Polylactic acid-based antibacterial masterbatch, antibacterial composite fiber and preparation method and application thereof

Abstract

The application relates to the technical field of high polymer materials and modified fibers, and particularly relates to a polylactic acid-based antibacterial master batch, an antibacterial composite fiber and a preparation method and application thereof, the polylactic acid-based antibacterial master batch is composed of the following components in percentage by mass: 95-99% of polylactic acid and 1-5% of antibacterial grafted polymerized rosin; the preparation method comprises the following steps: performing grinding treatment on the polylactic acid to obtain powdered PLA, and then drying the powdered PLA and antibacterial grafted polymerized rosin powder; mixing the dried powdered PLA and antibacterial grafted polymerized rosin powder according to different proportions, and then using a double-screw extruder to melt blend and extrude, and performing pelletizing after melt drawing and air cooling. The application constructs a novel polymerized rosin grafting modification system, effectively breaks through the technical difficulties of insufficient mechanical properties of traditional antibacterial fibers and low antibacterial efficiency, and optimizes the formula composition and system structure; the preparation process is simple and controllable, and the industrialization landing and market application value are prominent.

Description

Technical Field

[0001] This invention relates to the field of polymer materials and modified fiber technology, specifically to a polylactic acid-based antibacterial masterbatch, antibacterial composite fiber, its preparation method and application. Background Technology

[0002] Biodegradable materials have become a key research area in materials science. Polylactic acid (PLA), with its advantages of being derived from renewable biomass and being highly environmentally friendly, has demonstrated significant application value in various fiber applications such as medical dressings and antibacterial packaging. However, due to the inherent brittleness and poor thermal processing stability of PLA, its application in high-value-added fields has been severely limited. Developing modified PLA fibers that combine excellent mechanical properties with highly effective antibacterial effects and have a simple preparation process has become a key technological bottleneck that the industry urgently needs to overcome.

[0003] To overcome the aforementioned technical challenges, composite modification technology has gradually become a research focus in this field. Polymeric rosin (PR), as a natural biomass raw material, not only possesses excellent processing adaptability but also occupies an important position in the research of biodegradable material modification. Blending PR with polylactic acid (PLA) can effectively improve the thermoplastic rheological properties and surface characteristics of PLA, while also imparting basic antibacterial functions. However, simple direct blending easily leads to insufficient interfacial compatibility between the two phases, resulting in impaired fiber mechanical strength. Furthermore, the antibacterial efficacy of unmodified PR / PLA composite fibers is weak, failing to meet the demands of high-performance applications. Therefore, further modification is still needed to achieve comprehensive performance improvement. Summary of the Invention

[0004] The purpose of this invention is to provide a polylactic acid-based antibacterial masterbatch, antibacterial composite fiber, its preparation method and application, to solve the technical problems of insufficient antibacterial properties and weak tensile mechanical properties of PLA and its composite fibers.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] Polylactic acid-based antibacterial masterbatch is composed of the following components by weight percentage: polylactic acid 95-99%, antibacterial grafted polymeric rosin 1-5%;

[0007] The preparation process of the antibacterial grafted polymerized rosin includes the following steps:

[0008] S11. Dissolve polymerized rosin in tetrahydrofuran solution to obtain polymerized rosin solution;

[0009] S12. Dissolve polyhexamethylene biguanide in deionized water to obtain an aqueous solution of polyhexamethylene biguanide;

[0010] S13. Add polyhexamethylene biguanide aqueous solution dropwise to the polymerized rosin solution in step S11, stir, then add triethylamine, and reflux at 60℃-70℃.

[0011] S14. After the substrate reaction was confirmed to be complete by TLC, anhydrous ethanol was added to the system, and a solid was precipitated. The solid was then filtered, washed, and vacuum dried to obtain antibacterial grafted polymerized rosin.

[0012] Preferably, the polymerized rosin has a softening point of 135℃-145℃ and an acid value of 140mgKOH / g-150mgKOH / g; the polylactic acid has a relative molecular mass of 1×10⁻⁶. 5 ~2×10 5 Its melt index is 4g / 10min-5g / 10min.

[0013] Preferably, the ratio of the mass of the polymerized rosin to the volume of tetrahydrofuran is 1g:14mL-18mL.

[0014] Preferably, the ratio between the mass of the polyhexamethylene biguanide and the volume of deionized water is 1g:20mL-25mL.

[0015] Preferably, the ratio of the mass of the polymerized rosin, the mass of the polyhexamethylene biguanide, and the volume of the triethylamine is 3.5g:5g-6g:5mL-8mL.

[0016] This invention also provides a method for preparing polylactic acid-based antibacterial masterbatch, comprising the following steps:

[0017] S21. Polylactic acid is ground into powder to obtain powdered PLA, and then the powdered PLA and antibacterial grafted polymerized rosin powder are dried.

[0018] S22. The dried powdered PLA and antibacterial grafted polymerized rosin powder are mixed in different proportions, and then melt-blended and extruded using a twin-screw extruder. After melt stretching and air cooling, the mixture is pelletized to obtain polylactic acid-based antibacterial masterbatch.

[0019] Preferably, the particle size of the powdered PLA is 20-50 mesh.

[0020] Preferably, the temperature of each zone of the twin-screw extruder is 180℃-195℃, and the screw speed is 20r / min-30r / min.

[0021] This invention also provides an application of polylactic acid-based antibacterial masterbatch in the textile field.

[0022] The present invention further provides an antibacterial composite fiber, which is obtained by melt spinning the above-mentioned polylactic acid-based antibacterial masterbatch.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] This invention constructs a novel polymerized rosin graft modification system and establishes a preparation process for PLA / PR-g-PHMB composite antibacterial fibers. Through optimization of the formulation and system structure, it effectively overcomes the technical difficulties of insufficient mechanical properties and low antibacterial efficiency of traditional antibacterial fibers. The resulting composite fiber has both high-efficiency antibacterial properties, good mechanical strength and thermal stability. The preparation process is simple and controllable, and its industrialization and market application value are outstanding.

[0025] Experimental results show that the composite fiber of this invention only requires a low dosage of 1-5 wt% to simultaneously achieve a significant improvement in both mechanical and functional properties, greatly expanding its application space in medical protective and high-end textile fields. At a modifier dosage of 5 wt%, the biguanide groups of polyhexamethylene biguanide ionize upon contact with water to form a high-density positive charge, endowing the material with strong antibacterial capabilities, achieving antibacterial rates of 99.99% and 99.41% against Staphylococcus aureus and Escherichia coli, respectively. Under a low dosage of 3 wt%, the fiber breaking strength decreases only slightly by about 18%, while the breaking elongation increases by 26%, effectively improving the inherent brittleness of polylactic acid while still maintaining good antibacterial properties, achieving an ideal balance between material toughness and antibacterial function. Attached Figure Description

[0026] Figure 1 The reaction equation for the antibacterial grafted polymerized rosin PR-g-PHMB of this invention is shown in the figure. Detailed Implementation

[0027] To make the above features and advantages of the present invention more apparent and understandable, specific embodiments are described below in conjunction with the accompanying drawings for detailed explanation.

[0028] The polylactic acid (PLA) used in this invention was purchased from Anhui Fengyuan Futailai Polylactic Acid Co., Ltd., with the product name "Polylactic Acid Particles FY802", specification for industrial use, and a relative molecular mass of 1×10⁻⁶. 5 ~2×10 5 Its melt index is 4g / 10min (190℃ / 2.16kg); the polymeric rosin (PR) was purchased from Shenzhen Yoshida Chemical Co., Ltd., with a softening point of 135-145℃ and an acid value of 140mgKOH / g; anhydrous ethanol (AR) and polyhexamethylene biguanide (PHMB) were purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; triethylamine (AR grade) and tetrahydrofuran (THF, 99.9%) were both purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0029] This invention provides an antibacterial composite fiber, which is obtained by melt spinning of polylactic acid-based antibacterial masterbatch. The polylactic acid-based antibacterial masterbatch is made by melt blending polylactic acid and antibacterial grafted polymeric rosin PR-g-PHMB, wherein the mass of polylactic acid and the mass of antibacterial grafted polymeric rosin PR-g-PHMB are mixed according to the ratio in Table 1.

[0030] The preparation process of antibacterial grafted polymeric rosin PR-g-PHMB in each embodiment is as follows: 3.5g of polymeric rosin is dissolved in 50mL of tetrahydrofuran (THF) and stirred at 60℃ to form a clear and homogeneous solution; 5g of polyhexamethylene biguanide is dissolved in 100mL of water and added dropwise to the THF solution of polymeric rosin, stirred for 30min, then 5mL of triethylamine (TEA) is added, and the reaction is carried out at 60℃ for 12h; after cooling, 200mL of anhydrous ethanol (EtOH) is added to the system, a solid precipitates, is filtered and washed, and dried under vacuum at 50℃ to obtain antibacterial grafted polymeric rosin powder PR-g-PHMB. The reaction equation is shown below. Figure 1 .

[0031] The preparation process of the polylactic acid-based antibacterial masterbatch in each embodiment is as follows: polylactic acid is ground to obtain powdered PLA with a particle size of 20-50 mesh, and then the powdered PLA and antibacterial grafted polymerized rosin powder are dried; the dried powdered PLA and antibacterial grafted polymerized rosin powder are mixed in the above proportion, and then melt-blended and extruded using a twin-screw extruder. The specific temperatures of zones one to six of the twin-screw extruder are 190℃, 195℃, 195℃, 195℃, 185℃, and 180℃, respectively, and the screw speed is controlled at 25 r / min. After melt stretching and air cooling, the product is pelletized to obtain the polylactic acid-based antibacterial masterbatch.

[0032] The preparation process of the antibacterial composite fiber in each embodiment is as follows: polylactic acid-based antibacterial masterbatch is spun through a melt spinning machine to obtain fiber products; the temperatures of the melt spinning machine are: 175°C for the upper chamber plate and 180°C for the lower chamber plate, and the spinning stretching speed is 1000 r / min; the spinning setting temperature is 65°C and the time is 8 min.

[0033] Table 1: Raw material ratios of polylactic acid-based antibacterial masterbatches in Examples 1-5 of the present invention

[0034]

[0035] Comparative Example 1

[0036] The fiber in this comparative example uses polylactic acid particles FY802 as raw material and undergoes the same melting process.

[0037] Comparative Example 2

[0038] The only difference between this comparative example and Example 5 is that the PR-g-PHMB in the masterbatch is replaced with an equal amount of unmodified polymerized rosin PR.

[0039] The mechanical properties of Examples 1-5 and Comparative Examples 1-2 were tested according to GB / T14337 "Test Method for Tensile Properties of Chemical Fiber Filaments" and the antibacterial properties were tested according to GB / T20944.2-2008 "Evaluation of Antibacterial Properties of Textiles - Part 3: Vibration Method". The test results are shown in Tables 2 and 3.

[0040] Table 2: Mechanical test results of Examples 1-5 and Comparative Examples 1-2 of the present invention

[0041]

[0042] As shown in Table 2, the overall tensile strength of the composite fiber decreased after the introduction of PR-g-PHMB, while the elongation at break continuously increased. This is because PR-g-PHMB molecules contain flexible groups such as long-chain alkyl groups and cyclic flexible segments, which can act as flexible structural units embedded between the rigid PLA molecular chains, weakening the interactions between PLA molecular chains and making it easier for molecular chain segments to slip. In addition, PR-g-PHMB inhibits the crystallization behavior of PLA, reducing the crystallinity and crystal structure integrity of the system, further weakening the rigid scaffold support of the fiber. The combined effect of these multiple factors leads to a decrease in fiber tensile strength and an increase in elongation at break.

[0043] When the PR-g-PHMB addition amount is 3wt%, compared with pure PLA fiber (Comparative Example 1), the breaking strength decreases by about 18%, the breaking elongation increases by about 26%, and the fiber toughness is significantly improved; if the PR-g-PHMB content is further increased, the breaking strength will decrease slightly, but it can still meet the basic usage requirements of subsequent weaving processes.

[0044] In comparison, the overall mechanical properties of Comparative Example 2 are inferior to those of the samples in the various embodiments.

[0045] Table 3: Antibacterial test results of Examples 1-5 and Comparative Examples 1-2 of the present invention

[0046]

[0047] Table 3 shows that the inhibition rates of pure PLA fiber (Comparative Example 1) against Escherichia coli and Staphylococcus aureus were only 11.11% and 31.92%, respectively, indicating that the PLA matrix itself has weak antibacterial properties. After introducing the polyhexamethylene biguanide functional component, the composite fiber showed a significant inhibitory effect on bacterial growth and proliferation, and the antibacterial effect continued to improve with the increase of the proportion of grafted modified polymeric rosin. When the amount of modified component was 3 wt%, the composite fiber already had excellent antibacterial ability; when the amount was increased to 5 wt%, the inhibition rates against Escherichia coli and Staphylococcus aureus reached as high as 99.41% and 99.99%, respectively. In contrast, the single modified polymeric rosin sample without the introduction of functional components (Comparative Example 2) had almost no antibacterial effect.

[0048] The foregoing has shown and described the basic principles, main features and advantages of this invention. Those skilled in the art should understand that this invention is not limited to the above embodiments. The embodiments and descriptions in the specification are only illustrative of the principles of this invention. Various changes and modifications can be made to this invention without departing from the spirit and scope of this invention. All such changes and modifications fall within the scope of this invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A polylactic acid-based antibacterial master batch, characterized by: It consists of the following components by weight percentage: polylactic acid 95-99%, antibacterial grafted polymeric rosin 1-5%; The preparation process of the antibacterial grafted polymerized rosin includes the following steps: S11. Dissolve polymerized rosin in tetrahydrofuran solution to obtain polymerized rosin solution; S12. Dissolve polyhexamethylene biguanide in deionized water to obtain an aqueous solution of polyhexamethylene biguanide; S13. Add polyhexamethylene biguanide aqueous solution dropwise to the polymerized rosin solution in step S11, stir, then add triethylamine, and reflux at 60℃-70℃. S14. After the substrate reaction was confirmed to be complete by TLC, anhydrous ethanol was added to the system, and a solid was precipitated. The solid was then filtered, washed, and vacuum dried to obtain antibacterial grafted polymerized rosin.

2. The polylactic acid-based antibacterial master batch according to claim 1, characterized by: The polymerized rosin has a softening point of 135℃-145℃ and an acid value of 140mgKOH / g-150mgKOH / g; the polylactic acid has a relative molecular mass of 1×10⁻⁶. 5 ~2×10 5 Its melt index is 4g / 10min-5g / 10min.

3. The polylactic acid-based antibacterial master batch according to claim 1, characterized by: The ratio of the mass of the polymerized rosin to the volume of tetrahydrofuran is 1g:14mL-18mL.

4. The polylactic acid-based antibacterial masterbatch according to claim 1, characterized in that: The ratio of the mass of the polyhexamethylene biguanide to the volume of deionized water is 1g:20mL-25mL.

5. The polylactic acid-based antibacterial masterbatch according to claim 1, characterized in that: The ratio of the mass of the polymerized rosin, the mass of the polyhexamethylene biguanide, and the volume of the triethylamine is 3.5g:5g-6g:5mL-8mL.

6. A method of preparing the polylactic acid-based antibacterial master batch according to claim 1, characterized by, Includes the following steps: S21. Polylactic acid is ground into powder to obtain powdered PLA, and then the powdered PLA and antibacterial grafted polymerized rosin powder are dried. S22. The dried powdered PLA and antibacterial grafted polymerized rosin powder are mixed in different proportions, and then melt-blended and extruded using a twin-screw extruder. After melt stretching and air cooling, the mixture is pelletized to obtain polylactic acid-based antibacterial masterbatch.

7. The polylactic acid-based antibacterial master batch according to claim 6, characterized by: The particle size of the powdered PLA is 20-50 mesh.

8. The polylactic acid-based antibacterial master batch according to claim 6, characterized by: The temperature of each zone of the twin-screw extruder is 180℃-195℃, and the screw speed is 20r / min-30r / min.

9. The application of the polylactic acid-based antibacterial masterbatch as described in claim 1 in the textile field.

10. An antibacterial composite fiber, characterized by: It is prepared by melt spinning of the polylactic acid-based antibacterial masterbatch as described in claim 1.

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