Front and rear roller periodic drafting device and use method thereof

Abstract

The invention belongs to the technical field of modern textile, and discloses a front and rear roller periodic drafting device and a use method thereof. The periodic drafting device for the front roller and the rear roller comprises a front roller, a rear roller, a traction roller and a controller which are sequentially arranged, the rear roller is arranged at the rear lower position of the front roller, the axis of the rear roller is lower than the axis of the front roller and is parallel to the front roller, and a first element line at the highest position of the rear roller is higher than or equal to a second element line at the lowest position of the front roller; the axis of the traction roller is lower than the axis of the rear roller and is parallel to the rear roller. The periodic drafting device for the front roller and the rear roller can realize periodic drafting of spinning melt so as to enable nascent fibers to have barbs, can regulate and control the shapes of the barbs by controlling the speed and the speed difference of the front roller and the rear roller, and is simple in structure and suitable for industrial production.

Description

[0001] This application is a divisional application of the patent application filed on August 15, 2025, with application number 202511140811.6 and invention title "A barbed surgical suture with imaging function and its preparation method". Technical Field

[0002] This invention belongs to the field of modern textile technology and relates to a front and rear roller periodic drafting device and its usage method. Background Technology

[0003] Polylactic acid (PLA) fiber is a biodegradable green fiber made of polylactic acid. It has excellent physical properties and is a new type of biomaterial with broad application prospects. PLA fiber has good biocompatibility and biodegradability, and can be gradually decomposed into carbon dioxide and water in the body without causing any harm to the human body. Therefore, PLA fiber has great application potential in the medical field, such as making sutures and repairing tissues.

[0004] Current surgical sutures require surface cutting before use to achieve the desired suturing effect. However, this cutting process increases the risk of bacterial infection, and the sharp burrs on the surface can cause tissue trauma and reduce mechanical properties. Even with biocompatible and biodegradable surgical sutures, the degradation time is uncontrollable, potentially leaving hidden dangers within the body. Routine contrast imaging examinations, by directly delivering contrast particles into the body, can easily lead to complications and secondary tissue infections. These issues introduce numerous inconveniences and risks into surgical procedures and postoperative recovery. Summary of the Invention

[0005] In view of the shortcomings and deficiencies of the existing technology, the purpose of this invention is to provide a front and rear roller periodic drafting device and its usage method. This front and rear roller periodic drafting device can realize the periodic drafting of the spinning melt, thereby giving the nascent fiber barbs. Moreover, the shape of the barbs can be controlled by controlling the speed and speed difference of the front and rear rollers. It has a simple structure and is suitable for industrial production.

[0006] In a first aspect of the present invention, a method for preparing a barbed surgical suture with imaging function is provided, the method comprising the following steps:

[0007] S1. Mix granular low molecular weight polylactic acid and magnetic iron oxide nanocrystals uniformly to obtain the core material;

[0008] S2. The core material and the skin material are each melted into a spinning melt and then extruded through the core-skin spinneret to obtain a spinning melt. The skin material is granular high molecular weight polylactic acid.

[0009] S3. The spinning melt is wound into the front roller from the upper front of the front roller in a counterclockwise direction, then out from the bottom of the front roller, then into the rear roller in a clockwise direction, and then out from the rear side of the rear roller in a downward direction and wound onto the traction roller.

[0010] S4. Control the front roller and the rear roller to rotate for a preset time at each time interval to obtain polylactic acid nascent fibers with a barbed core structure; wherein, the rotation direction of the front roller is counterclockwise and the rotation speed is a first speed; the rotation direction of the rear roller is clockwise and the rotation speed is a second speed, the second speed being greater than the first speed;

[0011] S5. The polylactic acid nascent fiber is thermally stretched, and then the crystallinity is controlled by heat treatment to obtain polylactic acid monofilament;

[0012] S6. The polylactic acid monofilament is sterilized and dried, and then cooled and dried to obtain the barbed surgical suture.

[0013] In some embodiments of the present invention, the axis of the rear roller is lower than and parallel to the axis of the front roller, and the generatrix of the highest position of the rear roller is higher than or equal to the generatrix of the lowest position of the front roller.

[0014] In some embodiments of the present invention, the particle size of the magnetic iron oxide nanocrystals is 10~60 nm.

[0015] In some embodiments of the present invention, in step S1, the mass ratio of low molecular weight polylactic acid (L-PLLA) to magnetic iron oxide nanocrystals is (2-10):1.

[0016] In some embodiments of the present invention, in step S1 of the above preparation method, the mass ratio of L-PLLA to magnetic iron oxide nanocrystals is 9:1.

[0017] In some embodiments of the present invention, in step S1, the uniform mixing specifically involves uniform mixing in a twin-screw granulator, wherein the rotational speed of the twin-screw granulator is 260~600 r / min and the temperature is 190~210 ℃.

[0018] In some embodiments of the present invention, the molecular weight of low molecular weight polylactic acid is 50,000 to 70,000 g / mol, and the molecular weight of high molecular weight polylactic acid is 120,000 to 180,000 g / mol.

[0019] In some embodiments of the present invention, the step of melting the core material and the skin material into a spinning melt specifically involves: melting and extruding the core material at 190-210 °C, and melting and extruding the skin material at 220-240 °C.

[0020] In some embodiments of the present invention, the diameter ratio of the sheath to the core layer of the spinneret is (2-10):1.

[0021] In some embodiments of the present invention, in step S4, the first speed is 1~3m / s and the second speed is 6~12m / s.

[0022] In some embodiments of the present invention, in step S4, the time interval is 0.3 to 1 second, and the preset time is 2 to 4 times the time interval.

[0023] In some embodiments of the present invention, in step S5, the temperature of the hot stretching is 70~90°C, and the total stretching ratio of the hot stretching is 2 times.

[0024] In some embodiments of the present invention, in step S5, the heat treatment specifically involves treating at a temperature of 110~130℃ for 10~30 minutes.

[0025] In some embodiments of the present invention, in step S5 of the preparation method, sterilization and drying specifically involves drying at 90-100°C for 20-30 minutes in a sterilization oven.

[0026] In a second aspect, the present invention provides a barbed surgical suture with imaging function prepared by the above-described preparation method.

[0027] In some embodiments of the present invention, the diameter of the barbed surgical suture is 0.3~1mm.

[0028] In some embodiments of the present invention, the strength of the barbed surgical suture is 253MPa~300MPa, the crystallinity is 60~85%, and the complete degradation period is 90~170 days.

[0029] A third aspect of the present invention provides a front and rear roller periodic drafting device for drafting a spinning melt at regular time intervals to form nascent fibers with barbs. The front and rear roller periodic drafting device includes a front roller, a rear roller, a traction roller, and a controller arranged sequentially. The rear roller is positioned below and behind the front roller, and its axis is lower than and parallel to the axis of the front roller. The first generatrix at the highest position of the rear roller is higher than or equal to the second generatrix at the lowest position of the front roller. The axis of the traction roller is lower than and parallel to the axis of the rear roller.

[0030] The controller is used to control the front roller to rotate counterclockwise at a first speed at a time interval, and the rear roller to rotate in the opposite direction at a second speed for a preset time.

[0031] In some embodiments of the present invention, the controller is also used to control the surface temperature of the front roller.

[0032] In some embodiments of the present invention, the axis of the front roller is horizontal, that is, the front roller is set horizontally.

[0033] In some embodiments of the present invention, the radii of the end faces of the front roller and the rear roller are the same.

[0034] In some embodiments of the present invention, when the radii of the end faces of the front roller and the rear roller are the same, the distance between the first generatrix and the second generatrix in the vertical direction is 0-30cm.

[0035] In some embodiments of the present invention, when the radii of the end faces of the front roller and the rear roller are the same, the horizontal distance between the axes of the front roller and the rear roller is 1.5R-3R, where R is the end face radius of the front roller and the rear roller.

[0036] A fourth aspect of the present invention provides a method of using the above-described front and rear roller periodic drafting device, wherein the method of use specifically comprises:

[0037] The spinning melt is wound counterclockwise into the front roller from the upper front of the front roller, then out from the bottom of the front roller, then wound clockwise into the rear roller, and then out from the rear side of the rear roller downwards and onto the traction roller.

[0038] The front roller is controlled to rotate counterclockwise at a first speed for a preset time at a time interval, while the rear roller rotates in the opposite direction at a second speed.

[0039] In some embodiments of the present invention, the method of use further includes: before the spinning melt is wound into the front roller in a counterclockwise direction from the upper front of the front roller, controlling the surface temperature of the front roller to be higher than the room temperature and lower than the melting point of the surface material of the spinning melt.

[0040] Compared with the prior art, the present invention has the following technical effects:

[0041] (1) The preparation method provided by the present invention ingeniously achieves both pre-drafting before the spinning melt enters the front roller and drafting after entering the front roller by designing a differential speed periodic drafting method for the front and rear rollers. The pre-drafting before entering the front roller transforms the spinning melt into a coarse knot spinning melt with a bamboo-like structure, and the drafting after entering the front roller deforms the protruding part of the coarse knot spinning melt into a hook-like shape under the action of the differential speed of the front and rear rollers. This method reduces the step of secondary cutting of monofilaments and greatly reduces the number of sharp points on the surface of monofilaments. It has fewer production steps and is suitable for large-scale production.

[0042] (2) In this invention, a contrast-polymer polylactic acid (L-PLLA) material (L-PLLA / CM) formed by mixing low molecular weight L-PLLA with magnetic iron oxide nanocrystals is used as the core material, and high molecular weight L-PLLA (H-PLLA) particles are used as the skin material. After forming a melt, the material is spun through the core-spinneret. The resulting barbed surgical suture with a core-spinneret structure can not only suture wounds and promote wound healing during surgery, but also avoid direct contact between contrast particles and the wound surface during contrast examination, thereby improving safety and stability and avoiding the risk of contrast particle leakage and secondary tissue infection.

[0043] (3) In this invention, low molecular weight polylactic acid (L-PLLA) is used as the main material of the core layer and high molecular weight polylactic acid (H-PLLA) particles are used as the main material of the skin layer. After the two form a melt, they are spun through the core-spinning hole. The polylactic acid fiber obtained can utilize the difference in molecular weight between the skin layer material and the core layer material to regulate the crystallinity of the fiber by adjusting the heat treatment temperature, thereby regulating the degradation cycle of the material.

[0044] (4) The front and rear roller periodic stretching device provided by the present invention can cleverly achieve periodic stretching of the spinning melt by controlling the rotation speed of the front roller to be 0 (no rotation) to make the two have a certain speed difference, so as to make the nascent fiber have barbs. Furthermore, the shape of the barbs can be controlled by controlling the speed and speed difference of the front and rear rollers. The structure is simple and suitable for industrial production. Attached Figure Description

[0045] Figure 1 This is a schematic diagram illustrating the shape changes of the spinning melt in the preparation method of this invention;

[0046] Figure 2 This is a schematic diagram of the spinneret hole structure in an embodiment of the present invention;

[0047] Figure 3 This is a schematic diagram of the front and rear roller cycle stretching device in an embodiment of the present invention;

[0048] Figure 4This is a schematic diagram of the structure of the barbed surgical suture obtained in an embodiment of the present invention;

[0049] Figure 5 This is a schematic diagram of the core layer structure of the barbed surgical suture obtained in an embodiment of the present invention. Detailed Implementation

[0050] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0051] Unless otherwise specified below, the specifications and manufacturer information of all raw materials used in the various embodiments of this application are commercially available:

[0052] Low molecular weight polylactic acid (L-PLLA) was purchased from Xiamen Anfangxuan Industrial Co., Ltd.

[0053] High molecular weight polylactic acid (H-PLLA) was purchased from Xiamen Anfangxuan Industrial Co., Ltd.

[0054] Magnetic iron oxide nanocrystals (Fe3O4) were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0055] Tensile strength test: The tensile properties of surgical sutures were determined using a NETZSCH INSTRON 5696 universal testing machine from the United States. The clamping length was set to 100 mm and the tensile speed to 200 mm / min. Each sample was tested 5 times and the average value was taken.

[0056] Crystallinity test: The crystallinity of surgical sutures was tested using an X-ray diffractometer (Genesis XM type, EDAX, USA). The XRD test conditions were: filter: Ni, radiation source: CuKa rays, wavelength: 0.1542nm, scanning voltage: 40kV, scanning current: 40mA, scanning time: 7min, scanning speed: 3° / min, diffraction angle (2θ): 5~50° (scanning interval: 0.02°).

[0057] Degradation cycle test: The molecular weight and molecular weight distribution of the surgical sutures were measured using an Agilent PL-GPC50 gel permeation chromatograph. A 0.1 mg / mL chloroform solution was prepared as the mobile phase, the flow rate was 1.0 mL / min, and the column temperature was 40℃. The molecular weight of the fibers before and after hydrolysis (pH 5, temperature 100℃, hydrolysis time 14 days) was tested using gel permeation chromatography (GPC), and the complete degradation cycle of the fibers was calculated.

[0058] An embodiment of the first aspect of the present invention provides a method for preparing a barbed surgical suture with imaging function, the method comprising the following steps:

[0059] S1. Particulate low molecular weight polylactic acid (L-PLLA) and magnetic iron oxide nanocrystals are uniformly mixed to obtain a core layer material. The particle size of the magnetic iron oxide nanocrystals is preferably 10~60 nm. The mass ratio of L-PLLA particles to magnetic iron oxide nanocrystals is preferably (2~10):1, more preferably (8~10):1, and even more preferably 9:1. The molecular weight of H-PLLA is preferably 120000~180000 g / mol, more preferably 160000 g / mol, and the molecular weight of L-PLLA is preferably 50000~70000 g / mol, more preferably 50000 g / mol. The preferably low melt viscosity of L-PLLA allows for efficient and uniform mixing of iron oxide nanocrystals, while the preferably high molecular chain entanglement of H-PLLA improves the tensile strength, toughness, and tear resistance of the skin layer.

[0060] S2. The core material and the skin material are melted into spinning melts and then extruded through the core-skin spinneret to obtain the spinning melt. The skin material is granular high molecular weight polylactic acid.

[0061] S3. The spinning melt is wound counterclockwise into the front roller from the upper front of the front roller, then out from the bottom of the front roller, then wound clockwise into the rear roller, and then out from the rear side of the rear roller downwards and onto the traction roller.

[0062] S4. Control the front roller and the rear roller to rotate for a preset time at intervals to obtain nascent polylactic acid fibers with a barbed core structure; wherein, the rotation direction of the front roller is counterclockwise, and the rotation speed is a first speed; the rotation direction of the rear roller is clockwise, and the rotation speed is a second speed, the second speed being greater than the first speed; wherein, the first speed is preferably 1~3m / s, and the second speed is preferably 6~12m / s. The time interval is preferably set to 0.3~1s, and the preset time is preferably set to 2~4 times the time interval.

[0063] S5. The polylactic acid nascent fiber is thermally stretched, and then the crystallinity is controlled by heat treatment to obtain polylactic acid monofilament.

[0064] S6. The polylactic acid monofilament is sterilized and dried, and then cooled and dried to obtain the adjustable degradable surgical suture.

[0065] Figure 1This diagram illustrates the shape changes of the spinning melt in the preparation method of this invention. In the initial stage, the spinning melt is wound counterclockwise into the front roller from the upper front, then exits from the bottom of the front roller, and then wound clockwise into the rear roller. Finally, it exits from the rear roller and downwards, before being wound onto the traction roller. In the preparation and completion stages, the front and rear rollers and the traction roller are controlled to begin periodic operation. Because the front and rear rollers rotate at a certain speed, the spinning melt before entering the front roller is pre-stretched into a coarse, knotted spinning melt with a bamboo-like structure. On the other hand, since the rear roller rotates at a higher speed than the front roller, the low-speed movement of the front roller generates a stretching force F1, which stretches the fiber axially in the opposite direction to the fiber's movement. The high-speed movement of the rear roller generates a stretching force F2, which stretches the fiber axially in the same direction as the fiber's movement. The stretching force F1 works together to deform the protruding part of the coarse-knotted spinning melt into a hook-shaped shape under the differential speed action of the front and rear rollers. Since F2 > F1, the direction of the barbs is the same as the axial movement, and the lower part of the barbs is thinner than the upper part.

[0066] In some embodiments of the present invention, in step S1, the uniform mixing specifically involves uniform mixing in a twin-screw granulator, wherein the twin-screw granulator has a rotation speed of 260~600 r / min and a temperature of 190~210 ℃, which allows the materials to be uniformly mixed and improves the imaging effect.

[0067] In some embodiments of the present invention, in step S2, melting the core material and the sheath material into a spinning melt specifically involves: melting and extruding the core material at 190-210°C and melting and extruding the sheath material at 220-240°C to form a well-formed core-sheath structure monofilament.

[0068] In some embodiments of the present invention, the following are employed: Figure 2 The core-spinning orifice of the structure shown is composed of a core layer 1 and a skin layer 2. The ratio of the skin layer diameter d2 to the core layer diameter d1 is preferably (2~10):1, and more preferably 9:1.

[0069] In some embodiments of the present invention, in step S4, the temperature of the hot stretching is 70~90°C, and the total stretching ratio of the hot stretching is 2 times. Hot stretching makes the fibers more uniform.

[0070] In some embodiments of the present invention, in step S4, the heat treatment specifically involves treating the fiber at a temperature of 110~130℃ for 10~30 minutes. This further enhances the crystallinity of the fiber while preventing the barbs from melting, thereby stabilizing the barb structure, increasing fiber strength, and also regulating the degradation cycle.

[0071] In some embodiments of the present invention, in step S5 of the preparation method, sterilization and drying specifically involves drying at 90-100°C for 20-30 minutes in a sterilization oven. This sterilization treatment of the fiber surface facilitates direct use in subsequent surgeries.

[0072] According to an embodiment of the second aspect of the present invention, a barbed surgical suture with imaging function prepared by the above-described preparation method is provided.

[0073] like Figure 4 , 5 As shown, the barbed surgical suture has a core-skin structure, including a fibrous skin layer 8, a fibrous core layer 9, and barbs 11 distributed on the surface of the fibrous skin layer 8. Contrast particles 10, namely magnetic iron oxide (Fe3O4) nanocrystals, are uniformly distributed in the fibrous core layer 9.

[0074] The outer layer material is high molecular weight polylactic acid (H-PLLA), and the core layer material is low molecular weight polylactic acid (L-PLLA) and magnetic iron oxide nanocrystals, which are mixed and melted to form a contrast-polymer polylactic acid (L-PLLA / CM) melt as the core layer. The outer layer is composed of molten particles.

[0075] In some embodiments of the present invention, the diameter of the barbed surgical suture is 0.3~1mm.

[0076] In some embodiments of the present invention, the strength of the adjustable degradable surgical suture is 253MPa~300MPa, the crystallinity is 60~85%, and the complete degradation period is 90~170 days.

[0077] like Figure 3 As shown, in one embodiment of the third aspect of the present invention, a front and rear roller periodic drafting device is provided. This device is used to draft a spinning melt at regular intervals to form nascent fibers with barbs. The front and rear roller periodic drafting device includes a front roller 3, a rear roller 4, a traction roller 7, and a controller. The rear roller 4 is positioned below and behind the front roller 3. The axis of the rear roller 4 is lower than and parallel to the axis of the front roller 3. The first line at the highest position of the rear roller 4 is higher than or equal to the second line at the lowest position of the front roller 3. The axis of the traction roller 7 is lower than and parallel to the axis of the rear roller 4. The controller controls the front roller 3 to rotate counterclockwise at a first speed at regular intervals, while the rear roller 4 rotates in the opposite direction at a second speed simultaneously.

[0078] In some embodiments of the present invention, the controller is also used to control the heater to heat the front roller 3 so that the surface temperature of the front roller 3 is higher than the room temperature and lower than the melting point of the surface material of the spinning melt.

[0079] In some embodiments of the present invention, the surface of the front roller 3 is provided with a spiral groove with a depth of 0.05~0.2mm and a groove pitch of 5~10mm. The spiral groove on the surface of the front roller 3 is used for guiding the yarn.

[0080] In some embodiments of the present invention, the surface of the rear roller 4 is coated with a ceramic coating with a thickness of 0.1~0.3mm, and the surface roughness Ra of the coating is preferably 1.6~3.2μm. If the surface roughness of the rear roller 4 is too small, the barbs will be unevenly distributed; if the roughness is too large, the barbs will wear severely.

[0081] In some embodiments of the present invention, the distance between the first element and the second element in the vertical direction is 0~30mm.

[0082] In some embodiments of the present invention, when the radii of the end faces of the front roller and the rear roller are the same, the projection distance between the first axis and the second axis in the horizontal direction is 1.5R~3R, where R is the radius of the end faces of the front roller and the rear roller.

[0083] In some embodiments of the present invention, the first speed is 1~3m / s and the second speed is 6~12m / s.

[0084] A fourth aspect of the present invention provides a method of using the above-described front and rear roller periodic drafting device, wherein the method of use specifically comprises:

[0085] S100. The spinning melt is wound into the front roller 3 from the upper front of the front roller in a counterclockwise direction, then out from the bottom of the front roller 3, then wound into the rear roller 4 in a clockwise direction, and then out from the rear side of the rear roller 4 downwards and then wound onto the traction roller 7.

[0086] S200. Control the surface temperature of the front roller to heat to 110~130℃;

[0087] S300. Control the front roller 3 to rotate counterclockwise at a first speed for a preset time at a time interval, while the rear roller 4 rotates in the opposite direction at a second speed.

[0088] During the process of the front and rear roller cycle drafting device, the spinning melt in the process before the front roller roller is a coarse knot spinning melt 5 with a bamboo joint structure. After leaving the rear roller roller 4, it enters the process of the traction roller 7 to obtain fiber 6 with barbs.

[0089] In some embodiments of the present invention, step S100 specifically involves: introducing the spinning melt from the upper front of the front roller 3 into the spiral groove of the front roller 3 in a counterclockwise direction, then winding it out from the bottom of the front roller 3, and then winding it into the rear roller 4 in a clockwise direction under a tension of 5~20 cN, and then winding it out from the rear side of the rear roller 4 in a downward direction.

[0090] In some embodiments of the present invention, the time interval is 0.3 to 1 second, and the preset time is 2 to 4 times the time interval.

[0091] The front and rear roller cycle stretching device provided by the present invention can adjust the stretching ratio and barb shape by adjusting the first speed and the second speed.

[0092] The above technical implementation schemes will be illustrated by the following examples.

[0093] Example 1

[0094] (1) Weigh 18g of L-PLLA particles with a molecular weight of 53000g / mol and 2g of magnetic iron oxide (Fe3O4) nanocrystals, and mix them uniformly as the core material; weigh 90g of H-PLLA particles with a molecular weight of 160000g / mol as the skin material. The core material is melted in a twin-screw extruder at a speed of 350 m / min and a temperature of 190℃ for 2 min of self-stirring time, and the core and skin materials are melt-extruded at a temperature of 220℃.

[0095] (2) The skin and core melt obtained in step (1) is extruded through a skin and core spinneret with a diameter ratio of 9:1 to form a spinning melt.

[0096] (3) The spinning melt obtained in step (2) is periodically drawn by front and rear double rollers. Specifically, the surface of the front roller is provided with a spiral groove with a depth of 0.05 mm and a groove pitch of 5 mm. The diameter of both the front and rear rollers is 50 mm. The vertical distance between the first and second yarns is 10 mm. The surface of the rear roller is coated with a ceramic coating with a thickness of 0.1 mm and a surface roughness Ra of 1.6 μm. The horizontal projection distance between the axes of the front and rear rollers is 75 mm. The front roller is heated to 110°C and rotated counterclockwise at a low speed of 3 m / s, while the rear roller rotates clockwise at a high speed of 12 m / s. Every 0.3 s interval, the front and rear rollers rotate for 1 s to obtain polylactic acid nascent fibers with a barbed core structure.

[0097] (4) The polylactic acid nascent fiber obtained in step (3) is heat-stretched at 70°C with a total stretching ratio of 2 times, and then heat-treated at 110°C for 20 minutes to obtain polylactic acid monofilament.

[0098] (5) Place the polylactic acid monofilament obtained in step (4) into a high-temperature sterilization box at 90°C and dry for 20 minutes.

[0099] (6) The polylactic acid monofilament obtained in step (5) was cooled and dried to room temperature to obtain a barbed surgical suture with imaging function. Under the condition of a stretching ratio of 2, the diameter of the obtained barbed surgical suture was 0.8 mm. The tensile strength of the suture was 253 MPa and the elongation at break was 35% by the Instron universal tensile tester. The barb length was 0.1 mm and the spacing was 0.5 mm by the Korean COXEM EM-30 electron microscope. The crystallinity of the suture was 60% by the X-ray diffraction (XRD) instrument. The molecular weight of the fiber before and after hydrolysis (hydrolysis environment pH 5, temperature 100℃, hydrolysis time 14 days) was tested by gel permeation chromatography (GPC) to obtain the degradation cycle of the suture as 90 days.

[0100] Example 2

[0101] (1) Weigh 18g of L-PLLA particles with a molecular weight of 70,000 g / mol and 2g of magnetic iron oxide (Fe3O4) nanocrystals, and mix them uniformly as the core material; weigh 90g of H-PLLA particles with a molecular weight of 180,000 g / mol as the skin material. The core material is melted in a twin-screw extruder at a speed of 350 m / min and a temperature of 190 ℃ for 2 min of self-stirring time, and the core and skin materials are melt-extruded at a temperature of 220 ℃.

[0102] (2) The skin and core melt obtained in step (1) is extruded through a skin and core spinneret with a diameter ratio of 9:1 to form a spinning melt.

[0103] (3) The spinning melt obtained in step (2) is periodically drawn by front and rear double rollers. Specifically, the surface of the front roller is provided with a spiral groove with a depth of 0.05 mm and a groove pitch of 5 mm. The diameter of both the front and rear rollers is 50 mm. The distance between the first and second yarns in the vertical direction is 10 mm. The surface of the rear roller is coated with a ceramic coating with a thickness of 0.1 mm and a surface roughness Ra of 1.6 μm. The horizontal projection distance between the axes of the front and rear rollers is 150 mm. The front roller is heated to 120°C and rotated counterclockwise at a low speed of 3 m / s, while the rear roller rotates clockwise at a high speed of 12 m / s. Every 0.5 s interval, the front and rear rollers rotate for 1 s to obtain polylactic acid nascent fibers with a barbed core structure.

[0104] (4) The polylactic acid nascent fiber obtained in step (3) is heat-stretched at 70°C with a total stretching ratio of 2 times, and then heat-set at 120°C for 20 minutes to obtain polylactic acid monofilament.

[0105] (5) Place the polylactic acid monofilament obtained in step (4) into a high-temperature sterilization box at 90°C and dry for 20 minutes.

[0106] (6) The surgical suture obtained in step (5) was cooled and dried to room temperature to obtain a barbed surgical suture. Under the condition of a stretching ratio of 2, the diameter of the obtained polylactic acid monofilament was 0.8 mm. After heat treatment to improve the mechanical properties of the fiber, the tensile strength of the suture was 296 MPa and the elongation at break was 31% by tensile testing using an Instron universal tensile testing machine. The length of the barbs was 0.1 mm and the spacing was 0.4 mm by measuring the length of the barbs using a Korean COXEM EM-30 electron microscope. The crystallinity of the suture was 71% by measuring the length of the barbs using an X-ray diffractometer (XRD). The molecular weight of the fiber before and after hydrolysis (hydrolysis environment pH 5, temperature 100℃, hydrolysis time 14 days) was measured by gel permeation chromatography (GPC) to obtain the degradation cycle of the suture as 107 days.

[0107] Example 3

[0108] (1) Weigh 18g of L-PLLA particles with a molecular weight of 53000 g / mol and 2g of magnetic iron oxide (Fe3O4) nanocrystals, and mix them uniformly as the core material; weigh 90g of H-PLLA particles with a molecular weight of 160000 g / mol as the skin material. The core material is melted in a twin-screw extruder at a speed of 350 m / min and a temperature of 190℃ for 2 min of self-stirring. The core and skin materials are melt-extruded at a temperature of 220℃.

[0109] (2) The skin and core melt obtained in step (1) is extruded through a skin and core spinneret with a diameter ratio of 9:1 to form a spinning melt.

[0110] (3) The spinning melt obtained in step (2) is periodically drawn by front and rear double rollers. Specifically, the surface of the front roller is provided with a spiral groove with a depth of 0.1 mm and a groove pitch of 10 mm. The diameter of both the front and rear rollers is 60 mm. The distance between the first and second raw yarns in the vertical direction is 10 mm. The surface of the rear roller is coated with a ceramic coating with a thickness of 0.2 mm and a surface roughness Ra of 2 μm. The horizontal projection distance between the axes of the front and rear rollers is 90 mm. The front roller is heated to 130°C and rotated counterclockwise at a low speed of 3 m / s, while the rear roller rotates clockwise at a high speed of 12 m / s. Every 0.3 s interval, the front and rear rollers rotate for 1 s to obtain polylactic acid nascent fibers with a barbed core structure.

[0111] (4) The polylactic acid nascent fiber obtained in step (3) is heat-stretched at 70°C with a total stretching ratio of 2 times, and then heat-set at 130°C for 20 minutes to obtain polylactic acid monofilament.

[0112] (5) Place the polylactic acid monofilament obtained in step (4) into a high-temperature sterilization box at 90°C and dry for 20 min.

[0113] (6) The surgical suture obtained in step (5) was cooled and dried to room temperature to obtain a barbed surgical suture. Under the condition of a stretching ratio of 2, the diameter of the obtained polylactic acid monofilament was 0.8 mm. Under low stretching ratio, the barb length was relatively short, measured to be 0.1 mm with an interval of 0.4 mm using a Korean COXEM EM-30 electron microscope. The tensile strength of the suture was 300 MPa and the elongation at break was 29% by tensile testing using an Instron universal tensile testing machine. The crystallinity of the suture was 85% by X-ray diffraction (XRD). The molecular weight of the fiber before and after hydrolysis (pH 5, temperature 100℃, hydrolysis time 14 days) was tested by gel permeation chromatography (GPC) to obtain the degradation cycle of the suture as 170 days.

[0114] Example 4

[0115] (1) Weigh 18g of L-PLLA particles with a molecular weight of 53000 g / mol and 2g of magnetic iron oxide (Fe3O4) nanocrystals, and mix them uniformly as the core material; weigh 90g of H-PLLA particles with a molecular weight of 160000 g / mol as the skin material. The core material is melted in a twin-screw extruder at a speed of 350 m / min and a temperature of 190 ℃ for 2 min of self-stirring. The core and skin materials are melt-extruded at a temperature of 220 ℃.

[0116] (2) The skin and core melt obtained in step (1) is extruded through a skin and core spinneret with a diameter ratio of 9:1 to form a spinning melt.

[0117] (3) The spinning melt obtained in step (2) is periodically drawn by front and rear double rollers. Specifically, the surface of the front roller is provided with a spiral groove with a depth of 0.2 mm and a groove pitch of 10 mm. The diameter of both the front and rear rollers is 60 mm. The vertical distance between the first and second yarns is 20 mm. The surface of the rear roller is coated with a ceramic coating with a thickness of 0.3 mm and a surface roughness Ra of 3.2 μm. The horizontal projection distance between the axes of the front and rear rollers is 180 mm. The front roller is heated to 110°C and rotated counterclockwise at a low speed of 3 m / s, while the rear roller rotates clockwise at a high speed of 12 m / s. Every 0.5 s interval, the front and rear rollers rotate for 1.5 s to obtain polylactic acid nascent fibers with a barbed core structure.

[0118] (4) The polylactic acid nascent fiber obtained in step (3) is heat-stretched at 70°C with a total stretching ratio of 2 times, and then heat-set at 110°C for 20 minutes to obtain polylactic acid monofilament.

[0119] (5) Place the polylactic acid monofilament obtained in step (4) into a high-temperature sterilization box at 90°C and dry for 20 minutes.

[0120] (6) The surgical suture obtained in step (5) was cooled and dried to room temperature to obtain a barbed surgical suture. Under the condition of a stretching ratio of 4, the fiber was relatively thin and the diameter of the obtained polylactic acid monofilament was 0.5 mm. Due to the increase in the stretching ratio, the length and spacing of the barbs increased. The length was measured to be 0.2 mm and the spacing was 3 mm using a Korean COXEM EM-30 electron microscope. The heat treatment temperature was selected as 110℃. While maintaining the removal of fiber defects, good mechanical properties could be obtained. The tensile strength of the suture was 286 MPa and the elongation at break was 35% by the tensile test using an Instron universal tensile testing machine. The crystallinity of the suture was tested to be 75% by X-ray diffraction (XRD). The molecular weight of the fiber before and after hydrolysis (hydrolysis environment pH 5, temperature 100℃, hydrolysis time 14 days) was tested by gel permeation chromatography (GPC) to obtain the degradation cycle of the suture as 115 days.

[0121] Example 5

[0122] (1) Weigh 18g of L-PLLA particles with a molecular weight of 53000 g / mol and 2g of magnetic iron oxide (Fe3O4) nanocrystals, and mix them uniformly as the core material; weigh 90g of H-PLLA particles with a molecular weight of 160000 g / mol as the skin material. The core material is melted in a twin-screw extruder at a speed of 350 m / min and a temperature of 190 ℃ for 2 min of self-stirring. The core and skin materials are melt-extruded at a temperature of 220 ℃.

[0123] (2) The skin and core melt obtained in step (1) is passed through a skin and core spinneret with a diameter ratio of 7:3 to form a spinning melt.

[0124] (3) The spinning melt obtained in step (2) is periodically drawn by front and rear double rollers. Specifically, the surface of the front roller is provided with a spiral groove with a depth of 0.2 mm and a groove pitch of 10 mm. The diameter of both the front and rear rollers is 70 mm. The vertical distance between the first and second yarns is 20 mm. The surface of the rear roller is coated with a ceramic coating with a thickness of 0.3 mm and a surface roughness Ra of 1.6 μm. The horizontal projection distance between the axes of the front and rear rollers is 105 mm. The front roller is heated to 110°C and rotated counterclockwise at a low speed of 3 m / s, while the rear roller rotates clockwise at a high speed of 12 m / s. Every 0.5 s interval, the front and rear rollers rotate for 2 s to obtain polylactic acid nascent fibers with a barbed core structure.

[0125] (4) The polylactic acid nascent fiber obtained in step (3) is heat-stretched at 70°C with a total stretching ratio of 2 times, and then heat-set at 110°C for 20 minutes to obtain polylactic acid monofilament.

[0126] (5) Place the polylactic acid monofilament obtained in step (4) into a high-temperature sterilization box at 90°C and dry for 20 minutes.

[0127] (6) The surgical suture obtained in step (5) was cooled and dried to room temperature to obtain a barbed surgical suture. Under the condition of a stretching ratio of 4, the fiber was relatively thin and the diameter of the obtained polylactic acid monofilament was 0.5 mm. Due to the large time interval, the spacing between the barbs was also large. The spacing was measured to be 5 mm using a Korean COXEM EM-30 electron microscope, and the barb length was 0.2 mm. Due to the large thermal contact surface area, the fiber crystallinity was improved. The tensile strength of the suture was 296 MPa and the elongation at break was 32% by tensile testing using an Instron universal tensile testing machine. The crystallinity of the suture was 79% by X-ray diffraction (XRD). The molecular weight of the fiber before and after hydrolysis (hydrolysis environment pH 5, temperature 100℃, hydrolysis time 14 days) was tested by gel permeation chromatography (GPC) to obtain the degradation cycle of the suture as 140 days.

[0128] Comparative Example 1

[0129] The core material in Example 1 was replaced with: 18g of H-PLLA particles with a molecular weight of 160,000 and 2g of magnetic iron oxide (Fe3O4) nanocrystals were weighed and mixed uniformly as the core material.

[0130] The obtained barbed surgical suture has a diameter of 0.8 mm. The tensile strength of the suture was 320 MPa using an Instron universal tensile testing machine. The crystallinity of the suture was 87% using X-ray diffraction (XRD). The molecular weight of the fibers before and after hydrolysis (pH 5, temperature 100℃, hydrolysis time 14 days) was tested using gel permeation chromatography (GPC), and the degradation cycle of the suture was found to be 200-300 days.

[0131] According to Comparative Example 1, when both the skin and the core are made of H-PLLA particles, the degradation cycle is long.

[0132] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A front and rear roller periodic drafting device, characterized in that, The front and rear roller periodic drafting device is used to draft the spinning melt at regular time intervals to form nascent fibers with barbs. The front and rear roller periodic drafting device includes a front roller, a rear roller, a traction roller, and a controller arranged sequentially. The rear roller is located below and behind the front roller. The axis of the rear roller is lower than and parallel to the axis of the front roller. The first generatrix at the highest position of the rear roller is higher than or equal to the second generatrix at the lowest position of the front roller. The axis of the traction roller is lower than and parallel to the axis of the rear roller.

2. The front and rear roller periodic drafting device according to claim 1, characterized in that, It also includes a controller, which controls the front roller to rotate counterclockwise at a first speed at a time interval and the rear roller to rotate in the opposite direction at a second speed for a preset time.

3. The front and rear roller periodic drafting device according to claim 2, characterized in that, The controller is also used to control the surface temperature of the front roller.

4. The front and rear roller periodic drafting device according to claim 1, characterized in that, The front roller is set horizontally.

5. The front and rear roller periodic drafting device according to claim 1, characterized in that, The front roller and the rear roller have the same radius at their end faces.

6. The front and rear roller periodic drafting device according to claim 5, characterized in that, The vertical distance between the first generatrix and the second generatrix is ​​0-30cm.

7. The front and rear roller periodic drafting device according to claim 5, characterized in that, The horizontal distance between the axes of the front roller and the rear roller is 1.5R-3R, where R is the end face radius of the front roller and the rear roller.

8. A method of using a front and rear roller periodic drafting device, characterized in that, The front and rear roller cycle drafting device is the front and rear roller cycle drafting device according to any one of claims 1-7, and the specific method of use is as follows: The spinning melt is wound counterclockwise into the front roller from the upper front of the front roller, then out from the bottom of the front roller, then wound clockwise into the rear roller, and then out from the rear side of the rear roller downwards and onto the traction roller. The front roller is controlled to rotate counterclockwise at a first speed for a preset time at a time interval, while the rear roller rotates in the opposite direction at a second speed.

9. The method of use according to claim 8, characterized in that, The second speed is greater than the first speed.

10. The method of use according to claim 8, characterized in that, The first speed is 1~3m / s, and the second speed is 6~12m / s.

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