Thin coating type polyurethane waterproof coating as well as application and preparation method thereof

Abstract

The invention discloses a thin coating type polyurethane waterproof coating as well as application and a preparation method thereof. The thin coating type polyurethane waterproof coating is prepared from 20.0%-33.5% of polytetrahydrofuran ether, 6.5%-16.0% of isocyanate, 0.39%-0.48% of an anti-aging agent, 0.2%-0.35% of a cross-linking agent, 28%-34% of filler, 0.09%-0.11% of a catalyst, 4.0%-8.0% of a latent curing agent, 0.60%-0.90% of a hydrolysis accelerant, 7.0%-20.5% of a solvent and 5.79%-15.0% of other functional additives. Based on the weight of the polyurethane waterproof coating. The thin coating type polyurethane waterproof coating is a single-component waterproof coating, is convenient to construct and has good weather resistance, and the material loss is reduced, so that a thin coating type polyurethane waterproof layer with weather resistance on the whole can be formed.

Description

Technical Field

[0001] The invention relates to the field of engineering waterproof materials, and in particular to a thin-coat polyurethane waterproof coating and a use and a preparation method thereof. Background Art

[0002] The high-performance coatings commonly used in bridge deck waterproofing at home and abroad mainly include polyurethane waterproofing coatings, polyurea elastomers and methyl methacrylate (MMA) waterproofing coatings. MMA waterproofing coatings have a strong odor during construction, which is not conducive to environmental protection. The long-term waterproofing effect has not been widely recognized, and the cost of MMA waterproofing coatings is relatively high, which is not conducive to large-scale waterproofing engineering applications. The polyurea elastomer waterproofing layer has excellent mechanical properties and good adaptability. It has been widely used in the bridge decks of CRTS II type ballastless track in China. However, due to the high requirements of polyurea elastomers on construction conditions and equipment, the construction quality is difficult to control, and it is prone to yellowing, cracking, breakage, peeling and other defects. The thin-coated polyurethane waterproof layer is significantly superior to the polyurea waterproof layer in terms of bonding strength between concrete, simplicity of construction process, and construction adaptability.

[0003] Existing thin-coat polyurethane waterproof layers are usually composed of a primer, a topcoat, and a surface coating, all of which are formed by two-component coatings; usually only the surface coating is weather-resistant. Therefore, further research is still needed on waterproof coatings that form thin-coat polyurethane waterproof layers. Summary of the invention

[0004] In view of this, the present invention proposes a thin-coat polyurethane waterproof coating and its use and preparation method. The thin-coat polyurethane waterproof coating is a single-component waterproof coating, which is easy to construct and reduces material loss. It also has good weather resistance, thereby forming an overall thin-coat polyurethane waterproof layer with weather resistance.

[0005] The present invention provides the following technical solutions:

[0006] A thin-coat polyurethane waterproof coating comprises 20.0-33.5% of polytetramethylene ether, 6.5-16.0% of isocyanate, 0.39-0.48% of anti-aging agent, 0.2-0.35% of cross-linking agent, 28-34% of filler, 0.09-0.11% of catalyst, 4.0-8.0% of latent curing agent, 0.60-0.90% of hydrolysis accelerator, 7.0-20.5% of solvent, and 5.79-15.0% of other functional additives; based on the weight of the polyurethane waterproof coating.

[0007] The present invention provides the following non-conventional alternatives:

[0008] The number average molecular weight of the polytetramethylene oxide is 1000-2000 g / mol, measured according to DIN 55672-12016 gel permeation chromatography; the hydroxyl number is 50-120 mgKOH / g, measured according to the phthalic anhydride method of method A in GB / T12008.3-2009.

[0009] The isocyanate is an aliphatic isocyanate or an alicyclic isocyanate.

[0010] The anti-aging agent includes one or more of an ultraviolet light absorber, a light stabilizer, and an antioxidant.

[0011] In the polyurethane waterproof coating, the molar ratio of the hydroxyl value of polytetramethylene ether to the isocyanate group of isocyanate is (0.4-0.5):1.

[0012] The other functional additives include 5.4-13% plasticizer, 0.3-0.5% defoamer, 0.05-0.70% leveling agent, and 0.04-0.06% dispersant, based on the weight of the polyurethane waterproof coating.

[0013] The filler includes one or more of talc, titanium dioxide, calcium carbonate, clay, kaolin, etc.; the solvent includes at least one of C6-C8 aromatic hydrocarbons and C4-C8 alkanes.

[0014] The present invention also provides use of the polyurethane waterproof coating as described above for preparing a waterproof coating on the surface of an object.

[0015] Optionally, the waterproof coating has a thickness of 600-800 μm.

[0016] The present invention also provides a method for preparing the polyurethane waterproof coating as described above, which comprises mixing polytetramethylene ether, an aging agent, a crosslinking agent, a filler, and other functional additives to obtain a first mixture; and sequentially adding isocyanate, a catalyst, a latent curing agent, a hydrolysis accelerator, and a solvent to the first mixture to react to obtain the polyurethane waterproof coating.

[0017] According to the technical solution of the present invention, the thin-coat polyurethane waterproof coating contains specific contents of polytetramethylene furan ether, isocyanate, anti-aging agent, latent curing agent, cross-linking agent and hydrolysis accelerator. It is a one-component waterproof coating, which is easy to construct and reduces material loss. It also has good weather resistance, thereby forming an overall weather-resistant thin-coat polyurethane waterproof layer. DETAILED DESCRIPTION

[0018] For ease of understanding of the present invention, the present invention will be described more fully below with reference to Examples. Preferred embodiments of the present invention are provided in the Examples. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0019] The existing thin-coat polyurethane waterproof layer is usually composed of a primer, a topcoat, and a surface coating, and these three coatings are all formed by two-component coatings; in order to form a thin-coat polyurethane waterproof layer, six components need to be used for on-site metering and batching, which is prone to mismatching and abnormal mixing, and it is difficult to control the quality of the final slurry; and for small-scale repair projects, the complexity is high and the material loss is large. The existing thin-coat polyurethane waterproof layer usually only has weather resistance on the surface coating, so after the surface coating is damaged, the weather resistance of the entire waterproof layer decreases rapidly, which is not conducive to the long-term use of the waterproof layer. In an embodiment of the present invention, by using a specific ratio of polytetrahydrofuran ether polyol, isocyanate, anti-aging agent, latent curing agent, cross-linking agent and hydrolysis accelerator, the thin-coat polyurethane waterproof coating is configured as a single-component coating, which significantly improves the convenience of construction, reduces material loss, and makes the quality of the formed waterproof layer easier to control. At the same time, the resulting waterproof layer has good weather resistance as a whole, which significantly improves the service life of the waterproof layer.

[0020] In an embodiment of the present invention, the thin-coat polyurethane waterproof coating includes 20.0-33.5% polytetramethylene ether, 6.5-16.0% isocyanate, 0.39-0.48% anti-aging agent, 0.2-0.35% cross-linking agent, 28-34% filler, 0.09-0.11% catalyst, 4.0-8.0% latent curing agent, 0.60-0.90% hydrolysis accelerator, 7.0-20.5% solvent, and 5.79-15.0% other functional additives; based on the weight of the polyurethane waterproof coating; in the polyurethane waterproof coating, the sum of the contents of each component is 100%, based on the weight of the polyurethane waterproof coating.

[0021] Polytetrahydrofuran ether is a polyether polyol, usually a polyether diol. The number average molecular weight of polytetrahydrofuran ether is 1000-2000 g / mol, measured according to DIN 55672-12016 gel permeation chromatography; the hydroxyl number is 50-120 mgKOH / g, measured according to the phthalic anhydride method of method A in GB / T 12008.3-2009. Polytetrahydrofuran ether can be a mixture of polytetrahydrofuran ethers with different number average molecular weights, for example, a mixture of polytetrahydrofuran ether with a number average molecular weight of 1000 g / mol and polytetrahydrofuran ether with a number average molecular weight of 2000 g / mol in a weight ratio of 1: (1-2.5); polytetrahydrofuran ether can be purchased from BASF Chemical Company

[0022] Isocyanate is usually an aliphatic isocyanate or an alicyclic isocyanate, such as a diisocyanate. The aliphatic diisocyanate may include one or more of hexamethylene diisocyanate (HDI), trimethylhexyl diisocyanate (TMDI), and xylyl diisocyanate (XDI). The alicyclic diisocyanate may include one or two of dicyclohexylmethane diisocyanate (HMDI), isophorone diisocyanate (IPDI), 1,4-cyclohexane diisocyanate (CHDI), and methylcyclohexane diisocyanate (HTDI); for example, hexamethylene diisocyanate (HDI), dicyclohexylmethane diisocyanate (HMDI), or a mixture thereof, such as a mixture in which the weight ratio of HDI to HMDI is 1: (5-10) such as 1: 8.3.

[0023] In the polyurethane waterproof coating, the molar ratio of the hydroxyl value of the polytetramethylene ether to the isocyanate group of the isocyanate is (0.4-0.5): 1. Moreover, the weight ratio of the polytetramethylene ether to the isocyanate can be (2-4): 1, for example (2-3.7): 1.

[0024] The anti-aging agent includes 0.13-0.16% ultraviolet light absorber, 0.13-0.16% light stabilizer, and 0.13-0.16% antioxidant, based on the weight of the polyurethane waterproof coating. The weight ratio of the ultraviolet light absorber, the light stabilizer, and the antioxidant is 1:(0.5-1.5):(0.5-1.5), for example, 1:1:1.

[0025] The ultraviolet absorber may be a conventional ultraviolet absorber known to those skilled in the art, for example, one or more of benzotriazoles, salicylates, benzophenones, substituted acrylonitriles, triazines, such as benzotriazoles. The ultraviolet absorber may be, for example, UV-326.

[0026] The light stabilizer may be a conventional light stabilizer known to those skilled in the art, for example, one or more of a hindered amine light stabilizer and an organic nickel light stabilizer, for example, a hindered amine light stabilizer. The light stabilizer may be, for example, light stabilizer 770.

[0027] The antioxidant may be a conventional antioxidant known to those skilled in the art, for example, one or more of a phenolic antioxidant and an organic phosphorus complex, for example, a phenolic antioxidant. The antioxidant may be antioxidant 1010.

[0028] The crosslinking agent may be a conventional crosslinking agent well known to those skilled in the art, and generally includes one or more of trimethylolpropane TMP, trimethylolethane, and 3,3′-dichloro-4,4′-diaminodiphenylmethane (MOCA), such as trimethylolpropane.

[0029] The filler includes one or more of talc, titanium dioxide, calcium carbonate, barium sulfate clay, kaolin, etc., such as talc, titanium dioxide or a mixture thereof; the titanium dioxide is usually rutile titanium dioxide.

[0030] The catalyst may be a conventional catalyst well known to those skilled in the art, for example, one or more of organotin catalysts and organobismuth catalysts, for example, organotin catalysts.

[0031] The latent curing agent may be a conventional latent curing agent known to those skilled in the art, such as one or more of aldimines and oxazolidines. The latent curing agent may be, for example, LCA-30 or TP800 purchased from Foshan Poly Innovation Materials Co., Ltd.

[0032] The hydrolysis accelerator may be a conventional hydrolysis accelerator well known to those skilled in the art, such as A-289 purchased from Foshan Poly Innovation Materials Co., Ltd.

[0033] The solvent is an organic solvent, such as at least one of C6-C8 aromatics and C4-C8 alkanes, or at least one of trimethylbenzene, 150# aromatic oil, 120# aromatic oil, 200# aromatic oil, PMA, and butyl acetate; for example, trimethylbenzene.

[0034] Other functional additives include 5.4-13% plasticizer, 0.3-0.5% defoamer, 0.05-0.70% leveling agent, and 0.04-0.06% dispersant, based on the weight of the polyurethane waterproof coating.

[0035] The plasticizer may be a conventional plasticizer well known to those skilled in the art, such as chlorinated paraffin, epoxidized soybean oil, phthalate plasticizer, phosphate ester, such as chlorinated paraffin.

[0036] The defoamer may be a conventional defoamer known to those skilled in the art, for example, one or more of an organosilicon defoamer containing hydrophobic particles, such as a polysiloxane compound containing hydrophobic particles, a polymer defoamer, and a mineral oil defoamer, for example, an organosilicon defoamer. The defoamer may be D6800 purchased from Hemmings Deqian.

[0037] The leveling agent is usually a conventional leveling agent well known to those skilled in the art, such as a modified or unmodified polysiloxane polymer, such as a polyether-modified polysiloxane polymer; or an acrylic resin. The leveling agent can be BNK-317 purchased from Milliken Chemical Group, USA.

[0038] The dispersant may be a conventional dispersant known to those skilled in the art, such as phosphate esters. The dispersant may be Disuper S18 purchased from Guangdong Core New Materials Co., Ltd.

[0039] Optionally, the thin-coat polyurethane waterproof coating includes 20.0-33.5% polytetramethylene ether, 6.5-16.0% isocyanate, 5.4-13% plasticizer, 0.3-0.5% defoamer, 0.13-0.16% ultraviolet light absorber, 0.13-0.16% light stabilizer, 0.13-0.16% antioxidant, 0.2-0.35% cross-linking agent, 28-34% filler, 0.09-0.11% catalyst, 4.0-8.0% latent curing agent, 0.60-0.90% hydrolysis accelerator, 7.0-20.5% solvent, 0.05-0.07% leveling agent, and 0.04-0.06% dispersant; based on the weight of the polyurethane waterproof coating; the sum of the contents of each component in the polyurethane waterproof coating is 100%, based on the weight of the polyurethane waterproof coating.

[0040] In an embodiment of the present invention, the polyurethane waterproof coating can be used to prepare a waterproof coating on the surface of an object. The thickness of the waterproof coating is 600-800 μm, which is the thickness perpendicular to the plane where the coating is located measured by, for example, a micrometer. The surface of the object is usually the surface of the object to which the thin-coated polyurethane waterproof coating of the present invention is applicable, such as the bridge deck, railway such as the high-speed railway deck, and the surface of other exposed objects.

[0041] In an embodiment of the present invention, the polyurethane waterproof coating can be applied to the surface of an object in the form of a single layer or multiple layers, and the application method may include any one of rolling, brushing, scraping, and spraying. Before applying the polyurethane waterproof coating, the surface of the object may be optionally primed (also called a sealing treatment). The primer (also called a sealing paint) used for the primer is a commonly used two-component epoxy primer known to those skilled in the art, which generally includes component A and component B, wherein component A mainly includes epoxy resins such as E-51, toughening agents, silane coupling agents, solvents, etc., and component B mainly plays the role of a curing agent, which may include components commonly used in the art that play a curing role and related other functional additives, solvents, etc. The polyurethane waterproof coating of the embodiment of the present invention is a single-component coating, which has a simple application method and can be directly applied at the construction site without the need for a mixing step similar to the two-component coating of the prior art.

[0042] In an embodiment of the present invention, a method for preparing the above-mentioned polyurethane waterproof coating comprises mixing polytetramethylene ether, an aging agent, a cross-linking agent, a filler, and other functional additives to obtain a first mixture; adding isocyanate, a catalyst, a latent curing agent, a hydrolysis accelerator, and a solvent to the first mixture in sequence, and reacting for, for example, 2.5-5 hours to obtain the polyurethane waterproof coating.

[0043] Optionally, the method for preparing the above-mentioned polyurethane waterproof coating comprises mixing polytetrahydrofuran ether, a plasticizer such as chlorinated paraffin, a defoamer, a dispersant, an ultraviolet absorber, a light stabilizer, an antioxidant, a crosslinking agent (such as TMP), and a filler in a reaction kettle and removing water at the same time;

[0044] Then, a mixture of isocyanate and solvent is added to the reactor to carry out a polymerization reaction; in this step, the proportion of the added solvent to the total amount of solvent is higher than that in other steps, which helps to fully mix the reactants and thus make the reaction more complete;

[0045] Then, a solution of the catalyst in the solvent is added to the reactor to continue the polymerization reaction;

[0046] Then add the leveling agent, latent curing agent, hydrolysis accelerator, other catalysts and optional other solvents (if there is any solvent) into the reaction kettle, mix them evenly, degas, and obtain the polyurethane waterproof coating.

[0047] Optionally, the method for preparing the above-mentioned polyurethane waterproof coating comprises putting polytetramethylene oxide, a plasticizer such as chlorinated paraffin, a defoamer, a dispersant, an ultraviolet absorber, a light stabilizer, an antioxidant, a crosslinking agent (such as TMP), and a filler into a reaction kettle, and dispersing them at a high speed of 800-1600 r / min, such as 1200 r / min, for 2 to 3 hours at 80-140° C., such as 110° C. and a vacuum degree of 0.03-0.01 MPa, such as 0.095 MPa, to mix them evenly and remove water at the same time;

[0048] Then, the temperature is lowered to 70-95° C., for example, 85° C., the vacuum is turned off, and a mixture of isocyanate in a solvent is added to the reactor, wherein the amount of the solvent is 35-60%, based on the total weight of the solvent contained in the polyurethane waterproof coating, and the polymerization reaction is carried out for 2-3 hours; in this step, the proportion of the added solvent to the total amount of the solvent is higher than that in other steps, which helps to fully mix the reactants, thereby making the reaction more complete;

[0049] Then, the temperature is lowered to 60-80° C., for example, 75° C., and a solution of a catalyst in a solvent is added, wherein the amount of the catalyst is 40-50%, for example, 44-50%, based on the total weight of the catalyst contained in the polyurethane waterproof coating, and the amount of the solvent is 20-40%, based on the total weight of the solvent contained in the polyurethane waterproof coating, and then the polymerization is continued for 0.5-1.5 h, for example, 1 h (not less than 0.5 h);

[0050] Then, the temperature is lowered to 50-70°C, for example, 65°C, and a leveling agent, a latent curing agent, a hydrolysis accelerator, other catalysts and optional other solvents (if any) are added, followed by mixing for 20 minutes (mixing until uniform); degassing is performed for 5 minutes in a vacuum environment of 0.03-0.07MPa, for example, 0.06MPa; and a polyurethane waterproof coating is obtained.

[0051] In the preparation method, the stepwise addition of the catalyst, especially the addition of part of the catalyst in the last step, can help improve the drying speed of the polyurethane waterproof coating during construction.

[0052] Those skilled in the art should understand that, in the above method, the temperature of "cooling to" in the latter step should be lower than the temperature in the previous step; and the order of the steps can be adjusted as needed.

[0053] The present invention is described below by specific examples. The examples described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in this area or the product instructions are used. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be obtained commercially.

[0054] raw material

[0055] Polytetramethylenetetrahydrofuran ether: PTMG1000, number average molecular weight of 1000 g / mol, purchased from BASF Chemical Company; PTMG2000, number average molecular weight of 2000 g / mol, purchased from BASF Chemical Company;

[0056] Polyether polyol: PPG1000, number average molecular weight of 1000 g / mol, purchased from Yantai Wanhua Company; PPG2000, number average molecular weight of 1000 g / mol, purchased from Yantai Wanhua Company;

[0057] Chlorinated paraffin: S52# superior grade, purchased from Guangzhou Yuting Company;

[0058] Defoaming agent: D6800, purchased from Hemmings Deqian Company;

[0059] Dispersant S18, purchased from Guangzhou Core Chemical Company;

[0060] UV absorber 326, purchased from BASF;

[0061] Light stabilizer 770, purchased from BASF;

[0062] Antioxidant 1010, purchased from BASF;

[0063] Trimethylolpropane (TMP), purchased from BASF;

[0064] Talc: WF-051, average particle size 3.5 μm; purchased from Jiangsu Qunxin Company;

[0065] Titanium dioxide: rutile type; purchased from Anhui Anada Titanium Industry Co., Ltd.;

[0066] Isocyanate: HDI, TDI, MDI, HMDI, purchased from Covestro;

[0067] Catalyst: C101, purchased from Arkema;

[0068] Latent curing agent: LCA-30, purchased from Foshan Juxin Innovation Materials Co., Ltd.;

[0069] Hydrolysis accelerator: A-289, purchased from Foshan Poly Innovation Materials Co., Ltd.

[0070] Leveling agent: BNK-317, purchased from Milliken Chemical Company; and

[0071] Solvent: Trimethylbenzene, purchased from Jiangyin Dading Chemical Company.

[0072] Example 1

[0073] (1) Put the amounts of polytetrahydrofuran ether, chlorinated paraffin, defoamer, dispersant, ultraviolet absorber, light stabilizer, antioxidant, TMP, talc, and titanium dioxide in Table 1 into a reaction kettle, and disperse them at a high speed of 1200 r / min at a vacuum degree of 0.095 MPa for 3 hours to mix them uniformly and remove water at the same time;

[0074] (2) the temperature was lowered to 85° C., the vacuum was turned off, and a mixture of isocyanates in an amount of 40% of a solvent based on the total weight of the solvent was added to the reactor to carry out a polymerization reaction for 2 hours;

[0075] (3) lowering the temperature to 75° C., adding a solution of 45% of the catalyst based on the total weight of the catalyst diluted with 30% of the solvent based on the total weight of the solvent (its concentration is 1%), and continuing the polymerization for, for example, 1 hour;

[0076] (4) The temperature is lowered to 65° C., and a leveling agent, other solvents, other catalysts, a latent curing agent, and a hydrolysis accelerator are added, followed by mixing for 20 minutes; degassing is performed under a vacuum environment of 0.06 MPa for 5 minutes; and a polyurethane waterproof coating is obtained.

[0077] The types and amounts of each component are summarized in Table 1.

[0078] Embodiment 2-7

[0079] The steps of Example 1 were repeated, except that the types and amounts of the components were changed, as shown in Table 1.

[0080] Table 1 Composition of polyurethane waterproof coating of each embodiment

[0081]

[0082] Comparative Examples 1-7

[0083] The steps of Example 1 were repeated, except that the types and amounts of the components were changed, as shown in Table 2.

[0084] Table 2 Composition of polyurethane waterproof coatings of various comparative examples

[0085]

[0086]

[0087] Performance Testing

[0088] The polyurethane waterproof coatings obtained from the embodiments and comparative examples were subjected to performance tests according to the Q / CR568-2017 standard (“Technical conditions for thin-coated polyurethane waterproof layers on high-speed railway concrete bridge decks”), and the results are summarized in Table 3.

[0089] At the same time, (1) the performance of the base coat of the thin-coat polyurethane coating disclosed in Example 3 of Chinese Application No. 201410474706 as Comparative Example A; and (2) the performance of the top coat of the thin-coat polyurethane coating disclosed in Example 3 of Chinese Application No. 201410474706 as Comparative Example A were tested.

[0090] Table 3 Performance of polyurethane waterproof coatings in various embodiments and comparative examples

[0091]

[0092]

[0093] According to the technical solution of the embodiment of the present invention, the thin-coat polyurethane waterproof coating of the present invention is a one-component coating. Compared with the prior art (Comparative Examples A and B), it is easy to construct, improves work efficiency, and has better weather resistance. At the same time, its adhesion and tensile strength are also higher.

[0094] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions may occur depending on design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A thin-coat polyurethane waterproof coating, characterized in that: The invention comprises 20.0-33.5% polytetramethylene ether, 6.5-16.0% isocyanate, 0.39-0.48% anti-aging agent, 0.2-0.35% cross-linking agent, 28-34% filler, 0.09-0.11% catalyst, 4.0-8.0% latent curing agent, 0.60-0.90% hydrolysis accelerator, 7.0-20.5% solvent and 5.79-15.0% other functional additives; the weight of the polyurethane waterproof coating is used as the basis.

2. The polyurethane waterproof coating according to claim 1, characterized in that: The number average molecular weight of the polytetramethylene oxide is 1000-2000 g / mol, measured according to DIN 55672-12016 gel permeation chromatography; the hydroxyl number is 50-120 mgKOH / g, measured according to the phthalic anhydride method of method A in GB / T 12008.3-2009.

3. The polyurethane waterproof coating according to claim 1 or 2, characterized in that: The isocyanate is an aliphatic isocyanate or an alicyclic isocyanate.

4. The polyurethane waterproof coating according to claim 1 or 2, characterized in that: The anti-aging agent includes one or more of an ultraviolet light absorber, a light stabilizer, and an antioxidant.

5. The polyurethane waterproof coating according to claim 1 or 2, characterized in that: In the polyurethane waterproof coating, the molar ratio of the hydroxyl value of polytetramethylene ether to the isocyanate group of isocyanate is (0.4-0.5):

1.

6. The polyurethane waterproof coating according to claim 1 or 2, characterized in that: The other functional additives include 5.4-13% plasticizer, 0.3-0.5% defoamer, 0.05-0.70% leveling agent, and 0.04-0.06% dispersant, based on the weight of the polyurethane waterproof coating.

7. The polyurethane waterproof coating according to claim 1 or 2, characterized in that: The filler includes one or more of talc, titanium dioxide, calcium carbonate, clay, kaolin, etc.; the solvent includes at least one of C6-C8 aromatic hydrocarbons and C4-C8 alkanes.

8. Use of the polyurethane waterproof coating according to any one of claims 1 to 7 for preparing a waterproof coating on the surface of an object.

9. The use according to claim 8, characterized in that The thickness of the waterproof coating is 600-800 μm.

10. A method for preparing the polyurethane waterproof coating according to any one of claims 1 to 7, characterized in that: The method comprises mixing polytetrahydrofuran ether, an anti-aging agent, a cross-linking agent, a filler, and other functional additives to obtain a first mixture; and sequentially adding isocyanate, a catalyst, a latent curing agent, a hydrolysis accelerator, and a solvent to the first mixture to react to obtain the polyurethane waterproof coating.

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