Waterproof coating

Abstract

The invention discloses a waterproof coating which comprises the following raw materials: polyol, polyisocyanate, a filler, a latent curing agent, nano silicon dioxide aerogel and a modifier, and the modifier is prepared by reacting compounds as shown in a formula (I) and a formula (II); r1 is C1-10 linear alkyl, and n is greater than or equal to 1; r1 and R2 are independently C1-10 alkyl groups, R2 and R3 are independently C1-10 alkyl groups, R4 is C1-10 alkyl groups or C1-10 alkoxy groups, and a is selected from 1-10; the latent curing agent is prepared through a reaction, R5 is selected from C3-10 alkyl or fluorine-substituted C3-10 alkyl, R6 is selected from C1-10 alkyl, b is selected from 0-10, the sum of the number of carbon atoms of R6 and b is larger than or equal to 8, and the porosity of the nano-silica aerogel is larger than 90%; the waterproof coating disclosed by the invention is extremely low in odor, good in storage stability, good in waterproof durability, excellent in film flexibility, excellent in mechanical property and moderate in thick coating curing speed.

Description

[0001] The present application is a divisional application of the Chinese Invention Patent Application No. 2023115349866, filed on November 17, 2023, entitled "Single-component polyurethane waterproof coating and preparation method thereof". TECHNICAL FIELD

[0002] The present application relates to the field of waterproof coating, in particular to a waterproof coating. BACKGROUND

[0003] The single-component polyurethane waterproof coating is prepared by adding isocyanate, polyether and other isocyanate-containing prepolymer through addition polymerization reaction, and adding catalyst, anhydrous auxiliary agent, anhydrous filler, solvent and other materials through mixing process.

[0004] At present, in order to improve the flexibility of the single-component polyurethane waterproof coating, a plasticizer is usually added to improve the flexibility of the coating. However, the added plasticizer may migrate during application, which increases the brittleness of the coating after migration of the plasticizer. In addition, migration of the plasticizer also causes pollution or damage to the surface of the substrate, thereby causing the waterproof film to fall off from the substrate, affecting the waterproof durability, and reducing the performance and service life of the polyurethane waterproof coating. At the same time, the traditional single-component polyurethane waterproof coating is cured into a film by the reaction of the prepolymer containing NCO end groups with moisture in the air. During the curing reaction, CO2 is released. Therefore, the traditional single-component polyurethane waterproof coating is easily affected by the humidity of the construction environment during construction, which leads to the problems of thick coating, slow curing, and the occurrence of bubbles and pinholes in the cured coating film, which seriously affects the performance and construction quality of the single-component polyurethane waterproof coating. In order to solve the problems of bubbles and pinholes, a certain amount of latent curing agent is usually added to the polyurethane coating. The latent curing agent will react with the moisture in the air to generate amino or hydroxyl groups at a faster speed, and the generated amino or hydroxyl groups will react with the isocyanate groups to generate cross-linking and curing. In this process, no carbon dioxide is generated, thereby eliminating the generation of bubbles and pinholes. However, with the increase of the amount of the added latent curing agent, the storage stability of the single-component polyurethane waterproof coating is significantly reduced. In addition, many known latent curing agents usually have a strong odor and can easily cause harm to the body. SUMMARY

[0005] The purpose of the present application is to overcome one or more deficiencies in the prior art, and to provide an improved single-component polyurethane waterproof coating, which overcomes the problems of adding a plasticizer and a conventional latent curing agent in the prior art. The coating has a low odor, good flexibility of the film layer, and good storage stability.

[0006] The present application also provides a preparation method of the single-component polyurethane waterproof coating.

[0007] To achieve the above object, one technical solution adopted by the present application is:

[0008] A single-component polyurethane waterproof coating, raw materials of which include polyol, polyisocyanate, latent curing agent, the raw materials further include nanosilica aerogel and modifier, the modifier is made by reaction of a compound represented by formula (I) with a compound represented by formula (II);

[0009] In formula (I), R1 is C 1-10 straight-chain alkyl, n is greater than or equal to 1 In formula (II), R2, R3 are independently C 1-10 alkyl, R4 is C 1-10 alkyl or C 1-10 alkoxy, a is selected from 1-10;

[0010] The latent curing agent has a structure represented by formula (III), In formula (III), R5 is selected from C 3-10 alkyl or fluorine-substituted C 3-10 alkyl, R6 is selected from C 1-10 alkyl, b is selected from 0-10, and the sum of the number of carbon atoms of R6 and b is greater than or equal to 8.

[0011] According to some preferred and specific aspects of the present application, the molecular weight of the compound represented by formula (I) is 500-5000.

[0012] According to some preferred aspects of the present application, in formula (I), R1 is methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl or n-pentyl.

[0013] According to some preferred and specific aspects of the present application, in formula (II), R2, R3, R4 are independently selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl or n-pentyl, and a is 1, 2, 3, 4 or 5.

[0014] According to some preferred and specific aspects of the present application, in the process of preparing the modifier, the reaction is carried out at 70-90℃.

[0015] According to some preferred and specific aspects of the present application, the feed molar ratio of the compound represented by formula (I) to the compound represented by formula (II) is 1:0.8-1.2.

[0016] In some embodiments of the present application, the embodiment of preparing the modifier includes: after dehydration of the compound represented by formula (I), the compound represented by formula (II) is added to the compound represented by formula (I) under stirring, and the reaction is kept warm.

[0017] According to some preferred aspects of the present application, the modifier accounts for 12%-28% in the polyurethane waterproof coating by mass percentage.

[0018] According to some preferred and specific aspects of the present application, in formula (III), R5 is c is 1, 2 or 3.

[0019] According to some preferred and specific aspects of the present application, R6 is selected from methyl, ethyl or n-propyl, and b is selected from 6, 7, 8, 9 or 10.

[0020] According to some preferred aspects of the present application, the latent curing agent is prepared by reaction.

[0021] According to some preferred aspects of the present application, the embodiment for preparing the latent curing agent comprises: adding a compound shown in formula (III-1) to a compound shown in formula (III-2), reacting under a protective atmosphere, and vacuum dehydration.

[0022] According to some preferred aspects of the present application, the molar ratio of the compound shown in formula (III-2) to the compound shown in formula (III-1) is 1:2-2.1.

[0023] According to some preferred aspects of the present application, the latent curing agent accounts for 1%-3% in the polyurethane waterproof coating by mass percentage.

[0024] According to some preferred aspects of the present application, the nano-silica aerogel accounts for 0.2%-0.5% in the polyurethane waterproof coating by mass percentage.

[0025] According to some preferred aspects of the present application, in the nano-silica aerogel, the average pore size of the pores is 10-50 nm, the specific surface area is 600-1200 m 2 / g, and the porosity is greater than 90%. Further, in the nano-silica aerogel, the average pore size of the pores is 20-40 nm, the specific surface area is 800-1000 m 2 / g, and the porosity is greater than 90%.

[0026] According to some preferred and specific aspects of the present application, the raw materials of the polyurethane waterproof coating comprise, by mass percentage:

[0027]

[0028] In some embodiments of the present application, the polyol comprises a mixture of polyether diols and polyether triols.

[0029] In some embodiments of the present application, the polyether diol comprises any one of polyether 2000D, polyether 4000, polyether 6000.

[0030] In some embodiments of the present application, the polyether triol comprises any one of polyether 330N, Puranol G 4030, MN-3050D.

[0031] In some embodiments of the present application, the mass ratio of the polyether diol to the polyether triol is (2.3-4):1.

[0032] In some embodiments of the present application, the polyisocyanate can be diisocyanate, triisocyanate or a polymer thereof; further, in some embodiments, the polyisocyanate can be one or two of isophorone diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate.

[0033] In some embodiments of the present application, the filler can be a mixture of one or more of heavy calcium carbonate, talc, kaolin. Further, in some embodiments, the heavy calcium carbonate has a mesh size of 500-1000 mesh, the talc has a mesh size of 800-1000 mesh, and the kaolin has a mesh size of 800-1500 mesh.

[0034] The present application provides another technical solution: a preparation method of the one-component polyurethane waterproof coating described above, which comprises:

[0035] Dehydrating the polyol and the optional filler;

[0036] Then adding the polyisocyanate, reacting, defoaming after the reaction, cooling, and adding the modifier and the latent curing agent under the protection of the protective gas, and then adding the nanosilica aerogel and mixing.

[0037] In some embodiments of the present application, the dehydration can be carried out at 100-120℃, and further can be carried out under vacuum.

[0038] In some embodiments of the present application, the reaction after adding the polyisocyanate can be carried out at 70-90℃, for example, can be carried out at 75-85℃.

[0039] In some embodiments of the present application, after the reaction, vacuum defoaming is carried out, and the temperature is cooled to below 40℃.

[0040] In some embodiments of the present application, the protective gas can be nitrogen, argon, helium, etc.

[0041] Thanks to the above technical solutions, the present application has the following advantages compared with the prior art:

[0042] The present application is based on the problems of the prior art using plasticizers and conventional latent curing agents, and innovatively uses a specific modifier to modify the main chain containing urethane groups, which significantly increases the flexibility of the film after film formation without additional plasticizers. In particular, with a specific latent curing agent, the latent curing agent not only realizes latent curing, but also releases aldehyde, which not only has low volatility, but also is adsorbed under the restriction of nano-silica aerogel and greatly reduces the possibility of small molecules migrating from the polymer chain segment gap due to the presence of a straight carbon chain, further increasing the flexibility of the system. In addition, the polar surface and porous structure of the nano-silica aerogel will further adsorb the polyurethane molecular chain, thereby improving its cohesive strength. Practice shows that the waterproof coating of the present application not only has extremely low odor, good storage stability, but also has good waterproof durability, good film flexibility, excellent mechanical properties, and moderate curing speed for thick coating. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 NMR hydrogen spectrum of the latent curing agent prepared for Example 1 of the present application;

[0044] Figure 2 NMR hydrogen spectrum of the commercially available latent curing agent used in Comparative Examples 2-3 of the present application. DETAILED DESCRIPTION

[0045] The above scheme is further described in conjunction with specific examples. It should be understood that these examples are used to illustrate the basic principles, main features and advantages of the present application, and the present application is not limited in scope by the following examples. The implementation conditions used in the examples can be further adjusted according to specific requirements, and the implementation conditions not specified in the examples are usually the conditions in conventional experiments.

[0046] The amount of various substances added in the examples is indicated by "parts" unless otherwise specified. In the following examples, all raw materials can be obtained from commercial sources or prepared by conventional methods in the art, unless otherwise specified.

[0047] Example 1

[0048] This example provides a one-component polyurethane waterproof coating and a preparation method thereof. The raw materials of the one-component polyurethane waterproof coating include, in mass parts:

[0049]

[0050] Among them, the polyol is composed of polyether 2000D (Shanghai Dongda Chemical) and polyether 330N (Shanghai Dongda Chemical) with a mass ratio of 3:1;

[0051] The polyisocyanate is MDI, which is purchased from Wanhua Chemical, and the brand is MDI-50;

[0052] The modifier is prepared by the following method: 0.2 mol of polypropylene glycol monobutyl ether with a molecular weight of 1000 g / mol is added in a 500 mL four-necked flask, and vacuum dehydration is performed at 115°C for 2 h, and then the temperature is lowered to 80°C, and 0.21 mol of isocyanate propyl methyl dimethoxy silane is added while stirring, and the reaction is maintained for 4 h to obtain the modifier;

[0053] The latent curing agent is prepared by the following method: 0.2 mol of 2-methyl-1,5-pentanediamine is added in a 500 mL four-necked flask, and then 0.41 mol of 2-methyl lauric aldehyde is slowly added through a dropping funnel, and stirring is performed under nitrogen protection overnight (twelve hours), and then the temperature is raised to 70°C, and vacuum dehydration is performed for 2 h to obtain the latent curing agent, and the proton nuclear magnetic resonance spectrum thereof is shown in Figure 1

[0054] The nano-silica aerogel has an average pore size of 20-40 nm, a specific surface area of 800-1000 m 2 / g, and a porosity of greater than 90%, which is purchased from Aierge New Material Co., Ltd., and the brand is 06;

[0055] The heavy calcium carbonate has a mesh size of 1250 mesh, which is purchased from Hezhou Guibao Powder Co., Ltd., and the brand is GB-36;

[0056] The talc powder has a mesh size of 800 mesh, which is purchased from Xufeng Powder Co., Ltd., and the brand is BHS-305.

[0057] The preparation method of the one-component polyurethane waterproof coating includes:

[0058] (1) The formula amount of polyol, modifier, heavy calcium carbonate, and talc powder is weighed, and stirring and vacuum dehydration are performed at 110°C for 2 h;

[0059] (2) The temperature is lowered to 80°C, and the formula amount of polyisocyanate is added, and the reaction is performed for 3 h;

[0060] (3) Vacuum defoaming is performed, and the reaction temperature is lowered to below 40°C;

[0061] (4) The formula amount of latent curing agent is added to the system of step (3) under the protection of nitrogen, and stirring is performed for 20 min, and then the nano-silica aerogel is added and stirred for 15 min to obtain the one-component polyurethane waterproof coating.

[0062] Example 2

[0063] ​The example provides a single-component polyurethane waterproof coating and a preparation method thereof. Raw materials of the single-component polyurethane waterproof coating include, in mass parts:

[0064]

[0065] The other is the same as in Example 1.

[0066] Example 3

[0067] The example provides a single-component polyurethane waterproof coating and a preparation method thereof. Raw materials of the single-component polyurethane waterproof coating include, in mass parts:

[0068]

[0069] The other is the same as in Example 1.

[0070] Comparative Example 1

[0071] The same as in Example 1, except that no nano-silica aerogel is added.

[0072] Comparative Example 2

[0073] The same as in Example 1, except that the latent curing agent is replaced by a commercially available latent curing agent (a hydrogen nuclear magnetic resonance spectrum thereof is shown in Figure 2 ), and no nano-silica aerogel is added.

[0074] Comparative Example 3

[0075] The same as in Example 1, except that the latent curing agent is replaced by a commercially available latent curing agent (a hydrogen nuclear magnetic resonance spectrum thereof is shown in Figure 2 ).

[0076] Comparative Example 4

[0077] The same as in Example 1, except that the modifier is replaced by a chlorinated paraffin in the same amount.

[0078] Performance test

[0079] The coating samples prepared in Examples 1-3 and Comparative Examples 1-4 above are prepared into coating film samples with a thickness of about 1.5 mm by one-time film forming, and after curing for 7 days under standard conditions of a temperature of (23±2)℃ and a humidity of (60±5)%, the performance is tested according to the method of JC / T1066-2008, and the results are shown in Table 1.

[0080] Table 1

[0081]

[0082] From Table 1, compared with Example 1, the tensile strength of the coating obtained by not adding nano-silica aerogel in Comparative Example 1 is obviously reduced by about 22.4%, the water absorption is obviously increased, especially after long-term storage, the water absorption is significantly increased by 63.2% compared with the initial stage, the adhesion strength is slightly reduced, and there is a slight odor;

[0083] After the latent curing agent is replaced by a commercially available latent curing agent and nano-silica aerogel is not added in Comparative Example 2, the tensile strength of the coating obtained is obviously reduced by about 40.3%, the water absorption is obviously increased, especially after long-term storage, the water absorption is significantly increased by 75.2% compared with the initial stage, and the adhesion strength decreases faster after immersion;

[0084] After the latent curing agent is replaced by a commercially available latent curing agent in Comparative Example 3, the tensile strength of the coating obtained is obviously reduced by about 35.6%, the water absorption is obviously increased, especially after long-term storage, the water absorption is significantly increased by 69.4% compared with the initial stage;

[0085] In Comparative Example 4, the modifier is replaced by chlorinated paraffin, on the one hand, the chlorinated paraffin is physically blended, which does not contribute to the tensile strength of the material, on the other hand, the chlorinated paraffin has obvious migration, the toughness of the coating after film formation is not good, and due to the migration phenomenon, the porosity is opened, resulting in a significant increase in water absorption, and the adhesion strength of the system is low.

[0086] From the above comparative analysis, in the system of the present application, the change of any component has a significant effect on the performance, especially on the tensile strength, water absorption at different stages and adhesion strength at different stages, which shows that the components have a significant synergistic effect.

[0087] The above examples are only for illustrating the technical concept and characteristics of the present application, the purpose is to enable those skilled in the art to understand the content of the present application and to implement it, and cannot limit the protection scope of the present application. Any equivalent changes or modifications made according to the spirit and essence of the present application should be covered within the protection scope of the present application.

[0088] The endpoints of the ranges and any values in the ranges disclosed herein are not limited to the precise values. The ranges or values should be understood as being approximate, and inculding values near one or both of the recited ranges or values. For ranges, the endpoints are included within the ranges, and the ranges are inclusive of the endpoints. For values, the value includes the exact value, and the value is inclusive of the exact value.

Claims

1. A waterproof coating, characterized in that: The raw materials of the waterproof coating include polyol, polyisocyanate, filler, modifier, nano-silica aerogel and latent curing agent; Wherein, the modifier is prepared by reacting the compound represented by formula (I) with the compound represented by formula (II); In formula (I), R1 is C 1-10 Straight-chain alkyl, the molecular weight of the compound represented by formula (I) is 500-5000; In formula (II), R2 and R3 are independently C 1-10 Alkyl, R4 is C 1-10 Alkyl or C 1-10 Alkoxy, a is selected from 1-10; The latent curing agent is Reaction is prepared, wherein R5 is selected from C 3-10 Alkyl or fluorine-substituted C 3-10 Alkyl, R6 is selected from C 1-10 Alkyl, b is selected from 0-10, and the sum of the number of carbon atoms of R6 and b is greater than or equal to 8; The porosity of the nano-silicon dioxide aerogel is greater than 90%.

2. The waterproof coating according to claim 1, characterized in that The raw materials of the waterproof coating include, by mass percentage, 18% to 25% of polyol, 5% to 10% of polyisocyanate, 12% to 28% of modifier, 40% to 62% of filler, 1% to 3% of latent curing agent, and 0.2% to 0.5% of nano-silica aerogel; and / or, the average pore size of the nano-silica aerogel is 10-50nm, and the specific surface area is 600-1200m 2 / g.

3. The waterproof coating according to claim 1 or 2, characterized in that: In terms of mass percentage, the raw materials of the waterproof coating include 22% to 28% of the modifier, 2% to 3% of the latent curing agent, and 0.3% to 0.5% of the nano-silica aerogel; and / or, the nano-silica aerogel has an average pore diameter of 20-40 nm and a specific surface area of ​​800-1000 m 2 / g.

4. The waterproof coating according to claim 1, characterized in that The polyol is a polyether polyol; and / or the polyisocyanate is a diisocyanate, a triisocyanate or a polymer thereof; and / or the filler is a mixture of one or more of heavy calcium carbonate, talc and kaolin.

5. The waterproof coating according to claim 1 or 4, characterized in that: The polyol includes a mixture of polyether diols and polyether triols.

6. The waterproof coating according to claim 5, characterized in that: The polyether diol includes any one of polyether 2000D, polyether 4000, and polyether 6000; and / or the polyether triol includes any one of polyether 330N, polyether Puranol G4030, and polyether MN-3050D; and / or the mass ratio of the polyether diol to the polyether triol is (2.3-4):

1.

7. The waterproof coating according to claim 1, characterized in that: In formula (I), R1 is methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl or n-pentyl; and / or, in formula (II), R2, R3, and R4 are independently selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl or n-pentyl, and a is 1, 2, 3, 4 or 5; and / or, the molar ratio of the compound represented by formula (I) to the compound represented by formula (II) is 1:0.8-1.

2.

8. The waterproof coating according to claim 1 or 7, characterized in that: The compound represented by formula (I) is polypropylene glycol monobutyl ether; and / or the compound represented by formula (II) is isocyanate propylmethyldimethoxysilane.

9. The waterproof coating according to claim 1, characterized in that: The embodiment of preparing the modifier includes: after dehydrating the compound represented by formula (I), adding the compound represented by formula (II) to the compound represented by formula (I) under stirring conditions, and keeping the temperature at 70-90°C for reaction.

10. The waterproof coating according to claim 1, characterized in that: R5 is c is 1, 2 or 3; and / or, R6 is selected from methyl, ethyl or n-propyl, and b is selected from 6, 7, 8, 9 or 10.

11. The waterproof coating according to claim 1, characterized in that: The embodiment of preparing the latent curing agent comprises: adding the compound represented by formula (III-1) to the compound represented by formula (III-2), reacting under a protective atmosphere, and vacuum dehydrating; Wherein, the molar ratio of the compound represented by formula (III-2) to the compound represented by formula (III-1) is 1:2-2.

1.

12. The waterproof coating according to claim 1, 10 or 11, characterized in that: The compound represented by formula (III-1) is 2-methyllaurinaldehyde; and / or the compound represented by formula (III-2) is 2-methyl-1,5-pentanediamine.

Images