A triplex pretreatment composition and a method of making the same
By adding nano-inorganic oxides to the three-in-one pretreatment solution and treating it with a silane coupling agent to form a dense passivation film, the problems of low efficiency and insufficient performance in the existing technology are solved, achieving efficient degreasing, rust removal and passivation effects, and improving the corrosion resistance and coating adhesion of steel parts.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- XIAMEN SIFUZEREI TECH CO LTD
- Filing Date
- 2023-04-27
- Publication Date
- 2026-06-26
AI Technical Summary
Existing three-in-one pretreatment solutions suffer from low efficiency and high cost in the degreasing, derusting and passivation processes, and the passivation film affects the storage time and surface coating performance of steel parts.
A three-in-one pretreatment composition is used, comprising phosphoric acid, organic acid, accelerator, film-forming aid, pH stabilizer, corrosion inhibitor, defoamer, and nano-inorganic oxide. By adding nano-inorganic oxide and treating it with a silane coupling agent, a dense passivation film is formed, which improves passivation performance and coating adhesion.
It improves processing efficiency, and the resulting passivation film has good anti-corrosion properties and adhesion, enhances the bonding force between steel parts and organic coatings, and improves the protective effect of surface coating.
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Abstract
Description
Technical Field
[0001] This application relates to the field of metal surface treatment technology, specifically to a three-in-one pretreatment composition and its preparation method. Background Technology
[0002] Steel parts are prone to oxidation and rust formation during storage. Steel parts typically require surface coating, which necessitates degreasing, rust removal, and passivation before coating. Conventional methods involve using different agents for each of these processes, resulting in a time-consuming, labor-intensive, and costly process. Current technology has developed a three-in-one pretreatment solution that can complete degreasing, rust removal, and passivation in a single step, significantly improving work efficiency. The passivation film formed during passivation not only affects the storage time of steel parts but also influences the adhesion of surface coatings, such as paint, ultimately affecting the performance of the coating, including adhesion and corrosion resistance. Summary of the Invention
[0003] To further improve the performance of the three-in-one pretreatment solution, this application provides a three-in-one pretreatment composition and its preparation method.
[0004] The technical solution adopted in this application is as follows:
[0005] A three-in-one pretreatment composition, by weight, comprises the following raw material components: 20-40% phosphoric acid, 1-3% organic acid, 1-5% accelerator, 0.1-0.3% film-forming aid, 0.5-1.5% surfactant, 0.5-1% pH stabilizer, 0.5-1.5% corrosion inhibitor, 0.3-1% defoamer, 1-5% nano-inorganic oxide, with the balance being water.
[0006] Preferably, the organic acid is selected from one or a combination of malic acid, tartaric acid and citric acid.
[0007] Preferably, the accelerator is selected from one or a combination of two of sodium molybdate and sodium fluoride.
[0008] Preferably, the film-forming aid is selected from sodium nitrite.
[0009] Preferably, the pH stabilizer is selected from trisodium phosphate.
[0010] Preferably, the corrosion inhibitor is selected from thiourea and its derivatives.
[0011] Preferably, the nano-inorganic oxide is treated with a silane coupling agent, wherein the silane coupling agent contains one or more of the following in its molecular structure: thiol group, thioether bond, thiourea and polysulfide bond.
[0012] Preferably, the silane coupling agent is selected from one or a combination of mercapto-containing silane coupling agents and acylthiourea-containing silane coupling agents.
[0013] Preferably, the average particle size of the nano-inorganic oxide is 10-100 nm.
[0014] A method for preparing a three-in-one pretreatment composition according to any of the above embodiments includes: adding the water, the phosphoric acid, the organic acid and the surfactant to a container, mixing them evenly, then adding the nano-inorganic oxide and dispersing it evenly, followed by adding the promoter, the film-forming aid, the pH stabilizer, the corrosion inhibitor and the defoamer, mixing them evenly, and thus obtaining the final product.
[0015] In summary, this application has the following beneficial effects:
[0016] 1. This application adds nano-inorganic oxides to the three-in-one pretreatment composition. The nano-inorganic oxides can participate in the formation of the passivation film, further improving the passivation performance of the passivation film. Moreover, the addition of nano-inorganic oxides can also improve the performance of the passivation film as a coating substrate, and enhance the adhesion and corrosion resistance of the surface coating to steel.
[0017] 2. In this application, the nano-inorganic oxide is further surface-treated with a silane coupling agent. The silane coupling agent contains mercapto groups, thioether bonds, thiourea and polysulfide bonds in its molecular structure, which can synergistically improve the passivation performance of the passivation film with the corrosion inhibitor. Detailed Implementation
[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below.
[0019] Throughout this specification, unless otherwise specified, the terminology used herein should be understood as having the meaning commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In the event of any conflict, this specification shall prevail.
[0020] This application provides a three-in-one pretreatment composition, which, by weight, comprises: 20-40% phosphoric acid, 1-3% organic acid, 1-5% accelerator, 0.1-0.3% film-forming aid, 0.5-1.5% surfactant, 0.5-1% pH stabilizer, 0.5-1.5% corrosion inhibitor, 0.3-1% defoamer, 1-5% nano-inorganic oxide, and the balance being water.
[0021] The three-in-one pretreatment composition of this application integrates degreasing, rust removal, and rust prevention into one process. It has a short processing time, high efficiency, good degreasing and rust removal effect, and the formed rust-proof film has good anti-corrosion performance, effectively improving the corrosion resistance of steel. It also improves the adhesion between steel parts and various organic coatings. When organic coatings are applied to the steel surface, the adhesion and corrosion resistance of the organic coating to the steel can be improved.
[0022] In the above-mentioned three-in-one pretreatment composition of this application, the surfactant is not particularly limited and can be a nonionic surfactant, such as AEO-9, AEO-12, Tween-80, etc., or an anionic surfactant, such as sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, etc. The defoamer is not particularly limited and can be a dimethyl silicone oil defoamer, a dimethyl silicone oil defoamer loaded with silica, a polyether-modified silicone oil, etc.
[0023] In a preferred embodiment of this application, the organic acid is selected from one or a combination of malic acid, tartaric acid, and citric acid. Malic acid, tartaric acid, and citric acid are strong acids and can coordinate and complex with ferric ions and ferrous ions, thereby enhancing the rust removal effect of the three-in-one pretreatment composition.
[0024] In this application, the accelerator is a film-forming accelerator, which is beneficial to film formation. In a preferred embodiment of this application, the accelerator is selected from one or a combination of sodium molybdate and sodium fluoride. Taking sodium molybdate as an example, sodium molybdate can form ferrous molybdate insolubles with ferrous ions, which promotes the uniformity and density of the anti-rust film and improves the anti-rust performance of the anti-rust film.
[0025] In a preferred embodiment of this application, the film-forming aid is selected from sodium nitrite. The inventors have discovered that using sodium nitrite as a film-forming aid can create a synergistic effect with the corrosion inhibitor thiourea and its derivatives, thereby improving the rust prevention capability of the anti-rust layer.
[0026] In a preferred embodiment of this application, the pH stabilizer is selected from trisodium phosphate. Sodium phosphate can form a buffer solution with phosphoric acid, exhibiting certain buffering properties and improving the pH stability of the three-in-one pretreatment solution.
[0027] In a preferred embodiment of this application, the corrosion inhibitor is selected from thiourea and its derivatives. Thiourea and its derivatives are commonly used corrosion inhibitors for metal surface treatment, forming good adsorption with the metal surface and creating a good anti-corrosion layer. In this application, thiourea and its derivatives serve as the main film-forming substance of the anti-rust layer. Specifically, thiourea and its derivatives can be selected from N-methylthiourea, N,N-dimethylthiourea, N-ethylthiourea, (2-methoxyethyl)thiourea, N,N'-diethylthiourea, 1,3-diethylidene thiourea, allyl thiourea, phenylthiourea, etc.
[0028] In a preferred embodiment of this application, the nano-inorganic oxide is treated with a silane coupling agent, the silane coupling agent having one or more of the following molecular structures: thiol group, thioether bond, thiourea and polysulfide bond. The nano-inorganic oxides are treated with silane coupling agents containing thiol groups, thioether bonds, thiourea, or polysulfide bonds in their molecular structure. This allows organic groups containing thiol groups, thioether bonds, thiourea, or polysulfide bonds to be grafted onto the surface of the nano-inorganic oxides. These organic groups can interact with thiourea and participate in the film formation of thiourea, which not only improves the bonding force and density between the anti-corrosion layer and the nano-inorganic oxides, but also helps to improve the density of the anti-rust layer, thus improving the anti-corrosion performance of the metal surface after treatment with the three-in-one pretreatment composition. In addition, the organic groups on the surface of the nano-inorganic oxides can further improve the bonding force between the organic coating and the nano-inorganic oxides, improving the adhesion and protective effect of the organic coating on the metal surface. Furthermore, the nano-inorganic oxides can impart higher roughness to the treated metal surface, which is more conducive to improving the bonding force of subsequent organic coatings. Moreover, due to the nano-size effect, the nano-inorganic oxides have some defects on their surface and have high activity. The metal surface treated with the three-in-one pretreatment solution of this application also has high activity. Therefore, the nano-inorganic oxides and the metal surface have a high degree of interaction and good stability.
[0029] In a preferred embodiment of this application, the silane coupling agent is selected from one or a combination of mercapto-containing silane coupling agents and acylthiourea-containing silane coupling agents. For example, a mercapto-containing silane coupling agent refers to a silane coupling agent whose molecular structure contains a mercapto group; specifically, it can be selected from 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptomethyldimethoxysilane, 3-mercaptomethyldiethoxysilane, etc.; an acylthiourea-containing silane coupling agent refers to a silane coupling agent whose molecular structure contains an acylthiourea group; specifically, it has the general formula R... 1 CONHCSNH(CH2)3Si(OR 2 )3, where R 1 Selected from C1-C8 alkyl, aromatic or substituted aromatic groups, R 2 Selected from C1-C4 alkyl groups. For example, R 1 It can be selected from methyl, ethyl, phenyl, 2-methoxyphenyl, 4-methoxyphenyl, 2-methylphenyl, 4-methylphenyl, 2-nitrophenyl, 4-nitrophenyl, etc. In this application, the acylthiourea-containing silane coupling agent can be prepared according to the following method: the corresponding acyl chloride R... 1 COCl reacts with KSCN to obtain R. 1 CONCS, R 1 CONCS then reacts with the corresponding NH2(CH2)3Si(OR) 2 )3 undergoes an addition reaction to obtain R. 1CONHCSNH(CH2)3Si(OR 2 3.
[0030] In a preferred embodiment of this application, the average particle size of the nano-inorganic oxide is 10-100 nm. Nano-inorganic oxides exhibit a nanoscale effect. When the average particle size of the nano-inorganic oxide is very low, such as below 10 nm (e.g., 5 nm, 3 nm), the interaction forces between the nanoparticles are too strong, making dispersion difficult. The nano-inorganic oxide is prone to agglomeration, affecting its effectiveness and resulting in poor corrosion resistance of the formed passivation layer. When the nano-inorganic oxide particles are larger, such as 150 nm, 200 nm, defects easily appear at the interface between the inorganic oxide and the metal in the passivation layer. Furthermore, the larger the nano-inorganic oxide particles, the fewer surface defects there are, resulting in lower activity and poorer interaction with the metal surface, leading to a deterioration in the passivation effect of the localized passivation layer. More preferably, the average particle size of the nano-inorganic oxide is 10-80 nm, for example, the average particle size can be 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, etc. Specifically, the nano-inorganic oxide can be selected from nano-silica, nano-titanium dioxide, etc.
[0031] Another aspect of this application proposes a method for preparing the three-in-one pretreatment composition described in any of the above embodiments, comprising: adding water, phosphoric acid, organic acid and surfactant to a container, mixing them evenly, then adding nano-inorganic oxide, dispersing it evenly, and then adding an accelerator, a film-forming aid, a pH stabilizer, a corrosion inhibitor and an antifoaming agent, mixing them evenly to obtain the final product.
[0032] The technical solution of this application will be described in detail below with reference to embodiments and comparative examples.
[0033] Example 1
[0034] The raw material components of the three-in-one pretreatment composition, by 100% weight, include: 24% phosphoric acid, 1.7% malic acid, 2.1% sodium molybdate, 0.15% sodium nitrite, 0.8% AEO-9, 0.8% sodium phosphate, 1.3% N-methylthiourea, 0.5% dimethyl silicone oil, 2% nano-silica with an average particle size of 25 nm, and the balance being water. Water, phosphoric acid, malic acid, and AEO-9 are added to a container and mixed thoroughly. Then, nano-silica is added and dispersed evenly. Next, sodium molybdate, sodium nitrite, sodium phosphate, N-methylthiourea, and dimethyl silicone oil are added and mixed thoroughly to obtain the three-in-one pretreatment composition.
[0035] Example 2
[0036] In Example 1, 25nm average particle size silica was replaced with an equal weight percentage of 60nm average particle size silica, while the other steps remained unchanged.
[0037] Example 3
[0038] In Example 1, the percentage of 25nm nano-silica was adjusted from 2% to 4%, the percentage of water was reduced by 2% accordingly, and the remaining steps remained unchanged.
[0039] Example 4
[0040] The nano-silica in Example 1 was treated with an acylthiourea silane coupling agent 4-CH3PhCONHCSNH(CH2)3Si(OCH3)3. The specific operation was as follows: 10 parts by weight of nano-silica were ultrasonically dispersed in 100 parts by weight of anhydrous ethanol, 1 part by weight of the above-mentioned acylthiourea silane coupling agent was added, the mixture was stirred and reacted for 2 hours, and the temperature was further increased to 60°C and reacted for another 2 hours. The mixture was then filtered, and the filtered solid was washed twice with anhydrous ethanol and dried to obtain nano-silica treated with the acylthiourea silane coupling agent.
[0041] In Example 1, nano-silica was replaced with nano-silica treated with the above-mentioned acyl thiourea silane coupling agent at an equal weight percentage, while the remaining steps remained unchanged.
[0042] Example 5
[0043] The nano-silica in Example 1 was treated with 3-mercaptopropyltrimethoxysilane. The specific operation was as follows: 10 parts by weight of nano-silica were ultrasonically dispersed in 100 parts by weight of anhydrous ethanol, and 0.8 parts by weight of 3-mercaptopropyltrimethoxysilane were added. The mixture was stirred and reacted for 2 hours. The temperature was then raised to 60°C and reacted for another 2 hours. The mixture was filtered, and the filtered solid was washed twice with anhydrous ethanol and dried to obtain mercapto-containing nano-silica.
[0044] In Example 1, the nano-silica was replaced with the above-mentioned mercapto-containing nano-silica in equal weight percentages, while the other steps remained unchanged.
[0045] Comparative Example 1
[0046] In Example 1, no nano-silica was added, the weight percentage of water was increased by 2%, and the other steps remained unchanged.
[0047] Comparative Example 2
[0048] In Example 1, nano-silica was replaced with an equal weight percentage of nano-silica with an average particle size of 5 nm, while the other steps remained unchanged.
[0049] Comparative Example 3
[0050] In Comparative Example 2, nano-silica with an average particle size of 5 nm was treated according to the method for treating nano-silica with an acylthiourea silane coupling agent as described in Example 4.
[0051] In Example 1, nano-silica was replaced with an equal weight percentage of the above-treated nano-silica, while the remaining steps remained unchanged.
[0052] Comparative Example 4
[0053] Nano-silica with an average particle size of 150 nm was treated according to the method for treating nano-silica with an acylthiourea silane coupling agent in Example 4.
[0054] In Example 1, nano-silica was replaced with an equal weight percentage of the above-treated nano-silica, while the remaining steps remained unchanged.
[0055] Comparative Example 5
[0056] The nano-silica in Example 1 was treated with KH-560. The specific operation was as follows: 10 parts by weight of nano-silica were ultrasonically dispersed in 100 parts by weight of anhydrous ethanol, 0.8 parts by weight of KH-560 were added, the mixture was stirred and reacted for 2 hours, the temperature was raised to 60°C and reacted for another 2 hours, the mixture was filtered, the filtered solid was washed twice with anhydrous ethanol, and dried to obtain epoxy-modified nano-silica.
[0057] In Example 1, nano-silica was replaced with the above-mentioned epoxy-modified nano-silica in equal weight percentages, while the remaining steps remained unchanged.
[0058] Comparative Example 6
[0059] In Example 1, sodium nitrite was not added, and the weight percentage of N-methylthiourea was increased by 0.15% accordingly, while the other steps remained unchanged.
[0060] Comparative Example 7
[0061] In Example 1, N-methylthiourea was not added, the weight percentage of sodium nitrite was increased by 1.3%, and the other steps remained unchanged.
[0062] Example 6
[0063] The raw material components of the three-in-one pretreatment composition, by 100% weight, include: 29% phosphoric acid, 2.2% tartaric acid, 3.3% sodium molybdate, 0.1% sodium nitrite, 1.1% sodium dodecylbenzenesulfonate, 0.9% sodium phosphate, 0.8% N,N-dimethylthiourea, 0.5% dimethyl silicone oil, 3.5% nano-titanium dioxide with an average particle size of 45 nm, and the balance being water. Water, phosphoric acid, tartaric acid, and sodium dodecylbenzenesulfonate are added to a container and mixed thoroughly. Then, nano-titanium dioxide is added and dispersed thoroughly. Next, sodium molybdate, sodium nitrite, sodium phosphate, N,N-dimethylthiourea, and dimethyl silicone oil are added and mixed thoroughly to obtain the three-in-one pretreatment composition.
[0064] Example 7
[0065] In Example 6, nano-titanium dioxide was treated with an acylthiourea silane coupling agent CH3CH2CONHCSNH(CH2)3Si(OCH3)3. The specific operation was as follows: 10 parts by weight of nano-silica were ultrasonically dispersed in 100 parts by weight of anhydrous ethanol, and 1.2 parts by weight of the above-mentioned acylthiourea silane coupling agent were added. The mixture was stirred and reacted for 2 hours, and then the temperature was raised to 60°C and reacted for another 2 hours. The mixture was filtered, and the solid was washed twice with anhydrous ethanol and dried to obtain nano-titanium dioxide treated with the acylthiourea silane coupling agent.
[0066] In Example 6, nano-titanium dioxide was replaced with nano-titanium dioxide treated with the above-mentioned acyl thiourea silane coupling agent at an equal weight percentage, while the remaining steps remained unchanged.
[0067] Example 8
[0068] The raw material components of the three-in-one pretreatment composition, by 100% weight, include: 25% phosphoric acid, 2% tartaric acid, 2.6% sodium molybdate, 0.12% sodium nitrite, 1% AEO-9, 0.9% sodium phosphate, 1% N-ethylthiourea, 0.5% dimethyl silicone oil, 4.5% nano-silica with an average particle size of 50 nm, and the balance being water. Water, phosphoric acid, tartaric acid, and AEO-9 are added to a container and mixed thoroughly. Then, nano-silica is added and dispersed evenly. Next, sodium molybdate, sodium nitrite, sodium phosphate, N-ethylthiourea, and dimethyl silicone oil are added and mixed thoroughly to obtain the three-in-one pretreatment composition.
[0069] Performance testing
[0070] The three-in-one pretreatment compositions of Examples 1-8 and Comparative Examples 1-7 were diluted 7 times with water to obtain pretreatment solutions.
[0071] Soak a Q235B H-beam with dimensions of 20 cm × 10 cm × 0.5 cm, moderately rusted on the surface and with red to black scale, into the above pretreatment solution at room temperature respectively, bubble with air, soak for 15 min, take out, wash twice with water, and dry to obtain the treated steel.
[0072] (I) Separate pretreatment: Place the treated steel in a constant temperature and humidity oven at 85% humidity and 85 °C for 72 hours, and observe whether rust spots appear. Measure 3 for each sample, and count the total number of rust spots of 3 samples.
[0073] (II) Spray paint: Spray a layer of epoxy primer (Double Lion ED200) with an average thickness of 60 μm on the surface of the treated steel above, dry at room temperature for 24 h, and then spray a layer of polyurethane topcoat (Double Lion PUCM200) with an average thickness of 40 μm.
[0074] Adhesion test: The samples after spraying paint are tested by the cross-cut method. Grade 5 - 1, with grade 5 being the best and grade 1 being the worst.
[0075] Resistance to water vapor: Place the samples after spraying paint in an environment at 60 °C and 95% humidity for 45 min, take out, dry the moisture, and place at room temperature for 1 hour, and test the adhesion by the cross-cut method.
[0076] Neutral salt spray test: Wrap the edges of the steel after spraying paint with transparent tape, draw cross lines at a 75° angle in the middle position, draw through to the substrate, and conduct a neutral salt spray test with 5% sodium chloride at 37 °C for 500 h. It is qualified if the maximum corrosion width on one side of the cross line does not exceed 2 mm, and unqualified if it exceeds 2 mm.
[0077] The results are shown in Table 1 below.
[0078] Table 1
[0079]
[0080]
[0081] As can be seen from the results in Table 1, the rusty steel treated with the three-in-one pretreatment composition of the present application can form a better passivation layer, has better protection for the steel, and can endow the organic coating with better protection performance for the steel.
[0082] This specific embodiment is only an explanation of the present application, and it is not a limitation to the present application. Those skilled in the art can make modifications without creative contributions to this embodiment according to needs after reading this specification, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.
Claims
1. A pretreatment composition combining degreasing, rust removal, and rust prevention, characterized in that, Based on 100% weight, the raw material composition includes: 20-40% phosphoric acid, 1-3% organic acid, 1-5% accelerator, 0.1-0.3% film-forming aid, 0.5-1.5% surfactant, 0.5-1% pH stabilizer, 0.5-1.5% corrosion inhibitor, 0.3-1% defoamer, 1-5% nano-inorganic oxide, and the balance being water; The organic acid is selected from one or a combination of malic acid, tartaric acid and citric acid; The accelerator is selected from one or a combination of two of sodium molybdate and sodium fluoride; The film-forming aid is sodium nitrite; The pH stabilizer is trisodium phosphate; The corrosion inhibitor is selected from thiourea and its derivatives; The nano-inorganic oxide is treated with a silane coupling agent, which is an acyl thiourea silane coupling agent. The average particle size of the nano-inorganic oxide is 10-100 nm.
2. A method for preparing the three-in-one pretreatment composition for degreasing, rust removal, and rust prevention as described in claim 1, characterized in that, include: Add the water, phosphoric acid, organic acid, and surfactant to a container and mix thoroughly. Then add the nano-inorganic oxide and disperse it evenly. Next, add the accelerator, film-forming aid, pH stabilizer, corrosion inhibitor, and defoamer and mix thoroughly to obtain the final product.