Patent ID: 6803020
Filing Date: 2004-10-12
Classification: C08F,G01N

Abstract:
A process for the preparation of a latex with predefined properties by emulsion (co)polymerization of at least one ethylenically unsaturated monomer, wherein the process is carried out with continuous in situ monitoring of the (co)polymerization comprising the following stages:(i) emitting incident light radiation within the spectral band situated between 200 nm and 1 400 nm, into the emulsion, (ii) picking up the light scattered by the reaction medium and transmitting it to a Raman spectrometer, (iii) determining the Raman spectrum, which shows the energy of the scattered light as a function of the difference in wavelength with respect to the incident light radiation, (iv) a) by either the intensities (areas or heights) of specific lines of the spectrum: of un(co)polymerized free monomer(s) in the reaction medium, and of the polymer obtained, b) or the concentrations of un(co)polymerized free monomer(s) in the reaction medium and of the polymer obtained are calculated from the Raman spectrum using quantitative spectral analytical methods; (v) calculating the process data either from the concentrations of free monomer(s) and of the polymer obtained or from the intensities (areas or heights) of specific lines of the spectrum of free monomer(s) in the reaction medium and from the intensities (areas or heights) of specific lines of the spectrum of the polymer obtained; (vi) comparing these process data with reference data specific to the process for the production of the latex with the predefined properties; (vii) and adjusting the reaction parameters, comprising the pressure, the stirring of the medium and the feeding with monomers, in order to minimize the difference between the process data measured in-line and the reference process data.