Column 技術屋の解説

Let me focus finally on VCI paper from this time, although I have discussed various matters on rust preventive oil and anticorrosive polymer film so far.

It is known that VCI paper is wrapping paper which has a function to reduce the metal to corrosion.

If not familiar the above, kindly refer to the explanations in “VCI paper is helpful” and “The reason why VCI paper is useful” etc., since has been written for easy understanding.

I proceed my explanation on the assumption that you have a look at the technical contents tentatively.

I have been in contact with numerous users who have been using VCI paper. I have found the most common error among users has been that they have not properly understood the VCI paper is subjected to what kind of metal.

I feel so many people still believe VCI paper is effective in any metal.

Unfortunately, VCI paper does not exist which shows superior corrosion inhibiting effect  to steel, and at the same time with no bad impact on such as copper and zinc.

On the other hands, I cannot say VCI paper for copper is also sufficient against steel.

In other words, versatile VCI paper does not exist that can use for any metal.

Customers are liable to the misuse of VCI paper when they want to pack the assembly type products in which plurality metals co-exist. There is a possibility that would have been hit by unexpected corrosion without confirming whether what metal co-exist.

Let me introduce the parable I talk well.

The insecticides and pesticides on the market do not work to promote the growth of insects and propagate them even if misused against the insect to be defeated, there is just not effective.

But, it does not go to such as insecticides in VCI paper. If used incorrectly, VCI paper will lead to enhance corrosion.

Let’s introduce the two cases that had been hit by unexpected corrosion.

The first story is related to zinc-coated steel sheet.

Let’s consider the use of VCI paper as the countermeasure because the red rust has occurred in the products made with zinc-coated steel sheet. VCI paper for steel was used because the red rust is corrosion of steel. As a result, the red rust will not occur, but the products would have been covered with white rust by zinc corrosion.

The second case is with copper-plated steel products.

In the case of this product, VCI paper dedicated for steel was used, it is troubled by rust because it was steel.

But, one day the accident occurred, namely the plated copper had been splendidly discolored.

Fortunately, the discoloration did not reach to the plated copper and the function of the product was not impaired. However, it was a case that the commercial value was reduced as the appearance became worse.