Method for producing black plated resin part

Patent metadata

Field	Value
Publication number	US-11761106-B2
Application number	US-202117384552-A
Country	US
Kind code	B2
Filing date	Jul 23, 2021
Priority date	Sep 26, 2018
Publication date	Sep 19, 2023
Grant date	Sep 19, 2023

Abstract

A method for producing a black plated resin part includes the steps of electroplating a resin substrate provided with an underlying plating layer in a trivalent chromium plating bath containing thiocyanic acid, to thereby form, on the underlying plating layer, a black chromium plating layer composed of trivalent chromium and having a thickness of 0.15 μm or more; and immersing the resin substrate provided with the black chromium plating layer in warm water at 30° C. or higher for a predetermined time. In the method, the amount of thiocyanic acid contained in the trivalent chromium plating bath, the temperature of the warm water, and the time of immersion of the resin substrate in the warm water are adjusted so that the black chromium plating layer exhibits a b* value of −1.7 or less based on the L*a*b* color system.

First claim

The invention claimed is:

1. A method for producing a black plated resin part, comprising the steps of:
electroplating a resin substrate provided with an underlying plating layer in a trivalent chromium plating bath containing thiocyanic acid, to thereby form, on the underlying plating layer, a black chromium plating layer composed of trivalent chromium and having a thickness of 0.15 μm or more; and
immersing the resin substrate provided with the black chromium plating layer in warm water at 30° C. or higher for a predetermined time, wherein
the amount of thiocyanic acid contained in the trivalent chromium plating bath, the temperature of the warm water, and the time of immersion of the resin substrate in the warm water are adjusted so that the black chromium plating layer exhibits a b* value of −1.7 or less based on the L*a*b* color system, and
the trivalent chromium in the black chromium plating layer is present as metallic chromium, chromium oxide, and chromium hydroxide.

2. The method according to claim 1 , wherein, in a surface region of the black chromium plating layer having a depth of at least 23 nm as measured from the surface of the black chromium plating layer, the compositional proportions of metallic chromium, chromium oxide, and chromium hydroxide satisfy the following relations: b+c>4a and c>0.8b wherein a, b, and c represent the compositional proportions of metallic chromium, chromium oxide, and chromium hydroxide, respectively (note: a>0, b>0, and c>0).

Assignees

• Toyoda Gosei Kk

Inventors

• Hotta Yuji
• Nakatani Koji
• Ono Hiroaki
• Fujii Shiho
• Isomura Noritake

Classifications

• C25D3/06 Primary

  from solutions of trivalent chromium · CPC title

• C25D5/56

  of plastics · CPC title

• C25D5/48

  After-treatment of electroplated surfaces · CPC title

• C25D5/14

  two or more layers being of nickel or chromium, e.g. duplex or triplex layers · CPC title

• C23C28/027

  including at least one metal matrix material comprising a mixture of at least two metals or metal phases or metal matrix composites, e.g. metal matrix with embedded inorganic hard particles, CERMET, MMC. · CPC title