Extruder for mixing microcatheter

Abstract

The present invention relates to an extruder for mixing microconduits, comprising an extrusion die, a diverter element and several resin sources, the diverter element allowing resin selection.

Description

Technical Field

[0001] The present disclosure relates to microcatheter fabrication, and in particular to microcatheters having different flexibility along their length. The present disclosure relates to extruders, catheters, and methods of fabricating microcatheters. Such catheters are particularly suitable for use in the fields of interventional radiology and neuroradiology. Background Art

[0002] Since the 1980s, microcatheter technology has been developed to the extent that microcatheters are now commonly used in the treatment of vascular lesions in the central vascular system. Microcatheters are low-profile catheters that are used to treat stroke, cerebral aneurysms, fistulas, arteriovenous malformations and other areas by selective placement of coils, particles, balloons or liquid adhesives through intravascular access to occlude pathological vascular abnormalities, but are also used for ischemic stroke by opening occluded blood vessels. Such microcatheters can also be used in other areas of the body.

[0003] In these delicate procedures, a major difficulty involves guiding the catheter through the tortuous bifurcations of the artery to navigate it to the site of treatment. The ability to accurately and quickly guide the catheter is critical to effective cannulation with minimal risk.

[0004] The key feature of catheters to achieve correct guidance is their flexibility. In fact, catheters need to be rigid in some parts so that the catheter can be accurately guided when pushed on its guide. But in some areas where the cerebral vascular distribution is highly tortuous, the catheter also needs to be flexible. This feature must be achieved with catheters with very small diameters below 6Fr in order to be able to navigate through the carotid artery into the cerebral vessels.

[0005] Methods for obtaining such catheters use welding techniques: at least two tubes made of different materials are welded where the flexibility is expected to change. However, welding generally results in a change in the inner diameter, causing unpredictable changes in the functional properties of the catheter. In addition, the weld is mechanically weaker than the bulk material and the welded catheter may break.

[0006] Extrusion of tubes with different resin sources is also known, which results in a catheter with a gradient of composition along its length. This gradient of composition can be selected to provide a gradient of flexibility. However, this extrusion technique generally results in very long transition lengths, much longer than is needed in the tortuous arteries of the brain.

[0007] Although catheters with variable flexibility are known, there remains a need for microcatheters whose flexibility varies over very short lengths, typically less than 30 mm. Summary of the invention

[0008] Therefore, the present invention relates to an extruder for thermoplastic hybrid microcatheters. The extruder includes an extrusion die, which includes a die member and a mandrel arranged in the same direction as the die member. The extruder also includes at least two resin sources and a commutator element adjacent to the extrusion die and including at least one inflow channel opening on the mandrel. In addition, the commutator element slides on the extrusion die to allow a resin source selected from the at least two resin sources to flow to the die member through an extrusion channel defined by the die member, the mandrel and the opening of the inflow channel on the mandrel. In addition, the extrusion channel and the inflow channel together have a diameter of less than 20 mm. 3 , preferably less than 15mm 3 The volume V in .

[0009] In a first configuration, the commutator element slides rotationally on the extrusion die about the extrusion die axis. In this configuration, the extruder may include three resin sources.

[0010] In a second configuration, the commutator element slides longitudinally over the extrusion die.

[0011] In an embodiment, the dimensions of the mold member and the spindle are selected from the following pairs (unit: mm): 0.4 / 0.15; 0.6 / 0.25; 0.8 / 0.4; 1 / 0.6; 1.2 / 0.8; 1.4 / 1; 1.6 / 1.2; 1.8 / 1.4; 2 / 1.6; 2.2 / 1.8; 0.8×1.2 / 0.6; 0.6×1 / 0.4; 1×1.4 / 0.8; 1.2×1.6 / 1; 1.5×1.9 / 1.2; 1.8×2.2 / 1.5.

[0012] In an embodiment, the extrusion die comprises a die member and two mandrels. Preferably, the dimensions of the die member, the first mandrel and the second mandrel are selected from the following triplet (unit: mm): 0.6 / 0.15 / 0.15; 1 / 0.4 / 0.4; 1.4 / 0.6 / 0.4; 1.8 / 0.8 / 0.6; 2.2 / 1 / 0.8; 0.8×1.2 / 0.4 / 0.4; 1×1.4 / 0.6 / 0.4; 1.5×1.9 / 0.8 / 0.4.

[0013] In an embodiment, the mandrel has a central cavity extending in an axial direction, said central cavity of the mandrel being connected to a gas source.

[0014] The present invention also relates to a method for extruding a thermoplastic hybrid microcatheter, comprising the following steps: - placing a diverter element of the extruder as disclosed above to allow flow from the first resin source to the die member; - Extruding a microcatheter of a predetermined length; - sliding the commutator element to allow flow from the second resin source to the mold member; and - Extruding a microcatheter of a predetermined length.

[0015] In an embodiment, the extrusion speed is included within 30 mm.s -1 and 200mm.s -1 between.

[0016] Another object of the present invention is a microcatheter obtained by the method disclosed above, wherein the resin pair used is selected from: - polypropylene and a mixture of polypropylene and thermoplastic polyurethane in a weight ratio comprised between 20:80 and 80:20; - polyamides and polyamide-polyester block copolymers; or - Two different types of PVC.

[0017] In an embodiment, the transition length between the two resins is less than 25 mm, preferably less than 20 mm. definition

[0018] In the present invention, the following terms have the following meanings:

[0019] With respect to the "size" of a mold member, mandrel, tube or conduit, the diameter is referred to if the element is cylindrical, or the minor and major axes - recorded as minor axis x major axis - if the element is ellipsoidal or oval. The size of a pair of a mold member and a mandrel is recorded as size of mold / size of mandrel. For example, if the mold has an ellipsoidal shape with a minor axis of 0.8 mm and a major axis of 1.2 mm (recorded as 0.8×1.2), and the mandrel is cylindrical with a diameter of 0.6 mm, the pair would be recorded as 0.8×1.2 / 0.6. The same applies to a triplet consisting of a mold member and two mandrels. For example, if the mold has an ellipsoidal shape with a minor axis of 0.8 mm and a major axis of 1.2 mm (recorded as 0.8×1.2), and the two mandrels are cylindrical with a diameter of 0.4 mm, the triplet would be recorded as 0.8×1.2 / 0.4 / 0.4.

[0019] "French" (abbreviated Fr) refers to the catheter scale for diameter: 1 mm equals 3 Fr. Therefore, the diameter of a round catheter in millimeters can be calculated by dividing the French size by 3.

[0020] "Hybrid": refers to a microcatheter whose composition is not uniform. Some portions of the microcatheter are made of a first material A, and other portions of the microcatheter are made of a second material B. B differs from A in flexibility. The portion of the microcatheter where the composition changes from the first material A to the second material B is a transition. A hybrid microcatheter may include more than two different materials.

[0021] "Resin": refers to the material used to make the microcatheters, either in pellet form or molten form. In a broad sense, resin also refers to the material of the microcatheters. Therefore, the terms resin and material are used interchangeably.

[0022] "Transition length": refers to the length over which the flexibility of a catheter changes from the flexibility of a first material to the flexibility of a second material. The transition length can be measured in various ways: for example, by mechanical properties, optical properties (such as color), or by chemical composition. DETAILED DESCRIPTION

[0024] The following detailed description will be better understood when read in conjunction with the accompanying drawings. For illustrative purposes, the device is shown in a preferred embodiment. However, it should be understood that the application is not limited to the precise arrangements, structures, features, embodiments, and aspects shown. The accompanying drawings are not intended to limit the scope of the claims to the embodiments depicted. Therefore, it should be understood that where features mentioned in the attached claims are followed by figure marks, such marks are included only for the purpose of enhancing the understandability of the claims and are in no way a limitation on the scope of the claims.

[0025] The present disclosure relates to an extruder 1 envisioned for producing hybrid microcatheters. The extruder 1 comprises an extrusion die comprising a die member 11 and a mandrel 12. The die member 11 and the mandrel 12 are arranged along the same direction, i.e., the extrusion die direction or the extrusion die axis. This arrangement allows extrusion of a tube comprising a lumen: the mandrel 12 defines the inner dimensions of the tube, while the die member 11 defines the outer dimensions of the tube.

[0026] In an embodiment, the mandrel 12 has a central cavity 13 extending in the axial direction, and the central cavity 13 of the mandrel 12 is connected to a gas source configured to flow gas to keep the lumen open during extrusion and cool the microcatheter under extrusion. Alternatively, the extruder 1 can be combined with a cooling tray to cool the microcatheter very quickly after extrusion, thereby freezing the geometry of the microcatheter and keeping the lumen open.

[0027] Extruder 1 includes at least two resin sources. These sources will be used alternately to produce mixed micro-ducts. Figure 1 As shown above, the resin source typically includes a hopper 4 into which pellets of resin (typically a thermoplastic resin or polymer) are introduced, a screw inserted into a heated barrel 2 to melt the resin and move it toward an extrusion die, and a screw drive 3 . Figure 1 Two resin sources are shown arranged at an angle of 30° to the axis of the extrusion die. In other embodiments, the resin sources may be arranged parallel to the axis of the extrusion die or in any suitable direction. More than two sources may be used.

[0028] The extruder 1 further comprises a commutator element 14 adjacent to the extrusion die. The commutator element 14 comprises at least one inflow channel 15 opening on the mandrel 12. During extrusion, resin will be guided from the resin source to the extrusion die through the inflow channel 15.

[0029] The commutator element 14 slides on the extrusion die. The slide allows the resin to be selected from a source and flowed to the mandrel 12 through the inflow channel 15 and then to the die member 11. The volume defined by the die member 11, the mandrel 12 and the opening of the inflow channel 15 on the mandrel 11 is the extrusion channel. The extrusion channel prepares the resin distribution around the mandrel 12 before the die member 11.

[0030] In the first position, the diverter element 14 allows the flow of resin from the first resin source. In the second position, the diverter element allows the flow of resin from the second resin source. Sliding from the first position to the second position (and vice versa) allows the resin fed into the extrusion channel to be changed and ultimately the composition of the extruded microconduits to be changed.

[0031] In the present disclosure, the extrusion channel and the inflow channel 15 together have a length of less than 20 mm. 3 The volume V in In other words, the sum of the volume of the extrusion channel and the volume of the inflow channel 15 is V in Less than 20mm 3 In practice, this volume is related to the amount of resin that will be involved during the transition from one resin to another. Below 20 mm 3 The extrusion volume surprisingly provides a short transition length on the hybrid microcatheter with very good mechanical properties, especially good resistance to fracture in the transition.

[0032] Preferably, the extruder 1 is envisaged for producing thermoplastic hybrid microcatheters, ie microcatheters made of thermoplastic polymers.

[0033] In a first configuration, the commutator element 14 is rotationally slidable on the extrusion die about the extrusion die axis, such as Figure 2 As shown above.

[0034] The inflow channel 15 is here connected to the heated barrel 2 of the resin source via the feed pipe 5. The resin then flows through the inflow channel 15, reaches the mandrel 12 and is distributed in the extrusion channel. To select another resin source, the commutator element is rotated to align the inflow channel 15 with the feed pipe 5 of the resin source. During the slide, no resin is injected into the inflow channel. In order to avoid extrusion problems, the slide is preferably operated quickly so that the volume of resin extruded during the feed interruption time is proportional to V in Keep it smaller in comparison.

[0035] In an embodiment, the extruder 1 comprises three resin sources. The resin sources (referred to as A, B and C) are distributed on a circle, all of which can be connected to a commutator element that slides in rotation, the embodiment allowing sliding from source A to source B, from source A to source C and from source B to source C. It is thus possible to design any series of materials along the microduct: ABAB, ABCBA, ABCAB, ACBA...

[0036] In the second configuration, the commutator element 14 is slid longitudinally over the extrusion die.

[0037] For both configurations, the geometry of the microcatheter is defined by the dimensions of the mold member 11 on the one hand, and by the dimensions of the mandrel 12 on the other hand. In an embodiment, the diameter of the mold member 11 is in the range from 0.4 mm to 2.66 mm (from 1.2 Fr to 8 Fr) and defines the outer diameter of the microcatheter. For example, the diameter of the mold member 11 may be 0.4; 0.5; 0.6; 0.7; 0.8; 0.9; 1; 1.1; 1.2; 1.3; 1.4; 1.5; 1.6; 1.8; 2; 2.2 mm. In an embodiment, the mold member 11 has an ellipsoidal or oval shape with dimensions (in mm×mm) of 0.8×1.2; 0.6×1; 1×1.4; 1.2×1.6; 1.5×1.9; 1.8×2.2. In an embodiment, the diameter of the mandrel 12 ranges from 0.15 mm to 2 mm (about 0.5 Fr to 6 Fr) and defines the inner diameter of the microcatheter, i.e., the lumen diameter. For example, the diameter of the mandrel may be 0.15; 0.25; 0.4; 0.6; 0.8; 1; 1.4; 1.8 mm. The most suitable geometries for the microcatheters are the following pairs of mold member size / mandrel diameter (in mm): 0.4 / 0.15; 0.6 / 0.25; 0.8 / 0.4; 1 / 0.6; 1.2 / 0.8; 1.4 / 1; 1.6 / 1.2; 1.8 / 1.4; 2 / 1.6; 2.2 / 1.8; 0.8×1.2 / 0.6; 0.6×1 / 0.4; 1×1.4 / 0.8; 1.2×1.6 / 1; 1.5×1.9 / 1.2; 1.8×2.2 / 1.5.

[0038] In an embodiment that can be combined with both configurations, the extrusion die includes a die member 11 and a single mandrel 12 (see Figure 2 ). The mandrel 12 can be arranged coaxially with the mold member 11, thereby producing a catheter having a lumen surrounded by a wall of uniform thickness. Alternatively, the mandrel 12 can also be constructed along the same direction as the mold member 11, but eccentrically.

[0039] In an embodiment that can be combined with both configurations, the extrusion die comprises a die member 11 and two mandrels 12. The two mandrels 12 are arranged in the same direction as the die member 11. They can both be eccentric. Alternatively, one mandrel 12 is arranged coaxially with the die member and the other mandrel 12 is eccentric. The two mandrels 12 can have the same size or different sizes. The most suitable geometry of the microcatheter is the following triad of die member size / first mandrel diameter / second mandrel diameter: 0.6 / 0.15 / 0.15; 1 / 0.4 / 0.4; 1.4 / 0.6 / 0.4; 1.8 / 0.8 / 0.6; 2.2 / 1 / 0.8; 0.8×1.2 / 0.4 / 0.4; 1×1.4 / 0.6 / 0.4; 1.5×1.9 / 0.8 / 0.4.

[0040] The present invention also relates to a method for extruding a hybrid microcatheter, which comprises the following steps.

[0041] An extruder 1 as disclosed above is provided, and the diverter element 14 is positioned to allow flow from a first resin source to the mould member 11 .

[0042] Then, a microcatheter of a predetermined length is extruded.

[0043] To change the resin source, the diverter element 14 slides to allow flow from the second resin source to the mold member 11 according to the microduct design. To avoid extrusion problems, the slide is preferably operated quickly so that the volume of resin extruded during the feed interruption time is proportional to V in Keep it smaller in comparison.

[0044] Then, another predetermined length of microcatheter is extruded.

[0045] In the two extrusion steps, the extrusion speed can be from 30mm.s -1 Up to 200mm.s -1 In the present disclosure, extrusion can be accomplished with gas injection through mandrel 12 to maintain the lumen of the microcatheter. The gas flow rate is easily determined by one skilled in the art. Alternatively, extrusion can be accomplished with a cooling tray that is intended to freeze the microcatheter geometry and maintain lumen patency during extrusion.

[0046] The steps of extrusion and resin source selection may be repeated several times in order to obtain a conduit with variable properties along its length.

[0047] Preferably, the method of extrusion of the hybrid microcatheter is a method of producing a thermoplastic hybrid microcatheter using a thermoplastic polymer.

[0048] The present invention also relates to a microcatheter obtained by the method disclosed above.Preferably, the microcatheter is a thermoplastic hybrid microcatheter.

[0049] A variety of microcatheters are available.

[0050] The size of the microcatheter is defined by the geometry of the mold member 11 and the mandrel 12. The outer diameter of the microcatheter is in the range of from 0.4 mm to 2.66 mm (from 3 Fr to 8 Fr), and preferably, the diameter of the mold member 11 may be 0.4; 0.5; 0.6; 0.7; 0.8; 0.9; 1; 1.1; 1.2; 1.3; 1.4; 1.5; 1.6; 1.8; 2; 2.2 mm. The inner diameter of the microcatheter is in the range of from 0.15 mm to 2 mm (from about 0.5 Fr to 6 Fr), and preferably, the diameter of the mandrel 12 may be 0.15; 0.25; 0.4; 0.6; 0.8; 1; 1.4; 1.8 mm. The most suitable pairs of microcatheter sizes are (unit: mm): 0.4 / 0.15; 0.6 / 0.25; 0.8 / 0.4; 1 / 0.6; 1.2 / 0.8; 1.4 / 1; 1.6 / 1.2; 1.8 / 1.4; 2 / 1.6; 2.2 / 1.8; 0.8×1.2 / 0.6; 0.6×1 / 0.4; 1×1.4 / 0.8; 1.2×1.6 / 1; 1.5×1.9 / 1.2; 1.8×2.2 / 1.5. The most suitable trio of microcatheter sizes is (unit: mm): 0.4 / 0.15; 0.6 / 0.25; 0.8 / 0.4; 1 / 0.6; 1.2 / 0.8; 1.4 / 1; 1.6 / 1.2; 1.8 / 1.4; 2 / 1.6; 2.2 / 1.8; 0.8×1.2 / 0.6; 0.6×1 / 0.4; 1×1.4 / 0.8; 1.2×1.6 / 1; 1.5×1.9 / 1.2; 1.8×2.2 / 1.5.

[0051] Various resin pairs (preferably thermoplastic resins) can be used in the method for preparing the microcatheter. In each pair, one resin can have a higher flexibility (hereinafter flexible) and the other resin can have a lower flexibility (hereinafter rigid). For example, a suitable resin pair is polypropylene (rigid) and a mixture of 50%wt polypropylene and 50%wt thermoplastic polyurethane (flexible). A mixture of polypropylene and thermoplastic polyurethane in a weight ratio comprised between 20:80 and 80:20 is suitable as the flexible resin of the present invention. Another suitable resin pair is polyamide (rigid) and polyamide-polyether block copolymer (flexible, typically Another suitable resin pair includes two grades of polyvinyl chloride having different stiffness / flexibility.

[0052] In a preferred embodiment, the two resins within a resin pair have glass transition temperatures that differ by less than 40°C.

[0053] In a preferred embodiment, the two resins within a resin pair have melting temperatures that differ by less than 40°C.

[0054] In embodiments, some resins may be radiopaque. In each resin pair, one resin may be transparent and the other resin may include radiopaque markers.

[0055] In an embodiment, three resins are used, preferably thermoplastic resins: a rigid transparent resin, a rigid radiopaque resin and a flexible resin. This embodiment allows the preparation of a microcatheter with controlled flexibility over its length, the rigid portion of which is radiopaque or not.

[0056] Alternatively, three resins are used: a rigid resin, a transparent flexible resin and a radiopaque flexible resin. This embodiment allows the preparation of a microcatheter with controlled flexibility over its length, the flexible portion of which is either radiopaque or not.

[0057] Because this method allows the in The production of the micro-catheters of the extrusion channel and the inflow channel 15 changes the material, so the transition length is usually very short. Choose less than 20 mm 3 V in This results in a transition length that is typically shorter than 25 mm, preferably lower than 20 mm.

[0058] The transition length is the length over which the flexibility of the catheter changes from the flexibility of the first material A to the flexibility of the second material B. The measurement of the transition length can be achieved by various methods.

[0059] In the mechanical method, the flexibility of the catheter is measured continuously over the length of the catheter and reported on a graph. A Change to constant value F in material B B When the change occurs, the flexibility difference is △ F The transition length is defined here as the change in flexibility from △ F 90% of the variation is in length.

[0060] In the chemical method, the properties of the material can be measured continuously over the length of the conduit by spectroscopy (typically using infrared spectroscopy). A transition occurs when the spectrum changes from a characteristic spectrum of material A to a characteristic spectrum of material B, with different features in the two spectra. The transition length is defined here as the length over which the amplitude of the feature changes from 90%.

[0061] For example, if the resin pair used is polypropylene and a mixture of 50%wt polypropylene and 50%wt thermoplastic polyurethane: the signature may be the spectral signature of urethane bonds in the infrared spectrum. This signature is absent in polypropylene, whereas it appears at full amplitude in a mixture of polypropylene and thermoplastic polyurethane. For polyamides and polyamide-polyether block copolymers, the signature may be the spectral signature of ether bonds in the infrared spectrum.

[0062] If material A and material B are colored with different pigments and / or dyes, the transition length can also be evaluated by color transition. The transition length is defined here as the length over which the color changes from the color of material A to the color of material B using subjective visual appreciation.

[0063] In the present disclosure, the transition length obtained is typically shorter than 30 mm, preferably shorter than 25 mm. The transition length can be even shorter, especially for microcatheters with a size greater than 1 mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 is a schematic diagram of an extruder according to an embodiment: two resin sources are connected to the extrusion die through a commutator element (not shown).

[0065] Figure 2 is an enlarged side view showing the extrusion die 11 and the commutator element 14 in a first configuration (rotationally sliding). Figure 2 In FIG. 1 , the thickness of the commutator elements is not to scale. Example

[0066] The present invention is further illustrated by the following examples. Example 1: PP-PP / TPU micro-duct 1.2mm / 0.8mm

[0067] An extruder with two resin sources and a rotating commutator element is used. The commutator element is 6 mm thick and has a hole of 1.5 mm diameter in which the mandrel is placed, thereby defining an extrusion channel around the mandrel. The inflow channel is inclined and has a diameter of 3 mm. The total volume of the extrusion channel and the inflow channel together is V in About 18mm 3 .

[0068] Resin A is polypropylene (Tg ~ -10°C, Tf ~ 160°C). Resin B is a mixture of 50% wt of resin A (Tg ~ -10°C, Tf ~ 160°C) and 50% wt of thermoplastic polyurethane (Tg ~ -40°C, Tf> 120°C).

[0069] Resin source A supplies resin at a screw rotation speed of 45 rpm, with a heating barrel temperature of 225° C. Resin source B supplies resin at a screw rotation speed of 30 rpm, with a heating barrel temperature of 175° C. The temperatures of the two resin sources are the same to avoid thermal stress when switching resin sources.

[0070] The diameter of the mold member was 1.2 mm and the diameter of the mandrel was 0.8 mm.

[0071] Extrusion starts with resin A at 30 mm / s -1 During extrusion, at 6 cm H 2 A constant gas flow rate is injected through the mandrel at a pressure of 0.040. After a few seconds, the commutator element rotates within a few milliseconds to switch from resin A to resin B. -1 Extrusion continues for 30 seconds at the extrusion speed, and then the commutator element rotates back within a few milliseconds to select resin A again.

[0072] Finally, a 120 cm long microcatheter 1 (4 Fr) was obtained with two transitions between material A and material B, the two transitions having a length shorter than 30 mm. Example 2: PP-PP / TPU micro-duct 1.5mm / 1mm

[0073] Example 1 was repeated except for the change in extrusion geometry: the diameter of the die member was 1.5 mm and the diameter of the mandrel was 1 mm. Additionally, Resin A was changed to polypropylene having a glass transition temperature of 175°C and the temperature of both resin sources was set to 195°C.

[0074] Finally, a 120 cm long microcatheter 2 (5 Fr) was obtained with two transitions between material A and material B. Since the diameter and thickness of microcatheter 2 were larger than those of microcatheter 1, the transitions had a shorter length of less than 25 mm. Example 3: ABC microcatheter 1.2mm / 0.8mm

[0075] An extruder with three resin sources and a rotating commutator element is used. The commutator element is 6 mm thick and has a hole of 1.5 mm diameter in which the mandrel is placed, thereby defining an extrusion channel around the mandrel. The inflow channel is inclined and has a diameter of 3 mm. The total volume of the extrusion channel and the inflow channel together is V in About 18mm 3 .

[0076] Resin A is polypropylene (Tg ~ -10 ° C, Tf ~ 145 ° C). Resin B is a mixture of 50% wt of Resin A (Tg ~ -10 ° C, Tf ~ 145 ° C) and 50% wt of thermoplastic polyurethane (Tg ~ -40 ° C, Tf> 120 ° C). Resin C is a polyamide with 20% BaSO4 radiopaque marker (Tg ~ 45 ° C, Tf ~ 185 ° C).

[0077] The temperature of the three resin sources was the same, 165°C, to avoid thermal stress when switching the resin source.

[0078] The diameter of the mold member was 1.2 mm and the diameter of the mandrel was 0.8 mm.

[0079] Extrusion starts with resin A at 30 mm / s -1 During extrusion, at 6 cm H 2 A constant gas flow rate is injected through the mandrel at a pressure of 0.040. After a few seconds, the commutator element rotates within a few milliseconds to switch from resin A to resin B. -1 Extrusion is continued for 15 seconds at an extrusion speed, and then the commutator element is rotated again within a few milliseconds so that resin A is selected again.

[0080] Finally, a 150 cm long microcatheter 3 (4 Fr) was obtained, which had transitions between material A and material B, then between material B and material C, and finally between material C and material A. All transitions had a length shorter than 30 mm. Example 4: PA-PEBAX microcatheter 1.2mm / 0.8mm

[0081] Example 1 was repeated except for the changes in resin. Resin A was changed to polyamide (Tg ~ 45°C, Tf ~ 185°C). Resin B was changed to polyamide-polyether block copolymer ( Supplied by Arkema; ​​Tg ~ -65°C, Tf ~ 144°C), and the temperature of both resin sources was set to 170°C.

[0082] Finally, a 165 cm long microcatheter 4 (4 Fr) was obtained with two transitions between material A and material B, both transitions having a length shorter than 30 mm. Example 5: PVC-PVC micro-catheter 1.2mm / 0.8mm

[0083] Example 1 was repeated except for the change in resin. Resin A was changed to a first polyvinyl chloride grade (Tg ~ 78°C). Resin B was changed to a second polyvinyl chloride, different from the first grade (Tg ~ 78°C), and the temperature of both resin sources was set to 160°C.

[0084] Finally, a 165 cm long microcatheter 5 (4 Fr) was obtained with two transitions between material A and material B, the two transitions having a length shorter than 30 mm.

[0085] All microcatheters obtained were tested and showed compliance performance results for resistance to breakage. Reference numerals

[0086] 1: Extruder / 2: Barrel / 3: Screw drive motor / 4: Hopper / 5: Feed pipe / 11: Die member / 12: Mandrel / 13: Central cavity / 14: Commutator element / 15: Inflow channel.

Claims

1. An extruder (1) for thermoplastic hybrid micro-ducts, comprising: - an extrusion die, the extrusion die comprising a die member (11) and a mandrel (12) arranged along the same direction as the die member (11); - at least two resin sources; - a commutator element (14) adjoining the extrusion die and comprising at least one inflow channel (15) opening on the mandrel (12); and wherein the commutator element (14) slides on the extrusion die to allow a resin source selected from the at least two resin sources to flow to the die member (11) through an extrusion channel defined by the die member (11), the mandrel (12) and the opening of the inflow channel (15) on the mandrel (12); and The extrusion channel and the inflow channel (15) together have a width of less than 20 mm. 3 , preferably less than 15mm 3 The volume V in .

2. The extruder (1) according to claim 1, wherein: The commutator element (14) slides rotationally on the extrusion die about the extrusion die axis.

3. The extruder (1) according to claim 2, wherein: The extruder (1) comprises three resin sources.

4. The extruder (1) according to claim 1, wherein: The commutator element (14) slides longitudinally on the extrusion die.

5. The extruder (1) according to any one of claims 1 to 5, wherein: The sizes of the mould member (11) and the mandrel (12) are selected from the following pairs: 0.4 / 0.15; 0.6 / 0.25; 0.8 / 0.4; 1 / 0.6; 1.2 / 0.8; 1.4 / 1; 1.6 / 1.2; 1.8 / 1.4; 2 / 1.6; 2.2 / 1.8; 0.8×1.2 / 0.6; 0.6×1 / 0.4; 1×1.4 / 0.8; 1.2×1.6 / 1; 1.5×1.9 / 1.2; 1.8×2.2 / 1.

5.

6. The extruder (1) according to any one of claims 1 to 5, wherein: The extrusion die comprises two mandrels 12 .

7. The extruder (1) according to claim 6, wherein: The dimensions of the mold member (11), the first mandrel (12) and the second mandrel (12) are selected from the following triad: 0.6 / 0.15 / 0.15; 1 / 0.4 / 0.4; 1.4 / 0.6 / 0.4；1.8 / 0.8 / 0.6； 2.2 / 1 / 0.8；0.8×1.2 / 0.4 / 0.4；1×1.4 / 0.6 / 0.4； 1.5×1.9 / 0.8 / 0.4。 8. The extruder (1) according to any one of claims 1 to 7, wherein: The mandrel (12) has a central cavity (13) extending in an axial direction, and the central cavity (13) of the mandrel (12) is connected to a gas source.

9. A method for extruding a thermoplastic hybrid microcatheter, comprising: - the diverter element (14) of the extruder (1) according to any one of claims 1 to 8 is positioned to allow flow from a first resin source to the mould member (11); - Extruding a microcatheter of a predetermined length; - sliding the diverter element (14) to allow flow from a second resin source to the mould member (11); as well as - Extruding a microcatheter of a predetermined length.

10. The method for extruding a thermoplastic hybrid micro-catheter according to claim 9, wherein: Extrusion speed is included at 30mm.s -1 and 200mm.s -1 between.

11. A microcatheter obtained by the method according to claim 9 or 10, wherein: The thermoplastic resin used is selected from: - polypropylene and a mixture of polypropylene and thermoplastic polyurethane in a weight ratio comprised between 20:80 and 80:20; - polyamides and polyamide-polyester block copolymers; or - Two different types of PVC.

12. The microcatheter according to claim 11, wherein: The transition length between the two resins is below 25 mm, preferably below 20 mm.

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