Hydrolysis-resistant bio-based polyester polyol modified waterborne polyurethane adhesive

Abstract

The invention discloses a hydrolysis-resistant bio-based polyester polyol modified waterborne polyurethane adhesive, belongs to the technical field of adhesive preparation, and is used for solving the technical problem that the hydrolysis resistance and the adhesive property of a waterborne polyurethane adhesive in the prior art need to be further improved. Furan carbonate-polyester polyol is used as a matrix, phosphorus-silicon cross-linked flame-retardant polyol and a modified curing agent are used as auxiliary materials to construct a multi-layer cross-linked structure, a furan carbonate unit is introduced into a main chain to improve the rigidity and polarity matching of a molecular chain, and an organic-inorganic stable network is formed by using the phosphorus-silicon cross-linked structure; according to the preparation method, the polyurethane is taken as a raw material, and post-crosslinking densification is realized through the modified curing agent, so that chain segment migration and hydrolysis reaction are effectively inhibited, the interface bonding stability and thermal oxidation tolerance are improved, and the prepared polyurethane adhesive has high shear strength, excellent flame retardance and excellent damp-heat aging retention rate and balanced and stable performance at the same time.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of adhesive preparation, in particular to a hydrolysis-resistant bio-based polyester polyol modified waterborne polyurethane adhesive. BACKGROUND

[0002] Polyurethane adhesives are widely used in the field of metal, rubber, plastic and composite bonding due to their excellent flexibility, bonding strength and wide application range. Early systems mainly rely on the reaction of polyester or polyether polyols with isocyanate to form linear or lightly crosslinked structures to obtain high initial adhesion and peel strength. With the expansion of application fields, research has gradually shifted to molecular structure regulation. By introducing high-polarity segments, increasing hydrogen bond density and optimizing the hard-soft segment ratio, the energy matching of the bonding interface is improved, thereby improving impact resistance and long-term service stability. At the same time, the hydrolysis resistance of polyurethane adhesives has long been affected by the easy breaking of ester bonds and the migration of segments. In order to slow down the degradation process, researchers have developed carbonate, fluorinated and silicon-containing modified polyol systems, and introduced end group blocking, crosslinking density adjustment and inorganic filler synergistic strategies to reduce hydrophilicity and improve interface stability. In recent years, through molecular design and chemical modification means, double protection against thermal oxidation and hygrothermal degradation has been achieved, making the structure retention and bonding durability of polyurethane adhesives in high temperature and high humidity environments continue to improve.

[0003] The existing polyurethane adhesive system still has the problem of insufficient structural stability under long-term service conditions. Conventional polyester or polyether polyols are prone to ester bond or ether bond rupture in a hygrothermal environment, leading to molecular chain degradation and crosslinking network relaxation, which in turn causes the bonding interface strength to decrease. Although some systems enhance hydrolysis resistance by increasing crosslinking density, excessive crosslinking degree can make the material brittle, affecting the initial shear and peel performance, and it is difficult to balance strength and durability. In addition, traditional flame retardant modification mainly uses external or single element type flame retardants, which are prone to migration or uneven dispersion during processing, resulting in loose carbon layer structure and insufficient thermal stability during combustion. At the same time, the incomplete reaction of some systems during the curing stage, the residual active groups and hydrophilic end groups are prone to moisture absorption or reaction with the environment, accelerating the aging process. These factors together limit the long-term reliable application of polyurethane adhesives in high temperature, high humidity and flame retardant requirement scenarios.

[0004] In view of the technical defects in this regard, a solution is now proposed. SUMMARY

[0005] The purpose of the present application is to provide a hydrolysis-resistant bio-based polyester polyol modified waterborne polyurethane adhesive, which solves the technical problem that the hydrolysis resistance and bonding performance of the waterborne polyurethane adhesive in the prior art need to be further improved.

[0006] The purpose of the present application can be achieved by the following technical solutions:

[0007] A hydrolysis-resistant bio-based polyester polyol modified waterborne polyurethane adhesive, comprising the following raw material composition in parts by weight: 100 parts of a waterborne polyurethane main agent dispersion and 2-3 modified curing agents;

[0008] The preparation method of the waterborne polyurethane main agent dispersion comprises the following steps:

[0009] S1, furan carbonate-polyester polyol, phosphorus-silicon crosslinking flame retardant polyol, dimethylol propionic acid and dibutyl tin dilaurate are added into a reaction kettle and stirred, and then a calculated amount of isosorbide diisocyanate is added after nitrogen protection, and the temperature of the reaction kettle is raised to 80-85℃, and the temperature is kept for 3-4h, and then cooled to room temperature after the reaction is completed, and collected for standby, to obtain a carboxyl NCO terminated prepolymer;

[0010] S2, the carboxyl NCO terminated prepolymer, 2-amino-2-methyl-1-propanol and deionized water are added into the reaction kettle and stirred, the reaction kettle is heated to 55-60℃, and kept stirring for 40-60min, then after stirring, it is placed and defoamed, and then filtered through an 80 mesh filter screen to obtain a waterborne polyurethane main agent dispersion.

[0011] The reaction principle for preparing the waterborne polyurethane main agent dispersion is:

[0012] Firstly, isosorbide diisocyanate reacts with furan carbonate-polyester polyol, phosphorus-silicon crosslinking flame retardant polyol and dimethylol propionic acid in the system to form a polyurethane main chain structure containing urethane bond (-NHCOO-), which is a typical isocyanate-hydroxyl addition reaction, and dibutyl tin dilaurate acts as a catalyst in this process to promote the nucleophilic addition between -NCO and -OH, and since the DMPA molecule contains both hydroxyl and carboxyl groups, the terminal carboxyl group is introduced after the reaction, so that the prepolymer forms a carboxyl NCO terminated prepolymer with hydrophilic groups;

[0013] Subsequently, 2-amino-2-methyl-1-propanol and deionized water are added, the amino group in 2-amino-2-methyl-1-propanol reacts with the residual -NCO groups in the prepolymer to form a urea bond (-NHCONH–-), and at the same time the carboxyl group is neutralized to form a carboxylate, so that the polyurethane molecule has self-emulsifying ability, and then in the stirring and defoaming process, the prepolymer is dispersed in the water phase to form a stable waterborne polyurethane dispersion.

[0014] Further, in step S1, the furan carbonate-polyester polyol, phosphorus-silicon crosslinking flame retardant polyol, dimethylol propionic acid and dibutyl tin dilaurate are 40-50g:2-3mL:1g:0.02mL, and the addition amount of isosorbide diisocyanate is 0.8-0.9 times the molar amount of hydroxyl groups in the reaction system;

[0015] Further, in step S2, the amount of the carboxyl NCO-terminated prepolymer, 2-amino-2-methyl-1-propanol and deionized water is 40 g: 1 mL: 80-100 mL.

[0016] Further, the preparation method of the furan carbonate-polyester polyol comprises the following steps:

[0017] A1, acetylated furan diol, dimethyl carbonate, potassium carbonate and toluene are added to the reaction kettle and stirred, after nitrogen protection, the reaction kettle is heated to 105-115℃, and the reaction is stirred for 4-6h, and the furan carbonate-polyester polyol is obtained by post-treatment.

[0018] A2, the carbonate furan diol precursor, 1,4-butanediol, dimethylol propionic acid, dibutyltin dilaurate and cyclohexanone are added to the reaction kettle, and the reaction kettle is heated to 150-170℃ after nitrogen protection, and the reaction is stirred for 4-6h, and the furan carbonate-polyester polyol is obtained by post-treatment.

[0019] The reaction principle for preparing the furan carbonate-polyester polyol is:

[0020] Firstly, the acetylated furan diol is subjected to ester exchange reaction under the action of dimethyl carbonate and potassium carbonate, the hydroxyl group is substituted with the methoxyl group in dimethyl carbonate to form carbonate bond, thereby forming the carbonate furan diol precursor, and the process is essentially an activated carbonate reaction of dimethyl carbonate on hydroxyl compounds; subsequently, in the second stage, the carbonate furan diol precursor is subjected to polycondensation reaction with 1,4-butanediol and dimethylol propionic acid under the catalysis of the catalyst dibutyltin dilaurate, thereby generating the carbonate-polyester polyol containing furan ring structure, and the reaction realizes molecular chain growth through esterification and transesterification between the hydroxyl group and the carbonate or carboxylic acid functional group, thereby forming the linear polyester structure with coexisting carbonate and ester bonds.

[0021] Further, in step A1, the amount of the acetylated furan diol, dimethyl carbonate, potassium carbonate and toluene is 2-3g: 12mL: 0.03g: 12-15mL, and the post-treatment comprises: after the reaction is completed, the reaction kettle is cooled to room temperature, the reaction liquid is transferred to a rotary evaporator with a temperature of 80℃, and vacuum distillation is performed until no liquid is collected, thereby obtaining the carbonate furan diol precursor;

[0022] Further, in step A2, the amount ratio of the carbonated furan diol precursor, 1,4-butanediol, dimethylol propionic acid, dibutyl tin dilaurate and cyclohexanone is 4-5 g:2 mL:0.5 g:0.003-0.005 mL:8-10 mL, and the post-treatment includes: after the reaction is completed, the reaction kettle is cooled to room temperature, the reaction solution is transferred to a rotary evaporator with a temperature of 80°C, and is distilled under reduced pressure until no liquid is collected, to obtain the furan carbonate-polyester polyol.

[0023] Further, the preparation method of the acetylated furan diol includes the following steps:

[0024] B1, stirring the fructose, dimethyl sulfoxide, p-toluenesulfonic acid and acetic anhydride in a reaction kettle, after nitrogen protection, the reaction kettle is heated to 120-135°C, and is kept for 2-3 h, and the acetylated furan aldehyde is obtained after post-treatment;

[0025] B2, the acetylated furan aldehyde and methanol are added to the reaction kettle, the temperature of the reaction kettle is reduced to 0-5°C, and sodium borohydride is added, then the reaction kettle is raised to 20-30°C, and is kept for 1-2 h, after stirring is completed, acetic acid is added and is placed for 10 min, and the acetylated furan diol is obtained after post-treatment.

[0026] The reaction principle for preparing the acetylated furan diol is as follows:

[0027] Firstly, the fructose is dehydrated and acetylated under the joint action of acetic anhydride and p-toluenesulfonic acid, and the internal hydroxyl group of the sugar molecule is acetylated to generate the acetylated furan aldehyde with a furan ring structure; then, the acetylated furan aldehyde is reduced in the presence of sodium borohydride, the aldehyde group is converted into a hydroxyl group, and the corresponding acetylated furan diol is generated, in this process, the methanol acts as a solvent to provide a reaction medium, and the acetic acid is used to adjust the acidity of the system and terminate the reduction reaction, and the whole process realizes the structural conversion from the sugar raw material to the acetylated furan diol through basic organic transformations such as dehydration, cyclization, acetylation and reduction.

[0028] Further, in step B1, the amount ratio of the fructose, dimethyl sulfoxide, p-toluenesulfonic acid and acetic anhydride is 8-10 g:25-30 mL:0.1 g:6 mL, and the post-treatment includes: after the reaction is completed, the reaction kettle is cooled to room temperature, 2 times the volume of deionized water is added for dilution, the product is extracted with ethyl acetate for 3 times, then the organic phases are combined, dried with anhydrous sodium sulfate, and distilled under reduced pressure until no liquid is collected, to obtain the acetylated furan aldehyde;

[0029] Further, in step B2, the acetylated furan aldehyde, methanol, sodium borohydride and acetic acid are used in a ratio of 5g:20mL:0.3g:0.3mL, and the post-treatment includes: after the reaction is completed, dilute with 2 times the volume of deionized water, then extract the product with ethyl acetate 3 times, combine the organic phases, dry over anhydrous sodium sulfate and distill under reduced pressure until no liquid is collected to obtain acetylated furan diol.

[0030] Further, the preparation method of the phosphorus-silicon crosslinking flame-retardant polyol comprises the following steps:

[0031] C1, the epoxidized soybean oil, dimethyl phosphite, triphenylphosphine and o-xylene are stirred in a reaction kettle, nitrogen is introduced for protection, then the reaction kettle is heated to 90-100℃, and stirred for 4-6h, and the post-treatment is performed to obtain phosphorus-containing hydroxylated soybean oil polyol;

[0032] C2, the phosphorus-containing hydroxylated soybean oil polyol, 3-(2,3-epoxypropoxy) propyl trimethoxysilane and triethylamine are stirred in a reaction kettle, nitrogen is introduced for protection, then the reaction kettle is heated to 90-100℃, and stirred for 3-5h, and after the reaction is completed, the reaction kettle is left to stand and defoamed to obtain the phosphorus-silicon crosslinking flame-retardant polyol.

[0033] The reaction principle for preparing the phosphorus-silicon crosslinking flame-retardant polyol is as follows:

[0034] Firstly, the epoxidized soybean oil reacts with dimethyl phosphite and triphenylphosphine to form a phosphate compound, which mainly depends on the catalysis of triphenylphosphine to promote the nucleophilic substitution reaction between dimethyl phosphite and the epoxy group in the epoxidized soybean oil to generate the phosphate compound, and in this process, phosphorus element is introduced, so that the molecular structure of the soybean oil has a phosphorus functional group, thereby obtaining the phosphorus-containing hydroxylated soybean oil polyol;

[0035] Subsequently, the phosphorus-containing hydroxylated soybean oil polyol reacts with 3-(2,3-epoxypropoxy) propyl trimethoxysilane, and triethylamine is used as a catalyst to promote the ring-opening reaction between the epoxy group and the chloromethyl in the silane to form a siloxane bond, thereby realizing the crosslinking of the soybean oil polyol and the silane to form a phosphorus-silicon crosslinking structure, which not only enhances the crosslinking property of the polyol, but also effectively introduces phosphorus and silicon elements, so that the final product has good flame-retardant performance.

[0036] Further, in step C1, the epoxidized soybean oil, dimethyl phosphite, triphenylphosphine and o-xylene are used in a ratio of 80-100mL:20-25mL:1g:100mL, and the post-treatment includes: after the reaction is completed, the reaction kettle is cooled to room temperature, the reaction liquid is transferred to a rotary evaporator with a temperature of 80℃, and distilled under reduced pressure until no liquid is collected to obtain the phosphorus-containing hydroxylated soybean oil polyol;

[0037] Further, in step C2, the amount ratio of the phosphorus-containing hydroxylated soybean oil polyol, 3-(2,3-epoxypropoxy)propyl trimethoxysilane and triethylamine is 40-50 mL:5 mL:0.1 mL.

[0038] Further, the preparation method of the modified curing agent is as follows: 1,5-diaminopentane, propylene carbonate and N,N-dimethylformamide are added into a reaction kettle and stirred, the reaction kettle is protected by nitrogen, the temperature of the reaction kettle is increased to 70-80 DEG C, and the reaction kettle is kept stirring for 2-4 h, and then the modified curing agent is obtained by post-treatment.

[0039] The reaction principle for preparing the modified curing agent is as follows:

[0040] 1,5-diaminopentane and propylene carbonate undergo nucleophilic substitution reaction, in which the amino group in 1,5-diaminopentane attacks the ester group in propylene carbonate to form an amino methyl ester compound and release the corresponding alcohol, the reaction not only introduces the amine group modified functional group, but also converts the ester group in propylene carbonate, and finally the modified curing agent is prepared.

[0041] Further, the amount ratio of 1,5-diaminopentane, propylene carbonate and N,N-dimethylformamide is 12-15 mL:9 mL:60 mL, and the post-treatment includes: after the reaction is completed, the reaction solution is poured into 3 times the volume of anhydrous ethanol for precipitation, after the precipitation is completed, the reaction solution is filtered to collect the filter cake, the filter cake is transferred to a drying oven with a temperature of 50 DEG C for vacuum drying until the constant weight, and the modified curing agent is obtained.

[0042] The present application has the following advantages:

[0043] 1, the present application is constructed by the cooperation of furan carbonate-polyester polyol and phosphorus-silicon crosslinking flame-retardant polyol, rigid and flexible structural units are introduced into the polyurethane molecular chain at the same time, a high-strength network system with multi-phase micro-area distribution is formed, wherein the furan ring structure gives the molecular chain high rigidity and polarity, enhances the intermolecular hydrogen bond and van der waals force, thereby improving the cohesive force and structural stability of the adhesive layer; the introduction of phosphorus-silicon crosslinking polyol makes the system have certain flexibility and crosslinking density, improves the wettability and stress buffering capacity of the adhesive and the interface, promotes the interface combination to be more stable and firm, the cooperation of the two types of polyols at the molecular level enables the adhesive layer to realize effective stress transmission and dispersion under external force, not only enhances the shear failure resistance of the material, but also improves the resistance to interface peeling, at the same time, the carboxyl end-capped structure and the subsequent curing reaction further improve the crosslinking degree and durability of the polyurethane system, so that the adhesive layer can still maintain excellent bonding stability and mechanical integrity in complex environment, thereby realizing excellent comprehensive bonding performance.

[0044] 2、The phosphorus-silicon crosslinking flame-retardant polyol introduced in the system has the synergistic flame-retardant effect of phosphorus elements and silicon-oxygen skeleton in the molecular structure, the phosphorus elements can generate polyphosphoric acid and phosphate intermediates in the combustion process, promote the formation of a dense carbonized protective layer on the material surface, and block the further transmission of heat and oxygen; the silicon-oxygen structure is converted into an inorganic SiO2 ceramic film at high temperature, further enhancing the thermal stability and shielding effect of the carbon layer, thereby effectively inhibiting the release and combustion spread of flammable gas, at the same time, the furan carbonate groups are prone to cyclization and aromatization reaction when heated, which helps the rapid formation and structure densification of the carbon layer, significantly improves the carbonization rate of the system, and finally, through the synergistic effect of phosphorus, silicon and furan structure, the material has both gas-phase flame retardation and condensed-phase barrier effect in the combustion process, not only delays the combustion rate, but also improves the thermal and oxidative stability, through this molecular-level structure design, the adhesive has good mechanical properties while realizing excellent flame-retardant performance and safety and stability.

[0045] 3、The present application introduces a furan carbonate-polyester polyol and a phosphorus-silicon crosslinking flame-retardant polyol into the molecular structure to form a synergistic system, so that the polyurethane main chain has high chemical stability and flexibility adjustment ability, wherein the furan carbonate group has strong conjugation effect and polarity, which can increase the electron cloud density of the polyurethane segment and enhance the repellency to hydrophilic molecules, thereby inhibiting the penetration and diffusion of water in the adhesive layer; the Si-O bond in the phosphorus-silicon crosslinking structure has high bond energy and strong thermal chemical stability, and is not easy to break in a humid environment, which can effectively maintain the three-dimensional crosslinking network of the adhesive system; on the other hand, the hydrophobic side chain and flexible chain segment in the system form a microphase separation structure together, so that the local stress generated after water absorption can be released, avoiding the cracking and interfacial debonding of the adhesive layer, wherein the carboxyl-terminated and crosslinking curing reaction further increases the crosslinking density of the polyurethane network, reduces the exposure of hydrolyzable ester bonds, and enhances the hydrolysis resistance from the molecular level, finally, through the synergistic effect of various structural units, the adhesive can still maintain high bonding strength and structural stability under high temperature and high humidity conditions, and has excellent hydrolysis resistance and moisture resistance. DETAILED DESCRIPTION

[0046] The technical solutions of the present application will be described below in conjunction with the embodiments, obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

[0047] In the present application, the epoxy soybean oil used is purchased from Shanghai Maikelin Biochemical Technology Co., Ltd., and the item number is E808876.

[0048] Example 1

[0049] The embodiment provides a preparation method of furan carbonate-polyester polyol, and comprises the following steps:

[0050] Step 1, preparation of acetylated furfural

[0051] Take 80.0g of fructose, 250.0mL of dimethyl sulfoxide, 1.0g of p-toluenesulfonic acid and 60.0mL of acetic anhydride, stir in a reaction kettle, after nitrogen protection, the reaction kettle is heated to 120 DEG C, and the reaction is carried out for 2h, after the reaction is completed, the reaction kettle is cooled to room temperature, 2 times volume of deionized water is added for dilution, and then the product is extracted with ethyl acetate for 3 times, the organic phase is combined, dried with anhydrous sodium sulfate and distilled under reduced pressure until no liquid is collected, and acetylated furfural is obtained.

[0052] Step 2, preparation of acetylated furan diol

[0053] Take 50.0g of acetylated furfural and 200.0mL of methanol, stir in a reaction kettle, reduce the temperature of the reaction kettle to 0 DEG C, and then add sodium borohydride, then increase the temperature of the reaction kettle to 20 DEG C, stir for 1h, after stirring is completed, add 3.0mL of acetic acid and stand for 10min, after the reaction is completed, add 2 times volume of deionized water for dilution, extract the product with ethyl acetate for 3 times, combine the organic phase, dry with anhydrous sodium sulfate and distill under reduced pressure until no liquid is collected, and acetylated furan diol is obtained.

[0054] Step 3, preparation of carbonate furan diol precursor

[0055] Take 20.0g of acetylated furan diol, 120.0mL of dimethyl carbonate, 0.3g of potassium carbonate and 120.0mL of toluene, stir in a reaction kettle, after nitrogen protection, the reaction kettle is heated to 105 DEG C, and the reaction is carried out for 4h, after the reaction is completed, the reaction liquid is transferred to a rotary evaporator with a temperature of 80 DEG C, and distilled under reduced pressure until no liquid is collected, and carbonate furan diol precursor is obtained.

[0056] Step 4, preparation of furan carbonate-polyester polyol

[0057] Take 40.0g of carbonate furan diol precursor, 20.0mL of 1,4-butanediol, 5.0g of dimethylol propionic acid, 0.03mL of dibutyltin dilaurate and 80.0mL of cyclohexanone, stir in a reaction kettle, after nitrogen protection, the reaction kettle is heated to 150 DEG C, and the reaction is carried out for 4h, after the reaction is completed, the reaction liquid is transferred to a rotary evaporator with a temperature of 80 DEG C, and distilled under reduced pressure until no liquid is collected, and furan carbonate-polyester polyol is obtained.

[0058] Example 2

[0059] The present embodiment provides a method for preparing furan carbonate-polyester polyol, comprising the following steps:

[0060] Step 1, preparation of acetylated furfural

[0061] Take: 100.0g fructose, 300.0.0mL dimethyl sulfoxide, 1.0g p-toluenesulfonic acid and 60.0mL acetic anhydride into the reaction kettle and stir, after nitrogen protection, the reaction kettle is heated to 135℃, and the reaction is kept for 3h. After the reaction is completed, the reaction kettle is cooled to room temperature, and then diluted with 2 times the volume of deionized water. The product is extracted with ethyl acetate for 3 times, and then the organic phase is combined, dried with anhydrous sodium sulfate and distilled under reduced pressure until no liquid is collected. Acetylated furfural is obtained.

[0062] Step 2, preparation of acetylated furan diol

[0063] Take: 50.0g acetylated furfural and 200.0mL methanol into the reaction kettle, and then reduce the temperature of the reaction kettle to 5℃ and add sodium borohydride. Then, increase the temperature of the reaction kettle to 30℃, and keep stirring for 2h. After stirring is completed, add 3.0mL acetic acid and stand for 10min. After the reaction is completed, dilute with 2 times the volume of deionized water. The product is extracted with ethyl acetate for 3 times, and then the organic phase is combined, dried with anhydrous sodium sulfate and distilled under reduced pressure until no liquid is collected. Acetylated furan diol is obtained.

[0064] Step 3, preparation of carbonate furan diol precursor

[0065] Take: 30.0.0g acetylated furan diol, 120.0mL dimethyl carbonate, 0.3g potassium carbonate and 150.0mL toluene into the reaction kettle and stir, after nitrogen protection, the reaction kettle is heated to 115℃, and the reaction is kept for 6h. After the reaction is completed, the reaction liquid is transferred to a rotary evaporator with a temperature of 80℃, and distilled under reduced pressure until no liquid is collected. Carbonate furan diol precursor is obtained.

[0066] Step 4, preparation of furan carbonate-polyester polyol

[0067] Take: 50.0.0g carbonate furan diol precursor, 20.0mL 1,4-butanediol, 5.0g dimethylol propionic acid, 0.05mL dibutyltin dilaurate and 100.0mL cyclohexanone into the reaction kettle, and then increase the temperature of the reaction kettle to 170℃, and keep stirring for 6h. After the reaction is completed, the reaction liquid is transferred to a rotary evaporator with a temperature of 80℃, and distilled under reduced pressure until no liquid is collected. Furan carbonate-polyester polyol is obtained.

[0068] Example 3

[0069] The embodiment provides a preparation method of furan carbonate-polyester polyol, and comprises the following steps:

[0070] Step 1, preparation of acetylated furfural

[0071] Take 90.0g of fructose, 270.0mL of dimethyl sulfoxide, 1.0g of p-toluenesulfonic acid and 60.0mL of acetic anhydride, stir in a reaction kettle, after nitrogen protection, the reaction kettle is heated to 130 DEG C, and the reaction is carried out for 3h, after the reaction is completed, the reaction kettle is cooled to room temperature, 2 times volume of deionized water is added for dilution, and the product is extracted with ethyl acetate for 3 times, then the organic phase is combined, dried with anhydrous sodium sulfate and distilled under reduced pressure until no liquid is collected, and acetylated furfural is obtained.

[0072] Step 2, preparation of acetylated furan diol

[0073] Take 50.0g of acetylated furfural and 200.0mL of methanol, stir in a reaction kettle, reduce the temperature of the reaction kettle to 3 DEG C, and then add sodium borohydride, then increase the temperature of the reaction kettle to 25 DEG C, and stir for 2h, after stirring is completed, add 3.0mL of acetic acid and stand for 10min, after the reaction is completed, add 2 times volume of deionized water for dilution, extract the product with ethyl acetate for 3 times, combine the organic phase, dry with anhydrous sodium sulfate and distill under reduced pressure until no liquid is collected, and acetylated furan diol is obtained.

[0074] Step 3, preparation of carbonate furan diol precursor

[0075] Take 25.0g of acetylated furan diol, 120.0mL of dimethyl carbonate, 0.3g of potassium carbonate and 125.0mL of toluene, stir in a reaction kettle, after nitrogen protection, the reaction kettle is heated to 110 DEG C, and stirred for 5h, after the reaction is completed, the reaction liquid is transferred to a rotary evaporator with a temperature of 80 DEG C, and distilled under reduced pressure until no liquid is collected, and carbonate furan diol precursor is obtained.

[0076] Step 4, preparation of furan carbonate-polyester polyol

[0077] Take 45.0g of carbonate furan diol precursor, 20.0mL of 1,4-butanediol, 5.0g of dimethylol propionic acid, 0.04mL of dibutyltin dilaurate and 90.0mL of cyclohexanone, stir in a reaction kettle, after nitrogen protection, the reaction kettle is heated to 160 DEG C, and stirred for 5h, after the reaction is completed, the reaction liquid is transferred to a rotary evaporator with a temperature of 80 DEG C, and distilled under reduced pressure until no liquid is collected, and furan carbonate-polyester polyol is obtained.

[0078] Example 4

[0079] The embodiment provides a preparation method of phosphorus-silicon crosslinking flame-retardant polyol, which comprises the following steps:

[0080] Step I, preparation of phosphorus-containing hydroxylated soybean oil polyol

[0081] Take 80.0 mL of epoxidized soybean oil, 20.0 mL of dimethyl phosphite, 1.0 g of triphenylphosphine and 100.0 mL of o-xylene, stir in a reaction kettle, protect by introducing nitrogen, then heat the reaction kettle to 90 DEG C, and keep stirring for 4 h; after the reaction is completed, cool the reaction kettle to room temperature, transfer the reaction liquid to a rotary evaporator with a temperature of 80 DEG C, and distill under reduced pressure until no liquid is collected, to obtain the phosphorus-containing hydroxylated soybean oil polyol.

[0082] Step II, preparation of phosphorus-silicon crosslinking flame-retardant polyol

[0083] Take 40.0 mL of the phosphorus-containing hydroxylated soybean oil polyol, 5.0 mL of 3-(2,3-epoxypropoxy) propyl trimethoxysilane and 0.1 mL of triethylamine, stir in a reaction kettle, protect by introducing nitrogen, then heat the reaction kettle to 90 DEG C, and keep stirring for 5 h; after the reaction is completed, stand for defoaming, to obtain the phosphorus-silicon crosslinking flame-retardant polyol.

[0084] Example 5

[0085] The embodiment provides a preparation method of phosphorus-silicon crosslinking flame-retardant polyol, which comprises the following steps:

[0086] Step I, preparation of phosphorus-containing hydroxylated soybean oil polyol

[0087] Take 100.0 mL of epoxidized soybean oil, 25.0 mL of dimethyl phosphite, 1.0 g of triphenylphosphine and 100.0 mL of o-xylene, stir in a reaction kettle, protect by introducing nitrogen, then heat the reaction kettle to 100 DEG C, and keep stirring for 6 h; after the reaction is completed, cool the reaction kettle to room temperature, transfer the reaction liquid to a rotary evaporator with a temperature of 80 DEG C, and distill under reduced pressure until no liquid is collected, to obtain the phosphorus-containing hydroxylated soybean oil polyol.

[0088] Step II, preparation of phosphorus-silicon crosslinking flame-retardant polyol

[0089] Take 50.0 mL of the phosphorus-containing hydroxylated soybean oil polyol, 5.0 mL of 3-(2,3-epoxypropoxy) propyl trimethoxysilane and 0.1 mL of triethylamine, stir in a reaction kettle, protect by introducing nitrogen, then heat the reaction kettle to 100 DEG C, and keep stirring for 5 h; after the reaction is completed, stand for defoaming, to obtain the phosphorus-silicon crosslinking flame-retardant polyol.

[0090] Example 6

[0091] The embodiment provides a preparation method of phosphorus-silicon crosslinking flame-retardant polyol, which comprises the following steps:

[0092] Step I: Preparation of phosphorus-containing hydroxylated soybean oil polyols

[0093] Weigh out 90.0 mL of epoxidized soybean oil, 24.0 mL of dimethyl phosphite, 1.0 g of triphenylphosphine, and 100.0 mL of o-xylene and add them to a reaction vessel. Stir the mixture and then heat the reaction vessel to 95 °C under nitrogen protection. Keep the mixture at this temperature and stir for 5 hours. After the reaction is complete, let the reaction vessel cool to room temperature and transfer the reaction solution to a rotary evaporator at 80 °C. Distill the solution under reduced pressure until no liquid is collected, and obtain phosphorus-containing hydroxylated soybean oil polyol.

[0094] Step II: Preparation of phosphorus-silicon crosslinked flame-retardant polyols

[0095] Weigh out 45.0 mL of phosphorus-containing hydroxylated soybean oil polyol, 5.0 mL of 3-(2,3-epoxypropoxy)propyltrimethoxysilane and 0.1 mL of triethylamine and add them to the reaction vessel. Stir, purge with nitrogen, and heat the reaction vessel to 95°C. Keep the temperature and stir for 4 hours. After the reaction is complete, let it stand to remove bubbles to obtain phosphorus-silicon crosslinked flame retardant polyol.

[0096] Example 7

[0097] This embodiment provides a method for preparing a hydrolysis-resistant bio-based polyester polyol modified waterborne polyurethane adhesive, comprising the following steps:

[0098] Step 1: Preparation of carboxyl-NCO-terminated prepolymer

[0099] Weigh out 40.0g of furan carbonate-polyester polyol prepared in Example 1, 2.0mL of phosphorus-silicon crosslinked flame retardant polyol prepared in Example 4, 1.0g of dimethylolpropionic acid and 0.02mL of dibutyltin dilaurate and add them to the reaction vessel. Stir and purge with nitrogen. Then add 0.8 molar amount of isosorbide diisocyanate to the reaction system. Raise the temperature of the reaction vessel to 80°C and keep it at that temperature for 3 hours. After the reaction is completed, cool to room temperature and collect for later use to obtain carboxyl NCO-terminated prepolymer.

[0100] Step 2: Preparation of waterborne polyurethane main agent dispersion

[0101] Weigh out 40.0g of carboxyl NCO-terminated prepolymer, 1.0mL of 2-amino-2-methyl-1-propanol and 80.0mL of deionized water and add them to the reaction vessel. Stir the reaction vessel and heat it to 55℃. Keep it at this temperature and stir for 40min. After stirring, let it stand to remove bubbles and filter it through an 80-mesh screen to obtain the waterborne polyurethane main agent dispersion.

[0102] Step 3: Preparation of modified curing agent

[0103] Take: 12.0 mL 1,5-diaminopentane, 9.0 mL propylene carbonate and 60.0 mL N,N-dimethylformamide into the reaction kettle, stir, after nitrogen protection, the temperature of the reaction kettle is increased to 70℃, and the reaction is stirred for 2h. After the reaction is completed, the reaction liquid is poured into 3 times the volume of anhydrous ethanol for precipitation. After the precipitation is completed, the filter cake is collected by suction filtration, and the filter cake is transferred to a drying oven with a temperature of 50℃ for vacuum drying until the weight is constant. The modified curing agent is obtained.

[0104] Step four, preparation of water-based polyurethane adhesive

[0105] According to parts by weight, take: 100 parts of water-based polyurethane main agent dispersion and 2 modified curing agent mixture, pass through a 100 mesh screen, and obtain a water-based polyurethane adhesive.

[0106] Example 8

[0107] The present embodiment provides a preparation method of a hydrolysis-resistant bio-based polyester polyol modified water-based polyurethane adhesive, comprising the following steps:

[0108] Step one, preparation of carboxyl NCO terminated prepolymer

[0109] Take: 50.0 g of furan carbonate-polyester polyol prepared in Example 2, 3.0 mL of phosphorus-silicon crosslinking flame retardant polyol prepared in Example 5, 1.0 g of dimethylol propionic acid and 0.02 mL of dibutyltin dilaurate into the reaction kettle, stir, after nitrogen protection, add diisocyanate of isosorbide with 0.9 times the molar amount of hydroxyl groups in the reaction system, and increase the temperature of the reaction kettle to 85℃. After 4h of stirring, the reaction is cooled to room temperature, and the carboxyl NCO terminated prepolymer is collected for standby.

[0110] Step two, preparation of water-based polyurethane main agent dispersion

[0111] Take: 40.0 g of carboxyl NCO terminated prepolymer, 1.0 mL of 2-amino-2-methyl-1-propanol and 100.0 mL of deionized water into the reaction kettle, stir, and heat the reaction kettle to 60℃. After 60min of stirring, the reaction is completed, and the water-based polyurethane main agent dispersion is obtained by standing, degassing and passing through an 80 mesh filter screen.

[0112] Step three, preparation of modified curing agent

[0113] Take: 15.0 mL 1,5-diaminopentane, 9.0 mL propylene carbonate and 60.0 mL N, N-dimethylformamide into the reaction kettle, stir, after nitrogen protection, the temperature of the reaction kettle is increased to 80℃, keep stirring for 4h, after the reaction is completed, the reaction liquid is poured into 3 times the volume of anhydrous ethanol for precipitation, after the precipitation is completed, the filter cake is collected by suction filtration, and the filter cake is transferred to a drying oven with a temperature of 50℃ for vacuum drying until the constant weight is obtained. The modified curing agent is obtained.

[0114] Step four, preparation of water-based polyurethane adhesive

[0115] According to parts by weight, take: 100 parts of water-based polyurethane main agent dispersion and 3 modified curing agent mixture, pass through a 100 mesh screen, and obtain a water-based polyurethane adhesive.

[0116] Example 9

[0117] The present embodiment provides a preparation method of a hydrolysis-resistant bio-based polyester polyol modified water-based polyurethane adhesive, comprising the following steps:

[0118] Step one, preparation of carboxyl NCO terminated prepolymer

[0119] Take: 45.0 g of furan carbonate-polyester polyol prepared in Example 3, 2.5 mL of phosphorus-silicon crosslinking flame-retardant polyol prepared in Example 6, 1.0 g of dimethylol propionic acid and 0.02 mL of dibutyltin dilaurate into the reaction kettle, stir, after nitrogen protection, add diisocyanate of isosorbide with 0.9 times the molar amount of hydroxyl groups in the reaction system, and increase the temperature of the reaction kettle to 85℃, keep stirring for 4h, after the reaction is completed, cool to room temperature, collect and use, and obtain the carboxyl NCO terminated prepolymer.

[0120] Step two, preparation of water-based polyurethane main agent dispersion

[0121] Take: 40.0 g of carboxyl NCO terminated prepolymer, 1.0 mL of 2-amino-2-methyl-1-propanol and 96.0 mL of deionized water into the reaction kettle, stir, increase the temperature of the reaction kettle to 60℃, keep stirring for 50 min, after the stirring is completed, stand for defoaming and pass through an 80 mesh filter screen, and obtain the water-based polyurethane main agent dispersion.

[0122] Step three, preparation of modified curing agent

[0123] Take: 15.0 mL 1,5-diaminopentane, 9.0 mL propylene carbonate and 60.0 mL N, N-dimethylformamide into the reaction kettle stirring, after the protection of nitrogen gas reaction kettle temperature to 75℃, keep stirring 3h, after the reaction is completed into 3 times the volume of anhydrous ethanol precipitation, after the precipitation is completed filter the reaction liquid collection filter cake, the filter cake is transferred to the temperature of 50℃ drying oven vacuum drying to constant weight, the modified curing agent is obtained.

[0124] Step four, preparation of water-based polyurethane adhesive

[0125] According to the weight part, take: 100 parts of water-based polyurethane main agent dispersion and 3 modified curing agent mixture, pass through 100 mesh screen, get water-based polyurethane adhesive.

[0126] Comparative example 1

[0127] The difference between this comparative example and example 12 is that the phosphorus silicon crosslinking flame retardant polyol is not used in step one.

[0128] Comparative example 2

[0129] The difference between this comparative example and example 12 is that the furan carbonate-polyester polyol used in step one cancels step ③ in the preparation process.

[0130] Comparative example 3

[0131] The difference between this comparative example and example 12 is that step three is cancelled and the modified curing agent is not added in step four.

[0132] Performance test:

[0133] According to the standard GB / T 7124-2008 "determination of tensile shear strength of adhesive (rigid material to rigid material)", the shear strength of water-based polyurethane adhesive prepared in examples 7-9 and comparative examples 1-3 is tested;

[0134] According to the standard GB / T 2790-1995 "adhesive 180 degree peel strength test method flexible material to rigid material", the peel strength of water-based polyurethane adhesive prepared in examples 7-9 and comparative examples 1-3 is tested;

[0135] According to the standard GB / T 26526-2011 "plastics oxygen index method for determination of combustion behavior part 2: room temperature test", the limiting oxygen index of water-based polyurethane adhesive prepared in examples 7-9 and comparative examples 1-3 after curing is tested;

[0136] After the aging experiment of the waterborne polyurethane adhesives prepared in Examples 7-9 and Comparative Examples 1-3 for 3 weeks under the condition of temperature 40℃ and relative humidity 70% according to the standard GB / T 35489-2017 "Guidelines for Aging Conditions of Adhesives", the shear strength and peeling strength were determined according to the standards GB / T 7124-2008 and GB / T 2790-1995, and the hydrolysis shear strength retention rate and peeling strength retention rate were calculated, and the specific data are shown in Table 1;

[0137] Table 1 - Performance test data table of each sample

[0138]

[0139]

[0140] Data analysis:

[0141] After comparing and analyzing the data in Table 1, it can be found that the shear strength of the waterborne polyurethane adhesive prepared by the present application is 6.4 MPa, the peeling strength is 2.9 kN·m -1 , the limiting oxygen index is 29.3%, the shear strength retention rate is 90.9%, and the peeling strength retention rate is 89.8%, all of which are better than those of the comparative examples, which shows that:

[0142] In the system of Comparative Example 1, the phosphorus-silicon crosslinking structure is missing, the crosslinking density of the polyurethane network is significantly decreased, the topological constraint between the chain segments is weakened, the molecular chain activity is increased, the free volume in the system is increased, the loose structure makes it easier for water and small molecules to penetrate along the chain gap and interface, and then induces local hydrolysis and plasticization effect, under thermal stress or humid heat environment, the chain segment fracture and rearrangement gradually accumulates, forming micro cracks, which destroys the original continuous phase structure, at the same time, due to the lack of inorganic guiding role of phosphorus-silicon elements in the combustion process, the material is difficult to form a dense and strongly adhered carbon layer at high temperature, thus leading to the simultaneous decline of thermal stability and bonding durability, and the overall mechanical and aging resistance performance is significantly deteriorated;

[0143] In Comparative Example 2, the polyol is not subjected to carbonate treatment, the regular polar anchor points and rigid confinement structure in the molecular main chain are lost, the phase separation between the hard segment and soft segment of the polyurethane is weakened, the interchain interaction force is insufficient, with the disorder of the microphase structure, the density of chain segment accumulation is reduced, the stress transmission channel is weakened, leading to local load concentration and easy to damage, in long-term humid heat or thermal oxygen environment, the open intermolecular space further promotes the diffusion of water molecules and ester bond hydrolysis reaction, the molecular weight of the system decreases and the structure relaxes, under the condition of combustion or high temperature, due to the lack of stable carbonate unit participating in the carbonization reaction, the carbon layer is generated slowly and discontinuously, the shielding effect is significantly weakened, and finally the mechanical properties, moisture resistance and flame retardancy are comprehensively decreased.

[0144] Comparative Example 3, due to the absence of the introduction of the modified curing agent for post-crosslinking reaction, the reactive groups in the prepolymer cannot be fully consumed and fixed, and the network structure is dominated by physical entanglement instead of chemical crosslinking. During the film forming process, the residual hydrophilic end groups and oligomers are prone to migrate in the system, forming fine pores and phase boundary defects, thereby reducing the density and interface stability of the film layer. Under the action of external heat and humidity, these defects become channels for water penetration and chain segment migration, causing local plasticization and stress relaxation of the adhesive layer, and further leading to the attenuation of interfacial adhesion; when heated, due to the incomplete crosslinking network, the thermal decomposition of the system is more likely to occur rather than converting into a stable carbon layer, and the thermal decomposition products are released rapidly, ultimately causing a simultaneous decrease in bonding strength, aging retention rate and thermal stability;

[0145] The present application uses furan carbonate-polyester polyol as the main body, combined with phosphorus-silicon crosslinking flame-retardant polyol and modified curing agent to jointly build a dense and stable polyurethane network. The furan carbonate-polyester polyol provides rigidity and polar sites in the molecular backbone, enabling the system to maintain good stability in phase separation and load transfer. The phosphorus-silicon crosslinking flame-retardant polyol enhances the chemical bonding between molecules and the structure retention ability in a thermal and oxidative environment by forming an organic-inorganic bridging structure. The modified curing agent further improves the network structure during the post-crosslinking stage, reducing residual reactive groups and hydrophilic defects. The three components synergistically act during the reaction and film forming process, enabling the system to exhibit excellent comprehensive performance in terms of shear strength, peel strength, wet heat retention rate and limiting oxygen index, and achieving a coordinated and unified balance between mechanical properties, durability and flame retardancy.

[0146] The above content is merely an example and description of the structure of the present application, and those skilled in the art can make various modifications or supplements to the described specific embodiments or use similar ways to replace them, as long as they do not deviate from the structure of the invention or exceed the scope defined by the present claims, and should be within the protection scope of the present application.

[0147] In the description of the present application, the description of the terms "one embodiment", "example", "specific example" and the like means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0148] The preferred embodiments of the application disclosed above are only to facilitate the elucidation of the application. The preferred embodiments do not describe all the details of the application and limit the application to the specific embodiments. Obviously, many modifications and variations can be made in light of the teachings above. The description is chosen and described in order to provide the best illustration of the application and its practical application to those skilled in the art and to enable those skilled in the art to utilize the application in its best mode. The application is only limited by the claims and their full scope and equivalents.

Claims

1. A hydrolysis-resistant bio-based polyester polyol modified waterborne polyurethane adhesive, characterized in that, It comprises the following raw material components by weight: 100 parts of waterborne polyurethane main agent dispersion and 2-3 parts of modified curing agent; The preparation method of the aqueous polyurethane main agent dispersion includes the following steps: S1. Add furan carbonate-polyester polyol, phosphorus silicon crosslinked flame retardant polyol, dimethylolpropionic acid and dibutyltin dilaurate to a reaction vessel and stir. After nitrogen protection, add the calculated amount of isosorbide diisocyanate and raise the temperature of the reaction vessel to 80-85℃. Keep the temperature and stir for 3-4 hours. After the reaction is completed, cool to room temperature and collect for later use to obtain carboxyl NCO-terminated prepolymer. S2. Add the carboxyl NCO-terminated prepolymer, 2-amino-2-methyl-1-propanol and deionized water to the reactor and stir. Heat the reactor to 55-60℃ and stir for 40-60 minutes. After stirring, let it stand to remove bubbles and pass it through an 80-mesh filter to obtain the waterborne polyurethane main agent dispersion.

2. The hydrolysis-resistant bio-based polyester polyol modified waterborne polyurethane adhesive according to claim 1, characterized in that, In step S1, the furan carbonate-polyester polyol, phosphorus-silicon crosslinked flame-retardant polyol, dimethylolpropionic acid and dibutyltin dilaurate are in a ratio of 40-50g:2-3mL:1g:0.02mL, wherein the amount of isosorbide diisocyanate added is 0.8-0.9 times the molar amount of hydroxyl groups in the reaction system; in step S2, the ratio of carboxyl NCO-terminated prepolymer, 2-amino-2-methyl-1-propanol and deionized water is 40g:1mL:80-100mL.

3. The hydrolysis-resistant bio-based polyester polyol modified waterborne polyurethane adhesive according to claim 1, characterized in that, The preparation method of the furan carbonate-polyester polyol includes the following steps: A1. Add acetylated furan glycol, dimethyl carbonate, potassium carbonate and toluene to a reaction vessel and stir. After purging with nitrogen, heat the reaction vessel to 105-115℃ and stir for 4-6 hours. Post-processing yields carbonated furan glycol precursor. A2. Add carbonated furan glycol precursor, 1,4-butanediol, dimethylolpropionic acid, dibutyltin dilaurate and cyclohexanone to a reaction vessel, purge with nitrogen, heat the reaction vessel to 150-170℃, keep it at this temperature and stir for 4-6 hours, and then proceed with post-treatment to obtain furan carbonate-polyester polyol.

4. The hydrolysis-resistant bio-based polyester polyol modified waterborne polyurethane adhesive according to claim 3, characterized in that, In step A1, the ratio of acetylated furan glycol, dimethyl carbonate, potassium carbonate, and toluene is 2-3 g: 12 mL: 0.03 g: 12-15 mL; in step A2, the ratio of carbonated furan glycol precursor, 1,4-butanediol, dimethylolpropionic acid, dibutyltin dilaurate, and cyclohexanone is 4-5 g: 2 mL: 0.5 g: 0.003-0.005 mL: 8-10 mL.

5. The hydrolysis-resistant bio-based polyester polyol modified waterborne polyurethane adhesive according to claim 3, characterized in that, The method for preparing the acetylated furan diol includes the following steps: B1. Add fructose, dimethyl sulfoxide, p-toluenesulfonic acid and acetic anhydride to a reaction vessel and stir. After purging with nitrogen, heat the reaction vessel to 120-135℃ and keep it at that temperature for 2-3 hours. Then, after processing, acetylated furanaldehyde is obtained. B2. Add acetylated furanaldehyde and methanol to the reactor, lower the reactor temperature to 0-5℃ and add sodium borohydride, then raise the reactor temperature to 20-30℃ and keep it at that temperature for 1-2 hours with stirring. After stirring, add acetic acid and let it stand for 10 minutes. The post-treatment yields acetylated furan glycol.

6. The hydrolysis-resistant bio-based polyester polyol modified waterborne polyurethane adhesive according to claim 5, characterized in that, In step B1, the ratio of fructose, dimethyl sulfoxide, p-toluenesulfonic acid, and acetic anhydride is 8-10g:25-30mL:0.1g:6mL; in step B2, the ratio of acetylated furanaldehyde, methanol, sodium borohydride, and acetic acid is 5g:20mL:0.3g:0.3mL.

7. The hydrolysis-resistant bio-based polyester polyol modified waterborne polyurethane adhesive according to claim 1, characterized in that, The preparation method of the phosphorus-silicon crosslinked flame-retardant polyol includes the following steps: C1. Add epoxidized soybean oil, dimethyl phosphite, triphenylphosphine and o-xylene to a reaction vessel and stir. After purging with nitrogen, heat the reaction vessel to 90-100℃ and keep it at that temperature for 4-6 hours. Post-processing yields phosphorus-containing hydroxylated soybean oil polyol. C2. Add phosphorus-containing hydroxylated soybean oil polyol, 3-(2,3-epoxypropoxy)propyltrimethoxysilane and triethylamine to a reaction vessel and stir. After purging with nitrogen, heat the reaction vessel to 90-100℃ and keep it at this temperature for 3-5 hours. After the reaction is complete, allow it to stand to remove bubbles and obtain phosphorus-silicon crosslinked flame-retardant polyol.

8. The hydrolysis-resistant bio-based polyester polyol modified waterborne polyurethane adhesive according to claim 7, characterized in that, In step C1, the ratio of the amount of epoxidized soybean oil, dimethyl phosphite, triphenylphosphine, and o-xylene is 80-100 mL: 20-25 mL: 1 g: 100 mL; in step C2, the ratio of the amount of phosphorus-containing hydroxylated soybean oil polyol, 3-(2,3-epoxypropoxy)propyltrimethoxysilane, and triethylamine is 40-50 mL: 5 mL: 0.1 mL.

9. The hydrolysis-resistant bio-based polyester polyol modified waterborne polyurethane adhesive according to claim 1, characterized in that, The modified curing agent is prepared by adding 1,5-diaminopentane, propylene carbonate and N,N-dimethylformamide into a reaction vessel and stirring. After purging with nitrogen, the temperature of the reaction vessel is raised to 70-80℃ and stirred for 2-4 hours. The modified curing agent is then obtained through post-treatment.

10. The hydrolysis-resistant bio-based polyester polyol modified waterborne polyurethane adhesive according to claim 9, characterized in that, The ratio of 1,5-diaminopentane, propylene carbonate, and N,N-dimethylformamide is 12-15 mL:9 mL:60 mL.

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