Bio-based polyester polyol as well as preparation method and application thereof

Abstract

The invention relates to bio-based polyester polyol as well as a preparation method and application thereof. The bio-based polyester polyol is obtained by polymerizing vegetable oil, bio-based dibasic acid and bio-based dihydric alcohol in a weight ratio of 1: (0.27-0.35): (0.13-0.22). Compared with common polyester polyol, when the bio-based polyester polyol provided by the invention is used for preparing a bio-based two-component polyurethane adhesive, the adhesive has better acid and alkali resistance; the sealing structure adopting the adhesive still has good sealing property after being soaked in a solution with the pH value of 1 or 13 for 28 days.

Description

Technical Field

[0001] This invention relates to the field of adhesive technology, and in particular to a bio-based polyester polyol, its preparation method, and its application. Background Technology

[0002] Two-component polyurethane adhesives mainly consist of two components: A (primarily a polyol) and B (a polyisocyanate or terminal isocyanate prepolymer). The two-component polyurethane adhesive is applied by mixing the polyol (component A) containing active hydrogen with the terminal isocyanate prepolymer (component B), and then curing it on-site through a carbamate reaction, resulting in a tight bond between the adhered materials.

[0003] In the field of wastewater treatment, two-component polyurethane adhesives can be used for membrane bonding. This type of wastewater often exhibits a wide pH range and is frequently strongly acidic or alkaline. The ester bonds and other chemical bonds in the molecular chains of ordinary two-component polyurethane adhesives are prone to hydrolysis under acid or alkali catalysis, leading to adhesive layer degradation, weakened bond strength, and even seal failure. This damages the membrane module structure, shortens the lifespan and operating cycle of the entire wastewater treatment system, and increases maintenance costs. Furthermore, ordinary two-component polyurethane adhesives are not resistant to acid and alkali corrosion, limiting their application range. Summary of the Invention

[0004] This invention provides a bio-based polyester polyol, its preparation method, and its application, to solve the problems of insufficient mechanical properties and poor acid and alkali resistance of ordinary two-component polyurethane adhesives.

[0005] Based on the above problems, the present invention provides the following technical solution: In a first aspect, the present invention provides a bio-based polyester polyol, which is obtained by polymerizing vegetable oil, bio-based dicarboxylic acid and bio-based diol in a weight ratio of 1:(0.27~0.35):(0.13~0.22).

[0006] Secondly, the present invention provides a method for preparing a bio-based polyester polyol, comprising the following steps: Under an inert atmosphere, vegetable oil, bio-based dicarboxylic acid, and bio-based diol in a weight ratio of 1:(0.27~0.35):(0.13~0.22) are mixed and esterified at 140~150℃. Then, the temperature is raised to 220~230℃ and polycondensation is carried out under vacuum until the acid value of the system drops below 1.0 mgKOH / g and the hydroxyl value reaches 150~170 mgKOH / g, thus obtaining the bio-based polyester polyol. in: The bio-based polyester polyol has a weight-average molecular weight of 1000-5000 and an average functionality of 2.7-3.5.

[0007] In some embodiments of the present invention, the vegetable oil is one or more selected from castor oil, soybean oil, palm oil, cashew nut shell oil, and tung oil; and / or, The bio-based dicarboxylic acid is one or more selected from succinic acid, adipic acid, azelaic acid, sebacic acid, and dimer acids; and / or, The bio-based diol is one or more of ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, and 1,6-hexanediol.

[0008] Thirdly, the present invention provides the application of a bio-based polyester polyol in a bio-based two-component polyurethane adhesive.

[0009] Fourthly, the present invention provides a method for preparing a bio-based two-component polyurethane adhesive, wherein the bio-based two-component polyurethane adhesive is composed of component A and component B in a weight ratio of 1:(0.9~1.1), and the preparation method includes a preparation step of component A and a preparation step of component B, wherein: The preparation steps of component A include: At a temperature of 75~85℃, the bio-based polyester polyol and the first polyisocyanate are reacted first, then the temperature is lowered to below 60℃, filler and coupling agent are added and mixed, and then vacuum is applied to obtain component A; The preparation steps of component B include: Component B is obtained by mixing and reacting bio-based polyester polyol, second polyisocyanate and polyether polyol at a temperature of 75~85℃.

[0010] In some embodiments of the present invention Component A comprises a bio-based polyester polyol, a first polyisocyanate, fillers, and coupling agents in a weight ratio of (7~9):(0.5~1.5):(0.1~1):(0.01~0.1); and / or, Component B comprises bio-based polyester polyol, second polyisocyanate, and polyether polyol in a weight ratio of (4~6):(1~3):(0.1~1).

[0011] Polyurethane is a block copolymer of soft and hard segments. By adjusting the types and contents of soft and hard segments, different properties such as shear strength, peel strength, heat resistance, and acid and alkali resistance can be provided. Two-component polyurethane adhesives can be formulated to meet various structural requirements by adjusting the types and structures of hard and soft segments in the polyurethane molecule.

[0012] In preparing the bio-based two-component polyurethane adhesive, this invention uses the bio-based polyester polyol synthesized in this invention to replace vegetable oil, while adjusting the content of hard segments and soft segments in components A and B to increase the molecular weight and hard segment content, and simultaneously increasing the functionality and crosslinking degree of the bio-based polyester polyol, thereby improving the strength and acid and alkali resistance of the product.

[0013] In some embodiments of the present invention, the first polyisocyanate and the second polyisocyanate are independently selected from one or more of diphenylmethane diisocyanate, liquefied diphenylmethane diisocyanate, isophorone diisocyanate, and carbodiimide-modified diphenylmethane diisocyanate. In some embodiments of the present invention, the filler in component A is one or more of silica, kaolin, and talc; and / or, The coupling agent in component A is one or more of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, and phenylaminopropyltrimethoxysilane; and / or The polyether polyol of component B is one or more of polypropylene glycol, polypropylene oxide-ethylene oxide glycol, polytetrahydrofuran glycol, and polypropylene triol.

[0014] Fifthly, the present invention provides a bio-based two-component polyurethane adhesive.

[0015] In a sixth aspect, the present invention provides an application of a bio-based two-component polyurethane adhesive in the bonding of water treatment membranes.

[0016] The beneficial effects of this invention include at least the following: Compared to ordinary polyester polyols, the bio-based polyester polyols of this invention, when used to prepare bio-based two-component polyurethane adhesives, enable the adhesives to have better acid and alkali resistance; the sealing structure using this adhesive still maintains good sealing performance after being immersed in a solution with pH=1 or pH=13 for 28 days. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0018] Bio-based polyester polyols: The bio-based polyester polyol provided by this invention is obtained by reacting vegetable oil, bio-based dicarboxylic acid and bio-based diol in a weight ratio of 1:(0.27~0.35):(0.13~0.22).

[0019] Bio-based polyester polyols follow the conventional synthesis mechanism of polyester polyols, which belongs to the addition condensation reaction of polymers. Through the esterification reaction of acid and alcohol, water is generated and removed. Subsequently, under conditions such as vacuuming and heating, low molecular weight polyester undergoes further condensation reaction to remove water and other byproducts, generating a viscous substance with a certain molecular weight.

[0020] Preparation method of bio-based polyester polyols: This invention provides a method for preparing bio-based polyester polyols, comprising the following steps: Under nitrogen protection, bio-based dicarboxylic acid, bio-based diol, and vegetable oil in a weight ratio of 1:(0.27~0.35):(0.13~0.22) are added to the reactor, and the mixture is stirred and heated to 140~150°C. o The reaction begins at temperature C, and the system produces water. During the reaction, the top temperature is always controlled to be ≤103℃. The temperature is then increased to 190~210℃ and maintained. When the water output reaches 85~95% of the theoretical output and the acid value of the system is ≤30mgKOH / g, the temperature is increased to 220~230℃, and vacuuming begins. Under the condition of absolute pressure ≤5-10 kPa, the vacuum reaction continues until the acid value is less than 1mgKOH / g and the hydroxyl value is 150-170mgKOH / g. The material is then cooled and discharged to obtain bio-based polyester polyol.

[0021] The weight-average molecular weight of bio-based polyester polyols is 1000~5000; the average functionality is 2.7~3.5.

[0022] In some embodiments of the present invention, the vegetable oil is one or more selected from castor oil, soybean oil, palm oil, cashew nut shell oil, and tung oil; and / or, The bio-based dicarboxylic acid is one or more selected from succinic acid, adipic acid, azelaic acid, sebacic acid, and dimer acids; and / or, The bio-based diol is one or more of ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, and 1,6-hexanediol.

[0023] Succinic acid is mainly produced through microbial fermentation, utilizing sugars from crops such as corn and sugarcane as raw materials. Adipic acid is obtained via a bio-based route primarily through biomass conversion, using sugars such as glucose as starting materials for biological or chemical synthesis. Azelaic acid is obtained from natural oils through the pyrolysis of castor oil. Sebacic acid, similar to azelaic acid, is a bio-based product obtained from the hydrolysis and pyrolysis of castor oil. Dimer acids are essentially natural oils, formed from the dimerization of unsaturated fatty acids in vegetable oils.

[0024] Ethylene glycol is obtained through the chemical synthesis of glucose by converting it into bio-based ethanol. Diethylene glycol originates from bio-based ethylene or syngas derivative chemical processes. 1,2-Propanediol is produced via microbial fermentation or hydrogenolysis of biomass sugars. 1,3-Propanediol is produced using glucose and through the efficient conversion of specific engineered bacteria. 1,4-Butanediol is produced through fermentation, using sugars as raw materials to obtain succinic acid intermediates, followed by catalytic hydrogenation. 2,3-Butanediol is produced using Klebsiella pneumoniae and Bacillus subtilis to convert biomass sugars such as glucose and xylose into 2,3-butanediol. 1,5-Pentanediol is obtained through the catalytic conversion of bio-based lysine or furfural. 1,6-Hexanediol is obtained through the catalytic hydrogenation of bio-based adipic acid; it can also be derived from bio-based butadiene.

[0025] Applications of bio-based polyester polyols: This invention utilizes the aforementioned bio-based polyester polyol to prepare a bio-based two-component polyurethane adhesive. The long-chain fatty acid structure and moderate functionality contained in the bio-based polyester polyol molecule endow the cured adhesive product with a balance between high crosslinking density and molecular chain flexibility, thereby exhibiting excellent comprehensive mechanical properties, including high tensile strength, good elongation at break, and suitable hardness.

[0026] Using bio-based environmentally friendly materials, bio-based polyester polyols are synthesized based on vegetable oils, which improves the bonding strength and acid and alkali resistance of bio-based two-component polyurethane adhesives, thus broadening the application scope, reliability and environmental friendliness of the products in the field of wastewater treatment.

[0027] Preparation method of bio-based two-component polyurethane adhesive: This invention provides a method for preparing a bio-based two-component polyurethane adhesive, wherein the bio-based two-component polyurethane adhesive is composed of component A and component B in a weight ratio of 1:(0.9~1.1), and the preparation method includes a preparation step of component A and a preparation step of component B; wherein: The preparation steps of component A include: The reaction is carried out at 75~85℃ for 2~3h. First, the bio-based polyester polyol and the first polyisocyanate are reacted, then the temperature is lowered to below 60℃, filler and coupling agent are added and mixed, and then vacuum degassing is carried out for 1~2h to obtain component A. The preparation steps of component B include: The bio-based polyester polyol, the second polyisocyanate, and the polyether polyol were mixed and reacted at 75-85℃ for 2-3 hours. After titrating the NCO to reach 13%, the temperature was lowered to obtain component B.

[0028] In some embodiments of the present invention, the bio-based two-component polyurethane adhesive comprises component A and component B; Component A comprises a bio-based polyester polyol, a first polyisocyanate, fillers, and coupling agents in a weight ratio of (7~9):(0.5~1.5):(0.1~1):(0.01~0.1); and / or, Component B comprises bio-based polyester polyol, second polyisocyanate, and polyether polyol in a weight ratio of (4~6):(1~3):(0.1~1).

[0029] In some embodiments of the present invention, the first polyisocyanate and the second polyisocyanate are independently selected from one or more of diphenylmethane diisocyanate, liquefied diphenylmethane diisocyanate, isophorone diisocyanate, and carbodiimide-modified diphenylmethane diisocyanate. In some embodiments of the present invention, the filler in component A is one or more of silica, kaolin, and talc; and / or, The coupling agent in component A is one or more of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, and phenylaminopropyltrimethoxysilane.

[0030] In some embodiments of the present invention, the B component polyether polyol is one or more of polypropylene glycol, polypropylene oxide-ethylene oxide glycol, polytetrahydrofuran glycol, and polypropylene triol.

[0031] Bio-based two-component polyurethane adhesives: This invention provides a bio-based two-component polyurethane adhesive. The adhesive is prepared from a bio-based polyester polyol and exhibits high bonding strength, excellent flexibility, and outstanding acid and alkali resistance, enabling it to withstand long-term corrosion from strong acid and alkali environments.

[0032] Applications of bio-based two-component polyurethane adhesives: This invention provides the application of a bio-based two-component polyurethane adhesive in water treatment membrane bonding. This adhesive utilizes a bio-based polyester polyol synthesized according to this invention. Due to its unique long-chain structure and high cross-linking density, the cured adhesive exhibits excellent acid and alkali resistance, enabling it to withstand long-term corrosion from strong acid and alkali environments. This characteristic makes it suitable for bonding water treatment reverse osmosis membrane modules, providing high-strength structural support and long-term sealing for the membrane, perfectly solving the industry problem of easy aging and failure of ordinary two-component polyurethane adhesives in acidic and alkaline environments.

[0033] The method for testing the performance of bio-based polyester polyols is as follows: (1) Acid value determination: Tested according to HG / T 2708 standard; (2) Hydroxyl value determination: Tested according to HG / T 2709 standard; The method for testing diaphragm sealing performance is as follows: Air tightness test method: Pressurize the membrane with bio-based two-component polyurethane adhesive to 100 pis and observe the pressure change within 10 minutes. If the pressure drop exceeds 5%, it is considered unqualified.

[0034] Example 1: Castor oil (67.0%), bio-based sebacic acid (18.5%), and bio-based diethylene glycol (14.5%) by weight were added to the reactor. Under nitrogen protection, the mixture was stirred and heated to 145°C to initiate the reaction, at which point water began to be released from the system. The peak temperature was maintained at ≤103°C throughout the reaction. The temperature was then raised to 200°C and held. When the water output reached 90% of the theoretical output and the acid value was ≤30 mg KOH / g, the temperature was raised to 225°C, and a vacuum was applied. Under an absolute pressure ≤5 kPa, the reaction continued under vacuum until the acid value was less than 1 mg KOH / g. The mixture was then cooled and discharged to obtain a bio-based polyester polyol with satisfactory performance characteristics. The bio-based polyester polyol obtained in this example has the following specifications: acid value 0.21 mg KOH / g, hydroxyl value 164.4 mg KOH / g. Specific amounts of raw materials added are detailed in Table 1.

[0035] Example 2: 67.7% soybean oil, 20.8% bio-based adipic acid, and 11.5% bio-based diethylene glycol (by weight) were added to the reactor. Under nitrogen protection, the reaction began when the temperature was raised to 145°C with stirring, and water began to be released from the system. The top temperature was maintained at ≤103°C throughout the reaction. The temperature was then raised to 200°C and held. When the water output reached 93% of the theoretical output and the acid value was ≤30 mgKOH / g, the temperature was raised to 220°C, and a vacuum was applied. Under an absolute pressure ≤7 kPa, the reaction continued under vacuum until the acid value was less than 1 mgKOH / g. The product was then cooled and discharged to obtain a bio-based polyester polyol with satisfactory performance characteristics. The bio-based polyester polyol obtained in this example has the following specifications: acid value 0.34 mgKOH / g, hydroxyl value 159.6 mgKOH / g. Specific amounts of raw materials added are detailed in Table 1.

[0036] Example 3: Castor oil (67.4%), bio-based dimer acid (23.5%), and bio-based diethylene glycol (9.1%) by weight were added to the reactor. Under nitrogen protection, the reaction began when the temperature was raised to 140°C with stirring, and water began to be released from the system. During the reaction, the top temperature was consistently controlled to ≤103°C. The temperature was then raised to 205°C and maintained. When the water output reached 85% of the theoretical output and the acid value was ≤30 mgKOH / g, the temperature was raised to 220°C, and a vacuum was applied. Under an absolute pressure ≤10 kPa, the reaction continued under vacuum until the acid value was less than 1 mgKOH / g. The material was then cooled and discharged to obtain bio-based polyester polyol with qualified performance characteristics. The bio-based polyester polyol obtained in this example has the following properties: acid value 0.58 mgKOH / g, hydroxyl value 163.4 mgKOH / g. Specific amounts of raw materials added are detailed in Table 1.

[0037] Table 1. Raw material addition amounts for preparing bio-based polyester polyols

[0038] Example 4: The bio-based polyester polyols from Examples 1, 2, and 3 above were used to prepare bio-based two-component polyurethane adhesives. The synthesis process is as follows: Add bio-based polyester polyol to a flask, then add diphenylmethane diisocyanate, react at 80°C for 2 hours, cool down to below 60°C, add kaolin and γ-aminopropyltriethoxysilane respectively, stir for 30 minutes, degas under vacuum for 1 hour, and prepare component A. Bio-based polyester polyol was added to a flask, followed by liquefied diphenylmethane diisocyanate and polypropylene glycol. The mixture was reacted at 80°C for 2 hours. After titrating to achieve 13% NCO, the mixture was cooled to produce component B with 13% NCO content.

[0039] The raw material dosages for components A and B of the bio-based two-component polyurethane adhesive are shown in Tables 2 and 3.

[0040] Components A and B were mixed in a ratio of 0.9:1, and component A (0.9%) and component B (1%) were mixed. The two components were mixed sequentially in ascending order of their numerical values. After thorough mixing, the mixture was poured into a mold and cured at 50°C for 24 hours. The mold was then removed to obtain the film. Samples 1, 2, and 3 were prepared, and their mechanical properties, such as hardness and strength, were tested.

[0041] Comparative Example 1 The preparation methods of components A and B in Comparative Example 1 are the same as those in Example 4, except that the bio-based polyester polyol in component A is replaced with castor oil or soybean oil, and the bio-based polyester polyol in component B is replaced with castor oil or soybean oil. The raw material amounts of components A and B of the two-component polyurethane adhesive are shown in Tables 2 and 3.

[0042] Components A and B were mixed in a ratio of 0.9:1. Component A 4 and Component B 4 were mixed, and Component A 5 and Component B 5 were mixed. After thorough mixing, the mixture was poured into a mold and cured at 50°C for 24 hours. The film was then demolded to obtain the film. Samples 4 and 5 were prepared separately, and their mechanical properties, such as hardness and strength, were tested.

[0043] Table 2 Amount of raw materials added to component A

[0044] Table 3B Raw material addition amount

[0045] The mechanical properties of the films 1-5 obtained in Example 4 and Comparative Example 1 are shown in Table 4.

[0046] Table 4 Results of Mechanical Property Tests for Samples 1-5

[0047] Example 5: Acid and alkali resistance test of samples 1-5 The films 1-5 obtained in Example 4 and Comparative Example 1 were placed in water with pH=7, hydrochloric acid solution with pH=1, and NaOH solution with pH=13, respectively. They were then placed in an oven at 50°C and heated for a certain period of time. After removal, the transparency of the solution was observed. The test results are shown in Tables 5 and 6.

[0048] Table 5. Test results of acid resistance of samples 1-5.

[0049] Table 6. Test results of alkali resistance of samples 1-5.

[0050] Example 6: Components A and B, corresponding to Example 4 and Comparative Example 1, were mixed on the membrane at a ratio of 0.9:1. Component A (0.9) and Component B (1) were mixed, and the two components were mixed sequentially in ascending order of their numerical values. This mixture was used to bond the membrane, resulting in samples 6, 7, 8, 9, and 10. The prepared membranes were then placed in acidic or alkaline solutions and soaked for 28 days. After soaking, the sealing performance (air tightness test) of the membranes was tested. The test results are shown in Table 7.

[0051] Table 7 shows the sealing performance test results of diaphragms for samples 6-10.

[0052] As can be seen from Table 4, the bio-based two-component polyurethane adhesive synthesized using bio-based polyester polyols in this invention has superior mechanical properties compared to ordinary two-component polyurethane adhesives that do not use bio-based polyester polyols. As can be seen from Tables 5, 6, and 7, the acid and alkali resistance of the bio-based two-component polyurethane adhesive synthesized using bio-based polyester polyols in this invention and the water treatment membranes bonded to it can reach more than 28 days.

[0053] In the description of this specification, the references to terms such as "one embodiment / mode," "some embodiments / modes," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment / mode or example is included in at least one embodiment / mode or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment / mode or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments / modes or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments / modes or examples described in this specification, as well as the features of different embodiments / modes or examples.

[0054] It should be noted that in this invention, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. In this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise expressly specified.

[0055] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features of the invention herein.

Claims

1. A bio-based polyester polyol, characterized in that, It is obtained by polymerization of vegetable oil, bio-based dicarboxylic acid and bio-based diol in a weight ratio of 1 : (0.27~0.35) : (0.13~0.22).

2. A method for preparing a bio-based polyester polyol, characterized in that, Includes the following steps: Under an inert atmosphere, vegetable oil, bio-based dicarboxylic acid, and bio-based diol in a weight ratio of 1:(0.27~0.35):(0.13~0.22) are mixed and esterified at 140~150℃. Then, the temperature is raised to 220~230℃ and polycondensation is carried out under vacuum until the acid value of the system drops below 1.0 mgKOH / g and the hydroxyl value reaches 150~170 mgKOH / g, to obtain the bio-based polyester polyol. in: The bio-based polyester polyol has a weight-average molecular weight of 1000-5000 and an average functionality of 2.7-3.

5.

3. The method for preparing bio-based polyester polyol according to claim 2, characterized in that, The vegetable oil is one or more selected from castor oil, soybean oil, palm oil, cashew nut shell oil, and tung oil; and / or, The bio-based dicarboxylic acid is one or more selected from succinic acid, adipic acid, azelaic acid, sebacic acid, and dimer acids; and / or, The bio-based diol is one or more of ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, and 1,6-hexanediol.

4. The application of the bio-based polyester polyol of claim 1 or the bio-based polyester polyol prepared according to any one of claims 2 to 3 in bio-based two-component polyurethane adhesives.

5. A method for preparing a bio-based two-component polyurethane adhesive, wherein the bio-based two-component polyurethane adhesive is composed of component A and component B in a weight ratio of 1:(0.9~1.1), characterized in that, The preparation method includes preparation steps for component A and component B; wherein: The preparation steps of component A include: At a temperature of 75~85℃, the bio-based polyester polyol and the first polyisocyanate are reacted first, then the temperature is lowered to below 60℃, filler and coupling agent are added and mixed, and then vacuum is applied to obtain component A; The preparation steps of component B include: At a temperature of 75~85℃, bio-based polyester polyol, second polyisocyanate and polyether polyol are mixed and reacted to obtain component B; The bio-based polyester polyol is the bio-based polyester polyol according to claim 1 or the bio-based polyester polyol prepared according to any one of claims 2 to 3.

6. The method for preparing the bio-based two-component polyurethane adhesive according to claim 5, characterized in that: Component A comprises a bio-based polyester polyol, a first polyisocyanate, fillers, and coupling agents in a weight ratio of (7~9):(0.5~1.5):(0.1~1):(0.01~0.1); and / or, Component B comprises bio-based polyester polyol, second polyisocyanate, and polyether polyol in a weight ratio of (4~6):(1~3):(0.1~1).

7. The method for preparing the bio-based two-component polyurethane adhesive according to claim 5, characterized in that, The first polyisocyanate and the second polyisocyanate are independently selected from one or more of diphenylmethane diisocyanate, liquefied diphenylmethane diisocyanate, isophorone diisocyanate, and carbodiimide-modified diphenylmethane diisocyanate.

8. The method for preparing the bio-based two-component polyurethane adhesive according to claim 5, characterized in that: The filler in component A is one or more of silica, kaolin, and talc; and / or, The coupling agent in component A is one or more of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, and phenylaminopropyltrimethoxysilane; and / or The polyether polyol of component B is one or more of polypropylene glycol, polypropylene oxide-ethylene oxide glycol, polytetrahydrofuran glycol, and polypropylene triol.

9. A bio-based two-component polyurethane adhesive, characterized in that: It is prepared by the method for preparing the bio-based two-component polyurethane adhesive according to any one of claims 5 to 8.

10. The application of the bio-based two-component polyurethane adhesive of claim 9 in the bonding of water treatment membranes.

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