A biobased degradable cable compound and a preparation method thereof

Abstract

The present application relates to the technical field of surface treatment, in particular to a kind of biobased degradable cable material and preparation method thereof.Biobased degradable cable material includes 55-65 parts of poly-L-lactic acid and poly-3-hydroxybutyric acid-3-hydroxyhexanoate mixed matrix resin, 4-6 parts of dianhydride modified castor oil polyol, 10-15 parts of polyaminoval, 5-8 parts of nano enhanced filler, 6-10 parts of biobased plasticizer, 0.5-1.0 parts of antioxidant, 8-12 parts of environmentally friendly flame retardant.Dynamic ester bond crosslinking agent dianhydride modified castor oil polyol reaction forms dynamic ester bond crosslinking network, ester bond breakage occurs at high temperature beyond normal working range to release stress, temperature returns to normal and can recombine again;Semi-interpenetrating network enhanced phase polyaminoval forms interpenetrating structure with matrix resin in molecular chain interlacing mode, constructs stable heat-resistant skeleton, effectively inhibits high-temperature deformation, and its biobased structure ensures the overall degradability of the material, realizes the balance of heat resistance and degradability.

Description

Technical Field

[0001] This application belongs to the field of environmentally friendly cable material technology, and more specifically, it relates to a bio-based biodegradable cable material and its preparation method. Background Technology

[0002] Bio-based cable materials are polymer composites made primarily from renewable materials such as plant starch, oils, and microbial fermentation products. They are used for cable insulation and sheathing. The raw materials for bio-based biodegradable cable materials are green and renewable, capable of being degraded into harmless substances by microorganisms in the environment. Furthermore, their insulation, flame retardant, and mechanical properties can be optimized through component control. Currently, they are used in fields such as temporary agricultural wiring, low-voltage wiring harnesses for new energy vehicles, and emergency rescue cables.

[0003] Existing bio-based cable materials with polylactic acid, polyhydroxyalkanoates, etc. as the matrix face problems in practical applications, such as insufficient heat resistance or the use of traditional chemical additives to improve heat resistance, which can damage the biodegradability and mechanical properties of bio-based cable materials, seriously restricting their industrial application.

[0004] To address this issue, existing technologies introduce dynamic imine bond crosslinking and semi-interpenetrating network structures. The reversible breaking and recombination of dynamic imine bonds enables dynamic control of the crosslinking network in bio-based cable materials, while the semi-interpenetrating network structure introduces a second network phase to reinforce the heat-resistant framework of the bio-based matrix. However, dynamic imine bonds are prone to hydrolysis with trace amounts of moisture, leading to network breakage and insufficient heat resistance, making it unsuitable for long-term high-temperature operating environments. Furthermore, the semi-interpenetrating network structure design lacks interfacial synergy optimization with the bio-based matrix, resulting in insufficient interfacial bonding during heat transfer and failing to fully utilize the heat-resistant support role of the reinforcing phase. This directly limits the increase in the heat distortion temperature of the cable material, reaching a maximum of only 95℃, making it difficult to achieve an effective balance between heat resistance and practicality. Summary of the Invention

[0005] The purpose of this application is to provide a bio-based biodegradable cable material and its preparation method, so as to solve the technical problem of insufficient heat resistance of bio-based biodegradable cable materials in the prior art.

[0006] To achieve the above objectives, the technical solution adopted in this application is: to provide a non-bio-based biodegradable cable material comprising the following components by weight:

[0007] Bio-based matrix resin: 55-65 parts;

[0008] Dynamic ester bond crosslinking agent: 4-6 parts;

[0009] Semi-interpenetrating network enhancement phase: 10-15 copies;

[0010] Nano-reinforced filler: 5-8 parts;

[0011] Bio-based plasticizer: 6-10 parts;

[0012] Antioxidant: 0.5-1.0 parts;

[0013] Environmentally friendly flame retardant: 8-12 parts;

[0014] The bio-based matrix resin is a blend of poly-L-lactic acid and poly-3-hydroxybutyrate-3-hydroxyhexanoate;

[0015] The dynamic ester bond crosslinking agent is a dianhydride-modified castor oil polyol;

[0016] The semi-interpenetrating network reinforcement phase is polypentyl adipate diamine.

[0017] Optionally, the mass ratio of the poly-L-lactic acid to poly-3-hydroxybutyrate-3-hydroxyhexanoate is 3:1 to 2:1.

[0018] Optionally, the nano-reinforced filler is nano-montmorillonite modified with silane coupling agent KH550;

[0019] The bio-based plasticizer is a compound of epoxidized soybean oil and tributyl citrate, with a mass ratio of epoxidized soybean oil to tributyl citrate of 1:1.

[0020] The antioxidant is a compound of hindered phenolic antioxidant 1010 and phosphite antioxidant 168, with a mass ratio of hindered phenolic antioxidant 1010 to phosphite antioxidant 168 of 1:1.

[0021] The environmentally friendly flame retardant is a compound of melamine cyanurate and ammonium polyphosphate, with a mass ratio of melamine cyanurate to ammonium polyphosphate of 2:1.

[0022] Optionally, the dianhydride in the dianhydride-modified castor oil polyol is pyromellitic dianhydride.

[0023] This application further proposes a method for preparing a bio-based biodegradable cable material, the method comprising the following steps:

[0024] Raw material pretreatment: The bio-based matrix resin and polypentanediamine adipate are vacuum dried to remove moisture;

[0025] Premixing stage: Bio-based matrix resin, bio-based plasticizer, and antioxidant are added to a high-speed mixer to obtain a premix;

[0026] Melt blending and crosslinking: The premix, dianhydride-modified castor oil polyol, polypentanediamine adipate, and nano-reinforcing filler are added to a twin-screw extruder. When the temperature is raised to 170°C, an environmentally friendly flame retardant is added and the mixture is blended to complete the crosslinked extruded strip.

[0027] Pelletizing and annealing: After the extruded strips are cooled and pelletized, they are annealed in a forced-air drying oven;

[0028] Finished product screening: After annealing, the granules are screened to remove impurities, resulting in bio-based biodegradable cable material.

[0029] Optionally, the bio-based matrix resin is vacuum dried at 80°C for 8 hours;

[0030] The semi-interpenetrating network reinforcement phase was vacuum dried at 100°C for 12 hours.

[0031] Optionally, the high-speed mixer mixes the bio-based matrix resin, bio-based plasticizer, and antioxidant at 80°C for 10 minutes at a speed of 300 r / min.

[0032] Optionally, the twin-screw extruder is divided into four independent temperature control zones along the material conveying direction, wherein the temperature of zone one is set to 160℃, the temperature of zone two is set to 170℃, the temperature of zone three is set to 180℃, the temperature of zone four is set to 175℃, and the screw speed is controlled at 300-350 r / min.

[0033] The environmentally friendly flame retardant is added after the material enters the second zone and mixed for 5 minutes.

[0034] Optionally, the annealing process is carried out in a forced-air oven at 100°C for 2 hours.

[0035] This application provides a bio-based biodegradable cable material and its preparation method, the advantages of which are as follows: Compared with the prior art, the bio-based biodegradable cable material of this application constructs a material system with both heat resistance and biodegradability through the synergistic effect of the dynamic ester bond crosslinking agent dianhydride-modified castor oil polyol and the semi-interpenetrating network reinforcing phase polypentadiamine adipate. The dynamic ester bond network generated by the reaction of the dynamic ester bond crosslinking agent maintains a stable bond state at normal operating temperatures, providing continuous structural support for the material. Reversible fracture occurs only at high temperatures exceeding the normal operating range to release stress, ensuring the heat resistance performance of the bio-based biodegradable cable material in the working environment, and achieving stress release and self-repair under emergency conditions through bond energy characteristics. Thus, while maintaining the biodegradability of the bio-based biodegradable cable material, the heat resistance is significantly improved. The semi-interpenetrating network reinforcing phase forms an interpenetrating structure with the matrix resin in a molecular chain interpenetrating manner, constructing a stable heat-resistant skeleton, effectively inhibiting high-temperature deformation, and its bio-based structure ensures the overall biodegradability of the material. The two work together to solve the problems of insufficient heat resistance and poor functional stability of traditional bio-based materials, achieving a balance between heat resistance and biodegradability. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 A flowchart illustrating a method for preparing a bio-based biodegradable cable material, as provided in this application embodiment. Detailed Implementation

[0038] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0039] Bio-based cable materials are polymer composites made primarily from renewable materials such as plant starch, oils, and microbial fermentation products, used for cable insulation and sheathing. Existing bio-based cable materials based on polylactic acid (PLA) and polyhydroxyalkanoates (PHA) face challenges such as insufficient heat resistance or the use of traditional chemical additives to improve heat resistance, which can compromise biodegradability and mechanical properties. Current technologies introduce dynamic imine bond crosslinking and semi-interpenetrating network structures, but dynamic imine bonds are prone to hydrolysis above 120°C, resulting in insufficient heat stability. Furthermore, the semi-interpenetrating network structure design lacks interfacial synergistic optimization with the bio-based matrix, limiting the improvement in the cable material's heat distortion temperature.

[0040] To address the aforementioned problems, the bio-based biodegradable cable material provided in this application embodiment comprises the following components by weight:

[0041] Bio-based matrix resin: 55-65 parts;

[0042] Dynamic ester bond crosslinking agent: 4-6 parts;

[0043] Semi-interpenetrating network enhancement phase: 10-15 copies;

[0044] Nano-reinforced filler: 5-8 parts;

[0045] Bio-based plasticizer: 6-10 parts;

[0046] Antioxidant: 0.5-1.0 parts;

[0047] Environmentally friendly flame retardant: 8-12 parts;

[0048] The bio-based matrix resin is a blend of poly-L-lactic acid and poly-3-hydroxybutyrate-3-hydroxyhexanoate;

[0049] The dynamic ester bond crosslinking agent is a dianhydride-modified castor oil polyol;

[0050] The semi-interpenetrating network reinforcement phase is polypentyl adipate diamine.

[0051] The bio-based biodegradable cable materials provided in this application are all made from natural renewable raw materials, which can be degraded by microorganisms into harmless substances, and have good environmental protection and recyclability.

[0052] In this material, the bio-based matrix resin constitutes the main framework of the bio-based biodegradable cable material at a high proportion of 55-65 parts. As a blend of poly(L-lactic acid) [PLLA] and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [PHBH], it serves as the fundamental carrier supporting the mechanical properties and functions of the bio-based biodegradable cable material. The two bio-based polymers form a continuous and stable phase structure through the intertwining and close stacking of their molecular chains: PLLA molecular chains have high regularity, forming a rigid supporting framework with strong intermolecular forces, providing excellent tensile and flexural strength for the bio-based biodegradable cable material; PHBH molecular chains have flexible side chains, improving the system's toughness through chain segment movement and mitigating the brittleness of PLLA. This synergistic effect enables bio-based biodegradable cable materials to resist tensile and bending stresses during cable assembly, as well as external impacts and compressions during use. This effectively maintains the structural integrity of the cable insulation and sheath layers, preventing insulation performance degradation due to mechanical failure. PLLA and PHBH are both typical bio-based biodegradable polymers: PLLA originates from plant starch fermentation, with its molecular chain rich in ester bonds and containing hydroxyl and carboxyl groups at both ends; PHBH is synthesized by microbial fermentation, also using ester bonds as the main connecting unit, with hydroxyl and carboxyl groups at both ends of the molecule. In the natural environment, these ester bonds can be specifically recognized and catalyzed by esterases secreted by microorganisms, causing the molecular chain to gradually break down into smaller monomers, which are ultimately converted into carbon dioxide and water through microbial metabolism.

[0053] The dynamic ester bond crosslinking agent comprises 4-6 parts, using dianhydride-modified castor oil polyol. The castor oil polyol molecule contains multiple hydroxyl groups (-OH), which, along with the terminal hydroxyl groups (-OH) of the matrix resins PLLA and PHBH, can act as nucleophiles to attack the acyl carbon of the dianhydride, undergoing a ring-opening reaction to generate a linear intermediate with two carboxyl groups (-COOH). This intermediate then undergoes esterification with hydroxyl groups in the system (including the remaining hydroxyl groups of the castor oil polyol and the terminal hydroxyl groups of the matrix resin) to form a structure containing dynamic ester bonds (-COO-). Simultaneously, because the castor oil polyol has multiple hydroxyl sites, it can undergo dehydration condensation with the carboxyl groups in the PLLA and PHBH molecular chains to form dynamic ester bond connection points, and can also undergo esterification reactions with multiple matrix resin molecular chains, ultimately constructing a reversible three-dimensional crosslinked network. This network effectively disperses and bears external thermal stress, delaying the deformation and mechanical property degradation of the material caused by heat. This network structure enhances intermolecular forces, improves heat resistance and mechanical properties, does not disrupt the linear backbone structure of the matrix resin, and retains biodegradability.

[0054] Furthermore, the bond energy of dynamic ester bonds is relatively low. Under high temperatures (such as 100-150℃) or mechanical stress, the increased molecular thermal motion causes heterolytic cleavage of the ester bonds, breaking them into carboxyl anions (-COO). - The cross-linked network partially disintegrates to release stress, forming carboxyl groups and hydroxyl groups (-OH). When the external stimulus disappears, the system's energy decreases, and the resulting carboxyl and hydroxyl groups collide again under Brownian motion of the molecular chains. They then approach each other through hydrogen bonding or intermolecular forces, and can re-dehydrate and condense to form ester bonds without a catalyst, achieving self-repair of the cross-linked network and avoiding the degradation caused by traditional irreversible cross-linking. When the bio-based biodegradable cable material is discarded, microorganisms in the natural environment secrete esterases, which specifically catalyze the hydrolysis of ester bonds, causing the cross-linked network to gradually disintegrate into small molecular fragments, which are ultimately transformed into harmless substances through microbial metabolism.

[0055] The semi-interpenetrating network reinforcement phase is polypentanediamine adipate. Polypentanediamine adipate (PA56) is a typical bio-based polyamide. Its monomer, pentanediamine, can be prepared by fermentation from renewable resources such as corn and starch, while adipic acid can be synthesized through bio-based pathways such as conversion from vegetable oils. The semi-interpenetrating network refers to the interpenetration and entanglement of PA56 linear molecular chains with the molecular chains of the bio-based matrix resin, without forming chemical cross-links. The PA56 molecular chains contain amide bonds, and strong intermolecular interactions are formed through hydrogen bonding, resulting in high tensile strength and rigidity. After its linear chains become entangled with the matrix resin chains, it can share external stress, compensating for the mechanical shortcomings of bio-based matrix resins (such as PLLA, which is brittle, and PHBH, which has low strength). PA56 has a higher glass transition temperature and heat distortion temperature than most bio-based polyesters, and its network structure can inhibit the free movement of the matrix resin molecular chains at high temperatures, improving the high-temperature resistance of bio-based biodegradable cable materials. In the natural environment, the preferential degradation of the matrix resin will destroy the network structure of PA56, exposing it to microorganisms or environmental factors, and eventually it will be absorbed by the environment through slow degradation or fragmentation.

[0056] Nano-reinforced fillers can inhibit crack propagation through stress dispersion effects, significantly improving the tensile strength, flexural strength, and hardness of bio-based biodegradable cable materials. Commonly used nano-reinforced fillers include nano-silica, nano-calcium carbonate, and nano-zinc oxide. The high thermal stability of nano-reinforced fillers can inhibit the thermal motion of the matrix resin molecular chains at high temperatures, improving the heat distortion temperature and heat resistance of bio-based biodegradable cable materials. Simultaneously, the uniform dispersion of nanoparticles in the matrix can reduce the shrinkage and expansion of bio-based biodegradable cable materials caused by temperature changes or external forces, improving the dimensional stability of bio-based biodegradable cable materials. Some also possess auxiliary functions such as antibacterial properties.

[0057] Bio-based resins, with their rigid molecular chains and high melt viscosity, are prone to melt fracture and molding difficulties during processing. Common bio-based plasticizers include tributyl acetylacetonate, triethyl citrate, and dioctyl adipate. Bio-based plasticizers can intercalate between resin molecular chains, weakening intermolecular hydrogen bonds or van der Waals forces, reducing melt viscosity, and making the raw material flow more easily during extrusion, injection molding, and other processing, thus reducing equipment energy consumption and processing defects. They also lower the glass transition temperature of bio-based biodegradable cable materials, allowing them to maintain good flexibility and ductility at room temperature and even low temperatures.

[0058] Antioxidants can block oxidation reaction chains and protect the integrity of molecular chain structures. Bio-based resin molecular chains contain easily oxidized groups such as ester bonds and amide bonds. Under high processing temperatures or long-term use, these groups are easily attacked by oxygen, leading to oxidative breakage and discoloration of bio-based biodegradable cable materials, as well as a decline in mechanical properties. Antioxidants can delay aging and extend service life through mechanisms such as capturing free radicals and decomposing peroxides, without affecting biodegradability. Commonly used antioxidants include BHT (2,6-di-tert-butyl-4-methylphenol, Butylated Hydroxytoluene), antioxidant 1076 (β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and dilauryl thiodipropionate.

[0059] Environmentally friendly flame retardants inhibit combustion and delay flame spread through mechanisms such as heat absorption, formation of a protective layer, and release of inert gases, reducing the emission of toxic fumes. While ensuring flame retardant effects, they also maintain the biodegradability and mechanical properties of bio-based biodegradable cable materials. Common environmentally friendly flame retardants include magnesium hydroxide, aluminum hydroxide, and triphenyl phosphate. Magnesium hydroxide and aluminum hydroxide achieve flame retardancy by absorbing heat upon thermal decomposition and releasing water vapor to dilute flammable gases, while triphenyl phosphate works by forming a char layer to isolate oxygen. All of these meet the requirements of environmental protection and biodegradability.

[0060] This application's bio-based biodegradable cable material uses renewable resources such as starch fermentation products (PLLA) and microbial fermentation products (PHBH) as raw materials. These materials can be metabolized by microorganisms into harmless substances, exhibiting outstanding biodegradability. Utilizing a dynamic ester bond cross-linking network and the PA56 semi-interpenetrating structure, it enhances the heat distortion temperature and inhibits high-temperature deformation. Furthermore, the dynamic ester bonds can self-repair at 100-150℃ or under stress to extend lifespan. It also integrates flame-retardant functions, balancing practicality and heat resistance. This bio-based biodegradable cable material is suitable for applications with high environmental degradation requirements, such as agricultural fields, municipal outdoor applications, disposable electronic devices, and temporary projects. It is also compatible with conventional cable insulation and sheathing processes.

[0061] In another embodiment of this application, the mass ratio of poly-L-lactic acid and poly-3-hydroxybutyrate-3-hydroxyhexanoate is 3:1-2:1. This utilizes the complementary properties of the former (high strength and rigidity) and the latter (good flexibility, impact resistance, and processing fluidity). This retains the core biodegradable properties of the bio-based biodegradable cable material while balancing the strength and toughness of the bio-based matrix resin and improving processing moldability by adjusting the ratio of the two, thus meeting the comprehensive requirements of bio-based biodegradable cable material for structural stability and performance.

[0062] In another embodiment of this application, the nano-reinforced filler is nano-montmorillonite modified with silane coupling agent KH550; the bio-based plasticizer is a compound of epoxidized soybean oil and tributyl citrate, with a mass ratio of epoxidized soybean oil to tributyl citrate of 1:1; the antioxidant is a compound of hindered phenolic antioxidant 1010 and phosphite antioxidant 168, with a mass ratio of hindered phenolic antioxidant 1010 to phosphite antioxidant 168 of 1:1; and the environmentally friendly flame retardant is a compound of melamine cyanurate and ammonium polyphosphate, with a mass ratio of melamine cyanurate to ammonium polyphosphate of 2:1.

[0063] Among them, the silane coupling agent KH550 is γ-aminopropyltriethoxysilane. The silane coupling agent KH550 modifies the nano-montmorillonite molecular structure, containing amino and ethoxy groups. After hydrolysis, the ethoxy groups undergo a condensation reaction with the hydroxyl groups on the surface of the nano-montmorillonite, forming chemical bonds. The amino groups, on the other hand, form hydrogen bonds or van der Waals forces with the polar groups (ester bonds, etc.) of the bio-based matrix resin. This modification treatment solves the problem of poor compatibility between nano-montmorillonite and hydrophobic resins due to its hydrophilic surface, allowing its layered structure to be more uniformly dispersed in the matrix and enhancing interfacial bonding strength. The dispersed nano-montmorillonite layers, on the one hand, inhibit the thermal motion of the matrix resin molecular chains, improving the tensile strength, flexural modulus, and heat distortion temperature of the bio-based biodegradable cable material; on the other hand, through layer entanglement, they hinder crack propagation, enhancing the impact toughness and dimensional stability of the bio-based biodegradable cable material, while also improving its barrier properties (such as water resistance and chemical penetration resistance).

[0064] Among them, epoxidized soybean oil (ESO) contains epoxy groups and long-chain alkyl groups in its molecules, which have good compatibility with bio-based polyester resins. The epoxy groups can neutralize acidic impurities during resin processing and also provide thermal stability. Tributyl citrate (TBC), a citric acid derivative, has high plasticizing efficiency and can effectively reduce the glass transition temperature of the resin, improving flexibility. The mechanism of the 1:1 mass ratio compound of epoxidized soybean oil and tributyl citrate is synergistic complementarity: the long-chain structure of ESO can enhance the entanglement with the resin molecular chains, reduce the free movement of plasticizer molecules, thereby reducing their migration risk, ensuring the long-term stability of the performance of bio-based biodegradable cable materials, and improving long-term flexibility; the short-chain structure of TBC can quickly insert into the resin molecular chains, effectively weakening intermolecular forces, reducing melt viscosity, and improving processing fluidity. The compound formulation avoids the problem of bio-based biodegradable cable material being too hard after being plasticized with ESO alone, and also solves the migration risk that may exist after being plasticized with TBC alone. While ensuring smooth processing, it enables the bio-based biodegradable cable material to maintain good ductility and bending resistance at both room temperature and low temperature. Moreover, since both are bio-based, they do not interfere with the biodegradability of the bio-based biodegradable cable material.

[0065] Among them, hindered phenolic antioxidant 1010 is the main antioxidant, whose chemical composition is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]. The phenolic hydroxyl group in the molecule can capture free radicals (alkyl free radicals, peroxide free radicals) generated during the oxidation process of biodegradable cable materials by providing hydrogen atoms, thus terminating the free radical chain reaction. Phosphite antioxidant 168 is an auxiliary antioxidant, whose chemical composition is tris[2,4-di-tert-butylphenyl]phosphite. It can decompose the peroxides (ROOH) generated during the oxidation process and convert them into stable alcohols or esters, thus preventing the peroxides from further decomposing and generating new free radicals. The combination of the two forms a synergistic mechanism of free radical capture and peroxide decomposition: hindered phenolic antioxidant 1010 blocks the initiation and growth of free radical chains, and phosphite antioxidant 168 eliminates oxidation intermediates. Together, they inhibit the thermo-oxidative aging of bio-based resins during high-temperature processing and use, significantly extending the service life of bio-based biodegradable cable materials. Moreover, the antioxidant efficiency of the combination is much higher than that of a single antioxidant.

[0066] In this process, ammonium polyphosphate (APP) decomposes upon heating to produce acidic substances such as phosphoric acid, catalyzing the dehydration and charring of the bio-based resin molecular chains to form a char layer. Melamine cyanurate (MCA) releases nitrogen-containing gases such as melamine upon heating, diluting the concentration of oxygen and combustibles around the material, and the gas expansion promotes the formation of a porous, expanded structure in the char layer. APP promotes char layer formation, while MCA makes the char layer loose and porous through gas expansion, enhancing its ability to block heat and oxygen. Simultaneously, the nitrogen released by MCA inhibits flame combustion and reduces smoke generation. This compound not only compensates for the shortcomings of APP's strong charring ability but insufficient char layer density, but also solves the problem of MCA's low flame retardant efficiency. The release of halogen-free elements is environmentally friendly.

[0067] In another example of this application, the dianhydride in the dynamically crosslinked ester bond crosslinking agent dianhydride modified castor oil polyol is pyromellitic dianhydride. Pyromellitic dianhydride has the structure of an aromatic ring compound containing two symmetrical anhydride groups. Because the pyromellitic dianhydride molecule contains two independent anhydride groups, each anhydride group can react with the hydroxyl groups on different castor oil polyol molecules, effectively connecting multiple castor oil molecular chains and ultimately forming a three-dimensional network crosslinked structure. The aromatic ring structure of pyromellitic dianhydride is highly rigid. After being anchored in the crosslinked network through ester bonds, it can enhance the interaction forces between molecular chains, suppress random movement of chain segments, prevent excessive deformation of the material under stress or high temperature, and improve heat resistance.

[0068] Please see Figure 1 In one embodiment of this application, a method for preparing a bio-based biodegradable cable material is proposed, the method comprising the following steps:

[0069] Raw material pretreatment: The bio-based matrix resin and polypentanediamine adipate are vacuum dried to remove moisture;

[0070] Premixing stage: Bio-based matrix resin, bio-based plasticizer, and antioxidant are added to a high-speed mixer to obtain a premix;

[0071] Melt blending and crosslinking: The premix, dianhydride-modified castor oil polyol, polypentadiamine adipate, and nano-reinforcing filler are added to a twin-screw extruder. An environmentally friendly flame retardant is added at 170°C for blending to complete the crosslinked extruded strip.

[0072] Pelletizing and annealing: After the extruded strips are cooled and pelletized, they are annealed in a forced-air drying oven;

[0073] Finished product screening: After annealing, the granules are screened to remove impurities, resulting in bio-based biodegradable cable material.

[0074] It should be noted that in the raw material pretreatment, both the bio-based matrix resin and polypentyl adipate diamine are polar polymers containing hydrophilic groups such as ester and amide bonds in their molecular chains, which easily adsorb moisture from the environment. Vacuum drying of the bio-based matrix resin and polypentyl adipate diamine can accelerate moisture evaporation by reducing ambient air pressure, efficiently removing free and bound water from the raw materials, and providing a stable raw material state for subsequent melt blending and crosslinking reactions. In the premixing stage, the bio-based plasticizer, being a small molecule or oligomer, can initially penetrate into the gaps between resin particles through the shear force and frictional heat of high-speed mixing, reducing the problem of local over-plasticization or under-plasticization caused by uneven plasticizer dispersion in the subsequent melting stage, and ensuring the uniformity of material flexibility. Antioxidants need to be evenly distributed in the resin matrix to function effectively. High-speed mixing allows antioxidants to adhere to the surface of resin particles, preventing loss of antioxidant effect due to localized low concentrations during the melting stage. In melt blending and crosslinking, the dynamic ester bond crosslinking agent undergoes an esterification reaction with the matrix resin at the melting temperature. Environmentally friendly flame retardants are small organic molecules; adding them too early may cause decomposition and inactivation due to high temperatures. Adding the environmentally friendly flame retardant after the premix has melted reduces its residence time in the high-temperature zone, ensuring flame retardant efficiency. During annealing, low-temperature heating alleviates residual processing stress, while annealing in a forced-air oven allows the molecular chains to slowly relax, promoting perfect crystallization and further improving the material's heat resistance and mechanical property stability. In finished product screening, impurities or substandard particles generated during processing are removed, ensuring the quality stability of the bio-based biodegradable cable material.

[0075] In another embodiment of this application, the bio-based matrix resin is vacuum-dried at 80°C for 8 hours to gently and efficiently remove adsorbed surface free water and weakly bound water, avoiding thermal oxidative degradation or chain breakage of numerous ester bonds in the molecular chain due to high temperature. The semi-interpenetrating network reinforcing phase is vacuum-dried at 100°C for 12 hours. The PA56 molecular chain contains a large number of amide bonds, which easily adsorb moisture through hydrogen bonds, and its crystalline structure may encapsulate trace amounts of free water. If moisture remains, it will interfere with the subsequent reaction with the dynamic ester bond crosslinking agent.

[0076] In another embodiment of this application, a high-speed mixer is used to mix bio-based matrix resin, bio-based plasticizer, and antioxidant at 80°C for 10 minutes at a speed of 300 rpm. The 80°C temperature slightly softens the surface of the bio-based matrix resin, reducing intermolecular forces and allowing the bio-based plasticizer to penetrate more easily into the gaps between resin particles. Simultaneously, it promotes the adhesion and initial diffusion of the antioxidant on the resin surface, preventing localized performance fluctuations caused by uneven dispersion of additives during the subsequent melting stage. The 300 rpm speed provides moderate shear force, breaking up slight agglomeration of resin particles without causing localized overheating due to excessive speed (avoiding thermal degradation of the bio-based resin or volatilization of the plasticizer). The 10-minute mixing time balances dispersion effect and energy consumption, ensuring uniform distribution of the plasticizer and antioxidant on the resin particle surface, improving the uniformity and stability of the bio-based biodegradable cable material's performance.

[0077] In another embodiment of this application, the twin-screw extruder is divided into four independent temperature control zones along the material conveying direction. The temperature of zone one is set to 160°C, zone two to 170°C, zone three to 180°C, and zone four to 175°C. The screw speed is controlled at 300-350 r / min. An environmentally friendly flame retardant is added after the material enters zone two and mixed for 5 minutes.

[0078] It should be noted that the settings for each zone and the screw speed serve the following purposes:

[0079] Zone 1 (160℃, feeding section): Preheating and softening of bio-based matrix resin, bio-based plasticizer, and antioxidant reduces frictional resistance between particles and avoids feeding blockage. At the same time, it accumulates heat for subsequent melting to prevent local degradation of bio-based resin due to sudden heating.

[0080] Zone 2 (170℃, melting section): The temperature is close to the melting point of the bio-based matrix resin, allowing the resin particles to gradually melt and form a continuous phase. Dynamic ester bonds undergo cross-linking reactions during the melting process, forming a preliminary cross-linked network. The shear force generated by the screw speed of 300-350 r / min can disperse incompletely melted resin particles and nano-reinforced filler agglomerates, providing a molten matrix carrier for the addition of flame retardants and avoiding local performance defects caused by system inhomogeneity.

[0081] Zone 3 (180℃, reaction section): The high temperature ensures the complete melting of high-melting-point components and provides sufficient activation energy for dynamic ester bond crosslinking reaction, promoting the formation of three-dimensional network structure; strong shear force further disperses the nano-reinforced filler to the nanoscale. The dispersed nanoparticles form a strong interfacial bond with the polymer matrix through hydrogen bonding, van der Waals forces or chemical coordination, which can not only transfer stress to enhance the tensile strength and impact toughness of the material, but also delay heat transfer through the physical barrier effect of nanoparticles, thereby enhancing the mechanical properties and heat resistance of bio-based biodegradable cable materials.

[0082] Zone 4 (175℃, homogenization section): The temperature is slightly lower than that of Zone 3, maintaining the molten state of the mixture and avoiding long-term high-temperature degradation of the melt. At the same time, through screw conveying and mixing, the melt composition and temperature are homogenized, ensuring that the extruded strip has a smooth surface and stable dimensions.

[0083] In another embodiment of this application, annealing at 100°C for 2 hours in a forced-air oven further optimizes the material properties after extrusion pelletizing. This process promotes slow rearrangement of molecular chains through gentle heating, eliminating internal stress generated by rapid cooling during extrusion molding and preventing problems such as dimensional shrinkage and cracking caused by stress release during subsequent processing or use. Simultaneously, the stable temperature environment and uniform thermal field provided by the forced-air oven allow for a more complete internal crystalline structure and a more stable cross-linked network, further improving the dimensional stability and mechanical property consistency of the product, ensuring that the bio-based biodegradable cable material maintains stable heat resistance and mechanical strength during long-term use.

[0084] The present invention will be further illustrated below through specific embodiments:

[0085] Example 1

[0086] The preparation steps of a bio-based biodegradable cable material are as follows:

[0087] (1) 40 parts of PLLA and 20 parts of PHBH were vacuum dried at 80°C for 8 hours, and 10 parts of PA56 were vacuum dried at 100°C for 12 hours to remove moisture.

[0088] (2) Add 40 parts of PLLA, 20 parts of PHBH, 6 parts of the compound of epoxidized soybean oil and tributyl citrate, and 0.5 parts of the compound of hindered phenolic antioxidant 1010 and phosphite antioxidant 168 to a high-speed mixer and stir at 80°C for 10 minutes at a speed of 300 r / min to obtain a premix.

[0089] (3) Add the premix, 4 parts of dianhydride-modified castor oil polyol, 10 parts of PA56, and 5 parts of silane coupling agent KH550-modified nano-montmorillonite to a twin-screw extruder. The twin-screw extruder is divided into four independent temperature control zones along the material conveying direction. The temperature of zone one is set to 160℃, zone two to 170℃, zone three to 180℃, and zone four to 175℃. The screw speed is controlled at 300 r / min. Add 8 parts of the MCA and APP compound when the material enters the second zone and mix for 5 minutes.

[0090] (4) After the extruded strip is cooled and cut into pellets, it is annealed at 100°C for 2 hours in a forced-air drying oven.

[0091] (5) After annealing, the particles are screened to remove impurities, and the bio-based biodegradable cable material is obtained.

[0092] Example 2

[0093] The preparation steps of a bio-based biodegradable cable material are as follows:

[0094] (1) 45 parts of PLLA and 15 parts of PHBH were vacuum dried at 80°C for 8 hours, and 12 parts of PA56 were vacuum dried at 100°C for 12 hours to remove moisture.

[0095] (2) Add 45 parts of PLLA, 15 parts of PHBH, 8 parts of the compound of epoxidized soybean oil and tributyl citrate, and 0.8 parts of the compound of hindered phenolic antioxidant 1010 and phosphite antioxidant 168 to a high-speed mixer and stir at 80°C for 10 minutes at a speed of 300 r / min to obtain a premix.

[0096] (3) Add the premix, 5 parts of dianhydride-modified castor oil polyol, 12 parts of PA56, and 6 parts of silane coupling agent KH550-modified nano-montmorillonite to a twin-screw extruder. The twin-screw extruder is divided into four independent temperature control zones along the material conveying direction. The temperature of zone one is set to 160℃, zone two to 170℃, zone three to 180℃, and zone four to 175℃. The screw speed is controlled at 320 r / min. Add 10 parts of the MCA and APP compound when the material enters the second zone and mix for 5 minutes.

[0097] The remaining steps are the same as in Example 1.

[0098] Example 3

[0099] The preparation steps of a bio-based biodegradable cable material are as follows:

[0100] (1) 42 parts of PLLA and 21 parts of PHBH were vacuum dried at 80°C for 8 hours, and 15 parts of PA56 were vacuum dried at 100°C for 12 hours to remove moisture.

[0101] (2) Add 42 parts of PLLA, 21 parts of PHBH, 10 parts of the compound of epoxidized soybean oil and tributyl citrate, and 1.0 part of the compound of hindered phenolic antioxidant 1010 and phosphite antioxidant 168 to a high-speed mixer and stir at 80°C for 10 minutes at a speed of 300 r / min to obtain a premix.

[0102] (3) Add the premix, 6 parts of dianhydride-modified castor oil polyol, 15 parts of PA56, and 8 parts of silane coupling agent KH550-modified nano-montmorillonite to a twin-screw extruder. The twin-screw extruder is divided into four independent temperature control zones along the material conveying direction. The temperature of zone one is set to 160℃, zone two to 170℃, zone three to 180℃, and zone four to 175℃. The screw speed is controlled at 350 r / min. Add 10 parts of the MCA and APP compound when the material enters the second zone and mix for 5 minutes.

[0103] The remaining steps are the same as in Example 1.

[0104] Comparative Example 1

[0105] The difference between this comparative example and Example 1 is that no dynamic crosslinking agent and semi-interpenetrating network reinforcement phase are added in this comparative example.

[0106] Heat resistance test

[0107] 1. Load Deformation Temperature (HDT) Test

[0108] Test standard: GB / T 1634.2-2019 "Determination of load deformation temperature of plastics - Part 2: Plastics, hard rubber and long fiber reinforced composites"

[0109] Test conditions: The sample size is 80mm×10mm×4mm. A static bending load of 1.82MPa is applied, the heating rate is 120℃ / h, the medium is silicone oil, and the temperature when the deflection at the midpoint of the sample reaches 0.25mm is recorded to characterize the material's heat deformation resistance under moderate load.

[0110] 2. Thermal aging performance test

[0111] Test Standard: GB / T 2951.12-2008 "General Test Methods for Insulation and Sheath Materials of Cables and Optical Fibers - Part 12: General Test Methods – Thermal Aging Test Method"

[0112] Test conditions: Samples were thermally aged for 7 days in a forced-ventilation aging chamber at 120℃ with a wind speed ≥1m / s, ensuring the samples did not contact the chamber walls or each other. After aging, the samples were placed in an environment of 23±2℃ and 50±5% relative humidity for 24 hours before testing. Tensile strength and elongation at break were tested before and after aging according to GB / T 2951.11, and the performance retention rate was calculated (retention rate = performance after aging / performance before aging × 100%) to evaluate the material's long-term resistance to heat and oxygen degradation.

[0113] 3. Thermogravimetric analysis (TGA) test

[0114] Test Standard: GB / T 33047.1-2016 "Thermogravimetric Analysis (TGA) of Plastics Polymers - Part 1: General Rules"

[0115] Test conditions: nitrogen atmosphere (flow rate 50 mL / min), heating rate 10℃ / min, test range 30-800℃, record key indicators: initial decomposition temperature (T5%, temperature at which 5% mass loss occurs), maximum decomposition rate temperature (Tmax, temperature at which the rate of thermal weight loss is fastest), and mass fraction of residue at 800℃ (percentage of residue mass to initial mass) to evaluate the thermal stability and high-temperature residual properties of the material.

[0116] Table 1. Test data of heat resistance for each example

[0117]

[0118] (1) Comparison of heat resistance test data of Examples 1, 2 and 3. Overall, Example 3 has the best heat resistance. Since the synergistic ratio of PLLA and PHBH determines the basic heat resistance of the cable material, the formulation of Example 3 contains as much as 63 parts of PLLA and PHBH, which determines the excellent heat resistance of products of the same specifications. In addition, the functional additives in the formulation are mainly used to build dynamic ester bond crosslinking and semi-interpenetrating network. The addition of nano-reinforcing fillers and plasticizers and the establishment of antioxidant and flame retardant protection can improve heat resistance and mechanical properties. Specifically, the load deformation temperature of Example 3 reaches 138℃, which is significantly improved compared with 126℃ of Example 1 and 132℃ of Example 2. This is due to the formation of a more stable skeleton structure by more bio-based matrix resin. At the same time, the increase of dynamic ester bond crosslinking agent and semi-interpenetrating network reinforcing phase further strengthens the cable material's resistance to deformation at high temperature. In terms of thermal aging performance, Example 3 exhibited a tensile strength retention rate and an elongation at break retention rate of 92% and 88%, respectively, both higher than other examples. This indicates that the synergistic effect of its antioxidant and crosslinking system is more significant, effectively inhibiting the degradation and breakage of molecular chains under thermo-oxidative conditions. Thermogravimetric analysis results also show that Example 3 had an initial decomposition temperature of 325℃, a maximum decomposition rate temperature of 375℃, and a residue mass fraction of 6.5% at 800℃, all of which are the highest values ​​among all examples. This indicates that more flame retardants and nano-reinforced fillers form a more effective thermal insulation and flame retardant barrier at high temperatures, reducing the thermal decomposition rate and mass loss of the cable material, thereby improving overall thermal stability.

[0119] (2) A comparison of the heat resistance test data of Example 1 and Comparative Example 1 shows that even though the two examples contain the same type and proportion of matrix resin, there are still significant differences in heat resistance performance. This difference stems from the absence of the core functional structural components, dynamic crosslinking agent and semi-interpenetrating network reinforcing phase. Although Comparative Example 1 retains some modified nano-montmorillonite and antioxidant, these additives cannot fully exert their effectiveness due to the lack of crosslinking network and the interfacial anchoring effect of PA56. For example, montmorillonite is prone to agglomeration in a matrix without a crosslinking network, making it difficult to form a continuous barrier network, resulting in a residual mass fraction of only 1.8% at 800℃, far lower than 5.0% in Example 1; the antioxidant also cannot effectively inhibit the oxidative degradation of molecular chains due to the lack of protection of the crosslinking structure, further aggravating the decline in thermal aging performance.

[0120] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A bio-based biodegradable cable material, characterized in that, The bio-based biodegradable cable material comprises the following components by weight: Bio-based matrix resin: 55-65 parts; Dynamic ester bond crosslinking agent: 4-6 parts; Semi-interpenetrating network enhancement phase: 10-15 copies; Nano-reinforced filler: 5-8 parts; Bio-based plasticizer: 6-10 parts; Antioxidant: 0.5-1.0 parts; Environmentally friendly flame retardant: 8-12 parts; The bio-based matrix resin is a blend of poly-L-lactic acid and poly-3-hydroxybutyrate-3-hydroxyhexanoate; The dynamic ester bond crosslinking agent is a dianhydride-modified castor oil polyol; The semi-interpenetrating network reinforcement phase is polypentanediamine adipate; The nano-reinforced filler is nano-montmorillonite modified with silane coupling agent KH550.

2. The bio-based biodegradable cable material as described in claim 1, characterized in that: The mass ratio of poly-L-lactic acid to poly-3-hydroxybutyrate-3-hydroxyhexanoate is 3:1-2:

1.

3. The bio-based biodegradable cable material as described in claim 1, characterized in that: The bio-based plasticizer is a compound of epoxidized soybean oil and tributyl citrate, with a mass ratio of epoxidized soybean oil to tributyl citrate of 1:

1. The antioxidant is a compound of hindered phenolic antioxidant 1010 and phosphite antioxidant 168, with a mass ratio of hindered phenolic antioxidant 1010 to phosphite antioxidant 168 of 1:

1. The environmentally friendly flame retardant is a compound of melamine cyanurate and ammonium polyphosphate, with a mass ratio of melamine cyanurate to ammonium polyphosphate of 2:

1.

4. The bio-based biodegradable cable material as described in claim 1, characterized in that: The dianhydride in the dianhydride-modified castor oil polyol is pyromellitic dianhydride.

5. The method for preparing bio-based biodegradable cable material according to any one of claims 1-4, characterized in that, The preparation method includes the following steps: Raw material pretreatment: The bio-based matrix resin and polypentanediamine adipate are vacuum dried to remove moisture; Premixing stage: Bio-based matrix resin, bio-based plasticizer, and antioxidant are added to a high-speed mixer to obtain a premix; Melt blending and crosslinking: The premix, dianhydride-modified castor oil polyol, polypentanediamine adipate, and nano-reinforcing filler are added to a twin-screw extruder. When the temperature is raised to 170°C, an environmentally friendly flame retardant is added and the mixture is blended to complete the crosslinked extruded strip. Pelletizing and annealing: After the extruded strips are cooled and pelletized, they are annealed in a forced-air drying oven; Finished product screening: After annealing, the granules are screened to remove impurities, resulting in bio-based biodegradable cable material.

6. The preparation method according to claim 5, characterized in that, The bio-based matrix resin was vacuum dried at 80°C for 8 hours; The semi-interpenetrating network reinforcement phase was vacuum dried at 100°C for 12 hours.

7. The preparation method according to claim 5, characterized in that, The high-speed mixer mixes bio-based matrix resin, bio-based plasticizer, and antioxidant at 80°C for 10 minutes at a speed of 300 r / min.

8. The preparation method according to claim 5, characterized in that, The twin-screw extruder is divided into four independent temperature control zones along the material conveying direction. The temperature of zone one is set to 160℃, the temperature of zone two is set to 170℃, the temperature of zone three is set to 180℃, and the temperature of zone four is set to 175℃. The screw speed is controlled at 300-350 r / min. The environmentally friendly flame retardant is added after the material enters the second zone and mixed for 5 minutes.

9. The preparation method according to claim 5, characterized in that, The process involves annealing in a forced-air oven at 100°C for 2 hours.

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