A solvent-free two-component polyurethane waterproof coating and a preparation method thereof

Abstract

This invention belongs to the field of waterproof coating technology, specifically relating to a solvent-free two-component polyurethane waterproof coating and its preparation method. The waterproof coating consists of two components, A and B. Component A is a low-viscosity polyether composition, and component B is a mixture of isocyanate prepolymers. Component A contains inorganic highly absorbent fillers, borate esters, and adhesion promoters, forming a triple moisture control mechanism that inhibits the reaction between isocyanate and moisture, solving the problems of foaming and adhesion in thick coatings. The surface drying time of this waterproof coating is 13-16 minutes, the complete drying time is 45-50 minutes, the tensile strength is 8.7-9.1 MPa, the elongation at break is 544-575%, the tear strength is 59-64 N / mm, and the adhesive strength is 2.96-3.11 MPa. It exhibits no foaming in thick coatings (at 23℃ and 50% humidity, 40℃ and 60% humidity, and 50℃ and 80% humidity), has good workability, and can be smoothly sprayed without diluent.

Description

Technical Field

[0001] This invention belongs to the field of waterproof coating technology, specifically relating to a solvent-free two-component polyurethane waterproof coating and its preparation method. Background Technology

[0002] Solvent-free two-component polyurethane waterproof coatings occupy an important position in the modern building waterproofing field due to their environmental advantages of extremely low odor and solvent-free pollution, as well as their excellent waterproof performance, weather resistance, and wide applicability. Composed of two components, A and B, they react rapidly after precise proportioning and thorough mixing to form a tough and elastic waterproof membrane.

[0003] In the formulation system, solvent-free two-component polyurethane waterproof coatings typically use polymeric polyols as component A and isocyanates as component B (which acts as a cross-linking and curing agent). The long-chain structure of the polymeric polyol can act as a "soft segment," giving the coating excellent elasticity; the urethane bonds formed by its reaction with isocyanates easily form hydrogen bonds, acting as a "hard segment" to enhance the mechanical strength of the polyurethane. This structure of "alternating soft and hard segments" gives the coating both high strength, high water resistance, and excellent flexibility.

[0004] However, this type of coating still faces two key problems in practical applications:

[0005] (1) Bubbling problem in thick coating: The isocyanate group (-NCO) in component B is very easy to react with moisture to generate urea and release CO2 under high temperature and high humidity environment, which leads to bubble defects after the coating is cured and formed into film, and this phenomenon is more serious when the coating is thick.

[0006] (2) Poor adhesion to high-humidity substrates: When coating on a high-humidity substrate, the isocyanate groups in component B are prone to react with the moisture on the substrate surface to form urea bonds. This substance will significantly weaken the adhesion between the coating and the substrate, affecting the durability of the waterproof effect.

[0007] While existing technologies and related patents attempt to address some of the problems, limitations remain. For example, patent CN112521849A improves the weather resistance of coatings by introducing weather-resistant raw materials, but fails to solve the problem of foaming caused by the reaction of isocyanates with moisture. Patent CN108329826A uses a mixture of anhydrous sodium sulfate and anhydrous magnesium sulfate to suppress foaming in thick coatings, but does not address the adhesion performance on high-humidity substrates. Therefore, developing a solvent-free two-component polyurethane waterproof coating that can simultaneously solve both "foaming in thick coatings" and "poor adhesion to high-humidity substrates" has become an urgent need in the industry. Summary of the Invention

[0008] To overcome the shortcomings of the prior art, this invention provides a solvent-free two-component polyurethane waterproof coating and its preparation method, achieving the dual goals of "thick coating without bubbles" and "high adhesion to high-humidity substrate surfaces", while ensuring that the coating has excellent mechanical properties and workability.

[0009] The technical solution of the present invention is as follows:

[0010] This invention provides a solvent-free two-component polyurethane waterproof coating, which is composed of two components, A and B, in a mass ratio of (1-5):1.

[0011] The raw material formulation of component A, by weight, is as follows: 48-70 parts polyether polyol, 5-10 parts inorganic filler, 1-4 parts borate ester, 3-6 parts crosslinking agent, 1-3 parts adhesion promoter, 0.1-0.4 parts catalyst, 0.1-0.6 parts antioxidant, 0.2-0.8 parts ultraviolet absorber, 0.5-1.3 parts dispersant, and 0.1-0.6 parts defoamer;

[0012] Component B is a mixture of isocyanate prepolymers, prepared by reacting polypropylene glycol with toluene diisocyanate.

[0013] Furthermore, the adhesion promoter is obtained through the following steps:

[0014] The neutralization degree of hydroxyethyl acrylate was adjusted with NaOH solution, and after cooling, potassium persulfate was added and stirred evenly. Polymerization was carried out under water bath conditions for 2-3 hours. After drying, tetrahydrofuran was added to dissolve the hydroxyethyl acrylate, and POCl3 was added dropwise. The mixture was reacted at 20-50℃ for 3-5 hours until it became gel-like. After soaking in methanol, the mixture was washed and dried. The mass ratio of hydroxyethyl acrylate, potassium persulfate, and POCl3 was 5:0.004-0.01:0.8-1.3.

[0015] The borate ester is tributyl borate, triethyl borate, or trimethyl borate.

[0016] Preferably, the crosslinking agent is polythiol.

[0017] The polyether polyol has a viscosity of 300~900 mPa·s at 25°C.

[0018] The molecular weight of polypropylene glycol is 300~700 g / mol, and the mass ratio of polypropylene glycol to toluene diisocyanate is 30~55:70.

[0019] The inorganic filler is sepiolite or diatomaceous earth, and its particle size is 0.3~4μm.

[0020] In addition, the raw material formulation of component A also includes pigments.

[0021] The present invention also provides a method for preparing the solvent-free two-component polyurethane waterproof coating, comprising the following steps:

[0022] Preparation of Component A:

[0023] After heating, the polyether polyol is dehydrated under vacuum and then cooled to room temperature. Dispersant, defoamer, antioxidant, UV absorber, catalyst, adhesion promoter, borate ester, and crosslinking agent are added in sequence and stirred evenly. The mixed material is dispersed, and inorganic filler is added and the dispersion is continued. Finally, the material is vacuumed and discharged to obtain component A.

[0024] Preparation of component B:

[0025] After heating, polypropylene glycol is dehydrated under vacuum and then cooled to 60-80°C. Toluene diisocyanate is added, and the mixture is stirred at a constant temperature before being cooled to room temperature. Finally, a vacuum is applied to obtain component B.

[0026] In addition, polyether polyols are heated at 110~130℃, and polyoxypropylene glycols are heated at 110~140℃.

[0027] Beneficial effects

[0028] The waterproof coating provided by this invention consists of two components, A and B. Component A is a low-viscosity polyether composition, and component B is a mixture of isocyanate prepolymers. In component A, inorganic strong water-absorbing fillers, borate esters, and adhesion promoters form a triple moisture control mechanism, inhibiting the reaction between isocyanate and moisture and solving the problems of foaming and adhesion in thick coatings. The surface drying time of this waterproof coating is 13-16 minutes, the complete drying time is 45-50 minutes, the tensile strength is 8.7-9.1 MPa, the elongation at break is 544-575%, the tear strength is 59-64 N / mm, the adhesive strength is 2.96-3.11 MPa, and there are no bubbles in thick coatings (at 23℃ and 50% humidity, 40℃ and 60% humidity, and 50℃ and 80% humidity). It has good workability and can be sprayed smoothly without diluent.

[0029] The adhesion promoter provided by this invention can simultaneously achieve the dual core functions of improving water absorption and adhesion. Firstly, by introducing functional monomers containing hydrophilic groups into the acrylic resin matrix, the promoter is endowed with excellent water absorption capacity, which can quickly absorb trace amounts of residual moisture on the substrate surface or within the coating system, avoiding problems such as coating blistering and peeling caused by moisture, and ensuring the integrity of the coating. Secondly, by controlling the degree of resin crosslinking through molecular design, the adhesion promoter can form strong chemical bonds with the active sites on the substrate surface, while enhancing the interfacial compatibility with subsequent coatings, and significantly improving the adhesion of the coating on various substrates such as metals and plastics. Detailed Implementation

[0030] The following examples are intended to illustrate the present invention, and not to further limit the invention.

[0031] Example 1

[0032] Step 1: Preparation of Component A

[0033] The raw material formula for component A is as follows, in parts by weight:

[0034] 60 parts of low-viscosity polyether polyol

[0035] 8 parts of inorganic strong water absorption filler

[0036] 3 parts of borate ester

[0037] 5 parts crosslinking agent

[0038] Adhesion promoter F1 2 parts

[0039] 0.3 parts catalyst

[0040] 0.5 parts antioxidant

[0041] 0.7 parts of ultraviolet absorber

[0042] 1.0 part of dispersant

[0043] 0.4 parts of defoamer

[0044] Two parts pigment.

[0045] Among them, the inorganic super absorbent filler maintains the extremely low moisture content in component A through its strong water absorption properties; during the curing process of the paint film, borate ester is a substance that is extremely easy to hydrolyze, and its reaction rate with moisture is very fast, which can inhibit the reaction of isocyanate groups with water vapor to generate carbon dioxide gas, thereby achieving the goal of no foaming under thick coating conditions; finally, when the paint liquid comes into contact with the substrate during paint spraying, the adhesion promoter can quickly react with the water vapor on the surface of the damp substrate, quickly adhere to the surface of the substrate, and at the same time avoid the negative problems of isocyanate groups reacting with the damp surface to generate urea bonds and carbon dioxide.

[0046] The low-viscosity polyether polyol has a viscosity of 600 mPa·s at 25°C.

[0047] The inorganic super absorbent filler is sepiolite, with a particle size of 1 μm;

[0048] The borate ester is tributyl borate;

[0049] The crosslinking agent is polythiol;

[0050] The specific preparation method of the adhesion promoter F1 is as follows: Add 500g of hydroxyethyl acrylate (HEA) to a beaker, adjust the neutralization degree of the solution to 50% using NaOH solution, and after the solution cools to room temperature, add 0.5g of potassium persulfate (KPS), stir evenly, and heat in an 80℃ water bath for 2-3 hours for polymerization. Place the mixture in an oven and dry at 60℃ to constant weight, then add 500ml of tetrahydrofuran to dissolve it, slowly add 100g of POCl3, and after the addition is complete, react at 20-50℃ for 3-5 hours. After a gel is formed, remove it, soak it in methanol for 12 hours, wash it 2-3 times with anhydrous ethanol, and then dry it in an oven at 60℃ to constant weight. Grind it and pass it through a 1mm sieve to obtain the prepared compound F1, which has both adhesion-enhancing and water-absorbing properties.

[0051] The catalyst is bismuth isooctanoate;

[0052] The antioxidant is antioxidant 1010;

[0053] The ultraviolet absorber is UV-531;

[0054] The dispersant is BYK-163;

[0055] The defoamer is BYK-057.

[0056] Among them, the borate esters and amino-containing silane adhesion promoters in the coating formulation are very easy to hydrolyze, so they can strongly inhibit the reaction of isocyanate groups with water vapor to generate carbon dioxide, thus effectively eliminating the blistering phenomenon of thick coatings. In addition, the substances after hydrolysis of borate esters and amino-containing silane adhesion promoters have very active reactive functional groups, which can react chemically with isocyanate groups, thereby having a positive effect on improving the mechanical properties of the coating film.

[0057] Furthermore, the self-made adhesion promoter F1 can simultaneously achieve the dual core functions of improving water absorption and adhesion. The specific beneficial effects are as follows: First, by introducing functional monomers containing hydrophilic groups into the acrylic resin matrix, the promoter is endowed with excellent water absorption capacity, which can quickly absorb trace amounts of residual moisture on the substrate surface or in the coating system, avoiding problems such as coating blistering and peeling caused by moisture, and ensuring the integrity of the coating; Second, by controlling the degree of resin crosslinking through molecular design, the adhesion promoter F1 can form a strong chemical bond with the active sites on the substrate surface, while enhancing the interfacial compatibility with subsequent coatings, and significantly improving the adhesion of the coating on various substrates such as metals and plastics.

[0058] Furthermore, the highly reactive polythiol crosslinking agent with a high degree of crosslinking functionality in the formulation greatly enhances the mechanical properties of the coating after curing, giving the film a more durable waterproof and aging-resistant performance. The low-viscosity polyether polyol, combined with additives, allows for smooth spraying without the need for diluents, improving workability and making it more environmentally friendly.

[0059] According to the specific formula of component A by weight, the low viscosity polyether polyol is first added to the mixing tank, heated to 120°C, and then vacuum dehydrated for 4 hours. After cooling to room temperature, the dispersant, defoamer, antioxidant, UV absorber, catalyst, adhesion promoter F1, borate ester, and crosslinking agent are added in sequence. After stirring evenly, the mixed material is transferred to a high-speed dispersion tank. Inorganic strong water-absorbing filler and pigment are added at a dispersion rate of 18,000 rpm. After high-speed dispersion for 110 minutes, the mixture is vacuumed for 2 hours to completely defoam. Component A is then discharged, sealed, and dried for storage.

[0060] Step 2, Preparation of Component B

[0061] Polypropylene glycol was added to a reactor equipped with a stirrer and a temperature sensor. The temperature was raised to 130°C, and after vacuum dehydration for 3 hours, the temperature was lowered to 70°C. Then, toluene diisocyanate was added, and after stirring at a constant temperature for 3 hours, the temperature was lowered to room temperature. After vacuum degassing for 2 hours, component B was obtained and stored under nitrogen protection.

[0062] The molecular weight of the polyoxypropylene glycol is 600 g / mol;

[0063] The mass ratio of polyoxypropylene glycol to toluene diisocyanate is 45:70.

[0064] It should be noted that, to ensure the performance of the coating, the purity of the isocyanate prepolymer must be guaranteed and the side reactions of toluene diisocyanate must be suppressed during the preparation of component B. To this end, a reaction vessel with a PLC control system is further employed, integrating a temperature sensor, a vacuum monitor, and a stirring speed controller. During the heating to 130℃, cooling to 70℃, and the 3-hour constant-temperature reaction, the system automatically adjusts the heating power and cooling water flow rate to avoid deviations from manual temperature control. During the 3-hour vacuum dehydration and 2-hour degassing processes, an automatic alarm is triggered and supplementary vacuum is applied if the vacuum level is abnormal. Furthermore, the feeding ratio of polypropylene glycol and toluene diisocyanate is precisely controlled by an electromagnetic flowmeter to achieve automatic feeding. After the reaction, a nitrogen-protected closed conveying pipeline is added to directly transport component B to the finished product storage tank, reducing air contact during transfer. A liquid level sensor is installed in the storage tank, automatically triggering the next batch production when the liquid level is low, adapting to the needs of industrial-scale production.

[0065] Example 2

[0066] Step 1: Preparation of Component A

[0067] The specific formula of component A is as follows, in parts by weight:

[0068] 50 parts of low viscosity polyether polyol

[0069] 5 parts of inorganic superabsorbent filler

[0070] 1 part of borate ester

[0071] 3 parts crosslinking agent

[0072] Adhesion promoter F1 1 part

[0073] 0.1 parts catalyst

[0074] Antioxidant 0.1 parts

[0075] 0.4 parts of ultraviolet absorber

[0076] 0.6 parts of dispersant

[0077] 0.2 parts of defoamer;

[0078] The low-viscosity polyether polyol has a viscosity of 300 mPa·s at 25°C.

[0079] The inorganic super absorbent filler is diatomaceous earth with a particle size of 0.3 μm;

[0080] The borate ester is triethyl borate;

[0081] The crosslinking agent is polythiol;

[0082] The specific preparation method of the adhesion promoter F1 is as follows: Add 500g of hydroxyethyl acrylate (HEA) to a beaker, adjust the neutralization degree of the solution to 50% using NaOH solution, and after the solution cools to room temperature, add 0.5g of potassium persulfate (KPS), stir evenly, and heat in an 80℃ water bath for 2-3 hours for polymerization. Place the mixture in an oven and dry at 60℃ to constant weight, then add 500ml of tetrahydrofuran to dissolve it, slowly add 100g of POCl3, and after the addition is complete, react at 20-50℃ for 3-5 hours. After a gel is formed, remove it, soak it in methanol for 12 hours, wash it 2-3 times with anhydrous ethanol, and then dry it in an oven at 60℃ to constant weight. Grind it and pass it through a 1mm sieve to obtain the prepared compound F1, which has both adhesion-enhancing and water-absorbing properties.

[0083] The catalyst is bismuth isooctanoate;

[0084] The antioxidant is antioxidant 1010;

[0085] The ultraviolet absorber is UV-531;

[0086] The dispersant is BYK-163;

[0087] The defoamer is BYK-057.

[0088] According to the specific formula of component A by weight, the low viscosity polyether polyol is first added to the mixing tank, heated to 110°C, and then vacuum dehydrated for 3 hours. After cooling to room temperature, the dispersant, defoamer, antioxidant, UV absorber, catalyst, adhesion promoter F1, borate ester, and crosslinking agent are added in sequence. After stirring evenly, the mixed material is transferred to a high-speed dispersion tank. Inorganic strong water-absorbing filler and pigment are added at a dispersion rate of 13,000 rpm. After high-speed dispersion for 80 minutes, the mixture is vacuum dehydrated for 1 hour to obtain component A, which is then sealed and dried for storage.

[0089] Step 2, Preparation of Component B

[0090] Polypropylene glycol was added to a reactor equipped with a stirrer and a temperature sensor. The temperature was raised to 110°C, and after dehydration under vacuum for 2 hours, the temperature was lowered to 60°C. Toluene diisocyanate was then added, and the mixture was stirred at a constant temperature for 2 hours. After cooling to room temperature, the mixture was degassed under vacuum for 1 hour to completely remove bubbles, and component B was obtained. The mixture was then stored under nitrogen protection.

[0091] The molecular weight of the polyoxypropylene glycol is 300 g / mol;

[0092] The mass ratio of polyoxypropylene glycol to toluene diisocyanate is 33:70.

[0093] Example 3

[0094] Step 1: Preparation of Component A

[0095] The specific formula of component A is as follows, in parts by weight:

[0096] 70 parts of low-viscosity polyether polyol

[0097] 10 parts of inorganic superabsorbent filler

[0098] 4 parts of borate ester

[0099] 6 parts crosslinking agent

[0100] Adhesion promoter F1 3 parts

[0101] 0.4 parts catalyst

[0102] Antioxidant 0.6 parts

[0103] 0.8 parts of ultraviolet absorber

[0104] 1.3 parts dispersant

[0105] 0.6 parts of defoamer

[0106] 5 parts pigment;

[0107] The low-viscosity polyether polyol has a viscosity of 850 mPa·s at 25°C.

[0108] The inorganic super absorbent filler is sepiolite, with a particle size of 4μm;

[0109] The borate ester is trimethyl borate;

[0110] The crosslinking agent is polythiol;

[0111] The specific preparation method of the adhesion promoter F1 is as follows: Add 500g of hydroxyethyl acrylate (HEA) to a beaker, adjust the neutralization degree of the solution to 50% using NaOH solution, and after the solution cools to room temperature, add 0.5g of potassium persulfate (KPS), stir evenly, and heat in an 80℃ water bath for 2-3 hours for polymerization. Place the mixture in an oven and dry at 60℃ to constant weight, then add 500ml of tetrahydrofuran to dissolve it, slowly add 100g of POCl3, and after the addition is complete, react at 20-50℃ for 3-5 hours. After a gel is formed, remove it, soak it in methanol for 12 hours, wash it 2-3 times with anhydrous ethanol, and then dry it in an oven at 60℃ to constant weight. Grind it and pass it through a 1mm sieve to obtain the prepared compound F1, which has both adhesion-enhancing and water-absorbing properties.

[0112] The catalyst is bismuth isooctanoate;

[0113] The antioxidant is antioxidant 1010;

[0114] The ultraviolet absorber is UV-531;

[0115] The dispersant is BYK-163;

[0116] The defoamer is BYK-057.

[0117] According to the specific formula of component A by weight, the low viscosity polyether polyol is first added to the mixing tank, heated to 130°C, and then vacuum dehydrated for 5 hours. After cooling to room temperature, the dispersant, defoamer, antioxidant, UV absorber, catalyst, adhesion promoter F1, borate ester, and crosslinking agent are added in sequence. After stirring evenly, the mixed material is transferred to a high-speed dispersion tank. Inorganic strong water-absorbing filler and pigment are added at a dispersion rate of 20,000 rpm. After high-speed dispersion for 130 minutes, vacuum degassing is carried out for 2.5 hours to completely degas the material. Component A is then discharged, sealed, and dried for storage.

[0118] Step 2, Preparation of Component B

[0119] Polypropylene glycol was added to a reactor equipped with a stirrer and a temperature sensor. The temperature was raised to 140°C, and after dehydration under vacuum for 3.5 hours, the temperature was lowered to 80°C. Toluene diisocyanate was then added, and the mixture was stirred at a constant temperature for 4 hours. After cooling to room temperature, the mixture was degassed under vacuum for 2.5 hours to completely remove bubbles, and then component B was obtained. The mixture was stored under nitrogen protection.

[0120] The molecular weight of the polyoxypropylene glycol is 700 g / mol;

[0121] The mass ratio of polyoxypropylene glycol to toluene diisocyanate is 55:70.

[0122] Comparative Example 1 (Borate-free)

[0123] Replace 3 parts of borate ester in component A with 3 parts of low viscosity polyether polyol, and the rest is the same as in Example 1.

[0124] Comparative Example 2 (without cross-linking agent)

[0125] Replace 5 parts of polythiol in component A with 5 parts of low-viscosity polyether polyol, and the rest is the same as in Example 1.

[0126] Comparative Example 3 (with adhesiveness promoter replaced)

[0127] Replace 2 parts of adhesion promoter F1 in component A with 2 parts of 3-dimethylaminoethylsilane, and the rest is the same as in Example 1.

[0128] Performance testing

[0129] The solvent-free two-component polyurethane waterproof coatings obtained in Examples 1, 2, and 3 and Comparative Examples 1, 2, and 3 were mixed with components A and B at a mass ratio of 1:1, sprayed, cured into films, and then tested for the following performance indicators:

[0130] Referring to GB / T19250-2013 and GB / T16777-2008, the following parameters were tested: surface drying time, complete drying time, tensile strength, elongation at break, tear strength, bond strength, impermeability, impact resistance, UV resistance, thick coating foaming, water immersion adhesion, and application performance.

[0131] The test data for the above indicators are shown in Table 1.

[0132] Table 1 Test data of various indicators for different waterproof coatings

[0133]

[0134] As can be seen from the data in Table 1, the surface drying time and actual drying time of Examples 1-3 are relatively short, the construction performance is good, and the mechanical strengths such as tensile strength, elongation at break, tear strength, adhesive strength and impact resistance are very excellent. The UV resistance and water impermeability are also good. Thick coatings do not bubble under different temperatures and humidity. It can be seen that the solvent-free two-component polyurethane waterproof coating provided by the present invention has the characteristics of no bubbles when thickly coated and good adhesion when coated on high humidity substrates.

[0135] Compared to Example 1, Comparative Example 1 without borate esters showed significantly prolonged surface drying time and complete drying time, and a substantial decrease in mechanical properties such as tensile strength, elongation at break, tear strength, and bond strength. In particular, the bond strength decreased drastically, UV resistance declined, and blistering of thick coatings was severe. This indicates that the addition of borate esters can promote rapid curing of the coating and has a very significant effect on improving the mechanical properties of the coating, especially the bond strength. In addition, borate esters can inhibit the reaction between isocyanate and water vapor, effectively suppressing the problem of blistering in thick coatings.

[0136] Compared with Example 1, no crosslinking agent was added in Comparative Example 2. The surface drying time and actual drying time of Comparative Example 2 were prolonged, and the mechanical strengths such as tensile strength, tear strength, adhesive strength and impact resistance decreased drastically. In particular, the tensile strength decreased extremely drastically, and the UV resistance also decreased significantly. In terms of thick coating foaming, there was obvious foaming problem under high temperature and high humidity conditions. This indicates that the crosslinking agent has a significant effect on improving the curing speed of the coating and has a very significant effect on improving the mechanical properties of the coating. At the same time, it also has a significant effect on improving the foaming problem of thick coating under high temperature and high humidity conditions.

[0137] Compared with Example 1, Comparative Example 3 did not contain an adhesion promoter. The surface drying time and actual drying time of Comparative Example 3 were prolonged, and the mechanical strengths such as tensile strength, elongation at break, tear strength, and impact resistance were significantly reduced. The decrease in adhesive strength was very drastic, and the blistering phenomenon of thick coating was also very serious. This indicates that the adhesion promoter mainly plays the role of improving adhesive strength and inhibiting blistering of thick coating.

[0138] In summary, the solvent-free two-component polyurethane waterproof coating obtained by this invention has a surface drying time of 13-16 min, a complete drying time of 45-50 min, a tensile strength of 8.7-9.1 MPa, an elongation at break of 544-575%, a tear strength of 59-64 N / mm, an adhesive strength of 2.96-3.11 MPa, and exhibits no foaming when applied thickly (at 23℃ and 50% humidity, 40℃ and 60% humidity, and 50℃ and 80% humidity). It also has good workability and can be smoothly sprayed without the addition of diluent.

[0139] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A solvent-free two-component polyurethane waterproof coating, characterized in that, The solvent-free two-component polyurethane waterproof coating consists of two components, A and B, in a mass ratio of (1-5):

1. The raw material formulation of component A, by weight, is as follows: 48-70 parts polyether polyol, 5-10 parts inorganic filler, 1-4 parts borate ester, 3-6 parts crosslinking agent, 1-3 parts adhesion promoter, 0.1-0.4 parts catalyst, 0.1-0.6 parts antioxidant, 0.2-0.8 parts ultraviolet absorber, 0.5-1.3 parts dispersant, and 0.1-0.6 parts defoamer; The adhesion promoter is obtained through the following steps: The neutralization degree of hydroxyethyl acrylate was adjusted with NaOH solution, and after cooling, potassium persulfate was added and stirred well. Polymerization was carried out under water bath conditions for 2-3 hours. After drying, tetrahydrofuran was added to dissolve the hydroxyethyl acrylate, and POCl3 was added dropwise. The mixture was reacted at 20-50℃ for 3-5 hours until it became gel-like. After soaking in methanol, the mixture was washed and dried. The mass ratio of hydroxyethyl acrylate, potassium persulfate, and POCl3 was 5:0.004-0.01:0.8-1.

3. The crosslinking agent is polythiol; Component B is a mixture of isocyanate prepolymers, prepared by reacting polypropylene glycol with toluene diisocyanate.

2. The solvent-free two-component polyurethane waterproof coating according to claim 1, characterized in that, The borate ester is tributyl borate, triethyl borate, or trimethyl borate.

3. The solvent-free two-component polyurethane waterproof coating according to claim 1, characterized in that, The polyether polyol has a viscosity of 300~900 mPa·s at 25°C.

4. The solvent-free two-component polyurethane waterproof coating according to claim 1, characterized in that, The molecular weight of polypropylene glycol is 300~700 g / mol, and the mass ratio of polypropylene glycol to toluene diisocyanate is 30~55:

70.

5. The solvent-free two-component polyurethane waterproof coating according to claim 1, characterized in that, The inorganic filler is sepiolite or diatomaceous earth, and its particle size is 0.3~4μm.

6. The solvent-free two-component polyurethane waterproof coating according to claim 1, characterized in that, Component A of the raw material formulation also includes pigments.

7. A method for preparing a solvent-free two-component polyurethane waterproof coating as described in claim 1, characterized in that, Includes the following steps: Preparation of Component A: After heating, the polyether polyol is dehydrated under vacuum and then cooled to room temperature. Dispersant, defoamer, antioxidant, UV absorber, catalyst, adhesion promoter, borate ester, and crosslinking agent are added in sequence and stirred evenly. The mixed material is dispersed, and inorganic filler is added and the dispersion is continued. Finally, the material is vacuumed and discharged to obtain component A. Preparation of component B: After heating, polypropylene glycol is dehydrated under vacuum and then cooled to 60-80°C. Toluene diisocyanate is added, and the mixture is stirred at a constant temperature before being cooled to room temperature. Finally, a vacuum is applied to obtain component B.

8. The preparation method according to claim 7, characterized in that, Polyether polyols are heated at 110~130℃, and polyoxypropylene glycols are heated at 110~140℃.

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