Packing process
AssigneeW. R. Grace & Co.
InventorGiorgio Mugnai
Life of this patent
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Abstract
A vacuumizing and sealing operation on a package comprises initially reducing the external pressure on the package, before sealing of the package, to a value at which the flexible film covering of the package is capable of ballooning, and ensuring heating of the flexible film of the package, preferably while an intermediate pressure is maintained (at which intermediate pressure ballooning could just be sustained without excessive evacuation to reduce the thermal capacity of the circulating air). Finally the pressure inside and outside is reduced still further before re-pressurizing.
Claims1
A process for forming a vacuum sealed package comprising a flexible film covering at least one product article, such process comprising the steps of subjecting the unsealed package to reducing pressure at a first rate of reduction to attain an intermediate pressure at which ballooning of said flexible film away from the surface of the said at least one product article occurs;
- reducing the rate of pressure reduction to a second and slower rate around the package when the said flexible film is in the ballooned condition so that evacuation of the package proceeds at a slower rate;
- heating the said ballooned flexible film while the rate of pressure reduction is so reduced;
- allowing the flexible film to collapse onto the surface of said at least one product article;
- sealing the package;
- and finally increasing the pressure around the sealed package.
Dependencies are inferred from the claim text.