A corrosion-resistant waterproof coating and its preparation process

Abstract

The present invention relates to the technical field of coatings, and discloses a corrosion-resistant waterproof coating and a preparation process thereof. The corrosion-resistant waterproof coating of the present invention comprises 70-77 parts by weight of waterborne polyurethane, 1-7 parts by weight of modified waterborne polyaniline, 15-22 parts by weight of filler, etc.; after polyaniline is doped with a sulfonic acid dopant, a polymer containing a carbamate group is introduced into the side chain, and hydrogen bonds interact with the carbamate group in the polyurethane to form a stable molecular chain hydrogen bond network, thereby increasing the crosslinking degree of the polyurethane molecular chain, and improving the compatibility between polyaniline and polyurethane, which is beneficial to improving the mechanical properties of the paint film, and showing higher tensile strength and elongation at break. The modified waterborne polyaniline is uniformly dispersed in a polyurethane emulsion and a paint film thereof, significantly improving the salt spray resistance and anticorrosion performance of the polyurethane paint film, and having excellent waterproof performance.

Description

Technical Field

[0001] The invention relates to the technical field of coatings, in particular to a corrosion-resistant waterproof coating and a preparation process thereof. Background Art

[0002] Waterborne polyurethane coatings are green and environmentally friendly, have good film-forming properties, and excellent heat resistance. They are widely used in construction materials, the automotive industry, and mechanical equipment. However, due to their high hydrophilicity, waterborne polyurethanes will accelerate the addition of corrosive media such as water and salt into the film matrix, affecting the anti-corrosion properties of the coating. Adding conductive polymers, anti-corrosion fillers, etc. to waterborne polyurethanes can improve their anti-corrosion properties.

[0003] Polyaniline is a conductive polymer with excellent performance. After being doped with hydrochloric acid, dodecylbenzene sulfonic acid, etc., the conductive property becomes better, and the electrochemical anticorrosion performance of the material can be improved. Chinese patent CN109294423B discloses that ammonium persulfate, dodecylbenzene sulfonic acid, castor oil, epoxy acrylic resin, aniline, etc. are used as raw materials to prepare a nano polyaniline-epoxy acrylic resin mixture, which improves the crosslinking density, salt spray resistance, impact resistance and other properties of polyurethane coatings. However, polyaniline has poor water solubility, poor dispersibility in water-based coatings such as polyurethane, and is easy to agglomerate, affecting the mechanical and anticorrosion properties of the coating film. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a corrosion-resistant waterproof coating and a preparation process thereof, which solves the problem of poor anti-corrosion performance of polyurethane coatings and improves the waterproof performance of the coatings.

[0005] The invention provides a corrosion-resistant waterproof coating, comprising 70-77 parts by weight of waterborne polyurethane, 1-7 parts by weight of modified waterborne polyaniline, 15-22 parts by weight of filler, 1.2-2 parts by weight of dispersant, 0.4-1 parts by weight of defoamer, 0.3-0.7 parts by weight of leveling agent and 1.3-1.8 parts by weight of thickener.

[0006] The preparation process of the corrosion-resistant waterproof coating is as follows: adding waterborne polyurethane, modified waterborne polyaniline, filler, dispersant, defoamer, leveling agent and thickener into a container, stirring and mixing, and obtaining the corrosion-resistant waterproof coating.

[0007] Preferably, the filler is mica powder or titanium dioxide.

[0008] Preferably, the preparation process of modified waterborne polyaniline is:

[0009] (1) Add 1,2-dihydroxy-3-propanesulfonic acid, diisocyanate monomer, and dibutyltin dilaurate to acetone, stir and react in a nitrogen atmosphere, concentrate under reduced pressure, and dry to obtain a sulfonic acid dopant. The reaction formula is:

[0010] .

[0011] (2) Add sulfonic acid dopant and aniline to water, stir and then drop an aqueous solution of ammonium persulfate, stir to react, dry to remove water, wash with ethanol, and dry to obtain modified waterborne polyaniline. The structural formula is:

[0012] .

[0013] Preferably, in (1), the amount of 1,2-dihydroxy-3-propanesulfonic acid is 100 parts by weight, the amount of diisocyanate monomer is 108-143 parts by weight, and the amount of dibutyltin dilaurate is 0.15-0.18 parts by weight.

[0014] Preferably, the diisocyanate monomer is isophorone diisocyanate, toluene-2,4-diisocyanate or hexamethylene diisocyanate.

[0015] Preferably, in (1), the reaction temperature is 55-60°C and the reaction time is 3-5h.

[0016] Preferably, in (2), the amount of aniline is 100 parts by weight, the amount of sulfonic acid dopant is 280-440 parts by weight, and the amount of ammonium persulfate is 122-184 parts by weight.

[0017] Preferably, in (2), the reaction temperature is 0-5°C and the reaction time is 8-10h.

[0018] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0019] 1. The present invention conducts polymerization reaction on 1,2-dihydroxy-3-propanesulfonic acid, toluene-2,4-diisocyanate, etc. to obtain a sulfonic acid dopant, and dopes polyaniline to obtain modified waterborne polyaniline. The side chain of the sulfonic acid dopant contains a large number of sulfonic acid groups, and a part of the sulfonic acid groups interact electrostatically with the N positive ions of the polyaniline to form a doping effect, so that the sulfonic acid dopant molecular chain is modified to the side chain of the polyaniline, and the sulfonic acid groups that do not undergo doping give the polyaniline excellent water solubility, so that the polyaniline has better practical application in waterborne coatings.

[0020] 2. The present invention mixes waterborne polyurethane, modified waterborne polyaniline, mica powder and other fillers to obtain a corrosion-resistant waterproof coating. The modified waterborne polyaniline has good water solubility and is evenly dispersed in the polyurethane aqueous emulsion, thereby avoiding the poor dispersibility of polyaniline in water, the agglomeration phenomenon, and the influence of the mechanical properties of the paint film.

[0021] 3. After the polyaniline of the present invention is doped with a sulfonic acid dopant, a polymer containing a carbamate group is introduced into the side chain, which interacts with the carbamate group in the polyurethane by hydrogen bonding to form a stable molecular chain hydrogen bond network, thereby increasing the crosslinking degree of the polyurethane molecular chain and improving the compatibility between the polyaniline and the polyurethane, which is beneficial to improving the mechanical properties of the paint film and exhibiting higher tensile strength and elongation at break.

[0022] 4. The modified waterborne polyaniline of the present invention is uniformly dispersed in the polyurethane emulsion and its paint film, which significantly improves the salt spray resistance and corrosion resistance of the polyurethane paint film and has excellent waterproof performance. DETAILED DESCRIPTION

[0023] The present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0024] The following waterborne polyurethane, model HBHK-1007, water emulsion, solid content 50%, Guangzhou Black Panther Waterproof Building Materials Co., Ltd. Thickener, model SN-THCKENER 612, Guangzhou Chengzhenhao Trading Co., Ltd. Sodium polystyrene sulfonate, CAS No. 25704-18-1, Kangdisi Chemical (Hubei) Co., Ltd.

[0025] Example 1

[0026] (1) Add 10 g of 1,2-dihydroxy-3-propanesulfonic acid, 11.2 g of toluene-2,4-diisocyanate, and 16 mg of dibutyltin dilaurate to 150 mL of acetone, stir and reflux the mixture at 60° C. in a nitrogen atmosphere for 3 h, concentrate under reduced pressure, and dry to obtain a sulfonic acid dopant.

[0027] (2) Add 14 g of sulfonic acid dopant and 5 g of aniline to 500 mL of water, stir at 0°C, then drop 40 mL of an aqueous solution containing 7.8 g of ammonium persulfate, stir for 10 h, dry to remove water, wash with ethanol, and dry to obtain modified waterborne polyaniline.

[0028] (3) Add 760g of waterborne polyurethane, 10g of modified waterborne polyaniline, 180g of filler mica powder, 20g of dispersant BASF Disponil A 1080, 8g of defoamer TEGO-825, 7g of leveling agent TEGO-2300, and 15g of thickener into the container, stir and mix well to obtain a corrosion-resistant waterproof coating.

[0029] Example 2

[0030] (1) Add 10 g of 1,2-dihydroxy-3-propanesulfonic acid, 10.8 g of hexamethylene diisocyanate, and 18 mg of dibutyltin dilaurate to 200 mL of acetone, stir and reflux at 55° C. in a nitrogen atmosphere for 5 h, concentrate under reduced pressure, and dry to obtain a sulfonic acid dopant.

[0031] (2) Add 18 g of sulfonic acid dopant and 5 g of aniline to 600 mL of water, stir at 5 °C, then drop 40 mL of an aqueous solution containing 6.1 g of ammonium persulfate, stir and react for 10 h, dry to remove water, wash with ethanol, and dry to obtain modified waterborne polyaniline.

[0032] (3) Add 709 g of waterborne polyurethane, 25 g of modified waterborne polyaniline, 220 g of filler mica powder, 20 g of dispersant BASF Disponil A 1080, 10 g of defoamer TEGO-825, 3 g of leveling agent TEGO-2300, and 13 g of thickener into the container, stir and mix well to obtain a corrosion-resistant waterproof coating.

[0033] Example 3

[0034] (1) Add 10 g of 1,2-dihydroxy-3-propanesulfonic acid, 14.3 g of isophorone diisocyanate, and 15 mg of dibutyltin dilaurate to 200 mL of acetone, stir and reflux at 55° C. in a nitrogen atmosphere for 5 h, concentrate under reduced pressure, and dry to obtain a sulfonic acid dopant.

[0035] (2) Add 22 g of sulfonic acid dopant and 5 g of aniline to 600 mL of water, stir at 5 °C, then drop 40 mL of an aqueous solution containing 9.2 g of ammonium persulfate, stir and react for 8 h, dry to remove water, wash with ethanol, and dry to obtain modified waterborne polyaniline.

[0036] (3) Add 770 g of waterborne polyurethane, 40 g of modified waterborne polyaniline, 150 g of filler titanium dioxide, 12 g of dispersant BASF Disponil A 1080, 4 g of defoamer TEGO-825, 6 g of leveling agent TEGO-2300, and 18 g of thickener into the container, stir and mix well to obtain a corrosion-resistant waterproof coating.

[0037] Example 4

[0038] (1) Add 715 g of waterborne polyurethane, 55 g of modified waterborne polyaniline (prepared by the same process as in Example 1), 180 g of filler mica powder, 20 g of dispersant BASF Disponil A 1080, 8 g of defoamer TEGO-825, 7 g of leveling agent TEGO-2300, and 15 g of thickener into a container, stir and mix to obtain a corrosion-resistant waterproof coating.

[0039] Example 5

[0040] (1) Add 700 g of waterborne polyurethane, 70 g of modified waterborne polyaniline (prepared by the same process as in Example 1), 180 g of filler mica powder, 20 g of dispersant BASF Disponil A 1080, 8 g of defoamer TEGO-825, 7 g of leveling agent TEGO-2300, and 15 g of thickener into a container, stir and mix to obtain a corrosion-resistant waterproof coating.

[0041] Comparative Example 1

[0042] (1) Add 760g of waterborne polyurethane, 180g of filler mica powder, 20g of dispersant BASF Disponil A 1080, 8g of defoamer TEGO-825, 7g of leveling agent TEGO-2300, and 15g of thickener into a container, stir and mix well to obtain a corrosion-resistant waterproof coating.

[0043] Comparative Example 2

[0044] (1) Add 14 g of dodecylbenzenesulfonic acid and 5 g of aniline to 600 mL of water, stir at 0°C, then drop 40 mL of an aqueous solution containing 7.8 g of ammonium persulfate, stir for 10 h, dry to remove water, wash with ethanol, and dry to obtain polyaniline.

[0045] (2) Add 760g of waterborne polyurethane, 10g of polyaniline, 180g of filler mica powder, 20g of dispersant BASF Disponil A 1080, 8g of defoamer TEGO-825, 7g of leveling agent TEGO-2300, and 15g of thickener into a container, stir and mix well to obtain a corrosion-resistant waterproof coating.

[0046] Comparative Example 3

[0047] (1) Add 14 g of sodium polystyrene sulfonate to 600 mL of water, add concentrated hydrochloric acid to adjust the pH to 6.5, add 5 g of aniline, stir at 0°C, then add 40 mL of an aqueous solution containing 7.8 g of ammonium persulfate, stir for 10 h, dry to remove water, wash with ethanol, and dry to obtain modified water-based polyaniline.

[0048] (2) Add 760g of waterborne polyurethane, 10g of modified waterborne polyaniline, 180g of filler mica powder, 20g of dispersant BASF Disponil A 1080, 8g of defoamer TEGO-825, 7g of leveling agent TEGO-2300, and 15g of thickener into a container, stir and mix well to obtain a corrosion-resistant waterproof coating.

[0049] 10 g of the modified waterborne polyaniline prepared in Examples 1-3, the polyaniline prepared in Comparative Example 2, and the modified waterborne polyaniline prepared in Comparative Example 3 were respectively weighed and added into 300 mL of water, stirred for 2 h, and allowed to stand for 72 h to observe the dispersion of the solution.

[0050] Table 1 Dispersion of polyaniline solution

[0051]

[0052] After the polyaniline prepared in Examples 1-3 is treated with the sulfonic acid dopant, its hydrophilicity becomes better, its water solubility increases, and there is no precipitate in the aqueous solution. This is mainly because the side chains of the sulfonic acid dopant contain a large number of sulfonic acid groups, and a part of the sulfonic acid groups interact electrostatically with the NH bonds of the polyaniline to form a doping effect, so that the sulfonic acid dopant molecular chain is modified to the side chain of the polyaniline. The sulfonic acid groups that do not undergo doping give the polyaniline excellent water solubility, so that the polyaniline has better practical application in water-based coatings.

[0053] In Comparative Example 2, conventional dodecylbenzene sulfonic acid is used to dope polyaniline. Polyaniline has poor water solubility and is prone to produce precipitates, which is not conducive to the practical application of polyaniline in water-based coatings.

[0054] Comparative Example 3: Polyaniline was doped with acidified sodium polystyrene sulfonate, and the water solubility of polyaniline became better. However, there was still a small amount of precipitate, which may be because its main chain was a polystyrene molecular chain with greater hydrophobicity.

[0055] The coating was dried at 90°C for 10 hours to form a paint film. The salt spray resistance of the paint film was tested according to the method of GB / T 1771-2007.

[0056] Test the tensile strength of the cured coating film according to GB / T 528-2009 method. Test three times and take the average value.

[0057] The cured coating film is dried, weighed, and then soaked in water for 24 hours. After taking it out, wipe off the residual water on the surface, weigh it, and calculate the water absorption rate W. W = (m-m0) / m0×100%. m is the mass after water absorption, and m0 is the mass before water absorption.

[0058] Table 2 Coating performance test

[0059]

[0060] After testing, compared with Comparative Example 1, the modified water-based polyaniline is added to the polyurethane water-based coating of Examples 1-5, and the water-based polyaniline has good water solubility and is evenly dispersed in the polyurethane aqueous emulsion, avoiding the poor dispersibility of polyaniline in water, agglomeration, and affecting the mechanical properties of the paint film. At the same time, after the polyaniline is doped with a sulfonic acid dopant, a polymer containing a carbamate group is introduced into the side chain, and hydrogen bonds interact with the carbamate group in the polyurethane to form a stable molecular chain hydrogen bond network, increase the crosslinking degree of the polyurethane molecular chain, and improve the compatibility between polyaniline and polyurethane, which is beneficial to improve the mechanical properties of the paint film, showing higher tensile strength and elongation at break. At the same time, the evenly dispersed polyaniline significantly improves the salt spray resistance and anti-corrosion performance of the polyurethane paint film. Moreover, the water absorption rate of the polyurethane paint films of Examples 1-3 is lower and the waterproof property is improved. This may be because the addition of an appropriate amount of modified water-based polyaniline increases the molecular chain crosslinking degree of the polyurethane paint film and increases the cohesive force, which can inhibit water molecules from entering the paint film, thereby reducing the water absorption rate. However, when an excessive amount of hydrophilic modified water-based polyaniline is added, the hydrophilicity of the paint film increases and the water absorption rate increases.

[0061] In Comparative Example 2, polyaniline is doped with dodecylbenzenesulfonic acid. Polyaniline has poor water solubility and poor dispersibility in aqueous polyurethane emulsion. It is easy to agglomerate, which will affect the mechanical properties and anti-corrosion properties of the paint film, reduce tensile strength and elongation at break, and deteriorate salt spray resistance.

[0062] In Comparative Example 3, acidified sodium polystyrene sulfonate is used to dope polyaniline. Sodium polystyrene sulfonate does not contain carbamate groups, and its hydrogen bond interaction with polyurethane is weak. A stable molecular chain hydrogen bond network is not formed, and the compatibility between polyaniline and polyurethane is not improved, resulting in low tensile strength and elongation at break of the paint film.

[0063] The present invention is not limited to the above-mentioned embodiments. Without departing from the essential content of the present invention, any deformation, improvement and substitution that can be thought of by those skilled in the art shall fall within the scope of the present invention.

[0064] The present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

Claims

1. A corrosion-resistant waterproof coating, characterized in that: The corrosion-resistant waterproof coating comprises 70-77 parts by weight of waterborne polyurethane, 1-7 parts by weight of modified waterborne polyaniline, 15-22 parts by weight of filler, 1.2-2 parts by weight of dispersant, 0.4-1 parts by weight of defoamer, 0.3-0.7 parts by weight of leveling agent, and 1.3-1.8 parts by weight of thickener; The preparation process of the modified waterborne polyaniline is: (1) Add 1,2-dihydroxy-3-propanesulfonic acid, diisocyanate monomer, and dibutyltin dilaurate to acetone, stir and react in a nitrogen atmosphere, concentrate under reduced pressure, and dry to obtain a sulfonic acid dopant; (2) Add sulfonic acid dopant and aniline to water, add aqueous solution of ammonium persulfate dropwise after stirring, stir to react, dry to remove water, wash with ethanol, and dry to obtain modified waterborne polyaniline.

2. The corrosion-resistant waterproof coating according to claim 1, characterized in that: In the above (1), the amount of 1,2-dihydroxy-3-propanesulfonic acid is 100 parts by weight, the amount of diisocyanate monomer is 108-143 parts by weight, and the amount of dibutyltin dilaurate is 0.15-0.18 parts by weight.

3. The corrosion-resistant waterproof coating according to claim 1, characterized in that: The diisocyanate monomer is isophorone diisocyanate, toluene-2,4-diisocyanate or hexamethylene diisocyanate.

4. The corrosion-resistant waterproof coating according to claim 1, characterized in that: In the above (1), the reaction temperature is 55-60°C and the reaction time is 3-5h.

5. The corrosion-resistant waterproof coating according to claim 1, characterized in that: In the above (2), the amount of aniline used is 100 parts by weight, the amount of sulfonic acid dopant used is 280-440 parts by weight, and the amount of ammonium persulfate used is 122-184 parts by weight.

6. The corrosion-resistant waterproof coating according to claim 1, characterized in that: In the above (2), the reaction temperature is 0-5°C and the reaction time is 8-10h.

7. The corrosion-resistant waterproof coating according to claim 1, characterized in that: The filler is mica powder or titanium dioxide.

8. A process for preparing the corrosion-resistant waterproof coating according to any one of claims 1 to 7, characterized in that: The preparation process comprises the following steps: adding waterborne polyurethane, modified waterborne polyaniline, filler, dispersant, defoamer, leveling agent and thickener into a container, stirring and mixing the mixture to obtain the corrosion-resistant waterproof coating.

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