Polyurethane waterproof coating composition, polyurethane waterproof coating and preparation method and application thereof

Abstract

The application relates to the field of engineering waterproof materials, and discloses a polyurethane waterproof coating composition, a polyurethane waterproof coating and a preparation method and application thereof. The composition contains a main agent and an auxiliary agent; the main agent comprises polyol, isocyanate, hydroxy acrylate, soft monomer and hard monomer; the content of the isocyanate is 30-70 parts by weight, the content of the hydroxy acrylate is 5-15 parts by weight, the content of the soft monomer is 15-35 parts by weight, the content of the hard monomer is 75-100 parts by weight and the content of the auxiliary agent is 160-220 parts by weight, relative to 100 parts by weight of the polyol. The polyurethane waterproof coating obtained by the application has the advantages of ensuring the strength mechanical property, lower viscosity and high solid content.

Description

Technical Field

[0001] This invention relates to the field of engineering waterproofing materials, specifically to a composition for polyurethane waterproof coatings, polyurethane waterproof coatings, their preparation methods, and applications. Background Technology

[0002] Aliphatic polyurethane waterproof coatings are widely used in construction, transportation, and corrosion protection due to their excellent weather resistance, UV aging resistance, and chemical stability. However, existing products generally suffer from low solid content (usually ≤70%) and high viscosity (≥5000 mPa·s), resulting in insufficient film thickness, low construction efficiency, and difficulty in meeting the requirements of high-durability projects.

[0003] Most existing aliphatic polyurethane coatings use solvent-based systems. Their solid content is limited by the resin molecular weight and solvent ratio, leading to increased coating weight per unit area and higher construction costs. Commercially available products have a solid content of only 70%, requiring multiple coats to achieve the designed thickness of 1.5mm.

[0004] Currently, researchers in this field typically use methods such as increasing the amount of plasticizer, reducing the amount of filler, and increasing the isocyanate group (NCO value) to improve the above-mentioned defects. However, these methods can only slightly improve the applicability at the construction end and cannot fundamentally solve the problem. They can also lead to negative effects such as plasticizer migration, significant cost increase, and decreased physical properties.

[0005] Therefore, there is an urgent need to develop a physically stable aliphatic polyurethane waterproof coating with high solids content and low viscosity to meet the comprehensive needs of contractors and owners. Summary of the Invention

[0006] The purpose of this invention is to solve the problems of high viscosity and low solids content in existing aliphatic polyurethane waterproof coatings.

[0007] To achieve the above objectives, a first aspect of the present invention provides a composition for a polyurethane waterproof coating, the composition comprising a main agent and an auxiliary agent; said main agent includes polyol, isocyanate, hydroxy acrylate, soft monomer, and hard monomer; Relative to 100 parts by weight of the polyol, the content of the isocyanate is 30-70 parts by weight, the content of the hydroxy acrylate is 5-15 parts by weight, the content of the soft monomer is 15-35 parts by weight, the content of the hard monomer is 75-100 parts by weight, and the content of the additive is 160-220 parts by weight.

[0008] A second aspect of the present invention provides a method for preparing a polyurethane waterproof coating, the method comprising: mixing a mixture containing the components of the polyurethane waterproof coating composition described in the first aspect to obtain the polyurethane waterproof coating.

[0009] A third aspect of the present invention provides a polyurethane waterproof coating prepared by the method described in the second aspect.

[0010] The fourth aspect of the present invention provides the application of the polyurethane waterproof coating described in the third aspect in waterproofing exposed building environments.

[0011] This invention achieves a polyurethane waterproof coating with high solids content, low viscosity, high strength, low-temperature rapid curing, and excellent waterproof performance and durability by scientifically compounding polyols, isocyanates, hydroxy acrylates, soft monomers, and hard monomers, and precisely controlling their ratio. Detailed Implementation

[0012] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0013] As previously described, a first aspect of the present invention provides a composition for a polyurethane waterproof coating, the composition comprising a main agent and additives; the main agent includes polyols, isocyanates, hydroxyacrylates, soft monomers, and hard monomers; Relative to 100 parts by weight of the polyol, the content of the isocyanate is 30-70 parts by weight, the content of the hydroxy acrylate is 5-15 parts by weight, the content of the soft monomer is 15-35 parts by weight, the content of the hard monomer is 75-100 parts by weight, and the content of the additive is 160-220 parts by weight.

[0014] Preferably, relative to 100 parts by weight of the polyol, the isocyanate content is 44-50 parts by weight, the hydroxyacrylate content is 8-11.5 parts by weight, the soft monomer content is 17-20 parts by weight, and the hard monomer content is 80-90 parts by weight. The inventors have discovered that, under this preferred embodiment, multiple curing methods and multi-resin crosslinking copolymerization can be achieved, resulting in a polyurethane waterproof coating with higher solids content, lower viscosity, and superior mechanical properties.

[0015] Preferably, the hydroxyacrylate is selected from at least one of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, and hydroxypropyl methacrylate.

[0016] Preferably, the soft monomer is selected from at least one of butyl acrylate, ethyl acrylate, isobutyl acrylate, and 2-ethylhexyl acrylate.

[0017] Preferably, the hard monomer is selected from at least one of methyl methacrylate, methyl acrylate, styrene, and ethyl methacrylate.

[0018] Preferably, the polyol is selected from at least one of polytetrahydrofuran polyol and polyester polyol.

[0019] More preferably, the polyol is a combination of polytetrahydrofuran polyol A and polyester polyol B in a mass ratio of 1:3-5; the number average molecular weight of polytetrahydrofuran polyol A is 1500-2500; and the number average molecular weight of polytetrahydrofuran polyol B is 500-1000. The inventors have found that, under this preferred embodiment, the obtained polyurethane waterproof coating has higher solids content, lower viscosity, and superior mechanical properties.

[0020] Preferably, the isocyanate is selected from at least one of isophorone diisocyanate, 4,4-dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, and hexamethylene diisocyanate trimer.

[0021] More preferably, the isocyanate is a combination of hexamethylene diisocyanate trimer and 4,4-dicyclohexylmethane diisocyanate in a mass ratio of 1:10-15. The inventors have found that, under this preferred embodiment, the obtained polyurethane waterproof coating has higher solids content, lower viscosity, and superior mechanical properties.

[0022] Preferably, the additive is selected from at least one of chlorinated paraffin, defoamer, dispersant, ultraviolet absorber, light stabilizer, antioxidant, titanium dioxide, talc, hydrolysis accelerator, leveling agent, thixotropic agent, latent curing agent, curing agent, catalyst, and polymerization catalyst.

[0023] More preferably, the additives contain chlorinated paraffin, defoamer, dispersant, ultraviolet absorber, light stabilizer, antioxidant, titanium dioxide, talc, hydrolysis accelerator, leveling agent, thixotropic agent, latent curing agent, curing agent, catalyst, and polymerization catalyst.

[0024] More preferably, relative to 100 parts by weight of the polyol, the content of the chlorinated paraffin is 45-55 parts by weight, the content of the defoamer is 1-2 parts by weight, the content of the dispersant is 0.15-0.2 parts by weight, the content of the ultraviolet absorber is 0.4-0.6 parts by weight, the content of the light stabilizer is 0.4-0.6 parts by weight, the content of the antioxidant is 0.4-0.6 parts by weight, the content of titanium dioxide is 2-4 parts by weight, the content of talc is 120-130 parts by weight, the content of the hydrolysis accelerator is 2-3 parts by weight, the content of the leveling agent is 0.2-0.4 parts by weight, the content of the thixotropic agent is 0.4-0.6 parts by weight, the content of the latent curing agent is 5-9 parts by weight, the content of the curing agent is 4-6 parts by weight, the content of the catalyst is 0.5-1.5 parts by weight, and the content of the polymerization catalyst is 0.05-1 parts by weight.

[0025] Particularly preferably, the defoamer is selected from at least one of silicone defoamers, mineral oil defoamers, polyether defoamers, surfactant defoamers, and composite defoamers; the dispersant is selected from at least one of surfactant dispersants, polymer dispersants, and natural product-derived dispersants; the ultraviolet absorber is selected from at least one of benzophenones, salicylates, and benzotriazoles; the light stabilizer is selected from at least one of hindered amines and quenchers; the antioxidant is selected from at least one of amine antioxidants, phenolic antioxidants, and hydrogen peroxide decomposition agents; the hydrolysis accelerator is selected from at least one of oxazolidines and imines; the leveling agent is selected from at least one of silicones, acrylics, and fluorocarbons; the thixotropic agent is selected from at least one of polyamide waxes, polyurea derivatives, and fumed silica; the latent curing agent is at least one of oxazolidines and blocked imines; the curing agent is an organic peroxide curing agent; the catalyst is selected from tertiary amine accelerators; and the polymerization catalyst is selected from at least one of organometallic catalysts, amino catalysts, and organic base catalysts.

[0026] As previously stated, a second aspect of the present invention provides a method for preparing a polyurethane waterproof coating, the method comprising: mixing a mixture of the components of a composition containing the polyurethane waterproof coating described in the first aspect, to obtain the polyurethane waterproof coating.

[0027] Preferably, the mixing operation includes: (1) Combination A containing polyol and isocyanate is first mixed to obtain first material; combination A may optionally also contain chlorinated paraffin; (2) The hydroxyacrylate and the first material are mixed in a second mixture to obtain the second material; (3) Mix a portion of the additives, soft monomers and the second material in a third mixture to obtain a third material; (4) The hard monomer and the third material are mixed in a fourth way to obtain a fourth material; (5) Mix the remaining additives with the fourth material to obtain the polyurethane waterproof coating.

[0028] Preferably, the first mixture, the second mixture, the third mixture, the fourth mixture, and the fifth mixture are each carried out independently under stirring conditions.

[0029] Preferably, the conditions for the first mixing include: a temperature of 80-95°C, a time of 2-5 hours, and a stirring speed of 300-600 rpm.

[0030] Preferably, the conditions for the second mixing include: a temperature of 70-75°C, a time of 0.5-1 h, and a stirring speed of 500-1000 rpm.

[0031] Preferably, the conditions for the third mixing include: a temperature of 20-50°C, a time of 30-60 min, and a stirring speed of 200-1000 rpm; the conditions for the fourth mixing include: a temperature of 20-50°C, a time of 5-10 min, and a stirring speed of 200-1000 rpm; and the conditions for the fifth mixing include: a temperature of 20-50°C, a time of 2-4 min, and a stirring speed of 200-1000 rpm.

[0032] It should be noted that, in this invention, the temperatures of the first, second, third, fourth, and fifth mixtures in steps (1) to (5) can be specific temperature values ​​controlled within a defined range; or the temperature fluctuations within a defined range can be due to unavoidable heat release during the mixing process. The embodiments described below only illustrate specific mixing temperature values ​​that can achieve this invention, without illustrating the range values ​​caused by heat release. This invention will not be elaborated further here, and those skilled in the art should not interpret this as a limitation of the invention.

[0033] Preferably, in step (3), the auxiliary agent contains at least one of the following: defoamer, dispersant, ultraviolet absorber, light stabilizer, antioxidant, titanium dioxide, talc, hydrolysis accelerator, leveling agent, thixotropic agent, latent curing agent, and polymerization catalyst.

[0034] Preferably, in step (5), the remaining additives contain a curing agent and a catalyst.

[0035] In a preferred embodiment, the polyol is dehydrated before use. The dehydration is carried out under vacuum conditions, and the dehydration conditions include a temperature of 100-120°C and a time of 1-3 hours.

[0036] It should be noted that, in this invention, to promote rapid reaction, the components in the additive can be added in batches; alternatively, a suitable addition method can be selected based on the properties of each component. For example, in this invention, the polymerization catalyst can be added in multiple stages. For example, in this invention, the curing agent and catalyst are added sequentially before construction. Further details of this invention are omitted here, and those skilled in the art should not construe this as a limitation of the invention.

[0037] It should be noted that there are no special requirements for the instruments used in each step of the present invention. The appropriate mixing instrument is selected according to the properties of the raw materials themselves. For example, in step (3), in order to avoid the phenomenon of easy agglomeration when adding powder additives, the additives can be added by high-speed dispersion (for example, a planetary mixer can be used for feeding and mixing). The present invention will not elaborate further here, and those skilled in the art should not understand it as a limitation of the present invention.

[0038] As previously stated, a third aspect of the present invention provides a polyurethane waterproof coating prepared by the method described in the second aspect above.

[0039] As previously stated, the fourth aspect of the present invention provides the application of the polyurethane waterproof coating described in the third aspect in waterproofing exposed building environments.

[0040] The present invention will be described in detail below through embodiments.

[0041] Unless otherwise specified, all reagents and raw materials involved in the following examples are commercially available products, and all reagents are analytical grade products.

[0042] raw material: Polytetrahydrofuran polyol A: Functionality 2, number average molecular weight 2000, grade (model): PTMG2000, purchased from Mitsubishi Chemical Corporation; Polytetrahydrofuran polyol B: Functionality 2, number average molecular weight 1000, grade (model): PTMG1000, purchased from Mitsubishi Chemical Corporation; Polyester polyol: Functionality 2, number average molecular weight 1000, grade (model): XCP-1000PM, purchased from Asahikawa Chemical (Suzhou) Co., Ltd. Hexamethylene diisocyanate trimer: model HD-100, purchased from Wanhua Company; 4. 4-Dicyclohexylmethane diisocyanate: Model: Wannate HMDI; purchased from Wanhua Chemical Company; Defoamer: Deqian New Materials D6800; Dispersant: Core Chemical S18; UV absorber: BASF Tinuvin 326; Light stabilizer: BASF TINUVIN 770; Antioxidant: BASF Irganox® 1010; Hydrolysis accelerator: Accelerator B from Shandong Zhihuapu New Materials Co., Ltd.; Leveling agent: BNK-317 from Zhongshan Merrick Additives Co., Ltd.; Thixotropic agent: Crayvallac LA-150 from Arkema; ​​Latent curing agent: 800B from Suzhou Xiangyuan New Materials Co., Ltd.; Curing agent: Perkadox CH-50 from AkzoNobel; Catalyst: DMPT from Shandong Jiuan Chemical Co., Ltd.; Polymerization catalyst: T-12 catalyst from Xindian Chemical.

[0043] Example 1 This embodiment illustrates the preparation of the polyurethane waterproof coating provided by the present invention using the following steps: Polyols: A combination of polytetrahydrofuran polyol A and polytetrahydrofuran polyol B in a mass ratio of 1:4.65; Isocyanate: a combination of hexamethylene diisocyanate trimer and 4,4-dicyclohexylmethane diisocyanate in a mass ratio of 1:10; (1) 226g of polyol was dehydrated (vacuum dehydration, temperature 110℃, time 2h) and then mixed with chlorinated paraffin and isocyanate to obtain the first material; the conditions for the first mixing included: temperature 90℃, time 3h, and stirring speed 500rpm. (2) The hydroxyethyl acrylate and the first material are mixed in a second mixture to obtain the second material; the conditions for the second mixing include: temperature of 75°C, time of 1 h, and stirring speed of 800 rpm. (3) The defoamer, dispersant, ultraviolet absorber, light stabilizer, antioxidant, titanium dioxide, talc, hydrolysis accelerator, leveling agent, thixotropic agent, latent curing agent, polymerization catalyst, butyl acrylate and the second material are mixed in a third mixture to obtain the third material; the conditions for the third mixing include: temperature of 30°C, time of 30 min, and stirring speed of 500 rpm; (4) Methyl methacrylate and the third material are mixed in a fourth mixture to obtain a fourth material; the conditions for the fourth mixing include: temperature of 30°C, time of 10 min, and stirring speed of 500 rpm. (5) After mixing the curing agent with the fourth material for 2 minutes (temperature is 25℃, stirring speed is 500rpm), add the catalyst and mix for 1 minute (temperature is 25℃, stirring speed is 500rpm) to obtain the polyurethane waterproof coating S1; Relative to 100 parts by weight of the polyol, the content of the isocyanate is 44.6 parts by weight, the content of the hydroxyethyl acrylate is 8.6 parts by weight, the content of the butyl acrylate is 17.6 parts by weight, and the content of the methyl methacrylate is 80.6 parts by weight. Relative to 100 parts by weight of the polyol, the content of the chlorinated paraffin is 50 parts by weight, the content of the defoamer is 1.5 parts by weight, the content of the dispersant is 0.18 parts by weight, the content of the ultraviolet absorber is 0.525 parts by weight, the content of the light stabilizer is 0.5 parts by weight, the content of the antioxidant is 0.525 parts by weight, the content of the titanium dioxide is 2.35 parts by weight, the content of the talc is 125 parts by weight, the content of the hydrolysis accelerator is 2.2 parts by weight, the content of the leveling agent is 0.22 parts by weight, the content of the thixotropic agent is 0.5 parts by weight, the content of the latent curing agent is 7.75 parts by weight, the content of the curing agent is 5 parts by weight, the content of the catalyst is 1 part by weight, and the content of the polymerization catalyst is 0.18 parts by weight.

[0044] Example 2 This embodiment illustrates the preparation of the polyurethane waterproof coating provided by the present invention using the following steps: Polyols: A combination of polytetrahydrofuran polyol A and polytetrahydrofuran polyol B in a mass ratio of 1:3; Isocyanate: a combination of hexamethylene diisocyanate trimer and 4,4-dicyclohexylmethane diisocyanate in a mass ratio of 1:15; (1) 226g of polyol was dehydrated (vacuum dehydration, temperature 110℃, time 2h) and then mixed with chlorinated paraffin and isocyanate to obtain the first material; the conditions for the first mixing included: temperature 95℃, time 4h, and stirring speed 500rpm. (2) The hydroxyethyl acrylate and the first material are mixed in a second mixture to obtain the second material; the conditions for the second mixing include: temperature of 72°C, time of 0.5h, and stirring speed of 800rpm. (3) The defoamer, dispersant, ultraviolet absorber, light stabilizer, antioxidant, titanium dioxide, talc, hydrolysis accelerator, leveling agent, thixotropic agent, latent curing agent, polymerization catalyst, butyl acrylate and the second material are mixed in a third mixture to obtain the third material; the conditions for the third mixing include: temperature of 25°C, time of 40 min, and stirring speed of 500 rpm; (4) Methyl methacrylate and the third material are mixed in a fourth mixture to obtain a fourth material; the conditions for the fourth mixing include: temperature of 25°C, time of 8 min, and stirring speed of 500 rpm. (5) After mixing the curing agent with the fourth material for 2 minutes (temperature is 25℃, stirring speed is 500rpm), add the catalyst and mix for 1 minute (temperature is 25℃, stirring speed is 500rpm) to obtain the polyurethane waterproof coating S2; Relative to 100 parts by weight of the polyol, the content of the isocyanate is 50 parts by weight, the content of the hydroxyethyl acrylate is 11.3 parts by weight, the content of the butyl acrylate is 20 parts by weight, and the content of the methyl methacrylate is 85 parts by weight. Relative to 100 parts by weight of the polyol, the content of the chlorinated paraffin is 45 parts by weight, the content of the defoamer is 2 parts by weight, the content of the dispersant is 0.2 parts by weight, the content of the ultraviolet absorber is 0.4 parts by weight, the content of the light stabilizer is 0.5 parts by weight, the content of the antioxidant is 0.6 parts by weight, the content of the titanium dioxide is 4 parts by weight, the content of the talc is 120 parts by weight, the content of the hydrolysis accelerator is 3 parts by weight, the content of the leveling agent is 0.2 parts by weight, the content of the thixotropic agent is 0.6 parts by weight, the content of the latent curing agent is 8 parts by weight, the content of the curing agent is 6 parts by weight, the content of the catalyst is 1.5 parts by weight, and the content of the polymerization catalyst is 0.5 parts by weight.

[0045] Example 3 This embodiment follows a similar process to Example 1. The difference is that the amount of polyol used in this embodiment is the same as in Example 1, but the polyol is a combination of polytetrahydrofuran polyol A and polyester polyol with a mass ratio of 1:4.65.

[0046] Everything else is the same as in Example 1.

[0047] Polyurethane waterproof coating S3 was prepared.

[0048] Example 4 This embodiment follows a similar process to Example 1, except that in this embodiment, isophorone diisocyanate (converted to 77.6 parts by weight) with the same R value (molar amount of isocyanate group / molar amount of hydroxyl group) is used to replace 4,4-dicyclohexylmethane diisocyanate in Example 1.

[0049] Everything else is the same as in Example 1.

[0050] Polyurethane waterproof coating S4 was prepared.

[0051] Example 5 This embodiment follows a similar process to Example 1, except that in this embodiment, the amount of isocyanate used is 60 parts by weight relative to 100 parts by weight of polyol.

[0052] Everything else is the same as in Example 1.

[0053] Polyurethane waterproof coating S5 was prepared.

[0054] Example 6 This embodiment follows a similar process to Example 1, except that in this embodiment, the amount of hydroxyethyl acrylate used is 11.9 parts by weight relative to 100 parts by weight of polyol.

[0055] Everything else is the same as in Example 1.

[0056] Polyurethane waterproof coating S6 was prepared.

[0057] Example 7 This embodiment follows a similar process to Example 1, except that in this embodiment, the amount of hydroxyethyl acrylate used is 5.75 parts by weight relative to 100 parts by weight of polyol.

[0058] Everything else is the same as in Example 1.

[0059] Polyurethane waterproof coating S7 was prepared.

[0060] Example 8 This embodiment follows a similar process to Example 1, except that in this embodiment, the amount of butyl acrylate used is 30 parts by weight relative to 100 parts by weight of polyol.

[0061] Everything else is the same as in Example 1.

[0062] Polyurethane waterproof coating S8 was prepared.

[0063] Example 9 This embodiment follows a similar process to Example 1, except that in this embodiment, the amount of methyl methacrylate used is 100 parts by weight relative to 100 parts by weight of polyol.

[0064] Everything else is the same as in Example 1.

[0065] Polyurethane waterproof coating S9 was prepared.

[0066] Comparative Example 1 This comparative example was conducted using a similar process to Example 1, except that in this comparative example, the amount of hydroxyethyl acrylate used was 16 parts by weight relative to 100 parts by weight of polyol.

[0067] Everything else is the same as in Example 1.

[0068] The coating DS1 was prepared.

[0069] Comparative Example 2 This comparative example follows a similar procedure to Example 1, except that hydroxyethyl acrylate is not used. The specific steps are as follows: (1) Same as Example 1; (2) The first material is mixed in a second time to obtain the second material; the conditions for the second mixing include: temperature of 75°C, time of 1 hour, and stirring speed of 800 rpm. (3) Same as Example 1; (4) Same as Example 1; (5) Same as in Example 1, coating DS2 was obtained; All other cases not listed are the same as in Example 1.

[0070] The coating DS2 was prepared.

[0071] Comparative Example 3 This comparative example was carried out using a similar process to Example 1, except that butyl acrylate was not used in this comparative example.

[0072] Everything else is the same as in Example 1.

[0073] The coating DS3 was prepared.

[0074] Comparative Example 4 This comparative example follows a similar procedure to Example 1, except that methyl methacrylate is not used. The specific steps are as follows: (1) Same as Example 1; (2) Same as Example 1; (3) Same as Example 1; (4) The third material is mixed in a fourth way to obtain the fourth material; (5) Same as in Example 1, coating DS4 was obtained; All other processes not listed are the same as in Example 1.

[0075] The coating DS4 was prepared.

[0076] Test case The coatings obtained in the above examples were tested for performance according to standard JC / T2253-2014, and the results are shown in Table 1. Table 1

[0077] The results in Table 1 show that the polyurethane waterproof coating provided by this invention, while ensuring strength and mechanical properties, also has the beneficial effects of low viscosity and high solids content.

[0078] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing a polyurethane waterproof coating, characterized in that, The method includes: mixing a polyurethane waterproof coating with a mixture of the components in the composition to obtain the polyurethane waterproof coating; The composition for the polyurethane waterproof coating contains a main agent and additives; the main agent includes polyols, isocyanates, hydroxy acrylates, soft monomers, and hard monomers; Relative to 100 parts by weight of the polyol, the content of the isocyanate is 44-50 parts by weight, the content of the hydroxyacrylate is 8-11.5 parts by weight, the content of the soft monomer is 17-20 parts by weight, the content of the hard monomer is 80-90 parts by weight, and the content of the additives is 160-220 parts by weight; the additives contain a latent curing agent; The isocyanate is a combination of hexamethylene diisocyanate trimer and 4,4'-dicyclohexylmethane diisocyanate in a mass ratio of 1:10-15. The polyol is a combination of polytetrahydrofuran polyol A and polytetrahydrofuran polyol B in a mass ratio of 1:3-5; the number average molecular weight of polytetrahydrofuran polyol A is 2000-2500; and the number average molecular weight of polytetrahydrofuran polyol B is 1000. The hydroxy acrylate is selected from at least one of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, and hydroxypropyl methacrylate; The mixing operation includes: (1) Combination A containing polyol and isocyanate is first mixed to obtain first material; combination A may optionally also contain chlorinated paraffin; (2) The hydroxyacrylate and the first material are mixed in a second mixture to obtain the second material; (3) Mix the additives containing the latent curing agent, the soft monomer and the second material in a third mixture to obtain the third material; (4) The hard monomer and the third material are mixed in a fourth way to obtain a fourth material; (5) Mix the remaining additives with the fourth material to obtain the polyurethane waterproof coating.

2. The method according to claim 1, characterized in that, The soft monomer is selected from at least one of butyl acrylate, ethyl acrylate, isobutyl acrylate, and 2-ethylhexyl acrylate; And / or, the hard monomer is selected from at least one of methyl methacrylate, methyl acrylate, styrene, and ethyl methacrylate.

3. The method according to claim 2, characterized in that, The additives also contain chlorinated paraffin, defoamer, dispersant, ultraviolet absorber, light stabilizer, antioxidant, titanium dioxide, talc, hydrolysis accelerator, leveling agent, thixotropic agent, organic peroxide curing agent, catalyst and polymerization catalyst.

4. The method according to claim 1, characterized in that, The first mixture, the second mixture, the third mixture, the fourth mixture, and the fifth mixture are each carried out independently under stirring conditions; And / or, the conditions for the first mixing include: a temperature of 80-95°C, a time of 2-5 hours, and a stirring speed of 300-600 rpm; And / or, the conditions for the second mixing include: a temperature of 70-75°C, a time of 0.5-1 h, and a stirring speed of 500-1000 rpm.

5. The polyurethane waterproof coating prepared by the method of claim 1.

6. The application of the polyurethane waterproof coating according to claim 5 in waterproofing of exposed building surfaces.

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