Production process of waterproof, moistureproof, non-toxic and environment-friendly plastic-wood toy

Abstract

The invention discloses a production process of a waterproof, moistureproof, nontoxic and environment-friendly plastic-wood toy, belongs to the technical field of toy processing, and solves the problems that the environment-friendly plastic-wood toy is resistant to high-temperature and high-humidity gnawing, complex chemical substances are added, unknown toxic substances are possibly generated after aging, current standards are difficult to screen, a safety blind area is formed, and the environment-friendly plastic-wood toy is used for a long time. Comprising the following steps: S1, carrying out controllable micropore activation and selective functional group shielding pretreatment on a wood fiber raw material; s2, carrying out catalytic directional depolymerization and heavy polymerization purification regeneration on the recycled plastic matrix; s3, on the basis of a click chemistry principle, constructing a covalent bond network of a wood-plastic interface in situ in a melt blending process; and S4, carrying out deep penetration and impurity extraction on the blended material or the formed green body by adopting supercritical fluid. Through molecular-level reconstruction and multiple verification, generation of unknown toxic and by-products is blocked in advance, and a traditional detection blind area is penetrated.

Description

Technical Field

[0001] This invention relates to the field of toy processing technology, and in particular to a production process for waterproof, moisture-proof, non-toxic, and environmentally friendly wood-plastic toys. Background Technology

[0002] The environmentally friendly wood-plastic composite toy manufacturing process is a composite technology integrating polymer modification, molding, and green design. Its core is to transform recycled plastics and waste plant fibers into environmentally friendly materials that combine the appearance of wood with the durability of plastic to create toys. Production begins with raw material preparation. Wood fibers need to be dried to a moisture content of less than 2% and treated with coupling agents. The plastics are mostly recycled materials and require compatibilizers and other additives. Next, the raw materials are uniformly mixed at high speed and then melted, plasticized, and granulated into wood-plastic composite granules using a twin-screw extruder. Molding and processing can be selected according to needs, including injection molding, thermoforming, or micro-foaming injection molding, to suit complex and simple structures and weight reduction requirements. Subsequent trimming and sanding ensure a pleasant tactile experience, and surface treatments such as printing enhance the appearance and durability. This process is environmentally friendly throughout the entire lifecycle, with recycled raw materials, low energy consumption, and recyclable products. However, it still faces challenges such as balancing cost design and will continue to develop towards bio-based materials and intelligent manufacturing in the future.

[0003] However, in the production process of environmentally friendly wood-plastic composite toys, in order to produce toys suitable for tropical regions or as bath toys that need to withstand high temperatures and humidity, soaking, and chewing for a long time, manufacturers use high amounts of specific chemical coupling agents (such as aminosilanes) and reactive compatibilizers to deeply modify the materials in order to improve waterproof and moisture-proof properties. These complex chemical substances introduced to achieve the ultimate physical properties may undergo unpredictable cascade chemical reactions (such as chemical bond hydrolysis and degradation product interaction reactions) when exposed to long-term humid heat, ultraviolet radiation, or saliva and sweat. This may generate new toxic substances that are unknown at the initial safety assessment of the formulation, such as specific cyclic siloxanes or nitrosamines.

[0004] Industry-standard mandatory chemical safety testing standards, such as EN71-3, mainly use a list of target compounds and migration tests. These methods target known hazardous substances and cannot effectively screen and identify unexpected unknown hazardous substances newly generated during the complex aging process through conventional quality control procedures, thus creating a "safety blind spot".

[0005] This can lead to problems such as oily substances appearing on the surface, odors, or allergies appearing on products that have passed all factory inspections and been released to the market, even after consumers have used them for several months or even longer.

[0006] Therefore, a waterproof, moisture-proof, non-toxic, and environmentally friendly plastic-wood toy production process is proposed to solve or alleviate the above problems. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing technologies by proposing a waterproof, moisture-proof, non-toxic, and environmentally friendly plastic-wood toy production process.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A manufacturing process for waterproof, moisture-proof, non-toxic, and environmentally friendly wood-plastic composite toys includes the following steps:

[0010] S1. Controllable micropore activation and selective functional group shielding pretreatment of wood fiber raw materials;

[0011] S2. Catalytic directional depolymerization and repolymerization purification and regeneration of recycled plastic matrix;

[0012] S3. Based on the principle of click chemistry, a covalent bond network at the wood-plastic interface is constructed in situ during melt blending;

[0013] S4. Supercritical fluid is used to deeply penetrate and extract impurities from blended materials or molded preforms;

[0014] S5. Construct an inorganic-organic hybrid barrier layer on the surface of the product by reactive vapor deposition;

[0015] S6. Utilize synchrotron X-ray imaging technology to perform three-dimensional non-destructive verification of the microstructure of the product;

[0016] S7. Based on accelerated aging and non-targeted metabolomics analysis, predict and determine the ultimate safety performance of the product.

[0017] Preferably, the pretreatment of the wood fiber raw material with controllable micropore activation and selective functional group shielding specifically includes the following steps:

[0018] S1.1 Steam Explosion-Acid Washing Co-treatment: The dried wood fiber raw material is placed in an intermittent steam explosion tank and maintained at a saturated steam pressure of 1.5-2.0 MPa for 5-8 minutes, followed by instantaneous depressurization to activate the micropores of the fiber; then the exploded raw material is transferred to an acid-resistant reactor and impregnated at 60°C with a 1-3% oxalic acid solution for 30 minutes to dissolve some of the hemicellulose and ash;

[0019] S1.2 Selective end-capping of phenolic hydroxyl groups: After acid washing, the fibers are reacted with excess allyl glycidyl ether in an anhydrous and oxygen-free glove box environment in an aprotic polar solvent, with boron trifluoride diethyl ether complex as a catalyst, at 80°C for 4-6 hours to convert the phenolic hydroxyl groups on the fiber surface into allyl ether structures.

[0020] Preferably, the catalytic directional depolymerization and repolymerization purification and regeneration of the recycled plastic matrix specifically includes the following steps:

[0021] S2.1 The recycled plastic fragments and the supported metal porphyrin catalyst are fed together into a two-stage co-rotating twin-screw reactive extruder;

[0022] S2.2 melts at 160-180℃ under nitrogen protection in the first stage;

[0023] S2.3 raises the temperature to 200-220℃ in the second-stage specific reaction zone, causing the catalyst to selectively break the weak bonds in the plastic molecular chain;

[0024] S2.4 Inject a bifunctional benzoxazine monomer into the reaction zone to allow it to undergo a recombination reaction with the active chain ends formed by the breakage.

[0025] S2.5 uses a high-vacuum devolatilization system connected to the end of the extruder to extract volatile small molecule impurities generated by depolymerization, and then recovers them through a cryogenic trap to obtain a recycled plastic matrix material with a narrowed molecular weight distribution.

[0026] Preferably, the in-situ construction of a covalent bond network at the wood-plastic interface during melt blending based on click chemistry principles specifically includes the following steps:

[0027] S3.1 The processed wood fibers with allyl ether functional groups on the surface, the recycled plastic matrix material, and the catalyst are added together to a meshing internal mixer;

[0028] S3.2 In the melt blending state at 170-190℃, the allyl groups on the surface of wood fibers and the active unsaturated bonds or ends in the plastic matrix undergo mercapto-alkene click chemical reaction or Diels-Alder cycloaddition reaction under the action of a catalyst, forming a hydrolysis-resistant CC or CSC covalent bond interface in situ between the wood fibers and the plastic matrix.

[0029] S3.3 After blending, the material is granulated by an underwater pelletizer to obtain a wood-plastic composite masterbatch with covalent bonds at the interface.

[0030] Preferably, the step of using supercritical fluid to deeply penetrate and extract impurities from the blended material or the molded preform specifically includes the following steps:

[0031] S4.1 The obtained wood-plastic composite masterbatch or the preform formed from it is placed in a supercritical carbon dioxide extraction vessel;

[0032] S4.2 Supercritical carbon dioxide fluid containing ethanol as an entrainer is introduced in a dynamic circulation manner at a pressure of 25-30 MPa and a temperature of 50-60℃.

[0033] S4.3 utilizes its high permeability to dissolve and extract non-covalently bonded, migratable small molecule impurities remaining in the micropores and interfaces of the material;

[0034] During the S4.4 extraction process, the composition of the effluent was monitored using an online UV-Vis spectrometer until the spectral signal baseline stabilized, indicating that the content of extractables was approaching a very low limit.

[0035] Preferably, the construction of the inorganic-organic hybrid barrier layer on the surface of the product by reactive vapor deposition specifically includes the following steps:

[0036] S5.1 The product after deep extraction is placed in the reaction chamber of the atomic layer deposition and plasma-enhanced chemical vapor deposition composite equipment;

[0037] S5.2 At 80°C, by alternately introducing trimethylaluminum and water vapor precursor, 5-10 cycles of atomic layer deposition are performed to form a 5-10 nanometer thick, pinhole-free alumina film on the surface of the product.

[0038] S5.3 Subsequently, the process switches to plasma-enhanced chemical vapor deposition mode, introduces hexamethyldisilazane and oxygen, and under radio frequency plasma excitation, deposits a 20-30 nm thick silica-like organic-inorganic hybrid layer on the surface of the alumina film, forming a dense and hydrophobic composite barrier layer.

[0039] Preferably, the three-dimensional non-destructive verification of the microstructure of the product using synchrotron X-ray imaging technology specifically includes the following steps:

[0040] S6.1 Randomly select the processed products and place them in the hard X-ray coherent diffraction imaging beamline of the synchrotron radiation source;

[0041] S6.2 High-energy hard X-rays are used to perform three-dimensional scanning of key areas such as wall thickness changes or internal seams of the product to obtain coherent diffraction patterns with nanometer-level resolution.

[0042] S6.3 reconstructs a three-dimensional image of the internal microstructure of the sample using a phase retrieval algorithm, which is used to quantitatively assess the interfacial bonding tightness between the wood fiber and the plastic matrix, the presence or absence of internal micro-defects, and the continuity and integrity of the surface deposited film.

[0043] Preferably, the step of predicting and determining the ultimate safety performance of the product based on accelerated aging and non-targeted metabolomics analysis specifically includes the following steps:

[0044] S7.1 Enhanced Accelerated Aging: The verified qualified products are placed in a multi-factor coupled accelerated aging test chamber and subjected to 1000 hours of damp heat aging at 70℃ / 95% relative humidity, 500 hours of continuous xenon lamp ultraviolet irradiation, and cyclic immersion aging in artificial saliva / sweat at 40℃, either sequentially or cyclically.

[0045] S7.2 Non-targeted metabolomics screening: After aging, the samples were subjected to a simulated saliva migration experiment, the migration fluid was collected, and the full spectrum was analyzed by ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry.

[0046] S7.3 Safety assessment: Perform multivariate statistical analysis on the mass spectrometry data of the aged sample with that of the unaged sample and the blank control to identify all significantly increased "difference peaks";

[0047] S7.4 These differential compounds undergo precise structural identification and are assessed for their potential risks using toxicity prediction software.

[0048] S7.5 A batch of products is deemed to have passed full-cycle chemical safety verification only if no new, potentially toxic, significantly different compounds are detected.

[0049] The present invention has the following beneficial effects:

[0050] This invention eliminates the possibility of generating unknown toxic byproducts in complex chemical systems during long-term use by removing reaction sources through molecular surgery of raw materials, constructing stable interfaces through click chemistry, supercritical deep purification, and reconstructing a pre-system with surface nano-encapsulation. Combined with synchrotron radiation to verify structural integrity and accelerated aging coupled with non-targeted metabolomics screening for ultimate predictive verification, this invention fundamentally eliminates the possibility of generating unknown toxic byproducts in complex chemical systems during long-term use, thereby penetrating the safety blind spots of traditional targeted detection standards. Attached Figure Description

[0051] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0052] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0054] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0055] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0056] In the description of this invention, it should be understood that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used to facilitate the description of this invention and to simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0057] Furthermore, the terms "first," "second," and "third" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0058] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0059] A manufacturing process for waterproof, moisture-proof, non-toxic, and environmentally friendly wood-plastic composite toys includes the following steps:

[0060] S1. Controllable micropore activation and selective functional group shielding pretreatment of wood fiber raw materials;

[0061] S1.1 Steam Explosion-Acid Washing Co-treatment: The dried wood fiber raw material is placed in an intermittent steam explosion tank and maintained at a saturated steam pressure of 1.5-2.0 MPa for 5-8 minutes, followed by instantaneous depressurization to activate the micropores of the fiber; then the exploded raw material is transferred to an acid-resistant reactor and impregnated at 60°C with a 1-3% oxalic acid solution for 30 minutes to dissolve some of the hemicellulose and ash;

[0062] S1.2 Phenolic hydroxyl selective end-capping: After acid washing, the fiber was reacted with excess allyl glycidyl ether in an anhydrous and oxygen-free glove box environment in an aprotic polar solvent with boron trifluoride diethyl ether complex as catalyst at 80°C for 4-6 hours to convert the phenolic hydroxyl groups on the fiber surface into allyl ether structures.

[0063] S2. Catalytic directional depolymerization and repolymerization purification and regeneration of recycled plastic matrix;

[0064] S2.1 The recycled plastic fragments and the supported metal porphyrin catalyst are fed together into a two-stage co-rotating twin-screw reactive extruder;

[0065] S2.2 melts at 160-180℃ under nitrogen protection in the first stage;

[0066] S2.3 raises the temperature to 200-220℃ in the second-stage specific reaction zone, causing the catalyst to selectively break the weak bonds in the plastic molecular chain;

[0067] S2.4 Inject a bifunctional benzoxazine monomer into the reaction zone to allow it to undergo a recombination reaction with the active chain ends formed by the breakage.

[0068] S2.5 uses a high-vacuum devolatilization system connected to the end of the extruder to extract volatile small molecule impurities generated by depolymerization, and then recovers them through a cryogenic trap to obtain a recycled plastic matrix material with a narrowed molecular weight distribution.

[0069] S3. Based on the principle of click chemistry, a covalent bond network at the wood-plastic interface is constructed in situ during melt blending;

[0070] S3.1 The processed wood fibers with allyl ether functional groups on the surface, the recycled plastic matrix material, and the catalyst are added together to a meshing internal mixer;

[0071] S3.2 In the melt blending state at 170-190℃, the allyl groups on the surface of wood fibers and the active unsaturated bonds or ends in the plastic matrix undergo mercapto-alkene click chemical reaction or Diels-Alder cycloaddition reaction under the action of a catalyst, forming a hydrolysis-resistant CC or CSC covalent bond interface in situ between the wood fibers and the plastic matrix.

[0072] S3.3 The blended material is granulated by an underwater pelletizer to obtain wood-plastic composite masterbatch with covalent bonds at the interface;

[0073] S4. Supercritical fluid is used to deeply penetrate and extract impurities from blended materials or molded preforms;

[0074] S4.1 The obtained wood-plastic composite masterbatch or the preform formed from it is placed in a supercritical carbon dioxide extraction vessel;

[0075] S4.2 Supercritical carbon dioxide fluid containing ethanol as an entrainer is introduced in a dynamic circulation manner at a pressure of 25-30 MPa and a temperature of 50-60℃.

[0076] S4.3 utilizes its high permeability to dissolve and extract non-covalently bonded, migratable small molecule impurities remaining in the micropores and interfaces of the material;

[0077] During the S4.4 extraction process, the composition of the effluent is monitored by an online UV-Vis spectrometer until the spectral signal baseline stabilizes, indicating that the content of extractables is approaching a very low limit.

[0078] S5. Construct an inorganic-organic hybrid barrier layer on the surface of the product by reactive vapor deposition;

[0079] S5.1 The product after deep extraction is placed in the reaction chamber of the atomic layer deposition and plasma-enhanced chemical vapor deposition composite equipment;

[0080] S5.2 At 80°C, by alternately introducing trimethylaluminum and water vapor precursor, 5-10 cycles of atomic layer deposition are performed to form a 5-10 nanometer thick, pinhole-free alumina film on the surface of the product.

[0081] S5.3 Subsequently, the process was switched to plasma-enhanced chemical vapor deposition mode, and hexamethyldisilazane and oxygen were introduced. Under radio frequency plasma excitation, a silica-like organic-inorganic hybrid layer with a thickness of 20-30 nanometers was deposited on the surface of the alumina film to form a dense and hydrophobic composite barrier layer.

[0082] S6. Utilize synchrotron X-ray imaging technology to perform three-dimensional non-destructive verification of the microstructure of the product;

[0083] S6.1 Randomly select the processed products and place them in the hard X-ray coherent diffraction imaging beamline of the synchrotron radiation source;

[0084] S6.2 High-energy hard X-rays are used to perform three-dimensional scanning of key areas such as wall thickness changes or internal seams of the product to obtain coherent diffraction patterns with nanometer-level resolution.

[0085] S6.3 The three-dimensional image of the internal microstructure of the sample is reconstructed by the phase retrieval algorithm to quantitatively evaluate the interfacial bonding tightness between wood fiber and plastic matrix, the presence or absence of internal micro-defects, and the continuity and integrity of the surface deposited film.

[0086] S7. Based on accelerated aging and non-targeted metabolomics analysis, predict and determine the ultimate safety performance of the product;

[0087] S7.1 Enhanced Accelerated Aging: The verified qualified products are placed in a multi-factor coupled accelerated aging test chamber and subjected to 1000 hours of damp heat aging at 70℃ / 95% relative humidity, 500 hours of continuous xenon lamp ultraviolet irradiation, and cyclic immersion aging in artificial saliva / sweat at 40℃, either sequentially or cyclically.

[0088] S7.2 Non-targeted metabolomics screening: After aging, the samples were subjected to a simulated saliva migration experiment, the migration fluid was collected, and the full spectrum was analyzed by ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry.

[0089] S7.3 Safety assessment: Perform multivariate statistical analysis on the mass spectrometry data of the aged sample with that of the unaged sample and the blank control to identify all significantly increased "difference peaks";

[0090] S7.4 These differential compounds undergo precise structural identification and are assessed for their potential risks using toxicity prediction software.

[0091] S7.5 A batch of products is deemed to have passed full-cycle chemical safety verification only if no new, potentially toxic, significantly different compounds are detected.

[0092] To address the long-term safety crisis caused by deep modification using highly reactive chemical systems, this process adopts an active defense and verification paradigm of "risk precursor removal, active structural stabilization, deep purification of hidden dangers, permanent barrier construction, and ultimate safety prediction".

[0093] Firstly, in the raw material pretreatment stage, this process uses a combination of steam explosion and mild acid washing to synergistically treat the wood fibers. This not only physically increases the specific surface area and reactive sites of the fibers, but more importantly, it removes easily degradable hemicellulose and ash. Then, in a strictly anhydrous and oxygen-free environment, the highly active phenolic hydroxyl groups on the lignin, which are easily oxidized under ultraviolet light and humid heat to generate toxic quinones and phenols, are covalently modified into chemically stable allyl ether structures through an etherification reaction. This step "passivates" the wood flour components at the molecular source, transforming them from "active reactants" that may be attacked by free radicals and trigger chain degradation reactions in the future into "inert fillers," thereby cutting off the possible pathway for the formation of lignin-derived toxins.

[0094] Simultaneously, for the complex and unstable "impurity pool" in the recycled plastic matrix, such as residual antioxidant fragments, amine degradation by azo dyes, and weak bonds generated by oxidation, the process does not simply tolerate them. Instead, it actively purifies them through "molecular surgery" of catalytic directional depolymerization and repolymerization. In a two-stage reactive extruder, a supported metalloporphyrin catalyst precisely identifies and breaks weak bonds in the polymer chain. The subsequently injected bifunctional benzoxazine monomer immediately repolymerizes with the active chain ends. This process, in conjunction with a highly efficient high-vacuum devolatilization system, is like a "chemical dialysis" of the plastic matrix, directly removing unstable short chains, small molecule additive fragments, and other precursors that may participate in future interactive reactions (such as the formation of nitrosamines with amines) from the system. This results in a regenerated matrix with a narrow molecular weight distribution and high chemical purity, eliminating the reactant basis for unpredictable side reactions from another source.

[0095] After completing the molecular-level de-risking modification of the two main raw materials, the third step of the process constructs a revolutionary interface system. It utilizes the specific functional groups generated in the first two steps, the allyl groups on the surface of wood flour and the active sites introduced in recycled plastics, to directly undergo efficient mercapto-alkene click chemistry or Diels-Alder cycloaddition during melt blending. This results in the in-situ formation of a strong CC or CSC covalent bond network between the wood and plastic phases. The interface bond energy is much higher than the easily hydrolyzed Si-OC bond of traditional aminosilane coupling agents, and its hydrolysis resistance is improved by orders of magnitude. This eliminates the risk of the coupling agent decomposing into cyclic siloxanes (such as D4 and D5) and releasing catalytic amine groups due to the hydrolysis of interface bonds. This transforms the "interface" from a weak point and source of risk in traditional processes into a stable and reliable robust linker in this process.

[0096] Furthermore, despite the aforementioned deep processing, the process still presupposes the possibility of the presence of trace amounts of migratable substances. Therefore, supercritical carbon dioxide-assisted deep extraction is introduced as a fourth line of defense. Utilizing the extremely high permeability unique to supercritical fluids, the entrainer it carries can penetrate into every nanoscale micropore and interfacial gap of the material, forcibly "washing out" any residual, unreacted free monomers, catalyst residues, and even any non-covalently bonded small molecule impurities through physical dissolution.

[0097] This step is equivalent to a "deep cleaning" of the material before molding, ensuring that any oily exudate precursors that may slowly migrate to the surface in the future and cause allergies or visual problems for users are removed before the product leaves the factory, greatly reducing the total amount of extractables.

[0098] Subsequently, the process constructs a pinhole-free, shape-preserving nanoscale composite barrier layer on the surface of the deeply purified billet using a combination of atomic layer deposition and plasma-enhanced chemical vapor deposition. The inner dense alumina film perfectly covers all surface micro-defects, while the outer flexible silica-like hybrid layer provides hydrophobicity and durability.

[0099] This "artificial ceramic skin" physically blocks the channels for material migration from the inside to the outside. Even if the material undergoes any minute changes in the extremely distant future, it cannot break through this barrier and migrate to surfaces that children can access, thus achieving absolute isolation and safety in end-use scenarios. This verifies the actual effectiveness of the above steps and eliminates structural defects.

[0100] Synchrotron radiation X-ray coherent diffraction imaging technology was introduced as a non-destructive testing method. It provides three-dimensional perspective of key areas of products at nanometer-level resolution, clearly showing whether the wood-plastic interface is seamlessly integrated, whether there are hidden microbubbles or cracks inside, and whether the surface deposited film is continuous and complete. Any structural defects above the micrometer level cannot hide under this technology, thus ensuring that from macroscopic structure to microscopic morphology.

[0101] A comprehensive safety prediction and assessment system based on enhanced accelerated aging and non-targeted metabolomics was established. This system places products that have completed all the aforementioned steps in a multi-factor coupled accelerated aging environment several times more stringent than the actual working conditions of tropical bath toys, such as extreme humidity and heat, strong ultraviolet spray, and immersion in saliva and sweat circulation, for thousands of hours of extreme stress testing. This is not simply simulating aging, but aims to actively "stimulate" and "consume" all the aging reaction potential that may occur in the material during decades of real use using controllable extreme laboratory conditions. Subsequently, simulated migration experiments were conducted on the aged samples, and non-targeted metabolomics full-spectrum analysis was performed using ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry.

[0102] Instead of relying on a limited list of substances based on any existing safety standards, the system uses big data comparison to intelligently identify all “significant difference peaks” in the migration fluid before and after aging, and performs precise structural identification and toxicity prediction assessment of these unknown compounds. This is equivalent to previewing and comprehensively screening all possible chemical changes that may occur after the product’s entire life cycle before it is put on the market. Only when the analysis confirms that no new unknown migrations with potential toxicity are generated is the product allowed to be released.

[0103] This move fundamentally overturns the targeted testing logic of standards such as EN 71-3 that rely on a known list, expanding the boundaries of safety verification from "known and limited" to "unknown and comprehensive," thereby closing the deadly "safety blind spot" where unintended toxic substances are generated by chemical cascade reactions and cannot be detected by traditional testing.

[0104] It solves specific chemical risks such as aminosilane hydrolysis, in-situ formation of nitrosamines, and precipitation of cyclic siloxanes. More fundamentally, it transforms the long-term chemical safety of products from an unpredictable "black box" into a designable, controllable, and verifiable "white box" process. This ensures that even deeply modified wood-plastic composite products designed for extreme conditions such as tropical bath toys can maintain absolute chemical robustness and safety throughout their entire life cycle.

[0105] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A manufacturing process for waterproof, moisture-proof, non-toxic, and environmentally friendly wood-plastic composite toys, characterized in that: Includes the following steps: S1. Controllable micropore activation and selective functional group shielding pretreatment of wood fiber raw materials; S2. Catalytic directional depolymerization and repolymerization purification and regeneration of recycled plastic matrix; S3. Based on the principle of click chemistry, a covalent bond network at the wood-plastic interface is constructed in situ during melt blending; S4. Supercritical fluid is used to deeply penetrate and extract impurities from blended materials or molded preforms; S5. Construct an inorganic-organic hybrid barrier layer on the surface of the product by reactive vapor deposition; S6. Utilize synchrotron X-ray imaging technology to perform three-dimensional non-destructive verification of the microstructure of the product; S7. Based on accelerated aging and non-targeted metabolomics analysis, predict and determine the ultimate safety performance of the product.

2. The manufacturing process for waterproof, moisture-proof, non-toxic, and environmentally friendly wood-plastic composite toys according to claim 1, characterized in that, The controlled micropore activation and selective functional group shielding pretreatment of the wood fiber raw material specifically includes the following steps: S1.1 Steam Explosion-Acid Washing Co-treatment: The dried wood fiber raw material is placed in an intermittent steam explosion tank and maintained at a saturated steam pressure of 1.5-2.0 MPa for 5-8 minutes, followed by instantaneous depressurization to activate the micropores of the fiber; then the exploded raw material is transferred to an acid-resistant reactor and impregnated at 60°C with a 1-3% oxalic acid solution for 30 minutes to dissolve some of the hemicellulose and ash; S1.2 Selective end-capping of phenolic hydroxyl groups: After acid washing, the fibers are reacted with excess allyl glycidyl ether in an anhydrous and oxygen-free glove box environment in an aprotic polar solvent, with boron trifluoride diethyl ether complex as a catalyst, at 80°C for 4-6 hours to convert the phenolic hydroxyl groups on the fiber surface into allyl ether structures.

3. The manufacturing process for waterproof, moisture-proof, non-toxic, and environmentally friendly wood-plastic toys according to claim 1, characterized in that, The catalytic directional depolymerization and repolymerization purification and regeneration of the recycled plastic matrix specifically includes the following steps: S2.1 The recycled plastic fragments and the supported metal porphyrin catalyst are fed together into a two-stage co-rotating twin-screw reactive extruder; S2.2 melts at 160-180℃ under nitrogen protection in the first stage; S2.3 raises the temperature to 200-220℃ in the second-stage specific reaction zone, causing the catalyst to selectively break the weak bonds in the plastic molecular chain; S2.4 Inject a bifunctional benzoxazine monomer into the reaction zone to allow it to undergo a recombination reaction with the active chain ends formed by the breakage. S2.5 uses a high-vacuum devolatilization system connected to the end of the extruder to extract volatile small molecule impurities generated by depolymerization, and then recovers them through a cryogenic trap to obtain a recycled plastic matrix material with a narrowed molecular weight distribution.

4. The manufacturing process for waterproof, moisture-proof, non-toxic, and environmentally friendly wood-plastic composite toys according to claim 1, characterized in that, The method of constructing a covalent bond network at the wood-plastic interface in situ during melt blending based on click chemistry principles specifically includes the following steps: S3.1 The processed wood fibers with allyl ether functional groups on the surface, the recycled plastic matrix material, and the catalyst are added together to a meshing internal mixer; S3.2 In the melt blending state at 170-190℃, the allyl groups on the surface of wood fibers and the active unsaturated bonds or ends in the plastic matrix undergo mercapto-alkene click chemical reaction or Diels-Alder cycloaddition reaction under the action of a catalyst, forming a hydrolysis-resistant CC or CSC covalent bond interface in situ between the wood fibers and the plastic matrix. S3.3 After blending, the material is granulated by an underwater pelletizer to obtain a wood-plastic composite masterbatch with covalent bonds at the interface.

5. The manufacturing process for waterproof, moisture-proof, non-toxic, and environmentally friendly wood-plastic composite toys according to claim 1, characterized in that, The method of using supercritical fluid to deeply penetrate and extract impurities from blended materials or molded preforms specifically includes the following steps: S4.1 The obtained wood-plastic composite masterbatch or the preform formed from it is placed in a supercritical carbon dioxide extraction vessel; S4.2 Supercritical carbon dioxide fluid containing ethanol as an entrainer is introduced in a dynamic circulation manner at a pressure of 25-30 MPa and a temperature of 50-60℃. S4.3 utilizes its high permeability to dissolve and extract non-covalently bonded, migratable small molecule impurities remaining in the micropores and interfaces of the material; During the S4.4 extraction process, the composition of the effluent was monitored using an online UV-Vis spectrometer until the spectral signal baseline stabilized, indicating that the content of extractables was approaching a very low limit.

6. The manufacturing process for waterproof, moisture-proof, non-toxic, and environmentally friendly wood-plastic composite toys according to claim 1, characterized in that, The construction of an inorganic-organic hybrid barrier layer on the surface of the product by reactive vapor deposition specifically includes the following steps: S5.1 The product after deep extraction is placed in the reaction chamber of the atomic layer deposition and plasma-enhanced chemical vapor deposition composite equipment; S5.2 At 80°C, by alternately introducing trimethylaluminum and water vapor precursor, 5-10 cycles of atomic layer deposition are performed to form a 5-10 nanometer thick, pinhole-free alumina film on the surface of the product. S5.3 Subsequently, the process switches to plasma-enhanced chemical vapor deposition mode, introduces hexamethyldisilazane and oxygen, and under radio frequency plasma excitation, deposits a 20-30 nm thick silica-like organic-inorganic hybrid layer on the surface of the alumina film, forming a dense and hydrophobic composite barrier layer.

7. The manufacturing process for waterproof, moisture-proof, non-toxic, and environmentally friendly wood-plastic composite toys according to claim 1, characterized in that, The method of using synchrotron X-ray imaging technology to perform three-dimensional non-destructive verification of the microstructure of the product specifically includes the following steps: S6.1 Randomly select the processed products and place them in the hard X-ray coherent diffraction imaging beamline of the synchrotron radiation source; S6.2 High-energy hard X-rays are used to perform three-dimensional scanning of key areas such as wall thickness changes or internal seams of the product to obtain coherent diffraction patterns with nanometer-level resolution. S6.3 reconstructs a three-dimensional image of the internal microstructure of the sample using a phase retrieval algorithm, which is used to quantitatively assess the interfacial bonding tightness between the wood fiber and the plastic matrix, the presence or absence of internal micro-defects, and the continuity and integrity of the surface deposited film.

8. The manufacturing process for waterproof, moisture-proof, non-toxic, and environmentally friendly wood-plastic composite toys according to claim 1, characterized in that, The method for predicting and determining the ultimate safety performance of the product based on accelerated aging and non-targeted metabolomics analysis specifically includes the following steps: S7.1 Enhanced accelerated aging: The verified qualified products are placed in a multi-factor coupled accelerated aging test chamber and subjected to 1000 hours of damp heat aging at 70℃ / 95% relative humidity, 500 hours of continuous xenon lamp ultraviolet irradiation, and 40℃ artificial saliva / sweat periodic immersion aging in sequence or cycle. S7.2 Non-targeted metabolomics screening: After aging, the samples were subjected to a simulated saliva migration experiment, the migration fluid was collected, and the full spectrum was analyzed by ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry. S7.3 Safety assessment: Perform multivariate statistical analysis on the mass spectrometry data of the aged sample, the unaged sample, and the blank control to identify all significantly increased "difference peaks"; S7.4 These differential compounds undergo precise structural identification and are assessed for their potential risks using toxicity prediction software. S7.5 A batch of products is deemed to have passed full-cycle chemical safety verification only if no new, potentially toxic, significantly different compounds are detected.

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