The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 12, 1985
Filed:
Mar. 19, 1984
Werner Preiswerk, Binningen, CH;
Beat Bruttel, Bockten, CH;
Ciba Geigy Corporation, Ardsley, NY (US);
Abstract
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 .ANG.. 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.