A coating containing a modified molecular sieve, and a method for preparing and using the same

Abstract

The application relates to the technical field of paint, and discloses a paint containing modified molecular sieves, a preparation method and application thereof. The paint contains 100 parts of water-based polyurethane emulsion, 1.5-35 parts by weight of modified molecular sieves and the like. After the 4A molecular sieve is modified, the surface hydrophilicity is improved, the moisture absorption performance of the molecular sieve is improved, the molecular sieve is uniformly dispersed in the water-based polyurethane emulsion and the paint film, there are more moisture absorption sites, and the moisture absorption rate of the paint film is improved. Nitrogen-containing heterocyclic rings and a large number of hydroxyl groups and sulfonate groups are introduced on the surface of the molecular sieve, strong coordination forces are formed between the molecular sieve and the surface of a substrate such as a tinplate or an aluminum plate, the adhesion of the paint film to the substrate is improved, and the adhesion between the paint and the substrate is improved.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to a coating containing modified molecular sieves, its preparation method, and its application. Background Technology

[0002] Polyurethane coatings possess high toughness, excellent corrosion resistance, and superior wear resistance, making them widely used in air conditioning, dehumidification and refrigeration equipment, furniture, and appliances. However, ordinary polyurethane coatings suffer from poor mechanical strength and lack dehumidification capabilities, limiting their practical applications.

[0003] Molecular sieves are porous aluminosilicate materials with high mechanical strength and excellent adsorption properties, making them widely used in dehumidification, adsorption, and catalysis. However, molecular sieves have poor surface hydrophilicity, resulting in poor dispersibility in water-based coatings and poor compatibility with polymer resins. Patent application CN119039555A discloses a molecular sieve polyurethane composite material with excellent sound insulation properties and its preparation method. This method involves adsorbing an epoxy coupling agent into the pores of the molecular sieve and then grafting amino groups onto the outside of the pores, improving the compatibility between polyurethane and the molecular sieve and enhancing the mechanical and sound absorption properties of the polyurethane. However, this molecular sieve does not improve the hygroscopic properties of the polyurethane, which is detrimental to the application of polyurethane coatings in dehumidifier rotors, air conditioners, and other dehumidification and refrigeration equipment. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a coating containing modified molecular sieves, its preparation method, and its application, solving the problems of poor adhesion and moisture absorption properties of polyurethane coatings.

[0005] The technical solution of this invention is as follows: a coating containing modified molecular sieves and a preparation method thereof, comprising, by weight, 100 parts of aqueous polyurethane emulsion, 1.5-35 parts by weight of modified molecular sieves, and 0.2-0.5 parts by weight of leveling agent. The preparation method is as follows: the modified molecular sieves and leveling agent are added to the aqueous polyurethane emulsion, and the mixture is sheared and dispersed in a high-speed shear mill to obtain the coating containing modified molecular sieves.

[0006] The preparation method of modified molecular sieves is as follows:

[0007] (1) Add 4A molecular sieve to the solvent, disperse by ultrasonication, then add γ-chloropropyltrimethoxysilane and water, heat to the reaction temperature, stir the reaction and filter, wash with ethanol, dry to obtain chloropropyl molecular sieve.

[0008] (2) Add chloropropyl molecular sieve to ethanol, disperse by ultrasonication, then add tris(2-hydroxypropylaminoethanesulfonate), sodium hydroxide and water, heat to the reaction temperature, stir the reaction and filter, wash with water and ethanol, dry to obtain modified molecular sieve.

[0009] Preferably, the solvent in (1) is toluene or xylene.

[0010] Preferably, the ratio of 4A molecular sieve and γ-chloropropyltrimethoxysilane in (1) is 100g:(50-200)g.

[0011] Preferably, the reaction temperature in (1) is 60-90℃ and the reaction time is 12-18h.

[0012] Preferably, the reaction temperature in (2) is 70-80℃ and the reaction time is 12-24h.

[0013] Preferably, in (2), the ratio of chloropropyl molecular sieve, sodium isocyanurate tris(2-hydroxypropylaminoethanesulfonate) and sodium hydroxide is 100g:(30-150)mmol:(36-195)mmol.

[0014] A preferred method for preparing tris(2-hydroxypropylaminoethanesulfonate) is as follows: water, sodium hydroxide in a molar ratio of (3.6-4.8):1:(3-3.3), triglycidyl isocyanate, and 2-aminoethanesulfonic acid are added to tetrahydrofuran. The mixture is stirred and reacted at 25-40°C for 6-10 hours. After filtration, the mixture is distilled under reduced pressure. The crude product is added to ethanol, stirred, filtered, and the filtrate is heated to evaporate. After cooling and crystallization, tris(2-hydroxypropylaminoethanesulfonate) is obtained.

[0015] Preferably, coatings containing modified molecular sieves are used in dehumidifier rotors.

[0016] The beneficial technical effects of this invention are as follows: 4A molecular sieves are surface-modified using γ-chloropropyltrimethoxysilane. The introduced chloropropyl groups then react with the imino group of tris(2-hydroxypropylaminoethanesulfonate) isocyanurate to obtain a modified molecular sieve. Finally, this modified sieve is blended with an aqueous polyurethane emulsion to obtain a coating. The modified 4A molecular sieve surface incorporates a large number of hydrophilic hydroxyl and sulfonate groups, significantly improving its surface hydrophilicity and thus enhancing its dispersibility in aqueous emulsions. Furthermore, the introduced hydroxyl groups form hydrogen bonds and other interactions with the polyurethane, increasing the interfacial bonding and providing better reinforcement of the polyurethane, thereby improving the tensile properties of the coating film.

[0017] After modification, the molecular sieve of the present invention has better surface hydrophilicity, which is beneficial to improving the moisture absorption performance of the molecular sieve. It is also uniformly dispersed in the paint film and has more moisture absorption sites, which significantly improves the moisture absorption rate of the paint film.

[0018] This invention introduces nitrogen-containing heterocycles and a large number of hydroxyl and sulfonate groups on the surface of molecular sieves, forming strong coordination forces with the surfaces of substrates such as tinplate and aluminum plates, thereby improving the adhesion of the paint film to the substrate and thus enhancing the adhesion between the coating and the substrate. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] The following waterborne polyurethane emulsion has a solid content of approximately 45%, model number Weng Kai'er PU-YN, and is sourced from Weng Kai'er (Guangdong) Technology Co., Ltd. The 4A molecular sieve, with a particle size between 3-5mm, is sourced from Zhengzhou Jinbang Environmental Protection Technology Co., Ltd.

[0021] Example 1

[0022] (1) Add 80 mL of water, 0.48 mol of sodium hydroxide, 0.1 mol of triglycidyl isocyanate, and 0.3 mol of 2-aminoethanesulfonic acid to 200 mL of tetrahydrofuran. Stir the mixture at 40 °C for 6 h. After filtration, distill under reduced pressure. Add the crude product to ethanol, stir, and filter. Evaporate the filtrate by heating, and then cool to crystallize, yielding sodium tri(2-hydroxypropylaminoethanesulfonate) isocyanate. The preparation reaction formula is:

[0023]

[0024] (2) Add 70g of 4A molecular sieve to 1.5L xylene, disperse by ultrasonication, then add 35g of γ-chloropropyltrimethoxysilane and 20mL of water, heat to 70℃, stir for 12h, filter, wash with ethanol, dry, and obtain chloropropyl molecular sieve.

[0025] (3) Add 100g of chloropropyl molecular sieve to 1.5L of ethanol, disperse by ultrasonication, then add 30mmol of tris(2-hydroxypropylaminoethanesulfonate) isocyanuric acid, 36mmol of sodium hydroxide, and 20mL of water. Heat to 70℃, stir and reflux for 12h, filter, wash with water and ethanol, and dry to obtain modified molecular sieve.

[0026] (4) Add 30g of modified molecular sieve and 10g of leveling agent to 2kg of waterborne polyurethane emulsion, and shear and disperse them in a high-speed shearing machine to obtain a coating containing modified molecular sieve.

[0027] Example 2

[0028] (1) Add 50 mL of water, 0.36 mol of sodium hydroxide, 0.1 mol of triglycidyl isocyanurate and 0.33 mol of 2-aminoethanesulfonic acid to 250 mL of tetrahydrofuran. Stir the reaction at 25 °C for 10 h. After filtration, distill under reduced pressure. Add the crude product to ethanol, stir and filter. Heat the filtrate to evaporate, cool and crystallize to obtain sodium tri(2-hydroxypropylaminoethanesulfonate).

[0029] (2) Add 70g of 4A molecular sieve to 2L of toluene, disperse by ultrasonication, then add 140g of γ-chloropropyltrimethoxysilane and 60mL of water, heat to 90℃, stir for 12h, filter, wash with ethanol, dry, and obtain chloropropyl molecular sieve.

[0030] (3) Add 100g of chloropropyl molecular sieve to 2L of ethanol, disperse by ultrasonication, then add 150mmol of tris(2-hydroxypropylaminoethanesulfonate) isocyanuric acid, 195mmol of sodium hydroxide, and 50mL of water. Heat to 70℃, stir and reflux for 24h, filter, wash with water and ethanol, and dry to obtain modified molecular sieve.

[0031] (4) Add 300g of modified molecular sieve and 8g of leveling agent to 2kg of waterborne polyurethane emulsion, and shear and disperse them in a high-speed shearing machine to obtain a coating containing modified molecular sieve.

[0032] Example 3

[0033] (1) Sodium tris(2-hydroxypropylaminoethanesulfonate) isocyanurate was prepared according to the method of Example 1.

[0034] (2) Add 70g of 4A molecular sieve to 2L xylene, disperse by ultrasonication, then add 90g of γ-chloropropyltrimethoxysilane and 50mL of water, heat to 60℃, stir and react for 18h, filter, wash with ethanol, dry, and obtain chloropropyl molecular sieve.

[0035] (3) Add 100g of chloropropyl molecular sieve to 2L of ethanol, disperse by ultrasonication, then add 80mmol of tris(2-hydroxypropylaminoethanesulfonate) isocyanuric acid, 100mmol of sodium hydroxide, and 30mL of water. Heat to 80℃, stir and reflux for 18h, filter, wash with water and ethanol, and dry to obtain modified molecular sieve.

[0036] (4) Add 700g of modified molecular sieve and 10g of leveling agent to 2kg of waterborne polyurethane emulsion, and shear and disperse them in a high-speed shearing machine to obtain a coating containing modified molecular sieve.

[0037] Comparative Example 1

[0038] (1) Add 30g of 4A molecular sieve and 10g of leveling agent to 2kg of waterborne polyurethane emulsion, and shear and disperse them in a high-speed shearing machine to obtain a coating containing molecular sieve.

[0039] Comparative Example 2

[0040] (1) Chloropropyl molecular sieve was prepared according to the method of Example 1.

[0041] (2) Add 30g of chloropropyl molecular sieve and 10g of leveling agent to 2kg of waterborne polyurethane emulsion, and shear and disperse them in a high-speed shearing machine to obtain a coating containing modified molecular sieve.

[0042] Comparative Example 3

[0043] (1) Chloropropyl molecular sieve was prepared according to the method of Example 1.

[0044] (2) Add 100g of chloropropyl molecular sieve to 1.5L of ethanol, disperse by ultrasonication, then add 30mmol of 2-aminoethanesulfonic acid, 36mmol of sodium hydroxide and 20mL of water, heat to 70℃, stir and reflux for 12h, filter, wash with water and ethanol, dry to obtain modified molecular sieve.

[0045] (4) Add 30g of modified molecular sieve and 10g of leveling agent to 2kg of waterborne polyurethane emulsion, and shear and disperse them in a high-speed shearing machine to obtain a coating containing modified molecular sieve.

[0046] Comparative Example 4

[0047] (1) Add 80 mL of water, 0.48 mol of sodium hydroxide, 0.1 mol of triglycidyl isocyanurate, and 0.3 mol of ethylamine to 200 mL of tetrahydrofuran. Stir the mixture at 40 °C for 6 h. After filtration, distill under reduced pressure. Add the crude product to ethanol, stir, and filter. Heat the filtrate to evaporate, and then cool to crystallize, yielding tris(2-hydroxypropylaminoethane) isocyanurate, with the structural formula:

[0048] (2) Chloropropyl molecular sieves were prepared according to the method in Example 1.

[0049] (3) Add 100g of chloropropyl molecular sieve to 1.5L of ethanol, disperse by ultrasonication, then add 30mmol of tris(2-hydroxypropylaminoethane) isocyanurate, 36mmol of sodium hydroxide, and 20mL of water. Heat to 70℃, stir and reflux for 12h, filter, wash with water and ethanol, and dry to obtain modified molecular sieve.

[0050] (4) Add 30g of modified molecular sieve and 10g of leveling agent to 2kg of waterborne polyurethane emulsion, and shear and disperse them in a high-speed shearing machine to obtain a coating containing modified molecular sieve.

[0051] The coating was applied to the surface of the tinplate substrate and baked at 90°C for 6 hours to form a paint film. Adhesion was tested according to standard GB / T9286-2021. Tensile properties were tested according to standard GB / T 528-2009.

[0052] Moisture absorption performance test: Dry the paint film to constant weight, then place it in a constant temperature and humidity test chamber, set the temperature to 25℃ and the relative humidity to 70%, let it stand for 72 hours, take out the paint film, weigh it, and calculate the moisture absorption rate Q, Q=(m-m0) / m0×100%.

[0053] Table 1 Performance of Coatings

[0054]

[0055]

[0056] Comparative Example 1: Unmodified 4A molecular sieve was added to an aqueous polyurethane emulsion. The resulting coating had low tensile properties and moisture absorption, and its adhesion grade was only 3. The 4A molecular sieves in Examples 1-3 were modified with γ-chloropropyltrimethoxysilane and sodium isocyanurate tris(2-hydroxypropylaminoethanesulfonate). This introduced a large number of hydrophilic hydroxyl and sulfonate groups onto the surface of the molecular sieve, significantly improving its surface hydrophilicity. This is beneficial for improving the dispersibility of the molecular sieve in aqueous emulsions. Furthermore, the introduced hydroxyl groups form hydrogen bonds and other interactions with polyurethane, enhancing the interfacial bonding force and giving the molecular sieve a better reinforcing effect on the polyurethane, thus improving the tensile properties of the coating film. Simultaneously, the improved surface hydrophilicity of the molecular sieve enhances its moisture absorption properties, allowing it to be uniformly dispersed in the coating film with more moisture absorption sites, significantly increasing the moisture absorption rate of the coating film. The introduction of hydroxyl groups, sulfonates, and nitrogen-containing heterocycles onto the surface of the molecular sieve forms strong coordination forces with substrates such as tinplate, improving the adhesion of the coating film to the substrate, thereby increasing adhesion to grades 1 to 0.

[0057] Comparative Example 2 modified 4A molecular sieve using γ-chloropropyltrimethoxysilane. However, no hydrophilic hydroxyl or sulfonate groups were introduced on the surface of the molecular sieve, which was not conducive to improving the hygroscopic properties of the molecular sieve. Furthermore, the dispersibility in the waterborne polyurethane emulsion was poor, resulting in lower tensile properties of the paint film compared to Example 1, and an adhesion grade of only 3.

[0058] Comparative Example 3 modified 4A molecular sieve using γ-chloropropyltrimethoxysilane. The introduced chloropropyl group then reacted with the amino group of 2-aminoethanesulfonic acid to introduce sulfonate groups onto the surface of 4A molecular sieve. However, 2-aminoethanesulfonic acid contains only one sulfonic acid group and no hydroxyl group, resulting in fewer sulfonate groups on the surface of 4A molecular sieve than in Example 1. Consequently, the hydrophilicity and hygroscopicity of the molecular sieve were lower than in Example 1, as were its dispersibility in aqueous emulsions and its interfacial bonding with polyurethane. This resulted in lower tensile properties and an adhesion grade of only 2.

[0059] Comparative Example 4 modified 4A molecular sieve using γ-chloropropyltrimethoxysilane. The introduced chloropropyl group reacted with the imino group of tris(2-hydroxypropylaminoethane) isocyanurate. No sulfonate groups were introduced on the surface of the molecular sieve, resulting in lower hydrophilicity and hygroscopicity of 4A molecular sieve compared to Example 1. Its dispersibility in aqueous emulsions and interfacial bonding with polyurethane were also lower than those in Example 1, resulting in lower tensile properties and an adhesion grade of only 2.

[0060] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A coating containing a modified molecular sieve, characterized in that, The coating comprises 100 parts of water-based polyurethane emulsion, 1.5-35 parts by weight of modified molecular sieve, and 0.2-0.5 parts of leveling agent by weight; The preparation method of the modified molecular sieve is: (1) adding 4A molecular sieve into a solvent, ultrasonic dispersion, then adding γ-chloropropyltrimethoxysilane, water, heating to the reaction temperature, stirring and reacting, then filtering, washing, and drying to obtain chloropropyl molecular sieve; (2) adding chloropropyl molecular sieve into ethanol, ultrasonic dispersion, then adding tris(2-hydroxypropylaminoethanesulfonic acid sodium isocyanurate), sodium hydroxide and water, heating to the reaction temperature, stirring and reacting, then filtering, washing, and drying to obtain modified molecular sieve; The preparation method of the tris(2-hydroxypropylaminoethanesulfonic acid sodium isocyanurate) is: adding water, sodium hydroxide with a molar ratio of (3.6-4.8):1:(3-3.3), tris(glycidyl isocyanurate), and 2-aminoethanesulfonic acid into tetrahydrofuran, stirring at 25-40℃ for 6-10h, filtering, then distilling under reduced pressure, adding the crude product into ethanol, stirring, filtering, heating and evaporating the filtrate, cooling and crystallizing to obtain tris(2-hydroxypropylaminoethanesulfonic acid sodium isocyanurate).

2. The modified molecular sieve-containing coating of claim 1, wherein, The solvent in (1) is toluene or xylene.

3. The modified molecular sieve-containing coating of claim 1, wherein, The ratio of 4A molecular sieve to γ-chloropropyltrimethoxysilane in (1) is 100g:(50-200)g.

4. The modified molecular sieve-containing coating of claim 1, wherein, The reaction temperature in (1) is 60-90℃, and the reaction time is 12-18h.

5. The modified molecular sieve-containing coating of claim 1, wherein, The reaction temperature in (2) is 70-80℃, and the reaction time is 12-24h.

6. The modified molecular sieve-containing coating of claim 1, wherein, The ratio of chloropropyl molecular sieve to tris(2-hydroxypropylaminoethanesulfonic acid sodium isocyanurate) to sodium hydroxide in (2) is 100g:(30-150)mmol:(36-195)mmol.

7. The method of claim 1-6, wherein the modified molecular sieve-containing coating is prepared by the steps of: The preparation method is: adding modified molecular sieve and leveling agent into water-based polyurethane emulsion, and shearing and dispersing in a high-speed shearing machine to obtain coating containing modified molecular sieve.

8. Application of the coating containing modified molecular sieve prepared by the preparation method of claim 7 in a dehumidifier runner.

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