GB319038A - Improvements in gramophone records and methods of manufacture thereof - Google Patents

Abstract

319,038. Thornton, J. E. June 12, 1928. Coated fabrics.-Light, flexible, and unbreakable gramophone records are made. by impressing sound-grooves into a layer of chemically hardened glue or gelatine, which may be applied to a core or base of any suitable material, such as one or more sheets of paper. The colloid layer is applied to the base by flowing it on as a solution. An adhesive substratum is applied to the base or core before the colloidal face layer or layers are superposed thereon. A suitable adhesive mixture consists of a solution of glue in water, with the addition of alum as a hardener; for the record-receiving layer, a similar mixture, but with a greater proportion of glue (or gelatine) and with the addition of molasses, glycerine, or sugar as a flexing agent, is used. Suitable proportions of the. ingredients are specified in each case. The hardening is allowed to proceed for a long time before the sound-grooves are produced by means of a matrix, under heat and pressure or by pressure alone. The hardening agent, which may consist of chrome or potash alum, or of formalin, instead of being mixed with the colloid solution may be applied by absorption from a solution into the colloid layers before the latter begin to dry, or after drying, in which case further drying is necessary. Alternatively tbe colloid may be exposed to formalin vapour in a closed room. The flexing agent and the hardening agent may be combined in one bath, or applied separately. Several successive coatings may be applied, both for the adhesive substratum and the recordreceiving layers. The. material may be made in sheets, or as a continuous web which is afterwards cut up. One or both sides of a single sheet of paper may be coated with the celluloid layer; or two sheets may be cemented back to back before grooves are impressed on both outer sides simultaneously.