Radiation diffraction colorants

Abstract

A radiation diffraction material comprising an ordered periodic array of particles held in a polymeric matrix is disclosed; the particles each comprise a core surrounded by a shell of a non-film forming composition that is different from the matrix. Methods for using the material are also disclosed.

1 . A radiation diffractive material, comprising:
 an ordered periodic array of particles packed adjacent to each other, said array defining interstitial spaces between adjacent particles, said particles each comprising a core surrounded by a non-film forming shell; and   a matrix composition interpenetrated into the interstitial spaces in the array and cured therein.   
     
     
         2 . The radiation diffraction material of  claim 1 , wherein the refractive index of said core is different from the refractive index of said shell. 
     
     
         3 . The radiation diffraction material of  claim 2 , wherein said shell has a gradient of refractive index across the thickness of said shell. 
     
     
         4 . The radiation diffraction material of  claim 1 , wherein said matrix and said shell each comprise a polymeric material different from each other, wherein the polymeric material comprises a polystyrene, a polyurethane, an acrylic polymer, an alkyd polymer, a polyester, a siloxane-containing polymer, a polysulfide, an epoxy-containing polymer and/or a polymer derived from an epoxy-containing polymer. 
     
     
         5 . The radiation diffraction material of  claim 4 , wherein said shell is swellable by monomers of said matrix polymer and said core is substantially non-swellable. 
     
     
         6 . The radiation diffraction material of  claim 2 , wherein said particle core comprises a polymeric material comprising a polystyrene, a polyurethane, an acrylic polymer, an alkyd polymer, a polyester, a siloxane-containing polymer, a polysulfide, an epoxy-containing polymer, a polymer derived from an epoxy-containing polymer, a metal oxide and/or an inorganic polymer. 
     
     
         7 . The radiation diffraction material of  claim 1 , wherein the diameter of said core is 80 to 90 percent of the total particle diameter. 
     
     
         8 . The radiation diffraction material of  claim 1 , wherein the radiation diffraction material is in the form of a sheet. 
     
     
         9 . The radiation diffraction material of  claim 1 , wherein the radiation diffraction material is in particulate form. 
     
     
         10 . A method of producing a radiation diffractive material comprising:
 applying a dispersion of particles onto a substrate, the particles each comprising a core surrounded by a non-film forming shell;   packing the particles adjacent to each other in an ordered periodic array that diffracts radiation, such that the array defines interstitial spaces between adjacent particles;   filling the interstitial spaces in the array of particles with a curable matrix composition;   swelling the shells by diffusing components of the matrix composition into the shells; and   curing the matrix composition.   
     
     
         11 . The method of  claim 10 , wherein the diffusing components comprises crosslinkable monomers. 
     
     
         12 . The method of  claim 10 , wherein the diffusing components comprises solvent. 
     
     
         13 . The method of  claim 10 , wherein said swelling step produces a gradient of refractive index through the thickness of the shell. 
     
     
         14 . The method of  claim 10 , wherein said swelling step further comprises identifying the diffraction wavelength of the array and adjusting the degree of swelling of the shells to achieve a desired diffraction wavelength of the array. 
     
     
         15 . The method of  claim 10 , further comprising removing the radiation diffractive material from the substrate.