Modified rosin castor oil-based polyurethane degradable hot melt adhesive and preparation method thereof

Abstract

The invention relates to the technical field of hot melt adhesive preparation, and discloses a modified rosin castor oil-based polyurethane degradable hot melt adhesive and a preparation method thereof. The modified rosin castor oil based polyurethane degradable hot melt adhesive is prepared from the following raw materials in parts by weight: 200 to 250 parts of castor oil modified polyurethane, 80 to 120 parts of modified rosin resin, 15 to 30 parts of functional modified nanoparticles, 10 to 15 parts of ammonium polyphosphate, 5 to 10 parts of aluminum hydroxide, 0.5 to 5 parts of plasticizer and 0.1 to 0.5 part of antioxidant. The rosin resin is modified by acrylic acid and then compounded with castor oil-based polyurethane resin, so that the adhesion, heat resistance, glossiness and hardness of the material are improved, the material has good antibacterial property by adding functional modified particles, and meanwhile, the flame retardant property of the material is further improved.

Description

Technical Field

[0001] The invention belongs to the technical field of hot melt adhesive preparation, and particularly relates to a modified rosin castor oil-based polyurethane degradable hot melt adhesive and a preparation method thereof. Background Art

[0002] Hot melt adhesive refers to an adhesive that is solid at room temperature, becomes liquid after heating and melting, and after coating and wetting the adherend, it is pressed and cooled to complete the bonding within a few seconds. Therefore, people refer to hot melt adhesives as hot melt adhesives. It is made of thermoplastic resin as the base material, and contains viscosity modifiers, fillers, antioxidants, etc., which are melted and mixed. When heated, it melts into a viscous flow state and can wet the processing surface; after being separated from the heat source, it cools down and solidifies in a very short time, without a drying process, consumes less energy, and is easy to operate. It can be used in high-speed continuous production lines, which can solve the problem of difficult bonding of certain materials and improve production efficiency. At present, hot melt adhesive, as a convenient type of adhesive, has become a commonly used adhesive in various industries in modern society due to its excellent performance and convenient application. It has been widely used in packaging, plywood, woodworking and other fields, as well as fiber, construction, civil engineering, automobile, electrical and other departments.

[0003] At present, the hot melt adhesive market is dominated by EVA hot melt adhesive, which also includes different product types such as polyethylene, polypropylene, polyamide, polyimide, polyester, polyurethane, etc. The base resins are all high molecular organic matter with special chemical structures and characteristics that are difficult to biodegrade. With the widespread and in-depth application of hot melt adhesives, their long-term retention in the environment has become a hidden danger and hazard to the ecological environment. In recent years, biodegradable hot melt adhesives have emerged, especially for packaging materials such as paper and disposable sanitary ware, or packaging materials with a short service life, the demand for biodegradable hot melt adhesives is more urgent. At present, the most studied biodegradable hot melt adhesives are PLA hot melt adhesives and polyester amide hot melt adhesives, but they currently have disadvantages such as poor stability during use, unstable bonding, poor bonding strength and poor flexibility. At the same time, the existing degradable hot melt adhesives lack flame retardant and antibacterial properties, which limits their application in packaging materials. Summary of the invention

[0004] In order to solve the deficiencies mentioned in the above background technology, the purpose of the present invention is to provide a modified rosin castor oil-based polyurethane degradable hot melt adhesive and a preparation method thereof. Castor oil is modified by mercaptoethanol and then synthesized with isocyanate to form a castor oil-based polyurethane resin. Rosin resin is modified by acrylic acid and then compounded with a castor oil-based polyurethane resin to improve the adhesion, heat resistance, gloss and hardness of the material. By adding functional modified particles, the material has good antibacterial properties and the flame retardant properties of the material are further improved.

[0005] The purpose of the present invention can be achieved through the following technical solutions: A modified rosin castor oil-based polyurethane degradable hot melt adhesive comprises the following raw materials in parts by weight: 200-250 parts of castor oil-modified polyurethane, 80-120 parts of modified rosin resin, 15-30 parts of functional modified nanoparticles, 10-15 parts of ammonium polyphosphate, 5-10 parts of aluminum hydroxide, 0.5-5 parts of plasticizer, and 0.1-0.5 parts of antioxidant; The modified rosin resin is acrylic acid modified rosin resin; the functional nanoparticles are cyclotriphosphazene derivatives grafted with nano titanium dioxide, and the cyclotriphosphazene derivative molecules contain hindered phenol structure, benzisothiazolinone structure and siloxane structure.

[0006] More preferably, the plasticizer is selected from one or more of dibutyl phthalate, dioctyl phthalate, dioctyl terephthalate, dioctyl adipate, chlorinated paraffin, phosphate ester, and epoxidized soybean oil.

[0007] More preferably, the lubricant is one or more of stearic acid, sodium stearate, paraffin, and polyethylene wax.

[0008] Further preferably, the preparation method of castor oil modified polyurethane comprises the following steps: (1) Mix the vacuum-dried castor oil and mercaptoethanol, add azobisisobutyronitrile under nitrogen protection, react at 80°C for 3-5 hours, then raise the temperature to 100°C and react for 1-3 hours, cool down and add ethyl acetate, wash the product with water and brine for 3-5 times, and wash with MgSO 4 After drying, ethyl acetate is removed to obtain modified castor oil; (2) After mixing dehydrated xylene and diphenylmethane diisocyanate, heat the mixture in an oil bath to 50°C, then slowly add the modified castor oil in step (1), continue heating to 80°C, and rapidly stir to react for 1-3 hours. Add an appropriate amount of dibenzoyl peroxide diluent, disperse the mixture evenly, and then reduce the pressure to remove bubbles, thereby obtaining castor oil-modified polyurethane.

[0009] Further preferably, the molar ratio of castor oil to mercaptoethanol is 1:1-3, the mass ratio of the modified castor oil to diphenylmethane diisocyanate is 2-3:1, and the dehydrated xylene accounts for 3-5% of the total mass of the modified castor oil and diphenylmethane diisocyanate.

[0010] Further preferably, the preparation method of the modified rosin resin comprises the following steps: A. Grind the rosin and add hydroquinone, stir and heat to 160℃ under nitrogen protection, increase the nitrogen flow rate and continue to heat to 200℃; B. Reduce the nitrogen flow rate and slowly add acrylic acid. The dripping should be completed within 1.5 hours. Then, heat to 230℃ and react for 3-5 hours. C. After the reaction is completed, the nitrogen flow rate is increased to remove unreacted raw materials and moisture, and the temperature is slowly lowered to 175°C at room temperature to obtain modified rosin resin.

[0011] Further preferably, the method for preparing the functional modified nanoparticles comprises the following steps: Ⅰ. Mix 1,2-benzisothiazol-3-one, potassium carbonate and N,N-dimethylformamide, then slowly add 3,5-dibromobenzyl alcohol at room temperature, heat to 70°C and stir to react for 10-12 hours. After the reaction, add deionized water to dissolve the product and extract the mixed solution with ethyl acetate. Add anhydrous magnesium sulfate to the extract to dehydrate and filter. The filtrate is evaporated to remove ethyl acetate, and finally purified by a chromatographic column to obtain intermediate A; Ⅱ. Add hexachlorocyclotriphosphazene to 1,4-dioxane and triethylamine under nitrogen atmosphere, stir to dissolve the hexachlorocyclotriphosphazene, then uniformly add intermediate A, react in an ice bath for 1-3 hours after the addition is complete, add 3-aminopropyltriethoxysilane to the reaction system, then heat up to 40-50°C at a rate of 2-4°C / min, and keep the temperature for 1-3 hours. After the reaction is complete, cool and filter to remove triethylamine hydrochloride, remove tetrahydrofuran by vacuum distillation, add ethyl acetate, dry and filter, and vacuum distill the filtrate to obtain a cyclotriphosphazene derivative; III. Add nano titanium dioxide to 95% Vol ethanol aqueous solution, ultrasonically disperse for 10-15 minutes, adjust the solution pH to 4 with hydrochloric acid aqueous solution, then slowly add the cyclotriphosphazene derivative to the above dispersion, continue ultrasonic dispersion for 5-10 minutes, heat to 80°C and keep the reaction for 3-5 hours, filter after cooling, wash and dry to obtain functional modified nanoparticles.

[0012] More preferably, the molar ratio of 1,2-benzisothiazol-3-one to 3,5-dibromobenzyl alcohol is 2:1, and the molar ratio of hexachlorocyclotriphosphazene, intermediate A and 3-aminopropyltriethoxysilane is 1:1:5.

[0013] A method for preparing a modified rosin castor oil-based polyurethane degradable hot melt adhesive comprises the following steps: S1. Mix castor oil modified polyurethane and modified rosin resin, heat to 120-130°C to completely melt the materials, dehydrate in air for 1 hour, and then release the vacuum; S2. Then add functional modified nanoparticles, ammonium polyphosphate, aluminum hydroxide, plasticizer and antioxidant in sequence, stir for 2-3 hours, vacuum degassing until no bubbles appear in the system, and then discharge the material.

[0014] Beneficial effects of the present invention: The modified rosin castor oil-based polyurethane degradable hot melt adhesive of the present invention modifies castor oil by mercaptoethanol to improve its functionality, and then uses castor oil and isocyanate to synthesize castor oil-based polyurethane resin, effectively improving the adhesion and heat resistance of the hot melt adhesive, using acrylic acid to modify the rosin resin to solve the problem of easy oxidation of rosin, and adding the modified rosin to the castor oil-based polyurethane can effectively improve the glossiness, hardness and other properties of the material. At the same time, the present invention also adds functional modified nanoparticles, adopts affinity substitution reaction to graft the benzisothiazolinone structure to the hexachlorocyclotriphosphazene molecule, and then bridges with the nano titanium dioxide molecule by a silane coupling agent, so that the functional modified nanoparticles have antibacterial function, and the rich nitrogen, phosphorus and silicon elements can promote the dehydration and carbonization of the polymer in the thermal cracking process, and form a carbonaceous protective layer of Si-O and Si-C, which cooperates with ammonium polyphosphate and aluminum hydroxide to improve the flame retardant property of the material. DETAILED DESCRIPTION

[0015] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0016] Example 1 A method for preparing castor oil modified polyurethane comprises the following steps: (1) Mix 9.0 g of vacuum-dried castor oil and 2.2 g of mercaptoethanol, add 0.5 g of azobisisobutyronitrile under nitrogen protection, react at 80 °C for 4 h, then raise the temperature to 100 °C and react for 2 h, cool down and add 50 ml of ethyl acetate, wash the product with water and brine for 3 to 5 times, and then rinse with MgSO 4 After drying, ethyl acetate is removed to obtain modified castor oil; (2) 1.5 g of dehydrated xylene and 5.0 g of diphenylmethane diisocyanate were mixed and heated in an oil bath to 50° C., and then 11.2 g of the modified castor oil in step (1) was slowly added, and the temperature was continued to rise to 80° C., and the mixture was rapidly stirred for reaction for 2 h. A diluent of dibenzoyl peroxide was added, and after uniform dispersion, the pressure was reduced to eliminate bubbles, thereby obtaining a castor oil-modified polyurethane.

[0017] Example 2 A method for preparing a modified rosin resin comprises the following steps: A. Grind 20.5g of rosin and add 0.6g of hydroquinone. Stir and heat to 160℃ under nitrogen protection. Increase the nitrogen flow rate and continue to heat to 200℃. B. Reduce the nitrogen flow rate and slowly add 4.1 g of acrylic acid. The dripping time is 1.5 hours. Then, the temperature is raised to 230°C and the reaction is continued for 4 hours. C. After the reaction is completed, the nitrogen flow rate is increased to remove unreacted raw materials and moisture, and the temperature is slowly lowered to 175°C at room temperature to obtain modified rosin resin.

[0018] Example 3 A functional modified nanoparticle, wherein the functional nanoparticle is a cyclotriphosphazene derivative grafted with nano titanium dioxide, wherein the cyclotriphosphazene derivative molecule contains a hindered phenol structure, a benzisothiazolinone structure and a siloxane structure, and the molecular formula of the cyclotriphosphazene derivative is as follows: ; The above-mentioned method for preparing functional modified nanoparticles comprises the following steps: Ⅰ. Mix 4.5 g of 1,2-benzisothiazol-3-one, 0.5 g of potassium carbonate and 50 ml of N,N-dimethylformamide, then slowly add 4.0 g of 3,5-dibromobenzyl alcohol at room temperature, heat to 70°C and stir to react for 12 hours. After the reaction, add deionized water to dissolve the product and extract the mixed solution with ethyl acetate. Add anhydrous magnesium sulfate to the extract to dehydrate and filter. The filtrate is evaporated to remove ethyl acetate, and finally purified by a chromatographic column to obtain intermediate A; Ⅱ. Add 3.5g of hexachlorocyclotriphosphazene to 20ml of 1,4-dioxane and 30ml of triethylamine under nitrogen atmosphere, stir to dissolve the hexachlorocyclotriphosphazene, then uniformly add 4.1g of intermediate A, react in an ice bath for 2h after the addition is complete, add 11.5g of 3-aminopropyltriethoxysilane to the reaction system, then heat up to 45°C at a rate of 3°C / min, keep the temperature for 2h, cool after the reaction is complete, remove triethylamine hydrochloride by suction filtration, remove tetrahydrofuran by reduced pressure distillation, add ethyl acetate, dry and filter, and distill the filtrate under reduced pressure to obtain a cyclotriphosphazene derivative; III. Add 6.5 g of nano titanium dioxide to 50 ml of 95% Vol ethanol aqueous solution, ultrasonically disperse for 12 min, adjust the solution pH to 4 with hydrochloric acid aqueous solution, then slowly add 2.5 g of cyclotriphosphazene derivative to the above dispersion, continue ultrasonic dispersion for 8 min, heat to 80 ° C and keep the reaction for 4 h, filter after cooling, wash and dry to obtain the functional modified nanoparticles.

[0019] Example 4 A modified rosin castor oil-based polyurethane degradable hot melt adhesive comprises the following raw materials in parts by weight: 200 parts of castor oil-modified polyurethane, 120 parts of modified rosin resin, 15 parts of functional modified nanoparticles, 15 parts of ammonium polyphosphate, 5 parts of aluminum hydroxide, 5 parts of dibutyl phthalate, and 0.1 part of antioxidant 168; the castor oil-modified polyurethane is prepared in Example 1, and the modified rosin resin is prepared in Example 2; the functional nanoparticles are cyclotriphosphazene derivative-grafted nano-titanium dioxide prepared in Example 3.

[0020] A method for preparing a modified rosin castor oil-based polyurethane degradable hot melt adhesive comprises the following steps: S1. Mix castor oil modified polyurethane and modified rosin resin, heat to 125°C to completely melt the materials, dehydrate in air for 1 hour, and then release the vacuum; S2. Then, functional modified nanoparticles, ammonium polyphosphate, aluminum hydroxide, dibutyl phthalate, and antioxidant 168 are added in sequence, stirred for 2 hours, and vacuum degassed until no bubbles appear in the system, and then the material is discharged.

[0021] Example 5 A modified rosin castor oil-based polyurethane degradable hot melt adhesive comprises the following raw materials in parts by weight: 250 parts of castor oil-modified polyurethane, 80 parts of modified rosin resin, 30 parts of functional modified nanoparticles, 10 parts of ammonium polyphosphate, 10 parts of aluminum hydroxide, 0.5 parts of chlorinated paraffin, and 0.5 parts of antioxidant 626; the castor oil-modified polyurethane is prepared in Example 1, and the modified rosin resin is prepared in Example 2; the functional nanoparticles are cyclotriphosphazene derivative-grafted nano-titanium dioxide prepared in Example 3.

[0022] A method for preparing a modified rosin castor oil-based polyurethane degradable hot melt adhesive comprises the following steps: S1. Mix castor oil modified polyurethane and modified rosin resin, heat to 125°C to completely melt the materials, dehydrate in air for 1 hour, and then release the vacuum; S2. Then add functional modified nanoparticles, ammonium polyphosphate, aluminum hydroxide, chlorinated paraffin, and antioxidant 626 in sequence, stir for 3 hours, vacuum degassing until no bubbles appear in the system, and discharge the material.

[0023] Example 6 A modified rosin castor oil-based polyurethane degradable hot melt adhesive comprises the following raw materials in parts by weight: 220 parts of castor oil-modified polyurethane, 100 parts of modified rosin resin, 22 parts of functional modified nanoparticles, 13 parts of ammonium polyphosphate, 8 parts of aluminum hydroxide, 2 parts of dibutyl phthalate, 0.5 parts of epoxidized soybean oil, and 0.3 parts of antioxidant 1010; the castor oil-modified polyurethane is prepared in Example 1, and the modified rosin resin is prepared in Example 2; the functional nanoparticles are cyclotriphosphazene derivative-grafted nano-titanium dioxide prepared in Example 3.

[0024] A method for preparing a modified rosin castor oil-based polyurethane degradable hot melt adhesive comprises the following steps: S1. Mix castor oil modified polyurethane and modified rosin resin, heat to 125°C to completely melt the materials, dehydrate in air for 1 hour, and then release the vacuum; S2. Then add functional modified nanoparticles, ammonium polyphosphate, aluminum hydroxide, dibutyl phthalate, epoxy soybean oil, and antioxidant 1010 in sequence, stir for 2.5 hours, vacuum degassing until no bubbles appear in the system, and discharge the material.

[0025] Comparative Example 1 A modified rosin castor oil-based polyurethane degradable hot melt adhesive comprises the following raw materials in parts by weight: 220 parts of castor oil-modified polyurethane, 100 parts of modified rosin resin, 13 parts of ammonium polyphosphate, 8 parts of aluminum hydroxide, 2 parts of dibutyl phthalate, 0.5 parts of epoxidized soybean oil, and 0.3 parts of antioxidant 1010; the castor oil-modified polyurethane is prepared in Example 1, and the modified rosin resin is prepared in Example 2.

[0026] A method for preparing a modified rosin castor oil-based polyurethane degradable hot melt adhesive comprises the following steps: S1. Mix castor oil modified polyurethane and modified rosin resin, heat to 125°C to completely melt the materials, dehydrate in air for 1 hour, and then release the vacuum; S2. Then add ammonium polyphosphate, aluminum hydroxide, dibutyl phthalate, epoxy soybean oil and antioxidant 1010 in sequence, stir for 2.5 hours, vacuum degassing until no bubbles appear in the system, and discharge the material.

[0027] Performance Testing 1. Flame retardant performance test The modified rosin castor oil-based polyurethane degradable hot melt adhesive in Examples 4 to 6 and Comparative Example 1 was made into a 127×12.7×3.2 mm standard specimen, and a horizontal and vertical (UL-94) burning test was performed according to ASTM D3801-1996 standard. At the same time, an oxygen index test (LOI) was performed according to ASTM D2863-70 standard to obtain the data shown in Table 1 below.

[0028] Table 1 Test results of flame retardant properties of modified rosin castor oil based polyurethane degradable hot melt adhesive

[0029] It can be seen from the data in Table 1 that the modified rosin castor oil-based polyurethane degradable hot melt adhesive of the present invention has good flame retardant properties. In Comparative Example 1, no functional modified nanoparticles are added, and its flame retardant properties are slightly reduced. The reason may be that the cyclotriphosphazene derivative grafted in the functional modified nanoparticles contains a large amount of nitrogen and phosphorus elements and silicon elements, which, when compounded with ammonium polyphosphate and aluminum hydroxide, can give the material good flame retardant properties.

[0030] 3. Antibacterial performance test The antibacterial activity of the modified rosin castor oil-based polyurethane degradable hot melt adhesive in Examples 4 to 6 and Comparative Example 1 was determined by plate colony counting method. Escherichia coli was cultured in Luria-Bertani (LB) medium and cultured overnight at 37°C and 150r / min with shaking. The obtained bacterial suspension was centrifuged and diluted with an appropriate amount of 0.9% NaCl solution. 100µl of the bacterial solution was added to a 96-well plate and measured using an ELISA reader and diluted to an optical density of OD600 = 0.1 (at this time, the colony forming unit is 10 8 coli suspension) and then diluted to 10 CFU / mL using NaCl solution. 5 CFU / mL. The modified rosin castor oil-based polyurethane degradable hot melt adhesive was crushed into powder with a particle size of 0.1-1 mm. After being sterilized by ultraviolet irradiation for 3 hours, the sample was placed in 100 mL of bacterial suspension (10 5 CFU / mL) in a conical flask, take out the bacterial solution at different time intervals (0, 1, 2, 4, 8h) and put it into the well plate, and add NaCl solution to dilute it to 10 3 CFU / mL. 100µl of bacterial solution was applied to LB agar plates and cultured at 37°C for more than 16 hours. The colony plate test was performed at least three times independently. After determining the number of colonies, the inhibition rate was calculated according to the following formula: Inhibition rate (%) = mean number of colonies at a certain time / mean number of initial colonies × 100%, and the data are shown in Table 2 below: Table 2 Test results of antibacterial properties of modified rosin castor oil-based polyurethane degradable hot melt adhesive

[0031] It can be seen from the data in Table 2 that the environmentally friendly sponges in Examples 4 to 6 have good antibacterial properties, and the antibacterial rate of Comparative Example 1 is significantly lower than that of other groups due to the lack of functional modified nanoparticles. The present invention adopts an affinity substitution reaction to graft the benzisothiazolinone structure onto the hexachlorocyclotriphosphazene molecule, and then bridges it with the nano-titanium dioxide molecule through a silane coupling agent, so that the functional modified nanoparticles have antibacterial function.

[0032] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A modified rosin castor oil-based polyurethane degradable hot melt adhesive, characterized in that: The invention comprises the following raw materials in parts by weight: 200-250 parts of castor oil modified polyurethane, 80-120 parts of modified rosin resin, 15-30 parts of functional modified nanoparticles, 10-15 parts of ammonium polyphosphate, 5-10 parts of aluminum hydroxide, 0.5-5 parts of plasticizer, and 0.1-0.5 parts of antioxidant; The modified rosin resin is acrylic acid modified rosin resin; the functional nanoparticles are cyclotriphosphazene derivatives grafted with nano titanium dioxide, and the cyclotriphosphazene derivative molecules contain hindered phenol structure, benzisothiazolinone structure and siloxane structure.

2. The modified rosin castor oil-based polyurethane degradable hot melt adhesive according to claim 1, characterized in that: The plasticizer is selected from one or more of dibutyl phthalate, dioctyl phthalate, dioctyl terephthalate, dioctyl adipate, chlorinated paraffin, phosphate ester, and epoxidized soybean oil.

3. The modified rosin castor oil-based polyurethane degradable hot melt adhesive according to claim 1, characterized in that: The antioxidant is one or more of antioxidant 168, antioxidant 1010, antioxidant 1098 and antioxidant 626.

4. The modified rosin castor oil-based polyurethane degradable hot melt adhesive according to claim 1, characterized in that: The preparation method of the castor oil modified polyurethane comprises the following steps: (1) Mixing the vacuum-dried castor oil and mercaptoethanol, adding azobisisobutyronitrile under nitrogen protection, reacting at 80°C for 3-5 hours, then heating to 100°C, reacting for 1-3 hours, cooling and adding ethyl acetate, washing the product with water and brine for 3-5 times, drying with MgSO4 and removing ethyl acetate to obtain modified castor oil; (2) After mixing dehydrated xylene and diphenylmethane diisocyanate, heat the mixture in an oil bath to 50°C, then slowly add the modified castor oil in step (1), continue heating to 80°C, and rapidly stir to react for 1 to 3 hours. Then, add a dilute solution of dibenzoyl peroxide, disperse the mixture evenly, and then reduce the pressure to remove bubbles, thereby obtaining a castor oil-modified polyurethane.

5. The modified rosin castor oil-based polyurethane degradable hot melt adhesive according to claim 4, characterized in that: The molar ratio of the castor oil to mercaptoethanol is 1:1-3, the mass ratio of the modified castor oil to diphenylmethane diisocyanate is 2-3:1, and the dehydrated xylene accounts for 3-5% of the total mass of the modified castor oil and diphenylmethane diisocyanate.

6. The modified rosin castor oil-based polyurethane degradable hot melt adhesive according to claim 1, characterized in that: The preparation method of the modified rosin resin comprises the following steps: A. Grind the rosin and add hydroquinone, stir and heat to 160℃ under nitrogen protection, increase the nitrogen flow rate and continue to heat to 200℃; B. Reduce the nitrogen flow rate and slowly add acrylic acid dropwise for 1.5 hours, then raise the temperature to 230°C and react for 3-5 hours; C. After the reaction is completed, the nitrogen flow rate is increased to remove unreacted raw materials and moisture, and the temperature is slowly lowered to 175°C at room temperature to obtain modified rosin resin.

7. The modified rosin castor oil-based polyurethane degradable hot melt adhesive according to claim 6, characterized in that: The mass ratio of the rosin to the acrylic acid is 5:1, and the mass of the hydroquinone accounts for 2-3% of the total mass of the rosin and the acrylic acid.

8. The modified rosin castor oil-based polyurethane degradable hot melt adhesive according to claim 1, characterized in that: The preparation method of the functional modified nanoparticles comprises the following steps: Ⅰ. Mix 1,2-benzisothiazol-3-one, potassium carbonate and N,N-dimethylformamide, then slowly add 3,5-dibromobenzyl alcohol at room temperature, heat to 70°C and stir to react for 10-12 hours. After the reaction, add deionized water to dissolve the product and extract the mixed solution with ethyl acetate. Add anhydrous magnesium sulfate to the extract to dehydrate and filter. The filtrate is evaporated to remove ethyl acetate, and finally purified by a chromatographic column to obtain intermediate A; Ⅱ. Add hexachlorocyclotriphosphazene to 1,4-dioxane and triethylamine under nitrogen atmosphere, stir to dissolve the hexachlorocyclotriphosphazene, then uniformly add intermediate A, react in an ice bath for 1-3 hours after the addition is complete, add 3-aminopropyltriethoxysilane to the reaction system, then heat up to 40-50°C at a rate of 2-4°C / min, and keep the temperature for 1-3 hours. After the reaction is complete, cool and filter to remove triethylamine hydrochloride, remove tetrahydrofuran by vacuum distillation, add ethyl acetate, dry and filter, and vacuum distill the filtrate to obtain a cyclotriphosphazene derivative; III. Add nano titanium dioxide to 95% Vol ethanol aqueous solution, ultrasonically disperse for 10-15 minutes, adjust the solution pH to 4 with hydrochloric acid aqueous solution, then slowly add the cyclotriphosphazene derivative to the above dispersion, continue ultrasonic dispersion for 5-10 minutes, heat to 80°C and keep the reaction for 3-5 hours, filter after cooling, wash and dry to obtain the functional modified nanoparticles.

9. The modified rosin castor oil-based polyurethane degradable hot melt adhesive according to claim 8, characterized in that: The molar ratio of the 1,2-benzisothiazol-3-one to 3,5-dibromobenzyl alcohol is 2:1, and the molar ratio of the hexachlorocyclotriphosphazene, intermediate A and 3-aminopropyltriethoxysilane is 1:1:

5.

10. The method for preparing the modified rosin castor oil-based polyurethane degradable hot melt adhesive according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1. Mix castor oil modified polyurethane and modified rosin resin, heat to 125°C to completely melt the materials, dehydrate in air for 1 hour, and then release the vacuum; S2. Then add functional modified nanoparticles, ammonium polyphosphate, aluminum hydroxide, plasticizer and antioxidant in sequence, stir for 2-3 hours, vacuum degassing until no bubbles appear in the system, and then discharge the material.

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