Steel phosphating post-treatment agent as well as preparation method and application thereof

Abstract

The invention relates to the technical field of steel surface treatment, and discloses a steel phosphating post-treatment agent as well as a preparation method and application thereof. The steel phosphating post-treatment agent comprises a solvent and the following preparation raw materials in percentage by mass: 1-5% of a metal corrosion inhibitor; 1-5% of an emulsifier; 0.1-1% of a preservative; 0.1-1% of an antirust additive; a solvent of the steel phosphating post-treatment agent is water; the mass percentage refers to the percentage of each preparation raw material in the total mass of the steel phosphating post-treatment agent. The steel phosphating post-treatment agent provided by the invention can overcome the defects that a traditional oily phosphating post-treatment agent is easy to release volatile organic compounds, is easy to soften at high temperature and the like; in steel phosphating film sealing treatment, a compact protective film can be formed on the surface of a phosphating film, the corrosion resistance of the phosphating film is improved, the neutral salt mist environment tolerance time and the air storage time of a steel workpiece are prolonged, the quality and the uniformity of the phosphating film cannot be affected, and the appearance effect of the workpiece can be guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of steel surface treatment, and in particular to a steel phosphating post-treatment agent and a preparation method and application thereof. Background Art

[0002] In order to make steel materials withstand the corrosion of oxygen and water in the atmosphere, the surface of steel materials is usually phosphated to form a phosphate film, but the phosphate film has many gaps and its corrosion resistance is poor. In order to improve the corrosion resistance of the phosphate film, a phosphate post-treatment agent is usually used after phosphating to passivate or seal the phosphate film. The phosphate post-treatment agent can further react with the phosphate film, fill the micropores and defects of the phosphate film, and form a denser protective film, thereby improving the corrosion resistance of the metal and extending the tolerance time in the salt spray environment and the storage time in the air.

[0003] Most of the existing phosphating post-treatment agents are oil film post-treatment agents, which have the following disadvantages during and after use: (1) The phosphating film is easily contaminated with dust and dirt; (2) It affects subsequent processing, resulting in difficulty in coating and reduced welding performance; (3) It contains volatile organic compounds, which are easily released into the air during use and drying, endangering human health and the environment; (4) The oil film is not easily degraded in the natural environment and may pollute the soil and water sources; (5) The oil film is easy to soften, flow or decompose at high temperature, resulting in reduced protective performance and relatively weak corrosion resistance. It cannot provide sufficient protection in harsh corrosive environments, causing rust and corrosion on the metal surface.

[0004] In addition, some phosphating post-treatment agents are easily dissolved by alcohol or solvents, are not resistant to wiping, have impaired performance, and reduce protective performance, which affects the quality of the coating, causing blistering and peeling of the coating, and cannot achieve the expected aesthetic and protective effects. Some phosphating post-treatment agents also have an adverse effect on the roughness and glossiness of the metal surface. For example, in traditional chromium-free passivation treatment, the reaction between the passivating agent and the phosphating film may increase the surface roughness of the phosphating film and change the glossiness, affecting the quality and uniformity of the phosphating film; improper post-treatment operations, such as uneven painting and poor curing of the sealant during the process, will cause defects such as flow marks, bubbles, and particles on the surface, increase roughness, and affect glossiness.

[0005] Therefore, it is urgent to develop a non-oily phosphating post-treatment agent that does not affect the appearance of the phosphating film to improve the corrosion resistance of the steel phosphating film. Summary of the invention

[0006] The present invention aims to solve at least one of the above-mentioned technical problems existing in the prior art. To this end, one of the purposes of the present invention is to provide a steel phosphating post-treatment agent; the second purpose of the present invention is to provide a preparation method of the steel phosphating post-treatment agent; the third purpose of the present invention is to provide the application of the steel phosphating post-treatment agent.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] The first aspect of the present invention provides a steel phosphating post-treatment agent, comprising a solvent and the following raw materials in mass percentage:

[0009]

[0010] The solvent of the steel phosphating post-treatment agent is water;

[0011] The mass percentage refers to the percentage of each preparation raw material to the total mass of the steel phosphating post-treatment agent.

[0012] In some embodiments of the present invention, the steel phosphating post-treatment agent comprises a solvent and the following raw materials in percentage by weight:

[0013]

[0014] The solvent of the steel phosphating post-treatment agent is water.

[0015] In some specific embodiments of the present invention, the steel phosphating post-treatment agent is prepared from the following raw materials in mass percentage:

[0016]

[0017] The balance is water.

[0018] In some embodiments of the present invention, the metal corrosion inhibitor is selected from at least one of thiourea, sodium dihydrogen phosphate, and sodium hexametaphosphate.

[0019] In some embodiments of the present invention, the emulsifier is selected from at least one of alkylphenol polyoxyethylene ether, sodium lauryl sulfate, and hexadecyltrimethylammonium bromide.

[0020] In some embodiments of the present invention, the preservative is selected from at least one of sodium benzoate, sorbic acid, dodecenylsuccinic acid, and zinc phosphate.

[0021] In some embodiments of the present invention, the anti-rust additive is selected from at least one of imidazoline, benzotriazole, sodium nitrite and sodium tripolyphosphate.

[0022] In some embodiments of the present invention, the pH of the steel phosphating post-treatment agent is 6-8.

[0023] The second aspect of the present invention provides a method for preparing the steel phosphating post-treatment agent according to the first aspect of the present invention, comprising the following steps:

[0024] The antiseptic and the emulsifier are first mixed, and then the metal corrosion inhibitor, the anti-rust additive and the solvent are added, and the mixture is mixed under heating conditions to obtain the steel phosphating post-treatment agent.

[0025] In some embodiments of the present invention, the heating temperature is 50-70°C.

[0026] In some specific embodiments of the present invention, the heating temperature is 55-65°C.

[0027] The third aspect of the present invention provides the use of the steel phosphating post-treatment agent described in the first aspect of the present invention in the sealing treatment of the steel phosphating film.

[0028] In some embodiments of the present invention, the temperature of the steel phosphate film sealing treatment is 20-70° C. and the time is 1-5 min.

[0029] In some embodiments of the present invention, after the sealing treatment of the steel phosphate film is completed, an operation of directly drying with 70-75° C. hot air is also included.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1) The steel phosphating post-treatment agent provided by the present invention has simple components and uses water as a solvent to form an aqueous phosphating post-treatment agent, which can overcome the defects of the traditional oily phosphating post-treatment agent, such as easy release of volatile organic matter and easy softening at high temperature;

[0032] 2) The preparation method of the steel phosphating post-treatment agent provided by the present invention has simple steps, mild process conditions, and is suitable for industrial use;

[0033] 3) The steel phosphating post-treatment agent provided by the present invention is applied to the sealing treatment of the steel phosphating film, can form a dense protective film on the surface of the phosphating film, improve the corrosion resistance of the phosphating film, extend the neutral salt spray environment tolerance time and air storage time of the steel workpiece, and while achieving the protection of the phosphating film, will not affect the quality and uniformity of the phosphating film, and can ensure the appearance effect of the workpiece. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a physical picture of the workpiece in the application example. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below by specific examples. The raw materials, reagents or devices used in the examples can be obtained from conventional commercial sources or by prior art methods unless otherwise specified. Unless otherwise specified, the experiments or test methods are conventional methods in the art.

[0036] Example 1

[0037] This embodiment prepares a steel phosphating post-treatment agent, and the raw materials and amounts used are shown in Table 1:

[0038] Table 1 Preparation raw materials and dosage of steel phosphating post-treatment agent in Example 1

[0039]

[0040] The preparation steps are as follows:

[0041] Firstly, the preservative and the emulsifier are mixed, and then the metal corrosion inhibitor, the anti-rust additive and the solvent are added, and the mixture is heated and mixed at 60° C. to prepare a 1L mixed solution, and the pH of the mixed solution is adjusted to 6-8 to obtain a steel phosphating post-treatment agent.

[0042] Example 2

[0043] This embodiment prepares a steel phosphating post-treatment agent, and the raw materials and amounts are shown in Table 2:

[0044] Table 2 Preparation raw materials and dosage of steel phosphating post-treatment agent in Example 2

[0045]

[0046] The preparation steps are as follows:

[0047] Firstly, the preservative and the emulsifier are mixed, and then the metal corrosion inhibitor, the anti-rust additive and the solvent are added, and the mixture is heated and mixed at 60° C. to prepare a 1L mixed solution, and the pH of the mixed solution is adjusted to 6-8 to obtain a steel phosphating post-treatment agent.

[0048] Example 3

[0049] This embodiment prepares a steel phosphating post-treatment agent, and the raw materials and amounts are shown in Table 3:

[0050] Table 3 Preparation raw materials and dosage of steel phosphating post-treatment agent in Example 3

[0051]

[0052] The preparation steps are as follows:

[0053] Firstly, the preservative and the emulsifier are mixed, and then the metal corrosion inhibitor, the anti-rust additive and the solvent are added, and the mixture is heated and mixed at 60° C. to prepare a 1L mixed solution, and the pH of the mixed solution is adjusted to 6-8 to obtain a steel phosphating post-treatment agent.

[0054] Example 4

[0055] This embodiment prepares a steel phosphating post-treatment agent, and the raw materials and amounts are shown in Table 4:

[0056] Table 4 Preparation raw materials and dosage of steel phosphating post-treatment agent in Example 4

[0057]

[0058] The preparation steps are as follows:

[0059] Firstly, the preservative and the emulsifier are mixed, and then the metal corrosion inhibitor, the anti-rust additive and the solvent are added, and the mixture is heated and mixed at 60° C. to prepare a 1L mixed solution, and the pH of the mixed solution is adjusted to 6-8 to obtain a steel phosphating post-treatment agent.

[0060] Example 5

[0061] This embodiment prepares a steel phosphating post-treatment agent, and the raw materials and amounts are shown in Table 5:

[0062] Table 5 Preparation raw materials and dosage of steel phosphating post-treatment agent in Example 5

[0063]

[0064] The preparation steps are as follows:

[0065] Firstly, the preservative and the emulsifier are mixed, and then the metal corrosion inhibitor, the anti-rust additive and the solvent are added, and the mixture is heated and mixed at 60° C. to prepare a 1L mixed solution, and the pH of the mixed solution is adjusted to 6-8 to obtain a steel phosphating post-treatment agent.

[0066] Application Examples

[0067] The steel phosphating post-treatment agents in Examples 1 and 2 were used for phosphating film sealing treatment of carbon steel workpieces 1 and 2, respectively. Figure 1 is a physical picture of the workpiece in the application example, where: Figure 1 (a) is the physical picture of workpiece 1. Figure 1 (b) is a real picture of workpiece 2.

[0068] The process steps of phosphating treatment and phosphating film sealing treatment of carbon steel workpieces are shown in Table 6, wherein the formula of the phosphating solution used for phosphating treatment is: 45g / L manganese dihydrogen phosphate, 35g / L manganese nitrate, 24g / L phosphoric acid, 0.4g / L hydroxylamine sulfate, 0.8g / L nitric acid, and the balance is water.

[0069] Table 6 Phosphating treatment and phosphating film sealing treatment process steps of carbon steel workpieces 1 and 2 in the application example

[0070]

[0071] The carbon steel workpieces after phosphating film sealing treatment were subjected to neutral salt spray test, air storage time test, surface tension test and roughness test, and the workpieces that were not sealed by steel phosphating film after phosphating treatment and directly dried at 70-75℃ for 40s were used as comparison. The test method is as follows:

[0072] 1. Neutral salt spray test:

[0073] Refer to GB / T10125-2021 "Artificial atmosphere corrosion test salt spray test", specifically:

[0074] 1) Dissolve chemically pure sodium chloride in distilled water to prepare a saline solution with a concentration of (50±5) g / L. Measure the pH value of the solution with an acidity meter, and adjust the pH value to 6.5-7.2 with chemically pure hydrochloric acid or sodium hydroxide. Filter the solution before use, wash the sample thoroughly, avoid contamination after washing, and protect the cutting area of ​​the workpiece;

[0075] 2) Place the sample in the salt spray chamber with the test surface facing upwards and at an angle of 15°-30° to the vertical direction to prevent the sample from directly contacting the chamber or each other. The chamber temperature is maintained at (35±2)℃ and the humidity is greater than 95%. The salt solution is sprayed into the chamber through a spray device to form a salt spray environment. The nozzle pressure is 78.5-137.3kPa and the fogging volume is 1-2mL / (h·cm 2 The test was carried out continuously, with 2 hours as one observation period, and the spraying was continuous. The test period was 24 hours.

[0076] 2. Air storage time test:

[0077] The samples were exposed to the same air environment and the time when their appearance changed was recorded. The standard requirement for the air storage time of carbon steel workpieces 1 and 2 is greater than or equal to 8 hours.

[0078] 3. Surface tension test:

[0079] Use a 36-digit dyne pen to test, ensure that the workpiece surface is clean, free of oil and impurities, hold the dyne pen perpendicular to the test surface, apply a force of 3-5N, draw a 2-3cm long straight line within 2s, and then observe the shrinkage of the pen within 5s. If the line is evenly distributed without any beads, it means that the surface tension is higher than the index marked on the dyne pen, which means it has passed; if the line shrinks slowly or immediately and forms beads, it means that the surface tension is lower than the index marked on the dyne pen, which means it has failed. Among them, the surface tension standard requirement of carbon steel workpieces 1 and 2 is to pass the 36-digit dyne pen test.

[0080] 4. Roughness test:

[0081] Refer to GB / T 15056-2017 "Evaluation Method of Casting Surface Roughness" for testing, specifically:

[0082] A very sharp stylus is placed vertically on the surface of the workpiece to be measured, and the stylus moves horizontally. According to the contour of the measured surface, the stylus will automatically make vertical ups and downs. The displacement activity of the stylus is converted into an electrical signal by a circuit, and the surface roughness index is obtained after analysis and calculation. Among them, the roughness index RZ standard requirement of carbon steel workpiece 1 is less than 2μm, and the roughness index Ra standard requirement of carbon steel workpiece 2 is less than 0.5μm.

[0083] Table 7 Neutral salt spray test and air storage time test results of carbon steel workpieces in the application example

[0084]

[0085]

[0086] Table 7 shows the neutral salt spray test and air storage time test results of the carbon steel workpieces in the application examples. It can be seen from Table 1 that after the phosphating treatment, the workpieces 1 and 2 will rust once exposed to the neutral salt spray or air environment after drying without the phosphating film sealing treatment. After the phosphating film sealing treatment is performed using the steel phosphating post-treatment agent in Examples 1 and 2, the neutral salt spray environment and air storage time are significantly prolonged compared with the case without the phosphating film sealing treatment, indicating that the steel phosphating post-treatment agent provided by the present invention forms a denser protective film on the surface of the phosphating film, effectively improving the corrosion resistance of the phosphating film.

[0087] Table 8 Surface tension and roughness test results of carbon steel workpiece in application example

[0088]

[0089] Table 8 shows the test results of surface tension and roughness of carbon steel workpieces in the application examples. It can be seen from Table 8 that after workpieces 1 and 2 are phosphated, they are subjected to phosphating film sealing treatment using the steel phosphating post-treatment agent in Examples 1 and 2. The surface tension of the phosphating film can be tested by a No. 36 dyne pen, and the surface roughness is slightly reduced compared to that before sealing, indicating that the quality and uniformity of the phosphating film are not affected compared to the case without phosphating film sealing treatment, and the appearance is not affected while achieving the protective effect.

Claims

1. A steel phosphating post-treatment agent, characterized in that: Including solvent and the following mass percentages of preparation raw materials: Metal corrosion inhibitor 1-5%; Emulsifier 1-5%; Preservatives 0.1-1%; Anti-rust additive 0.1-1%; The solvent of the steel phosphating post-treatment agent is water; The mass percentage refers to the percentage of each preparation raw material to the total mass of the steel phosphating post-treatment agent.

2. The steel phosphating post-treatment agent according to claim 1, characterized in that: The metal corrosion inhibitor is selected from at least one of thiourea, sodium dihydrogen phosphate and sodium hexametaphosphate.

3. The steel phosphating post-treatment agent according to claim 1, characterized in that: The emulsifier is selected from at least one of alkylphenol polyoxyethylene ether, sodium lauryl sulfate, and hexadecyltrimethylammonium bromide.

4. The steel phosphating post-treatment agent according to claim 1, characterized in that: The preservative is selected from at least one of sodium benzoate, sorbic acid, dodecenylsuccinic acid and zinc phosphate.

5. The steel phosphating post-treatment agent according to claim 1, characterized in that: The anti-rust additive is selected from at least one of imidazoline, benzotriazole, sodium nitrite and sodium tripolyphosphate.

6. The steel phosphating post-treatment agent according to any one of claims 1 to 5, characterized in that: The pH of the steel phosphating post-treatment agent is 6-8.

7. The method for preparing the steel phosphating post-treatment agent according to any one of claims 1 to 6, characterized in that: The following steps are involved: The antiseptic and the emulsifier are first mixed, and then the metal corrosion inhibitor, the anti-rust additive and the solvent are added, and the mixture is mixed under heating conditions to obtain the steel phosphating post-treatment agent.

8. The preparation method according to claim 7, characterized in that: The heating temperature is 50-70°C.

9. Use of the steel phosphating post-treatment agent according to any one of claims 1 to 6 in the sealing treatment of steel phosphating film.

10. The use according to claim 9, characterized in that: The temperature of the steel phosphating film sealing treatment is 20-70°C and the time is 1-5 minutes.

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