Surface treatment process for coloring metal articles

Abstract

A surface treatment process for coloring metal articles includes following steps. In a first step, a metal article is anodized to form a first anodic oxide layer including a first portion and a second portion on the original metal article. In a second step, the anodized metal article is dyed. In a third step, the first portion of the first anodic oxide layer is removed from the anodized metal article to partially expose a metal body of the anodized metal article. In a fourth step, the exposed metal body of the anodized metal article is anodized to form a second anodic oxide layer. In a fifth step, the exposed metal body of the metal article is dyed.

1 . A surface treatment process for coloring metal articles, comprising:
 providing a metal article;   anodizing the metal article, thereby forming a first anodic oxide layer on the original metal article;   dyeing the anodized metal article;   coating the first anodic oxide layer with a light curable ink;   attaching a flexible film to the anodized metal article, with the flexible film covering the light curable ink coating, the flexible film having a transparent portion and a patterned portion, the patterned portion being exposed and opaque to light;   exposing the metal article to cure the light curable ink coating covered by the transparent portion of flexible film, with the light curable ink coating covered by the patterned portion of flexible film remaining uncured;   removing the uncured light curable ink coating, thereby the first anodic oxide layer having a first portion exposed to the environment and a second portion covered by the cured light sensitive coating;   removing the first portion of the first anodic oxide layer form the anodized metal article, thereby exposing a metal body of the anodized metal article to the environment;   anodizing the exposed metal body; and   dyeing the exposed metal body.   
   
   
       2 . The surface treatment process as claimed in  claim 1 , wherein the metal article is made of a metal selected from the group consisting of aluminum, titanium, magnesium, steel, and any alloy thereof. 
   
   
       3 . The surface treatment process as claimed in  claim 1 , further comprising pretreatment pre-treating pre-anodized article by degreasing the surface of the metal article and then polishing the surface of the metal article. 
   
   
       4 . The surface treatment process as claimed in  claim 1 , wherein the anodizing process is carried out in an electrolyte containing about 180 to 200 g/l sulphuric acid and metal ions less than 20 g/l, at a direct current of about 11 volts to 13 volts for 30 to 50 minutes. 
   
   
       5 . The surface treatment process as claimed in  claim 1 , wherein the thickness of the light curable ink coating is about 10 to 50 microns. 
   
   
       6 . The surface treatment process as claimed in  claim 1 , wherein during the step of exposing the metal article to cure the light curable ink coating, the anodized metal article is exposed using an exposure machine at exposure energy of about 100 to 150 mj/cm 2 . 
   
   
       7 . The surface treatment process as claimed in  claim 1 , wherein the step of removing the uncured light curable ink coating is carried out in a photographic developer. 
   
   
       8 . The surface treatment process as claimed in  claim 1 , wherein the first portion of the first anodic oxide layer is removed from the anodized metal article by a chemical etching process. 
   
   
       9 . The surface treatment process as claimed in  claim 8 , wherein during the chemical etching process, the anodized metal article is immersed into sodium hydroxide solution at a concentration of about 40 g/l. 
   
   
       10 . The surface treatment process as claimed in  claim 1 , further comprising a step of removing the cured light curable coating covering the second portion of the first anodic oxide layer by using a release agent. 
   
   
       11 . A surface treatment process for coloring metal articles, comprising steps of:
 anodizing a metal article, thereby forming a first anodic oxide layer including a first portion and a second portion on the original metal article;   dyeing the anodized metal article;   removing a portion of the first anodic oxide layer from the anodized metal article to partially expose a portion of the metal body of the anodized metal article;   anodizing the exposed metal body of the anodized metal article to form a second anodic oxide layer; and   dyeing the exposed metal body of the metal article.   
   
   
       12 . The surface treatment process as claimed in  claim 11 , further comprising a step of applying a protective ink coating onto the first anodic oxide layer before removing the first portion of the first anodic oxide layer, the protective ink coating covering the second portion of the first anodic oxide layer. 
   
   
       13 . The surface treatment process as claimed in  claim 12 , wherein the step of applying a protective ink coating comprising: forming a light curable ink coating onto the first anodic oxide layer; attaching a flexible film to the anodized metal article, with the flexible film covering the light curable ink coating, the flexible having a transparent portion and a patterned portion, the patterned portion being exposed and opaque to light; exposing the metal article to cure the light curable ink coating covered by the transparent portion of flexible film, with the light curable ink coating covered by the patterned portion of flexible film remaining uncured; removing the uncured light curable ink coating. 
   
   
       14 . The surface treatment process as claimed in  claim 11 , wherein the metal article is made of a metal selected from the group consisting of aluminum, titanium, magnesium, steel, and any alloy thereof. 
   
   
       15 . The surface treatment process as claimed in  claim 11 , further comprising pre-treating the pre-anodized material by degreasing the surface of the metal article and then polishing the surface of the metal article. 
   
   
       16 . The surface treatment process as claimed in  claim 13 , wherein the thickness of the light curable ink coating is about 10 to 50 microns. 
   
   
       17 . The surface treatment process as claimed in  claim 13 , wherein the first portion of the first anodic oxide layer is removed from the anodized metal article by a chemical etching process.