Patent ID: 6488972
Filing Date: 2002-12-03
Classification: B65B,B65D

Abstract:
A hermetically sealed package comprising:a) a substantially rigid base; b) a product supported on said substantially rigid base; and c) a thermoplastic stretch film over said product wherein said stretch film: is capable of cold stretching at room temperature under the conditions of ASTM D-882 (Method A) by at least 150% of its original length without breaking when applying a stretching force of not higher than 2 kg/cm; is capable of a permanent deformation in length in each of the machine and transverse directions of less than 20%, where the permanent deformation is measured by providing a representative film sample having original dimensions of 12.5 cm long and 2.5 cm wide, stretching the film sample lengthwise at a constant rate until 50% stretch is obtained, releasing the film sample for 30 seconds, subsequently measuring the length of the stretched film sample, and calculating the percent increase in length of the stretched film sample compared to the original film sample; is pre-stretched by an elongation of at least 10% in at least one direction to place the stretch film under pre-stretched tension before contact with said rigid base or said product; and is welded to said substantially rigid base along a sealing line while said stretch film is under at least said pre-stretched tension so as to form said hermetically sealed package.