Styrene Maleic Anhydride Polymers in Cosmetics and Personal Care Products

Abstract

The invention relates generally to pigmented compositions that, upon the application of water and pressure, exhibit a visible change in one or more optical attributes such as color.

What is claimed: 
     
         1 . A method for preparing a pigment grind capable of exhibiting a color change comprising dispersing, under shear, pigment particulates in a substantially anhydrous carrier in the presence of a styrene maleic anhydride copolymer. 
     
     
         2 . The method according to  claim 1 , wherein said pigment grind comprises: from about 20% to about 80% by weight carrier, from about 20% to about 80% by weight pigment, and from about 0.5% to about 20% by weight styrene-maleic anhydride copolymer. 
     
     
         3 . The method according to  claim 2 , wherein said carrier is anhydrous and comprises oil. 
     
     
         4 . The method according to  claim 2 , wherein said carrier comprises castor oil. 
     
     
         5 . The method according to  claim 2 , wherein said pigment comprises one or more of titanium dioxide, iron oxide, FD & C lakes, D & C lakes, and carbon black. 
     
     
         6 . The method according to  claim 2 , wherein said pigment comprises iron oxide. 
     
     
         7 . The method according to  claim 2 , wherein said styrene maleic anhydride copolymer is composed of from about 25% to about 50% maleic anhydride monomers and from about 50% to about 75% styrene monomers. 
     
     
         8 . The method according to  claim 7 , wherein said styrene maleic anhydride copolymer comprises the following repeat unit: 
       
         
           
           
               
               
           
         
         wherein, X is selected from —O—, —NH—, or —NR*—, where R* is a C 1-12  hydrocarbon optionally containing from 1-3 heteroatoms selected from oxygen, sulfur, and nitrogen, and “n” and “m” are each independently integers selected to provide a molecular weight between about 2,500 and about 80,000 Daltons. 
       
     
     
         9 . The method according to  claim 8 , wherein said styrene-maleic anhydride copolymer comprises an alternating copolymer. 
     
     
         10 . The method according to  claim 7 , wherein “n” and “m” are each independently integers selected to provide a molecular weight between about 5,000 and about 10,000 Daltons. 
     
     
         11 . The method according to  claim 7 , wherein said styrene-maleic anhydride copolymer comprises the following repeat unit: 
       
         
           
           
               
               
           
         
         wherein, X 1  and X 2  are independently selected from —OH, —OZ, —OR —NH 2 , and —NHR*, wherein R and R* are independently a C 1-12  hydrocarbon optionally containing from 1-3 heteroatoms selected from oxygen, sulfur, and nitrogen, and Z is a cation selected from Na +  and NH 4   + , where “n” and “m” are each independently integers selected to provide a molecular weight between about 2,500 and about 80,000 Daltons. 
       
     
     
         12 . The method according to  claim 11  wherein one of X 1  or X 2  is a group —NH 2  and the other of X 1  or X 2  is —OH. 
     
     
         13 . The method according to  claim 11 , wherein said styrene-maleic anhydride copolymer comprises alternating copolymer. 
     
     
         14 . The method according to  claim 11 , wherein “n” and “m” are each independently integers selected to provide a molecular weight between about 5,000 and about 10,000 Daltons. 
     
     
         15 . The method according to  claim 1 , wherein said shear is applied in a three-roll mill. 
     
     
         16 . A pigment grind capable of exhibiting a color change prepared according to the method of any of  claims 1 . 
     
     
         17 . A cosmetic composition capable of changing color comprising:
 one or more cosmetic ingredient selected from waxes, gelling agents, emollients, and film forming polymers; and   a pigment grind comprising pigment particulates in a carrier and a styrene-maleic anhydride copolymer;   wherein said cosmetic composition is substantially anhydrous.   
     
     
         18 . A method of achieving a color change in a cosmetic composition applied to a human integument comprising:
 (1) applying to said human integument a substantially anhydrous cosmetic composition to form a film thereon, wherein said composition comprises:
 (a) one or more cosmetic ingredient selected from waxes, gelling agents, emollients, and film forming polymers; and 
 (b) a pigment grind capable of exhibiting a color change according to  claim 16 ; and 
   (2) applying water to said film and rubbing it until a visible color change is achieved.