Black coupling member for vehicles, having excellent corrosion resistance and black appearance

Patent metadata

Field	Value
Publication number	US-10240237-B2
Application number	US-201414915120-A
Country	US
Kind code	B2
Filing date	Aug 19, 2014
Priority date	Aug 28, 2013
Publication date	Mar 26, 2019
Grant date	Mar 26, 2019

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.

First claim

The invention claimed is:

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.

2. The black fastening member for a vehicle according to claim 1 , wherein
the amount of chromium in the trivalent chromium black chemical conversion film is in a range from 0.3 to 3.0 mg/dm 2 .

3. The black fastening member for a vehicle according to claim 1 , wherein
the black coating film has a thickness in a range from 0.8 to 5 μm.

4. The black fastening member for a vehicle according to claim 1 , wherein
the black coating film comprises, relative to 100% by weight of the black coating film,
the blackening component in an amount of 2% by weight or more but less than 25% by weight, the blackening component comprising carbon black and a black dye,
a polyoxyethylene fatty acid ester as the friction coefficient-modifying component in an amount of 6 to 18% by weight, and
a polypropylene glycol-modified silicone as the modified organopolysiloxane in an amount of 92 to 47% by weight.

5. A method for obtaining a black fastening member for a vehicle having a lightness L value of 28 or lower, the method comprising:
forming a trivalent chromium black chemical conversion film having a lightness L value of 33 or lower on a surface of a zinc-plated metal substrate 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
forming a black coating film containing a blackening component in an amount of 2% by weight or more but less than 25% by weight relative to 100% by weight of the coating film on the trivalent chromium black chemical conversion film by using a black coating solution comprising the blackening component, a modified organopolysiloxane, and a friction coefficient-modifying component.

6. The black fastening member for a vehicle according to claim 1 , which is a bolt, a screw, a nut, or a washer.

7. The method according to claim 5 , wherein
the black fastening member for a vehicle is a bolt, a screw, a nut, or a washer.

Assignees

• Dipsol Chem
• Honda Motor Co Ltd

Inventors

• Kato Yasuhiro
• Inomata Toshiki
• Inoue Manabu
• Yoshida Hiroyuki
• Hirayama Hiroshi
• Mochizuki Shinsuke
• NAGAI Toshiyasu

Classifications

• C23C22/53 Primary

  Treatment of zinc or alloys based thereon · CPC title

• B05D5/06

  to obtain multicolour or other optical effects (B05D5/02 takes precedence) · CPC title

• C08K3/04

  Carbon · CPC title

• C09D183/12

  containing polyether sequences · CPC title

• C09D7/40

  Additives · CPC title