Acrylic acid composite rust converting agent of organic acid modified aluminum tripolyphosphate

Abstract

The invention provides an acrylic acid composite rust converting agent of organic acid modified aluminum triphosphate. The acrylic acid composite rust converting agent comprises an acrylic emulsion component A, an organic acid component B and an aluminum triphosphate component C, wherein the component A is prepared by mixing an acrylic emulsion, a coalescing agent and deionized water according to the mass ratio of (5-15): (0.3-0.5): (6-12); and the component B is prepared from ethanol, deionized water, isopropanol, ethylene glycol and organic acid according to a mass ratio of (5-10): (5-10): (0.1-1): (0.1-0.5): (3-6). And the component C is aluminum triphosphate powder. Wherein the component A, the component B and the component C are added according to the mass ratio of (10-30): (8-25): (0.2-5). According to the invention, rusted Q235 carbon steel is taken as a test object, which proves that the composite rust transforming agent has excellent rust transforming performance, can effectively treat corrosion traces on the surface of the Q235 carbon steel, and is of great significance to subsequent protection of a metal substrate.

Description

Technical Field

[0001] The present invention relates to the technical fields of the synthesis of polymer materials and the metal surface treatment technology, and particularly to an acrylic composite rust converter modified by an organic acid and aluminum tripolyphosphate. Background Art

[0002] Metal resources are a huge treasure bestowed by nature on mankind. However, due to its spontaneous corrosion tendency, metal has also made mankind pay a heavy price. Before covering the protective layer on the steel surface, rust removal must be carried out first to clean the steel surface and produce a certain roughness, so as to ensure a good bonding force between the covering layer and the substrate. Otherwise, the service life of the anti-corrosion coating will be reduced due to the continuous expansion of rust. Rust treatment is an essential pretreatment process for the long-term application of anti-corrosion coatings.

[0003] At present, the rust removal technologies mainly include mechanical rust removal, sandblasting, flame rust removal, and chemical rust removal, etc. These methods all have obvious deficiencies. For example, mechanical manual rust removal, etc. will be restricted by the workpiece structure and is prone to cause dust pollution; the strong acids used in chemical rust removal will affect the performance of the substrate. In addition, the waste liquid treatment after rust removal is difficult and pollutes the environment. In view of the above problems, a large number of studies have been carried out in the industry. New rust treatment materials usually use a variety of organic weak acids to reduce the damage to the substrate while removing rust; the rust-inhibiting coatings with rust can be directly coated on the metal surface that has not been completely rust-removed, and can endow the substrate with a certain protective effect while converting rust. With the development of various technologies, the current anti-rust coatings with a single action mechanism can no longer meet the actual needs. The research on anti-rust coatings should focus on the synergistic action of multiple mechanisms to jointly improve the corrosion resistance of the coatings on the rusted metal surface.

[0004] Here, we propose an acrylic composite rust converter modified by an organic acid and aluminum tripolyphosphate. The main components of this rust conversion system, aluminum tripolyphosphate and organic acid, reduce the influence on the system stability. The acrylic emulsion has a physical isolation and corrosion inhibition protection effect. Aluminum tripolyphosphate has the ability to capture metal ions, with strong chelating power, and can passivate the metal surface to prevent rusting. A variety of organic acids are added to modify aluminum tripolyphosphate in the experiment, and all three have a chelating effect. Through the synergistic effect, the rust conversion rate and the rust prevention performance are improved, and the disadvantage of the relatively weak early rust prevention performance of using aluminum tripolyphosphate alone is significantly improved. Summary of the Invention

[0005] The technical task of the present invention is to provide a brand-new rust treatment method with excellent rust treatment ability, low cost and environmental friendliness in view of the deficiencies of the existing technology.

[0006] The innovation points of the present invention are mainly in the following aspects: 1. The present invention uses organic acids to modify aluminum tripolyphosphate. The organic acids have good wettability and permeability, which improves the dispersibility of aluminum tripolyphosphate. The addition of organic acids can prevent the microcrystals of tripolyphosphate ions from colliding with each other through electrostatic repulsion and reduce agglomeration. 2. The organic acids used in the present invention are weakly acidic and mostly come from natural extracts. They can react with rust and reduce the impact on the system stability, which is environmentally friendly and green. 3. The organic acid modification adopted in the present invention not only can chelate with rust, but also can produce a synergistic effect with aluminum tripolyphosphate. After the organic acid modification, the rust conversion effect far exceeds the simple superposition of the three, and can achieve an excellent rust conversion effect.

[0007] The technical solution adopted by the present invention to solve its technical problems is as follows: 1. An acrylic composite rust converter modified with organic acid aluminum tripolyphosphate, comprising an acrylic emulsion A component, an organic acid B component, and an aluminum tripolyphosphate C component: Among them, the acrylic emulsion A component solution is prepared by mixing acrylic emulsion, film-forming aid, and deionized water in a mass ratio of 5–15:0.3–0.5:6–12; the organic acid B component is prepared by ethanol, deionized water, isopropanol, ethylene glycol, and organic acid in a mass ratio of 5–10:5–10:0.1–1:0.1–0.5:3–6. The C component is a separate aluminum tripolyphosphate powder. Among them, the acrylic emulsion A component, the organic acid B component, and the aluminum tripolyphosphate C component are added in a mass ratio of 10–30:8–25:0.2–5; Mix the acrylic emulsion A component, the organic acid B component, and the aluminum tripolyphosphate C component and stir evenly. While stirring, add a few drops of defoaming agent and stir at room temperature for 20–50 minutes to make the composite rust converter. Place the rusted steel sheet in a petri dish, add the prepared rust converter to the petri dish to cover the rusted steel sheet, take it out after soaking for 0.5–3 hours, and wash the residual acrylic emulsion with absolute ethanol. After drying, put the sample into an oven for further use.

[0008] 2. The present invention further provides a preparation method of an acrylic composite rust converter modified with organic acid aluminum tripolyphosphate, and the specific implementation steps are as follows: 1) Synthesis of the A component acrylic emulsion: Weigh acrylic emulsion, film-forming aid, and deionized water in a mass ratio of 5–15:0.3–0.5:6–12, and the order of adding the drugs is as follows: 1.1) First mix the acrylic emulsion and deionized water, and stir at a speed of 300–1000 rmp for 0.5–1 hour within a temperature range of 20–35 °C; 1.2) Then, add a film-forming auxiliary agent and stir at a rotation speed of 200 - 500 rmp for 0.5 - 1 hour within the temperature range of 20 - 35°C; 2) Preparation of organic acid B component: Weigh ethanol, deionized water, isopropanol, ethylene glycol, and organic acid according to the mass ratio of 5 - 10:5 - 10:0.1 - 1:0.1 - 0.5:3 - 6, and stir at a rotation speed of 300 - 700 rpm for 10 - 50 minutes to mix ethanol, deionized water, isopropanol, and ethylene glycol evenly. Subsequently, add different types of organic acids to the mixed solution and stir at a rotation speed of 300 - 700 rpm for 10 - 50 minutes to mix all raw materials evenly; 3) Preparation of the composite rust converter: Weigh the organic acid B component and aluminum tripolyphosphate C component according to the mass ratio of 8 - 25:0.2 - 5, slowly add the aluminum tripolyphosphate powder to the B component, and stir at a rotation speed of 300 - 1000 rmp for 0.5 - 2 hours within the temperature range of 20 - 35°C. Mix and stir evenly the acrylic emulsion A component, organic acid B component, and aluminum tripolyphosphate C component according to the mass ratio of 10 - 30:8 - 25:0.2 - 5, add a few drops of defoaming agent while stirring, and stir at room temperature for 20 - 50 minutes to prepare the composite rust converter; 4) Rust treatment method and steps: Place the rusted Q235 steel sheet in a petri dish, add the prepared rust converter to the petri dish to cover the rusted steel sheet, take it out after soaking for 0.5 - 3 hours, and wash the residual acrylic emulsion with absolute ethanol. After drying, put the sample into an oven for further use.

[0009] According to the embodiments of the present invention, the acrylic emulsion can be selected from one or more of pure acrylic emulsion, styrene-acrylic emulsion, silicone-acrylic emulsion, fluorine-acrylic emulsion, vinyl acetate-acrylic emulsion, etc.; According to the embodiments of the present invention, the film-forming auxiliary agent can be selected from one or more of alcohol ester-12, fatty acid ethyl ester, isooctyl fatty acid ester, ethyl oleate, etc.; According to the embodiments of the present invention, the organic acid is any one or more of gluconic acid, ferrocyanic acid, organic phosphonic acid, tannic acid, citric acid, gallic acid, etc.; According to the embodiments of the present invention, the defoaming agent can be selected from one or more of polyether-modified silicone defoaming agents, silicone defoaming agents, polyester-modified defoaming agents, etc.; 3. Among them, the metal substrate for surface rust removal treatment can be steel materials with wide applications, or other materials such as iron.

[0010] The beneficial effects of the acrylic composite rust converter modified by organic acid of aluminum tripolyphosphate of the present invention compared with the prior art are: 1. The present invention modifies aluminum tripolyphosphate with organic acids. The organic acids have good wettability and permeability, which improves the dispersibility of aluminum tripolyphosphate. The addition of organic acids can prevent the microcrystals of tripolyphosphate ions from colliding with each other through electrostatic repulsion and reduce agglomeration. The modification with organic acids significantly improves the deficiencies of using aluminum tripolyphosphate alone for rust conversion; 2. The organic acids used in the present invention are weakly acidic and mostly come from natural extracts. They can not only react with rust but also reduce the impact on the stability of the system. The raw materials for rust conversion are environmentally friendly and green, avoiding problems such as waste liquid treatment that are prone to cause secondary pollution, and providing a new strategy for the field of rust treatment; 3. The organic acid modification adopted in the present invention not only chelates with rust but also has a synergistic effect with aluminum tripolyphosphate. After the organic acid modification, the rust conversion effect far exceeds the simple superposition of the three, and can achieve an excellent rust conversion effect. Description of the Drawings

[0011] Appendix Figure 1 is a comparison physical photo of the steel sheet treated with the composite rust converter in Example 1 of the present invention and the rusty Q235 steel sheet.

[0012] Appendix Figure 2 is the optical morphology and surface roughness diagram of the steel sheet treated with the composite rust converter in Example 1 of the present invention and the rusty Q235 steel sheet.

[0013] Appendix Figure 3 is the scanning electron microscope photo of the steel sheet treated with the composite rust converter in Example 1 of the present invention, the steel sheet converted by aluminum tripolyphosphate alone, and the rusty Q235 steel sheet.

[0014] Appendix Figure 4 is the XRD pattern of the steel sheet treated with the composite rust converter in Example 1 of the present invention, the steel sheet converted by aluminum tripolyphosphate alone, and the rusty Q235 steel sheet.

[0015] Appendix Figure 5 is the FT-IR spectrum analysis diagram of the steel sheet treated with the composite rust converter in Example 1 of the present invention, the steel sheet converted by aluminum tripolyphosphate alone, and the rusty Q235 steel sheet.

[0016] Appendix Figure 6 is a comparison physical photo of the steel sheet treated with the composite rust converter in Example 2 of the present invention and the rusty Q235 steel sheet.

[0017] Appendix Figure 7 is the Raman spectrum comparison diagram of the steel sheet treated with the composite rust converter in Example 2 of the present invention, the steel sheet converted by aluminum tripolyphosphate alone, and the rusty Q235 steel sheet.

[0018] Appendix Figure 8XPS spectra of the steel sheet treated with the composite rust converter in Example 2 of the present invention, the steel sheet converted by aluminum tripolyphosphate alone, and the rusty Q235 steel sheet.

[0019] Appendix Figure 9 Physical comparison photos of the steel sheet treated with the composite rust converter in Example 3 of the present invention and the rusty Q235 steel sheet.

[0020] Appendix Figure 10 Adhesion test result diagram of the epoxy coating on the surface of the steel sheet treated with the composite rust converter in Example 3 of the present invention, the steel sheet converted by aluminum tripolyphosphate alone, and the rusty Q235 steel sheet.

[0021] Appendix Figure 11 Physical comparison photos of the steel sheet treated with the composite rust converter in Example 4 of the present invention and the rusty Q235 steel sheet after 96-hour neutral salt spray test.

[0022] Appendix Figure 12 DSC-TG curve diagram of the conversion film formed by the reaction of the composite rust converter in Example 4 of the present invention with rust during heating.

[0023] Appendix Figure 13 Open circuit voltage curve diagram of the steel sheet treated with the composite rust converter in Example 5 of the present invention, the steel sheet converted by aluminum tripolyphosphate alone, and the rusty Q235 steel sheet.

[0024] Appendix Figure 14 Electrochemical impedance analysis test results of the steel sheet treated with the composite rust converter in Example 5 of the present invention, the steel sheet converted by aluminum tripolyphosphate alone, and the rusty Q235 steel sheet. Detailed implementation manners

[0025] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with 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 of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0026] The present invention provides an acrylic composite rust converter modified by organic acid for aluminum tripolyphosphate, which includes acrylic emulsion component A, organic acid component B, and aluminum tripolyphosphate component C: Among them, the acrylic emulsion A component solution is prepared by mixing acrylic emulsion, film-forming aid and deionized water in a mass ratio of 5–15:0.3–0.5:6–12; the organic acid B component is prepared by mixing ethanol, deionized water, isopropanol, ethylene glycol and organic acid in a mass ratio of 5–10:5–10:0.1–1:0.1–0.5:3–6. The C component is a separate aluminum tripolyphosphate powder. Among them, the acrylic emulsion A component, the organic acid B component and the aluminum tripolyphosphate C component are added in a mass ratio of 10–30:8–25:0.2–5; Mix the acrylic emulsion A component, the organic acid B component and the aluminum tripolyphosphate C component and stir evenly. While stirring, add a few drops of defoaming agent and stir at room temperature for 20–50 minutes to prepare the composite rust converter. Place the rusty steel sheet in a petri dish, add the prepared rust converter to the petri dish to cover the rusty steel sheet, take it out after soaking for 0.5–3 hours, and wash the remaining acrylic emulsion with absolute ethanol. After drying, put the sample into an oven for further use.

[0027] The present invention further provides a preparation method of an acrylic composite rust converter modified by an organic acid aluminum tripolyphosphate, and the specific implementation steps are as follows: 1) Synthesis of acrylic emulsion A component: Weigh acrylic emulsion, film-forming aid and deionized water in a mass ratio of 5–15:0.3–0.5:6–12. The order of adding the drugs is as follows: 1.1) First mix the acrylic emulsion and deionized water, and stir at a speed of 300–1000 rmp for 0.5–1 hour within the temperature range of 20–35 °C; 1.2) Then add the film-forming aid, and stir at a speed of 200–500 rmp for 0.5–1 hour within the temperature range of 20–35 °C; 2) Preparation of organic acid B component: Weigh ethanol, deionized water, isopropanol, ethylene glycol and organic acid in a mass ratio of 5–10:5–10:0.1–1:0.1–0.5:3–6, and stir at a speed of 300–700 rpm for 10–50 minutes to make ethanol, deionized water, isopropanol and ethylene glycol mix evenly. Subsequently, add different kinds of organic acids to the mixed solution and stir at a speed of 300–700 rpm for 10–50 minutes to make all raw materials mix evenly; 3) Preparation of the composite rust converter: Weigh the organic acid component B and the aluminum tripolyphosphate component C according to the mass ratio of 8–25:0.2–5. Slowly add the aluminum tripolyphosphate powder to component B and stir at a speed of 300–1000 rmp for 0.5–2 hours within the temperature range of 20–35°C. Mix and stir evenly the acrylic emulsion component A, the organic acid component B, and the aluminum tripolyphosphate component C according to the mass ratio of 10–30:8–25:0.2–5, and add a few drops of defoamer during stirring. Stir at room temperature for 20–50 minutes to prepare the composite rust converter; 4) Rust treatment method and steps: Place the rusted Q235 steel sheet in a petri dish, add the prepared rust converter to the petri dish to cover the rusted steel sheet, take it out after soaking for 0.5–3 hours, and wash the residual acrylic emulsion with absolute ethanol. After drying, put the sample into an oven for further use.

[0028] Among them, the acrylic emulsion described in step 1) can be selected from one or more of pure acrylic emulsion, styrene-acrylic emulsion, silicone-acrylic emulsion, fluorine-acrylic emulsion, vinyl acetate-acrylic emulsion, etc.; Among them, the film-forming auxiliary described in step 1) can be selected from one or more of alcohol ester-12, fatty acid ethyl ester, isooctyl fatty acid ester, and ethyl oleate; Among them, the organic acid described in step 2) is any one or more of gluconic acid, ferrocyanic acid, organophosphonic acid, tannic acid, citric acid, gallic acid, etc.; Among them, the defoamer described in step 3) can be selected from one or more of polyether-modified silicone oil defoamers, silicone defoamers, polyester-modified defoamers, etc.;

[0029] Among them, the metal substrate for surface rust removal treatment can be steel materials with wide applications, or other materials such as iron. Example 1

[0030] The present invention provides an acrylic composite rust converter modified with organic acid and aluminum tripolyphosphate, which includes an acrylic emulsion component A, an organic acid component B, and an aluminum tripolyphosphate component C. The specific steps are as follows: 1) Synthesis of component A acrylic emulsion: Weigh the acrylic emulsion, film-forming auxiliary, and deionized water according to the mass ratio of 10:0.45:8. The order of adding the drugs is as follows: 1.1) Add 8 g of styrene-acrylic emulsion to 10 g of deionized water, stir at a temperature of 25°C and a speed of 500 rmp for 0.5 hour; 1.2) Then add 0.45 g of the film-forming auxiliary alcohol ester-12, stir at a temperature of 25°C and a speed of 500 rmp for 30 minutes; 2) Preparation of organic acid B component: First, mix 5 g of deionized water and 6 g of ethanol, and stir for 20 minutes at a rotation speed of 500 rpm to make them evenly mixed. Subsequently, add 0.4 g of isopropanol and 0.2 g of ethylene glycol to the mixed solution, and stir for 20 minutes at a rotation speed of 500 rpm to make all raw materials evenly mixed. Finally, slowly add 2.5 g of gallic acid and 2 g of gluconic acid solution, and stir for 30 minutes at a rotation speed of 500 rpm to make all raw materials evenly mixed to obtain component B; 3) Preparation of composite rust converter: First, weigh 0.5 g of aluminum tripolyphosphate powder, and slowly add the aluminum tripolyphosphate powder to component B. Stir at a temperature of 25 °C and a rotation speed of 500 rmp for 1 hour to obtain a uniformly mixed solution. Slowly add the above mixed solution to the prepared component A, and add an appropriate amount of silicone defoamer while stirring. Stir at room temperature for 50 minutes to prepare the composite rust converter; 4) Rust treatment method and steps: Place the rusted Q235 steel sheet in a petri dish, add the prepared rust converter to the petri dish to cover the rusted steel sheet. After soaking for 0.5 hours, take it out to complete rust conversion, and wash the residual acrylic emulsion with anhydrous ethanol. After drying, put the sample into an oven for further use.

[0031] Characterize the above rusted steel sheet and the sample after rust treatment: The physical photos of the rusted Q235 steel sheet and the steel sheet after rust treatment are as Figure 1 shown. It can be seen from the physical pictures before and after rust conversion that the surface of the rusted Q235 steel sheet is uneven and rough. Using the prepared composite rust converter to carry out rust conversion on the rusted steel sheet, under the action of the rust converter, a black and dense conversion film is formed on the surface of the rusted steel sheet. Compared with before rust conversion, the matrix surface after conversion is more dense and tidy, and this rust converter has a good rust conversion effect on the rusted steel sheet.

[0032] The optical morphology and surface roughness of the rusted Q235 steel sheet and the steel sheet after rust treatment are as Figure 2 shown. The surface of the steel sheet before rust treatment is uneven, covered with loose floating rust and unevenly distributed, showing a highly rough state; from the height distribution diagram, the height difference on the matrix surface is large and uneven. The surface of the steel sheet after rust treatment is significantly smoother and tidier than that of the steel sheet before rust treatment, and the rust is reacted into a dense chelate protective film; the overall height difference is uniform, and the rust conversion effect is remarkable.

[0033] The scanning electron microscope photos of the rusted Q235 steel sheet, the steel sheet converted by aluminum tripolyphosphate alone, and the steel sheet treated with the composite rust converter are as Figure 3As shown, there are obvious rusty parts on the surface of the steel sheet before rust treatment, and large granular areas can be observed; after rust conversion, the granular and needle-like substances on the surface of the steel sheet basically disappear, the roughness of the steel sheet is greatly reduced, a dense film is formed on the sample surface, and the rust conversion effect is very obvious. After treatment with aluminum tripolyphosphate, many bright white spots can be seen and the surface is uneven; during the collision process, the tripolyphosphate particles will cause anion dissociation, resulting in physical and chemical adsorption phenomena, thus generating a negatively charged surface on the microcrystals. If the surface area is large, the surface will be able to adsorb many microparticles with the same charge, and the charged microcrystals will form large aggregates, which will affect the quality and corrosion resistance of the conversion film. After the modification of aluminum tripolyphosphate with organic acids, under the combined action of the organic acid and aluminum tripolyphosphate, the conversion film is a black dense film, and the white particles are evenly dispersed, which is more uniform than when only aluminum tripolyphosphate is used as the rust conversion agent. It can be confirmed that under the electrostatic repulsion of gallic acid and gluconic acid, the collision of aluminum tripolyphosphate microcrystals can be prevented, agglomeration can be reduced, and the quality of the conversion film can be improved.

[0034] The XRD patterns of the rusty Q235 steel sheet, the steel sheet converted by aluminum tripolyphosphate alone, and the steel sheet treated with the composite rust converter are as Figure 4 shown. The XRD pattern of the rusty steel sheet has high-intensity diffraction peaks, and these peaks correspond to the characteristic peaks of different iron oxides and oxyhydroxides. The crystal corrosion products in rust include Fe2O3, Fe3O4, γ-FeOOH, and α-FeOOH. After treatment with the aluminum tripolyphosphate conversion agent alone, the peak intensities corresponding to Fe2O3, Fe3O4, γ-FeOOH, and α-FeOOH are significantly reduced, and some of the corrosion product peaks disappear, indicating that the rust converter reacts with the rust on the surface of the rusty steel sheet, and the content of active rust is greatly reduced. However, some characteristic peaks of rust can still be seen, indicating that there is still some rust after treatment with only aluminum tripolyphosphate as the rust converter, and the conversion effect is worse than that of the composite rust converter; no new rust characteristic peaks are found in the XRD pattern of the composite rust converter modified with organic acids, and a relatively wide amorphous peak is formed at about 2θ = 20°; this is the amorphous iron chelate obtained by the reaction of the composite rust converter with rust.

[0035] The FTIR spectra of the rusty Q235 steel sheet, the steel sheet converted by aluminum tripolyphosphate alone, and the steel sheet treated with the composite rust converter are as Figure 5 shown. The characteristic absorption peaks of α-FeOOH and γ-FeOOH are in the range of 1100 cm –1 ~500 cm –1 . The rust-containing matrix has a characteristic absorption peak of α-FeOOH at 802 cm –1 , and the characteristic absorption peaks at 878 cm –1 and 1022 cm –1 correspond to γ-FeOOH. 616 cm–1 is the stretching vibration peak of Fe-O. 1634 cm –1 The absorption peak at may be due to the stretching vibration of the single bond -OH bond in the rust. After treatment with the rust converter, new characteristic peaks appear at 2933 cm –1 at, 1733 cm –1 , 756 cm –1 and 698 cm –1 at, which may be attributed to the vibrations of C-H, C=O, C=C, and double bonds in the residual acrylic emulsion respectively. The characteristic absorption peaks of α-FeOOH and γ-FeOOH disappear or weaken. An absorption band of P-O-C appears at 973 cm –1 and a stretching vibration peak of P=O is found at 1449 cm –1 . The spectral image shows that the rust converter combines with iron ions and reduces the intensity of the relevant peaks, indicating that after treating the rusted steel sheet with aluminum tripolyphosphate as the rust converter, the oxygen atoms in aluminum tripolyphosphate form a complex with iron ions, forming a new chelate. Similarly, after treatment with the composite rust converter, the characteristic peaks related to the rust components also weaken or even disappear. A new characteristic P-O peak is also formed at 965 cm –1 , indicating that the rust converter is effective in rust treatment and can react with rust to form a new chelate. Example 2

[0036] The present invention provides an acrylic composite rust converter of organic acid modified aluminum tripolyphosphate, which includes component A of acrylic emulsion, component B of organic acid, and component C of aluminum tripolyphosphate. The specific steps are as follows: 1) Synthesis of component A of acrylic emulsion: Mix acrylic emulsion, film-forming aid, and deionized water and weigh them according to the mass ratio of 10:0.4:10. The order of adding the drugs is as follows: 1.1) Add 10 g of pure acrylic emulsion to 10 g of deionized water, stir at a speed of 500 rmp at a temperature of 25 °C for 0.5 hour; 1.2) Then add 0.4 g of film-forming aid alcohol ester-12, stir at a speed of 500 rmp at a temperature of 25 °C for 30 minutes; 2) Preparation of component B of organic acid: First, mix 5 g of deionized water and 6 g of ethanol, and stir at a speed of 500 rpm for 20 minutes to make them evenly mixed. Subsequently, add 0.4 g of isopropanol and 0.2 g of ethylene glycol to the mixed solution, and stir at a speed of 500 rpm for 20 minutes to make all the raw materials evenly mixed. Finally, slowly add 2.5 g of tannic acid and 2 g of citric acid, and stir at a speed of 500 rpm for 30 minutes to make all the raw materials evenly mixed to obtain component B; 3) Preparation of the composite rust converter: First, weigh 2.5 g of aluminum tripolyphosphate powder, and slowly add the aluminum tripolyphosphate powder to component B. Stir at a temperature of 25 °C and a rotation speed of 500 rmp for 1 hour to obtain a uniformly mixed solution. Slowly add the above mixed solution to the prepared component A, and add an appropriate amount of polyether-modified silicone oil defoamer while stirring. Stir at room temperature for 50 minutes to prepare the composite rust converter; 4) Rust treatment method and steps: Place the rusted Q235 steel sheet in a petri dish, add the prepared rust converter to the petri dish to submerge the rusted steel sheet. After soaking for 0.5 hours, take it out to complete the rust conversion, and wash the remaining acrylic emulsion with absolute ethanol. After drying, put the sample into a drying oven for further use.

[0037] Characterize the above rusted steel sheet and the sample after rust treatment: The physical photos of the rusted Q235 steel sheet and the steel sheet after rust treatment are as Figure 6 shown. It can be seen from the physical pictures before and after rust conversion that the surface of the rusted Q235 steel sheet is uneven and rough. Use the prepared composite rust converter to carry out rust conversion on the rusted steel sheet. Under the action of the rust converter, a black and dense conversion film is formed on the surface of the rusted steel sheet. Compared with before rust conversion, the surface of the substrate after conversion is more dense and clean, and this rust converter has a good rust conversion effect on the rusted steel sheet.

[0038] The Raman spectra of the rusted Q235 steel sheet, the steel sheet converted by aluminum tripolyphosphate alone, and the steel sheet treated with the composite rust converter are as Figure 7 shown. The Raman spectrum of the rusted steel sheet shows obvious characteristic peaks of α-Fe2O3, which appear at 212 cm –1 , 279 cm –1 and 1291 cm –1 . In addition, significant characteristic peaks of α-FeOOH are also observed in the Raman spectrum, which are located at 389 cm –1 and 548 cm –1 . The Raman characteristic peaks of γ-FeOOH correspond to 213 cm –1 , 377 cm –1 and 1302 cm –1 respectively. In addition, 670 cm in the Raman spectrum –1The vibration can be attributed to magnetite (Fe3O4). By comparing the Raman spectra of the steel sheet before and after rust conversion, it can be clearly seen that the Raman peak intensities related to various rust components on the surface of the steel sheet after rust conversion decreased significantly or disappeared, indicating that the rust conversion effect is remarkable. After the rust conversion was completed, the steel sheet was stored in a laboratory fume hood at an ambient temperature of about 25°C and a relative humidity between 75% and 85%. The rust-converted steel sheet was placed in the above environment for 30 days, and then Raman tests were carried out. The Raman peak intensities related to various rust components on the surface of the steel sheet treated with the composite conversion agent did not show obvious enhancement within 30 days, which indicates that the chelate formed by the reaction of the rust conversion agent with rust is very stable; it shows that treating the rusty steel sheet with the composite conversion agent can endow the steel sheet with good protection, and the rust conversion effect is remarkable.

[0039] The XPS spectra of the rusty Q235 steel sheet, the steel sheet with only aluminum tripolyphosphate for rust conversion, and the steel sheet treated with the composite rust conversion agent are as Figure 8 shown. Before rust conversion, elements C, O, and Fe were detected on the surface of the steel sheet. After rust conversion, the binding energies of O and Fe on the surface of the steel sheet decreased significantly, especially the binding energies of O and Fe on the surface of the steel sheet converted by the composite conversion agent decreased most significantly. This is mainly because the conversion film is generated on the surface of the rusty substrate by the action of the rust conversion agent, thereby significantly reducing the contents of Fe and O. The contents of Fe and O on the surface of the steel sheet converted by the composite conversion agent are less than those when only aluminum tripolyphosphate is used as the rust conversion agent, while the content of C is higher, indicating that the composite conversion agent has a stronger ability to convert iron oxides, and the rust conversion ability is improved after modifying aluminum tripolyphosphate with tannic acid and citric acid. Example 3

[0040] The present invention provides an acrylic composite rust conversion agent for organic acid-modified aluminum tripolyphosphate, which includes acrylic emulsion component A, organic acid component B, and aluminum tripolyphosphate component C. The specific steps are as follows: 1) Synthesis of acrylic emulsion component A: Mix acrylic emulsion, film-forming aid, and deionized water and weigh them according to the mass ratio of 10:0.45:9. The order of adding the drugs is as follows: 1.1) Add 9 g of silicon-acrylic emulsion to 10 g of deionized water, stir at a temperature of 25°C and a speed of 500 rmp for 0.5 hour; 1.2) Then add 0.45 g of film-forming aid fatty acid ethyl ester, stir at a temperature of 25°C and a speed of 500 rmp for 30 minutes; 2) Preparation of organic acid B component: First, mix 5 g of deionized water and 6 g of ethanol, and stir at a speed of 500 rpm for 20 minutes to make them evenly mixed. Subsequently, add 0.4 g of isopropanol and 0.2 g of ethylene glycol to the mixed solution, and stir at a speed of 500 rpm for 20 minutes to make all raw materials evenly mixed. Finally, slowly add 2 g of gallic acid and 2 g of organic phosphonic acid, and stir at a speed of 500 rpm for 30 minutes to make all raw materials evenly mixed to obtain the B component; 3) Preparation of composite rust converter: First, weigh 0.8 g of aluminum tripolyphosphate powder, and slowly add the aluminum tripolyphosphate powder to the B component. Stir at a temperature of 25 °C and a speed of 500 rmp for 1 hour to obtain a uniformly mixed solution. Slowly add the above mixed solution to the prepared A component, and add an appropriate amount of polyester modified defoamer while stirring. Stir at room temperature for 50 minutes to prepare the composite rust converter; 4) Rust treatment method and steps: Place the rusted Q235 steel sheet in a petri dish, add the prepared rust converter to the petri dish to cover the rusted steel sheet. After soaking for 1 hour, take it out to complete the rust conversion. Wash the remaining acrylic emulsion with absolute ethanol. After drying, put the sample into a drying oven for further use.

[0041] Characterize the above rusted steel sheet and the sample after rust treatment: The physical pictures of the rusted Q235 steel sheet and the steel sheet after rust treatment are as Figure 9 shown. It can be seen from the physical pictures before and after rust conversion that the surface of the rusted Q235 steel sheet is uneven and rough. Use the prepared composite rust converter to carry out rust conversion on the rusted steel sheet. Under the action of the rust converter, a black and dense conversion film is formed on the surface of the rusted steel sheet. Compared with before rust conversion, the matrix surface after conversion is more dense and clean, and this rust converter has a good rust conversion effect on the rusted steel sheet.

[0042] The adhesion test results of the epoxy coating on the surface of the rusted Q235 steel sheet, the steel sheet after rust conversion with aluminum tripolyphosphate alone, and the steel sheet after treatment with the composite rust converter are as Figure 10 shown. The adhesion of the epoxy coating on the surface of the rusted Q235 steel sheet is the smallest; the adhesion of the epoxy coating on the surface after rust conversion with organic acid modified aluminum tripolyphosphate is significantly higher than that after rust conversion with pure aluminum tripolyphosphate alone; under the electrostatic repulsion of the organic acid, it can prevent the aluminum tripolyphosphate microcrystals from colliding with each other, reduce agglomeration, improve the quality of the rust conversion film, and make the metal matrix surface more dense and clean. Therefore, the coating adhesion also increases significantly. Example 4

[0043] The present invention provides an acrylic composite rust converter modified with organic acid aluminum tripolyphosphate, which includes an acrylic emulsion A component, an organic acid B component, and an aluminum tripolyphosphate C component. The specific steps are as follows: 1) Synthesis of Component A acrylic emulsion: Weigh acrylic emulsion, film-forming aid and deionized water according to the mass ratio of 10:0.45:8. The order of adding the chemicals is as follows: 1.1) Add 8 g of fluoropropyl emulsion to 10 g of deionized water, and stir at a speed of 500 rmp for 0.5 hour at a temperature of 25 °C; 1.2) Then add 0.45 g of film-forming aid fatty acid ethyl ester, and stir at a speed of 500 rmp for 30 minutes at a temperature of 25 °C; 2) Preparation of organic acid Component B: First, mix 5 g of deionized water and 6 g of ethanol, and stir at a speed of 500 rpm for 20 minutes to make them evenly mixed. Subsequently, add 0.4 g of isopropanol and 0.2 g of ethylene glycol to the mixed solution, and stir at a speed of 500 rpm for 20 minutes to make all the raw materials evenly mixed. Finally, slowly add 1 g of gallic acid, 1.5 g of organic phosphonic acid and 2 g of ferrocyanic acid, and stir at a speed of 500 rpm for 30 minutes to make all the raw materials evenly mixed to obtain Component B; 3) Preparation of composite rust converter: First, weigh 1.2 g of aluminum tripolyphosphate powder, and slowly add the aluminum tripolyphosphate powder to Component B. Stir at a speed of 500 rmp for 1 hour at a temperature of 25 °C to obtain a uniformly mixed solution. Slowly add the above mixed solution to the prepared Component A, and add an appropriate amount of polyester-modified defoaming agent while stirring. Stir at room temperature for 40 minutes to prepare the composite rust converter; 4) Rust treatment method and steps: Put the rusted Q235 steel sheet into a petri dish, add the prepared rust converter to the petri dish to cover the rusted steel sheet, take it out after soaking for 0.5 hour to complete rust conversion, and wash the remaining acrylic emulsion with absolute ethanol. After drying, put the sample into a drying oven for further use.

[0044] Characterize the above rusted steel sheet and the sample after rust treatment: The comparison physical photos of the rusted Q235 steel sheet and the steel sheet treated with the composite rust converter after 96-hour neutral salt spray test are as Figure 11 shown. After 96 hours of salt spray test, the rusted Q235 metal steel sheet shows large-area severe rust, while the rusted steel sheet converted by the composite converter does not show severe rust phenomenon, indicating the anti-corrosion protection effect of the rust conversion film.

[0045] The DSC-TG curve of the conversion film formed by the reaction of the composite rust converter and rust during heating is as Figure 12As shown, from room temperature to about 400 °C, the mass of the sample decreases sharply, which may be due to the evaporation of small molecules such as ethanol and isopropanol in the rust converter; after 400 °C, the rate of mass reduction of the sample gradually slows down, indicating that the volatile substances in the conversion film have completely evaporated. The DSC curve shows that there are no obvious endothermic and exothermic peaks when the conversion film is heated to 1000 °C, indicating that the conversion film is difficult to decompose and has good heat resistance. Example Five

[0046] The present invention provides an acrylic composite rust converter modified with organic acid for aluminum tripolyphosphate, which includes acrylic emulsion component A, organic acid component B, and aluminum tripolyphosphate component C. The specific steps are as follows: 1) Synthesis of acrylic emulsion component A: Weigh acrylic emulsion, film-forming aid, and deionized water according to the mass ratio of 10:0.4:7. The order of adding the drugs is as follows: 1.1) Add 7 g of styrene-acrylic emulsion to 10 g of deionized water, and stir at a speed of 500 rmp for 0.5 hour at a temperature of 25 °C; 1.2) Then add 0.4 g of film-forming aid fatty acid ethyl ester, and stir at a speed of 500 rmp for 30 minutes at a temperature of 25 °C; 2) Preparation of organic acid component B: First, mix 5 g of deionized water and 6 g of ethanol, and stir at a speed of 500 rpm for 20 minutes to make them evenly mixed. Subsequently, add 0.4 g of isopropanol and 0.2 g of ethylene glycol to the mixed solution, and stir at a speed of 500 rpm for 20 minutes to make all the raw materials evenly mixed. Finally, slowly add 1.5 g of tannic acid, 1 g of citric acid, and 2.5 g of ferrocyanic acid, and stir at a speed of 500 rpm for 30 minutes to make all the raw materials evenly mixed to obtain component B; 3) Preparation of the composite rust converter: First, weigh 2 g of aluminum tripolyphosphate powder, and slowly add the aluminum tripolyphosphate powder to component B, and stir at a speed of 500 rmp for 1 hour at a temperature of 25 °C to obtain a uniformly mixed solution. Slowly add the above mixed solution to the prepared component A, and add an appropriate amount of polyester-modified defoaming agent while stirring, and stir at room temperature for 50 minutes to make the composite rust converter; 4) Rust treatment method and steps: Place the rusted Q235 steel sheet in a petri dish, add the prepared rust converter to the petri dish to cover the rusted steel sheet, take it out after soaking for 1.5 hours to complete rust conversion, and wash the remaining acrylic emulsion with anhydrous ethanol. After drying, put the sample into an oven for further use.

[0047] Characterize the above rusted steel sheet and the sample after rust treatment: The open circuit potential-time curves of the rusted Q235 steel sheet, the rust converter steel sheet with only aluminum tripolyphosphate, and the steel sheet treated with the composite rust converter are asFigure 13 As shown, the stable open-circuit voltage value of the rusty steel sheet is the lowest, approximately -0.67 V. In contrast, the stable open-circuit voltage value of the steel sheet treated with aluminum tripolyphosphate conversion is -0.47 V, lower than that of the steel sheet treated with the composite conversion agent (-0.13 V), but significantly higher than that of the rusty steel sheet (-0.67 V). Compared with the rusty steel sheet, the stability of the whole system is enhanced and the corrosion rate of Q235 steel is reduced after the steel sheet is treated with the rust conversion agent. Better rust conversion effect can be achieved by adding tannic acid, citric acid and ferrocyanic acid to modify aluminum tripolyphosphate.

[0048] The EIS data of the rusty Q235 steel sheet, the steel sheet with aluminum tripolyphosphate rust conversion alone and the steel sheet treated with the composite rust conversion agent are as Figure 14 shown. For the rusty steel sheet, the loose and porous rust cannot isolate the metal matrix from oxygen and electrolyte, making the steel sheet prone to react with oxygen and electrolyte, and the metal matrix continues to rust with a small impedance value. After treatment with aluminum tripolyphosphate and the composite rust conversion agent respectively, a relatively dense film will be formed, and the impedance arc radius increases, isolating the metal matrix from the corrosive medium to a certain extent. The rusty matrix treated only with aluminum tripolyphosphate has a small impedance semicircle diameter and poor corrosion resistance of the conversion film. As an anti-rust filler, aluminum tripolyphosphate has poor dispersibility and is easy to agglomerate, so it will affect the quality of the paint film and reduce the corrosion resistance. The impedance of the rust conversion film formed by modifying the rusty matrix with organic acid-modified aluminum tripolyphosphate is dozens of times higher than that of the conversion film treated only with aluminum tripolyphosphate. This result shows that in addition to chelating with rust, the addition of organic acid can also produce a synergistic effect with aluminum tripolyphosphate.

[0049] Although the preferred embodiments of the present application have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and modifications falling within the scope of the present application.

[0050] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application is also intended to include these modifications and variations.

[0051] Except for the technical features described in the specification, the rest are the known technologies of those skilled in the art.

Claims

1. An acrylic composite rust converter of organic acid modified aluminum tripolyphosphate, comprising acrylic emulsion component A, organic acid component B, and aluminum tripolyphosphate component C: Among them, the acrylic emulsion component A solution is prepared by mixing acrylic emulsion, film-forming aid, and deionized water according to the mass ratio of 5–15:0.3–0.5:6–12; the organic acid component B is prepared by mixing ethanol, deionized water, isopropanol, ethylene glycol, and organic acid according to the mass ratio of 5–10:5–10:0.1–1:0.1–0.5:3–6. Component C is a separate aluminum tripolyphosphate powder. Among them, the acrylic emulsion component A, the organic acid component B, and the aluminum tripolyphosphate component C are added according to the mass ratio of 10–30:8–25:0.2–5; the acrylic emulsion component A, the organic acid component B, and the aluminum tripolyphosphate component C are mixed and stirred evenly, and a few drops of defoamer are added while stirring, and stirred at room temperature for 20–50 minutes to make the composite rust converter. Put the rusted steel sheet into a petri dish, add the prepared rust converter into the petri dish to cover the rusted steel sheet, take it out after soaking for 0.5–3 hours, and wash the remaining acrylic emulsion with absolute ethanol. After drying, put the sample into an oven for further use; Among them, the acrylic emulsion can be selected from one or more of pure acrylic emulsion, styrene-acrylic emulsion, silicone-acrylic emulsion, fluorine-acrylic emulsion, vinyl acetate-acrylic emulsion, etc.; Among them, the film-forming aid can be selected from one or more of alcohol ester-12, fatty acid ethyl ester, isooctyl fatty acid ester, ethyl oleate; Among them, the organic acid is any one or more of gluconic acid, ferrocyanic acid, organic phosphonic acid, tannic acid, citric acid, gallic acid, etc.; Among them, the defoamer can be selected from one or more of polyether modified silicone oil defoamer, silicone defoamer, polyester modified defoamer, etc.

2. The acrylic composite rust converter of organic acid modified aluminum tripolyphosphate according to claim 1, and the specific implementation steps are as follows: 1) Synthesis of acrylic emulsion component A: Weigh acrylic emulsion, film-forming aid, and deionized water according to the mass ratio of 5–15:0.3–0.5:6–12, and the order of adding drugs is: 1.1) First mix the acrylic emulsion and deionized water, and stir at a speed of 300–1000 rmp for 0.5–1 hour within the temperature range of 20–35°C; 1.2) Then add the film-forming aid, and stir at a speed of 200–500 rmp for 0.5–1 hour within the temperature range of 20–35°C; 2) Preparation of organic acid component B: Weigh ethanol, deionized water, isopropanol, ethylene glycol, and organic acid according to the mass ratio of 5–10:5–10:0.1–1:0.1–0.5:3–6, and stir at a speed of 300–700 rpm for 10–50 minutes to mix ethanol, deionized water, isopropanol, and ethylene glycol evenly. Subsequently, add different kinds of organic acids to the mixed solution, and stir at a speed of 300–700 rpm for 10–50 minutes to mix all raw materials evenly; 3) Preparation of the composite rust converter: Weigh the organic acid component B and the aluminum tripolyphosphate component C according to the mass ratio of 8–25:0.2–5. Slowly add the aluminum tripolyphosphate powder to component B and stir at a speed of 300–1000 rmp for 0.5–2 hours within the temperature range of 20–35 °C. Mix and stir evenly the acrylic emulsion component A, the organic acid component B, and the aluminum tripolyphosphate component C according to the mass ratio of 10–30:8–25:0.2–5. Add a few drops of defoamer while stirring and stir at room temperature for 20–50 minutes to prepare the composite rust converter; 4) Rust treatment method and steps: Place the rusted Q235 steel sheet in a petri dish. Add the prepared rust converter to the petri dish to submerge the rusted steel sheet. Take it out after soaking for 0.5–3 hours. Wash the remaining acrylic emulsion with absolute ethanol. After drying, put the sample into an oven for further use.

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