PROCESS FOR PREPARING PHOTOGRAPHIC GELATIN Russian patent published in 1994 - IPC

FIELD: chemical and photographic industry. SUBSTANCE: a gelatin solution is concentrated after filtration by an ultrafiltration method through membranes made of aromatic polysulfonamide having a water permeability coefficient of dm³m²h·MPa or of fluoroplastic having a water permeability coefficient of 500-2500 dm³m²h·MPa. The retaining power of said membranes of the gelatin fragments is 20,000-100,000 D. The ultrafiltration gives two semiproducts, namely an ultraconcentrate having a gelatin concentration of 10-20% (this product is directed for gelatinization and convective drying), and a permeated having gelatin concentration not greater than 2.5%. If the concentration is not greater 0,5%, the permeate is utilized or used for cooking food or industrial gelatin. If the gelatin concentration is 0.5-2.5, the permeate is mixed with food or industrial gelatin solutions and directed for evaporation. EFFECT: improved properties of the photographic gelatin. 7 cl, 5 tbl