Black Coupling Member for Vehicles, Having Excellent Corrosion Resistance and Black Appearance

摘要

Provided is a black coupling member for vehicles, comprising a trivalent chromium black chemical conversion film and a black coating film upon the trivalent chromium black chemical conversion film, on the surface of a zinc-plated metal substrate. The trivalent chromium black chemical conversion film is formed using a hexavalent chromium-free trivalent chromium black chemical conversion treatment solution having a Zn ion concentration of no more than 20 g/L. The lightness (L) of the trivalent chromium black chemical conversion film is no more than 33. The black coating film includes a black chemical conversion component, a modified organopolysiloxane, and a friction coefficient-adjustment component. The black chemical conversion component content is 2-25 wt % relative to 100 wt % of the black coating film. The lightness (L) is no more than 28.

主权项

1. A black fastening member for a vehicle, comprising:
a zinc-plated metal substrate; a trivalent chromium black chemical conversion film on a surface of the metal substrate; and a black coating film on the trivalent chromium black chemical conversion film, wherein the trivalent chromium black chemical conversion film is formed by using a hexavalent chromium-free trivalent chromium black chemical conversion treatment liquid having a Zn ion concentration of 20 g/L or lower, and has a lightness L value of 33 or lower, and the black coating film comprises a blackening component, a modified organopolysiloxane, and a friction coefficient-modifying component with the amount of the blackening component being 2% by weight or more but less than 25% by weight relative to 100% by weight of the black coating film, and has a lightness L value of 28 or lower.