Column 技術屋の解説

In the title this time, I did daringly use “anticorrosive paper”, instead of writing with “VCI paper”. I wonder whether or say “Anticorrosive paper”, or saying “VCI paper? This time is a historic story related to the crown word of “volatile”. 

The two designations have been always used as a synonym for a long time. 

At first, “anticorrosive paper” was invented in the world by the Shell engineers in USA around the end of World War Ⅱ and was called with “VPI (Vapor Phase Inhibitor) paper”. The rust inhibitor used in this “anticorrosive paper” was a substance of new invention with the abbreviation of “DICHAN (Dicyclohexyl Ammonium Nitrite)”, which was slightly volatile. At the time, volatile-free rust inhibitor was well known. “DICHAN” was therefore positioned to say “volatile corrosion inhibitor”. 

The Shell engineers found that it was possible to prevent the occurrence of rust when leaving steel products in the anticorrosive paper, even if the paper and the products were not completely in close contact. “DICHAN” had exhibited rust preventive effect, vaporizing from the anticorrosive paper. In other words, “VPI paper” was a product that was applied “volatile corrosion inhibitor” to paper. 

Incidentally, the domestic production of this “VPI paper” was firstly started by the company known as “NIPPON KAKOH SEISHI CO., LTD.”, where I used to work before, with the introduction of technology from Shell. The products were manufactured and sold under the name of “NKVPI”. Photo 2 shows the first page of the technical circular at that time. This technology is not obsolete yet, even though it was issued in 1955, 60 years ago. “NKVPI” has been manufactured and being sold now even after “NIPPON KAKOH SEISHI CO., LTD.” was missed, and the technology has been inherited in our “adpack® White”. 

In Japan at that time, there was “NKVPI” only, and no other anticorrosive paper using volatile-free anticorrosive chemical. Although JIS (Japanese Industrial Standards) has been established in the name of “volatile rust sealant” in 1959, the targets were only “DICHAN”, volatile corrosion inhibitor, and “VPI paper”, vapor phase inhibitor paper. Namely, “anticorrosive paper” did just omit the designation of “volatile corrosion inhibitor paper”. 

Then, the type of anticorrosive paper was increased from USA to compete with “VPI paper” by newly developed technology introduced. “Anticorrosive paper” and “Volatile anticorrosive paper” state of synonyms was not changed, although the specification of volatile anticorrosive paper was revised in 1973 to JIS Z 1535 independently from JIS Z 1519 which used to cover both volatile corrosion inhibitor and volatile anticorrosive paper.   

However, through the times many types of anticorrosive paper have appeared in the market, those volatile level are less or almost nil when compared with “VPI paper” etc., and therefore, confusion has been occurred unless “Anticorrosive paper” and “Volatile anticorrosive paper” are clearly distinguished 

Therefore, discussions of years were developed to JIS Z 1535 and the large revision was finally performed and entered last year. In the last revision of JIS, that title was also changed. There are the volatile type and the contact type to the anticorrosive paper for steel. I think that it has become easier by clearly mentioning to understand a little.

In the JIS, we are supposed to call the former as “Volatile corrosion inhibitor paper” and the latter as “Contact type anticorrosive paper”. Of course, the above is the anticorrosive paper for steel, the anticorrosive paper for copper and copper alloy has been defined in the different JIS.