Phosphating process as cathode electrophoresis coating pretreatment

A cathodic electrophoresis and pretreatment technology, applied in the field of phosphating technology, can solve the problems of slow phosphating speed, high working temperature and difficult control, and achieve excellent corrosion resistance and adhesion, alkali resistance and corrosion resistance. , the effect of saving energy and resources

Inactive Publication Date: 2014-12-31
WUXI LUOSHE TECH VENTURE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The main problems of zinc-nickel-manganese ternary phosphating solution currently used in cathodic electrophoretic coating are: high working temperature, many phosphating residues; complex composition ratio, narrow range of process parameters, and difficult to control; nickel, High manganese content, high cost, poor market competitiveness, and nickel and manganese are toxic heavy metals, which is not conducive to environmental protection; slow phosphating speed, not suitable for automatic painting assembly line operations
Chinese patent CN1221043A "Zinc-nickel-manganese ternary system medium-temperature phosphating solution" has simple composition, good film formation, and low requirements for accelerators, but the concentration of phosphating solution is high,...

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0013] A phosphating process used as a pretreatment for cathodic electrophoretic coating. The phosphating solution used in this process consists of: zinc oxide 33g / L, 85% phosphoric acid 127g / L, nickel sulfate 12g / L, manganese carbonate 8g / L, potassium chlorate 5g / L, potassium fluoride 4g / L, hydroxylamine sulfate 9g / L, m-nitrobenzenesulfonic acid 6g / L, sodium citrate 17g / L, sodium polyphosphate 5g / L, triethanolamine 0.5g / L, plant acid 2g / L, pentaerythritol phosphate 0.2g / L, and the balance is water; the phosphating process is as follows: after the workpiece is first pickled→neutralized→oil degreasing→water washing process, its immersion temperature is at 25 ℃ , the free acidity is between 2-6 points; the total acidity is 55-65 points in the phosphating solution, take it out after 12 minutes of reaction, rinse with water, and dry.

Embodiment 2

[0015] A phosphating process used as a pretreatment for cathodic electrophoretic coating. The phosphating solution used in this process consists of: zinc oxide 37g / L, 85% phosphoric acid 123g / L, nickel sulfate 14g / L, manganese carbonate 6g / L, potassium chlorate 7g / L, potassium fluoride 2g / L, hydroxylamine sulfate 11g / L, m-nitrobenzenesulfonic acid 4g / L, sodium citrate 19g / L, sodium polyphosphate 3g / L, triethanolamine 1.5g / L, plant acid 1g / L, pentaerythritol phosphate 0.6g / L, and the balance is water; the phosphating process is as follows: after the workpiece is first pickled→neutralized→oil degreasing→water washing process, its immersion temperature is at 35 ℃ , the free acidity is between 2-6 points; the total acidity is 55-65 points in the phosphating solution, take it out after 6 minutes of reaction, rinse with water, and dry.

Embodiment 3

[0017] A phosphating process used as a pretreatment for cathodic electrophoretic coating. The phosphating solution used in this process consists of: zinc oxide 35g / L, 85% phosphoric acid 125g / L, nickel sulfate 13g / L, manganese carbonate 7g / L, potassium chlorate 6g / L, potassium fluoride 3g / L, hydroxylamine sulfate 10g / L, m-nitrobenzenesulfonic acid 5g / L, sodium citrate 18g / L, sodium polyphosphate 4g / L, triethanolamine 1.0g / L, plant acid 1.5g / L, pentaerythritol phosphate 0.4g / L, and the balance is water; the phosphating process is as follows: the workpiece is first soaked at a temperature of 30 ℃, the free acidity is between 2-6 points; the total acidity is 55-65 points in the phosphating solution, take it out after 8 minutes of reaction, rinse with water, and dry.

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Abstract

The present invention discloses a phosphating process as a cathode electrophoresis coating pretreatment. The phosphating solution adopted by the process comprises: 33-37 g/L of zinc oxide, 123-127 g/L of 85% phosphoric acid, 12-14 g/L of nickel sulfate, 6-8 g/L of manganese carbonate, 5-7 g/L of potassium chlorate, 2-4 g/L of potassium fluoride, 9-11 g/L of hydroxylamine sulfate, 4-6 g/L of m-nitrobenzene sulfonic acid, 17-19 g/L of sodium citrate, 3-5 g/L of sodium polyphosphate, 0.5-1.5 g/L of triethanolamine, 1-2 g/L of phytic acid, 0.2-0.6 g/L of pentaerythritol phosphate, and the balance of water. The phosphating process comprises: carrying out acid washing, neutralization, deoiling degreasing, and water washing on a workpiece, immersing into a phosphating solution with temperature of 25-35 DEG C, a free acidity of 2-6 and the total acidity of 55-65, carrying out a reaction for 6-12 min, washing with water, and drying.

Description

technical field [0001] The invention relates to the technical field of surface treatment, in particular to a phosphating process used as a pretreatment for cathodic electrophoretic coating. Background technique [0002] As one of the core technologies of pre-painting treatment, phosphating has been widely used in the world for nearly a hundred years. At present, the most used phosphating technology is zinc-based phosphating technology, and the main component of the phosphating film formed is zinc phosphate, namely Zn 3 (PO 4 ) 2 4H 2 O, referred to as [H] film. However, as domestic large-scale coating production lines generally adopt the cathodic electrophoretic coating process, the traditional zinc-based phosphating technology can no longer meet the requirements of cathodic electrophoretic coating, because cathodic electrophoretic coating requires the phosphating film to have good alkali resistance and electrical conductivity. properties, corrosion resistance and adhes...

Claims

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Application Information

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IPC IPC(8): C23C22/36C25D13/20
Inventor 高忠清
Owner WUXI LUOSHE TECH VENTURE
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