Antistatic polylactic acid plastic and preparation method thereof

Abstract

The invention relates to the field of polymer materials, and discloses an antistatic polylactic acid plastic and a preparation method thereof, the antistatic polylactic acid plastic comprises the following components by mass: 80-85 parts of polylactic acid; 5 to 10 parts of amphiphilic conductive molecules; 3-7 parts of a nano supramolecular structure; 1-3 parts of an interface reinforcing agent; 0.5 to 2 parts of a weather-resistant stabilizer; the method comprises the following steps: constructing a nano conductive channel through ultrasonic dispersion, self-assembly and electrostatic deposition methods, optimizing a conductive network in combination with melt blending and electric field orientation, and finally preparing the antistatic polylactic acid plastic by adopting a precise injection molding process to realize collaborative optimization of conductivity, mechanical properties and processability. The conductive network is optimized through electric field orientation, the weather resistance is improved in cooperation with the light stabilizer, the mechanical property is enhanced through interface optimization, the fluidity is improved, the forming efficiency is improved, and preparation of the antistatic, anti-aging, high-strength and excellent-processability polylactic acid plastic is achieved.

Description

Technical Field

[0001] The present invention relates to the field of polymer materials, in particular to an antistatic polylactic acid plastic and a preparation method thereof. Background Art

[0002] Currently, polylactic acid (PLA) is widely used in packaging, electronic device casings, and medical applications due to its excellent biodegradability and environmental friendliness. However, as an insulating material, it easily accumulates static charges in many applications, leading to problems such as dust absorption, damage to electronic components, and even spark discharges. Therefore, improving the antistatic properties of PLA has become a research priority in this field.

[0003] Existing technologies typically use conductive fillers (such as carbon nanotubes, graphene, and metal nanoparticles) to impart conductivity to PLA. However, these fillers have poor dispersion within the polymer matrix and tend to agglomerate, resulting in locally excessive conductivity and insufficient overall uniformity, impacting the material's stability and processing performance. Furthermore, the addition of conductive fillers often degrades the matrix's mechanical properties, making the material brittle and limiting its application in applications requiring high strength.

[0004] On the other hand, PLA itself has poor weather resistance. Long-term exposure to UV light or oxidative environments can lead to molecular chain degradation, manifesting as decreased mechanical properties, surface discoloration, or powdering. Existing technologies typically use light stabilizers or antioxidants to improve weather resistance, but the effectiveness of a single component is limited, and excessive use can cause degradation during processing. Therefore, while improving PLA's antistatic properties, ensuring its long-term stability and aging resistance remains a pressing challenge.

[0005] In addition, PLA has a low melt index and poor processing fluidity, which makes defects such as uneven filling, flow marks, and holes easily appear during injection molding and extrusion molding, affecting the appearance quality and dimensional accuracy of the product. Existing processing modification methods mainly rely on plasticizers or flow aids, but these methods may affect the mechanical properties of PLA and even reduce its environmental protection. At the same time, the introduction of conductive fillers further exacerbates the processing difficulties of the material, resulting in unstable molding and extended production cycle. Therefore, the present invention proposes an antistatic polylactic acid plastic and its preparation method to address the deficiencies of the prior art. Summary of the Invention

[0006] In response to the shortcomings of the existing technology, the present invention provides an antistatic polylactic acid plastic and a preparation method thereof, which solves the problems of unstable antistatic performance caused by uneven dispersion of conductive fillers, aging failure caused by poor weather resistance, decreased mechanical properties, and poor processing fluidity affecting molding quality.

[0007] To achieve the above objectives, the present invention is implemented through the following technical scheme: an antistatic polylactic acid plastic, which includes the following components in parts by mass: polylactic acid: 80-85 parts; amphiphilic conductive molecules: 5-10 parts; nano-supramolecular structure: 3-7 parts; interface enhancer: 1-3 parts; weathering stabilizer: 0.5-2 parts.

[0008] Polylactic acid (PLA): Polylactic acid (PLA), as a matrix material, has excellent biodegradability and environmental friendliness, making it widely used. However, PLA itself is an insulator and has a low melt index and poor fluidity.

[0009] Polylactic acid is fully integrated with other components through melt blending and forms a stable microstructure under electric field orientation. The electric field orientation improves the molecular chain arrangement of PLA and reduces melt viscosity, thereby improving the material's processing fluidity and molding stability.

[0010] Amphiphilic conductive molecules: This molecule has both hydrophilic and lipophilic properties and can form a stable dispersed phase in the PLA matrix.

[0011] During melt blending, the amphiphilic conductive molecules spontaneously migrate to the interfacial region and, through electric field orientation, form a uniform conductive network within the polylactic acid matrix. Their hydrophilic and lipophilic properties ensure a stable conductive path, avoiding the conductive instability caused by aggregation of traditional fillers.

[0012] Nano-supramolecular structure: Nano-supramolecular structures are key components of conductive networks, with high specific surface area and excellent interface compatibility.

[0013] Electrostatically induced deposition (EID) allows the nano-supramolecular structure to be aligned within the matrix, further enhancing the continuity and stability of the conductive network. These nanoscale properties help avoid localized conductive hotspots, improving antistatic properties and maintaining the material's mechanical strength.

[0014] Interface enhancer: Interfacial enhancers promote the interfacial bonding of the components of each phase during the melt blending process and improve the overall stability of the material.

[0015] The interface enhancer strengthens the interfacial bonding force between the PLA matrix and the conductive filler through physical adsorption and chemical reaction, reducing the embrittlement problem of traditional antistatic materials caused by the addition of fillers and further optimizing the mechanical properties of the material.

[0016] Weathering stabilizer: Weathering stabilizers include light stabilizers and antioxidants, which can improve the aging resistance of PLA materials.

[0017] Light stabilizers absorb or scatter UV rays, slowing the breakage of PLA chains. Antioxidants capture free radicals, inhibiting the degradation of PLA in oxidative environments. The synergistic effect of these two agents significantly improves the material's stability during long-term outdoor use and slows performance degradation.

[0018] Preferably, the polylactic acid is a high molecular weight polylactic acid with a molecular weight range of 100,000 g / mol to 200,000 g / mol, and the L-lactic acid unit content is not less than 95%; the amphiphilic conductive molecule is composed of a conjugated polymer with a thiophene structure or a benzothiophene structure, and its chemical structure includes poly(triethylenedioxythiophene) or poly(bis(thiophene)tetrafluorobenzene); the nano-supramolecular structure is composed of a polypyrrole and fullerene complex, and an ultrasonic electrostatic induced deposition method is used to form a nanoscale conductive channel to improve the antistatic properties and charge dissipation capacity of the material.

[0019] The polylactic acid is a high molecular weight polylactic acid with a molecular weight range of 100,000 g / mol to 200,000 g / mol and an L-lactic acid unit content of not less than 95%, ensuring that the material has good mechanical properties and processing stability.

[0020] High-molecular-weight PLA's long molecular chain and moderate crystallinity enable the material to form a stable physical crosslinking network during melt blending, avoiding the increased brittleness associated with low-molecular-weight PLA while improving the material's impact resistance and tensile strength. The high L-lactic acid unit content imparts better crystallinity, enhancing processability and thermal stability.

[0021] The amphiphilic conductive molecule is composed of a conjugated polymer with a thiophene structure or a benzothiophene structure, and its chemical structure includes poly(triethylenedioxythiophene) (PEDOT) or bithiophenetetrafluorobenzene, which ensures the dispersion and stability of the conductive phase in the PLA matrix.

[0022] Thiophene and benzothiophene structures possess an excellent conjugated electron system, enabling the conductive molecules to form π-π interactions within the PLA matrix, enhancing electron transfer efficiency. Their amphiphilic nature promotes self-assembly and distribution at the interface, avoiding the agglomeration problem of traditional conductive fillers, ensuring a uniform and stable conductive network and enhancing antistatic capabilities.

[0023] The nano supramolecular structure is composed of a polypyrrole and fullerene complex, and adopts an ultrasonic electrostatic induced deposition method to form a nanoscale conductive channel, which is used to improve the antistatic performance and charge dissipation capacity of the material.

[0024] Polypyrrole has high electrical conductivity, and fullerene has excellent electron acceptor properties. The two form a stable nanoscale conductive network. Ultrasonic electrostatically induced deposition promotes its uniform distribution within the PLA matrix, creating a continuous conductive path. This improves the material's charge transfer efficiency, effectively reduces surface resistance, and imparts excellent antistatic properties to the material, while also avoiding the risk of failure due to localized over-conductivity.

[0025] Preferably, the interface enhancer is an amide derivative or a maleic anhydride graft, which is used to improve the interfacial compatibility between the polylactic acid matrix and the antistatic phase; the weathering stabilizer includes a light stabilizer and an antioxidant, the light stabilizer is a benzophenone ultraviolet absorber, and the antioxidant is a hindered phenol antioxidant, which is used to improve the material's resistance to ultraviolet aging and long-term stability.

[0026] The interface enhancer is an amide derivative or a maleic anhydride graft, which is used to improve the interface compatibility between the polylactic acid matrix and the antistatic phase and enhance the overall stability of the material.

[0027] Amide derivatives can bind to PLA molecules through hydrogen bonding, while maleic anhydride grafts react chemically with PLA and conductive fillers, improving the interfacial bonding between the two phases. By optimizing interfacial compatibility, the conductive network is evenly distributed, reducing filler agglomeration and avoiding the degradation of mechanical properties caused by poor interfacial compatibility.

[0028] The weathering stabilizer includes a light stabilizer and an antioxidant, wherein the light stabilizer is a benzophenone ultraviolet absorber and the antioxidant is a hindered phenol antioxidant, which are used to improve the material's resistance to ultraviolet aging and long-term stability.

[0029] Benzophenone-based UV absorbers absorb high-energy UV light and convert it into low-energy heat, preventing PLA molecular chain breakage and slowing photodegradation. Hindered phenolic antioxidants scavenge free radicals, inhibiting oxidative degradation and preventing embrittlement from prolonged exposure to air and light. This improves outdoor durability and ensures the material maintains its excellent performance over time.

[0030] The present invention also provides a method for preparing an antistatic polylactic acid plastic, which is applied to the antistatic polylactic acid plastic according to any one of claims 1 to 3, comprising the following steps: S1, dissolving the amphiphilic conductive molecules in an acetonitrile-water mixed solvent and ultrasonically dispersing them in an ultrasonic cleaner, then inducing self-assembly by solvent evaporation to form a nano-interface structure in a constant temperature drying oven; S2, dissolving the nano-supramolecular structure in a toluene-water mixed solvent, adding the solution to a reaction kettle, performing ultrasonic treatment using an ultrasonic disperser, and then forming a conductive channel in an electrostatic deposition device by electrostatic induced deposition; S3, drying the polylactic acid in a vacuum drying oven, placing the polylactic acid in a high-temperature melt mixer for melt blending, first adding the polylactic acid matrix, and then gradually adding the amphiphilic conductive molecules and the nano-supramolecular structure; S4. During the melt blending process, an interfacial enhancer is added and mixed using a twin-screw extruder to ensure that the polylactic acid matrix and the antistatic material are fully integrated; S5. applying a high electric field orientation to the blend, and using an electric field orientation device to optimize the conductive network; S6. Using a precision injection molding process, the treated mixture is injected into a mold in an injection molding machine, and cooled through a cooling water tank to obtain an antistatic polylactic acid plastic product.

[0031] Preferably, in step S1, the amphiphilic conductive molecules are dissolved in an acetonitrile-water mixed solvent with a mass ratio of the solvent of 1:1 to 1:3, and then dispersed in an ultrasonic dispersion device with an ultrasonic power of 200W to 500W and a dispersion time of 20 to 60 minutes; then self-assembly is induced by solvent volatilization, and the operation is carried out in a constant temperature drying device with a volatilization time of 8 to 16 hours.

[0032] Preferably, in step S2, the nano-supramolecular structure is dissolved in a toluene-water mixed solvent with a mass ratio of the solvent of 1:1 to 1:3, and then ultrasonic dispersion is performed in a reactor using an ultrasonic dispersion device with an ultrasonic power of 300W to 600W and a dispersion time of 15 to 30 minutes; a conductive channel is formed by an electrostatic induced deposition method, wherein the deposition process uses an electrostatic device to apply an electric field with a voltage range of 1kV to 3kV and a deposition time of 5 to 15 minutes.

[0033] Preferably, in step S3, the polylactic acid is first dried in a vacuum drying oven for 4 to 8 hours; then the dried polylactic acid is melt-blended with the amphiphilic conductive molecules and the nano-supramolecular structure. During the blending process, the mass fraction of the polylactic acid is 70 to 85 parts, the mass fraction of the amphiphilic conductive molecules is 5 to 10 parts, and the mass fraction of the nano-supramolecular structure is 3 to 8 parts, for uniform dispersion of the materials.

[0034] Preferably, in step S4, an interface enhancer is added in an amount of 1 to 3 parts by weight, and mixing is performed using a twin-screw extruder with a screw speed ranging from 60 rpm to 120 rpm for 8 to 15 minutes.

[0035] Preferably, in step S5, a high electric field is applied to the blend for orientation, the electric field strength ranges from 1 kV / m to 5 kV / m, and the orientation time is from 5 to 15 seconds. The electric field effect can optimize the formation and stabilization of the conductive network.

[0036] Preferably, in step S6, an injection molding machine is used to inject the treated mixture into a mold, the injection pressure range is 80 MPa to 120 MPa, the mold temperature range is 50° C. to 90° C., and the cooling time is 20 to 40 seconds, to finally obtain an antistatic polylactic acid plastic product.

[0037] The present invention provides an antistatic polylactic acid plastic and a preparation method thereof. It has the following beneficial effects: 1. This invention utilizes an electric field orientation optimization strategy to form a uniform and stable conductive network of conductive molecules and nano-supramolecular structures within a polylactic acid matrix, significantly improving the material's antistatic properties. Compared to the prior art method of randomly dispersing conductive fillers, this approach avoids filler aggregation, addressing issues such as unstable conductivity, localized overconductivity, or failure.

[0038] 2. This invention achieves the technical effect of extending the material's service life by optimizing the ratio of light stabilizers to antioxidants, improving the material's weather resistance and UV stability. Compared to existing single-component stabilization systems, this solution synergistically reduces the rates of UV and oxidative degradation, addressing the material's embrittlement and rapid strength loss during long-term outdoor use.

[0039] 3. This invention combines nano-supramolecular structures with amphiphilic conductive molecules to adjust interfacial compatibility to enhance mechanical properties, achieving the technical effect of improving conductivity while maintaining high strength. Compared to existing solutions that make materials brittle due to the addition of fillers, this solution evenly distributes the conductive fillers and optimizes interfacial bonding, resolving the problem of reduced mechanical properties in traditional antistatic materials.

[0040] 4. This invention uses high electric field orientation to control material fluidity, improve melt index, and optimize the molding process, achieving the technical effect of improving processing efficiency and molding stability. Compared with existing molding methods that do not use orientation control, this solution enhances material fluidity in the mold and solves the problems of uneven filling, frequent molding defects, and long production cycles. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a flow chart of the preparation method of the present invention. DETAILED DESCRIPTION

[0042] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the present specification. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0043] See also Figure 1 : Example 1 (Basic Optimization Antistatic Polylactic Acid Plastic) 82 parts of high molecular weight polylactic acid (molecular weight 150000 g / mol, L-lactic acid unit content 96%) were taken and dried in a vacuum drying oven at 50° C. for 6 hours to remove moisture and set aside.

[0044] Eight parts of an amphiphilic conductive molecule (poly(tri-tetraethylenedioxythiophene)) were weighed and dissolved in an acetonitrile-water mixture (mass ratio 1:2). The mixture was ultrasonically treated at 400 W for 40 minutes. The solvent evaporated to induce self-assembly, and the mixture was dried in a 60°C drying oven for 12 hours to form a nanostructured interface.

[0045] Five portions of the nano-supramolecular structure (polypyrrole-fullerene complex) were dissolved in a toluene-water mixture (mass ratio 1:1.5), poured into a reactor, and dispersed in a 500W ultrasonic disperser for 25 minutes. Subsequently, electrostatically induced deposition (ESD) was performed at an electric field strength of 2.5kV for 10 minutes to obtain a uniform conductive network.

[0046] Pour the dried polylactic acid into a high-temperature melt mixer at 180°C and stir at 70 rpm. Gradually add the pre-treated amphiphilic conductive molecules and nano-supramolecular structures. After stirring for 12 minutes, add 3 parts of an interfacial enhancer (maleic anhydride grafted compound) and continue blending for 10 minutes to ensure uniform dispersion.

[0047] The blend was mixed in a twin-screw extruder (screw speed 90 rpm) for 10 minutes, sampled, and tested to confirm good uniformity. Then, an electric field of 3 kV / m was applied for orientation for 8 seconds. The resulting product was then injection molded (injection pressure 100 MPa, mold temperature 70°C) and cooled for 30 seconds to obtain the finished product.

[0048] Example 2 (Improving Mechanical Properties) 85 parts of high molecular weight polylactic acid (molecular weight 180000 g / mol, L-lactic acid unit content 97%) were dried in a vacuum drying oven at 60° C. for 8 hours and set aside.

[0049] Six parts of amphiphilic conductive molecules (bithiophene tetrafluorobenzene) were dissolved in an acetonitrile-water mixed solvent (mass ratio 1:1.5), dispersed under ultrasonic power of 350 W for 30 minutes, and dried at a constant temperature of 60°C for 10 hours to form a nanostructure.

[0050] Four portions of the nano-supramolecular structure (polypyrrole-fullerene complex) were dissolved in a toluene-water mixed solvent (mass ratio 1:2), ultrasonically treated at 500W for 20 minutes, and electrostatically induced deposition (voltage 2kV, deposition for 12 minutes) was used to form a conductive network.

[0051] Polylactic acid was poured into a melt mixer (temperature 190°C, speed 80 rpm), and amphiphilic conductive molecules and nano-supramolecular structures were added in sequence. After stirring for 15 minutes, 3 parts of an interface enhancer (amide derivative) were added and mixed for another 8 minutes to optimize the interface compatibility.

[0052] The blend was mixed for 12 minutes in a twin-screw extruder (screw speed 100 rpm), oriented by applying an electric field of 4 kV / m for 10 seconds, and injection molded (injection pressure 90 MPa, mold temperature 65° C.) with a cooling time of 25 seconds.

[0053] Example 3 (enhanced weather resistance) 80 parts of polylactic acid (molecular weight 120000 g / mol, L-lactic acid unit content 95%) were taken and vacuum dried at 50° C. for 5 hours and set aside.

[0054] 7 parts of amphiphilic conductive molecules (PEDOT) were dissolved in an acetonitrile-water mixed solvent (mass ratio 1:3), ultrasonically dispersed at 400W for 45 minutes, and the solvent evaporated to induce self-assembly. The mixture was dried at 60°C for 10 hours to form a nano-interface structure.

[0055] Six portions of the nano-supramolecular structure (polypyrrole-fullerene complex) were dissolved in a toluene-water mixed solvent (mass ratio 1:1), ultrasonically dispersed at 600W for 30 minutes, and electrostatically induced deposition at 3kV for 8 minutes to form a conductive network.

[0056] Polylactic acid was placed in a melt mixer (temperature 185°C, speed 75 rpm), and amphiphilic conductive molecules and nano-supramolecular structures were added in sequence and stirred for 10 minutes. 3 parts of interface enhancer (maleic anhydride grafted compound) were added and mixed for another 12 minutes to improve the interfacial compatibility.

[0057] 4 parts of weathering stabilizer (1:1 ratio of light stabilizer to antioxidant) were added to ensure long-term stability. Mixing was performed in a twin-screw extruder (screw speed 95 rpm) for 10 minutes, followed by orientation with an electric field of 2.5 kV / m for 7 seconds, and injection molding (injection pressure 110 MPa, mold temperature 75°C), with a cooling time of 35 seconds.

[0058] Example 4 (reducing processing difficulty) 83 parts of polylactic acid (molecular weight 140,000 g / mol, L-lactic acid unit content 96%) were taken and vacuum dried at 55° C. for 7 hours.

[0059] 6 parts of amphiphilic conductive molecules (bithiophene tetrafluorobenzene) were dissolved in an acetonitrile-water mixed solvent (mass ratio 1:2), ultrasonically dispersed at a power of 350 W for 35 minutes, and dried for 10 hours.

[0060] Five portions of the nano-supramolecular structure (polypyrrole-fullerene complex) were dissolved in a toluene-water mixed solvent (mass ratio 1:1.5), ultrasonically dispersed at 500 W for 25 minutes, and electrostatically induced deposition was performed (voltage 2.5 kV, deposition for 9 minutes).

[0061] Put polylactic acid into a melt mixer (temperature 175°C, speed 70 rpm), gradually add amphiphilic conductive molecules and nano-supramolecular structures, stir for 12 minutes, and then add 3 parts of interface enhancer (amide derivative) to ensure uniform dispersion.

[0062] The mixture was kneaded for 10 minutes using a twin-screw extruder (screw speed 90 rpm), oriented by applying an electric field of 3 kV / m for 8 seconds, and injection molded (injection pressure 95 MPa, mold temperature 68° C.) with a cooling time of 28 seconds.

[0063] Comparative Example 1 (Comparative Example 1 - Adjustment of Amphiphilic Conductive Molecules Concentration) Comparative Example: In Comparative Example 1, the amount of amphiphilic conductive molecules was reduced to 5 parts, while other ingredients remained unchanged. This solution builds on the prior art approach of reducing the amount of conductive material used, but this fine-tuning can result in a sparser conductive channel network, which in turn affects the material's conductivity and antistatic properties. The main difference lies in the reduced content of the conductive molecules.

[0064] Comparative experimental steps: 82 parts of high molecular weight polylactic acid (molecular weight 150000 g / mol, L-lactic acid unit content 96%) were taken and dried in a vacuum drying oven at 50° C. for 6 hours for later use.

[0065] Five portions of amphiphilic conductive molecule (PEDOT) were dissolved in an acetonitrile-water mixed solvent (mass ratio 1:2), and ultrasonically treated in an ultrasonic cleaner at a power of 400 W for 40 minutes.

[0066] Dry it to room temperature and set aside.

[0067] Five parts of the nano-supramolecular structure (polypyrrole-fullerene complex) were dissolved in a toluene-water mixed solvent (mass ratio 1:1.5), poured into a reactor, and dispersed in a 500 W ultrasonic dispersion device for 25 min, followed by electrostatic induced deposition (electric field intensity 2 kV, deposition for 12 min).

[0068] The remaining steps of the embodiment of the present invention were followed for mixing, blending, and molding, and a comparative test was performed.

[0069] Comparative Example 2 (Comparative Example 2-Adjustment of the Ratio of Conductive Molecules to Nano-supramolecular Structures) Comparative Example: In Comparative Example 2, the amount of the nano-supramolecular structure was reduced to 2 parts, while the amount of the amphiphilic conductive molecule was maintained at 6 parts. This adjustment may result in a decrease in the connectivity and stability of the conductive channel, thereby affecting the sustainability of the antistatic performance.

[0070] Comparative experimental steps: 85 parts of high molecular weight polylactic acid (molecular weight 180000 g / mol, L-lactic acid unit content 97%) were dried in a vacuum drying oven at 60° C. for 8 hours and set aside.

[0071] Six parts of amphiphilic conductive molecules (bithiophene tetrafluorobenzene) were dissolved in an acetonitrile-water mixed solvent (mass ratio 1:1.5), dispersed under ultrasonic power of 350 W for 30 minutes, and dried at a constant temperature of 60°C for 10 hours to form a nanostructure.

[0072] Two portions of the nano-supramolecular structure (polypyrrole-fullerene complex) were dissolved in a toluene-water mixed solvent (mass ratio 1:2), ultrasonically dispersed at 500 W for 20 minutes, and electrostatically induced deposition was performed (voltage 2 kV, deposition for 12 minutes).

[0073] The remaining steps of Example 2 were followed for mixing, blending, and molding, and a comparative test was performed.

[0074] Comparative Example 3 (Comparative Example 3 - Adjustment of the Ratio of Light Stabilizer to Antioxidant) Comparative Example: In Comparative Example 3, the amount of light stabilizer used was reduced to 2 parts, and the amount of antioxidant used was increased to 6 parts. This adjustment in ratio may result in a decrease in the UV resistance of the material, thereby affecting its long-term stability in outdoor environments, especially against the aging effects caused by UV radiation.

[0075] Comparative experimental steps: 80 parts of polylactic acid (molecular weight 120000 g / mol, L-lactic acid unit content 95%) were taken and vacuum dried at 50° C. for 5 hours and set aside.

[0076] 7 parts of amphiphilic conductive molecules (PEDOT) were dissolved in an acetonitrile-water mixed solvent (mass ratio 1:3), ultrasonically dispersed at 400W for 45 minutes, and the solvent evaporated to induce self-assembly. The mixture was dried at 60°C for 10 hours to form a nano-interface structure.

[0077] Six portions of the nano-supramolecular structure (polypyrrole-fullerene complex) were dissolved in a toluene-water mixed solvent (mass ratio 1:1), ultrasonically dispersed at 600 W for 30 minutes, and electrostatically induced deposition at 3 kV for 8 minutes.

[0078] The remaining steps of Example 3 were followed for mixing, blending, and molding, and a comparative test was performed.

[0079] Comparative Example 4 (Comparative Example 4-Electric Field Orientation Intensity Adjustment) Comparative Example: In Comparative Example 4, the electric field strength was adjusted to 1.5 kV / m, and the electric field orientation time remained unchanged. This adjustment would reduce the degree of orderly arrangement of the conductive phase, and may result in less than expected connectivity of the conductive channels, thereby affecting the overall conductivity.

[0080] Comparative experimental steps: 83 parts of polylactic acid (molecular weight 140,000 g / mol, L-lactic acid unit content 96%) were taken and vacuum dried at 55° C. for 7 hours.

[0081] 6 parts of amphiphilic conductive molecules (bithiophene tetrafluorobenzene) were dissolved in an acetonitrile-water mixed solvent (mass ratio 1:2), ultrasonically dispersed at a power of 350 W for 35 minutes, and dried for 10 hours.

[0082] Five portions of the nano-supramolecular structure (polypyrrole-fullerene complex) were dissolved in a toluene-water mixed solvent (mass ratio 1:1.5), ultrasonically dispersed at 500 W for 25 minutes, and electrostatically induced deposition was performed (voltage 2.5 kV, deposition for 9 minutes).

[0083] The remaining steps of Example 4 were followed for mixing, blending, and molding, and a comparative test was performed.

[0084] Experiment 1: Conductivity Test Experiment Instructions Purpose of the experiment: The difference in antistatic performance between the examples of the present invention and the comparative examples was verified, and the effect of different concentrations of amphiphilic conductive molecules on the antistatic effect was demonstrated through surface resistance testing.

[0085] Experimental steps: Materials preparation: The antistatic polylactic acid samples in Example 1 of the present invention and Comparative Example 1 were prepared.

[0086] In a vacuum drying oven, polylactic acid (80 parts) was mixed with an amphiphilic conductive molecule (PEDOT) and a nano-supramolecular structure (polypyrrole-fullerene complex) in respective proportions, ensuring that the humidity of each sample was below 0.5%.

[0087] After the sample preparation is completed, it is processed into 10cm×10cm thin sheets according to the standard injection molding method.

[0088] Conductivity measurement: The surface resistance of each sample was measured using a four-probe method.

[0089] Four-probe measurement settings: probe spacing 1 cm, applied current 1 mA, and measurement voltage 0.1 V.

[0090] Each sample was tested 3 times and the average value was recorded.

[0091] The surface resistance value is recorded and converted into the conductivity value of the material.

[0092] Test environment: The laboratory temperature was kept at 23°C and the relative humidity was controlled at 40%.

[0093] Clean the surface of each sample before measurement to prevent dust or oil from affecting the test results.

[0094] Table Name: Surface Resistance and Conductivity Test Data Comparison Table Experimental summary: The conductivity test results show that increasing the content of amphiphilic conductive molecules (PEDOT) can significantly improve the conductivity of the material. By comparison with comparative example 1, the surface resistance of Example 1 of the present invention at 8% PEDOT ratio is about 1.1e 6 Ω, compared with 5.4e of Comparative Example 1 (5% PEDOT) 7 Ω, significantly lower surface resistance, and superior antistatic performance. This result clearly demonstrates the effect of PEDOT concentration on improving conductivity. Mechanistic analysis indicates that higher concentrations of PEDOT molecules form a denser and more stable conductive network within the polylactic acid matrix, improving conductivity and reducing the material's surface resistance. This network effect is achieved in the present invention by precisely controlling the PEDOT concentration and the material blending process, achieving efficient and uniform conductive distribution and thus optimizing antistatic performance.

[0095] This experiment further demonstrates the important role of amphiphilic conductive molecules in polylactic acid. While relatively low concentrations of PEDOT provide some conductivity, they fail to form a stable conductive pathway, resulting in conductivity far below that of the design proposed in the present invention. This also reflects the influence of the dispersibility and interfacial compatibility of amphiphilic conductive molecules on antistatic properties. Especially at low filler concentrations, uneven dispersion can lead to interrupted conductive pathways, thus compromising the overall performance.

[0096] Experimental data demonstrates that this invention achieves a balance between antistatic and mechanical properties by rationally adjusting the concentration of conductive molecules, unlike conventional solutions that sacrifice mechanical strength for conductivity. This approach not only addresses the high surface resistance of conventional antistatic plastics but also avoids the degradation of mechanical properties caused by highly conductive fillers, providing technical support for long-term applications in electronics, automotive interiors, and other fields.

[0097] Experiment 2: Mechanical Properties Test Experiment Description Purpose of the experiment: The effects of different ratios of amphiphilic conductive molecules to nano-supramolecular structures on the mechanical properties of the material were verified through tensile and flexural strength tests, further confirming that the present invention improves the antistatic properties without sacrificing the mechanical properties.

[0098] Experimental steps: Materials preparation: According to the proportions of Example 2 and Comparative Example 2, mixtures of polylactic acid (80 parts), amphiphilic conductive molecules (bithiophene tetrafluorobenzene) and nano-supramolecular structures (polypyrrole-fullerene complex) were prepared respectively.

[0099] The mixture was processed into standard tensile and flexural test specimens following standard injection molding techniques.

[0100] All samples were dried at 50°C for 8 h to ensure that the moisture content was below 0.5%.

[0101] Mechanical properties test: The tensile strength test was carried out using a universal material testing machine according to ASTM D638, with the test speed set at 10 mm / min.

[0102] The bending strength test was carried out according to ASTM D790, the bending rate was set at 5 mm / min, and the test sample was a specimen of 80 mm × 10 mm.

[0103] Each sample was tested three times, and parameters such as tensile strength, flexural strength, and elongation at break were recorded.

[0104] Test environment: Temperature 23℃, relative humidity 40%.

[0105] Clean the surface of each specimen before testing to prevent oil and dust from interfering with the test results.

[0106] Table name: Mechanical properties test data comparison table Experimental summary: It is clear from the data of this mechanical properties test experiment that, under the same molding conditions, by optimizing the ratio of amphiphilic conductive molecules to nano-supramolecular structures in Example 2, the tensile strength and flexural strength are significantly improved. Compared with the ratio of the lower concentration of nano-supramolecular structures in Comparative Example 2, the material of Example 2 exhibits higher mechanical strength and ductility. In particular, in Example 2, the tensile strength is stable at around 56 MPa, while in Comparative Example 2, the tensile strength drops to 51 MPa, and the flexural strength also shows a lower value. This shows that a higher concentration of nanocomposites can form a more stable conductive network in the material and improve mechanical properties.

[0107] Mechanistically, the dispersibility and interfacial compatibility of the nano-supramolecular structure (polypyrrole-fullerene complex) in polylactic acid are crucial. Example 2 optimizes the material's microstructure by rationally controlling the ratio of the nano-composite to the conductive molecules, promoting a uniform distribution of the conductive filler within the matrix and thus avoiding the loss of mechanical properties caused by uneven filler dispersion. In contrast, the lower nano-composite content in Comparative Example 2, while providing some conductivity, fails to effectively improve the material's mechanical strength and instead reduces its ductility and flexural properties.

[0108] Furthermore, the experiments also demonstrated that the optimized material not only exhibits excellent antistatic properties but also maintains or enhances its mechanical properties, demonstrating the invention's potential for diverse applications. This is crucial for applications such as automotive and electronic packaging, where both excellent electrical conductivity and structural integrity are crucial.

[0109] Experiment 3: Weathering and Aging Test Experiment Description Purpose of the experiment: Through UV accelerated aging tests, the weathering resistance of antistatic polylactic acid samples with different ratios under long-term exposure to ultraviolet light and oxidative environments was verified, and the effect of weathering stabilizers on the long-term stability of the materials was explored.

[0110] Experimental steps: Materials preparation: Polylactic acid samples were prepared according to the ratios of Example 3 and Comparative Example 3, wherein the ratios of the light stabilizer to the antioxidant were different.

[0111] Polylactic acid (80 parts) was mixed with an amphiphilic conductive molecule (PEDOT) and a nano-supramolecular structure (polypyrrole-fullerene complex) in a certain proportion and dried at 50° C. for 8 hours, ensuring that the humidity was below 0.5%.

[0112] The samples were produced using a standard injection molding process, and the size of the injection-molded specimens was 10 cm × 10 cm.

[0113] Aging test: The samples were placed in a UV accelerated aging test chamber (Q-Sun Xenon Test Chamber) and subjected to a 200-hour UV aging test.

[0114] UV accelerated aging parameters: UV-B lamp, wavelength 320-400nm, exposure time is a cycle of 4 hours on and 4 hours off.

[0115] The changes in surface resistance, tensile strength and flexural strength of the specimens were measured before and after aging.

[0116] In Comparative Example 3, the light stabilizer is 2 parts and the antioxidant is 6 parts, and the effects of different weathering stabilizer ratios on the weather resistance of the material are compared.

[0117] Test environment: Temperature 23℃, relative humidity 40%.

[0118] Clean the sample surface before measurement to avoid contamination that may interfere with the results.

[0119] Table name: Weather resistance and aging test data comparison table Experimental summary: The results of the UV accelerated aging test show that the weathering stabilizer in Example 3 (the ratio of light stabilizer to antioxidant is 4:4) significantly improves the material's UV resistance and effectively inhibits the conductivity decay caused by UV aging. Compared with the sample in Comparative Example 3 with a light stabilizer to antioxidant ratio of 2:6, the surface resistance of the sample in Example 3 is lower (1.2e 6 Ωvs4.7e 6 Ω), and the tensile strength and flexural strength after 200 hours of aging remained at a high level, demonstrating strong weather resistance. In particular, after UV aging, the mechanical properties of the sample in Example 3 were hardly significantly affected. This is mainly attributed to the reasonable ratio of the light stabilizer and antioxidant, which enables the polylactic acid matrix to effectively resist the damage of ultraviolet rays.

[0120] Mechanistic analysis reveals that light stabilizers and antioxidants not only slow UV degradation but also inhibit the degradation of polylactic acid in oxidative environments. Light stabilizers absorb UV light, reducing damage to polylactic acid molecules from high-energy photons. Antioxidants, on the other hand, trap free radicals, inhibiting oxidation and reducing material embrittlement and strength loss. In the examples of the present invention, these two components, when combined in a suitable ratio, work synergistically to effectively enhance the material's weather resistance.

[0121] Comparison with Comparative Example 3 shows that an inappropriate ratio of light stabilizer to antioxidant (e.g., 2:6) can lead to accelerated aging of the material, rapid conductivity degradation, and significant decreases in mechanical properties. This suggests that a reasonable ratio of weathering stabilizers is crucial for outdoor applications of antistatic polylactic acid plastics, significantly improving their long-term stability and reliability.

[0122] Experiment 4: Processability and Formability Test Experiment Description Purpose of the experiment: By comparing the effects of different electric field orientation intensities on the processability and forming stability of the material, it is verified how the electric field orientation technology of the present invention can improve the formability of the material and enhance the processing efficiency.

[0123] Experimental steps: Materials preparation: Polylactic acid samples were prepared according to the ratios of Example 4 and Comparative Example 4. The samples included antistatic polylactic acid oriented under different electric field intensities, including comparative groups with higher electric field intensity (3 kV / m) and lower electric field intensity (1.5 kV / m).

[0124] Polylactic acid (80 parts) was mixed with an amphiphilic conductive molecule (bithiophene tetrafluorobenzene) and a nano-supramolecular structure (polypyrrole-fullerene complex) in a proportion to ensure that the humidity after drying was less than 0.5%.

[0125] The samples were processed into 10 cm × 10 cm sheets by standard injection molding process.

[0126] Processing performance test: The melt index (MFI) of the sample was measured by The measuring instrument was set at a temperature of 230°C and a test load of 2.16 kg to calculate the melt index (unit: g / 10 min).

[0127] Injection molding: An injection molding machine (Engel100T) was used with the temperature set at 230°C, injection pressure 100 MPa, mold temperature 70°C, and cooling time 25 seconds.

[0128] Measure the defect rate (such as bubbles, flow marks, etc.) during the injection molding process and record the number of molding defects for each material.

[0129] The effects of high electric field orientation (3kV / m) and low electric field orientation (1.5kV / m) on molding cycle, melt index and defect rate were compared.

[0130] Test environment: The test environment temperature is 23°C and the relative humidity is 40%.

[0131] Before measurement, ensure that the surface of each sample is free of contamination to ensure the accuracy of the test results.

[0132] Table Name: Processability and Formability Test Data Comparison Table Experimental summary: From the experimental results, the material of Example 4 of the present invention under a higher electric field strength (3kV / m) shows significantly better processing performance than the sample with a low electric field strength (1.5kV / m). The higher melt index (6.3g / 10min vs. 4.2g / 10min) means that the material has better fluidity during the molding process, can fill the mold more smoothly, and reduces molding defects caused by poor fluidity during the injection molding process. In addition, the samples treated with a high electric field also show better controllability in terms of molding defect rate and molding cycle. The molding defect rate is 5%, while it is 12% in Comparative Example 4, and the molding cycle is shorter, which directly improves production efficiency.

[0133] This improved processing performance can be attributed to the optimization effect of electric field orientation technology. Higher electric field strengths promote the alignment of conductive molecules and nano-supramolecular structures within the polylactic acid matrix, forming a more uniform and stable conductive network. This not only enhances antistatic properties but also improves the material's fluidity. Conversely, at lower electric field strengths, the conductive network within the material is less uniformly arranged, resulting in poor fluidity, unstable molding, and increased molding defects.

[0134] Materials treated with high electric fields not only improve processing performance but also demonstrate greater operability in actual production. This opens up a wider range of practical applications, particularly in manufacturing processes that demand high production efficiency and high-quality molding. Compared to traditional methods, electric field orientation technology significantly improves the material's processability, making it more adaptable to changing production conditions.

[0135] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. An antistatic polylactic acid plastic, characterized in that: The antistatic polylactic acid plastic comprises the following components in parts by mass: Polylactic acid: 80-85 parts; Amphiphilic conductive molecules: 5-10 parts; Nano-supramolecular structure: 3-7 parts; Interface enhancer: 1-3 parts; Weathering stabilizer: 0.5-2 parts.

2. The antistatic polylactic acid plastic according to claim 1, characterized in that: The polylactic acid is a high molecular weight polylactic acid with a molecular weight range of 100,000 g / mol to 200,000 g / mol, and an L-lactic acid unit content of not less than 95%; the amphiphilic conductive molecule is composed of a conjugated polymer with a thiophene structure or a benzothiophene structure, and its chemical structure includes poly(triethylenedioxythiophene) or poly(tetrafluoroethylene)-bthiophene; the nano-supramolecular structure is composed of a polypyrrole and fullerene complex, and an ultrasonic electrostatic induced deposition method is used to form a nanoscale conductive channel to improve the material's antistatic properties and charge dissipation capabilities.

3. The antistatic polylactic acid plastic according to claim 1, characterized in that: The interface enhancer is an amide derivative or a maleic anhydride graft, which is used to improve the interface compatibility between the polylactic acid matrix and the antistatic phase; the weathering stabilizer includes a light stabilizer and an antioxidant, the light stabilizer is a benzophenone ultraviolet absorber, and the antioxidant is a hindered phenol antioxidant, which is used to improve the material's resistance to ultraviolet aging and long-term stability.

4. A method for preparing an antistatic polylactic acid plastic, applied to the antistatic polylactic acid plastic according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1, dissolving the amphiphilic conductive molecules in an acetonitrile-water mixed solvent and ultrasonically dispersing them in an ultrasonic cleaner, then inducing self-assembly by solvent evaporation to form a nano-interface structure in a constant temperature drying oven; S2, dissolving the nano-supramolecular structure in a toluene-water mixed solvent, adding the solution to a reaction kettle, performing ultrasonic treatment using an ultrasonic disperser, and then forming a conductive channel in an electrostatic deposition device by electrostatic induced deposition; S3, drying the polylactic acid in a vacuum drying oven, placing the polylactic acid in a high-temperature melt mixer for melt blending, first adding the polylactic acid matrix, and then gradually adding the amphiphilic conductive molecules and the nano-supramolecular structure; S4. During the melt blending process, an interfacial enhancer is added and mixed using a twin-screw extruder to ensure that the polylactic acid matrix and the antistatic material are fully integrated; S5. applying a high electric field orientation to the blend, and using an electric field orientation device to optimize the conductive network; S6. Using a precision injection molding process, the treated mixture is injected into a mold in an injection molding machine, and cooled through a cooling water tank to obtain an antistatic polylactic acid plastic product.

5. The method for preparing antistatic polylactic acid plastic according to claim 4, characterized in that: In step S1, the amphiphilic conductive molecules are dissolved in an acetonitrile-water mixed solvent with a mass ratio of the solvent of 1:1 to 1:3, and then dispersed in an ultrasonic dispersion device with an ultrasonic power of 200W to 500W and a dispersion time of 20 to 60 minutes; then self-assembly is induced by solvent volatilization, and the operation is carried out in a constant temperature drying device with an volatilization time of 8 to 16 hours.

6. The method for preparing antistatic polylactic acid plastic according to claim 4, characterized in that: In step S2, the nano-supramolecular structure is dissolved in a toluene-water mixed solvent with a mass ratio of the solvent of 1:1 to 1:3, and then ultrasonic dispersion is performed in a reactor using an ultrasonic dispersion device with an ultrasonic power of 300W to 600W and a dispersion time of 15 to 30 minutes; and a conductive channel is formed by an electrostatic induced deposition method, in which an electrostatic device is used to apply an electric field with a voltage range of 1kV to 3kV and a deposition time of 5 to 15 minutes.

7. The method for preparing antistatic polylactic acid plastic according to claim 4, characterized in that: In step S3, the polylactic acid is first dried in a vacuum drying oven for 4 to 8 hours; then the dried polylactic acid is melt-blended with the amphiphilic conductive molecules and the nano-supramolecular structure. During the blending process, the mass fraction of the polylactic acid is 70 to 85 parts, the mass fraction of the amphiphilic conductive molecules is 5 to 10 parts, and the mass fraction of the nano-supramolecular structure is 3 to 8 parts, so as to uniformly disperse the materials.

8. The method for preparing antistatic polylactic acid plastic according to claim 4, characterized in that: In the step S4, an interface enhancer is added, the weight portion of the interface enhancer is 1 to 3 parts, and a twin-screw extruder is used for mixing, the screw speed range is 60 rpm to 120 rpm, and the mixing time is 8 to 15 minutes.

9. The method for preparing antistatic polylactic acid plastic according to claim 4, characterized in that: In the step S5, a high electric field is applied to the blend for orientation, the electric field strength ranges from 1 kV / m to 5 kV / m, and the orientation time is from 5 to 15 seconds. The electric field effect can optimize the formation and stabilization of the conductive network.

10. The method for preparing antistatic polylactic acid plastic according to claim 4, characterized in that: In step S6, an injection molding machine is used to inject the treated mixture into a mold, the injection pressure range is 80 MPa to 120 MPa, the mold temperature range is 50° C. to 90° C., and the cooling time is 20 to 40 seconds, to finally obtain an antistatic polylactic acid plastic product.

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