The present invention relates generally to apparatus for the application of adhesives or solvents to the surfaces of thermoplastic materials to be bonded together, one to the other, and more particularly to apparatus for the spray application of adhesives, either as film forming materials held in a solvent solution or as solvents per se to surfaces of thermoplastic materials, such as polystyrene in either sheet or foamed form, with the spray application being controlled within a spray enclosure, and being controllably applied to surfaces of the workpieces to be bonded. The present apparatus is particularly adapted for use in connection with solvent bonding of polystyrene, including foamed polystyrene, and particularly wherein solvents such as trichloroethylene or other more dangerous solvents may be employed, and wherein the atmosphere from the spray enclosure is controllably monitored so as to avoid contamination of the work area, and also to avoid pollution of the environment.
Solvent bonding of workpieces such as surfaces of typical thermoplastic articles including such articles in sheet form, complex shaped articles such as vacuum-formed articles or molded articles, and including solid as well as foamed thermoplastics has been known and highly utilized in the past. Typically, the surfaces to be bonded are treated with an application of adhesive in a solvent solution or a solvent per se so that the surfaces of the workpiece portions may be bonded together in face-to-face relationship. The means of solvent and adhesive application including spray application, brush application, dipping and the like. Typically too, and in solvent application operations, solvent has been applied without regard to the quantity of solvent employed, the manner of disposing of the solvent, or the manner in which the environment is protected from contamination due to the inevitable vaporization or volatilization of the solvent.
Solvent bonding of foamed articles has generally been regarded as an extremely difficult or, in some instances, an impossible operation. However, in accordance with the aspects of the present invention, it has been found possible to bond foamed polystyrene workpieces together without adversely affecting the quality of the product and with a firm bond created. Such operations are made possible in accordance with the various aspects of the present invention.