Abstract: 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.

Abstract: An object is to provide a technique capable of forming a film having a dark black appearance and high corrosion resistance on a zinc plated component in a simple process, and a black coating film-forming vehicle component and/or fastening component that is obtained by: treating a surface of a zinc plated metal substrate with a black chemical conversion treatment agent containing trivalent chromium as an active ingredient, to form a black chemical conversion treatment film having an L value (brightness) of from 33 to 30; coating a black coating composition containing a black pigment in an amount of from 25 to 65% by weight in a thermosetting film-forming component and an alkoxysilane oligomer, on the black chemical conversion treatment film; and heat-curing the black coating composition thus coated.

Abstract: 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.

Abstract: An object is to provide a technique capable of forming a film having a dark black appearance and high corrosion resistance on a zinc plated component in a simple process, and a black coating film-forming vehicle component and/or fastening component that is obtained by: treating a surface of a zinc plated metal substrate with a black chemical conversion treatment agent containing trivalent chromium as an active ingredient, to form a black chemical conversion treatment film having an L value (brightness) of from 33 to 30; coating a black coating composition containing a black pigment in an amount of from 25 to 65% by weight in a thermosetting film-forming component and an alkoxysilane oligomer, on the black chemical conversion treatment film; and heat-curing the black coating composition thus coated.

Abstract: 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.