Polymer valve leaflet material, valve leaflet, valve and preparation method thereof

Abstract

According to the high-molecular valve leaflet material, the valve leaflet, the valve and the preparation method of the high-molecular valve leaflet material, the high-molecular valve leaflet material is a polyurethane material, the tensile strength of the high-molecular valve leaflet material ranges from 35 MPa to 60 MPa, the elasticity modulus ranges from 15 MPa to 40 MPa, the softness ranges from 20 degrees to 50 degrees, and the thickness of the high-molecular valve leaflet material ranges from 0.10 mm to 0.20 mm.

Description

Polymer leaflet material, leaflet, valve and preparation method thereof Technical Field

[0001] The present application relates to the technical field of medical materials, and in particular to polymer leaflet materials, leaflets, valves and their preparation methods. Background Art

[0002] In the existing technology, the application of polymer materials in valves is becoming increasingly widespread, but the polymer materials used for valves are generally difficult to meet the requirements in terms of mechanical properties, biostability and biocompatibility at the same time. Under normal circumstances, polymer materials with excellent mechanical properties cannot meet the requirements in terms of biostability and biocompatibility at the same time, while polymer materials with excellent biostability and biocompatibility have difficulty meeting the requirements in terms of mechanical properties. At the same time, under the action of small stress, relative slippage between molecular chain segments of polymer materials is prone to occur over time, that is, creep, causing the valve leaflet size to elongate, resulting in incomplete valve leaflet closure and greater regurgitation.

[0003] Polyurethane has long been used in valve leaflet materials. Existing technologies generally seek a balance and trade-off between biocompatibility, biostability, and mechanical properties. Currently, the following two types of implantable polyurethane valve materials are making rapid progress:

[0004] The first type is PDMS-PU, which means adding PDMS to polyurethane to improve its biostability and biocompatibility. However, at the same time, the mechanical properties of polyurethane will be sacrificed to a certain extent. Through the ratio of raw materials, the material achieves a basic balance between softness and strength. Currently, the tensile strength of the polyurethane material with better performance is 35MPa and the elastic modulus is 18MPa.

[0005] The second type is POSS-PCU, which is to add cage-shaped POSS into polyurethane to improve the biostability and biocompatibility of polyurethane. The Si on the nanoparticles will be enriched on the surface of the material, which greatly improves the biocompatibility of the material. The cage-shaped POSS plays a role similar to filler, which increases the strength of polyurethane to a certain extent, but at the same time the elastic modulus increases significantly and the hardness increases significantly.

[0006] The polymer materials used for valves must not only be soft enough to adapt to the requirements of leaflet fluid mechanics, but also have sufficient strength and a high elastic modulus to improve the fatigue performance and creep resistance of the leaflets to achieve long-term durability requirements. The existing biofilm plane cutting process places very high demands on the strength and softness of the material. Since the above materials themselves cannot achieve the corresponding performance, valves made in the form of biofilms cannot be used normally. Therefore, polyurethane materials are currently reinforced with fabrics to achieve mechanical performance requirements. Technical issues

[0007] The main method of fabric reinforcement is to use the fabric to withstand stress, so that the polyurethane leaflet, which is inherently insufficient in strength, can meet the mechanical requirements of the leaflet. At the same time, the fabric will also limit the creep of the polyurethane. However, as the valve continues to open and close, the surface polyurethane will wear out over a long period of time, and after peeling, the fabric may be exposed, which may lead to problems such as thrombosis and calcification. At the same time, the point where the leaflet is subjected to the greatest force is the center of the free edge. Due to gaps in the fabric, the outermost edge is covered with polyurethane, and the outermost polyurethane cannot withstand the shear stress at the center of the free edge, which can easily cause a gap in the free edge and cause the risk of polyurethane falling off. Technical Solutions

[0008] Based on this, the present application provides a polymer leaflet material that has the biocompatibility, biostability and mechanical properties that meet the leaflet requirements.

[0009] A polymer leaflet material, which is made of polyurethane. The polymer leaflet material has a tensile strength of 35 to 60 MPa, an elastic modulus of 15 to 40 MPa, a softness of 20 to 50°, and a thickness of 0.10 to 0.20 mm.

[0010] Several optional methods are also provided below, but they are not intended to be additional limitations on the above-mentioned overall solution. They are merely further supplements or optimizations. Under the premise that there are no technical or logical contradictions, each optional method can be combined separately for the above-mentioned overall solution, or multiple optional methods can be combined.

[0011] Optionally, the permanent deformation of the polymer leaflet material is 5% to 10%.

[0012] The present application also provides a method for preparing a polymer leaflet material, comprising the following steps:

[0013] A force is applied to the polymer diaphragm to stretch the polymer diaphragm in a first direction to a target size, where the target size is 120% to 300% of the original size, and the deformation of the polymer diaphragm in a second direction is limited, where the second direction is perpendicular to the first direction. After the polymer diaphragm reaches the target size, the force is continuously applied for at least 30 minutes.

[0014] Several optional methods are also provided below, but they are not intended to be additional limitations on the above-mentioned overall solution. They are merely further supplements or optimizations. Under the premise that there are no technical or logical contradictions, each optional method can be combined separately for the above-mentioned overall solution, or multiple optional methods can be combined.

[0015] Optionally, the elongation rate of the polymer membrane is 100 mm / min to 500 mm / min.

[0016] Optionally, the elongation rate of the polymer membrane is 100 mm / min to 200 mm / min.

[0017] Optionally, the target size of the polymer membrane is 150% to 200% of the original size.

[0018] Optionally, after the polymer membrane reaches the target size, the force is continuously applied for 30 to 180 minutes.

[0019] Optionally, the thickness of the polymer film before stretching is 0.15 to 0.40 mm.

[0020] Optionally, the thickness of the polymer film before stretching is 0.15 to 0.30 mm.

[0021] Optionally, the polymer film before stretching has a tensile strength of 20 to 35 MPa, an elastic modulus of 10 to 30 MPa, a softness of 10 to 20°, and a permanent deformation of 10% to 40%.

[0022] Optionally, the polymer membrane before stretching is prepared by a casting molding process and is made of polyurethane.

[0023] Optionally, the polymer membrane is in a planar or curved shape during the stretching process.

[0024] Optionally, during the stretching process, two opposite side edges of the polymer membrane are connected to each other to form a circumferentially closed cylindrical shape.

[0025] Optionally, the two opposite side edges are connected to each other in an integral manner or indirectly via a connecting piece.

[0026] Optionally, in the indirect connection mode, the span of the polymer membrane in the cylindrical circumferential direction is at least half a circumference, and the remaining portion is provided by the connecting member.

[0027] Optionally, the polyurethane molecular chain includes a hard segment and a soft segment, wherein the soft segment content is 40 to 70%, and the rest is a hard segment, the soft segment is at least one of polyether diol, polycarbonate diol, polyester diol, and polysiloxane diol, and the hard segment is isocyanate, and the R value of the isocyanate is 1.0 to 1.1.

[0028] Optionally, the isocyanate is at least one of TDI, HDI, MDI, NDI, PPDI, IPDI, and XDI.

[0029] Optionally, the polyurethane molecular chain further includes a chain extender, and the chain extender is at least one of ethylene glycol, butanediol, hexanediol, octanediol, and ethylenediamine.

[0030] Optionally, the polymer membrane is planar, and the planar polymer membrane is prepared by casting in a mold, wherein the mold has a flat bottom surface and side walls standing on the bottom surface to define the boundaries of the polymer membrane.

[0031] Optionally, a polyurethane solution with a concentration of 3 wt.% to 40 wt.% is poured into a mold, and the solvent is evaporated to obtain the polymer membrane.

[0032] Optionally, the concentration of the polyurethane solution is 5 wt.% to 30 wt.%.

[0033] Optionally, the solvent of the polyurethane solution is volatilized at 30-100° C. under a nitrogen atmosphere.

[0034] Optionally, the solvent of the polyurethane solution is at least one of DMAc, DMF, DMSO, THF, and toluene.

[0035] Optionally, the polymer membrane is a cylindrical polymer membrane, and the method for preparing the cylindrical polymer membrane includes:

[0036] Step 1: Covering the surface of a cylindrical mold with a polyurethane solution and volatilizing the solvent to obtain a polyurethane film;

[0037] Step 2: repeat step 1 3 to 6 times to obtain a cylindrical polymer membrane with a predetermined thickness on the surface of the cylindrical mold.

[0038] Optionally, in step 1, the polyurethane solution is covered on the surface of the cylindrical mold, which can be achieved by at least one of coating and infiltration.

[0039] Optionally, in step 1, the cylindrical mold is continuously rotated at a speed of 1 to 30 r / min and immersed in the polyurethane solution, so that the surface of the cylindrical mold is covered with the polyurethane solution.

[0040] Optionally, in step 1, the solvent is evaporated under a nitrogen atmosphere and dried at 30-100°C.

[0041] Optionally, the cylindrical mold is a rotating body, and the generatrix of the rotating body is a straight line or a curve.

[0042] Optionally, the rotation axis of the cylindrical mold is arranged horizontally.

[0043] Optionally, the diameter of the cylindrical mold is 15 to 35 mm.

[0044] Optionally, the cylindrical polymer membrane and the cylindrical mold are soaked in water for 1 to 12 hours, and the cylindrical polymer membrane is peeled off from the surface of the cylindrical mold.

[0045] Optionally, the first direction and the second direction are coplanar and perpendicular, or in three-dimensional space, one of the two corresponds to the axial direction and the other corresponds to the circumferential direction extending around the axial direction.

[0046] Optionally, the deformation of the polymer membrane when stretched to the target size in the first direction is W1, the deformation of the polymer membrane in the second direction is W2, and W2 / W1 is less than 30%. Further preferably, W2 / W1 is less than 10%. Further preferably, W2 / W1 is less than 5%.

[0047] Optionally, the method of limiting the deformation amount of the polymer membrane in the second direction includes applying limiting forces to two opposite sides of the polymer membrane in the second direction.

[0048] Optionally, the planar polymer film is stretched using a first device, the first device comprising:

[0049] a first clamp for fixing the polymer film in a second direction;

[0050] A second clamp is used to apply a force to the polymer membrane in a first direction.

[0051] Optionally, the first clamp provides a plurality of force-applying locations for the same-side edge of the polymer film, and the spacing between the force-applying locations along the first direction is adjustable.

[0052] Optionally, the first clamp is a pressure roller.

[0053] Optionally, there are two groups of pressing rollers, and two opposite edges of the polymer membrane each correspond to a group of pressing rollers, and the axis direction of each pressing roller is parallel to the second direction.

[0054] Optionally, each group of pressing rollers includes at least two pressing rollers, the position where each pressing roller interacts with the polymer film is a contact line, and the distance between the contact lines of two adjacent pressing rollers is 50 to 200 mm.

[0055] Optionally, each pressing roller includes a fixed shaft and a rotating roller rotatably mounted on the fixed shaft.

[0056] Optionally, there are two pairs of second clamps, and two opposite edges of the polymer membrane each correspond to a second clamp. The two pairs of second clamps clamp the polymer membrane and move in opposite directions to stretch the polymer membrane in the first direction.

[0057] Optionally, each second clamp includes a plurality of clamping portions arranged at intervals, and a distance between two adjacent clamping portions is 5 to 20 mm.

[0058] Optionally, two opposite edges of the planar polymer membrane have fabric-reinforced edges, and the fabric-reinforced edges are connected to pulling lines for cooperating with the second clamp.

[0059] Optionally, the cylindrical polymer membrane is stretched using a second device, the second device comprising:

[0060] a radially expandable balloon having a cylindrical section for sheathing the tubular polymer membrane;

[0061] An infusion device for delivering fluid into the balloon.

[0062] The first direction may be understood as the circumferential direction of the cylindrical segment, and the second direction may be understood as the axial direction of the cylindrical segment.

[0063] Optionally, both axial sides of the cylindrical polymer membrane may be fixed to the outer periphery of the cylindrical segment, for example, by bonding.

[0064] Optionally, the cylindrical polymer membrane is stretched using a third device, the third device comprising:

[0065] A support column, used for housing the cylindrical polymer membrane;

[0066] two clamping members, each clamping member clamping one axial end of the polymer membrane and being used to stretch the polymer membrane in a first direction;

[0067] At least one moving ring is slidably sleeved on the support column, and at least one clamping member is arranged on the moving ring.

[0068] The first direction can be understood as the axial direction of the support column, and the second direction can be understood as the axial direction of the support column.

[0069] The cross-section of the support column is not strictly limited, and can be, for example, circular or elliptical with a smooth outer contour. The support column can be solid or hollow, as long as it provides the necessary structural strength.

[0070] Optionally, two movable rings are sleeved on the support column, and the two clamping members are respectively arranged on the corresponding movable ring.

[0071] Optionally, a movable ring is sleeved on the support column, a clamping member is fixedly arranged on the support column, and another clamping member is fixedly arranged on the movable ring.

[0072] Optionally, the support column is provided with a guide device for limiting the moving ring path to be along the axial direction of the support column.

[0073] Optionally, both axial ends of the cylindrical polymer diaphragm are provided with fabric-reinforced edges, and the fabric-reinforced edges are connected to traction lines for cooperating with the clamping member.

[0074] Optionally, the cylindrical polymer membrane is stretched using a fourth device, the fourth device comprising:

[0075] A plurality of supporting members that can be brought together or apart from each other, each supporting member acting on the inner surface of the cylindrical polymer membrane;

[0076] A driving mechanism drives at least two supporting members to move away from each other.

[0077] The present application also provides a method for preparing a polymer leaflet, comprising:

[0078] The polymer leaflet material is soaked in water for at least 4 hours, and then cut to obtain the polymer leaflet.

[0079] Several optional methods are also provided below, but they are not intended to be additional limitations on the above-mentioned overall solution. They are merely further supplements or optimizations. Under the premise that there are no technical or logical contradictions, each optional method can be combined separately for the above-mentioned overall solution, or multiple optional methods can be combined.

[0080] Optionally, the polymer leaflet material is soaked in water at 30-40°C.

[0081] Optionally, the polymer leaflet material is immersed in water at 37°C.

[0082] Optionally, the leaflet includes: a fixed edge fixedly connected to the stent, and a free edge cooperating with other leaflets to control the blood flow channel, and the polymer membrane extends in a first direction, which is parallel to the direction of the free edge of the leaflet.

[0083] Optionally, the thickness of the polymer leaflet material is 0.10 to 0.20 mm.

[0084] The present application also provides a polymer leaflet, which is prepared using the polymer leaflet preparation method.

[0085] Optionally, the tensile strength of the leaflet material is 35-60 MPa, the elastic modulus is 15-40 MPa, the softness is 20-50°, the permanent deformation is 5%-10%, and the thickness of the polymer leaflet material is 0.10-0.20 mm.

[0086] The present application also provides a polymer valve, comprising:

[0087] Stent, with a blood flow channel inside;

[0088] One or more leaflets, wherein the leaflets are made of the polymer leaflet material.

[0089] Optionally, the tensile strength of the leaflet material is 35-60 MPa, the elastic modulus is 15-40 MPa, the softness is 20-50°, the permanent deformation is 5%-10%, and the thickness of the polymer leaflet material is 0.10-0.20 mm. Beneficial effects

[0090] The present application provides a polymer leaflet material that has the biocompatibility, biostability and mechanical properties that meet the requirements of the leaflet. BRIEF DESCRIPTION OF THE DRAWINGS

[0091] FIG1 is a schematic diagram of a first device for stretching a polymer film;

[0092] FIG2 is a schematic diagram of the first device stretching the polymer membrane (the polymer membrane has been strengthened);

[0093] FIG3 a is a schematic diagram of the initial state of the polymer film stretched by the second device;

[0094] FIG3 b is a schematic diagram of the final state of stretching the polymer film by the second device;

[0095] FIG4 is a schematic diagram of a cylindrical polymer membrane cut to form leaflets;

[0096] FIG5 is a schematic diagram of a third device for stretching a polymer film;

[0097] FIG6 a is a schematic diagram of the fourth apparatus for stretching a polymer film in an initial state;

[0098] FIG6 b is a schematic diagram of the fourth apparatus at the end of stretching the polymer film.

[0099] In the figure: 110, pressure roller; 120, second clamp; 200, polymer membrane; 210, fabric reinforcement edge; 220, traction line; 300, leaflet; 310, free edge; 320, fixed edge; 400, balloon; 500, support column; 600, support member. Modes for Carrying Out the Invention

[0100] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0101] In order to better describe and illustrate the embodiments of the present application, reference may be made to one or more drawings, but the additional details or examples used to describe the drawings should not be considered as limiting the scope of the invention of the present application, any of the currently described embodiments or preferred methods.

[0102] It should be noted that when a component is referred to as being "connected" to another component, it may be directly connected to the other component or there may be an intermediate component. When a component is referred to as being "disposed on" another component, it may be directly disposed on the other component or there may be an intermediate component.

[0103] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0104] A polymer leaflet material, which is made of polyurethane. The polymer leaflet material has a tensile strength of 35-60 MPa, an elastic modulus of 15-40 MPa, a softness of 20-50°, and a thickness of 0.10-0.20 mm.

[0105] The polymer leaflet material is a polyurethane material with good biocompatibility and biostability. The biocompatibility and biostability are derived from the material itself, and this method does not change the inherent chemical properties of the material.

[0106] Based on the existing polyurethane material, the leaflet material has its tensile strength increased by stretching, thereby increasing its tolerance to force and moderately improving its elastic modulus. During the diastole-systole cycle of the heart, the force and deformation of the valve are significantly reduced. At the same time, the material's softness is significantly improved due to the decrease in thickness. After being made into leaflets, the leaflets are easier to open and close, and the fluid performance is further improved.

[0107] The permanent deformation of the polymer leaflet material is 5% to 10%.

[0108] The polymer leaflet material has good creep resistance, can recover from tensile deformation in a relatively short time, and has a small amount of permanent deformation. When used as a leaflet material, the leaflet will not be over-elongated, thereby affecting the performance of the valve.

[0109] The polymer leaflet material is anisotropic. Due to stretching, the polyurethane has hard segment orientation, which is parallel to the stretching direction. Therefore, the tear strength perpendicular to the stretching direction is significantly improved. When making the leaflet, the free edge of the leaflet is selectively parallel to the stretching direction, which can greatly improve the tear resistance of the leaflet material, greatly reduce the possibility of fatigue damage caused by free edge tearing, and thus improve the fatigue performance of the leaflet.

[0110] The leaflet material can also be used as a covering material for an artificial valve, or as a material other than the stent on an artificial valve that plays roles such as positioning, blocking, and sealing.

[0111] A method for preparing a polymer leaflet material comprises the following steps:

[0112] A force is applied to the polymer diaphragm to stretch the polymer diaphragm in a first direction to a target size, where the target size is 120% to 300% of the original size, and the deformation of the polymer diaphragm in a second direction is limited, where the second direction is perpendicular to the first direction. After the polymer diaphragm reaches the target size, the force is continuously applied for at least 30 minutes.

[0113] The preparation method of the polymer leaflet material provided in this application only performs stretching treatment after the polyurethane membrane is prepared. Without changing the good biocompatibility and biostability of the polymer membrane itself, the physical properties of the polymer leaflet material are improved by physically processing the polymer leaflet material.

[0114] The present application achieves the early realization of the slippage of the soft segment with stronger mobility through stretching, and orients the hard segment under stress through stretching, so that part of the soft segment produces a trace crystallization area due to the influence of the stretching force, and more hydrogen bonds are formed between the soft and hard segments in the stretching direction, which further limits the mobility of the soft segment chain, weakening the ability of the leaflet material to further creep, that is, improving the anti-creep performance, and avoiding the problem of valve closure and regurgitation caused by the valve being too long due to creep. In addition, the breaking force of the material itself will not be reduced by stretching, and even because of the local crystallization of the soft segment, the breaking force is increased. When the total thickness decreases, the tensile strength increases significantly, and the fatigue performance of the valve is significantly improved. At the same time, due to the decrease in thickness, the softness of the valve is improved, the opening and closing of the leaflet is smoother, and the fluid performance is significantly improved.

[0115] The deformation of polymer materials usually includes four stages in sequence. The first stage is the deformation caused by the change of bond length and bond angle within the molecular chain. This deformation occurs instantaneously, the deformation is very small, the elastic modulus is large, and it is a reversible deformation; the second stage is high elastic deformation, which is caused by the change of molecular chain conformation. This deformation requires a certain relaxation time, the deformation is large, the elastic modulus is small, and it is also a reversible deformation. At the same time, there is also a certain degree of viscous rheology; the third stage is viscous rheology, which is caused by the relative sliding between molecular chains. This deformation will develop indefinitely over time; the fourth deformation stage is permanent deformation, the relative slip between molecular chains is completed and irreversible.

[0116] The creep of polymer materials is mainly caused by the relative movement between the molecular chains within the polymer materials. The quality of the creep resistance mainly depends on the relative movement ability between the molecular chains within the polymer materials. The polymer diaphragm is made of polyurethane, which is a thermoplastic elastomer. There are soft segments and hard segments distributed in phase in the structure. The deformation under tension is achieved by the rearrangement of the soft segments and hard segments. At the moment of stress application (the first stage of deformation), the bond angles and bond lengths of the soft and hard segments of the molecular chain change, causing elastic deformation, which is recoverable. Subsequently, the conformation of the soft segment molecular chain changes (the second stage of deformation). This conformational change is also reversible. At the same time, the hard segment produces orientation (the third stage of deformation). The soft segment with strong mobility that is not restricted by the hard segment slips and produces deformation (the fourth stage of deformation). This deformation is irreversible. After the stress is released, permanent deformation occurs.

[0117] The orientation of the hard segments in the polyurethane molecular chain and the trace crystallization produced by some soft segments under tensile force both improve the creep resistance and mechanical properties of the material. Under tensile action, the soft segments with strong mobility are eliminated due to sufficient slip. In addition, due to the orientation, more hydrogen bonds are formed between the soft and hard segments in the tensile direction, which increases the difficulty of further slippage and further enhances the creep resistance of the polyurethane material.

[0118] In this application, the target size of the polymer membrane after stretching is controlled at 120%-300% of the original size, so that the hard segment orientation is fully completed (that is, the third stage of deformation is completed), eliminating the creep caused by the orientation of the hard segments of the molecular chain. At the same time, the soft segments with strong mobility fully slip, and this part of the creep is also eliminated. The further slip of the soft segments is limited by the action of hydrogen bonds between the soft segments and the hard segments, and the difficulty of the relative movement of the molecular chains increases. Therefore, after effectively eliminating the slip of the small molecule segments, the creep caused by the orientation of the hard segments after stretching is eliminated and through the action of hydrogen bonds, the leaflet material is effectively prevented from being over-elongated, while effectively improving the creep resistance and avoiding further elongation of the leaflet after implantation.

[0119] The polymer diaphragm is stretched to the target size. When the target size is less than 120% of the original size, the tensile strength increases only slightly. When the target size is greater than 300% of the original size, the tensile strength increases significantly, and the thickness of the polymer diaphragm needs to be significantly reduced to ensure softness (the elastic modulus is proportional to the cube of the thickness). If the thickness of the polymer diaphragm is too small, the originally small thickness difference will have a greater impact on the overall performance, and thus will have a greater adverse effect on the leaflet performance.

[0120] After the polymer film reaches the target size, the force is continuously applied for at least 30 minutes to ensure sufficient time for the hard segments within the polymer film to complete their orientation. Once the polymer film reaches the target size, the force is varied over the duration of the applied force to maintain the target size without further stretching.

[0121] After stretching, the polymer membrane's thickness decreases, localized microcrystallization forms between the soft segment molecular chains, and the maximum breaking force slightly increases, resulting in an increase in tensile strength. Simultaneously, due to the reduced thickness, the polymer membrane's softness is also significantly improved. Furthermore, stretching orients the molecular chains within the polymer membrane, with most tending to be parallel to the stretching direction, significantly improving the tear resistance perpendicular to that direction. Furthermore, because the easily movable macromolecular segments have already fully moved during stretching, further deformation of the material is mostly elastic, manifesting as a significant decrease in the permanent deformation of the stretched polymer membrane. Therefore, stretching can improve the performance of polymer membranes.

[0122] Under the action of tensile force, the molecular chains of the polymer membrane tend to be parallel to the force direction, and the shear resistance of the polymer membrane is greatly improved in the direction perpendicular to the tensile direction (ie, the first direction).

[0123] The polymer diaphragm is made of polyurethane. The polyurethane molecular chain has soft segments and hard segments. The soft segments and hard segments are intertwined to form physical cross-linking points. When subjected to external forces, the weak physical cross-linking points are destroyed, causing the creep that is prone to occur to occur in advance. At the same time, the orientation and hydrogen bonding after stretching further improve the creep resistance of the polymer leaflet material during use.

[0124] This application uses a polyurethane material with good biocompatibility and biostability. Through the stretching method, the tensile strength of the material is greatly increased while maintaining the same softness, and the fatigue performance is significantly improved. After stretching, the elasticity of the polyurethane material is significantly improved, the permanent deformation is greatly reduced, and the creep resistance of the material is better. At the same time, the molecular chain orientation brought about by stretching gives the material anisotropic properties, which are more suitable for the requirements of the free edge of the valve for greater shear resistance.

[0125] Compared to stereo molding, the leaflet preparation method provided in this application significantly improves the strength of polyurethane and can be prepared in the same manner as existing bioprosthetic valves. The process is mature and stable, simple to operate, and low in cost, while also achieving excellent thickness consistency. Stereo molding significantly reduces internal stress during fatigue by designing the leaflets in three dimensions, compensating for the inherent lack of strength. However, the stereo molding process requires expensive equipment and is complex. Furthermore, under the influence of gravity, the thickness is inconsistent, resulting in internal weak points. It also does not address the creep problem of polymer materials.

[0126] Compared with fabric reinforcement, the leaflet preparation method provided in the present application does not need to worry about fabric exposure caused by polyurethane wear, nor will there be problems with free edge gaps.

[0127] The elongation rate of the polymer membrane is 100 mm / min to 500 mm / min.

[0128] The elongation rate of the polymer membrane is 100 mm / min to 200 mm / min.

[0129] The target size of the polymer membrane is 150% to 200% of the original size.

[0130] After the polymer membrane reaches the target size, the force is continuously applied for 30 to 180 minutes.

[0131] The thickness of the polymer film before stretching is 0.15-0.40 mm.

[0132] The thickness of the polymer film before stretching is 0.15-0.30 mm.

[0133] The tensile strength of the polymer film before stretching is 20-35 MPa, the elastic modulus is 10-30 MPa, the softness is 10-20 degrees, and the permanent deformation is 10%-40%.

[0134] The polymer membrane before stretching is prepared by a casting molding process and is made of polyurethane.

[0135] The polymer film is in a planar or curved shape during the stretching process.

[0136] During the stretching process, two opposite side edges of the polymer film are connected to each other to form a circumferentially closed cylindrical shape.

[0137] The two opposite side edges are connected to each other in an integral manner or indirectly via a connecting piece.

[0138] In the indirect connection mode, the span of the polymer membrane in the cylindrical circumferential direction is at least half of the circumference, and the remaining portion is provided by the connecting member.

[0139] The polyurethane molecular chain includes a hard segment and a soft segment, wherein the soft segment content is 40-70% and the rest is a hard segment. The soft segment is at least one of polyether diol, polycarbonate diol, polyester diol and polysiloxane diol. The hard segment is isocyanate, and the R value of the isocyanate is 1.0-1.1.

[0140] In the polyurethane molecular chain, the soft segment content is 50%-65%.

[0141] The isocyanate is at least one of TDI, HDI, MDI, NDI, PPDI, IPDI, and XDI.

[0142] The polyurethane molecular chain also includes a chain extender, which is at least one of ethylene glycol, butanediol, hexanediol, octanediol, and ethylenediamine.

[0143] The polymer membrane is planar and is prepared by casting in a mold. The mold has a flat bottom surface and side walls standing on the bottom surface to define the boundaries of the polymer membrane.

[0144] A polyurethane solution with a concentration of 3 wt.% to 40 wt.% is poured into a mold, and the solvent is evaporated to obtain the polymer membrane.

[0145] The concentration of the polyurethane solution is 5 wt.% to 30 wt.%.

[0146] The solvent of the polyurethane solution is evaporated at 30-100°C under a nitrogen atmosphere.

[0147] The solvent of the polyurethane solution is at least one of DMAc, DMF, DMSO, toluene and tetrahydrofuran.

[0148] The polymer membrane is a cylindrical polymer membrane. The preparation method of the cylindrical polymer membrane includes:

[0149] Step 1: Covering the surface of a cylindrical mold with a polyurethane solution and volatilizing the solvent to obtain a polyurethane film;

[0150] Step 2: repeat step 1 3 to 6 times to obtain a cylindrical polymer membrane with a predetermined thickness on the surface of the cylindrical mold.

[0151] In step 1, the polyurethane solution is covered on the surface of the cylindrical mold, which can be achieved by at least one of coating and infiltration.

[0152] In step 1, the cylindrical mold is continuously rotated at a speed of 1 to 30 r / min and immersed in the polyurethane solution to achieve uniform coverage of the polyurethane solution on the surface of the cylindrical mold.

[0153] In step 1, the solvent is evaporated under a nitrogen atmosphere and dried at 30-100°C.

[0154] The finished cylindrical polymer membrane is cut into several leaflets, each of which is an integral structure. Together, the leaflets form a valve, which is sewn onto the stent. To accommodate different stent sizes, the diameter of the cylindrical mold ranges from 15 to 35 mm.

[0155] The cylindrical polymer membrane sheet, together with the cylindrical mold, is immersed in water for 1 to 12 hours, and the cylindrical polymer membrane sheet is peeled off from the surface of the cylindrical mold.

[0156] The cylindrical mold is a solid of revolution, and the generatrix of the solid of revolution is a straight line or a curve.

[0157] The rotation axis of the cylindrical mold is arranged horizontally.

[0158] The cross-section of the cylindrical mold is not limited to being circular, and can also be a graph with a smooth extension of lines such as an ellipse.

[0159] Both the first direction and the second direction are perpendicular to each other in the same plane, or in three-dimensional space, one of them corresponds to the axial direction and the other corresponds to the circumferential direction extending around the axial direction.

[0160] When the polymer membrane sheet elongates to the target size in the first direction, the deformation rate is W1 (deformation rate W1 = value of size change in the first direction / initial length), and when the polymer membrane sheet deforms in the second direction, the deformation rate is W2 (deformation rate W2 = absolute value of size change in the second direction / initial length), and W2 < W1. For example, W2 / W1 < 30%, or for example, W2 / W1 < 10%, or for example, W2 = 0.

[0161] The method of restricting the deformation amount of the polymer membrane sheet in the second direction includes applying a restricting force to two opposite sides of the polymer membrane sheet in the second direction.

[0162] In terms of control implementation, it can be controlled based on the magnitude of the deformation amount in the second direction. Optionally, when applying the restricting force, the two opposite sides of the polymer membrane sheet in the second direction are fixed, that is, the deformation amount in the second direction is maintained at zero; it can also control the change of the deformation amount in the second direction according to the first trend. For example, the first trend can be the deformation amount in the second direction per unit time. Of course, in order to adapt to the change of the deformation amount, the magnitude of the restricting force also changes accordingly.

[0163] Moreover, it can also be controlled based on the magnitude of the restricting force. Optionally, the magnitude of the restricting force is fixed or controlled according to the second trend.

[0164] For example, the second trend can be the change amount of the restricting force per unit time. When the magnitude of the restricting force is fixed, the magnitude of the deformation amount in the second direction is passively adapted. If the magnitude of the restricting force is actively adjusted, the deformation amount is actively controlled. Various means of restricting the deformation amount of the polymer membrane sheet in the second direction can be used in combination.

[0165] Referring to FIGS. 1 and 2, for the planar polymer membrane sheet, the polymer membrane sheet is fixed in the second direction;

[0166] A force is applied to the polymer membrane in a first direction, wherein the first direction is perpendicular to the second direction.

[0167] The polymer membrane is fixed in the second direction, and the polymer membrane can maintain its original size as much as possible in the second direction. A force is applied in the first direction to stretch the polymer membrane and reduce the overall thickness of the polymer.

[0168] When a force is applied to the polymer membrane in a first direction, the polymer membrane stretches in the first direction, and the measure of fixing the polymer membrane in a second direction does not prevent the stretching, but rather accommodates the stretching.

[0169] As shown in Figures 1 and 2, the angle between the first direction and the second direction is 90°. In Figure 1, the X direction is the first direction, and the Y direction is the second direction. Taking Figure 1 as an example, in this application, the first direction is the direction along the X-axis, and both left and right directions along the X-axis are the first direction. The second direction is the direction along the Y-axis, and both upward and downward directions along the Y-axis are the second direction.

[0170] 1 and 2 , a planar polymer film 200 is stretched using a first device, the first device comprising:

[0171] A first clamp for fixing the polymer film 200 in the second direction (providing the force for limiting deformation in the second direction);

[0172] a second clamp 120 for applying a force to the polymer film 200 in a first direction.

[0173] Optionally, the first clamp provides a plurality of force-applying locations for the same-side edge of the polymer film, and the spacing between the force-applying locations along the first direction is adjustable.

[0174] The adjustable spacing can be either passive following or active adjustment. When actively adjusted, it is preferably consistent with the deformation speed of the polymer diaphragm along the first direction, that is, the spacing change of the first clamp is synchronized with the deformation speed of the polymer in the first direction, ensuring that the spacing change of the first clamp neither hinders nor promotes the deformation process of the polymer diaphragm in the first direction.

[0175] The first clamp and the second clamp act on the corresponding force-applying parts in the polymer membrane respectively. For some force-applying parts, for example, the corners of a rectangular membrane, the first clamp and the second clamp may act on the force-applying parts at the same time. In this case, it is understood that one of the first clamp and the second clamp also serves as the other.

[0176] The first fixture is a pressure roller 110 . There are two groups of pressure rollers 110 . Two opposite edges of the polymer film 200 each correspond to a group of pressure rollers 110 . The axis direction of each pressure roller 110 is parallel to the second direction.

[0177] Each group of pressing rollers 110 includes at least two pressing rollers 110 . The contact line between each pressing roller 110 and the polymer film 200 is a contact line. The distance between the contact lines of two adjacent pressing rollers 110 is 5 to 20 mm.

[0178] Each pressing roller 110 includes a fixed shaft and a rotating roller rotatably mounted on the fixed shaft.

[0179] There are two pairs of second clamps 120 , with each of the two opposite edges of the polymer film 200 corresponding to a second clamp 120 . The two pairs of second clamps 120 clamp the polymer film 200 and move in opposite directions to stretch the polymer film 200 in the first direction.

[0180] Each second clamp 120 includes a plurality of clamping portions arranged at intervals, and the distance between two adjacent clamping portions is 5 to 20 mm.

[0181] The two pairs of second clamps 120 move in opposite directions but at the same speed. The sum of the movement speeds of the two pairs of second clamps 120 gives the elongation rate of the polymer film 200. For example, if the elongation rate of the polymer film 200 is 100 mm / min, the movement speed of each second clamp 120 is 50 mm / min.

[0182] Of the two pairs of second clamps, one pair of second clamps may be fixed and the other pair of second clamps may be movable, and the movement speed of the fixed second clamps corresponds to the elongation rate of the polymer film.

[0183] As shown in FIG. 2 , two opposite edges of the polymer membrane 200 have fabric-reinforced edges 210 , and the fabric-reinforced edges 210 are connected to pulling wires 220 for cooperating with the second clamp 120 .

[0184] 3a and 3b , a second device is used to stretch the cylindrical polymer membrane. The second device includes:

[0185] A radially expandable balloon 400, wherein the balloon 400 has a cylindrical section for sheathing the tubular polymer membrane;

[0186] A perfusion device for delivering fluid into the balloon 400 .

[0187] The first direction may be understood as the circumferential direction of the cylindrical segment, and the second direction may be understood as the axial direction of the cylindrical segment.

[0188] Both sides of the cylindrical polymer membrane in the axial direction can be fixed to the outer periphery of the cylindrical segment, for example, by bonding.

[0189] As shown in Figure 3a, the tubular polymer membrane 200 is sleeved on the cylindrical section of the balloon 400. The perfusion device transports fluid (which can be gas or liquid) into the balloon 400, and the balloon 400 expands radially. The polymer membrane sleeved on the cylindrical section of the balloon 400 also deforms accordingly (i.e., changes from the state of Figure 3a to the state of Figure 3b), and elongates and deforms along the circumferential direction of the cylindrical section.

[0190] 5 , a third device is used to stretch the cylindrical polymer membrane. The third device includes:

[0191] A support column 500 is used to cover the cylindrical polymer membrane;

[0192] Two clamping members, each clamping member clamps one axial end of the polymer membrane, and is used to stretch the polymer membrane in a first direction (the first direction is the N direction in the figure);

[0193] At least one moving ring is slidably sleeved on the support column, and at least one clamping member is arranged on the moving ring.

[0194] The first direction may be understood as the axial direction of the support column, and the second direction may be understood as the circumferential direction of the support column.

[0195] The cross-section of the support column is not strictly limited, and can be, for example, circular or elliptical with a smooth outer contour. The support column can be solid or hollow, as long as it provides the necessary structural strength.

[0196] The movable ring slides axially along the support column, stretching the cylindrical polymer membrane in a first direction. The support column limits the radial contraction of the polymer membrane, while the circumferential dimension of the polymer membrane remains unchanged. As shown in Figure 5, the axial length of the polymer membrane is stretched from L1 to L2.

[0197] Two movable rings are sleeved on the support column, and the two clamping members are respectively arranged on the corresponding movable rings.

[0198] A movable ring is sleeved on the support column, a clamping piece is fixedly arranged on the support column, and another clamping piece is fixedly arranged on the movable ring.

[0199] The support column is provided with a guide device which limits the moving ring path to be along the axial direction of the support column.

[0200] Both axial ends of the cylindrical polymer diaphragm are provided with fabric-reinforced edges, and the fabric-reinforced edges are connected with traction lines for cooperating with the clamping parts.

[0201] The cross section of the support column can be circular, or can be an elliptical shape or other shape with smoothly extended lines.

[0202] Optionally, the cylindrical polymer membrane is stretched using a fourth device, the fourth device comprising:

[0203] A plurality of supporting members that can be brought together or apart from each other, each supporting member acting on the inner surface of the cylindrical polymer membrane;

[0204] A driving mechanism drives at least two supporting members to move away from each other.

[0205] When the fourth device is used, the cylindrical polymer membrane is sleeved on the outer periphery of multiple supports, that is, multiple supports are located inside the cylindrical polymer membrane, and the driving mechanism drives at least two supports away from each other to stretch the polymer membrane.

[0206] Taking two support members as an example, as shown in Figures 6a and 6b, a cylindrical polymer membrane is sleeved around the outer periphery of the two support members 600. A drive mechanism (omitted in the figure) drives the two support members 600 away from each other. In the first direction (i.e., the X direction in the figure), the polymer membrane changes from size L1 to size L2. In the second direction, i.e., the Y direction, the polymer membrane maintains a fixed size.

[0207] A method for preparing a polymer leaflet, comprising:

[0208] The polymer leaflet material is soaked in water for at least 4 hours, and then cut to obtain the polymer leaflet.

[0209] When preparing the leaflet, the free edge direction of the leaflet is kept consistent with the stretching direction. Under the action of force, the hard segment of the polyurethane material will be oriented and crystallized along the stretching direction, thereby greatly improving the tear resistance in the vertical direction and greatly reducing the fatigue damage of the leaflet caused by free edge tearing.

[0210] The polymer leaflet material is immersed in water at 30-40°C.

[0211] The polymer leaflet material was immersed in water at 37°C.

[0212] When preparing the polymer leaflet, the polymer leaflet material is immersed in water at 37°C to simulate the human body environment, so that the polymer leaflet material can be fully stressed and no longer deformed after being implanted in the body.

[0213] As shown in Figures 1 and 2, the leaflet 300 includes: a fixed edge 320 fixedly connected to the stent, and a free edge 310 that cooperates with other leaflets to control the blood flow channel. The polymer membrane extends in a first direction, and the first direction is parallel to the direction of the leaflet free edge 310.

[0214] 1 and 2 , the outline of the leaflet 300 is indicated by a dotted line. The leaflet 300 is cut from the leaflet material along the dotted line at the middle portion of the leaflet material to obtain the leaflet.

[0215] Optionally, the most uniform portion in the middle of the stretched polymer film is selected for cutting.

[0216] Optionally, when cutting the leaflet, the free edge should be ensured to be consistent with the first direction, so that the force direction of the leaflet is parallel to the stretching direction of the polymer membrane.

[0217] The polymer membrane stretches in a first direction, and the molecular chains are oriented in the first direction. The first direction is parallel to the direction of the free edge of the leaflet, that is, the free edge is parallel to the extension direction of the molecular chains. When the free edge is subjected to external force, the molecular chain itself is not easy to break, and the free edge has better tear resistance. When the leaflet is fatigued, there will be no gap in the center of the free edge.

[0218] The thickness of the polymer leaflet material is 0.10-0.20 mm.

[0219] The tensile strength of the polymer leaflet material is 35-60 MPa, the elastic modulus is 15-40 MPa, the softness is 20-50 degrees, and the permanent deformation is 5%-10%.

[0220] A polymer leaflet is prepared by adopting the preparation method of the polymer leaflet.

[0221] The tensile strength of the polymer leaflet is 35-60 MPa, the elastic modulus is 15-40 MPa, the softness is 20-50 degrees, and the permanent deformation is 5%-10%.

[0222] A polymer valve, comprising:

[0223] Stent, with a blood flow channel inside;

[0224] One or more leaflets, wherein the leaflets are made of the polymer leaflet material.

[0225] The leaflet has a tensile strength of 35 to 60 MPa, an elastic modulus of 15 to 40 MPa, a softness of 20 to 50 degrees, and a permanent deformation of 5% to 10%.

[0226] The valve is composed of multiple leaflets. The multiple leaflets can be prepared separately and then connected by suturing to form leaflets. The leaflets can also be prepared together. For example, a cylindrical polymer membrane is stretched to form a membrane structure as shown in Figure 4. The cylindrical polymer membrane shown in Figure 4 can be directly cut to form multiple leaflets with an integrated structure. It can also be cut into multiple independent leaflets and connected together by suturing. The leaflets formed by cutting the cylindrical polymer membrane have a three-dimensional configuration, which can better adapt to the stent during actual use and also have better mechanical properties.

[0227] A method for preparing a polymer leaflet material comprises the following steps:

[0228] (1) dissolving the polyurethane in at least one of DMAc, DMF, DMSO, toluene, and tetrahydrofuran;

[0229] (2) Pour 30 mL to 400 mL of a polyurethane solution having a concentration of 3 wt.% to 40 wt.% into a mold, which is a square box with a bottom area of ​​200 mm*200 mm;

[0230] (3) placing the mold at 60-80°C in a dry nitrogen atmosphere for 6-24 hours to form a polyurethane film (i.e., a polymer film) with a thickness of 0.15-0.3 mm;

[0231] (4) A stretching device (first device) is used to stretch the polyurethane film, as shown in FIG1 . The polyurethane film is rectangular, wherein two opposite edges are clamped by rollers 110, respectively. The rollers 110 can limit the movement of the polyurethane film in the second direction (i.e., the Y direction). The other two edges of the polyurethane film are clamped by corresponding clamps 120, respectively. The clamps 120 move in opposite directions to stretch the polyurethane film in the first direction. The rollers 110 can roll relative to the polyurethane film to adapt to the deformation of the polyurethane film in the first direction. The stretching rate is 50 to 500 mm / min, and the stretching rates of the clamps on both sides are kept consistent. When the film is stretched to 120% to 300% of its original length, the clamps are fixed and maintained for 30 minutes to 180 minutes.

[0232] (5) When cutting the leaflets, ensure that the free edge is consistent with the first direction.

[0233] A method for preparing a polymer leaflet material comprises the following steps:

[0234] (1) dissolving the polyurethane in at least one of DMAc, DMF, DMSO, toluene, and tetrahydrofuran;

[0235] (2) placing a frame fabric (rectangular frame) in a mold, wherein the frame fabric strip width is 1 to 5 mm, and the mold is a square box with a bottom area of ​​200 mm*200 mm, and pouring 30 mL to 400 mL of a polyurethane solution with a concentration of 3 wt.% to 40 wt.% into the mold;

[0236] (3) placing the mold at 60-80°C in a dry nitrogen atmosphere for 6-24 hours to form a polyurethane film (i.e., a polymer film) with a thickness of 0.15-0.3 mm;

[0237] (4) trimming the polyurethane film to remove the polyurethane outside the frame fabric. The polyurethane film is rectangular, and the fabric at two opposite edges thereof is trimmed to accommodate the subsequent stretching process of the polyurethane. The remaining two opposite edges of the fabric serve as the fabric reinforcement edge 210;

[0238] The fabric reinforced edges 210 of the two opposite uncut edges of the polyurethane film are connected with stitches (i.e., traction lines 220), and the stitches are connected to the clamps. The stretching process is shown in Figure 2. The two opposite edges of the polyurethane film without fabric are clamped by the press roller 110 respectively. The pressure roller 110 can limit the movement of the polyurethane film in the second direction (i.e., the Y direction). The stitches connected on the other two edges of the polyurethane film are clamped by the corresponding clamps 120 respectively. The clamps 120 move in opposite directions to stretch the polyurethane film in the first direction. The pressure roller can roll relative to the polyurethane film to adapt to the deformation of the polyurethane film in the first direction; the stretching rate is 50-500mm / min, and the stretching rates of the clamps on both sides are kept consistent. When the film is stretched to 120%-300% of the original length, the clamps are fixed and maintained for 30min-180min.

[0239] (5) When cutting the leaflets, ensure that the free edge is consistent with the first direction.

[0240] A method for preparing a polymer leaflet material comprises the following steps:

[0241] (1) dissolving the polyurethane in at least one of DMAc, DMF, DMSO, toluene, and tetrahydrofuran;

[0242] (2) Immerse a cylindrical mold (15-35 mm in diameter) at a rotation speed of 1-30 r / min into the polyurethane solution;

[0243] (3) drying at 60-80°C in a dry nitrogen atmosphere;

[0244] (4) Determine the number of repetitions of steps (2) and (3) based on the thickness of the polyurethane deposited on the cylindrical mold, generally 3-6 times;

[0245] (5) Immerse the cylindrical mold in pure water for 1-12 hours to peel off the polyurethane from the surface of the cylindrical mold;

[0246] (6) As shown in FIG3a, polyurethane is put on the balloon and the balloon is inflated until the diameter increases to 120%-300% of the diameter of the cylindrical mold (i.e., reaches the state shown in FIG3b), and maintained for 30 minutes to 180 minutes.

[0247] (7) Referring to FIG. 4 , the polyurethane material is cut into leaflet shapes.

[0248] A method for preparing a polymer leaflet material comprises the following steps:

[0249] (1) dissolving the polyurethane in at least one of DMAc, DMF, DMSO, toluene, and tetrahydrofuran;

[0250] (2) Immerse a cylindrical mold (15-35 mm in diameter) at a rotation speed of 1-30 r / min into the polyurethane solution;

[0251] (3) drying at 60-80°C in a dry nitrogen atmosphere;

[0252] (4) Determine the number of repetitions of steps (2) and (3) based on the thickness of the polyurethane deposited on the cylindrical mold, generally 3-6 times;

[0253] (5) Immerse the cylindrical mold in pure water for 1-12 hours to peel off the polyurethane from the surface of the cylindrical mold;

[0254] (6) Referring to FIG. 5 , the cylindrical polymer membrane is stretched axially by a third device until the axial length of the cylindrical polymer membrane is 120% to 300% of the length before stretching, and the stretching is maintained for 30 to 180 minutes.

[0255] (7) Cut the cylindrical polymer membrane along the axial direction and flatten it.

[0256] (8) When cutting the leaflets, ensure that the free edge and the axis are in the same direction.

[0257] Example 1

[0258] A method for preparing a polymer leaflet material comprises the following steps:

[0259] (1) Synthesis of PDMS-PU (i.e., polyurethane), the block composition of which is 32.23% MDI, 11% PHMO, 44% PDMS, 10.5% BHTD, and 2.27% EDA. The tensile strength of PDMS-PU is 28 MPa, and the elastic modulus is 15 MPa;

[0260] (2) Dissolving PDMS-PU in DMAc to form a 10 wt.% polyurethane solution;

[0261] (3) Pour 100 mL of polyurethane solution into a mold (200 mm * 200 mm metal box);

[0262] (4) The mold was placed at 80°C and baked in a dry nitrogen atmosphere for 12 h to form a polyurethane film (i.e., polymer film) with a thickness of 0.23 mm;

[0263] (5) The polyurethane film is stretched. The stretching method is shown in FIG1 . The clamp stretches the polyurethane film in the left and right directions at a stretching rate of 100 mm / min. When the film is stretched to 200% of its original length, the clamp is fixed and maintained for 120 minutes.

[0264] (6) When cutting the leaflets, ensure that the free edge and the stretching direction are consistent.

[0265] Example 2

[0266] A method for preparing a polymer leaflet material comprises the following steps:

[0267] (1) Synthesis of PDMS-PU (i.e., polyurethane), the block composition of which is 32.23% MDI, 11% PHMO, 44% PDMS, 10.5% BHTD, and 2.27% EDA. The tensile strength of PDMS-PU is 28 MPa, and the elastic modulus is 15 MPa;

[0268] (2) Dissolving PDMS-PU in DMAc to form a 10 wt.% polyurethane solution;

[0269] (3) Place a frame fabric (rectangular frame) in a mold. The frame fabric strip width is 5 mm. The mold is a square box with a bottom area of ​​200 mm*200 mm. Pour 100 mL of polyurethane solution into the mold.

[0270] (4) The mold was placed at 80°C and baked in a dry nitrogen atmosphere for 12 hours to form a 0.25 mm thick polyurethane film (i.e., polymer film);

[0271] (5) Trim the polyurethane film and remove the polyurethane outside the frame fabric. The polyurethane film is rectangular, and the fabric at two opposite edges is cut to accommodate the subsequent stretching process of the polyurethane. As shown in Figure 2, the clamp stretches the polyurethane film in the left and right directions at a stretching rate of 100 mm / min. When the film is stretched to 200% of its original length, fix the clamp and maintain it for 120 minutes.

[0272] (6) When cutting the leaflets, ensure that the free edge is consistent with the stretching direction.

[0273] Example 3

[0274] A method for preparing a polymer leaflet material comprises the following steps:

[0275] (1) Synthesis of PDMS-PU (i.e., polyurethane), the block composition of which is 32.23% MDI, 11% PHMO, 44% PDMS, 10.5% BHTD, and 2.27% EDA, with a tensile strength of 28 MPa and an elastic modulus of 15 MPa;

[0276] (2) dissolving polyurethane in DMAc to form a 10 wt.% polyurethane solution;

[0277] (3) Immerse a cylindrical mold (18 mm in diameter) at a rotation speed of 5 r / min into the polyurethane solution;

[0278] (4) drying at 80°C in a dry nitrogen atmosphere;

[0279] (5) Repeat steps 2 and 3 for 3 times;

[0280] (6) Immerse the cylindrical mold in pure water for 6 hours to peel off the polyurethane from the surface of the cylindrical mold;

[0281] (7) As shown in FIG3a and FIG3b, polyurethane is put on the balloon and the balloon is inflated until the diameter increases to 200% of the diameter of the cylindrical mold and maintained for 120 minutes.

[0282] (8) Cut the polyurethane leaflet with reference to FIG4 .

[0283] Example 4

[0284] A method for preparing a polymer leaflet material comprises the following steps:

[0285] (1) Synthesis of PDMS-PU (i.e., polyurethane), the block composition of which is 32.23% MDI, 11% PHMO, 44% PDMS, 10.5% BHTD, and 2.27% EDA, with a tensile strength of 28 MPa and an elastic modulus of 15 MPa;

[0286] (2) dissolving polyurethane in DMAc to form a 10 wt.% polyurethane solution;

[0287] (3) Immerse a cylindrical mold (18 mm in diameter) at a rotation speed of 5 r / min into the polyurethane solution;

[0288] (4) drying at 80°C in a dry nitrogen atmosphere;

[0289] (5) Repeat steps 2 and 3 for 3 times;

[0290] (6) Immerse the cylindrical mold in pure water for 6 hours to peel off the polyurethane from the surface of the cylindrical mold;

[0291] (7) Referring to FIG. 5 , the cylindrical polymer membrane is stretched axially by a third device until the axial length of the cylindrical polymer membrane is 120% to 300% of the length before stretching, and the stretching is maintained for 30 to 180 minutes.

[0292] (8) Cut the cylindrical polymer membrane along the axial direction and flatten it.

[0293] (9) When cutting the leaflets, ensure that the free edge and the axis are in the same direction.

[0294] Comparative Example 1

[0295] A method for preparing a polymer leaflet material comprises the following steps:

[0296] (1) Synthesis of PDMS-PU. The block composition of polyurethane is 32.23% MDI, 11% PHMO, 44% PDMS, 10.5% BHTD, and 2.27% EDA. The tensile strength of polyurethane is 28 MPa and the elastic modulus is 15 MPa.

[0297] (2) dissolving polyurethane in DMAc to form a 10 wt.% polyurethane solution;

[0298] (3) Pour 100 mL of polyurethane solution into a mold (200 mm * 200 mm metal box);

[0299] (4) The mold was placed at 80°C and baked in a dry nitrogen atmosphere for 12 hours to form a 0.23 mm thick polyurethane film.

[0300] Performance Characterization

[0301] Characterization methods:

[0302] Thickness: Measured with a thickness gauge with an accuracy of 0.01mm. The thickness of each sample was tested 5 times and the average value was taken.

[0303] Tensile strength: tested according to ASTM D412-16 standard, and the test specimens were cut into dumbbell 2 shape.

[0304] Shear strength: Tested according to ATSM D 624-00 standard, with the test specimen cut into die C shape.

[0305] Softness: Cut the leaflet material into 10mm*50mm strips and place them symmetrically on the test bench. Adjust the position of the strips so that they droop symmetrically. Connect the center point and one end of the strip to form a straight line, and measure the angle between the straight line and the horizontal line.

[0306] Permanent deformation: Cut the leaflet material according to ASTM D412-16 Dumbbell Type 2, and mark two straight lines on the narrow side of the dumbbell film strip with a spacing of 30 mm. Set the crosshead speed to 500 mm / min, and stop and remove the film strip when the marked lines are stretched to 60 mm. After the film strip has been allowed to stand for 10 minutes, measure the distance l between the gauge lengths. The permanent deformation is (l-30) / 30.

[0307] EOA (Effective Opening Area): The test is performed in accordance with ISO 5840-3:2021 standard.

[0308] Fatigue: Testing is performed in accordance with ISO 5840-1:2021.

[0309] The performance characterization results of Example 1, Example 3, and Comparative Example 1 are shown in Table 1.

[0310] Table 1

[0311] As shown in Table 1, after stretching, the tensile strength and longitudinal tear strength of the polymer film increased significantly, and the softness increased (EOA is generally related to softness, and the larger the EOA, the softer the material). The fatigue performance test was excellent.

[0312] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0313] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A polymer leaflet material, It is characterized in that The polymer leaflet material is made of polyurethane, the tensile strength of the polymer leaflet material is 35-60 MPa, the elastic modulus is 15-40 MPa, the softness is 20-50°, and the thickness of the polymer leaflet material is 0.10-0.20 mm.

2. The polymer leaflet material according to claim 1, It is characterized in that The permanent deformation of the polymer leaflet material is 5% to 10%.

3. A method for preparing a polymer leaflet material, It is characterized in that The steps include: Apply a force to the polymer membrane so that the polymer membrane is stretched to a target size in a first direction and the deformation of the polymer membrane in a second direction is limited, wherein the second direction is perpendicular to the first direction and the target size is 120% to 300% of the original size. After the polymer membrane reaches the target size, the force is continuously applied for at least 30 minutes.

4. The method for preparing the polymer leaflet material according to claim 3, It is characterized in that The elongation rate of the polymer film is 100 mm / min to 500 mm / min.

5. The method for preparing the polymer leaflet material according to claim 3, It is characterized in that The elongation rate of the polymer film is 100 mm / min to 200 mm / min.

6. The method for preparing the polymer leaflet material according to claim 3, It is characterized in that The target size of the polymer membrane is 150% to 200% of the original size.

7. The method for preparing the polymer leaflet material according to claim 3, It is characterized in that After the polymer membrane reaches the target size, the force is continuously applied for 30 to 180 minutes.

8. The method for preparing the polymer leaflet material according to claim 3, It is characterized in that The thickness of the polymer film before stretching is 0.15-0.40 mm.

9. The method for preparing the polymer leaflet material according to claim 3, It is characterized in that The thickness of the polymer film before stretching is 0.15-0.30 mm.

10. The method for preparing the polymer leaflet material according to claim 3, It is characterized in that The tensile strength of the polymer film before stretching is 20-35MPa, the elastic modulus is 10-30MPa, the softness is 10-20°, and the permanent deformation is 10%-40%.

11. The method for preparing the polymer leaflet material according to claim 3, It is characterized in that The polymer membrane before stretching is prepared by a casting molding process and is made of polyurethane.

12. The method for preparing the polymer leaflet material according to claim 3, It is characterized in that The polymer film is in a planar or curved shape during the stretching process.

13. The method for preparing the polymer leaflet material according to claim 3, It is characterized in that During the stretching process, the two opposite side edges of the polymer film are connected to each other to form a circumferentially closed cylindrical shape.

14. The method for preparing the polymer leaflet material according to claim 13, It is characterized in that The two opposite side edges are connected to each other in an integral manner or indirectly via a connecting piece.

15. The method for preparing the polymer leaflet material according to claim 14, It is characterized in that In the indirect connection mode, the span of the polymer membrane in the cylindrical circumferential direction is at least half a circumference, and the remaining part is provided by the connecting member.

16. The method for preparing the polymer leaflet material according to claim 11, It is characterized in that The polyurethane molecular chain includes hard segments and soft segments, wherein the soft segment content is 40-70% and the rest is hard segments, the soft segment is at least one of polyether diol, polycarbonate diol, polyester diol and polysiloxane diol, and the hard segment is isocyanate, and the R value of the isocyanate is 1.0-1.

1.

17. The method for preparing the polymer leaflet material according to claim 16, It is characterized in that The isocyanate is at least one of TDI, HDI, MDI, NDI, PPDI, IPDI, and XDI.

18. The method for preparing the polymer leaflet material according to claim 16, It is characterized in that The polyurethane molecular chain also includes a chain extender, which is at least one of ethylene glycol, butanediol, hexanediol, octanediol, and ethylenediamine.

19. The method for preparing the polymer leaflet material according to claim 3, It is characterized in that The polymer membrane is planar and is prepared by casting in a mold. The mold has a flat bottom surface and side walls standing on the bottom surface and defining the boundaries of the polymer membrane.

20. The method for preparing the polymer leaflet material according to claim 19, It is characterized in that A polyurethane solution with a concentration of 3wt.% to 40wt.% is poured into a mold, and the solvent is evaporated to obtain the polymer membrane.

21. The method for preparing the polymer leaflet material according to claim 19, It is characterized in that The concentration of the polyurethane solution is 5wt.% to 30wt.%.

22. The method for preparing the polymer leaflet material according to claim 20, It is characterized in that The solvent of the polyurethane solution is evaporated at 30-100°C in a nitrogen atmosphere.

23. The method for preparing the polymer leaflet material according to claim 20 or 21, It is characterized in that The solvent of the polyurethane solution is at least one of DMAc, DMF, DMSO, THF and toluene.

24. The method for preparing the polymer leaflet material according to claim 3, It is characterized in that The polymer membrane is a cylindrical polymer membrane, and the preparation method of the cylindrical polymer membrane comprises: Step 1, covering the surface of the cylindrical mold with a polyurethane solution and volatilizing the solvent to obtain a polyurethane film; Step 2, repeating step 1 3 to 6 times to obtain a cylindrical polymer membrane with a predetermined thickness on the surface of the cylindrical mold.

25. The method for preparing the polymer leaflet material according to claim 24, It is characterized in that In step 1, the polyurethane solution is covered on the surface of the cylindrical mold, which can be achieved by at least one of coating and infiltration.

26. The method for preparing the polymer leaflet material according to claim 24, It is characterized in that In step 1, the cylindrical mold is continuously rotated at a speed of 1 to 30 r / min and immersed in the polyurethane solution, so that the surface of the cylindrical mold is covered with the polyurethane solution.

27. The method for preparing the polymer leaflet material according to claim 24, It is characterized in that In step 1, the solvent is evaporated under a nitrogen atmosphere and dried at 30-100°C.

28. The method for preparing the polymer leaflet material according to claim 24, It is characterized in that The cylindrical mold is a rotating body, and the generatrix of the rotating body is a straight line or a curve.

29. The method for preparing the polymer leaflet material according to claim 24, It is characterized in that The rotation axis of the cylindrical mold is arranged horizontally.

30. The method for preparing the polymer leaflet material according to claim 24, It is characterized in that The diameter of the cylindrical mold is 15 to 35 mm.

31. The method for preparing the polymer leaflet material according to claim 24, It is characterized in that The cylindrical polymer membrane sheet and the cylindrical mold are immersed in water for 1 to 12 hours, and the cylindrical polymer membrane sheet is peeled off from the surface of the cylindrical mold.

32. The method for preparing the polymer leaflet material according to claim 3, It is characterized in that The first direction and the second direction are coplanar and perpendicular to each other, or in three-dimensional space, one of the two corresponds to an axial direction and the other corresponds to a circumferential direction extending around the axial direction.

33. The method for preparing the polymer leaflet material according to claim 3, It is characterized in that The deformation amount of the polymer film when it is stretched to a target size in the first direction is W1, the deformation amount of the polymer film in the second direction is W2, and W2 / W1<30%.

34. The method for preparing the polymer leaflet material according to claim 3, It is characterized in that The method of limiting the deformation amount of the polymer membrane in the second direction includes applying limiting forces to two opposite sides of the polymer membrane in the second direction.

35. The method for preparing the polymer leaflet material according to claim 12, It is characterized in that The planar polymer film is stretched by using a first device, wherein the first device comprises: a first clamp for fixing the polymer film in a second direction; A second clamp is used to apply a force to the polymer film in a first direction.

36. The method for preparing the polymer leaflet material according to claim 35, It is characterized in that The first clamp provides a plurality of force-applying locations for the same side edge of the polymer film, and the spacing between the force-applying locations along the first direction is adjustable.

37. The method for preparing the polymer leaflet material according to claim 35, It is characterized in that The first clamp is a pressure roller.

38. The method for preparing the polymer leaflet material according to claim 37, It is characterized in that There are two groups of pressing rollers, and two opposite edges of the polymer membrane each correspond to a group of pressing rollers, and the axis direction of each pressing roller is parallel to the second direction.

39. The method for preparing the polymer leaflet material according to claim 38, It is characterized in that Each group of pressing rollers includes at least two pressing rollers, the position where each pressing roller interacts with the polymer film is a contact line, and the distance between the contact lines of two adjacent pressing rollers is 50-200mm.

40. The method for preparing the polymer leaflet material according to claim 37, It is characterized in that Each pressing roller includes a fixed shaft and a rotating roller rotatably mounted on the fixed shaft.

41. The method for preparing the polymer leaflet material according to claim 35, It is characterized in that There are two pairs of second clamps, and two opposite edges of the polymer film each correspond to a second clamp. The two pairs of second clamps clamp the polymer film and move in opposite directions to stretch the polymer film in the first direction.

42. The method for preparing the polymer leaflet material according to claim 35, It is characterized in that Each second clamp includes a plurality of clamping parts arranged at intervals, and the distance between two adjacent clamping parts is 5 to 20 mm.

43. The method for preparing the polymer leaflet material according to claim 35, It is characterized in that Two opposite edges of the planar polymer membrane are provided with fabric-reinforced edges, and the fabric-reinforced edges are connected with traction lines for cooperating with the second clamp.

44. The method for preparing the polymer leaflet material according to claim 13, It is characterized in that The cylindrical polymer film is stretched by a second device, wherein the second device comprises: A radially expandable balloon having a cylindrical section for sheathing the tubular polymer membrane; A perfusion device is provided for delivering fluid into the balloon.

45. The method for preparing the polymer leaflet material according to claim 44, It is characterized in that Both sides of the cylindrical polymer membrane in the axial direction can be fixed to the outer circumference of the cylindrical segment.

46. ​​The method for preparing the polymer leaflet material according to claim 13, It is characterized in that The cylindrical polymer film is stretched by a third device, wherein the third device comprises: A support column, used for sleeve-mounting the cylindrical polymer membrane; Two clamping members, each clamping member clamps one axial end of the polymer membrane respectively, and is used to stretch the polymer membrane in a first direction; At least one moving ring is slidably sleeved on the support column, and at least one clamping member is arranged on the moving ring.

47. The method for preparing the polymer leaflet material according to claim 46, It is characterized in that The support column is sleeved with two moving rings, and the two clamping members are respectively arranged on the corresponding moving rings.

48. The method for preparing the polymer leaflet material according to claim 46, It is characterized in that A moving ring is sleeved on the support column, a clamping member is fixedly arranged on the support column, and another clamping member is fixedly arranged on the moving ring.

49. The method for preparing the polymer leaflet material according to claim 46, It is characterized in that The support column is provided with a guide device which limits the moving ring path to be along the axial direction of the support column.

50. The method for preparing the polymer leaflet material according to claim 46, It is characterized in that Both axial ends of the cylindrical polymer diaphragm are provided with fabric-reinforced edges, and the fabric-reinforced edges are connected with traction wires for cooperating with the clamping parts.

51. The method for preparing the polymer leaflet material according to claim 13, It is characterized in that The cylindrical polymer film is stretched by a fourth device, the fourth device comprising: A plurality of supporting members that can be brought together or away from each other, each supporting member acting on the inner surface of the cylindrical polymer membrane; A driving mechanism drives at least two supporting members to move away from each other.

52. A method for preparing a polymer leaflet, include: The polymer leaflet material as claimed in claims 1 to 2 is soaked in water for at least 4 hours and cut to obtain the polymer leaflet.

53. The method for preparing the polymer leaflet according to claim 52, It is characterized in that The polymer leaflet material is immersed in water at 30-40°C.

54. The method for preparing the polymer leaflet according to claim 52, It is characterized in that The polymer leaflet material was immersed in water at 37°C.

55. The method for preparing the polymer leaflet according to claim 52, It is characterized in that The leaflet comprises: a fixed edge fixedly connected to the support, and a free edge cooperating with other leaflets to control the blood flow channel. The polymer membrane is extended in a first direction, and the first direction is parallel to the direction of the free edge of the leaflet.

56. The method for preparing the polymer leaflet according to claim 52, It is characterized in that The thickness of the polymer leaflet material is 0.10-0.20 mm.

57. The method for preparing the polymer leaflet according to claim 52, It is characterized in that The tensile strength of the leaflet material is 35-60 MPa, the elastic modulus is 15-40 MPa, the softness is 20-50°, the permanent deformation is 5%-10%, and the thickness of the polymer leaflet material is 0.10-0.20 mm.

58. A polymer leaflet, It is characterized in that The polymer leaflet is prepared by the method for preparing the polymer leaflet as described in any one of claims 52 to 57.

59. A polymer valve, It is characterized in that include: The stent has a blood flow channel inside; One or more leaflets, wherein the leaflets are made of the polymer leaflet material as described in claims 1 to 2.

60. The polymer valve according to claim 59, It is characterized in that The tensile strength of the leaflet material is 35-60 MPa, the elastic modulus is 15-40 MPa, the softness is 20-50°, the permanent deformation is 5%-10%, and the thickness of the polymer leaflet material is 0.10-0.20 mm.

Images