Photocuring of radiation-curable compositions under inert gas

Abstract

A process is described for producing molding compounds and coatings on substrates by curing radiation-curable compositions under inert gas by exposure to light wherein said inert gas comprises a gas heavier than air, and lateral escape of the inert gas in the course of radiation curing is prevented by means of appropriate apparatus or other measures.

1 - 16 . (canceled)  
   
   
       17 . A process for coating a substrate with a radiation-curable composition, comprising: 
 coating the substrate with the radiation-curable composition,    introducing carbon dioxide gas into a dip tank to force air upwardly out of the dip tank and form a carbon dioxide-containing atmosphere in the dip tank,    placing the substrate coated with the radiation-curable composition in the carbon dioxide gas-containing atmosphere in the dip tank, and    exposing the substrate in the dip tank to light to cure the radiation-curable composition.    
   
   
       18 . The process of  claim 17 , wherein the dip tank prevents lateral escape of carbon dioxide gas.  
   
   
       19 . The process of  claim 17 , wherein the carbon dioxide gas-containing atmosphere surrounds the substrate at a distance of up to 10 cm from the surface of the substrate and wherein the carbon dioxide gas-containing atmosphere inside the dip tank contains less than 15% by weight of oxygen gas based on the total amount of gas.  
   
   
       20 . The process as claimed in  claim 17 , wherein the carbon dioxide gas-containing atmosphere in the dip tank comprises oxygen in an amount of 1% by weight or less.  
   
   
       21 . The process of  claim 17 , wherein the carbon dioxide gas-containing atmosphere in the dip tank comprises oxygen in an amount of 0.1% by weight or less.  
   
   
       22 . The process of  claim 17 , wherein introducing carbon dioxide into the dip tank includes: 
 placing dry ice in the dip tank to force air upwardly out of the dip tank, and    evaporating the dry ice to form the carbon dioxide gas-containing atmosphere in the dip tank.    
   
   
       23 . The process of  claim 17 , wherein the carbon dioxide gas is introduced into the enclosed environment from gas bottles.  
   
   
       24 . The process of  claim 17 , wherein the radiation-curable composition comprises from 0.001 to 12 mol of radiation-curable ethylenically unsaturated groups per 1,000 gm of one or more radiation-curable compounds present in the radiation-curable composition.  
   
   
       25 . The process of  claim 24 , wherein at least 60 mol % of the radiation-curable ethylenically unsaturated groups are (meth) acrylic groups.  
   
   
       26 . The process as claimed in  claim 17 , wherein the radiation-curable composition comprises less than 10 parts by weight of a photoinitiator per 100 parts by weight of the total amount of the radiation-curable composition.  
   
   
       27 . The process as claimed in  claim 17 , wherein the light has a wavelength above 300 nm.  
   
   
       28 . The process of  claim 17 , wherein the light is from one or more selected from the group consisting of sunlight, a halogen lamp, an incandescent lamp, a light emitting diode and a laser.  
   
   
       29 . The process as claimed in  claim 17 , wherein the substrate is at least one selected from the group consisting of a motor vehicle, a road vehicle, a rail vehicle, an aircraft, a motor vehicle body and a motor vehicle part.  
   
   
       30 . The process as claimed in  claim 17 , wherein the substrate is made of one or more selected from the group consisting of wood, plastic, metal, a mineral material and ceramic.  
   
   
       31 . The process as claimed in  claim 17 , wherein the substrate is at least one of a composite material or a molding for stereolithography.  
   
   
       32 . The process as claimed in  claim 17 , wherein the substrate is three-dimensional.