A nano-toughening agent containing colloidal zirconia and a preparation method and application thereof

Abstract

The present application relates to the technical field of metal surface treatment, and particularly relates to a nano-toughening agent containing colloidal zirconium oxide and a preparation method and application thereof, the nano-toughening agent containing colloidal zirconium oxide comprises the following raw materials in parts by weight: hexafluorozirconic acid 0.55-0.65 parts, colloidal zirconium oxide 6-9 parts, modified organic silicon resin 5-7 parts, and pure water 90-110 parts. The nano-toughening agent containing colloidal zirconium oxide prepared by the present application has excellent rust-proof effect and corrosion resistance, can improve the yellowing resistance of the toughening bath, and through the dual effects of physical isolation formed by nano-zirconium oxide and organic silicon barrier and chemical passivation formed by fluorozirconic acid complex, the service life of the bath is significantly prolonged, and the present application is suitable for toughening treatment with strict appearance requirements.

Description

Technical Field

[0001] This invention relates to the field of metal surface treatment technology, specifically to a nano-ceramic agent containing colloidal zirconium oxide, its preparation method, and its application. Background Technology

[0002] In recent years, ceramic coating technology has rapidly developed as one of the most promising alternatives to traditional high-pollution phosphating and chromate passivation, and has begun to be widely used in metal surface treatment. Ceramic coating agents are surface treatment agents for phosphorus-free metals such as zirconium-based, zirconium-titanium-based, silane-based, and zirconium-silane-based metals. They can partially replace phosphating solutions, fluorozirconic acid, silane coupling agents, etc., and are used to improve the hardness, strength, wear resistance, corrosion resistance, and other properties of materials.

[0003] Patent CN117107227A discloses a nano-ceramic agent and its preparation method, comprising the following steps, by weight: (1) adding 5-15 parts of zirconium compound and 2-5 parts of inorganic acid to 80-90 parts of water, stirring at room temperature for 1-3 hours until completely dissolved; (2) adding 0.5-2 parts of complexing agent, stirring at room temperature for 0.5-1 hour; (3) continuing to add 1-3 parts of nano-inorganic material and 0.5-1.5 parts of silane coupling agent, stirring at room temperature for 0.5-1 hour; (4) finally adding an alkali adjuster to adjust the pH value to weakly acidic, thereby obtaining the nano-ceramic agent. The nano-ceramic agent prepared by this invention extends the corrosion resistance time of metals. Patent CN103938198A discloses a phosphorus-free nano-ceramic agent, its preparation method, and its application. The phosphorus-free nano-ceramic agent, by mass percentage, is made from the following raw materials: 3-6% fluorozirconic acid, 3-7% zirconium oxychloride, 0.1-0.6% ammonium fluorozirconate, 0.8-2% tartaric acid, 0.5-1% sodium nitrate, with the balance being water. This invention's phosphorus-free nano-ceramic agent can be operated at room temperature, has a short processing time, a simple process, produces almost no sediment, does not clog nozzles, reduces waste disposal costs, and can significantly improve the adhesion between coatings and metals, extending the corrosion resistance time of metals. However, using zirconium compounds alone as the main film-forming agent often results in a loose, porous network structure, which is difficult to provide ideal corrosion resistance and can easily cause the ceramic coating bath to yellow, affecting the stability of the bath process.

[0004] Therefore, there is an urgent need in the market for a nano-ceramic agent with good rust prevention and excellent corrosion resistance. Summary of the Invention

[0005] In view of the problems existing in the prior art, the purpose of this invention is to obtain a nano-ceramic agent containing colloidal zirconium oxide with excellent rust prevention and corrosion resistance.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] The first aspect of the present invention provides a nano-ceramic agent containing colloidal zirconium oxide, which, by weight, comprises the following raw materials: 0.55-0.65 parts of hexafluorozirconic acid, 6-9 parts of colloidal zirconium oxide, 5-7 parts of modified organosilicon resin, and 90-110 parts of pure water.

[0008] The nano-ceramic agent prepared by adding hexafluorozirconic acid, colloidal zirconium oxide, and modified organosilicon resin to pure water has excellent rust prevention and corrosion resistance. It can improve the yellowing resistance of the ceramic coating bath. Through the dual effects of physical isolation formed by nano-zirconium oxide and organosilicon barrier and chemical passivation formed by complexation with hexafluorozirconic acid, the service life of the bath is significantly extended. It is suitable for ceramic coating treatment with strict appearance requirements.

[0009] Colloidal zirconium oxide can be dispersed in nanoparticle form to form a stable sol system, reducing free metal ions such as Fe. 3+ Cu 2+ The adsorption of these ions can lead to yellowing of the bath solution through oxidation or complexation reactions. Zirconia, rich in hydroxyl groups, preferentially binds to these impurity ions, preventing them from participating in the color development reaction. Furthermore, the inert surface of zirconia blocks the diffusion of oxygen into the bath solution, reducing the oxidative degradation of organic components such as residual grease and additives, thus preventing yellowing caused by the oxidative degradation of organic impurities.

[0010] Zr generated after hydrolysis of hexafluorozirconic acid 4+ and F - Fe can react with free Fe in the bath solution 3+ When metal ions form stable complexes, their catalytic oxidation is inhibited. Hexafluorozirconic acid can also maintain a weakly acidic environment in the system, preventing the hydrolysis of organosilicon resins or impurities under alkaline conditions.

[0011] Modified organosilicon resin forms a hydrophobic layer on the surface of the ceramic film, blocking the penetration of water and oxygen, reducing yellowing caused by oxidation reaction, and the Si-O bond of organosilicon has high chemical stability and is not easily broken by oxidants or ultraviolet light in the bath.

[0012] In some embodiments, the purity of the hexafluorozirconic acid is 40-45 wt%.

[0013] In some embodiments, the colloidal zirconium oxide contains 20-30 wt% zirconium oxide and has an average particle size of 8-12 nm.

[0014] In some embodiments, the pH of the colloidal zirconium oxide is 1-2.

[0015] In some embodiments, the method for preparing the modified organosilicon resin includes the following steps:

[0016] A1. Add hydroxyl-terminated polydimethylsiloxane to a reaction vessel, add silane coupling agent SI-186 and catalyst under nitrogen protection, heat to 83-87℃ and react for 2-4 hours, add pentafluorophenylpropyltrimethoxysilane and react for 1-2 hours to obtain modified organosilicon.

[0017] A2. Add the modified organosilicon obtained in step A1 to the aqueous phase containing emulsifier, and shear at high speed at 35-45℃ and 7000-9000rpm for 10-30min. Then, use a high-pressure homogenizer to cycle the mixture 3-5 times at 40-50MPa pressure, adjust the pH to 5.5-6, and filter to obtain the modified organosilicon resin.

[0018] This application introduces epoxy groups onto silicone resin by reacting hydroxyl-terminated polydimethylsiloxane with the silane coupling agent SI-186, forming an organic-inorganic hybrid network between silicone resin segments. This further seals the active metal sites and inhibits yellowing of the bath solution. Furthermore, by introducing a small amount of fluorinated aryl silane into the modified silicone resin, this application further enhances the rust-preventive and corrosion-resistant properties of the nano-ceramic agent. This is because the modified silicone resin becomes more hydrophobic after introducing fluorine-containing groups, thus reducing salt spray water film penetration. Compared to the conventional method of introducing -CF3, the fluorine on the fluorinated aryl group is more dispersed and less likely to affect the activity of the epoxy groups. Moreover, the introduction of fluorine and benzene ring structures can improve the heat resistance of the modified silicone resin.

[0019] In some embodiments, the mass ratio of the hydroxyl-terminated polydimethylsiloxane to the silane coupling agent SI-186 is 1:(0.1-0.3).

[0020] This application allows for better rust prevention performance of nano-ceramic agents containing colloidal zirconium oxide by limiting the ratio of hydroxyl-terminated polydimethylsiloxane and silane coupling agent SI-186. This may be because the modified organosilicon has a suitable crosslinking density at this ratio, which makes it less prone to microcracks after the nano-ceramic agent is cured, thus giving the nano-ceramic agent better rust prevention performance.

[0021] In some embodiments, the mass ratio of the hydroxyl-terminated polydimethylsiloxane to pentafluorophenylpropyltrimethoxysilane is 1:(0.05-0.15).

[0022] This application allows for a better rust-preventing effect of nano-ceramic agents containing colloidal zirconium oxide by limiting the ratio of hydroxyl-terminated polydimethylsiloxane and pentafluorophenylpropyltrimethoxysilane. This may be because the ratio can reduce the influence of fluorine-containing groups on the polymerization reaction and the dispersibility of modified organosilicon resin, thereby improving the stability of the nano-ceramic agents.

[0023] In some embodiments, the mass ratio of the modified organosilicon and the emulsifier in step A2 is 1:(0.1-0.14).

[0024] This application enables nano-ceramic agents containing colloidal zirconium oxide to have better rust-preventive effects by limiting the ratio of modified organosilicon and emulsifier. This may be because the ratio can improve the stability of the nano-ceramic agent while reducing foam formation, thus preventing the foam from affecting the rust-preventive performance of the nano-ceramic agent.

[0025] The second aspect of this invention provides a method for preparing a nano-ceramic agent containing colloidal zirconium oxide, comprising the following steps: adding hexafluorozirconic acid to pure water, stirring at 20-25°C for 20-30 min, adding colloidal zirconium oxide, heating to 40-50°C and reacting for 30-40 min, adding modified organosilicon resin, heating to 60-70°C and reacting for 60-80 min, cooling to room temperature, and filling to obtain the product.

[0026] The third aspect of this invention provides an application of the nano-ceramic agent containing colloidal zirconium oxide obtained by the above preparation method in metal surface treatment.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The nano-ceramic agent prepared by adding hexafluorozirconic acid, colloidal zirconium oxide and modified organosilicon resin to pure water has excellent anti-rust effect and corrosion resistance. It can improve the yellowing resistance of the ceramic coating bath. Through the dual effect of physical isolation formed by nano-zirconium oxide and organosilicon barrier and chemical passivation formed by complexation of fluorozirconic acid, the service life of the bath is significantly extended. It is suitable for ceramic treatment with strict appearance requirements.

[0029] (2) The present invention introduces epoxy groups on modified organosilicon resin by reacting hydroxyl-terminated polydimethylsiloxane with silane coupling agent SI-186, and forms an organic-inorganic hybrid network between organosilicon resin segments, which can further block metal active sites and inhibit yellowing of the bath solution.

[0030] (3) By introducing a small amount of fluoroarylsilane into the modified organosilicon resin, the present invention can further improve the rust prevention effect and corrosion resistance of the nano-ceramic agent. Detailed Implementation

[0031] The present invention will be described below with reference to specific embodiments. It should be noted that the following embodiments are examples of the present invention and are used only to illustrate the invention, not to limit it. Other combinations and various modifications within the scope of the present invention can be made without departing from its spirit or scope.

[0032] In the following examples and comparative examples, except for the modified silicone resin, all other compounds and related reagents used were commercially available. Specifically, the viscosity of the hydroxyl-terminated polydimethylsiloxane was 1500 mPa·s; the emulsifier, HM293D, was purchased from Shanghai Jusheng Chemical Technology Co., Ltd.; the colloidal zirconium oxide, TM-48, was a product of Shanghai Wenjing Chemical Technology Co., Ltd., containing 25 wt% zirconium oxide, with an average particle size of 10 nm and a pH of 1.5; and the purity of hexafluorozirconic acid was 45%.

[0033] Preparation Example 1

[0034] The preparation method of modified organosilicon resin-1 includes the following steps:

[0035] A1. Add 10g of hydroxyl-terminated polydimethylsiloxane to a reaction vessel. Under nitrogen protection, add 2g of silane coupling agent SI-186 and 0.05g of dibutyltin dilaurate. Heat to 85℃ and react for 3 hours. Add 1g of pentafluorophenylpropyltrimethoxysilane and react for 1.5h to obtain modified organosilicon.

[0036] A2. Add 10g of the modified organosilicon obtained in step A1 to 15g of aqueous phase containing 1.2g of HM293D emulsifier, shear at 40℃ and 8000rpm for 20min, then cycle through a high-pressure homogenizer at 45MPa pressure 4 times, adjust the pH to 5.8, filter, and obtain modified organosilicon resin-1.

[0037] Preparation Example 2

[0038] The preparation method of modified organosilicon resin-2 is the same as that of preparation example 1, except that the amount of silane coupling agent SI-186 added is 4g.

[0039] Preparation Example 3

[0040] The preparation method of modified organosilicon resin-3 is the same as that of preparation example 1, except that the amount of pentafluorophenylpropyltrimethoxysilane added is 2.5g.

[0041] Preparation Example 4

[0042] The preparation method of hyperbranched silicone resin-4 is the same as that of preparation example 1, except that the amount of HM293D emulsifier added in step A2 is 2g.

[0043] Preparation Example 5

[0044] The preparation method of modified organosilicon resin-5 includes the following steps:

[0045] A1. Add 10g of hydroxyl-terminated polydimethylsiloxane to a reaction vessel. Under nitrogen protection, add 2g of silane coupling agent SI-186 and 0.05g of dibutyltin dilaurate. Heat to 85℃ and react for 3 hours to obtain modified organosilicon.

[0046] A2. Add 10g of the modified organosilicon obtained in step A1 to 15g of aqueous phase containing 1.2g of HM293D emulsifier, shear at 40℃ and 8000rpm for 20min, then cycle through a high-pressure homogenizer at 45MPa pressure 4 times, adjust the pH to 5.8, filter, and obtain modified organosilicon resin-5.

[0047] Example 1

[0048] A nano-ceramic agent containing colloidal zirconium oxide, comprising the following raw materials by weight: 0.6 parts of 45wt% hexafluorozirconic acid, 7 parts of colloidal zirconium oxide, 6 parts of modified organosilicon resin-1, and 100 parts of pure water.

[0049] The preparation method of the nano-ceramic agent containing colloidal zirconium oxide in this embodiment includes the following steps: adding hexafluorozirconic acid to pure water, stirring at 23°C for 25 min, adding colloidal zirconium oxide, heating to 45°C and reacting for 35 min, adding modified organosilicon resin-1, heating to 65°C and reacting for 70 min, cooling to room temperature, and filling to obtain the product.

[0050] Example 2

[0051] A nano-ceramic agent containing colloidal zirconium oxide, comprising the following raw materials by weight: 0.55 parts of 40wt% hexafluorozirconic acid, 6 parts of colloidal zirconium oxide, 5 parts of modified organosilicon resin-1, and 90 parts of pure water.

[0052] The preparation method of the nano-ceramic agent containing colloidal zirconium oxide in this embodiment includes the following steps: adding hexafluorozirconic acid to pure water, stirring at 20°C for 30 min, adding colloidal zirconium oxide, heating to 40°C and reacting for 40 min, adding modified organosilicon resin-1, heating to 60°C and reacting for 80 min, cooling to room temperature, and filling to obtain the product.

[0053] Example 3

[0054] A nano-ceramic agent containing colloidal zirconium oxide, comprising the following raw materials by weight: 0.65 parts of 50wt% hexafluorozirconic acid, 9 parts of colloidal zirconium oxide, 7 parts of modified organosilicon resin-1, and 110 parts of pure water.

[0055] The preparation method of the nano-ceramic agent containing colloidal zirconium oxide in this embodiment includes the following steps: adding hexafluorozirconic acid to pure water, stirring at 25°C for 20 min, adding colloidal zirconium oxide, heating to 50°C and reacting for 30 min, adding modified organosilicon resin-1, heating to 70°C and reacting for 60 min, cooling to room temperature, and filling to obtain the product.

[0056] Example 4

[0057] A nano-ceramic agent containing colloidal zirconium oxide and its preparation method are described. The specific implementation method is the same as in Example 1, except that modified organosilicon resin-1 is replaced with modified organosilicon resin-2 in equal amounts.

[0058] Example 5

[0059] A nano-ceramic agent containing colloidal zirconium oxide and its preparation method are described. The specific implementation method is the same as in Example 1, except that modified organosilicon resin-1 is replaced with modified organosilicon resin-3 in equal amounts.

[0060] Example 6

[0061] A nano-ceramic agent containing colloidal zirconium oxide and its preparation method are described. The specific implementation method is the same as in Example 1, except that modified organosilicon resin-1 is replaced with modified organosilicon resin-4 in equal amounts.

[0062] Example 7

[0063] A nano-ceramic agent containing colloidal zirconium oxide and its preparation method are described. The specific implementation method is the same as in Example 1, except that modified organosilicon resin-1 is replaced with modified organosilicon resin-5 in equal amounts.

[0064] Comparative Example 1

[0065] A nano-ceramic agent containing colloidal zirconium oxide and its preparation method are described. The specific implementation method is the same as in Example 1, except that the modified organosilicon resin-1 is replaced with an equal amount of organosilicon resin.

[0066] Performance testing

[0067] The performance of the nano-ceramic agents containing colloidal zirconium oxide obtained in the above embodiments and comparative examples was tested:

[0068] 1. Sample preparation

[0069] The 2024 aluminum alloy plate was polished on 1500-grit alumina polishing paper for 5 minutes, and then ultrasonically cleaned with purified water for 20 minutes. Then it was degreased in a 10wt% degreasing agent-water solution for 10 minutes, rinsed twice with purified water for 2 minutes each time, and then immersed in a nano-ceramic agent at room temperature for 3 minutes. It was rinsed twice with purified water for 2 minutes each time, and finally dried at 110℃ for 10 minutes to obtain the aluminum alloy plate test samples corresponding to Examples 1-7 and Comparative Example 1.

[0070] 2. Neutral Salt Spray Resistance Test

[0071] Prepare 24 test samples corresponding to Examples 1-7 and Comparative Example 1, with 3 test samples in each group.

[0072] The test sample was placed in an environment of 25℃ and 30% humidity for 5 days before the test was started. The test method was based on the national standard GB / T1771-2007 "Determination of resistance to neutral salt spray of paints and varnishes". The average value of the test data was taken and the test results are shown in Table 1.

[0073] Example 1 7. The aluminum alloy plates corresponding to Comparative Example 1 were placed in a salt spray chamber, with the coating of the steel sample facing upwards at a 20° angle to the vertical. The salt spray chamber temperature was set to 35°C and the salt spray pressure to 1 kg / cm². 2 The gas source is 5 kg / cm³. 2 A 5wt% sodium chloride aqueous solution, atomized, was periodically and continuously sprayed onto the coated sample substrate. Changes in the substrate were observed during spraying, and the time at which corrosion began to appear was recorded. In the neutral salt spray resistance test, the longer the time before corrosion appeared, the better the coating's corrosion resistance.

[0074] Table 1

[0075]

[0076] As shown in Table 1, the nano-ceramic agents containing colloidal zirconium oxide used in Examples 1-3 exhibit excellent rust prevention and corrosion resistance. A comparison between Example 4 and Example 1 shows that changing the ratio of hydroxyl-terminated polydimethylsiloxane to silane coupling agent SI-186 increases the crosslinking density of the modified organosilicon, leading to a decrease in the corrosion resistance of the nano-ceramic agent. A comparison between Example 5 and Example 1 shows that changing the ratio of hydroxyl-terminated polydimethylsiloxane to pentafluorophenylpropyltrimethoxysilane affects the polymerization of fluorinated groups. The reaction and dispersibility of the modified organosilicon resin lead to a decrease in the corrosion resistance of the nano-ceramic agent. A comparison between Example 6 and Example 1 shows that changing the ratio of modified organosilicon and emulsifier increases foaming and reduces the corrosion resistance of the nano-ceramic agent. A comparison between Example 7 and Example 1 shows that without using pentafluorophenylpropyltrimethoxysilane to modify the organosilicon resin, the corrosion resistance of the nano-ceramic agent is poor. A comparison between Comparative Example 1 and Example 1 shows that directly using organosilicon resin results in poor corrosion resistance of the nano-ceramic agent.

[0077] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A nano-ceramic agent containing colloidal zirconium oxide, characterized in that, By weight, it is composed of the following raw materials: 0.55-0.65 parts hexafluorozirconic acid, 6-9 parts colloidal zirconium oxide, 5-7 parts modified organosilicon resin, and 90-110 parts pure water. The preparation method of the modified organosilicon resin includes the following steps: A1. Add hydroxyl-terminated polydimethylsiloxane to a reaction vessel, add silane coupling agent SI-186 and catalyst under nitrogen protection, heat to 83-87℃ and react for 2-4 hours, add pentafluorophenylpropyltrimethoxysilane and react for 1-2 hours to obtain modified organosilicon. A2. Add the modified organosilicon obtained in step A1 to the aqueous phase containing emulsifier, and shear at high speed at 35-45℃ and 7000-9000rpm for 10-30min. Then, use a high-pressure homogenizer to cycle the mixture 3-5 times at 40-50MPa pressure, adjust the pH to 5.5-6, and filter to obtain the modified organosilicon resin.

2. The nano-ceramic agent containing colloidal zirconium oxide according to claim 1, characterized in that, The purity of the hexafluorozirconic acid is 40-45 wt%.

3. The nano-ceramic agent containing colloidal zirconium oxide according to claim 1, characterized in that, The colloidal zirconium oxide contains 20-30 wt% zirconium oxide and has an average particle size of 8-12 nm.

4. The nano-ceramic agent containing colloidal zirconium oxide according to claim 1, characterized in that, The pH of the colloidal zirconium oxide is 1-2.

5. The nano-ceramic agent containing colloidal zirconium oxide according to claim 1, characterized in that, The mass ratio of the hydroxyl-terminated polydimethylsiloxane to the silane coupling agent SI-186 is 1:(0.1-0.3).

6. The nano-ceramic agent containing colloidal zirconium oxide according to claim 1, characterized in that, The mass ratio of the hydroxyl-terminated polydimethylsiloxane to pentafluorophenylpropyltrimethoxysilane is 1:(0.05-0.15).

7. The nano-ceramic agent containing colloidal zirconium oxide according to claim 1, characterized in that, The mass ratio of the modified organosilicon and the emulsifier in step A2 is 1:(0.1-0.14).

8. A method for preparing a nano-ceramic agent containing colloidal zirconium oxide as described in any one of claims 1-7, characterized in that, The process includes the following steps: adding hexafluorozirconic acid to pure water, stirring at 20-25℃ for 20-30 minutes, adding colloidal zirconium oxide, heating to 40-50℃ and reacting for 30-40 minutes, adding modified organosilicon resin, heating to 60-70℃ and reacting for 60-80 minutes, cooling to room temperature, and filling to obtain the final product.

9. The application of a nano-ceramic agent containing colloidal zirconium oxide as described in any one of claims 1-7 or a nano-ceramic agent containing colloidal zirconium oxide obtained by the preparation method described in claim 8 in metal surface treatment.

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