Coating containing modified molecular sieve as well as preparation method and application of coating

Abstract

The invention relates to the technical field of coatings, and discloses a coating containing a modified molecular sieve and a preparation method and application thereof, and the coating comprises 100 parts by weight of a waterborne polyurethane emulsion, 1.5-35 parts by weight of the modified molecular sieve and the like. After the 4A molecular sieve is modified, the surface hydrophilicity becomes good, the moisture absorption performance of the molecular sieve is improved, the 4A molecular sieve is uniformly dispersed in the waterborne polyurethane emulsion and the paint film, more moisture absorption sites are achieved, 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 to the surface of the molecular sieve, strong coordination acting force is formed with the surfaces of substrates such as tinplate and aluminum plates, the bonding capacity of a paint film to the substrates is improved, and therefore the adhesive force between the paint and the substrates is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, in particular to a coating containing modified molecular sieves, a preparation method thereof and an application thereof. Background Art

[0002] Polyurethane coatings are widely used in air conditioners, dehumidification and refrigeration equipment, furniture and electrical appliances due to their high toughness, good corrosion resistance and excellent wear resistance. However, conventional polyurethane coatings have poor mechanical strength and lack of dehumidification effect, which limits their practical application.

[0003] Molecular sieve is a porous aluminosilicate material with high mechanical strength and excellent adsorption performance. It has a wide range of practical applications in dehumidification, adsorption, catalysts, etc. However, the surface hydrophilicity of molecular sieve is poor, the dispersibility in water-based paint is poor, and the compatibility with polymer resins is poor. The patent application document with publication number CN119039555A discloses a molecular sieve polyurethane composite material with excellent sound insulation performance and a preparation method thereof. The epoxy coupling agent is adsorbed into the pores of the molecular sieve and then grafted with amino groups outside the pores, thereby improving the compatibility between polyurethane and molecular sieve and enhancing the mechanical, sound absorption and other properties of polyurethane. However, the molecular sieve does not improve the hygroscopicity of polyurethane, which is unfavorable for the application of polyurethane coating in dehumidifying and refrigeration equipment such as dehumidifier wheels and air conditioners. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the present invention provides a coating containing modified molecular sieves, a preparation method thereof, and an application thereof, which solve the problems of poor adhesion, moisture absorption, and other properties of polyurethane coatings.

[0005] The technical solution of the present invention is a coating containing a modified molecular sieve and a preparation method. The coating comprises, by weight, 100 parts of an aqueous polyurethane emulsion, 1.5-35 parts of a modified molecular sieve, and 0.2-0.5 parts of a leveling agent. The preparation method comprises adding the modified molecular sieve and the leveling agent to the aqueous polyurethane emulsion, shearing and dispersing the emulsion in a high-speed shearing machine, and obtaining the coating containing the modified molecular sieve.

[0006] The preparation method of modified molecular sieve is:

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

[0008] (2) Add chloropropyl molecular sieve to ethanol, disperse by ultrasonication, then add tris(2-hydroxypropylaminoethanesulfonic acid sodium)isocyanurate, sodium hydroxide and water, heat to the reaction temperature, stir the reaction and filter, wash with water and ethanol, and dry to obtain a 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°C and the reaction time is 12-18h.

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

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

[0014] Preferably, the preparation method of tris(2-hydroxypropylaminoethanesulfonic acid sodium) is as follows: water, sodium hydroxide, triglycidyl isocyanurate, and 2-aminoethanesulfonic acid in a molar ratio of (3.6-4.8):1:(3-3.3) are added to tetrahydrofuran, and the mixture is stirred at 25-40°C for 6-10 hours. After filtering, the mixture is distilled under reduced pressure, and the crude product is added to ethanol, stirred, filtered, and the filtrate is heated for evaporation and cooled for crystallization to obtain tris(2-hydroxypropylaminoethanesulfonic acid sodium) isocyanurate.

[0015] Preferably, the coating containing the modified molecular sieve is used in a dehumidifier wheel.

[0016] The beneficial technical effect of the present invention is as follows: 4A molecular sieve is surface-modified using γ-chloropropyltrimethoxysilane, and the introduced chloropropyl reacts with the imino group of tris(2-hydroxypropylaminoethanesulfonic acid sodium) isocyanurate to obtain a modified molecular sieve, which is finally blended with an aqueous polyurethane emulsion to obtain a coating. A large number of hydrophilic hydroxyl groups and sulfonate groups are introduced onto the surface of the modified 4A molecular sieve, which significantly improves the surface hydrophilicity of the molecular sieve, is beneficial to improving the dispersibility of the molecular sieve in the aqueous emulsion, and the introduced hydroxyl groups form hydrogen bonds and other interaction forces with the polyurethane, thereby improving the interfacial bonding between the two, so that the molecular sieve has a better reinforcing effect on the polyurethane and improves 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 hygroscopic performance of the molecular sieve. It is also evenly dispersed in the paint film, has more hygroscopic sites, and significantly improves the moisture absorption rate of the paint film.

[0018] The present invention introduces nitrogen-containing heterocycles and a large number of hydroxyl and sulfonate groups on the surface of the molecular sieve, forming a strong coordination force with the surface of substrates such as tinplate and aluminum plate, thereby improving the bonding ability of the paint film to the substrate, thereby improving the adhesion between the paint and the substrate. DETAILED DESCRIPTION

[0019] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0020] The following water-based polyurethane emulsion has a solid content of about 45%, model number Wengkaier PU-YN, and is sourced from Wengkaier (Guangdong) Technology Co., Ltd. 4A molecular sieve, with a particle size of 3-5 mm, 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 isocyanurate, and 0.3 mol of 2-aminoethanesulfonic acid to 200 mL of tetrahydrofuran, and stir at 40°C for 6 h. After filtration, the mixture is evaporated under reduced pressure. The crude product is added to ethanol, stirred, filtered, and the filtrate is heated for evaporation and cooled for crystallization to obtain tris(2-hydroxypropylaminoethanesulfonic acid sodium)isocyanurate. The preparation reaction formula is:

[0023]

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

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

[0026] (4) Add 30 g of modified molecular sieve and 10 g of leveling agent to 2 kg of aqueous polyurethane emulsion, shear and disperse 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, and stir at 25°C for 10 h. After filtering, distill under reduced pressure. The crude product is added to ethanol, stirred, filtered, and the filtrate is heated for evaporation and cooled for crystallization to obtain tris(2-hydroxypropylaminoethanesulfonic acid sodium)isocyanurate.

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

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

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

[0032] Example 3

[0033] (1) Prepare tris(2-hydroxypropylaminoethanesulfonic acid sodium)isocyanurate according to the method of Example 1.

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

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

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

[0037] Comparative Example 1

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

[0039] Comparative Example 2

[0040] (1) Prepare chloropropyl molecular sieve according to the method of Example 1.

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

[0042] Comparative Example 3

[0043] (1) Prepare chloropropyl molecular sieve according to the method of Example 1.

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

[0045] (4) Add 30 g of modified molecular sieve and 10 g of leveling agent to 2 kg of aqueous polyurethane emulsion, shear and disperse 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 and react at 40°C for 6 h, filter and distill under reduced pressure, add the crude product to ethanol, stir and filter, heat and evaporate the filtrate, cool and crystallize to obtain tris(2-hydroxypropylaminoethane)isocyanurate, the structural formula of which is

[0048] (2) Prepare chloropropyl molecular sieve according to the method of Example 1.

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

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

[0051] The coating was applied to the surface of a 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: the paint film was dried to constant weight, and then placed in a constant temperature and humidity test chamber, set the temperature to 25 ° C, the relative humidity to 70%, and stood for 72 hours. The paint film was taken out and weighed, and the moisture absorption rate Q was calculated, Q = (m-m0) / m0×100%.

[0053] Table 1 Properties of coatings

[0054]

[0055]

[0056] In Comparative Example 1, unmodified 4A molecular sieve was added to the aqueous polyurethane emulsion. The tensile properties and moisture absorption rate of the prepared coating were low, and the adhesion grade was only level 3. The 4A molecular sieve of Example 1-3 is modified by γ-chloropropyltrimethoxysilane and tris(2-hydroxypropylaminoethanesulfonic acid sodium) isocyanurate, and a large number of hydrophilic hydroxyl groups and sulfonate groups are introduced on the surface of the molecular sieve, which significantly improves the surface hydrophilicity of the molecular sieve, which is beneficial to improving the dispersibility of the molecular sieve in the aqueous emulsion, and the introduced hydroxyl groups form hydrogen bonds and other interaction forces with the polyurethane, thereby improving the interfacial bonding force between the two, so that the molecular sieve has a better reinforcing effect on the polyurethane and improves the tensile properties of the coating film. At the same time, the surface hydrophilicity of the molecular sieve is improved, which is beneficial to improving the hygroscopic properties of the molecular sieve, and is evenly dispersed in the paint film, with more hygroscopic sites, which significantly improves the moisture absorption rate of the paint film. The introduction of hydroxyl groups, sulfonates, and nitrogen-containing heterocycles on the surface of the molecular sieve forms a strong coordination force with the surface of substrates such as tinplate, thereby improving the bonding ability of the paint film to the substrate, thereby improving the adhesion to levels 1 to 0.

[0057] In Comparative Example 2, 4A molecular sieve was modified using γ-chloropropyltrimethoxysilane. No hydrophilic hydroxyl group or sulfonate group was introduced on the surface of the molecular sieve, which was not conducive to improving the hygroscopic properties of the molecular sieve. In addition, the dispersion in the aqueous polyurethane emulsion was poor, resulting in the tensile properties of the paint film being lower than that of Example 1, and the adhesion grade being only level 3.

[0058] In Comparative Example 3, the 4A molecular sieve is modified using γ-chloropropyltrimethoxysilane. The introduced chloropropyl group reacts with the amino group of 2-aminoethanesulfonic acid to introduce sulfonate groups on the surface of the 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 the 4A molecular sieve than in Example 1. The hydrophilicity and hygroscopicity of the molecular sieve are lower than in Example 1, and the dispersibility in aqueous emulsion and the interfacial bonding strength with polyurethane are lower than in Example 1, resulting in lower tensile properties and an adhesion grade of only Level 2.

[0059] In Comparative Example 4, the 4A molecular sieve was modified using γ-chloropropyltrimethoxysilane. The introduced chloropropyl group then reacted with the imino group of tris(2-hydroxypropylaminoethane)isocyanurate, and no sulfonate group was introduced on the surface of the molecular sieve. As a result, the hydrophilicity and hygroscopicity of the 4A molecular sieve were lower than those in Example 1, and the dispersibility in the aqueous emulsion and the interfacial bonding strength with the polyurethane were lower than those in Example 1, resulting in lower tensile properties and an adhesion grade of only level 2.

[0060] The above describes in detail the preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A coating containing modified molecular sieve, characterized in that: The coating comprises, by weight, 100 parts of aqueous polyurethane emulsion, 1.5-35 parts by weight of modified molecular sieve, and 0.2-0.5 parts of leveling agent; The preparation method of the modified molecular sieve is: (1) adding 4A molecular sieve to a solvent, ultrasonically dispersing, then adding γ-chloropropyltrimethoxysilane and water, heating to the reaction temperature, stirring the reaction, filtering, washing, and drying to obtain chloropropyl molecular sieve; (2) Add chloropropyl molecular sieve to ethanol, disperse by ultrasonication, then add tris(2-hydroxypropylaminoethanesulfonic acid sodium)isocyanurate, sodium hydroxide and water, heat to the reaction temperature, stir the reaction, filter, wash and dry to obtain the modified molecular sieve.

2. The coating containing modified molecular sieve according to claim 1, characterized in that The solvent in (1) is toluene or xylene.

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

4. The coating containing modified molecular sieve according to claim 1, characterized in that The reaction temperature in (1) is 60-90°C and the reaction time is 12-18h.

5. The coating containing modified molecular sieve according to claim 1, characterized in that The reaction temperature in (2) is 70-80°C, and the reaction time is 12-24h.

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

7. The coating containing modified molecular sieve according to claim 6, characterized in that The preparation method of tris(2-hydroxypropylaminoethanesulfonic acid sodium) is as follows: water, sodium hydroxide, triglycidyl isocyanurate, and 2-aminoethanesulfonic acid in a molar ratio of (3.6-4.8):1:(3-3.3) are added to tetrahydrofuran, and the mixture is stirred at 25-40° C. for 6-10 hours. After filtering, the mixture is subjected to reduced pressure distillation, and the crude product is added to ethanol, stirred, filtered, and the filtrate is heated for evaporation, and cooled for crystallization to obtain tris(2-hydroxypropylaminoethanesulfonic acid sodium) 8. The method for preparing a coating containing a modified molecular sieve according to any one of claims 1 to 7, wherein: The preparation method comprises the following steps: adding modified molecular sieve and leveling agent into aqueous polyurethane emulsion, shearing and dispersing the emulsion in a high-speed shearing machine, and obtaining a coating containing the modified molecular sieve.

9. Use of the coating containing modified molecular sieve obtained by the preparation method according to claim 8 in a dehumidifier wheel.

Images