Sewage-resistant polyurethane and its preparation method and application

Abstract

The present invention belongs to the field of waterborne polyurethane materials, and specifically discloses a kind of sewage-resistant polyurethane and its preparation method and application. The preparation raw materials of sewage-resistant polyurethane of the present invention include the following components in parts by weight: 60-80 parts of carbon dioxide copolymer polyol, 20-40 parts of soybean oil polyol, 30-70 parts of aliphatic diisocyanate, 1-10 parts of cross-linking agent, 4-20 parts of hydrophilic chain extender, 30-60 parts of hydroxyl-containing silicone oil, 1-15 parts of neutralizer, 1-15 parts of hydroxyl-containing acrylate, 100-400 parts of water, 1-10 parts of chain extender, 10-40 parts of acrylate monomer, 0.01-0.5 parts of initiator. The present invention is combined by block copolymerization with hydroxyl-containing silicone oil, acrylate and anhydrous polyol mixture prepared by modification, so that the internal phase separation of polyurethane structure is more obvious, showing more excellent stain resistance and aging resistance.

Description

Technical Field

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

[0002] Common sports flooring materials are made from polyurethane. Ideal polyurethane materials should have good aging resistance, stain resistance, water resistance, wear resistance and other properties, but poor weather resistance. However, in reality, polyurethane often cannot have multiple excellent weather resistance properties. The water-based polyurethane topcoat commonly used in existing sports flooring materials has poor stain resistance, and the venue appears black and dirty. Existing technical means have not yet found a good technical solution to perfectly solve this problem. In particular, sports flooring materials made of polyurethane will obviously turn black after aging in natural light outdoors, and their dirt or stain resistance is extremely poor. Therefore, there is still a need to develop a more stain-resistant water-based polyurethane coating. Summary of the Invention

[0003] In response to the above-mentioned problems in the prior art related to the poor stain resistance of water-based polyurethane topcoat for sports floors, the present invention provides a sewage-resistant polyurethane and its preparation method and application.

[0004] To achieve the above objectives, the following technical solutions are specifically included:

[0005] Disclosed is sewage-resistant polyurethane. The raw materials for preparing the polyurethane include the following components in parts by weight: 60-80 parts of carbon dioxide copolymer polyol, 20-40 parts of soybean oil polyol, 30-70 parts of aliphatic diisocyanate, 1-10 parts of a crosslinking agent, 4-20 parts of a hydrophilic chain extender, 30-60 parts of hydroxyl-containing silicone oil, 1-15 parts of a neutralizer, 1-15 parts of a hydroxyl-containing acrylate, 100-400 parts of water, 1-10 parts of a chain extender, 10-40 parts of an acrylate monomer, and 0.01-0.5 parts of an initiator. The raw materials for preparing the hydroxyl-containing silicone oil include the following components: 80-120 parts of allyl polyoxyethylene ether and 5-30 parts of polydimethylmethylhydrogensiloxane.

[0006] The invention combines modified hydroxyl-containing organic silicone oil, acrylate and anhydrous polyol mixture by block copolymerization, so that the internal phase separation of the polyurethane structure is more obvious, and exhibits more excellent stain resistance and aging resistance.

[0007] As a preferred embodiment of the present invention, the raw materials for preparing the sewage-resistant polyurethane include the following components in parts by weight: 60-80 parts of carbon dioxide copolymer polyol, 20-40 parts of soybean oil polyol, 45-65 parts of aliphatic diisocyanate, 1-5 parts of a crosslinking agent, 4-15 parts of a hydrophilic chain extender, 30-55 parts of hydroxyl-containing silicone oil, 3-11 parts of a neutralizer, 3-15 parts of a hydroxyl-containing acrylate, 150-300 parts of water, 1-2 parts of a chain extender, 20-35 parts of an acrylate monomer, and 0.2-0.3 parts of an initiator; the raw materials for preparing the hydroxyl-containing silicone oil include the following components: 100 parts of allyl polyoxyethylene ether and 10-20 parts of polydimethylmethylhydrogensiloxane.

[0008] As a preferred embodiment of the present invention, the carbon dioxide copolymer polyol is copolymerized by small molecule polyether, propylene oxide and carbon dioxide, and the molecular weight of the carbon dioxide copolymer polyol is 1000 g / mol to 3000 g / mol.

[0009] As a preferred embodiment of the present invention, the number average molecular weight of the soybean oil polyol is 1000 g / mol to 4000 g / mol.

[0010] As a preferred embodiment of the present invention, the aliphatic diisocyanate is at least one of isophorone diisocyanate, hexamethylene diisocyanate, and hydrogenated diphenylmethane diisocyanate (hydrogenated MDI).

[0011] As a preferred embodiment of the present invention, the cross-linking agent is at least one of trimethylolpropane, glucose, and glycerol.

[0012] As a preferred embodiment of the present invention, the hydrophilic chain extender is at least one of dimethylol propionic acid, dimethylol butyric acid, and sodium sulfamate aqueous solution.

[0013] As a preferred embodiment of the present invention, the sodium sulfamate aqueous solution is a sodium sulfamate aqueous solution with a mass percentage of 50%.

[0014] As a preferred embodiment of the present invention, the hydroxyl-containing acrylate is at least one of hydroxyethyl acrylate, hydroxymethyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxymethyl acrylate, and hydroxypropyl acrylate.

[0015] As a preferred embodiment of the present invention, the neutralizing agent is triethylamine.

[0016] As a preferred embodiment of the present invention, the chain extender is at least one of ethylenediamine, diethylenetriamine, and isophoronediamine.

[0017] As a preferred embodiment of the present invention, the acrylic acid ester monomer is at least one of methyl acrylate, ethyl acrylate, 2-methyl methacrylate, 2-ethyl methacrylate, methyl methacrylate, and butyl acrylate.

[0018] As a preferred embodiment of the present invention, the molecular weight of the allyl polyoxyethylene ether is 600-2400.

[0019] As a preferred embodiment of the present invention, the initiator is ammonium persulfate.

[0020] A method for preparing sewage-resistant polyurethane comprises the following steps:

[0021] (1) mixing allyl polyoxyethylene ether and polydimethylmethylhydrogensiloxane, heating and reacting in the presence of a catalyst, and separating the reaction product to obtain the hydroxyl-containing organic silicone oil;

[0022] (2) mixing the carbon dioxide copolymer polyol and the soybean oil polyol, heating and performing a dehydration reaction to obtain an anhydrous polyol mixture;

[0023] (3) adding an aliphatic diisocyanate to the anhydrous polyol mixture to react;

[0024] (4) adding a crosslinking agent, a hydrophilic chain extender and a hydroxyl-containing acrylate to react;

[0025] (5) adding hydroxyl-containing silicone oil to react, and adding solvent, neutralizing agent and water to disperse;

[0026] (6) adding a chain extender and reacting under stirring, removing the solvent to obtain a silicone-modified waterborne polyurethane;

[0027] (7) Adding an acrylate monomer and an initiator to the organosilicon-modified waterborne polyurethane to carry out a copolymerization reaction to obtain the sewage-resistant polyurethane.

[0028] As a preferred embodiment of the present invention, in step (1), the hydrogen content of the polydimethylmethylhydrogensiloxane is 0.8%-2%.

[0029] As a preferred embodiment of the present invention, in step (1), the catalyst is chloroplatinic acid.

[0030] As a preferred embodiment of the present invention, in step (1), the mass fraction of chloroplatinic acid is 0.01 to 1 parts.

[0031] As a preferred embodiment of the present invention, in step (1), the reaction temperature is 70-100° C., and the reaction time is 6-10 h.

[0032] As a further preferred embodiment of the present invention, in step (1), the reaction temperature is 90° C. and the reaction time is 8 h.

[0033] As a preferred embodiment of the present invention, in step (1), the method for separating the reaction product is vacuum distillation, and the specific steps of vacuum distillation are: heating the reaction system to 100-160°C and vacuum distilling under negative pressure for 20 to 120 minutes.

[0034] As a further preferred embodiment of the present invention, in step (1), the method for separating the reaction product is vacuum distillation, and the specific steps of vacuum distillation are: heating the reaction system to 120°C and performing vacuum distillation for 30 minutes under a negative pressure of 0.095 MPa.

[0035] As a preferred embodiment of the present invention, in step (2), the specific steps of the dehydration reaction include: performing the dehydration reaction under negative pressure and a temperature of 70-120° C. for 0.5-3 h.

[0036] As a further preferred embodiment of the present invention, in step (2), the specific steps of the dehydration reaction include: performing the dehydration reaction under the conditions of a negative pressure of 0.095 MPa and a temperature of 100° C. for 2 hours.

[0037] As a preferred embodiment of the present invention, in step (3), the reaction temperature is 75-90° C., and the reaction time is 1-4 h.

[0038] As a further preferred embodiment of the present invention, in step (3), the reaction temperature is 85° C. and the reaction time is 3 h.

[0039] As a preferred embodiment of the present invention, in step (3), the reaction is carried out under the condition of catalysis by a catalyst, and the catalyst is organic bismuth.

[0040] As a preferred embodiment of the present invention, in step (4), the reaction temperature is 60-75° C., and the reaction time is 1-3 h.

[0041] As a further preferred embodiment of the present invention, in step (4), the reaction temperature is 70° C., and the reaction time is 2 h.

[0042] As a preferred embodiment of the present invention, in step (5), the reaction temperature is 60-80° C., and the reaction time is 1-5 h.

[0043] As a further preferred embodiment of the present invention, in step (5), the reaction temperature is 70° C. and the reaction time is 3 h.

[0044] As a preferred embodiment of the present invention, in step (5), the dispersion temperature is 10-60° C., the dispersion time is 1-30 min, and the dispersion speed is 1000-2000 rpm.

[0045] As a further preferred embodiment of the present invention, in step (5), the dispersion temperature is 50° C., the dispersion time is 15 min, and the dispersion speed is 1500 rpm.

[0046] As a preferred embodiment of the present invention, in step (5), the solvent is acetone or butanone.

[0047] As a preferred embodiment of the present invention, in step (6), the reaction temperature is 10-60° C., and the reaction time is 1-30 min.

[0048] As a preferred embodiment of the present invention, in step (7), the temperature of the copolymerization reaction is 70-100° C., and the time of the copolymerization reaction is 1-5 h.

[0049] As a further preferred embodiment of the present invention, in step (7), the temperature of the copolymerization reaction is 75° C., and the time of the copolymerization reaction is 5 h.

[0050] The present invention also provides an application of the sewage-resistant polyurethane in preparing waterborne polyurethane coatings.

[0051] A water-based polyurethane coating, the preparation raw materials of which include the following components in parts by weight: 80-120 parts of sewage-resistant polyurethane, 10-50 parts of filler, and 0.1-5 parts of water-based additive.

[0052] As a further preferred embodiment of the present invention, the filler is at least one of talc powder with a mesh size of 400 to 1250 mesh, heavy calcium carbonate, kaolin, and titanium dioxide.

[0053] As a preferred embodiment of the present invention, the aqueous auxiliary agent is at least one of a defoaming agent, a wetting agent, a preservative, a thickener, and a pH regulator.

[0054] The raw materials for preparing the waterborne polyurethane coating include the following components in parts by weight: 100 parts of the sewage-resistant polyurethane, 15 parts of filler, 0.3 parts of dispersant, 0.4 parts of wetting agent, 0.2 parts of defoamer, 0.1 parts of preservative, and 1 part of thickener.

[0055] Compared with the prior art, the present invention has the following beneficial effects: the present invention uses allyl polyoxyethylene ether and polydimethylmethylhydrogensiloxane to prepare a hydroxyl-containing silicone oil (such as Figure 1), and then grafted with the prepared branched terminal isocyanate polyurethane prepolymer to form a silicone modified waterborne polyurethane with a specific multi-branched structure (R(OH)n, where R represents polyurethane and n represents 3-5), and then introduced with acrylate to form a special core-shell structure (such as Figure 2 ), and the modified polyurethane structure is different from that of ordinary polyurethanes because its carbon dioxide copolymer polyol has both ether bonds and carbonate bonds with greater polarity, and soybean oil has excellent hydrophobicity. Through block copolymerization, they are combined together to make the internal phase separation of the polyurethane structure more obvious, showing better stain resistance and aging resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 This is a schematic diagram of the reaction for preparing hydroxyl-containing silicone oil in an example.

[0057] Figure 2 Schematic diagram of the preparation of a special core-shell structure product in this example. DETAILED DESCRIPTION

[0058] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below through specific embodiments.

[0059] The sources of some of the raw materials used in the following examples and comparative examples are as follows:

[0060] Dispersant: Dow dispersant 1124; Wetting agent: Dow wetting agent BD109; Defoaming agent: Nopco NXZ defoaming agent; Preservative: Dow preservative 631; Thickener: Rohm and Haas thickener 8w mix.

[0061] The carbon dioxide copolymer polyol, polybutadiene polyol and polyether polyol all use difunctional polyol copolymers, namely carbon dioxide copolymer diol, polybutadiene diol and polyether diol, which are commercially available. The molar fraction of the polycarbonate group in the carbon dioxide copolymer diol is 0.3.

[0062] Unless otherwise specified, the same components used in the examples and comparative examples are of the same type.

[0063] Example 1

[0064] The sewage-resistant polyurethane of this embodiment includes the following raw material components in parts by weight: 80 parts of carbon dioxide copolymer polyol, 20 parts of soybean oil polyol, 45 parts of aliphatic diisocyanate, 5 parts of cross-linking agent, 15 parts of hydrophilic chain extender, 3 parts of hydroxyl-containing acrylate, 55 parts of hydroxyl-containing silicone oil, 11 parts of neutralizer, 300 parts of water, 1 part of chain extender, 35 parts of acrylate monomer, and 0.2 part of initiator; the raw materials for preparing the hydroxyl-containing silicone oil include the following components: 100 parts of allyl polyoxyethylene ether (Mn=600) and 20 parts of polydimethylmethylhydrogensiloxane.

[0065] A method for preparing sewage-resistant polyurethane comprises the following steps:

[0066] (1) adding 100 parts by mass of allyl polyoxyethylene ether and 20 parts of polydimethylmethylhydrogensiloxane (hydrogen content 1.56-1.62%) to a reactor under stirring, and then adding 0.25 parts of chloroplatinic acid, heating to 90° C. and reacting for 8 hours. After the reaction is completed, heating to 120° C. and performing reduced pressure distillation for 30 minutes under a negative pressure of 0.095 MPa to separate the reaction product, thereby obtaining the hydroxyl-containing organic silicone oil;

[0067] (2) Add 80 parts by mass of carbon dioxide copolymer polyol (Mn = 3000 g / mol) and 20 parts of soybean oil polyol (Mn = 1000 g / mol) to a reactor, heat to 100° C., and dehydrate at a negative pressure of 0.095 MPa for 2 h to obtain an anhydrous polyol mixture;

[0068] (3) adding 45 parts of isophorone diisocyanate and 0.08 parts of organic bismuth to the anhydrous polyol mixture, and reacting at 85° C. for 3 hours;

[0069] (4) Lower the system temperature to 70°C, add 5 parts of trimethylolpropane, 15 parts of dimethylolpropionic acid, and 3 parts of hydroxyethyl acrylate, and react for 2 hours;

[0070] (5) Controlling the temperature of the system at 70° C., adding 55 parts of the hydroxyl-containing silicone oil prepared in (1) above, reacting for 3 h, cooling the system temperature to 50° C., adding 50 parts of acetone and 11 parts of triethylamine, adding 300 parts of deionized water under high-speed stirring, dispersing for 15 min, adding 1 part of ethylenediamine, and removing the solvent to obtain silicone-modified waterborne polyurethane;

[0071] (6) adding 1 part of ethylenediamine, reacting for 20 minutes under stirring, and removing the solvent to obtain a silicone-modified waterborne polyurethane;

[0072] (7) Add 20 parts of methyl methacrylate and 15 parts of butyl acrylate to the organosilicon-modified waterborne polyurethane, raise the temperature to 75° C., add 0.2 parts of ammonium persulfate and carry out copolymerization for 5 hours to obtain the sewage-resistant polyurethane.

[0073] A method for preparing a waterborne polyurethane coating comprises the following steps: mixing, by mass, 100 parts of the sewage-resistant polyurethane prepared in step (7) above, 15 parts of 1250-mesh kaolin, 0.3 parts of a dispersant, 0.4 parts of a wetting agent, 0.2 parts of a defoaming agent, 0.1 parts of a preservative and 1 parts of a thickener, and stirring the mixture to obtain a waterborne polyurethane coating.

[0074] Example 2

[0075] Compared with Example 1, the difference is that in this example, 60 parts of carbon dioxide copolymer polyol (Mn=3000 g / mol) and 40 parts of soybean oil polyol (Mn=1000 g / mol) are used.

[0076] Example 3

[0077] Compared with Example 1, the difference is that the amount of hydroxyl-containing silicone oil added in this example is 30 parts.

[0078] Example 4

[0079] Compared with Example 1, the difference is that the amount of hydroxyethyl acrylate added in this example is 15 parts.

[0080] Comparative Example 1

[0081] Compared with Example 1, the difference is that in step (2), 80 parts of carbon dioxide copolymer polyol and 20 parts of soybean oil polyol are replaced by 100 parts of polyether polyol (Mn=2000 g / mol).

[0082] Comparative Example 2

[0083] Compared with Example 1, the difference is that the soybean oil polyol is replaced by an equal amount of polybutadiene polyol (Mn=2000 g / mol).

[0084] Comparative Example 3

[0085] Compared with Example 1, the difference is that step (7) is not performed, that is, acrylic acid monomer is not added for polymerization.

[0086] Comparative Example 4

[0087] Compared with Example 1, the difference is that hydroxyethyl acrylate is not added.

[0088] Comparative Example 5

[0089] Compared with Example 1, the difference is that step (1) is not performed, and the hydroxyl-containing silicone oil is replaced by an equal amount of silane coupling agent KH550.

[0090] The waterborne polyurethane coatings prepared in the examples and comparative examples were applied to glass plates and dried at room temperature for 7 days to measure the initial contact angle. Three parallel samples were tested and the test results were averaged. The test method was based on GB / T24368-2009.

[0091] Water-based coatings can degrade in performance and affect usability due to outdoor light aging. Due to the long natural aging cycle of the material, accelerated aging was employed. This test was conducted in accordance with GB / T 16422.3-2014, "Plastics - Test Methods for Laboratory Light Source Exposure - Part 3: Fluorescent UV Lamp." Samples were prepared as described above and subjected to UV aging for 14 days. Contact angles were then measured. Three replicate samples were tested, and the results were averaged.

[0092] Table 1 Contact angles of the coatings of the waterborne polyurethane coatings of Examples and Comparative Examples

[0093] sample Initial contact angle / ° Contact angle after exposure / ° Pencil hardness Example 1 116 105 3H Example 2 109 101 3H Example 3 100 92 3H Example 4 118 107 3H Comparative Example 1 85 61 2B Comparative Example 2 81 55 H Comparative Example 3 72 44 B Comparative Example 4 75 51 H Comparative Example 5 55 32 HB

[0094] A contact angle greater than 90° indicates hydrophobicity. The larger the contact angle, the better the hydrophobicity and the better the stain resistance. The initial contact angle and the contact angle after exposure in the examples show that the waterborne polyurethane coating of the present invention exhibits excellent hydrophobicity and stain resistance. Even after UV aging, the coating maintains excellent hydrophobicity and exhibits excellent aging and stain resistance.

[0095] Compared to Example 1, Example 2 increased the amount of CO2 copolymer polyol and reduced the amount of soybean oil. The lack of significant hardness change is due to the increased polarity and hardness of the carbonate bonds, but the reduced multifunctional soybean oil resulted in fewer crosslinks, which counteracted each other. Regarding the contact angle, soybean oil is more hydrophobic, so the reduced soybean oil amount in Example 2 resulted in a decreased contact angle.

[0096] Compared with Example 1, the amount of silicone was reduced in Example 3, and the contact angle of the waterborne polyurethane coating was significantly reduced; in terms of hardness, the hardness of the two remained unchanged, because the degree of reduction in the amount of silicone was not enough to allow the silicone wrapped around the outside to affect the hardness of the main body of the polyurethane acrylic component.

[0097] Compared with Example 1, the amount of hydroxyethyl acrylate in Example 4 was increased, and the contact angle of the waterborne polyurethane coating was slightly improved because hydroxyethyl propionate could better form a core-shell structure with acrylic monomers and polyurethane segments.

[0098] Compared to Example 1, Comparative Example 1 uses a polyether instead of the CO2 copolymer polyol and soybean oil polyol in the present invention. The polyether contains a large number of pendant methyl groups, resulting in poor chemical stability and susceptibility to aging. Furthermore, the ether bonds alone are inferior to those of CO2 copolymer polyols possessing both ether and carbonate bonds, nor are they as good as the multifunctional cross-linked structure of soybean oil polyol. Therefore, the coating of the present invention using both CO2 copolymer polyol and soybean oil polyol exhibits better stain and aging resistance.

[0099] Compared with Example 1, Comparative Example 2 uses polybutadiene polyol. Since it does not have the multifunctional structure of soybean oil polyol in Example 1, it has poor crosslinking degree, insufficient film density, low contact angle, and low hardness.

[0100] Compared with Example 1, in Comparative Example 3, no acrylic acid was added, and the core-shell structure could not be formed in the product, so that the organosilicon group was surrounded by the outer layer, resulting in a lower contact angle and poorer hardness.

[0101] Compared with Example 1, hydroxyethyl acrylate was not added in Comparative Example 4. Although a certain core-shell structure could be formed, the connection between the acrylic acid segment and the polyurethane segment resulted in a weaker effect in forming the core-shell structure.

[0102] Compared with Example 1, Comparative Example 5 uses a silane coupling agent, which has a low molecular weight and is difficult to effectively increase the contact angle.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A sewage-resistant polyurethane, characterized in that The raw materials for its preparation include the following components in parts by weight: 60-80 parts of carbon dioxide copolymer polyol, 20-40 parts of soybean oil polyol, 30-70 parts of aliphatic diisocyanate, 1-10 parts of crosslinking agent, 4-20 parts of hydrophilic chain extender, 30-60 parts of hydroxyl-containing silicone oil, 1-15 parts of neutralizer, 1-15 parts of hydroxyl-containing acrylate, 100-400 parts of water, 1-10 parts of chain extender, 10-40 parts of acrylate monomer, and 0.01-0.5 parts of initiator; The hydrophilic chain extender is at least one of dimethylol propionic acid and dimethylol butyric acid; the chain extender is at least one of ethylenediamine, diethylenetriamine, and isophorone diamine; the hydroxyl-containing acrylate is at least one of hydroxyethyl acrylate, hydroxymethyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxymethyl acrylate, and hydroxypropyl acrylate; the acrylate monomer is at least one of methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl 2-methacrylate, and butyl acrylate; The raw materials for preparing the hydroxyl-containing organic silicone oil include the following components: 80-120 parts of allyl polyoxyethylene ether and 5-30 parts of polydimethylmethylhydrogensiloxane.

2. The sewage-resistant polyurethane according to claim 1, wherein The raw materials for preparing the sewage-resistant polyurethane include the following components in parts by weight: 60-80 parts of carbon dioxide copolymer polyol, 20-40 parts of soybean oil polyol, 45-65 parts of aliphatic diisocyanate, 1-5 parts of a crosslinking agent, 4-15 parts of a hydrophilic chain extender, 30-55 parts of hydroxyl-containing silicone oil, 3-11 parts of a neutralizer, 3-15 parts of a hydroxyl-containing acrylate, 150-300 parts of water, 1-2 parts of a chain extender, 20-35 parts of an acrylate monomer, and 0.2-0.3 parts of an initiator; The raw materials for preparing the hydroxyl-containing silicone oil include the following components: 100 parts of allyl polyoxyethylene ether and 10-20 parts of polydimethylmethylhydrogensiloxane.

3. The sewage-resistant polyurethane according to claim 1, wherein Include at least one of the following (a)-(d): (a) The carbon dioxide copolymer polyol is copolymerized by small molecule polyether, propylene oxide and carbon dioxide, and the molecular weight of the carbon dioxide copolymer polyol is 1000g / mol to 3000g / mol; (b) the soybean oil polyol has a number average molecular weight of 1000 g / mol to 4000 g / mol; (c) the aliphatic diisocyanate is at least one of isophorone diisocyanate, hexamethylene diisocyanate, and hydrogenated diphenylmethane diisocyanate; (d) The cross-linking agent is at least one of trimethylolpropane, glucose, and glycerol.

4. The sewage-resistant polyurethane according to claim 1, wherein The initiator is ammonium persulfate; the neutralizer is triethylamine.

5. The method for preparing the sewage-resistant polyurethane according to any one of claims 1 to 4, characterized in that: The steps include: (1) mixing allyl polyoxyethylene ether and polydimethylmethylhydrogensiloxane, heating and reacting in the presence of a catalyst, and separating the reaction product to obtain the hydroxyl-containing organic silicone oil; (2) mixing the carbon dioxide copolymer polyol and the soybean oil polyol, heating and performing a dehydration reaction to obtain an anhydrous polyol mixture; (3) adding an aliphatic diisocyanate to the anhydrous polyol mixture to react; (4) adding a crosslinking agent, a hydrophilic chain extender and a hydroxyl-containing acrylate to react; (5) adding hydroxyl-containing silicone oil to react, and adding solvent, neutralizing agent and water to disperse; (6) adding a chain extender and reacting under stirring, removing the solvent to obtain a silicone-modified waterborne polyurethane; (7) Adding an acrylate monomer and an initiator to the organosilicon-modified waterborne polyurethane to carry out a copolymerization reaction to obtain the sewage-resistant polyurethane.

6. The method for preparing the sewage-resistant polyurethane according to claim 5, wherein: In step (1), the hydrogen content of the polydimethylmethylhydrogensiloxane is 0.8%-2%; in step (1), the catalyst is chloroplatinic acid.

7. The method for preparing the sewage-resistant polyurethane according to claim 5, wherein: Include at least one of the following AJ: A. In step (1), the reaction temperature is 70-100°C and the reaction time is 6-10h; B. In step (1), the method for separating the reaction product is vacuum distillation, and the specific steps of vacuum distillation are: heating the reaction system to 100-160° C. and vacuum distilling under negative pressure for 20-120 min; C. In step (2), the specific steps of the dehydration reaction include: carrying out the dehydration reaction under negative pressure and a temperature of 70-120° C. for 0.5-3 h; D. In step (3), the reaction temperature is 75-90° C. and the reaction time is 1-4 h; E. In step (4), the reaction temperature is 60-75°C and the reaction time is 1-3h; F. In step (5), the reaction temperature is 60-80°C and the reaction time is 1-5h; G. In step (5), the dispersion temperature is 10-60°C, the dispersion time is 1-30 min, and the dispersion speed is 1000-2000 rpm; H. In step (5), the solvent is acetone or butanone; I. In step (6), the reaction temperature is 10-60°C and the reaction time is 1-30 min; J. In step (7), the temperature of the copolymerization reaction is 70-100° C., and the time of the copolymerization reaction is 1-5 h.

8. A waterborne polyurethane coating, characterized in that: The raw materials for its preparation comprise the following components in parts by weight: 80-120 parts of the sewage-resistant polyurethane according to any one of claims 1 to 4, 10-50 parts of fillers, and 0.1-5 parts of a water-based auxiliary agent.

9. The waterborne polyurethane coating according to claim 8, wherein The filler is at least one of 400-1250 mesh talc, heavy calcium carbonate, kaolin, and titanium dioxide; and the aqueous additive is at least one of a defoamer, a wetting agent, a preservative, a thickener, and a pH regulator.

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