The Use of Rubber in Paint Vehicles

Abstract

Abstract The fact that raw rubber swells and eventually dissolves with stirring in a number of solvents to yield a viscous, sticky solution naturally led to attempts to utilize this material for the preparation of paints and for the manufacture of adhesive and calking compounds like marine glue. It must be remembered that the raw rubber of the early days was not usually Hevea, but of lower grade containing much resin, and perished or deteriorated hydrocarbon, so that the product in a solvent was more sticky and less viscous than that which we should have in mind today. But whatever the grade, the viscosity of rubber solutions is a disadvantage, and has proved the main obstacle to the utilization of rubber in paints today. Apart from this drawback, quite a number of those technologists who experimented with rubber in paints were too optimistic as to the improvement likely to result. To many the word rubber sums up a material of “elastic” properties; and having great resistance to penetration by moisture and aqueous reagents generally, all desirable properties for a paint film; hence a proportion of rubber might be expected to impart added elasticity and impermeability. Such, however, is not the case. Complete incorporation of rubber to produce a homogeneous film is necessary to provide increased elasticity, while on the other hand rubber is not water-resistant unless vulcanized, and as vulcanization renders the rubber insoluble it cannot be used in this form. The prevalent idea that if a film of raw rubber were applied to a surface in the same manner as paint it should yield a moisture-proof coating is entirely erroneous, that is, using the word paint in the ordinary sense. it is possible to utilize rubber in this manner by compounding a solution of latex and applying the mixture to the surface to be coated, subsequently heating sufficiently to vulcanize, preferably to the ebonite state. By such means a water-resisting layer is obtained, but the process is only adaptable in special circumstances, and the materials are not of the class of paint which is now being considered.