GB1234839A - Process for hardening colloid layers in photographic material - Google Patents

Abstract

1,234,839. Hardening layer-forming materials for photographic purposes. CIBA-GEIGY A. G. Aug.14, 1968 [Aug.22, 1967], No.38856/68. Heading G2C. Photographic colloid layers in photographic materials are hardened by incorporating in the casting solution for at least one of said layers (a) a slowly after-hardening agent and (b) a rapidly hardening agent the hardening action of which declines on storage. The hardeners (a) are preferably derived from two classes of hardeners; (a 1 ) a colourless halo 1, 3, 5-triazine compound which contains at least one acid group conferring solubility in water, examples of which compounds are disclosed, or (a 2 ) a compound which is at most slightly coloured which contains at least one sulphonic acid group and two α-halogenacrylamide residues. The rapidhardening agents of class (b) exemplified are N, #-chloro-propionyl N<SP>1</SP> -acryloylurea, N-acryloyl 2, 3-epoxypropyl carbamate, N, #-chloropropionyl 2, 3-epoxypropyl carbamate, N, #-chloropropionyl N<SP>1</SP>, N -ethylene urea, N, #-chloropropionyl formylmethyl carbamate and N, N<SP>1</SP> -bis-acryloyl urea. The layer-forming materials which are hardened may be polyvinyl alcohol, polyvinyl pynolidone and especially gelatine. The hardeners may, before drying, diffuse from one layer into another layer of a multi-layer casting, and hence all the layers of a multi-layer casting may be hardened by adding a hardener mixture only to some of the layers or by adding one hardener to some of the layers and another hardener to other layers.