Saline-alkaline tolerant powder coating and preparation method thereof

Abstract

The invention relates to the technical field of powder coatings, in particular to a saline-alkaline tolerant powder coating and a preparation method thereof. Comprising the following raw materials: a triphenyl phosphate modified barite powder-fluorocarbon resin composite material, diaminodiphenyl sulfone, talcum powder, bis (2, 2, 6, 6-tetramethyl-4-piperidyl) sebacate, polyacrylate, titanium dioxide and an epoxy chloropropane-quaternary ammonium salt nano potassium titanate composite material. In a traditional coating, the compatibility between barite powder and polar components is poor due to surface hydrophobicity and chemical inertness, triphenyl phosphate is adopted for modification, phosphorus-oxygen bonds and the barite powder form chemical bonding, and an amphiphilic surface structure is formed; a protective layer is provided in cooperation with fluorocarbon resin coating; a multi-interface effect is formed with the epichlorohydrin-quaternary ammonium salt nano potassium titanate; and bis-piperidinyl sebacate is used as an interfacial compatibilizer, so that a multi-layer structure is constructed, and the dispersity and durability are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of powder coatings, and particularly relates to a salt-alkali resistant powder coating and a preparation method thereof. Background Art

[0002] Traditional salt-alkali resistant powder coatings are widely used in the field of industrial protection, but still face multiple technical challenges in practical applications.

[0003] In the protection of saline-alkali environments, barite powder is widely used due to its good saline-alkali stability. However, the compatibility of barite powder with other components in the coating system is poor, which will lead to a decline in the overall performance of the coating, especially manifested as the unsatisfactory bonding force between the coating and the substrate, and easy occurrence of adhesion failure phenomena such as peeling and falling off. At present, the industry attempts to improve the compatibility of barite powder through surface modification. However, although the compatibility of the modified barite powder is improved, its weather resistance and stability are often reduced.

[0004] In addition, the durability of the salt-alkali resistance performance of traditional formulations is poor, and it is prone to aging under strong ultraviolet irradiation conditions, manifested as problems such as powdering, cracking, and discoloration.

[0005] These problems seriously restrict the application scope and market promotion of traditional salt-alkali resistant powder coatings, and it is urgent to achieve breakthroughs through technological innovation and formulation optimization. Summary of the Invention

[0006] (1) Technical Problems to be Solved

[0007] The purpose of the present invention is to provide a salt-alkali resistant powder coating and a preparation method thereof, so as to solve the problems of poor compatibility between barite powder and other components in traditional coatings and the decline in the stability and weather resistance of modified barite powder.

[0008] (2) Technical Solutions

[0009] To achieve the above purpose, on the one hand, the present invention provides a salt-alkali resistant powder coating, including the following raw materials in parts by weight: 35-45 parts of triphenyl phosphate modified barite powder-fluorocarbon resin composite material, 8-12 parts of diaminodiphenyl sulfone, 10-15 parts of talc powder, 3-5 parts of bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, 15-20 parts of polyacrylate, and 5-8 parts of titanium dioxide.

[0010] Furthermore, a salt-alkali resistant powder coating, by weight fraction, further includes: 5-8 parts of epichlorohydrin-quaternary ammonium salt modified nano-potassium titanate composite material.

[0011] Furthermore, the preparation method of the epichlorohydrin-quaternary ammonium salt modified nano-potassium titanate composite material includes:

[0012] S11. Dry potassium titanate nanowhiskers at 105 °C for 6 - 8 h to obtain dried potassium titanate nanowhiskers. Add the dried potassium titanate nanowhiskers to deionized water to obtain a potassium titanate nanowhisker dispersion. Adjust the pH of the potassium titanate nanowhisker dispersion to 6 - 7 with 0.1 mol / L HCl solution to obtain a potassium titanate nanowhisker dispersion with adjusted pH. Filter the potassium titanate nanowhisker dispersion with adjusted pH to obtain a first precipitate. Wash the first precipitate with deionized water until neutral to obtain the washed first precipitate. Vacuum-dry the washed first precipitate at 80 - 90 °C for 12 - 15 h to obtain pretreated potassium titanate nanowhiskers;

[0013] S12. Add the pretreated potassium titanate nanowhiskers to an aqueous solution of cetyltrimethylammonium bromide with a concentration of 2 - 3 wt% to obtain a first mixture. Stir the first mixture at 70 - 80 °C and 300 - 500 rpm for 2 - 3 h to obtain a second mixture. Filter the second mixture to obtain a second precipitate. Wash the second precipitate 3 times each with deionized water and ethanol to obtain the washed second precipitate. Vacuum-dry the washed second precipitate at 60 - 70 °C for 12 - 24 h to obtain quaternized potassium titanate nanowhiskers;

[0014] S13. Add the quaternized potassium titanate nanowhiskers to absolute ethanol to obtain a third mixture. Ultrasonically disperse the third mixture for 15 min to obtain a quaternized potassium titanate nanowhisker dispersion. Add epichlorohydrin to the quaternized potassium titanate nanowhisker dispersion to obtain a fourth mixture. Heat the fourth mixture to 60 - 70 °C and stir and react at 300 - 500 rpm for 4 - 5 h to obtain a fifth mixture. Add NaOH solution to the fifth mixture to adjust the pH to 8 - 9 to obtain a sixth mixture. Continue to react the sixth mixture for 2 - 3 h to obtain a seventh mixture;

[0015] S14. Centrifuge the seventh mixture at 6000 - 8000 rpm for 10 - 20 min to obtain a third precipitate. Wash the third precipitate 3 times each with ethanol and deionized water to obtain the washed third precipitate. Vacuum-dry the washed third precipitate at 80 - 90 °C for 24 - 48 h to obtain an epichlorohydrin - quaternized potassium titanate nanowhisker composite material.

[0016] Furthermore, the preparation method of the triphenyl phosphate - modified barite powder - fluorocarbon resin composite material includes:

[0017] S21. Dry barite powder at 80 - 90 °C for 4 - 5 h to obtain pretreated barite powder;

[0018] S22. Add the pretreated barite powder to a 3 wt% triphenyl phosphate solution to obtain a first mixture. Stir and react the first mixture at 50 - 60 °C and 300 - 500 rpm for 3 - 5 h to obtain a second mixture. Filter the second mixture by suction to obtain a first precipitate. Wash the first precipitate with absolute ethanol 3 - 4 times to obtain the washed first precipitate. Vacuum dry the washed first precipitate at 60 - 70 °C for 12 - 24 h to obtain triphenyl phosphate-modified barite powder;

[0019] S23. Add fluorocarbon resin to N,N-dimethylformamide and stir at 50 - 60 °C and 300 - 500 rpm for 4 - 6 h to obtain a fluorocarbon resin solution;

[0020] S24. Add the triphenyl phosphate-modified barite powder to the fluorocarbon resin solution to obtain a third mixture. Stir the third mixture at 100 - 200 rpm for 15 - 20 min to obtain a fourth mixture. Ultrasonic the fourth mixture for 30 - 40 min to obtain a fifth mixture. Stir the fifth mixture at 300 - 500 rpm for 50 - 60 min to obtain a sixth mixture. Vacuum degas the sixth mixture for 10 - 20 min to obtain a mixed slurry;

[0021] S25. Pour the mixed slurry into a mold, first pre-dry at 70 - 80 °C for 2 - 3 h, then raise the temperature to 150 - 160 °C and keep warm for 1 - 2 h, and finally naturally cool to room temperature and demold to obtain a triphenyl phosphate-modified barite powder-fluorocarbon resin composite.

[0022] On the other hand, based on the same inventive concept, the present invention also provides a preparation method of a salt and alkali resistant powder coating, which is applied to the above-mentioned salt and alkali resistant powder coating, and includes the following steps:

[0023] S31. Vacuum dry the triphenyl phosphate-modified barite powder-fluorocarbon resin composite at 80 - 90 °C for 12 - 24 h and grind it through a 100-mesh sieve to obtain a pretreated triphenyl phosphate-modified barite powder-fluorocarbon resin composite. Vacuum dry 4,4'-diaminodiphenyl sulfone at 50 - 60 °C for 4 - 5 h and grind it through a 200-mesh sieve to obtain a pretreated 4,4'-diaminodiphenyl sulfone. Dry talcum powder at 105 - 110 °C for 6 - 7 h and grind it through a 200-mesh sieve to obtain a pretreated talcum powder. Dry polyacrylate at 50 - 60 °C for 7 - 8 h and grind it through a 120-mesh sieve to obtain a pretreated polyacrylate. Dry titanium dioxide at 110 - 120 °C for 4 - 5 h and grind it through a 200-mesh sieve to obtain a pretreated titanium dioxide. Vacuum dry the epoxy chloropropane-quaternary ammonium salt modified nano-potassium titanate composite at 70 - 80 °C for 10 - 12 h and grind it through a 200-mesh sieve to obtain a pretreated epoxy chloropropane-quaternary ammonium salt modified nano-potassium titanate composite;

[0024] S32. First, add the pretreated epoxy chloropropane-quaternary ammonium salt modified potassium titanate nanocomposite and the pretreated talc powder into a high-speed mixer, then add the pretreated polyacrylate and the pretreated titanium dioxide, and finally add the pretreated triphenyl phosphate modified barite powder-fluorocarbon resin composite and the pretreated diaminodiphenyl sulfone and bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate to obtain a mixed component. Mix the mixed component at 500-600 rpm for 5-8 min to obtain a first mixture, mix the first mixture at 1200-1500 rpm for 10-12 min to obtain a second mixture, and mix the second mixture at 2000-2200 rpm for 5-8 min to obtain a third mixture;

[0025] S33. Transport the third mixture to a twin-screw extruder. The operating parameters of the extruder are as follows: the temperature of the feeding zone is 110-120 °C, the temperature of the compression zone is 130-140 °C, the temperature of the homogenization zone is 150-160 °C, the temperature of the metering zone is 140-150 °C, the temperature of the die head is 130-140 °C, and the screw speed is 150-200 rpm to obtain a melt. Extrude the melt through a flat die orifice to obtain a molten sheet with a thickness of about 2-3 mm;

[0026] S34. Cool the extruded molten sheet on a cooling belt. The temperature of the cooling belt is 15-20 °C, and the cooling time is 5-8 min to obtain a cooled sheet. Crush the cooled sheet preliminarily with a crusher. The speed of the crusher is 800-1000 rpm, and the aperture of the sieve is 10 mm to obtain preliminarily crushed particles;

[0027] S35. Transport the preliminarily crushed particles to a turbo mill. The speed is 10000-12000 rpm, and the temperature of the cooling water is 15-20 °C. Operate continuously until all the materials are crushed to obtain a crushed product. Screen the crushed product through a 100-mesh sieve. Return the oversize to the mill for re-crushing, and collect the undersize, which is the initial powder coating;

[0028] S36. Place the initial powder coating in a fluidized bed for surface treatment. The temperature of the fluidized bed is 50-60 °C, the fluidization time is 30-40 min, and the air flow rate is 0.2-0.3 m / s to obtain a fluidized powder. Vacuum-dry the fluidized powder at 40-50 °C for 4-5 h to obtain a salt and alkali-resistant powder coating.

[0029] The action mechanisms of the above raw material components are as follows:

[0030] Triphenyl phosphate modified barite powder - fluorocarbon resin composite: The phosphor-oxygen bond in the triphenyl phosphate molecule forms a chemical bond with the surface of the barite powder, improving the surface properties of the barite powder. Its polar head combines with the barite while the non-polar phenyl tail faces outward, forming an amphiphilic structure. At the same time, the fluorocarbon resin forms a dense protective layer on its surface, providing excellent weather resistance and chemical stability, improving the compatibility between the barite powder and the resin matrix and the overall durability of the coating.

[0031] Diaminodiphenyl sulfone: As a curing agent and catalyst for the epoxy system, it promotes the ring-opening addition reaction of epoxy groups, catalyzes the reaction between epoxy groups and surface active groups (such as -OH, -COOH, etc.) of the filler during the heat curing process, and improves the thermal stability and mechanical strength of the system.

[0032] Talc powder: As an auxiliary filler, it has a good layered structure and lubricity, and can improve the leveling property and construction performance of the coating.

[0033] Bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate: As an interfacial compatibilizer, the ester group in its molecular structure can form a hydrogen bond with the surface of the filler, while the piperidine group has good compatibility with the resin matrix, forming a "molecular bridge" between the filler and the resin. In addition, its special three-dimensional structure also endows the coating with excellent ultraviolet resistance, prevents the resin from degrading under ultraviolet irradiation, and improves the weather resistance and service life of the coating.

[0034] Polyacrylate: As a dispersant and film-forming aid, its molecular chain contains a large number of carboxyl and ester groups, which can form multi-point adsorption with the surface of the filler, improving the dispersion stability of the filler in the system.

[0035] Titanium dioxide: As the main white pigment, it provides excellent hiding power, whiteness and brightness for the coating.

[0036] Epichlorohydrin - quaternary ammonium salt modified potassium titanate nanocomposite: Through the reaction of epichlorohydrin with potassium titanate nanometer and then quaternary ammonium salt treatment, a nano-filler with -NR 4 + groups on the surface is formed. This modification not only enhances the dispersibility of potassium titanate nanometer, but also forms an ion-dipole interaction with the surface of triphenyl phosphate modified barite powder. The nano-scale size of this material can fill the microvoids, improve the packing density of the system, and at the same time the layered structure provides a mechanical strengthening effect and enhances the barrier performance and corrosion resistance of the coating.

[0037] (3) Beneficial effects

[0038] Compared with the prior art, the beneficial effects of the present invention are:

[0039] 1. The surface modification of barite powder with triphenyl phosphate and the coating with fluorocarbon resin have successfully solved the problems of poor dispersibility and low compatibility with resin in the traditional barite powder in the coating system, while maintaining the excellent chemical resistance and covering power of the barite powder, and improving the uniformity and adhesion of the final coating.

[0040] 2. Through the multiple interfacial actions (ion-dipole interaction, hydrogen bond interaction, covalent crosslinking, etc.) between triphenyl phosphate-modified barite powder and quaternized potassium titanate nanosheets, as well as the molecular bridging action of bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, the saline-alkali resistance and weather resistance of the composite material are improved.

[0041] 3. The use of the structure of micron-sized flaky barite powder and nano-sized layered potassium titanate increases the packing density of the material. At the same time, surface modification reduces the surface energy of the filler, realizes the uniform dispersion of the filler in the resin matrix, and improves the saline-alkali resistance and weather resistance of the composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a physical picture of the saline-alkali resistant powder coating of Example 1 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0043] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0044] The test equipment and preparations for the following embodiments are as follows:

[0045] Electronic balance (Sartorius, Germany), electrothermal blast drying oven (Shanghai Fuma Experimental Equipment), electrothermal constant temperature water bath (Jiangsu Keduo), crusher (Shandong Tianfang Machinery), magnetic stirrer (Shanghai Meiyingpu), ball mill (Henan Zheng Mine), twin-screw extruder (Shanghai Zhouxing), vacuum shaping box (Qingdao Kunlun Haosu), vacuum drying oven (Wuxi Mary), high-speed mixer (Shandong Lanjing), ultrasonic disperser (Hangzhou Fansuo), centrifuge (Shanghai Jipu); chemical drugs and reagents are purchased from Sigma-Aldrich.

[0046] Example 1: This example discloses a saline-alkali resistant powder coating, which comprises the following raw materials in parts by weight: 38 parts of triphenyl phosphate-modified barite powder-fluorocarbon resin composite material, 11 parts of diaminodiphenyl sulfone, 12 parts of talc powder, 4 parts of bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, 16 parts of polyacrylate, and 6 parts of titanium dioxide.

[0047] The described alkali-resistant powder coating, by weight fraction, further comprises: 7 parts of epichlorohydrin-quaternized potassium titanate nanocomposite.

[0048] In traditional coating formulations, barite powder, as an important filler, although having good chemical resistance and covering power, has a highly hydrophobic and chemically inert surface, resulting in poor compatibility with polar components in the coating system such as resins and additives, seriously affecting the uniformity and adhesion of the coating.

[0049] Triphenyl phosphate is used as a modifier for barite powder. Through the phosphorus-oxygen bond in its molecular structure, a stable chemical bond is formed with the surface of barite powder. At the same time, the triphenyl structure provides a good steric hindrance effect, effectively improving the dispersibility of barite powder. During the modification process, the polar head of the triphenyl phosphate molecule binds to the surface of barite powder, and the non-polar phenyl tail faces outward, forming an amphiphilic surface structure, improving the compatibility of the modified barite powder with fluorocarbon resin. Fluorocarbon resin has excellent weather resistance and chemical stability, and can form a dense protective layer covering the surface of the modified barite powder, effectively blocking the erosion of the external environment on barite powder, solving the problem of the decline in the stability and weather resistance of barite powder in traditional modification methods.

[0050] Multiple interfacial interactions are formed between triphenyl phosphate-modified barite powder - fluorocarbon resin and epichlorohydrin-quaternized potassium titanate nanocomposite: First, the surface of the triphenyl phosphate-modified barite powder forms -O-PO 3 H 2 groups, generating ion-dipole interactions with the -NR 4 + groups on the surface of quaternized potassium titanate. This interaction enhances the binding force between the two fillers at the molecular level; Second, the C-F bonds on the fluorocarbon resin molecular chain form a permanent dipole moment due to the strong electronegativity of fluorine atoms. These polar groups can form hydrogen bonds and dipole-dipole interactions with the polar groups on the filler surface, enhancing the interfacial binding between the resin and the filler; Third, during the heat curing process, the epoxy group undergoes a ring-opening addition reaction with the active groups (such as -OH, -COOH, etc.) on the filler surface under the catalysis of an amine compound (diaminodiphenyl sulfone), forming a covalent crosslinking network, significantly improving the structural stability of the composite system.

[0051] To further stabilize the interfacial binding, bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate is introduced into the system as an interfacial compatibilizer. One end of the compound can form a hydrogen bond with the filler surface, and the other end of the piperidyl group can have good compatibility with the resin matrix, thus forming a "molecular bridge" between the filler and the resin, improving the thermal stability of the interfacial binding strength.

[0052] This composite material also optimizes its performance through multi-level structural design: micron-scale flaky barite powder and nano-scale layered potassium titanate form a multi-scale complementary structure. The larger barite powder flakes construct the basic framework, while the smaller nano potassium titanate fills the microvoids between the flakes, significantly increasing the packing density of the composite material. At the same time, through the surface modification with triphenyl phosphate and quaternary ammonium salt, the surface energy of the two fillers is reduced, their compatibility with the organic resin is increased, the interfacial wettability is improved, and the uniform dispersion of the fillers in the resin matrix is achieved. This optimized interfacial structure and dispersion state not only improve the mechanical properties of the composite material but also form a more effective protective barrier, as Figure 1 shown, enhancing the salt and alkali resistance and weather resistance of the material.

[0053] The preparation method of the epoxy chloropropane-quaternary ammonium salt modified nano potassium titanate composite material includes:

[0054] S11. Dry nano potassium titanate at 105 °C for 7 h to obtain dried nano potassium titanate. Add the dried nano potassium titanate to deionized water to obtain a nano potassium titanate dispersion. Adjust the pH of the nano potassium titanate dispersion to 6 with 0.1 mol / L HCl solution to obtain the nano potassium titanate dispersion with adjusted pH. Filter the nano potassium titanate dispersion with adjusted pH to obtain a first precipitate. Wash the first precipitate with deionized water until neutral to obtain the washed first precipitate. Vacuum dry the washed first precipitate at 85 °C for 13 h to obtain pretreated nano potassium titanate;

[0055] S12. Add the pretreated nano potassium titanate to a 2 wt% cetyltrimethylammonium bromide aqueous solution to obtain a first mixture. Stir the first mixture at 75 °C and 500 rpm for 2 h to obtain a second mixture. Filter the second mixture to obtain a second precipitate. Wash the second precipitate 3 times with deionized water and ethanol respectively to obtain the washed second precipitate. Vacuum dry the washed second precipitate at 60 °C for 20 h to obtain quaternary ammonium salt modified nano potassium titanate;

[0056] S13. Add the quaternary ammonium salt modified nano potassium titanate to absolute ethanol to obtain a third mixture. Ultrasonically disperse the third mixture for 15 min to obtain a quaternary ammonium salt modified nano potassium titanate dispersion. Add epoxy chloropropane to the quaternary ammonium salt modified nano potassium titanate dispersion to obtain a fourth mixture. Heat the fourth mixture to 65 °C and stir at 500 rpm for 5 h to obtain a fifth mixture. Add NaOH solution to the fifth mixture to adjust the pH to 8 to obtain a sixth mixture. React the sixth mixture for another 2 h to obtain a seventh mixture;

[0057] S14. Centrifuge the seventh mixture at 8000 rpm for 15 min to obtain the third precipitate. Wash the third precipitate three times each with ethanol and deionized water to obtain the washed third precipitate. Vacuum dry the washed third precipitate at 90 °C for 36 h to obtain the epichlorohydrin-quaternary ammonium salt modified potassium titanate nanocomposite.

[0058] The preparation method of the triphenyl phosphate modified barite powder-fluorocarbon resin composite material includes:

[0059] S21. Dry the barite powder at 90 °C for 5 h to obtain the pretreated barite powder;

[0060] S22. Add the pretreated barite powder to a 3 wt% triphenyl phosphate solution to obtain the first mixture. Stir and react the first mixture at 60 °C and 500 rpm for 5 h to obtain the second mixture. Filter the second mixture to obtain the first precipitate. Wash the first precipitate four times with absolute ethanol to obtain the washed first precipitate. Vacuum dry the washed first precipitate at 70 °C for 24 h to obtain the triphenyl phosphate modified barite powder;

[0061] S23. Add the fluorocarbon resin to N,N-dimethylformamide and stir at 60 °C and 500 rpm for 6 h to obtain the fluorocarbon resin solution;

[0062] S24. Add the triphenyl phosphate modified barite powder to the fluorocarbon resin solution to obtain the third mixture. Stir the third mixture at 200 rpm for 20 min to obtain the fourth mixture. Ultrasonic the fourth mixture for 40 min to obtain the fifth mixture. Stir the fifth mixture at 500 rpm for 60 min to obtain the sixth mixture. Vacuum degas the sixth mixture for 20 min to obtain the mixed slurry;

[0063] S25. Pour the mixed slurry into a mold, first pre-dry at 80 °C for 3 h, then raise the temperature to 160 °C and keep warm for 2 h, and finally naturally cool to room temperature and demold to obtain the triphenyl phosphate modified barite powder-fluorocarbon resin composite material.

[0064] A preparation method of a salt and alkali resistant powder coating, applied to the described salt and alkali resistant powder coating, includes the following steps:

[0065] S31. Vacuum-dry the triphenyl phosphate-modified barite powder-fluorocarbon resin composite at 90 °C for 24 h and grind it through a 100-mesh sieve to obtain the pretreated triphenyl phosphate-modified barite powder-fluorocarbon resin composite. Vacuum-dry the diaminodiphenyl sulfone at 60 °C for 5 h and grind it through a 200-mesh sieve to obtain the pretreated diaminodiphenyl sulfone. Dry the talc powder at 110 °C for 7 h and grind it through a 200-mesh sieve to obtain the pretreated talc powder. Dry the polyacrylate at 60 °C for 8 h and grind it through a 120-mesh sieve to obtain the pretreated polyacrylate. Dry the titanium dioxide at 120 °C for 5 h and grind it through a 200-mesh sieve to obtain the pretreated titanium dioxide. Vacuum-dry the epichlorohydrin-quaternized potassium titanate nanocomposite at 80 °C for 12 h and grind it through a 200-mesh sieve to obtain the pretreated epichlorohydrin-quaternized potassium titanate nanocomposite;

[0066] S32. First, add the pretreated epichlorohydrin-quaternized potassium titanate nanocomposite and the pretreated talc powder to a high-speed mixer, then add the pretreated polyacrylate and the pretreated titanium dioxide, and finally add the pretreated triphenyl phosphate-modified barite powder-fluorocarbon resin composite, the pretreated diaminodiphenyl sulfone, and bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate to obtain a mixed component. Mix the mixed component at 600 rpm for 8 min to obtain a first mixture, mix the first mixture at 1500 rpm for 12 min to obtain a second mixture, and mix the second mixture at 2200 rpm for 8 min to obtain a third mixture;

[0067] S33. Transfer the third mixture to a twin-screw extruder. The operating parameters of the extruder are as follows: the temperature of the feeding zone is 120 °C, the temperature of the compression zone is 140 °C, the temperature of the homogenization zone is 160 °C, the temperature of the metering zone is 150 °C, the temperature of the die head is 140 °C, and the screw speed is 200 rpm to obtain a melt. Extrude the melt through a flat die orifice to obtain a molten sheet with a thickness of about 3 mm;

[0068] S34. Cool the extruded molten sheet on a cooling belt. The temperature of the cooling belt is 20 °C and the cooling time is 8 min to obtain a cooled sheet. Roughly crush the cooled sheet with a crusher. The speed of the crusher is 1000 rpm and the screen aperture is 10 mm to obtain roughly crushed particles;

[0069] S35. Transfer the roughly crushed particles to a turbo mill. The speed is 12000 rpm and the temperature of the cooling water is 20 °C. Operate continuously until all the materials are crushed to obtain a crushed product. Screen the crushed product through a 100-mesh sieve. Return the oversize material to the mill for re-crushing and collect the undersize material, which is the initial powder coating;

[0070] S36. Put the initial powder coating into a fluidized bed for surface treatment. The temperature of the fluidized bed is 60 °C, the fluidization time is 40 min, and the air flow rate is 0.3 m / s to obtain the powder after fluidization treatment. Vacuum dry the powder after fluidization treatment at 50 °C for 5 h to obtain the powder coating resistant to saline and alkali.

[0071] Example 2: This example discloses a powder coating resistant to saline and alkali, which comprises the following raw materials in parts by weight: 35 parts of triphenyl phosphate modified barite powder - fluorocarbon resin composite, 8 parts of diaminodiphenyl sulfone, 10 parts of talc powder, 3 parts of bis(2,2,6,6 - tetramethyl - 4 - piperidyl) sebacate, 15 parts of polyacrylate, and 5 parts of titanium dioxide.

[0072] The described powder coating resistant to saline and alkali, by weight fraction, further comprises: 5 parts of epichlorohydrin - quaternary ammonium salt modified potassium titanate nanocomposite.

[0073] The preparation methods of the triphenyl phosphate modified barite powder - fluorocarbon resin composite and the epichlorohydrin - quaternary ammonium salt modified potassium titanate nanocomposite in this example are the same as those in Example 1. The preparation method of the powder coating resistant to saline and alkali in this example is the same as that in Example 1.

[0074] Example 3: This example discloses a powder coating resistant to saline and alkali, which comprises the following raw materials in parts by weight: 45 parts of triphenyl phosphate modified barite powder - fluorocarbon resin composite, 12 parts of diaminodiphenyl sulfone, 15 parts of talc powder, 5 parts of bis(2,2,6,6 - tetramethyl - 4 - piperidyl) sebacate, 20 parts of polyacrylate, and 8 parts of titanium dioxide.

[0075] The described powder coating resistant to saline and alkali, by weight fraction, further comprises: 8 parts of epichlorohydrin - quaternary ammonium salt modified potassium titanate nanocomposite.

[0076] The preparation methods of the triphenyl phosphate modified barite powder - fluorocarbon resin composite and the epichlorohydrin - quaternary ammonium salt modified potassium titanate nanocomposite in this example are the same as those in Example 1. The preparation method of the powder coating resistant to saline and alkali in this example is the same as that in Example 1.

[0077] Example 4: This example discloses a powder coating resistant to saline and alkali, which comprises the following raw materials in parts by weight: 40 parts of triphenyl phosphate modified barite powder - fluorocarbon resin composite, 10 parts of diaminodiphenyl sulfone, 12.5 parts of talc powder, 4 parts of bis(2,2,6,6 - tetramethyl - 4 - piperidyl) sebacate, 17.5 parts of polyacrylate, and 6.5 parts of titanium dioxide.

[0078] The described powder coating resistant to saline and alkali, by weight fraction, further comprises: 6.5 parts of epichlorohydrin - quaternary ammonium salt modified potassium titanate nanocomposite.

[0079] The preparation method of the triphenyl phosphate modified barite powder-fluorocarbon resin composite material and the epichlorohydrin-quaternary ammonium salt modified potassium titanate nanocomposite material in this example is the same as that in Example 1. The preparation method of a salt and alkali resistant powder coating in this example is the same as that in Example 1.

[0080] Example 5: This example discloses a salt and alkali resistant powder coating, which comprises the following raw materials in parts by weight: 42 parts of triphenyl phosphate modified barite powder-fluorocarbon resin composite material, 9 parts of diaminodiphenyl sulfone, 13 parts of talc powder, 5 parts of bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, 17 parts of polyacrylate, and 7 parts of titanium dioxide.

[0081] The above-mentioned salt and alkali resistant powder coating further comprises 5 parts of epichlorohydrin-quaternary ammonium salt modified potassium titanate nanocomposite material by weight fraction.

[0082] The preparation method of the triphenyl phosphate modified barite powder-fluorocarbon resin composite material and the epichlorohydrin-quaternary ammonium salt modified potassium titanate nanocomposite material in this example is the same as that in Example 1. The preparation method of a salt and alkali resistant powder coating in this example is the same as that in Example 1.

[0083] Control Group 1: This example discloses a salt and alkali resistant powder coating, which comprises the following raw materials in parts by weight: 38 parts of fluorocarbon resin, 11 parts of diaminodiphenyl sulfone, 12 parts of talc powder, 4 parts of bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, 16 parts of polyacrylate, and 6 parts of titanium dioxide.

[0084] The above-mentioned salt and alkali resistant powder coating further comprises 7 parts of epichlorohydrin-quaternary ammonium salt modified potassium titanate nanocomposite material by weight fraction.

[0085] The preparation method of the fluorocarbon resin and the epichlorohydrin-quaternary ammonium salt modified potassium titanate nanocomposite material in this example is the same as that in Example 1. The preparation method of a salt and alkali resistant powder coating in this example is the same as that in Example 1.

[0086] Control Group 2: This example discloses a salt and alkali resistant powder coating, which comprises the following raw materials in parts by weight: 38 parts of barite powder-fluorocarbon resin composite material, 11 parts of diaminodiphenyl sulfone, 12 parts of talc powder, 4 parts of bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, 16 parts of polyacrylate, and 6 parts of titanium dioxide.

[0087] The above-mentioned salt and alkali resistant powder coating further comprises 7 parts of epichlorohydrin-quaternary ammonium salt modified potassium titanate nanocomposite material by weight fraction.

[0088] The preparation methods of the barite powder-fluorocarbon resin composite material and the epichlorohydrin-quaternary ammonium salt modified potassium titanate nanocomposite material in this example are the same as those in Example 1. The preparation method of a salt and alkali resistant powder coating in this example is the same as that in Example 1.

[0089] Control Group 3: This example discloses a salt and alkali resistant powder coating, which includes the following raw materials in parts by weight: 38 parts of triphenyl phosphate modified barite powder-fluorocarbon resin composite material, 11 parts of diaminodiphenyl sulfone, 12 parts of talc powder, 16 parts of polyacrylate, and 6 parts of titanium dioxide.

[0090] The above-mentioned salt and alkali resistant powder coating, by weight fraction, further includes: 7 parts of epichlorohydrin-quaternary ammonium salt modified potassium titanate nanocomposite material.

[0091] The preparation methods of the triphenyl phosphate modified barite powder-fluorocarbon resin composite material and the epichlorohydrin-quaternary ammonium salt modified potassium titanate nanocomposite material in this example are the same as those in Example 1. The preparation method of a salt and alkali resistant powder coating in this example is the same as that in Example 1.

[0092] Control Group 4: This example discloses a salt and alkali resistant powder coating, which includes the following raw materials in parts by weight: 38 parts of triphenyl phosphate modified barite powder-fluorocarbon resin composite material, 11 parts of diaminodiphenyl sulfone, 12 parts of talc powder, 4 parts of bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, 16 parts of polyacrylate, and 6 parts of titanium dioxide.

[0093] The above-mentioned salt and alkali resistant powder coating, by weight fraction, further includes: 7 parts of quaternary ammonium salt modified potassium titanate nanocomposite material.

[0094] The preparation methods of the triphenyl phosphate modified barite powder-fluorocarbon resin composite material and the quaternary ammonium salt modified potassium titanate nanocomposite material in this example are the same as those in Example 1. The preparation method of a salt and alkali resistant powder coating in this example is the same as that in Example 1.

[0095] Control Group 5: This example discloses a salt and alkali resistant powder coating, which includes the following raw materials in parts by weight: 38 parts of triphenyl phosphate modified barite powder-fluorocarbon resin composite material, 11 parts of diaminodiphenyl sulfone, 12 parts of talc powder, 4 parts of bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, 16 parts of polyacrylate, and 6 parts of titanium dioxide.

[0096] The above-mentioned salt and alkali resistant powder coating, by weight fraction, further includes: 7 parts of epichlorohydrin-potassium titanate nanocomposite material.

[0097] The preparation methods of the triphenyl phosphate modified barite powder-fluorocarbon resin composite material and the epichlorohydrin-potassium titanate nanocomposite material in this example are the same as those in Example 1. The preparation method of a kind of powder coating resistant to saline-alkali in this example is the same as that in Example 1.

[0098] Control Group 6: This example discloses a kind of powder coating resistant to saline-alkali, which comprises the following raw materials in parts by weight: 38 parts of triphenyl phosphate modified barite powder-fluorocarbon resin composite material, 11 parts of diaminodiphenyl sulfone, 12 parts of talc powder, 4 parts of bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, 16 parts of polyacrylate, and 6 parts of titanium dioxide.

[0099] The preparation method of the triphenyl phosphate modified barite powder-fluorocarbon resin composite material in this example is the same as that in Example 1. The preparation method of a kind of powder coating resistant to saline-alkali in this example is the same as that in Example 1.

[0100] Test verification:

[0101] 1. Contact angle measurement: The samples of the example group and the control group are prepared into flat discs (diameter 13 mm, thickness 2 mm). The test temperature is room temperature (23±2 °C), the test relative humidity is (50±5%), and the test liquids are deionized water, diiodomethane, and glycerol. The samples are placed on the test bench, and 2 μL of the test liquid is added dropwise using a micro syringe, and the average contact angle is recorded.

[0102] 2. Dynamic mechanical analysis (DMA): The samples of the example group and the control group are prepared with dimensions of 35 mm×10 mm×2 mm, and the surface should be flat and bubble-free. A dynamic analyzer is used, and the test temperature range is -50 °C to 150 °C, and the heating rate is 3 °C / min.

[0103] 3. Saline-alkali resistance performance test: The samples of the example group and the control group are prepared with dimensions of 150 mm×70 mm×2 mm, and the surface should be flat and smooth. Record the initial weight, prepare a 5% NaOH solution, and the soaking temperature is 40±2 °C, and the time is 7 d, 14 d, and 28 d.

[0104] 4. Weather resistance test: The samples of the example group and the control group are prepared with dimensions of 150 mm×70 mm×2 mm, and the surface should be flat and smooth. Record the initial color and gloss, and use an ultraviolet aging test chamber for 500 h of ultraviolet accelerated aging.

[0105] Table 1 Contact angle test results (°)

[0106]

[0107]

[0108] Table 2 Dynamic mechanical analysis (DMA) results

[0109] Sample Storage modulus E'(MPa) Tg (°C) tanδ peak Example 1 3200 135 0.28 Example 2 2850 1 28 0.35 Example 3 2900 129 0.34 Example 4 2880 127 0.36 Example 5 2820 126 0.37 Control Group 1 1800 105 0.65 Control Group 2 1900 108 0.62 Control Group 3 1650 102 0.72 Control Group 4 1750 104 0.68 Control Group 5 1700 103 0.70 Control Group 6 1680 102 0.71

[0110] Table 3 Salt and Alkali Resistance Performance Test (Weight Loss Rate %)

[0111]

[0112]

[0113] Table 4 Weather Resistance Test (After 500 h)

[0114] Sample Gloss retention rate (%) Yellowing index (ΔYI) Example 1 95 1.2 Example 2 88 2.5 Example 3 89 2.3 Example 4 87 2.6 Example 5 86 2.8 Control Group 1 65 6.8 Control Group 2 68 6.2 Control Group 3 58 7.8 Control Group 4 62 7.2 Control Group 5 60 7.5 Control Group 6 59 7.6

[0115] According to the comprehensive analysis of the table data, Examples 1-5 exhibit significantly better comprehensive performance than Control Groups 1-6. From the contact angle test results in Table 1, the water contact angles of the example groups are generally between 105° and 115°, significantly higher than those of the control groups, which are between 75° and 85°, indicating that the surface of the modified coating has better hydrophobicity. This improvement in hydrophobicity is mainly due to the successful surface modification of triphenyl phosphate and quaternary ammonium salt, which reduces the surface energy of the filler and achieves excellent interfacial wettability. Among them, Example 1 reaches the optimal water contact angle of 115°.

[0116] The results of dynamic mechanical analysis (DMA) show that the storage modulus of the example groups is significantly higher than that of the control groups. Among them, Example 1 reaches 3200 MPa, while the control groups are only in the range of 1650-1900 MPa. The glass transition temperature (Tg) also shows a similar trend. The Tg values of the example groups are generally between 126°C and 135°C, about 20-30°C higher than those of the control groups. The lower tanδ peak values (0.28-0.37) indicate that the example groups have better elastic response and energy loss characteristics, which is attributed to the formation of multiple interfacial interactions and covalent crosslinking networks.

[0117] In the salt and alkali resistance performance test, the example groups show excellent chemical stability. After 28 days of testing, the weight loss rate of Example 1 is only 1.2%, while the loss rates of the control groups are as high as 8.2-9.8%. This significant difference confirms the synergistic protection effect of triphenyl phosphate-modified and quaternary ammonium salt-modified potassium titanate nanocomposites. Control Group 3 (without an interfacial compatibilizer) performs the worst, confirming the importance of bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate as a "molecular bridge". Its ester group forms hydrogen bonds with the filler surface, and the piperidine group is compatible with the resin matrix, significantly enhancing the interfacial bonding strength.

[0118] The weather resistance test further verified the excellent performance of the modified coating. The example group maintained a gloss retention rate of 86-95% after 500 hours of exposure, and the yellowing index was only 1.2-2.8. While the gloss retention rate of the control group decreased to 58-68%, and the yellowing index reached 6.2-7.8.

[0119] These data reasonably prove that the formulation of Example 1 has the best comprehensive performance, and also verify the important role of each component in the material performance.

[0120] Finally, it should be noted that although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A salt-alkali resistant powder coating, characterized in that: The invention comprises the following raw materials in parts by weight: 35-45 parts of triphenyl phosphate modified barite powder-fluorocarbon resin composite material, 8-12 parts of diaminodiphenyl sulfone, 10-15 parts of talc powder, 3-5 parts of bis(2,2,6,6-tetramethyl-4-piperidinyl)sebacate, 15-20 parts of polyacrylate, 5-8 parts of titanium dioxide and 5-8 parts of epichlorohydrin-quaternary ammonium salt nano potassium titanate composite material.

2. A salt-alkali resistant powder coating as claimed in claim 1, characterized in that: The preparation method of the epichlorohydrin-quaternary ammonium salt nano-potassium titanate composite material comprises: S11. Dry the nano potassium titanate at 105° C. for 6 to 8 hours to obtain dried nano potassium titanate, add the dried nano potassium titanate to deionized water to obtain a nano potassium titanate dispersion, adjust the pH of the nano potassium titanate dispersion to 6 to 7 with a 0.1 mol / L HCl solution to obtain a nano potassium titanate dispersion after adjusting the pH, filter the nano potassium titanate dispersion after adjusting the pH to obtain a first precipitate, wash the first precipitate with deionized water until neutral to obtain a washed first precipitate, and vacuum dry the washed first precipitate at 80 to 90° C. for 12 to 15 hours to obtain pretreated nano potassium titanate; S12. The pretreated nano-potassium titanate is added to a 2-3 wt% aqueous solution of hexadecyltrimethylammonium bromide to obtain a first mixed solution, the first mixed solution is stirred at 70-80° C. and 300-500 rpm for 2-3 h to obtain a second mixed solution, the second mixed solution is filtered to obtain a second precipitate, the second precipitate is washed with deionized water and ethanol for 3 times each to obtain a washed second precipitate, the washed second precipitate is vacuum dried at 60-70° C. for 12-24 h to obtain a quaternary ammonium salt nano-potassium titanate; S13. Add quaternary ammonium salted nano potassium titanate to anhydrous ethanol to obtain a third mixed solution, ultrasonically disperse the third mixed solution for 15 minutes to obtain a quaternary ammonium salted nano potassium titanate dispersion, add epichlorohydrin to the quaternary ammonium salted nano potassium titanate dispersion to obtain a fourth mixed solution, heat the fourth mixed solution to 60-70° C., stir at 300-500 rpm for 4-5 hours to obtain a fifth mixed solution, add NaOH solution to the fifth mixed solution to adjust the pH to 8-9 to obtain a sixth mixed solution, and continue to react the sixth mixed solution for 2-3 hours to obtain a seventh mixed solution; S14. Centrifuge the seventh mixed solution at 6000-8000 rpm for 10-20 min to obtain a third precipitate, wash the third precipitate with ethanol and deionized water for 3 times respectively to obtain a washed third precipitate, and vacuum dry the washed third precipitate at 80-90° C. for 24-48 h to obtain an epichlorohydrin-quaternary ammonium salt nano-potassium titanate composite material.

3. The salt-alkali resistant powder coating according to claim 1, characterized in that: The preparation method of the triphenyl phosphate modified barite powder-fluorocarbon resin composite material comprises: S21. Drying the barite powder at 80-90° C. for 4-5 h to obtain pretreated barite powder; S22. The pretreated barite powder is added to a 3wt% triphenyl phosphate solution to obtain a first mixed solution, the first mixed solution is stirred at 50-60°C, 300-500rpm for 3-5h to obtain a second mixed solution, the second mixed solution is filtered to obtain a first precipitate, the first precipitate is washed with anhydrous ethanol 3-4 times to obtain a washed first precipitate, the washed first precipitate is vacuum dried at 60-70°C for 12-24h to obtain triphenyl phosphate modified barite powder; S23. Adding a fluorocarbon resin to N,N-dimethylformamide and stirring at 50 to 60° C. and 300 to 500 rpm for 4 to 6 hours to obtain a fluorocarbon resin solution; S24. Add triphenyl phosphate modified barite powder to the fluorocarbon resin solution to obtain a third mixed solution, stir the third mixed solution at 100-200 rpm for 15-20 min to obtain a fourth mixed solution, ultrasonicate the fourth mixed solution for 30-40 min to obtain a fifth mixed solution, stir the fifth mixed solution at 300-500 rpm for 50-60 min to obtain a sixth mixed solution, and vacuum degas the sixth mixed solution for 10-20 min to obtain a mixed slurry; S25. Pour the mixed slurry into a mold, first pre-dry at 70-80°C for 2-3 hours, then heat to 150-160°C and keep warm for 1-2 hours, finally naturally cool to room temperature, demold, and obtain a triphenyl phosphate modified barite powder-fluorocarbon resin composite material.

4. A method for preparing a salt-alkali resistant powder coating, which is used to prepare the salt-alkali resistant powder coating as claimed in any one of claims 1 to 3, characterized in that: The method comprises the following steps: S31. The triphenyl phosphate modified barite powder-fluorocarbon resin composite material is vacuum dried at 80-90°C for 12-24 hours and ground through a 100-mesh sieve to obtain a pretreated triphenyl phosphate modified barite powder-fluorocarbon resin composite material, diaminodiphenyl sulfone is vacuum dried at 50-60°C for 4-5 hours and ground through a 200-mesh sieve to obtain a pretreated diaminodiphenyl sulfone, talcum powder is dried at 105-110°C for 6-7 hours and ground through a 200-mesh sieve to obtain a pretreated talcum powder, drying polyacrylate at 50-60° C. for 7-8 hours and grinding through a 120-mesh sieve to obtain pretreated polyacrylate, drying titanium dioxide at 110-120° C. for 4-5 hours and grinding through a 200-mesh sieve to obtain pretreated titanium dioxide, and vacuum drying the epichlorohydrin-quaternary ammonium salt nano-potassium titanate composite material at 70-80° C. for 10-12 hours and grinding through a 200-mesh sieve to obtain a pretreated epichlorohydrin-quaternary ammonium salt nano-potassium titanate composite material; S32. First, add the pretreated epichlorohydrin-quaternary ammonium salt nano-potassium titanate composite material and the pretreated talc powder into a high-speed mixer, then add the pretreated polyacrylate and the pretreated titanium dioxide, and finally add the pretreated triphenyl phosphate modified barite powder-fluorocarbon resin composite material and the pretreated diaminodiphenyl sulfone and bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate to obtain a mixed component, mix the mixed component at 500-600rpm for 5-8min to obtain a first mixture, mix the first mixture at 1200-1500rpm for 10-12min to obtain a second mixture, mix the second mixture at 2000-2200rpm for 5-8min to obtain a third mixture; S33. The third mixture is conveyed to a twin-screw extruder, and the operating parameters of the extruder are: a feeding zone temperature of 110 to 120°C, a compression zone temperature of 130 to 140°C, a homogenization zone temperature of 150 to 160°C, a metering zone temperature of 140 to 150°C, a die temperature of 130 to 140°C, and a screw speed of 150 to 200 rpm to obtain a melt, and the melt is extruded through a flat die to obtain a molten sheet having a thickness of about 2 to 3 mm; S34. The extruded molten sheet is cooled on a cooling belt at a temperature of 15 to 20°C for a cooling time of 5 to 8 min to obtain a cooled sheet, and the cooled sheet is initially crushed by a crusher at a crusher speed of 800 to 1000 rpm and a sieve aperture of 10 mm to obtain initially crushed particles; S35. The preliminary crushed particles are conveyed to a turbine grinder at a speed of 10,000 to 12,000 rpm and a cooling water temperature of 15 to 20 ° C. The operation is continued until all the materials are crushed to obtain a crushed product, and the crushed product is sieved through a 100-mesh sieve, and the sieve is returned to the grinder for re-crushing, and the sieve is collected, which is the initial powder coating; S36. Place the initial powder coating in a fluidized bed for surface treatment at a temperature of 50-60°C, a fluidization time of 30-40 min, and an air flow rate of 0.2-0.3 m / s to obtain a fluidized powder. Vacuum dry the fluidized powder at 40-50°C for 4-5 h to obtain a salt- and alkali-resistant powder coating.

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