Preparation of alkylimidazolidone (meth)acrylates in water
The invention relates to special (methyl)acrylaic monomers and concerns more particularly an enhanced process for preparing solutions of alkylimiozolidone (meth)acrylates in water solutions of alkylimidazolidone (meth)acrylates in a light (meth)acrylate.
1. A process for preparing solutions, in water, of an alkylimidazolidone (meth)acrylate of formula (I):
in which R 1 is a hydrogen atom or a methyl group and A and B represent, independently of one another, a straight-chain alkylene group or branched-chain alkylene group having from 2 to 5 carbon atoms,
from solutions of an alkylimidazolidone (meth)acrylate of formula (I) in a light (meth)acrylate of formula (II):
in which R 2 is a straight- or branched-chain alkyl group having from 1 to 4 carbon atoms, characterized in that it comprises the following steps:
(a) adding, to an initial solution of an alkylimidazolidone (meth)acrylate of formula (I), from 100 to 2000 ppm of at least one polymerization inhibitor, with the exception of 2,2,6,6-tetramethyl-1-piperidinyloxy derivatives;
(b) removing, by distillation under reduced pressure, from 75 to 95% by weight of the (meth)acrylate of formula (II) present in the initial solution;
(c) continuously adding water at the same time as the distillation is continued in order to remove the remaining (meth)acrylate of formula (II) in the form of a (meth)acrylate of formula (II)/water azeotrope; and
(d) bringing the mixture obtained in (c) back to atmospheric pressure and to ambient temperature and introducing an amount of water in order to adjust the water content of the final solution.
2. The process as claimed in claim 1 , characterized in that the compound of formula (I) is 1-ethyl-imidazolidyl-2-one methacrylate.
3. The process as claimed in claim 1 , characterized in that, in step (b), from 80 to 90% by weight of the (meth)acrylate of formula (II) present in the initial solution is distilled.
4. The process as claimed in claim 1 , characterized in that the amount of water added continuously in step (c) ranges from 10% to 50% expressed relative to the initial light (meth)acrylate.
5. The process as claimed in claim 1 , characterized in that the water content of the final solution is adjusted to 40% to 60%.