A modified polyurethane dispersion and compositions thereof

Abstract

The present application relates to a kind of modified polyurethane dispersions and its application in waterproof and moisture-permeable coating.The modified waterborne polyurethane dispersion includes the following raw materials: polyisocyanate, polyol, trihydroxy benzoic acid, chain extender, modified monomer (acrylate hard monomer containing double bond, acrylate soft monomer containing double bond, phosphate ester monomer).The waterproof and moisture-permeable coating prepared by the modified polyurethane dispersion of the present application has excellent moisture permeability, waterproofness and wash resistance.

Description

Technical Field

[0001] This invention relates to a modified polyurethane dispersion, and more particularly to a modified polyurethane dispersion for use in waterproof and breathable coatings. Background Technology

[0002] Waterproof and breathable materials, generally referred to as breathable materials abroad, are fabrics that allow water to not penetrate the fabric under certain pressure, but allow sweat to be conducted to the outside in the form of water vapor, maintaining the comfort and dryness of the fabric. They are high-level functional fabrics.

[0003] Waterproof and breathable materials are generally classified into three types according to their permeability mechanism: natural diffusion through pores, microporous permeability, and hydrophilic group permeability. The most representative material using the natural diffusion through pores mechanism is high-count, high-density waterproof and breathable cotton fabric. When the cotton fibers in the material are wetted, because cotton fibers are hydrophilic, the fabric expands due to fiber water absorption, making the pores inside the material smaller and the material more compact. When rainwater continues to wet the fabric, it achieves a waterproof and breathable effect. The design of the microporous diffusion permeability mechanism utilizes the significant difference between the diameter of the micropores and the diameter of water vapor and water droplets in the fiber membrane prepared by various processing methods. Generally, the pore size of membrane materials prepared by conventional processes is between 0.2-5.0 μm. Ordinary rain or melted snow has a diameter of about 100 μm, but the molecular diameter of water vapor is typically between 0.0003-0.0004 μm. Therefore, its principle mainly utilizes the humidity pressure difference between the material and the environment. This pressure difference allows smaller water vapor molecules or sweat to pass through the micropores of the material to reach the external environment. Conversely, water droplets, due to their large molecular diameter (especially when the micropores are very small), are difficult to enter the micropores even under certain pressure, thus achieving the purpose of waterproofing and breathability. The moisture permeability mechanism of the "pores" between polymers and hydrophilic groups is unrelated to the internal structure of the material. That is, it uses the "adsorption-diffusion-desorption" method to transfer water vapor emitted from the material. When the hydrophilic functional groups in the membrane material encounter water, intermolecular forces (hydrogen bonds) are generated between them and the water vapor molecules. This force causes the water vapor to be transferred along the gaps between the molecular chains of the membrane material, thereby allowing the water vapor molecules to be expelled.

[0004] With the development of waterborne polyurethane technology, hydrophilic group penetration technology has been increasingly studied in the field of waterproofing and breathability. Patent CN114437307A describes waterborne polyurethane dispersions, coating compositions and their applications, which enhance breathability by introducing diols with polyoxyethylene alkyl side chains. However, while this group improves breathability, it also leads to a decrease in water washability. Summary of the Invention

[0005] In view of the above problems, the present invention provides a modified waterborne polyurethane dispersion composition, wherein the waterproof and transparent coating made therefrom has excellent moisture permeability, waterproofness and water resistance.

[0006] This invention innovatively prepares a modified waterborne polyurethane composition to form a core-shell structure, which is more conducive to the entanglement between the molecular chains of polyurethane emulsion and polyacrylate emulsion than blending of pure polyurethane emulsion and polyacrylate emulsion, thus improving polymerization stability and complementing each other's advantages; the introduction of phosphate ester monomers, whose strong hydrophilicity can serve as a water vapor permeation channel, enhances the moisture permeability of the coating.

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

[0008] A modified polyurethane dispersion is prepared from the following raw materials in weight percentages:

[0009] 1) Polyisocyanate, the amount of which is 30-45 wt% of the isocyanate prepolymer;

[0010] 2) Macromolecular polyols, used in amounts of 47-59 wt% of the isocyanate prepolymer;

[0011] 3) Trihydroxybenzoic acid, used in amounts of 1-4 wt% of the isocyanate prepolymer;

[0012] 4) Hydrophilic chain extender, the amount of which is 3-8 wt% of the isocyanate prepolymer;

[0013] 5) Polyamine chain extender, the amount of which is 4-8 wt% of the isocyanate prepolymer;

[0014] 6) Modified monomers, used in amounts of 95-101% of the isocyanate prepolymer mass, including hard monomers containing double bonds, soft monomers containing double bonds, and phosphate ester monomers; wherein the amount of hard monomers containing double bonds is 19-35 wt% of the modified monomer mass; the amount of soft monomers containing double bonds is 50-70 wt% of the modified monomer mass; and the amount of phosphate ester monomers is 10-20 wt% of the modified monomer mass.

[0015] 7) Initiator, the amount of which is 0.05-0.3% of the total mass of the modified monomers, preferably 0.1-0.2%;

[0016] In this invention, the mass of the isocyanate prepolymer refers to the sum of the masses of the polyisocyanate, macromolecular polyol, trihydroxybenzoic acid, and hydrophilic chain extender.

[0017] In this invention, the polyisocyanate is selected from aliphatic diisocyanates, including but not limited to one or a combination of several of HDI, IPDI, HMDI, and TMXDI;

[0018] In this invention, the molecular weight of the macromolecular polyol is 1000-2000, and it is selected from one or more of the polyether polyols, such as PTMG, PPG, etc.

[0019] In this invention, trihydroxybenzoic acid is selected from one or a combination of gallic acid and phloroglucinol carboxylic acid.

[0020] In this invention, the hydrophilic chain extender is selected from one or more of dimethylolpropionic acid, dimethylolbutyric acid, amino acids, aminosulfonates, etc., with dimethylolbutyric acid being preferred.

[0021] In this invention, the polyamine chain extender is an organic or inorganic primary or secondary amine functional compound containing at least two active hydrogen atoms, including ethylenediamine, isophorone diamine, hexamethylenediamine, diethylenetriamine, phenylenediamine, toluenediamine, dicyclohexylmethanediamine, and mixtures thereof, preferably isophorone diamine.

[0022] In this invention, the hard monomer containing a double bond is selected from one or more of methyl methacrylate, styrene, and α-methylstyrene; preferably selected from one or more of methyl methacrylate and styrene.

[0023] In this invention, the soft monomer containing a double bond is selected from one or more of ethyl acrylate, n-butyl acrylate, isobutyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, 2-ethylheptyl acrylate, isooctyl acrylate, vinyl acetate, and vinyl propionate, preferably selected from one or more of ethyl acrylate, n-butyl acrylate, and isooctyl acrylate.

[0024] In this invention, the phosphate ester monomer is selected from one or a combination of several of HEMAP, PAM-100, and PAM-200.

[0025] In this invention, the initiator initiation system is a redox system;

[0026] Preferably, the oxidant includes one or more of ammonium persulfate, sodium persulfate, potassium persulfate di-tert-butyl peroxide, hydrogen peroxide, cumene hydrogen peroxide, and tert-butyl hydrogen peroxide, with tert-butyl hydrogen peroxide being more preferred;

[0027] Preferably, the reducing agent includes one or more of ferrous sulfate, silver nitrate, thiols, ferrous chloride, sodium metabisulfite, sodium bisulfite, and isoascorbic acid, with sodium metabisulfite being more preferred.

[0028] In this invention, the method for synthesizing the modified polyurethane dispersion is as follows:

[0029] a. In a multifunctional reactor, add polyisocyanate, macromolecular polyol, trihydroxybenzoic acid, hydrophilic chain extender, catalyst, and acetone according to the weight of the formula and mix them evenly. React at 50-80℃ until the theoretical NCO value is reached to obtain the prepolymer.

[0030] b. Cool the system to 50-60℃, add acetone and a portion of the modified monomer (preferably 50-70% of the total modified monomer, preferably about 2 / 3) and stir for 2-10 minutes, then continue to cool to 30-35℃;

[0031] c. Add deionized water to the cooled system and disperse it under high-speed shear conditions;

[0032] d. After dispersion is complete, the polyamine chain extender is slowly added to the system to obtain a modified waterborne polyurethane dispersion emulsion;

[0033] e. Add another portion of the modified monomer to the modified waterborne polyurethane dispersion emulsion to swell, add an initiator to carry out free radical polymerization, remove the acetone after polymerization to obtain a modified polyurethane dispersion with 50-55% solid content and a particle size of 120-150nm that emits obvious blue light.

[0034] In this invention, the modified waterborne polyurethane dispersion prepared by the above method can be used in coating fields such as clothing and tents where high requirements are placed on moisture permeability, water resistance and washability.

[0035] The positive effects of this invention are mainly reflected in the following aspects:

[0036] The preparation of modified waterborne polyurethane dispersions with a core-shell structure is more conducive to the entanglement between the molecular chains of polyurethane emulsions and polyacrylate emulsions than blending of simple polyurethane emulsions and polyacrylate emulsions, thus improving polymerization stability and complementing each other's advantages. Introducing trihydroxybenzoic acid into the polyurethane chain segments and phosphate ester monomers into the acrylate chain segments can greatly improve the water wash resistance of the modified polyurethane resin due to the strong polarity of the phosphate ester groups and trihydroxybenzoic acid. Detailed Implementation

[0037] The testing method in this invention is as follows:

[0038] Moisture permeability test: The moisture permeability of the waterproof and breathable products of the examples and comparative examples was tested according to the ASTM E-96 1995BW standard test method.

[0039] Water resistance test: The water pressure resistance of the waterproof and breathable products of the examples and comparative examples was tested according to the test method of JIS L 1092-2009B standard to evaluate the water resistance.

[0040] Water resistance test: The waterproof and breathable products prepared in the examples and comparative examples were washed with water and laundry detergent at 40°C according to the AATCC 135-2004 (WO & W5) standard test method. After 5 washes, the water resistance of the waterproof and breathable products was measured again using the aforementioned method.

[0041] The application process for preparing fabric coatings using dispersions is as follows: Using a doctor blade, the application formulations prepared from the polyurethane dispersions of each example and comparative example are applied to Oxford cloth (fabric specifications are 600d / 600d, and the plain weave basis weight is 218g / m²). 2 Then, proceed with the heating step, baking at 140℃ for 2 minutes, repeating the coating process twice, maintaining an application rate of 20g / m². 2 Left and right; among them,

[0042] The fabric coating application formula is as follows:

[0043]

[0044] The raw materials used in the examples are as follows:

[0045] HMDI (dicyclohexylmethane diisocyanate, NCO% content approximately 32.0%, Wanhua Chemical Group Co., Ltd.);

[0046] IPDI (Isophorone diisocyanate, NCO% content approximately 37.8%, Wanhua Chemical Group Co., Ltd.);

[0047] PPG2000 (polypropylene glycol diol, hydroxyl value 56mgKOH / g, number-average molecular weight ≈2000, functionality 2, Dongda Chemistry);

[0048] PTMG2000 (polytetrahydrofuran ether diol, hydroxyl value 56mgKOH / g, number average molecular weight 2000, functionality 2, Yantai Huada Chemical);

[0049] PTMG1000 (polytetrahydrofuran ether diol, hydroxyl value 112 mgKOH / g, number average molecular weight 1000, functionality 2, Yantai Huada Chemical);

[0050] Phloroglucinol carboxylic acid (2,4,6-trihydroxybenzoic acid, Jiangsu Runfeng Synthetic Technology Co., Ltd.)

[0051] Gallic acid (3,4,5-trihydroxybenzoic acid, Hubei Biaoyue Biotechnology Development Co., Ltd.)

[0052] Styrene, Wanhua Chemical Group Co., Ltd.;

[0053] Methyl methacrylate, Tianjin Kemeo Chemical Reagent Co., Ltd.

[0054] n-Butyl acrylate, Wanhua Chemical Group Co., Ltd.

[0055] Ethyl acrylate, Tianjin Kemeo Chemical Reagent Co., Ltd.;

[0056] Isooctyl acrylate, Tianjin Kemeo Chemical Reagent Co., Ltd.;

[0057] Sodium metabisulfite (Xilong Chemical Co., Ltd.)

[0058] TBHP (tert-butyl hydroperoxide, Xilong Chemical Co., Ltd.)

[0059] PAM-100, Shanghai Sanjing Chemical Co., Ltd.

[0060] PAM-200, Shanghai Sangying Chemical Co., Ltd.

[0061] HEMAP, Hubei Chengfeng Chemical Co., Ltd.

[0062] Example 1

[0063] Add 20g IPDI, 32.5g HMDI, 20g PPG2000, 65.5g PTMG1000, 4.5g gallic acid, 7.5g dimethylolbutyric acid, 0.3g organic bismuth Coscat 83, and 40g acetone to a four-necked flask equipped with a reflux condenser, thermometer, and mechanical stirrer, and mix thoroughly. React at 80°C until the theoretical NCO value is reached to obtain the prepolymer.

[0064] Cool the system to 60°C, add 100g acetone, 19g styrene monomer, 70g n-butyl acrylate monomer, and 10.8g PAM-100 and stir for 5 minutes, then continue to cool to 30-35°C.

[0065] Add 269.5g of deionized water to the cooled system and disperse it under high-speed shear conditions;

[0066] 9g of isophorone diamine diluted with 40g of water was slowly added to the system to obtain a modified waterborne polyurethane dispersion emulsion.

[0067] A pre-emulsion consisting of 9.56g styrene monomer, 35.2g n-butyl acrylate monomer, and 5.4g PAM-100 was added to the system. The mixture was heated to 35℃ and stirred for 1 hour. Then, 0.15g tert-butyl hydroperoxide and 0.15g sodium metabisulfite were added sequentially to initiate free radical polymerization. After polymerization, the acetone in the emulsion was removed by vacuum distillation to obtain a modified waterborne polyurethane dispersion with a particle size of 120nm and obvious blue light.

[0068] Example 2

[0069] Add 10g IPDI, 50g HMDI, 10g PTMG 2000, 66.5g PTMG1000, 6g gallic acid, 7.5g dimethylolbutyric acid, 0.3g organic bismuth Coscat 83, and 40g acetone to a four-necked flask equipped with a reflux condenser, thermometer, and mechanical stirrer, and mix well. React at 80°C until the theoretical NCO value is reached to obtain the prepolymer.

[0070] Cool the system to 60°C, add 100g acetone, 35g methyl methacrylate monomer, 55g n-butyl acrylate monomer, and 10g HEMAP, and stir for 5 minutes. Then continue to cool to 30-35°C.

[0071] Add 211g of deionized water to the cooled system and disperse it under high-speed shear conditions;

[0072] 6g of isophorone diamine diluted with 40g of water was slowly added to the system to obtain a modified waterborne polyurethane dispersion emulsion.

[0073] A pre-emulsion consisting of 17.6 g methyl methacrylate monomer, 27.5 g n-butyl acrylate monomer, and 5 g HEMAP was added to the system. The mixture was heated to 35 °C and stirred for 1 h. Then, 0.08 g tert-butyl hydroperoxide and 0.08 g sodium metabisulfite were added sequentially to initiate free radical polymerization. After polymerization, the acetone in the emulsion was removed by vacuum distillation to obtain a modified waterborne polyurethane dispersion with a particle size of 130 nm and obvious blue light.

[0074] Example 3

[0075] Add 67.5g HMDI, 70.5g PTMG 1000, 4.5g phloroglucinol carboxylic acid, 7.5g dimethylolbutyric acid, 0.3g organic bismuth Coscat 83, and 40g acetone to a four-necked flask equipped with a reflux condenser, thermometer, and mechanical stirrer, and mix well. React at 80°C until the theoretical NCO value is reached to obtain the prepolymer.

[0076] Cool the system to 60°C, add 100g acetone, 30g methyl methacrylate monomer, 50g isooctyl acrylate monomer, and 20g PAM-100 and stir for 5 minutes, then continue to cool to 30-35°C.

[0077] Add 248g of deionized water to the cooled system and disperse it under high-speed shear conditions;

[0078] 12g of isophorone diamine diluted with 40g of water was slowly added to the system to obtain a modified waterborne polyurethane dispersion emulsion.

[0079] A pre-emulsion consisting of 15g methyl methacrylate monomer, 25g isooctyl acrylate monomer, and 10g PAM-100 was added to the system. The mixture was heated to 35℃ and stirred for 1 hour. Then, 0.12g tert-butyl hydroperoxide and 0.12g sodium metabisulfite were added sequentially to initiate free radical polymerization. After polymerization, the acetone in the emulsion was removed by vacuum distillation to obtain a modified waterborne polyurethane dispersion with a particle size of 150nm and obvious blue light.

[0080] Example 4

[0081] Add 30g HMDI, 30g IPDI, 76.5g PTMG 1000, 1.5g phloroglucinol carboxylic acid, 12g dimethylolbutyric acid, 0.3g organic bismuth Coscat 83, and 40g acetone to a four-necked flask equipped with a reflux condenser, thermometer, and mechanical stirrer, and mix well. React at 80°C until the theoretical NCO value is reached to obtain the prepolymer.

[0082] Cool the system to 60°C, add 100g acetone, 25g styrene monomer, 60g n-butyl acrylate monomer, and 15g HEMAP monomer, stir and mix for 5 minutes, and continue to cool to 30-35°C.

[0083] Add 272.5g of deionized water to the cooled system and disperse it under high-speed shear conditions;

[0084] 12g of isophorone diamine diluted with 40g of water was slowly added to the system to obtain a modified waterborne polyurethane dispersion emulsion.

[0085] A pre-emulsion consisting of 12.6g styrene monomer, 30g n-butyl acrylate monomer, and 7.5g HEMAP monomer was added to the system. The mixture was heated to 35℃ and stirred for 1 hour. Then, 0.08g tert-butyl hydroperoxide and 0.08g sodium metabisulfite were added sequentially to initiate free radical polymerization. After polymerization, the acetone in the emulsion was removed by vacuum distillation to obtain a modified waterborne polyurethane dispersion with a particle size of 120nm and obvious blue light.

[0086] Example 5

[0087] Add 35.5g HMDI, 20g IPDI, 58g PTMG 1000, 30g PTMG 2000, 1g phloroglucinol carboxylic acid, 1g gallic acid, 4.5g dimethylolbutyric acid, 0.3g organic bismuth Coscat 83, and 40g acetone to a four-necked flask equipped with a reflux condenser, thermometer, and mechanical stirrer, and mix thoroughly. React at 80°C until the theoretical NCO value is reached to obtain the prepolymer.

[0088] Cool the system to 60°C, add 100g acetone, 19g styrene monomer, 70g n-butyl acrylate monomer, and 10.8g PAM-100 and stir for 5 minutes, then continue to cool to 30-35°C.

[0089] Add 272.5g of deionized water to the cooled system and disperse it under high-speed shear conditions;

[0090] 12g of isophorone diamine diluted with 40g of water was slowly added to the system to obtain a modified waterborne polyurethane dispersion emulsion.

[0091] A pre-emulsion consisting of 9.56g styrene monomer, 35.2g n-butyl acrylate monomer, and 5.4g PAM-100 was added to the system. The mixture was heated to 35℃ and stirred for 1 hour. Then, 0.12g tert-butyl hydroperoxide and 0.12g sodium metabisulfite were added sequentially to initiate free radical polymerization. After polymerization, the acetone in the emulsion was removed by vacuum distillation to obtain a modified waterborne polyurethane dispersion with a particle size of 120nm and obvious blue light.

[0092] Comparative Example 1

[0093] Add 20g IPDI, 32.5g HMDI, 20g PPG2000, 70g PTMG1000, 7.5g dimethylolbutyric acid, 0.3g organic bismuth Coscat 83, and 40g acetone to a four-necked flask equipped with a reflux condenser, thermometer, and mechanical stirrer, and mix well. React at 80°C until the theoretical NCO value is reached to obtain the prepolymer.

[0094] Cool the system to 60°C, add 100g acetone, 29.8g styrene monomer, and 70g n-butyl acrylate monomer and stir for 5 minutes, then continue to cool to 30-35°C.

[0095] Add 269.5g of deionized water to the cooled system and disperse it under high-speed shear conditions;

[0096] 9g of isophorone diamine diluted with 40g of water was slowly added to the system to obtain a modified waterborne polyurethane dispersion emulsion.

[0097] A pre-emulsion consisting of 14.96 g styrene monomer and 35.2 g n-butyl acrylate monomer was added to the system. The mixture was heated to 35 °C and stirred for 1 h. Then, 0.15 g tert-butyl hydroperoxide and 0.15 g sodium metabisulfite were added sequentially to initiate free radical polymerization. After polymerization, the acetone in the emulsion was removed by vacuum distillation to obtain a modified waterborne polyurethane dispersion.

[0098] Comparative Example 2

[0099] Add 20g IPDI, 32.5g HMDI, 20g PPG2000, 65.5g PTMG1000, 4.5g gallic acid, 7.5g dimethylolbutyric acid, 0.3g organic bismuth Coscat 83, and 40g acetone to a four-necked flask equipped with a reflux condenser, thermometer, and mechanical stirrer, and mix thoroughly. React at 80°C until the theoretical NCO value is reached to obtain the prepolymer.

[0100] Cool the system to 60°C, add 100g acetone, 29.8g styrene monomer, and 70g n-butyl acrylate monomer and stir for 5 minutes, then continue to cool to 30-35°C.

[0101] Add 269.5g of deionized water to the cooled system and disperse it under high-speed shear conditions;

[0102] 9g of isophorone diamine diluted with 40g of water was slowly added to the system to obtain a modified waterborne polyurethane dispersion emulsion.

[0103] A pre-emulsion consisting of 14.96 g styrene monomer and 35.2 g n-butyl acrylate monomer was added to the system. The mixture was heated to 35 °C and stirred for 1 h. Then, 0.15 g tert-butyl hydroperoxide and 0.15 g sodium metabisulfite were added sequentially to initiate free radical polymerization. After polymerization, the acetone in the emulsion was removed by vacuum distillation to obtain a modified waterborne polyurethane dispersion.

[0104] Comparative Example 3

[0105] Add 67.5g HMDI, 75g PTMG1000, 7.5g dimethylolbutyric acid, 0.3g organic bismuth Coscat 83 and 40g acetone to a four-necked flask equipped with a reflux condenser, thermometer and mechanical stirrer and mix well. React at 80℃ until the theoretical NCO value is reached to obtain the prepolymer.

[0106] Cool the system to 60°C, add 100g acetone, 30g methyl methacrylate monomer, 50g isooctyl acrylate monomer, and 20g PAM-100 and stir for 5 minutes, then continue to cool to 30-35°C.

[0107] Add 248g of deionized water to the cooled system and disperse it under high-speed shear conditions;

[0108] 12g of isophorone diamine diluted with 40g of water was slowly added to the system to obtain a modified waterborne polyurethane dispersion emulsion.

[0109] A pre-emulsion consisting of 15g methyl methacrylate monomer, 25g isooctyl acrylate monomer, and 10g PAM-100 was added to the system. The mixture was heated to 35℃ and stirred for 1 hour. Then, 0.12g tert-butyl hydroperoxide and 0.12g sodium metabisulfite were added sequentially to initiate free radical polymerization. After polymerization, the acetone in the emulsion was removed by vacuum distillation to obtain a modified waterborne polyurethane dispersion with a solid content of 52% and a particle size of 150nm that showed obvious blue light.

[0110] Modified waterborne polyurethane compositions were prepared using the compositions obtained in the various examples and comparative examples according to the coating formulations listed in the specific embodiments, and performance tests were performed. The performance test results of the obtained coatings are shown in the table below:

[0111]

[0112] As can be seen from the table above, the modified polyurethane composition prepared by this invention achieves good results in terms of waterproof performance, moisture permeability, and water resistance in coatings.

Claims

1. A modified polyurethane dispersion, prepared from raw materials comprising the following weight percentages: 1) Polyisocyanate, the amount of which is 30-45 wt% of the isocyanate prepolymer; 2) Macromolecular polyols, used in amounts of 47-59 wt% of the isocyanate prepolymer; 3) Trihydroxybenzoic acid, used in amounts of 1-4 wt% of the isocyanate prepolymer; 4) Hydrophilic chain extender, the amount of which is 3-8 wt% of the isocyanate prepolymer; 5) Polyamine chain extender, the amount of which is 4-8 wt% of the isocyanate prepolymer; 6) Modified monomers, used in amounts of 95-101% of the isocyanate prepolymer mass; 7) Initiator, the amount of which is 0.05-0.3% of the total mass of the modified monomers; in, The modified monomers include hard monomers containing double bonds, soft monomers containing double bonds, and phosphate ester monomers; wherein the amount of hard monomers containing double bonds is 19-35 wt% of the mass of the modified monomers. The amount of soft monomers containing double bonds is 50-70 wt% of the modified monomer mass; the amount of phosphate ester monomers is 10-20 wt% of the modified monomer mass.

2. The dispersion according to claim 1, wherein, The hard monomer containing a double bond is selected from one or more of methyl methacrylate, styrene, and α-methylstyrene; The soft monomer containing a double bond is selected from one or more of ethyl acrylate, n-butyl acrylate, isobutyl acrylate, cyclohexyl acrylate, 2-ethylheptyl acrylate, isooctyl acrylate, vinyl acetate, and vinyl propionate. The phosphate ester monomer is selected from one or more of HEMAP, PAM-100, and PAM-200.

3. The dispersion according to any one of claims 1-2, wherein, Polyisocyanates are selected from aliphatic diisocyanates.

4. The dispersion according to claim 3, wherein, The polyisocyanate is selected from one or more of HDI, IPDI, HMDI, and TMXDI.

5. The dispersion according to any one of claims 1-2, wherein, The molecular weight of the macromolecular polyol is 1000-2000, and it is selected from one or more polyether polyols.

6. The dispersion according to claim 5, wherein, The macromolecular polyols are selected from PTMG and PPG.

7. The dispersion according to any one of claims 1-2, wherein, Trihydroxybenzoic acid is selected from gallic acid and / or phloroglucinol carboxylic acid.

8. The dispersion according to any one of claims 1-2, wherein, The hydrophilic chain extender is selected from one or more of dimethylolpropionic acid, dimethylolbutyric acid, amino acids, and aminosulfonates.

9. The dispersion according to any one of claims 1-2, wherein, Polyamine chain extenders are organic primary or secondary amine functional compounds containing at least two active hydrogen atoms.

10. The dispersion according to claim 9, wherein, Polyamine chain extenders include one or more of ethylenediamine, isophorone diamine, hexamethylenediamine, diethylenetriamine, phenylenediamine, toluenediamine, and dicyclohexylmethanediamine.

11. The dispersion according to any one of claims 1-2, wherein, The initiator-initiated system is a redox system; Oxidizing agents include one or more of the following: ammonium persulfate, sodium persulfate, potassium persulfate, di-tert-butyl peroxide, hydrogen peroxide, cumene hydrogen peroxide, and tert-butyl hydrogen peroxide. The reducing agents include one or more of ferrous sulfate, thiols, ferrous chloride, sodium metabisulfite, sodium bisulfite, and isoascorbic acid.

12. A method for preparing a dispersion according to any one of claims 1-11, comprising: a. In a reaction vessel, add polyisocyanate, macromolecular polyol, trihydroxybenzoic acid, hydrophilic chain extender, catalyst, and acetone and mix well. React at 50-80℃ until the theoretical NCO value is reached to obtain the prepolymer. b. Cool the system to 50-60℃, add acetone and a portion of the modified monomer and stir to mix, then continue to cool to 30-35℃; c. Add deionized water to the cooled system and disperse it under high-speed shear conditions; d. After dispersion is complete, the polyamine chain extender is slowly added to the system to obtain a modified waterborne polyurethane dispersion emulsion; e. Add another portion of the modified monomer to the modified waterborne polyurethane dispersion emulsion to swell, add an initiator to carry out free radical polymerization, and remove the acetone after polymerization to obtain the modified polyurethane dispersion.

13. The preparation method according to claim 12, wherein, The portion of modified monomers mentioned in step b refers to 50-70% of the total amount of modified monomers.

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