A high-strength polyurethane waterproof coating and preparation method thereof

Abstract

The present invention relates to the technical field of decorative materials, and discloses a high-strength polyurethane waterproof coating and a preparation method thereof. The high-strength polyurethane waterproof coating comprises the following raw materials in parts by weight: 80-120 parts of diphenylmethane diisocyanate, 80-120 parts of bio-based polyether polyol, 1-10 parts of poly-N-isopropylacrylamide, 10-20 parts of polystyrene microspheres, 5-15 parts of composite fiber, 10-20 parts of 1,4-butanediol, 1-5 parts of polyfluorosilicone, 1-10 parts of TiO2 nanoparticles, 1-10 parts of nanofiller, 1-5 parts of antibacterial agent, 1-5 parts of catalyst, 1-5 parts of antifoaming agent, 1-5 parts of flexibilizer, and 1-5 parts of diluent. The present invention can not only improve the waterproof performance, wear resistance, strength, crack resistance and environmental performance of the polyurethane waterproof coating, but also give the coating a self-cleaning function, thereby increasing the weather resistance and pollution resistance of the coating.

Description

Technical Field

[0001] The present invention relates to the technical field of decorative materials, and in particular to a high-strength polyurethane waterproof coating and a preparation method thereof. Background Art

[0002] With the rapid growth of the national economy, continuous innovation in the construction industry has also brought new challenges to some traditional fields, including waterproof coatings. As a protective layer on the exterior of buildings, waterproof coatings effectively resist moisture erosion and have therefore attracted widespread attention. Polyurethane waterproof coatings are an emerging waterproof coating. They are made from raw materials such as isocyanates and polyethers through an addition polymerization reaction to produce a prepolymer containing isocyanate groups. With the addition of auxiliary ingredients such as fillers, catalysts, chain extenders, and organic solvents, polyurethane waterproof coatings with excellent waterproof properties are formed.

[0003] However, while traditional polyurethane waterproof coatings offer excellent waterproofing, good adhesion, and abrasion resistance, they suffer from limited strength and poor crack resistance. Furthermore, they are easily damaged by physical factors such as scratching and squeezing during daily use, which impacts their service life. Specifically, the polyurethane resin in traditional polyurethane coatings is weak and cannot withstand external impact and stretching. While the addition of fillers enhances strength, the interfacial bonding is poor, hindering crack resistance. During use, tiny cracks are prone to forming on the coating surface, which further expand under external forces, ultimately causing the coating to fall off.

[0004] On the other hand, traditional coatings often use petroleum-based materials as their primary raw materials, which poses certain environmental concerns. For example, phenyl isocyanate, a type of isocyanate, is toxic and can pollute the air upon volatilization. Solvents such as xylene can also cause environmental pollution upon volatilization. Therefore, the development of high-strength, self-healing, and environmentally friendly polyurethane coatings is a current research priority. Therefore, the present invention proposes a high-strength polyurethane waterproof coating and its preparation method. Summary of the Invention

[0005] In response to the problems in the related art, the present invention proposes a high-strength polyurethane waterproof coating and a preparation method thereof to overcome the above-mentioned technical problems existing in the existing related art.

[0006] To this end, the specific technical solutions adopted in the present invention are as follows:

[0007] According to one aspect of the present invention, a high-strength polyurethane waterproof coating is provided, comprising the following raw materials in parts by weight:

[0008] 80-120 parts of diphenylmethane diisocyanate, 80-120 parts of bio-based polyether polyol, 1-10 parts of poly N-isopropyl acrylamide, 10-20 parts of polystyrene microspheres, 5-15 parts of composite fibers, 10-20 parts of 1,4-butanediol, 1-5 parts of polyfluorosilicone, 1-10 parts of TiO2 nanoparticles, 1-10 parts of nanofiller, 1-5 parts of antibacterial agent, 1-5 parts of catalyst, 1-5 parts of antifoaming agent, 1-5 parts of softening agent and 1-5 parts of diluent.

[0009] The composite fiber is a mixture of glass fiber and carbon fiber, and the weight ratio of glass fiber to carbon fiber is 1:1. The particle size of the polystyrene microspheres is 10-40 μm, and the particle size of the TiO2 nanoparticles is 10-50 nm. The nanofiller is a mixture of any one or more of nanosilica, nanomontmorillonite, nanographene, and nanoalumina. The antibacterial agent is a mixture of any one or more of nanosilver, nanozinc oxide, hydroquinone, and quaternary ammonium salts. The catalyst is a mixture of any one or more of organic tin compounds and amine compounds. The antifoaming agent is any one of silicone oil and polydimethylsiloxane or a mixture of both. The flexible agent is any one of polyether-type flexible agent and polyester-type flexible agent or a mixture of both. The diluent is a mixture of any one or more of ethylene glycol monobutyl ether, acetone, ethyl acetate, and cellulose ether.

[0010] Specifically, the functions of the above raw materials are as follows:

[0011] Diphenylmethane diisocyanate: In order to reduce the health impact on operators and users during the coating production process, a low-toxicity isocyanate raw material is used. It has low toxicity but can still react with polyether to form a prepolymer;

[0012] Bio-based polyether polyols: To improve the environmental performance of coatings, bio-based raw materials are used, thereby reducing the environmental impact of coatings. Their raw materials are usually derived from renewable resources such as vegetable oils and biomass, with a lower carbon footprint and environmental impact.

[0013] Poly (N-isopropylacrylamide): To make the coating exhibit different properties at different temperatures. For example, at high temperatures, the coating can become softer to improve heat resistance; at low temperatures, the coating can become harder to improve cold resistance.

[0014] The principle that poly(N-isopropylacrylamide) makes the coating exhibit different properties at different temperatures is as follows:

[0015] Temperature response effect: There are hydrophilic and hydrophobic groups distributed at intervals on the poly (N-isopropylacrylamide) molecular chain. When the temperature rises, the molecular chain shrinks, the hydrophobic groups aggregate, and the molecular chain becomes hydrophobic.

[0016] Critical Solution Temperature: Poly(N-isopropylacrylamide) has a well-defined critical solution temperature (LCST). When the temperature is below the LCST, poly(N-isopropylacrylamide) has high solubility and stable dispersion. When the temperature is above the LCST, the solubility decreases and aggregation and precipitation occur.

[0017] Viscosity change: Temperature rise causes poly (N-isopropylacrylamide) to change from an expanded state to a contracted state, the molecular chain entanglement is enhanced, and the solution viscosity increases;

[0018] Coordination effect: Poly(N-isopropylacrylamide) can coordinate with other components in the coating. Increasing the temperature promotes coordination and enhances the performance of the coating.

[0019] Phase transition: The solution phase transition of poly (N-isopropylacrylamide) has a certain transition range, which makes the coating performance change continuously and smoothly;

[0020] Polystyrene microspheres: can improve the mechanical properties and weather resistance of coatings;

[0021] Composite fiber: Glass fiber and carbon fiber can significantly improve the strength of the coating, have high tensile strength and compressive strength, and can enhance the mechanical properties of the coating;

[0022] 1,4-Butanediol: can increase the crosslinking density and strength of polyurethane waterproof coatings;

[0023] Polyfluorosilicone: It can provide good weather resistance and anti-pollution properties. The fluorine atoms reduce the surface energy, and the siloxane main chain provides strength. The synergistic effect of the two makes polyfluorosilicone have excellent weather resistance and anti-pollution properties.

[0024] TiO2 nanoparticles: They can provide self-cleaning functionality, namely, TiO2 degrades pollutants through photocatalysis. Its super-hydrophilicity and nano-effect further enhance the effect, and its compatibility with the substrate makes it an economical and environmentally friendly self-cleaning additive;

[0025] Nanofillers: They can improve the mechanical properties, abrasion resistance, and weather resistance of coatings. Due to their small particle size, nanofillers can be more evenly distributed in the coating, thereby improving the coating's density and water resistance.

[0026] According to another aspect of the present invention, there is provided a method for preparing a high-strength polyurethane waterproof coating, comprising the following steps:

[0027] S1. Weighing a preset number of parts by weight of raw materials for preparing a high-strength polyurethane waterproof coating;

[0028] S2, adding diphenylmethane diisocyanate, bio-based polyether polyol and 1,4-butanediol into a reactor and stirring evenly;

[0029] S3. Gradually add poly (N-isopropylacrylamide) to the reactor and continue stirring to ensure uniform distribution;

[0030] S4, adding polystyrene microspheres, composite fibers, polyfluorosilicone, TiO2 nanoparticles and nanofillers into the reactor in sequence, and continuing to stir evenly;

[0031] S5. Add an antibacterial agent, a catalyst, an antifoaming agent, a softener, and a diluent to the reactor and continue stirring until a uniform coating is obtained;

[0032] S6. Degas the evenly mixed coating under vacuum conditions to obtain a finished high-strength polyurethane waterproof coating.

[0033] The beneficial effects of the present invention are as follows: by using diphenylmethane diisocyanate and bio-based polyether polyol as the main ingredients, and adding poly (N-isopropyl acrylamide), polystyrene microspheres, composite fibers, 1,4-butanediol, polyfluorosilicone, TiO2 nanoparticles, nanofillers, and additives as auxiliary ingredients, the waterproofing, wear resistance, strength, and crack resistance of the polyurethane waterproof coating can be improved, and the use of bio-based polyether polyol can also make the coating environmentally friendly. In addition, the use of polyfluorosilicone, TiO2 nanoparticles, and antibacterial agents can give the coating a self-cleaning function, increasing the coating's weather resistance and pollution resistance. At the same time, the use of poly (N-isopropyl acrylamide) allows the coating to exhibit different properties at different temperatures, that is, the coating can become softer at high temperatures to improve heat resistance, and harder at low temperatures to improve cold resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 The present invention is a flowchart of a method for preparing a high-strength polyurethane waterproof coating according to an embodiment of the present invention. DETAILED DESCRIPTION

[0036] To further illustrate each embodiment, the present invention provides drawings, which are part of the disclosure of the present invention. They are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. By referring to these contents, ordinary technicians in this field should be able to understand other possible implementation methods and advantages of the present invention. The components in the figures are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0037] According to an embodiment of the present invention, a high-strength polyurethane waterproof coating and a preparation method thereof are provided.

[0038] The present invention is now further described with reference to the accompanying drawings and specific embodiments. According to one aspect of the present invention, a high-strength polyurethane waterproof coating is provided, comprising the following raw material components in parts by weight:

[0039] 80-120 parts of diphenylmethane diisocyanate, 80-120 parts of bio-based polyether polyol, 1-10 parts of poly N-isopropyl acrylamide, 10-20 parts of polystyrene microspheres, 5-15 parts of composite fibers, 10-20 parts of 1,4-butanediol, 1-5 parts of polyfluorosilicone, 1-10 parts of TiO2 nanoparticles, 1-10 parts of nanofiller, 1-5 parts of antibacterial agent, 1-5 parts of catalyst, 1-5 parts of antifoaming agent, 1-5 parts of softening agent and 1-5 parts of diluent.

[0040] The composite fiber is a mixture of glass fiber and carbon fiber, and the weight ratio of glass fiber to carbon fiber is 1:1. The particle size of the polystyrene microspheres is 10-40 μm, and the particle size of the TiO2 nanoparticles is 10-50 nm. The nanofiller is a mixture of any one or more of nanosilica, nanomontmorillonite, nanographene, and nanoalumina. The antibacterial agent is a mixture of any one or more of nanosilver, nanozinc oxide, hydroquinone, and quaternary ammonium salts. The catalyst is a mixture of any one or more of organic tin compounds and amine compounds. The antifoaming agent is any one of silicone oil and polydimethylsiloxane or a mixture of both. The flexible agent is any one of polyether-type flexible agent and polyester-type flexible agent or a mixture of both. The diluent is a mixture of any one or more of ethylene glycol monobutyl ether, acetone, ethyl acetate, and cellulose ether.

[0041] In order to better understand the above technical solutions of the present invention, specific examples of the present invention are described in detail below.

[0042] Example 1

[0043] A high-strength polyurethane waterproof coating comprises the following raw materials in parts by weight:

[0044] 80 parts of diphenylmethane diisocyanate, 80 parts of bio-based polyether polyol, 1 part of poly N-isopropyl acrylamide, 10 parts of polystyrene microspheres, 5 parts of composite fibers, 10 parts of 1,4-butanediol, 1 part of polyfluorosilicone, 1 part of TiO2 nanoparticles, 1 part of nanofiller, 1 part of antibacterial agent, 1 part of catalyst, 1 part of antifoaming agent, 1 part of softening agent and 1 part of diluent.

[0045] The composite fiber is a mixture of glass fiber and carbon fiber, with a weight ratio of glass fiber to carbon fiber of 1:1. The particle size of the polystyrene microspheres is 10 μm, and the particle size of the TiO2 nanoparticles is 10 nm. The nanofiller is nanosilica. The antibacterial agent is nanosilver. The catalyst is dioctyltin. The antifoaming agent is silicone oil. The flexibility agent is a polyether flexibility agent (preferably polyether ketone alcohol). The diluent is ethylene glycol monobutyl ether.

[0046] Example 2

[0047] A high-strength polyurethane waterproof coating comprises the following raw materials in parts by weight:

[0048] 90 parts of diphenylmethane diisocyanate, 90 parts of bio-based polyether polyol, 3 parts of poly N-isopropyl acrylamide, 13 parts of polystyrene microspheres, 8 parts of composite fibers, 1,4-butanediol, 13 parts of polyfluorosilicone, 2 parts of TiO2 nanoparticles, 2 parts of nanofiller, 2 parts of antibacterial agent, 2 parts of catalyst, 2 parts of antifoaming agent, 2 parts of softener and 2 parts of diluent.

[0049] The composite fiber is a mixture of glass fiber and carbon fiber, and the weight ratio of glass fiber to carbon fiber is 1:1. The particle size of the polystyrene microspheres is 20 μm, and the particle size of the TiO2 nanoparticles is 30 nm. The nanofiller is a mixture of nanosilica and nanographene. The antibacterial agent is a mixture of nanosilver and nanozinc oxide. The catalyst is dioctyltin. The antifoaming agent is a mixture of silicone oil and polydimethylsiloxane. The flexible agent is a polyester flexible agent (preferably dibutyl phthalate). The diluent is a mixture of ethylene glycol monobutyl ether and acetone.

[0050] Example 3

[0051] A high-strength polyurethane waterproof coating comprises the following raw materials in parts by weight:

[0052] 100 parts of diphenylmethane diisocyanate, 100 parts of bio-based polyether polyol, 5 parts of poly N-isopropyl acrylamide, 15 parts of polystyrene microspheres, 10 parts of composite fibers, 15 parts of 1,4-butanediol, 3 parts of polyfluorosilicone, 5 parts of TiO2 nanoparticles, 5 parts of nanofiller, 3 parts of antibacterial agent, 3 parts of catalyst, 3 parts of antifoaming agent, 3 parts of softener and 3 parts of diluent.

[0053] The composite fiber is a mixture of glass fiber and carbon fiber, with the weight ratio of glass fiber to carbon fiber being 1:1. The particle size of the polystyrene microspheres is 40 μm, and the particle size of the TiO2 nanoparticles is 50 nm. The nanofiller is nanoalumina. The antibacterial agent is nanozinc oxide. The catalyst is an amine compound (preferably an aromatic amine). The antifoaming agent is polydimethylsiloxane. The flexible agent is a polyester-type flexible agent (preferably dibutyl phthalate). The diluent is cellulose ether.

[0054] Example 4

[0055] A high-strength polyurethane waterproof coating comprises the following raw materials in parts by weight:

[0056] 110 parts of diphenylmethane diisocyanate, 110 parts of bio-based polyether polyol, 8 parts of poly N-isopropylacrylamide, 18 parts of polystyrene microspheres, 12 parts of composite fibers, 18 parts of 1,4-butanediol, 4 parts of polyfluorosilicone, 8 parts of TiO2 nanoparticles, 4 parts of nanofiller, 4 parts of antibacterial agent, 4 parts of catalyst, 4 parts of antifoaming agent, 4 parts of softener and 4 parts of diluent.

[0057] The composite fiber is a mixture of glass fiber and carbon fiber, and the weight ratio of glass fiber to carbon fiber is 1:1. The particle size of the polystyrene microspheres is 20 μm, and the particle size of the TiO2 nanoparticles is 30 nm. The nanofiller is a mixture of nanosilica and nanographene. The antibacterial agent is a mixture of nanosilver and nanozinc oxide. The catalyst is dioctyltin. The antifoaming agent is a mixture of silicone oil and polydimethylsiloxane. The flexible agent is a polyester flexible agent (preferably dibutyl phthalate). The diluent is a mixture of ethylene glycol monobutyl ether and acetone.

[0058] Example 5

[0059] A high-strength polyurethane waterproof coating comprises the following raw materials in parts by weight:

[0060] 120 parts of diphenylmethane diisocyanate, 120 parts of bio-based polyether polyol, 10 parts of poly N-isopropyl acrylamide, 20 parts of polystyrene microspheres, 15 parts of composite fibers, 20 parts of 1,4-butanediol, 5 parts of polyfluorosilicone, 10 parts of TiO2 nanoparticles, 10 parts of nanofiller, 5 parts of antibacterial agent, 5 parts of catalyst, 5 parts of antifoaming agent, 5 parts of softening agent and 5 parts of diluent.

[0061] The composite fiber is a mixture of glass fiber and carbon fiber, with the weight ratio of glass fiber to carbon fiber being 1:1. The particle size of the polystyrene microspheres is 40 μm, and the particle size of the TiO2 nanoparticles is 50 nm. The nanofiller is nanoalumina. The antibacterial agent is nanozinc oxide. The catalyst is an amine compound (preferably an aromatic amine). The antifoaming agent is polydimethylsiloxane. The flexible agent is a polyester-type flexible agent (preferably dibutyl phthalate). The diluent is cellulose ether.

[0062] Comparative Example

[0063] A high-strength polyurethane waterproof coating comprises the following raw materials in parts by weight:

[0064] 120 parts of isocyanate, 120 parts of polyether, 10 parts of anhydrous filler, 5 parts of catalyst, 5 parts of antifoaming agent, 5 parts of softener and 5 parts of diluent.

[0065] The anhydrous filler is silica. The antibacterial agent is nano zinc oxide. The catalyst is an amine compound (preferably an aromatic amine). The antifoaming agent is polydimethylsiloxane. The flexible agent is a polyester-type flexible agent (preferably dibutyl phthalate). The diluent is cellulose ether.

[0066] Test example:

[0067] A high-strength polyurethane waterproof coating obtained in Examples 1-3 of the present invention was subjected to a brushing test with a thickness of 1 mm. The test results were shown in Table 1 below according to the test method specified in the national standard (GB / T23445-2009):

[0068] Table 1 Test results

[0069]

[0070] It can be seen from the above test results that the various properties of the high-strength polyurethane waterproof coatings of Examples 1-5 of the present invention are greatly improved compared with the various properties of the polyurethane waterproof coatings of the comparative example.

[0071] According to another aspect of the present invention, Figure 1 As shown, a method for preparing a high-strength polyurethane waterproof coating is provided, comprising the following steps:

[0072] S1. Weighing a preset number of parts by weight of raw materials for preparing a high-strength polyurethane waterproof coating;

[0073] S2, adding diphenylmethane diisocyanate, bio-based polyether polyol and 1,4-butanediol into a reactor and stirring evenly;

[0074] S3. Gradually add poly (N-isopropylacrylamide) to the reactor and continue stirring to ensure uniform distribution;

[0075] S4, adding polystyrene microspheres, composite fibers, polyfluorosilicone, TiO2 nanoparticles and nanofillers into the reactor in sequence, and continuing to stir evenly;

[0076] S5. Add an antibacterial agent, a catalyst, an antifoaming agent, a softener, and a diluent to the reactor and continue stirring until a uniform coating is obtained;

[0077] S6. Degas the evenly mixed coating under vacuum conditions to obtain a finished high-strength polyurethane waterproof coating.

[0078] In summary, with the help of the above technical solution of the present invention, by using diphenylmethane diisocyanate and bio-based polyether polyol as the main ingredients, and adding poly (N-isopropyl acrylamide), polystyrene microspheres, composite fibers, 1,4-butanediol, polyfluorosilicone, TiO2 nanoparticles, nanofillers and additives as auxiliary materials, it is possible to not only improve the waterproofing, wear resistance, strength and crack resistance of the polyurethane waterproof coating, but also make the coating environmentally friendly by using bio-based polyether polyol. In addition, the use of polyfluorosilicone, TiO2 nanoparticles and antibacterial agents can give the coating a self-cleaning function, increase the coating's weather resistance and pollution resistance, and at the same time, the use of poly (N-isopropyl acrylamide) allows the coating to exhibit different properties at different temperatures, that is, the coating can become softer at high temperatures to improve heat resistance, and harder at low temperatures to improve cold resistance.

[0079] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A high-strength polyurethane waterproof coating, characterized in that: The invention comprises the following raw materials in parts by weight: 80-120 parts of diphenylmethane diisocyanate, 80-120 parts of bio-based polyether polyol, 1-10 parts of poly (N-isopropylacrylamide), 10-20 parts of polystyrene microspheres, 5-15 parts of composite fiber, 10-20 parts of 1,4-butanediol, 1-5 parts of polyfluorosilicone, 1-10 parts of TiO2 nanoparticles, 1-10 parts of nanofiller, 1-5 parts of antibacterial agent, 1-5 parts of catalyst, 1-5 parts of antifoaming agent, 1-5 parts of flexibilizer, and 1-5 parts of diluent; Among them, bio-based polyether polyol makes the coating environmentally friendly, and poly N-isopropyl acrylamide makes the coating softer at high temperatures to improve heat resistance and harder at low temperatures to improve cold resistance.

2. A high-strength polyurethane waterproof coating according to claim 1, characterized in that: The composite fiber is a mixture of glass fiber and carbon fiber, and the weight ratio of the glass fiber to the carbon fiber is 1:

1.

3. The high-strength polyurethane waterproof coating according to claim 1, characterized in that: The particle size of the polystyrene microspheres is 10-40 μm, and the particle size of the TiO2 nanoparticles is 10-50 nm.

4. The high-strength polyurethane waterproof coating according to claim 1, characterized in that: The nano filler is a mixture of any one or more of nano silica, nano montmorillonite, nano graphene and nano alumina.

5. The high-strength polyurethane waterproof coating according to claim 1, characterized in that: The antibacterial agent is a mixture of any one or more of nano silver, nano zinc oxide, hydroquinone and quaternary ammonium salt.

6. The high-strength polyurethane waterproof coating according to claim 1, characterized in that: The catalyst is a mixture of any one or more of an organic tin compound and an amine compound.

7. The high-strength polyurethane waterproof coating according to claim 1, characterized in that: The antifoaming agent is any one of silicone oil and polydimethylsiloxane or a mixture of the two.

8. The high-strength polyurethane waterproof coating according to claim 1, characterized in that: The flexible agent is any one of a polyether-type flexible agent and a polyester-type flexible agent, or a mixture of the two.

9. The high-strength polyurethane waterproof coating according to claim 1, characterized in that: The diluent is a mixture of any one or more of ethylene glycol monobutyl ether, acetone, ethyl acetate, and cellulose ether.

10. A method for preparing a high-strength polyurethane waterproof coating, for preparing the high-strength polyurethane waterproof coating according to any one of claims 1 to 9, characterized in that: The preparation method of the high-strength polyurethane waterproof coating comprises the following steps: S1. Weighing a preset number of parts by weight of raw materials for preparing a high-strength polyurethane waterproof coating; S2, adding diphenylmethane diisocyanate, bio-based polyether polyol and 1,4-butanediol into a reactor and stirring evenly; S3. Gradually add poly (N-isopropylacrylamide) to the reactor and continue stirring to ensure uniform distribution; S4, adding polystyrene microspheres, composite fibers, polyfluorosilicone, TiO2 nanoparticles and nanofillers into the reactor in sequence, and continuing to stir evenly; S5. Add an antibacterial agent, a catalyst, an antifoaming agent, a softener, and a diluent to the reactor and continue stirring until a uniform coating is obtained; S6. Degas the evenly mixed coating under vacuum conditions to obtain a finished high-strength polyurethane waterproof coating.

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