurality of dipping steps d).

[0054] Preferably, according to the latter embodiment, the external sheath and the internal sheath are made of the same plastic material.

[0055] Alternatively, the single layers that make up the internal and external sheaths are made of a plastic material of a different chemical nature or different mechanical and / or rheological features. In particular, it is possible to make layers of aromatic polyurethane (mechanically very high-performance and chemically very resistant to acids and bases) alternating with layers of aliphatic polyurethane (more flexible and transparent) .

[0056] According to the present invention, the expression “room temperature” indicates a temperature comprised between 18 and 25°C, specifically between 18-21 °C.

[0057] More preferably, in the intermediate rest step the above-mentioned preset time has a duration between 10-20 minutes, still more preferably between 12-15 minutes.

[0058] Advantageously, in this way it is possible to create a reinforced tube of plastic material, even using a different polymeric material, from layer to layer, depending on the applications required.

[0059] In particular, the first and the second polymer blends are stored in suitable containers, i.e. containment tanks, where the first forming means and the second forming means are immersed and extracted, respectively.

[0060] More particularly, the containers where the first and the second polymer blends are stored are made of glass, stainless steel or polytetrafluoroethylene (PTFE).

[0061] In particular, it is possible to make the forming means with a constant or variable section, thus creating, by way of example, armored tubes with variable section, if necessary for the final application.

[0062] For instance, as it will be illustrated hereinafter in connection with the detailed description and the figures, forming means having a variable section along their longitudinal extension may be used.

[0063] According to a specific embodiment, said first forming means has a first section of first forming means having a first width of first forming means and a second section of first forming means having a second width of first forming means, wherein said first width of first forming means is greater than the second width of first forming means.

[0064] Meanwhile, said second forming means has a first section of second forming means having a first width of second forming means and a second section of second forming means having a second width of second forming means, wherein said first width of second forming means is greater than the second width of second forming means.

[0065] More preferably, said first section of first forming means and said second section of first forming means are joined together by an intermediate section of first forming means having a conical perimeter extension. Meanwhile, said first section of second forming means and said second section of second forming means are joined together by an intermediate section of second forming means having a conical perimeter extension.

[0066] Consistently with the specific embodiment described above, the first and the second sheaths thus obtained during steps c) and e) have a section variable along their own longitudinal extension.

[0067] In other words, the first sheath thus obtained during step c) has a first section of first sheath having a first width of first sheath and a second section of first sheath having a second width of first sheath, wherein said first width of first sheath is greater than the second width of first sheath.

[0068] Meanwhile, the second sheath thus obtained during step e) has a first section of second sheath having a first width of second sheath and a second section of second sheath having a second width of second sheath, wherein said first width of second sheath is greater than the second width of second sheath.

[0069] Consistently with the specific embodiment described above, the tube of plastic material reinforced with armour obtained in step i) has a first tube section having a first tube width and a second tube section having a second tube width, wherein said first tube width is greater than the second tube width.

[0070] Specifically, the first tube section is placed in the distal direction, whereas the second tube section, whose width is less than that of the first tube section, is placed in the proximal direction.

[0071] According to the present invention, the term “proximal direction” indicates a portion of tube which, in the conditions of application of the same, is designed for contact or approach to the patient, whereas the term “distal direction” indicates a portion of tube, opposite the above proximal direction, which is arranged for contact or interaction with a healthcare professional or with an equipment operated by a healthcare professional.

[0072] Preferably, as it will be illustrated hereinafter in connection with the detailed description and the figures, the first tube section, placed in the distal direction and having a first tube width, may be made of a plastic material different from the second tube section, placed in the proximal direction and having a second tube width, less than the first tube width.

[0073] The armored tube described above can also be made using two different polymeric materials to make the first tube section and the second tube section, respectively.

[0074] In other words, the first and the second forming means may be first of all immersed in the distal portion into a so-called material 1, then, once an intermediate drying step has been performed, they can be turned upside down and subsequently immersed into a so-called material 2, different from material 1, thus obtaining a first sheath of polymeric material and a second sheath of polymeric material made, each of them, of two different materials.

[0075] Preferably, the forming means may be made of metal, more preferably of steel, still more preferably stainless steel.

[0076] Advantageously, the use of metal and preferably steel as a material for the formers allows acting as a heat reservoir, useful for heating and lamination step h), as it will be seen later.

[0077] Preferably, in particular when said first polymeric material and said second polymeric material are a thermoplastic elastomer, more particularly thermoplastic polyurethane (TPU) or a polymer blend comprising thermoplastic polyurethane, the first forming means and the second forming means are covered with an insoluble material in the first solvent and / or in the second solvent used during dipping steps b) and d), respectively, more preferably the first forming means and the second forming means are covered by a fluorinated polymer, still more preferably said fluorinated polymer being selected from polytetrafluoroethylene (PTFE), FEP, PVDF, PP, or PE.

[0078] In a completely preferred way, according to the present invention it is therefore possible to use both “Teflon-coated” formers, which have undergone a surface deposition process of PTFE (or coating), and formers coated with a heat- shrinkable PTFE tube.

[0079] Preferably, during the extraction operations of the first and second forming means during steps b) and d), respectively, the first and the second forming means are set in rotation at a speed comprised between 5 and 20 rpm.

[0080] Advantageously, by adopting said speed during the extraction and ascent operation, it is possible to ensure a high concentricity of the thin layers thus obtainable.

[0081] As implicit, for making a tube of armoured polymeric material according to the process of the present invention, it is necessary to make an internal layer of the tube and an external layer of the tube, inside which the perforated armour of steel (coil and hypotube) will be present.

[0082] Preferably, in assembly step f) the perforated armour has an armour section having an armour width having an intermediate value and comprised between the width of said first forming means and the width of said second forming means.

[0083] Preferably, the interference between the internal diameter of the perforated armour and the diameter of the thin internal layer may vaiy from 0. 1 mm to 0.5 mm, more preferably from 0.2 mm to 0.3 mm.

[0084] Advantageously, said interference allows positioning the spring, automatically or manually, preventing air from remaining between the perforated armour and the thin internal layer.

[0085] In an equally preferred manner, said perforated armour is made of metal, preferably stainless steel. As said, preferably said perforated armour is in the form of a perforated mesh, of a spiral or a hypotube.

[0086] Once all the necessary components are made available, i.e. the first thin sheath of plastic material (internal) and the second thin sheath of plastic material (external), as well as the perforated armour, assembly step f) is performed.

[0087] Preferably, assembly step f) comprises the following sub-steps:

[0088] - inserting said perforated armour onto the first sheath of plastic material;

[0089] - optionally, immersing said first sheath of plastic material and said perforated armour thus inserted thereon into a further solvent, the plastic material being at least partially miscible in said further solvent, for a pre-set time;

[0090] - optionally, extracting said first sheath of plastic material and said perforated armour from the solvent and diying said further solvent;

[0091] - inserting said second sheath of plastic material onto the perforated armour thus coupled to the first sheath of plastic material, thus obtaining said tubular- shaped assembly.

[0092] Preferably, in the dipping sub- step said pre-set time is comprised between 1 second and 2 minutes, preferably between 2 seconds and 10 seconds.

[0093] Preferably, during the dipping sub- step said further solvent coincides with said first solvent and / or with said second solvent, more preferably said solvent is tetrahydrofuran.

[0094] Advantageously, by immersing the first sheath of plastic material and said formed armour thus inserted thereon into a further solvent and subsequently drying the latter, it is possible to improve the adhesion features between these two components, prior to fitting the second sheath of plastic material onto the perforated armour and then performing subsequent lamination step h).

[0095] More preferably, said second sheath of plastic material has a longitudinal extension and a section of second sheath having a width of second sheath such that, when the second sheath is inserted onto the perforated armour thus coupled to the first sheath of plastic material, there is a gap between said second sheath and said perforated armour thus coupled to the first sheath of plastic material, wherein said gap has a transversal dimension comprised between 0.5- 1.5 mm.

[0096] According to a specific embodiment, when the perforated armour is a net, during lamination step h), said second sheath of plastic material is subjected to tension.

[0097] Tensioning can be imposed by applying a force with a value between 0.1 N and 5 N.

[0098] In particular, said force value may be modified and modulated based on the thickness of the external sheath.

[0099] In a completely preferred way, during the above assembly step f) in the sub-step of inserting said perforated armour onto the first sheath of plastic material, said first sheath of plastic material is laid on said first forming means.

[0100] Optionally, when the perforated armour is a net, in the above mentioned assembly step f) and prior to the sub-step of inserting said second sheath of plastic material onto the perforated armour thus coupled to the first sheath of plastic material, the following further substeps are performed:

[0101] - immersing the first forming means into a third polymer blend comprising a third polymeric material and a third solvent, said third polymeric material being dissolved in the third solvent, and subsequently extracting the first forming means from said third polymer blend, wherein during dipping and extraction the first forming means is set in rotation, thus determining the adhesion of an additional thin layer of polymer blend on said perforated armour thus coupled to the first sheath of plastic material;

[0102] - drying or letting diy said additional thin layer of polymer blend, thus obtaining the perforated armour coupled to the first sheath of plastic material and covered by an additional sheath of plastic material.

[0103] Preferably, said third polymer blend corresponding to the second polymer blend or the third polymeric material of said third polymer blend corresponds to the second polymeric material of said second polymer blend.

[0104] More preferably, said third polymeric material is a thermoplastic elastomer, in a completely preferred way said thermoplastic elastomer is a thermoplastic polyurethane (TPU) or a polymer blend comprising thermoplastic polyurethane.

[0105] Advantageously, by subjecting the second sheath of plastic material to tensioning, for instance by applying a constant force in the direction of the sheath’s extension or by hanging a weight on the sheath itself in the vertical position, since during lamination step h) the second sheath is brought to the softening point of the plastic material which makes it up and thus undergoes an elongation, a general narrowing of the section width of the second sheath is caused, second sheath which adheres to the additional sheath of plastic material and / or to the underlying perforated armour thus coupled to the first sheath of plastic material.

[0106] According to an alternative embodiment, when the perforated armour is a spring (or spiral), in the above mentioned assembly step f) and during the sub-step of inserting said second sheath of plastic material onto the perforated armour thus coupled to the first sheath of plastic material, after the insertion of the second sheath of plastic material, a sheath made of heat- shrinkable material is inserted onto the latter, thus obtaining a tubular- shaped assembly comprising said first sheath of plastic material, said perforated armour, said second sheath of plastic material and said further sheath of heat- shrinkable material; and, subsequently to cooling step i), said further sheath of heat- shrinkable material is removed from the tube reinforced with armour thus obtained.

[0107] Preferably, said sheath of heat- shrinkable material is a polyolefin sheath.

[0108] In this way, during lamination step h), the heat- shrinkable sheath of plastic material narrows and adheres to the underlying second sheath of plastic material, the latter in turn adhering to the underlying perforated armour.

[0109] The contact of the second sheath of plastic material with the perforated armour, due to the heat transmitted to the innermost layers of the tubular-shaped assembly and thanks to the through-holes of the armour, determines the contact between the material that constitutes the second sheath and the one that constitutes the first sheath, thus obtaining - further to cooling - a monolithic structure.

[0110] Preferably, lamination step h) is performed by making said tubularshaped assembly thus assembled during previous step f) pass through a thermostatic laminating head and applying, gradually along its longitudinal extension, a hot air flow on said tubular- shaped assembly.

[0111] Advantageously, through the lamination process it is possible to fuse the external layer with the internal layer, i.e. namely the first sheath with the second sheath.

[0112] According to the present invention, the term “lamination” indicates the procedure during which the passage of said tubular-shaped assembly occurs, in particular with at least the external layer, the perforated armour and the internal layer mounted on the internal forming means, in a high temperature area with air flow capable of releasing heat (calories) to the internal former and to the internal and external layers deposited or fitted thereon.

[0113] Preferably, when the first polymeric material and the second polymeric material are a said thermoplastic elastomer, in particular thermoplastic polyurethane (TPU) or a polymer blend comprising thermoplastic polyurethane, in lamination step h) said tubular- shaped assembly is heated at a temperature comprised between 180°C-210°C.

[0114] Preferably, during lamination step h) the internal forming means may be made to rotate according to a speed comprised between 2 to 10 rpm.

[0115] Advantageously, in this way it is possible to determine a greater symmetry in the former’s heating.

[0116] Preferably, during moisture removal step g) from the tubular- shaped assembly obtained in previous assembly step f), the moisture of the assembly is brought to a value less than 800 ppm (0.08% w / w on the total weight of the tubular- shaped assembly), more preferably less than 500 ppm (0.05% w / w of water on the total weight of the tubular- shaped assembly), still more preferably less than 200 ppm (0.02% w / w on the total weight of the tubular- shaped assembly).

[0117] Preferably, said step i) is carried out further until room temperature is reached and / or subsequently to cooling step i) the following steps are performed: j) removing the tube of plastic material reinforced with armour from said first forming means; k) keeping the tube of plastic material reinforced with armour at room temperature, preferably for a time period of at least 24 hours.

[0118] The above technical problem is also solved by a reinforced tube of plastic material obtained according to the process of the invention above described.

[0119] The present invention also relates to the use of the above mentioned reinforced tube of plastic material in the medical- surgical field, in particular to its use as a catheter.

[0120] The above technical problem is thus solved by a catheter made with the reinforced tube of plastic material according to the present invention.

[0121] The present invention thus also relates to the use of the above described reinforced tube of plastic material for making biomedical equipment.

[0122] Indeed, the present invention is particularly suitable to the field of application of catheterisation, i.e. tubes that can perform a medical or surgical function inside the body using the venous and arterial blood system as entry and passage routes of the catheter. Indeed, this is a field that requires extreme guarantee and precision of the coiled tube, both in terms of dimensions and in terms of the mechanical performance required.

[0123] The tube of reinforced polymeric material according to the present invention is optionally a coiled tube.

[0124] More preferably, the tube of reinforced plastic material of the present invention has a pitch having a value comprised between 30-40 turns / inch.

[0125] Advantageously, by decreasing this value the mechanical contribution linked to the internal armour (coil) decreases with the decrease of the turns / inch parameter.

[0126] According to a particular embodiment, it is possible to alternate parts of the coil and hypotubes to create different points of emission or injection of liquids along the armored tube thus made.

[0127] In an equally preferred manner, the tube of reinforced plastic material of the invention has a cross section width or diameter (when it is a tube with a spherical cross section) comprised between 3 mm and 30 mm.

[0128] Preferably, the perforated mesh, possibly in the form of a net or spring, comprising a plurality of wires welded together or a single wire seamlessly, wherein said wire or the single wires which make up said plurality of wires welded together, has a diameter (if the reinforced tube has a circular cross section) comprised between 0.1 mm - 0.5 mm, more preferably between 0.2 mm - 0.4 mm, or a width comprised between 0.2 mm - 0.6 mm, more preferably between 0.1 mm - 0.3 mm (if the reinforced tube has a rectangular cross section).

[0129] Preferably, when the perforated armour is a spring, the wire that makes up the spring may have a thickness comprised between 0.1 mm and 1.0 mm, more preferably between 0.1 and 0.5 mm, when the wire that makes up the coil has a rectangular cross section; when the wire that makes up the coil has a circular section, its diameter may be comprised between 0.1 mm and 1.0 mm, more preferably between 0.1 and 0.5 mm.

[0130] Preferably, when the perforated armour is a hypotube, the hypotube may have a wall thickness comprised between 0.05 mm and 0.5 mm, more preferably between 0. 1 and 0.5 mm.

[0131] Finally, the present invention relates to a biomedical equipment comprising the above described reinforced tube of plastic material, preferably said biomedical equipment being designed for performing ECC (extra corporeal circulation) or ECMO (extracorporeal membrane oxygenation) .

[0132] Brief description of the drawings

[0133] Figure 1 shows a schematic representation of a cross-section of the armoured tube. The section of the wall extremely reduced compared to the diameter of the armoured tube is made of a polymeric internal layer and of a polymeric external layer, comprising a metal armour to provide mechanical properties that cannot be achieved by a tube without armour.

[0134] Figure 2 shows a representative example of a former having a cylindrical variable section constituted by a distal part and a proximal part, connected by a conical part. The ends of the former are conical to ensure a better fluid dynamics of the former in the dipping step into the fluid solution. In the represented case, the distal part has smaller diameter and greater length compared to the proximal part. This allows meeting numerous needs in the medical field, being able to make armoured tubes with variable geometry. In the case of figure 2, the distal part will allow the formation of the invasive part (part of the device that enters the body through veins or arteries). The proximal part (larger) may act as a handle, clamping point (closing the flow) and / or connection to the extracorporeal circuit for, for instance, blood oxygenation pumps. The possibility of making armoured semi-finished products with variable geometry in a single process allows avoiding assembly, gluing and welding steps between the distal part and the proximal part.

[0135] Figure 3 shows the dipping step of the former into the viscous solution composed of solvent and polymer at least partially soluble in said solvent.

[0136] Figure 4 shows the extraction step of the former from the viscous solution.

[0137] Figure 5A shows a longitudinal sectional view of the hardware (lamination head) required for the lamination step. The former, in axis with respect to the lamination head, moves relative to the lamination head with a linear speed that is a function of the diameter of the former’s section. The thermostatically controlled hot air, radially exiting from the lamination head toward the former, releases calories to the polymeric layers that coat the internal former. Figure 5B shows a cross sectional view of the hardware (lamination head) .

[0138] Figure 6 shows the cross section of the semi-finished product obtained following the lamination process according to a first embodiment, wherein the perforated armour is a spring.

[0139] Figure 7 shows an embodiment of the process according to which it is possible to make a semi-finished product made of two different materials. Indeed, it is possible for the distal part to have mechanical features different from the proximal part. By reversing the direction of the former, it is possible to create distal and proximal parts that are different from each other in terms of both material and thickness.

[0140] Figure 8 shows an embodiment of the process according to which it is possible to make semi-finished products with the same internal diameter but different external diameter (different wall thickness). It is possible to make semi-finished products of a single material but with different mechanical features (based on the thickness) .

[0141] Figure 9 shows the cross section of the semi-finished product obtained following the lamination process according to a second embodiment, wherein the perforated armour is a metal mesh, obtained by braiding metal wires. It is worth noting the additional TPU layer needed to increase the contact surface with the external sheath.

[0142] Detailed description

[0143] It is now described, according to some of its embodiments, a process for preparing a reinforced tube of plastic material according to the present invention.

[0144] The reinforced tube of plastic material according to these embodiments is made of thermoplastic polyurethane. Lubrizol products were used, in particular aromatic polyurethanes from the Pellethane 2363 series. This code is accompanied by USP Class VI biocompatibility certification.

[0145] In addition to the Pellethane 2363 series, other commercially available polyurethane granules may be used, as exemplified in other passages of the present disclosure.

[0146] In particular, according to the present invention, thermoplastic polyurethane granules with medium and / or low molecular weight may be used.

[0147] More particularly, the thermoplastic polyurethane used according to the present invention has a weight average molecular weight (Mw) between 50000 and 200000 Da, still more particularly between 90000 and 180000 Da, in a completely preferred way between 110000 and 140000 Da.

[0148] The weight average molecular weight (Mw) is calculated using the gel permeation chromatography (GPC) technique, using THF as the elution solvent.

[0149] The measurement is conveniently performed using the ISO 13885-1 (2020) experimental method.

[0150] Advantageously, the dissolution of medium / low molecular polyurethanes in the solvent allows obtaining a polymeric solution that is easily processable in accordance with the application provided by the present invention.

[0151] The process described is based on the preparation of semi-finished products starting from viscous solvent-based polyurethane solutions.

[0152] The chosen solvent is tetrahydrofuran (THF) since it allows obtaining homogeneous solutions with stable viscosity, with a high evaporation percentage that allows not to have toxic residues in the final semifinished products.

[0153] The process allows obtaining coiled or braided tubes, optionally multilayered, with variable flexibility.

[0154] The process described below requires preferential environmental conditions to obtain coiled or braided tubes free from systematic defects related to temperature and humidity conditions.

[0155] The evaporation process and the miscibility between water (air humidity) and solvent (in particular, THF) may require temperature and humidity ranges that allow a controlled and stable evaporation of the solvent (in particular, THF).

[0156] Temperature range: 18-21°C, preferably 19-20°C;

[0157] Humidity range: 25-40 % HR, preferably 30-35 % HR.

[0158] For making coiled tubes for the medical field, it is preferable to carry out the production in a controlled environment in a clean room, so that airborne particles do not negatively affect the final product.

[0159] In the catheterization field it is also often necessary to have holes along the armored tube in order to allow liquids (or gases) to enter or exit the armored tube. Indeed, this possibility is not precluded by the present procedure.

[0160] In these cases, it is necessary to use thin steel tubes (hypotubes), from a few millimetres to a few centimetres long, which have holes made mechanically or by laser.

[0161] The use of a hypotube may be provided in combination with a coiled tube or with a braided tube.

[0162] From said holes, liquids (or gases) can be expelled or taken from the coiled tube or braided tube. During the assembly step, the positioning of said additional metal components may occur automatically, by using completely conventional dedicated machines (winders) already present on the market or manually, by inserting the metal parts onto the first polyurethane layer, which may advantageously be placed onto the internal former.

[0163] For instance, should the hypotube be used in combination with a spring (or spiral) or with a perforated net, first of all, a first portion of spring or perforated net can be placed on the first sheath; consecutively, the hypotube can be placed; finally, consecutively, a second portion of spring or perforated net can be placed.

[0164] Optionally, additional portions of spring or perforated net and additional portions of hypotube may be positioned, one after the other along the longitudinal extension of the first sheath and depending on the desired final application.

[0165] It is necessary to fix the components to the polyurethane substrate so that they cannot move during the following processing steps.

[0166] In particular, the positioning of the coil must occur respecting a parameter relating to the coil pitch. Said parameter is described by the number of turns / inch. Said parameter affects the resistance to bending of the coiled tube; the greater the value of turns / inch, the greater the resistance of the coiled tube to bending (kinking resistance) .

[0167] The metal reinforcement (coil) can be made up of either a round section metal wire or a square section metal wire.

[0168] The internal diameter of the armour (coil and hypotube) must have a certain dimensional interference with the substrate of TPU (internal layer) :

[0169] Internal diameter of the coil (or hypotube) = diameter of the internal former + internal layer - interference In any case, the wall thickness of the tube of plastic material reinforced with armour according to the present invention may be comprised between 1 / 12 and 1 / 8, preferably between 1 / 11 and 1 / 9, of the width of the overall cross section of the tube (external diameter of the armoured tube).

[0170] Looking at Figure 1, a cross-section of the armoured tube 100 is shown. The section of the wall, extremely small compared to the diameter of the armoured tube 100, is made up of an internal layer of plastic material 101 and an external layer of plastic material 102, between which a metal armour 103 is placed, which is completely immersed in the plastic material that constitutes the internal and external layers.

[0171] Figure 2 shows a representative example of a former having a cylindrical variable section consisting of a distal part la and a proximal part lb, connected by a conical part 1c. In the case shown, the distal part lb has a smaller diameter and a greater length than the proximal part 1c.

[0172] Figure 3 shows the dipping step of the former 1 into the viscous solution composed of solvent and polymer at least partially soluble in such solvent. Arrow A indicates the direction of the dipping movement of the former 1.

[0173] Figure 4 shows the extraction step of the former from the viscous solution. Arrow B indicates the direction of the extraction movement of the former 1. Arrow C indicates the rotation direction of the former 1 , while it is being extracted.

[0174] Figure 5A shows a longitudinal section view of the lamination head used for the lamination step. The former, in axis with respect to the lamination head, is inserted into the lamination head and moves relative to the lamination head with a linear speed that is a function of the diameter of the former’s section. Double-headed arrow D indicates the relative movement of the former. Arrows E indicate the movement of air toward the assembly.

[0175] Figure 5B shows a cross sectional view of the lamination head used for the lamination step. The thermostatically controlled hot air, radially exiting from the lamination head toward the former, releases calories to the polymeric layers that coat the internal former. Arrows E indicate the movement of air toward the assembly 10.

[0176] Figure 6 shows the cross section of the semi-finished product obtained following the lamination process according to a first embodiment, wherein the perforated armour 103 is a spring. The internal layer 101 and the external layer 102 fully enclose the perforated armour 103.

[0177] The internal former 1 is covered by a layer of thermoplastic polyurethane, whereas the external layer 102 is still covered by a heat- shrinkable sheath of polyolefin material, before it is removed.

[0178] Figure 7 shows an embodiment of the process according to which it is possible to make an armoured tube made of two different materials. Indeed, it is possible for the distal part to have mechanical features different from the proximal part lb. By reversing the direction of the former, it is possible to make the distal part la and the proximal part lb different from each other both in terms of material and thickness.

[0179] For instance, a 500 mm long coiled tube of polyurethane can be made: a portion of 100 mm may be made of Pellethane 80-AE (low flexural modulus) orienting the spindle in a first direction during the dipping step, whereas the opposite portion of 400 cm may be made of Pellethane 55-DE, orienting the spindle in the opposite direction during the dipping step.

[0180] In this way, it is possible to obtain a coiled tube with 400 mm of reduced flexibility and 100 mm of flexible tip. In this way, the coiled tube thus obtained is easily orientable and maneuverable (rigid part), whereas the 100 mm tip is veiy soft to be able to bend easily in an atraumatic manner (if inside the human body).

[0181] Alternatively, a 500 mm long coiled tube of polyurethane can be made: a 250 mm portion can be made of Tecoflex EG 80A (veiy high flexibility) by orienting the spindle in a first direction during the dipping step, whereas the opposite 250 cm portion can be made of Pellethane 90-AE by orienting the mandrel in the opposite direction during the dipping step.

[0182] In this way, it is possible to obtain a coiled tube with 400 mm of high flexibility and chemical resistance and 100 mm of soft and extremely flexible tip.

[0183] It is possible to obtain a coiled tube that is extremely atraumatic and can reach extreme bends on one side and is chemically resistant to acids and bases on the other, in addition to excellent resistance to abrasion.

[0184] Figure 8 shows an embodiment of the process according to which it is possible to make semi-finished products with the same internal diameter, determined by the width of the cross section of the internal former 1, but different external diameter (different wall thickness). It is thus possible to make semi-finished products in a single material but with different mechanical features (depending on the wall thickness).

[0185] In Figure 8, instead, a semi-finished product is represented (right part of the figure), made by coupling a first multilayered sheath (obtained by dipping the internal former 1 into the container illustrated in the left part of the figure) with a second multilayered sheath (obtained by dipping the external former 2 into the container illustrated in the central part of the figure) .

[0186] Consistently, according to the illustrated embodiment, it is possible to make the internal sheath by performing a plurality, specifically three, dipping steps b) and corresponding drying steps c), and to make the external sheath by performing a plurality, specifically three, dipping steps c) and corresponding drying steps d). Specifically, the external sheath and the internal sheath are made of the same plastic material.

[0187] Alternatively, according to an embodiment not represented, the single layers which make up the internal and external sheaths are made from plastic material of different chemical nature or different mechanical and / or rheological features. In particular, it is possible to make layers of aromatic polyurethane (mechanically very high-performance and chemically very resistant to acids and bases) alternating with layers of aliphatic polyurethane (more flexible and transparent).

[0188] For instance, it is possible to make a coiled tube 7mm x 6mm made of internal layer (3 layers) and external layer (3 layers) .

[0189] According to this embodiment and more generally according to the present invention, the internal layer (in contact with the fluids flowing inside the coiled tube) and / or the internal layer (in contact with the fluids flowing outside the coiled tube) may contain active or pharmaceutical ingredients, specifically in order to have a drugreleasing effect.

[0190] Figure 9 shows the cross section of an armoured tube 100 following the lamination process according to a second embodiment, wherein the perforated armour 103 is a metal mesh, obtained by braiding metal wires. It is worth noting the additional TPU layer needed to increase the contact surface with the external sheath 102.

[0191] The production process for making an armoured tube through a perforated armour of the spring (or spiral) type according to two exemplifying embodiments (Example 1 and Example 2) is now described step by step.

[0192] Preparation of the polymer blend (preliminary step preceding dipping steps b) and d)): Example 1

[0193] Formulation by weight:

[0194] 1 part by weight of Pellethane 90-AE

[0195] 9 parts by weight of tetrahydrofuran

[0196] Final viscosity: 1100 mPa sec (tolerance: + / - 50 mPa sec)

[0197] The blend is made at room temperature with a rod mixer, 1500 rpm for 8 hours. The blend does not require filtration.

[0198] Example 2

[0199] 1 part by weight of Pellethane 90-AE

[0200] 8 parts by weight of tetrahydrofuran

[0201] Final viscosity: 1100 mPa sec (tolerance: + / - 50 mPa sec)

[0202] The blend is made at room temperature with a rod mixer, 1500 rpm for 8 hours. The blend does not require filtration.

[0203] In both example 1 and example 2 the polymer solution or blend is poured into tanks whose height is at least 10 cm greater than the length of the semi-finished product to be made.

[0204] Preparation of the forming means or formers (step a):

[0205] The diameter of the internal former is therefore equivalent to the internal diameter of the armoured tube that it is wished to obtain.

[0206] The formers used are made of stainless steel.

[0207] The former must be rectilinear and the centre of gravity must be located exactly on the longitudinal symmetry axis of the former. The former is hung in a perfectly vertical position, whether it is the internal or external one.

[0208] Polyurethane has a strong adhesion to most surfaces, including stainless steel, therefore, in order to be used, the former must be coated with a layer that acts as a release agent between steel and polyurethane.

[0209] For this reason it is necessary to use mandrels coated with polymeric material that is inert to the THF solvent and that do not show adhesion to polyurethane.

[0210] It is therefore proposed to coat the formers with a PTFE layer, since it is inert to THF, has minimal adhesion to polyurethane, and no release which is potentially unacceptable in the medical field.

[0211] In these examples, it has been chosen to use a PTFE heat- shrinkable tube with a maximum shrink ratio of 4: 1, using a heat source at 700°F.

[0212] The heat- shrinkable must have a diameter between +20% and +300% compared to the maximum diameter of the former to be coated.

[0213] It is possible to perform this step by putting the heat- shrinkable tube under tension before heating to obtain a thinner and more uniform coating.

[0214] The process requires two formers for each armored tube to be made, as previously described in relation to the summary.

[0215] Example 1

[0216] Coating a 500mm steel cylinder having a diameter of 5mm with PTFE.

[0217] Using a PTFE heat- shrinkable having a diameter of 1 / 2” (12.5 mm), a 4: 1 shrink ratio, heating it with an air heater at 700°F, with a tensile force of the heat- shrinkable between 20 Newtons and 40 Newtons. Final thickness of the PTFE tube 0. 1 mm. Double thickness PTFE = 0.2 mm.

[0218] Example 2

[0219] The same specifications and conditions as in Example 1 were applied.

[0220] Execution of the dipping steps (steps b) with subsequent step c), then step d) with subsequent step e):

[0221] Dipping is the process that allows creating the polyurethane layers that make up the armored tube.

[0222] By using a viscosity of 1100 mPaxsec + / - 50 mPaxsec, each layer deposits 0.07 - 0.08 mm of polyurethane onto the former.

[0223] In order to obtain the most complete layer possible over the entire length of the former, it is necessary to set the speed and acceleration as follows:

[0224] Former length: 500mm

[0225] Initial ascent rate: 300mm / min

[0226] Final ascent rate after extraction from solution: 0 mm / min

[0227] Acceleration: -3mm / secA2

[0228] To obtain a highly concentric result, it is necessary to ensure the perfect verticality of the former.

[0229] Maintaining a time interval comprised between 15 and 20 minutes between one dipping and the next.

[0230] Calculating the needed number of dipping by dividing the required final thickness of the layer to be made by 0.07 mm. To ensure maximum concentricity of the layers, it is preferable to perform the ascent step of the dipping by rotating the spindle at a speed of 10 rpm.

[0231] Example 1

[0232] Internal former:

[0233] Internal former length: 400 mm

[0234] Former diameter: 5 mm

[0235] Required thickness: 0.20mm + / -0.02

[0236] Single layer thickness: 0.07-0.08 mm

[0237] Number of baths: 3

[0238] Initial speed: 300mm / min

[0239] Waiting time (delta time) between two consecutive dipping: 15 min

[0240] Spindle rotation RPM: 8

[0241] Deceleration: 4 mm / seA2

[0242] Example 2

[0243] Internal former:

[0244] External former length: 550 mm

[0245] Former diameter: 7mm

[0246] Required thickness: 0.3mm + / -0.03

[0247] Single layer thickness: 0.07-0.08mm

[0248] Number of baths: 4 Initial speed: 260mm / min

[0249] Waiting time (delta time) between two dipping: 15 min

[0250] Spindle rotation RPM: 8

[0251] Deceleration: 4.5mm / seA2

[0252] The semi-finished products thus obtained, in accordance with Example 1 and Example 2, were used to produce a 5 mm x 6.5 mm armoured tube, with armour represented by coil with a diameter of 0.1 mm.

[0253] The spring was positioned approximately halfway the wall thickness of the final polyurethane tube. It is advantageous to keep the spring in an area comprised between 40% and 60% of the coiled tube thickness.

[0254] Example 1

[0255] Coiled tube 7 mm x 6 mm (21 Er), wall thickness 0.50 mm:

[0256] Internal layer: 0.20 mm number of dipping 0.2 / 0.07 = 3 dipping steps

[0257] Armor thickness: 0.10 mm

[0258] External layer: 0.20 mm number of dipping 0.2 / 0.07 = 3 dipping steps

[0259] Example 2

[0260] Coiled tube 6 mm x 4.5 mm (18 Fr), wall thickness: 0.75 mm:

[0261] Internal layer 0.30 mm number of dipping: 0.3 / 0.07 = 4 dipping steps

[0262] Armor thickness: 0.10 mm

[0263] External layer: 0,30 mm number of dipping 0.3 / 0.07= 4 dipping steps

[0264] The former for the external layer must have a similar shape but larger diameters than the internal former. Indeed, the external layer must be able to fit over the mechanical parts without friction or rubbing. The diameter of the external former should be equal to the diameter of the internal former + internal layer + gap.

[0265] An easily processable gap is between 0.5- 1.5 mm.

[0266] The internal and external formers are therefore geometrically similar, the external former is larger.

[0267] Example 1

[0268] Coiled tube: 5 mm x 4 mm (15 Fr):

[0269] Internal former diameter: 4mm

[0270] Internal former diameter + internal layer + coil: 4.5mm

[0271] External former diameter: 5.5mm

[0272] Example 2

[0273] The same specifications and conditions as in Example 1 were applied.

[0274] Execution of assembly step (step f):

[0275] The coiled tube has a stainless steel spiral therein, which allows the tube to resist extreme bending, as well as making it resistant to both external pressure / depression and internal pressure / depression.

[0276] The components are assembled in the following order from inside to outside: internal sheath, perforated armour and external sheath (coil).

[0277] For both Example 1 and Example 2, the perforated armour pitch was 35 turns / inch.

[0278] Preparation of semi-finished products usefill for lamination (moisture removal step g from the assembly obtained in the previous assembly step): The internal layer deposited on the internal mandrel and the external layer (already extracted from the external mandrel) were subjected to a moisture removal step at a value lower than 200 ppm (0.02% w / w).

[0279] A measurement of the moisture content of the two layers was performed with Karl Fischer technology or thermobalance or Aquatrac after having performed an oven drying step of the polyurethane layers for at least 8 hours at 60°C.

[0280] If the measurement result is less than 200 ppm, then it is possible to move on to the lamination step.

[0281] If the measurement result is higher than 200 ppm, then it is necessary to extend the drying step. Generally 8 hours at 60°C are sufficient to reach a value lower than 200 ppm. Drying in a ventilated oven with exhaust extraction. Drying for a longer period does not damage the polyurethane since 60°C do not lead to degradation even for prolonged periods.

[0282] Execution of the lamination step (step h):

[0283] The lamination step was performed by using a thermostatically controlled heating head.

[0284] To provide more homogeneous heating and avoid degradation of the polyurethane, placing a polyolefin heat-shrinkable tube over the external layer.

[0285] Said heat- shrinkable tube during the shrinking step presses the external layer onto the coil, giving it the heat necessary to reach a viscosity (or fluidity) such that the external layer can flow between the coil turns and come into contact with the internal polyurethane layer.

[0286] During the lamination step the internal former was rotated at a speed of 10 rpm.

[0287] Example 1 Making a coiled tube 15 Fr length 500mm, wall thickness 0.5mm, of Pellethane 2363 90AE.

[0288] Internal and external formers of stainless steel coated with PTFE.

[0289] Internal former + 0.2mm PTFE cover: diameter 4mm length 650mm.

[0290] Internal layer: thickness 0.2mm - / +0,03 (3 dipping steps at 1100 mPaxsec) length 650 mm.

[0291] External former: diameter 6 mm, length 650 mm (3 dipping steps at 1100 mPaxsec).

[0292] External layer: 0.2mm - / +0,03; tube: 6.4 x 6 mm, length 650 mm.

[0293] Coil with rectangular section: 0.1 x 0.4 mm; length 500 mm, 30 turns / inch. Stainless steel, internal diameter of the spring 5.3mm, external diameter 5.5 mm.

[0294] Internal former + internal layer + coil: diameter 5.5 mm.

[0295] Heat-shrinkable: diameter 10 mm, stretching ratio 3: 1 , polyolefin material (PP or PE), wall thickness 0.3 mm.

[0296] Heating head geometry: 360° round, diameter 1 inch, depth 20 mm.

[0297] Lamination temperature: 610 °F.

[0298] Lamination speed: 20mm / min.

[0299] Air flow: 15 liters / min at 610 °F.

[0300] Example 2

[0301] Making a coiled tube 25 Fr, length 500 mm, wall thickness 0.7mm, of Pellethane 2363 90AE, coiled tube 8.33 mm x 7mm x 500mm.

[0302] Internal and external formers of stainless steel coated with PTFE. Internal former + 0.2mm PTFE cover: diameter 7.00 mm length 650mm.

[0303] Internal layer: thickness 0.3 mm + 0.03 mm (4 dipping steps at 1100 mPaxsec ), length 650 mm.

[0304] External former: diameter 9 mm; length 650 mm.

[0305] External layer: wall thickness 0.3 mm + 0.03 mm (4 dipping steps at 1100 mPaxsec).

[0306] Coil with rectangular section: 0.15 x 0.4 mm length 500, 37 turns / inch. Stainless steel, spring internal diameter 7.4 mm, external diameter 7.7 mm.

[0307] Internal former + internal layer + coil: diameter 7.6 mm.

[0308] Heat- shrinkable: diameter 10 mm, stretching ratio 3: 1, polyolefin material (PP or PE), wall thickness 0.3 mm.

[0309] Heating head geometry: 360° round, diameter 1 inch, depth 20 mm.

[0310] Lamination temperature: 750 °F.

[0311] Lamination speed: 20mm / min

[0312] Air flow: 20 liters / min at 750 °F.

[0313] Cooling (step i) and extraction of the former from the cannula and removal of the external heat-shrinkable:

[0314] Once the lamination step has ended, the reinforced tube of plastic material thus obtained was left to cool at room temperature, along with the internal former.

[0315] After thirty minutes as of the end of the lamination, the cannula reaches the room temperature and it is possible to remove the polyolefin heat- shrinkable from the outside of the cannula. Scoring the heat- shrinkable along the entire length of the tube coil using a fixed depth razor blade.

[0316] Heating at 60°C to facilitate the removal of the heat- shrinkable following the incision made with the razor blade.

[0317] The polyolefin heat- shrinkable has no adhesion to polyurethane, so no deformation of the polyurethane layer of the coiled tube occurs during this step.

[0318] Once the external heat- shrinkable has been removed, we proceed with the removal of the internal former from the cannula.

[0319] By cutting the ends of the coiled tube on the former, and therefore also cutting the PTFE layer that covers the internal former, the cannula slides out of the steel former without any friction.

[0320] Indeed, the PTFE layer does not have any adhesion or friction with the steel of the former.

[0321] Therefore, the use of the PTFE coating is useful to facilitate the removal of the polyurethane cannula from the steel former as best as possible.

[0322] Once the cannula has been removed, it is easy to extract the PTFE layer remaining inside the cannula.

[0323] Using tweezers, pull the PTFE layer by rotating it and it will detach from the internal layer of the coiled tube, as there is no chemical or mechanical adhesion between PTFE and polyurethane.

[0324] Performing a cooling step, leaving the cannula at room temperature for at least 24 hours, so that the polyurethane can stabilize and reach the final mechanical performances.

[0325] Both for Example 1 and for Example 2, a tube of plastic material reinforced with armour has been obtained, wherein the plastic material was monolithic without bubbles or defects. Quality control and validation of the mechanical performance of the coiled tube obtained through Example 1 :

[0326] 4D Rotary test (ISO 18193 standard): 20mm curvature wheel, time 1 week, temperature 37°C, flow drop 5%.

[0327] Quality control and validation of the mechanical performance of the coiled tube obtained through Example 2:

[0328] 4D Rotary test (ISO 18193 standard): curvature wheel 33.3 mm, time 1 week, temperature 37°C, flow drop 8%.

[0329] The production procedure for making an armoured tube using a perforated armour of the mesh type is now described according to an exemplary embodiment (Example 3).

[0330] Example 3

[0331] The production procedure performed for Example 1 and Example 2 is the same as that adopted in the present example, with the exception of the operation of applying the heat- shrinkable sheath of polyolefin material.

[0332] Moreover, during Example 3, during assembly step f) and prior to the sub-step of inserting the second sheath of plastic material onto the perforated armour previously coupled to the first sheath of plastic material, an additional dipping step (overbraid bath) and a subsequent drying step were performed.

[0333] Moreover, during the lamination step, a tensor was applied to the external sheath.

[0334] The following specifications have been adopted.

[0335] Perforated armor used: BRAIDED TUBE 15 Fr;

[0336] Internal former diameter covered by PTFE: 4 mm; External former diameter: 5 mm;

[0337] First layer or internal sheath: made of Pellethane 2363 80-AE - Thickness, 0.2 mm obtained with 3 dipping steps with viscosity 1200 mPa - ascent speed, 150 mm / min - rotation during ascent, 8 rpm; Second layer or external sheath: made of Pellethane 2363 80-AE - thickness 0.15 mm; obtained with 3 dipping steps with viscosity 1200 mPa - ascent speed, 150 mm / min - rotation during ascent, 8 rpm;

[0338] Mesh: internal diameter of the tubular braid 4 mm - diameter braid wire 0. 15 mm of stainless steel - number of wires 24 - pitch 20 mm; Overbraid bath: of Pellethane 80AE with viscosity 1200 mPa;

[0339] Tensor weight 0.3 N - lamination temperature: 275°C - lamination speed: 60 mm / min- flow 22 1 / min - lamination rotation: 10 rpm.

[0340] A cooling step was performed, leaving the cannula at room temperature for at least 24 hours, so that the polyurethane could stabilize and reach the final mechanical performances.

[0341] A tube of plastic material reinforced with armour was obtained, where the plastic material was monolithic without bubbles or defects.

Claims

CLAIMS1. Process for the production of tubes of plastic material reinforced with armour comprising the following steps: a) providing a first forming means (1) and a second forming means (2), wherein said first forming means and said second forming means have a longitudinal extension and are adapted to be set in rotation about a longitudinal axis, said first forming means extending along a longitudinal axis of first forming means and having a section of first forming means having a width of first forming means and said second forming means extending along a longitudinal axis of second forming means and having a section of second forming means having a width of second forming means, said width of first forming means being less than said width of second forming means; b) immersing said first forming means (1) into a first polymer blend comprising a first polymeric material and a first solvent, said first polymeric material being dissolved in said first solvent, so as bring said first forming means into contact with said first polymer blend, and subsequently extracting the first forming means from said first polymer blend, wherein during dipping and extraction the first forming means is set in rotation, thus determining the adhesion of a first thin layer of said first polymer blend on said first forming means; c) drying or letting dry said first thin layer of first polymer blend, thus obtaining a first sheath (101) of plastic material and tubular in shape; d) immersing said second forming means (2) into a second polymer blend comprising a second polymeric material and a second solvent, said second polymeric material being dissolved in said second solvent, so as to bring said second forming means into contact with said second polymer blend, and subsequently extracting the second forming means from said second polymer blend, wherein during dipping and extraction the second forming means is set in rotation, thus determining theadhesion of a second thin layer of said second polymer blend on said second forming means; e) drying or letting dry said second thin layer of second polymer blend, thus obtaining a second sheath (102) of plastic material and tubular in shape; f) performing an assembly step, by arranging a perforated armour between said first sheath (101) of plastic material and said second sheath (102) of plastic material and obtaining a tubular-shaped assembly (10) comprising a first sheath (101) of plastic material, a second sheath (192) of plastic material and a perforated armour (103) arranged there between, said perforated armour (103) being provided with through-holes; g) subjecting said (10) tubular- shaped assembly to a moisture removal operation; h) once the moisture removal step g) has been performed, heating said tubular-shaped assembly (10) to the point of at least partial fusion of said first sheath (101) of plastic material and / or of said second sheath (102) of plastic material, so as to let a portion of said first sheath of plastic material and / or of said second sheath of plastic material flow through the through-holes of said perforated armour (103); and i) cooling said tubular- shaped assembly, thus obtaining a tube (100) of plastic material reinforced with armour.

2. Process according to claim 1, wherein in the tube of plastic material reinforced with armour obtained in cooling step i) said plastic material is monolithic and said perforated armour is completely immersed in said plastic material.

3. Process according to claim 1 or 2, wherein said polymeric material is a thermoplastic elastomer, preferably it is a thermoplastic polyurethane or a polymer blend comprising thermoplastic polyurethane.

4. Process according to claim 3, wherein in said heating step h) said tubular- shaped assembly is heated at a temperature comprised between 180°C-210°C.

5. Process according to claim 3 or 4, wherein the solvent in said first polymer blend and / or in said second polymer blend is tetrahydro furan.

6. Process according to any one of the preceding claims, wherein in assembly step g) said perforated armour has an armour section having an armour width having an intermediate value comprised between the width of said first forming means and the width of said second forming means.

7. Process according to any one of the preceding claims, wherein said perforated armour is made of metal, preferably stainless steel.

8. Process according to any one of the preceding claims, wherein said perforated armour is in the form of a net, of a spiral, of perforated hypotube or any combination thereof.

9. Process according to claim 8, wherein said perforated armour is in the form of a metal spiral, preferably of stainless steel.

10. Process according to any one of the preceding claims, wherein said first forming means and said second forming means are covered by an material insoluble in the first solvent and / or in the second solvent used during dipping steps b) and d), respectively, preferably said first forming means and said second forming means being covered by a fluorinated polymer, more preferably said fluorinated polymer being selected from polytetrafluoroethylene (PTFE), FEP, PVDF, PP, or PE.

11. Process according to any one of the preceding claims, wherein in said assembly step g) comprises the following sub-steps:- inserting said perforated armour onto the first sheath of plastic material;- optionally, immersing said first sheath of plastic material and said perforated armour thus inserted thereonto into a further solvent, the plastic material being at least partially miscible in said further solvent, for a pre-set time;- optionally, extracting said first sheath of plastic material and said perforated armour from the solvent and drying said further solvent;- inserting said second sheath of plastic material onto the perforated armour thus coupled to the first sheath of plastic material, thus obtaining said tubular- shaped assembly.

12. Process according to claim 11, wherein in the dipping sub-step said pre-set time is comprised between 1 second and 2 minutes, preferably between 2 seconds and 10 seconds.

13. Process according to claim 11 or 12, wherein in the dipping substep said further solvent coincides with the first solvent and / or with the second solvent, preferably said solvent is tetrahydro furan.

14. Process according to any one of claims 11 to 13, wherein during assembly step f) in the sub-step of inserting said perforated armour onto the first sheath of plastic material said first sheath of plastic material is laid on said first forming means.

15. Process according to claim 14, wherein said step i) is carried out until a temperature comprised between 18-25°C is reached and / or subsequently to cooling step i) the following steps are performed: j) removing the tube (100) of plastic material reinforced with armour from said first forming means; k) keeping the tube of plastic material reinforced with armour at room temperature, preferably for a period of at least 24 hours.

16. Tube (100) of plastic material reinforced with armour obtainable according to any one of claims 1 to 15.

17. Tube (100) of plastic material reinforced with armour according to claim 16 for use in the medical- surgical field.

18. Tube (100) of plastic material reinforced with armour according to claim 17 for use as a catheter.

19. Catheter made with the tube of plastic material reinforced with armour according to claim 16.

20. Use of the tube of plastic material reinforced with armour according to claim 16 for making biomedical equipment.

21. Biomedical equipment comprising the tube of plastic material reinforced with armour according to claim 16, preferably said biomedical equipment being arranged for performing ECC (extra corporeal circulation) or ECMO (extracorporeal membrane oxygenation).

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