CN114773535A - A kind of fluorine-free urethane waterproof emulsion and its preparation and application - Google Patents

Abstract

The invention relates to a fluorine-free urethane waterproof emulsion and a preparation method thereof, which are prepared from the following raw materials in percentage by weight: polyol 16-24%, catalyst 0.07-0.09%, polyisocyanate 4-6% , 1-2% of surfactant, 1-2% of end-capping agent, 2-4% of hydrophobic monomer, 0.015-0.03% of initiator, and the balance is water. The water-based waterproof emulsion provided by the present invention not only has good waterproof performance and mechanical performance, but also has certain surface decontamination and good texture on the treated fabric, so it can be widely used in clothing, protective clothing, carpets, etc. , furniture decoration materials, clothing and other fields and products, thereby improving the application value of waterproof coatings.

Description

A kind of fluorine-free urethane waterproof emulsion and its preparation and application

technical field

The invention relates to a fluorine-free urethane waterproof emulsion and a preparation method thereof, which can be used for the preparation of an aqueous polyurethane composition for imparting durable water resistance and detergency to textiles, and belongs to the field of waterproof materials in the textile industry.

Background technique

Fluorocarbon water repellents are the most advanced chemical water repellents at present, but such water repellents contain perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), fluorotelomer alcohol (FTOH) and other substances. A large number of studies have confirmed that PFOA and PFOS are currently one of the most refractory organic pollutants in the world. They have persistent environmental stability, high bioaccumulation, and strong environmental migration capabilities. The United Nations has included them in the list of POPs. disabled in. Therefore, the development of environmentally friendly fluorine-free waterproofing agents is in line with the needs of the times.

Water-based polyurethane waterproof coating is a new type of high-resolution waterproof coating developed in Europe, America and Japan in the 1960s. The research of polyurethane waterproof coating in my country started in the 1970s, developed rapidly in the 1990s and has been widely promoted and popularized.

Water-based polyurethane has the advantages of environmental protection and low energy consumption. Water-based polyurethane with waterproof properties can form a durable water-repellent film on the surface of the fabric, thereby achieving waterproof function. However, due to a serious disadvantage, it uses water as a dispersant. Inevitably, hydrophilic groups such as -COOH or -OH will be introduced into the molecular structure. Due to the addition of hydrophilic monomers and the hydrophilicity of urethane and urea bonds, their water resistance is higher than that of solvent-based polyurethane coatings. Much worse, limiting its scope of use. In order to overcome a series of problems such as poor water resistance of ordinary water-based polyurethane waterproof coatings and poor hand-feeling of fabrics, this patent introduces polyols with long carbon chains and polyisocyanates with cyclic structures, and invents a kind of polyisocyanates that can provide better textile substrates. Fluorine-free urethane water repellent emulsion with high water and stain release properties.

SUMMARY OF THE INVENTION

The invention provides a fluorine-free urethane waterproof emulsion and a preparation method thereof. The aqueous polyurethane emulsion of the invention has low pollution, excellent waterproof performance, and certain decontamination performance.

The present invention is achieved through the following technical solutions:

A fluorine-free urethane waterproof emulsion and a preparation method thereof are specifically implemented according to the following steps:

Step 1. Weigh the following raw materials according to mass percentage:

Polyol 16-24% (preferably 19.5-23.5%), catalyst 0.07-0.09% (preferably 0.08-0.09%), isocyanate and/or polyisocyanate 4-6% (preferably 4.5-6%), surfactant 1- 2% (preferably 1.2-1.8%), capping agent 1-2% (preferably 1.4-1.6%), hydrophobic monomer 2-4% (preferably 2.6-3.4%), initiator 0.015-0.03% (preferably 0.02- 0.03%), the balance is water;

Step 2, premixing the polyhydric alcohol weighed in step 1 with the dried acetone after refluxing for dewatering, passing nitrogen, heating and stirring to obtain an alcohol solution mixture;

Step 3. Add the isocyanate and/or polyisocyanate weighed in step 1 to the alcohol mixture in step 2, add a solvent with a mass of 1:1 polyol to reduce the viscosity of the system, continue to maintain a nitrogen atmosphere, and raise to a certain temperature Then add the catalyst, stir and react in an oil bath, and cool down after the -NCO content reaches 3-3.5% to obtain a urethane prepolymer;

Step 4. Add the end-capping agent to the prepolymer for reaction, and cool down after the -NCO content is lower than 0.1-0.3%; then add the hydrophobic monomer to the above solution, and continue to mix and stir for 30-40min post cooling

Step 5. Slowly add deionized water to the solution in step 4, and at the same time disperse at a high speed under the condition of a gauge pressure of 300-500KPa to obtain an aqueous polyurethane coarse emulsion;

Step 6, adding the above-mentioned initiator to the coarse emulsion of step 5, raising the temperature for reaction, continuing to disperse uniformly at a high speed under the condition of a gauge pressure of 300-500Kpa after the reaction, and then carrying out reduced-pressure distillation to remove the solvent, and cooling to obtain a water-based solution Polyurethane emulsion.

The feature of the present invention also lies in:

The polyol is selected from sorbitan fatty acid esters. The sorbitan fatty acid ester is preferably selected from any one or two or more mixtures in the sorbitan fatty acid ester obtained from mono-substituted, di-substituted or tri-substituted alcohol hydroxyl groups of fatty acids; the sorbitan fatty acid ester is composed of , dehydrated sorbitol is formed by esterification with fatty acids containing chain-like hydrocarbyl groups having 7 to 21 carbons. The initiator is selected from inorganic peroxides (such as one or more of potassium persulfate, ammonium persulfate and benzoyl peroxide) or azo compounds (such as 2,2-azobisisobutyronitrile (AIBN) , any one or two or more of 4,4-azobis(4-cyanovaleric acid) and azodicarbonamide.

Surfactant is a mixture of nonionic surfactant and cationic surfactant, preferably one or more of fatty alcohol polyoxyethylene ether or polyethylene glycol trimethyl nonyl ether and hexadecyl trimethyl ether. The mixture of ammonium bromide, their mixing mass ratio (nonionic surfactant: cationic surfactant) is 1:1-3.

The end-capping agent is any one of 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate and hydroxyethyl acrylate.

The hydrophobic monomer is any one or more of methyl methacrylate, ethyl methacrylate, and butyl methacrylate.

The catalyst is any one or more of zinc isooctanoate, tin isooctanoate and bismuth isooctanoate.

In step 2, the temperature of the polyol reflux dewatering oil bath is controlled at 105-110°C, the reflux time is 2-3h, after the reflux is completed, nitrogen is purged for 0.2h, and the acetone is subjected to 4A molecular sieve for 24h to stand for dewatering treatment, and two The temperature of the mixing oil bath is controlled at 45-55°C, the mixing and stirring time is 0.2-0.5h, and the rotating speed is 300-450r/min.

In step 3, the reaction temperature of the oil bath is controlled at 80-90°C, the mixing and stirring time is 0.5-1h, the reaction time is 2-3h, and the rotation speed is 400-500r/min; the cooling temperature of the oil bath is controlled at 70-75°C , the speed is 300-450r/min.

In steps 4 and 5, the end capping temperature is controlled at 70-75°C, deionized water needs to be added slowly, and high-speed shear dispersion is performed at the same time, the emulsification and dispersion temperature is controlled at 45-50°C, and the emulsification and dispersion time is 0.3-0.5h , the speed is 900-1200r/min.

In step 6, the initiation temperature is controlled at 70-80°C, the reaction time is 3-4h, the rotating speed is 900-1200r/min, the vacuum degree of the suction filtration is controlled at 0.01-0.02Mpa, and the suction filtration time is 0.3-0.5h, The suction filtration temperature is 75-85°C.

The water-based waterproof emulsion provided by the present invention not only has good waterproof performance and mechanical performance, but also has certain surface decontamination and good texture on the treated fabric, so it can be widely used in clothing, protective clothing, carpets, etc. , furniture decoration materials, clothing and other fields and products, thereby improving the application value of waterproof coatings.

Detailed ways

Example 1

Weigh 23g of sorbitan trilaurate and reflux for 120min under the condition of oil bath temperature of 105 ℃, and continue to pass nitrogen, after the reflux, use the nitrogen purge of 25mL/min for 15min to remove sorbitan trilaurate Moisture in the acid fatty acid ester, dry 5g of acetone (AT) placed in an airtight container with 10g 4A molecular sieves for 24h, remove the water in the acetone, put acetone and sorbitan trilaurate in the equipment In a three-necked flask with an overhead stirrer, the reaction system was protected by _N2 , and the system was strictly controlled to be anhydrous and oxygen-free. all solids melted;

Weigh 6g of IPDI trimer (IDT 70S) and appropriately add solvent butyl acetate (BuAc, 23g), stir and mix it and add it to the flask (addition time is 2-5s), observe the viscosity of the system, mix and stir for 1h, then Then add the catalyst zinc isooctanoate and tin isooctanoate mixture (0.08g, mass ratio 1:1), and raise the temperature of the system to 85 ° C, continue to pass nitrogen, and react for 3h; NCO (isocyanate) is detected by the di-n-butylamine method. base) content, the NCO mass fraction is 3.24%, and it is judged that the reaction is complete;

Experimental steps of the di-n-butylamine method: accurately weigh 5g of urethane prepolymer into a dry 250ml conical flask, use a 20ml graduated cylinder to measure 20ml of toluene into the conical flask, and use a 20ml large belly pipette to accurately pipette 20ml Di-n-butylamine solution was placed in a triangular flask, and fully shaken. After standing for 20 minutes, use a 100ml graduated cylinder to measure 100ml of isopropanol in the triangular flask, shake, add 2-3 drops of bromocresol green indicator, and use 1mol/L The HCl standard solution was titrated until the sample solution changed from blue to yellow-green.

Calculation formula:

V ₀ : the volume (mL) of the standard hydrochloric acid solution consumed by the blank titration; V ₁ : the volume (mL) of the standard hydrochloric acid solution consumed by the sample titration; m: the sample mass (g), W is the isocyanate mass fraction, and c is the standard hydrochloric acid solution Molar concentration (mol/L), blank titration refers to titration without urethane prepolymer.

Cool the system to 75°C, add the capping agent 2-hydroxyethyl acrylate (1.6g), and detect the NCO content by the di-n-butylamine method. If the NCO mass fraction is less than 0.1%, it is judged that the reaction is complete, and the system is cooled to At 45°C, add the hydrophobic monomers methyl methacrylate (0.9 g) and butyl methacrylate (2.0 g), and appropriately increase the speed of the stirring bar to 450 r/min, and continue to mix and stir for 35 minutes to obtain a prepolymer solution .

Weigh deionized water (65g) into a beaker, dissolve fatty alcohol polyoxyethylene ether (AEO-9, 0.6g) and cetyltrimethylammonium bromide (CTAB, 0.9g) in deionized water , slowly drop deionized water into the emulsifier, and emulsification at a high speed of 1000r/min under the pressure of 400KPa gauge pressure for 20min;

The obtained emulsion solution was transferred from the emulsifying machine to a three-necked flask, potassium persulfate (KPS, 0.02 g) was added, and the reaction was carried out at a temperature of 80 ° C for 3 h, and then the crude emulsion was transferred to the emulsifying machine to make it Continuous high-speed emulsification and dispersion for 0.5h at a speed of 1000r/min and a gauge pressure of 400KPa;

Finally, under the condition of 0.01Mpa vacuum degree, keep 80°C for 30min distillation, remove the solvent butyl acetate and acetone, and obtain an aqueous polyurethane emulsion with a solid content of about 33% after cooling. The obtained emulsion was evenly sprayed on the surface of the textile by spraying. The treated textile was pre-baked at 100 °C for 1 min, then dried at 130 °C for 5 min, and flattened for use. The wettability test was carried out according to ISO 4920-1981 standard.

Example 2

The synthesis steps of Example 2 are the same as those of Example 1, except that the raw material sorbitan trilaurate is changed to sorbitan tristearate, and the value of NCO:OH remains unchanged. An aqueous polyurethane emulsion with a solid content of 34% was obtained. The obtained emulsion was evenly sprayed on the surface of the textile by spraying. The treated textile was pre-baked at 100 °C for 1 min, then dried at 130 °C for 5 min, and flattened for use. The wettability test was carried out according to ISO 4920-1981 standard.

Example 3

The synthetic steps of Example 3 are the same as those of Example 1, except that the raw material sorbitan trilaurate is replaced with sorbitan trioleate, and the value of NCO:OH remains unchanged. An aqueous polyurethane emulsion with a solid content of 32% was obtained. The obtained emulsion was evenly sprayed on the surface of the textile by spraying. The treated textile was pre-baked at 100°C for 1min, then dried at 130°C for 5min, flattened for use, and tested for wettability according to the ISO 4920-1981 standard.

Example 4

The synthesis step of Example 4 is the same as that of Example 1, except that the amount of sorbitan trilaurate is increased to 24 g. An aqueous polyurethane emulsion with a solid content of 33% was obtained. The obtained emulsion was evenly sprayed on the surface of the textile by spraying. The treated textile was pre-baked at 100 °C for 1 min, then dried at 130 °C for 5 min, and flattened for use. The wettability test was carried out according to ISO 4920-1981 standard.

Example 5

The synthesis steps of Example 5 are the same as those of Example 1, except that the amount of sorbitan trilaurate is reduced to 16 g. An aqueous polyurethane emulsion with a solid content of 33% was obtained. The obtained emulsion was evenly sprayed on the surface of the textile by spraying. The treated textile was pre-baked at 100 °C for 1 min, then dried at 130 °C for 5 min, and flattened for use. The wettability test was carried out according to ISO 4920-1981 standard.

Example 6

The synthesis steps of Example 6 are the same as those of Example 1, except that the amount of hydrophobic monomer methyl methacrylate is increased to 1.5 g, and the amount of butyl methacrylate is increased to 3.2 g. An aqueous polyurethane emulsion with a solid content of 33% was obtained. The obtained emulsion was evenly sprayed on the surface of the textile by spraying. The treated textile was pre-baked at 100 °C for 1 min, then dried at 130 °C for 5 min, and flattened for use. The wettability test was carried out according to ISO 4920-1981 standard.

Example 7

The synthesis steps of Example 7 are the same as those of Example 1, except that the amount of hydrophobic monomer methyl methacrylate is reduced to 0.5 g, and the amount of butyl methacrylate is reduced to 1.5 g. An aqueous polyurethane emulsion with a solid content of 31% was obtained. The obtained emulsion was evenly sprayed on the surface of the textile by spraying. The treated textile was pre-baked at 100 °C for 1 min, then dried at 130 °C for 5 min, and flattened for use. The wettability test was carried out according to ISO 4920-1981 standard.

Example 8

The synthesis steps of Example 8 were the same as those of Example 1, except that the amount of IPDI trimer was increased to 6.5 g. An aqueous polyurethane emulsion with a solid content of 36% was obtained. The obtained emulsion was evenly sprayed on the surface of the textile by spraying. The treated textile was pre-baked at 100°C for 1min, then dried at 130°C for 5min, flattened for use, and tested for wettability according to the ISO4920-1981 standard.

Example 9

The synthesis steps of Example 9 were the same as those of Example 1, except that the amount of IPDI trimer was reduced to 4 g. An aqueous polyurethane emulsion with a solid content of 30% was obtained. The obtained emulsion was evenly sprayed on the surface of the textile by spraying. The treated textile was pre-baked at 100°C for 1min, then dried at 130°C for 5min, flattened for use, and tested for wettability according to the ISO4920-1981 standard.

Example 10

The synthesis steps of Example 10 are the same as those of Example 1, except that an aqueous prepolymer is prepared without (without adding) an isocyanate compound, and is emulsified with a surfactant solution to obtain an aqueous polyurethane emulsion. The prepared emulsions were diluted and applied to textiles and tested for wettability according to the ISO 4920-1981 standard. The obtained emulsion was evenly sprayed on the surface of the textile by spraying. The treated textile was pre-baked at 100 °C for 1 min, then dried at 130 °C for 5 min, and flattened for use. The wettability test was carried out according to ISO 4920-1981 standard.

Example 11

The synthesis steps of Example 11 are the same as those of Example 1, except that the water-based prepolymer is prepared without (without adding) alcohols, and is emulsified with the surfactant solution to obtain the water-based polyurethane emulsion. The obtained emulsion was evenly sprayed on the surface of the textile by spraying. The treated textile was pre-baked at 100 °C for 1 min, then dried at 130 °C for 5 min, and flattened for use. The wettability test was carried out according to ISO 4920-1981 standard.

Example 12 is a blank control, and the synthesis steps are the same as those of Example 1, except that the aqueous prepolymer is prepared without (without adding) isocyanate compounds and alcohols, and only surfactant solution is used. The surfactant solution is evenly sprayed on the surface of the textile by spraying. The treated textile is pre-baked at 100°C for 1min, then dried at 130°C for 5min, flattened for use, and tested for wettability according to ISO 4920-1981. .

Table 1 is the wettability performance test results of Examples 1-10

Example cotton Polyester Chun Yafang Example 1 100 100 100 Example 2 90 100 100 Example 3 100 100 90 Example 4 90 100 100 Example 5 90 90 90 Example 6 90 100 90 Example 7 90 90 100 Example 8 90 80 90 Example 9 80 90 80 Example 10 50 70 60 Example 11 50 50 50 Example 12 0 0 0

Table 2 shows the test results of the detergency performance of the cotton cloth of Example 1-12: the detergency performance is based on GB/T 30159.1-2013 "Detection and Evaluation of the Antifouling Properties of Textiles Part 1: Stain Resistance" to the stain resistance of textiles Evaluation was performed using the liquid stain method.

Comparative ratio

Compared with the fluorine-free products currently available in the market and reported by patents, the fluorine-free urethane waterproof emulsion synthesized in this specification has the wettability and decontamination performance on cotton, polyester fiber and spring sub-textile under the same fabric treatment. Higher performance. The fluorine-free waterproof emulsion of the present invention can achieve the waterproof effect of the commercially available fluorine-containing products, but compared with the fluorine-containing products, the present invention has the advantages of safety and environmental protection, and the treated fabric has a better hand feeling.

Comparative Example 1

We purchased the commercially available fluorine-free water repellent HGST-1692S produced by Suzhou Huangyongyuan Chemical Industry, with an effective solid content of 30%. The results are compared with the present invention.

Comparative Example 2

We purchased the commercially available fluorine-free water repellent YZ-5505A produced by Suzhou Yize Textile Technology Co., Ltd. with an effective solid content of 35%. Test, the test results are compared with the present invention.

Comparative Example 3

We prepared a fluorine-free water repellent according to patent CN 107278221 A. The solid content of the water repellent prepared by this method is 30%, but the reaction requirements are more complicated, and a large amount of organic solvent is also used, which is not easy to recycle and pollutes the environment. We use the same process as the present invention to process the fabric, and carry out corresponding tests, and the test results are compared with the present invention.

Comparative Example 4

We purchased the commercially available fluorine-containing water repellent TG-5671 produced by Daikin Company, with an effective solid content of 30%. The purchased product was treated with the same process as the present invention, and the corresponding tests were carried out. The test results Compare with the present invention.

Comparative Example 5

We prepared a fluorine-free water repellent according to patent CN 103396510 A, the solid content of the water repellent prepared by this method is 30%, and the preparation steps are complicated. We use the same process as the present invention to process the fabric, and carry out corresponding tests, the test results are compared with the present invention Comparative Example 6

The synthesis step of Comparative Example 6 is the same as that of Example 1, except that the amount of sorbitan trilaurate is increased to 30 g. An aqueous polyurethane emulsion with a solid content of 36% was obtained. We use the same process as the present invention to process the fabric, and carry out corresponding tests, and the test results are compared with the present invention.

Comparative Example 7

The synthesis steps of Comparative Example 7 are the same as those of Example 1, except that the amount of the hydrophobic monomer methyl methacrylate is increased to 5.0 g to obtain an aqueous polyurethane emulsion with a solid content of 38%. We use the same process as the present invention to process the fabric, and carry out corresponding tests, and the test results are compared with the present invention.

Comparative Example 8

The synthesis steps of Comparative Example 8 were the same as those of Example 1, except that the amount of IPDI trimer was increased to 5.0 g to obtain an aqueous polyurethane emulsion with a solid content of 31%. We use the same process as the present invention to process the fabric, and carry out corresponding tests, and the test results are compared with the present invention.

The following is the product of the present invention (Example 1) and the products reported in the fluorine-free water repellent HGST-1692 S, YZ-5505 A, fluorine-containing water repellent agent TG-5671, patent CN 103396510 A currently on the market, and patent CN 107278221 A. The performance and cost of Comparative Example 6, Comparative Example 7 and Comparative Example 8 are shown in Table 3, and the stainability on the treated cotton cloth is shown in Table 4.

table 3

Table 4

Example milk red ink Corn oil soy sauce this invention 5 5 5 5 Comparative Example 1 4 4 4 4 Comparative Example 2 4 4 4 4 Comparative Example 3 3 3 3 4 Comparative Example 4 5 5 5 5 Comparative Example 5 4 3 4 3 Comparative Example 6 3 4 3 4 Comparative Example 7 3 4 4 3 Comparative Example 8 4 4 4 4

From the comparison results, it can be seen that the fluorine-free urethane waterproof emulsion prepared by the present invention is compared with commercially available fluorine-free waterproofing agents, products synthesized by similar patents and emulsions prepared in non-preferred ratios. Under the same fabric treatment, cotton cloth, The wetting performance and decontamination performance of polyester fiber and spring sub-fabric are higher, and the waterproof effect of commercially available fluorine-containing products can be achieved. However, compared with fluorine-containing products, the invention has the advantages of safety and environmental protection. The fabric feels better.

Claims (10)

1. A fluorine-free urethane waterproof emulsion, characterized in that, its raw materials comprise by weight percentage: polyol 16-24% (preferably 19.5-23.5%), catalyst 0.07-0.09% (preferably 0.08-0.09%) %), isocyanate and/or polyisocyanate 4-6% (preferably 4.5-6%), surfactant 1-2% (preferably 1.2-1.8%), blocking agent 1-2% (preferably 1.4-1.6%) , hydrophobic monomer 2-4% (preferably 2.6-3.4%), initiator 0.015-0.03% (preferably 0.02-0.03%), and the balance is water. 2. waterproof emulsion according to claim 1, is characterized in that, described polyhydric alcohol is sorbitan fatty acid ester; The sorbitan fatty acid ester is preferably selected from any one or two or more mixtures in the sorbitan fatty acid ester obtained from mono-substituted, di-substituted or tri-substituted alcohol hydroxyl groups of fatty acids; the sorbitan fatty acid ester is composed of , dehydrated sorbitol and fatty acids containing chain hydrocarbon groups with 7 to 21 carbons are generated by esterification; The initiator is selected from inorganic peroxides (such as one or more of potassium persulfate, ammonium persulfate and benzoyl peroxide) or azo compounds (such as 2,2-azobisisobutyronitrile ( AIBN), 4,4-azobis (4-cyanovaleric acid) and one or more of azodicarbonamide) any one or two or more. 3. The waterproof emulsion according to claim 1, wherein the surfactant is a mixture of nonionic surfactant and cationic surfactant, preferably fatty alcohol polyoxyethylene ether or polyethylene glycol trimethyl A mixture of one or more of nonyl ethers and cetyl trimethyl ammonium bromide, their mixing mass ratio (nonionic surfactant: cationic surfactant) is 1:1-1:3 . 4. The waterproof emulsion according to claim 1, wherein the end-capping agent is any one of acrylic acid-2 hydroxyethyl acrylate, 4-hydroxybutyl acrylate, and hydroxyethyl acrylate; The hydrophobic monomer is any one or more than two of methyl methacrylate, ethyl methacrylate and butyl methacrylate; The catalyst is any one or more than two of zinc isooctanoate, tin isooctanoate and bismuth isooctanoate. 5. the preparation method of the waterproof emulsion described in any one of claim 1-4, is characterized in that, comprises the following steps: Step 1, premixing the polyol with dried acetone after dewatering, heating and stirring evenly under nitrogen protection to obtain an alcohol solution mixture; Step 2. Add the isocyanate and/or polyisocyanate to the alcohol mixture in step 1, add a solvent with a mass ratio of 1:1-1:1.5 to the polyol to reduce the viscosity of the system, continue to maintain a nitrogen atmosphere, and rise to After the reaction temperature, the catalyst is added, and the reaction is stirred. After the -NCO content reaches 3-3.5%, the temperature is lowered to obtain a urethane prepolymer; Step 3, adding the end-capping agent to the prepolymer for reaction, cooling down after the -NCO content is less than 0.1-0.3%, then adding the hydrophobic monomer to the above solution, and continuing to mix and stir for 30-40min; Step 4, dissolving the surfactant in water, adding the aqueous solution containing the surfactant to the solution in step 3, and at the same time dispersing uniformly at a high speed under the condition of 300-500Kpa gauge pressure to obtain an aqueous polyurethane coarse emulsion; Step 5. Add the initiator to the coarse emulsion of step 4, raise the temperature to react, continue to disperse uniformly at a high speed under the condition of 300-500Kpa gauge pressure after the reaction, and then carry out vacuum distillation to remove excess solvent and acetone, and after cooling An aqueous polyurethane emulsion was obtained. 6. The method for preparing a waterproof emulsion according to claim 5, wherein in step 1, the reflux temperature of the polyol raw material is controlled at 105-110°C, the reflux time is 2-3h, and the Nitrogen (nitrogen flow rate is 20-25mL/min) is purged for 0.1-0.3h; the used acetone is left standing in molecular sieves for 24-36h to remove water; the mixing temperature of the two is controlled at 45-55°C, and the mixing and stirring time is 0.2-0.5h, the speed is 300-450r/min. 7. The preparation method of waterproof emulsion according to claim 5, is characterized in that, in step 2, adding isocyanate and/or polyisocyanate time is 2-5s, and system keeps nitrogen atmosphere all the time, and described reaction temperature is controlled at 80 ℃ -90℃, mixing and stirring time is 0.5-1h, reaction time is 2-3h, rotating speed is 400-500r/min; cooling temperature is controlled at 70-75℃, rotating speed is 300-450r/min; solvent is butyl acetate, One or more of ethyl acetate, butanone and acetone. 8 . The method for preparing a waterproof emulsion according to claim 5 , wherein, in steps 3 and 4, the end-capping reaction temperature is controlled at 70-75° C., and the hydrophobic monomer is added and the emulsification and dispersion temperature after addition is controlled at 70-75° C. 9 . The temperature is controlled at 45-50℃, the emulsification and dispersion time is 0.3-0.5h, and the rotating speed is 900-1200r/min. 9. The preparation method of waterproof emulsion according to claim 5, characterized in that, in step 5, the initiating reaction temperature is controlled at 70-80°C, the reaction time is 3-4h, and the high-speed dispersing rotation speed is 900-1200r/ min, the vacuum degree of the vacuum distillation is controlled at 0.01-0.02Mpa, the time is 0.3-0.5h, and the temperature is 75-85°C. 10. The application of the waterproof emulsion of any one of claims 1-4 in the waterproofing process of textiles.