A hydrophobic antifouling coating and preparation method thereof

Abstract

The present invention relates to the field of coating technology, and discloses a kind of hydrophobic antifouling coating and preparation method thereof, the hydrophobic antifouling coating of the present invention includes 100 parts by weight of polyurethane emulsion, 30-50 parts by weight of modified titanium dioxide, 0.7-1.2 parts by weight of defoamer;Styrene-based functional monomer and KH570 modified titanium dioxide are subjected to graft polymerization reaction, hydrophobic hydrogenated phenanthrene ring condensed ring and polystyrene molecular chain are introduced on titanium dioxide surface, added to polyurethane, significantly improve the hydrophobicity of paint film.And nano titanium dioxide is after modification, dispersibility becomes better, is evenly dispersed in polyurethane paint film, forms micro-nano convex structure on paint film surface, makes paint film show super hydrophobic characteristic under synergistic effect, and water absorption is very low, is conducive to improving the waterproof and antifouling performance of coating.

Description

Technical Field

[0001] The invention relates to the technical field of coatings, in particular to a hydrophobic antifouling coating and a preparation method thereof. Background Art

[0002] Superhydrophobic material is a new type of material with strong hydrophobicity and self-cleaning properties, and has broad application prospects in waterproofing, anti-fouling, anti-corrosion, and oil pipeline transportation. Polyurethane coatings have high mechanical properties, good wear resistance, and excellent anti-corrosion properties. They are widely used in road traffic, roof waterproofing, building materials and facilities. Traditional polyurethane coatings do not have superhydrophobic and self-cleaning properties, and have poor waterproof and anti-fouling properties.

[0003] Fillers such as nano titanium dioxide are added to coatings such as polyurethane, and micro-nano structures are formed on the surface of the paint film, while reducing the low surface energy of the paint film, so that the paint film can be formed into super-hydrophobic properties. Nano titanium dioxide is easily agglomerated, and has poor dispersibility in coatings, and it is impossible to effectively give the coating super-hydrophobic properties. The Chinese invention patent publication with the announcement number CN108753132B discloses a method for preparing a road super-hydrophobic ice-suppressing coating, and nano titanium dioxide is treated with low surface energy structure reorganization using stearic acid and ethanol, and then compounded with silicone oil-based polyurethane, and the coating obtained has super-hydrophobic and ice-suppressing effects. However, it is usually necessary to add fillers such as excessive nano titanium dioxide to give the coating good super-hydrophobic properties, and adding excessive nano fillers can reduce the mechanical properties of the coating. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention solves the problem that polyurethane coatings do not have super-hydrophobic and antifouling properties.

[0005] The invention provides a hydrophobic antifouling coating and a preparation method thereof. The hydrophobic antifouling coating comprises 100 parts by weight of a polyurethane emulsion with a curing amount of 50-60%, 30-50 parts by weight of modified titanium dioxide, and 0.7-1.2 parts by weight of a defoaming agent.

[0006] The preparation method comprises the following steps: adding polyurethane emulsion, modified titanium dioxide and defoaming agent into a container, stirring and mixing the mixture to obtain a hydrophobic antifouling coating.

[0007] Preferably, the preparation method of modified titanium dioxide is:

[0008] (1) Add N,N-didehydroabietylamine longitudinal alkyl diamine, 3-isopropyl-dimethylbenzyl isocyanate, and dibutyltin dilaurate to toluene, react at 15-25°C for 3-4 hours, and concentrate under reduced pressure. The product is recrystallized in chloroform to obtain a styrene-based functional monomer. The reaction formula is:

[0009] .

[0010] (2) Add KH570 modified nano titanium dioxide to toluene, add styrene-based functional monomer after stirring, add azobisisobutyronitrile dropwise in a nitrogen atmosphere, stir and react at 60-75°C for 18-24h, filter, wash with N,N-dimethylformamide and ethanol in turn, and dry to obtain modified titanium dioxide.

[0011] Preferably, the amount of N,N-didehydroabietylamine longitudinal alkyl diamine used is 100 parts by weight, 3-isopropyl-dimethylbenzyl isocyanate is 68-72 parts by weight, and dibutyltin dilaurate is 0.5-0.6 parts by weight.

[0012] Preferably, the amount of KH570 modified nano titanium dioxide is 100 parts by weight, the amount of styrene-based functional monomer is 8-20 parts by weight, and the amount of azobisisobutyronitrile is 0.006-0.02 parts by weight.

[0013] Preferably, the preparation method of KH570 modified nano titanium dioxide is: add ethanol to water, add ammonia water to adjust the pH to 9-9.5, then add 100 parts by weight of nano titanium dioxide, ultrasonically disperse for 10 minutes, then heat to 75-80°C, add 2-4 parts by weight of ethanol solution containing KH570, stir and condense reflux reaction for 1-3 hours, cool and stand for aging for 12 hours, filter, wash with ethanol, and dry to obtain KH570 modified nano titanium dioxide.

[0014] Beneficial technical effects:

[0015] The present invention uses the olefin group of KH570 modified titanium dioxide as a polymerization reaction, and grafts a polymerization reaction with a styrene-based functional monomer, introduces a hydrophobic hydrogenated phenanthrene ring condensed ring and a polystyrene molecular chain on the surface of the nano titanium dioxide, and adds them to the polyurethane, thereby significantly improving the hydrophobicity of the paint film. After the nano titanium dioxide is modified, the dispersibility becomes better, and it is evenly dispersed in the polyurethane paint film, forming a micro-nano protrusion structure on the surface of the paint film, and under the synergistic effect, the paint film exhibits super-hydrophobic characteristics, and the water absorption rate is very low, which is conducive to improving the waterproof and antifouling performance of the coating.

[0016] The polystyrene polymer molecular chain grafted on the surface of the nano-titanium dioxide of the present invention contains urea groups, which form hydrogen bonding forces with the urethane groups of the polyurethane, thereby increasing the interfacial forces between the nano-titanium dioxide and the polyurethane, and is beneficial to improving the mechanical properties of the paint film, with higher tensile strength and elongation at break. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] The following polyurethane emulsion, solid content 60%, model polyurethane 911, was purchased from Guangzhou Black Panther Waterproof Building Materials Co., Ltd. Nano titanium dioxide, average particle size 30nm.

[0019] Add 25 mL of ethanol to 25 mL of water, add ammonia water to adjust the pH to 9, then add 10 g of nano-titanium dioxide, ultrasonically disperse for 10 min, then heat to 80 ° C, add 10 mL of ethanol solution containing 0.25 g of KH570, stir and condense reflux reaction for 1.5 h, cool and let stand for 12 h, filter, wash with ethanol, and dry to obtain KH570 modified nano-titanium dioxide.

[0020] N,N-didehydroabietylamine longitudinal alkyl diamine was prepared according to the method of the journal Petrochemical Industry, Vol. 38, No. 6, 2009, in the document Synthesis and Properties of Rosin-Based Sulfonate Gemini Surfactants.

[0021] Add 20g (70mmol) dehydroabietylamine, 23.3mmol 1,2-dibromoethane, and 23.3mmol sodium carbonate to 60mL toluene, heat to 110°C, condense and reflux for 20h, cool and filter, wash the filter residue with methanol, then add it to chloroform, extract and wash with water, concentrate the chloroform organic phase under reduced pressure, purify with ether, filter, and dry to obtain N,N-didehydroabietylamine longitudinal ethylenediamine. The structural formula is: .

[0022] Add 20g (70mmol) dehydroabietylamine, 23.3mmol 1,8-dibromooctane, and 23.3mmol sodium carbonate to 60mL toluene, heat to 110°C, condense and reflux for 20h, filter after cooling, wash the filter residue with methanol, then add it to chloroform, extract and wash with water, concentrate the chloroform organic phase under reduced pressure, purify with ether, filter, and dry to obtain N,N-didehydroabietylamine octanediamine. The structural formula is: .

[0023] Example 1

[0024] (1) Add 10 g of N,N-didehydroabietylamine, 6.8 g of 3-isopropyl-dimethylbenzyl isocyanate, and 0.05 g of dibutyltin dilaurate to 100 mL of toluene, react at 25°C for 3 h, and concentrate under reduced pressure. The product is recrystallized in chloroform to obtain a styrene-based functional monomer. The structural formula is as follows:

[0025] .

[0026] (2) Add 50 g of KH570 modified nano titanium dioxide to 700 mL of toluene, add 4 g of styrene-based functional monomer after stirring, add 3 mg of azobisisobutyronitrile dropwise in a nitrogen atmosphere, stir and react at 65 °C for 18 h, filter, wash with N,N-dimethylformamide and ethanol in turn, and dry to obtain modified titanium dioxide.

[0027] (3) Add 1000 g of polyurethane emulsion, 300 g of modified titanium dioxide, and 8 g of defoaming agent TEGO-825 into a container and stir to mix well to obtain a hydrophobic antifouling coating.

[0028] Example 2

[0029] (1) Add 10 g of N,N-didehydroabietylamine octanediamine, 7.2 g of 3-isopropyl-dimethylbenzyl isocyanate, and 0.06 g of dibutyltin dilaurate to 100 mL of toluene, react at 15°C for 4 h, and concentrate under reduced pressure. The product is recrystallized in chloroform to obtain a styrene-based functional monomer. The reaction formula is:

[0030] .

[0031] (2) Add 50 g of KH570 modified nano titanium dioxide to 900 mL of toluene, add 5.5 g of styrene-based functional monomer after stirring, add 5 mg of azobisisobutyronitrile dropwise in a nitrogen atmosphere, stir and react at 75 °C for 18 h, filter, wash with N,N-dimethylformamide and ethanol in turn, and dry to obtain modified titanium dioxide.

[0032] (3) Add 1000 g of polyurethane emulsion, 350 g of modified titanium dioxide, and 7 g of defoaming agent TEGO-825 into a container and stir to mix well to obtain a hydrophobic antifouling coating.

[0033] Example 3

[0034] (1) Add 50 g of KH570 modified nano titanium dioxide to 800 mL of toluene, stir and add 7.2 g of styrene-based functional monomer (prepared in the same manner as in Example 1), dropwise add 7 mg of azobisisobutyronitrile in a nitrogen atmosphere, stir and react at 60 ° C for 24 h, filter, wash with N, N-dimethylformamide and ethanol in turn, and dry to obtain modified titanium dioxide.

[0035] (2) Add 1000 g of polyurethane emulsion, 400 g of modified titanium dioxide, and 7 g of defoaming agent TEGO-825 into a container and stir to obtain a hydrophobic antifouling coating.

[0036] Example 4

[0037] (1) Add 50 g of KH570 modified nano titanium dioxide to 900 mL of toluene, stir and add 8.6 g of styrene-based functional monomer (prepared in the same manner as in Example 1), dropwise add 8.3 mg of azobisisobutyronitrile in a nitrogen atmosphere, stir and react at 75 °C for 18 h, filter, wash with N,N-dimethylformamide and ethanol in turn, and dry to obtain modified titanium dioxide.

[0038] (2) Add 1000 g of polyurethane emulsion, 450 g of modified titanium dioxide, and 12 g of defoaming agent TEGO-825 into a container and stir to mix well to obtain a hydrophobic antifouling coating.

[0039] Example 5

[0040] (1) Add 50 g of KH570 modified nano titanium dioxide to 900 mL of toluene, stir and add 10 g of styrene-based functional monomer (prepared in the same manner as in Example 1), add 10 mg of azobisisobutyronitrile dropwise in a nitrogen atmosphere, stir and react at 70 ° C for 24 h, filter, wash with N, N-dimethylformamide and ethanol in turn, and dry to obtain modified titanium dioxide.

[0041] (2) Add 1000 g of polyurethane emulsion, 500 g of modified titanium dioxide, and 10 g of defoaming agent TEGO-825 into a container and stir to obtain a hydrophobic antifouling coating.

[0042] Comparative Example 1

[0043] (1) Add 1000 g of polyurethane emulsion, 300 g of nano titanium dioxide, and 8 g of defoamer TEGO-825 into a container and stir to obtain a polyurethane coating.

[0044] Comparative Example 2

[0045] (1) Add 1000 g of polyurethane emulsion, 300 g of KH570 modified nano titanium dioxide, and 8 g of defoamer TEGO-825 into a container and stir to obtain a polyurethane coating.

[0046] Comparative Example 3

[0047] (1) Add 50g KH570 modified nano titanium dioxide to 700mL toluene, stir and add 4g divinylbenzene (structural formula: ), add 3 mg of azobisisobutyronitrile dropwise in a nitrogen atmosphere, stir and react at 65°C for 18 hours, filter, wash with N,N-dimethylformamide and ethanol in sequence, and dry to obtain modified titanium dioxide.

[0048] (2) Add 1000 g of polyurethane emulsion, 300 g of modified titanium dioxide, and 8 g of defoaming agent TEGO-825 into a container and stir to obtain a polyurethane coating.

[0049] The coating was poured into a mold and dried at 80°C for 6 h to form a paint film, and the water contact angle was tested according to GB / T 30693-2014.

[0050] The cured coating film was dried, weighed, and then immersed in water for 48 hours. After removal, the residual water on the surface was wiped off, weighed, and the water absorption rate W was calculated. W = (mm 0 ) / m 0 ×100%. m is the mass after absorbing water, m 0 It is the mass before water absorption.

[0051] The tensile properties of the cured coating film were tested according to the GB / T 528-2009 method, and the test was repeated three times to obtain the average value. The test results are shown in Table 1.

[0052] Table 1 Coating performance test

[0053]

[0054] After testing, the unmodified nano titanium dioxide added to the polyurethane coating of Comparative Example 1 is easy to agglomerate, has poor dispersibility in the polyurethane coating and paint film, is difficult to form a micro-nano protrusion structure, has a low water contact angle, does not reach the super-hydrophobic level, has a large water absorption rate, and has poor waterproof and antifouling properties. In addition, nano titanium dioxide has poor compatibility with polyurethane, has a great influence on the mechanical properties of the polyurethane film, and has low tensile strength and elongation at break.

[0055] Embodiment 1-5 utilizes styrene-based functional monomer to carry out graft polymerization modification on KH570 modified titanium dioxide, introduces hydrophobic hydrogenated phenanthrene ring condensed ring and polystyrene molecular chain on the surface of nano titanium dioxide, adds to polyurethane, significantly improves the hydrophobicity of paint film, at the same time, after modification, nano titanium dioxide has better dispersibility, is evenly dispersed in polyurethane paint film, forms micro-nano protrusion structure on the surface of paint film, makes paint film show super hydrophobic property under synergistic effect, water contact angle reaches 150.4-156.8°, and water absorption rate is very low, is conducive to improving the waterproof and antifouling performance of coating. At the same time, the polystyrene polymer molecular chain grafted on the surface of nano titanium dioxide contains urea group (-NH-CO-N-), forms hydrogen bond force with carbamate group (-NH-CO-O-) of polyurethane, can improve the interface force between nano titanium dioxide and polyurethane, is conducive to improving the mechanical properties of paint film, has higher tensile strength and elongation at break.

[0056] Compared with Example 1, Comparative Example 2 added KH570 modified titanium dioxide, and the dispersibility in polyurethane became better, but the water contact angle of the coating film was only 128.7°C, which did not reach the super hydrophobic level, and the waterproof and antifouling performance was poor.

[0057] Compared with Example 1, Comparative Example 3 uses divinylbenzene to graft-modify KH570 modified titanium dioxide, and does not introduce hydrophobic hydrogenated phenanthrene ring condensed rings on the surface of nano-titanium dioxide, resulting in a low water contact angle of the paint film, which does not reach the super-hydrophobic level, and the grafted polystyrene polymer molecular chain does not contain urea groups, which makes it difficult to form hydrogen bonding forces with polyurethane, and cannot improve the interfacial force between nano-titanium dioxide and polyurethane, resulting in the tensile strength and elongation at break of the paint film being lower than those in Example 1.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A hydrophobic antifouling coating, characterized in that: The hydrophobic antifouling coating comprises 100 parts by weight of polyurethane emulsion, 30-50 parts by weight of modified titanium dioxide, and 0.7-1.2 parts by weight of defoaming agent; The preparation method of the modified titanium dioxide is as follows: adding KH570 modified nano titanium dioxide to toluene, adding styrene functional monomer after stirring, adding azobisisobutyronitrile dropwise in a nitrogen atmosphere, stirring for reaction, filtering, washing, and drying to obtain the modified titanium dioxide; The structural formula of the styrene-based functional monomer is as follows: , n is any integer from 1 to 4.

2. The hydrophobic antifouling coating according to claim 1, characterized in that: The reaction temperature is 60-75°C and the reaction time is 18-24h.

3. The hydrophobic antifouling coating according to claim 1, characterized in that: The amount of the KH570 modified nano titanium dioxide is 100 parts by weight, the amount of the styrene-based functional monomer is 8-20 parts by weight, and the amount of azobisisobutyronitrile is 0.006-0.02 parts by weight.

4. The hydrophobic antifouling coating according to claim 1, characterized in that: The preparation method of the styrene-based functional monomer comprises: adding N,N-didehydroabietylamine longitudinal alkyl diamine, 3-isopropyl-dimethylbenzyl isocyanate and dibutyltin dilaurate to toluene, and concentrating under reduced pressure after the reaction, and recrystallizing the product in chloroform to obtain the styrene-based functional monomer; The structural formula of the N,N-didehydroabietylamine longitudinal alkyl diamine is as follows: , n is any integer from 1 to 4.

5. The hydrophobic antifouling coating according to claim 4, characterized in that: The dosage of the N,N-didehydroabietylamine longitudinal alkyl diamine is 100 parts by weight, the dosage of 3-isopropyl-dimethylbenzyl isocyanate is 68-72 parts by weight, and the dosage of dibutyltin dilaurate is 0.5-0.6 parts by weight.

6. The hydrophobic antifouling coating according to claim 4, characterized in that: In the preparation method of the styrene-based functional monomer, the reaction temperature is 15-25° C. and the reaction time is 3-4 hours.

7. The hydrophobic antifouling coating according to claim 1, characterized in that: The preparation method of the KH570 modified nano titanium dioxide is as follows: adding ethanol to water, dripping ammonia water, then adding nano titanium dioxide, ultrasonically dispersing, dripping an ethanol solution containing KH570, stirring and condensing and refluxing, cooling and standing for aging, filtering, washing, and drying to obtain the KH570 modified nano titanium dioxide.

8. The hydrophobic antifouling coating according to claim 7, characterized in that: In the preparation method of KH570 modified nano titanium dioxide, washing includes washing with ethanol.

9. A method for preparing a hydrophobic antifouling coating according to any one of claims 1 to 8, characterized in that: The preparation method comprises the following steps: adding polyurethane emulsion, modified titanium dioxide and defoaming agent into a container, stirring and mixing the mixture to obtain a hydrophobic antifouling coating.

Images