Polyurethane waterproof coating and preparation process thereof

Abstract

The invention relates to the technical field of waterproof coatings, in particular to a polyurethane waterproof coating and a preparation process thereof. The polyurethane waterproof coating is prepared from the following raw materials: toluene diisocynate, polyether polyol, chlorinated paraffin, talcum powder, a latent curing agent, self-repairing microcapsules and temperature-sensitive polymer nanoparticles. According to the self-repairing capsule, hexamethylene diisocyanate serves as a core material, the outer layer of the self-repairing capsule is wrapped with a polyurethane / nano-silicon dioxide hybrid wall material or a urea-formaldehyde resin wall material, and the temperature-sensitive polymer nanoparticles are poly N-isopropylacrylamide. The self-repairing microcapsules and the temperature-sensitive polymer nanoparticles are used, the self-repairing capacity and the capacity of adapting to different environmental conditions of a coating film are improved, when tiny cracks occur in the coating film, the microcapsules are broken to release a repairing agent, the cracks are automatically filled, the integrity of the coating is recovered, and the self-repairing performance of the coating film is improved. And the temperature-sensitive polymer nanoparticles can expand when the temperature rises to further promote the flowing and curing of the repairing agent, so that the service life of the coating film is prolonged, and the maintenance cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of waterproof coatings, and particularly relates to a polyurethane waterproof coating and a preparation process thereof. Background Art

[0002] Polyurethane waterproof coating is a waterproof coating obtained by reacting an excessive amount of isocyanate monomer with polyether polyol to form a polyurethane prepolymer containing residual -NCO groups, and then adding crosslinking agents, pigments and fillers, solvents, etc. for compounding. Its waterproof coating film has good extensibility and substrate adhesion, and is particularly suitable for construction on the surface of substrates with complex structures or non-planar shapes. Therefore, it is widely used in the waterproofing of projects such as roofs, basements, kitchens and bathrooms, storage pools, subways, bridges, parking lots, etc. At present, polyurethane waterproof coating has become the new type of polymer waterproof coating with the best performance and the largest consumption in the field of building waterproofing.

[0003] Polyurethane waterproof coatings are divided into coal tar type, asphalt type and polyether type polyurethane waterproof coatings according to different organic fillers; the commonly used polyurethane waterproof coatings are polyether type polyurethane waterproof coatings, which can be further divided into two-component and one-component polyurethane waterproof coatings according to the number of components. Due to the complex construction of two-component coatings, one-component polyurethane waterproof coatings are more commonly used in the industry at present. In order to improve the coating film quality, the industry has gradually adopted latent curing agents to replace the traditional wet curing or water curing systems. These latent curing agents can reduce the generation of bubbles and reduce the dependence on environmental humidity and temperature, thereby forming a more dense and flat coating film structure and enhancing the waterproof effect.

[0004] During the coating process and actual application, the coating is inevitably affected by external actions or internal stresses, resulting in defects such as scratch damage and microscopic pores, and the situation of anticorrosion failure is widespread. Therefore, it is usually necessary to regularly maintain the coating by means of surface treatment, manual paint repair, etc., resulting in high labor costs and the repair effect being difficult to meet the original performance requirements; nowadays, in the coating self-healing technology, common external aid type self-healing coatings include nano-container loading type, fiber tube network type, microcapsule filling type, etc., to achieve online repair of coating defects.

[0005] Patent CN106010188B discloses a self-healing polyurethane waterproof coating and a preparation method thereof. A microcapsule material is obtained by spray-drying a mixture of ethyl cellulose and oil-soluble polyurethane grouting liquid, and the core material of the microcapsule is polyurethane grouting liquid and the wall material is ethyl cellulose. By applying the gel technology and microcapsule technology to the waterproof coating, when the coating is applied to the concrete surface layer and the cracking degree of the base layer exceeds the extensibility of the coating, the coating will be torn, resulting in water leakage. After the coating cracks, the internal active materials are exposed, and under the action of water, it can automatically react quickly to generate reactants to repair the cracks, block the leakage channels, and at the same time repair the defects of the base concrete (mortar).

[0006] However, although ethyl cellulose as a wall material has good film-forming properties and solubility, it has problems of insufficient water resistance and mechanical strength. For example, in a high-humidity environment or when in contact with water for a long time, its structure may gradually absorb moisture and soften, resulting in the loss of integrity of the microcapsules, affecting the controlled release of active substances. The film formed by ethyl cellulose is relatively brittle and has poor adaptability under complex stress conditions. It is easily broken when subjected to slight physical impact or stress, unable to provide sufficient protection for the core material, leading to insufficient stability of the microcapsules. In addition, during the spray drying process, it is difficult to precisely control the size of the microcapsules, which may result in uneven particle size distribution, affecting its dispersion in the coating and the final performance. Therefore, the present invention provides a polyurethane waterproof coating and its preparation process to solve the above problems. Summary of the Invention

[0007] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a polyurethane waterproof coating and its preparation process.

[0008] A polyurethane waterproof coating includes a basic component, a functional additive, and an intermediate. By mass, the raw materials of the basic component include 4 - 14 parts of polyether diol, 14 - 34 parts of polyether triol, 6 - 26 parts of chlorinated paraffin, 15 - 30 parts of solvent, 28 - 45 parts of talcum powder, and 0.5 - 2 parts of pigment. The functional additive includes 0.5 - 1.2 parts of defoamer, 0.1 - 1.5 parts of dispersant, 0.01 - 0.03 parts of dryer, 0.8 - 1.5 parts of latent curing agent, and 0.3 - 0.6 parts of accelerator. The raw materials of the intermediate include 2 - 8 parts of toluene diisocyanate, 2 - 4.5 parts of self-healing microcapsules, and 1 - 2 parts of thermosensitive polymer nanoparticles.

[0009] Furthermore, the self-healing capsule uses hexamethylene diisocyanate as the core material, and the outer layer is wrapped with a polyurethane / nanosilica hybrid wall material or a urea-formaldehyde resin wall material. The self-healing capsule is prepared by an interfacial polymerization method and a sol-gel in-situ generation method or an interfacial polymerization method; The interfacial polymerization method and the sol-gel in-situ generation method are as follows: Dissolve hexamethylene diisocyanate in an organic solvent to form a uniform internal phase solution; dissolve tetraethyl orthosilicate in ethanol, add an acidic, basic, or acid-base composite catalyst, and perform an aging treatment to form a transparent sol solution; slowly add the internal phase solution to the sol solution containing a non-ionic surfactant, and perform high-speed shear stirring at 600 r / min for 30 min to form a stable water-in-oil emulsion; add a polyurethane prepolymer to the emulsion to cause a polymerization reaction at the oil-water interface, with the reaction temperature being 25 - 50 °C, and form a microcapsule wall material at the interface to obtain the self-healing capsule; The interfacial polymerization method is as follows: Dissolve hexamethylene diisocyanate in an organic solvent, and slowly stir at 40 - 50 °C to form a uniform internal phase solution; Add an emulsifier accounting for 3% of the mass of hexamethylene diisocyanate to deionized water, stir until fully dissolved, and adjust the pH value to 3.5 using an acid or a base to form an aqueous phase containing the emulsifier; Slowly add the internal phase solution to the aqueous phase containing the emulsifier, perform high-speed shear stirring at 600 r / min for 30 min, add a urea-formaldehyde resin prepolymer to the emulsion, and carry out a polymerization reaction at 25 - 50 °C. After the reaction is completed, fully cure to obtain self-healing microcapsules.

[0010] Further, the temperature-sensitive polymer nanoparticles are poly(N-isopropylacrylamide).

[0011] Further, the polyether diol is poly(propylene glycol), and the polyether triol is poly(propylene triol).

[0012] Further, the mass ratio of the polyether diol to the polyether triol is 3 - 4:6 - 7.

[0013] Further, the solvent is acetone or methyl ethyl ketone.

[0014] Further, the latent curing agent is an imine-type latent curing agent or an oxazolidine-type latent curing agent.

[0015] Further, the pigment is one or more of iron red, titanium dioxide, and chrome yellow.

[0016] Further, the defoaming agent is a silicone defoaming agent, the dispersant is a polycarboxylate dispersant, and the drier is a cobalt drier.

[0017] A preparation process of a polyurethane waterproof coating includes the following steps: Add the polyether diol, polyether triol, chlorinated paraffin, solvent, defoaming agent, and dispersant to a reaction kettle, mix and stir at a speed of 300 - 500 r / min at 80 - 90 °C for 1 - 2 h, add the self-healing microcapsules and temperature-sensitive polymer nanoparticles, stir and mix evenly, add talcum powder and pigment, continue to stir until fully dispersed, raise the temperature to 105 - 115 °C, increase the speed to 1000 - 1100 r / min, stir for 0.5 - 1 h to mix evenly, then carry out vacuum dehydration at 115 - 120 °C and (-0.095) - (-0.1 MPa) for 3 - 4 h, remove the vacuum, cool down to 80 - 85 °C, add toluene diisocyanate, stir and react at 300 - 400 r / min for 1 - 2 h, finally cool down to 50 °C, add the drier, latent curing agent, and accelerator, stir and mix evenly, cool down and discharge to obtain the polyurethane waterproof coating.

[0018] The beneficial effects achieved by the present invention are as follows: 1. The present invention uses self-repairing microcapsules and thermosensitive polymer nanoparticles to enhance the self-repairing ability of the coating and its ability to adapt to different environmental conditions. By embedding self-repairing microcapsules containing liquid polyurethane prepolymers, when tiny cracks appear in the coating, the microcapsules rupture to release the repair agent, automatically filling the cracks and restoring the integrity of the coating. At the same time, smart nanoparticles (poly (N-isopropylacrylamide)) that can respond to temperature changes are selected. These nanoparticles can expand when the temperature rises, further promoting the flow and curing of the repair agent, thereby extending the service life of the coating, reducing maintenance costs, and improving the durability and stability of the coating in complex environments.

[0019] 2. The self-repairing capsule of the present invention uses hexamethylene diisocyanate as the core material and is wrapped inside the shell material. When the coating is damaged, it is released and reacts with water or moisture in the air to generate polyurethane substances, which fill the crack defects and achieve local self-healing effects. The shell material is polyurethane / nano-silica hybrid material or stage A urea-formaldehyde resin, which has a uniform and dense structure, ensures the high sealing and thermal stability of the microcapsules, and enhances the self-repairing ability of the polyurethane waterproof coating. In addition, urea-formaldehyde resin has good water resistance. After nano-silica and polyurethane prepolymer are tightly combined, they can form an effective barrier at the interface, thereby enhancing the water resistance of the wall material and preventing the microcapsules from absorbing moisture and softening in a high humidity environment.

[0020] 3. The present invention adopts thermosensitive polymer nanoparticles, which can respond to environmental changes and provide an additional protective layer to prevent the coating from being damaged due to temperature fluctuations, thereby improving the overall performance of the coating and ensuring its long-term stability and reliability in complex environments. In addition, the polyurethane / nano-silica hybrid wall material combines the elasticity and chemical resistance of polyurethane with the mechanical strength and stability of nano-silica, thereby further enhancing the comprehensive performance of the microcapsules. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a flow chart of the preparation process of the polyurethane waterproof coating used in Examples 1 to 3 of the present invention; Figure 2 The tensile properties test results of the polyurethane waterproof coatings prepared in Examples 1-3 and Comparative Examples 1-2 of the present invention are shown in FIG. Figure 3 The surface drying time, actual drying time, solid content and coating viscosity test results of the polyurethane waterproof coatings prepared in Examples 1-3 of the present invention and Comparative Examples 1-2; Figure 4 These are the test results of water absorption, leveling, hardness, water impermeability, and UV aging performance of the polyurethane waterproof coatings prepared in Examples 1-3 of the present invention and Comparative Examples 1-2. DETAILED DESCRIPTION

[0022] The present invention is further described in detail below in conjunction with specific embodiments.

[0023] In the following embodiments, the self-healing capsule is made of hexamethylene diisocyanate as the core material, and the outer layer is wrapped with a polyurethane / nano-silica hybrid wall material or a urea-formaldehyde resin wall material. The self-healing capsule is prepared by an interfacial polymerization method and a sol-gel in-situ generation method or an interfacial polymerization method; the thermosensitive polymer nanoparticles are poly-N-isopropylacrylamide; the polyether diol is polyoxypropylene diol, the polyether triol is polyoxypropylene triol, and the mass ratio of the polyether diol to the polyether triol is 3-4:6-7; the latent curing agent is an imine-type latent curing agent or an oxazolidine-type latent curing agent, the imine-type latent curing agent uses hexamethylenetetramine (HMTA), and the oxazolidine-type latent curing agent uses 2-ethyl-4-methylimidazole (EMIM); the mesh size of the talc is 2000 mesh; the defoaming agent is BYK-054, a silicone defoaming agent of BYK Chemical, the dispersant is a polycarboxylate dispersant F108, and the drying agent is a cobalt drying agent T-22 of Dow Chemical.

[0024] The interfacial polymerization method and the sol-gel in-situ generation method are as follows: dissolve hexamethylene diisocyanate in an organic solvent (such as toluene, dichloromethane) to form a uniform internal phase solution; dissolve tetraethyl orthosilicate in ethanol, add an acidic, alkaline or acid-base composite catalyst, and age to form a transparent sol solution; slowly add the internal phase solution to a sol solution containing a non-ionic surfactant (such as OP-10), and stir at a high speed of 600r / min for 30 minutes to form a stable oil-in-water emulsion; add a polyurethane prepolymer to the emulsion to cause a polymerization reaction at the oil-water interface. The reaction temperature is 35°C, and a microcapsule wall material is formed on the interface to obtain a self-healing capsule.

[0025] The interfacial polymerization method is as follows: hexamethylene diisocyanate is dissolved in an organic solvent, and slowly stirred at 40°C to form a uniform internal phase solution; an emulsifier (such as OP-10) of 3% by mass of hexamethylene diisocyanate is added to deionized water, and stirred to fully dissolve, and the pH value is adjusted to 3.5 with an acid or base to form an aqueous phase containing the emulsifier; the internal phase solution is slowly added to the aqueous phase containing the emulsifier, and high-speed shear stirring is performed at 600 r / min for 30 minutes, and urea-formaldehyde resin prepolymer is added to the emulsion (prepared by mixing urea and formaldehyde in a molar ratio of 1:1.5-3, pre-condensing at a pH value of 3.0-3.5 and 40-50°C, and heating to 70-80°C for further condensation), and a polymerization reaction is carried out at 35°C. After the reaction is completed, it is completely cured to obtain self-healing microcapsules.

[0026] After preparing the self-healing microcapsules by the above two methods, centrifuge at 3000 - 5000 rpm for 15 - 30 minutes to separate the self-healing microcapsules from the emulsion. After washing with deionized water, place them in a vacuum drying oven and dry at 40 - 60 °C to obtain the final self-healing microcapsule powder.

[0027] Example 1: A polyurethane waterproof coating, comprising a base component, a functional additive, and an intermediate. By mass, the raw materials of the base component include 9 parts of polyether diol, 21 parts of polyether triol, 16 parts of chlorinated paraffin, 22 parts of solvent (acetone), 36 parts of talcum powder, and 1.2 parts of pigment (iron oxide red). The functional additives include 0.8 part of defoamer, 0.8 part of dispersant, 0.02 part of dryer, 1.2 parts of latent curing agent (hexamethylenetetramine), and 0.4 part of accelerator. The raw materials of the intermediate include 5 parts of toluene diisocyanate, 3.2 parts of self-healing microcapsules, and 1.5 parts of thermosensitive polymer nanoparticles; A preparation process of a polyurethane waterproof coating, as Figure 1 shown, includes the following steps: (1) Premixing stage: Add polyether diol, polyether triol, chlorinated paraffin, solvent, defoamer, and dispersant into a reaction kettle, and mix and stir at a speed of 300 r / min at 85 °C for 1 h; (2) Adding microcapsules and nanoparticles: Add self-healing microcapsules and thermosensitive polymer nanoparticles, and stir and mix evenly; (3) Adding pigments and fillers: Add talcum powder and iron oxide red, and continue to stir until completely dispersed; (4) High-temperature and high-shear mixing: Raise the temperature to 110 °C, increase the speed to 1000 r / min, and stir for 0.5 h; (5) Vacuum dehydration: Under the conditions of 115 °C and -0.098 MPa, vacuum dehydrate for 3.5 h; (6) Toluene diisocyanate reaction: Remove the vacuum, cool down to 82 °C, add toluene diisocyanate, and stir and react at 350 r / min for 1.5 h; (7) Final formulation: Finally, cool down to 50 °C, add dryer, latent curing agent, and accelerator, stir and mix evenly, cool down and discharge to obtain the polyurethane waterproof coating.

[0028] Example 2: A polyurethane waterproof coating, comprising a base component, functional additives, and an intermediate. By mass, the raw materials of the base component include 10 parts of polyether diol, 24 parts of polyether triol, 18 parts of chlorinated paraffin, 25 parts of solvent (methyl ethyl ketone), 40 parts of talcum powder, and 1.5 parts of pigment (titanium dioxide). The functional additives include 1 part of defoamer, 1.2 parts of dispersant, 0.025 parts of dryer, 1.4 parts of latent curing agent (2-ethyl-4-methylimidazole), and 0.5 parts of accelerator. The raw materials of the intermediate include 6 parts of toluene diisocyanate, 3.7 parts of self-healing microcapsules, and 1.8 parts of thermosensitive polymer nanoparticles; A preparation process of a polyurethane waterproof coating, as Figure 1 shown, comprises the following steps: (1) Premixing stage: Add polyether diol, polyether triol, chlorinated paraffin, solvent, defoamer, and dispersant into a reaction kettle, and mix and stir at a speed of 400 r / min at 88 °C for 1.5 h; (2) Adding microcapsules and nanoparticles: Add self-healing microcapsules and thermosensitive polymer nanoparticles, and stir and mix evenly; (3) Adding pigments and fillers: Add talcum powder and titanium dioxide, and continue to stir until completely dispersed; (4) High-temperature and high-shear mixing: Raise the temperature to 112 °C, increase the speed to 1050 r / min, and stir for 0.75 h; (5) Vacuum dehydration: Carry out vacuum dehydration at 118 °C and -0.095 MPa for 3 h; (6) Reaction with toluene diisocyanate: Remove the vacuum, cool down to 83 °C, add toluene diisocyanate, and stir and react at 380 r / min for 1.2 h; (7) Final formulation: Finally, cool down to 50 °C, add dryer, latent curing agent, and accelerator, stir and mix evenly, cool down and discharge to obtain the polyurethane waterproof coating.

[0029] Example 3: A polyurethane waterproof coating, comprising a base component, functional additives, and an intermediate. By mass, the raw materials of the base component include 12 parts of polyether diol, 30 parts of polyether triol, 20 parts of chlorinated paraffin, 28 parts of solvent (acetone), 42 parts of talcum powder, and 1.8 parts of pigment (iron oxide red). The functional additives include 1.1 parts of defoamer, 1.4 parts of dispersant, 0.028 parts of dryer, 1.3 parts of latent curing agent (hexamethylenetetramine), and 0.55 parts of accelerator. The raw materials of the intermediate include 7 parts of toluene diisocyanate, 4.3 parts of self-healing microcapsules, and 1.9 parts of thermosensitive polymer nanoparticles; A preparation process of a polyurethane waterproof coating, as Figure 1 shown, comprises the following steps: (1) Premixing stage: Add polyether diol, polyether triol, chlorinated paraffin, solvent, defoamer and dispersant into the reaction kettle, and mix and stir at a speed of 450 r / min at 90 °C for 2 h; (2) Adding microcapsules and nanoparticles: Add self-healing microcapsules and thermosensitive polymer nanoparticles, and stir and mix evenly; (3) Adding pigments and fillers: Add talcum powder and iron oxide red, and continue to stir until completely dispersed; (4) High-temperature and high-shear mixing: Raise the temperature to 115 °C, increase the speed to 1100 r / min, and stir for 1 h; (5) Vacuum dehydration: Dehydrate under vacuum at 120 °C and -0.1 MPa for 4 h; (6) Toluene diisocyanate reaction: Remove the vacuum, cool down to 85 °C, add toluene diisocyanate, and stir and react at 400 r / min for 2 h; (7) Final formulation: Finally, cool down to 50 °C, add driers, latent curing agents and accelerators, stir and mix evenly, cool down and discharge to obtain polyurethane waterproof coating.

[0030] Comparative Example 1: Compared with Example 1, self-healing microcapsules are not used; A polyurethane waterproof coating, comprising the following raw materials in parts by mass: 8.2 parts of toluene diisocyanate, 9 parts of polyether diol, 24 parts of polyether triol, 16 parts of chlorinated paraffin, 22 parts of solvent, 0.8 part of defoamer, 0.8 part of dispersant, 0.02 part of drier, 36 parts of talcum powder, 1.2 parts of iron oxide red, 1.2 parts of latent curing agent (hexamethylenetetramine HMTA), 0.4 part of accelerator, 1.5 parts of thermosensitive polymer nanoparticles; A preparation process of a polyurethane waterproof coating, comprising the following steps: (1) Premixing stage: Add polyether diol, polyether triol, chlorinated paraffin, solvent, defoamer and dispersant into the reaction kettle, and mix and stir at a speed of 300 r / min at 85 °C for 1 h; (2) Adding nanoparticles and pigments and fillers: Add thermosensitive polymer nanoparticles, stir and mix evenly, add talcum powder and iron oxide red, and continue to stir until completely dispersed; (3) High-temperature and high-shear mixing: Raise the temperature to 110 °C, increase the speed to 1000 r / min, and stir for 0.5 h; (4) Vacuum dehydration: Dehydrate under vacuum at 115 °C and -0.098 MPa for 3.5 h; (5) Toluene diisocyanate reaction: Remove the vacuum, cool down to 82 °C, add toluene diisocyanate, and stir and react at 350 r / min for 1.5 h; (6) Final blending: Finally, cool down to 50 °C, add driers, latent curing agents and accelerators, stir and mix evenly, cool down and discharge to obtain polyurethane waterproof coating.

[0031] Comparative Example 2: Compared with Example 1, without using thermosensitive polymer nanoparticles; a polyurethane waterproof coating, comprising the following raw materials in parts by mass: toluene diisocyanate 6.5 parts, polyether diol 9 parts, polyether triol 24 parts, chlorinated paraffin 16 parts, solvent 22 parts, defoamer 0.8 parts, dispersant 0.8 parts, drier 0.02 parts, talcum powder 36 parts, iron oxide red 1.2 parts, latent curing agent 1.2 parts (hexamethylenetetramine HMTA), accelerator 0.4 parts, self-healing microcapsules 3.2 parts; A preparation process of a polyurethane waterproof coating, comprising the following steps: (1) Premixing stage: Add polyether diol, polyether triol, chlorinated paraffin, solvent, defoamer and dispersant into a reaction kettle, mix and stir at 300 r / min at 85 °C for 1 h; (2) Adding microcapsules: Add self-healing microcapsules and stir and mix evenly; (3) Adding pigment and filler: Add talcum powder and iron oxide red and continue to stir until completely dispersed; (4) High-temperature and high-shear mixing: Heat up to 110 °C, increase the rotation speed to 1000 r / min and stir for 0.5 h; (5) Vacuum dehydration: Carry out vacuum dehydration for 3.5 h under the conditions of 115 °C and -0.098 MPa; (6) Reaction with toluene diisocyanate: Remove the vacuum, cool down to 82 °C, add toluene diisocyanate, and stir and react at 350 r / min for 1.5 h; (7) Final blending: Finally, cool down to 50 °C, add driers, latent curing agents and accelerators, stir and mix evenly, cool down and discharge to obtain polyurethane waterproof coating.

[0032] For the polyurethane waterproof coatings of Examples 1-3 and Comparative Examples 1-2, they can be coated three times after discharging. The final film thickness is 1.5 mm ± 0.2 mm. After coating, gently scrape off the surface bubbles with paper after 5 min. Cure for 96 h under standard experimental conditions, then turn the film over and continue to cure for 72 h under the same conditions. When pouring the coating into the mold, avoid pouring it along the cup wall in a folded manner. After the film is thoroughly dry, conduct relevant performance tests after 7 days of curing.

[0033] Performance test: Conduct film tensile performance, surface drying time, through drying time, solid content, coating viscosity, water absorption rate, leveling property, hardness, water impermeability, and ultraviolet aging performance tests on the polyurethane waterproof coatings prepared in Examples 1-3 and Comparative Examples 1-2; 1. Tensile properties of the coating film: According to GB / T 528-2009 "Rubber, vulcanized or thermoplastic - Determination of tensile stress - strain properties", dumbbell - shaped specimens (usually type D) with a thickness of about 2 mm are prepared according to the standard requirements. The specimens are placed in a standard environmental condition (temperature 23 ± 2 °C, relative humidity 50 ± 5%) for at least 24 hours. Using an electronic universal material testing machine, the clamp spacing is set to 50 mm, and the tensile speed is 500 mm / min. Record the tensile strength (MPa) and elongation at break (%).

[0034] 2. Surface - drying time and through - drying time: According to GB / T 1728-2007 "Testing methods for drying time of film, putty film", the coating is evenly applied on a glass plate to form a wet film with a thickness of about 1 mm. Gently touch the surface of the coating film with a finger, and record the time when it no longer sticks to the finger as the surface - drying time. Use a sharp blade to cut the coating film, observe whether the edge of the cut is sticky, and record the time when it is completely dry and non - sticky as the through - drying time. The test is carried out under standard environmental conditions (temperature 23 ± 2 °C, relative humidity 50 ± 5%).

[0035] 3. Solids content: According to GB / T 1725-2007 "Paints, varnishes and plastics - Determination of non - volatile matter content", take an appropriate amount of coating (about 1 g) and put it into an aluminum foil dish with a known weight. Place the sample in an oven and bake it at 105 ± 2 °C for 2 hours. Take out the sample, put it in a desiccator and cool it to room temperature, then weigh it. Calculate: Solids content (%)=(weight after baking / weight before baking)×100.

[0036] 4. Coating viscosity: According to GB / T 1723-1993 "Testing methods for coating viscosity - Stormer viscometer method", use a Stormer viscometer to ensure that the instrument is accurately calibrated. After stirring the coating evenly, pour it into the viscometer cup and conduct the test under standard environmental conditions (temperature 23 ± 2 °C). Read and record the viscosity value (KU unit).

[0037] 5. Water absorption rate: According to GB / T 16777-2008 "Test methods for building waterproof coatings", apply the coating on a glass plate to form a coating film with a thickness of about 1.5 mm, and place it in a standard environment to cure for 7 days. Cut the specimen into an appropriate size (100 cm²), weigh the initial weight, completely immerse the specimen in distilled water, keep the water surface higher than the specimen surface, soak for 24 hours, take out the specimen, blot the surface moisture with filter paper, and immediately weigh it. Calculate: Water absorption rate (%)=[(weight after soaking - initial weight) / initial weight]×100.

[0038] 6. Levelling property: In accordance with GB / T 6753.1-2007 "Paints and varnishes - Determination of levelling property", the coating is evenly applied on a glass plate to form a wet film with a thickness of about 100 μm, and placed for a period of time (1 hour) under standard environmental conditions (temperature 23 ± 2 °C, relative humidity 50 ± 5%). Observe the flatness of the coating film surface and score according to the surface flatness (grade 1 is the worst, grade 5 is the best).

[0039] 7. Hardness: In accordance with GB / T 6739-2006 "Paints and varnishes - Determination of pencil hardness", the coating is applied on a glass plate to form a coating film with a thickness of about 1 mm, placed in the standard environment for curing for 7 days. Use a pencil hardness tester, select pencils with different hardnesses (from 6B to 6H), and conduct tests under standard environmental conditions (temperature 23 ± 2 °C, relative humidity 50 ± 5%). Record the hardness grade of the hardest pencil that can scratch the coating film.

[0040] 8. Water impermeability: In accordance with GB / T 16777-2008 "Test methods for building waterproof coatings", the coating is applied in a prefabricated mold to form a coating film with a thickness of about 1.5 mm, placed in the standard environment for curing for 7 days. Install the specimen on a water impermeability tester, apply a water pressure (0.3 MPa), maintain the pressure for 30 minutes, check whether there is water seepage on the back of the specimen, and record the results (pass / fail).

[0041] 9. UV aging performance: In accordance with GB / T 16422.2-1999 "Plastics - Methods of exposure to laboratory light sources - Part 2: Xenon-arc lamps", the coating is applied on a glass plate to form a coating film with a thickness of about 1.5 mm, placed in the standard environment for curing for 7 days. Use a xenon-arc lamp aging chamber, set the light cycle (102 minutes of light + 18 minutes of spraying), the light intensity is 0.35 W / m 2 @340 nm, the blackboard temperature is 65 ± 3 °C, the relative humidity is 50 ± 5%, the total irradiation time is 1000 hours. Regularly take out the specimens, evaluate their appearance changes (such as color, gloss, cracks, etc.), and record the results.

[0042] The performance test results of the polyurethane waterproof coatings in Examples 1-3 and Comparative Examples 1-2 are as Figures 2 - 4 shown.

[0043] The above examples are only illustrative of the principles and effects of the present invention, and are not used to limit the present invention. Any person familiar with this technology can modify or change the above examples without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A polyurethane waterproof coating, characterized in that, It includes basic components, functional additives and intermediates. Calculated by weight, the basic component raw materials include 4-14 parts of polyether diol, 14-34 parts of polyether triol, 6-26 parts of chlorinated paraffin, 15-30 parts of solvent, 28-45 parts of talc, and 0.5-2 parts of pigment; the functional additives include 0.5-1.2 parts of defoamer, 0.1-1.5 parts of dispersant, 0.01-0.03 parts of drying agent, 0.8-1.5 parts of latent curing agent, and 0.3-0.6 parts of accelerator; the intermediate raw materials include 2-8 parts of toluene diisocyanate, 2-4.5 parts of self-healing microcapsules, and 1-2 parts of thermosensitive polymer nanoparticles.

2. The polyurethane waterproof coating according to claim 1, wherein The self-repairing capsule is made of hexamethylene diisocyanate as the core material, and the outer layer is wrapped with polyurethane / nano-silica hybrid wall material or urea-formaldehyde resin wall material. The self-repairing capsule is prepared by interfacial polymerization and sol-gel in-situ generation method or interfacial polymerization method; The interfacial polymerization method and the sol-gel in-situ generation method are as follows: dissolving hexamethylene diisocyanate in an organic solvent to form a uniform internal phase solution; dissolving tetraethyl orthosilicate in ethanol, adding an acidic, alkaline or acid-base composite catalyst, and performing an aging treatment to form a transparent sol solution; The internal phase solution is slowly added to the sol solution containing a nonionic surfactant, and stirred at a high speed of 600 r / min for 30 minutes to form a stable oil-in-water emulsion; a polyurethane prepolymer is added to the emulsion to cause a polymerization reaction at the oil-water interface, and the reaction temperature is 25-50°C to form a microcapsule wall material on the interface to obtain a self-repairing capsule; The interfacial polymerization method comprises the following steps: dissolving hexamethylene diisocyanate in an organic solvent, slowly stirring at 40-50° C. to form a uniform inner phase solution; adding an emulsifier of 3% by mass of hexamethylene diisocyanate to deionized water, stirring to fully dissolve, adjusting the pH value to 3.5 with an acid or alkali to form an aqueous phase containing the emulsifier; slowly adding the inner phase solution to the aqueous phase containing the emulsifier, stirring at a high speed of 600 r / min for 30 minutes, adding a urea-formaldehyde resin prepolymer to the emulsion, performing a polymerization reaction at 25-50° C., and completely curing after the reaction is completed to obtain a self-repairing microcapsule.

3. A polyurethane waterproof coating according to claim 1, characterized in that, The temperature-sensitive polymer nanoparticles are poly-N-isopropylacrylamide.

4. A polyurethane waterproof coating according to claim 1, characterized in that, The polyether diol is polyoxypropylene diol, and the polyether triol is polyoxypropylene triol.

5. A polyurethane waterproof coating according to claim 1, characterized in that, The mass ratio of the polyether diol to the polyether triol is 3-4:6-7.

6. A polyurethane waterproof coating according to claim 1, wherein, The solvent is acetone or methyl ethyl ketone.

7. A polyurethane waterproof coating according to claim 1, characterized in that, The latent curing agent is an imine type latent curing agent or an oxazolidine type latent curing agent.

8. A polyurethane waterproof coating according to claim 1, characterized in that, The pigment is one or more of iron oxide red, titanium dioxide and chrome yellow.

9. A polyurethane waterproof coating according to claim 1, characterized in that, The defoamer is an organosilicon defoamer, the dispersant is a polycarboxylate dispersant, and the drier is a cobalt drier.

10. The preparation process of the polyurethane waterproof coating according to any one of claims 1-9, characterized in that, The following steps are involved: Add polyether diol, polyether triol, chlorinated paraffin, solvent, defoamer and dispersant into a reaction kettle, mix and stir at a speed of 300 - 500 r / min at 80 - 90 °C for 1 - 2 h, add self-healing microcapsules and thermosensitive polymer nanoparticles, stir and mix evenly, add talcum powder and pigment, continue to stir until completely dispersed, raise the temperature to 105 - 115 °C, increase the speed to 1000 - 1100 r / min, stir for 0.5 - 1 h to mix evenly, then carry out vacuum dehydration at 115 - 120 °C and (-0.095) - (-0.1 MPa) for 3 - 4 h, then remove the vacuum, cool down to 80 - 85 °C, add toluene diisocyanate, stir and react at 300 - 400 r / min for 1 - 2 h, finally cool down to 50 °C, add drier, latent curing agent and accelerator, stir and mix evenly, cool down and discharge to obtain polyurethane waterproof coating.

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