Degradable starch-based toy material, child toy and preparation method thereof

Abstract

The invention relates to the field of degradable materials, and discloses a degradable starch-based toy material, a child toy and a preparation method of the degradable starch-based toy material and the child toy. The base material comprises modified plant starch and modified PBAT (poly (butylene adipate-co-terephthalate)) in a mass ratio of (60-70): (30-40); the modified plant starch is plant starch grafted by hydroxyethyl methylacrylate and a silane coupling agent KH-570; the modified PBAT is prepared by mixing, melting and extruding PBAT, maleic anhydride and coupling agent modified nano SiO2; the compatilizer is a segmented copolymer of PEG grafted plant starch and PBS. The starch and PBAT are modified, the compatilizer is added, the safe, environment-friendly and biodegradable child toy material can be successfully manufactured, and on the premise that it is guaranteed that the performance of the composite material meets the manufacturing requirements of child toys, the starch proportion is increased, and meanwhile the comprehensive performance of the child toys is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of degradable materials, and in particular to a degradable starch-based toy material, a children's toy and a preparation method thereof. Background Art

[0002] With the enhancement of people's environmental protection awareness, the problem of environmental pollution has attracted much attention. Therefore, it is of great significance to develop a kind of toy that can be biodegradable, safe and environmentally friendly.

[0003] The existing environmentally friendly degradable materials mainly include polylactic acid (PLA), polybutylene succinate (PBS), polyhydroxyalkanoates (PHA), polybutylene adipate / terephthalate (PBAT), etc. Due to the high cost of these materials and insufficient physical properties, their applications in toy manufacturing are limited. Plant starch comes from plants in nature, is a natural substance, has rich resources, is relatively easy to extract, does not produce harmful substances during the production and use processes, is friendly to the environment, and is more easily biodegradable after being discarded. Using it to prepare toys can greatly reduce the cost.

[0004] Patent CN114806102A discloses a preparation method of a degradable toy and the toy obtained thereby, including the following steps: S1. Preparation of the first mixture: blending PBAT, full starch plastic and polyvinyl alcohol to obtain the first mixture; S2. Preparation of the second mixture: blending sodium dodecylbenzenesulfonate and straw powder to obtain the second mixture; S3. Preparation of the toy masterbatch: blending the second mixture and the first mixture to obtain the toy masterbatch; S4. Putting the toy masterbatch into a mold for compression molding to obtain a toy embryo, and coating a polyvinylidene fluoride coating on the surface of the toy embryo to obtain a finished toy.

[0005] However, starch has strong water absorption and high polarity, and has a large polarity difference from PBAT. When directly blending it with PBAT, increasing the starch ratio easily leads to phase separation, reducing the mechanical properties and stability of the material. Summary of the Invention

[0006] The present invention is to overcome the above problems existing in the starch-based toy materials in the prior art, and provides a degradable starch-based toy material, a children's toy and a preparation method thereof. By modifying starch and PBAT and adding a compatibilizer, a safe, environmentally friendly and biodegradable children's toy material can be successfully manufactured. While ensuring that the properties of the composite material meet the requirements for children's toy manufacturing, the starch ratio is increased while ensuring the comprehensive performance of children's toys.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions: In the first aspect, the present invention provides a degradable starch-based toy material, the raw materials of which include a matrix material and a compatibilizer; The matrix material described above comprises modified plant starch and modified PBAT with a mass ratio of 60 - 70:30 - 40; The modified plant starch is plant starch grafted with 2 - hydroxyethyl methacrylate and silane coupling agent KH - 570; The modified PBAT is prepared by melt - extrusion mixing of PBAT, maleic anhydride, and nano - SiO modified with a coupling agent 2 ; the masses of both maleic anhydride and the coupling - agent - modified nano - silica are 2 - 5% of the mass of PBAT; The compatibilizer is a block copolymer of PEG - grafted plant starch and PBS; The mass of the compatibilizer is 5 - 10% of the total mass of the matrix material.

[0008] First of all, in the present invention, 2 - hydroxyethyl methacrylate (HEMA) and silane coupling agent KH - 570 are used to graft plant starch. The double bonds and hydroxyl groups contained in HEMA, and the double bonds and hydrolyzable siloxy groups contained in silane coupling agent KH - 570 provide a variety of active groups for the grafting reaction, which can react with the hydroxyl groups on starch and other groups in different types, increasing the diversity and sufficiency of the reaction, improving the grafting efficiency and the uniformity of the product. The grafting of HEMA can enhance the hydrophilicity and flexibility of starch, but when combined with PBAT, the interfacial bonding force is insufficient, and it will lead to a decrease in the water resistance of the material; therefore, in the present invention, KH - 570 is added together with HEMA as a composite monomer; the addition of KH - 570 can form chemical bonding or physical entanglement between starch and PBAT, and the methacryloyloxy group of KH - 570 has a similar polarity to the ester group structure of PBAT, further reducing the polarity difference between starch and PBAT, significantly enhancing the interfacial bonding force, reducing the phase - separation phenomenon, making the structure of the composite material more stable and the mechanical properties better; moreover, the silanol groups formed after the hydrolysis of KH - 570 can condense with the hydroxyl groups on the surface of starch and other materials to form stable silicon - oxygen bonds, reducing the water absorption of the material and improving its water resistance. Therefore, through the synergistic effect of HEMA and KH - 570, the interfacial bonding force between starch and PBAT can be significantly enhanced, improving the mechanical properties and water resistance of the composite material; using two composite monomers endows the modified starch with multiple properties, laying a foundation for adding functionality in the subsequent manufacture of children's toys.

[0009] Secondly, in the present invention, maleic anhydride is grafted onto PBAT and nano - SiO is modified with a coupling agent 2 for its modification. The introduction of maleic anhydride can improve the processing performance of PBAT, making it easier to be mixed uniformly with other components such as starch, and at the same time, it also helps to improve the melt fluidity and thermal stability of the composite material; the filling of nano - SiO 2 helps to improve the mechanical properties of the composite material. In the present invention, a coupling agent is used to modify nano - SiO 2After modification and then blending and extrusion with PBAT, the compatibility between inorganic nano-SiO 2 and the organic matrix material and its dispersion in the matrix material can be improved, making the composite material have higher tensile strength, elongation at break and impact strength, and better meeting the requirements of children's toys for material properties.

[0010] Meanwhile, the present invention adds a block copolymer of polyethylene glycol (PEG)-grafted plant starch and poly(butylene succinate) (PBS) as a compatibilizer. The compatibilizer in the present invention has both a starch-philic segment (PEG-grafted plant starch segment) and a PBAT-philic segment (PBS segment), which can significantly improve the compatibility between the modified plant starch and the modified PBAT, reduce the phase separation phenomenon, thereby improving the overall performance and stability of the material and meeting the performance requirements of toys. Moreover, the compatibilizer of the present invention is a biodegradable material and does not affect the biodegradable performance of the material.

[0011] Therefore, the present invention can increase the starch proportion to 60-70% of the matrix material while ensuring that the performance of the composite material meets the requirements for manufacturing children's toys, and at the same time, ensuring the comprehensive performance of children's toys.

[0012] Preferably, when the plant starch is polar grafted with 2-hydroxyethyl methacrylate and silane coupling agent KH-570, the mass ratio of 2-hydroxyethyl methacrylate to silane coupling agent KH-570 is 3-5:1; the total mass of 2-hydroxyethyl methacrylate and silane coupling agent KH-570 is 20-30% of the mass of the plant starch.

[0013] Preferably, the mass of PBS in the compatibilizer is 60-100% of the mass of PEG-grafted plant starch; in the PEG-grafted plant starch, the mass of PEG is 30-50% of the mass of the plant starch.

[0014] Preferably, the plant starch is one or more of corn starch, wheat starch, rice starch, potato starch, and cassava starch.

[0015] Preferably, the raw materials further include a nucleating agent, an antioxidant, an antistatic agent, and a colorant; the mass of the nucleating agent is 1-2% of the total mass of the matrix material, the mass of the antioxidant is 0.5-1.5% of the total mass of the matrix material, the mass of the antistatic agent is 0.2-2% of the total mass of the matrix material, and the mass of the colorant is 0.1-2% of the total mass of the matrix material.

[0016] In a second aspect, the present invention provides a preparation method of the above-mentioned biodegradable starch-based toy material, and the steps include: (1) Performing a grafting reaction on the plant starch with 2-hydroxyethyl methacrylate and silane coupling agent KH-570 to obtain a modified plant starch; (2) React the amino-silane coupling agent with nano-SiO₂ 2 to obtain the coupling agent-modified nano-SiO₂ 2 ; (3) Mix and melt-extrude PBAT, maleic anhydride and the coupling agent-modified nano-SiO₂ 2 to obtain the modified PBAT; (4) First, conduct a grafting reaction on PEG and plant starch to obtain PEG-grafted plant starch; then conduct a copolymerization reaction on the PEG-grafted plant starch and PBS to obtain a compatibilizer; (5) Mix all the raw materials and then extrude and pelletize them to obtain the degradable starch-based toy material.

[0017] Preferably, in step (1), the grafting reaction of plant starch with 2-hydroxyethyl methacrylate and the silane coupling agent KH-570 is carried out in a solvent under the action of a catalyst and an initiator; the catalyst is ferric chloride, and its mass is 0.5 - 1.5% of the total mass of 2-hydroxyethyl methacrylate and the silane coupling agent KH-570; the initiator is KPS and AIBN with a mass ratio of 0.8 - 1.2:1, and the total mass of the initiator is 1 - 2% of the mass of plant starch; the solvent is water, and the mass ratio of water to plant starch is 4 - 6:1.

[0018] Preferably, in step (2), the reaction of the amino-silane coupling agent with nano-SiO₂ 2 is carried out in a solvent under the action of a catalyst; the mass ratio of the amino-silane coupling agent to nano-SiO₂ 2 is 4 - 6:1; the catalyst is dibutyltin dilaurate, and its mass is 1 - 2% of the mass of the amino-silane coupling agent; the solvent is n-hexane, and its mass is 5 - 10 times that of the amino-silane coupling agent.

[0019] Preferably, in step (3), tert-butyl peroxybenzoate as an initiator is added during the melt extrusion, and its mass is 0.1 - 1% of the mass of PBAT.

[0020] Preferably, in step (4), the grafting reaction of PEG and plant starch is carried out in a solvent under the action of an initiator; the initiator is potassium persulfate and sodium bisulfite with a mass ratio of 2 - 3:1, and the total mass of the initiator is 0.5 - 1% of the total mass of PEG and plant starch; the solvent is water, and its mass is 5 - 8 times that of plant starch.

[0021] Preferably, in step (4), the copolymerization reaction of PEG-grafted plant starch and PBS is carried out in a solvent under the action of a catalyst; the catalyst is stannous octoate, and its mass is 0.5 - 1% of the total mass of PEG-grafted plant starch and PBS; the solvent is ethanol, and its mass is 3 - 5 times that of the total mass of PEG-grafted plant starch and PBS.

[0022] In a third aspect, the present invention provides a children's toy made of the above-mentioned degradable starch-based toy material.

[0023] In a fourth aspect, the present invention provides a method for preparing the above-mentioned children's toy, the steps of which are: injection molding or blow molding the degradable starch-based toy material to obtain the children's toy.

[0024] Preferably, after injection molding or blow molding, one or more of the following post-treatment steps are included: A) Annealing: Annealing the molded children's toy by using a variable temperature annealing process in a nitrogen atmosphere; B) Coating: Spraying a coating on the surface of the children's toy; C) Surface treatment: Immersing the children's toy in a plant wax solution and then drying it; the components of the plant wax solution include: rice bran wax, carnauba wax, nano silver particles, a dispersant and ethanol; the mass ratio of rice bran wax, carnauba wax and nano silver particles is 8-10:8-10:2; the mass of the dispersant is 2-5% of the total mass of rice bran wax, carnauba wax and nano silver particles; the total mass concentration of rice bran wax and carnauba wax in the plant wax solution is 6-8%.

[0025] The annealing treatment can improve the physical properties and dimensional stability of the toy. The coating treatment can perform printing and decoration on the toy to increase its aesthetic property. The surface treatment can improve the glossiness and antibacterial property of the toy surface, further enhancing the safety of the children's toy.

[0026] Therefore, the present invention has the following beneficial effects: (1) Significant environmental benefits: Using plant starch to manufacture children's toys, plant starch is a natural and abundant substance, there is no pollution in the production and use process, and it is easily biodegradable after being discarded, effectively solving the environmental pollution problem caused by the non-degradability of traditional petroleum-based plastic toys; (2) Obvious cost advantages: The common environmentally friendly degradable materials in the prior art have high costs and insufficient physical properties, which limit their application in toy manufacturing; the present invention reduces the cost while achieving the environmental protection goal by compounding modified PBAT and modified plant starch; (3) Technological innovation breakthrough: Aiming at the problems of material compatibility and performance deterioration caused by the increase in the starch ratio when starch and PBAT are compounded, the present invention successfully finds a solution, and on the premise of ensuring that the performance of the composite material meets the requirements for manufacturing children's toys, the starch ratio is increased, ensuring the comprehensive performance of the children's toy; (4)High quality standards: The material properties in the present invention comply with the Chinese GB6675 - 2014 children's toy detection standards, and are developed by benchmarking against the EU EN71, US ASTM F963 and CPSIA children's toy and consumer product detection standards. At the same time, it meets the requirements of the Japanese Toy Association ST2016 standard and the relevant requirements of the Health Law JFSL. Detailed implementation manners

[0027] The following further describes the present invention in combination with the detailed implementation manners.

[0028] In the present invention, unless otherwise specified, all equipment and raw materials can be purchased from the market or are commonly used in this industry. The methods in the following embodiments are conventional methods in this field unless otherwise specified.

[0029] General embodiment: A degradable starch-based toy material, the raw materials including a matrix material and a compatibilizer; The matrix material includes modified plant starch and modified PBAT with a mass ratio of 60 - 70:30 - 40; The modified plant starch is plant starch grafted with 2-hydroxyethyl methacrylate and silane coupling agent KH-570; The modified PBAT is prepared by mixing and melt-extruding PBAT, maleic anhydride and a coupling agent-modified nano-SiO 2 ; The masses of maleic anhydride and the coupling agent-modified nano-silica are both 2 - 5% of the mass of PBAT; The compatibilizer is a block copolymer of PEG-grafted plant starch and PBS; The mass of the compatibilizer is 5 - 10% of the total mass of the matrix material.

[0030] As a specific implementation manner, when grafting the plant starch polar with 2-hydroxyethyl methacrylate and silane coupling agent KH-570, the mass ratio of 2-hydroxyethyl methacrylate and silane coupling agent KH-570 is 3 - 5:1; the total mass of 2-hydroxyethyl methacrylate and silane coupling agent KH-570 is 20 - 30% of the mass of the plant starch.

[0031] As a specific implementation manner, the mass of PBS in the compatibilizer is 60 - 100% of the mass of PEG-grafted plant starch; in the PEG-grafted plant starch, the mass of PEG is 30 - 50% of the mass of the plant starch.

[0032] As a specific implementation manner, the plant starch is one or more of corn starch, wheat starch, rice starch, potato starch, and cassava starch.

[0033] As a specific embodiment, the raw materials further include a nucleating agent, an antioxidant, an antistatic agent, and a colorant; the mass of the nucleating agent is 1-2% of the total mass of the matrix material, the mass of the antioxidant is 0.5-1.5% of the total mass of the matrix material, the mass of the antistatic agent is 0.2-2% of the total mass of the matrix material, and the mass of the colorant is 0.1-2% of the total mass of the matrix material.

[0034] As a specific embodiment, the nucleating agent is cellulose nanocrystal; the antioxidant is BASF Irganox B215 of the BASF Irganox B series produced by BASF of Germany; the antistatic agent is quaternized chitosan; the colorant is one or more of organic pigments, inorganic pigments, and plant pigments.

[0035] As a specific embodiment, the organic pigment is one or more of Pigment Red 254, lemon yellow pigment, phthalocyanine blue, and phthalocyanine green; the inorganic pigment is titanium dioxide and / or carbon black; the plant pigment is water-soluble plant pigment and / or fat-soluble plant pigment; the water-soluble pigment is strawberry red pigment and / or anthocyanins; the fat-soluble pigment is one or more of zeaxanthin, chlorophylls, and carotenoids.

[0036] A preparation method of the above-mentioned degradable starch-based toy material, the steps include: (1) Graft the plant starch with 2-hydroxyethyl methacrylate and silane coupling agent KH-570 to obtain modified plant starch; (2) React the amino silane coupling agent with nano-SiO 2 to obtain coupling agent-modified nano-SiO 2 ; (3) Mix and melt-extrude PBAT, maleic anhydride, and coupling agent-modified nano-SiO 2 to obtain modified PBAT; (4) First, graft PEG and plant starch to obtain PEG-grafted plant starch; then copolymerize PEG-grafted plant starch and PBS to obtain a compatibilizer; (5) Mix all the raw materials and extrude them into pellets to obtain the degradable starch-based toy material.

[0037] As a specific embodiment, the grafting reaction of plant starch with 2-hydroxyethyl methacrylate and silane coupling agent KH-570 in step (1) is carried out in a solvent under the action of a catalyst and an initiator; the catalyst is ferric chloride, and its mass is 0.5-1.5% of the total mass of 2-hydroxyethyl methacrylate and silane coupling agent KH-570; the initiator is KPS and AIBN with a mass ratio of 0.8-1.2:1, and the total mass of the initiator is 1-2% of the mass of plant starch; the solvent is water, and the mass ratio of water to plant starch is 4-6:1.

[0038] As a specific embodiment, the reaction steps of step (1) are as follows: 1) Preparation of composite monomer: ① Raw material preparation: Weigh 2-hydroxyethyl methacrylate (HEMA), silane coupling agent KH-570 and ferric chloride catalyst in proportion; the purity of the raw materials should reach over 98%. ② Feeding: Add the weighed HEMA and KH-570 into a stainless steel multi-functional reaction kettle, start stirring, set the rotation speed to 200-300 r / min, and stir for 6-10 min to fully mix the two monomers evenly. ③ Adding catalyst: Slowly add the weighed ferric chloride catalyst into the reaction vessel, maintain the rotation speed of 200-300 r / min, and continue to stir for 6-10 min to ensure that the catalyst is evenly dispersed in the monomer mixture. ④ Reaction temperature control: Start the heating device, gradually increase the temperature of the reaction system to 50-60 °C at a heating rate of 2-3 °C / min, and keep this temperature stable through the temperature control device. ⑤ Reaction progress: At 50-60 °C, let HEMA react with KH-570 under the action of ferric chloride catalyst for 2-3 h, and keep stirring throughout the reaction to promote full contact of the reactants. ⑥ Reaction end: After the reaction for 2-3 h ends, turn off the heating device, stop stirring, and let the reaction system cool naturally to room temperature to obtain the composite monomer for standby.

[0039] 2) Initiator compounding: ① Weigh the initiator: Weigh potassium persulfate (KPS) and azobisisobutyronitrile (AIBN) in proportion respectively. ② Add solvent: Add water into the stainless steel multi-functional reaction kettle. ③ Add initiator: Start stirring, set the rotation speed to 200-300 r / min. Under the stirring condition, first slowly add KPS into water, stir until it is completely dissolved, then add AIBN dissolved in a small amount of ethanol, and continue to stir for 10-15 min to fully mix the initiator evenly. ④ Introduce nitrogen: Introduce nitrogen into the reaction vessel to remove the air inside the vessel; the compounding process is carried out at room temperature, with a stirring time of 30 - 60 min. The whole process is carried out under nitrogen protection to prepare the initiator solution for standby.

[0040] 3) Starch dispersion: Add water to the stainless - steel multi - functional reaction kettle, start stirring, and add plant starch under stirring. At the same time, introduce nitrogen into the reaction vessel, heat up to 60 - 70 °C, control the stirring speed at 250 - 350 rpm, and stir for 40 - 60 min to fully disperse the starch and obtain a starch suspension.

[0041] 4) Grafting reaction: Add the compounded monomer prepared for standby to the starch suspension and stir evenly; slowly drip the initiator solution using a peristaltic pump, with the dripping time controlled at 20 - 40 min; after the dripping is completed, heat up to 75 - 85 °C at a heating rate of 3 - 5 °C / min and react for 3 - 4 h. During the reaction process, keep the stirring speed at 350 - 450 rpm; the whole process is carried out under nitrogen protection.

[0042] 5) Product separation and washing: After the reaction is completed, cool the reaction solution to room temperature, pour it into a centrifuge, centrifuge at 5000 - 8000 rpm for 30 - 40 min, and collect the precipitate; wash the precipitate with deionized water repeatedly 2 - 4 times to remove the residual initiator and impurities.

[0043] 6) Drying and grinding: Place the washed precipitate in a vacuum drying oven, set the vacuum degree to - 0.09 - - 0.1 MPa, dry it to constant weight at 50 - 55 °C, crush the crude product with a crusher, and pass it through an 80 - 100 - mesh sieve to obtain the graft - modified corn starch.

[0044] As a specific embodiment, the reaction of the amino - silane coupling agent and nano - SiO 2 in step (2) is carried out in a solvent under the action of a catalyst; the mass ratio of the amino - silane coupling agent to nano - SiO 2 is 4 - 6:1; the catalyst is dibutyltin dilaurate, and its mass is 1 - 2% of the mass of the amino - silane coupling agent; the solvent is n - hexane, and its mass is 5 - 10 times that of the amino - silane coupling agent.

[0045] As a specific embodiment, the reaction steps of step (2) are: 1) Inject n - hexane into the stainless - steel multi - functional reaction kettle with a reflux condenser, introduce nitrogen, start stirring, adjust the rotation speed to 500 - 600 r / min, and stir for 5 - 10 min to fully mix the n - hexane. 2) Add an amino-silane coupling agent, reduce the stirring speed to 300 - 400 r / min, and stir for 15 - 20 min until homogeneous. 3) Add dibutyltin dilaurate (DBTDL), continue stirring for 5 - 10 min to fully mix the catalyst and the coupling agent. 4) Slowly add nano-SiO 2 , increase the stirring speed to 400 - 500 r / min, and stir for 30 - 40 min to ensure uniform dispersion in the reaction system. 5) Heat up to 80 - 90 °C, maintain the reflux reaction for 2 - 3 h, and keep the stirring speed at 200 - 300 r / min to allow the reaction system to fully react. 6) After the reaction is completed, cool the reaction system to room temperature, pour it into a centrifuge, with a centrifuge speed of 5000 - 8000 r / min for 20 - 30 min; wash it 3 - 4 times with n-hexane to remove impurities. 7) Place the washed nano-SiO 2 in a vacuum drying oven at 50 - 60 °C, set the vacuum degree to -0.09 - -0.1 MPa, and dry for 8 - 10 h to obtain the coupling agent-modified nano-SiO 2 for standby.

[0046] As a specific embodiment, in step (3), add tert-butyl peroxybenzoate as an initiator during melt extrusion, with a mass of 0.1 - 1% of the mass of PBAT.

[0047] As a specific embodiment, the reaction steps of step (3) are as follows: 1) Premixing: First, put the weighed PBAT particles into a high-speed mixer, then add the coupling agent-modified nano-SiO 2 , stir for 10 - 20 min, then add maleic anhydride (MAH) and tert-butyl peroxybenzoate, and continue stirring for 10 - 20 min, with the rotation speed controlled at 300 - 500 r / min to ensure preliminary uniform dispersion of each component. 2) Melt grafting: The premixed raw materials are extruded through a twin-screw extruder with a screw length-diameter ratio of 30:1 - 35:1, and each heating zone is set separately; the feeding section is 140 - 150 °C, the melting section is 160 - 170 °C, the homogenizing section is 170 - 180 °C, and the die head is 175 - 185 °C; the screw rotation speed is 200 - 300 r / min. 3) Cooling and pelletizing: The extruded strip is cooled and shaped through a water-cooling tank, the pellet size is 3 - 5 mm, and it is dried with hot air to obtain the modified PBAT.

[0048] As a specific embodiment, the grafting reaction of PEG and plant starch in step (4) is carried out in a solvent under the action of an initiator; the initiator is potassium persulfate and sodium bisulfite with a mass ratio of 2-3:1, and the total mass of the initiator is 0.5-1% of the total mass of PEG and plant starch; the solvent is water, and the mass is 5-8 times the mass of plant starch.

[0049] As a specific embodiment, the copolymerization reaction of PEG-grafted plant starch and PBS in step (4) is carried out in a solvent under the action of a catalyst; the catalyst is stannous octoate, and the mass is 0.5-1% of the total mass of PEG-grafted plant starch and PBS; the solvent is ethanol, and the mass is 3-5 times the total mass of PEG-grafted plant starch and PBS.

[0050] As a specific embodiment, the reaction steps of step (4) are as follows: 1) Synthesis of PEF-grafted plant starch: ① Starch dissolution: Deionized water is injected into a stainless-steel multi-functional reaction kettle, and then plant starch is added. The temperature is raised to 50-60 °C, and it is stirred at a speed of 300 r / min for 60-90 min until the starch is completely dissolved to form a uniform semi-transparent solution; ② Addition of PEG and initiator: The weighed PEG and the prepared potassium persulfate-sodium bisulfite initiator in proportion are successively added to the reaction kettle. Nitrogen is introduced into the reaction system to discharge the air in the reaction system, and stirring is continued for 20-30 minutes to fully mix the components; ③ Heating reaction: The heating temperature is set at 70-75 °C, and the stirring speed is maintained at 300-500 r / min, and the reaction is carried out for 7-9 h.

[0051] ④ After the reaction is completed, the reaction solution is cooled to room temperature, poured into a centrifuge, and centrifuged at 5000-8000 rpm for 20-30 min to collect the precipitate; the precipitate is washed 3-4 times with deionized water to remove the residual initiator and impurities; ⑤ Drying and pulverization: The washed precipitate is placed in a vacuum drying oven, the vacuum degree is set at -0.09~-0.1 MPa, and it is dried to constant weight at 50-55 °C. The crude product is pulverized with a pulverizer and sieved through an 80-100 mesh sieve to obtain PEG-grafted plant starch.

[0052] 2) Synthesis of compatibilizer: ① Material mixing: Ethanol is injected into a multi-functional reaction kettle, and the weighed PEG-grafted plant starch and PBS are added to the reaction kettle, and it is stirred at a speed of 300 r / min for 30-60 min to fully mix the materials evenly; ②Add catalyst: Add stannous octoate into the reactor, introduce nitrogen into the reaction system, discharge the air in the reaction system, and continue stirring for 15 - 30 min to fully mix all components; ③Heat the reaction: Set the heating temperature at 130 °C, keep the stirring speed at 300 - 500 r / min, and react for 8 - 10 h; The whole process is carried out under nitrogen protection; ④Product separation and washing: After the reaction is completed, cool the reaction solution to room temperature, pour it into a centrifuge, centrifuge at 5000 - 8000 rpm for 20 - 30 min, and collect the precipitate; Wash the precipitate with methanol 2 - 3 times to remove the residual initiator and impurities; ⑤Drying: Put the washed product into a vacuum drying oven, set the vacuum degree at -0.09 - -0.1 MPa, set the temperature at 50 - 60 °C and dry to constant weight to obtain the compatibilizer.

[0053] As a specific embodiment, the reaction steps of step (5) are as follows: 1) Pretreatment of raw materials: ①Drying treatment of basic materials (to prevent bubbles or hydrolysis during the composite process): Place the modified plant starch and modified PBAT in a drying oven, dry at 80 - 100 °C for 4 - 6 h to remove moisture; ②Pretreatment of colorants (to enhance the binding force between the colorant and the matrix): Pretreatment of organic pigments: Weigh 10 parts of organic pigments, 0.5 - 1 part of silane coupling agent KH - 570, and 30 - 50 parts of ethanol by weight; Through reaction, washing, and drying, obtain the pretreated organic pigments; Pretreatment of inorganic pigments: Weigh 10 parts of inorganic pigments, 0.3 - 0.8 part of stearic acid, and 20 - 30 parts of ethyl acetate by weight; Through reaction, washing, and drying, obtain the pretreated inorganic fillers; Pretreatment of water - soluble plant pigments: Weigh 10 parts of water - soluble plant pigments, 2 - 3 parts of gelatin, 1 - 2 parts of gum arabic, and 100 - 150 parts of water by weight; Through reaction, homogenization treatment, washing, and drying, collect the micro - encapsulated water - soluble plant pigments; Pretreatment of fat - soluble plant pigments: Weigh 10 parts of fat - soluble plant pigments, 1 - 2 parts of soy lecithin, and 30 - 50 parts of ethanol by weight; Through reaction, homogenization treatment, washing, and drying, collect the dried product to obtain the pretreated fat - soluble plant pigments.

[0054] 2) Premixing of raw materials: Add the modified plant starch, modified PBAT, compatibilizer, nucleating agent, antioxidant, antistatic agent, and colorant in sequence, set the stirring speed at 500 - 800 r / min, and stir for 10 - 15 min after each component material is added to make them evenly dispersed in the system to form a premix.

[0055] 3) Twin-screw extruder melt compounding: The premix is extruded using a twin-screw extruder with a length-diameter ratio of 30:1 to 40:1; it is set with multiple temperature zones, the feeding section is 120 - 130 °C, the melting section is 140 - 150 °C, the homogenizing section is 150 - 160 °C, and the die head is 160 - 170 °C; the screw speed is 200 - 250 r / min; the extruded composite material is made into 3 - 5 mm granular material through cooling, pelletizing, and hot air drying methods to obtain the degradable starch-based toy material.

[0056] A preparation method of a children's toy made of the above-mentioned degradable starch-based toy material, the steps are: injection molding or blow molding the degradable starch-based toy material to obtain the children's toy.

[0057] As a specific implementation manner, after injection molding or blow molding, it further includes one or several of the following post-treatment steps: A) Annealing: Anneal the molded children's toy using a variable temperature annealing process in a nitrogen atmosphere; B) Coating: Spray paint on the surface of the children's toy; C) Surface treatment: Immerse the children's toy in a plant wax solution and then air dry; the components of the plant wax solution include: rice bran wax, carnauba wax, nano silver particles, dispersant, and ethanol; the mass ratio of rice bran wax, carnauba wax, and nano silver particles is 8 - 10:8 - 10:2; the mass of the dispersant is 2 - 5% of the total mass of rice bran wax, carnauba wax, and nano silver particles; the total mass concentration of rice bran wax and carnauba wax in the plant wax solution is 6 - 8%.

[0058] As a specific implementation manner, water-based environmentally friendly paint is used for coating and electrostatic spraying is adopted.

[0059] Example 1: A preparation method of a children's toy, the steps are: S1: Prepare modified corn starch S11: Compound monomer preparation (1) Raw material preparation: Weigh 60 kg of 2-hydroxyethyl methacrylate (HEMA), 15 kg of silane coupling agent KH-570, and 0.675 kg of iron chloride catalyst; (2) Feeding: Add the weighed HEMA and KH-570 into a 100 L stainless steel multi-functional reaction kettle, start stirring, set the rotation speed to 250 r / min, and stir for 8 min to fully mix the two monomers evenly; (3) Adding catalyst: Slowly add the weighed iron chloride catalyst into the reaction vessel, maintain a rotation speed of 250 r / min, and continue stirring for 8 min to ensure that the catalyst is evenly dispersed in the monomer mixture; (4) Controlling reaction temperature: Start the heating device, gradually increase the temperature of the reaction system to 55 °C at a heating rate of 2 °C / min, and keep this temperature stable through the temperature control device; (5) Conducting the reaction: At 55 °C, let HEMA and KH-570 react under the action of the iron chloride catalyst for 2.5 h. Stir continuously throughout the reaction to promote full contact of the reactants; (6) Ending the reaction: After the reaction time ends, turn off the heating device, stop stirring, and let the reaction system cool naturally to room temperature to obtain the composite monomer for standby; S12: Initiator compounding (1) Weighing the initiators: Weigh 2.25 kg of potassium persulfate (KPS) and 2.25 kg of azobisisobutyronitrile (AIBN) respectively; (2) Adding the solvent: Add 18 kg of water to a 50 L stainless steel multi-functional reaction kettle; (3) Adding the initiators: Start stirring, set the rotation speed to 250 r / min. Under stirring conditions, first slowly add KPS into the water, stir until it is completely dissolved, then add AIBN dissolved in a small amount of ethanol, and continue stirring for 10 min to make the initiators fully mixed and uniform; (4) Introducing nitrogen: Introduce nitrogen into the reaction vessel to remove the air in the vessel. The compounding process is carried out at room temperature, and the stirring time is 45 min. The whole process is carried out under nitrogen protection to prepare the initiator solution for standby.

[0060] S13: Starch dispersion Add 1500 kg of water to a 3000 L stainless steel multi-functional reaction kettle, start stirring, add 300 kg of corn starch under stirring, and at the same time introduce nitrogen into the reaction vessel to prepare a starch suspension; Heat up to 65 °C, control the stirring speed at 300 rpm, and stir for 50 min to make the starch fully dispersed.

[0061] S14: Grafting reaction Add the prepared composite monomer to the starch suspension and stir evenly; Slowly drip the initiator solution using a peristaltic pump, and control the dripping time within 30 min; After the dripping is completed, heat up to 80 °C at a heating rate of 4 °C / min and react for 3.5 h. Keep the stirring speed at 400 rpm during the reaction; The whole process is carried out under nitrogen protection.

[0062] S15: Product separation and washing After the reaction is completed, cool the reaction solution to room temperature, pour it into a centrifuge, centrifuge at 7000 rpm for 35 min, and collect the precipitate; wash the precipitate with deionized water repeatedly 3 times to remove the residual initiator and impurities.

[0063] S16: Drying and Crushing Place the washed precipitate in a vacuum drying oven, set the vacuum degree to -0.1 MPa, dry at 52 °C until constant weight, crush the crude product with a crusher, and pass through an 80-mesh sieve to obtain modified corn starch.

[0064] S2: Preparation of Modified PBAT S21: Nano-SiO 2 Surface Modification (1) Inject 42 kg of n-hexane into a 100 L stainless steel multi-functional reaction kettle with a reflux condenser; introduce nitrogen, start stirring, adjust the rotation speed to 500 r / min, and stir for 7 min to fully mix the n-hexane; (2) Add the amino silane coupling agent KH-550, reduce the stirring speed to 350 r / min, and stir for 15 min until uniform; (3) Add dibutyltin dilaurate (DBTDL), continue stirring for 5 min to fully mix the catalyst and the coupling agent; (4) Slowly add nano-SiO 2 , increase the stirring speed to 450 r / min, and stir for 30 min to ensure uniform dispersion in the reaction system; (5) Raise the temperature to 85 °C, maintain the reflux reaction for 2.5 h, and keep the stirring speed at 250 r / min to allow the reaction system to react fully; (6) After the reaction is completed, cool the reaction system to room temperature, pour it into a centrifuge, with a rotation speed of 7000 r / min and a time of 20 min; wash 3 times with n-hexane to remove impurities; (7) Place the washed nano-SiO 2 in a vacuum drying oven at 55 °C, set the vacuum degree to -0.1 MPa, and dry for 8 h to obtain coupling agent-modified nano-SiO 2 for standby.

[0065] S22: Melt Grafting and Composite (1) Premixing: First, put 500 kg of PBAT particles (THJS-5801 from Xinjiang Blue Mountain Tunhe Yinchuang Co., Ltd.) weighed into a high-speed mixer, then add coupling agent-modified nano-SiO 2 , stir for 15 min, then add 20 kg of maleic anhydride (MAH) and 2.25 kg of tert-butyl peroxybenzoate, continue stirring for 15 min, and control the rotation speed at 500 r / min to ensure preliminary uniform dispersion of each component; (2)Melt grafting: The premix is melt-extruded through a twin-screw extruder with a screw length-diameter ratio of 35:1, and each heating zone is set separately; the feeding section is at 145°C, the melting section is at 165°C, the homogenization section is at 175°C, and the die head is at 180°C; the screw speed is 220 r / min; (3)Cooling and pelletizing: The extruded strip is cooled and shaped in a water-cooling tank, and the pellet size is 3 - 5 mm, followed by hot air drying to obtain modified PBAT.

[0066] S3: Preparation of compatibilizer S31: Preparation of PEG-grafted corn starch (1)Starch dissolution: Inject 600 kg of deionized water into a 1000 L stainless steel multi-functional reaction kettle, then add 100 kg of corn starch (purity ≥ 98%, moisture content ≤ 8%. Pass through a 100-mesh sieve), raise the temperature to 55°C, and stir at a speed of 300 r / min for 70 min until the starch is completely dissolved to form a uniform semi-transparent solution; (2)Addition of PEG and initiator: Add 40 kg of PEG (Wanhua Chemical PEG2000) and 1.12 kg of potassium persulfate-sodium bisulfite initiator (0.75 kg of potassium persulfate, 0.37 kg of sodium bisulfite) into the reaction kettle in sequence, introduce nitrogen into the reaction system to discharge the air in the reaction system, and continue stirring for 25 min to fully mix each component; (3)Heating reaction: Set the heating temperature to 70°C, keep the stirring speed at 400 r / min, and react for 8 h; (4)Product separation and washing: After the reaction is completed, cool the reaction solution to room temperature, pour it into a centrifuge, centrifuge at 7000 rpm for 25 min, and collect the precipitate; wash the precipitate 3 times with deionized water to remove the residual initiator and impurities; (5)Drying and pulverizing: Place the washed precipitate in a vacuum drying oven, set the vacuum degree to -0.1 MPa, dry it at 50°C to constant weight, pulverize the crude product with a pulverizer, and pass through a 100-mesh sieve to obtain PEG-grafted corn starch.

[0067] S32: Copolymerization reaction (1)Material mixing: Inject 700 kg of ethanol into a 1500 L stainless steel multi-functional reaction kettle, add 100 kg of PEG-grafted corn starch and 75 kg of PBS (TH803S of Lanshan Tunhe Yinchuang Company) into the reaction kettle, and stir at a speed of 300 r / min for 40 min to fully mix the materials evenly; (2)Addition of catalyst: Add 1.4 kg of stannous octoate into the reactor, introduce nitrogen into the reaction system to discharge the air in the reaction system, and continue stirring for 20 min to fully mix each component; (3)Heating reaction: The heating temperature is set at 130 °C, the stirring speed is maintained at 400 r / min, and the reaction is carried out for 8 h under nitrogen protection throughout the process; (4)Product separation and washing: After the reaction is completed, the reaction solution is cooled to room temperature, poured into a centrifuge, centrifuged at 8000 rpm for 25 min, and the precipitate is collected; the precipitate is washed twice with methanol to remove residual initiator and impurities; (5)Drying: The washed product is placed in a vacuum drying oven, the vacuum degree is set at -0.1 MPa, and the temperature is set at 50 °C for drying to constant weight to obtain the compatibilizer.

[0068] S4: Preparation of degradable starch-based toy materials: S41: Raw material pretreatment: (1)Drying treatment of basic materials: The modified corn starch and modified PBAT are placed in a drying oven and dried at 90 °C for 5 h to remove moisture; (2)Pretreatment of colorants: Pretreatment of Pigment Red 254: Weigh 30 kg of Pigment Red 254, 2 kg of silane coupling agent KH-570, and 100 kg of ethanol; pour the ethanol into a clean reaction vessel, slowly add the silane coupling agent, and stir for 20 min until fully dissolved; gradually add Pigment Red 254 to the above solution and stir evenly while adding; stir the reaction mixture at a high-speed stirrer speed of 1000 r / min for 1.5 h; filter the reaction mixture, collect the filter cake, and wash the filter cake twice with ethanol; dry the washed filter cake in a vacuum drying oven at 50 °C for 7 h to obtain pretreated Pigment Red 254; Pretreatment of titanium dioxide: Weigh 30 kg of titanium dioxide, 1.5 kg of stearic acid, and 70 kg of ethyl acetate; add ethyl acetate to the reaction kettle and start stirring, add stearic acid, heat up to 50 °C, and stir for 35 min until completely dissolved; slowly add titanium dioxide, control the speed to prevent caking, keep at 50 °C, and continue stirring for 2 h; stop heating, cool naturally to room temperature and then filter, collect the filtered solid matter filter cake, and wash it twice with ethyl acetate; dry the washed filter cake in a vacuum drying oven at 50 °C for 4 h to obtain pretreated titanium dioxide.

[0069] S42: Premixing of raw materials: First, add 65 kg of modified corn starch to facilitate the subsequent uniform mixing with other components. Then, add 35 kg of modified PBAT and mix it preliminarily and evenly with the modified corn starch. Next, add 7 kg of compatibilizer to promote the combination of modified corn starch and PBAT. Then, add 1.2 kg of nucleating agent (cellulose nanocrystals) to help improve the crystallization performance of the material. After that, add 0.8 kg of antioxidant (BASF Irganox B215 from BASF, Germany) to prevent the material from oxidizing during processing and use. Then, add 0.6 kg of antistatic agent quaternized chitosan (2-hydroxypropyltrimethylammonium chloride chitosan, HACC from Liangshan Tianhua Auxiliary Factory) to improve the antistatic performance of the material. Finally, add 0.7 kg of colorant (the mass ratio of pigment red 254 to titanium dioxide is 2:1). Set the stirring speed to 600 r / min, and after each component material is added, stir for 12 min to make it evenly dispersed in the system to form a premix.

[0070] S43: Twin-screw extruder melt compounding Extrude the premix using a twin-screw extruder. The long-diameter ratio of the twin-screw extruder is 40:1, with multiple temperature zones set. The feeding section is at 125 °C, the melting section is at 145 °C, the homogenization section is at 160 °C, and the die head is at 165 °C. The screw speed is 250 r / min. The strip-shaped composite material extruded from the die head is made into 3 - 5 mm granular material through cooling, pelletizing, and hot air drying to obtain a degradable starch-based toy material.

[0071] S5: Preparation of children's toys S51: Injection molding (1) Mold installation: Take the small shovel mold for children's toys and install it on the mold mounting plate of the injection molding machine. (2) Temperature setting: According to the characteristics of the composite material and the requirements of the mold, the temperature gradually increases from the hopper to the nozzle. The first section is at 150 °C, the second section is at 160 °C, the third section is at 170 °C, and the nozzle is at 180 °C. Use zone temperature control for uniform heating and melting to improve the molding quality of the toy. The mold temperature is set at 50 °C, and the cooling system of the mold uses circulating water cooling with a water temperature of 15 °C. (3) Injection molding parameter setting: The injection pressure is 90 MPa, the holding pressure is 70% of the injection pressure, the holding time is 4 s, the cooling time is 15 s, and then take out the small shovel for children's toys.

[0072] S52: Post-treatment (1) Annealing treatment: Put the injection-molded small shovel toy into an annealing furnace and adopt a variable-temperature annealing process. First, raise the temperature from room temperature to 90 °C and hold at this temperature for 1 h to initially release the internal stress of the toy. Then, lower the temperature to 70 °C and hold for 1 h to further eliminate the residual stress. Finally, cool naturally to room temperature. (2) Painting: Electrostatic spraying is used to spray water-based environmentally friendly paint (Henggeili water-based toy paint, model ZWA-45XX, produced by Fujian Zhengbang Environmental Protection Technology Materials Co., Ltd.) on the surface of the toy after annealing. (3) Surface treatment: First, prepare a vegetable wax solution: put rice bran wax and carnauba wax into a container filled with ethanol, place it in a constant temperature water bath at 70°C, and stir at a speed of 250 r / min until it is completely dissolved; then add nanosilver particles and dispersant Tween-80, increase the stirring speed to 350 r / min, and stir for 30 min to evenly disperse the nanosilver particles; the mass ratio of rice bran wax, carnauba wax and nanosilver particles is 9:9:2; the mass of Tween-80 is 2% of the total mass of rice bran wax, carnauba wax and nanosilver particles; finally, add ethanol to make the total mass concentration of rice bran wax and carnauba wax in the vegetable wax solution 7%; then soak the toy in the vegetable wax solution at a temperature of 75°C for 3 min, and then take it out and dry it; the toy production steps are completed.

[0073] Embodiment 2: The difference between Example 2 and Example 1 is that the modified starch is a mixed modified starch of modified corn starch and modified wheat starch, the preparation method of the modified corn starch is the same as that in Example 1, and the preparation method of the modified wheat starch is: S1: Preparation of modified wheat starch S11: Compound Monomer Preparation (1) Raw material preparation: weigh 38.64 kg of hydroxyethyl methacrylate (HEMA), 9.66 kg of silane coupling agent KH-570, and 0.483 kg of ferric chloride catalyst; (2) Adding materials: Add the weighed HEMA and KH-570 into a 100L stainless steel multifunctional reactor, start stirring, set the speed to 280r / min, and stir for 7 minutes to fully mix the two monomers; (3) Adding catalyst: slowly add the weighed ferric chloride catalyst into the reaction vessel, maintain the speed at 280 r / min, and continue stirring for 7 min to ensure that the catalyst is evenly dispersed in the monomer mixture; (4) Reaction temperature control: Start the heating device and gradually increase the temperature of the reaction system to 55°C at a heating rate of 2°C / min, and keep the temperature stable using the temperature control device; (5) Reaction: HEMA and KH-570 were reacted under the action of ferric chloride catalyst at 55°C for 2.5 h. Stirring was continued throughout the reaction to ensure full contact between the reactants. (6) End of reaction: After the reaction time is over, turn off the heating device, stop stirring, and let the reaction system cool naturally to room temperature to obtain the composite monomer for later use; S12: Initiator compounding (1) Weigh the initiators: Weigh 1.47 kg of potassium persulfate (KPS) and 1.47 kg of azobisisobutyronitrile (AIBN) respectively; (2) Add the solvent: Add 11.76 kg of water to a 50 L stainless steel multi-functional reaction kettle; (3) Add the initiators: Turn on the stirrer, set the rotation speed to 250 r / min. Under stirring conditions, first slowly add KPS to the water and stir until it is completely dissolved. Then add AIBN dissolved in a small amount of ethanol and continue stirring for 10 min to make the initiators fully mixed and uniform; (4) Introduce nitrogen: Introduce nitrogen into the reaction vessel to remove the air in the vessel. The compounding process is carried out at room temperature, and the stirring time is 45 min. The whole process is carried out under nitrogen protection to prepare the initiator solution for standby.

[0074] S13: Starch dispersion Add 1050 kg of water to a 2000 L stainless steel multi-functional reaction kettle, turn on the stirrer, and add 210 kg of wheat starch under stirring. At the same time, introduce nitrogen into the reaction vessel to prepare a starch suspension; Heat up to 65 °C, control the stirring speed at 300 rpm, and stir for 50 min to make the starch fully dispersed.

[0075] S14: Grafting reaction Add the compounded monomer for standby to the starch suspension and stir evenly; Slowly drip the initiator solution using a peristaltic pump, and control the dripping time within 30 min; After the dripping is completed, heat up to 80 °C at a heating rate of 4 °C / min and react for 3.5 h. Keep the stirring speed at 400 rpm during the reaction process; The whole process is carried out under nitrogen protection.

[0076] S15: Product separation and washing After the reaction is completed, cool the reaction solution to room temperature, pour it into a centrifuge, centrifuge at 7000 rpm for 35 min, and collect the precipitate; Wash the precipitate with deionized water repeatedly for 3 times to remove the residual initiators and impurities.

[0077] S16: Drying and grinding Place the washed precipitate in a vacuum drying oven, set the vacuum degree to -0.1 MPa, dry it to a constant weight at 52 °C, grind the crude product with a grinder, and pass through an 80-mesh sieve to obtain the modified wheat starch.

[0078] The raw material premixing method for preparing the degradable starch-based toy material in S4 is as follows: S42: Raw material premixing: First, add 35 kg of modified corn starch and 35 kg of modified wheat starch. Then, add 30 kg of modified PBAT and mix it preliminarily and evenly with the modified starches. Next, add 9 kg of compatibilizer. Then, add 1.3 kg of nucleating agent (cellulose nanocrystals). After that, add 0.9 kg of antioxidant (BASF Irganox B215 from BASF, Germany) to prevent the material from oxidizing during processing and use. Then, add 0.6 kg of antistatic agent quaternized chitosan (2-hydroxypropyltrimethylammonium chloride chitosan, HACC from Liangshan Tianhua Auxiliary Factory) to improve the antistatic performance of the material. Finally, add 0.7 kg of colorant (the mass ratio of pigment red 254 to titanium dioxide is 2:1). Set the stirring speed to 600 r / min. After each component material is added, stir for 12 min to make them evenly dispersed in the system and form a premix. The remaining steps are the same as those in Example 1.

[0079] Example 3: The difference between Example 3 and Example 1 is that the modified starch uses a mixed modified starch of modified corn starch, modified wheat starch, and modified rice starch, and the finally produced product is a children's toy yellow duck. The preparation method of the modified corn starch is the same as that in Example 1, the preparation method of the modified wheat starch is the same as that in Example 2, and the preparation method of the modified rice starch is as follows: S1: Preparation of modified rice starch S11: Preparation of composite monomers (1) Raw material preparation: Weigh 41.6 kg of 2-hydroxyethyl methacrylate (HEMA), 10.4 kg of silane coupling agent KH-570, and 0.52 kg of ferric chloride catalyst. (2) Feeding: Add the weighed HEMA and KH-570 into a 100 L stainless steel multi-functional reaction kettle, start stirring, set the rotation speed to 280 r / min, and stir for 7 min to make the two monomers fully mixed and evenly dispersed. (3) Adding the catalyst: Slowly add the weighed ferric chloride catalyst into the reaction vessel, maintain the rotation speed of 280 r / min, and continue stirring for 7 min to ensure that the catalyst is evenly dispersed in the monomer mixture. (4) Reaction temperature control: Start the heating device and gradually increase the temperature of the reaction system to 55 °C at a heating rate of 2 °C / min, and keep this temperature stable through the temperature control device. (5) Reaction progress: At 55 °C, let HEMA react with KH-570 under the action of ferric chloride catalyst for 2.5 h. Stir continuously throughout the reaction to promote full contact of the reactants. (6)End of reaction: After the reaction time ends, turn off the heating device, stop stirring, and let the reaction system cool naturally to room temperature to obtain the composite monomer for standby. S12: Initiator compounding (1)Weigh the initiators: Weigh 1.4 kg of potassium persulfate (KPS) and 1.4 kg of azobisisobutyronitrile (AIBN) respectively. (2)Add the solvent: Add 11.2 kg of water to a 50 L stainless steel multi-functional reaction kettle. (3)Add the initiators: Turn on the stirring, set the rotation speed to 250 r / min. Under the stirring condition, first slowly add KPS to the water and stir until it is completely dissolved, then add AIBN dissolved in a small amount of ethanol, and continue to stir for 10 min to make the initiators fully mixed and uniform. (4)Introduce nitrogen: Introduce nitrogen into the reaction vessel to remove the air in the vessel. The compounding process is carried out at room temperature, and the stirring time is 45 min. The whole process is carried out under nitrogen protection to prepare the initiator solution for standby.

[0080] S13: Starch dispersion Add 1000 kg of water to a 2000 L stainless steel multi-functional reaction kettle, turn on the stirring, and add 200 kg of rice starch under the stirring state. At the same time, introduce nitrogen into the reaction vessel to prepare a starch suspension; heat up to 65 °C, control the stirring speed at 300 rpm, and stir for 50 min to make the starch fully dispersed.

[0081] S14: Grafting reaction Add the prepared composite monomer to the starch suspension and stir evenly; use a peristaltic pump to slowly drip the initiator solution, and control the dripping time within 30 min; after the dripping is completed, heat up to 80 °C at a heating rate of 4 °C / min and react for 3.5 h. During the reaction process, keep the stirring speed at 400 rpm; the whole process is carried out under nitrogen protection.

[0082] S15: Product separation and washing After the reaction ends, cool the reaction solution to room temperature, pour it into a centrifuge, centrifuge at 7000 rpm for 35 min, and collect the precipitate; wash the precipitate with deionized water repeatedly for 3 times to remove the residual initiators and impurities.

[0083] S16: Drying and pulverizing Place the washed precipitate in a vacuum drying oven, set the vacuum degree to -0.1 MPa, dry it to constant weight at 52 °C, pulverize the crude product with a pulverizer, and pass through an 80-mesh sieve to obtain the modified rice starch.

[0084] S2 and S3 are the same as in Example 1.

[0085] S4: Preparation of Degradable Starch-based Toy Materials: S41: Pretreatment of Raw Materials: (1) Drying Treatment of Basic Materials: Place the modified corn starch, modified wheat starch, modified rice starch, and modified PBAT in a drying oven and dry at 90 °C for 5 h to remove moisture; (2) Pretreatment of Colorants: Pretreatment of Corn Yellow Pigment: First, add 100 kg of ethanol to a reaction kettle and start stirring; then add 4 kg of soy lecithin to the ethanol, heat up to 45 °C, and stir for 35 min until it is completely dissolved; slowly add 30 kg of corn yellow pigment, control the addition speed to avoid caking; keep the temperature at 45 °C and continue stirring for 2.5 h to allow the soy lecithin to fully coat the pigment; homogenize the mixed solution through a high-pressure homogenizer, control the pressure at 20 MPa, and homogenize 2 times; recover most of the ethanol through vacuum distillation, and subject the remaining product to vacuum drying at a temperature of 45 °C, and collect the dried product to obtain the pretreated corn pigment; Pretreatment of Titanium Dioxide: The method is the same as in Example 1.

[0086] S42: Premixing of Raw Materials: First, add 22 kg of modified corn starch, 22 kg of modified wheat starch, and 22 kg of modified rice starch, then add 34 kg of modified PBAT and mix it preliminarily with the modified starch; then add 6 kg of compatibilizer; then add 1.1 kg of nucleating agent (cellulose nanocrystals); then add 0.8 kg of antioxidant (BASF Irganox B215 from BASF, Germany) to prevent the material from oxidizing during processing and use; then add 0.6 kg of antistatic agent quaternized chitosan (2-hydroxypropyltrimethylammonium chloride chitosan from Liangshan Tianhua Auxiliary Factory, HACC) to improve the antistatic performance of the material; finally, add 0.8 kg of colorant (mass ratio of corn yellow pigment to titanium dioxide is 1:1); set the stirring speed at 600 r / min, and stir for 12 min after each component material is added to make it evenly dispersed in the system to form a premix; S43: Melt Compounding by Twin-Screw Extruder Extrude the premix using a twin-screw extruder with a length-diameter ratio of 40:1, multiple temperature zones are set, the feeding section is 125 °C, the melting section is 145 °C, the homogenizing section is 160 °C, the die head is 165 °C, and the screw speed is 250 r / min; the strip-shaped composite material extruded from the die head is made into 3 - 5 mm granular materials through cooling, pelletizing, and hot air drying to obtain the degradable starch-based toy materials.

[0087] S5: Preparation of Children's Toys S51: Blow Molding (1)Mold installation: Take the mold of the children's toy yellow duck and install it on the mold mounting rack of the blow molding machine; (2)Temperature setting: The barrel temperature, the first section is 150 °C, the second section is 160 °C, the third section is 170 °C, and the head is 175 °C; the mold temperature is set at 40 °C; (3)Blow molding: Pass compressed air into the parison through the air blowing system to form the shape of the children's toy yellow duck; the blowing pressure is 0.5 MPa and the blowing time is 4 s; adopt a cooling method combining spray cooling and air cooling. First, spray tiny water mist on the surface of the toy through the spray device to quickly take away a large amount of heat; then, perform air cooling; take out the children's toy yellow duck.

[0088] The post-treatment steps in S52 are the same as those in Example 1.

[0089] Example 4: The difference between Example 4 and Example 3 is that the modified starch is a mixed modified starch of modified corn starch, modified wheat starch, modified rice starch and modified potato-cassava mixed starch; The preparation method of the modified corn starch is the same as that in Example 1, the preparation method of the modified wheat starch is the same as that in Example 2, the preparation method of the modified rice starch is the same as that in Example 3, and the preparation method of the modified potato-cassava mixed starch is as follows: S1: Preparation of modified potato-cassava mixed starch S11: Compound monomer preparation (1)Raw material preparation: Weigh 44.8 kg of 2-hydroxyethyl methacrylate (HEMA), 11.2 kg of silane coupling agent KH-570, and 0.56 kg of ferric chloride catalyst; (2)Feeding: Add the weighed HEMA and KH-570 into a 100 L stainless steel multi-functional reaction kettle, start stirring, set the rotation speed to 260 r / min, and stir for 8 min to fully mix the two monomers evenly; (3)Adding catalyst: Slowly add the weighed ferric chloride catalyst into the reaction vessel, maintain the rotation speed of 260 r / min, and continue stirring for 8 min to ensure that the catalyst is evenly dispersed in the monomer mixture; (4)Reaction temperature control: Start the heating device, gradually increase the temperature of the reaction system to 55 °C at a heating rate of 2 °C / min, and keep the temperature stable through the temperature control device; (5)Reaction progress: At 55 °C, let HEMA react with KH-570 under the action of ferric chloride catalyst for 2.5 h, and keep stirring throughout the reaction to promote full contact of the reactants; (6)Reaction end: After the reaction time ends, turn off the heating device, stop stirring, and let the reaction system cool naturally to room temperature to obtain the compound monomer for standby; S12: Initiator Blending (1) Weigh the initiators: Weigh 1.5 kg of potassium persulfate (KPS) and 1.5 kg of azobisisobutyronitrile (AIBN) respectively; (2) Add the solvent: Add 12 kg of water to a 50 L stainless steel multi-functional reactor; (3) Add the initiators: Start stirring, set the rotation speed to 250 r / min. Under stirring conditions, first slowly add KPS to the water and stir until it is completely dissolved. Then add AIBN dissolved in a small amount of ethanol and continue stirring for 10 min to make the initiators fully mixed and uniform; (4) Introduce nitrogen: Introduce nitrogen into the reaction vessel to remove the air in the vessel. The blending process is carried out at room temperature, and the stirring time is 45 min. The whole process is carried out under nitrogen protection to prepare the initiator solution for standby.

[0090] S13: Starch Dispersion Add 1000 kg of water to a 2000 L stainless steel multi-functional reactor, start stirring, and add 100 kg of potato starch and 100 kg of tapioca starch under stirring. At the same time, introduce nitrogen into the reaction vessel to prepare a starch suspension; Heat up to 65 °C, control the stirring speed at 300 rpm, and stir for 50 min to make the starch fully dispersed.

[0091] S14: Grafting Reaction Add the prepared composite monomer to the starch suspension and stir evenly; Slowly drip the initiator solution using a peristaltic pump, and control the dripping time within 30 min; After dripping, heat up to 80 °C at a heating rate of 4 °C / min and react for 3.5 h. Keep the stirring speed at 400 rpm during the reaction process; The whole process is carried out under nitrogen protection.

[0092] S15: Product Separation and Washing After the reaction is completed, cool the reaction solution to room temperature, pour it into a centrifuge, centrifuge at 8000 rpm for 35 min, and collect the precipitate; Wash the precipitate with deionized water repeatedly for 3 times to remove the residual initiators and impurities.

[0093] S16: Drying and Crushing Place the washed precipitate in a vacuum drying oven, set the vacuum degree to -0.1 MPa, dry it at 50 °C until it reaches a constant weight, crush the crude product with a crusher, and pass it through a 100-mesh sieve to obtain the modified potato-tapioca mixed starch.

[0094] The raw material premixing method for preparing the degradable starch-based toy material in S4 is as follows: S42: Raw material premixing: First, add 15 kg of modified corn starch, 15 kg of modified wheat starch, 15 kg of modified rice starch, and 15 kg of modified potato and cassava mixed starch. Then, add 40 kg of modified PBAT and mix it preliminarily with the modified starch until evenly distributed. Next, add 8 kg of compatibilizer. Then, add 1.4 kg of nucleating agent (cellulose nanocrystals). After that, add 0.7 kg of antioxidant (BASF Irganox B215 from BASF, Germany) to prevent the material from oxidizing during processing and use. Then, add 0.6 kg of antistatic agent quaternized chitosan (2-hydroxypropyltrimethylammonium chloride chitosan from Liangshan Tianhua Auxiliary Factory, HACC) to improve the antistatic performance of the material. Finally, add 0.8 kg of colorant (the mass ratio of corn yellow pigment to titanium dioxide is 1:1). Set the stirring speed to 600 r / min. After adding each component material, stir for 12 min to make them evenly dispersed in the system and form a premix. The remaining steps are the same as those in Example 3.

[0095] Comparative Example 1 (starch is not modified): The difference between Comparative Example 1 and Example 1 is that in S42, unmodified corn starch is mixed with modified PBAT and other raw materials, and the remaining steps are the same as those in Example 1.

[0096] Comparative Example 2 (PBAT is not modified): The difference between Comparative Example 2 and Example 1 is that in S42, unmodified PBAT is mixed with modified corn starch and other raw materials, and the remaining steps are the same as those in Example 1.

[0097] Comparative Example 3 (compatibilizer is not added): The difference between Comparative Example 3 and Example 1 is that in S42, no compatibilizer is added, and the remaining steps are the same as those in Example 1.

[0098] Comparative Example 4 (both starch and PBAT are not modified): The difference between Comparative Example 4 and Example 1 is that in S42, unmodified corn starch and unmodified PBAT are mixed with other raw materials, and the remaining steps are the same as those in Example 1.

[0099] Comparative Example 5 (only starch is modified with HEMA): The difference between Comparative Example 5 and Example 1 is that in S1, 75 kg of HEMA is added to modify corn starch, and no silane coupling agent KH-570 is added, and the remaining steps are the same as those in Example 1.

[0100] Comparative Example 6 (only starch is modified with silane coupling agent): The difference between Comparative Example 6 and Example 1 is that in S1, 75 kg of silane coupling agent KH-570 was added to modify corn starch, and no HEMA was added. The remaining steps were the same as those in Example 1.

[0101] Comparative Example 7 (using PEG-grafted starch as compatibilizer): The difference between Comparative Example 7 and Example 1 is that the PEG-grafted corn starch prepared by S31 was used as the compatibilizer, and no subsequent copolymerization reaction was carried out with PBS; the remaining steps were the same as those in Example 1.

[0102] Comparative Example 8 (PEG in the compatibilizer is not grafted with starch): The difference between Comparative Example 8 and Example 1 is that the preparation method of the compatibilizer in S3 is as follows: (1) Material mixing: Inject 700 kg of ethanol into a 1500 L stainless steel multi-functional reaction kettle, add 100 kg of PEG (Wanhua Chemical PEG2000) and 75 kg of PBS (Blue Mountain Tunhe Yinchuang Company TH803S) into the reaction kettle, and stir at a speed of 300 r / min for 40 min to fully mix the materials evenly; (2) Adding catalyst: Add 1.4 kg of stannous octoate to the reactor, introduce nitrogen into the reaction system, discharge the air in the reaction system, and continue stirring for 20 min to fully mix each component; (3) Heating reaction: Set the heating temperature to 130 °C, keep the stirring speed at 400 r / min, and react for 8 h, which is carried out under nitrogen protection throughout the process; (4) Product separation and washing: After the reaction is completed, cool the reaction solution to room temperature, pour it into a centrifuge, centrifuge at 8000 rpm for 25 min, and collect the precipitate; wash the precipitate with methanol twice to remove residual initiator and impurities; (5) Drying: Put the washed product into a vacuum drying oven, set the vacuum degree to -0.1 MPa, and set the temperature to 50 °C to dry to constant weight to obtain the compatibilizer; The remaining steps were the same as those in Example 1.

[0103] The mechanical properties of the children's toy products prepared in the above examples and comparative examples were tested, and the results are shown in Table 1.

[0104] Among them, the tensile strength, elongation at break, elastic modulus, and Poisson's ratio were tested according to the method of GB / T 1040.2-2022; the notch impact strength was tested according to the method of GB / T 1843-2008.

[0105] Table 1: Test results of mechanical properties of children's toys

[0106] As can be seen from Table 1, the products prepared by the method of the present invention in Examples 1 to 4 have excellent mechanical properties. The Poisson's ratios of the samples in the examples and comparative examples are all in the range of 0.4 - 0.5, with no obvious difference. The Poisson's ratio reflects the lateral deformation characteristics of the material, indicating that the starch and PBAT are unmodified and no compatibilizer is added, which mainly affects the interfacial bonding and overall mechanical properties and has no significant effect on the Poisson's ratio.

[0107] In Comparative Example 1, the starch is not modified. There are many intermolecular hydrogen bonds and high crystallinity in the unmodified starch, which is difficult to be uniformly dispersed when blended with modified PBAT, and the interfacial bonding is weak. All the mechanical properties of the product are significantly lower than those in Example 1.

[0108] In Comparative Example 2, PBAT is not modified. The molecular chain arrangement and crystallization of unmodified PBAT are not ideal, and the reinforcing effect when blended with modified starch is weak. When stretched, the PBAT molecular chains are easy to slide relative to each other, resulting in low tensile strength; unmodified PBAT itself has good flexibility. After being blended with modified starch, during the deformation process, the flexibility of the PBAT phase can buffer the stress to a certain extent, so its elongation at break is improved compared with that in the examples.

[0109] In Comparative Example 3, no compatibilizer is added, and the starch and PBAT are phase-separated. When stretched, the interfacial stress transfer is not smooth, resulting in early failure and low tensile strength; the phase separation forms defects inside the material, reducing the elastic modulus; when impacted, the energy is difficult to transfer and dissipate, and the notch impact strength decreases.

[0110] In Comparative Example 4, neither the starch nor the PBAT is modified. Due to the poor synergistic effect between the unmodified starch and the unmodified PBAT, they cannot coordinate deformation when stressed, resulting in a decrease in the ability of the blend material to resist elastic deformation and a reduction in the elastic modulus; during the impact process, due to the weak interfacial bonding force between the starch and the PBAT phases, the stress is difficult to be effectively transferred and dissipated between the two phases, and the impact energy cannot be fully absorbed, resulting in a decrease in the notch impact strength.

[0111] In Comparative Example 5, only HEMA is used to modify the starch. Due to the lack of KH-570 and only relying on HEMA grafting, the degree of cross-linking between starch molecules will decrease, resulting in a decline in the mechanical properties of the material. KH-570 has a special chemical structure. One end can react with groups such as hydroxyl groups on the starch surface, and the other end can interact with other polymer molecules. When KH-570 is not used, when the modified starch is compounded with the modified PBAT material, the interfacial bonding force weakens, resulting in a reduction in the overall impact resistance and tensile properties of the composite material.

[0112] In Comparative Example 6, only silane coupling agent KH-570 was used to modify starch. Due to the lack of HEMA, the flexibility of the modified starch molecular chain was insufficient. HEMA has good flexibility and hydrophilicity and can introduce flexible chain segments into the starch molecular chain, resulting in a decrease in the tensile strength of the material. HEMA helps to improve the compatibility between the modified starch and PBAT. When only KH-570 was used, during the compounding process with PBAT, the interfacial bonding between the two was not tight enough, leading to a decline in the overall performance of the composite material and the toy being prone to cracking.

[0113] In Comparative Example 7, PEG-grafted starch was used as a compatibilizer without copolymerizing it with PBS. PEG-grafted starch only has hydrophilic starch segments and PEG segments and lacks the hydrophobic segments of PBS. In the composite system of the modified starch and the modified PBAT, it is difficult to establish an effective bridge between the hydrophobic modified PBAT and the modified plant starch relying solely on PEG-grafted starch. Moreover, PBS has good flexibility. Without the PBS segments, the toughness of the material decreases, resulting in a decline in mechanical properties such as tensile strength and impact strength, and the toy being prone to cracks, affecting the overall performance of the material.

[0114] In the compatibilizer of Comparative Example 8, PEG was not grafted with starch but directly copolymerized with PBS. The copolymer product of PEG and PBS did not undergo a grafting process with starch, making it difficult to form an effective connection bridge between starch and PBAT. Starch is a polysaccharide polymer, and PBAT is a polyester polymer, with a large polarity difference between the two. The originally designed PEG-grafted starch uses its similar structure to the modified starch and the flexible segments of PEG to improve its compatibility with PBAT. Without this grafting process, the copolymer product of PEG and PBS is difficult to combine well with the modified starch and the modified PBAT, resulting in a weakened interfacial bonding force between the modified plant starch and the modified PBAT, a decline in the mechanical properties of the material, a reduction in tensile strength, toughness, etc., and affecting the quality of the material as a children's toy material.

[0115] 1. GB6675.1-2014 "Toy Safety - Part 1: Basic Specifications": (1) Safety requirements: Requirements that toys and materials designed for children to play with should not cause any harm to children. Manufacturing should avoid producing sharp edges, the risk of small parts causing choking by swallowing, and toys should not contain harmful substances, etc.

[0116] (2) Specific safety requirements: Limitation requirements for plasticizers.

[0117] Referring to the test idea of GB / T 1733-1993, the toy specimens obtained in Example 1 and Example 3 were immersed in water for 12 h, the toy material powder was scraped off with a blade, and the phthalate plasticizer content in the product was tested by gas chromatography-mass spectrometry (GC-MS). The results are shown in Tables 2 and 3.

[0118] Table 2: Test Results of Phthalate Plasticizer Content in Example 1

[0119] Table 3: Test Results of Phthalate Plasticizer Content in Example 3

[0120] As can be seen from Tables 2 and 3, for the detection of six phthalic acid substances in the present invention, the result data of each test are not detected, and the corresponding limit value is 0.1% / mg. This indicates that the content of the above six phthalate ester substances in the samples of the present invention is extremely low, far lower than the specified limit value, meeting the safety requirements of children's toys.

[0121] 2. GB6675.2-2014 "Toy Safety - Part 2: Mechanical and Physical Properties": (1) Material requirements: Visually inspect that the toys and all materials used in the toys should be clean and pollution-free.

[0122] (2) Small parts regulations: Children's toys should not contain small parts and should not have sharp edges before and after abuse testing.

[0123] (3) Protrusion requirements: Rigid parts on the toys should not pose a risk of stabbing before and after abuse testing.

[0124] Drop tests were conducted on the toys obtained in Example 1 and Example 3 of the present invention. The results are shown in Tables 4 and 5. The test method is as follows: When the drop height is 93 ± 5 cm, 4 drops are carried out. After the test, the product appearance has no fractures, no sharp corners, and no small objects, and the result is qualified; when the drop height is increased to 138 ± 5 cm, after 10 drops, the product has no fractures, and the result is qualified; at a drop height of 150 ± 5 cm, 5 drops are carried out, and the product has no fractures, and the result is qualified.

[0125] Table 4: Drop Test Results of Example 1

[0126] Table 5: Drop Test Results of Example 3

[0127] As can be seen from Table 4 and Table 5, in the drop tests at different heights for the products prepared by the present invention, no unqualified situations such as cracking, damage, and deformation occurred, indicating that the products have good drop resistance and structural stability.

[0128] 3. GB6675.3-2014 "Toy Safety - Part 3: Flammability": The degradable starch-based toy material in the present invention is not a flammable material, and there is no flammability risk for the children's toys manufactured, so no flammability test is required.

[0129] 4. GB6675.4-2014 "Toy Safety - Part 4: Migration of Certain Elements": Referring to the test idea in GB / T 1733-1993, the toy specimens prepared in Example 1 and Example 3 of the present invention were immersed in water for 12 h, the material powder of the toy spatula was scraped off with a blade, and the content of specific heavy metal elements was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). The results are shown in Table 6 and Table 7.

[0130] Table 6: Test Results of Heavy Metal Elements in Example 1

[0131] Table 7: Test Results of Heavy Metal Elements in Example 3

[0132] As can be seen from Table 6 and Table 7, the content of the above heavy metal elements in the products of the present invention is extremely low, far lower than the specified limit standards, meeting the safety requirements for children's toys.

[0133] 5. Referring to GB / T 41010 - 2021 for biodegradability performance, an experiment on the compost degradation performance of the product obtained in Example 1 of the present invention was carried out. The specific experimental methods and conditions are shown in Table 8, and the experimental results are shown in Table 9.

[0134] Table 8: Compost Degradation Experimental Conditions

[0135] Table 9: Compost Degradation Experimental Results

[0136] As can be seen from Table 8 and Table 9, in the 90-day compost experiment for the products of the present invention, the degradation rate reached more than 63%, and all environmental parameters during the composting process were controlled within the standard requirements. This shows that the degradation performance of the materials in the present invention meets the requirements of GB / T 41010 - 2021 and has good biodegradation characteristics.

[0137] The two toys in the present invention all passed the tests in Parts 1, 1, 3, and 4 of the national standard for children's toys GB6675-2014. This fully demonstrates that the toys made of the materials in the present invention perform excellently in terms of safety, physical properties, etc., meet the safety requirements of children's toys, and at the same time achieve the environmental protection goal.

[0138] The above specific embodiments are only the preferred embodiments of the present invention, and are only used to illustrate the technical solutions of the present invention, and are not used to limit the present invention. The innovation of the present invention lies in the uniqueness of the idea of using plant starch as the material for manufacturing toys, which is safe, environmentally friendly and biodegradable, and replaces traditional petroleum-based plastic toys. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention. In summary, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A degradable starch-based toy material, characterized in that: The raw materials include base material and compatibilizer; The matrix material comprises modified plant starch and modified PBAT in a mass ratio of 60-70:30-40; The modified plant starch is plant starch grafted with hydroxyethyl methacrylate and silane coupling agent KH-570; The modified PBAT is prepared by mixing and melt-extruding PBAT, maleic anhydride and coupling agent-modified nano-SiO2; the mass of maleic anhydride and coupling agent-modified nano-SiO2 is 2-5% of the mass of PBAT; The compatibilizer is a block copolymer of PEG grafted plant starch and PBS; The mass of the compatibilizer is 5-10% of the total mass of the base material.

2. The degradable starch-based toy material according to claim 1, characterized in that: When hydroxyethyl methacrylate and silane coupling agent KH-570 are used for polar grafting of plant starch, the mass ratio of hydroxyethyl methacrylate and silane coupling agent KH-570 is 3-5:1; the total mass of hydroxyethyl methacrylate and silane coupling agent KH-570 is 20-30% of the mass of plant starch.

3. The degradable starch-based toy material according to claim 1, characterized in that: The mass of PBS in the compatibilizer is 60-100% of the mass of PEG grafted plant starch; in the PEG grafted plant starch, the mass of PEG is 30-50% of the mass of the plant starch.

4. The degradable starch-based toy material according to claim 1, 2 or 3, characterized in that: The plant starch is one or more of corn starch, wheat starch, rice starch, potato starch and cassava starch.

5. The degradable starch-based toy material according to claim 1, characterized in that: The raw materials also include nucleating agent, antioxidant, antistatic agent and colorant; the mass of the nucleating agent is 1-2% of the total mass of the base material, the mass of the antioxidant is 0.5-1.5% of the total mass of the base material, the mass of the antistatic agent is 0.2-2% of the total mass of the base material, and the mass of the colorant is 0.1-2% of the total mass of the base material.

6. A method for preparing a degradable starch-based toy material as claimed in any one of claims 1 to 5, characterized in that the steps include: (1) Grafting plant starch with hydroxyethyl methacrylate and silane coupling agent KH-570 to obtain modified plant starch; (2) reacting an aminosilane coupling agent with nano-SiO2 to obtain coupling agent-modified nano-SiO2; (3) Mixing PBAT, maleic anhydride and coupling agent-modified nano-SiO2 and melt-extruding to obtain modified PBAT; (4) firstly subjecting PEG to a plant starch for a grafting reaction to obtain a PEG-grafted plant starch; then subjecting the PEG-grafted plant starch to a copolymerization reaction with PBS to obtain a compatibilizer; (5) After mixing all the raw materials, extruding and granulating them to obtain the degradable starch-based toy material.

7. The method for preparing the degradable starch-based toy material according to claim 6, characterized in that: In step (1), the grafting reaction of plant starch with hydroxyethyl methacrylate and silane coupling agent KH-570 is carried out in a solvent under the action of a catalyst and an initiator; the catalyst is ferric chloride, the mass of which is 0.5-1.5% of the total mass of hydroxyethyl methacrylate and silane coupling agent KH-570; the initiator is KPS and AIBN in a mass ratio of 0.8-1.2:1, and the total mass of the initiator is 1-2% of the mass of the plant starch; the solvent is water, and the mass ratio of water to plant starch is 4-6:1; In step (2), the reaction of the aminosilane coupling agent and nano-SiO2 is carried out in a solvent under the action of a catalyst; the mass ratio of the aminosilane coupling agent to the nano-SiO2 is 4-6:1; the catalyst is dibutyltin dilaurate, the mass of which is 1-2% of the mass of the aminosilane coupling agent; the solvent is n-hexane, the mass of which is 5-10 times that of the aminosilane coupling agent; In step (3), during melt extrusion, an initiator, tert-butyl peroxybenzoate, is added in an amount of 0.1 to 1% of the mass of PBAT; In step (4), the grafting reaction of PEG and plant starch is carried out in a solvent under the action of an initiator; the initiator is potassium persulfate and sodium bisulfite in a mass ratio of 2 to 3:1, and the total mass of the initiator is 0.5 to 1% of the total mass of PEG and plant starch; the solvent is water, and the mass is 5 to 8 times the mass of the plant starch; In step (4), the copolymerization reaction of PEG grafted plant starch and PBS is carried out in a solvent under the action of a catalyst; the catalyst is stannous octoate, and its mass is 0.5-1% of the total mass of PEG grafted plant starch and PBS; the solvent is ethanol, and its mass is 3-5 times of the total mass of PEG grafted plant starch and PBS.

8. A children's toy, characterized in that: Made of the degradable starch-based toy material as described in any one of claims 1 to 5.

9. A method for preparing a children's toy as claimed in claim 8, characterized in that the step comprises: injection molding or blow molding the degradable starch-based toy material to obtain the children's toy.

10. The method for preparing a children's toy according to claim 9, characterized in that: After injection molding or blow molding, one or more of the following post-processing steps may also be included: A) Annealing: In a nitrogen atmosphere, the molded children's toys are annealed using a variable temperature annealing process; B) Painting: spraying paint on the surface of children's toys; C) Surface treatment: soak the children's toys in a vegetable wax solution and then dry them; The components of the plant wax solution include: rice bran wax, carnauba wax, nano-silver particles, dispersant and ethanol; the mass ratio of rice bran wax, carnauba wax and nano-silver particles is 8-10:8-10:2; the mass of the dispersant is 2-5% of the total mass of the rice bran wax, carnauba wax and nano-silver particles; the total mass concentration of rice bran wax and carnauba wax in the plant wax solution is 6-8%.

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