Abstract 1,058,805. Wrapping. W. R. GRACE & CO. May 5, 1965 [May 6. 1964], No. 19020/65. Heading B8C. Electrostatic forces apply a dielectric film about an article, or hold the film on the article while it is heat-shrunk. The article may be a container 14 (Fig. 2) with a flange 15 gripped by the film 16 as in Fig. 3 (not shown) when the film has been heat-shrunk. The electrostatic field is set up between electrodes 18, 24, the latter being pointed electrodes which may be mounted within hot air ducts providing the heat for shrinking the film. The container 14 itself may form one of the electrodes. The wrapping material may be in the form of netting or filaments or may be oriented sheet, or a laminate. The electrode 18 may be coated with friction-reducing material, and may be smooth or of reticular form. The electrode 18 may be of metal, wood or paper pulp, it may form part of the final package, or it may form part of a conveyer carrying the container 14 or, as in Fig. 1 (not shown), an article (2) to be wrapped. The article to be covered may alternatively be mounted between horizontally spaced electrodes.
A METHOD FOR HEAT SHRINKING A DIELECTRIC THERMOPLASTIC HEAT SHRINKABLE MATERIAL ABOUT AN OBJECT COMPRISING: (A) PLACING SAID OBJECT ON AN ELECTRICALLY CHARGEABLE SUPPORT, (B) PLACING SAID MATERIAL OVER AT LEAST A PORTION OF SAID OBJECT, THE PERIPHERAL PORTINS OF SAID MATERIAL EXTENDING BEYOND THE PERIPHERY OF SAID OBJECT, (C) ELECTROSTATICALLY CHARGING SAID MATERIAL SUFFICIENT TO ATTRACT THE PERIPHERAL PORTIONS OF SAID MATERIAL TOWARD SAID SUPPORT AND RESTRAIN MOVEMENT OF SAID MATERIAL AND, (D) HEATING AT LEAST A PORTION OF SAID MATERIAL TO HEAT SHRINKING TEMPERATURES SUFFICIENT FOR THE SHRINK ENERGY OF THE FILM TO COVERCOME THE RESTRAINING FOCE OF THE ELECTROSTATIC CHARGE AND TO SHRINK THE MATERIAL ABOUT AT LEAST A PORTION OF THE OBJECT.
Claim 2
Independent Claim
116 words
A METHOD FOR HEAT SHRINKING A DIELECTRIC THERMOPLASTIC HEAT SHRINKABLE MATERIAL ABOUT AN OBJECT COMPRISING: (A) PLACING SAID OBJECT ON AN ELECTRICALLY CHARGEABLE SUPPORT, (B) PLACING SAID MATERIAL OVER AT LEAST A PORTION OF SAID OBJECT, THE PERIPHERAL PORTINS OF SAID MATERIAL EXTENDING BEYOND THE PERIPHERY OF SAID OBJECT, (C) ELECTROSTATICALLY CHARGING SAID MATERIAL SUFFICIENT TO ATTRACT THE PERIPHERAL PORTIONS OF SAID MATERIAL TOWARD SAID SUPPORT AND RESTRAIN MOVEMENT OF SAID MATERIAL AND, (D) HEATING AT LEAST A PORTION OF SAID MATERIAL TO HEAT SHRINKING TEMPERATURES SUFFICIENT FOR THE SHRINK ENERGY OF THE FILM TO COVERCOME THE RESTRAINING FOCE OF THE ELECTROSTATIC CHARGE AND TO SHRINK THE MATERIAL ABOUT AT LEAST A PORTION OF THE OBJECT.