Abstract
However, their present uses and possible future uses deserve consideration. Their tendency to thicken in certain solvents has been applied to use in imparting false body (thickening) to certain varnishes. In such cases it is likely that the rubber resin is modified to reduce tackiness before compounding it into quick-drying spirit varnishes. As plasticizers for brittle resins and asphalts they afford a very inexpensive raw material. But, again, experiments must be performed to see if the rubber resin is compatible with the natural or synthetic one, as there is little information as to whether plasticizers form solid solutions or only mechanical mixtures with the resins after heating and mixing. In one case a large shoe manufacturer purchased many tons of gutta-percha resin for impregnation of threads used in sewing on soles; the object was to prevent the entrance of moisture into the shoe and to supply a flexible adhesive. Electric friction tape, which must have an eversoft tacky surface, is coated with a compound of a bitumen, regenerated rubber, and a gutta resin, and is similar in composition to readily appliable insulation pastes, which are used on underground electric cables. The use in ever-soft adhesives and in flypaper are only two of the minor ones. The application of these resins to textiles in the form of emulsions shows large possibilities, as they can be emulsified with ammonium oleate or linoleate and, on drying, leave behind films of rubber resin and the fat acid of the emulsifier. A hardened balata resin has been used in linoleum cement. The soft resin or even the oily one can be hardened by heating for four hours at 80° C, after adding 1 per cent of manganese resinate or 0.5 per cent of calcium carbonate. Treatment of the same resin with sulfur chloride results in a viscous resin which, when warm, can be pulled out into ropes like taffy candy and, when cold, is still viscous. In closing, the writer wishes to state that, even if a reader may fail to find here the exact information he desires about a certain rubber resin, let it be hoped that what information he does find will save many hours of fruitless toil.
