Two-component polyurethane waterproof coating and preparation method thereof

Abstract

The application provides a two-component polyurethane waterproof coating, which comprises the following components by mass fraction: A component: lignin oligomer 40-90 parts, polyether polyol 40-90 parts, organic silicon modifier 2-5 parts, and water-based solvent 20-40 parts; the number average molecular weight of the lignin oligomer is 3000-4000; the organic silicon modifier comprises double-end hydroxyl polyether modified silicon oil; B component: isocyanate curing agent 60-80 parts and catalyst 1-5 parts; wherein the mass ratio of the A component to the B component is 10-15:1. The coating prepared from the two-component polyurethane waterproof coating has good water resistance and hydrophobicity.

Description

Technical Field

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

[0002] With the development of the times and the advancement of technology, the modern construction industry has developed rapidly, and people's requirements for coatings have also risen accordingly. Coatings are an important part of construction projects, serving both protective and decorative functions. Two-component polyurethane coatings possess superior properties such as low film-forming temperature, strong adhesion, good abrasion resistance, high hardness, and excellent chemical and weather resistance, making them widely used as industrial protective coatings, wood furniture coatings, and automotive coatings. As people's demands for a high-quality life gradually increase, they are also paying more and more attention to the waterproof performance of coatings made from paints.

[0003] Therefore, it is necessary to seek a two-component polyurethane coating with excellent waterproof performance that can effectively prevent rainwater and groundwater leakage. Summary of the Invention

[0004] The purpose of this invention is to provide a two-component polyurethane waterproof coating and its preparation method, so that the resulting coating has good water resistance and hydrophobicity.

[0005] According to a first aspect of the present invention, a two-component polyurethane waterproof coating is provided, comprising, by weight parts: Component A: 40-90 parts of lignin oligomer, 40-90 parts of polyether polyol, 2-5 parts of organosilicon modifier, and 20-40 parts of aqueous solvent, wherein the number average molecular weight of the lignin oligomer is 3000-4000, and the organosilicon modifier includes hydroxyl-terminated polyether modified silicone oil; Component B: 60-80 parts of isocyanate curing agent and 1-5 parts of catalyst; wherein the mass ratio of Component A to Component B is 10-15:1.

[0006] The two-component polyurethane waterproof coating provided by this invention is safe and environmentally friendly, and the resulting coating exhibits excellent waterproofing, flexibility, and high hardness. During the cross-linking reaction between the hydroxyl groups in component A and the isocyanates in component B, an organosilicon modifier participates in the reaction. Utilizing the siloxanes and long hydrophobic carbon chains of the hydroxyl-terminated polyether-modified silicone oil, the hydrophobic and waterproof properties of the two-component polyurethane waterproof coating are further improved, ensuring that water from the external environment remains on the surface of the coating and does not penetrate into it. During the cross-linking reaction, the organosilicon modifier undergoes hydrolysis and condensation, forming a Si-O-Si cross-linked network structure together with lignin oligomers, polyether polyols, and isocyanate curing agents. Furthermore, during the curing process, as the aqueous solvent evaporates, this Si-O-Si cross-linked network structure migrates to the coating surface, thereby improving the surface strength of the coating. The hydrophobicity of the siloxy groups in this Si-O-Si cross-linked network structure improves the coating's water resistance and hydrophobicity, reduces the water separation rate, and increases the water contact angle. Secondly, by introducing hydroxyl-terminated polyether-modified silicone oil into the two-component polyurethane waterproof coating, the resulting Si-O-Si crosslinked network structure hinders the movement of molecular chains, thereby increasing the tensile strength of the coating. Compared with conventional polyurethane coatings that only use polyether polyols to provide hydroxyl groups, this solution uses lignin oligomers and polyether polyols together to provide hydroxyl groups in the two-component polyurethane waterproof coating, resulting in coatings with better hydrophobicity and thermal stability.

[0007] Preferably, the number-average molecular weight of the hydroxyl-terminated polyether modified silicone oil is 2000–4000, and the number-average molecular weight of the polyether polyol is 5000–7000. When a hydroxyl-terminated polyether modified silicone oil meeting the above-mentioned number-average molecular weight conditions is selected to prepare a two-component polyurethane waterproof coating with a polyether polyol, the isocyanate curing agent in component B will preferentially undergo a cross-linking reaction with the lignin oligomer, and then form a cross-linked network structure together with the polyether polyol and the organosilicon modifier, thereby further improving the cross-linking degree of the lignin oligomer and giving the resulting coating better hydrophobicity and thermal stability. In addition, the hydroxyl-terminated polyether modified silicone oil meeting the above conditions has a better modification effect as an organosilicon modifier, which can give the coating better tensile strength at break. If the number-average molecular weight of the hydroxyl-terminated polyether modified silicone oil is too small, the improvement effect on the hydrophobicity of the two-component polyurethane waterproof coating will not be significant; if the number-average molecular weight of the hydroxyl-terminated polyether modified silicone oil is too large, the modification reaction activity will be low.

[0008] Preferably, in component A, the mass ratio of lignin oligomer to polyether polyol is 1–1.5:1. When the mass ratio of lignin oligomer to polyether polyol is 1–1.5:1, the polyurethane network formed with component B has a more stable structure, resulting in a more stable two-component polyurethane waterproof coating. If too much lignin oligomer is added, the resulting coating is prone to flaking; if too little lignin oligomer is added, the improvement effect on the coating is not significant.

[0009] Preferably, the isocyanate curing agent includes at least one selected from toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, and lysine diisocyanate. Using diisocyanates such as toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate (HMDI), hexamethylene diisocyanate (HDI), and lysine diisocyanate (LDI) as isocyanate curing agents results in higher curing activity and is more conducive to the preparation of two-component polyurethane waterproof coatings.

[0010] Preferably, the lignin oligomers are prepared by depolymerizing lignin-containing biomass materials using a deep eutectic solvent system. The deep eutectic solvent is a ternary deep eutectic solvent of choline chloride / 1,2,4-butanetriol / aluminum chloride. Deep eutectic solvent (DES) is a low-cost, low-toxicity, and highly stable liquid. The ternary deep eutectic solvent of choline chloride / 1,2,4-butanetriol / aluminum chloride uses choline chloride as a hydrogen bond acceptor and 1,2,4-butanetriol and aluminum chloride as hydrogen bond donors. Using this ternary DES to depolymerize the natural lignin in the biomass materials, the hydrogen bonds in the ternary DES can break the bonds between lignin molecules, converting the highly polymerized natural lignin into the lignin oligomers required for preparing two-component polyurethane waterproof coatings. Furthermore, compared with other commonly used deep eutectic solvents, this ternary DES has a better depolymerization effect on lignin, and the resulting lignin oligomers have low and uniform molecular weights, which is beneficial to the preparation and curing of two-component polyurethane waterproof coatings.

[0011] Preferably, the lignin oligomer is prepared by the following steps: S1. Preparation of a deep eutectic solvent: Choline chloride, 1,2,4-butanetriol, and aluminum chloride are mixed evenly at 60-70°C until the mixture transforms into a clear liquid in a molten state, thus obtaining a deep eutectic solvent; S2. Depolymerization and extraction: The lignin-containing biomass material is mixed evenly with the deep eutectic solvent and reacted at 100-130°C for 1-3 hours to obtain the lignin oligomer. The lignin oligomer obtained by this step has excellent reactivity, and the reaction temperature of 100-130°C minimizes damage to the functional groups of the obtained lignin oligomer, without altering the main structure of its monomers.

[0012] Preferably, the lignin-containing biomass material has a particle size of less than 60 mesh, and the mass ratio of the lignin-containing biomass material to the deep eutectic solvent is 1:5 to 10. When the lignin-containing biomass material and the deep eutectic solvent meet the above conditions, the yield and purity of lignin extraction from the biomass material and the depolymerization of lignin into lignin oligomers are higher, and the obtained lignin oligomers are more conducive to the subsequent preparation of two-component polyurethane waterproof coatings.

[0013] Preferably, in the deep eutectic solvent, the molar ratio of choline chloride, 1,2,4-butanetriol, and aluminum chloride is 1:2:0.05–0.2. The deep eutectic solvent prepared with the above ratio has better extraction efficiency for lignin and higher purity of lignin oligomers.

[0014] Preferably, component A further includes 0.1 to 3 parts of defoamer, 0.1 to 3 parts of thickener, and 10 to 20 parts of filler.

[0015] According to another aspect of the present invention, a method for preparing the above-mentioned two-component polyurethane waterproof coating is provided, comprising the following steps: first, mixing all components of component A uniformly, and then mixing component A and component B uniformly to obtain the two-component polyurethane waterproof coating. The preparation process of the two-component polyurethane waterproof coating provided by this solution is simple, convenient to operate, and has mild conditions, resulting in good economic benefits. Detailed Implementation

[0016] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0017] Example 1

[0018] This embodiment provides a two-component polyurethane waterproof coating, and the specific preparation method is as follows:

[0019] (1) Preparation of lignin oligomers:

[0020] In this embodiment, lignin-containing biomass materials are depolymerized using a deep eutectic solvent system to obtain lignin oligomers. The lignin-containing biomass material used is straw; the mass ratio of straw to deep eutectic solvent is 1:8. The deep eutectic solvent is a ternary deep eutectic solvent of choline chloride / 1,2,4-butanetriol / aluminum chloride. In this deep eutectic solvent, the molar ratio of choline chloride:1,2,4-butanetriol:aluminum chloride is 1:2:0.1.

[0021] Lignin oligomers are prepared by the following steps:

[0022] S1. Preparation of deep eutectic solvent: At 65°C, choline chloride, 1,2,4-butanetriol and aluminum chloride are mixed evenly according to the ratio until the mixture is transformed into a clear liquid in a molten state to obtain a deep eutectic solvent;

[0023] S2. Depolymerization and extraction: First, the straw is dried, then crushed and passed through a 60-mesh sieve. The sieved straw is then mixed evenly with the above-mentioned deep eutectic solvent and reacted at 120°C for 1 hour to obtain lignin oligomers. The number average molecular weight of this lignin oligomer is 3765.

[0024] (2) Preparation of two-component polyurethane waterproof coating

[0025] This two-component polyurethane waterproof coating comprises component A and component B, wherein the mass ratio of component A to component B is 10:1. The raw materials for preparing component A and component B include:

[0026] Component A: 90 parts lignin oligomer, 60 parts polyether polyol, 5 parts organosilicon modifier, 30 parts water-based solvent, 2 parts defoamer, 2 parts thickener, and 20 parts filler. The number average molecular weight of the polyether polyol is 6000, and the organosilicon modifier is a double-hydroxyl-terminated polyether modified silicone oil with a number average molecular weight of 3000.

[0027] Component B: 70 parts isocyanate curing agent and 4 parts catalyst; the isocyanate curing agent is isophorone diisocyanate.

[0028] This two-component polyurethane waterproof coating is prepared by the following steps:

[0029] First, mix all components of component A evenly, then mix component A and component B evenly to obtain a two-component polyurethane waterproof coating.

[0030] Example 2

[0031] This embodiment refers to the preparation method provided in Example 1 to prepare a two-component polyurethane waterproof coating. The difference between this embodiment and Example 1 is that the mass ratio of component A to component B is 15:1 during the preparation of the two-component polyurethane waterproof coating. The remaining raw material ratios and preparation methods are strictly consistent with those in Example 1.

[0032] Example 3

[0033] This embodiment refers to the preparation method provided in Example 1 to prepare a two-component polyurethane waterproof coating. The difference between this embodiment and Example 1 is that, in the process of preparing the two-component polyurethane waterproof coating, an equal mass of hydroxyl-terminated polyether modified silicone oil with a number average molecular weight of 2000 is used instead of the organosilicon modifier in Example 1. The remaining raw material ratios and preparation methods are strictly consistent with those in Example 1.

[0034] Example 4

[0035] This embodiment refers to the preparation method provided in Example 1 to prepare a two-component polyurethane waterproof coating. The difference between this embodiment and Example 1 is that, in the process of preparing the two-component polyurethane waterproof coating, an equal mass of double-terminated hydroxyl polyether modified silicone oil with a number average molecular weight of 4000 is used instead of the organosilicon modifier in Example 1. The remaining raw material ratios and preparation methods are strictly consistent with those in Example 1.

[0036] Example 5

[0037] This embodiment refers to the preparation method provided in Example 1 to prepare a two-component polyurethane waterproof coating. The difference between this embodiment and Example 1 is that in the preparation of the two-component polyurethane waterproof coating, component A includes 60 parts of lignin oligomer and 60 parts of polyether polyol, making the ratio of lignin oligomer to polyether polyol 1:1. The remaining raw material ratios and preparation methods are strictly consistent with those in Example 1.

[0038] Example 6

[0039] This embodiment refers to the preparation method provided in Example 1 to prepare a two-component polyurethane waterproof coating. The difference between this embodiment and Example 1 is that, in the process of preparing the lignin oligomer, an equal mass of choline chloride / 1,2,4-butanetriol binary eutectic solvent is used instead of the eutectic solvent used in Example 1. Specifically, the addition of aluminum chloride is omitted in the preparation of the eutectic solvent. The remaining raw material ratios and preparation methods are strictly consistent with those of Example 1.

[0040] Example 7

[0041] This embodiment refers to the preparation method provided in Example 1 to prepare a two-component polyurethane waterproof coating. The difference between this embodiment and Example 1 is that in the process of preparing the lignin oligomer, an equal mass of ternary deep eutectic solvent of choline chloride / glycerol / aluminum chloride is used instead of the deep eutectic solvent used in Example 1. Specifically, in the preparation of the deep eutectic solvent, an equal mass of glycerol is used instead of 1,2,4-butanetriol used in Example 1. The remaining raw material ratios and preparation methods are strictly consistent with those of Example 1.

[0042] Example 8

[0043] This embodiment refers to the preparation method provided in Example 1 to prepare a two-component polyurethane waterproof coating. The difference between this embodiment and Example 1 is that the mass ratio of straw to deep eutectic solvent is adjusted to 1:5 during the preparation of lignin oligomers. The remaining raw material ratios and preparation methods are strictly consistent with those in Example 1.

[0044] Example 9

[0045] This embodiment refers to the preparation method provided in Example 1 to prepare a two-component polyurethane waterproof coating. The difference between this embodiment and Example 1 is that the mass ratio of straw to deep eutectic solvent is adjusted to 1:10 during the preparation of lignin oligomers. The remaining raw material ratios and preparation methods are strictly consistent with those in Example 1.

[0046] Example 10

[0047] This embodiment refers to the preparation method provided in Example 1 to prepare a two-component polyurethane waterproof coating. The difference between this embodiment and Example 1 is that the molar ratio of choline chloride, 1,2,4-butanetriol, and aluminum chloride is adjusted to 1:2:0.2 during the preparation of the deep eutectic solvent. The remaining raw material ratios and preparation methods are strictly consistent with those in Example 1.

[0048] Example 11

[0049] This embodiment refers to the preparation method provided in Example 1 to prepare a two-component polyurethane waterproof coating. The difference between this embodiment and Example 1 is that the molar ratio of choline chloride, 1,2,4-butanetriol, and aluminum chloride is adjusted to 1:1:0.1 during the preparation of the deep eutectic solvent. The remaining raw material ratios and preparation methods are strictly consistent with those in Example 1.

[0050] Comparative Example 1

[0051] This comparative example uses the preparation method provided in Example 1 to prepare a polyurethane coating. The difference between this comparative example and Example 1 is that, in the preparation of the two-component polyurethane waterproof coating, an equal mass of lignin oligomer is used instead of the polyether polyol used in Example 1. The remaining raw material ratios and preparation methods are strictly consistent with those of Example 1.

[0052] Comparative Example 2

[0053] This comparative example uses the preparation method provided in Example 1 to prepare a polyurethane coating. The difference between this comparative example and Example 1 is that, in the preparation of the two-component polyurethane waterproof coating, an equal mass of commercially available lignin is used instead of the lignin oligomer used in Example 1. The remaining raw material ratios and preparation methods are strictly consistent with those of Example 1.

[0054] Comparative Example 3

[0055] This comparative example uses the preparation method provided in Example 1 to prepare a polyurethane coating. The difference between this comparative example and Example 1 is that, in the preparation of the two-component polyurethane waterproof coating, an equal mass of polyether polyol is used instead of the lignin oligomer used in Example 1. The remaining raw material ratios and preparation methods are strictly consistent with those of Example 1.

[0056] Comparative Example 4

[0057] This comparative example uses the preparation method provided in Example 1 to prepare a polyurethane coating. The difference between this comparative example and Example 1 is that, in the preparation of the two-component polyurethane waterproof coating, an equal mass of silane coupling agent KH550 is used instead of the hydroxyl-terminated polyether modified silicone oil used in Example 1. The remaining raw material ratios and preparation methods are strictly consistent with those of Example 1.

[0058] Test case

[0059] Test subjects: Two-component polyurethane waterproof coatings provided in Examples 1-11 and polyurethane coatings provided in Comparative Examples 1-4.

[0060] Test items:

[0061] (1) Water resistance: The water resistance of the coating prepared by the test object was tested in accordance with GB / T 1733-1993 Test Method for Water Resistance of Coating.

[0062] (2) Hardness: The pencil hardness of the coating prepared by the test object was tested according to GB / T 6739-2006 Determination of Hardness of Coating by Pencil Method for Paints and Varnishes.

[0063] (3) Weather resistance: Refer to GB / T 1767-1979 Test method for weather resistance of coatings to test the weather resistance of the coatings prepared on the test objects.

[0064] (4) Stain resistance: Refer to GB / T 9780-2013 Test method for stain resistance of architectural coatings to test the stain resistance of the coatings prepared on the test objects.

[0065] Test results are shown in Table 1.

[0066] Table 1. Test performance of each test subject

[0067]

[0068]

[0069] Results analysis:

[0070] A comparison of the test performance of the two-component polyurethane waterproof coatings provided in Examples 1-11 and Comparative Examples 1-4 in Table 1 shows that the overall test performance of the coatings prepared in Examples 1-11 is better than that of the paint films prepared in Comparative Examples 1-6. Among them, the paint film provided in Example 1 has the best water resistance, hardness, weather resistance, and stain resistance.

[0071] The coatings obtained in Examples 1-11 were compared with those in Comparative Examples 1-2. In Comparative Example 1, the addition of lignin oligomers was omitted, while in Comparative Example 2, commercially available lignin was used. Compared to Comparative Examples 1-2, the coating film obtained in Example 1 exhibited higher hardness, better hydrophobicity, and better weather resistance. This demonstrates that using lignin oligomers with a number-average molecular weight of 3000-4000 to prepare a two-component polyurethane waterproof coating can result in a coating with excellent water resistance, hydrophobicity, and heat stability.

[0072] In Comparative Example 3, the polyurethane coating prepared by omitting the polyether polyol had excessive viscosity, causing it to transform from a liquid state into an unusable solid or semi-solid state, i.e., gelation occurred. However, this gelation phenomenon did not occur during the preparation processes of Examples 1-11, Comparative Examples 1-2, and Comparative Example 4. This indicates that in the preparation raw materials, lignin oligomers need to be combined with polyether polyols to form stable coatings and coatings.

[0073] Comparing the coatings obtained in Examples 1-11 with those in Comparative Example 4 in Table 1, the coatings provided in Examples 1-11 exhibit better water resistance and stain resistance compared to Comparative Example 4. This demonstrates that modifying the two-component polyurethane waterproof coating with a specific organosilicon modifier containing a dual-terminated hydroxyl polyether modified silicone oil can increase the coating's hydrophobicity, thereby improving its stain resistance.

[0074] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A two-component polyurethane waterproof coating, characterized in that, Calculated by weight parts, including: Component A: 40-90 parts lignin oligomer, 40-90 parts polyether polyol, 2-5 parts organosilicon modifier, and 20-40 parts aqueous solvent. The number average molecular weight of the lignin oligomer is 3000-4000. The lignin oligomer is obtained by depolymerizing lignin-containing biomass materials through a deep eutectic solvent system. The deep eutectic solvent is a ternary deep eutectic solvent of choline chloride / 1,2,4-butanetriol / aluminum chloride. The organosilicon modifier includes hydroxyl-terminated polyether modified silicone oil. Component B: 60-80 parts isocyanate curing agent, 1-5 parts catalyst; The mass ratio of component A to component B is 10-15:

1.

2. The two-component polyurethane waterproof coating as described in claim 1, characterized in that, The number-average molecular weight of the hydroxyl-terminated polyether modified silicone oil is 2000-4000, and the number-average molecular weight of the polyether polyol is 5000-7000.

3. The two-component polyurethane waterproof coating as described in claim 1, characterized in that, In component A, the ratio of lignin oligomer to polyether polyol is calculated by mass ratio as 1~1.5:

1.

4. The two-component polyurethane waterproof coating as described in claim 1, characterized in that, The isocyanate curing agent includes at least one of toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, and lysine diisocyanate.

5. The two-component polyurethane waterproof coating as described in claim 1, characterized in that, The lignin oligomer is prepared by the following steps: S1. Preparation of deep eutectic solvent: The choline chloride, the 1,2,4-butanetriol, and the aluminum chloride are mixed evenly at 60~70°C until the mixture is transformed into a clear liquid in a molten state to obtain the deep eutectic solvent; S2. Depolymerization and extraction: The lignin-containing biomass material is mixed evenly with the deep eutectic solvent and reacted at 100~130℃ for 1~3 hours to obtain the lignin oligomer.

6. The two-component polyurethane waterproof coating as described in claim 5, characterized in that, The mass ratio of the lignin-containing biomass material to the deep eutectic solvent is 1:5~10.

7. The two-component polyurethane waterproof coating as described in claim 5, characterized in that, In the deep eutectic solvent, the molar ratio of choline chloride, 1,2,4-butanetriol, and aluminum chloride is 1:2:0.05~0.

2.

8. The two-component polyurethane waterproof coating as described in any one of claims 1 to 7, characterized in that, The A component also includes 0.1 to 3 parts of defoamer, 0.1 to 3 parts of thickener, and 10 to 20 parts of filler.

9. The method for preparing the two-component polyurethane waterproof coating according to any one of claims 1 to 8, characterized in that, Includes the following steps: First, mix all components of component A evenly, then mix component A and component B evenly to obtain the two-component polyurethane waterproof coating.

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