Uv-reflecting compositions

Abstract

A composition containing polymeric particles. The polymeric particles have an average particle diameter from 30 to 300 nm, at least 95 wt % polymerized residues of styrenic monomers and from 0 to 5 wt % polymerized residues of acid monomers. The composition also contains a film-forming polymer having T g no greater than 80° C. and comprising from 40 to 65 wt % polymerized residues of C 4 -C 10 alkyl acrylates and 35 to 60 wt % polymerized residues of C 1 -C 4 alkyl(meth)acrylates. The refractive index difference between the polymeric particles and the film-forming polymer is at least 0.04.

1 . A composition comprising polymeric particles having: (a) an average particle diameter from 30 to 300 nm; and (b) at least 95 wt % polymerized residues of styrenic monomers and from 0 to 5 wt % polymerized residues of acid monomers; and a film-forming polymer having T g  no greater than 80° C. and comprising from 40 to 65 wt % polymerized residues of C 4 -C 10  alkyl acrylates and 35 to 60 wt % polymerized residues of C 1 -C 4  alkyl (meth)acrylates; wherein a refractive index difference between the polymeric particles and the film-forming polymer is at least 0.04. 
     
     
         2 . The composition of  claim 1  in which the refractive index difference between the polymeric particles and the film-forming polymer is at least 0.08. 
     
     
         3 . The composition of  claim 2  in which the film-forming polymer comprises from 45 to 65 wt % polymerized residues of C 4 -C 10  alkyl acrylates and 35 to 55 wt % polymerized residues of at least one of methyl methacrylate and ethyl methacrylate. 
     
     
         4 . The composition of  claim 3  in which the average particle diameter is from 70 to 260 nm. 
     
     
         5 . The composition of  claim 4  in which the refractive index difference between the polymeric particles and the film-forming polymer is at least 0.105. 
     
     
         6 . A film comprising polymeric particles having: (a) an average particle diameter from 30 to 300 nm; (b) at least 95 wt % polymerized residues of styrenic monomers and from 0 to 5 wt % polymerized residues of acid monomers; and a continuous polymeric phase having T g  no greater than 80° C. and comprising from 40 to 65 wt % polymerized residues of C 4 -C 10  alkyl acrylates and 35 to 60 wt % polymerized residues of C 1 -C 4  alkyl(meth)acrylates; wherein a refractive index difference between the polymeric particles and the continuous polymeric phase is at least 0.04; and wherein an average distance between the polymeric particles is from 35 to 400 nm. 
     
     
         7 . The film of  claim 6  in which the refractive index difference between the polymeric particles and the continuous polymeric phase is at least 0.08 and the average particle diameter is from 70 to 200 nm. 
     
     
         8 . The film of  claim 7  in which the average distance between the polymeric particles is from 50 to 200 nm. 
     
     
         9 . The film of  claim 8  in which the continuous polymeric phase comprises from 45 to 65 wt % polymerized residues of C 4 -C 10  alkyl acrylates and 35 to 55 wt % polymerized residues of at least one of methyl methacrylate and ethyl methacrylate. 
     
     
         10 . The film of  claim 9  in which refractive index difference between the polymeric particles and the continuous polymeric phase is at least 0.11.