Environment-friendly heavy truck cab phosphating process

Abstract

The invention relates to an environment-friendly heavy truck cab phosphating process. The problem of generation of a type of pollutant nickel element is solved from the source. The method comprises the following steps: preparing a normal working liquid level solution in a phosphating tank, and weighing 3120 kg of a nickel-free phosphating agent SPH-L1600M, 325 kg of an additive AD-4813, 1105 kg of an additive AD-4856, 555 kg of a neutralizing agent NT-4055, and 29.25 kg of an accelerant AC-131; the method comprises the following steps: firstly, adding 2 / 3 volume of water into a phosphating tank, and then adding a metered nickel-free phosphating agent SPH-L1600M into the tank in a stirring state; after the materials are uniformly stirred, metered additives AD-4813 and AD-4856 are added into the tank in a stirring state; after uniformly stirring, adding a metered neutralizing agent NT-4055 into the tank in a stirring state; and after uniform stirring, adding a calculated amount of accelerant AC-131 into the tank in a stirring state, then adding water to a working liquid level, and putting into use after uniform stirring. By introducing a green phosphating process, a good working environment is created; after the green phosphating process is introduced, compared with traditional phosphating, the performance of the product is not reduced, the cost is not increased, and the discharge requirement of a park is met.

Description

Technical Field

[0001] The present invention belongs to the technical field of automobile coating pretreatment, and is used to form a uniform, dense, porous phosphating film on the surface through chemical reaction after degreasing, thereby enhancing the adhesion with the subsequent electrophoretic paint and improving the corrosion resistance of the entire coating. Specifically, it relates to an environmentally friendly heavy truck cab phosphating process. Background Art

[0002] In the phosphating process, nickel can accelerate the phosphating reaction and refine the crystallization of the phosphating film due to its similar properties to iron. The nickel content in traditional phosphating baths is usually 500-1300ppm, which is a Class I pollutant. The current automobile factory emission standards require the nickel content to be less than 1ppm. With increasingly stringent regulations, the cost of dealing with nickel emissions through water treatment will be very high.

[0003] At present, the industry uses zirconium salt + organic thin film pretreatment system to replace phosphating process, which is green and environmentally friendly. However, there are still many problems, such as higher quality requirements for body-in-white, no grinding marks are allowed, requirements for the activity of surface elements of the plate, higher requirements for oil residue after body degreasing, need for humidification device, higher requirements for electrophoretic performance, high throwing power and strong shrinkage resistance of electrophoretic paint, which is currently widely used in passenger cars (high requirements for metal raw material control and galvanizing) and small parts (low requirements), and is not suitable for pretreatment of heavy truck cabs. Summary of the invention

[0004] The present invention provides an environmentally friendly phosphating process, which solves the generation of a type of pollutant nickel element from the source, while continuously improving the function, consistency and stability of the product.

[0005] The present invention is achieved by the following technical solutions:

[0006] An environmentally friendly heavy truck cab phosphating process comprises the following steps:

[0007] S1: Prepare the normal working level solution in the phosphating tank, weigh: nickel-free phosphating agent SPH-L1600M: 3120kg, additive AD-4813: 325kg, additive AD-4856: 1105Kg, neutralizer NT-4055: 559kg, accelerator AC-131: 29.25kg; first add 2 / 3 volume of water to the phosphating tank, and then add the measured nickel-free phosphating agent SPH-L1600M to the tank under stirring; after stirring evenly, add the measured additives AD-4813 and AD-4856 to the tank under stirring; after stirring evenly, add the measured neutralizer NT-4055 to the tank under stirring; after stirring evenly, add the calculated amount of accelerator AC-131 to the tank under stirring, then add water to the working liquid level, stir evenly and put into use;

[0008] S2: During each production shift, the heating system and circulating stirring system shall be turned on more than 90 minutes in advance, and the stirring shall not be stopped during the production process;

[0009] S3: During production, check whether the phosphating position pipelines and liquid levels are normal. The temperature control devices of the phosphating heating circulation and phosphating warm water circulation pipeline systems are set to 40-45°C.

[0010] S4: Control online working parameters: total acid: 20-24 points, free acid: 0.6-1.1 points, accelerator: 2.5-5.0 points; phosphating solution working temperature: 40-45℃; phosphating time 3min, detection frequency is accelerator once / half shift, others once / shift;

[0011] S5: Periodic control parameters: phosphating bath solution ion concentration (g / L): Zn0.7-1.6, Mn0.2-0.7, F0.3-1.0, NO33.0-15.0, PO410.0-20.0; phosphating film analysis: uniform and dense appearance, crystallization 1-10um, P ratio ≥85%, film weight 1-3g / ㎡, phosphating slag content <300ppm, detection frequency 1 time / 2 months;

[0012] S6: Set the addition standard: When the total acid and free acid concentrations are low, add them according to daily consumption and the "Pretreatment, Electrophoresis Fluid Detection Test Sheet". For every 108kg SPH-L1600M added, the total acid increases by 1.0 point and the free acid increases by 0.2 point. When the accelerator is low, add 9.8kg AC131 accelerator to increase it by 1.0 point. When the total acid concentration is high, it will naturally decrease. When the free acid concentration is high, add 10kg NT-4055 to reduce the free acid by 0.1 point. When the accelerator concentration is high, it will naturally decrease.

[0013] In S1, the additives AD-4813 and AD-4856 should be added in small amounts and multiple times.

[0014] In S1, the neutralizer NT-4055 should be added in small amounts and multiple times and diluted 10 times, and then sprinkled on the tank and sprayed with water.

[0015] In S1, the accelerator AC-131 should be added in small amounts and multiple times, and diluted 3-5 times.

[0016] The process of the invention is environmentally friendly, removes a class of pollutants, and creates a good working environment by introducing a green phosphating process. After the green phosphating process is introduced, it is ensured that the performance of the product is not reduced and the cost is not increased compared with the traditional phosphating process, and the emission requirements of the park are met. DETAILED DESCRIPTION

[0017] The present invention makes the liquid surface conditioning agent have the function of inducing crystal morphology by compounding the crystal nucleus elements, adds the modified rare earth elements to the traditional phosphating accelerator, achieves the effect of refining the crystallization of the phosphating film and accelerating the film formation, and adds the coupling agent component to the phosphating agent to make up for the formation defect leakage point, increase the corrosion resistance of the film layer and the bonding force with the electrophoretic film layer. The specific scheme is:

[0018] In the phosphating tank, the normal working liquid level solution is prepared, which requires 3120kg of nickel-free phosphating agent SPH-L1600M (phosphoric acid, zinc oxide, organic silane, manganese carbonate), 325kg of additive AD-4813 (hydrofluoric acid, fluorosilicic acid), 1105kg of additive AD-4856 (sodium nitrate), 559kg of neutralizer NT-4055 (sodium hydroxide), and 29.25kg of accelerator AC-131 (sodium nitrite). First, add 2 / 3 volume of water to the phosphating tank, then add the measured phosphating slotting agent SPH-L1600M to the tank under stirring; after stirring evenly, add the calculated amount of additives AD-4813 and AD-4856 (addition process should be small and multiple times) to the tank under stirring; after stirring evenly, add the calculated amount of neutralizer NT-4055 (addition process should be small and multiple times, and it needs to be diluted 10 times and sprinkled on the tank and sprayed with water) to the tank under stirring; after stirring evenly, add the calculated amount of accelerator AC-131 (addition process should be small and multiple times, and it needs to be diluted 3-5 times) to the tank under stirring, and then add water to the working liquid level. After stirring evenly, it can be put into use.

[0019] Note:

[0020] 1) During each production shift, the heating system and circulating stirring system should be turned on more than 90 minutes in advance, and the stirring should not be stopped during the production process.

[0021] 2) During production, check whether the phosphating position pipeline and liquid level are normal. The temperature control devices of the phosphating heating circulation and phosphating warm water circulation pipeline system should be set to 40-45℃.

[0022] 3) Online working parameters: total acid: 20-24 points, free acid: 0.6-1.1 points, accelerator: 2.5-5.0 points; phosphating solution working temperature: 40-45℃; phosphating time 3min. The detection frequency is accelerator once / half shift, and other once / shift.

[0023] 4) Periodic control parameters: phosphating bath liquid ion concentration (g / L): Zn0.7-1.6, Mn0.2-0.7, F0.3-1.0, NO33.0-15.0, PO410.0-20.0; phosphating film analysis shows uniform and dense appearance, crystallization 1-10um, P ratio ≥85%, film weight 1-3g / ㎡, phosphating slag content <300ppm, detection frequency 1 time / 2 months.

[0024] 5) Adding standard: When the total acid and free acid concentrations are low, add them according to daily consumption and the "Pretreatment, Electrophoresis Fluid Detection Test Sheet". For every 108kg SPH-L1600M added, the total acid increases by 1.0 point and the free acid increases by 0.2 point. When the accelerator is low, add 9.8kg AC131 accelerator to increase it by about 1.0 point. When the total acid concentration is high, let it decrease naturally. When the free acid concentration is high, add 10kg NT-4055 to reduce the free acid by about 0.1 point. When the accelerator concentration is high, let it decrease naturally.

[0025] Positive effects of the present invention:

[0026] 1. Environmentally friendly, does not contain any type of pollutants;

[0027] 2. Stable quality, excellent phosphating film microstructure, compatibility with electrophoresis and topcoat, and excellent performance;

[0028] 3. The tank liquid is easy to maintain and the construction process parameters are easy to control.

[0029] The environmentally friendly phosphating of the present invention has fine and uniform crystals, which are consistent with the traditional ternary phosphating film. According to the national standard GB / T 6807 technical conditions for phosphating treatment of steel workpieces before painting, the environmentally friendly phosphating corrosion resistance performance test is carried out, and the corrosion resistance performance is qualified for 1h, which meets the requirements of the national standard GB / T 6807 technical conditions for phosphating treatment of steel workpieces before painting.

Claims

1. An environmentally friendly heavy truck cab phosphating process, characterized by: The following steps are involved: S1: Prepare the normal working level solution in the phosphating tank, weigh: nickel-free phosphating agent SPH-L1600M: 3120kg, additive AD-4813: 325kg, additive AD-4856: 1105Kg, neutralizer NT-4055: 559kg, accelerator AC-131: 29.25kg; first add 2 / 3 volume of water to the phosphating tank, then add the measured nickel-free phosphating agent SPH-L1600M to the tank under stirring; after stirring evenly, add the measured additives AD-4813 and AD-4856 to the tank under stirring; After stirring evenly, add the measured neutralizer NT-4055 into the tank under stirring; after stirring evenly, add the calculated amount of accelerator AC-131 into the tank under stirring, then add water to the working liquid level, stir evenly and put into use; S2: During each production shift, the heating system and circulating stirring system shall be turned on more than 90 minutes in advance, and the stirring shall not be stopped during the production process; S3: During production, check whether the phosphating position pipelines and liquid levels are normal. The temperature control devices of the phosphating heating circulation and phosphating warm water circulation pipeline systems are set to 40-45°C. S4: Control online working parameters: total acid: 20-24 points, free acid: 0.6-1.1 points, accelerator: 2.5-5.0 points; phosphating solution working temperature: 40-45℃; phosphating time 3min, detection frequency is accelerator once / half shift, others once / shift; S5: Periodic control parameters: phosphating bath solution ion concentration (g / L): Zn0.7-1.6, Mn0.2-0.7, F0.3-1.0, NO33.0-15.0, PO410.0-20.0; phosphating film analysis: uniform and dense appearance, crystallization 1-10um, P ratio ≥85%, film weight 1-3g / ㎡, phosphating slag content <300ppm, detection frequency 1 time / 2 months; S6: Set the addition standard: When the total acid and free acid concentrations are low, add them according to daily consumption and the "Pretreatment, Electrophoresis Fluid Detection Test Sheet". For every 108kg SPH-L1600M added, the total acid increases by 1.0 point and the free acid increases by 0.2 point. When the accelerator is low, add 9.8kg AC131 accelerator to increase it by 1.0 point. When the total acid concentration is high, it will naturally decrease. When the free acid concentration is high, add 10kg NT-4055 to reduce the free acid by 0.1 point. When the accelerator concentration is high, it will naturally decrease.

2. The environmentally friendly heavy truck cab phosphating process according to claim 1 is characterized by: In S1, the additives AD-4813 and AD-4856 should be added in small amounts and multiple times.

3. The environmentally friendly heavy truck cab phosphating process according to claim 1 is characterized by: In S1, the neutralizer NT-4055 should be added in small amounts and multiple times and diluted 10 times, and then sprinkled on the tank and sprayed with water.

4. The environmentally friendly heavy truck cab phosphating process according to claim 1 is characterized by: In S1, the accelerator AC-131 should be added in small amounts and multiple times, and diluted 3-5 times.