Aqueous polyurethane and its preparation method and aqueous polyurethane permeable layer

Abstract

The present invention provides a waterborne polyurethane, a preparation method thereof, and a waterborne polyurethane permeable coating. The preparation method comprises reacting a diisocyanate with a bisaminosilane coupling agent, followed by reacting with a polyol, and then reacting the resulting product with a monoaminosilane coupling agent to produce a waterborne polyurethane prepolymer. Compared to conventional permeable coatings of high-permeability emulsified asphalt, coal tar, and diluted asphalt, the present invention introduces a novel polyurethane permeable coating. Furthermore, by embedding a silane coupling agent within the polyurethane molecular chain, the present invention enhances the adhesion of the waterborne polyurethane to a semi-rigid base layer and its waterproofing capability, providing technical support for cold-mix, cold-laid, single-component polyurethane mixture pavements.

Description

Technical Field

[0001] The present invention relates to the technical field of materials, in particular to a waterborne polyurethane and a preparation method thereof, and a waterborne polyurethane permeable layer. Background Art

[0002] With growing environmental awareness, the high energy consumption and high emissions associated with hot-mix asphalt production in the highway construction industry are becoming increasingly prominent. Cold-mix, cold-paving technology offers low energy consumption, minimal pollution, and minimal environmental impact, meeting the demands of environmental protection. However, traditional cold-mix, cold-paving technology for asphalt pavements is limited, limiting its applicability. Polyurethane-based pavements utilize room-temperature mixing and construction, significantly improving road performance compared to traditional cold-mix, cold-paved asphalt pavements. Polyurethane-based pavements are becoming a key development direction in pavement development. Polyurethane-based pavements utilize a polyurethane polymer as a substitute for an asphalt binder, enabling room-temperature mixing of the mixture, achieving energy conservation and emission reduction goals, and significantly improving the mixture's road performance. Polyurethane binders can be divided into two-component and one-component. Because two-component polyurethanes require precise on-site mixing and uniform mixing, which presents challenges during on-site construction, one-component polyurethanes are often used in road construction. The strength of one-component polyurethanes is primarily achieved through the reaction of the isocyanate (-NCO) reactive groups in the polyurethane with moisture in the air to form urea groups, which cure the one-component polyurethane to form an elastomer with superior mechanical properties. Single-component polyurethane mixture pavement is mixed and paved at room temperature during construction, with low energy consumption and small pollution emissions, which conforms to the new concept of "green transportation". In addition, the road performance of the mixture is significantly improved compared to asphalt mixture. Therefore, single-component polyurethane mixture pavement is receiving more and more attention.

[0003] When paving an asphalt surface, a permeable layer is required between the semi-rigid base and the underlying asphalt mixture. This layer stabilizes loose particles on the surface of the semi-rigid base, improving its surface integrity and waterproofing. Furthermore, it penetrates 5-10 mm into the semi-rigid base, enhancing the bond between the semi-rigid base and the asphalt mixture. Common permeable layers include high-permeability emulsified asphalt, coal tar, and diluted asphalt. However, due to the high pollution levels of coal tar and diluted asphalt, they are rarely used in current projects, with high-permeability emulsified asphalt primarily used. When applied to the semi-rigid base, high-permeability emulsified asphalt forms an asphalt permeable layer. This layer helps improve interlayer tension and shear between the semi-rigid base and the underlying asphalt mixture, ensuring sufficient adhesion and enhancing the pavement's integrity.

[0004] In the construction of one-component polyurethane mixture pavement, if the penetration layer uses highly permeable emulsified asphalt, after the penetration layer is formed, an asphalt layer is formed on the semi-rigid base layer. When the one-component polyurethane tack coat or the one-component polyurethane mixture is spread on the asphalt layer, some of the one-component polyurethane will enter the asphalt, plasticizing the formed asphalt and making it soft and sticky. After the polyurethane mixture is paved, the one-component polyurethane that has entered the penetration layer is difficult to contact with moisture in the air, forming a "weak layer" between the semi-rigid base layer and the polyurethane mixture. This can lead to problems such as slippage, cracks, and potholes during later road use. Therefore, it is necessary to develop a penetration layer suitable for one-component polyurethane pavements. Summary of the Invention

[0005] The present invention provides a water-based polyurethane and a preparation method thereof, and a water-based polyurethane permeable layer, which are used to solve the defect of a "weak layer" that is prone to occur in the asphalt permeable layer used in the prior art, and to achieve a water-based polyurethane permeable layer with good performance, thereby providing a guarantee for paving a single-component polyurethane mixture road surface.

[0006] The invention provides a method for preparing waterborne polyurethane, comprising: reacting diisocyanate with a bisaminosilane coupling agent, reacting the reactant with a polyol, and reacting the obtained product with a monoaminosilane coupling agent to obtain a waterborne polyurethane prepolymer.

[0007] The present invention embeds a silane coupling agent into the polyurethane molecular chain. The molecular structure of the silane coupling agent generally contains a hydrophobic organic active group and a hydrolyzable group. The hydrolyzable group reacts with water in the gaps of the semi-rigid base layer, reducing the influence of moisture on the polyurethane-aggregate interface and increasing the contact area between the asphalt and the aggregate. In addition, the silane coupling agent undergoes a condensation reaction on the aggregate surface to generate a polysiloxane coupling layer, forming chemical adsorption, generating hydrogen bonds and covalent bonds, and enhancing the adhesion and durability of the polyurethane-aggregate interface.

[0008] The diisocyanate of the present invention can be selected from diisocyanates commonly used in the art, for example, toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate (HMDI), hexamethylene diisocyanate (HDI), and lysine diisocyanate (LDI).

[0009] According to the preparation method of waterborne polyurethane provided by the present invention, the bisaminosilane coupling agent is selected from one or more of Si-602 and KH-792.

[0010] According to the preparation method of waterborne polyurethane provided by the present invention, the monoaminosilane coupling agent is selected from one or more of Si-902, Si-903, and KH-540.

[0011] According to the preparation method of waterborne polyurethane provided by the present invention, the polyol is selected from one or more of polyethylene glycol, polypropylene glycol, 1,4-butanediol, 2,2-dihydroxymethylpropionic acid, and isopentyl glycol.

[0012] In a preferred embodiment of the present invention, the polyol is polypropylene glycol or polyethylene glycol, and its molecular weight is preferably 400-1000.

[0013] According to the preparation method of waterborne polyurethane provided by the present invention, the addition amount of the polyol is 35%-65% of the total mass of the diisocyanate and the polyol, preferably 60.6%.

[0014] The invention controls the particle size of the waterborne polyurethane to be below 0.1 μm by regulating the addition ratio of the polyol, thereby improving the permeability of the waterborne polyurethane emulsion particles.

[0015] It should be noted that, according to the reaction requirements, a certain amount of small molecule chain extender and catalyst may be added during the reaction with the polyol.

[0016] In some specific embodiments of the present invention, the step of preparing the waterborne polyurethane prepolymer includes: reacting diisocyanate with a bisaminosilane coupling agent, mixing the resulting reactant with a polyol after vacuum dehydration, adding a certain amount of a small molecule chain extender and a catalyst, reacting at a constant temperature for a period of time, adding butanone to reduce viscosity, and then adding a monoaminosilane coupling agent to react to obtain the waterborne polyurethane prepolymer.

[0017] Taking KH-792 as the bisaminosilane coupling agent and KH-550 as the monoaminosilane coupling agent as an example, the above reaction process is as follows:

[0018]

[0019] The preparation method of the waterborne polyurethane provided by the present invention further comprises: mixing the waterborne polyurethane prepolymer with deionized water containing a neutralizer, and emulsifying at high speed to form a waterborne polyurethane emulsion;

[0020] The slow-cracking emulsifier is mixed with deionized water containing a stabilizer to form a soap solution, and the soap solution is mixed with the aqueous polyurethane emulsion to obtain the aqueous polyurethane.

[0021] It will be understood by those skilled in the art that when butanone is used to reduce viscosity during the preparation of the waterborne polyurethane prepolymer, the butanone can be removed by rotary evaporation after high-speed emulsification.

[0022] The present invention further mixes the aqueous polyurethane emulsion with soap solution, which is beneficial to improving the stability of the aqueous polyurethane emulsion, prolonging the demulsification time, and providing a longer permeable time for the aqueous polyurethane to penetrate into the interior of the semi-rigid base layer.

[0023] According to the preparation method of waterborne polyurethane provided by the present invention, the stabilizer is selected from one or more of polyethylene glycol, polyvinyl pyrrolidone, and hydroxyethyl cellulose.

[0024] According to the preparation method of waterborne polyurethane provided by the present invention, the neutralizing agent is selected from one or more of triethylamine, ammonia water, tripropylamine, dimethylcyclohexylamine, and dimethylethylamine.

[0025] According to the preparation method of water-based polyurethane provided by the present invention, the slow-cracking emulsifier is selected from one or more of GYMK-02 (Wesson Road Materials Co., Ltd.), PA-3 (Guangdong Lixin Energy Co., Ltd.), and CSP-08 (Nanjing Qixiashan Printing and Dyeing Auxiliary Factory).

[0026] According to the preparation method of waterborne polyurethane provided by the present invention, in the soap solution, the mass percentage of the slow-cracking emulsifier is 0.3%-0.7%, and the mass percentage of the stabilizer is 0.1%-0.5%.

[0027] In a preferred embodiment of the present invention, in the soap solution, the mass percentage of the slow-cracking emulsifier is 0.5%, and the mass percentage of the stabilizer is 0.3%.

[0028] According to the method for preparing waterborne polyurethane provided by the present invention, the mass ratio of the soap solution to the waterborne polyurethane emulsion is 1:3 to 2:1, and can be any ratio within the above numerical range, such as 1:3, 1:2, 1:1 or 2:1.

[0029] In a preferred embodiment of the present invention, the mass ratio of the soap solution to the aqueous polyurethane emulsion is 1:1.

[0030] The present invention also provides a waterborne polyurethane prepared by the above preparation method.

[0031] The present invention also provides a waterborne polyurethane permeable layer, the raw materials of which include the above-mentioned waterborne polyurethane.

[0032] Due to its small particle size and low viscosity, the waterborne polyurethane of the present invention easily penetrates into the tiny gaps in the semi-rigid base layer, forming a permeable polyurethane layer on the upper surface of the semi-rigid base. This penetration of the polyurethane into the semi-rigid base stabilizes loose particles on the surface, while also providing a bonding surface for applying a single-component polyurethane adhesive layer or paving the upper layer. Because the permeable layer is polyurethane and the adhesive layer or polyurethane binder is also polyurethane, the bonding between the materials is strong, improving the bonding between the semi-rigid base layer and the single-component polyurethane mixture.

[0033] This invention provides a waterborne polyurethane, a preparation method thereof, and a waterborne polyurethane permeable coating. Compared to traditional permeable coatings made of high-permeability emulsified asphalt, coal tar, and diluted asphalt, this novel polyurethane permeable coating is introduced. Furthermore, by embedding a silane coupling agent into the polyurethane molecular chain, this invention improves the adhesion of the waterborne polyurethane to the semi-rigid base layer and its waterproofing capability, providing technical support for cold-mix, cold-laid, single-component polyurethane mixture pavements. DETAILED DESCRIPTION

[0034] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention are described clearly and completely below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0035] In the following examples, unless otherwise specified, all reagents used were obtained through regular commercial channels.

[0036] Example 1

[0037] This embodiment provides a method for preparing waterborne polyurethane, and the specific steps are as follows:

[0038] (1) Add 150g of isophorone diisocyanate (IPDI) to a three-necked flask (1#) and heat to 60°C. Then slowly add 6g of bisaminosilane coupling agent (KH-792) and 0.25g of dibutyltin dilaurate (DBTDL) to the three-necked flask. After reacting for 1h, cool to room temperature for later use.

[0039] 160 g of polypropylene glycol (PPG1000) (temperature 120 ° C, vacuum degree ≤ 0.05 MPa) was added to another three-necked flask (2#) for dehydration for 2 h, and then cooled to 65 ° C. Subsequently, 14 g of 1,4-butanediol (BDO) was added to the 2# three-necked flask, stirred and heated to 75 ° C, and then 104 g of IPDI prepolymer (IPDI + KH-792) was added. The reaction was maintained at 75 ° C for 4 h, the heating was stopped, butanone was added to reduce the viscosity, and the mixture was cooled to room temperature. Then, 15 g of monoaminosilane coupling agent (KH-550) was added dropwise and maintained for 60 min to obtain a waterborne polyurethane prepolymer.

[0040] (2) 200 g of deionized water containing triethylamine (TEA) was added to 100 g of the aqueous polyurethane prepolymer, and the mixture was emulsified and dispersed at high speed for 30 min. Then, butanone was removed by rotary evaporation to obtain an aqueous polyurethane emulsion.

[0041] (3) 1 g of slow-cracking emulsifier (GYMK-02) was added to deionized water containing polyethylene glycol (198.4 g of water, 0.6 g of polyethylene glycol), and the mixture was evenly mixed to obtain a soap solution. The soap solution was then mixed with an aqueous polyurethane emulsion in a mass ratio of 1:1 to obtain a highly permeable aqueous polyurethane.

[0042] Example 2

[0043] This embodiment provides a method for preparing waterborne polyurethane, and the specific steps are as follows:

[0044] (1) Add 150g of isophorone diisocyanate (IPDI) to a three-necked flask (1#) and heat to 60°C. Then slowly add 6g of bisaminosilane coupling agent (KH-792) and 0.25g of dibutyltin dilaurate (DBTDL) to the three-necked flask. After reacting for 1h, cool to room temperature for later use.

[0045] 160 g of polypropylene glycol (PPG1000) (temperature 120 ° C, vacuum degree ≤ 0.05 MPa) was added to another three-necked flask (2#) for dehydration for 2 h, and then cooled to 65 ° C. Subsequently, 15 g of 2,2-dihydroxymethylpropionic acid (DMPA) and 4 g of 1,4-butanediol (BDO) were added to the 2# three-necked flask, stirred and heated to 75 ° C, and then 104 g of IPDI prepolymer (IPDI + KH-792) was added. The reaction was maintained at 75 ° C for 4 h, the heating was stopped, butanone was added to reduce the viscosity, and the mixture was cooled to room temperature. Then, 15 g of monoaminosilane coupling agent (KH-550) was added dropwise and maintained for 60 min to obtain a waterborne polyurethane prepolymer.

[0046] (2) 200 g of deionized water containing triethylamine (TEA) was added to 100 g of the aqueous polyurethane prepolymer, and the mixture was emulsified and dispersed at high speed for 30 min. Then, butanone was removed by rotary evaporation to obtain an aqueous polyurethane emulsion.

[0047] (3) 1 g of slow-cracking emulsifier (GYMK-02) was added to deionized water containing polyethylene glycol (198.4 g of water, 0.6 g of polyethylene glycol), and the mixture was evenly mixed to obtain a soap solution. The soap solution was then mixed with an aqueous polyurethane emulsion in a ratio of 1:1 to obtain a highly permeable aqueous polyurethane.

[0048] Example 3

[0049] This embodiment provides a method for preparing waterborne polyurethane, and the specific steps are as follows:

[0050] (1) Add 150g of isophorone diisocyanate (IPDI) to a three-necked flask (1#) and heat to 60°C. Then slowly add 6g of bisaminosilane coupling agent (KH-792) and 0.25g of dibutyltin dilaurate (DBTDL) to the three-necked flask. After reacting for 1h, cool to room temperature for later use.

[0051] In another three-necked flask (2#), 40 g of polyethylene glycol (PEG1000) and 120 g of polypropylene glycol (PPG1000) were added to a mixed polyol (temperature 120°C, vacuum degree ≤ 0.05 MPa) for dehydration for 2 h, and then cooled to 65°C. Subsequently, 15 g of 2,2-dihydroxymethylpropionic acid (DMPA) and 4 g of 1,4-butanediol (BDO) were added to the 2# three-necked flask, stirred and heated to 75°C, and then 104 g of IPDI prepolymer (IPDI+KH-792) was added. The reaction was maintained at 75°C for 4 h, the heating was stopped, butanone was added to reduce the viscosity, and the mixture was cooled to room temperature. Then, 15 g of monoaminosilane coupling agent (KH-550) was added dropwise and maintained for 60 min to obtain a waterborne polyurethane prepolymer.

[0052] (2) 200 g of deionized water containing triethylamine (TEA) was added to 100 g of the aqueous polyurethane prepolymer, and the mixture was emulsified and dispersed at high speed for 30 min. Then, butanone was removed by rotary evaporation to obtain an aqueous polyurethane emulsion.

[0053] (3) 1 g of slow-cracking emulsifier (GYMK-02) was added to deionized water containing polyethylene glycol (198.4 g of water, 0.6 g of polyethylene glycol), and the mixture was evenly mixed to obtain a soap solution. The soap solution was then mixed with an aqueous polyurethane emulsion in a ratio of 1:1 to obtain a highly permeable aqueous polyurethane.

[0054] Example 4

[0055] This embodiment provides a method for preparing waterborne polyurethane, and the specific steps are as follows:

[0056] (1) Add 150g of isophorone diisocyanate (IPDI) to a three-necked flask (1#) and heat to 60°C. Then slowly add 6g of bisaminosilane coupling agent (KH-792) and 0.25g of dibutyltin dilaurate (DBTDL) to the three-necked flask. After reacting for 1h, cool to room temperature for later use.

[0057] In another three-necked flask (2#), 160 g of polypropylene glycol (PPG1000) polyol (temperature 120°C, vacuum degree ≤0.05 MPa) was added and dehydrated for 2 h, then cooled to 65°C. Subsequently, 14 g of 1,4-butanediol (BDO) was added to the 2# three-necked flask, stirred and heated to 75°C, and then 104 g of IPDI prepolymer (IPDI+KH-792) was added. The reaction was maintained at 75°C for 4 h, the heating was stopped, butanone was added to reduce the viscosity, and the mixture was cooled to room temperature. Then, 15 g of monoaminosilane coupling agent (KH-550) was added dropwise and maintained for 60 min to obtain a waterborne polyurethane prepolymer.

[0058] (2) 200 g of deionized water containing triethylamine (TEA) was added to 100 g of the aqueous polyurethane prepolymer, and the mixture was emulsified and dispersed at high speed for 30 min. Then, butanone was removed by rotary evaporation to obtain an aqueous polyurethane emulsion.

[0059] Comparative Example 1

[0060] This comparative example provides a method for preparing waterborne polyurethane, and the steps are as follows:

[0061] (1) 160 g of polypropylene glycol (PPG1000) was added to a three-necked flask (temperature 120 °C, vacuum degree ≤ 0.05 MPa) and dehydrated for 2 h, then cooled to 65 °C. Subsequently, 15 g of 2,2-dihydroxymethylpropionic acid (DMPA) and 5.6 g of 1,4-butanediol (BDO) were added to the three-necked flask, stirred and heated to 75 °C, and then 100 g of isophorone diisocyanate (IPDI) was added. The temperature was maintained at 75 °C for 4 h. The heating was stopped, butanone was added to reduce the viscosity, and the mixture was cooled to room temperature. Then, 15 g of monoaminosilane coupling agent (KH-550) was added dropwise and kept for 60 min to obtain a waterborne polyurethane prepolymer.

[0062] (2) 200 g of deionized water containing triethylamine (TEA) was added to 100 g of the aqueous polyurethane prepolymer, and the mixture was emulsified and dispersed at high speed for 30 min. Then, butanone was removed by rotary evaporation to obtain an aqueous polyurethane emulsion.

[0063] (3) 1 g of slow-cracking emulsifier (GYMK-02) was added to deionized water containing polyethylene glycol (198.4 g of water, 0.6 g of polyethylene glycol), and the mixture was evenly mixed to obtain a soap solution. The soap solution was then mixed with an aqueous polyurethane emulsion in a mass ratio of 1:1 to obtain a highly permeable aqueous polyurethane.

[0064] Performance Testing

[0065] In order to facilitate the testing of the penetration ability of high-permeability water-based polyurethane, a small amount of black water-based pigment was added to the water-based polyurethane. Then, the accurately weighed high-permeability water-based polyurethane was sprinkled on the semi-rigid base specimen and fully cured. Referring to the test method of JTG 3450-2019 "Field Test Procedure for Highway Roadbed and Pavement", the penetration depth of different water-based polyurethanes was tested. The results are shown in Table 1.

[0066] Table 1 Penetration depth of different waterborne polyurethanes

[0067]

[0068] As can be seen in Table 1, the penetration depths of Examples 1, 2, and 3 are superior to those of Example 4. A comparison reveals that increasing the proportion of hydrophilic segments (PEG1000 and DMPA) can improve the penetration capacity of the waterborne polyurethane. Furthermore, a comparison of Examples 1 and 4 demonstrates that soap solution improves the stability of the waterborne polyurethane emulsion, prolongs the demulsification time, and provides a longer permeability window for the waterborne polyurethane to penetrate the semi-rigid substrate.

[0069] In order to facilitate the testing of the bonding ability of the high-permeability water-based polyurethane permeable layer, accurately weighed high-permeability water-based polyurethane was sprinkled on the semi-rigid base specimen and fully cured. Referring to the test method of GB / T5210-2006 "Paint and varnish adhesion test by pull-off method", the pull-out failure strength of different water-based polyurethane permeable layers was tested. The results are shown in Table 2.

[0070] Table 2 Pull-out strength of different waterborne polyurethane layers

[0071]

[0072] Table 2 shows that, by comparing Examples 1, 2, and 3, the strength is better than that of Example 4. As the penetration depth increases, the through-layer pull-out strength of the waterborne polyurethane increases, indicating that increasing the penetration depth is beneficial for increasing the through-layer pull-out strength. Furthermore, by comparing the pull-out strength of Example 2 with that of Comparative Example 1, it can be seen that Example 2 has a higher pull-out strength than Comparative Example 1, indicating that the use of a bisaminosilane coupling agent is beneficial for improving the through-layer pull-out strength.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for preparing waterborne polyurethane, characterized in that: include: reacting a diisocyanate with a bisaminosilane coupling agent, and then reacting with a polyol; and then reacting the obtained product with a monoaminosilane coupling agent to obtain a waterborne polyurethane prepolymer; and mixing the waterborne polyurethane prepolymer with deionized water containing a neutralizing agent, and emulsifying at high speed to form a waterborne polyurethane emulsion; The slow-cracking emulsifier is mixed with deionized water containing a stabilizer to form a soap solution, and the soap solution is mixed with the aqueous polyurethane emulsion to obtain the aqueous polyurethane.

2. The method for preparing waterborne polyurethane according to claim 1, wherein The bisaminosilane coupling agent is selected from one or more of Si-602 and KH-792; And / or, the monoaminosilane coupling agent is selected from one or more of Si-902, Si-903, and KH-540.

3. The method for preparing waterborne polyurethane according to claim 1, wherein The polyol is selected from one or more of polyethylene glycol, polypropylene glycol, 1,4-butanediol, 2,2-dihydroxymethylpropionic acid, and isopentyl glycol.

4. The method for preparing waterborne polyurethane according to claim 3, wherein The added amount of the polyol is 35-65% of the total mass of the diisocyanate and the polyol.

5. The method for preparing waterborne polyurethane according to any one of claims 1 to 4, characterized in that: The stabilizer is selected from one or more of polyethylene glycol, polyvinyl pyrrolidone, and hydroxyethyl cellulose; and / or, the neutralizing agent is selected from one or more of triethylamine, ammonia water, tripropylamine, dimethylcyclohexylamine, and dimethylethylamine; And / or, the slow-cracking emulsifier is selected from one or more of GYMK-02, PA-3, and CSP-08.

6. The method for preparing waterborne polyurethane according to claim 5, wherein In the soap solution, the mass percentage of the slow-cracking emulsifier is 0.3%-0.7%, and the mass percentage of the stabilizer is 0.1%-0.5%.

7. The method for preparing waterborne polyurethane according to claim 6, wherein The mass ratio of the soap solution to the aqueous polyurethane emulsion is 1:3 to 2:

1.

8. A waterborne polyurethane, characterized in that The invention is prepared by the preparation method according to any one of claims 1 to 7.

9. A waterborne polyurethane permeable layer, characterized in that: The raw materials include the water-based polyurethane described in claim 8.

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