PLA / PR / ZnO composite modified fiber and preparation method thereof

Abstract

The invention discloses a PLA / PR / ZnO composite modified fiber and a preparation method thereof, and belongs to the technical field of high polymer materials and modified fibers. According to the method, polymerized rosin and nano-zinc oxide are introduced into a PLA matrix, and the modified PLA fiber with the antibacterial property while the toughness of the polylactic acid fiber is enhanced is obtained by utilizing the synergistic effect of the polymerized rosin and the nano-zinc oxide. When PR and ZnO are introduced into a PLA matrix at the same time, after 0.5 wt% of zinc oxide and 1 wt% of zinc oxide are added, the breaking strength of the fiber is improved from 35.84% to 56.52% and 55.82%. The preparation method disclosed by the invention is simple, environment-friendly in process and high in controllability. The modified fiber is widely applicable to the fields of medical textiles, environment-friendly packaging materials, antibacterial functional clothes and other high-performance fibers, and opens up a new direction for application of PLA-based materials in functional polymer materials.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials and modified fibers, and in particular to a PLA / PR / ZnO composite modified fiber and a preparation method thereof. Background Art

[0002] With the increasing attention paid to environmental protection and sustainable development, the research and development of biodegradable materials has gradually become a research hotspot in the field of modern materials science. Polylactic acid (PLA), a degradable polymer made from renewable resources (such as corn, sugarcane, etc.), has good biocompatibility, mechanical properties and low environmental burden, so it is widely used in packaging, textiles, medical dressings and other fields. However, the application of PLA is still subject to some limitations, mainly manifested in its low heat resistance, poor antibacterial properties, and relatively fragile mechanical properties, which restricts its application in certain specific fields, especially in medical and protective products.

[0003] In order to overcome these limitations, researchers began to explore improving the performance of PLA through composite modification. In recent years, polymerized rosin (PR) has received extensive attention in the field of biodegradable materials due to its excellent processability, naturalness and certain antibacterial properties. Polymerized rosin can not only enhance the thermoplasticity and processing fluidity of PLA, but also improve its surface properties and antibacterial properties. The ZnO material combined with it has become an ideal supplement with its unique antibacterial, UV resistance and improved thermal stability.

[0004] At present, there have been some studies on PLA / PR composites, but the research on PLA / PR / ZnO composites is still in its infancy, especially in the field of fibers. PLA / PR composites have been initially applied to improve the antibacterial properties and mechanical properties of fibers, but in actual production, they still face problems such as unstable antibacterial effects and insufficient tensile properties.

[0005] In addition, the existing PLA fiber production process has high energy consumption and is difficult to process. How to improve the comprehensive performance of the material through simple and effective composite modification, especially in terms of improving antibacterial, heat resistance, mechanical strength and sustainability, is still a problem that needs to be solved urgently. Summary of the invention

[0006] Technical issues

[0007] PLA / PR composite materials face problems such as unstable antibacterial effect and insufficient tensile strength. It is necessary to provide a method for preparing PLA composite materials with high antibacterial and high tensile strength.

[0008] Technical content

[0009] The object of the present invention is to provide a PLA / PR / ZnO composite modified fiber and a preparation method thereof, wherein the method introduces polymerized rosin (PR) and nano zinc oxide (ZnO), improves the toughness structure of PLA fiber through the synergistic effect of PR and ZnO in melt spinning, and imparts antibacterial properties. The prepared composite modified fiber meets the requirements of high-performance textile materials, especially the requirements of medical fibers, functional textiles and other fields, and has important practical application value and market prospects.

[0010] The technical solution adopted by the present invention to solve its technical problem is:

[0011] A PLA / PR / ZnO masterbatch, wherein the PLA / PR / ZnO masterbatch is composed of the following components in percentage by mass:

[0012] Polylactic acid (PLA): 59-80%,

[0013] Polymerized rosin (PR): 19-40%,

[0014] Nano zinc oxide (ZnO): 0.5-2%.

[0015] Furthermore, the PLA / PR / ZnO masterbatch is composed of the following components in percentage by mass:

[0016] Polylactic acid (PLA): 64-75%,

[0017] Polymerized rosin (PR): 24-35%,

[0018] Nano zinc oxide (ZnO): 0.5-1.5%.

[0019] Preferably, the PLA / PR / ZnO masterbatch is composed of the following components in percentage by mass:

[0020] Polylactic acid (PLA): 66-73%,

[0021] Polymerized rosin (PR): 26-33%,

[0022] Nano zinc oxide (ZnO): 0.5-1%.

[0023] Furthermore, the PLA is thermoplastic polylactic acid with a melting point of 175°C.

[0024] Furthermore, the softening point of the polymerized rosin is 130-140°C.

[0025] Furthermore, the relative molecular mass of the polylactic acid is 1 to 2×10 5 , and its melt index is 4-5g / 10min.

[0026] Furthermore, the relative molecular weight of the polymerized rosin is 600-1000, and the melt index is 20-80 g / 10 min.

[0027] Furthermore, the nano zinc oxide has an average particle size of 25 to 35 nm and a purity greater than 99.9%.

[0028] The PLA / PR / ZnO masterbatch provided by the present invention is applied in the textile field and the environmental protection material field.

[0029] Furthermore, the application in the textile field includes preparing fibers using PLA / PR / ZnO masterbatch.

[0030] Furthermore, the application in the field of environmentally friendly materials includes using PLA / PR / ZnO masterbatch to prepare thin films.

[0031] A method for preparing a PLA / PR / ZnO masterbatch comprises the following steps:

[0032] (1) grinding PLA to obtain powdered PLA, and then drying the powdered PLA and polymerized rosin;

[0033] (2) The dried powdered PLA and polymerized rosin are mixed, and then ZnO nanoparticles are added, and then melt-blended and extruded using a twin-screw extruder. After melt-drawing and air-cooling, the mixture is pelletized to obtain a PLA / PR / ZnO masterbatch.

[0034] As an embodiment of the present invention, in step (1), the particle size of the powdered PLA is preferably controlled to be 20 mesh to 50 mesh; theoretically, the smaller the particle size, the better, but in actual operation, due to the large amount of heat generated during the mechanical grinding process, grinding the PLA too finely may cause thermal degradation of part of the PLA.

[0035] As an embodiment of the present invention, in step (1), the amount of polylactic acid added is 59 to 80 wt % of the mass of the PLA / PR / ZnO masterbatch.

[0036] As an embodiment of the present invention, in step (1), the amount of polymerized rosin added is 19-40 wt % of the mass of the PLA / PR / ZnO masterbatch.

[0037] As an embodiment of the present invention, in step (1), the drying condition is 60±5°C for 12±5h.

[0038] As an embodiment of the present invention, in step (2), the temperature of each zone of the twin-screw extruder is 170°C to 185°C, and the screw speed is 60-75r / min.

[0039] As an embodiment of the present invention, in step (2), the amount of ZnO nanoparticles added is 0.5-2 wt % of the mass of the PLA / PR / ZnO masterbatch.

[0040] Preferably, in step (2), the amount of ZnO nanoparticles added is 0.5-1 wt % of the mass of the PLA / PR / ZnO masterbatch.

[0041] A PLA / PR / ZnO composite modified fiber, the PLA / PR / ZnO composite modified fiber is composed of the following components in percentage by mass:

[0042] Polylactic acid (PLA): 59-80%,

[0043] Polymerized rosin (PR): 19-40%,

[0044] Nano zinc oxide (ZnO): 0.5-2%.

[0045] Furthermore, the PLA / PR / ZnO composite modified fiber is composed of the following components in percentage by mass:

[0046] Polylactic acid (PLA): 64-75%,

[0047] Polymerized rosin (PR): 24-35%,

[0048] Nano zinc oxide (ZnO): 0.5-1.5%.

[0049] Preferably, the PLA / PR / ZnO composite modified fiber is composed of the following components in percentage by mass:

[0050] Polylactic acid (PLA): 66-73%,

[0051] Polymerized rosin (PR): 26-33%,

[0052] Nano zinc oxide (ZnO): 0.5-1%.

[0053] Furthermore, the PLA is thermoplastic polylactic acid with a melting point of 175°C.

[0054] Furthermore, the softening point of the polymerized rosin is 130-140°C.

[0055] Furthermore, the relative molecular mass of the polylactic acid is 1 to 2×10 5 , and its melt index is 4g / 10min.

[0056] Furthermore, the relative molecular weight of the polymerized rosin is 600-1000, and the melt index is 20-80 g / 10 min.

[0057] Furthermore, the nano zinc oxide has an average particle size of 25 to 35 nm and a purity greater than 99.9%.

[0058] The PLA / PR / ZnO composite modified fiber provided by the present invention is used in the production of protective clothing, antibacterial medical products or degradable materials.

[0059] The present invention provides a method for preparing a PLA / PR / ZnO composite modified fiber, comprising the following steps:

[0060] (1) grinding PLA to obtain powdered PLA, and then drying the powdered PLA and polymerized rosin;

[0061] (2) mixing the dried powdered PLA and polymerized rosin, adding ZnO nanoparticles, and then using a twin-screw extruder to melt-blend and extrude, and then pelletizing after melt-drawing and air-cooling to obtain PLA / PR / ZnO masterbatch;

[0062] (3) melt spinning the PLA / PR / ZnO masterbatch obtained in step (2) through a twin-screw extruder to obtain a composite modified fiber product;

[0063] (4) subjecting the composite modified fiber obtained in step (3) to heat setting treatment.

[0064] As an embodiment of the present invention, in step (1), the particle size of the powdered PLA is preferably controlled to be 20 mesh to 50 mesh; theoretically, the smaller the particle size, the better, but in actual operation, due to the large amount of heat generated during the mechanical grinding process, grinding the PLA too finely may cause thermal degradation of part of the PLA.

[0065] As an embodiment of the present invention, in step (1), the amount of polylactic acid added is 59 to 80 wt % of the mass of the PLA / PR / ZnO masterbatch.

[0066] As an embodiment of the present invention, in step (1), the amount of polymerized rosin added is 19-40 wt % of the mass of the PLA / PR / ZnO masterbatch.

[0067] As an embodiment of the present invention, in step (1), the drying condition is 60±5°C for 12±5h.

[0068] As an embodiment of the present invention, in step (2), the temperature of each zone of the twin-screw extruder is 170°C to 185°C, and the screw speed is 60-75r / min.

[0069] As an embodiment of the present invention, in step (2), the amount of ZnO nanoparticles added is 0.5-2 wt % of the mass of the PLA / PR / ZnO masterbatch.

[0070] Preferably, in step (2), the amount of ZnO nanoparticles added is 0.5-1 wt % of the mass of the PLA / PR / ZnO masterbatch.

[0071] As an embodiment of the present invention, in step (3), the temperature of each zone of the melt spinning is 175°C to 185°C, and the drawing speed is 1000r / min to 1200r / min.

[0072] As an embodiment of the present invention, in step (4), the spinning temperature is 60-65°C and the time is 5-10 minutes.

[0073] Beneficial effects of the present invention:

[0074] (1) Simple preparation: The present invention adopts a simple and efficient melt blending modification, comprehensively utilizes the advantages of PLA, PR, and ZnO materials, and utilizes the synergistic effect of PR and ZnO to improve the toughness structure of PLA materials, while imparting antibacterial properties. A PLA / PR / ZnO blended composite material with good compatibility is prepared, and it is then processed into a PLA / PR / ZnO composite fiber through a melt spinning machine.

[0075] (2) Environmental protection of raw materials: The main material used in the present invention is renewable and degradable synthetic polymer polylactic acid, which has sufficient raw materials and good biodegradability and can be completely degraded into water and carbon dioxide. The polymerized rosin used is of natural origin, biodegradable, and has good compatibility, durability, and antioxidant properties. The nano zinc oxide used is an inorganic material, the preparation process is relatively environmentally friendly, and it can be degraded under natural conditions, reducing pollution to the environment, which is consistent with the environmental friendliness of degradable matrix materials such as polylactic acid. Compared with traditional antibacterial agents, nano zinc oxide has a long-lasting antibacterial effect and has no toxic side effects on the human body, meeting safety and environmental protection requirements.

[0076] (3) Excellent effect: In the present invention, polylactic acid is blended with polymerized rosin, and zinc oxide nanoparticles are introduced as an antibacterial agent. The synergistic effect of nano zinc oxide and polymerized rosin is utilized to effectively improve the tensile strength and elastic modulus of PLA fiber, so that it has higher mechanical strength and meets the requirements for toughness in practical applications. When the addition amount of nano zinc oxide is 1wt%, the elongation at break increases from 35.84% to 56.52%, and the elongation at break increases by 1.58 times; although the breaking strength decreases from 1.60cN / dtex to 1.50cN / dtex, the decrease is small and has little effect on the overall. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] Figure 1 The figures are the mechanical property test results of the embodiments and comparative examples. DETAILED DESCRIPTION

[0078] The preferred embodiments of the present invention are described below. It should be understood that the embodiments are for better explaining the present invention and are not used to limit the present invention.

[0079] The polylactic acid particles used in the present invention can be purchased from Anhui Fengyuan Futailai Polylactic Acid Co., Ltd. Polylactic acid particles FY801; polymerized rosin particles with a specification of industrial 140 can be purchased from Shenzhen Yoshida Chemical Co., Ltd., with a softening point of 135-145°C and an acid value of 140 mgKOH / g; ZnO nanoparticles can be purchased from Shanghai Hansi Chemical Co., Ltd., with a particle size of 30 nm.

[0080] Example 1

[0081] (1) Preparation of PLA-PR masterbatch

[0082] Prepare raw materials: PLA 21g, PR 9g

[0083] The powdered PLA and polymerized rosin are stirred evenly in a beaker, and then the mixed raw materials are melt-blended and extruded through a twin-screw extruder, and pelletized after melt drawing and air cooling to obtain PLA-PR masterbatch.

[0084] The temperatures of zones 1 to 6 of the twin-screw extruder are 180°C, 185°C, 185°C, 185°C, 175°C, and 170°C, respectively, and the screw speed is controlled at 60-75r / min.

[0085] (2) Preparation of PLA / PR composite modified fiber materials

[0086] The prepared PLA-PR masterbatch is spun through a melt spinning machine to obtain a PLA / PR composite modified fiber product.

[0087] The temperatures of the melt spinning machine are: 175°C for the upper cavity plate, 180°C for the lower cavity plate, the spinning drafting speed is 1000r / min-1200r / min, the spinning setting temperature is 60-65°C, and the time is 5-10min.

[0088] Example 2

[0089] The difference from Example 1 is the ratio of raw materials in step (1), which is PLA 21g, PR 9g, and ZnO 0.151g.

[0090] Example 3

[0091] The difference from Example 1 is the ratio of raw materials in step (1), which is PLA 21g, PR 9g, and ZnO 0.303g.

[0092] Example 4

[0093] The difference from Example 1 is the ratio of raw materials in step (1), which is PLA 21g, PR 9g, ZnO 0.612g.

[0094] Comparative Example 1

[0095] The difference from Example 1 is the ratio of raw materials in step (1), wherein the raw material is 30 g of PLA.

[0096] Comparative Example 2

[0097] The difference from Example 1 is the ratio of raw materials in step (1), which is 29.85 g of PLA and 0.15 g of ZnO.

[0098] Comparative Example 3

[0099] The difference from Example 1 is the ratio of the raw materials in step (1), which are 29.7 g PLA and 0.3 g ZnO.

[0100] Comparative Example 4

[0101] The difference from Example 1 is the ratio of the raw materials in step (1), which are 29.4 g PLA and 0.6 g ZnO.

[0102] The raw material ratios and compositions in the various embodiments and comparative examples are summarized as shown in Table 1.

[0103] Table 1 Summary of original proportions in the embodiments and comparative examples (unit: g)

[0104] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 PLA 21 21 21 21 30 29.85 29.70 29.40 PR 9 9 9 9 0 0 0 0 ZnO 0 0.151 0.303 0.612 0 0.15 0.3 0.6

[0105] The mechanical properties of the above-mentioned examples 1 to 4 and comparative examples 1 to 4 were tested, and the test results are shown in Figure 1 And Table 2. The test method refers to GB / T14337 "Test method for tensile properties of chemical fiber filaments".

[0106] Table 2 Mechanical properties test results of the embodiments and comparative examples

[0107] Breaking strength (cN / dtex) Elongation at break (%) Example 1 1.6 35.84 Example 2 1.5 56.52 Example 3 1.52 55.82 Example 4 1.19 57.12 Comparative Example 1 2.06 30.42 Comparative Example 2 1.66 35.55 Comparative Example 3 1.63 38.59 Comparative Example 4 1.8 31.85

[0108] from Figure 1As can be seen from Table 2, when no polymerized rosin is added, low concentrations of ZnO nanoparticles (0.5wt% and 1wt%) slightly increase the elongation at break of PLA fibers, from 30.42% of pure PLA to 35.55% and 38.59%. However, when the concentration of ZnO nanoparticles increases to 2wt%, the elongation of the fiber increases less, only from 30.42% to 31.85%. The change in breaking strength is generally a downward trend (from 2.06cN / dtex to 1.63cN / dtex), and the increase in breaking elongation is generally accompanied by a decrease in breaking strength.

[0109] When polymerized rosin and nano zinc oxide are introduced into the PLA matrix at the same time, the synergistic effect of the two can optimize the comprehensive performance of PLA fiber at a certain concentration. When the addition amount of ZnO nanoparticles is 0.5wt%, it can be seen from the data of comparative example 2 that the elongation at break is increased by 5.08%, and the elongation at break of PR is increased by 5.42%, and when 0.5wt% ZnO and PR act together, the elongation at break is increased by 26.1%, which is much greater than 5.08%+5.42%; when the addition amount of ZnO nanoparticles is 1wt%, it can be seen from the data of comparative example 3 that the elongation at break is increased by 8.17%, and the elongation at break of PR is increased by 5.42%, and when 1wt% ZnO and PR act together, the elongation at break is increased by 25.4%, which is also much greater than 8.17%+5.42%.

[0110] Therefore, it can be seen from Examples 2 and 3 that when low concentrations of ZnO nanoparticles (0.5wt% and 1wt%) and polymerized rosin work together, they can synergistically improve the elongation of PLA fibers, and can also maintain a relatively high strength (1.50cN / dtex and 1.52cN / dtex) to a certain extent, showing excellent tensile properties.

[0111] The antibacterial properties of the above-mentioned Examples 1 to 4 and Comparative Examples 1 to 4 were tested, and the test results are shown in Table 3. The test method refers to GB / T20944.2-2008 "Evaluation of antibacterial properties of textiles Part 3: Oscillation method".

[0112] Table 3 Antibacterial performance test results of the embodiments and comparative examples

[0113]

[0114] From the data in Table 3, it can be seen that the antibacterial rates of Comparative Example 1 against Escherichia coli and Staphylococcus aureus are 29% and 54% respectively, indicating that the antibacterial performance of pure PLA fiber is relatively limited. In Example 1, without the addition of ZnO nanoparticles, the antibacterial rates against Escherichia coli and Staphylococcus aureus are 69% and 73% respectively, which are significantly improved compared with pure PLA (Comparative Example 1). Rosin itself has certain natural antibacterial properties, especially showing a good inhibitory effect on Staphylococcus aureus.

[0115] With the increase of the mass fraction of ZnO nanoparticles, the antibacterial rates of Comparative Examples 2 to 3 are significantly improved compared with Comparative Example 1. When the mass fraction of ZnO nanoparticles is 1wt%, the antibacterial rate against Staphylococcus aureus reaches 90%, showing excellent antibacterial properties. However, when the mass fraction of ZnO nanoparticles is 2wt%, the reason why the antibacterial rate decreases compared with Comparative Examples 2 and 3 may be that the nanoparticles may not be evenly dispersed in the matrix and are prone to aggregation and agglomeration. The aggregation of particles will cause the surface area of ​​the particles to be significantly reduced, thereby reducing the chance of contact with bacteria, resulting in a decrease in antibacterial properties. The change trends of Examples 2 to 4 are also the same. It is worth noting that the antibacterial rates of Example 3 against Escherichia coli and Staphylococcus aureus reached 90% and 94%, which are higher than those of Comparative Example 3. It can be shown that there is a synergistic effect between polymerized rosin and ZnO nanoparticles, which can further improve the antibacterial properties of PLA fibers.

[0116] In summary, the present invention provides a novel PLA / PR / ZnO composite modified fiber and a preparation method thereof. By rationally designing the composite system and optimizing the formula, the problems of poor mechanical properties and insufficient antibacterial effect of existing antibacterial fiber materials are successfully solved. The composite fiber has significant advantages in antibacterial properties, mechanical properties, thermal stability, etc., and the preparation process is simple and has good market application potential. The present invention not only has important technical innovation, but also has broad commercial prospects, and has a positive role in promoting the textile industry, especially in the field of antibacterial materials.

[0117] The embodiments provided above are not intended to limit the scope of the present invention, and the steps described are not intended to limit the execution order thereof. Those skilled in the art may make obvious improvements to the present invention in combination with existing common knowledge, which also fall within the scope of protection defined by the claims of the present invention.

Claims

1. A PLA / PR / ZnO masterbatch, characterized in that: The PLA / PR / ZnO masterbatch is composed of the following components in percentage by mass: composition: Polylactic acid: 59-80%, Polymerized rosin: 19-40%, Nano zinc oxide: 0.5-2%.

2. The PLA / PR / ZnO masterbatch according to claim 1, characterized in that: The PLA / PR / ZnO masterbatch is composed of the following components in percentage by mass: composition: Polylactic acid: 64-75%, Polymerized rosin: 24-35%, Nano zinc oxide: 0.5-1.5%.

3. The PLA / PR / ZnO masterbatch according to claim 1 or 2, characterized in that: The relative molecular mass of the polylactic acid is 1 to 2×10 5 , and its melt index is 4-5g / 10min; the relative molecular weight of the polymerized rosin is 600-1000, and its melt index is 20-80g / 10min; the average particle size of the nano zinc oxide is 25-35nm.

4. The method for preparing the PLA / PR / ZnO masterbatch according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) grinding PLA to obtain powdered PLA, and then drying the powdered PLA and polymerized rosin; (2) The dried powdered PLA and polymerized rosin are mixed, and then ZnO nanoparticles are added, and then melt-blended and extruded using a twin-screw extruder. After melt-drawing and air-cooling, the mixture is pelletized to obtain a PLA / PR / ZnO masterbatch.

5. The preparation method according to claim 4, characterized in that: The particle size of the powdered PLA in step (1) is 20 mesh to 50 mesh.

6. The preparation method according to claim 4, characterized in that: The drying condition described in step (1) is drying at 60±5°C for 12±5h.

7. The preparation method according to claim 4, characterized in that: In step (2), the temperature of each zone of the twin-screw extruder is 170°C to 185°C, and the screw speed is 60-75r / min.

8. Use of the PLA / PR / ZnO masterbatch according to any one of claims 1 to 3 in the field of textiles or environmentally friendly materials.

9. A PLA / PR / ZnO composite modified fiber, characterized in that: The PLA / PR / ZnO composite modified fiber is prepared from the PLA / PR / ZnO masterbatch described in any one of claims 1 to 3.

10. The method for preparing the PLA / PR / ZnO composite modified fiber as claimed in claim 9, characterized in that: The following steps are involved: (1) grinding PLA to obtain powdered PLA, and then drying the powdered PLA and polymerized rosin; (2) mixing the dried powdered PLA and polymerized rosin, adding ZnO nanoparticles, and then using a twin-screw extruder to melt-blend and extrude, and then pelletizing after melt-drawing and air-cooling to obtain PLA / PR / ZnO masterbatch; (3) melt spinning the PLA / PR / ZnO masterbatch obtained in step (2) through a twin-screw extruder to obtain a composite modified fiber product; the temperature of each zone of the melt spinning is 175° C. to 185° C., and the drafting speed is 1000 r / min to 1200 r / min; (4) subjecting the composite modified fiber obtained in step (3) to a heat setting treatment, wherein the spinning setting temperature is 60 to 65° C.; The time is 5-10 minutes.

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