Method for producing layered materials using long-lived photo-induced active centers

Abstract

The invention relates to a method for applying a photo-activated layered polymer coating to a substrate material in which one or more layers do not contain photoinitiator, or are not exposed to initiating light, but cure due to migration of cationic active centers. At least two separate monomer layers are applied to the substrate material. At least one of the monomer layers includes a photoinitiator capable of producing cationic active centers. The at least one layer including the photoinitiator is exposed to a source of UV radiation at a desired wavelength forming cationic active centers. The at least two separate monomer layers react in a polymerization reaction forming a cured layered material. The cationic active centers of the exposed monomer layer migrate to the unexposed layer such that both layers cure via the polymerization reaction.

1 . A method of forming a layered material on a substrate comprising the steps of:
 providing a substrate material;   applying at least two separate monomer layers to the substrate material, at least one of the monomer layers including a photoinitiator capable of producing cationic active centers;   exposing only the at least one layer including the photoinitiator to a source of UV radiation at a desired wavelength forming cationic active centers;   wherein the at least two separate monomer layers react in a polymerization reaction forming a cured layered material.   
     
     
         2 . The method of  claim 1  wherein the cationic active centers of the exposed monomer layer migrate to the unexposed layer wherein both layers cure via a polymerization reaction. 
     
     
         3 . The method of  claim 1  including the step of applying a first of the at least two monomer layers to the substrate material, the first monomer layer including the photoinitiator. 
     
     
         4 . The method of  claim 3  including exposing the first monomer layer to the source of UV radiation, curing the first monomer layer. 
     
     
         5 . The method of  claim 4  including the step of applying a second monomer layer to the cured first layer wherein the second layer cures with no further exposure to UV radiation. 
     
     
         6 . The method of  claim 1  including the step of applying a first of the at least two monomer layers to the substrate material. 
     
     
         7 . The method of  claim 4  including the step of applying a second monomer layer to the first layer wherein the second layer the first monomer layer includes the photoinitiator. 
     
     
         8 . The method of  claim 7  including exposing the second monomer layer to the source of UV radiation, curing the first and second monomer layers without exposing the first monomer layer to UV radiation. 
     
     
         9 . The method of  claim 1  including adding a plurality of monomer layers to the substrate material at least one of the plurality of layers including a photoinitiator, wherein the at least one layer including the photoinitiator is exposed to a source of UV radiation at a desired wavelength and all the separate monomer layers react in a polymerization reaction forming a cured layered material. 
     
     
         10 . The method of  claim 1  wherein at least one of the layers includes a pigment. 
     
     
         11 . The method of  claim 10  wherein the at least one layer including the photoinitiator includes the pigment. 
     
     
         12 . The method of  claim 1  wherein the substrate includes steel having an electro-coated layer applied thereon. 
     
     
         13 . The method of  claim 1  including the step of applying a first base coat layer to the substrate. 
     
     
         14 . The method of  claim 13  including the step of applying a clear coat layer to the base coat layer, the clear coat including the photoinitiator. 
     
     
         15 . The method of  claim 14  including the step of exposing the clear coat layer to UV at a desired wavelength when both the clear coat layer and base coat layer are cured in a polymerization reaction. 
     
     
         16 . The method of  claim 1  wherein the monomer layers are selected from:
 monofunctional or difunctional epoxides, high molecular weight epoxy oligomers and resins, cyclic sulphides, vinyl ethers, cyclic ethers, cyclic formals and acetals, lactones, or siloxanes. 
 
     
     
         17 . The method of  claim 1  wherein the monomer layers have a thickness of from 5 to 150 micrometers. 
     
     
         18 . The method of  claim 1  wherein the photoinitiator is selected from the group consisting of: diazonium salts, diaryliodonium salts, triarylsulphonium salts, dialkylphenacyl-sulfonium salts, ferrocenium salts, α-sulphonyloxy ketones, or silyl benzyl ethers. 
     
     
         19 . The method of  claim 1  wherein the photoinitiator is present in an amount of about 0.5 to 6 weight percent relative to the monomer. 
     
     
         20 . A method of forming a layered material on a substrate comprising the steps of:
 providing a substrate material;   applying a first base coat layer to the substrate material;   applying a second clear coat layer to the base coat layer, the clear coat layer including a photoinitiator capable of producing cationic active centers;   exposing the clear coat layer to a source of IN radiation at a desired wavelength forming cationic active centers;   wherein the base coat and clear coat layers react in a polymerization reaction forming a cured layered material.   
     
     
         21 . A method of forming a layered material on a substrate comprising the steps of:
 providing a substrate material;   applying a plurality of monomer layers to the substrate material, at least one of the plurality of layers including a photoinitiator capable of producing cationic active centers;   exposing the layer including the photoinitiator to a source of UV radiation at a desired wavelength forming cationic active centers;   applying additional monomer layers to the exposed layer wherein the plurality of layers react in a polymerization reaction forming a cured layered material.