PROCESS FOR INHIBITING THE GELATINISING OF CONCENTRATED AQUEOUS PHOTOACTIVATOR SOLUTIONS

摘要

The invention relates to a process for preventing the gelation of concentrated aqueous photoactivator solutions containing sulfonated zinc or aluminium phthalocyanines. The process comprises passing a crude solution containing these compounds, when preparing the solutions, through a semipermeable asymmetrical membrane having a pore diameter of 1 to 500 ANGSTROM . This membrane consists of a basic structure of cellulose acetate, polyacrylonitrile or a copolymer of acrylonitrile and other ethylenically unsaturated monomers. This basic structure is modified in specific manner with ionic groups. The concentrated photoactivator solutions so obtained have excellent storage stability, do not gel, and contain exceedingly small amounts of inorganic and organic impurities.