Self-cleaning coating for sanitary products and preparation method of self-cleaning coating

Abstract

The invention relates to the technical field of bathroom coatings, in particular to a self-cleaning coating for a bathroom product and a preparation method of the self-cleaning coating. The invention relates to a self-cleaning coating for sanitary products, which is prepared from the following preparation raw materials in parts by mass: 30 to 35 parts of modified polyurethane, 30 to 35 parts of hydrophobic modified talcum powder, 2 to 2.5 parts of adhesion promoter, 3 to 4 parts of dispersing agent, 1.4 to 1.6 parts of defoaming agent, 0.5 to 0.8 part of flatting agent, 1 to 1.5 parts of anti-settling agent and 60 to 70 parts of deionized water. The self-cleaning coating not only has excellent physical properties and chemical properties, but also has good environmental protection characteristics and economic benefits, and has important application value for surface treatment of sanitary products.

Description

Technical Field

[0001] This application relates to the technical field of bathroom coatings, and particularly relates to a self-cleaning coating for bathroom products and a preparation method thereof. Background Art

[0002] Most of the coatings for bathroom products on the current market use polymers such as epoxy resins and acrylic resins as the main film-forming substances. Although they have certain waterproof and decorative effects, they are prone to problems such as coating aging and peeling in an environment of long-term contact with water vapor, cleaning agents, etc. Especially in a humid and corrosive environment, the durability and aesthetics of the coating are difficult to maintain for a long time. Most of the commonly used coatings for bathroom products are solvent-based. Although they have good adhesion and wear resistance, they have problems such as a large amount of volatile organic compound (VOC) emissions and serious environmental pollution. In recent years, with the enhancement of environmental awareness and the promotion of the concept of green manufacturing, waterborne coatings have received more and more attention due to their advantages such as low VOC emissions, safety, and non-toxicity. However, the existing waterborne coatings are still difficult to compare with traditional solvent-based coatings in terms of corrosion resistance, wear resistance, self-cleaning property, and gloss. Especially in an environment like a bathroom with high humidity and frequent changes in acidity and alkalinity, the coating is prone to delamination, discoloration, and even rusting. Summary of the Invention

[0003] The purpose of this application is to provide a self-cleaning coating for bathroom products and a preparation method thereof in view of the deficiencies of the current technology. The self-cleaning coating for bathroom products prepared in this application has excellent adhesion, salt spray resistance, hardness, impact resistance, and hydrophobic self-cleaning properties.

[0004] In the first aspect, this application provides a self-cleaning coating for bathroom products, adopting the following technical solution: A self-cleaning coating for bathroom products, by mass, comprises the following preparation raw materials: 30 - 35 parts of modified polyurethane, 30 - 35 parts of hydrophobic modified talc powder, 2 - 2.5 parts of adhesion promoter, 3 - 4 parts of dispersant, 1.4 - 1.6 parts of defoamer, 0.5 - 0.8 parts of leveling agent, 1 - 1.5 parts of anti-settling agent, and 60 - 70 parts of deionized water.

[0005] By adopting the above technical solution, modified polyurethane: As one of the main components of the coating, modified polyurethane provides the basic mechanical properties and wear resistance of the coating. Its special intermolecular hydrogen bonding force, electrostatic interaction and layered molecular stacking structure ensure the mechanical properties and substrate adhesion of the coating. At the same time, the self-healing property of polyurethane enables the surface to quickly recover its original performance even after being damaged. Hydrophobic modified talc powder: Hydrophobic self-cleaning properties are introduced through chemical grafting modification and acylation reaction, while endowing the coating with good salt spray resistance. The amino group reacts with modified polyurethane to form a chemical bond, improving the wear resistance of the coating; the fluorine-containing group extends outward to form a hydrophobic layer, enhancing the salt spray resistance and hardness of the coating. Adhesion promoter: The adhesion promoter is prepared from raw materials such as hydroxypropyl acrylate and polyoxyethylene fatty alcohol ether, effectively improving the adhesion performance of the coating. Its phosphate group forms a coordination bond or covalent bond with the hydroxyl group or oxide layer on the substrate surface to enhance adhesion, while the unsaturated double bond participates in the cross-linking reaction to improve the durability of the coating. The siloxane bond generated by N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane further enhances adhesion and compatibility. Other additives: Although the amount of additives such as dispersants, defoamers, leveling agents, and anti-settling agents is small, they play a role in stabilizing the system, improving the construction performance and enhancing the product quality during the coating preparation process. For example, dispersants help to uniformly disperse pigments and fillers; defoamers reduce the generation of foam during the coating preparation process; leveling agents improve the fluidity and flatness of the coating; anti-settling agents prevent the coating from settling during storage or construction. These components form a complex three-dimensional network structure through chemical bonding and interaction, not only improving the mechanical properties and wear resistance of the coating, but also enhancing the adhesion between the coating and the substrate. At the same time, the synergistic effect of each component endows the coating with excellent self-cleaning performance and salt spray resistance, meeting the high requirements for coating performance of sanitary products.

[0006] Preferably, the preparation method of the modified polyurethane comprises the following steps: S21. According to the mass parts, add 3-4 parts of ethylenediaminetetraacetic dianhydride and 2-3 parts of 3-amino-1-propanol to 30-35 parts of pyridine, heat to 57 °C and stir for 1-2 h, then raise the temperature to 105 °C and continue stirring for 8 h. After the stirring is completed, add 30 parts of deionized water, filter, and the residue is dried after alcohol washing to obtain a dihydroxyimide derivative; S22. By mass parts, add 10 - 12 parts of polytetramethylene ether glycol, 2 - 2.5 parts of naphthalene diisocyanate, 3 - 3.5 parts of 1,8 - diisocyanatooctane, and 0.02 - 0.03 parts of stannous 2 - ethylhexanoate to 83 parts of N - methylpyrrolidone. After heating to 73 °C and stirring for 2 h, then add 3 - 3.5 parts of dihydroxyimide derivative and 2 - 2.5 parts of 2,2’ - dithioglycol. Raise the temperature to 88 °C and stir for 10 h for polymerization. After the stirring ends, cool to room temperature and add 500 parts of deionized water for dilution. After precipitation occurs, filter, wash the residue with water and then dry to obtain the modified polyurethane.

[0007] By adopting the above technical solution, polyurethane, as a block copolymer containing urethane groups (-NHCOO-) and urea groups (-NHCONH-), has the advantages of high strength, wear resistance, tear resistance, etc., and is widely used in water - borne coatings. Since polyurethane is a multi - segment polymer with soft - hard alternating chain units, where the soft chain is composed of polyols and the hard chain is composed of isocyanates. Through appropriate molecular chain modulation, polyurethane can easily achieve self - healing. This can not only solve the problems of poor durability and abrasion resistance existing in current self - cleaning coatings, but also improve the mechanical properties by regulating the chain segment composition to adjust the molecular chain toughness. In the present invention, the synthesized polyurethane has good mechanical properties and substrate adhesion due to the special intermolecular hydrogen bond force, electrostatic interaction and layered molecular stacking structure. The disulfide bond and hydrogen bond force are introduced into the structure to achieve the self - healing effect together. The component obtained by compounding it with hydrophobically modified silica is added to the self - cleaning coating and can exhibit good self - cleaning effect. The hard segments and soft segments existing in the polyurethane molecular chain build a good network structure in a cycle, making it have good toughness and be able to withstand a large tensile limit. When the molecular chain is cut under external force, through self - repair, its self - repair mechanism includes not only self - assembly between molecular chains but also intermolecular hydrogen bonds and disulfide bonds. Under the action of multiple mechanisms, the coating can quickly complete the repair of the coating surface.

[0008] Preferably, the preparation method of the hydrophobically modified talc powder includes the following steps: S31. By mass parts, add 100 parts of talc powder to 300 parts of absolute ethanol, ultrasonically disperse for 30 - 40 min, then mechanically stir and mix at a speed of 1500 - 1800 rpm for 50 - 60 min to obtain a mixed solution. Slowly drop the ethanol solution of N - (β - aminoethyl) - γ - aminopropyltrimethoxysilane into the mixed solution, react at 80 - 85 °C for 5 - 6 h, centrifuge, wash, and vacuum dry to obtain the talc powder modified by the silane coupling agent. S32. According to the mass parts, take 300 parts of a dimethylformamide solution of trifluoroacetic anhydride with a mass concentration of 2%, heat it up to 95°C, add 100 parts of talc powder modified with a silane coupling agent, and adjust the pH of the dispersion to 9 - 10 with a 10% sodium hydroxide aqueous solution. React at a constant temperature for 3 - 4 h, filter, wash with water, and dry to obtain hydrophobically modified talc powder.

[0009] By adopting the above technical solution, first, chemically graft-modify the surface of talc powder with N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane to introduce amino groups onto the surface of talc powder. Subsequently, through the acylation reaction of trifluoroacetic anhydride with some amino groups, introduce trifluoromethyl groups to endow talc powder with hydrophobic self-cleaning properties. By adding talc powder with amino groups and fluorine-containing groups on the surface, among which the amino groups can react with modified polyurethane to form chemical connections, ensuring the firm connection between talc powder and the substrate and improving the wear resistance of the coating. The fluorine-containing groups extend outwards to form a hydrophobic layer, which can endow the coating with good salt spray resistance and self-cleaning properties. In addition, fluorine atoms have a very high electronegativity, which makes there be strong intermolecular forces between fluorine atoms. This stronger intermolecular interaction can improve the cohesion of the coating, thereby increasing the hardness, wear resistance, and self-cleaning of the coating.

[0010] Preferably, the mass parts ratio of the talc powder to the ethanol solution of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane is 1:4 - 5; the mass percentage of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane in the ethanol solution of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane is 15%.

[0011] Preferably, the preparation method of the adhesion promoter includes the following steps: S51. According to the mass parts, mix 30 - 35 parts of a 25% aqueous solution of phytic acid with 4 - 5 parts of glycidyl acrylate, then add 0.2 - 0.3 parts of tetrabutylammonium bromide and 0.04 - 0.05 parts of hydroquinone, react at 92°C and 450 rpm for 2 - 3 h, extract with butyl acetate, and then recover butyl acetate by vacuum distillation to obtain alkenyl-grafted phytic acid; S52. According to the mass parts, mix 12 parts of hydroxypropyl acrylate, 3.5 parts of polyoxyethylene fatty alcohol ether, and 3.5 parts of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane. Under a nitrogen atmosphere, at 80°C and 500 rpm stirring conditions, add 7 parts of alkenyl-grafted phytic acid and stir for 6 - 7 h, then add 1 part of deionized water and continue stirring for 3 h, and cool to room temperature to obtain the adhesion promoter.

[0012] By adopting the above technical solution, the adhesion promoter is prepared from hydroxypropyl acrylate, polyoxyethylene fatty alcohol ether, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane and alkenyl-grafted phytic acid, and can effectively improve the adhesion performance of waterborne coatings. During the whole process, each component forms a complex three-dimensional network structure through chemical bonding and interaction, enabling the adhesion promoter to not only firmly adhere to the substrate surface, but also tightly combine with the modified polyurethane, thereby further improving the adhesion performance of waterborne coatings. Among them, the phosphate group of the alkenyl-grafted phytic acid can form strong coordination bonds or covalent bonds with the hydroxyl groups or oxide layers on the substrate surface to enhance adhesion, and the unsaturated double bonds can participate in cross-linking reactions to improve the coating durability; the siloxane bonds formed by N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane have hydrogen bond interactions with the carboxyl / hydroxyl groups in the film-forming resin, further enhancing adhesion and compatibility.

[0013] Preferably, the dispersant is composed of sodium carboxymethyl cellulose and isomeric tridecyl alcohol polyoxyethylene ether in a mass ratio of 2:3.

[0014] By adopting the above technical solution, the main function of the dispersant is to help evenly disperse the solid particles in the coating in the liquid medium and prevent particle aggregation or precipitation. The dispersant interacts with the surface of the solid particles through physical or chemical actions to form a stable dispersion system. Sodium carboxymethyl cellulose is a commonly used water-soluble polymer with good dispersibility and stability. It can form hydrogen bonds or other chemical bonds with the solid particles in the coating, thereby enhancing the dispersion stability of the particles. At the same time, sodium carboxymethyl cellulose also has good viscosity and thickening effects. Isomeric tridecyl alcohol polyoxyethylene ether is a non-ionic surfactant with good emulsifying and dispersing properties. It can reduce the surface tension, making it easier for the solid particles to be dispersed in the coating. At the same time, isomeric tridecyl alcohol polyoxyethylene ether also has good emulsifying and stabilizing effects, which helps to improve the storage stability of the coating. The combination of the two dispersants can provide stronger dispersing ability, enabling the solid particles in the coating to be more evenly dispersed in the liquid medium. Sodium carboxymethyl cellulose and isomeric tridecyl alcohol polyoxyethylene ether can interact to form a stable dispersion system, preventing the coating from precipitating or delaminating during storage and use. Sodium carboxymethyl cellulose has good viscosity and thickening properties, while isomeric tridecyl alcohol polyoxyethylene ether can improve the fluidity and coating performance of the coating. The combination of the two can improve the viscosity and stability of the coating while maintaining good rheological properties of the coating. Isomeric tridecyl alcohol polyoxyethylene ether has good emulsifying properties, which helps to improve the emulsion stability of the coating, enabling the water and other liquid components in the coating to be better dispersed and stabilized. In summary, the combined use of sodium carboxymethyl cellulose and isomeric tridecyl alcohol polyoxyethylene ether can effectively improve the dispersibility, stability and emulsion stability of the coating, thus ensuring the quality and performance of the coating.

[0015] Preferably, the defoamer is BYK028 defoamer from BYK of Germany.

[0016] Preferably, the anti-settling agent is AEROSIL R972 from Evonik Degussa.

[0017] Preferably, the leveling agent is BYK-323 leveling agent from BYK of Germany.

[0018] In a second aspect, the present application provides a preparation method for a self-cleaning coating for sanitary ware products, adopting the following technical solution: As a general technical concept, the present application also provides the above-mentioned preparation method for a self-cleaning coating for sanitary ware products, including the following steps: According to mass parts, mix modified polyurethane, hydrophobically modified talc powder, adhesion promoter, dispersant, defoamer, leveling agent, anti-settling agent and deionized water, stir evenly at a speed of 2000 r / min at 50 °C, and disperse through a sand mill to a fineness of less than 5 μm to obtain a self-cleaning coating for sanitary ware products.

[0019] In summary, the beneficial technical effects of the present application are as follows: 1. Excellent adhesion: By using modified polyurethane and adhesion promoter, the coating can firmly adhere to the surface of the substrate, improving the wear resistance and durability of the coating.

[0020] 2. Salt spray resistance: The fluorine-containing groups in the hydrophobically modified talc powder endow the coating with good salt spray resistance, enabling it to resist the erosion of corrosive environments.

[0021] 3. Hardness and impact resistance: The use of modified polyurethane and hydrophobically modified talc powder improves the hardness and impact resistance of the coating, enabling it to withstand large physical impacts without being easily damaged.

[0022] 4. Hydrophobic self-cleaning performance: The introduction of hydrophobically modified talc powder endows the coating with good hydrophobic performance, making it difficult for dirt and dust to adhere to the coating surface, thus having a self-cleaning function.

[0023] 5. Self-healing ability: The hard segments and soft segments in the polyurethane molecular chain build a good network structure in a cyclic manner, endowing the coating with good toughness. When the coating is damaged due to external forces, the coating can quickly restore its performance through the self-assembly of molecular chains and the self-repair mechanism of interlayer hydrogen bonds and disulfide bonds.

[0024] 6. Environmental protection performance: Deionized water is used as a solvent in the coating, reducing the impact on the environment. At the same time, the hydrophobic self-cleaning characteristics of the coating reduce the frequency and difficulty of cleaning and maintenance, reducing the burden on the environment. Specific embodiments

[0025] The implementation scheme of the present application will be described in detail below in combination with embodiments. However, those skilled in the art will understand that the following embodiments are only used to illustrate the present application and should not be regarded as limiting the scope of the present application. For those conditions not specified in the embodiments, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained by purchasing in the market.

[0026] In the following examples and preparation examples, 1 part means 100 g.

[0027] Preparation Example 1 Preparation of Modified Polyurethane The preparation method of the modified polyurethane includes the following steps: S21. According to the mass parts, 3.5 parts of ethylenediaminetetraacetic dianhydride and 2.5 parts of 3-amino-1-propanol are added to 33 parts of pyridine, heated to 57 °C and stirred for 1.5 h, then the temperature is raised to 105 °C and stirring is continued for 8 h. After the stirring is completed, 30 parts of deionized water is added, filtered, and the residue is washed with alcohol and then dried to obtain a dihydroxyimide derivative; S22. According to the mass parts, 11 parts of polytetramethylene ether glycol, 2.3 parts of naphthalene diisocyanate, 3.4 parts of 1,8-diisocyanatooctane, and 0.02 part of stannous 2-ethylhexanoate are added to 83 parts of N-methylpyrrolidone, heated to 73 °C and stirred for 2 h, then 3.3 parts of the dihydroxyimide derivative and 2.3 parts of 2,2'-dithioglycol are added, and the temperature is raised to 88 °C and stirred for 10 h for polymerization. After the stirring is completed, it is cooled to room temperature and diluted with 500 parts of deionized water. After precipitation appears, it is filtered, and the residue is washed with water and then dried to obtain the modified polyurethane.

[0028] Preparation Example 2 Preparation of Hydrophobic Modified Talc The preparation method of the hydrophobic modified talc includes the following steps: S31. According to the mass parts, 100 parts of talc with an average particle size of 2 μm is added to 300 parts of absolute ethanol and ultrasonically dispersed for 35 min, and then mechanically stirred and mixed at a speed of 1600 rpm for 55 min to obtain a mixed solution. 450 parts of an ethanol solution of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane is slowly added dropwise to the mixed solution, and the reaction is carried out at 83 °C for 5.6 h, centrifuged, washed, and vacuum dried to obtain talc modified with a silane coupling agent; the mass percentage of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane in the ethanol solution of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane is 15%; S32. According to the parts by mass, 300 parts of a dimethylformamide solution of trifluoroacetic anhydride with a mass concentration of 2% was taken and heated to 95°C, 100 parts of silane coupling agent-modified talc powder was added, and the pH of the dispersion was adjusted to 9.5 with an aqueous sodium hydroxide solution with a mass concentration of 10%. The reaction was carried out at a constant temperature for 3.4 h, followed by filtration, washing with water, and drying to obtain hydrophobically modified talc powder.

[0029] Preparation Example 3 Preparation of adhesion promoter The preparation method of the adhesion promoter includes the following steps: S51. According to the parts by mass, 33 parts of an aqueous solution of phytic acid with a mass concentration of 25% was mixed with 4.5 parts of glycidyl acrylate, then 0.25 part of tetrabutylammonium bromide and 0.045 part of hydroquinone were added, and the reaction was carried out at 92°C and 450 rpm for 2.5 h. It was extracted with butyl acetate, and then butyl acetate was recovered by vacuum distillation to obtain alkenyl-grafted phytic acid; S52. According to the parts by mass, 12 parts of hydroxypropyl acrylate, 3.5 parts of polyoxyethylene fatty alcohol ether, and 3.5 parts of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane were mixed. Under a nitrogen atmosphere, 7 parts of alkenyl-grafted phytic acid was added and stirred at 80°C and 500 rpm for 6.5 h, then 1 part of deionized water was added and stirring was continued for 3 h, and it was cooled to room temperature to obtain the adhesion promoter.

[0030] Preparation of Comparative Example 1 Modified polyurethane According to the parts by mass, 11 parts of polytetramethylene ether glycol, 2.3 parts of naphthalene diisocyanate, 3.4 parts of 1,8-diisocyanatooctane, and 0.02 part of stannous 2-ethylhexanoate were added to 83 parts of N-methylpyrrolidone. After heating to 73°C and stirring for 2 h, 2.3 parts of 2,2'-dithiobisethanol was added, and the temperature was raised to 88°C and stirred for 10 h for polymerization. After the stirring was completed, it was cooled to room temperature and diluted with 500 parts deionized water. After precipitation occurred, it was filtered, and the residue was washed with water and dried to obtain modified polyurethane.

[0031] Example 1 A self-cleaning coating for sanitary ware products, by mass, includes the following preparation raw materials: 30 parts of modified polyurethane, 30 parts of hydrophobically modified talc powder, 2 parts of adhesion promoter, 3 parts of dispersant, 1.4 parts of defoamer, 0.5 part of leveling agent, 1 part of anti-settling agent, 60 parts of deionized water. The dispersant is composed of sodium carboxymethyl cellulose and isomeric tridecanol polyoxyethylene ether in a mass ratio of 2:3. The defoamer is BYK028 defoamer from BYK of Germany, the anti-settling agent is AEROSIL R972 from Evonik Degussa, the leveling agent is BYK-323 leveling agent from BYK of Germany, and the modified polyurethane is prepared from Preparation Example 1; The preparation method of the above self-cleaning coating for sanitary ware products includes the following steps: Mix the modified polyurethane, hydrophobically modified talc powder, adhesion promoter, dispersant, defoamer, leveling agent, anti-settling agent and deionized water according to parts by mass, stir evenly at a speed of 2000 r / min at 50 °C, and disperse through a sand mill to a fineness of less than 5 μm to obtain a self-cleaning coating for sanitary ware products.

[0032] Example 2 A self-cleaning coating for sanitary ware products, by mass, includes the following preparation raw materials: 35 parts of modified polyurethane, 35 parts of hydrophobically modified talc powder, 2.5 parts of adhesion promoter, 4 parts of dispersant, 1.6 parts of defoamer, 0.8 part of leveling agent, 1.5 parts of anti-settling agent, 70 parts of deionized water. The dispersant is composed of sodium carboxymethyl cellulose and isomeric tridecyl alcohol polyoxyethylene ether in a mass ratio of 2:3. The defoamer is BYK028 defoamer from BYK of Germany. The anti-settling agent is AEROSIL R972 from Evonik Degussa. The leveling agent is BYK-323 leveling agent from BYK of Germany. The modified polyurethane is obtained from Preparation Example 1. The preparation method of the above self-cleaning coating for sanitary ware products includes the following steps: Mix the modified polyurethane, hydrophobically modified talc powder, adhesion promoter, dispersant, defoamer, leveling agent, anti-settling agent and deionized water according to parts by mass, stir evenly at a speed of 2000 r / min at 50 °C, and disperse through a sand mill to a fineness of less than 5 μm to obtain a self-cleaning coating for sanitary ware products.

[0033] Example 3 A self-cleaning coating for sanitary ware products, by mass, includes the following preparation raw materials: 33 parts of modified polyurethane, 33 parts of hydrophobically modified talc powder, 2.3 parts of adhesion promoter, 3.5 parts of dispersant, 1.5 parts of defoamer, 0.7 part of leveling agent, 1.3 parts of anti-settling agent, 65 parts of deionized water. The dispersant is composed of sodium carboxymethyl cellulose and isomeric tridecyl alcohol polyoxyethylene ether in a mass ratio of 2:3. The defoamer is BYK028 defoamer from BYK of Germany. The anti-settling agent is AEROSIL R972 from Evonik Degussa. The leveling agent is BYK-323 leveling agent from BYK of Germany. The modified polyurethane is obtained from Preparation Example 1. The preparation method of the above self-cleaning coating for sanitary ware products includes the following steps: Mix the modified polyurethane, hydrophobically modified talc powder, adhesion promoter, dispersant, defoamer, leveling agent, anti-settling agent and deionized water according to parts by mass, stir evenly at a speed of 2000 r / min at 50 °C, and disperse through a sand mill to a fineness of less than 5 μm to obtain a self-cleaning coating for sanitary ware products.

[0034] Comparative Example 1 Same as Example 3, except that talcum powder with an average particle size of 2 microns in equal mass parts is used instead of hydrophobically modified talcum powder.

[0035] Comparative Example 2 Same as Example 3, except that the modified polyurethane is prepared as in Comparative Example 1.

[0036] Comparative Example 3 Same as Example 3, except that an adhesion promoter BYK-4509 in equal mass parts is used instead of the adhesion promoter prepared in Preparation Example 2.

[0037] Comparative Example 4 Same as Example 3, except that the dispersant is sodium carboxymethyl cellulose.

[0038] Comparative Example 5 Same as Example 3, except that the dispersant is isomeric tridecanol polyoxyethylene ether.

[0039] Performance Test Samples of the self-cleaning coatings for sanitary ware prepared in Examples 1 - 3 and Comparative Examples 1 - 5 were taken. The corresponding self-cleaning coatings for sanitary ware were sprayed onto several electroplated nickel ABS plates of 5 cm X 5 cm X 0.2 cm (nickel layer thickness is 10 microns), and forced drying was carried out at a low temperature (60°C / 50 min) to obtain a coating with a thickness of 28 - 32 microns. After standing for 3 days, the following performance tests were carried out, and the test results are shown in Table 1; Adhesion Test: Conducted according to the standard of GB / T9286 - 1998, using the cross-cut method. A grid with a spacing of 1 mm was drawn on the coating surface, and the peeling situation was observed after peeling with tape. The rating standard is from 0 - 5 levels, where level 0 indicates no peeling, and level 5 indicates that the peeling area exceeds 65%; Neutral Salt Spray Resistance: Determined according to the provisions of GB / T1771 - 2007; Impact Resistance: According to GB / T1732 - 2007, the height of the heavy hammer is 50 cm. Whether it is a positive impact or a reverse impact, observe whether there is any damage to the coating; Contact Angle: Tested with reference to the standard of GB / T 30447 - 2013 "Measurement Method of Contact Angle of Nanometer Films"; Pencil Hardness: Tested with reference to GB / T6739 - 2022 "Determination of Film Hardness by Pencil Method for Paints and Varnishes"; Wear Resistance: The wear resistance of the samples was tested according to GB / T 1768 - 2006 "Determination of Wear Resistance of Paints and Varnishes - Rotating Rubber Wheel Method"; The number of revolutions of the wear experiment is 800 revolutions.

[0040] Self-cleaning performance evaluation: Drop an aqueous solution of oily dye on the surface of the coating at a 45° inclination, and observe the rolling angle and residue of the droplet. This method can evaluate the anti-fouling and self-cleaning performance of the coating.

[0041] Table 1 Performance Test Analyzing the data in Table 1, it can be seen that: 1) The self-cleaning coatings prepared in Examples 1 - 3 for sanitary products have excellent adhesion, salt spray resistance, hardness, impact resistance, and hydrophobic self-cleaning performance.

[0042] 2) Through the comparative analysis of the performance of the self-cleaning coatings prepared by combining Example 3 and Comparative Example 1, it is shown that the hydrophobic modified talc powder prepared in this application first chemically grafts and modifies the surface of talc powder with N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane to introduce amino groups onto the surface of talc powder. Subsequently, through the acylation reaction of trifluoroacetic anhydride with some amino groups, trifluoromethyl groups are introduced to endow talc powder with hydrophobic self-cleaning characteristics. By adding talc powder with amino and fluorine-containing groups on the surface, among which the amino groups can react with the modified polyurethane to form chemical bonds, ensuring the firm connection between talc powder and the substrate and improving the wear resistance of the coating. The fluorine-containing groups extend outward to form a hydrophobic layer, which can endow the coating with good salt spray resistance and self-cleaning performance. In addition, fluorine atoms have a high electronegativity, which results in strong intermolecular forces between fluorine atoms. This stronger intermolecular interaction can improve the cohesion of the coating, thereby increasing the hardness, wear resistance, and self-cleaning performance of the coating.

[0043] 3) Through the comparative analysis of the performance of the self-cleaning coatings prepared by combining Example 3 and Comparative Example 2, it is shown that the modified polyurethane prepared in this application can easily achieve self-healing through appropriate molecular chain modulation. This can not only solve the problems of poor durability and wear resistance existing in current self-cleaning coatings but also improve the mechanical properties by regulating the toughness of the molecular chain through adjusting the chain segment composition. The synthesized polyurethane has good mechanical properties and substrate adhesion due to its special intermolecular hydrogen bond forces, electrostatic interactions, and layered molecular stacking structure. Disulfide bonds and hydrogen bond forces are also introduced into the structure to achieve the self-healing effect. The component obtained by compounding it with hydrophobic modified silica is added to the self-cleaning coating, which can exert a good self-cleaning effect, thereby improving the comprehensive performance of the self-cleaning coating.

[0044] 4) Comparative analysis of the performance of the self-cleaning coatings for sanitary products prepared in Example 3 and Comparative Example 3 shows that the adhesion promoter prepared in this application from hydroxypropyl acrylate, polyoxyethylene fatty alcohol ether, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, and alkenyl-grafted phytic acid can effectively improve the adhesion performance of waterborne coatings. During the whole process, each component forms a complex three-dimensional network structure through chemical bonding and interaction, enabling the adhesion promoter not only to firmly adhere to the substrate surface but also to closely combine with the modified polyurethane, thereby further improving the adhesion performance of the waterborne coatings. Among them, the phosphate group of the alkenyl-grafted phytic acid can form strong coordination bonds or covalent bonds with the hydroxyl groups or oxide layers on the substrate surface to enhance adhesion, and the unsaturated double bonds can participate in cross-linking reactions to improve the coating durability; the siloxane bonds formed by N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane have hydrogen bond interactions with the carboxyl / hydroxyl groups in the film-forming resin, further enhancing adhesion and compatibility, and thus improving the comprehensive performance of the self-cleaning coatings.

[0045] 5) Comparative analysis of the performance of the self-cleaning coatings for sanitary products prepared in Example 3 and Comparative Examples 4 - 5 shows that the dispersant consists of sodium carboxymethyl cellulose and isomeric tridecyl alcohol polyoxyethylene ether in a mass ratio of 2:3. The main function of the dispersant is to help evenly disperse the solid particles in the coating in the liquid medium and prevent particle aggregation or precipitation. The combination of the two dispersants can provide stronger dispersing ability, enabling the solid particles in the coating to be more evenly dispersed in the liquid medium. Sodium carboxymethyl cellulose and isomeric tridecyl alcohol polyoxyethylene ether can interact to form a stable dispersion system, preventing precipitation or stratification of the coating during storage and use. Sodium carboxymethyl cellulose has good viscosity and thickening properties, while isomeric tridecyl alcohol polyoxyethylene ether can improve the fluidity and coatability of the coating. The combined use of the two can improve the viscosity and stability of the coating while maintaining good rheological properties. Isomeric tridecyl alcohol polyoxyethylene ether has good emulsifying properties, which helps to improve the emulsion stability of the coating, enabling the water and other liquid components in the coating to be better dispersed and stabilized. In summary, the combined use of sodium carboxymethyl cellulose and isomeric tridecyl alcohol polyoxyethylene ether can effectively improve the dispersibility, stability, and emulsion stability of the coating, thereby enhancing the comprehensive performance of the self-cleaning coatings.

[0046] The above examples are only used to explain the technical solutions of this application and not to limit them. Although the above examples have specifically described this application, those skilled in the art should understand that they can still modify the specific implementation manners of the present invention or make equivalent substitutions. Any modification and equivalent substitution that do not depart from the spirit and scope of this application shall be covered by the protection scope of this application.

Claims

1. A self-cleaning coating for bathroom products, characterized in that: The preparation raw materials include the following by weight: 30-35 parts of modified polyurethane, 30-35 parts of hydrophobic modified talc, 2-2.5 parts of adhesion promoter, 3-4 parts of dispersant, 1.4-1.6 parts of defoaming agent, 0.5-0.8 parts of leveling agent, 1-1.5 parts of anti-settling agent and 60-70 parts of deionized water.

2. A self-cleaning coating for sanitary products according to claim 1, characterized in that: The preparation method of the modified polyurethane comprises the following steps: S21. Add 3-4 parts of ethylenediaminetetraacetic acid dianhydride and 2-3 parts of 3-amino-1-propanol to 30-35 parts of pyridine according to their mass fractions, heat to 57° C. and stir for 1-2 hours, then raise the temperature to 105° C. and continue stirring for 8 hours. After the stirring is completed, add 30 parts of deionized water, filter, wash the residue with alcohol and then dry to obtain a dihydroxy imide derivative; S22. Add 10-12 parts of polytetramethylene ether glycol, 2-2.5 parts of naphthalene diisocyanate, 3-3.5 parts of 1,8-diisocyanooctane and 0.02-0.03 parts of 2-ethylhexanoate tin to 83 parts of N-methylpyrrolidone in parts by mass, heat to 73°C and stir for 2 hours, then add 3-3.5 parts of dihydroxyimide derivative and 2-2.5 parts of 2,2'-dithiodiethanol, heat to 88°C and stir for 10 hours to polymerize, cool to room temperature after stirring, add 500 parts of deionized water to dilute, filter after precipitation, wash the residue with water and dry to obtain modified polyurethane.

3. A self-cleaning coating for sanitary products according to claim 1, characterized in that: The preparation method of the hydrophobically modified talcum powder comprises the following steps: S31. According to the mass fraction, 100 parts of talc powder are added to 300 parts of anhydrous ethanol, and ultrasonically dispersed for 30-40 minutes, and then mechanically stirred and mixed at a speed of 1500-1800 rpm for 50-60 minutes to obtain a mixed solution, and an ethanol solution of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane is slowly added dropwise to the mixed solution, and the mixture is reacted at 80-85° C. for 5-6 hours, and the mixture is centrifuged, washed, and vacuum dried to obtain talc powder modified with a silane coupling agent; S32. According to the mass proportions, add 300 parts of 2% trifluoroacetic anhydride solution in dimethylformamide and heat it to 95°C, add 100 parts of talc modified by silane coupling agent, and adjust the pH value of the dispersion to 9-10 with 10% sodium hydroxide aqueous solution, react at a constant temperature for 3-4 hours, filter, wash with water, and dry to obtain hydrophobically modified talc.

4. A self-cleaning coating for sanitary products according to claim 3, characterized in that: The mass ratio of the talc powder to the ethanol solution of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane is 1:4-5; the mass percentage of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane in the ethanol solution of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane is 15%.

5. The self-cleaning coating for sanitary products according to claim 1, characterized in that: The preparation method of the adhesion promoter comprises the following steps: S51, according to the mass fractions, 30-35 parts of phytic acid aqueous solution with a mass concentration of 25% and 4-5 parts of glycidyl acrylate are mixed, and then 0.2-0.3 parts of tetrabutylammonium bromide and 0.04-0.05 parts of hydroquinone are added, and the mixture is reacted at 92° C. and 450 rpm for 2-3 hours, extracted with butyl acetate, and then the butyl acetate is recovered by reduced pressure distillation to obtain alkenyl-grafted phytic acid; S52. Mix 12 parts of hydroxypropyl acrylate, 3.5 parts of polyoxyethylene fatty alcohol ether, and 3.5 parts of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane according to their mass proportions, add 7 parts of alkenyl grafted phytic acid under nitrogen atmosphere, 80°C, and 500 rpm stirring conditions, stir for 6-7 hours, then add 1 part of deionized water and continue stirring for 3 hours. Cool to room temperature to obtain an adhesion promoter.

6. A self-cleaning coating for sanitary products according to claim 1, characterized in that: The dispersant is composed of sodium carboxymethyl cellulose and isomeric tridecanol polyoxyethylene ether in a mass ratio of 2:

3.

7. A self-cleaning coating for sanitary products according to claim 1, characterized in that: The defoamer is German BYK defoamer BYK028.

8. The self-cleaning coating for sanitary products according to claim 1, characterized in that: The anti-settling agent is Evonik Degussa AEROSIL R972.

9. The self-cleaning coating for sanitary products according to claim 1, characterized in that: The leveling agent is German BYK leveling agent BYK-323.

10. A method for preparing a self-cleaning coating for sanitary products according to any one of claims 1 to 9, characterized in that: The following steps are involved: The modified polyurethane, hydrophobically modified talc, adhesion promoter, dispersant, defoamer, leveling agent, anti-settling agent and deionized water were mixed according to their mass proportions, stirred evenly at 50°C at a speed of 2000 r / min, and dispersed by a sand mill to a fineness of less than 5 μm to obtain a self-cleaning coating for sanitary products.

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