Photographic matt layers or surfaces
US4235959A · kind A · utility
Inventors
Key dates
| Filing date | Feb 2, 1979 |
| Grant date | Nov 25, 1980 |
| Priority date | — |
| Expiry date | Feb 2, 1999 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S430/162
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
Hydrophilic coating compositions are made comprising a protective colloid and dispersed therein a matting agent. The matting agent is obtained by mixing in aqueous medium area, formaldehyde and an aqueous colloidal dispersion of silica. The mixture is buffered to keep the pH at 3.2 or lower. Urea and formaldehyde are polycondensed while vigorously stirring until particles comprising urea-formaldehyde resin and silica are formed of average particle size of 1-8 .mu.m. The rate of stirring is reduced and the pH is raised to 5 or higher to prevent afterpolycondensation and agglomeration of the polymer particles. A hydrophilic colloid is then dissolved in the reaction mixture. Photographic light-sensitive silver halide material incorporating a layer formed from the hydrophilic coating composition.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.