JPS5947386A - Method for chromating plated steel sheet - Google Patents

Abstract

PURPOSE:To stabilize the quality, by filling hardly soluble additives into a container other than a chromating vessel and by gradually dissolving the additives at the outside of the vessel to prevent the suspension of undissolved solid matter and to keep the concn. of additives uniform. CONSTITUTION:Hardly soluble additives 5 such as barium silicofluoride as a reaction accelerator are filled into a container 4 communicating with a chromating vessel 1 in which a Zn or Al plated steel sheet is chromated. A chromating soln. 3 is circulated through the container 4 to dissolve the additives 5 in the container 4 up to the maximum solubility. The concn. of the additives 5 in the soln. 3 is kept uniform, and the suspension of the additives 5 in the vessel 1 is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses a treatment solution 'fl: j+11. ,
This relates to a method for making full use of the original performance of a chromate treatment (41! product) by adjusting the chromate treatment to lJ.

Conventional, zinc plating, aluminum plating 3% M vx
It is used either unpainted, painted, or a combination of both. Accordingly, a chromate film is formed on the Mengi steel sheet by chromate treatment for the purpose of rust prevention, adhesion of the paint film after painting, and surface corrosion resistance depending on the respective application.

The method for forming a chromate film is to apply a treatment solution on the surface of the plated steel sheet in which enotinol coexists between the surface of the plated steel sheet and the chromate treatment solution, or a method using acid f treatment. There is.

Among these methods, a method in which the entire chromate film is formed by a chemical reaction with the surface of the plated steel sheet metal (
Zinc and aluminum are dissolved in the chromate treatment solution to become metal ions, and at the same time hydrogen ions from the treatment 7F are consumed. As a result, the concentration of free acid in the treatment solution decreases depending on the paper used to treat the steel sheet, and the desired chemical reaction gradually decreases until it becomes appropriate and no longer forms a Ronaut film, and the treatment solution must be discarded or renewed. It becomes necessary. In particular, in reactive chromate treatment solutions that utilize normal chemical reactions, llllI
As a reaction accelerator to improve edibility and paint film adhesion.
For example, products to which various acids, salts, or inorganic polymers have been added are used, but when these additives are used, corrosion resistance and odor-tightness of the coating are the same, but on the other hand, the processing solution is inevitably degraded. The disadvantage is that the lifespan is shortened.

Therefore, it is necessary to prevent aging of the reactive chromate treatment solution. For this reason, the addition of reaction accelerators is necessary to stabilize the product performance by adding a reaction accelerator to the
) Must be supplied at a strict constant rate. Therefore, it is desirable that the reaction accelerator used as an additive be highly efficient, and various fluorine compounds are generally used.

For example, barium fluorosilicate (BaS) is a fluorine compound.
iF6J is suitable for etching even if it is saturated in the chromate treatment solution (g-K/J-Is it possible to obtain a film with excellent corrosion resistance? 1] Above K, 1t=S If a surplus of 1 is contained in solid form, the chromate treatment progresses and is consumed as time goes on. While a constant concentration is maintained, in the spray method r1 is constantly circulated and in the dip method undissolved solids are dispersed (inhabited) in the chromate treatment. This is definitely preferable ( By suspending the above-mentioned undissolved solids rather than with -, they adhere to the chromate film formed on the surface of the plated steel sheet and restrict contact corrosion. Due to this, the influence of chromic acid stains on the product, which impairs the appearance of the product and reduces the product value by 1F.To prevent this phenomenon, filters VC and C are used.
Possible methods include settling in the past or in a separate tank, but d
) In the case of the recent report, work interruptions and complexity due to filter clogging due to heat radiation, and the need for sedimentation equipment/H7
1.Everything has its drawbacks.

As a result of intensive research to eliminate all of the above-mentioned drawbacks, the inventors of the present invention have found that in order to improve product performance, a poorly soluble additive (hereinafter referred to as the additive) is filled in a separate container from the entire treatment liquid tank, and the chromate treatment solution is The present invention has been developed to solve the problem of dissolving the liquid Wl in circulation, that is, sequentially dissolving it outside the treatment liquid tank.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a side sectional view showing a molten tube apparatus with a separate circuit comprising the basic constituent elements of the present invention.
5 is the additive. The chromate treatment liquid 6 dissolves the additive 5 as it passes through the entire communication container 4 from the treatment liquid tank 1, and
nn Quiz' The tray is structured so that it returns to the chromate treatment liquid tank 1. FIG. 2 is a side cross-sectional view fully illustrating an embodiment of a column contacting device using a separate circuit according to the present invention. In addition, by providing the filter 7, it became possible to capture undissolved solids as well as slatch which dissolves in the treatment liquid due to a chemical reaction with the chromate treatment liquid.

In the figure, 8 indicates a pump, and 9 indicates a floating object. The use of the above-mentioned apparatus achieves a product performance 11υ higher than that of the former) and also prevents aging of the processing solution.

Next, in actually observing the present invention, chromate treatment solution 1.1
A chromate treatment rrJj of a predetermined concentration is poured into a container 91, and a plastic ball 6 made of barium fluorosilicate (BaSiF6) is placed in a container 4 provided with a filter 7 as a cutting material 11. When the chromate treatment liquid filters through the communication pipe 2τ and passes through the container 4 by the operation of the pump 8, only the amount of barium fluorosilicate 11 necessary for chemical development is melted on the metal surface of the steel plate to be treated.IL filter 7f:
After that, it returns to chromate-1/treated liquid acid. Each time the chromate treatment solution passes through a separately provided container 4, fluorine ions are supplied in an amount commensurate with the amount consumed due to chemical decomposition, making it possible to perform continuous amate treatment. In addition, the present invention is applicable to the case of easily (6-added/)In products. - also applies. The method is chrome (・circulation flow of treatment liquid i+1
- just adjust. It may be circulated intermittently.

This will be explained in more detail in the following examples.

Part of Cr06 (7) is reduced with CrO3 water m solution K PVA (forpynyl alcohol polymerization + f500), and cr+
6° and cr+ 6 and nomolar ratio (Cr /Cr)
(The sum of Ba5iF65y, /l'f' and Cr and Cr'' to the ro-3 solution, when converted to total Crus'a degree, is 60!/l, and the plate thickness is 1.0 m in the bamate treatment line. ,rn,, Zinc coating amount 9CVl/-2 on one side, width 914m, -2 coils, plate thickness 0.6m-, aluminum coating amount 40y/''-2 on one side
The corrosion resistance and surface appearance of each talomete-treated steel sheet were investigated by threading a coil with a width of 914WLm and a total volume of 3QQ ton.

The survey results are shown in Table F.

As a conventional method, a method not according to the present invention shown in FIG. 6 was used, that is, a method in which excess barium fluorosilicate was completely added to the chromate treatment tank.

The basis of the investigation was indicated as follows.

The appearance of the product is visible to the naked eye, and there is no chromic acid stain at all. ◎ It is extremely closed and has a slight stain (J mark indicates that the stain is clearly visible).
Corrosion resistance marked with × indicates Corrosion resistance 1 wet test and stack test were conducted. The wet test was conducted in accordance with Section 6-1 of J Engineering Sz 0236.

In addition, the stack test was carried out using a board 1 canted into 70x150-islands.
Sprinkle water droplets uniformly on the sheet with a sprayer, let it sit, then wrap it in polyethylene film, etc., and store it under certain conditions in a 7 fl J humidity tank (temperature IW 49 ± 1°C, relative humidity 95% or more). After being allowed to stand for 2411 hours, it was visually evaluated in addition to a wetness test as follows.

Items with no white rust at all ◎ Items with a very small amount of white rust Q Items with a surface grade rate of 1U% or more × Galvanized steel sheets with test Nos. The aluminized steel sheets of Nos. 1 to 10 all showed good corrosion resistance and stable product performance, whereas conventional methods Nos. 11 to 20 caused white rust and showed unstable product performance. Ta. - 10,000, even though the surface appearance of the present invention V has no chromic acid stains = J
Therefore, in J17: Methods 11 to 20, chromic acid stains were clearly observed, impairing the appearance of the product.

Therefore, according to the method of the present invention, chromic acid stains caused by the fraction, mixing, and suspension of unfermented solid proboscis in the chromate-1 treatment solution can be completely prevented, and the chromic acid stains can be completely prevented. Glass power former rlt in f
In addition to maintaining the l15j- constant, the product performance is stabilized and the aging of the chromate treatment solution is also prevented.Industrially, each piece is considered to have one shift.

[Brief explanation of drawings]

Figure 1 shows the separate circuit IC, l: bath noqJ (equipment) of the present invention. Figure 2 shows the column contact seat behind the separate circuit of the present invention. Figure 6 shows the replenishment by the conventional method. This is a power 1 note. 1... Chromate treatment liquid 2. 2'... Communication field filter... Chromate treatment liquid 4... Container 5... Additive 6... Flastisoku 4ζ-Lua... Filter 8.・Pump 9...Floating object patent applicant Nissin!! Steel Co., Ltd. 7] ゝ4゛Patent attorney Noma ・Kakeo□...:
,... Patent Attorney Tadayuki Noma'・11 , (,, 1・1.-\゛PaN')'12. ' Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. In a method for completely treating a plated steel plate while supplying a concentration of a poorly soluble additive to a chromate treatment solution, a container communicating with a chromate treatment solution tank is filled with the hardly soluble additive, and the chromate treatment solution is circulated. A chromate treatment method for a plated steel sheet, in which the additives in the container are dissolved to a maximum degree and the concentration of the hardly soluble additives in the chromate treatment solution is kept constant. 2. The method for chromate treatment of a plated steel sheet according to claim 1, wherein the plated steel sheet is a galvanized steel sheet. 6. The method for chromate treatment of a plated steel plate according to claim 1, wherein the plated steel plate is an aluminized steel plate.