Chromium-free rust inhibitive treatment method for metal products having zinc surface and metal products treated thereby
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United States of America Patent
Stats
-
Sep 15, 2009
Grant Date -
May 1, 2008
app pub date -
Dec 13, 2007
filing date -
Jan 24, 2005
priority date (Note) -
In Force
status (Latency Note)
Importance
Abstract
Provided is a chromium-free surface treatment method which imparts practical rust inhibitive performance to a metal product having a zinc surface to which it was difficult to impart rust inhibitive performance of practical level. A conversion-coated film of zinc phosphate etc. is formed on the zinc surface of the metal product as pretreatment, and the silica-based film is formed by applying a chromium-free surface treatment agent which uses alcohol or mixture of water and alcohol as a solvent to the conversion-coated film. As a result, when an aqueous surface treatment agent containing alcohol is applied, it is possible to suppress the formation of white rusting for 72 hours or longer in the salt spray test.
First Claim
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