A tea polyphenol palmitate modified aqueous polyurethane dispersion and a preparation method and use thereof

Abstract

This invention provides a tea polyphenol palmitate-modified waterborne polyurethane dispersion, its preparation method, and its applications. The waterborne polyurethane dispersion, based on the solids content of the waterborne polyurethane resin, is prepared from raw materials comprising the following weight percentages: 24-34 wt% polyisocyanate; 48-71 wt% polyol; 5-8 wt% tea polyphenol palmitate; 1-6 wt% hydrophilic chain extender containing active hydrogen; 1-6 wt% polyfunctional chain extender containing amino groups; 1-8 wt% aminosilane coupling agent; and 0-1 wt% neutralizing agent. The polyurethane emulsion synthesized using the acetone method with tea polyphenol palmitate as a modifier exhibits excellent resistance to yellowing and good substrate adhesion when applied to industrial paints.

Description

Technical Field

[0001] This invention belongs to the field of waterborne polyurethane materials, specifically relating to a tea polyphenol palmitate modified waterborne polyurethane dispersion, its preparation method, and its uses. Background Technology

[0002] Waterborne polyurethane dispersions, when further formulated into industrial topcoats and applied to metal surfaces, not only provide decorative functions but also offer a degree of protection.

[0003] Industrial topcoats, applied to metal surfaces and exposed to natural environments for extended periods, are prone to yellowing due to prolonged exposure to sunlight, rain, and other environmental factors. This reduces their aesthetic appeal and, to some extent, diminishes their protective properties. Patent CN109099241A discloses a UV-resistant matte topcoat and its preparation method, using polyurethane acrylate as the main resin and adding palmitic acid as an anti-yellowing agent to prepare a matte topcoat with excellent yellowing resistance. However, in this patent, the palmitic acid is added through physical blending, which makes it prone to migration and precipitation, resulting in poor coating stability.

[0004] Given the current market demands for environmental friendliness in industrial topcoats, the performance requirements for water-based industrial topcoats are becoming increasingly stringent. As water-based polyurethane is a key raw material in industrial topcoats, improving its overall performance is essential. Furthermore, since formulated industrial topcoats are intended for long-term outdoor exposure, enhancing their resistance to yellowing is crucial. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing a tea polyphenol palmitate-modified waterborne polyurethane dispersion, which can improve the yellowing resistance of industrial topcoats.

[0006] The tea polyphenol palmitate modified waterborne polyurethane dispersion of the present invention provides a new solution for solving problems such as yellowing resistance, substrate adhesion and film strength of current industrial coatings.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] This invention provides a tea polyphenol palmitate-modified aqueous polyurethane dispersion, prepared from raw materials comprising the following mass percentages based on the solid content of aqueous polyurethane resin:

[0009] A) Polyisocyanate, 24-34 wt%, preferably 28-30 wt%;

[0010] B) Polyols, 48-71 wt%, preferably 58-62 wt%;

[0011] C) Tea polyphenol palmitate, 5-8 wt%, preferably 6.5 wt%;

[0012] D) A hydrophilic chain extender containing active hydrogen, 1-6 wt%, preferably 1.5-4 wt%;

[0013] E) A multifunctional chain extender containing amino groups, 1-6 wt%, preferably 2-5 wt%;

[0014] F) Aminosilane coupling agent, 1-8 wt%, preferably 2-6 wt%;

[0015] G) Neutralizing agent, 0-1 wt%, preferably 0.4-0.6 wt%.

[0016] Specifically, it is prepared from raw materials comprising the following mass percentages:

[0017] A) Polyisocyanates include, but are not limited to, 24wt%, 25wt%, 26wt%, 27wt%, 28wt%, 29wt%, 30wt%, 31wt%, 32wt%, 33wt%, 34wt%, etc.;

[0018] B) Polyols include, but are not limited to, 48wt%, 50wt%, 52wt%, 54wt%, 56wt%, 58wt%, 60wt%, 62wt%, 64wt%, 66wt%, 68wt%, 70wt%, 71wt%, etc.

[0019] C) Tea polyphenol palmitate, including but not limited to 5wt%, 5.5wt%, 6wt%, 6.5wt%, 7wt%, 7.5wt%, 8wt%, etc.;

[0020] D) Hydrophilic chain extenders containing active hydrogen, including but not limited to 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, etc.;

[0021] E) Multifunctional chain extenders containing amino groups include, but are not limited to, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, etc.;

[0022] F) Aminosilane coupling agents include, but are not limited to, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, etc.;

[0023] G) Neutralizing agents include, but are not limited to, 0 wt%, 0.05 wt%, 0.2 wt%, 0.4 wt%, 0.6 wt%, 0.8 wt%, 1 wt%, etc.

[0024] In this invention, the NCO% content of the polyisocyanate in component A) is 30-50%;

[0025] Preferably, the polyisocyanate is selected from one or more of aliphatic polyisocyanates and alicyclic isocyanates, and more preferably from one or more of isophorone diisocyanate, 1,6-hexyl diisocyanate, and dicyclohexylmethane diisocyanate.

[0026] In this invention, the polyol in component B) is a polyol with a number average molecular weight of 100-5000 and a functionality of 2-4.

[0027] Preferably, the polyol is selected from one or more of polypropylene glycol, polyethylene glycol, and polytetrahydrofuran ether glycol.

[0028] In this invention, the hydrophilic chain extender containing active hydrogen in component D) is selected from one or more of dihydroxypropionic acid, dimethylolbutyric acid, dimethylolvalerate, dimethyloloctanoic acid, sodium 1,2-propanediol-3-sulfonate, and sodium 1,4-butanediol-2-sulfonate.

[0029] In this invention, the amino-containing multifunctional chain extender in component E) is selected from acylhydrazine chain extenders, preferably one or more of succinic hydrazine, sebacylhydrazine, adipic dihydrazine, benzoylhydrazine, isophthalic hydrazine, and p-hydroxybenzoic acid hydrazine.

[0030] In this invention, the aminosilane coupling agent of component F) is selected from one or more of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, and aminoethylaminoethylaminopropyltrimethoxysilane.

[0031] In this invention, the neutralizing agent described in component G) is selected from alkaline compounds, preferably one or more of sodium hydroxide, potassium hydroxide, triethylamine, and ammonia.

[0032] In this invention, the solid content of the tea polyphenol palmitate modified waterborne polyurethane dispersion is 50-70 wt%, and the remainder is a water dispersant.

[0033] In this invention, the particle size of the tea polyphenol palmitate modified waterborne polyurethane dispersion is 200-400 nm, preferably 300 nm.

[0034] Another aspect of the present invention provides a method for preparing the tea polyphenol palmitate modified aqueous polyurethane dispersion.

[0035] The tea polyphenol palmitate modified waterborne polyurethane dispersion was prepared by adding tea polyphenol palmitate during the isocyanate prepolymerization stage.

[0036] Tea polyphenol palmitate contains hydroxyl groups, which can react with the NCO groups of isocyanate in the system and participate in the chain extension of the system. Because tea polyphenol palmitate has a high functional structure, it can form a highly cross-linked system during the reaction with isocyanate. The resulting resin not only has excellent resistance to yellowing, but also has high bulk strength and paint film adhesion.

[0037] In addition, the present invention adds a silane coupling agent and an amino-containing multifunctional chain extender, such as an acylhydrazine chain extender, in the post-chain extension stage to extend the chain, thereby further improving the adhesion of the synthesized waterborne polyurethane to the substrate.

[0038] Specifically, a method for preparing a tea polyphenol palmitate-modified aqueous polyurethane dispersion includes the following preparation steps:

[0039] (1) Mix component A) polyisocyanate and component B) polyol to react and obtain a prepolymer, then add acetone and mix evenly;

[0040] (2) Add component C) tea polyphenol palmitate, component D) hydrophilic chain extender containing active hydrogen, component E) multifunctional chain extender containing amino group, and component F) aminosilane coupling agent to the system in step (1) and carry out the reaction.

[0041] (3) Add component G) neutralizer to the system in step (2) and stir. Then add acetone and mix evenly. Add deionized water under high-speed shearing to disperse and remove acetone to obtain the tea polyphenol palmitate modified waterborne polyurethane dispersion.

[0042] The preparation method provided by this invention is the acetone method commonly used in the field. Specifically, the relevant operations and process conditions in the preparation method of this invention, as well as the apparatus used, can all be carried out using conventional methods in the field, without any particular limitation. Those skilled in the art can optimize the process based on existing technology and known processes according to actual needs. Specifically, for example, the following conditions listed in this invention can be used:

[0043] In this invention, the reaction in step (1) is carried out at a temperature of 80-90℃ for a time of 0.8-1.2h.

[0044] In this invention, the amount of acetone added in step (1) is 20-25% of the total mass of component A) polyisocyanate and component B) polyol.

[0045] In this invention, the reaction in step (2) is carried out at a temperature of 60-80℃;

[0046] Specifically, the reaction ends when the theoretical NCO% is reached; the theoretical NCO content is a conventional method in the field for determining the reaction endpoint of isocyanate and polyol, and can be calculated by those skilled in the art based on the effective content ratio of isocyanate and polyol.

[0047] In this invention, the reaction in step (2) is further complicated by the addition of a catalyst to the system. The catalyst is selected from one or more of organobismuth catalysts, such as bismuth isooctanoate, bismuth laurylate, and bismuth neodecanoate, preferably one or more of organobismuth Coscat 83, organobismuth 1610, organobismuth 2010, organobismuth 2810, and organobismuth 2808.

[0048] Preferably, the amount of catalyst added is 0.2-0.6% of the solid content in the reaction system by mass.

[0049] In this invention, the stirring time in step (3) is 3-8 minutes, and the temperature is preferably lowered to 30-35°C after neutralization.

[0050] In this invention, the acetone added in step (3) is used to dilute and reduce viscosity. The amount added does not need to be precisely controlled and can be obtained by technicians based on experience. It is usually about 25 wt% of the total solids. For example, based on the solids of the raw material, the amount of acetone added can be 20-30 wt%.

[0051] In this invention, step (3) also includes adding deionized water for dispersion under high-speed shearing and removing acetone, which are all conventional operations in the field and are not specifically required here;

[0052] Specifically, the amount of deionized material added is such that the solid content of the tea polyphenol palmitate modified waterborne polyurethane dispersion is 50-70 wt%.

[0053] In another aspect, the present invention provides the application of the tea polyphenol palmitate modified aqueous polyurethane dispersion.

[0054] The tea polyphenol palmitate modified waterborne polyurethane dispersion of the present invention has excellent resistance to yellowing, substrate adhesion and film strength, and can be used in printing coatings, architectural coatings, industrial paints and topcoats, etc., especially suitable for industrial paints and topcoats.

[0055] Compared with the prior art, the positive effects of the present invention are as follows:

[0056] This invention uses tea polyphenol palmitate as a modifier to give the resulting waterborne polyurethane excellent resistance to yellowing. Simultaneously, in combination with components such as silane coupling agents, it can also improve the substrate adhesion and film strength of the coating. Detailed Implementation

[0057] The following embodiments will further illustrate the method provided by the present invention, but the present invention is not limited to the listed embodiments, and should also include any other known modifications within the scope of the claims of the present invention.

[0058] Unless otherwise specified, the reagents, materials and instruments used in the following examples are all conventional reagents, materials and instruments in the art, and can be obtained commercially.

[0059] The main testing methods used for the characteristic parameters of the waterborne polyurethane dispersion in this embodiment of the invention are as follows:

[0060] Particle size testing method: The Malvern ZetaSizer Nano-ZS90 laser particle size analyzer from Malvem, UK, was used. The emulsion was first diluted by 5%. The test was conducted at room temperature (approximately 25°C), with a detection angle of 90° and a laser wavelength of 633nm to measure the particle size of the sample.

[0061] Solid content test method: Take a clean, dry aluminum foil container and weigh it using an analytical balance, record the weight as w1. Weigh 1.5–2 grams of the sample emulsion into the weighed aluminum foil container using the subtraction method, record the weight of the sample emulsion as w2, then place it in a 140℃ oven to dry for 30 minutes. Remove it and weigh it again, record the weight as w3. Repeat this weighing process until the weight difference between two consecutive weighings is ≤0.01 grams (accurate to 0.01 grams). Solid content = (w3-w1) / w2 × 100%.

[0062] The main raw material sources used in the embodiments of this invention are as follows:

[0063] HMDI (dicyclohexylmethane diisocyanate, NCO% content approximately 32.0%, Wanhua Chemical Group Co., Ltd.);

[0064] IPDI (Isophorone diisocyanate, NCO% content approximately 37.8%, Wanhua Chemical Group Co., Ltd.);

[0065] PPG2000 (polypropylene glycol, number average molecular weight ≈2000, functionality is 2, Dongda Chemistry);

[0066] PTMG2000 (polytetrahydrofuran ether diol, number average molecular weight 2000, functionality 2, Yantai Huada Chemical);

[0067] PTMG1000 (polytetrahydrofuran ether diol, number average molecular weight 1000, functionality 2, Yantai Huada Chemical);

[0068] Tea polyphenol palmitate (Ningbo Kangle Biotechnology Co., Ltd., purity >98%), functionality 8;

[0069] Sebacic acid dihydrazide (Shanghai Aladdin Biochemical Technology Co., Ltd., purity 96%);

[0070] ADH (adipic acid dihydrazide, Shandong Dengnuo New Material Co., Ltd., analytical grade);

[0071] Isophthalic acid hydrazide (Zhejiang Runtu Co., Ltd., analytical grade);

[0072] γ-aminopropyltriethoxysilane (Shandong Silicon Science New Materials Co., Ltd., analytical grade);

[0073] γ-aminopropyltrimethoxysilane (Shandong Silicon Science New Materials Co., Ltd., analytical grade);

[0074] Aminoethylaminoethylaminopropyltrimethoxysilane (Shandong Silicon Science New Materials Co., Ltd., analytical grade);

[0075] Triethylamine (Nantong Runfeng Petrochemical Co., Ltd., analytical grade);

[0076] Ammonia water (Dezhou Wanyu Chemical Products Co., Ltd., industrial grade);

[0077] Organic bismuth Coscat 83: from a leading US chemical company (analytical grade);

[0078] U605 (Polyurethane associative thickener, Wanhua Chemical Group Co., Ltd.)

[0079] Example 1

[0080] (1) Add 36g IPDI, 20g HMDI, 36g PPG2000, 40g PTMG2000 and 36g PTMG1000 to a four-necked flask equipped with a reflux condenser, thermometer and mechanical stirrer. After reacting at 85℃ for 1h, a prepolymer is obtained. Add 40g acetone to reduce the viscosity.

[0081] (2) Cool down to 60°C, add 12g of tea polyphenol palmitate, 4g of dimethylolbutyric acid, 8g of sebacate, and 6g of γ-aminopropyltriethoxysilane. At the same time, add 0.4wt% of organic bismuth Coscat83 to the reaction system, stir evenly, and heat up to 70°C to react. When the reaction reaches the theoretical NCO%, cool down.

[0082] (3) Add 0.4g of triethylamine and stir for 5min. Add 50g of acetone to dilute and stir for 5min. Continue to cool down to 35℃ and add 198g of deionized water under high-speed shearing to disperse and remove acetone to obtain tea polyphenol palmitate modified waterborne polyurethane dispersion.

[0083] The solid content of this tea polyphenol palmitate modified waterborne polyurethane dispersion is 50 wt%, and the particle size is 300-400 nm.

[0084] Example 2

[0085] (1) Add 32g IPDI, 30g HMDI, 20g PPG2000, 48g PTMG2000 and 40g PTMG1000 to a four-necked flask equipped with a reflux condenser, thermometer and mechanical stirrer. After reacting at 80℃ for 0.8h, a prepolymer is obtained. Add 40g acetone to reduce the viscosity.

[0086] (2) Cool down to 60°C, add 10g of tea polyphenol palmitate, 8g of dimethylolbutyric acid, 6g of adipamide, and 8g of γ-aminopropyltriethoxysilane. At the same time, add 0.4wt% of organic bismuth Coscat83 to the reaction system, stir evenly, and heat up to 75°C to react. When the reaction reaches the theoretical NCO%, cool down.

[0087] (3) Add 0.8g of triethylamine and stir for 5min. Add 43g of acetone to dilute and stir for 5min. Continue to cool down to 32℃. Add 172g of deionized water under high-speed shearing to disperse and remove acetone to obtain tea polyphenol palmitate modified waterborne polyurethane dispersion.

[0088] The solid content of this tea polyphenol palmitate modified waterborne polyurethane dispersion is 50 wt%, and the particle size is 300-400 nm.

[0089] Example 3

[0090] (1) Add 20g IPDI, 40g HMDI, 40g PPG2000, 20g PTMG2000 and 36g PTMG1000 to a four-necked flask equipped with a reflux condenser, thermometer and mechanical stirrer. After reacting at 90℃ for 1.2h, a prepolymer is obtained. Add 40g acetone to reduce the viscosity.

[0091] (2) Cool down to 60°C, add 14g of tea polyphenol palmitate, 10g of dimethylolbutyric acid, 12g of isophthalic acid hydrazide and 10g of γ-aminopropyltrimethoxysilane, and add 0.5wt% organic bismuth Coscat83 to the reaction system. Stir evenly, heat up to 80°C to react, and cool down when the reaction reaches the theoretical NCO%.

[0092] (3) Add 0.4g of ammonia water and stir for 5min. Add 50g of acetone to dilute and stir for 5min. Continue to cool down to 30℃. Add 202g of deionized water under high-speed shearing to disperse and remove acetone to obtain tea polyphenol palmitate modified waterborne polyurethane dispersion.

[0093] The solid content of this tea polyphenol palmitate modified waterborne polyurethane dispersion is 50 wt%, and the particle size is 300-400 nm.

[0094] Example 4

[0095] (1) Add 28g IPDI, 28g HMDI, 20g PPG2000, 36g PTMG2000 and 48g PTMG1000 to a four-necked flask equipped with a reflux condenser, thermometer and mechanical stirrer. After reacting at 85℃ for 1h, a prepolymer is obtained. Add 40g acetone to reduce the viscosity.

[0096] (2) Cool down to 60°C, add 18g of tea polyphenol palmitate, 6g of dimethylolbutyric acid, 8g of sebacate, and 12g of γ-aminopropyltrimethoxysilane. At the same time, add 0.6wt% organic bismuth Coscat83 to the reaction system, stir evenly, and heat up to 70°C to react. When the reaction reaches the theoretical NCO%, cool down.

[0097] (3) Add 1.2g of ammonia and stir for 5min, add 50g of acetone to dilute, stir and mix for 5min, and continue to cool down to 35℃. Add 205g of deionized water under high-speed shearing to disperse and remove acetone to obtain tea polyphenol palmitate modified waterborne polyurethane dispersion.

[0098] The solid content of this tea polyphenol palmitate modified waterborne polyurethane dispersion is 50 wt%, and the particle size is 300-400 nm.

[0099] Comparative Example 1

[0100] Referring to the method of Example 1, the difference is that component C) tea polyphenol palmitate is not added in step (2), and other operations and conditions remain unchanged to obtain an aqueous polyurethane dispersion.

[0101] Comparative Example 2

[0102] Referring to the method of Example 1, the difference is that in step (2), component C) tea polyphenol palmitate is replaced with an equimolar amount of palmitate, while other operations and conditions remain unchanged, to obtain an aqueous polyurethane dispersion.

[0103] Comparative Example 3

[0104] Referring to the method of Example 1, the difference is that aminopropyltriethoxysilane is not added in step (2), and other operations and conditions remain unchanged to obtain an aqueous polyurethane dispersion.

[0105] Performance tests of the aqueous polyurethane dispersions prepared in Examples 1-4 and Comparative Examples 1-3 in industrial topcoats:

[0106] Specifically, industrial topcoats were prepared using the aqueous polyurethane dispersions of the examples and comparative examples, and the formulations are shown in Table 1 below:

[0107] Table 1. Waterborne Polyurethane Application Formulation

[0108]

[0109] The raw materials in Table 1 were mixed and brushed onto a metal plate. After curing at room temperature (25℃) for 24 hours or in an oven at 50℃ for 12 hours, the test samples were obtained. The performance was then tested using the following method, and the results are shown in Table 2.

[0110] Viscosity testing method: The BROOKFIELD DV2T touchscreen viscometer was used with a No. 63 rotor at a room temperature of 25°C and a rotation speed of 30 rpm. The reading was taken after the test was stopped.

[0111] Tensile strength test method: Take a 15cm*15cm curing sheet mold with a thickness of 1mm, pour the synthesized PUD into the mold, cure it in an oven at 50℃ for 12h, take it out and dry it in an oven at 80℃ for 2h to obtain a cured PUD film. After cutting it with a dumbbell-shaped cutter, use a tensile testing machine to test its tensile strength.

[0112] Adhesion: The cross-cut adhesion test is used. A cross-cut adhesion tester has a blade width of approximately 10mm-12mm, with 10 squares spaced 1mm-1.2mm apart. When a straight line is drawn, 10 equally spaced straight lines will appear. Drawing perpendicular to these lines creates a 10x10 square. After completing the cross-cut test, tape is used to test for adhesion. Tape is applied to the cross-cut area, pressed firmly with a finger, and then quickly peeled off. The coating on the substrate is then visually inspected for any peeling. Evaluation is conducted according to ISO 2409 standards.

[0113] Yellowing test method: The sample is placed in a QUV-B instrument for aging. The aging conditions are: light wavelength 313nm, irradiation intensity 0.71W / m². 2 The aging temperature was 60℃ for 2000 hours. After removal, the yellowness of the paint film sample was measured using a Hunterlab colorimeter in reflectance mode according to ASTM YIE313.

[0114] Table 1. Performance Comparison of Examples and Comparative Examples

[0115]

Claims

1. A tea polyphenol palmitate-modified aqueous polyurethane dispersion, characterized in that, Based on the solid content of waterborne polyurethane resin, it is prepared from raw materials comprising the following mass percentages: A) Polyisocyanates, 24-34 wt%; B) Polyols, 48-71 wt%; C) Tea polyphenol palmitate, 5-8 wt%; D) Hydrophilic chain extenders containing active hydrogen, 1-6 wt%; E) Amino-containing multifunctional chain extenders, 1-6 wt%; F) Aminosilane coupling agent, 1-8 wt%; G) Neutralizing agent, 0-1 wt%; Component E) The amino-containing polyfunctional chain extender is selected from hydrazide chain extenders.

2. The tea polyphenol palmitate-modified aqueous polyurethane dispersion according to claim 1, characterized in that, Based on the solid content of waterborne polyurethane resin, it is prepared from raw materials comprising the following mass percentages: A) Polyisocyanates, 28-30 wt%; B) Polyols, 58-62 wt%; C) Tea polyphenol palmitate, 6.5 wt%; D) Hydrophilic chain extenders containing active hydrogen, 1.5-4 wt%; E) Amino-containing multifunctional chain extenders, 2-5 wt%; F) Aminosilane coupling agent, 2-6 wt%; G) Neutralizing agent, 0.4-0.6 wt%.

3. The tea polyphenol palmitate-modified aqueous polyurethane dispersion according to claim 1, characterized in that, Component A) The NCO% content of the polyisocyanate is 30-50%; and / or, The polyisocyanate is selected from one or more of aliphatic polyisocyanates and alicyclic isocyanates.

4. The tea polyphenol palmitate-modified aqueous polyurethane dispersion according to claim 3, characterized in that, The polyisocyanate is selected from one or more of isophorone diisocyanate, 1,6-hexyl diisocyanate, and dicyclohexylmethane diisocyanate.

5. The tea polyphenol palmitate-modified aqueous polyurethane dispersion according to claim 1, characterized in that, Component B) The polyol is a polyol with a number average molecular weight of 100-5000 and a functionality of 2-4; and / or, The polyol is selected from one or more of polypropylene glycol, polyethylene glycol, and polytetrahydrofuran ether glycol.

6. The tea polyphenol palmitate-modified aqueous polyurethane dispersion according to claim 1, characterized in that, Component D) The hydrophilic chain extender containing active hydrogen is selected from one or more of dihydroxypropionic acid, dimethylolbutyric acid, dimethylolvalerate, dimethyloloctanoic acid, sodium 1,2-propanediol-3-sulfonate, and sodium 1,4-butanediol-2-sulfonate.

7. The tea polyphenol palmitate-modified aqueous polyurethane dispersion according to claim 1, characterized in that, Component E) The acylhydrazine chain extender is selected from one or more of succinic acylhydrazine, sebacylhydrazine, adipic diacylhydrazine, benzoylhydrazine, isophthalic acylhydrazine, and p-hydroxybenzoic acid acylhydrazine.

8. The tea polyphenol palmitate-modified aqueous polyurethane dispersion according to claim 1, characterized in that, Component F) The aminosilane coupling agent is selected from one or more of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, and aminoethylaminoethylaminopropyltrimethoxysilane; and / or The neutralizing agent described in component G is selected from basic compounds.

9. The tea polyphenol palmitate-modified aqueous polyurethane dispersion according to claim 8, characterized in that, The neutralizing agent is selected from one or more of sodium hydroxide, potassium hydroxide, triethylamine, and ammonia.

10. The tea polyphenol palmitate-modified aqueous polyurethane dispersion according to claim 1, characterized in that, The solid content is 50-70 wt%, with the remainder being a water dispersant; and / or The particle size is 200-400nm.

11. A method for preparing the tea polyphenol palmitate modified aqueous polyurethane dispersion according to any one of claims 1-10, characterized in that the step include: (1) Mix component A) polyisocyanate and component B) polyol to react and obtain a prepolymer, then add acetone and mix evenly; (2) Add component C) tea polyphenol palmitate, component D) hydrophilic chain extender containing active hydrogen, component E) multifunctional chain extender containing amino group, and component F) aminosilane coupling agent to the system in step (1) and carry out the reaction; (3) Add component G) neutralizer to the system in step (2) and stir. Then add acetone and mix evenly. Add deionized water under high-speed shearing to disperse and remove acetone to obtain the tea polyphenol palmitate modified waterborne polyurethane dispersion.

12. The preparation method according to claim 11, characterized in that, The reaction described in step (1) is carried out at a temperature of 80-90℃ for a time of 0.8-1.2 h; and / or The amount of acetone added in step (1) is 20-25% of the total mass of component A) polyisocyanate and component B) polyol; and / or The reaction described in step (2) is carried out at a temperature of 60-80℃; and / or In step (2), a catalyst is added to the system, the catalyst being selected from organobismuth catalysts; and / or The stirring in step (3) takes 3-8 minutes.

13. The preparation method according to claim 12, characterized in that, The reaction described in step (2) ends when the theoretical NCO% is reached.

14. The preparation method according to claim 12, characterized in that, In step (2), the amount of catalyst added is 0.2-0.6% of the mass of the solids in the reaction system.

15. The application of the tea polyphenol palmitate modified waterborne polyurethane dispersion according to any one of claims 1-10 or the tea polyphenol palmitate modified waterborne polyurethane dispersion prepared by the method according to any one of claims 11-14 in the fields of printing coatings, architectural coatings, and industrial paints and topcoats.

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