Hoden Seimitsu Kako Kenkyusho Co., Ltd.

Shoichiro Adachi

Yasuhiko Endo

Shunjiro Watanabe

Hideaki Nogami

Yukiyasu Kang

Kengo Takase

Yukiyasu Kan

Disclosed is a chromium-free rust-inhibitive surface treatment agent to form a siliceous film that rarely cracks or peels off and yields an excellent rust-inhibitive performance on zinc surfaces of a metal part. The chromium-free rust-inhibitive surface treatment agent is an alcoholic solution of alkoxysilane oligomer having weight-averaged molecular weight of 1,000 to 10,000, and 2.5 to 15% of silicon in molecules of the alkoxysilane oligomer has been replaced with titanium. To prepare partly titanium-replaced alkoxysilane oligomer, titanium compound, in which about a half of alkoxy groups in titanium tetraalkoxide has been chelated, is reacted with tetraalkoxysilane monomer or alkoxysilane oligomer in the alcoholic solution.

Chromium-free rust-inhibitive surface treatment agent for metal parts with zinc surfaces and metal parts with zinc surfaces coated with rust-inhibitive surface coated film

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.

Chromium-free rust inhibitive treatment method for metal products having zinc surface and metal products treated thereby

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Ogaki, Japan

Shoichiro Adachi