Metal surface treatment method

A treatment method and technology for metal surfaces, applied in the direction of metal material coating process, etc., can solve problems such as accumulation of sodium ions

Inactive Publication Date: 2002-08-28
NIPPON PAINT CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, even in these methods, the addition of aqueous sodium nitrite solution as an accelerator in the zinc phosphate chemical conversion treatm

Method used

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  • Metal surface treatment method

Examples

Experimental program
Comparison scheme
Effect test

preparation example 1

[0063] (preparation example 1 prepares zinc nitrite aqueous solution)

[0064] In the 5-compartment electrodialyzer using the ion-exchange membrane shown in Fig. 1, an anion-exchange membrane (product of Asahi Glass Co.; Selemion AMV) A1, a cation-exchange membrane (Asahi Glass Co. Co.'s product; Selemion CMV) C1, said anion exchange membrane A2 and said cation exchange membrane C2 to define an anode compartment, a desalination compartment (I), a concentration compartment (I), a desalination compartment (II) and a cathode compartment , and only make NO 2 and Zn ions selectively migrate through the anion-exchange membrane and cation-exchange membrane respectively to obtain an aqueous solution of zinc nitrite. The test protocol is as follows.

[0065] In this way, 575 g of zinc sulfate heptahydrate was dissolved in ion-exchanged water to prepare ZnSO with a concentration of 15%. 4 aqueous solution, which is fed into the desalination chamber (I). On the other hand, 600 g of s...

Embodiment 1

[0088] Example 1 Effect of sodium ion concentration in surface treatment bath In the surface treatment bath described above, the concentration of sodium ions was varied, and the results obtained with the following iron plates were evaluated. Iron sheet (size / type): 70mm×150mm / SPC (cold-rolled steel sheet) and GA (galvanized steel sheet) The results of SPC steel sheet are listed in Table 1, and the results of GA steel sheet are listed in Table 2.

[0089] Table 1

[0090] sodium concentration

3600ppm

5000ppm

7500ppm

10000ppm

Appearance, naked eye observation

it is good

it is good

it is good

Difference

Coating weight

2.12

2.37

2.28

2.72

Crystal size

uniform, good

uniform, good

uniform, good

uneven, large

[0091] Table 2

[0092] sodium concentration

reference example 1

[0093] Reference example 1 Determine Na ion-1 (NaNO 2 Aqueous solution) cumulative amount

[0094] The SPC substrate (70mm×150mm) was treated under the above conditions to supplement the components (phosphoric acid, zinc, etc.) consumed during coating formation.

[0095] Quantities of various liquids on conventional production lines

[0096] A: Capacity of chemical conversion tank: 120 tons

[0097] B: NaNO used 2 Aqueous solution (NO 2 The concentration of sodium ions is 27% by weight, and the concentration of sodium ions is 13% by weight) Quantity: 150mL / batch

[0098] C: Amount of zinc used / batch: 60g

[0099] D: Amount of chemical conversion bath carried / batch: 5L (amount carried / substrate: 2mL; 2500 treated plates)

[0100] The above steps were repeated 3 times (3 cycles) as 1 cycle, and a total of 7500 plates were processed. When the carrier liquid of the above-mentioned chemical conversion bath is not recovered, NaNO 2 NO in aqueous solution 2 The ion concentra...

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Abstract

The invention provides a metal surface treatment method, which can form a zinc phosphate coating suitable for cationic electrodeposition coating of metal formed products, especially metal formed products with iron-type metal surfaces and zinc-type metal surfaces. The method applies to closed systems. A method of treating metal surfaces comprising a chemical conversion step of immersing a substrate in an acidic aqueous solution of zinc phosphate and using an aqueous solution of zinc nitrite as an accelerator, at an assumed concentration of zinc nitrite [Zn(NO2)2] of When NO2 is 10% by weight, the zinc nitrite aqueous solution basically does not contain calcium ions, and contains 0-6500ppm of sodium ions and 0-20ppm of sulfate ions.

Description

field of invention [0001] The present invention relates to a method for chemical conversion treatment of zinc phosphate on metal formed products such as automobile body, household electrical equipment, steel furniture and the like. background of the invention [0002] Metal formed products such as automotive bodies, household electrical appliances and steel furniture are often treated with zinc phosphate chemical conversion prior to coating. This treatment method is usually carried out using spray technology or dipping technology, but in the case of automobile bodies, the substrate has a complex multi-cavity structure and the corrosion resistance after coating is an important quality parameter, It is common practice to sequentially employ dip chemical conversion and coat with cationic electrodeposition coatings. In addition, as such a substrate, a substrate having an iron-type surface and a zinc-type surface is generally used. [0003] Conventional zinc phosphating treatme...

Claims

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Application Information

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IPC IPC(8): C23C22/07C23C22/13C23C22/18C23C22/36C23C22/73
CPCC23C22/13C23C22/182C23C22/365C23C22/73C23C22/07
Inventor 千原裕史柘植建二木之瀬丰畠透奥野惠理子
Owner NIPPON PAINT CO LTD
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