A one-component polyurethane waterproof coating and its preparation method

Abstract

The present invention discloses a one-component polyurethane waterproof coating and a preparation method thereof. The raw materials thereof include polyols, polyisocyanates, latent curing agents, nano-silica aerogels and modifiers. The modifier is prepared by reacting the compounds represented by formula (I) and formula (II); R1 is a C 1‑10 straight-chain alkyl group, n is greater than or equal to 1; R2 and R3 are independently C 1‑10 alkyl groups, R4 is C 1‑10 alkyl group or C 1‑10 alkoxy group, a is selected from 1-10; the latent curing agent has a structure represented by formula (III), R5 is selected from C 3‑10 alkyl group or fluorine-substituted C 3‑10 alkyl group, R6 is selected from C 1‑10 alkyl group, 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 waterproof coating of the present invention not only has extremely low odor and good storage stability, but also has good waterproof durability, excellent film flexibility, excellent mechanical properties, and moderate curing speed for thick coating.

Description

Technical Field

[0001] The invention relates to the field of waterproof coatings, and in particular to a single-component polyurethane waterproof coating and a preparation method thereof. Background Art

[0002] One-component polyurethane waterproof coating is made from an isocyanate-containing prepolymer formed by the addition polymerization reaction of isocyanate, polyether, etc., with a catalyst, anhydrous auxiliary agent, anhydrous filler, solvent, etc., and is processed through mixing and other processes.

[0003] At present, in order to improve the flexibility of the cured coating of the single-component polyurethane waterproof coating, plasticizers are generally added to improve the flexibility of the coating. However, the added plasticizers may migrate during the application process. After the migration of the plasticizers, the brittleness of the coating will increase. In addition, the migration of the plasticizers will also cause the surface of the substrate to be contaminated or damaged, thereby causing the waterproof film to fall off the substrate, affecting the waterproof durability, resulting in a decrease in the performance of the polyurethane waterproof coating, and shortening the service life of the polyurethane waterproof coating. At the same time, the traditional one-component polyurethane waterproof coating is cured into a film by reacting the prepolymer containing NCO end groups with moisture in the air. CO2 will be released during the curing reaction. Therefore, the traditional one-component polyurethane waterproof coating is easily affected by the humidity of the construction environment during the construction process, resulting in the inability to apply thick coating, slow curing, and the coating film after curing is prone to bubbles and pinholes, which seriously affects the performance and construction quality of the one-component polyurethane waterproof coating. In order to solve the problem of bubbles and pinholes, it is usually practiced to add a certain amount of latent curing agent to the polyurethane coating. The latent curing agent will preferentially react with moisture in the air to generate amino or hydroxyl groups at a faster rate. The generated amino or hydroxyl groups react with isocyanate groups to undergo cross-linking and curing reactions. In this process, no carbon dioxide will be generated, thereby eliminating the generation of bubbles and pinholes. However, with the increase in the amount of latent curing agent added, the storage stability of the one-component polyurethane waterproof coating is significantly deteriorated. In addition, many known latent curing agents usually have a strong odor and are easy to cause harm to the body. Summary of the invention

[0004] The purpose of the present invention is to overcome one or more deficiencies in the prior art and to provide an improved one-component polyurethane waterproof coating, which overcomes the problem of losing one thing while gaining another after adding a plasticizer and a conventional latent curing agent in the prior art. The coating has low odor, good film flexibility, and good storage stability.

[0005] The invention also provides a method for preparing the one-component polyurethane waterproof coating.

[0006] In order to achieve the above object, a technical solution adopted by the present invention is:

[0007] A one-component polyurethane waterproof coating, the raw materials of which include polyols, polyisocyanates, and latent curing agents. The raw materials also include nano-silica aerogel and a modifier, and the modifier is prepared by reacting a compound represented by formula (I) with a compound represented by formula (II);

[0008] In formula (I), R1 is a C 1-10 linear alkyl group, and n is greater than or equal to 1; In formula (II), R2 and R3 are independently C 1-10 alkyl groups, R4 is C 1-10 alkyl group or C 1-10 alkoxy group, and a is selected from 1-10;

[0009] The latent curing agent has a structure represented by formula (III), In formula (III), R5 is selected from C 3-10 alkyl group or fluorine-substituted C 3-10 alkyl group, R6 is selected from C 1-10 alkyl group, 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.

[0010] According to some preferred and specific aspects of the present invention, the molecular weight of the compound represented by formula (I) is 500-5000.

[0011] According to some preferred aspects of the present invention, in formula (I), R1 is methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl or n-pentyl.

[0012] According to some preferred and specific aspects of the present invention, 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.

[0013] According to some preferred and specific aspects of the present invention, in the process of preparing the modifier, the reaction is carried out at 70-90°C.

[0014] According to some preferred and specific aspects of the present invention, the molar ratio of the compound represented by formula (I) to the compound represented by formula (II) in the feed is 1:0.8-1.2.

[0015] In some embodiments of the present invention, the embodiment of preparing the modifier includes: dehydrating the compound represented by formula (I), and then adding the compound represented by formula (II) to the compound represented by formula (I) under stirring conditions, and carrying out a heat-preservation reaction.

[0016] According to some preferred aspects of the present invention, by mass percentage, in the polyurethane waterproof coating, the modifier accounts for 12%-28%.

[0017] According to some preferred and specific aspects of the present invention, in formula (III), R5 is c is 1, 2 or 3.

[0018] According to some preferred and specific aspects of the present invention, R6 is selected from methyl, ethyl or n-propyl, and b is selected from 6, 7, 8, 9 or 10.

[0019] According to some preferred aspects of the present invention, the latent curing agent is made from a reaction.

[0020] According to some preferred aspects of the present invention, the implementation mode of preparing the latent curing agent includes: adding the compound shown in formula (III-1) to the compound shown in formula (III-2), reacting under a protective atmosphere, and dehydrating under vacuum.

[0021] According to some preferred aspects of the present invention, the molar ratio of the compound shown in formula (III-2) to the compound shown in formula (III-1) in the feed is 1:2 - 2.1.

[0022] According to some preferred aspects of the present invention, by mass percentage, in the polyurethane waterproof coating, the latent curing agent accounts for 1% - 3%.

[0023] According to some preferred aspects of the present invention, by mass percentage, in the polyurethane waterproof coating, the nano-silica aerogel accounts for 0.2% - 0.5%.

[0024] According to some preferred aspects of the present invention, in the nano-silica aerogel, the average pore diameter 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 diameter of the pores is 20 - 40 nm, the specific surface area is 800 - 1000 m 2 / g, and the porosity is greater than 90%.

[0025] According to some preferred and specific aspects of the present invention, by mass percentage, the raw materials of the polyurethane waterproof coating include:

[0026]

[0027] In some embodiments of the present invention, the polyol includes a mixture of a polyether diol and a polyether triol.

[0028] In some embodiments of the present invention, the polyether diol includes any one of polyether 2000D, polyether 4000, and polyether 6000.

[0029] In some embodiments of the present invention, the polyether triol includes any one of polyether 330N, Puranol G 4030, and MN-3050D.

[0030] In some embodiments of the present invention, the mass ratio of the polyether diol to the polyether triol is (2.3 - 4):1.

[0031] In some embodiments of the present invention, the polyisocyanate can be a diisocyanate, a triisocyanate, or their respective polymers; further, in some embodiments, the polyisocyanate can be one or two of isophorone diisocyanate, hexamethylene diisocyanate, and diphenylmethane diisocyanate.

[0032] In some embodiments of the present invention, the filler can be a mixture of one or more of heavy calcium carbonate, talcum powder, and kaolin. Further, in some embodiments, the mesh number of heavy calcium carbonate is 500 - 1000 mesh, the mesh number of talcum powder is 800 - 1000 mesh, and the mesh number of kaolin is 800 - 1500 mesh.

[0033] Another technical solution provided by the present invention: A preparation method of the above-mentioned one-component polyurethane waterproof coating, the preparation method comprising:

[0034] Dehydrate the polyol and the optional filler;

[0035] Then add the polyisocyanate and react. After the reaction is completed, defoam, cool down, add the modifier and the latent curing agent under the protection of an inert gas, and then add nano-silica aerogel and mix well.

[0036] In some embodiments of the present invention, the dehydration can be carried out at 100 - 120 °C, and further can be carried out under vacuum conditions.

[0037] In some embodiments of the present invention, the reaction after adding the polyisocyanate can be carried out at 70 - 90 °C, for example, can be carried out at 75 - 85 °C.

[0038] In some embodiments of the present invention, after the reaction is completed, vacuum defoaming is carried out, and the temperature is cooled down to below 40 °C.

[0039] In some embodiments of the present invention, the inert gas can be nitrogen, argon, helium, etc.

[0040] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0041] Based on the problem of one-sidedness in the use of plasticizers and conventional latent curing agents in the prior art, the present invention innovatively uses a specific modifier to modify the main chain containing urethane groups, achieving a significant increase in the flexibility of the film layer after film formation without the additional addition of plasticizers. In particular, in combination with a specific latent curing agent, on the one hand, the latent curing agent realizes the latent curing effect, and on the other hand, the released aldehyde not only has low volatility, but also can be adsorbed under the confinement of nano-silica aerogel and, due to the presence of obvious straight-chain carbon chains, greatly reduces the possibility of small molecules migrating outward from the polymer chain segment voids, further increasing the flexibility of the system. In addition, the polar surface and porous structure of nano-silica aerogel will further adsorb the polyurethane molecular chains, thereby improving its cohesive strength. Practice shows that the waterproof coating of the present invention not only has extremely low odor and good storage stability, but also has good waterproof durability under the synergistic action of various components, excellent film layer flexibility, excellent mechanical properties, and moderate thick coating curing speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 1H NMR spectrum of the latent curing agent prepared in Example 1 of the present invention;

[0043] Figure 2 1H NMR spectrum of the commercially available latent curing agent used in Comparative Examples 2-3 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0044] The following further illustrates the above scheme with specific embodiments; it should be understood that these embodiments are used to illustrate the basic principles, main features and advantages of the present invention, and the present invention is not limited by the scope of the following embodiments; the implementation conditions adopted in the embodiments can be further adjusted according to specific requirements, and the implementation conditions not specified are usually the conditions in conventional experiments.

[0045] The addition amounts of various substances are involved in the embodiments, and the "parts" mentioned herein refer to "parts by weight" unless otherwise specified. In the following embodiments, without special instructions, all raw materials can be obtained commercially or prepared by conventional methods in the art.

[0046] Example 1

[0047] This example provides a one-component polyurethane waterproof coating and its preparation method. In terms of mass parts, the raw materials of the one-component polyurethane waterproof coating include:

[0048]

[0049] Among them, the polyol is composed of polyether 2000D (Shanghai Dongda Chemical) and polyether 330N (Shanghai Dongda Chemical) with a feeding mass ratio of 3:1;

[0050] The polyisocyanate is MDI, purchased from Wanhua Chemical, with the grade MDI-50;

[0051] The modifier was prepared by the following method: In a 500 mL four-necked flask, 0.2 mol of polypropylene glycol monobutyl ether with a molecular weight of 1000 g / mol (purchased from Shanghai Banggao Chemical) was added. The temperature was raised to 115 °C and vacuum dehydration was carried out for 2 h. Subsequently, the temperature was lowered to 80 °C, and 0.21 mol of isocyanatopropylmethyldimethoxysilane was added while stirring. The reaction was carried out at a constant temperature for 4 h to obtain the modifier;

[0052] The latent curing agent was prepared by the following method: In a 500 mL four-necked flask, 0.2 mol of 2-methyl-1,5-pentanediamine was added, and then 0.41 mol of 2-methyllaurinaldehyde was slowly added dropwise through a dropping funnel. Stirring was carried out overnight (twelve hours) under nitrogen protection. Subsequently, the temperature was raised to 70 °C and vacuum dehydration was carried out for 2 hours to obtain the latent curing agent. Its nuclear magnetic resonance hydrogen spectrum is as Figure 1 shown;

[0053] Nano-silica aerogel, with an average pore size of 20 - 40 nm, a specific surface area of 800 - 1000 m 2 / g, and a porosity greater than 90%, purchased from Areguo New Materials Co., Ltd., with the grade 06;

[0054] Heavy calcium carbonate, with a mesh number of 1250 mesh, purchased from Hezhou Guibao Powder Co., Ltd., with the grade GB-36;

[0055] Talc powder, with a mesh number of 800 mesh, purchased from Xufeng Powder Co., Ltd., with the grade BHS-305.

[0056] The preparation method of the one-component polyurethane waterproof coating includes:

[0057] (1) Weigh the formulated amounts of polyol, modifier, heavy calcium carbonate, and talc powder, stir at 110 °C, and carry out vacuum dehydration for 2 h;

[0058] (2) Lower the temperature to 80 °C, add the formulated amount of polyisocyanate, and react for 3 h;

[0059] (3) Carry out vacuum degassing and lower the reaction temperature to below 40 °C;

[0060] (4) Under the protection of nitrogen, add the formulated amount of latent curing agent to the system in step (3), stir for 20 min, and then add nano-silica aerogel and stir and mix for 15 min to obtain the one-component polyurethane waterproof coating.

[0061] Example 2

[0062] This example provides a one-component polyurethane waterproof coating and its preparation method. Calculated by mass parts, the raw materials of the one-component polyurethane waterproof coating include:

[0063]

[0064] Others are the same as in Example 1.

[0065] Example 3

[0066] This example provides a one-component polyurethane waterproof coating and its preparation method. Calculated by mass parts, the raw materials of the one-component polyurethane waterproof coating include:

[0067]

[0068] Others are the same as in Example 1.

[0069] Comparative Example 1

[0070] Basically the same as Example 1, the only difference is that nano-silica aerogel is not added.

[0071] Comparative Example 2

[0072] Basically the same as Example 1, the only difference is that the latent curing agent is replaced with a commercially available latent curing agent with the same addition amount (the proton nuclear magnetic resonance spectrum of which is as Figure 2 shown), and nano-silica aerogel is not added.

[0073] Comparative Example 3

[0074] Basically the same as Example 1, the only difference is that the latent curing agent is replaced with a commercially available latent curing agent with the same addition amount (the proton nuclear magnetic resonance spectrum of which is as Figure 2 shown).

[0075] Comparative Example 4

[0076] Basically the same as Example 1, the only difference is that the modifier is replaced with chlorinated paraffin with the same addition amount.

[0077] Performance Test

[0078] The coating samples prepared in the above Examples 1 to 3 and Comparative Examples 1 to 4 were prepared into film specimens with a thickness of about 1.5 mm by the one-time film-forming method. After curing for 7 days under the standard conditions of temperature (23±2)°C and humidity (60±5)%, the test was carried out according to the method of JC / T1066-2008, and the results are shown in Table 1 below.

[0079] Table 1

[0080]

[0081] As can be seen from Table 1, compared with Example 1, after nano-silica aerogel was not added in Comparative Example 1, the tensile strength of the obtained coating decreased significantly by about 22.4%, and the water absorption rate increased significantly. Especially after long-term storage, the water absorption rate increased significantly compared with the initial stage, by 63.2%. At the same time, the bonding strength decreased slightly, and there was also a slight odor emitted.

[0082] In Comparative Example 2, after replacing the latent curing agent with a commercially available latent curing agent and not adding nano-silica aerogel, the tensile strength of the obtained coating decreased significantly by about 40.3%, and the water absorption rate increased significantly. Especially after long-term storage, the water absorption rate increased significantly compared with the initial stage, by 75.2%. At the same time, the bonding strength decreased faster after immersion in water.

[0083] In Comparative Example 3, after replacing the latent curing agent with a commercially available latent curing agent, the tensile strength of the obtained coating decreased significantly by about 35.6%, and the water absorption rate increased significantly. Especially after long-term storage, the water absorption rate increased significantly compared with the initial stage, by 69.4%.

[0084] In Comparative Example 4, the modifier was replaced with chlorinated paraffin. On the one hand, since chlorinated paraffin is physically blended, it does not contribute to the tensile strength of the material. On the other hand, due to the obvious migration of chlorinated paraffin, the toughness of the coating film is poor. Moreover, due to the occurrence of the migration phenomenon, the pores are opened, resulting in a significant increase in the absorption rate, and the bonding strength of the system is low.

[0085] From the above comparative analysis, it can be seen that under the system of the present invention, any change in components has an obvious impact on the performance, especially on the tensile strength, water absorption rate at different stages, and bonding strength at different stages, indicating that there is an obvious synergistic effect among the components.

[0086] The above embodiments are only used to illustrate the technical concept and characteristics of the present invention, and their purpose is to enable those who are familiar with this technology to understand the content of the present invention and implement it accordingly, and it cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

[0087] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

Claims

1. A one-component polyurethane waterproof coating, the raw materials of which comprise polyols, polyisocyanates, and latent curing agents, and are characterized in that, The raw materials further include nano-silica aerogel and a modifier, and the modifier is prepared by reacting a compound represented by formula (I) with a compound represented by formula (II); In it, R1 is C 1-10 a straight-chain alkyl group, and n is greater than or equal to 1; In, R2 and R3 are independently C 1-10 alkyl groups, R4 is C 1-10 alkyl or C 1-10 alkoxy, and a is selected from 1 - 10; The latent curing agent has a structure represented by the formula (III), 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.

2. The one-component polyurethane waterproof coating according to claim 1, wherein The molecular weight of the compound represented by formula (I) is 500 - 5000; and / or, in formula (I), R1 is methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl or n-pentyl.

3. The one-component polyurethane waterproof coating according to claim 1, characterized in that, 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.

4. The one-component polyurethane waterproof coating according to claim 1, wherein In the process of preparing the modifier, the reaction is carried out at 70 - 90 °C; and / or, the molar ratio of the compound represented by formula (I) to the compound represented by formula (II) in the feed is 1:0.8 - 1.

2.

5. The one-component polyurethane waterproof coating according to claim 1, characterized in that, The implementation mode of preparing the modifier includes: dehydrating the compound represented by formula (I), and then adding the compound represented by formula (II) to the compound represented by formula (I) under stirring conditions, and carrying out a heat preservation reaction.

6. The one-component polyurethane waterproof coating according to claim 1, characterized in that, By mass percentage, in the polyurethane waterproof coating, the modifier accounts for 12% - 28%.

7. The one-component polyurethane waterproof coating according to claim 1, characterized in that, In formula (III), R5 is c is 1, 2 or 3.

8. The one-component polyurethane waterproof coating according to claim 1, wherein R6 is selected from methyl, ethyl or n-propyl, and b is selected from 6, 7, 8, 9 or 10.

9. The one-component polyurethane waterproof coating according to claim 1, characterized in that, The latent curing agent is made from through reaction.

10. The one-component polyurethane waterproof coating according to claim 9, characterized in that, The implementation mode of preparing the latent curing agent includes: adding the compound represented by formula (III-1) to the compound represented by formula (III-2), reacting under a protective atmosphere, and carrying out vacuum dehydration; and / or, the molar ratio of the compound represented by formula (III-2) to the compound represented by formula (III-1) in the feed is 1:2 - 2.

1.

11. The one-component polyurethane waterproof coating according to claim 1, characterized in that, By mass percentage, in the polyurethane waterproof coating, the latent curing agent accounts for 1% - 3%.

12. The one-component polyurethane waterproof coating according to claim 1, characterized in that, In the polyurethane waterproof coating, the nano-silica aerogel accounts for 0.2% - 0.5% by mass percentage; and / or, in the nano-silica aerogel, the average pore diameter of the pores is 10 - 50 nm, the specific surface area is 600 - 1200 m 2 / g, and the porosity is greater than 90%.

13. The one-component polyurethane waterproof coating according to claim 1, characterized in that, By mass percentage, the raw materials of the polyurethane waterproof coating include:

14. A method for preparing the one-component polyurethane waterproof coating according to any one of claims 1-13, characterized in that, This preparation method includes: Dehydrating the polyol and optionally the filler; Then adding polyisocyanate, reacting, degassing after the reaction is completed, cooling down, adding the modifier and the latent curing agent under the protection of a protective gas, and then adding nano-silica aerogel and mixing evenly.

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