pH-regulated polyamide powder for cosmetic applications

Abstract

The present invention relates to polyamide powders suitable for cosmetic applications are described which have a pH of 4.0 to 7.0, cosmetic compositions containing the polyamide powders and processes of making the same.

1 . A polyamide powder, wherein the pH of the polyamide powder is from 4.0 to 7.0.  
     
     
         2 . The polyamide powder as claimed in  claim 1 , wherein the pH of the polyamide powder is from 4.5 to 6.5.  
     
     
         3 . The polyamide powder as claimed in  claim 1 , which has an average particle diameter of from 1 to 400 μm.  
     
     
         4 . The polyamide powder as claimed in  claim 1 , which is one or more of polyamide 11 and polyamide 12.  
     
     
         5 . The polyamide powder as claimed in  claim 1 , wherein the polyamide is obtained by a precipitation process or by an anionic solution polymerisation process.  
     
     
         6 . A method of making a polyamide powder, comprising adding a buffer system to a polyamide powder in amount sufficient to yield a polyamide powder with a pH of from 4.0 to 7.0.  
     
     
         7 . The method as claimed in  claim 6 , wherein the polyamide powder has a pH of from 4.5 to 6.5.  
     
     
         8 . The method as claimed in  claim 6 , wherein the buffer system comprises at least one of a natural organic acid, a natural mineral acid, and a corresponding salt thereof.  
     
     
         9 . The method as claimed in  claim 6 , wherein the buffer system comprises at least one of a citrate buffer and a phosphate buffer.  
     
     
         10 . The method as claimed in  claim 6 , wherein the buffer system is in an amount of from 0.001 to 10 parts of buffer per 100 parts of the polyamide powder.  
     
     
         11 . The method as claimed in  claim 6 , wherein the polyamide powder has an average particle diameter of from 1 to 400 μm.  
     
     
         12 . The method as claimed in  claim 6 , wherein the polyamide powder is one or more of polyamide 11 and polyamide 12.  
     
     
         13 . The method as claimed in  claim 6 , wherein the polyamide powder is obtained by a precipitation process or by an anionic solution polymerisation process.  
     
     
         14 . The method as claimed in  claim 6 , wherein the buffer system is mixed with a dry blend of polyamide powder.  
     
     
         15 . The method as claimed in  claim 6 , wherein the buffer system is sprayed in solution onto the polyamide powder and then the polyamide powder is dried.  
     
     
         16 . A cosmetic composition comprising a polyamide powder suitable for cosmetic applications, wherein the pH of the polyamide powder is from 4.0 to 7.0; and a carrier.  
     
     
         17 . The cosmetic composition as claimed in  claim 16 , wherein the pH of the polyamide powder is from 4.5 to 6.5.  
     
     
         18 . The cosmetic composition as claimed in  claim 16 , which has an average particle diameter of from 1 to 400 μm.  
     
     
         19 . The cosmetic composition as claimed in  claim 16 , which is one or more of polyamide 11 and polyamide 12.  
     
     
         20 . The cosmetic composition as claimed in  claim 16 , wherein the polyamide is obtained by a precipitation process or by an anionic solution polymerisation process.