A biodegradable hot melt adhesive based on castor oil and rosin resin and its preparation process

Abstract

The present invention relates to the field of hot melt adhesives, and discloses a biodegradable hot melt adhesive based on castor oil and rosin resin and its preparation process. The biodegradable hot melt adhesive includes: EVA resin, modified castor oil, rosin resin, modified additive, lubricant, antioxidant; the modified castor oil is prepared by crosslinking castor oil with isophorone diisocyanate, and reacting lignin and 1,4-butanediol with isocyanate groups; the modified additive is prepared by grafting aminated cage-like silsesquioxane with coated aluminum hydroxide, and further grafting with SBS-g-MAH, wherein the coated aluminum hydroxide is prepared by depositing polydopamine on the surface of aluminum hydroxide. By adding the modified castor oil and the modified additive, the present invention improves the tensile performance and bonding performance of the hot melt adhesive, and at the same time can improve the flame retardant performance and high and low temperature resistance of the hot melt adhesive.

Description

Technical Field

[0001] The present invention belongs to the technical field of hot melt adhesives, and particularly relates to a biodegradable hot melt adhesive based on castor oil and rosin resin and a preparation process thereof. Background Art

[0002] A hot melt adhesive refers to an adhesive that is solid at room temperature, becomes liquid after heating and melting, and can complete bonding within a few seconds after being coated, wetted on the adherend, and then pressed and cooled. The preparation of hot melt adhesives usually uses thermoplastic resins as the matrix, supplemented with components such as tackifiers, plasticizers, antioxidants, etc., and melts into a viscous flow state when heated, can wet the processing surface, and after leaving the heat source, cools and solidifies in a very short time, without a drying process, with low energy consumption, convenient operation, can be used on high-speed continuous production lines, can solve the problem of difficult adhesion of some materials, and improve production efficiency. At present, as a convenient-to-use type of adhesive, hot melt adhesives have become commonly used adhesives in various industries in modern society due to their excellent performance and convenient sizing.

[0003] EVA hot melt adhesives are known as environmentally friendly adhesives due to their good processing fluidity, non-toxicity, low price, convenient use, etc., and are widely used in fields such as book binding, wood processing, and sealants. Under the background of "dual carbon", preparing green and environmentally friendly, excellent-performance bio-based adhesives from renewable and environmentally friendly biomass raw materials meets the development requirements of economic green transformation and ecological civilization construction. Among them, natural renewable resources represented by vegetable oil esters have the potential advantage of synthesizing bio-based polymer materials. However, due to the performance defect of easy hydrolysis of vegetable oils themselves, the corresponding synthetic materials are insufficient in weather resistance, thermal stability, and mechanical properties. In addition, existing EVA hot melt adhesives have disadvantages such as flammability, low bonding strength, poor mechanical properties, and poor high and low temperature resistance. It is easy to shrink at low temperatures, resulting in poor bonding strength of EVA-based hot melt adhesives at low temperatures. At high temperatures, due to the increase in temperature, the movement of EVA molecular segments in the system intensifies, and obvious slippage exists between molecules, resulting in a rapid decrease in the bonding strength of the hot melt adhesive, showing poor peel strength, which severely limits its application range. Summary of the Invention

[0004] To solve the deficiencies mentioned in the above background art, the purpose of the present invention is to provide a biodegradable hot melt adhesive based on castor oil and rosin resin and a preparation process thereof. By blending and kneading EVA resin, modified castor oil, rosin resin, modified additives, lubricants, and antioxidants in a kneader, a biodegradable hot melt adhesive based on castor oil and rosin resin is prepared, which improves the tensile performance and bonding performance of the hot melt adhesive, and at the same time can improve the flame retardant performance and high and low temperature resistance of the hot melt adhesive.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A biodegradable hot melt adhesive based on castor oil and rosin resin, comprising the following raw materials in parts by weight: 30 - 50 parts of EVA resin, 5 - 10 parts of modified castor oil, 30 - 40 parts of rosin resin, 5 - 10 parts of modified additive, 2 - 5 parts of lubricant, and 0.1 - 1 part of antioxidant;

[0007] The modified castor oil is prepared by cross - linking castor oil with isophorone diisocyanate through a chemical reaction, and reacting with lignin and 1,4 - butanediol with isocyanate groups; the modified additive is prepared by grafting aminated cage - type silsesquioxane with coated aluminum hydroxide through a chemical reaction, and further grafting with SBS - g - MAH, wherein the coated aluminum hydroxide is prepared by depositing polydopamine generated by the oxidative self - polymerization of dopamine under weak alkaline conditions on the surface of aluminum hydroxide.

[0008] Preferably, the lubricant is one or a combination of polyethylene wax, oxidized polyethylene wax, and microcrystalline wax; the antioxidant is one or a combination of antioxidant 1010, antioxidant 168, and antioxidant 1076.

[0009] Preferably, the preparation method of the modified castor oil comprises the following steps: Take castor oil in a reactor, add ethyl acetate solvent and stir to dissolve, then add isophorone diisocyanate and catalyst stannous octoate, react at 75 - 85 °C for 2 - 3 h in a nitrogen atmosphere to obtain a prepolymer. Take lignin and 1,4 - butanediol, add them to ethyl acetate solvent and stir to mix, then add them to the prepolymer, and continue to stir and react at 75 - 85 °C for 2 - 3 h to prepare the modified castor oil.

[0010] Preferably, the mass ratio of castor oil, isophorone diisocyanate, lignin, and 1,4 - butanediol is 4 - 5:3.4 - 4.8:0.5 - 1.5:0.45 - 0.75.

[0011] Preferably, the preparation method of the modified additive comprises the following steps:

[0012] A. Take deionized water, propanol, acetonitrile, and tetraethylammonium hydroxide in a reactor, stir and mix evenly, then add γ - aminopropyltriethoxysilane, react at 55 - 70 °C for 20 - 24 h, cool to room temperature after the reaction is completed, place the product in tetrahydrofuran for cooling and precipitation, and filter and dry the precipitate to prepare aminated cage - type silsesquioxane;

[0013] B. Take aluminum hydroxide, deionized water, and dopamine hydrochloride in a reactor, then add Tris - HCl, adjust the pH value of the system to 8 - 8.5 with ammonia water, stir and react for 28 - 36 h, and after the reaction is completed, centrifuge, wash, and dry to prepare coated aluminum hydroxide;

[0014] C. Take the coated aluminum hydroxide and the amino cage silsesquioxane in a reactor, add toluene solvent and Tris buffer with a pH value of 8-8.5, place at 70-85°C for reaction for 5-6 hours, and after the reaction is completed, centrifuge, wash and dry to prepare modified aluminum hydroxide;

[0015] D. Take modified aluminum hydroxide in a reactor, add toluene solvent and disperse it evenly by ultrasonication, take SBS-g-MAH and add toluene solvent, swell it for 20-24 hours at room temperature, then add it to the reactor, place it at 105-120°C for reflux reaction for 1-2 hours, then add triethylamine, reduce the temperature to 80-90°C, and reflux reaction for 2-3 hours. After the reaction is completed, filter, wash and dry to prepare the modified additive.

[0016] Preferably, in step A, the volume ratio of deionized water, propanol, acetonitrile, tetraethylammonium hydroxide and γ-aminopropyltriethoxysilane is 20-25:8-14:2-5:0.5-1:50-60.

[0017] Preferably, in step B, the mass ratio of aluminum hydroxide, deionized water, dopamine hydrochloride and Tris-HCl is 17-20:350-400:1.5-2.5:1.

[0018] Preferably, in step C, the mass ratio of the amino cage silsesquioxane to the coated aluminum hydroxide is 1:3-5.

[0019] Preferably, in step D, the mass ratio of modified aluminum hydroxide to SBS-g-MAH is 0.1-0.5:1.

[0020] The preparation process of the biodegradable hot melt adhesive based on castor oil and rosin resin as described above comprises the following steps:

[0021] S1, taking parts by weight of EVA resin, modified castor oil, rosin resin and lubricant in a high-speed disperser and fully mixing them, then heating them to 120-130° C. and stirring them until they are completely melted to prepare a mixture;

[0022] S2. Add parts by weight of the modifying additive to the mixture and continue stirring until it is completely mixed, then add parts by weight of the antioxidant and stir for 5 to 8 minutes, and finally reduce the temperature to 80 to 90° C. and stir at a constant temperature and uniform speed for 20 to 30 minutes to prepare the biodegradable hot melt adhesive based on castor oil and rosin resin.

[0023] Beneficial effects of the present invention:

[0024] The present invention utilizes EVA resin, modified castor oil, rosin resin, modified additives, lubricants and antioxidants to be blended and kneaded in a kneader to prepare a biodegradable hot melt adhesive based on castor oil and rosin resin, which improves the tensile property and bonding property of the hot melt adhesive, and simultaneously can improve the flame retardancy and high and low temperature resistance of the hot melt adhesive. The present invention crosslinks castor oil as a high-functional polyol with isophorone diisocyanate, and utilizes active groups such as phenolic hydroxyl groups and alcoholic hydroxyl groups in the lignin structure to react with isocyanate groups. Lignin, as the second largest biomass resource in the plant kingdom after cellulose in terms of reserves, has the characteristics of low cost, biodegradability and non-toxicity. Its phenolic structure has antioxidant activity due to its scavenging effect on oxygen-containing active free radicals. The introduction of lignin not only reduces the cost, but also improves the biodegradability, and can enhance the crosslinking density when preparing modified castor oil, so as to combine the dual advantages of lignin and castor oil and improve the comprehensive performance of the hot melt adhesive.

[0025] The present invention synthesizes amino-functionalized cage-like silsesquioxane by the hydrolysis and condensation reaction of γ-aminopropyltriethoxysilane. Meanwhile, the present invention utilizes dopamine to oxidatively self-polymerize under weak alkaline conditions to generate polydopamine. The polyphenol structure of polydopamine is not only a good charring agent, but also its catechol has a good free radical capturing effect during the combustion process. Deposit polydopamine on the surface of aluminum hydroxide, and then use the environmentally friendly bio-based raw material dopamine as a bridge to connect the coated aluminum hydroxide and the amino-functionalized cage-like silsesquioxane. The self-polymerization advantage of dopamine makes the surface of the coated aluminum hydroxide rich in carbonyl groups. Then, carry out a Schiff base reaction between the amino-functionalized cage-like silsesquioxane with a three-dimensional Si-O-Si backbone structure and the coated aluminum hydroxide to prepare modified aluminum hydroxide, and further carry out a graft reaction between the amino group in the modified aluminum hydroxide structure and the anhydride group in the SBS-g-MAH structure to prepare a modified additive. The modified aluminum hydroxide and SBS-g-MAH are combined through strong chemical bonds, which can improve the polarity of SBS-g-MAH, avoid the migration of SBS-g-MAH to the surface or bonding interface of the hot melt adhesive, thereby avoiding the formation of a weak adhesive layer at the bonding interface and resulting in a decrease in the peel strength, and the interfacial strength between the modified aluminum hydroxide and SBS is improved, thereby enhancing the mechanical properties of the hot melt adhesive. Detailed implementation manners

[0026] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0027] Example 1 A preparation method of modified castor oil includes the following steps:

[0028] Take 4 g of castor oil in a reactor, add 15 mL of ethyl acetate solvent and stir to dissolve. Then add 3.5 g of isophorone diisocyanate and 100 μL of stannous octoate catalyst. React at 85 °C for 2 h in a nitrogen atmosphere to obtain a prepolymer. Take 0.7 g of lignin and 0.55 g of 1,4-butanediol, add them to 5 mL of ethyl acetate solvent and stir to mix. Then add the mixture to the prepolymer and continue to stir and react at 85 °C for 2 h to prepare the modified castor oil.

[0029] Example 2 A preparation method of a modified additive comprises the following steps:

[0030] A. Take 24 mL of deionized water, 12 mL of propanol, 3 mL of acetonitrile and 1 mL of tetraethylammonium hydroxide in a reactor, stir and mix evenly. Then add 55 mL of γ-aminopropyltriethoxysilane and react at 60 °C with stirring for 24 h. After the reaction is completed, cool to room temperature. Place the product in tetrahydrofuran for cooling and precipitation. The precipitate is filtered and dried to prepare the aminated cage-like silsesquioxane.

[0031] B. Take 20 g of aluminum hydroxide, 400 mL of deionized water and 2 g of dopamine hydrochloride in a reactor. Then add 1 g of Tris-HCl and adjust the pH value of the system to 8.5 with ammonia water. Stir and react for 36 h. After the reaction is completed, centrifuge, wash and dry to prepare the coated aluminum hydroxide.

[0032] C. Weigh 0.5 g of tris(hydroxymethyl)aminomethane hydrochloride and dissolve it in 450 mL of deionized water. Adjust the pH value to 8.5 with 0.1 mol / L sodium hydroxide solution to obtain Tris buffer solution. Take 5 g of coated aluminum hydroxide and 1 g of aminated cage-like silsesquioxane in a reactor, add 200 mL of toluene solvent and 60 mL of Tris buffer solution, and react at 80 °C for 5 h. After the reaction is completed, centrifuge, wash and dry to prepare the modified aluminum hydroxide.

[0033] D. Take 1 g of modified aluminum hydroxide in a reactor, add 100 mL of toluene solvent and disperse it evenly by ultrasonic wave. Take 5 g of SBS-g-MAH and add it to 450 mL of toluene solvent. After swelling at room temperature for 24 h, add it to the reactor. React under reflux at 110 °C for 1 h, then add 2 mL of triethylamine, lower the temperature to 85 °C and react under reflux for 2 h. After the reaction is completed, filter, wash and dry to prepare the modified additive.

[0034] Example 3 A biodegradable hot melt adhesive based on castor oil and rosin resin comprises the following raw materials in parts by weight: 33 parts of EVA resin, 5 parts of the modified castor oil prepared in Example 1, 30 parts of rosin resin, 5 parts of the modified additive prepared in Example 2, 2 parts of lubricant polyethylene wax, 0.2 part of antioxidant 1010.

[0035] The preparation process of the above-mentioned biodegradable hot melt adhesive based on castor oil and rosin resin comprises the following steps:

[0036] S1. Take parts by weight of EVA resin, modified castor oil, rosin resin and lubricant, and fully mix them in a high-speed disperser, then heat up to 125°C and stir until completely melted to obtain a mixture.

[0037] S2. Add parts by weight of modified additive to the mixture and continue stirring until completely mixed, then add parts by weight of antioxidant and stir for 5 min. Finally, lower the temperature to 80°C and stir at a constant temperature and uniform speed for 20 min to obtain the biodegradable hot melt adhesive based on castor oil and rosin resin.

[0038] Example 4 A biodegradable hot melt adhesive based on castor oil and rosin resin, comprising the following raw materials in parts by weight: 45 parts of EVA resin, 7 parts of the modified castor oil prepared in Example 1, 35 parts of rosin resin, 8 parts of the modified additive prepared in Example 2, 3 parts of lubricant polyethylene wax oxide, and 0.5 part of antioxidant 168.

[0039] The preparation process of the above-mentioned biodegradable hot melt adhesive based on castor oil and rosin resin is the same as that in Example 3.

[0040] Example 5 A biodegradable hot melt adhesive based on castor oil and rosin resin, comprising the following raw materials in parts by weight: 48 parts of EVA resin, 9 parts of the modified castor oil prepared in Example 1, 37 parts of rosin resin, 10 parts of the modified additive prepared in Example 2, 5 parts of lubricant microcrystalline wax, and 0.9 part of antioxidant 1076.

[0041] The preparation process of the above-mentioned biodegradable hot melt adhesive based on castor oil and rosin resin is the same as that in Example 3.

[0042] Comparative Example 1 A preparation method of modified castor oil comprises the following steps:

[0043] Take 4 g of castor oil in a reactor, add 15 mL of ethyl acetate solvent and stir to dissolve it, and add 3.5 g of isophorone diisocyanate and 100 μL of catalyst stannous octoate. React at 85°C for 2 h in a nitrogen atmosphere to obtain a prepolymer. Take 0.55 g of 1,4-butanediol, add 5 mL of ethyl acetate solvent and stir to mix, then add it to the prepolymer and continue stirring and reacting at 85°C for 2 h to prepare the modified castor oil.

[0044] Comparative Example 2 A preparation method of modified additive comprises the following steps:

[0045] A. Take 24 mL of deionized water, 12 mL of propanol, 3 mL of acetonitrile, and 1 mL of tetraethylammonium hydroxide in a reactor, stir and mix them evenly, then add 55 mL of γ-aminopropyltriethoxysilane, place it at 60 °C and stir for reaction for 24 h. After the reaction is completed, cool it to room temperature, place the product in tetrahydrofuran for cooling precipitation, and filter and dry the precipitate to prepare amino-functionalized cage-shaped silsesquioxane;

[0046] B. Take 1 g of amino-functionalized cage-shaped silsesquioxane in a reactor, add 100 mL of toluene solvent and disperse it evenly by ultrasonic wave. Take 5 g of SBS-g-MAH and add it to 450 mL of toluene solvent, swell it at room temperature for 24 h and then add it to the reactor, place it at 110 °C and reflux for reaction for 1 h, then add 2 mL of triethylamine, lower the temperature to 85 °C, and reflux for reaction for 2 h. After the reaction is completed, filter, wash, and dry to prepare the modified additive.

[0047] Comparative Example 3 A preparation method of a modified additive comprises the following steps:

[0048] A. Take 20 g of aluminum hydroxide, 400 mL of deionized water, and 2 g of dopamine hydrochloride in a reactor, then add 1 g of Tris-HCl, adjust the pH value of the system to 8.5 with ammonia water, stir and react for 36 h. After the reaction is completed, centrifuge, wash, and dry to prepare coated aluminum hydroxide;

[0049] B. Take 1 g of coated aluminum hydroxide in a reactor, add 100 mL of toluene solvent and disperse it evenly by ultrasonic wave. Take 5 g of SBS-g-MAH and add it to 450 mL of toluene solvent, swell it at room temperature for 24 h and then add it to the reactor, place it at 110 °C and reflux for reaction for 1 h, then add 2 mL of triethylamine, lower the temperature to 85 °C, and reflux for reaction for 2 h. After the reaction is completed, filter, wash, and dry to prepare the modified additive.

[0050] Comparative Example 4 A biodegradable hot melt adhesive based on castor oil and rosin resin comprises the following raw materials in parts by weight: 48 parts of EVA resin, 9 parts of castor oil prepared in Comparative Example 1, 37 parts of rosin resin, 10 parts of the modified additive prepared in Example 2, 5 parts of lubricant microcrystalline wax, and 0.9 part of antioxidant 1076.

[0051] The preparation process of the above biodegradable hot melt adhesive based on castor oil and rosin resin is the same as that of Example 3.

[0052] Comparative Example 5 A biodegradable hot melt adhesive based on castor oil and rosin resin comprises the following raw materials in parts by weight: 48 parts of EVA resin, 9 parts of modified castor oil prepared in Example 1, 37 parts of rosin resin, 10 parts of the modified additive prepared in Comparative Example 2, 5 parts of lubricant microcrystalline wax, and 0.9 part of antioxidant 1076.

[0053] The preparation process of the above-mentioned biodegradable hot melt adhesive based on castor oil and rosin resin is the same as that of Example 3.

[0054] Comparative Example 6 A biodegradable hot melt adhesive based on castor oil and rosin resin, comprising the following raw materials in parts by weight: 48 parts of EVA resin, 9 parts of the modified castor oil prepared in Example 1, 37 parts of rosin resin, 10 parts of the modified additive prepared in Comparative Example 3, 5 parts of lubricant microcrystalline wax, and 0.9 part of antioxidant 1076.

[0055] The preparation process of the above-mentioned biodegradable hot melt adhesive based on castor oil and rosin resin is the same as that of Example 3.

[0056] Comparative Example 7 A biodegradable hot melt adhesive based on castor oil and rosin resin, comprising the following raw materials in parts by weight: 48 parts of EVA resin, 9 parts of the modified castor oil prepared in Example 1, 37 parts of rosin resin, 2 parts of the modified aluminum hydroxide prepared in Example 2, 8 parts of SBS-g-MAH, 5 parts of lubricant microcrystalline wax, and 0.9 part of antioxidant 1076.

[0057] The preparation process of the above-mentioned biodegradable hot melt adhesive based on castor oil and rosin resin is the same as that of Example 3.

[0058] Performance testing

[0059] Perform performance testing on the hot melt adhesives prepared in Examples 3-5 and Comparative Examples 4-7:

[0060] a. According to the GB / T 528-2009 standard, use a universal tensile testing machine to test the tensile strength and elongation at break of the hot melt adhesive; prepare samples according to the GB / T 2790-1995 standard and use a universal tensile testing machine to measure the 180° peel strength; according to the GB / T 15332-1994 standard, use the ring method to conduct the softening point test; according to GB / T 10707-2008, conduct the limiting oxygen index and vertical burning tests, and the data results are shown in Table 1.

[0061] b. Biodegradability test: Biodegradability refers to the property of a specimen being decomposed into small molecules by microorganisms in the natural environment. Usually, the soil burial method is used for testing. Weigh the square thin film specimen with a specification of 10×10 cm 2 as m 1 , bury it in moist soil, take it out after one month, wash, dry and weigh it as m 2 , and characterize its degradation performance by its mass change rate. The monthly degradation rate α = (m 1 -m 2 ) / m 1 ×100%, and the data results are shown in Table 1.

[0062] Table 1 Test results of specimen performance

[0063]

[0064] As can be seen from the data in Table 1, the hot melt adhesives prepared in Examples 3-5 of the present invention have good adhesion performance, flame retardant performance, mechanical properties and high and low temperature resistance. Among them, the modified castor oil added in Comparative Example 4 does not contain lignin components, and the measured tensile strength is significantly lower than that in Examples 3-5. The reason is that the introduction of lignin increases the intramolecular crosslinking density, resulting in a significant enhancement of the tensile strength. However, the addition of lignin reduces the toughness of the hot melt adhesive, so the elongation at break will decrease. The modified additive added in Comparative Example 5 does not contain coated aluminum hydroxide components, and the measured limiting oxygen index and UL-94 rating are lower than those in Examples 3-5, indicating that the addition of coated aluminum hydroxide can improve the flame retardant performance of the hot melt adhesive. The modified additive added in Comparative Example 6 does not contain aminated cage-like silsesquioxane components, and the measured tensile strength, elongation at break, softening point and peel strength are lower than those in Examples 3-5, indicating that the introduction of aminated cage-like silsesquioxane can improve the mechanical properties of the material, and improve its high and low temperature resistance and adhesion performance. In Comparative Example 7, the modified aluminum hydroxide and SBS-g-MAH were simply mixed, and the measured tensile strength, elongation at break and peel strength were lower than those in Examples 3-5, indicating that the graft reaction of the modified aluminum hydroxide and SBS-g-MAH can improve the mechanical properties and adhesion performance of the material.

[0065] In the description of this specification, the descriptions referring to the terms "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0066] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art of this industry should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. A biodegradable hot melt adhesive based on castor oil and rosin resin, characterized in that: The invention comprises the following raw materials in parts by weight: 30-50 parts of EVA resin, 5-10 parts of modified castor oil, 30-40 parts of rosin resin, 5-10 parts of modified additive, 2-5 parts of lubricant, and 0.1-1 part of antioxidant; The preparation method of the modified castor oil comprises the following steps: taking castor oil in a reactor, adding ethyl acetate solvent to stir and dissolve, adding isophorone diisocyanate and stannous octoate as a catalyst, reacting at 75-85° C. for 2-3 hours in a nitrogen atmosphere to obtain a prepolymer, taking lignin and 1,4-butanediol, adding ethyl acetate solvent to stir and mix, then adding the mixture to the prepolymer, and continuing to stir and react at 75-85° C. for 2-3 hours to prepare the modified castor oil; The preparation method of the modified additive comprises the following steps: A. Deionized water, propanol, acetonitrile and tetraethylammonium hydroxide are placed in a reactor, stirred and mixed evenly, and then γ-aminopropyltriethoxysilane is added, and the mixture is stirred and reacted at 55-70° C. for 20-24 hours. After the reaction is completed, the mixture is cooled to room temperature, and the product is placed in tetrahydrofuran and cooled and precipitated. The precipitate is filtered and dried to prepare an amino cage-type silsesquioxane; B. Put aluminum hydroxide, deionized water and dopamine hydrochloride in a reactor, then add Tris-HCl, adjust the pH value of the system to 8-8.5 with ammonia water, stir and react for 28-36 hours, and after the reaction is completed, centrifuge, wash and dry to prepare coated aluminum hydroxide; C. Take the coated aluminum hydroxide and the amino cage silsesquioxane in a reactor, add toluene solvent and Tris buffer with a pH value of 8-8.5, place at 70-85°C for reaction for 5-6 hours, and after the reaction is completed, centrifuge, wash and dry to prepare modified aluminum hydroxide; D. Take modified aluminum hydroxide in a reactor, add toluene solvent and disperse it evenly by ultrasonication, take SBS-g-MAH and add toluene solvent, swell for 20-24 hours at room temperature, then add it to the reactor, place it at 105-120°C for reflux reaction for 1-2 hours, then add triethylamine, reduce the temperature to 80-90°C, and reflux reaction for 2-3 hours. After the reaction is completed, filter, wash and dry to prepare the modified additive; The mass ratio of castor oil, isophorone diisocyanate, lignin and 1,4-butanediol is 4-5: 3.4-4.8: 0.5-1.5: 0.45-0.75; In the step A, the volume ratio of deionized water, propanol, acetonitrile, tetraethylammonium hydroxide and γ-aminopropyltriethoxysilane is 20-25:8-14:2-5:0.5-1:50-60; in the step B, the mass ratio of aluminum hydroxide, deionized water, dopamine hydrochloride and Tris-HCl is 17-20:350-400:1.5-2.5:1; in the step C, the mass ratio of amino cage silsesquioxane and coated aluminum hydroxide is 1:3-5; in the step D, the mass ratio of modified aluminum hydroxide and SBS-g-MAH is 0.1-0.5:

1.

2. The biodegradable hot melt adhesive based on castor oil and rosin resin according to claim 1, characterized in that: The lubricant is one or more combinations of polyethylene wax, oxidized polyethylene wax, and microcrystalline wax; the antioxidant is one or more combinations of antioxidant 1010, antioxidant 168, and antioxidant 1076.

3. A process for preparing a biodegradable hot melt adhesive based on castor oil and rosin resin according to any one of claims 1 to 2, characterized in that: The following steps are involved: S1. Take EVA resin, modified castor oil, rosin resin and lubricant in a high-speed disperser and mix them thoroughly, then heat them to 120-130° C. and stir until they are completely melted to prepare a mixture; S2. Add the modified additive to the mixture and continue stirring until it is completely mixed, then add the antioxidant and stir for 5-8 minutes, and finally reduce the temperature to 80-90° C. and stir at a constant temperature and uniform speed for 20-30 minutes to prepare the biodegradable hot melt adhesive based on castor oil and rosin resin.

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