Composite resin composition as well as preparation method and application thereof

Abstract

The invention relates to the technical field of composite plastic compositions, in particular to a composite plastic composition as well as a preparation method and application thereof. The composite resin composition is prepared from, by mass, 20-60 parts of modified shell powder, 30-70 parts of bio-based polymer, 0.1-5 parts of hollow silicon dioxide microspheres, 0.5-5 parts of compatilizer and 1-5 parts of other auxiliaries, the modified shell powder comprises shell powder, a first coating arranged on the surface of the shell powder and a second coating connected with the first coating, and the second coating is arranged on the surface of the shell powder. The first coating is a reactive polyphenol-alkoxy coating, and the second coating is a metal chelating layer. A double-layer modified structure of the reactive polyphenol-alkoxy coating and the metal chelating layer is formed on the surface of the shell powder, and the defect that in the prior art, a single coating only depends on physical adsorption, and interface bonding is weak is overcome. The present invention improves mechanical strength, weather resistance and processability by using calcium carbonate-based biological by-products such as shellfish and crustacean shells and compounding the calcium carbonate-based biological by-products with a bio-based resin.

Description

Technical Field

[0001] This invention relates to the field of composite resin composition technology, specifically a composite resin composition, its preparation method, and its application. Background Technology

[0002] In recent years, to address environmental issues, the application of biodegradable plastics such as polylactic acid (PLA), polybutylene succinate (PBS), and polybutylene adipate / terephthalate (PBAT) has become increasingly widespread. However, existing biodegradable resin-based composite materials still have many shortcomings: PLA-based composite resins have low impact strength and high brittleness; PBS / PBAT-based resins require the addition of large amounts of additives to control mechanical strength. Meanwhile, seashells (mainly composed of CaCO3), as industrial byproducts, are mostly landfilled or discarded, becoming one of the causes of environmental pollution. Although there have been studies on the preparation of biodegradable composite resins using seashells, the existing technology still has the following shortcomings: First, when using a single silane or stearic acid-based coating, the coating is purely adsorbent, resulting in poor heat resistance and water resistance of the composite material; Second, if the seashells are subjected to high-temperature or fermentation pretreatment, it will increase costs and cause fluctuations in product quality; Third, when using hollow silica microspheres, their breakage rate is high during the extrusion process, and the lightweight effect is greatly reduced; Fourth, the inherent low heat distortion temperature of biodegradable resin-based composite materials limits their application scenarios.

[0003] Therefore, there is a need to develop a composite material composition that can maintain stable quality and good heat and water resistance while ensuring its lightweight and reducing environmental pollution, in order to solve the current plastic pollution problem and promote the development of a green, low-carbon and circular economy. Summary of the Invention

[0004] In view of the aforementioned technical problems of existing biodegradable composite resins prepared from seashells, such as poor heat resistance and water resistance, high cost, fluctuating product quality, insufficient lightweight effect, and low inherent heat distortion temperature, the present invention adopts the following technical solution to solve the above technical problems.

[0005] A composite resin composition, by mass parts, comprises 20-60 parts of modified seashell powder, 30-70 parts of bio-based polymer, 0.1-5 parts of hollow silica microspheres, 0.5-5 parts of compatibilizer, and 1-5 parts of other additives. The modified seashell powder comprises seashell powder, a first coating disposed on the surface of the seashell powder, and a second coating connected to the first coating. The first coating is a reactive polyphenol-alkoxy coating, and the second coating is a metal chelating layer.

[0006] This invention overcomes the shortcomings of existing single-layer coatings, which rely solely on physical adsorption and have weak interfacial bonding, by forming a two-layer modified structure of reactive polyphenol-alkoxy coating and metal chelate layer on the surface of seashell powder. Specifically, the reactive polyphenol in the first coating has strong adhesion, which can tightly coat the seashell matrix. Combined with the hydrolysis and condensation of alkoxy groups, it forms a stable chemical bond between the inorganic filler and the organic resin. The metal chelate layer of the second coating further fixes the surface structure through strong coordination bonds, which not only reduces the water absorption of the seashell powder and shields it from external moisture intrusion, but also utilizes the heat resistance of metal ions to improve the thermal stability of the interface, fundamentally solving the problem of poor heat resistance and water resistance of composite materials.

[0007] As mentioned above, this invention utilizes the rigidity of the metal chelating layer and the toughness of the reactive polyphenol coating to form an interfacial layer that combines rigidity and flexibility, improving the dispersibility of seashell powder in bio-based polymers. The modified seashell powder, acting as a nucleating agent, promotes the crystallization of bio-based polymers such as polylactic acid and butylene terephthalate. Furthermore, the strong interfacial bonding forces restrict the slippage of polymer molecular chains at high temperatures, thereby increasing the heat distortion temperature of the composite resin composition. Simultaneously, the optimized interfacial layer effectively transfers stress, solving the problems of low impact strength and high brittleness caused by traditional seashell fillers.

[0008] Furthermore, this invention introduces hollow silica microspheres in combination with modified seashell powder, creating a synergistic support effect within the matrix. The excellent lubrication and dispersing properties of the modified seashell powder effectively reduce melt viscosity and shear friction during extrusion processing, thereby reducing the breakage rate of the hollow silica microspheres and ensuring the integrity of the microsphere structure. This allows the composite material to maintain a low density without sacrificing its mechanical properties, resolving the conflict between lightweighting goals and processing technology.

[0009] Specifically, the hollow silica microspheres have an average particle size (D50) of 5-30 μm and an average wall thickness of 0.4-3.0 μm.

[0010] The average particle size of the seashell powder is D50 = 1-15 μm.

[0011] Furthermore, the first coating contains gallic acid or a catechol derivative, and the polyphenol content of the first coating is 0.5-8 wt%.

[0012] Based on the above configuration, gallic acid and catechol derivatives contain catechol or pyrogallol functional groups, which possess wet adhesion properties. They can undergo coordination complexation reactions with calcium ions on the surface of the shell powder, thereby enabling the first coating to firmly anchor to the shell matrix through chemical bonding. This prevents the coating from detaching or shifting during subsequent high-temperature, high-shear extrusion processing. While tightly coating the shell surface, these polyphenolic substances retain a large number of active phenolic hydroxyl groups. These unreacted active functional groups become excellent grafting sites for the second coating, promoting the cross-linking and curing of metal ions with the first coating. This ensures the integrity and density of the double-layer coating structure, thereby maximizing the barrier to water molecule penetration and improving the hydrophobicity and corrosion resistance of the shell powder.

[0013] Furthermore, as a preferred embodiment of the invention and not a limitation thereof, the polyphenol content is limited to 0.5-8 wt%. When the lower limit of the polyphenol content is greater than 0.5 wt%, it ensures that the polyphenol molecules can form a continuous, pore-free, and complete coating film on the surface of the shell powder. If the content is lower than this, the coating coverage is insufficient, and the exposed points on the shell surface are easily eroded by moisture, resulting in a decrease in the water resistance of the composite material. When the upper limit of the polyphenol content is less than 8 wt%, it avoids the self-polymerization or multilayer physical adsorption phenomena caused by excessive accumulation of polyphenol molecules. If the content is higher than this, the excessively thick coating not only increases the cost but also forms a weak boundary layer with poor mechanical properties. Under stress, it is easy for the material to fracture within this layer, which in turn reduces the impact strength and tensile properties of the composite material.

[0014] Furthermore, the second coating contains Zn 2+ or Ca 2+ Gluconic acid complex.

[0015] As mentioned above, the Zn in the gluconate complex 2+ or Ca 2+ As a highly active crosslinking center, it can undergo rapid and strong coordination chelation reactions with the excess catechol or pyrogallol functional groups in the first coating. Through interlayer reactions, it connects independent organic molecular chains into a dense metal-organic network structure. This dense structure can fill the micropores of the coating, forming a strong physical barrier that blocks the path of external water penetration into the shell, thereby improving the hydrolysis resistance of the composite material.

[0016] Based on the above settings, by introducing Zn 2+ or Ca 2+Metal ions, utilizing the high bond energy of metal coordination bonds, increase the thermal decomposition temperature of the coating itself. During high-temperature extrusion or injection molding, this metal-containing chelate layer acts as a heat shield, protecting the internal bio-based material from thermal degradation. Simultaneously, this rigid metal complex layer enhances the interfacial modulus between the filler and the resin matrix, restricting the free movement of polymer molecular chains under heat, thereby increasing the overall heat distortion temperature of the composite material.

[0017] Furthermore, gluconate, as a polyhydroxy organic ligand, possesses abundant organic functional groups and exhibits excellent affinity with bio-based polymers, improving the wetting and dispersibility of inorganic seashell powder in organic resins. Moreover, gluconate segments act as molecular-level lubricants during processing, effectively reducing the coefficient of friction and shear viscosity of the melt. This soft-lubricated environment reduces the mechanical impact of screw shear force on the hollow silica microspheres in the blend system, thereby lowering the microsphere breakage rate and ensuring the lightweight effect of the composite material.

[0018] Furthermore, zinc gluconate and calcium gluconate are widely used in the food and pharmaceutical industries, possessing the characteristics of being non-toxic, biocompatible, and completely biodegradable. Using these complexes as the second coating does not introduce new toxic or harmful substances into the environment, ensuring the ecological safety of the final degradation products.

[0019] Specifically, in some embodiments, the metal ions of the metal chelating layer are Zn. 2+ (The chelation amount is 0.05-0.5 wt%, and the Zn-O bond energy (XPS standard) is in the range of 1021-1023 eV). The chelation reaction pH of the metal chelate layer is in the range of 5.5-7.5.

[0020] Furthermore, the bio-based polymer is any one of polylactic acid, polybutylene succinate, or bio-based polyolefin; the compatibilizer is maleic anhydride-grafted polypropylene, epoxy-containing polymer, or copolymer having both carboxyl and epoxy groups; and the raw material for the shell is oyster shell or clam shell.

[0021] This invention selects polylactic acid (PLA), polybutylene succinate (PBS), or bio-based polyolefins as the matrix resin, ensuring that the composite material possesses excellent mechanical strength while also exhibiting complete biodegradability or reduced carbon footprint, thus meeting the requirements of a green circular economy. By selecting different types of bio-based resins, the rigidity or toughness of the composite material can be specifically adjusted to meet the differentiated performance requirements of various application scenarios.

[0022] The present invention preferably uses maleic anhydride-grafted polypropylene, epoxy-containing polymers, or carboxyl / epoxy copolymers as compatibilizers, and utilizes their high reactivity to generate interfacial chemical bonding effects, thereby further enhancing the overall performance of the material.

[0023] Specifically, the anhydride groups, epoxy groups, or carboxyl groups on the compatibilizer molecular chain can, on the one hand, undergo esterification or ring-opening reactions with the hydroxyl or carboxyl groups at the ends of bio-based polymers such as polylactic acid and polybutylene succinate; on the other hand, they can also chemically bond with the active functional groups on the surface of modified seashell powder, such as the phenolic hydroxyl groups of the first coating or the coordinating groups of the second coating. Through bidirectional chemical bonding, a stable molecular bridge is built between the inorganic filler and the organic matrix, which not only improves compatibility but also effectively transfers stress, making up for the poor impact resistance of simple bio-based resins.

[0024] This invention specifically selects oyster shells or clam shells as raw materials, transforming these aquaculture wastes into valuable resources. This not only solves the environmental odor and land occupation problems caused by the accumulation of waste shells, but also reduces the raw material cost of composite materials and enhances the product's market competitiveness. Oyster shells, in particular, naturally possess a unique layered microstructure. After crushing and modification, this layered structure can act as a sheet-like reinforcing filler in the resin matrix, more effectively blocking gas permeation and improving the material's flexural modulus and dimensional stability compared to ordinary calcium carbonate.

[0025] Furthermore, the method for processing modified seashell powder includes the following steps:

[0026] N1. The collected shells are processed to obtain pretreated shell powder;

[0027] N2, stir the pretreated seashell powder, and react the reactive polyphenol-alkoxy mixture with its surface in the form of a spray to form the first coating.

[0028] N3 and gluconic acid complex solution are dispersed and sprayed onto pretreated seashell powder containing the first coating and react to form a second coating. After drying, the modified seashell powder is recovered.

[0029] This invention involves drying the seashells at 60-75°C before forming the first coating, followed by vacuum drying (60-75°C, 1-3 hours). In steps N2 and N3, the modified liquid is applied via atomized spraying under dynamic stirring conditions. Compared to traditional liquid-phase immersion methods, atomized spraying disperses the modified liquid into micron-sized droplets, which are uniformly adsorbed onto the surface of the tumbling seashell powder, effectively preventing powder agglomeration or hard clustering caused by excessive local liquid. This process ensures that the first and second coatings are uniformly spread on the surface of the seashell particles with molecular-level thickness, eliminating modification blind zones and resulting in a narrow particle size distribution of the final modified powder, exhibiting good dispersion and flowability during subsequent melt blending with resin.

[0030] This invention utilizes the incompletely reacted active sites of the first coating layer (N2 followed by N3) to directly induce an in-situ reaction in the second coating layer. Through a wet-to-wet or semi-dry reaction mode, the two coating layers are not simply physically stacked, but rather form a stable chemically bonded interface. This method not only simplifies intermediate processing steps but, more importantly, ensures the structural integrity of the bilayer structure, preventing coating peeling during drying or subsequent processing.

[0031] In addition, after step N1, a catalyst solution of γ-aminopropyltriethoxysilane can be added first. The alkoxysilane end of γ-aminopropyltriethoxysilane needs to be hydrolyzed to form silanol groups, which then undergo dehydration condensation with the hydroxyl groups on the surface of the seashell powder to form stable Si-O-Ca covalent bonds. The amino end of γ-aminopropyltriethoxysilane serves as an active reaction site, which can react with the carboxyl or phenolic hydroxyl groups in the subsequently introduced gallic acid-alkoxysiloxane oligomer to form amide bonds or strongly bind through hydrogen bonds or electrostatic interactions, thereby connecting the polyphenol functional layer.

[0032] Compared to traditional wet modification methods that require large amounts of solvent dispersion, filtration, and prolonged drying, this invention requires only a small amount of solvent carrier for coating. After the reaction, only a simple drying step is needed, significantly reducing energy consumption and production cycle. Furthermore, the entire preparation process exhibits high modifier utilization, with no waste liquid generated or discharged, eliminating the need for complex wastewater treatment systems and fully meeting the requirements of green chemistry and clean production.

[0033] Specifically, the entire preparation process does not require high-temperature calcination above 800℃ or prolonged bio-fermentation; it can be completed under only mild drying and reaction conditions. This not only reduces equipment requirements and production costs but also avoids damage to the calcium carbonate crystal form, the main component of the shell, preserving the original bioporous structure and mechanical strength of the shell.

[0034] In summary, the core of this invention lies in having the following structure, which differs from existing stearic acid / titanium ester-based technologies:

[0035] Specifically, the first coating is a reactive polyphenol-alkoxy group coating, containing reactive organic compounds with gallic acid-catechol groups and alkoxysiloxane oligomers. It forms covalent bonds with the shell surface at a low temperature of 40-65℃. Unlike existing simple adsorption coatings, the first coating is an organic layer. The formation temperature of the first coating is 40-65℃, the reaction time is 15-60 minutes, and its thickness ranges from 20-150 nm. The second coating is a secondary coating based on a low-temperature metal chelation reaction at pH 5.5-7.5, with a formation temperature of 25-40℃ and a metal chelation time of 5-30 minutes. This invention uses a material that can react with Zn... 2+ Ca 2+The combined biodegradable metal chelating agent, specifically a gluconate metal salt, is chelated with the phenolic group of the first coating at 25-40℃. Its chemical structure is significantly different from that of traditional titanates and silanes. After chelation, a Zn2p peak appears on the surface, and the thickness of the second metal chelating layer is 5-35nm.

[0036] Furthermore, the method for pretreating seashell powder includes the following steps:

[0037] M1. After crushing the seashells, add them to the reaction vessel, add water and stir to adjust the pH value;

[0038] M2. Add peroxide to the mixture from step M1 and heat the mixture to obtain the pretreated product.

[0039] M3. Filter the pretreated material from step M2, wash and dry it to obtain pretreated seashell powder.

[0040] Based on the above settings, the shell processing technology of the present invention adopts a short-term organic matter removal method that is non-enzymatic and non-microbial based. The present invention removes organic matter under the following conditions without using any microorganisms or enzymes: a weakly alkaline environment (pH 9.5-11.2), 0.05-0.2wt% low concentration of oxidant (percarbonate or perborate), temperature 45-60℃, and 2-4 hours.

[0041] This invention represents a process significantly different from existing microbial fermentation methods (10-48 hours or more). Specifically, compared to existing technologies that require high-temperature calcination or bio-fermentation pretreatment of the shells, the surface chemical modification method employed in this invention is gentler, less energy-intensive, and more controllable. This method not only avoids the high costs associated with high-temperature treatment but also eliminates the risk of large batch-to-batch quality fluctuations in bio-fermentation. While ensuring consistent and stable product quality, it maximizes the utilization of waste shell resources, aligning with the development requirements of green, low-carbon, and circular economy.

[0042] Specifically, by adjusting the pH value in step M1 to create a suitable reaction environment, and in conjunction with the strong oxidizing free radicals released by the peroxide in step M2, the keratin, pigments, and residual organic impurities on the surface of the seashell powder can be deeply oxidized, decomposed, and peeled off. This process effectively removes the organic inert layer that hinders interfacial bonding, exposing the clean crystalline surface of calcium carbonate, the main component of the seashell. The deeply cleaned surface contains more microporous structures and high-energy surface sites, providing an adhesion substrate for the chemical anchoring of the reactive polyphenol-alkoxy coating in the subsequent step N2, thereby improving the modification efficiency.

[0043] Specifically, by utilizing the strong oxidizing and bleaching properties of peroxides, this invention can completely destroy amines and bacterial residues that produce a fishy odor in seashells, while simultaneously oxidizing and decomposing colored impurities. This solves the technical problem of unpleasant odors easily generated by seashell powder during processing and use, ensuring the odorless and environmentally friendly characteristics of the final composite resin product. At the same time, it also improves the whiteness of the seashell powder, ensuring that when added as a filler to bio-based polymers, it does not negatively affect the color of the finished product. This broadens the application areas of the material for cosmetic packaging or electronic product casings where appearance is crucial. Compared to the commonly used high-temperature calcination method above 800℃ in existing technologies, the mild reaction conditions of this invention avoid the embrittlement caused by the transformation of seashells from aragonite to calcite at high temperatures or excessive ablation, thus fully preserving the natural high-strength lamellar and porous skeletal structure of the seashells. The chemical pretreatment of this invention can be completed under medium-low temperature heating conditions, reducing energy consumption in the pretreatment process and avoiding carbon dioxide emissions from high-temperature combustion.

[0044] Furthermore, the molar ratio of polyphenols to alkoxysiloxanes in the first coating is between 0.3 and 1.2.

[0045] Specifically, the polyphenol component provides excellent interfacial wettability and chemical anchoring to the shell substrate. The Si-O-Si inorganic framework formed by the hydrolysis and condensation of alkoxysiloxanes provides the structural strength and water barrier of the coating. Within a molar ratio range of 0.3-1.2, the two components can undergo effective intermolecular entanglement and co-condensation, forming a stable organic-inorganic hybrid network, ensuring that the first coating adheres firmly and resists thermal stress. If the ratio is too low (less than 0.3), excessive self-condensation of siloxanes leads to a brittle coating that is prone to cracking and peeling during processing. If the ratio is too high (greater than 1.2), excessive polyphenols cause the coating to soften, reduce water resistance, and easily undergo self-aggregation. The hybrid coating formed within this molar ratio range has an elastic modulus between that of the inorganic shell and the organic resin matrix, forming a modulus transition layer. This gradient transition structure can effectively alleviate interfacial stress caused by the mismatch of thermal expansion coefficients. When the composite material is subjected to external impact, it can more effectively disperse stress, thereby maximizing the impact strength and tensile toughness of the material.

[0046] Furthermore, this molar ratio ensures that after the first coating film has cured, the surface still retains an appropriate amount of active phenolic hydroxyl groups that are not completely sealed by the siloxane. These residual active sites, in appropriate amounts, can interact with the subsequently sprayed Zn... 2+ Ca 2+ A high-density chelation reaction occurs, which tightly bonds the two coatings. On the other hand, it avoids excessive hydrophilicity caused by excess polyphenols, which could damage the barrier properties of the final product.

[0047] Furthermore, the other additives include at least two or more of the following: heat stabilizers, light stabilizers, lubricants, nucleating agents, moisture inhibitors, friction modifiers, and defoamers. The heat stabilizers include at least one of phosphite-based heat stabilizers and phenolic antioxidants. The light stabilizers include at least one of HALS light stabilizers and benzotriazole-based UV absorbers. The lubricants include internal lubricants and external lubricants. The nucleating agents include at least one of organophosphate-based nucleating agents and tartaric acid-based nucleating agents. The moisture inhibitors are silane-based moisture inhibitors.

[0048] This invention preferably uses a compound system of internal and external lubricants, synergistically combined with phosphite-based and phenolic heat stabilizers. The balance of internal and external lubricants reduces internal friction of the resin melt and wall friction between the melt and the equipment, minimizing mechanical damage to the hollow silica microspheres caused by screw shear forces, ensuring the microsphere closed-cell ratio, and maintaining the material's lightweight advantage. Phosphite can decompose hydroperoxides generated during processing, while phenolic antioxidants can capture free radicals. Their synergistic effect effectively prevents thermal oxidative degradation or yellowing of bio-based polymers under high-shear conditions containing fillers, ensuring the molecular weight and mechanical strength of the matrix resin.

[0049] This invention employs organophosphate or tartaric acid-based nucleating agents to create a dual nucleation effect with the aforementioned modified seashell powder. These highly efficient nucleating agents lower the nucleation barrier of bio-based polymers and increase the crystallization rate. Combined with the modified seashell powder, they induce the resin to rapidly form a small and dense crystalline structure, thereby shortening the molding cycle and improving the heat distortion temperature and rigidity of the composite material, thus solving the problem of poor heat resistance in existing bio-based materials.

[0050] Furthermore, addressing the inherent defects of bio-based materials such as easy hydrolysis and aging, this invention introduces a silane-based moisture-absorbing inhibitor and a composite light stabilizer system. The silane-based moisture-absorbing inhibitor actively captures trace amounts of moisture from raw materials and the environment during processing, reacting preferentially with the resin, thereby effectively breaking the high-temperature hydrolysis chain of the bio-based polymer and ensuring the stability of the material's properties. HALS (hindered amine light stabilizer) can capture photo-oxidative free radicals, while benzotriazole-based UV absorbers can convert ultraviolet light energy into harmless heat energy. The combined use of these two components endows the composite material with excellent outdoor weather resistance, preventing surface powdering and brittleness caused by ultraviolet radiation.

[0051] Specifically, based on mass parts, the epoxy-terminated functionalized polymer accounts for 0.3-3 parts, which can react with the phenolic-siloxane in the first coating and also react with the Si-OH on the surface of the hollow silica microspheres to inhibit the agglomeration of broken fine fragments.

[0052] The maleic anhydride graft PP-g-MAH comprises 0.5-4 parts, which can compensate for the polarity difference between bio-based polyolefins and modified seashell powder. The acid value (AN) of PP-g-MAH ranges from 20-60 mg KOH / g.

[0053] The copolymer containing 0.5-2 parts of epoxy / carboxyl groups provides a dual reaction pathway, thereby increasing interfacial adhesion. In some embodiments, the interfacial adhesion can be increased by 20-35%.

[0054] Phosphite-based heat stabilizers, comprising 0.05-0.3 parts, can suppress viscosity decrease caused by peroxide decomposition in the presence of hollow silica microspheres.

[0055] The phenolic antioxidant (bent-type hindered phenol) accounts for 0.05-0.2 parts, which can reduce the oxidative degradation of the resin during high-temperature extrusion, thereby maintaining mechanical strength.

[0056] HALS (sterically hindered amine light stabilizer) at a concentration of 0.1-0.5 parts can compensate for the UV fragility of bio-based polymers.

[0057] A benzotriazole-based UV absorber, at a concentration of 0.05-0.3 parts, can inhibit discoloration and decomposition of outdoor products (panels, building materials, etc.).

[0058] The low molecular weight lubricant (internal / external lubricant) accounts for 0.1-3 parts, which has the side effect of suppressing the breakage of hollow silica microspheres in shear energy density SED controlled extrusion.

[0059] The trace amount of defoamer uses polydimethylsiloxane BYK-024 at a ratio of 0.01-0.05 parts, which solves the problem of occasional bubbles generated when using oxidative-alkali treatment on seashells.

[0060] The organophosphate nucleating agent accounts for 0.05-0.2 parts. In some examples, when used in combination with PBS or PLA, the crystallization rate is increased by 15-30%.

[0061] Tartaric acid nucleating agents, at a concentration of 0.05-0.3 parts, can ensure rigidity even during low-temperature molding.

[0062] The silane-based moisture-absorbing inhibitor contains 0.1-0.3 parts, which interacts with the shell coating to inhibit long-term moisture absorption.

[0063] The surface friction modifier is applied at a concentration of 0.1-0.3 parts. When used in packaging materials and appliance casings, it reduces scratches and friction.

[0064] Furthermore, another object of the present invention is to provide a method for preparing a composite resin composition, comprising the composite resin composition as described above, including the following steps:

[0065] S1. Modified seashell powder, bio-based polymer, compatibilizer and other additives are fed into the extruder through the main feed inlet for mixing;

[0066] S2. Add a portion of hollow silica microspheres at the 20%-40% L / D point of the extruder;

[0067] S3. Add the remaining hollow silica microspheres at the 40%-60% L / D point of the extruder;

[0068] S4. After extrusion and cooling, cut the pellets using a pelletizer.

[0069] Specifically, the 20%-40% point of the extruder's L / D ratio can be understood as the screw's axial position corresponding to L / D = 20%-40%.

[0070] This invention introduces fragile hollow silica microspheres in stages through a side feed port, avoiding the high-intensity shear and compression zones of the solid conveying section (0-20% L / D) and the molten section of the extruder. The hollow silica microspheres directly enter the already molten flexible matrix, significantly shortening their residence time and shear stress exposure within the screw, thereby maximizing the preservation of the microspheres' intact closed-cell structure and achieving the desired low-density and lightweight composite material.

[0071] This invention divides hollow silica microspheres into two parts, adding them at 20%-40% and 40%-60% of the L / D ratio, respectively. This gradual, multiple-batch feeding method avoids the agglomeration of dry material caused by excessive local filling due to a large-scale single addition, which would prevent the microspheres from being properly wetted by the resin. The phased addition ensures that each batch of microspheres is fully coated and dispersed by the melt. This reduces the local packing density of microspheres within the screw channel, effectively reducing self-wear and breakage caused by mutual compression and friction between microspheres, further improving the survival rate of the microspheres.

[0072] In step S1, the modified seashell powder, bio-based polymer, and additives are pre-mixed. When the microspheres are added in subsequent steps, the matrix resin has been fully plasticized under shear heat, and the modified seashell powder is uniformly dispersed within it. The melt at this point forms a soft, protective buffer pool with low viscosity and high lubricity. Upon entry, the microspheres are immediately enveloped by this lubricating melt, which not only reduces the hard impact on the microspheres from the screw and barrel metal surfaces but also utilizes the viscous resistance of the melt to gently transfer mixing energy. This ensures uniform distribution of the microspheres while maintaining the excellent tensile and impact strength of the composite material.

[0073] Furthermore, by controlling the feeding point (within the 20%-60% L / D range), this invention has found the optimal balance between the minimum mixing length required to ensure uniform microsphere mixing and the maximum safe length required to prevent microsphere breakage. This process is robust, adaptable to formulations with varying densities, and ensures minimal product density fluctuations and uniform cell structure during continuous production. It solves the problem of large batch-to-batch quality fluctuations caused by microsphere breakage in existing technologies.

[0074] Furthermore, this invention employs a low-shear hollow silica microsphere protective dispersion process, which differs from existing twin-screw extrusion processes. Its key features are: first, the screw elements are designed to maintain the shear energy density (SED) within the range of 45-75 kJ / kg; second, the hollow silica microspheres are not fed into the main feed inlet, but rather in batches into the extruder at L / D points of 20%-40% and 40%-60%. This differs from the single-feed method of existing extruders, allowing the breakage rate of the hollow silica microspheres to be maintained below 15%.

[0075] Furthermore, another object of the present invention is to provide an application of a composite resin composition, including the composite resin composition as described above, wherein products manufactured by injection molding or extrusion molding of the composite resin composition are used in automotive interior materials, appliance housings, or building panels.

[0076] The hollow silica microspheres of this invention possess high survival rate and low density. Applying this composition to automotive interior materials such as dashboard frames and door panel liners can reduce component weight, thereby improving overall vehicle fuel economy or increasing the driving range of new energy vehicles. Simultaneously, because the pretreatment process thoroughly removes organic residues and odors from the seashells, and the seashell powder replaces some petroleum-based resins, interior parts made from this material have extremely low volatile organic compound (VOC) emissions, fully meeting the stringent air quality standards for automotive interiors and enhancing the health and comfort of the passenger cabin.

[0077] The metal chelate layer and seashell powder of this invention promote matrix crystallization, and the composition exhibits excellent heat distortion temperature. When applied to appliance housings such as rice cooker shells and vacuum cleaner bodies, it maintains dimensional stability and does not soften or deform even under high-temperature environments such as motor heating or prolonged operation, ensuring the electrical safety and assembly tightness of the appliances. Furthermore, the modified seashell powder, after oxidation and bleaching, has high whiteness and few impurities, resulting in a smooth, uniform surface and excellent appearance of the molded product, meeting the aesthetic requirements of high-end home appliances.

[0078] The hydrophobic barrier created by the double-layer coating of this invention, combined with the synergistic protective effect of the compounded light stabilizer, allows the composition to exhibit resistance to hydrolysis and UV aging when applied to building panels such as decorative wall panels and sound-absorbing panels. This effectively solves the problems of traditional bio-based materials being prone to mold, powdering, and cracking in humid or outdoor environments, thus extending the service life of building materials. Furthermore, this material extensively utilizes waste seashells and employs bio-based resins, making it a low-carbon and environmentally friendly material that contributes to the development of a green economy.

[0079] This composite resin composition possesses optimized rheological properties and melt strength, making it suitable not only for large-scale continuous extrusion molding (such as sheets and pipes) but also for precision injection molding to produce environmentally friendly daily necessities (cups, lunch boxes, toothbrush handles, etc.), improving biodegradability. It can also be used to create food contact suitable products for packaging materials or food containers, as well as biodegradable bags, cling film, plastic bags, or agricultural covering films. When manufacturing components with complex geometries, reinforcing ribs, or thin-walled structures, the melt flows smoothly, filling the mold completely without floating fibers or flow marks, resulting in low shrinkage and high dimensional accuracy, significantly reducing defect rates and production costs.

[0080] The present invention has the following beneficial effects:

[0081] 1. This invention overcomes the shortcomings of existing technologies where single coatings rely solely on physical adsorption and have low interfacial bonding strength by forming a dual-layer modified structure of reactive polyphenol-alkoxy coating and metal chelate layer on the surface of seashell powder. This invention also improves mechanical strength, weather resistance, and processability by utilizing calcium carbonate-based biological byproducts from shellfish and crustaceans and combining them with bio-based resins.

[0082] 2. The preparation method of the present invention is controllable, so as to prepare a biodegradable composite resin composition with high yield, excellent mechanical strength and heat resistance. By adopting a dispersion process, hollow silica microspheres are added in batches to the 20%-40% and 40%-60% L / D of the extruder. By reducing the breakage of hollow silica microspheres, the overall quality stability is improved.

[0083] 3. The composite resin composition of the present invention can be applied to automotive interior materials, home appliance casings or building panels, etc., and has the advantages of being green, environmentally friendly and economical in the market. Detailed Implementation

[0084] To enable those skilled in the art to better understand the technical solutions described in this invention, the following embodiments are provided for illustration. Unless otherwise specified, the raw materials, reagents, or devices used in the following embodiments can be obtained from conventional commercial channels or by existing known methods.

[0085] A composite resin composition, by mass parts, comprises 20-60 parts of modified seashell powder, 30-70 parts of bio-based polymer, 0.1-5 parts of hollow silica microspheres, 0.5-5 parts of compatibilizer, and 1-5 parts of other additives. The modified seashell powder comprises seashell powder, a first coating disposed on the surface of the seashell powder, and a second coating connected to the first coating. The first coating is a reactive polyphenol-alkoxy coating, and the second coating is a metal chelating layer.

[0086] The first coating contains gallic acid or a catechol derivative, and the polyphenol content of the first coating is 0.5-8 wt%.

[0087] The second coating contains Zn 2+ or Ca 2+ Gluconic acid complex.

[0088] The bio-based polymer is any one of polylactic acid, polybutylene succinate, or bio-based polyolefin; the compatibilizer is maleic anhydride-grafted polypropylene, epoxy-containing polymer, or copolymer having both carboxyl and epoxy groups; and the raw material of the shell includes oyster shells and clam shells.

[0089] The method for processing modified seashell powder includes the following steps:

[0090] N1. The collected shells are processed to obtain pretreated shell powder;

[0091] N2, stir the pretreated seashell powder, and react the reactive polyphenol-alkoxy mixture with its surface in the form of a spray to form the first coating.

[0092] N3 and gluconic acid complex solution are dispersed and sprayed onto pretreated seashell powder containing the first coating and react to form a second coating. After drying, the modified seashell powder is recovered.

[0093] The method for pretreating seashell powder includes the following steps:

[0094] M1. After crushing the seashells, add them to the reaction vessel, add water and stir to adjust the pH value;

[0095] M2. Add peroxide to the mixture from step M1 and heat the mixture to obtain the pretreated product.

[0096] M3. Filter the pretreated material from step M2, wash and dry it to obtain pretreated seashell powder.

[0097] The molar ratio of polyphenols to alkoxysiloxanes in the first coating is between 0.3 and 1.2.

[0098] The other additives include at least two or more of the following: heat stabilizers, light stabilizers, lubricants, nucleating agents, moisture inhibitors, friction modifiers, and defoamers. The heat stabilizers include at least one of phosphite-based heat stabilizers and phenolic antioxidants. The light stabilizers include at least one of HALS light stabilizers and benzotriazole-based UV absorbers. The lubricants include internal lubricants and external lubricants. The nucleating agents include at least one of organophosphate-based nucleating agents and tartaric acid-based nucleating agents. The moisture inhibitors are silane-based moisture inhibitors.

[0099] Specifically, epoxy-terminated functionalized polymers include at least one of epoxy-terminated polylactic acid prepolymers, epoxy-terminated polybutylene succinate, and epoxy-modified ethylene-methyl acrylate copolymers.

[0100] Maleic anhydride-grafted polypropylene includes maleic anhydride-grafted homopolymer polypropylene and maleic anhydride-grafted copolymer polypropylene.

[0101] Copolymers that simultaneously possess epoxy and carboxyl groups include either acrylate-glycidyl acrylate copolymer or maleic anhydride-epoxypropyl methacrylate copolymer.

[0102] Phosphite-based heat stabilizers include one of the following: triphenyl phosphite, tris(2,4-di-tert-butylphenyl) phosphite, and pentaerythritol diphosphite (2,4-di-tert-butylphenyl) bis(2,4-di-tert-butylphenyl) diphosphite.

[0103] Phenolic antioxidants (bent-type hindered phenols) include one of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate octadecyl alcohol ester and 3,9-bis[2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane.

[0104] HALS sterically hindered amine light stabilizers include bis(2,2,6,6-tetramethylpiperidinol) sebacate and poly{[6-[(1,1,3,3-tetramethylbutyl)amino]]-1,3,5-triazine-2,4-diyl}[(2,2,6,6-tetramethyl-4-piperidinyl)imino]hexamethylene[(2,2,6,6-tetramethyl-4-piperidinyl)imino]}.

[0105] Benzotriazole UV absorbers include one of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole and 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole.

[0106] The internal lubricant includes one of the following: butyl stearate, pentaerythritol tetrastearate, or ethylene bis-stearamide.

[0107] External lubricants include one of the following: polyethylene wax or oxidized polyethylene wax.

[0108] Organophosphate nucleating agents include sodium bis(p-tert-butylphenyl)phosphate and aluminum 2,2'-methylenebis(4,6-di-tert-butylphenyl)phosphate.

[0109] Tartaric acid nucleating agents include one of the following: diisopropyl L-tartrate, calcium tartrate, potassium L-tartrate, or tartaric anhydride derivatives.

[0110] Silyl hygroscopic inhibitors include one of methyltrimethoxysilane, vinyltrimethoxysilane, or γ-aminopropyltriethoxysilane.

[0111] Surface friction modifiers include ultra-high molecular weight polyethylene micro powder, polytetrafluoroethylene micro powder, and modified silica micro powder.

[0112] A method for preparing a composite resin composition, comprising the composite resin composition as described above, including the following steps:

[0113] S1. Modified seashell powder, bio-based polymer, compatibilizer and other additives are fed into the extruder through the main feed inlet for mixing;

[0114] S2. Add a portion of hollow silica microspheres at the 20%-40% L / D point of the extruder;

[0115] S3. Add the remaining hollow silica microspheres at the 40%-60% L / D point of the extruder;

[0116] S4. After extrusion and cooling, the mixture is cut into pellets to obtain a composite resin composition.

[0117] Example 1

[0118] The pretreatment method for seashell powder employs a non-enzymatic, non-microbial-based oxidation-alkali treatment approach, including the following steps:

[0119] Prepare the following raw materials: 1 kg of raw shell powder (average particle size 3-8 mm) consisting of equal parts oyster shells and clam shells, 0.8 g-1.5 g of sodium percarbonate (Na2CO3·1.5H2O2), potassium carbonate (K2CO3) solution for pH adjustment to a final pH of 10.4±0.2, and 8 L of distilled water.

[0120] Equipment conditions: Reactor: 10L PTFE-lined stainless steel reactor, stirring speed: 210rpm, temperature: 50±2℃.

[0121] M1. Crush 1 kg of seashells and add them to the reaction vessel. Pour in 8 L of water and stir at 210 rpm. Add potassium carbonate solution dropwise and adjust the pH to 10.4.

[0122] M2. Add sodium percarbonate to the mixture from step M1 to achieve a concentration of 0.08 wt%, heat to 50°C and maintain for 2.5 hours, filter after the reaction is complete, wash twice with water, and dry at 70°C for 1.5 hours to obtain the pretreated product.

[0123] M3. Filter the pretreated material from step M2, wash and dry it to obtain pretreated seashell powder.

[0124] The purpose of this embodiment is to remove organic matter (proteins, fats, membrane tissues, etc.) from the surface of shells within 2-4 hours and to demonstrate that it is different in principle from existing technologies using microbial fermentation bases.

[0125] Measurement results:

[0126] Organic matter reduction rate: 94.3%; Chemical oxygen demand (COD) reduction rate: 71%; Shell inorganic matter loss rate: <1.8%; Surface Fourier transform infrared spectroscopy (FTIR) analysis results: CH, CN, and protein-related peaks decreased sharply, confirming the removal of the organic film. Because it does not use microorganisms or enzymes, unlike existing technologies, the oxidation-alkali treatment process takes 2-4 hours.

[0127] Example 2

[0128] Based on Example 1, Example 2 has the following implementation method.

[0129] A two-stage reactive surface-modified shell powder treatment method, including a polyphenol-alkoxy layer and a metal chelate layer, comprising the following steps:

[0130] Prepare the raw materials: 500g of pretreated seashell powder (average particle size D50 = 4.1μm); the polyphenolic reactant is gallic acid-alkoxysiloxane oligomer at 3wt%, specifically, the molar ratio of gallic acid to γ-glycidoxypropyltrimethoxysilane is 1:1; the catalyst is γ-aminopropyltriethoxysilane at 0.2wt%, zinc gluconate at 1wt%, and the remainder is a solvent, a mixture of ethanol / water at a mass ratio of 6:4.

[0131] N1. The collected shells are processed to obtain pretreated shell powder;

[0132] N2 and 500g of seashell powder were dry-stirred at 40℃ for 10 minutes. On this basis, the catalyst was added in the form of spray. Gallic acid-alkoxysiloxane mixture (3wt%) was added in the form of spray. The reaction was carried out at 55℃ for 45 minutes. Reaction bonds were formed between the catechol groups and CaCO3 surfaces, and the reaction formed the first coating.

[0133] N3. Spray a 1 wt% zinc gluconate aqueous solution in a fine dispersion form. Perform a chelation reaction at 30°C for 20 minutes to form a second coating. After drying (60°C, 40 minutes), recover the powder.

[0134] The purpose of this embodiment is to verify how to improve interfacial shear strength through a reactive coating structure that is completely different from the chemical structure of existing stearic acid and titanate coatings.

[0135] Example 3

[0136] Based on Example 2, Example 3 has the following implementation method.

[0137] A method for preparing a composite resin composition, comprising the composite resin composition as described above, including the following steps:

[0138] Extruder conditions: 40mm twin-screw, L / D ratio 44; screw speed: 230rpm; zone temperature: 140 / 155 / 160 / 160 / 165 / 165℃; target shear energy density (SED): 50-70kJ / kg; application of low-shear design elements (2 micro-mixing elements, minimizing kneading clumps). Hollow silica microspheres are produced based on the entire screw length (L / D) of the extruder, with 40%-60% of the total input allocated to the upstream 20%-40% points and the remaining 60%-40% to the midstream 40%-60% points. This prevents localized pressure increases and inhibits the breakage of the hollow silica microspheres.

[0139] S1. Modified seashell powder, bio-based polymer, compatibilizer, and other additives are fed into an extruder through the main feed inlet for mixing. By mass, the mixture includes 30 parts of the modified seashell powder, 65 parts of polybutylene succinate, 3 parts of hollow silica microspheres (D50=18μm, wall thickness 1.2μm), 2 parts of the compatibilizer acrylate-glycidyl acrylate copolymer, and 1.35 parts of other additives; specifically, 0.1 parts of triphenyl phosphite and β-(3,5-di-tert-butyl-4-hydroxyphenyl)... Octadecyl propionate accounts for 0.1 parts, bis(2,2,6,6-tetramethylpiperidinol) sebacic acid accounts for 0.1 parts, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole accounts for 0.1 parts, butyl stearate accounts for 0.3 parts, polyethylene wax accounts for 0.2 parts, polydimethylsiloxane BYK-024 accounts for 0.05 parts, sodium bis(p-tert-butylphenyl) phosphate accounts for 0.1 parts, diisopropyl L-tartrate accounts for 0.1 parts, methyltrimethoxysilane accounts for 0.1 parts, and ultra-high molecular weight polyethylene micro powder accounts for 0.1 parts.

[0140] S2. The first feeding is carried out in Zone 3, that is, 1.5 parts of hollow silica microspheres are added at the 30% point of the extruder L / D.

[0141] S3. A second feeding is performed in Zone 5, that is, the remaining hollow silica microspheres are fed into the extruder at 60% of the L / D; the shear energy density SED is 60kJ / kg;

[0142] S4. After extrusion and cooling, cut the pellets using a pelletizer.

[0143] This embodiment describes a low-shear, low-breakage hollow silica microsphere dispersion process. Its purpose is to verify a novel process condition that can significantly reduce the breakage rate of hollow silica microspheres compared to the existing single-feed method.

[0144] Example 4

[0145] Based on Example 2, Example 4 has the following implementation method.

[0146] A method for preparing a composite resin composition, comprising the composite resin composition as described above, including the following steps:

[0147] S1. The modified seashell powder, bio-based polymer, compatibilizer, and other additives are fed into the extruder through the main feed inlet for mixing. By mass, the mixture includes 20 parts of the modified seashell powder, 30 parts of polybutylene succinate, 0.1 parts of hollow silica microspheres, 0.5 parts of epoxy-terminated polybutylene succinate, and 1 part of other additives. Specifically, it consists of: 0.05 parts of tris(2,4-di-tert-butylphenyl) phosphite, 0.05 parts of 3,9-bis[2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane, and poly{[6-[(1,1,3,3-tetramethylbutyl...]...]...]... The following components are listed: 0.1 parts of pentaerythritol tetrastearate (internal lubricant), 0.3 parts of oxidized polyethylene wax (external lubricant), 0.05 parts of 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, 0.05 parts of polydimethylsiloxane BYK-024, 0.05 parts of 2,2'-methylenebis(4,6-di-tert-butylphenyl)aluminum phosphate, 0.05 parts of potassium L-tartrate, 0.1 parts of vinyltrimethoxysilane, and 0.1 parts of polytetrafluoroethylene micropowder.

[0148] S2. For the first feed, add 0.05 parts of hollow silica microspheres at the 20% mark of the extruder's L / D.

[0149] S3. Second feeding: The remaining hollow silica microspheres are fed at the 40% point of the extruder's L / D; the shear energy density (SED) is 45 kJ / kg.

[0150] S4. After extrusion and cooling, cut the pellets using a pelletizer.

[0151] Example 5

[0152] Based on Example 2, Example 5 has the following implementation method.

[0153] A method for preparing a composite resin composition, comprising the composite resin composition as described above, including the following steps:

[0154] S1. Modified seashell powder, bio-based polymer, compatibilizer, and other additives are fed into an extruder through the main feed inlet for mixing. By mass, the mixture includes 60 parts of the modified seashell powder, 70 parts of polybutylene succinate, 5 parts of hollow silica microspheres, 5 parts of epoxy-modified ethylene-methyl acrylate copolymer, and 5 parts of other additives. Specifically, it includes 0.3 parts of bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, and β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid... 0.2 parts of octadecyl alcohol ester, 0.5 parts of bis(2,2,6,6-tetramethylpiperidinol) sebacic acid ester, 0.3 parts of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 1.35 parts of ethylene bis-stearamide, 1.2 parts of polyethylene wax, 0.2 parts of sodium bis(p-tert-butylphenyl) phosphate, 0.3 parts of calcium tartrate, 0.3 parts of γ-aminopropyltriethoxysilane, 0.3 parts of Qinghe Chaotai KH550 modified silica micro powder, and 0.05 parts of polydimethylsiloxane BYK-024.

[0155] S2. For the first feed, add 3 parts of hollow silica microspheres at the 30% point of the extruder's L / D.

[0156] S3. Second feeding: The remaining hollow silica microspheres are fed into the extruder at 50% of the L / D ratio; the shear energy density (SED) is 75 kJ / kg.

[0157] S4. After extrusion and cooling, cut the pellets using a pelletizer.

[0158] Example 6

[0159] Based on Example 2, Example 6 has the following implementation method.

[0160] A method for preparing a composite resin composition, comprising the composite resin composition as described above, including the following steps:

[0161] S1. The modified seashell powder, bio-based polymer, compatibilizer, and other additives are fed into the extruder through the main feed inlet for mixing. By mass, the mixture includes 40 parts of the modified seashell powder, 50 parts of polylactic acid, 2 parts of hollow silica microspheres, 3 parts of maleic anhydride-epoxypropyl methacrylate copolymer, and 2 parts of other additives. Specifically, it includes 0.2 parts of tris(2,4-di-tert-butylphenyl) phosphite, 0.1 parts of 3,9-bis[2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane, and poly{[6-[(1,1,3,3-tetramethylbutyl)amino] The following components are present: 0.2 parts of pentaerythritol tetrastearate (internal lubricant), 0.3 parts of polyethylene wax (external lubricant), 0.2 parts of 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, 0.05 parts of polydimethylsiloxane BYK-024, 0.2 parts of 2,2'-methylenebis(4,6-di-tert-butylphenyl)aluminum phosphate, 0.05 parts of potassium L-tartrate, 0.2 parts of vinyltrimethoxysilane, and 0.2 parts of polytetrafluoroethylene micropowder.

[0162] S2. For the first feed, add 0.8 parts of hollow silica microspheres at the 40% point of the extruder's L / D.

[0163] S3. Second feeding: The remaining hollow silica microspheres are fed at the 60% point of the extruder's L / D; the shear energy density (SED) is 50 kJ / kg.

[0164] S4. After extrusion and cooling, cut the pellets using a pelletizer.

[0165] Example 7

[0166] Based on Example 2, Example 7 has the following implementation method.

[0167] A method for preparing a composite resin composition, comprising the composite resin composition as described above, including the following steps:

[0168] S1. Modified seashell powder, bio-based polymer, compatibilizer, and other additives are fed into an extruder through the main feed inlet for mixing. By mass, the mixture includes 30 parts of the modified seashell powder, 60 parts of poly(butylene adipate / terephthalate), 5 parts of hollow silica microspheres, 5 parts of maleic anhydride-grafted homopolymer polypropylene, and 3 parts of other additives. Specifically, it includes 0.2 parts of bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, 0.2 parts of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate octadecyl alcohol, and poly{[6-[(1,1,3,3-tetramethylbutyl)amino]]-1,3,5-triazine-2,4- 0.5 parts of ⁻¹⁻¹[(2,2,6,6-tetramethyl-4-piperidinyl)imino]hexamethylene[(2,2,6,6-tetramethyl-4-piperidinyl)imino]}, 0.4 parts of butyl stearate as internal lubricant, 0.35 parts of polyethylene wax as external lubricant, 0.2 parts of 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, 0.05 parts of polydimethylsiloxane BYK-024, 0.2 parts of 2,2'-methylenebis(4,6-di-tert-butylphenyl)aluminum phosphate, 0.3 parts of diisopropyl L-tartrate, 0.3 parts of vinyltrimethoxysilane, and 0.3 parts of polytetrafluoroethylene micropowder.

[0169] S2. For the first feed, add 3 parts of hollow silica microspheres at the 30% point of the extruder's L / D.

[0170] S3. Second feeding: The remaining hollow silica microspheres are fed into the extruder at 60% of the L / D ratio; the shear energy density (SED) is 65 kJ / kg.

[0171] S4. After extrusion and cooling, cut the pellets using a pelletizer.

[0172] Example 8

[0173] Based on Example 2, Example 8 has the following implementation method.

[0174] A method for preparing a composite resin composition, comprising the composite resin composition as described above, including the following steps:

[0175] S1. The modified seashell powder, bio-based polymer, compatibilizer, and other additives are fed into the extruder through the main feed inlet for mixing. By mass, the mixture includes 50 parts of the modified seashell powder, 50 parts of Dow Chemical's bio-based polyolefin elastomer REN series bio-based POE, 5 parts of hollow silica microspheres, 2 parts of maleic anhydride graft copolymer polypropylene, and 1.5 parts of other additives. Specifically, it includes 0.2 parts of tris(2,4-di-tert-butylphenyl) phosphite, 0.1 parts of 3,9-bis[2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane, and poly{[6-[(1,1,3,3] 0.2 parts of the following components: 1,3,5-triazine-2,4-diyl[(2,2,6,6-tetramethyl-4-piperidinyl)imino]hexamethylene[(2,2,6,6-tetramethyl-4-piperidinyl)imino]; 0.05 parts of the internal lubricant pentaerythritol tetrastearate; 0.05 parts of the external lubricant polyethylene wax; 0.2 parts of 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole; 0.05 parts of polydimethylsiloxane BYK-024; 0.2 parts of 2,2'-methylenebis(4,6-di-tert-butylphenyl)aluminum phosphate; 0.05 parts of potassium L-tartrate; 0.2 parts of vinyltrimethoxysilane; and 0.2 parts of polytetrafluoroethylene micropowder.

[0176] S2. For the first feed, add 3 parts of hollow silica microspheres at the 20% point of the extruder's L / D.

[0177] S3. Second feeding: The remaining hollow silica microspheres are fed at the 60% point of the extruder's L / D; the shear energy density (SED) is 70 kJ / kg.

[0178] S4. After extrusion and cooling, cut the pellets using a pelletizer.

[0179] Comparative Example 1

[0180] Compared with Example 1, Comparative Example 1 uses pretreated seashell powder prepared by microbial fermentation with a pretreatment time of 10-48 hours, specifically 24 hours. The pretreated seashell powder prepared by microbial fermentation is used to make a composite resin composition, in which hollow silica microspheres are directly mixed and added in step S1 by a single feeding method. The shear energy density SED is 140kJ / kg. Other components and preparation methods are the same as in Example 3.

[0181] Comparative Example 2

[0182] Compared with Example 2, Comparative Example 2 uses a single silane coating, the reaction temperature is 80-110℃, specifically 100℃ for 2 hours, and the modified seashell powder with this single silane coating is used to make a composite resin composition. Other components and preparation methods are the same as in Example 3.

[0183] Comparative Example 3

[0184] Compared with Example 2, Comparative Example 3 uses a stearic acid-based coating, and the reaction temperature is 80-110°C, specifically 100°C for 2 hours. The modified seashell powder with this single stearic acid-based coating is used to make a composite resin composition. Other components and preparation methods are the same as in Example 3.

[0185] Comparative Example 4

[0186] Compared with Example 3, Comparative Example 4 differs in that the hollow silica microspheres in Comparative Example 3 were directly mixed and added in step S1, and the shear energy density SED was 90 kJ / kg. The other components and preparation methods were the same as in Example 3.

[0187] Comparative Example 5

[0188] The difference between Comparative Example 5 and Example 3 is that the shear energy density (SED) of Comparative Example 5 is 35 kJ / kg, while the other components and preparation methods are the same as those of Example 3.

[0189] Comparative Example 6

[0190] The difference between Comparative Example 6 and Example 3 is that the shear energy density (SED) of Comparative Example 6 is 85 kJ / kg, while the other components and preparation methods are the same as those of Example 3.

[0191] Comprehensive tests were conducted on the composite materials of Examples 3 to 8 and Comparative Examples 1 to 6.

[0192] Test methods for the test samples: ASTM D638 (tensile strength), ASTM D256 (cantilever beam impact strength, Izod), ASTM D790 (flexural strength), ASTM D648 (heat distortion temperature, HDT), ASTM D3418 (differential scanning calorimetry, DSC), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM).

[0193] Table 1. Performance test results of Examples 3 to 8

[0194] characteristic unit Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Tensile strength MPa 44.8 42 43.5 54.6 40.2 21.8 Impact strength (Izod) J / m 125 118 122 75 210 140 Bending strength MPa 62.5 60.1 62.1 80 52.3 30.2 Heat distortion temperature (HDT @1.82MPa) ℃ 78.2 76.0 77.2 90.8 72.8 45.2 Hollow silica microsphere breakage rate % 11 8 14 9 12 13 density g / cm³ 0.83 0.84 0.85 0.90 0.80 0.77 Shear energy density SED kJ / kg 60 45 75 50 65 70

[0195] Table 2. Performance test results of Comparative Examples 1 to 6

[0196] characteristic unit Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Tensile strength MPa 31.5 36.2 36.5 38.1 30.5 40.2 Impact strength (Izod) J / m 72 85 87 98 67 103 Bending strength MPa 45.8 50.1 50.5 55.3 44.7 57.3 Heat distortion temperature (HDT @1.82MPa) ℃ 65.8 70.5 70.8 71 64.1 73.2 Hollow silica microsphere breakage rate % 11 11 11 32 5 28 density g / cm³ 1.02 0.99 0.99 0.89 0.90 0.85 Shear energy density SED kJ / kg 140 60 60 90 35 85

[0197] As shown in Tables 1 and 2, the composite resins of Examples 3 to 5 of the present invention are superior to the comparative examples in terms of mechanical strength, impact resistance, heat resistance, and lightweight, demonstrating their technical advantages and promising industrial applications. In Comparative Example 5, the dispersion was poor and the physical properties were the worst; in Comparative Example 6, excessive damage resulted in a decrease in physical properties; Example 3 represented the optimal conditions; Example 4 was at the critical point for achieving the desired physical properties; and Example 5 was at the critical point for suppressing damage.

[0198] For Comparative Example 5, when the shear energy density (SED) is below 45 kJ / kg, the shear force within the extruder is insufficient, causing the seashell powder and hollow silica microspheres to fail to disperse sufficiently within the resin, thus forming aggregates. This increases the brittleness of the final molded product, confirming the technical critical point where the tensile strength drops sharply below 40 MPa.

[0199] For Comparative Example 6, when the shear energy density (SED) exceeds 75 kJ / kg, the hollow silica microspheres disintegrate under high shear conditions due to the high pressure, causing the breakage rate to surge from 11% to 28%. As a result, the lightweight effect is lost, and the fragments act as stress concentration points, leading to a further decrease in tensile strength.

[0200] Compared with Comparative Example 4, under different pretreatment times and methods for the seashell powder, high shear conditions affected the dispersibility, and the introduction of too many broken hollow silica microspheres led to a decrease in the overall mechanical properties.

[0201] Measurement results:

[0202] Surface scanning electron microscopy (SEM): confirmed the formation of a bilayer (reaction layer + metal chelate layer).

[0203] X-ray photoelectron spectroscopy (XPS) analysis showed an increase in the Zn2p peak, confirming the presence of the metal chelate layer.

[0204] Thermogravimetric analysis (TGA): 1.9 wt% organic layer present.

[0205] The interfacial shear strength of Example 3 (composite with cellulose-based biodegradable resin) was 13.4 MPa, compared to 8.5 MPa for the stearic acid coating in Comparative Example 2 and 9.1 MPa for the titanate coating in Comparative Example 3. The interfacial shear strength of Example 3 was significantly better than that of the single coating.

[0206] The stearic acid coating of Comparative Example 2 and the titanate coating of Comparative Example 3 are not as good as those of Example 3 in terms of overall dispersion, heat resistance and waterproofing. Therefore, in terms of mechanical properties, Comparative Example 2 and Comparative Example 3 are worse than Example 3.

[0207] The differences between Example 3 and Comparative Example 4 are as follows: First, Example 3 uses batch feeding, with the first feed being 40-60% of the total and the second feed being 60-40% of the total, while Comparative Example 4 uses a single batch directly mixed with other components. Second, Example 3 uses low shear energy density SED treatment, while Comparative Example 4 uses high shear energy density SED treatment. Third, the screw configuration in Example 3 uses a minimized kneading block, a configuration centered on the conveying element, and two micro-mixers located at the extruder L / D points of 20%-40% and 40%-60%, respectively. Fourth, the hollow silica microspheres in Example 3 are uniformly dispersed, while those in Comparative Example 4 are unevenly dispersed and agglomerate. Fifth, the hollow silica microspheres in Example 3 suffer minimal damage, resulting in improved lightweighting and functionality, while those in Comparative Example 4 experience more breakage, leading to decreased lightweighting and thermal insulation performance. Specifically, in Example 3, the breakage rate of the hollow silica microspheres was 11%, with normal hollow silica microspheres accounting for 89% and broken hollow silica microspheres accounting for 11%. In Comparative Example 4, the breakage rate of the hollow silica microspheres was 32%, with normal hollow silica microspheres accounting for 45%, partially damaged hollow silica microspheres accounting for 23%, and broken hollow silica microspheres accounting for 32%.

[0208] As can be seen from the above, firstly, the interfacial shear strength of Example 3 is 15-40% higher than that of existing stearic acid / titanium ester-based coating technology; secondly, the breakage rate of Examples 3 to 8 is below 15%, and its impact strength is improved compared to the comparative example; thirdly, the shell processing time of Example 3 is within 4 hours, and the process cost is reduced by 30% compared to the fermentation / microbial-based method of Comparative Example 1; fourthly, in terms of density, Examples 3 to 8 are uniformly dispersed, and the shell powder and hollow silica microspheres are uniformly dispersed, which can manufacture lightweight, high-strength parts.

[0209] The polylactic acid of Example 6 of this invention has high rigidity, high brittleness, and good heat resistance. Therefore, its tensile strength, flexural strength, and heat distortion temperature are superior to those of the polybutylene succinate of Example 3. The polybutylene adipate / terephthalate of Example 7 has the advantages of flexibility, high ductility, and impact resistance, but its strength and modulus are low. Therefore, its impact strength is inferior to that of Example 3, while its other mechanical properties are relatively inferior. Bio-based polyolefin elastomers have extremely high elasticity and good impact toughness, but they inherently have low tensile strength, extremely low heat distortion temperature, and low modulus and hardness. Therefore, their impact strength is inferior to that of Example 3, while their other mechanical properties are relatively inferior.

[0210] In summary, this invention relates to a composite resin composition and its preparation method, which improves mechanical strength, weather resistance, and processability by utilizing calcium carbonate-based biological byproducts from shellfish and crustaceans and combining them with bio-based resins. Specifically, this invention relates to the field of high-impact composite resin manufacturing technology, including: first, a non-enzymatic, non-microbial-based short-term shell pretreatment process; second, a two-stage reactive coating formation technology using polyphenol-alkoxy and metal chelates; and third, an optimal shear energy density dispersion process that minimizes the breakage of hollow silica microspheres. The invention also relates to a high-strength, low-shrinkage biodegradable composite resin composition and its preparation method using a bilayer environmentally friendly surface modification process with shellfish inorganic fillers and a low-shear, low-thermal-damage process.

[0211] First, compared with the prior art, the present invention has the advantages of low temperature and short time pretreatment process, reactive coating, two-stage metal chelation protective layer, low shear high strength extrusion process, two batch feeding method, and overcomes the problem of low heat resistance of biodegradable resin.

[0212] Second, the present invention solves the problem of non-reactive adsorption in existing silane and stearic acid-based single coatings and the high-temperature reaction problem in existing titanate and silane coatings: it provides a new combination of a reactive organic polyphenol coating and a metal chelate coating at a temperature of 25-40°C, which is different from the combination.

[0213] Third, this invention solves the problem of achieving a breakage rate of over 30% in the extrusion process when using hollow silica microspheres.

[0214] Fourth, in order to solve the problem of serious carbon dioxide emissions caused by the long time consumption (10-48 hours) or high temperature heat treatment (above 800-1200℃) of the microbial fermentation-based shell pretreatment process, this invention provides a short-term shell organic matter removal process of less than 4 hours based on the simultaneous treatment of low concentration oxidant and weak alkali.

[0215] Fifth, this invention also improves the problems of low heat resistance and low impact strength of biodegradable resins (PLA, PBS, etc.).

[0216] In summary, the following improvements are made to each step of the present invention: First, the modified seashell powder of the present invention contains a reactive polyphenol-alkoxy first coating formed on the surface of the seashell and a second metal chelating layer based on a gluconate metal salt.

[0217] Second, the low-shear dispersion process of the present invention involves feeding hollow silica microspheres in batches to the 20%-40% and 40%-60% L / D points of the extruder, and controlling the shear energy density (SED) at 45-75 kJ / kg.

[0218] Third, the non-microbial / non-enzymatic short-term shell pretreatment process of the present invention is based on a weak alkali (pH 9.5-11.2) and a low concentration of oxidant (0.05-0.2wt%), with a treatment time of 2-4 hours.

[0219] A biodegradable composite resin composition exhibiting excellent mechanical strength and heat resistance, manufactured using the above-described technologies. The composite resin composition and its preparation method according to the present invention provide the following significant practical effects:

[0220] First: Compared with existing stearic acid / titanium ester-based coating technologies, the interfacial shear strength of this invention is increased by more than 15-40% (measured value: 13.4 MPa).

[0221] Second: This invention significantly reduces the breakage rate of HSM to below 15% (measured value: 11%), while achieving lightweight and high impact resistance (measured value: 125J / m).

[0222] Third: This invention shortens the pretreatment time of seashells to less than 4 hours, and reduces the process cost by more than 30% compared with the existing fermentation process.

[0223] Fourth: This invention overcomes the limitation of low heat resistance of biodegradable resins, increasing the heat distortion temperature (HDT@1.82MPa) to over 78℃ (measured value: 78.2℃). Compared with ordinary PP resin (HDT 50-60℃) under the same conditions, it achieves excellent heat resistance. Its tensile strength, flexural strength, and other mechanical properties are comprehensively improved.

[0224] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A composite resin composition, characterized in that: The product comprises, by weight, 20-60 parts modified seashell powder, 30-70 parts bio-based polymer, 0.1-5 parts hollow silica microspheres, 0.5-5 parts compatibilizer, and 1-5 parts other additives. The modified seashell powder includes seashell powder, a first coating disposed on the surface of the seashell powder, and a second coating connected to the first coating. The first coating is a reactive polyphenol-alkoxy coating, and the second coating is a metal chelating layer.

2. The composite resin composition according to claim 1, characterized in that: The first coating contains gallic acid or a catechol derivative, and the polyphenol content of the first coating is 0.5-8 wt%.

3. The composite resin composition according to claim 1, characterized in that: The second coating contains Zn 2+ or Ca 2+ Gluconic acid complex.

4. The composite resin composition according to claim 1, characterized in that: The bio-based polymer is any one of polylactic acid, polybutylene succinate, or bio-based polyolefin; the compatibilizer is maleic anhydride-grafted polypropylene, epoxy-containing polymer, or copolymer having both carboxyl and epoxy groups; and the raw material of the shell includes oyster shells and clam shells.

5. The composite resin composition according to claim 4, characterized in that: The method for processing modified seashell powder includes the following steps: N1. The collected shells are processed to obtain pretreated shell powder; N2, stir the pretreated seashell powder, and react the reactive polyphenol-alkoxy mixture with its surface in the form of a spray to form the first coating. N3 and gluconic acid complex solution are dispersed and sprayed onto pretreated seashell powder containing the first coating and react to form a second coating. After drying, the modified seashell powder is recovered.

6. The composite resin composition according to claim 4, characterized in that: The method for pretreating seashell powder includes the following steps: M1. After crushing the seashells, add them to the reaction vessel, add water and stir to adjust the pH value; M2. Add peroxide to the mixture from step M1 and heat the mixture to obtain the pretreated product. M3. Filter the pretreated material from step M2, wash and dry it to obtain pretreated seashell powder.

7. The composite resin composition according to claim 4, characterized in that: The molar ratio of polyphenols to alkoxysiloxanes in the first coating is between 0.3 and 1.

2.

8. The composite resin composition according to claim 7, characterized in that, The other additives include at least two or more of the following: heat stabilizers, light stabilizers, lubricants, nucleating agents, moisture inhibitors, friction modifiers, and defoamers. The heat stabilizers include at least one of phosphite-based heat stabilizers and phenolic antioxidants. The light stabilizers include at least one of HALS light stabilizers and benzotriazole-based UV absorbers. The lubricants include internal lubricants and external lubricants. The nucleating agents include at least one of organophosphate-based nucleating agents and tartaric acid-based nucleating agents. The moisture inhibitors are silane-based moisture inhibitors.

9. A method for preparing a composite resin composition, comprising the composite resin composition according to any one of claims 1-8, characterized in that, Includes the following steps, S1. Modified seashell powder, bio-based polymer, compatibilizer and other additives are fed into the extruder through the main feed inlet for mixing; S2. Add a portion of hollow silica microspheres at the 20%-40% mark of the extruder's L / D. S3. Add the remaining hollow silica microspheres at the 40%~60% point of the extruder's L / D. S4. After extrusion and cooling, cut the pellets using a pelletizer.

10. The application of a composite resin composition, including the composite resin composition according to any one of claims 1-8, characterized in that, Products manufactured from this composite resin composition by injection molding or extrusion molding are used in automotive interior materials, appliance housings, or building panels.