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Column 技術屋の解説

Column 技術屋の解説

2015.04.09

[No.8/17] Basic knowledge of Anticorrosive polymer film

Let me explain about Anticorrosive polymer film for a while.

I am proud to introduce myself that anyone cannot favorably compare with my experience and the knowledge. As I used to work for long periods and I could actually accumulate so many of them at the manufacturer of VCI paper. Compared to them, I cannot say I have much experience in the development for anticorrosive polymer film .

But, I can effectively point out about the basic matters and their fundamental issues of the anticorrosive polymer film.

When classified from how to make the rust preventive film, they can be in two types. One type is that the film is made by extrusion into film after applying heat to the corrosion inhibitor kneaded into resin such as polyethylene etc.  and making resin to flowing condition. The other is that the film is made by coating the corrosion inhibitor together with the adhesive on the plastic film surface.

Most of the anticorrosive polymer film in the present market is the former kneaded type, however I think the effectiveness of the coating type cannot be ignored in terms of the performance.

The respective character can be compared in the Table 6.

Coating type retain higher anti-corrosion capacity, because the similar corrosion inhibitor for VCI paper can be theoretically used.

On the other hands, kneaded type retain slightly anti-corrosion capacity, because the limited type of rust inhibitor can be only used which can withstand the heat, namely the resin is exposed at the high temperature enough to be melted in the process.

If used a rust inhibitor that is easy to vaporize, the inhibitor run away as vapor from the resin and cannot be remained. Even without escaping, the inhibitor will be decomposed by the heat.

The corrosion inhibitor, which can easily be vaporized as employed in making VCI paper, cannot be used for the kneaded type anticorrosive polymer film manufacturing.

As a result, it becomes difficult to make the higher anti-corrosion capacity, especially high volatile rust preventive power film.

The biggest disadvantage of the coating type is in the expensive manufacturing cost, compared with the kneaded type film.

Both the solvent to dissolve the corrosion inhibitor and the adhesive agent to attach the corrosion inhibitor on the film are required as the raw materials. These expenses are not necessary in manufacturing of the kneaded type film. Those portions are directly added as the material expense in the case of coating type film.

In addition, the energy for vaporizing the solvent and fixing the corrosion inhibitor on the film is required. Although it rather belongs to the manufacturing technique, it is also disadvantage for the coating type film, that can easily get curling because of attaching the different property of material on one side of the film,.

I think it was happened nearly 30 years old days. Because the information of a new coated type anticorrosive polymer film was invented, which had the same anti-corrosion power, was given to me, I tried to analyze its effectiveness of actual performance obtaining the sample in corrosion prevention. I remember that the sample showed the same anti-corrosion performance not to be outdone compared with VCI paper. But, this anticorrosive polymer film was not spread to the market. I think the reason was in the higher price.

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