An antibacterial composite fiber and its preparation method

Abstract

This invention relates to the field of composite fiber preparation technology, and discloses an antibacterial composite fiber and its preparation method, comprising: melting and mixing an antibacterial functional component containing matrix affinity segments and surface migration segments with a matrix polymer component; maintaining their miscibility using high shear transport; triggering phase separation of the antibacterial functional component and its migration to the surface of the fiber nascent body during extrusion to release shear force; and subsequently applying a rapid curing treatment to lock the antibacterial functional component in the surface layer. This invention utilizes the physicochemical properties between components and the control of process timing to achieve active self-assembly of functional components in fiber forming. This method can prepare composite fibers on conventional spinning equipment, achieving targeted enrichment and firm anchoring of functional components to the surface while maintaining the core mechanical properties of the matrix.

Description

Technical Field

[0001] This invention relates to an antibacterial composite fiber and its preparation method, belonging to the field of composite fiber preparation technology. Background Technology

[0002] Currently, to achieve a specific spatial arrangement of different components within the fiber cross-section—for example, placing a functional component in the fiber sheath while using the matrix component as the core—the industry-recognized approach relies on precise and specialized spinning assembly hardware. This method, through the design of complex spinneret geometries, such as sheath-core or island-type spinnerets, passively forms the pre-defined fiber structure during melt extrusion using external physical force. This is currently the mainstream process for achieving structured composite fibers. However, this passive forming method, highly dependent on precision hardware, has its limitations. It not only leads to high equipment investment and maintenance costs but also a relatively narrow process window. Once the spinneret geometry is determined, the microstructure of the fiber that can be produced is fixed. More importantly… This approach makes it difficult to form a gradient distribution of functional components on the fiber surface and to achieve a firm physical anchor between the functional components and the matrix, thus limiting further improvement in the performance of composite fibers. To avoid the above-mentioned dependence on complex hardware, the conventional homogenization blending method is usually adopted, which mixes functional additives with matrix polymers and then spins them. However, this approach has inherent technical contradictions, namely, the ineffective embedding and dispersion of functional additives in the fiber bulk phase, which not only leads to low utilization efficiency, but also acts as impurity points to destroy the crystallinity and regularity of matrix polymers, causing the deterioration of the core mechanical properties of the fiber. At the same time, the weak binding force between the additives and the matrix makes them easy to lose, resulting in poor functional durability and potentially causing biosafety issues.

[0003] To avoid the aforementioned reliance on precision hardware, some researchers in this field have attempted to employ active control methods, such as applying external physical fields, to induce the migration of functional components during molding. However, such methods also introduce new process complexities. For example, Chinese invention patent CN108866665B discloses antibacterial cellulose composite fibers and their preparation method. In this scheme, during wet spinning, charged water-soluble chitosan / carboxymethyl cellulose sol is mixed with cellulose spinning solution, and an attempt is made to drive charged particles toward the fiber by applying an electric field perpendicular to the spinning stream. While single-sided surface enrichment is possible, this active control method, which relies on an external electric field, not only requires additional and complex electrode modifications to conventional spinning equipment, increasing equipment costs and instability, but also makes it difficult to achieve uniform and precise control of the electric field in the high-speed flowing spinning stream. This results in difficulties in ensuring the enrichment effect of functional components and the uniformity of fibers. This method still relies on specific external forces, whether geometric hardware or physical fields, and fails to solve the core problem of how to achieve active enrichment and anchoring using only the physicochemical properties of the system itself under conventional and standard spinning process conditions.

[0004] Therefore, the technical problem to be solved by this invention is how to utilize the physicochemical principles of polymer systems to achieve active induction, surface self-enrichment and in-situ locking of functional components during the fiber forming process while maintaining the mechanical properties of the matrix, under the condition of using conventional spinning components. Summary of the Invention

[0005] This invention provides an antibacterial composite fiber and its preparation method. Its main purpose is to solve the problem that existing technologies rely on dedicated hardware or homogeneous blending methods, which cannot simultaneously achieve the directional enrichment of functional components, in-situ anchoring, and maintenance of matrix mechanical properties on conventional spinning components.

[0006] To achieve the above objectives, the present invention provides a method for preparing antibacterial composite fibers, comprising:

[0007] Step 101, Formulation: A matrix polymer component and an antibacterial functional component are melt-mixed. The antibacterial functional component is a block copolymer whose chemical structure includes: matrix affinity segments with the same or compatible chemical structure as the matrix polymer component, surface migration segments with a surface energy lower than that of the matrix polymer component, and antibacterial functional groups grafted onto the matrix affinity segments or surface migration segments. The chemical structure of the block copolymer gives it rheological properties, which are such that the matrix affinity segments and the matrix polymer component are miscible at high shear rates.

[0008] Step 102, Transport and Solubilization: The molten mixture is transported to the spinneret under the high shear rate generated by the spinning machine screw to maintain the miscibility between the matrix affinity segments and the matrix polymer components;

[0009] Step 103, Extrusion and Release: The molten mixture is extruded from the spinneret to form a fiber nascent body; during the extrusion process, the shear rate disappears, causing the thermodynamic incompatibility between the matrix affinity segments and the surface migration segments to be released, thereby triggering phase separation;

[0010] Step 104, Enrichment and Locking: Simultaneously with the triggering of phase separation, surface migration segments migrate to the surface of the fiber nascent body due to their low surface energy; and after the antibacterial functional component has completed surface enrichment, but before macroscopic phase separation occurs, a rapid curing treatment is immediately applied to the fiber nascent body to lock the antibacterial functional component onto the surface layer of the fiber.

[0011] Preferably, the matrix polymer component is polylactic acid, and the antibacterial functional component is a quaternary ammonium salt-functionalized PLLA-b-PDMS block copolymer; wherein the matrix affinity segment is a polylactic acid segment, the surface migration segment is a polydimethylsiloxane segment, and the antibacterial functional group is a quaternary ammonium salt group grafted onto the polydimethylsiloxane segment.

[0012] Preferably, in step 101, the matrix polymer component is at 190°C. The melt index under a load of 2.16 kg is 5 g / 10 min to 40 g / 10 min; the rapid curing process in step 104 is achieved by a quench air zone; the quench air zone is set at the outlet of the spinneret assembly, and the melt index ensures that the viscosity of the matrix polymer component can increase instantaneously and solidify under the action of the quench air zone.

[0013] Preferably, in step 101, the matrix polymer component is at 190°C. The melt index under a load of 2.16 kg is 5 g / 10 min to 40 g / 10 min; the rapid curing treatment in step 104 is achieved by a rapid coagulation bath, which is set at the outlet of the spinneret assembly. The melt index ensures that the matrix polymer components can be rapidly phase-separated and cured under the action of the rapid coagulation bath.

[0014] Preferably, the spinning screw in step 102 is the screw of a single-screw extruder; the method, through the rheological properties of the antibacterial functional component defined in step 101, works in conjunction with the process timing control in steps 102 to 104, thereby achieving surface self-enrichment of the antibacterial functional component on a single-screw extruder and a standard spinneret assembly, where the standard spinneret assembly does not have geometric channels for forming a core-sheath structure.

[0015] Preferably, in step 101, the amount of the antibacterial functional component is 0.5 to 10 parts by weight, based on the total weight of the molten mixture, with the matrix polymer component as the balance; the total weight of the surface-migrating segments in the antibacterial functional component is... The total weight of the matrix affinity segments is ,in and The ratio satisfies .

[0016] Preferably, the disappearance of shear rate in step 103 means that the shear stress experienced by the molten mixture after passing through the capillary of the spinneret assembly is reduced to a certain value. The reduction occurs within a timescale of seconds; the timescale matches the response time of the rapid curing process in step 104 to ensure that locking is completed between the completion of surface enrichment of the antimicrobial functional components and the occurrence of macroscopic phase separation.

[0017] Preferably, the high shear rate in step 102 specifically refers to controlling the rotational speed of the spinning machine screw so that the shear rate experienced by the molten mixture in the kneading or transport zone of the screw is not lower than that of the spinning machine screw. To ensure that the matrix affinity segments are fully entangled with the matrix polymer components and maintain a miscible state, in step 101, the surface energy of the surface migration segments is lower than the surface energy of the matrix polymer components, and the difference between the two surface energies is not less than 10 mN / m.

[0018] Preferably, the quaternary ammonium salt-functionalized PLLA-b-PDMS block copolymer has a number average molecular weight of 10,000 g / mol to 50,000 g / mol; wherein the number average molecular weight of the polylactic acid segments is 5,000 g / mol to 30,000 g / mol, and the number average molecular weight of the polydimethylsiloxane segments is 3,000 g / mol to 20,000 g / mol.

[0019] An antibacterial composite fiber, prepared by a method for preparing antibacterial composite fibers, comprising:

[0020] A matrix polymer component that constitutes the core of an antibacterial composite fiber;

[0021] An antibacterial functional component is locked in the surface layer of an antibacterial composite fiber; wherein the concentration distribution of the antibacterial functional component on the cross-section of the antibacterial composite fiber exhibits a gradient, with the concentration in the surface layer being higher than that in the core.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] 1. This invention utilizes the high shear stress inside the spinning machine screw to maintain a controlled pseudo-miscible state between the matrix polymer and a functional component with specific rheological properties during transport, avoiding macroscopic phase separation caused by the incompatibility of the two components before entering the spinneret. When the mixed melt is extruded and the shear force disappears, the incompatibility between the two components is immediately released. At this time, the functional component, due to its lower surface energy, gains the driving force to migrate to the surface of the fiber nascent body. In the very short time after this migration process is completed, the matrix polymer is rapidly solidified through an immediate rapid curing treatment, irreversibly anchoring the functional component already enriched on the surface to the surface layer of the fiber.

[0024] 2. The problem of spatial arrangement of functional components in the cross-section of the fiber is transformed from passive geometric shaping that relies on dedicated and complex spinneret assemblies to an active self-assembly process that utilizes the physicochemical properties between polymer components and controls their process. This approach makes it possible to prepare composite fibers with functional gradient distribution on spinning equipment without irregularly shaped spinnerets, avoiding dependence on specific precision hardware and providing a different path for the preparation of multi-component fibers.

[0025] 3. Through the synergistic effect of thermodynamic driving and kinetic locking mechanisms, functional components are not only enriched on the fiber surface, but also physically anchored in the surface layer structure of the fiber while the matrix polymer is rapidly solidified. This forms a strong binding force that is different from traditional blending or post-treatment adsorption. This structure makes it difficult for functional components to be lost in the subsequent use environment, thus maintaining their function for a long time. At the same time, since the functional components are actively guided to the surface, ineffective embedding within the fiber bulk phase is avoided. This ensures that the crystallization behavior and molecular chain regularity of the matrix polymer are maintained during the molding process, and the core mechanical properties of the fiber are no longer degraded due to the introduction of functional components. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the process flow and key control points of the preparation method of the present invention;

[0027] Figure 2 This is a graph showing the influence of the block ratio on the overall fiber performance of the present invention;

[0028] Figure 3 This is a comparison diagram showing the effect of the curing time sequence of the present invention on the fiber microstructure;

[0029] Figure 4 This is a timeline diagram of the surface enrichment and rapid curing locking mechanism of the present invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0031] This invention discloses an antibacterial composite fiber and its preparation method. The core of this method lies in constructing a dynamic self-assembly process based on polymer physicochemical principles and process timing control. It no longer relies on dedicated spinneret hardware to achieve the fiber's microstructure, but instead actively induces functional components to migrate to the fiber surface and fix them in situ through a series of coordinated process steps: step 101 (formulation), step 102 (transport and solubilization), step 103 (extrusion and release), and step 104 (enrichment and locking). In a specific implementation of this invention, step 101, the formulation stage, defines the technical state of the initial materials; the matrix polymer component is polylactic acid (PLA), and to ensure the instantaneous increase in viscosity during the subsequent rapid cooling and curing process in step 104, its viscosity is controlled at 190°C. The melt index under a 2.16 kg load condition is controlled within the range of 5 g / 10 min to 40 g / 10 min; the antibacterial functional component is a block copolymer designed for this process, and its amount, based on the total weight of the melt mixture, is 0.5 parts by weight to 10 parts by weight; chemically, this copolymer is specifically a quaternary ammonium salt-functionalized PLLA-b-PDMS block copolymer, with a typical number-average molecular weight range of 10,000 g / mol to 50,000 g / mol; this structure is used to provide specific physicochemical properties: its contained polylactic acid segments serve as matrix affinity segments, and their chemical structure is the same as that of the matrix polymer component (polylactic acid), for use in... In step 102, the polydimethylsiloxane (PDMS) block copolymer achieves high shear miscibility with the polylactic acid (PLLA) matrix. The polydimethylsiloxane segments within it serve as surface migration segments, with their surface energy designed to be lower than that of the PLLA matrix, with a surface energy difference of not less than 10 mN / m, thus constituting the driving force for surface enrichment in step 104. Quaternary ammonium salt groups grafted onto the PDMS segments serve as antibacterial functional groups. Furthermore, the AB-type structure of this PLLA-b-PDMS block copolymer endows the system with specific rheological properties, namely, increased compatibility under high shear (as in step 102) and release of incompatibility under low shear (as in step 103). To balance affinity and migration, the total weight of the PDMS segments is... Total weight of polylactic acid segments The ratio satisfies The polylactic acid segments have a number average molecular weight of 5000 g / mol to 30000 g / mol, and the polydimethylsiloxane segments have a number average molecular weight of 3000 g / mol to 20000 g / mol. The final step of step 101 is to mix the two components in a molten state to prepare for the transport in the subsequent step 102.

[0032] Following step 101, the objective of step 102 is to suppress phase separation during transport by utilizing rheological properties. To achieve this, the method utilizes a spinning machine screw, which can be a conventional single-screw extruder screw. By controlling the rotational speed of the spinning machine screw, the high shear rate experienced by the molten mixture in the kneading or transport zone of the screw is not less than [a certain value]. Under this high shear rate, the matrix affinity segments (PLLA segments) and the matrix polymer components (PLLA matrix) in the antibacterial functional component (PLLA-b-PDMS) are fully entangled under high shear, achieving a miscible state of the system, thus ensuring that a uniform melt is stably transported to the spinneret assembly; step 103 is the triggering stage for self-assembly; the molten mixture is extruded to form a fiber nascent body when passing through the spinneret assembly; it should be noted that the spinneret assembly here is a standard spinneret assembly, which does not have geometric channels for forming a core-sheath structure, and this method does not rely on hardware to passively shape the structure; when the melt leaves the capillary of the spinneret assembly, the shear stress it experiences suddenly disappears, and this reduction in shear rate occurs to Within the timescale, the disappearance of shear force relieves the forces maintaining mutual solubility in step 102, resulting in the release of the thermodynamic incompatibility between the matrix affinity segment (PLLA) and the surface migration segment (PDMS).

[0033] Step 104 is crucial for achieving structural solidification. Simultaneously with the phase separation triggered in step 103, the surface migration segments (PDMS segments) in the antibacterial functional component, due to their low surface energy, acquire a driving force towards the fiber nascent body-air interface, spontaneously migrating and accumulating on the surface of the fiber nascent body. To fix this instantaneous surface-accumulated structure, this method employs a time-matched locking mechanism: immediately after the antibacterial functional component completes surface enrichment, but before macroscopic phase separation occurs, a rapid solidification treatment is applied to the fiber nascent body. The response time of this rapid solidification treatment is related to the disappearance of the shear rate in step 103. to The timescale is matched; in an optional embodiment, the rapid curing process is achieved through a quench air zone located at the exit of the spinneret assembly, utilizing the melt index range (5 g / 10 min to 40 g / 10 min) defined in step 101 to ensure that the viscosity of the matrix polymer (PLLA) increases instantaneously and solidifies under the action of quench air; in another optional embodiment, the rapid curing process is achieved through a rapid coagulation bath, also located at the exit of the spinneret assembly, into which the nascent fiber is immediately immersed after leaving the spinneret orifice; for systems with polylactic acid as the matrix polymer component, the coagulation bath may be ethanol, water, or a mixture thereof, and the temperature of the coagulation bath is controlled at 0. Up to 25 Within the range; the residence time of the fiber nascent body in the coagulation bath matches the time scale in step 103, which is achieved by controlling the speed of the traction roller; the melt index (5 g / 10 min to 40 g / 10 min) characteristic defined in step 101 ensures that the PLLA melt can undergo rapid phase separation and instantaneous solidification when it comes into contact with the low-temperature solidification medium due to the high heat transfer coefficient of the liquid medium and the dual effect of induced phase separation, thereby locking the antibacterial functional components that have migrated to the surface onto the surface layer of the fiber; the final result of both methods is to irreversibly fix the antibacterial functional components that have migrated and enriched on the surface onto the surface layer of the fiber, thereby preparing an antibacterial composite fiber. On the cross-section of the fiber, the concentration distribution of the antibacterial functional components presents a gradient, with the concentration on the surface layer being higher than that in the core, while the core is mainly composed of matrix polymer components that maintain their crystalline regularity.

[0034] To determine the timing match between the rapid curing process in step 104 and the phase separation and migration process in step 103, those skilled in the art, when faced with a specific material system, can perform an engineering calibration procedure. This procedure fixes the specifications and amounts of the matrix polymer component and the antibacterial functional component in step 101, using polylactic acid with a melt index of 20 g / 10 min. A PLLA-b-PDMS copolymer with a ratio of 0.7 was used, and the screw speed in step 102 was set to maintain a constant high shear rate, for example... The curing strength in step 104 is systematically adjusted. When using a quenching air zone, the temperature of the quenching air is kept at 5°C. Up to 25 The wind speed can be adjusted gradients and fixed within a certain range, or when using a rapid condensation bath, the temperature of the condensation bath can be kept at 0°C. Up to 25 Within a certain range, the residence time of the nascent fiber in the bath is changed by adjusting the speed of the traction roller. Finally, by detecting the breaking strength of the fibers prepared under different curing parameters and the antibacterial rate after 20 washes, a combination of process parameters that can simultaneously maintain high breaking strength and achieve high surface antibacterial rate is selected. The physical state corresponding to this combination is the timing matching point where surface enrichment lock-in occurs faster than macroscopic phase separation. The melt index of the matrix polymer component defined in step 101 is a key material parameter affecting the instantaneous viscosity increase rate in step 104 and the phase separation kinetic timescale in step 103. When this melt index changes, it is replaced with a melt index of 35. Polylactic acid with a viscosity of g / 10min has a lower viscosity, resulting in a shorter characteristic time for phase separation and surface migration after shear release. Therefore, it is necessary to readjust the rapid curing parameters in step 104 according to the aforementioned engineering calibration procedures. This typically involves matching a faster curing response time or a stronger cooling intensity to achieve surface locking within the shorter time window. Conversely, if a high-viscosity matrix with a lower melt index, such as 10g / 10min, is selected, its characteristic time for phase separation and migration is relatively longer. In this case, the curing parameters in step 104 should also be adjusted accordingly to ensure that the curing sequence always matches the phase separation kinetics of the specific material. Similarly, in antibacterial functional components... The ratio directly affects the driving force and characteristic time of surface migration in step 104; a lower ratio... A ratio close to 0.2 corresponds to a weaker migration driving force, and the time required to complete surface enrichment is relatively longer. Therefore, the start-up timing of the rapid curing process in step 104 should be matched to this longer time scale. Conversely, a higher ratio indicates a weaker migration driving force. A ratio close to 5.0 provides a stronger migration drive, and surface enrichment is completed in a very short time. At this point, the curing process in step 104 must have a faster response speed.

[0035] Example 1: In a specific application for preparing in vivo absorbable antibacterial surgical sutures, the objective engineering challenge lies in the fact that the fiber must maintain the core mechanical properties and biocompatibility of the matrix material, such as polylactic acid, while achieving efficient and long-lasting antibacterial function. Traditional homogeneous blending methods, due to the ineffective embedding and uncontrollable dissolution of the antibacterial agent in the bulk phase, are difficult to simultaneously meet the above-mentioned multiple and mutually restrictive performance requirements. To address this challenge, the preparation method of this invention is applied, using polylactic acid as the matrix polymer component with a melt index of 20 g / 10 min, which falls within the range of 5 g / 10 min to 40 g / 10 min; and a quaternary ammonium salt-functionalized PLLA-b-PDMS block copolymer is selected as the antibacterial functional component, wherein the weight ratio of polylactic acid segments (matrix affinity segments) to polydimethylsiloxane segments (surface migration segments) is... The value is set to 0.8, which falls within the range of 0.2 to 5.0. The total amount of the antibacterial functional component is 3 parts by weight, which falls within the range of 0.5 to 10 parts by weight. This preparation method is performed on a single-screw extruder equipped with a standard spinneret assembly. The formulation is completed in step 101, in which the two components are melt-mixed. In step 102, the screw speed is set to a specific value so that the high shear rate experienced by the melt in the transport zone is maintained at a certain level. The rate is not lower than Under this shear force, the PLLA segments in PLLA-b-PDMS become miscible with the PLLA matrix, forming a seemingly homogeneous molten mixture that is then transported to the spinneret assembly.

[0036] In step 103, when the molten mixture is extruded through the capillaries of the standard spinneret assembly, the shear rate is at... It disappears abruptly within a timescale, which is within... to Within a certain range, the thermodynamic incompatibility between the PLLA and PDMS segments is released, triggering phase separation. Subsequently, in step 104, the triggering of phase separation and the low surface energy of the PDMS segments (with a surface energy difference greater than 10 mN / m between the PDMS segments and the PLLA matrix) synergistically drive the antibacterial functional components to migrate to the surface of the fiber nascent body. At the instant this migration occurs, the fiber nascent body immediately enters the quenched air zone located at the spinneret outlet. Based on the melt index characteristics of the selected PLLA, the matrix polymer rapidly solidifies, thereby... The PLLA-b-PDMS block copolymer, already enriched on the surface, is locked in the surface layer of the fiber. The resulting antibacterial composite fiber has a core mainly composed of PLLA matrix, maintaining the original crystalline regularity of PLLA. Therefore, its core mechanical properties, including its breaking strength and toughness, are preserved. At the same time, its antibacterial functional components are enriched and firmly locked in the fiber surface layer, realizing the surface deployment of functional components. This structure not only provides high-density antibacterial activity at the contact points, but also avoids the mechanical property degradation caused by the embedding of antibacterial agents in the bulk phase.

[0037] Example 2: To objectively verify the synergistic effect between the specific chemical structure of the antibacterial functional component, its dosage, and the process timing control (high shear solubilization and rapid curing and locking) in the preparation method of the present invention, and its influence on the final fiber properties, the following experiment was set up; Experiment preparation: Two groups of the present invention sample groups (labeled as sample group 1 and sample group 2) and four control groups (labeled as control group 1 to control group 4) were set up; Materials used: Matrix polymer component (PLLA): polylactic acid, which at 190 The melt index under a 2.16 kg load condition is 25 g / 10 min; the antibacterial functional component (Func-BCP) is a quaternary ammonium salt-functionalized PLLA-b-PDMS block copolymer with a number average molecular weight of 25,000 g / mol, of which the number average molecular weight of the PLLA matrix affinity segments is 15,000 g / mol and the number average molecular weight of the PDMS surface migration segments is 10,000 g / mol. The ratio was 0.67; the control antibacterial agent (Add-QAS) was a conventional quaternary ammonium salt oligomer, a non-block copolymer, with a number average molecular weight of approximately 3000 g / mol; the equipment used was a single-screw extruder with a screw length-to-diameter ratio (L / D) of 30:1, the screw structure including a kneading zone and a transport zone; a standard spinneret assembly without a core-sheath structure; and a quenching air zone located at the spinneret assembly outlet, providing 15... Forced cooling air; Experimental grouping and preparation method: Control group 1 (traditional homogeneous blending): 95 parts by weight of PLLA and 5 parts by weight of control antibacterial agent (Add-QAS) were melt-mixed; the same process parameters as the sample group of this invention were used (screw speed corresponding to shear rate). The sudden cold air zone 15 ) was spun; Control group 2 (incorrect process: low shear and slow curing): 95 parts by weight of PLLA and 5 parts by weight of antibacterial functional component (Func-BCP) were melt-mixed; a low screw speed (corresponding to shear rate) was used. ), and instead of using a quench air zone after extrusion, a 25 Natural air cooling at room temperature (slow curing); Control group 3 (out of range: dosage too low): 99.9 parts by weight of PLLA were melt-mixed with 0.1 parts by weight of the antibacterial functional component (Func-BCP).

[0038] Sample Group 1 (5.0%): 95 parts by weight of PLLA and 5 parts by weight of the antibacterial functional component (Func-BCP) were melt-mixed and prepared using the method of this invention; Sample Group 2 (10.0%): 90 parts by weight of PLLA and 10 parts by weight of the antibacterial functional component (Func-BCP) were melt-mixed and prepared using the method of this invention; Control Group 4 (out of range: excessive dosage): 85 parts by weight of PLLA and 15 parts by weight of the antibacterial functional component (Func-BCP) were melt-mixed and prepared using the method of this invention; wherein, all groups prepared using the method of this invention (Sample Group 1, Sample Group 2, Control Group 3, and Control Group 4) strictly adhered to the process timing control: in step 102, the screw speed was controlled to maintain the high shear rate experienced by the melt in the kneading zone and transport zone at a certain level. (not less than) In step 104, the fiber progenitor immediately enters 15 after extrusion. Rapid curing treatment was carried out in a sudden cooling air zone; Performance testing: The fibers prepared in the above groups were tested according to the standard test methods for composite fibers in this field to detect their core mechanical properties (breaking strength, breaking elongation), initial antibacterial properties (based on GB / T20944.3-2008, with Staphylococcus aureus as the test strain) and functional durability (antibacterial rate after 20 standard washing cycles). Test results and data analysis: The performance test data of each group of fibers are summarized in Table 1.

[0039] Table 1: Comparison Test Data of Fiber Properties of Each Sample Group

[0040]

[0041] Analysis of the data in Table 1: Data from control group 1 (traditional homogeneous blending) shows low mechanical properties (breaking strength 41.5 MPa) and poor functional durability (antibacterial rate after washing 22.4%), consistent with the defects in the background technology. Secondly, data from control group 2 (incorrect process) shows that while it used the antibacterial functional component (Func-BCP) of this invention, it did not use process timing control (i.e., low shear and slow curing), resulting in severely damaged fiber mechanical properties (strength only 30.2 MPa) and a significantly lower antibacterial rate than control group 1. This data comparison indicates that the high-shear solubilization and rapid curing locking process timing of this invention are indispensable for achieving component surface enrichment and maintaining performance; the two have a synergistic effect. In contrast, using the complete process of this invention… The mechanical properties (57.9 MPa and 55.4 MPa) of samples 1 and 2 (5.0% and 10.0% respectively) prepared by the whole method remained at a high level, and the antibacterial rates after initial preparation and washing were both above 99.0%, indicating that the method of the present invention achieves efficient and long-lasting antibacterial function while maintaining the mechanical properties of the matrix. Finally, the antibacterial rate (35.7%) of control group 3 (0.1%, below the lower limit of 0.5%) was insufficient, while the mechanical properties (strength 48.3 MPa) of control group 4 (15.0%, above the upper limit of 10%) showed a significant decrease. The data of these two groups that exceeded the range, combined with the data of samples 1 and 2, confirmed that 0.5 parts by weight to 10 parts by weight is an effective range that takes into account both antibacterial and mechanical properties.

[0042] Example 3: To further verify the synergistic relationship between the rapid curing lock in step 104 and the high shear transport in step 102 in the process timing control of the present invention, especially the role of rapid curing treatment in preventing macroscopic phase separation and maintaining fiber mechanical properties, the following comparative example was set up; a control group 5 was set up in this comparative example to isolate and verify the necessity of rapid curing treatment in step 104; the initial state definition used in this comparative example, including materials and equipment, is the same as that of sample group 1 in Example 2, that is: the melt index of the matrix polymer component (PLLA) is 25 g / 10 min; the antibacterial functional component (Func-BCP) is a quaternary ammonium salt functionalized PLLA-b-PDMS block copolymer, The ratio was 0.67; the amount of antibacterial functional component was 5.0 parts by weight; the only difference in the preparation method from sample group 1 in terms of process flow was step 104: this comparative example also performed steps 101 and 102, that is, in a single-screw extruder, the screw speed was controlled to maintain the high shear rate experienced by the melt at a certain level. To achieve a miscible state; in step 103, the melt is also extruded from the standard spinneret assembly, triggering phase separation; however, in step 104, this comparative example removes 15 Instead of cooling the air region, the extruded fibrous prototypes are placed at 25°C. The fiber prepared in this comparative example (control group 5) was naturally cooled in a room temperature environment. The fiber was then compared with the sample group 1 in Example 2, which had the same material ratio. The test method and standard were the same as in Example 2. The results are shown in Table 2.

[0043] Table 2: Comparative Data on the Effects of Rapid Curing Steps on Fiber Properties

[0044]

[0045] Analysis of the data in Table 2 shows that the only key variable in the preparation conditions of control group 5 and sample group 1 is the curing speed. After removing the rapid curing treatment, the mechanical properties (fracture strength 25.4 MPa, elongation at break 33.7%) of control group 5 decreased compared to sample group 1 (strength 57.9 MPa, elongation at break 139.8%). At the same time, its functional durability (antibacterial rate after washing 30.5%) was also much lower than that of sample group 1 (99.0%). This result indicates that without the rapid curing lock-in in step 104, even though the high shear solubilization in step 102 and the phase separation triggering in step 103 have occurred, the slow cooling process provides sufficient time for the antibacterial functional components to undergo further macroscopic phase separation after completing surface migration. This macroscopic phase separation structure, as a defect point, disrupts the continuity and regularity of the PLLA matrix polymer, leading to a decrease in mechanical properties. Furthermore, this separated structure is not firmly anchored in the surface layer and is therefore easily lost during washing.

[0046] Example 4: This example combines Figures 1 to 4 This describes an antibacterial composite fiber and its preparation method, such as... Figure 1 As shown, the method begins with the formulation of a matrix polymer component, such as polylactic acid (PLLA), and an antimicrobial functional component, namely a block copolymer containing a core functional component, in step 101, i.e., melt mixing. The core functional component comprises three parts: matrix affinity segments that are miscible with the matrix under high shear, surface migration segments with low surface energy to drive migration to the surface, and antimicrobial functional groups grafted onto the segments to provide antimicrobial activity. The mixture proceeds to step 102, transport and solubilization, which is controlled by key regulation A, i.e., a high shear rate generated by the spinning machine screw to maintain the miscibility of the system. Next, in step 103, extrusion and release, the melt is extruded, the shear force is released, thereby triggering phase separation. Finally, it proceeds to step 104, enrichment and locking. After the surface migration segments have completed surface enrichment, key regulation B, i.e., rapid curing treatment, is immediately applied to lock the functional component in the surface layer, ultimately producing an antimicrobial composite fiber in which the functional component is locked in the surface layer and exhibits a gradient distribution.

[0047] like Figure 2 As shown, the horizontal axis is The ratio, with the vertical axis representing performance index values, where the solid line represents breaking strength (unit MPa) and the dashed line represents the antibacterial rate (unit %) after 20 washes. Data shows that when... When the ratio is 0.1, the breaking strength is high at 58.5 MPa, but the antibacterial rate after washing is extremely low at 15.3%. When the ratio increased to 0.2, the antibacterial rate after washing jumped to 98.7%, and remained above 99.0% at ratios of 0.7 and 5.0. Simultaneously, the tensile strength remained at a high level above 51.2 MPa within the range of 0.2 to 5.0. However, when... When the ratio increases to 6.0, the fracture strength decreases to 29.8 MPa; for example... Figure 3 As shown, the process begins with the preparation and solubilization in steps 101 / 102. A controlled miscible state is maintained within the spinning machine screw through a high shear rate. Then, in step 103, the extrusion and release stage begins. The shear force within the nascent fiber is released, instantaneously triggering phase separation and surface migration. At this point, the process path diverges: if step 104 of this invention is adopted, i.e., a time-matched rapid curing treatment is applied, time matching is achieved, the system reaches the target state of surface enrichment and locking, functional components are locked in the surface layer, and the mechanical properties of the matrix are maintained. Conversely, if an incorrect process is used, i.e., slow curing, time mismatch occurs, the system has sufficient time for macroscopic phase separation, functional components fail to be firmly locked, ultimately forming a defective state, leading to deterioration of mechanical properties.

[0048] like Figure 4 As shown, once the fibrous nascent tissue has just completed enrichment on the surface and the antibacterial components have migrated to the surface, it immediately enters the rapid curing zone. At this time, the curing system can adopt method A, as shown in Figure 15. Sudden cooling of air or method B such as 0 Up to 25 Rapid cooling is applied to the rapid coagulation bath. Based on the specific melt index of the PLLA matrix, such as 5 g / 10 min to 40 g / 10 min, this rapid cooling ensures a sudden surge in viscosity, achieving a rapid response. The timescale of this curing transfer, such as 0.001 s to 0.1 s, matches the phase separation time, allowing the matrix to solidify and encapsulate the surface-enriched components. Ultimately, the antimicrobial components are locked in the surface layer, forming a physically anchored structure that prevents macroscopic phase separation. Once the structure has solidified, the resulting fiber has a surface layer that is a functional layer in which the antimicrobial components are firmly anchored, while the core maintains the crystalline regularity of the matrix. The figure also indicates that if the curing is too slow, macroscopic phase separation will continue to occur, leading to a decrease in mechanical properties and easy loss of functional components.

[0049] Example 5: Total weight of surface migration segments in the antibacterial functional component of the present invention Total weight of matrix affinity segments The ratio, i.e. This is a parameter that controls the high-shear solubilization effect in step 102 and the surface migration driving force in step 104. To determine the effective working range of this parameter, this embodiment sets up a systematic calibration procedure to clarify the influence of this ratio on the final comprehensive performance of the fiber. The initial state of the calibration procedure in this embodiment is defined as follows: the matrix polymer component (PLLA) and the equipment used are consistent with sample group 1 in Example 2; the total amount of antibacterial functional component (Func-BCP) added is constant at 5.0 parts by weight; the preparation method is the method of the present invention used in sample group 1 in Example 2, that is, the high shear rate is maintained at And the curing method is 15 Rapid solidification occurs through quenching with air; the only variable is the internal block ratio of the antimicrobial functional component (Func-BCP) used. Five groups with different The ratio of PLLA-b-PDMS block copolymers (the total average molecular weight was controlled between 24000 g / mol and 26000 g / mol) was used to prepare control group 6, sample group 3, sample group 4, sample group 5 and control group 7. The materials in each group were prepared according to the method of the present invention (high shear, fast curing) and the resulting fibers were tested for performance. The test method and standard were the same as in Example 2. The key performance data are shown in Table 3.

[0050] Table 3: Block ratio of antibacterial functional components Calibration data table of the effect on fiber properties

[0051]

[0052] Analysis of the data in Table 3: In the control group of 6, The ratio (0.1) is below the lower limit of 0.2, indicating that the content of surface migration segments (PDMS) is too low, resulting in insufficient driving force for their migration to the surface. Although the high proportion of PLLA matrix affinity segments allows the mechanical properties (strength 58.5 MPa) to be maintained, insufficient surface enrichment leads to an antibacterial rate of only 15.3% after washing; in control group 7, When the ratio (6.0) is higher than the upper limit of 5.0, the content of matrix affinity segments (PLLA) is too low. This results in the PLLA matrix failing to achieve effective entanglement and miscibility under the high shear rate in step 102. This component exists as an incompatible component in the screw, leading to instability in the spinning process and easy fiber breakage, ultimately causing a decrease in the mechanical properties of the fiber (strength 29.8 MPa). In contrast, data from samples 3, 4, and 5 show that when... When the ratio is in the range of 0.2 to 5.0, the fibers can achieve efficient and strong surface antibacterial function while maintaining spinning stability and high mechanical properties (strength greater than 51.2 MPa).

[0053] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing an antibacterial composite fiber, characterized in that, include: Step 101, Formulation: A matrix polymer component and an antibacterial functional component are melt-mixed. The antibacterial functional component is a block copolymer whose chemical structure includes: matrix affinity segments with the same or compatible chemical structure as the matrix polymer component, surface migration segments with a surface energy lower than that of the matrix polymer component, and antibacterial functional groups grafted onto the matrix affinity segments or surface migration segments. The chemical structure of the block copolymer gives it rheological properties, which are such that the matrix affinity segments and the matrix polymer component are miscible at high shear rates. Step 102, Transport and Solubilization: The molten mixture is transported to the spinneret under the high shear rate generated by the spinning machine screw to maintain the miscibility between the matrix affinity segments and the matrix polymer components; Step 103, Extrusion and Release: The molten mixture is extruded from the spinneret to form a fiber nascent body; during the extrusion process, the shear rate disappears, causing the thermodynamic incompatibility between the matrix affinity segments and the surface migration segments to be released, thereby triggering phase separation; Step 104, enrichment and locking: While phase separation is triggered, surface migration segments migrate to the surface of the fiber nascent body due to their low surface energy; and after the antibacterial functional component has completed surface enrichment, but before macroscopic phase separation occurs, a rapid curing treatment is immediately applied to the fiber nascent body to lock the antibacterial functional component in the surface layer of the fiber. Furthermore, the matrix polymer component is polylactic acid, and the antibacterial functional component is specifically a quaternary ammonium salt-functionalized PLLA-b-PDMS block copolymer; wherein the matrix affinity segment is a polylactic acid segment, the surface migration segment is a polydimethylsiloxane segment, and the antibacterial functional group is a quaternary ammonium salt group grafted onto the polydimethylsiloxane segment. The base polymer component has a melt flow rate of 190 a melt flow rate of 5 g / 10 min to 40 g / 10 min under a load of 2.16 kg; The total weight of the surface migration segment in the antibacterial functional component is The total weight of the matrix affinity segment is The ratio of to satisfies .

2. The method for preparing antibacterial composite fibers according to claim 1, characterized in that, The rapid curing process in step 104 is achieved through a quench air zone; the quench air zone is set at the outlet of the spinneret assembly, and the melt flow index ensures that the viscosity of the matrix polymer component can increase instantaneously and solidify under the action of the quench air zone.

3. The method for preparing antibacterial composite fibers according to claim 1, characterized in that, The rapid curing process in step 104 is achieved through a rapid coagulation bath, which is located at the outlet of the spinneret assembly.

4. The method for preparing antibacterial composite fibers according to claim 1, characterized in that, The spinning machine screw in step 102 is the screw of a single-screw extruder; the method uses the rheological properties of the antibacterial functional component defined in step 101, in conjunction with the process timing control of steps 102 to 104, to achieve surface self-enrichment of the antibacterial functional component on a single-screw extruder and a standard spinneret assembly, the standard spinneret assembly not having geometric channels for forming a core-sheath structure.

5. The method for preparing antibacterial composite fibers according to claim 1, characterized in that, In step 101, the amount of antibacterial functional component is 0.5 to 10 parts by weight, and the matrix polymer component is the balance, based on the total weight of the molten mixture.

6. The method for preparing antibacterial composite fibers according to claim 1, characterized in that, The disappearance of shear rate in step 103 refers to the shear stress experienced by the molten mixture after passing through the capillary of the spinneret assembly. Decrease within a second timescale; The timescale is matched with the response time of the rapid curing process in step 104, and the locking is completed between the completion of surface enrichment of the antibacterial functional components and the occurrence of macro-phase separation.

7. The method for preparing antibacterial composite fibers according to claim 1, characterized in that, The high shear rate in step 102 specifically refers to controlling the rotational speed of the spinning machine screw so that the shear rate experienced by the molten mixture in the kneading or transport zone of the screw is not lower than [a certain value]. To ensure that the matrix affinity segments are fully entangled with the matrix polymer components and maintain a miscible state, in step 101, the surface energy of the surface migration segments is lower than the surface energy of the matrix polymer components, and the difference between the two surface energies is not less than 10 mN / m.

8. The method for preparing antibacterial composite fibers according to claim 1, characterized in that, The quaternary ammonium salt-functionalized PLLA-b-PDMS block copolymer has a number average molecular weight of 10,000 g / mol to 50,000 g / mol; wherein the number average molecular weight of the polylactic acid segment is 5,000 g / mol to 30,000 g / mol, and the number average molecular weight of the polydimethylsiloxane segment is 3,000 g / mol to 20,000 g / mol.

9. An antibacterial composite fiber, prepared by the method for preparing the antibacterial composite fiber according to claim 1, characterized in that, Antibacterial composite fibers contain: A matrix polymer component that constitutes the core of an antibacterial composite fiber; An antibacterial functional component is locked in the surface layer of an antibacterial composite fiber; wherein the concentration distribution of the antibacterial functional component on the cross-section of the antibacterial composite fiber exhibits a gradient, with the concentration in the surface layer being higher than that in the core.

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