Patent GB-1194410-A (GB)
Title: Chromatographic Films and preparation thereof
Inventor: WIETERS ERICH
IPC: G01N30/93
Filed: 1967-11-28
Abstract: 1,194,410. Chromatographic films. E. MERCK A.G. 28 Nov., 1967 [22 Dec., 1966], No. 54067/67. Heading B1X. A surface of a film is treated in preparation for the application thereto of a layer of chromatographic sorption material by a process which comprises sintering on the surface of the film a layer of a mixture of chromatographic sorption material and of a finely divided thermoplastic resin which is insoluble in organic solvents at ambient temperatures. The mixture may be applied to the surface of the film by dusting. Alternatively and preferably, the mixture is applied to the surface of the film from a dilute suspension thereof in a liquid or liquid mixture, for example water or methanol, ethanol, isopropanol or acetone, either alone or mixed with water; a suspension which contains water also may contain a wetting agent, for example a condensation product of ethylene oxide. Prior to sintering, the thermoplastic resin preferably is in the form of a fine powder, for example a powder having a maximum particle size of 30 microns. The mixture of chromatographic sorption material and thermoplastic resin and the subsequent sintered layer preferably each contain from 10% to 50% by weight of thermoplastic resin. Sintering is effected at a temperature preferably of not above 200‹C, for example of from 60‹C to 1180‹C, the temperature being so chosen that the resin is sintered but the film is not affected deleteriously. The film may be formed from a polyester, for example polyethylene terephthalate; the chromatographic sorption material may be silica gel, kieselguhr, aluminium oxide, magnesium silicate, a calcium phosphate or cellulose or a derivative thereof; the thermoplastic resin may be polyethylene, polypropylene or a polyamide, for example polycaprolactam. A layer of further chromatographic sorption material may be applied, for example by painting, immersion or rolling techniques, to the exposed surface of the sintered layer to provide chromatographic film; this further chromatographic sorption material advantageously is the same as the material used as a component of the layer which was sintered but also may contain an inorganic or organic fluorescence indicator and/or for example a reactive dye bound in cellulose and/or an adhesive and/or binding agent, examples of which agents are starch, gypsum, finely divided silica and alumina, montmorillonite, polyvinyl polymers containing carboxy groups and the salts thereof, and polymers and copolymers of acrylamide and methacrylamide either unsubstituted or mono- or di-substituted by lower alkyl groups at the amide nitrogen. As exemplified, polyester film is treated by depositing thereon from aqueous suspension and subsequently sintering thereon a layer of a mixture of polyethylene and a chromatographic sorption material which is silica gel (Example 1), aluminium oxide (Example 2). kieselguhr (Example 3) or microrystalline cellulose (Example 4); to the exposed surface of the sintered layer is applied a layer of silica gel (Example 1) or microcrystalline cellulose (Example 4) thereby to provide a chromatingraphic film.