Improvements in and relating to closure means and seals for bottles, cans and other like containers

Abstract

Abstract Closures and closure protectors or seals are made of a thermoplastic resinous composition having a vinyl resin as a base which is in a state of internal strain so that upon application of heat, or other treatment such as the application of solvents or softeners, the strain is released and the shape is altered irreversibly whereby an intimate sealing is effected which can be destroyed only by deformation or destruction. Preferably, a vinyl resin is used resulting from the conjoint polymerization of vinyl halides and vinyl esters of organic acids, in the proportion of about 70 per cent to 95 per cent of vinyl halide, preferably chloride. Substances, such as urea and calcium stearate, may be incorporated to increase stability to heat and/or light; lubricants, such as carnauba wax and halogenated naphthalenes, when the material is to be extruded; fillers such as wood flour, silica, and asbestos; and pigments and dyes. For example, a vinyl resin prepared by conjointly polymerizing vinyl acetate and vinyl chloride and containing carnauba wax and alkaline calcium stearate, is heated and extruded under pressure in the form of a tube of \ba1/2\be" internal diameter which is expanded to an internal diameter of 1 \ba1/32\be" and ,015" thick and quickly chilled. Sections of the tube are cut to constitute closure members and after application are subjected to heat for about ten minutes, whereupon the internal strain consequent upon expansion and chilling is released and the resulting shrinkage causes a tight closure.

Inventors

No inventors recorded.

Bibliographic Details