A kind of sewage resistant polyurethane and preparation method thereof

Abstract

The present application discloses a sewage-resistant polyurethane and a preparation method thereof, and relates to the field of coatings. The sewage-resistant polyurethane comprises 10-15 parts of silicone polyol, 4.5-8.5 parts of polyether diol, 13-15 parts of diisocyanate, 2-4 parts of chain extender, 1-2 parts of neutralizer, 0.01-0.015 parts of catalyst, 24-28 parts of acetone, and 60-70 parts of water. The silicone polyol comprises hydroxy silicone oil and fluorine-containing silicone polyol, and the weight ratio of hydroxy silicone oil to fluorine-containing silicone polyol is 1: (3-4), and the fluorine-containing silicone polyol is prepared by hydrosilylation reaction of fluorine-terminated hydrogen-containing silicone oil and vinyl-terminated hydroxyl silicone oil in a molar ratio of 1: (2-2.25), and the chain extender comprises a carboxylic acid chain extender and an amine chain extender, and the weight ratio of the carboxylic acid chain extender to the amine chain extender is (2-2.5): 1. The sewage-resistant polyurethane of the present application has excellent surface hydrophobicity and scratch resistance, and can effectively improve the stain resistance of the coating.

Description

Technical Field

[0001] The present application relates to the field of coatings, and in particular to a sewage-resistant polyurethane and a preparation method thereof. Background Art

[0002] Polyurethane coatings are widely used in automotive interior leather coatings. Among them, traditional polyurethane coatings are prepared from polyether diols or polyester diols with diisocyanate, catalysts, chain extenders, neutralizers, acetone and water. These polyurethane coatings have the characteristics of good flexibility. However, the above polyurethane coatings have the following two disadvantages: first, the polyurethane coatings have poor hydrophobicity and dirt is easy to adhere to; second, the polyurethane coatings have poor scratch resistance. The polyurethane coatings are prone to scratches after being scratched, and dirt is easy to hide in the scratches, and the dirt in the scratches is difficult to remove.

[0003] In order to improve the poor stain resistance of traditional polyurethane coatings, related technologies have introduced silicone to modify polyurethane, such as using hydroxy silicone oil and polyether diol or polyester diol as a polymer diol, and then preparing silicone-modified polyurethane coatings with diisocyanate, catalyst, chain extender, etc. Among them, the hydrophobicity of silicone-modified polyurethane coatings in related technologies has been improved, which can reduce the adhesion of dirt, but it still needs to be improved. In addition, the scratch resistance of silicone-modified polyurethane coatings has not been significantly improved, and the polyurethane coating is still easily scratched by scratches, thereby hiding dirt. Summary of the invention

[0004] In order to improve the problem of poor stain resistance of polyurethane coatings in the related art, the present application provides a sewage-resistant polyurethane and a preparation method thereof.

[0005] In the first aspect, the present application provides a sewage resistant polyurethane adopting the following technical solution:

[0006] A sewage resistant polyurethane comprises the following raw materials in parts by weight:

[0007] Silicone polyol: 10-15 parts;

[0008] Polyether diol: 4.5-8.5 parts;

[0009] Diisocyanate: 13-15 parts;

[0010] Chain extender: 2-4 parts;

[0011] Neutralizer: 1-2 parts;

[0012] Catalyst: 0.01-0.015 parts;

[0013] Acetone: 24-28 parts;

[0014] Water: 60-70 parts;

[0015] The organosilicon polyol comprises hydroxy silicone oil and fluorine-containing organosilicon polyol, the weight ratio of the hydroxy silicone oil to the fluorine-containing organosilicon polyol is 1:(3-4), the fluorine-containing organosilicon polyol is prepared by a hydrosilylation reaction of fluorine-containing terminal hydrogen-containing silicone oil and vinyl-terminated hydroxyl-terminated silicone oil in a molar ratio of 1:(2-2.25), and the chain extender comprises a carboxylic acid chain extender and an amine chain extender, the weight ratio of the carboxylic acid chain extender to the amine chain extender is (2-2.5):1.

[0016] The present application obtains isocyanate-terminated prepolymer by reacting hydroxy silicone oil, fluorinated organosilicon polyol, polyether diol and diisocyanate, and then obtains sewage-resistant polyurethane by chain extension reaction with carboxylic acid-type chain extender, amine chain extender and isocyanate-terminated prepolymer. Among them, the use of hydroxy silicone oil and fluorinated organosilicon polyol to modify polyurethane can effectively improve the surface hydrophobicity of the sewage-resistant polyurethane, so that the sewage-resistant polyurethane is not easy to adhere to stains such as soy sauce and milk, which is conducive to improving the stain resistance of the coating. In addition, the hydroxy silicone oil and fluorinated organosilicon polyol work together to improve the scratch resistance of the sewage-resistant polyurethane, so that the sewage-resistant polyurethane is not easy to scratch, so as not to cause the problem of poor stain resistance caused by dirt and dirt hiding in the scratches.

[0017] Optionally, the structural formula of the hydroxy silicone oil is HO[(CH3)2SiO] a H, where the value of a is 12-20.

[0018] As the degree of polymerization a of the dimethylsiloxane segment in the hydroxy silicone oil increases, the interaction between molecules is enhanced, and the surface hydrophobicity, scratch resistance and heat resistance of the sewage resistant polyurethane are enhanced. However, when the degree of polymerization a of the dimethylsiloxane segment in the hydroxy silicone oil is too high, the dispersibility between the hydroxy silicone oil and other raw materials will deteriorate, which is not conducive to obtaining a sewage resistant polyurethane that is stable in storage and not prone to stratification. Therefore, in this application, the degree of polymerization a of the dimethylsiloxane segment in the hydroxy silicone oil is controlled within the range of 12-20, which is conducive to obtaining a sewage resistant polyurethane that has both stain resistance, scratch resistance, heat resistance, storage stability, and is not prone to stratification.

[0019] Optionally, the structural formula of the fluorine-containing hydrogen-terminated silicone oil is as follows:

[0020]

[0021] Among them, the value of m is 5-8, and the value of n is 10-15.

[0022] In the present application, the fluorine-terminated hydrogen-containing silicone oil includes a trifluoropropylmethylsiloxane segment and a dimethylsiloxane segment, wherein when the degree of polymerization m of the trifluoropropylmethylsiloxane segment is controlled at 5-8 and the degree of polymerization n of the dimethylsiloxane segment is controlled at 10-15, a sewage-resistant polyurethane having stain resistance, scratch resistance and heat resistance can be obtained, and at the same time, the storage stability of the sewage-resistant polyurethane can be further improved.

[0023] Optionally, the structural formula of the vinyl-terminated hydroxyl-terminated silicone oil is as follows:

[0024]

[0025] Among them, the value of t is 3-6.

[0026] The degree of polymerization t of the dimethylsiloxane segment in the vinyl-terminated hydroxyl-terminated silicone oil of the present application is controlled within the range of 3-6, so that a sewage-resistant polyurethane having stain resistance, scratch resistance and heat resistance can be obtained, and at the same time, the storage stability of the sewage-resistant polyurethane can be further improved.

[0027] Optionally, the method for preparing the fluorinated organosilicon polyol comprises the following steps:

[0028] (1) After mixing fluorine-containing hydrogen-terminated silicone oil and vinyl-terminated hydroxyl-terminated silicone oil in a molar ratio, adding a solvent and a platinum catalyst, stirring evenly, to obtain a premix; wherein the amount of the solvent is 50-60% of the total weight of the fluorine-containing hydrogen-terminated silicone oil and the vinyl-terminated hydroxyl-terminated silicone oil, and the amount of the platinum catalyst is 0.5-0.8% of the total weight of the fluorine-containing hydrogen-terminated silicone oil and the vinyl-terminated hydroxyl-terminated silicone oil;

[0029] (2) Under nitrogen protection, the premix is ​​heated to 75-85° C., refluxed for 3-4 hours, and then the solvent is removed to obtain a fluorinated organosilicon polyol.

[0030] Optionally, the polyether diol is at least one of polytetramethylene ether diol and polyoxypropylene diol.

[0031] In the present application, the polyether diol can be common polyether diols such as polytetrahydrofuran ether diol and polyoxypropylene diol. Among them, the polyether diol is further preferably polytetrahydrofuran ether diol, because polytetrahydrofuran ether diol has excellent heat resistance and can improve the heat resistance of sewage resistant polyurethane.

[0032] Optionally, the molecular weight of the polyether diol is 1000-2000.

[0033] Optionally, the diisocyanate is at least one of an aliphatic diisocyanate and an aromatic diisocyanate.

[0034] In the present application, the diisocyanate may be at least one of aliphatic diisocyanate and aromatic diisocyanate, and aromatic diisocyanate is more preferably used, which is beneficial to further improve the scratch resistance.

[0035] Optionally, the neutralizing agent is at least one of triethylamine, triethanolamine, and diethanolamine.

[0036] In the second aspect, the present application provides a method for preparing sewage resistant polyurethane using the following technical solution:

[0037] A method for preparing sewage resistant polyurethane comprises the following steps:

[0038] After dehydrating the organosilicon polyol and polyether diol, add diisocyanate and catalyst, and under nitrogen protection, heat to 85-92°C for reaction for 2-2.5h, then add carboxylic acid chain extender and 30-40% of the total weight of acetone, continue to react for 1-1.5h, cool to 40-45°C, add the remaining acetone to reduce viscosity, then add neutralizer, stir evenly, add water, disperse at high speed, immediately add amine chain extender, continue to react for 1-1.5h, and finally vacuum to remove acetone to obtain sewage resistant polyurethane.

[0039] In the present application, the sewage-resistant polyurethane is prepared by the above method, which can obtain sewage-resistant polyurethane with good surface hydrophobicity and good scratch resistance, and the reaction process is easy to control, and the differences between different batches of products are small and the stability is good.

[0040] In summary, the technical solution of this application includes at least the following technical effects:

[0041] The present application obtains isocyanate-terminated prepolymer by reacting hydroxy silicone oil, fluorinated organosilicon polyol, polyether diol and diisocyanate, and then obtains sewage-resistant polyurethane by chain extension reaction with carboxylic acid-type chain extender, amine chain extender and isocyanate-terminated prepolymer. Among them, the use of hydroxy silicone oil and fluorinated organosilicon polyol to modify polyurethane can effectively improve the surface hydrophobicity of the sewage-resistant polyurethane, so that the sewage-resistant polyurethane is not easy to adhere to stains such as soy sauce and milk, which is conducive to improving the stain resistance of the coating. In addition, the hydroxy silicone oil and fluorinated organosilicon polyol work together to improve the scratch resistance of the sewage-resistant polyurethane, so that the sewage-resistant polyurethane is not easy to scratch, so as not to cause the problem of poor stain resistance caused by dirt and dirt hiding in the scratches. DETAILED DESCRIPTION

[0042] The present application is further described below in conjunction with specific experiments.

[0043] Example

[0044] [Example 1]

[0045] A sewage-resistant polyurethane comprises 10 kg of organosilicon polyol, 8.5 kg of polytetramethylene ether glycol PTMG1000 produced by Suihua Biotechnology, 13 kg of isophorone diisocyanate, 4 kg of chain extender, 2 kg of triethanolamine, 0.01 kg of dibutyltin dilaurate, 24 kg of acetone and 60 kg of water.

[0046] Among them, silicone polyols include hydroxy silicone oil and fluorinated silicone polyols, hydroxy silicone oil and

[0047] The weight ratio of the fluorinated silicone polyol is 1:3.

[0048] In this embodiment, the structural formula of hydroxy silicone oil is HO[(CH3)2SiO] a The value of H,a is 12;

[0049] The fluorinated organosilicon polyol is prepared by a fluorinated terminal hydrogen-containing silicone oil and a vinyl-terminated hydroxyl-terminated silicone oil in a molar ratio of 1:2 through a silylation reaction, wherein the structural formula of the fluorinated terminal hydrogen-containing silicone oil is as follows:

[0050]

[0051] The value of m is 5, and the value of n is 15;

[0052] The structural formula of vinyl-terminated hydroxyl-terminated silicone oil is as follows:

[0053] The value of t is 3.

[0054] The preparation method of fluorinated organosilicon polyol comprises the following steps:

[0055] (1) After mixing fluorine-containing hydrogen-terminated silicone oil and vinyl-terminated hydroxyl-terminated silicone oil in a molar ratio, tetrahydrofuran and chloroplatinic acid catalyst are added, and stirred evenly to obtain a premix; wherein the amount of tetrahydrofuran is 50% of the total weight of the fluorine-containing hydrogen-terminated silicone oil and the vinyl-terminated hydroxyl-terminated silicone oil, and the amount of chloroplatinic acid catalyst is 0.5% of the total weight of the fluorine-containing hydrogen-terminated silicone oil and the vinyl-terminated hydroxyl-terminated silicone oil;

[0056] (2) Under nitrogen protection, the premix is ​​heated to 75° C. and refluxed for 4 hours, and then tetrahydrofuran is removed to obtain a fluorinated organosilicon polyol.

[0057] In addition, the chain extender includes dimethylolpropionic acid and ethylenediamine, and the weight ratio of the dimethylolpropionic acid to the ethylenediamine is 2:1.

[0058] The preparation method of sewage resistant polyurethane comprises the following steps:

[0059] After dehydrating hydroxy silicone oil, fluorinated silicone polyol, and polytetramethylene glycol PTMG1000,

[0060] Isophorone diisocyanate and dibutyltin dilaurate were added, and the temperature was raised to 85°C for reaction for 2.5 hours under nitrogen protection. Then, 30% of the total weight of dimethylolpropionic acid and acetone were added, and the reaction was continued for 1 hour. The temperature was lowered to 40°C, and the remaining acetone was added to reduce the viscosity. Subsequently, triethanolamine was added, and water was added after stirring evenly. After high-speed dispersion, ethylenediamine was immediately added, wherein the time interval between the addition of ethylenediamine and the addition of water was no more than 3 minutes. The reaction was continued for 1.5 hours, and finally, the acetone was removed by vacuum to obtain a sewage-resistant polyurethane.

[0061] [Example 2]

[0062] A sewage-resistant polyurethane comprises 15 kg of organosilicon polyol, 4.5 kg of polytetramethylene ether glycol PTMG2000 produced by Suihua Biotechnology, 15 kg of diphenylmethane diisocyanate, 3 kg of chain extender, 1 kg of diethanolamine, 0.015 kg of dibutyltin dilaurate, 28 kg of acetone and 70 kg of water.

[0063] Among them, silicone polyols include hydroxy silicone oil and fluorinated silicone polyols, hydroxy silicone oil and

[0064] The weight ratio of the fluorinated silicone polyol is 1:4.

[0065] In this embodiment, the structural formula of hydroxy silicone oil is HO[(CH3)2SiO] a The value of H,a is 12;

[0066] The fluorinated organosilicon polyol is prepared by a fluorinated terminal hydrogen-containing silicone oil and a vinyl-terminated hydroxyl-terminated silicone oil in a molar ratio of 1:2.25 for a silylation reaction, wherein the structural formula of the fluorinated terminal hydrogen-containing silicone oil is as follows:

[0067]

[0068] The value of m is 5, and the value of n is 15;

[0069] The structural formula of vinyl-terminated hydroxyl-terminated silicone oil is as follows:

[0070] The value of t is 3.

[0071] The preparation method of fluorinated organosilicon polyol comprises the following steps:

[0072] (1) After mixing fluorine-containing hydrogen-terminated silicone oil and vinyl-terminated hydroxyl-terminated silicone oil in a molar ratio, tetrahydrofuran and chloroplatinic acid catalyst are added, and stirred evenly to obtain a premix; wherein the amount of tetrahydrofuran is 60% of the total weight of the fluorine-containing hydrogen-terminated silicone oil and the vinyl-terminated hydroxyl-terminated silicone oil, and the amount of chloroplatinic acid catalyst is 0.8% of the total weight of the fluorine-containing hydrogen-terminated silicone oil and the vinyl-terminated hydroxyl-terminated silicone oil;

[0073] (2) Under nitrogen protection, the premix is ​​heated to 85° C. and refluxed for 3 h, and then tetrahydrofuran is removed to obtain a fluorinated organosilicon polyol.

[0074] In addition, the chain extender includes dimethylolbutyric acid and ethylenediamine, and the weight ratio of dimethylolbutyric acid to ethylenediamine is 2.5:1.

[0075] The preparation method of sewage resistant polyurethane comprises the following steps:

[0076] After dehydrating hydroxy silicone oil, fluorinated silicone polyol and polytetramethylene glycol PTMG2000, diphenylmethane diisocyanate and dibutyltin dilaurate are added, and the temperature is raised to 92°C for reaction for 2 hours under nitrogen protection, and then 40% of the total weight of dihydroxymethylbutyric acid and acetone are added. After continuing the reaction for 1.5 hours, the temperature is lowered to 45°C, and the remaining acetone is added to reduce the viscosity, followed by adding diethanolamine. After stirring evenly, water is added, and after high-speed dispersion, ethylenediamine is immediately added, wherein the time interval between the addition of ethylenediamine and the addition of water is no more than 3 minutes. The reaction is continued for 1 hour, and finally vacuum removal of acetone is performed to obtain sewage-resistant polyurethane.

[0077] [Example 3]

[0078] A sewage resistant polyurethane, which differs from [Example 1] in that:

[0079] The value of a in hydroxy silicone oil is 20.

[0080] [Example 4]

[0081] A sewage resistant polyurethane, which differs from [Example 1] in that:

[0082] The value of a in hydroxy silicone oil is 30.

[0083] [Example 5]

[0084] A sewage resistant polyurethane, which differs from [Example 1] in that:

[0085] In the fluorine-terminated hydrogen-containing silicone oil, the value of m is 8 and the value of n is 10.

[0086] [Example 6]

[0087] A sewage resistant polyurethane, which differs from [Example 1] in that:

[0088] In the fluorine-terminated hydrogen-containing silicone oil, the value of m is 15 and the value of n is 5.

[0089] [Example 7]

[0090] A sewage resistant polyurethane, which differs from [Example 1] in that:

[0091] In vinyl-terminated hydroxyl-terminated silicone oil, the value of t is 6.

[0092] [Example 8]

[0093] A sewage resistant polyurethane, which differs from [Example 1] in that:

[0094] In vinyl-terminated hydroxyl-terminated silicone oil, the value of t is 15.

[0095] Comparative Example

[0096] [Comparative Example 1]

[0097] A waterborne polyurethane, which differs from [Example 1] in that:

[0098] The fluorinated silicone polyol is replaced by an equal amount of hydroxy silicone oil.

[0099] [Comparative Example 2]

[0100] A waterborne polyurethane, which differs from [Example 1] in that:

[0101] The hydroxy silicone oil is replaced by an equal amount of fluorinated organosilicon polyol.

[0102] Performance testing

[0103] 1. Stain resistance: The sewage-resistant polyurethane in each embodiment and comparative example was used to prepare the test sample. When preparing the test sample, the sewage-resistant polyurethane was evenly coated on the leather with a size of 20cm*20cm*0.5cm, and the coating thickness was controlled at 15μm. After drying, the test sample was obtained. Among them, 10 test samples were prepared from the sewage-resistant polyurethane in each embodiment and comparative example, and then 10g of soy sauce was evenly coated. After standing for 48 hours, the 10 test samples prepared in each embodiment and comparative example were divided into two groups, and the soy sauce stains on the coating were cleaned with running water. The cleaning time of one group was 30s, and the cleaning time of one group was 60s. It was observed whether the soy sauce stains were completely removed.

[0104] 2. Scratch resistance: The test samples were prepared using the sewage resistant polyurethane in each embodiment and comparative example. When preparing the test samples, the sewage resistant polyurethane was evenly coated on leather with a size of 20cm*20cm*0.5cm, and the coating thickness was controlled at 15μm. After drying, the test samples were obtained. Among them, 10 test samples were prepared from the sewage resistant polyurethane in each embodiment and comparative example, and the average pencil hardness of the 10 test samples was tested. The greater the hardness of the sewage resistant polyurethane, the better the scratch resistance. However, the greater the hardness of the sewage resistant polyurethane, the lower the toughness, and the performance of the water-based polyurethane in resisting bending becomes worse. According to practical experience, the hardness of the sewage resistant polyurethane can take into account both scratch resistance and good bending resistance within 2H-3H.

[0105] 3. Heat resistance: The sewage resistant polyurethane in each embodiment and comparative example was used to prepare the test sample. When preparing the test sample, the sewage resistant polyurethane was evenly coated on the leather with a size of 20cm*20cm*0.5cm, and the coating thickness was controlled at 15μm. After drying, the test sample was obtained. Among them, 10 test samples were prepared from the sewage resistant polyurethane in each embodiment and comparative example, and all the test samples were placed in an environment of 80℃ for 12h, then taken out and cooled to room temperature to observe whether the coating had cracking.

[0106] 4. Stability of sewage-resistant polyurethane: The stability of sewage-resistant polyurethane was simulated by centrifuge accelerated sedimentation test. The samples of each embodiment and comparative example were placed in a centrifuge and centrifuged at 2000 r / min and 4000 r / min, respectively. After 15 minutes, the sewage-resistant polyurethane was observed to see whether stratification occurred. The easier it was to stratify, the worse the storage stability of the sewage-resistant polyurethane was.

[0107] Table 1

[0108]

[0109] Table 2

[0110]

[0111]

[0112] The difference between Comparative Example 1 and Example 1 is that the fluorinated organosilicon polyol is replaced by an equal amount of hydroxy silicone oil. Combining the data in Tables 1 and 2, it can be seen that after the fluorinated organosilicon polyol is replaced by hydroxy silicone oil, the stain removal efficiency on the waterborne polyurethane coating is reduced, indicating that the stain resistance of the waterborne polyurethane coating is reduced. At the same time, the hardness of the waterborne polyurethane coating is reduced, the scratch resistance is reduced, and scratches are easily generated, resulting in a decrease in the stain resistance of the waterborne polyurethane coating. In addition, the heat resistance of the waterborne polyurethane coating is also deteriorated, and thermal cracking problems are prone to occur.

[0113] The difference between Comparative Example 2 and Example 1 is that the hydroxy silicone oil is replaced by an equal amount of fluorinated organosilicon polyol. Combining the data in Tables 1 and 2, it can be seen that after the hydroxy silicone oil is replaced by fluorinated organosilicon polyol, the storage stability of the water-based polyurethane coating is significantly reduced, and the surface smoothness of the water-based polyurethane coating is poor, resulting in a decrease in the stain removal efficiency on the water-based polyurethane coating, that is, the stain resistance of the water-based polyurethane coating is reduced.

[0114] The difference between Example 3-4 and Example 1 is that the value of a in the hydroxy silicone oil is different. Combining the data in Table 1-Table 2, it can be seen that the value of a in the hydroxy silicone oil is in the range of 12-20, which is conducive to further improving the storage stability of the sewage resistant polyurethane.

[0115] The difference between Example 5-6 and Example 1 is that the values ​​of m and n in the fluorine-terminated hydrogen-containing silicone oil are different. Combining the data in Table 1-Table 2, it can be seen that the value of m in the fluorine-terminated hydrogen-containing silicone oil is in the range of 5-8, and the value of n is in the range of 10-15, which is conducive to further improving the storage stability of the sewage-resistant polyurethane.

[0116] The difference between Example 7-8 and Example 1 is that the value of t in the vinyl-terminated hydroxyl-terminated silicone oil is different. Combining the data in Table 1-Table 2, it can be seen that the value of t in the vinyl-terminated hydroxyl-terminated silicone oil is in the range of 3-6, which is conducive to further improving the storage stability of the sewage resistant polyurethane.

[0117] This specific implementation manner is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the specific implementation manner as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A sewage resistant polyurethane, characterized in that: The invention comprises the following raw materials in parts by weight: Silicone polyol: 10-15 parts; Polyether diol: 4.5-8.5 parts; Diisocyanate: 13-15 parts; Chain extender: 3-4 parts; Neutralizer: 1-2 parts; Catalyst: 0.01-0.015 parts; Acetone: 24-28 parts; Water: 60-70 parts; The organosilicon polyol comprises hydroxy silicone oil and fluorine-containing organosilicon polyol, the weight ratio of the hydroxy silicone oil to the fluorine-containing organosilicon polyol is 1:(3-4), the fluorine-containing organosilicon polyol is prepared by hydrosilylation reaction of fluorine-containing terminal hydrogen-containing silicone oil and vinyl-terminated hydroxyl-terminated silicone oil in a molar ratio of 1:(2-2.25), the chain extender comprises a carboxylic acid chain extender and an amine chain extender, the weight ratio of the carboxylic acid chain extender to the amine chain extender is (2-2.5):1; The structural formula of the hydroxy silicone oil is HO[(CH3)2SiO] a H, where a is between 12 and 20; The structural formula of the fluorine-terminated hydrogen-containing silicone oil is as follows: ； Among them, the value of m is 5-8, and the value of n is 10-15; The structural formula of the vinyl-terminated hydroxyl-terminated silicone oil is as follows: ； Among them, the value of t is 3-6.

2. The sewage resistant polyurethane according to claim 1, characterized in that: The polyether diol is at least one of polytetrahydrofuran ether diol and polyoxypropylene diol.

3. The sewage resistant polyurethane according to claim 1, characterized in that: The molecular weight of the polyether diol is 1000-2000.

4. The sewage resistant polyurethane according to claim 1, characterized in that: The diisocyanate is at least one of an aliphatic diisocyanate and an aromatic diisocyanate.

5. The sewage resistant polyurethane according to claim 1, characterized in that: The catalyst is at least one of dibutyltin dilaurate and dibutyltin diacetate.

6. The sewage resistant polyurethane according to claim 1, characterized in that: The neutralizing agent is at least one of triethylamine, triethanolamine and diethanolamine.

7. The method for preparing a sewage resistant polyurethane according to any one of claims 1 to 6, characterized in that: The following steps are involved: After dehydrating the organosilicon polyol and polyether diol, add diisocyanate and catalyst and Under gas protection, heat to 85-92℃ and react for 2-2.5h, then add 30-40% of the total weight of carboxylic acid chain extender and acetone, continue to react for 1-1.5h, cool to 40-45℃, add the remaining acetone to reduce viscosity, then add neutralizer, stir evenly, add water, disperse at high speed, immediately add amine chain extender, continue to react for 1-1.5h, finally vacuum to remove acetone to obtain sewage resistant polyurethane.

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