A high-bio-based-content self-repairing cold seal adhesive and a preparation method thereof

Abstract

This invention relates to the field of packaging material adhesives, specifically to a high-bio-based self-healing cold sealant and its preparation method, addressing the problems of insufficient environmental friendliness, poor reliability, and difficulty in achieving satisfactory interfacial performance in existing cold sealants. The main raw material of this preparation method is a bio-based polyurethane prepolymer. By using bio-based polyols to replace a portion of the petroleum-based polyol raw materials, the dependence on fossil resources is significantly reduced, improving the biodegradability of the cold sealant. Adding a dynamic crosslinking agent constructs a crosslinking network based on dynamic covalent bonds, giving the cold sealant excellent self-healing properties, greatly enhancing the packaging's resistance to damage and sealing reliability during transportation. Adding an interfacial compatibilizer enables the dual function of an interfacial anchoring layer and a surface adhesive layer, fundamentally solving the contradiction between "insufficient adhesion" and "peeling residue," and further enhancing its self-healing ability.

Description

Technical Field

[0001] This invention relates to the field of packaging material adhesives, specifically to a high-bio-based self-healing cold sealant and its preparation method. Background Technology

[0002] Cold sealants are adhesives that bond without heating, using only pressure. They are widely used in the packaging of heat-sensitive items such as chocolate and pharmaceuticals. Traditional cold sealants are typically made primarily of natural rubber, synthetic rubber, or acrylate polymers, combined with tackifying resins and various additives.

[0003] However, existing cold-sealing adhesives have the following main technical defects: 1. Insufficient environmental friendliness: Traditional cold sealants mainly rely on petroleum-based synthetic resins, which are non-renewable and difficult to degrade after disposal, failing to meet the current requirements of green environmental protection and sustainable development.

[0004] 2. Poor reliability (lack of self-healing): During transportation or handling, if the seal is subjected to minor pressure or impact, micro-cracks that are difficult to detect with the naked eye can easily occur. Existing cold sealants cannot repair these damages on their own, leading to a decrease in seal strength and even quality problems such as "air leakage" and "powder leakage".

[0005] 3. Difficulty in achieving both interface performance and adhesion: In practical applications, cold sealants generally suffer from poor adhesion between the adhesive layer and the base film (such as BOPP and PET), and cohesive failure occurs during peeling, resulting in adhesive residue on the base film surface, which affects the packaging aesthetics and customer experience.

[0006] Therefore, developing a self-healing cold sealant with high bio-based content and its preparation method has significant market value. Summary of the Invention

[0007] In order to overcome the above-mentioned technical problems, the purpose of this invention is to provide a high bio-based self-healing cold sealant and its preparation method, which solves the problems of insufficient environmental protection, poor reliability and difficulty in achieving both environmental performance and interfacial properties of existing cold sealants.

[0008] The objective of this invention can be achieved through the following technical solutions: In a first aspect, this application provides a high-bio-based self-healing cold sealant, comprising the following components in parts by weight: 40-70 parts of bio-based polyurethane prepolymer, 1-10 parts of dynamic crosslinking agent, 0.5-5 parts of interface compatibilizer, 10-30 parts of tackifying resin, and 1-10 parts of filler; The bio-based polyurethane prepolymer is prepared by the following steps: The alcohol-containing monomer was added to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Nitrogen gas was introduced for protection, and the mixture was vacuum dehydrated for 1-2 hours at a temperature of 110-120℃ and a stirring rate of 200-300 r / min. Then, the temperature was lowered to 80-85℃ and diphenylmethane diisocyanate was added and stirred for 2-3 hours to obtain a bio-based polyurethane prepolymer.

[0009] In a preferred embodiment of the present invention, the interface compatibilizer is a disulfide-based fluorosiloxane.

[0010] In a preferred embodiment of the present invention, the tackifying resin is terpene resin T-100.

[0011] In a preferred embodiment of the present invention, the filler is fumed silica.

[0012] In a preferred embodiment of the present invention, the ratio of the alcohol-containing monomer to diphenylmethane diisocyanate is 90-100g:80g.

[0013] In a preferred embodiment of the present invention, the alcohol-containing monomer is a mixture of bio-based polyol and poly(1,4-butanediol adipate) in equal mass ratio; the poly(1,4-butanediol adipate) is PBA1000.

[0014] In a preferred embodiment of the present invention, the bio-based polyol is prepared by the following steps: Methanol, deionized water, and fluoroboric acid were added to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Nitrogen gas was introduced for protection, and the mixture was stirred at 20-25°C and 200-300 r / min for 30-50 min. Then, epoxidized soybean oil was added, and the mixture was heated to 50-60°C and stirred for another 5-7 h. After the reaction was completed, the product was cooled to room temperature and poured into n-hexane. The mixture was then allowed to stand and separate into layers. The organic phase was washed 2-3 times with distilled water and dried with anhydrous sodium sulfate. The mixture was then vacuum filtered, and the solvent was removed by rotary evaporation of the filtrate to obtain the bio-based polyol.

[0015] In a preferred embodiment of the present invention, the ratio of methanol, deionized water, fluoroboric acid and epoxidized soybean oil is 40-45g: 10-15mL: 1-1.5mL: 40g.

[0016] In a preferred embodiment of the present invention, the dynamic crosslinking agent is prepared by the following steps: Furan-methanol, N-(2-hydroxyethyl)maleimide, and acetone were added to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Nitrogen gas was introduced for protection, and the mixture was stirred at 20-25°C and 200-300 r / min for 20-30 min. The temperature was then raised to 60-70°C and the stirring was continued for 20-30 h. After the reaction was completed, the product was cooled to room temperature, and the solvent was removed by rotary evaporation to obtain the dynamic crosslinking agent.

[0017] In a preferred embodiment of the present invention, the ratio of furanol, N-(2-hydroxyethyl)maleimide and acetone is 20 mmol: 20 mmol: 60-70 mL.

[0018] In a preferred embodiment of the present invention, the disulfide-based fluorosiloxane is prepared by the following steps: Step a1: Add (3-chloropropyl)triethoxysilane, cystamine, potassium iodide, potassium carbonate, and toluene to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Purge with nitrogen for protection and stir the reaction at 0-5℃ and 200-300 r / min for 10-20 min. Then raise the temperature to 80-90℃ and continue stirring for 20-25 h. After the reaction is complete, cool the reaction product to room temperature, then filter under vacuum. Remove the solvent from the filtrate by rotary evaporation to obtain dithioaminosiloxane. Step a2: Dithioaminosiloxane, 2,5-dibromotrifluorinated benzene, triethylamine, and methanol are added to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Nitrogen gas is introduced for protection. The mixture is stirred and reacted for 10-20 min at a temperature of 20-25℃ and a stirring rate of 200-300 r / min. Then, the temperature is raised to 50-60℃ and the stirring is continued for 10-15 h. After the reaction is completed, the reaction product is cooled to room temperature, then vacuum filtered, and the solvent is removed by rotary evaporation of the filtrate to obtain dithiofluorosiloxane.

[0019] In a preferred embodiment of the present invention, the ratio of (3-chloropropyl)triethoxysilane, cystamine, potassium iodide, potassium carbonate and toluene in step a1 is 20 mmol: 21-25 mmol: 2-3 mmol: 40-50 mmol: 60-70 mL.

[0020] In a preferred embodiment of the present invention, the ratio of dithioaminosiloxane, 2,5-dibromotrifluoride benzene, triethylamine and methanol in step a2 is 20 mmol: 10 mmol: 30-35 mmol: 90-100 mL.

[0021] Secondly, this application provides a method for preparing a high-bio-based self-healing cold sealant, comprising the following steps: Step 1: Weigh out 40-70 parts of bio-based polyurethane prepolymer, 1-10 parts of dynamic crosslinking agent, 0.5-5 parts of interface compatibilizer, 10-30 parts of tackifying resin, and 1-10 parts of filler according to the following weight proportions, and set aside. Step 2: Add the bio-based polyurethane prepolymer, dynamic crosslinking agent, interface compatibilizer, tackifying resin and filler to a mixer, and mix for 20-40 minutes at a temperature of 20-25℃ and a stirring rate of 1000-2000 r / min to obtain a high bio-based self-healing cold sealant.

[0022] The beneficial effects of this invention are: This invention discloses a high-bio-based self-healing cold sealant and its preparation method. The method involves mixing a bio-based polyurethane prepolymer, a dynamic crosslinking agent, an interfacial compatibilizer, a tackifying resin, and fillers to obtain the high-bio-based self-healing cold sealant. The main raw material of this preparation method is the bio-based polyurethane prepolymer. By using bio-based polyols to replace part of the petroleum-based polyol raw materials, the dependence on fossil resources is significantly reduced, and the biodegradability of the cold sealant is improved. The addition of a dynamic crosslinking agent constructs a crosslinking network based on dynamic covalent bonds, giving the cold sealant excellent self-healing properties. This greatly enhances the packaging's resistance to damage and sealing reliability during transportation. The addition of an interfacial compatibilizer enables the cold sealant to function as both an interfacial anchoring layer and a surface adhesive layer, fundamentally solving the contradiction between "insufficient adhesion" and "peeling residue," and further enhancing its self-healing ability.

[0023] In the preparation of a high-bio-based self-healing cold sealant, a bio-based polyurethane prepolymer was first prepared. This was achieved by reacting methanol with the epoxy groups on epoxidized soybean oil to form multiple hydroxyl groups, yielding a bio-based polyol. Subsequently, the bio-based polyol was used to partially replace poly(1,4-butanediol adipate) in the polymerization reaction, forming a polyurethane structure and obtaining the bio-based polyurethane prepolymer. This bio-based polyurethane prepolymer, using bio-based polyol as a raw material, possesses excellent biodegradability. Furthermore, its molecular structure contains a large number of long-chain alkyl structures, which, through their flexibility, improve the flexibility and peel strength of the cold sealant.

[0024] In the process of preparing a high-bio-based self-healing cold sealant, a dynamic crosslinking agent was also prepared. Furan methanol and N-(2-hydroxyethyl)maleimide were used as raw materials to react and form Diels-Alder bonds to obtain the dynamic crosslinking agent. This dynamic crosslinking agent utilizes Diels-Alder bonds, which are dynamic covalent bonds that can form a reversible crosslinking network in the polymer backbone. When the cold sealant develops microcracks due to external forces, the dynamic covalent bonds can undergo reversible breakage and recombination under room temperature static conditions, thereby achieving self-repair of the microcracks, restoring the sealing strength, and greatly improving the packaging's resistance to damage and sealing reliability during transportation.

[0025] In the process of preparing a high-bio-based self-healing cold sealant, an interface compatibilizer was also prepared. This was achieved by reacting (3-chloropropyl)triethoxysilane with cystamine, where the chlorine atom on (3-chloropropyl)triethoxysilane reacts with an amino atom on cystamine to obtain disulfoaminosiloxane. Subsequently, the disulfoaminosiloxane was reacted with 2,5-dibromotrifluorinated benzene, where the amino atom on the disulfoaminosiloxane reacts with the bromine atom on the 2,5-dibromotrifluorinated benzene to obtain disulfofluorinated siloxane. This disulfofluorinated siloxane contains a large number of siloxane groups in its molecular structure, enabling it to tightly anchor to the substrate surface. Furthermore, the low surface energy of the fluorinated groups simultaneously enhances the adhesion of the adhesive layer to the base film and controls the location of interfacial damage during unsealing, reducing the sealant residue rate. Moreover, the disulfide bonds in its molecular structure are dynamic covalent bonds, further enhancing the self-healing ability of the cold sealant. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] Example 1:

[0028] This embodiment describes a method for preparing a high-bio-based self-healing cold sealant, comprising the following steps: Step S1: Add 40g methanol, 10mL deionized water and 1mL fluoroboric acid to a three-necked flask equipped with a stirrer, thermometer and gas delivery tube. Purge with nitrogen for protection and stir at 20℃ and 200r / min for 30min. Then add 40g epoxidized soybean oil and continue stirring at 50℃ for 5h. After the reaction is complete, cool the reaction product to room temperature and pour it into n-hexane. After standing and separating the layers, wash the organic phase twice with distilled water and dry with anhydrous sodium sulfate. Then filter under vacuum and remove the solvent by rotary evaporation to obtain bio-based polyol. Step S2: Add 90g of alcohol-containing monomer to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Purge with nitrogen for protection and dehydrate under vacuum for 1 hour at 110℃ and a stirring rate of 200 r / min. Then cool to 80℃ and add 80g of diphenylmethane diisocyanate, stirring for 2 hours to obtain a bio-based polyurethane prepolymer. The alcohol-containing monomer is a mixture of bio-based polyol and poly(1,4-butanediol adipate) in equal mass ratios. The poly(1,4-butanediol adipate) is PBA1000. Step S3: Add 20 mmol of furanol, 20 mmol of N-(2-hydroxyethyl)maleimide and 60 mL of acetone to a three-necked flask equipped with a stirrer, thermometer and gas delivery tube. Purge with nitrogen for protection and stir at 20 °C and 200 r / min for 20 min. Then raise the temperature to 60 °C and continue stirring for 20 h. After the reaction is completed, cool the reaction product to room temperature and then remove the solvent by rotary evaporation to obtain the dynamic crosslinking agent. Step S4: 20 mmol (3-chloropropyl)triethoxysilane, 21 mmol cystamine, 2 mmol potassium iodide, 40 mmol potassium carbonate and 60 mL toluene were added to a three-necked flask equipped with a stirrer, thermometer and gas delivery tube. Nitrogen gas was introduced for protection. The mixture was stirred at 0 °C and 200 r / min for 10 min. Then the temperature was raised to 80 °C and the mixture was stirred for 20 h. After the reaction was completed, the reaction product was cooled to room temperature and then filtered under vacuum. The solvent was removed by rotary evaporation of the filtrate to obtain dithioaminosiloxane. Step S5: Add 20 mmol of dithioaminosiloxane, 10 mmol of 2,5-dibromotrifluorinated benzene, 30 mmol of triethylamine and 90 mL of methanol to a three-necked flask equipped with a stirrer, thermometer and gas delivery tube. Purge with nitrogen for protection and stir at 20 °C and 200 r / min for 10 min. Then raise the temperature to 50 °C and continue stirring for 10 h. After the reaction is complete, cool the reaction product to room temperature, then filter under vacuum. Remove the solvent by rotary evaporation of the filtrate to obtain dithiofluorosiloxane. Step S6: Weigh out 40 parts by weight of bio-based polyurethane prepolymer, 1 part by weight of dynamic crosslinking agent, 0.5 parts by weight of interface compatibilizer, 10 parts by weight of tackifying resin and 1 part by weight, and set aside; the interface compatibilizer is disulfide-based fluorosiloxane; the tackifying resin is terpene resin T-100; the filler is fumed silica. Step S7: Add the bio-based polyurethane prepolymer, dynamic crosslinking agent, interface compatibilizer, tackifying resin and filler into a mixer, and stir and mix for 20 minutes at a temperature of 20℃ and a stirring rate of 1000r / min to obtain a high bio-based self-healing cold sealant.

[0029] Example 2:

[0030] This embodiment describes a method for preparing a high-bio-based self-healing cold sealant, comprising the following steps: Step S1: Add 42g methanol, 12mL deionized water and 1.2mL fluoroboric acid to a three-necked flask equipped with a stirrer, thermometer and gas delivery tube. Purge with nitrogen for protection and stir at 22℃ and 250r / min for 40min. Then add 40g epoxidized soybean oil and continue stirring at 55℃ for 6h. After the reaction is complete, cool the reaction product to room temperature and pour it into n-hexane. After standing and separating the layers, wash the organic phase twice with distilled water and dry with anhydrous sodium sulfate. Then filter under vacuum and remove the solvent by rotary evaporation to obtain bio-based polyol. Step S2: Add 95g of alcohol-containing monomer to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Purge with nitrogen for protection and vacuum dehydrate at 115℃ and a stirring rate of 250r / min for 1.5h. Then cool to 82℃ and add 80g of diphenylmethane diisocyanate, stirring for 2.5h to obtain a bio-based polyurethane prepolymer. The alcohol-containing monomer is a mixture of bio-based polyol and poly(1,4-butanediol adipate) in equal mass ratios. The poly(1,4-butanediol adipate) is PBA1000. Step S3: Add 20 mmol of furanol, 20 mmol of N-(2-hydroxyethyl)maleimide and 65 mL of acetone to a three-necked flask equipped with a stirrer, thermometer and gas delivery tube. Purge with nitrogen for protection and stir at 22 °C and 250 r / min for 25 min. Then raise the temperature to 65 °C and continue stirring for 25 h. After the reaction is completed, cool the reaction product to room temperature and then remove the solvent by rotary evaporation to obtain the dynamic crosslinking agent. Step S4: 20 mmol (3-chloropropyl)triethoxysilane, 23 mmol cystamine, 2.5 mmol potassium iodide, 45 mmol potassium carbonate and 65 mL toluene were added to a three-necked flask equipped with a stirrer, thermometer and gas delivery tube. Nitrogen gas was introduced for protection. The mixture was stirred at 3 °C and 250 r / min for 15 min. Then the temperature was raised to 85 °C and the mixture was stirred for 22 h. After the reaction was completed, the reaction product was cooled to room temperature and then filtered under vacuum. The solvent was removed by rotary evaporation of the filtrate to obtain dithioaminosiloxane. Step S5: 20 mmol of dithioaminosiloxane, 10 mmol of 2,5-dibromotrifluorinated benzene, 32 mmol of triethylamine and 95 mL of methanol were added to a three-necked flask equipped with a stirrer, thermometer and gas delivery tube. Nitrogen gas was introduced for protection. The mixture was stirred at 22 °C and 250 r / min for 15 min. Then the temperature was raised to 55 °C and the mixture was stirred for 12 h. After the reaction was completed, the reaction product was cooled to room temperature and then filtered under vacuum. The solvent was removed by rotary evaporation of the filtrate to obtain dithiofluorosiloxane. Step S6: Weigh out 55 parts by weight of bio-based polyurethane prepolymer, 5.5 parts by weight of dynamic crosslinking agent, 3 parts by weight of interface compatibilizer, 20 parts by weight of tackifying resin and 5.5 parts by weight, and set aside; the interface compatibilizer is disulfide-based fluorosiloxane; the tackifying resin is terpene resin T-100; the filler is fumed silica. Step S7: Add the bio-based polyurethane prepolymer, dynamic crosslinking agent, interface compatibilizer, tackifying resin and filler to a mixer, and stir and mix for 30 minutes at a temperature of 22℃ and a stirring rate of 1500r / min to obtain a high bio-based self-healing cold sealant.

[0031] Example 3:

[0032] This embodiment describes a method for preparing a high-bio-based self-healing cold sealant, comprising the following steps: Step S1: Add 45g methanol, 15mL deionized water and 1.5mL fluoroboric acid to a three-necked flask equipped with a stirrer, thermometer and gas delivery tube. Purge with nitrogen for protection and stir at 25℃ and 300r / min for 50min. Then add 40g epoxidized soybean oil and continue stirring at 60℃ for 7h. After the reaction is complete, cool the reaction product to room temperature and pour it into n-hexane. After standing and separating the layers, wash the organic phase three times with distilled water and dry it with anhydrous sodium sulfate. Then filter under vacuum and remove the solvent by rotary evaporation to obtain bio-based polyol. Step S2: Add 100g of alcohol-containing monomer to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Purge with nitrogen for protection and vacuum dehydrate at 120℃ and a stirring rate of 300r / min for 2 hours. Then cool to 85℃ and add 80g of diphenylmethane diisocyanate, stirring for 3 hours to obtain a bio-based polyurethane prepolymer. The alcohol-containing monomer is a mixture of bio-based polyol and poly(1,4-butanediol adipate) in equal mass ratios. The poly(1,4-butanediol adipate) is PBA1000. Step S3: Add 20 mmol of furanol, 20 mmol of N-(2-hydroxyethyl)maleimide and 70 mL of acetone to a three-necked flask equipped with a stirrer, thermometer and gas delivery tube. Purge with nitrogen for protection and stir at 25 °C and 300 r / min for 30 min. Then raise the temperature to 70 °C and continue stirring for 30 h. After the reaction is completed, cool the reaction product to room temperature and then remove the solvent by rotary evaporation to obtain the dynamic crosslinking agent. Step S4: 20 mmol (3-chloropropyl)triethoxysilane, 25 mmol cystamine, 3 mmol potassium iodide, 50 mmol potassium carbonate and 70 mL toluene were added to a three-necked flask equipped with a stirrer, thermometer and gas delivery tube. Nitrogen gas was introduced for protection. The mixture was stirred at 5 °C and 300 r / min for 20 min. Then the temperature was raised to 90 °C and the mixture was stirred for 25 h. After the reaction was completed, the reaction product was cooled to room temperature and then filtered under vacuum. The solvent was removed by rotary evaporation of the filtrate to obtain dithioaminosiloxane. Step S5: Add 20 mmol of dithioaminosiloxane, 10 mmol of 2,5-dibromotrifluorinated benzene, 35 mmol of triethylamine and 100 mL of methanol to a three-necked flask equipped with a stirrer, thermometer and gas delivery tube. Purge with nitrogen for protection and stir at 25 °C and 300 r / min for 20 min. Then raise the temperature to 60 °C and continue stirring for 15 h. After the reaction is complete, cool the reaction product to room temperature, then filter under vacuum. Remove the solvent by rotary evaporation of the filtrate to obtain dithiofluorosiloxane. Step S6: Weigh out 70 parts by weight of bio-based polyurethane prepolymer, 10 parts by dynamic crosslinking agent, 5 parts by weight of interface compatibilizer, 30 parts by weight of tackifying resin and 10 parts by weight, and set aside; the interface compatibilizer is disulfide-based fluorosiloxane; the tackifying resin is terpene resin T-100; the filler is fumed silica. Step S7: Add the bio-based polyurethane prepolymer, dynamic crosslinking agent, interface compatibilizer, tackifying resin and filler to a mixer, and mix for 40 minutes at a temperature of 25°C and a stirring rate of 2000 r / min to obtain a high bio-based self-healing cold sealant.

[0033] Comparative Example 1: This comparative example demonstrates a method for preparing a high-bio-based self-healing cold sealant, comprising the following steps: Step S1: Add 100g of alcohol-containing monomer to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Purge with nitrogen for protection and vacuum dehydrate at 120℃ and a stirring rate of 300r / min for 2 hours. Then cool to 85℃ and add 80g of diphenylmethane diisocyanate, stirring for 3 hours to obtain a bio-based polyurethane prepolymer. The alcohol-containing monomer is poly(1,4-butanediol adipate) diol; the poly(1,4-butanediol adipate) diol is PBA1000. Step S2: Weigh out 70 parts by weight of bio-based polyurethane prepolymer, 30 parts by weight of tackifying resin and 10 parts by weight, and set aside; the tackifying resin is terpene resin T-100; the filler is fumed silica. Step S3: Add the bio-based polyurethane prepolymer, tackifying resin and filler to the mixer and mix for 40 minutes at a temperature of 25°C and a stirring rate of 2000 r / min to obtain a high bio-based self-healing cold sealant.

[0034] Comparative Example 2: This comparative example demonstrates a method for preparing a high-bio-based self-healing cold sealant, comprising the following steps: Step S1: Add 45g methanol, 15mL deionized water and 1.5mL fluoroboric acid to a three-necked flask equipped with a stirrer, thermometer and gas delivery tube. Purge with nitrogen for protection and stir at 25℃ and 300r / min for 50min. Then add 40g epoxidized soybean oil and continue stirring at 60℃ for 7h. After the reaction is complete, cool the reaction product to room temperature and pour it into n-hexane. After standing and separating the layers, wash the organic phase three times with distilled water and dry it with anhydrous sodium sulfate. Then filter under vacuum and remove the solvent by rotary evaporation to obtain bio-based polyol. Step S2: Add 100g of alcohol-containing monomer to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Purge with nitrogen for protection and vacuum dehydrate at 120℃ and a stirring rate of 300r / min for 2 hours. Then cool to 85℃ and add 80g of diphenylmethane diisocyanate, stirring for 3 hours to obtain a bio-based polyurethane prepolymer. The alcohol-containing monomer is a mixture of bio-based polyol and poly(1,4-butanediol adipate) in equal mass ratios. The poly(1,4-butanediol adipate) is PBA1000. Step S3: 20 mmol (3-chloropropyl)triethoxysilane, 25 mmol cystamine, 3 mmol potassium iodide, 50 mmol potassium carbonate and 70 mL toluene were added to a three-necked flask equipped with a stirrer, thermometer and gas delivery tube. Nitrogen gas was introduced for protection. The mixture was stirred at 5 °C and 300 r / min for 20 min. Then the temperature was raised to 90 °C and the mixture was stirred for 25 h. After the reaction was completed, the reaction product was cooled to room temperature and then filtered under vacuum. The solvent was removed by rotary evaporation of the filtrate to obtain dithioaminosiloxane. Step S4: 20 mmol of dithioaminosiloxane, 10 mmol of 2,5-dibromotrifluorinated benzene, 35 mmol of triethylamine and 100 mL of methanol were added to a three-necked flask equipped with a stirrer, thermometer and gas delivery tube. Nitrogen gas was introduced for protection. The mixture was stirred at 25 °C and 300 r / min for 20 min. Then the temperature was raised to 60 °C and the mixture was stirred for 15 h. After the reaction was completed, the product was cooled to room temperature and then filtered under vacuum. The solvent was removed by rotary evaporation of the filtrate to obtain dithiofluorosiloxane. Step S5: Weigh out 70 parts by weight of bio-based polyurethane prepolymer, 5 parts by weight of interface compatibilizer, 30 parts by weight of tackifying resin and 10 parts by weight, and set aside; the interface compatibilizer is disulfide-based fluorosiloxane; the tackifying resin is terpene resin T-100; the filler is fumed silica. Step S6: Add the bio-based polyurethane prepolymer, interface compatibilizer, tackifying resin and filler to the mixer, and stir and mix for 40 minutes at a temperature of 25℃ and a stirring rate of 2000r / min to obtain a high bio-based self-healing cold sealant.

[0035] Comparative Example 3: This comparative example demonstrates a method for preparing a high-bio-based self-healing cold sealant, comprising the following steps: Step S1: Add 45g methanol, 15mL deionized water and 1.5mL fluoroboric acid to a three-necked flask equipped with a stirrer, thermometer and gas delivery tube. Purge with nitrogen for protection and stir at 25℃ and 300r / min for 50min. Then add 40g epoxidized soybean oil and continue stirring at 60℃ for 7h. After the reaction is complete, cool the reaction product to room temperature and pour it into n-hexane. After standing and separating the layers, wash the organic phase three times with distilled water and dry it with anhydrous sodium sulfate. Then filter under vacuum and remove the solvent by rotary evaporation to obtain bio-based polyol. Step S2: Add 100g of alcohol-containing monomer to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Purge with nitrogen for protection and vacuum dehydrate at 120℃ and a stirring rate of 300r / min for 2 hours. Then cool to 85℃ and add 80g of diphenylmethane diisocyanate, stirring for 3 hours to obtain a bio-based polyurethane prepolymer. The alcohol-containing monomer is a mixture of bio-based polyol and poly(1,4-butanediol adipate) in equal mass ratios. The poly(1,4-butanediol adipate) is PBA1000. Step S3: Add 20 mmol of furanol, 20 mmol of N-(2-hydroxyethyl)maleimide and 70 mL of acetone to a three-necked flask equipped with a stirrer, thermometer and gas delivery tube. Purge with nitrogen for protection and stir at 25 °C and 300 r / min for 30 min. Then raise the temperature to 70 °C and continue stirring for 30 h. After the reaction is completed, cool the reaction product to room temperature and then remove the solvent by rotary evaporation to obtain the dynamic crosslinking agent. Step S4: Weigh out 70 parts by weight of bio-based polyurethane prepolymer, 10 parts by dynamic crosslinking agent, 30 parts by weight of tackifying resin and 10 parts by weight, and set aside; the tackifying resin is terpene resin T-100; the filler is fumed silica. Step S5: Add the bio-based polyurethane prepolymer, dynamic crosslinking agent, tackifying resin and filler to a mixer and mix for 40 minutes at a temperature of 25°C and a stirring rate of 2000 r / min to obtain a high bio-based self-healing cold sealant.

[0036] The high-bio-based self-healing cold sealants of Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests, and the test results are shown in the table below:

[0037] Referring to the data in the table above, and based on the comparison between Examples 1-3 and Comparative Examples 1-3, it can be seen that the high bio-based self-healing cold sealant of this application has good adhesion and repair properties, and low residue after peeling.

[0038] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0039] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in this application, they should all fall within the protection scope of the present invention.

Claims

1. A self-healing cold sealant with high bio-based content, characterized in that, Includes the following components by weight: 40-70 parts of bio-based polyurethane prepolymer, 1-10 parts of dynamic crosslinking agent, 0.5-5 parts of interface compatibilizer, 10-30 parts of tackifying resin, and 1-10 parts of filler; The bio-based polyurethane prepolymer is prepared by the following steps: The alcohol-containing monomer was added to a three-necked flask equipped with a stirrer, thermometer and gas delivery tube. Nitrogen gas was introduced for protection. The mixture was vacuum dehydrated for 1-2 hours at a temperature of 110-120℃ and a stirring rate of 200-300 r / min. Then the temperature was lowered to 80-85℃ and diphenylmethane diisocyanate was added and stirred for 2-3 hours to obtain a bio-based polyurethane prepolymer. The interface compatibilizer is a disulfide-based fluorosiloxane; The tackifying resin is terpene resin T-100; The filler is fumed silica.

2. The high bio-based self-healing cold sealant according to claim 1, characterized in that, The ratio of the alcohol-containing monomer to diphenylmethane diisocyanate is 90-100g:80g; the alcohol-containing monomer is a mixture of bio-based polyol and poly(1,4-butanediol adipate) in equal mass ratio; the poly(1,4-butanediol adipate) is PBA1000.

3. The high bio-based self-healing cold sealant according to claim 2, characterized in that, The bio-based polyol is prepared by the following steps: Methanol, deionized water, and fluoroboric acid were stirred and reacted. Then, epoxidized soybean oil was added and the reaction was continued with stirring. After the reaction was completed, the reaction product was cooled and poured into n-hexane. After standing and separating into layers, the organic phase was washed, dried, and then filtered under vacuum. The filtrate was then evaporated by rotary evaporation to obtain bio-based polyol.

4. The high bio-based self-healing cold sealant according to claim 3, characterized in that, The ratio of methanol, deionized water, fluoroboric acid, and epoxidized soybean oil is 40-45g: 10-15mL: 1-1.5mL: 40g.

5. The high bio-based self-healing cold sealant according to claim 1, characterized in that, The dynamic crosslinking agent is prepared by the following steps: Furan methanol, N-(2-hydroxyethyl)maleimide and acetone were stirred and reacted. After the reaction was completed, the reaction product was cooled and then rotary evaporated to obtain a dynamic crosslinking agent.

6. The high bio-based self-healing cold sealant according to claim 5, characterized in that, The ratio of furanol, N-(2-hydroxyethyl)maleimide, and acetone used is 20 mmol: 20 mmol: 60-70 mL.

7. The high bio-based self-healing cold sealant according to claim 1, characterized in that, The disulfide-based fluorosiloxane is prepared by the following steps: Step a1: (3-chloropropyl)triethoxysilane, cystamine, potassium iodide, potassium carbonate and toluene were stirred and reacted. After the reaction was completed, the reaction product was cooled and then filtered under vacuum. The filtrate was evaporated by rotary evaporation to obtain dithioaminosiloxane. Step a2: Disulfoaminosiloxane, 2,5-dibromotrifluorinated benzene, triethylamine and methanol are stirred and reacted. After the reaction is completed, the reaction product is cooled, then vacuum filtered, and the filtrate is evaporated by rotary evaporation to obtain disulfofluorosiloxane.

8. The high bio-based self-healing cold sealant according to claim 7, characterized in that, The ratio of (3-chloropropyl)triethoxysilane, cystamine, potassium iodide, potassium carbonate, and toluene in step a1 is 20 mmol: 21-25 mmol: 2-3 mmol: 40-50 mmol: 60-70 mL.

9. The high bio-based self-healing cold sealant according to claim 7, characterized in that, The ratio of dithioaminosiloxane, 2,5-dibromotrifluoride benzene, triethylamine and methanol used in step a2 is 20 mmol: 10 mmol: 30-35 mmol: 90-100 mL.

10. A method for preparing a high-bio-based self-healing cold sealant as described in any one of claims 1-9, characterized in that, Includes the following steps: Step 1: Weigh out 40-70 parts of bio-based polyurethane prepolymer, 1-10 parts of dynamic crosslinking agent, 0.5-5 parts of interface compatibilizer, 10-30 parts of tackifying resin, and 1-10 parts of filler according to the following weight proportions, and set aside. Step 2: Add the bio-based polyurethane prepolymer, dynamic crosslinking agent, interface compatibilizer, tackifying resin and filler to a mixer, and mix for 20-40 minutes at a temperature of 20-25℃ and a stirring rate of 1000-2000 r / min to obtain a high bio-based self-healing cold sealant.

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