Method for manufacturing metal powder

Patent metadata

Field	Value
Publication number	US-10130995-B2
Application number	US-201515302712-A
Country	US
Kind code	B2
Filing date	Apr 10, 2015
Priority date	Apr 23, 2014
Publication date	Nov 20, 2018
Grant date	Nov 20, 2018

Abstract

A method for manufacturing metal powder comprising:
providing a basic metal salt solution; contacting the basic metal salt solution with a reducing agent to precipitate metal powder therefrom; and recovering precipitated metal powder from the solvent.

First claim

The invention claimed is:

1. A method for manufacturing silver powder comprising: providing a basic silver salt solution;
contacting the basic silver salt solution, the basic silver salt solution comprising a silver salt and a solvent, with a reducing agent comprising one or more of hydrazine, formaldehyde and borohydride to precipitate silver powder therefrom;
contacting the basic silver salt solution with a first capping agent after contacting the basic silver salt solution with the reducing agent; and recovering precipitated silver powder from the solvent;
and milling the recovered precipitated silver powder for at least 30 minutes in the presence of a second capping agent using a ball mill,
wherein the silver powder has a d50 of from 500 nm to 10 μm, and a tap density of greater than 2 g/cm 3 , wherein the first capping agent comprises one or more of lauric acid, palmitic acid, stearic acid, iso-stearic acid and oleic acid.

2. The method of claim 1 , wherein the reducing agent comprises hydrazine and borohydride.

3. The method of claim 1 , wherein the second capping agent comprises one or more of lauric acid, palmitic acid, stearic acid, iso-stearic acid, and oleic acid.

4. The method of claim 1 , wherein the milling is carried out for at least 90 minutes.

5. The method of claim 1 , further comprising the step of
combining the silver powder with a binder and a solvent, and optionally one or more of a rheology modifier, an organosilver compound, an activator, and a peroxide.

6. The method of claim 1 , wherein the second capping agent comprises a polymer, said polymer comprising PEG 400.

7. The method of claim 1 , wherein the second capping agent comprises a polyamine, said polyamine comprising triethylenetetramine.

8. A method of manufacturing a copper powder comprising: providing a basic copper salt solution, the basic copper salt solution comprising a copper salt and a solvent; contacting the basic copper salt solution with a reducing agent comprising one or more of hydrazine, formaldehyde, and borohydride to precipitate copper powder therefrom; contacting the basic copper salt solution with a capping agent after contacting the basic copper salt solution with the reducing agent; recovering precipitated copper powder from the solvent; and milling the recovered precipitated copper powder for at least 30 minutes in the presence of a polymer or a polvamine using a ball mill, wherein the copper powder has a d50 of from 500 nm to 10 μm, and a tap density of greater than 2 g/cm 3 .

9. The method of claim 8 , further comprising the step of applying a silver coating to the copper particles forming the powder.

10. The method of claim 8 , wherein the milling is carried out for at least 90 minutes.

11. The method of claim 9 , wherein applying the silver coating comprises:
etching an oxide layer from the copper particles; and
applying a silver coating to the copper particles using galvanic plating.

12. The method of claim 9 , further comprising applying a fatty acid coating to the silver coated particles.

Assignees

• Alpha Assembly Solutions Inc

Inventors

• Chaki Nirmalya Kumar
• Roy Poulami Sengupta
• Sarkar Siuli
• Mukherjee Sutapa

Classifications

• C01P2004/20

  extending in two dimensions, e.g. plate-like · CPC title

• C01P2006/12

  Surface area · CPC title

• C01P2006/11

  Powder tap density · CPC title

• C09C1/62

  Metallic pigments or fillers {(C09C1/0015 takes precedence)} · CPC title

• C09C1/622

  Comminution, shaping or abrasion of initially uncoated particles, possibly in presence of grinding aids, abrasives or chemical treating or coating agents; Particle solidification from melted or vaporised metal; Classification · CPC title