Coating compositions for plastic substrates

Abstract

The present invention provides radiation-curable compositions for coating plastic substrates, wherein the compositions, after cure, have a combination of sufficient adhesion, flexibility, and hardness. The compositions include: (a) at least one component comprised of a metal oxide bonded to an organic compound, said organic compound having (i) a radiation curable group; and (ii) a group represented by the following formula (1) wherein X represents an amine (NH), oxygen (O), or sulfur (S) radical; and Y represents an oxygen (O), or sulfur (S) radical; (b) a poly(meth)acrylate compound; and (c) an adhesion promoter.

1 . A curable composition for coating a plastic substrate, said composition comprising: 
 (a) at least one component comprised of a metal oxide bonded to an organic compound, said organic compound having 
 (i) a radiation curable group; and  
 (ii) a group represented by the following formula (1)  
                     
 wherein  
 X represents an amine (NH), oxygen (O), or sulfur (S) radical; and  
 Y represents an oxygen (O), or sulfur (S) radical;  
   (b) a poly(meth)acrylate compound; and    (c) an adhesion promoter;    wherein said composition, after cure, has 
 (a) sufficient adhesion to said plastic substrate;  
 (b) a pencil hardness of B or higher; and  
 (c) sufficient flexibility.  
   
     
     
         2 . The composition of  claim 1 , wherein said plastic substrate comprises at least one plastic selected from the group consisting of polynorbornene, polyethyleneterephtalate, polymethylmethacrylate, polycarbonate, polyethersulphone, polyimide, and polyethernaphtalene.  
     
     
         3 . The composition according to  claim 1 , wherein said plastic substrate comprises polynorbornene.  
     
     
         4 . The composition according to  claim 1 , wherein said metal oxide comprises at least one metal selected from the group consisting of silicon, aluminum, zirconium, titanium, zinc, germanium, indium, tin, antimony, and cerium.  
     
     
         5 . The composition according to  claim 1 , wherein said metal oxide is a silicon oxide.  
     
     
         6 . The composition according to  claim 1 , wherein said composition comprises, relative to the total weight of the composition, 20-95 wt % of said at least one component.  
     
     
         7 . The composition according to  claim 1 , wherein said composition comprises, relative to the total weight of the composition, at least 50 wt % of said at least one component.  
     
     
         8 . The composition according to  claim 1 , wherein said poly(meth)acrylate compound comprises at least three (meth)acrylate groups.  
     
     
         9 . The composition according to  claim 1 , wherein said composition comprises 5-25 wt %, relative to the total weight of the composition, of a poly(meth)acrylate comprising three (meth)acrylate groups.  
     
     
         10 . The composition according to  claim 1 , wherein said composition comprises at least two compounds having at least three (meth)acrylate groups.  
     
     
         11 . The composition according to  claim 1 , wherein said composition comprises an ethoxylated triacrylate.  
     
     
         12 . The composition according to  claim 1 , wherein said composition comprises a pentacrylate.  
     
     
         13 . The composition of  claim 12 , wherein said composition comprises 5-25 wt %, relative to the total weight of the composition, of said pentacrylate.  
     
     
         14 . The composition according to  claim 1 , wherein said adhesion promoter is selected from the group consisting of gamma-mercaptopropyl trimethoxysilane and methacryloxypropyl trimethoxy silane.  
     
     
         15 . The composition according to  claim 1 , wherein said composition comprises at least 3 wt %, relative to the total weight of the composition, of said adhesion promoter.  
     
     
         16 . The composition according to  claim 1 , wherein said composition comprises at least 5 wt %, relative to the total weight of the composition, of said adhesion promoter.  
     
     
         17 . The composition according to  claim 1 , wherein said poly(meth)acrylate compound comprises hydroxy groups and/or carboxylic groups.  
     
     
         18 . The composition according to  claim 1 , wherein said composition is absent epoxy-functional compounds.  
     
     
         19 . The composition according to  claim 1 , wherein the pencil hardness of the composition, after cure, is at least HB.  
     
     
         20 . The composition according to  claim 1 , wherein a 5-10 micron thick cured layer of said composition has a transparency of at least 65% for light having a wavelength of 400 mm.  
     
     
         21 . The composition according to  claim 1 , wherein the composition exhibits a flexibility such that less than 10 cracks are visible in a 5-10 micron thick cured layer of the composition when the composition is coated on said plastic substrate (length 20 cm, width 5 cm, and thickness 100 microns) and wound around a rod of 3.10 mm diameter with the plastic facing the surface of the rod and, consequently, the cured layer facing away from the rod.  
     
     
         22 . The composition according to  claim 1 , wherein the composition, after cure, has an adhesion value of at least 1 as measured according to ASTM D3359.  
     
     
         23 . An article comprising 
 (a) a substrate comprising at least one plastic selected from the group consisting of polynorbornene, polyethyleneterephtalate, polymethylmethacrylate, polycarbonate, polyethersulphone, polyimide, and polyethernaphtalene; and    (b) a coating on said substrate, said coating being obtained by curing the composition according to  claim 1 .    
     
     
         24 . The article of  claim 23 , wherein said substrate is corona treated.  
     
     
         25 . The article according to  claim 23 , wherein said article includes an optical display.  
     
     
         26 . The article according to  claim 23 , wherein said article includes a liquid crystal display or an organic light emitting diode display.  
     
     
         27 . The article according to  claim 23 , wherein said article includes an optical disc.  
     
     
         28 . A process for preparing a substantially flexible coating, said process comprising curing a composition according to  claim 1 .  
     
     
         29 . A display monitor comprising a plastic substrate coated at least in part with a coating formed by curing the composition according to  claim 1 .  
     
     
         30 . The display monitor of  claim 29  wherein an image is viewed through said coating.