Method of removing coating from coated magnesium alloy product, method of making recycled magnesium alloy and method of recycling coating

Abstract

A method is provided for removing a coating from a coated magnesium alloy product. The method includes a first treatment step of immersing the coated magnesium alloy product in a first alkaline solution, and a second treatment step of immersing the magnesium alloy product, which has undergone the first treatment step, in a second alkaline solution or in an acid solution. The second alkaline solution is different from the first alkaline solution.

1 . A method of removing a coating from a coated magnesium alloy product, the method comprising: 
 a first treatment step of immersing the coated magnesium alloy product in a first alkaline solution; and    a second treatment step of immersing the magnesium alloy product, which has undergone the first treatment step, in a second alkaline solution or in an acid solution, the second alkaline solution being different from the first alkaline solution.    
     
     
         2 . The method according to  claim 1 , wherein the first alkaline solution and/or the second alkaline solution contains potassium hydroxide as a main alkaline component.  
     
     
         3 . The method according to  claim 1 , wherein the acid solution contains an organic acid as a main acid component.  
     
     
         4 . The method according to  claim 1 , wherein the first treatment and/or the second treatment using the second alkaline solution is performed at 60-90° C.  
     
     
         5 . The method according to  claim 1 , wherein the first treatment is performed at 60-90° C., whereas the second treatment using the acid solution is performed at 20-70° C.  
     
     
         6 . The method according to  claim 1 , further comprising the step of rinsing the magnesium alloy product with water after the first treatment step and/or the second treatment step.  
     
     
         7 . The method according to  claim 1 , wherein the coating includes an undercoat layer and an overcoat layer, the first treatment step being performed for removing the overcoat layer, the second treatment step being performed for removing the undercoat layer.  
     
     
         8 . A method of making a recycled magnesium alloy comprising: 
 a coating removing step which includes a first treatment of immersing a coated magnesium alloy product in a first alkaline solution, and a second treatment of immersing the magnesium alloy product in a second alkaline solution or in an acid solution, the second alkaline solution being different from the first alkaline solution;    a melting step of melting the magnesium alloy product to provide molten metal;    a component analyzing step for determining a content of at least one component contained in the molten metal; and    a component controlling step for controlling the content of the component in the molten metal.    
     
     
         9 . The method according to  claim 8 , wherein the melting step includes melting a first flux together with the magnesium alloy product, the first flux functioning to separate impurities contained in the magnesium alloy product from the molten metal.  
     
     
         10 . The method according to  claim 8 , further comprising the step of putting a second flux into the molten metal before the component controlling step, the second flux functioning to generate a gas for preventing the molten metal from oxidizing.  
     
     
         11 . The method according to  claim 8 , further comprising the step of rinsing the magnesium alloy product with water after the first treatment and/or the second treatment.  
     
     
         12 . A coating recycling method comprising the steps of: 
 removing a coating from a coated magnesium alloy product by a first treatment of immersing the coated magnesium alloy product in a first alkaline solution, and a second treatment of immersing the magnesium alloy product, which has undergone the first treatment step, in a second alkaline solution or in an acid solution, the second alkaline solution being different from the first alkaline solution;    recovering the coating removed from the magnesium alloy product in the first treatment and the second treatment; and    pulverizing the recovered coating to provide a recycled coating material.    
     
     
         13 . The method according to  claim 12 , further comprising the steps of rinsing the magnesium alloy product with water after the first treatment and/or the second treatment, and recovering the coating removed from the magnesium alloy product in the rinsing step.  
     
     
         14 . The method according to  claim 12 , wherein the recycled coating material is added to a resin composition for molding a resin product.  
     
     
         15 . The method according to  claim 14 , wherein the resin composition contains a thermoplastic resin selected from the group consisting of ABS resin, polycarbonate resin, polypropylene resin, polystyrene resin, polyamide resin and polyphenylene sulfide resin.  
     
     
         16 . The method according to  claim 12 , wherein the recycled coating material is added to asphalt.