Method for recovering metal powder from platinum paste and method for regenerating platinum paste

Abstract

The present invention relates to a technique for recovering and recycling a platinum paste. The present invention provides a method for recovering a metal powder from a platinum paste formed by mixing a solid component composed of a metal powder including at least a platinum powder or a platinum alloy powder and an organic component including at least an organic solvent, the method including removing the organic component by heating the platinum paste at a recovery temperature set in a temperature range of 300° C. or higher and 500° C. or lower. The recovered metal powder can be recycled into a platinum paste equivalent to a new product by mixing the metal powder with a solvent etc.

1 - 8 . (canceled) 
     
     
         9 . A method for recovering a metal powder from a platinum paste formed by mixing a solid component composed of a metal powder including at least a platinum powder or a platinum alloy powder and an organic component including at least an organic solvent, comprising the steps of
 heating the platinum paste at a recovery temperature set in a temperature range of 300° C. or higher and 500° C. or lower, thereby to remove the organic component and recover the metal powder.   
     
     
         10 . The method for recovering a metal powder from a platinum paste according to  claim 9 , comprising the steps of treating a platinum paste corresponding to at least one of the following conditions:
 (a) a platinum paste viscosity has been changed by ±20% or more compared with the viscosity at the time of production of the platinum paste;   (b) one or both of a platinum paste viscosity ratio of 0.4/s to 4/s (η0.4/η4) or a platinum paste viscosity ratio of 4/s to 20/s (η4/η20) as measured by Brookfield viscometer are changed by 10% or more with respect to the platinum paste viscosity ratio at the time of production; and   (c) a solid component content has been changed by ±2% or more with respect to the solid component content at the production time.   
     
     
         11 . The method for recovering a metal powder from a platinum paste according to  claim 10 , wherein the organic solvent as the organic component includes ethylene glycol, propylene glycol, ethylene glycol monophenyl ether, benzyl alcohol, kerosene, γ-butyrolactone, N-methylpyrrolidone, butyl carbitol, butyl carbitol acetate, terpin oil, α-terpineol, texanol, menthanol and/or menthanol acetate. 
     
     
         12 . The method for recovering a metal powder from a platinum paste according to  claim 11 , wherein the organic component includes a resin. 
     
     
         13 . The method for recovering a metal powder from a platinum paste according to  claim 12 , wherein the resin includes at least one of a cellulose derivative, a butyral resin, a polyvinyl acetate resin, an amino-based resin and an alkyd resin. 
     
     
         14 . The method for recovering a metal powder from a platinum paste according to  claim 13 , wherein the solid component includes at least one of a ceramic powder and insoluble particles. 
     
     
         15 . The method for recovering a metal powder from a platinum paste according to  claim 14 , wherein the platinum paste is preliminarily heated at 150° C. to 200° C. before being heated at a recovery temperature. 
     
     
         16 . A method for recycling a platinum paste, comprising the steps of
 producing a platinum paste by mixing an organic component, which includes at least an organic solvent, with a metal powder recovered by the method defined in any of  claim 9 .   
     
     
         17 . The method for recovering a metal powder from a platinum paste according to  claim 13 , wherein the organic component includes a surfactant. 
     
     
         18 . The method for recovering a metal powder from a platinum paste according to  claim 14 , wherein the solid component comprises at least one of the group of alumina, zirconia, carbon powder or diamond. 
     
     
         19 . The method for recovering a metal powder from a platinum paste according to  claim 15 , wherein the preliminary heating is conducted for a period of between 5 minutes and 60 minutes. 
     
     
         20 . The method for recovering a metal powder from a platinum paste according to  claim 9 , wherein the platinum paste has a platinum concentration chosen from the group of (i) at least 99% platinum concentration by mass, or (ii) at least 40% platinum concentration by mass. 
     
     
         21 . The method for recovering a metal powder from a platinum paste according to  claim 20 , wherein the platinum paste comprises a platinum alloy comprising at least one additional metal chosen from the group of palladium, gold, silver, rhodium and iridium. 
     
     
         22 . The method for recovering a metal powder from a platinum paste according to  claim 9 , wherein the platinum paste has an average particle size of between 0.05 μm and 5 μm. 
     
     
         23 . The method for recovering a metal powder from a platinum paste according to  claim 9 , wherein the step of heating the platinum paste proceeds at a temperature elevation rate of between 5° C./minute and 20° C./minute. 
     
     
         24 . The method for recovering a metal powder from a platinum paste according to  claim 23 , wherein the step of heating the platinum paste includes a period during which the recovery temperature is held constant for between 5 minutes and 60 minutes. 
     
     
         25 . A method for recovering a metal powder from a platinum paste formed by mixing a solid component composed of a metal powder including at least a platinum powder or a platinum alloy powder and an organic component including at least an organic solvent, comprising the steps of
 heating the platinum paste to a recovery temperature between 300° C. and 500° C.,   removing the organic component, and   recovering the metal powder.   
     
     
         26 . A method for recycling a platinum paste, comprising the steps of
 producing a platinum paste by mixing an organic component with a metal powder, wherein the organic component includes at least an organic solvent,   heating the platinum paste to a recovery temperature between 300° C. and 500° C.,   removing the organic component, and   recovering the metal powder.