Absorbable surgical suture and preparation method thereof

Abstract

The invention relates to an absorbable surgical suture and a preparation method thereof, the surgical suture takes a bioabsorbable polymer as a main body material, and the bioabsorbable polymer comprises the following raw materials: a polyglycolide copolymer, a function enhancer and an optional coloring agent, polymeric monomers of the polyglycolide copolymer comprise glycolide and comonomers selected from one or more of lactide, caprolactone, trimethylene carbonate and p-dioxanone, and the function enhancer is selected from at least one of a carbodiimide compound, an oxazoline compound, an isocyanate compound and an epoxy compound. By adding a small amount of function enhancer into the polyglycolide copolymer, the mechanical retentivity of the polymer is enhanced, the degradation time of the polymer is not affected, and compared with the prior art, the surgical suture has better fracture strength retentivity and stability.

Description

Technical Field

[0001] The invention relates to the technical field of modified polyglycolide, in particular to an absorbable surgical suture and a preparation method thereof. Background Art

[0002] Absorbable surgical sutures are a type of surgical suture with important application prospects. Polyglycolide (PGA) has good biocompatibility, no inhibitory reaction to the human body and good degradability. PGA fiber is one of the earliest synthetic fibers used for absorbable surgical sutures, but PGA fiber has disadvantages such as short degradation cycle, rough thread body and high hardness, which limit its application in surgical sutures.

[0003] Surgical sutures with modified polyglycolide as the main material, for example, glycolide-lactide copolymer or glycolide-trimethylene carbonate copolymer as the main material, can extend their degradation time and improve the softness of the harness. However, due to the reduced crystallinity and relatively low glass transition temperature, the tensile strength is low, and the breaking strength retention (BSR) cannot meet the requirements of some application scenarios. Summary of the Invention

[0004] The purpose of the present invention is to solve the above problems and provide an absorbable surgical suture and a preparation method thereof. The main material is a bioabsorbable polymer. By adding a small amount of functional enhancer, the mechanical retention of the polymer is enhanced without affecting the degradation time of the polymer. The prepared surgical suture has good breaking strength retention and stability.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A first object of the present invention is to provide a method for preparing an absorbable surgical suture, the method comprising:

[0007] adding the bioabsorbable polymer into a spinning machine for melt spinning to obtain fibers;

[0008] Weaving the obtained fibers to obtain a braided yarn;

[0009] The braided wire is immersed in the coating liquid, and then dried and sterilized to obtain the surgical suture;

[0010] The raw materials of the bioresorbable polymer include: polyglycolide copolymer, a functional enhancer, and an optional colorant, wherein the polymerization monomers of the polyglycolide copolymer include glycolide and one or more comonomers selected from lactide, caprolactone, trimethylene carbonate (TMC), and para-dioxanone (PDO), and the functional enhancer is selected from at least one of carbodiimide compounds, oxazoline compounds, isocyanate compounds, and epoxy compounds.

[0011] Furthermore, based on the total moles of the polymerized monomers, the polymerized monomers include at least 60 mol% glycolide.

[0012] Furthermore, based on the total weight of the polymerized monomers, the added amount of the functional enhancer is 0.01 to 0.5 wt %, and the added amount of the colorant is 0 to 0.5 wt %.

[0013] Furthermore, the colorant is a blue colorant or a purple colorant.

[0014] Further preferably, the functional enhancer is of polymer grade with a molecular weight of 4,000 to 30,000.

[0015] Furthermore, the preparation method of the bioabsorbable polymer comprises:

[0016] (a) melt-polymerizing glycolide and one or more comonomers selected from lactide, caprolactone, trimethylene carbonate, and p-dioxanone to obtain a polyglycolide copolymer;

[0017] (b) mixing the polyglycolide copolymer, the functional enhancer, and the optional colorant in an extruder and then extruding and granulating the mixture to obtain the bioabsorbable polymer.

[0018] Furthermore, the particle size of the bioabsorbable polymer is 1.5 to 3 mm.

[0019] Furthermore, the bioabsorbable polymer has a melt index of 1 to 50 g / 10 min at 230° C. and 2.16 kg.

[0020] Furthermore, the intrinsic viscosity of the bioabsorbable polymer is greater than or equal to 1.2 dL / g.

[0021] Furthermore, the weight average molecular weight of the bioabsorbable polymer is 15w-25w, and the molecular weight distribution is 1.4-1.5.

[0022] Furthermore, the above step (a) specifically includes:

[0023] (1) adding glycolide, comonomer, catalyst and initiator under a protective gas atmosphere at 60-80° C. and normal pressure, stirring and mixing uniformly to obtain a mixed material;

[0024] (2) raising the temperature to react the mixture at 120-170° C. for 3-7 hours to obtain a prepolymer;

[0025] (3) Lowering the pressure of the reaction system and increasing the temperature, allowing the prepolymer to react at Tm-30°C to Tm+10°C and a vacuum degree of 30 to 100 Pa for 3 to 12 hours to obtain a polyglycolide copolymer, where Tm is the melting temperature of the polyglycolide copolymer.

[0026] Furthermore, the catalyst is an inorganic non-metallic catalyst, a tin catalyst, a zinc catalyst or an aluminum catalyst.

[0027] Furthermore, based on the total mass of the polymerized monomer, when the catalyst is an inorganic non-metallic catalyst, the amount of the inorganic non-metallic catalyst added is 0.01 to 1 wt%; when the catalyst is a tin catalyst, the concentration of Sn is ≤600 ppm; when the catalyst is a zinc catalyst, the concentration of Zn is ≤1500 ppm; when the catalyst is an aluminum catalyst, the concentration of Al is ≤5000 ppm.

[0028] Furthermore, based on the total mass of the polymerizable monomers, the added amount of the initiator is 0.01 to 2 wt%.

[0029] Furthermore, the initiator is selected from one or more of monohydric alcohols or dihydric alcohols.

[0030] More preferably, the initiator is selected from one or more of n-propanol, isopropanol, n-butanol, isobutanol and the like.

[0031] Furthermore, during the spinning process: the spinning temperature is Tm-10°C to Tm+25°C, the melting screw adopts 4 to 8 zones for temperature control, and the temperature difference between two adjacent zones is 5 to 15°C.

[0032] Furthermore, during the spinning process: the spinneret temperature is Tm+5°C to Tm+30°C, the spinneret aperture is 0.2 to 0.3 mm, the spinneret aspect ratio is 2 to 10, the number of spinneret holes is 12 to 48 holes, the single filament fineness is 2 to 4D, and the assembly pressure is 5 to 20 MPa.

[0033] Furthermore, during the spinning process: the number of hot rollers is 2 to 6 pairs, the spinning speed is 1000 to 3000 m / min, and the drafting ratio is 2 to 8 times.

[0034] Furthermore, during the spinning process: the side blowing speed is 0 to 3 m / min, the side blowing temperature is Tg-20°C to Tg, the slow cooler temperature is Tc to Tm, the slow cooler height is 5 to 30 cm, and the air duct height is 1.5 to 2.5 m.

[0035] Wherein, Tm is the melting temperature of the bioabsorbable polymer, Tg is the glass transition temperature of the bioabsorbable polymer, and Tc is the crystallization temperature of the bioabsorbable polymer.

[0036] Furthermore, during the immersion treatment, the temperature of the coating liquid is 50-60° C., and the immersion time is 10-30 seconds.

[0037] Furthermore, the coating liquid is a solution containing poly(lactide-glycolide) (PLGA) and an organic solvent, the lactide content in the poly(lactide-glycolide) is 60-90 mol%, and the organic solvent is one or more selected from acetone, ethyl acetate, chloroform, dichloromethane, DMF, etc.

[0038] More preferably, the organic solvent is one or more of acetone and ethyl acetate.

[0039] Furthermore, in the coating liquid, the concentration of the poly(lactide) is 3 to 6 g / L; the intrinsic viscosity of the poly(lactide) is 0.2 to 1.0 dL / g; and the weight-average molecular weight of the poly(lactide) is 2 to 15w.

[0040] The second object of the present invention is to provide an absorbable surgical suture, which is prepared using the above preparation method.

[0041] Compared with the prior art, the present invention has the following advantages:

[0042] 1. The present invention prepares a surgical suture with good breaking strength retention and stability by adding a small amount of functional enhancer to the polyglycolide copolymer to enhance the mechanical retention of the polymer.

[0043] 2. The present invention improves the spinning process and increases the stability of the melt spinning process by controlling the operating parameters, so that the obtained fibers have both softness and mechanical strength.

[0044] 3. The present invention uses PLGA with lactide as the main component as the coating material, which has better compatibility and adhesion with the wire, and further improves the mechanical properties of the wire. DETAILED DESCRIPTION

[0045] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several variations and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0046] The surgical suture provided by the present invention is mainly made of a bioabsorbable polymer. The raw materials of the bioabsorbable polymer include: a polyglycolide copolymer, a functional enhancer, and an optional colorant. The monomers of the polyglycolide copolymer include glycolide and one or more comonomers selected from lactide, caprolactone, trimethylene carbonate, and p-dioxanone. The functional enhancer is selected from at least one of carbodiimide compounds, oxazoline compounds, isocyanate compounds, and epoxy compounds. By adding a small amount of the functional enhancer to the polyglycolide copolymer, the mechanical retention of the polymer is enhanced without affecting the degradation time of the polymer. The resulting surgical suture has good breaking strength retention and stability.

[0047] Furthermore, in the polyglycolide copolymer, based on the total moles of the polymerized monomers, the polymerized monomers include at least 60% mol of glycolide; further preferably, the polymerized monomers include 70-90% mol of glycolide and 10-30% mol of comonomers, so that the polyglycolide copolymer has good mechanical properties and a suitable melting point.

[0048] Furthermore, in the bioabsorbable polymer, based on the total weight of the polymerized monomers, the added amount of the function enhancer is 0.01 to 0.5 wt%, and the added amount of the colorant is 0 to 0.5 wt%.

[0049] The functional enhancer is preferably polymer grade with a molecular weight of 4000 to 30000, which is beneficial for maintaining the chemical stability of the bioabsorbable polymer. More preferably, the functional enhancer is polycarbodiimide.

[0050] In one embodiment, a method for preparing a bioabsorbable polymer comprises:

[0051] (a) melt-polymerizing glycolide and one or more comonomers selected from lactide, caprolactone, trimethylene carbonate, and p-dioxanone to obtain a polyglycolide copolymer;

[0052] (b) mixing the polyglycolide copolymer, the functional enhancer, and the optional colorant in an extruder and then extruding and granulating the mixture to obtain the bioabsorbable polymer, wherein the particle size of the bioabsorbable polymer is 1.5 to 3 mm.

[0053] The extruder temperature is above the melting temperature of the polyglycolide copolymer, and the time it takes for the material to pass through the extruder is controlled within 5 minutes, preferably within 3 minutes. Compared to the size of granules obtained by conventional extrusion granulation (>5 mm), the granules obtained by granulation in this embodiment have a smaller particle size, which facilitates feeding in the subsequent spinning process and is less likely to cause blockage of the screw in the spinning equipment. More importantly, during the heating process, the polymer melts faster and is heated more evenly. However, if the particle size is too small, the bulk density will be too high, which may cause bridging in the silo.

[0054] Furthermore, the above step (a) specifically includes:

[0055] (1) adding glycolide, comonomer, catalyst and initiator under a protective gas atmosphere at 60-80° C. and normal pressure, stirring and mixing uniformly to obtain a mixed material;

[0056] (2) raising the temperature to react the mixture at 120-170° C. for 3-7 hours to obtain a prepolymer;

[0057] (3) Lowering the pressure of the reaction system and increasing the temperature, allowing the prepolymer to react at Tm-30°C to Tm+10°C and a vacuum degree of 30 to 100 Pa for 3 to 12 hours to obtain a polyglycolide copolymer, where Tm is the melting temperature of the polyglycolide copolymer.

[0058] Wherein, the catalyst is an inorganic non-metallic catalyst, a tin catalyst, a zinc catalyst or an aluminum catalyst.

[0059] Furthermore, based on the total weight of the polymerized monomers, when the catalyst is an inorganic non-metallic catalyst, the amount of the inorganic non-metallic catalyst added is 0.01 to 1 wt %. When the catalyst is a tin catalyst, the Sn concentration is ≤ 600 ppm. When the catalyst is a zinc catalyst, the Zn concentration is ≤ 1500 ppm. When the catalyst is an aluminum catalyst, the Al concentration is ≤ 5000 ppm. By controlling the amount of metal catalyst added, the metal content in the bioabsorbable polymer / surgical suture can be controlled.

[0060] In the present invention, the prepared bioabsorbable polymer has the following properties: melt index 1-50 g / 10 min, 230° C., 2.16 kg, intrinsic viscosity ≥1.2 dL / g, weight average molecular weight 15w-25w, and molecular weight distribution 1.4-1.5.

[0061] The present invention also provides a method for preparing a surgical suture, the method comprising the following steps:

[0062] S1. Spinning process: spinning the bioabsorbable polymer to obtain fibers;

[0063] S2, weaving process: weaving the fibers obtained in step S1 to obtain a braided yarn;

[0064] S3, coating process: the braided wire obtained in step S2 is immersed in the coating liquid, and after the immersion treatment, it is dried and sterilized to obtain the surgical suture thread.

[0065] Furthermore, the spinning process includes one or more of the following features:

[0066] Spinning temperature is Tm-10℃~Tm+30℃, melting screw temperature is controlled in 4 to 8 zones, screw aspect ratio is 25 to 35, screw diameter is 20 to 35mm;

[0067] The spinneret temperature is Tm+5°C to Tm+30°C, the spinneret aperture is 0.2 to 0.3 mm, the spinneret aspect ratio is 2 to 10, the number of spinneret holes is 12 to 48, the total fineness / the number of spinneret holes (i.e., the single filament fineness) is 2 to 4D, and the assembly pressure is 5 to 20 MPa.

[0068] The side blowing speed is 0 to 3 m / min, the side blowing temperature is Tg-20℃ to Tg, the slow cooling device temperature is Tc to Tm, the slow cooling device height is 5 to 30 cm, the air duct height is 1.5 to 2.5 m, the number of hot rollers is 2 to 6 pairs, the spinning speed is 1000 to 3000 m / min, and the drafting ratio is 2 to 8 times.

[0069] Wherein, Tm is the melting temperature of the bioabsorbable polymer, Tg is the glass transition temperature of the bioabsorbable polymer, and Tc is the crystallization temperature of the bioabsorbable polymer.

[0070] The modified polyglycolide synthesized by melt copolymerization has a high melting point and is prone to instability during the melt spinning process. In particular, as an improvement:

[0071] 1) The melting screw adopts 4 to 8 zone temperature control, that is, at least 4 zones are used for temperature control, and the temperature difference between two adjacent zones is 5 to 15 ° C, which reduces the residence time of the polymer in the high temperature section without affecting the transportation of the polymer;

[0072] For example, the heating temperature of zone 1 is 200-215°C, the heating temperature of zone 2 is 220-235°C, the heating temperature of zone 3 is 230-240°C, and the heating temperature of zone 4 is 240-250°C.

[0073] 2) Controlling the number of spinneret holes to 12 to 48 and the single filament fineness to 2 to 4D reduces the risk of melt blockage during the spinning process and improves the uniformity of the single filament. The obtained fiber has both softness and mechanical strength, and the yield can be above 90%.

[0074] 3) 2 to 6 pairs of heated rollers, with a temperature range of Tg to Tc. At a constant spinning speed and total fineness, multi-stage heated roller stretching can more easily ensure fiber strength and yield, while avoiding fiber breakage and lint during the spinning process. Preferably, for a total fineness of 40 to 100D, 4 to 6 pairs of heated rollers are used, and for a total fineness of 100 to 192D, 2 to 4 pairs of heated rollers are used.

[0075] In the present invention, the prepared fiber has the following properties: strength of 3.5-8.5 cN / dtex, total fineness of 40-192D, strength CV value ≤ 5%; and yield of more than 90%.

[0076] Furthermore, the above-mentioned weaving process can adopt a conventional weaving process and be weaved according to the common specifications of absorbable surgical sutures, for example, weaving into braided wires with specifications of 2, 1, 0, 2-0, 3-0, 4-0, 5-0, 6-0, 7-0, 8-0, 9-0, and 10-0.

[0077] Furthermore, the coating process includes one or more of the following features:

[0078] Adopt dipping method: coating liquid temperature is 50-60℃, dipping time is 10-30 seconds;

[0079] PLGA is used as the coating material, with a lactide (LA) content of 60-90% mol, an intrinsic viscosity of 0.2-1.0 dL / g, and a weight-average molecular weight of 2-15w. The wire is coated after the PLGA is dissolved in an organic solvent; the concentration is 3-6 g / L, and the organic solvent can be acetone, ethyl acetate, chloroform, dichloromethane, DMF, etc., preferably acetone and ethyl acetate.

[0080] Using PLGA with lactide as the main component as the coating material enhances the softness and surface smoothness of the wire and reduces the friction coefficient. Compared with other coatings, it has better compatibility and adhesion with the wire, further improving the mechanical properties of the wire.

[0081] Furthermore, the drying and sterilization can be performed by vacuum drying or air drying, or ethylene oxide sterilization.

[0082] In the following examples, unless otherwise specified, the reagents used are conventional commercially available products, and the methods employed are well known in the art.

[0083] In the following examples, the colorant used is D&C Purple No. 2 (1-hydroxy-4-(4-methylphenyl)amino)-9,10-anthracenedione).

[0084] Example 1

[0085] The temperature of the polymerization reactor was set at 70°C, and N2 protection was introduced. 70 mol of glycolide, 30 mol of lactide, 7.954 g of stannous chloride, and 124.5 g of isopropyl alcohol were added in sequence under normal pressure, and stirred and mixed uniformly at 130 rpm to obtain a mixture. The temperature was increased, and the mixture was reacted at 130°C for 5 hours to obtain a prepolymer. The mixture was then evacuated to 20 kPa at a rate of 5 kPa / min, and the temperature was increased to 170°C at the same time, and the reaction was continued for 1 hour. The mixture was evacuated at a rate of 5 kPa / min. to 100 Pa, and at the same time, the temperature was raised to 190° C., and the reaction was carried out for 10 hours to obtain a polymer product; the molten polymer product was introduced into a twin-screw extruder, and 0.2 wt% of dicyclohexylcarbodiimide (Shanghai test, >99%) and 0.05 wt% of a colorant (both based on the total mass of glycolide and lactide) were added and mixed, and then extruded into granules. The time for the material to pass through the twin-screw extruder was about 1 minute. The pellets were cooled and dried to finally obtain a bioresorbable polymer 1 (PGLA7030) with a particle size of 1.5 to 3 mm.

[0086] Example 2

[0087] The difference from Example 1 is that the added 0.2 wt % dicyclohexylcarbodiimide is replaced by an equal mass of polycarbodiimide (Aladdin, molecular weight 4000), and finally the bioabsorbable polymer 2 (PGLA7030) is obtained.

[0088] Example 3

[0089] The temperature of the polymerization reactor was set at 70°C, and N2 protection was introduced. 90 mol of glycolide, 10 mol of lactide, 33.68 g of diethyl zinc, and 118.9 g of isopropyl alcohol were added in sequence under normal pressure, and stirred and mixed uniformly at 130 rpm to obtain a mixture. The temperature was increased, and the mixture was reacted at 140°C for 4 hours to obtain a prepolymer. The mixture was then evacuated to 30 kPa at a rate of 5 kPa / min, and the temperature was increased to 170°C, and the reaction was continued for 1 hour. The mixture was evacuated to 1 kPa at a rate of 5 kPa / min, and the reaction was continued for 1 hour. The mixture was evacuated to 1 kPa at a rate of 5 kPa / min, and the reaction was continued for 1 hour. / min and continue to evacuate to 100 Pa, while raising the temperature to 210°C and reacting for 5 hours to obtain a polymer product; the molten polymer product is introduced into a twin-screw extruder, and 0.5wt% N,N'-diisopropylcarbodiimide (Shanghai test, >99%) and 0.05wt% colorant (both based on the total mass of glycolide and lactide) are added and mixed, and then extrusion granulation is performed. The time for the material to pass through the twin-screw extruder is about 1 minute. The pellets are cooled and dried to finally obtain a bioresorbable polymer 3 (PGLA9010) with a particle size of 1.5 to 3 mm.

[0090] Example 4

[0091] The temperature of the polymerization reactor was set at 70°C, and N2 protection was introduced. 85 mol of glycolide, 15 mol of lactide, 22.72 g of diethyl zinc, and 120.3 g of isopropyl alcohol were added in sequence under normal pressure, and stirred and mixed at 130 rpm to obtain a mixture. The temperature was increased, and the mixture was reacted at 130°C for 5 hours to obtain a prepolymer. The mixture was then evacuated to 30 kPa at a rate of 5 kPa / min, and the temperature was increased to 170°C, and the reaction was continued for 1 hour. The mixture was evacuated to 1 kPa at a rate of 5 kPa / min, and the reaction was continued for 1 hour. The vacuum was continued to be applied to 100 Pa at a rate of a / min, and the temperature was raised to 200°C. The reaction was carried out for 8 hours to obtain a polymer product. The molten polymer product was introduced into a twin-screw extruder, and 0.1 wt% polycarbodiimide (Aladdin, molecular weight 4000) and 0.05 wt% colorant (both based on the total mass of glycolide and lactide) were added and mixed, and then extruded and granulated. The material passed through the twin-screw extruder for about 1 minute. The pellets were cooled and dried to finally obtain bioresorbable polymer 4 (PGLA8515) with a particle size of 1.5 to 3 mm.

[0092] Example 5

[0093] The temperature of the polymerization reactor was set at 70°C, and N2 protection was introduced. 75 mol of glycolide, 25 mol of trimethylene carbonate, 21.26 g of diethyl zinc, and 112.5 g of n-butanol were added in sequence under normal pressure, and stirred and mixed uniformly at 130 rpm to obtain a mixture. The temperature was increased, and the mixture was reacted at 130°C for 4 hours to obtain a prepolymer. The mixture was then evacuated to 30 kPa at a rate of 5 kPa / min, and the temperature was increased to 160°C, and the reaction was continued for 1 hour. The mixture was evacuated to 1 kPa at a rate of 5 kPa / min, and the reaction was continued for 1 hour. Pa / min rate to 100Pa, and at the same time, the temperature was raised to 190°C and the reaction was carried out for 8h to obtain a polymer product; the molten polymer product was introduced into a twin-screw extruder, and 0.5wt% L-lysine diisocyanate (Wokai, >95%) and 0.05wt% colorant (both based on the total mass of glycolide and lactide) were added and mixed, and then extrusion granulation was carried out. The time for the material to pass through the twin-screw extruder was about 1min. The pellets were cooled and dried to finally obtain bioresorbable polymer 5 (PGMC7525) with a particle size of 1.5 to 3mm.

[0094] Example 6

[0095] The temperature of the polymerization reactor was set at 70°C, and N2 protection was introduced. 90 mol of glycolide, 10 mol of trimethylene carbonate, 7.326 g of stannous chloride, and 114.6 g of n-butanol were added in sequence under normal pressure, and stirred and mixed uniformly at 130 rpm to obtain a mixture. The temperature was increased, and the mixture was reacted at 130°C for 4 hours to obtain a prepolymer. The mixture was then evacuated to 30 kPa at a rate of 5 kPa / min, and the temperature was increased to 160°C, and the reaction was continued for 1 hour. The mixture was evacuated to 1 kPa at a rate of 5 kPa / min, and the reaction was continued for 1 hour. kPa / min, the vacuum was continued to 100 Pa, and the temperature was raised to 200°C. The reaction was carried out for 7 hours to obtain a polymer product. The molten polymer product was introduced into a twin-screw extruder, and 0.2wt% polycarbodiimide (Aladdin, molecular weight 4000) and 0.05wt% colorant (both based on the total mass of glycolide and lactide) were added and mixed, and then extrusion granulation was performed. The time for the material to pass through the twin-screw extruder was about 1 minute. The pellets were cooled and dried to finally obtain bioresorbable polymer 6 (PGMC9010) with a particle size of 1.5 to 3 mm.

[0096] The performance tests of the bioabsorbable polymers prepared in Examples 1-6 are shown in Table 1 below:

[0097] Table 1 Performance tests of the bioabsorbable polymers prepared in Examples 1-6.

[0098]

[0099]

[0100] Test method:

[0101] Melt Flow Index: 1) Dry the polymer in a vacuum drying oven at 105°C for 3 hours; 2) Set the test temperature of the test instrument to 230°C and preheat the instrument; 3) After the temperature stabilizes, add 4-7g of the dried polymer to a barrel via a funnel, insert a piston into the barrel to compact the dried polymer, and heat for 4 minutes; 4) Hold the barrel under a load of 2.16kg for 10 seconds, then cut a section every 10 seconds, for a total of ten sections; 5) Weigh each sample and calculate its MFR. MFR = 600W / t (g / 10min), where W is the average mass of each section and t is the time interval between cutting each section.

[0102] Intrinsic viscosity: About 0.125 g of sample was weighed and dissolved in 25 ml of hexafluoroisopropanol. The mixture was placed in a constant temperature water bath at 25°C and measured using an Ubbelohde viscometer.

[0103] Weight average molecular weight and molecular weight distribution: measured by gel permeation chromatography (GPC).

[0104] The bioabsorbable polymers prepared in the above Examples 1-6 were spun using the following method. During the spinning process, the following conditions were met: screw aspect ratio 30, screw diameter 30 mm, spinneret aperture 0.25 mm, spinneret aspect ratio 3, spinneret hole number 24, single filament fineness 4, assembly pressure 10 MPa; side blowing speed 1 m / min, side blowing temperature was room temperature, annealer height 20 cm, annealer temperature 60°C, air duct height 2 m, number of hot rollers 4 pairs, spinning speed 1500 m / min, and drafting multiple 5 times to obtain the corresponding fibers 1-6.

[0105] For each sample, the parameters of the spinneret temperature and the melting screw are set as shown in Table 2 below:

[0106] Table 2 Parameter settings of spinneret temperature and melting screw.

[0107]

[0108]

[0109] Fibers 1-6 are braided on an automatic braiding machine to obtain braided wires 1-6 of specification #1, each of which is 16 strands.

[0110] PLGA8020 (80% molLA) with a molecular weight of 10W was used as the coating material and dissolved in ethyl acetate to obtain a coating liquid with a concentration of 5 g / L. The braided wire was immersed in the coating liquid at 55°C for about 30 seconds. After being immersed in the coating liquid, it was dried at 60°C and sterilized with ethylene oxide to obtain the corresponding shaped sutures 1-6.

[0111] Comparative Example 1:

[0112] Compared with suture 1, dicyclohexylcarbodiimide is not added during the preparation of the bioabsorbable polymer, and the remaining processes are the same as those of suture 1, thereby obtaining comparative suture 1.

[0113] Comparative Example 2:

[0114] Compared with suture line 1, no coating treatment is performed, and the remaining processes are the same as suture line 1 to obtain comparison line 2.

[0115] Comparative Example 3:

[0116] Compared with suture line 1, polycaprolactone with a molecular weight of 13W is used as the coating material, and the rest of the process is the same as suture line 1 to obtain comparison line 3.

[0117] Comparative Example 4:

[0118] Compared with suture 1, the bioabsorbable polymer 1 prepared in Example 1 was spun using the following method: during the spinning process, the spinneret holes were selected to be 60 and the single filament fineness was 1.6. The remaining processes were the same as those of suture 1, and a comparative line 4 was obtained.

[0119] The performance test results of sutures 1-6 and comparison lines 1-4 are shown in Table 3 below:

[0120] Table 3 Performance test results of sutures 1-6 and comparison lines 1-4.

[0121]

[0122] Test method:

[0123] Breaking strength and elongation at break: tested according to GB / T 14344-2022 "Test method for tensile properties of chemical fiber filaments".

[0124] The initial strength of the suture can be referred to Appendix B of YY1116-2020, and the strength after 14 days of in vitro degradation can be referred to YY1746-2020.

[0125] As can be seen from Table 2, the breaking strength of the suture thread 1-6 with specification #1 prepared in the embodiment of the present invention can reach 6.7 cN / dtex or above, the elongation at break can stably reach 30% or above, the initial strength reaches 59N or above, and the strength retention ratio after 14 days is 60% or above.

[0126] Comparing suture 1 / 2 and comparison line 1, adding a small amount of functional enhancer (0.2wt%) can significantly improve the breaking strength, elongation at break and initial strength of the suture. In particular, after 14 days of in vitro degradation, the strength of suture 1 / 2 can still be maintained at more than 60%, which is much higher than the strength retention ratio of comparison line 1 after 14 days. At the same addition amount, the effect of polycarbodiimide is better than that of dicyclohexylcarbodiimide.

[0127] Comparing suture line 1 and control lines 2 / 3, there is no doubt that coating treatment can improve the mechanical properties of suture lines, but the strength retention ratio of suture lines obtained with PLGA as the coating material after 14 days is significantly higher than that of suture lines obtained with polycaprolactone as the coating material.

[0128] Comparing suture 1 and comparison line 4, the breaking strength, elongation at break, initial strength and strength retention ratio after 14 days of comparison line 4 are all weaker than those of suture 1. Suture 1 is beneficial to improving the uniformity of the monofilament by selecting an appropriate number of spinneret holes and controlling the monofilament fineness, thereby improving the mechanical properties of the suture.

[0129] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A method for preparing an absorbable surgical suture, characterized in that: The preparation method comprises: adding the bioabsorbable polymer into a spinning machine for melt spinning to obtain fibers; Weaving the obtained fibers to obtain a braided yarn; The braided wire is immersed in the coating liquid, and then dried and sterilized to obtain the surgical suture; The raw materials of the bioabsorbable polymer include: polyglycolide copolymer, functional enhancer, and optional colorant, wherein the polymerization monomer of the polyglycolide copolymer includes glycolide and one or more comonomers selected from lactide, caprolactone, trimethylene carbonate, and p-dioxanone, and the functional enhancer is selected from at least one of carbodiimide compounds, oxazoline compounds, isocyanate compounds, and epoxy compounds.

2. The preparation method according to claim 1, characterized in that Based on the total moles of the polymerized monomers, the polymerized monomers include at least 60 mol% glycolide; And / or, based on the total weight of the polymerized monomers, the added amount of the functional enhancer is 0.01 to 0.5 wt%, and the added amount of the colorant is 0 to 0.5 wt%.

3. The preparation method according to claim 2, characterized in that The preparation method of the bioabsorbable polymer comprises: (a) melt-polymerizing glycolide and one or more comonomers selected from lactide, caprolactone, trimethylene carbonate, and p-dioxanone to obtain a polyglycolide copolymer; (b) mixing the polyglycolide copolymer, the functional enhancer, and the optional colorant in an extruder and then extruding and granulating the mixture to obtain the bioabsorbable polymer, wherein the particle size of the bioabsorbable polymer is 1.5 to 3 mm.

4. The preparation method according to claim 3, characterized in that The bioabsorbable polymer has a melt index of 1 to 50 g / 10 min at 230° C. and 2.16 kg; The intrinsic viscosity of the bioabsorbable polymer is greater than or equal to 1.2 dL / g; The weight average molecular weight of the bioabsorbable polymer is 15w-25w, and the molecular weight distribution is 1.4-1.

5.

5. The preparation method according to claim 3, characterized in that The step (a) specifically comprises: (1) adding glycolide, comonomer, catalyst and initiator under a protective gas atmosphere at 60-80° C. and normal pressure, stirring and mixing uniformly to obtain a mixed material; (2) raising the temperature to react the mixture at 120-170° C. for 3-7 hours to obtain a prepolymer; (3) Lowering the pressure of the reaction system and increasing the temperature, allowing the prepolymer to react at Tm-30°C to Tm+10°C and a vacuum degree of 30 to 100 Pa for 3 to 12 hours to obtain a polyglycolide copolymer, where Tm is the melting temperature of the polyglycolide copolymer.

6. The preparation method according to claim 5, characterized in that The catalyst is an inorganic non-metallic catalyst, a tin catalyst, a zinc catalyst or an aluminum catalyst; Based on the total mass of the polymerized monomers, when the catalyst is an inorganic non-metallic catalyst, the amount of the inorganic non-metallic catalyst added is 0.01 to 1 wt%; when the catalyst is a tin catalyst, the concentration of Sn is ≤600 ppm; when the catalyst is a zinc catalyst, the concentration of Zn is ≤1500 ppm; when the catalyst is an aluminum catalyst, the concentration of Al is ≤5000 ppm.

7. The preparation method according to any one of claims 1 to 6, characterized in that In the melt spinning, the spinning temperature is Tm-10°C to Tm+25°C, the melting screw adopts 4-8 zones for temperature control, the temperature difference between two adjacent zones is 5-15°C, the assembly pressure is 5-20 MPa, and Tm is the melting temperature of the bioabsorbable polymer; The spinneret temperature is Tm+5°C to Tm+30°C, the spinneret aperture is 0.2 to 0.3 mm, the spinneret aspect ratio is 2 to 10, the number of spinneret holes is 12 to 48, and the single filament fineness is 2 to 4D; The number of hot rollers is 2 to 6 pairs, the spinning speed is 1000 to 3000 m / min, and the drafting ratio is 2 to 8 times.

8. The preparation method according to any one of claims 1 to 6, characterized in that During the immersion treatment, the temperature of the coating liquid is 50-60°C and the immersion time is 10-30 seconds; The coating liquid is a solution containing poly(lactide-glycol) and an organic solvent. The lactide content in the poly(lactide-glycol) is 60-90 mol%. The organic solvent is one or more selected from acetone, ethyl acetate, chloroform, dichloromethane, and DMF.

9. The preparation method according to claim 8, characterized in that The concentration of the poly(lactide-glycol) is 3 to 6 g / L; The intrinsic viscosity of the poly(lactide-glycol) is 0.2-1.0 dL / g, and the weight average molecular weight of the poly(lactide-glycol) is 2-15w.

10. An absorbable surgical suture, characterized in that: The method is described in any one of claims 1 to 9.

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