Extreme low temperature resistant waterproof anticorrosive paint for metal roofs and preparation method of extreme low temperature resistant waterproof anticorrosive paint

Abstract

The invention relates to the technical field of waterproof and anticorrosive coatings for buildings, in particular to an ultimate low temperature resistant waterproof and anticorrosive coating for metal roofs and a preparation method of the waterproof and anticorrosive coating. According to the invention, an emulsion compounding system with low Tg and good freeze-thaw stability is selected or designed, and a core-shell structure or a cross-linking technology is adopted to balance the waterproof and anti-corrosion properties at low temperature. The high-efficiency and environment-friendly coalescing agent is added to ensure good film formation at low temperature, a proper amount of anti-freezing agent and a special freeze-thaw stabilizer are added to resist freeze-thaw damage, a rheological agent system with stable low-temperature performance is selected to ensure low-temperature constructability, and through strict synergistic optimization of the components in the formula and comprehensive low-temperature performance tests (freeze-thaw, film formation, construction and storage), the anti-freezing performance of the coating is greatly improved. The metal roof coating with excellent flexibility, high adhesive force, strong weather resistance and long-acting waterproof and anti-corrosion functions is provided for the application environment of extreme low temperature (such as-50 DEG C or even lower).

Description

Technical Field

[0001] This invention relates to the field of building waterproof and anti-corrosion coatings, specifically to a waterproof and anti-corrosion coating for metal roofs that can withstand extreme low temperatures and its preparation method. Background Technology

[0002] Metal roofing (such as corrugated steel sheets and aluminum-magnesium-manganese panels) is widely used in industrial plants, warehouses, airports, and stadiums. Conventional waterproof and anti-corrosion coatings (such as acrylic, polyurethane, and epoxy coatings) perform well at normal temperatures or generally low temperatures, but they have serious problems at extreme low temperatures (such as below -40°C). a. At low temperatures, brittleness increases, polymer chain segments freeze, the coating becomes hard and brittle, and loses its flexibility; b. The difference in shrinkage coefficients between the metal substrate and the coating at low temperatures leads to stress concentration, and the embrittled coating is very prone to cracking. c. At low temperatures, the adhesion between the coating and the metal substrate weakens, making it prone to peeling. Cracks and peeling of the coating allow corrosive media (moisture, salt) to penetrate the substrate, directly causing the failure of its waterproof and anti-corrosion functions.

[0003] There is a lack of existing metal roofing coating technologies that can simultaneously meet the requirements of extreme low-temperature flexibility, excellent adhesion, long-term weather resistance, waterproofing and corrosion resistance, and convenient construction for metal roofing. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, this invention provides a waterproof and anti-corrosion coating for metal roofs that can withstand extreme low temperatures and its preparation method.

[0005] This invention is achieved through the following technical solution: In a first aspect, the present invention provides a waterproof and anti-corrosion coating for metal roofing that is resistant to extreme low temperatures, characterized in that it is composed of the following components, in parts by weight: Resin base material: including 35-45 parts of fluorosilicone modified polyurethane dispersion, 10-15 parts of epoxy-acrylic core-shell emulsion, 0-5 parts of liquid fluorocarbon resin, 5-10 parts of low temperature plasticizer 1: dioctyl adipate (DOA) and polyester polyol compound, and 10-20 parts of low temperature toughening agent 2: hydrogenated nitrile rubber nanoparticles. Functional additives include: low-temperature film-forming aids: dodecyl alcohol ester TXIB, 1-2 parts of ultraviolet absorber, 2-4 parts of rheology modifier; antifreeze agents include 3-8 parts of propylene glycol; Functional fillers: including extender fillers, 10-20 parts of graphene-modified mica sheets; 3-7 parts of pigment titanium dioxide; 5-10 parts of hydrophobically modified TiO2 nanoparticles; 5-10 parts of multi-walled carbon nanotubes (MWCNTs); The above ingredients are listed in parts by weight.

[0006] Furthermore, the ultraviolet absorber is a benzotriazole, and the rheology modifier is fumed silica.

[0007] Furthermore, the mass ratio of dioctyl adipate (DOA) to polyester polyol is 1:1 to 1:2.

[0008] Secondly, the present invention provides a method for preparing a waterproof and anti-corrosion coating for metal roofing that is resistant to extreme low temperatures, characterized by comprising the following steps: (1) Add 35-45 parts of fluorosilicone modified polyurethane dispersion, 10-15 parts of epoxy-acrylic core-shell emulsion, and 0-5 parts of liquid fluorocarbon resin to a dispersion vessel, and mix at low speed (500 rpm) for 5 minutes. (2) Add 5-10 parts of dioctyl adipate (DOA) and polyester polyol compound, and 10-20 parts of hydrogenated nitrile rubber nanoparticles, and mix at low speed (700 rpm) for 5 minutes; (3) Add 1-2 parts of dodecyl alcohol ester (TXIB) and 1-2 parts of ultraviolet absorber in sequence, and mix at low speed (700 rpm) for 5 minutes; (4) Slowly add the filler material: 10-20 parts of graphene-modified mica sheets, 3-7 parts of titanium dioxide, 5-10 parts of hydrophobically modified TiO2 nanoparticles, and 5-10 parts of multi-walled carbon nanotubes (MWCNTs), and mix at high speed (1000 rpm) for 20 minutes. (5) Reduce the rotation speed to 500 rpm, add 3-8 parts of propylene glycol and 2-4 parts of fumed silica, disperse for 10-15 minutes, and discharge.

[0009] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention selects or designs an emulsion compound system with low Tg and good freeze-thaw stability, and uses a core-shell structure or cross-linking technology to balance waterproof and anti-corrosion performance at low temperatures. The addition of efficient and environmentally friendly film-forming aids ensures good film formation at low temperatures; the addition of appropriate amounts of antifreeze and special freeze-thaw stabilizers resists freeze-thaw damage; the selection of a rheology modifier system with stable low-temperature performance ensures low-temperature workability; and through rigorous optimization of the formulation components and comprehensive low-temperature performance testing (freeze-thaw, film formation, application, and storage), this invention provides a metal roofing coating with excellent flexibility, high adhesion, strong weather resistance, and long-lasting waterproof and anti-corrosion functions for extreme low-temperature applications (such as -50°C or even lower). Detailed Implementation

[0010] The present invention will be further described below.

[0011] Example 1 This invention selects or designs an emulsion compound system with low Tg and good freeze-thaw stability, and uses a core-shell structure or cross-linking technology to balance waterproofing and anti-corrosion performance at low temperatures. Highly efficient and environmentally friendly film-forming aids are added to ensure good film formation at low temperatures, and appropriate amounts of antifreeze and special freeze-thaw stabilizers are added to resist freeze-thaw damage. A rheology modifier system with stable low-temperature performance is selected to ensure low-temperature workability. Through rigorous optimization of the formulation components and comprehensive low-temperature performance testing (freeze-thaw, film formation, application, and storage), this invention provides a metal roofing coating with excellent flexibility, high adhesion, strong weather resistance, and long-lasting waterproofing and anti-corrosion functions for extreme low-temperature applications (such as -50°C or even lower). The following components are in parts by weight: 1. Resin base material (synergistic) 40 parts of fluorosilicone modified polyurethane dispersion 15 parts epoxy-acrylic core-shell emulsion 0 parts of liquid fluorocarbon resin Low-temperature plasticizer 1: 3 parts dioctyl adipate (DOA) and 3 parts polyester polyol compound. Low-temperature toughening agent 2: 10 parts of hydrogenated nitrile butadiene rubber nanoparticles 2. Functional additives Low-temperature film-forming aid: 3 parts dodecyl alcohol ester (TXIB) 2 parts of UV absorber (benzotriazole) 2 parts rheology modifier (fumed silica) Antifreeze: (propylene glycol) 3 parts 3. Pigments and fillers Filler material: 20 parts of graphene-modified mica sheets Pigment: 4 parts titanium dioxide Example 2 1. Resin base material (synergistic) 35 parts of fluorosilicone modified polyurethane dispersion 15 parts epoxy-acrylic core-shell emulsion 0 parts of liquid fluorocarbon resin Low-temperature plasticizer 1: 4 parts dioctyl adipate (DOA) and 4 parts polyester polyol compound. Low-temperature toughening agent 2: 7 parts of hydrogenated nitrile butadiene rubber nanoparticles 2. Functional additives Low-temperature film-forming aid: 3 parts dodecyl alcohol ester (TXIB) 2 parts of UV absorber (benzotriazole) 3 parts rheology modifier (fumed silica) Antifreeze: (propylene glycol) 3 parts 3. Pigments and fillers Pigment: 4 parts titanium dioxide 10 parts of hydrophobically modified TiO2 nanoparticles 10 parts of multi-walled carbon nanotubes (MWCNTs) Example 3 1. Resin base material (synergistic) 35 parts of fluorosilicone modified polyurethane dispersion 10 parts epoxy-acrylic core-shell emulsion 5 parts of liquid fluorocarbon resin Low-temperature plasticizer 1: 5 parts dioctyl adipate (DOA) and 5 parts polyester polyol compound. Low-temperature toughening agent 2: 7 parts of hydrogenated nitrile butadiene rubber nanoparticles 2. Functional additives Low-temperature film-forming aid: 3 parts dodecyl alcohol ester (TXIB) 2 parts of UV absorber (benzotriazole) 2 parts rheology modifier (fumed silica) Antifreeze: (propylene glycol) 3 parts 3. Pigments and fillers Pigment: 3 parts titanium dioxide 10 parts of hydrophobically modified TiO2 nanoparticles 10 parts of multi-walled carbon nanotubes (MWCNTs) Example 4 1. Resin base material (synergistic) 35 parts of fluorosilicone modified polyurethane dispersion 10 parts epoxy-acrylic core-shell emulsion 0 parts of liquid fluorocarbon resin Low-temperature plasticizer 1: 4 parts dioctyl adipate (DOA) and 4 parts polyester polyol compound. Low-temperature toughening agent 2: 7 parts of hydrogenated nitrile butadiene rubber nanoparticles 2. Functional additives Low-temperature film-forming aid: 3 parts dodecyl alcohol ester (TXIB) 2 parts of UV absorber (benzotriazole) 3 parts rheology modifier (fumed silica) Antifreeze: (propylene glycol) 3 parts 3. Pigments and fillers Filler material: 10 parts of graphene-modified mica sheets Pigment: 4 parts titanium dioxide 10 parts of hydrophobically modified TiO2 nanoparticles 5 parts of multi-walled carbon nanotubes (MWCNTs) Example 5 1. Resin base material (synergistic) 30 parts of fluorosilicone modified polyurethane dispersion 10 parts epoxy-acrylic core-shell emulsion 5 parts of liquid fluorocarbon resin Low-temperature plasticizer 1: 4 parts dioctyl adipate (DOA) and 4 parts polyester polyol compound. Low-temperature toughening agent 2: 7 parts of hydrogenated nitrile butadiene rubber nanoparticles 2. Functional additives Low-temperature film-forming aid: 2 parts dodecyl alcohol ester (TXIB) 3 parts of UV absorber (benzotriazole) 2 parts rheology modifier (fumed silica) Antifreeze: (propylene glycol) 4 parts 3. Pigments and fillers Filler material: 10 parts of graphene-modified mica sheets Pigment: 4 parts titanium dioxide 5 parts of hydrophobically modified TiO2 nanoparticles 10 parts of multi-walled carbon nanotubes (MWCNTs) Comparative Example 1 1. Resin base material (synergistic) 40 parts of fluorosilicone modified polyurethane dispersion 15 parts epoxy-acrylic core-shell emulsion Low-temperature toughening agent 2: 10 parts of hydrogenated nitrile butadiene rubber nanoparticles 2. Functional additives Low-temperature film-forming aid: 3 parts dodecyl alcohol ester (TXIB) 2 parts of UV absorber (benzotriazole) 3 parts rheology modifier (fumed silica) Antifreeze: (propylene glycol) 3 parts 3. Pigments and fillers Filler material: 20 parts mica powder Pigment: 4 parts titanium dioxide Comparative Example 2 1. Resin base material (synergistic) 45 parts of fluorosilicone modified polyurethane dispersion Low-temperature plasticizer 1: 5 parts of dioctyl adipate (DOA) Low-temperature plasticizer 1: 5 parts polyester polyol Low-temperature toughening agent 2: 10 parts of hydrogenated nitrile butadiene rubber nanoparticles 2. Functional additives Low-temperature film-forming aid: 3 parts dodecyl alcohol ester (TXIB) 2 parts of UV absorber (benzotriazole) 3 parts rheology modifier (fumed silica) Antifreeze: (propylene glycol) 3 parts 3. Pigments and fillers Filler material: 20 parts mica powder Pigment: 4 parts titanium dioxide Example 6 Formula composition (parts by weight) 1. Resin base material (synergistic) Fluorosilicone modified polyurethane dispersion, 35-45 parts (main film-forming material, Tg≤-60℃, weather resistance>15 years). 10-15 parts of epoxy-acrylic core-shell emulsion (enhances adhesion (>8MPa) and blocks the penetration of corrosive media) 0-5 parts of liquid fluorocarbon resin (surface energy <20mN / m, anti-icing adhesion) Low-temperature plasticizer 1: Dioctyl adipate (DOA) 3-4 (compound (addition amount 6-8%), ensuring elongation >300% at -70℃) Low-temperature plasticizer 1: Polyester polyol 3-4 Low-temperature toughening agent 2: 5-15 parts of hydrogenated nitrile butadiene rubber nanoparticles 2. Functional additives Low-temperature film-forming aid: 2-3 parts of dodecyl alcohol ester (TXIB) 1-2 parts of UV absorber (benzotriazole) Rheology modifier (fumed silica) 2-4 parts Antifreeze: (propylene glycol) 3-8 parts 3. Pigments and fillers Filler material: 10-20 parts of graphene-modified mica sheets (to enhance thermal conductivity uniformity and reduce low-temperature thermal stress cracking). Pigment: 3-7 parts titanium dioxide; 5-10 parts of hydrophobically modified TiO2 nanoparticles (photocatalytic decomposition of organic matter, maintaining surface cleanliness). 5-10 parts of multi-walled carbon nanotubes (MWCNTs) (MWCNTs can efficiently absorb light energy and convert it into heat energy) 1. Matrix resin system: Fluorocarbon resin, silicone-modified acrylic resin, vinyl acetate-ethylene copolymer emulsion, styrene-acrylate emulsion, or special modified polyurethane resin are selected. These resins themselves have excellent low-temperature toughness and weather resistance.

[0012] Preferred fluorocarbon resins: due to their extremely low glass transition temperature (Tg), excellent chemical inertness, weather resistance, and hydrophobicity. They offer excellent weather resistance, but low-temperature flexibility requires special formulation optimization.

[0013] Preferred silicone-modified acrylic resin: While maintaining the good properties of acrylic resin, siloxane bonds are introduced to improve flexibility, weather resistance, and low-temperature resistance. It inherently possesses excellent high and low temperature resistance, and modification further enhances adhesion, weather resistance, and strength.

[0014] Preferred special modified polyurethanes: Select or synthesize polyether-type or aliphatic polyurethane resins with excellent low-temperature elasticity, and select varieties with compliant molecular chains, moderate crosslinking density and good hydrolysis resistance. Low-temperature performance can be optimized through molecular design (such as organosilicon modification and fluorine modification).

[0015] Preferred core-shell structure emulsions: designed with a soft core (low Tg, ensuring low-temperature film formation) and a hard shell (higher Tg, providing the final coating with hardness, abrasion resistance and stain resistance).

[0016] Preferred self-crosslinking or post-crosslinking emulsions: These emulsions can undergo crosslinking reactions after film formation or under low-temperature baking conditions, improving the final hardness, chemical resistance, and low-temperature resistance of the coating film, thus compensating for the defects caused by low Tg.

[0017] Composite resin system: Two or more resins are blended together to complement each other's advantages (such as silicone-modified polyurethane, which has low-temperature elasticity, adhesion and weather resistance).

[0018] 2. Toughening / Flexibility Modifiers: Select special toughening agents or plasticizers that do not crystallize, migrate, or fail at extremely low temperatures to effectively lower the glass transition temperature of the resin and improve its flexibility. Avoid using ordinary plasticizers that become brittle or precipitate at low temperatures.

[0019] Add reactive liquid polymer toughening agents, such as hydroxyl-terminated / carboxyl-terminated butadiene-acrylonitrile rubber (CTBN), polyether / polyester polyols (long-chain flexible segments), and specialty acrylate rubbers. These toughening agents can chemically react with the main resin to form island structures or interpenetrating networks, effectively absorbing impact energy, significantly reducing the glass transition temperature (Tg) of the coating, and improving flexibility and crack resistance at extreme low temperatures.

[0020] Nanomaterials such as nano-silica (with surface modification), nano-calcium carbonate, and nano-clay are introduced to toughen the matrix. These nanoparticles disperse stress concentration points, deflect cracks, and inhibit propagation, thereby improving low-temperature toughness.

[0021] 3. Antifreeze plasticizing system: Select plasticizers with excellent migration resistance, volatility resistance, and low-temperature resistance, such as trimellitates, adipates (such as DOA), and polyester plasticizers. These plasticizers can insert into the polymer chains, increase chain segment mobility, significantly improve the flexibility of the coating at ultra-low temperatures, and prevent brittleness.

[0022] 4. Packing system: Extender fillers: Graphene-modified mica sheets, hydrophobically modified TiO2 nanoparticles, and multi-walled carbon nanotubes (MWCNTs) are selected as extender fillers, which can effectively extend the penetration path of corrosive media, improve the shielding and anti-corrosion effect, and enhance the physical and mechanical strength of the coating. Simultaneously, the particle size distribution and surface treatment of the fillers are optimized to reduce the negative impact on the coating's flexibility.

[0023] Pigments: Selected are titanium dioxide with excellent weather resistance and low-temperature resistant organic / inorganic color pastes. 5. Weather-resistant stabilization system: Sufficient amounts of UV absorbers, light stabilizers (HALS), and antioxidants are added to resist strong UV radiation and oxidative aging in frigid regions, ensuring long-term performance stability. These additives themselves must also possess good low-temperature compatibility.

[0024] 6. Antifreeze: Lowers the freezing point of water to prevent the coating from freezing and breaking during transportation and storage.

[0025] Common types: Ethylene glycols: ethylene glycol, propylene glycol, diethylene glycol butyl ether. They are highly effective and relatively inexpensive, but have high VOC content and are toxic (ethylene glycol).

[0026] Propylene glycol: Propylene glycol is more environmentally friendly and safer, with relatively low VOCs, making it a more commonly used and recommended choice.

[0027] Glycerin: Natural and environmentally friendly, but with high viscosity and relatively weak effects.

[0028] Novel low-VOC / VOC-free antifreeze agents: such as certain low molecular weight polyethers, specific salts, etc.

[0029] In this embodiment, an innovative epoxy-acrylic core-shell emulsion is used, achieving a performance balance through a "soft core, hard shell" structural design. The soft core portion has a low glass transition temperature (Tg), maintaining chain segment mobility in extreme low-temperature environments (below -40°C), ensuring the coating's flexibility and preventing embrittlement due to low temperatures. The hard shell portion has a high Tg, providing sufficient hardness, abrasion resistance, and stain resistance to the film-formed coating, compensating for the structural strength deficiencies of low-Tg resins. This "soft inside, hard outside" core-shell structure solves the contradiction of traditional coatings being "flexible at low temperatures but easily damaged at room temperature, hard at room temperature but easily cracked at low temperatures" at the microstructural level, achieving synergistic high and low temperature performance independently without relying on simple mixing of multiple resins.

[0030] Instead of conventional polyurethane, a fluorosilicone-modified polyurethane dispersion was specifically chosen, incorporating fluorine atoms and siloxane bonds through molecular design. The strong electronegativity of fluorine atoms forms a stable molecular structure, enhancing the coating's chemical inertness and weather resistance, while simultaneously reducing surface energy, increasing hydrophobicity, and minimizing corrosion caused by moisture adhesion at low temperatures. The siloxane bonds, on the other hand, possess excellent flexibility, effectively improving the low-temperature mobility of molecular chains and reducing the coating's brittleness at extreme low temperatures. This molecular-level modification endows the resin with the dual characteristics of "low-temperature flexibility + high weather resistance and corrosion resistance," enabling it to meet performance requirements at extreme low temperatures independently without relying on other additives.

[0031] To address the problem of coatings easily freezing and demulsifying during low-temperature transportation and storage, this invention abandons traditional toxic ethylene glycol-based antifreeze agents and preferentially uses propylene glycol as the antifreeze agent. The advantages of propylene glycol are: firstly, it has high safety, being non-toxic and odorless, avoiding harm to construction workers and the environment; secondly, it has stable antifreeze effects, effectively lowering the freezing point of the coating system, preventing freezing even below -40℃, and has good compatibility with resins and additives, without affecting the low-temperature flexibility and adhesion of the coating. This selection solves the antifreeze requirement while also considering environmental safety, achieving a stable antifreeze effect independently without relying on multiple antifreeze agents.

[0032] Example 7 Preparation process (1) Add 35-45 parts of fluorosilicone modified polyurethane dispersion, 10-15 parts of epoxy-acrylic core-shell emulsion, and 0-5 parts of liquid fluorocarbon resin to a dispersion vessel, and mix at low speed (500 rpm) for 5 minutes. (2) Add 5-10 parts of dioctyl adipate (DOA) and polyester polyol compound, and 10-20 parts of hydrogenated nitrile rubber nanoparticles, and mix at low speed (700 rpm) for 5 minutes; (3) Add 1-2 parts of dodecyl alcohol ester (TXIB) and 1-2 parts of ultraviolet absorber in sequence, and mix at low speed (700 rpm) for 5 minutes; (4) Slowly add the filler material: 10-20 parts of graphene-modified mica sheets, 3-7 parts of titanium dioxide, 5-10 parts of hydrophobically modified TiO2 nanoparticles, and 5-10 parts of multi-walled carbon nanotubes (MWCNTs), and mix at high speed (1000 rpm) for 20 minutes. (5) Reduce the rotation speed to 500 rpm, add 3-8 parts of propylene glycol and 2-4 parts of fumed silica, disperse for 10-15 minutes, and discharge.

[0033] Example 7 Preparation process 1. Add 40 parts of fluorosilicone modified polyurethane dispersion, 10 parts of epoxy-acrylic core-shell emulsion, and 5 parts of liquid fluorocarbon resin to a dispersion vessel, and mix at low speed (500 rpm) for 5 minutes; 2. Then add 5 parts of dioctyl adipate (DOA) and polyester polyol compound, and 10 parts of hydrogenated nitrile rubber nanoparticles, and mix at low speed (700 rpm) for 5 minutes; 3. Then add 2 parts of dodecyl alcohol ester (TXIB) and 2 parts of ultraviolet absorber in sequence, and mix at low speed (700 rpm) for 5 minutes; 4. Slowly add 10 parts of graphene modified mica sheets, 3 parts of titanium dioxide, 5 parts of hydrophobically modified TiO2 nanoparticles, and 5 parts of multi-walled carbon nanotubes (MWCNTs), and mix at high speed (1000 rpm) for 20 minutes; 5. Reduce the speed to 500 rpm, add 5 parts of propylene glycol and 3 parts of fumed silica, disperse for 10-15 minutes, and discharge. Test Results .

Claims

1. A waterproof and anti-corrosion coating for metal roofing that is resistant to extreme low temperatures, characterized in that: Composed of the following ingredients, by weight: Resin base material: including 35-45 parts of fluorosilicone modified polyurethane dispersion, 10-15 parts of epoxy-acrylic core-shell emulsion, 0-5 parts of liquid fluorocarbon resin, 5-10 parts of low temperature plasticizer 1: compounded with dioctyl adipate (DOA) and polyester polyol, and 10-20 parts of low temperature toughening agent 2: hydrogenated nitrile rubber nanoparticles. Functional additives include: low-temperature film-forming aids: 2-3 parts dodecyl alcohol ester (TXIB), 1-2 parts ultraviolet absorber, and 2-4 parts rheology modifier; antifreeze agents include 3-8 parts propylene glycol. Functional fillers: including extender fillers, 10-20 parts of graphene-modified mica sheets; 3-7 parts of pigment titanium dioxide; 5-10 parts of hydrophobically modified TiO2 nanoparticles; 5-10 parts of multi-walled carbon nanotubes (MWCNTs); The above ingredients are listed in parts by weight.

2. The waterproof and anti-corrosion coating for metal roofing resistant to extreme low temperatures according to claim 1, characterized in that, The ultraviolet absorber is a benzotriazole, and the rheology modifier is fumed silica.

3. The waterproof and anti-corrosion coating for metal roofing resistant to extreme low temperatures according to claim 1, characterized in that, The mass ratio of dioctyl adipate (DOA) to polyester polyol is 1:1 to 1:

2.

4. A method for preparing a waterproof and anti-corrosion coating for metal roofing resistant to extreme low temperatures as described in claim 1, characterized in that, Includes the following steps: (1) Add 35-45 parts of fluorosilicone modified polyurethane dispersion, 10-15 parts of epoxy-acrylic core-shell emulsion, and 0-5 parts of liquid fluorocarbon resin to the dispersion vessel, and stir at low speed for 500 rpm for 5 minutes. (2) Add 5-10 parts of dioctyl adipate (DOA) and polyester polyol compound, and 10-20 parts of hydrogenated nitrile rubber nanoparticles, and mix at low speed (700 rpm) for 5 minutes. (3) Add 2-3 parts of dodecyl alcohol ester TXIB and 1-2 parts of ultraviolet absorber in sequence, and mix at low speed of 700 rpm for 5 minutes; (4) Slowly add the filler material: 10-20 parts of graphene-modified mica sheets, 3-7 parts of titanium dioxide, 5-10 parts of hydrophobically modified TiO2 nanoparticles, and 5-10 parts of multi-walled carbon nanotubes (MWCNTs). Mix at 1000 rpm for 20 minutes. (5) Reduce the rotation speed to 500 rpm, add 3-8 parts of propylene glycol and 2-4 parts of fumed silica, disperse for 10-15 minutes, and discharge.