Patent ID: 6528606
Filing Date: 2003-03-04
Classification: C08F,C08G

Abstract:
A method of preparing a stable composition of radically copolymerisable monomers, said composition containing firstly at least one monomer which has at least one urea function in its formula and secondly at least one monomer which does not have an isocyanate function in its formula, said method comprising:preparing said monomer(s) having urea function(s) by reaction of two types of reagents: at least one radically copolymerisable monomer which has at least one isocyanate function in its formula and at least one amine selected from primary and secondary amines; and incorporating said monomer(s) which does(do) not have an isocyanate function in its(their) formula, prior to said reaction, together with one of said reagents before adding the other of said reagents, during the addition of said reagents, and/or after said reaction, wherein said reaction of preparing said monomer(s) having urea function(s) is carried out in the absence of non-radially polymerisable solvent and wherein said monomer(s) having isocyanate function(s) and said amine(s) are incorporated in relative proportions such that the isocyanate equivalent/amine equivalent ratio is between 0.98 and 1.02; wherein said monomer(s) having urea function(s) thus obtained at the end of said reaction is(are) maintained diluted in the solvent which is constituted of said monomer(s) which does(do) not have an isocyanate function in its(their) formula, in the presence of dissolved oxygen; and wherein said reaction is carried out in the absence of oxygen dissolved in the reaction mixture and wherein a bubbling of gas is carried out at the end of said reaction in order to dissolve oxygen within said monomers having urea function(s).