초록 ▼

A container having a generally rectangular rim surrounding its opening is closed by a foil membrane that extends over the rim and is sealed to the rim by inductively heating it. The membrane does not correspond in configuration to the rim, but instead its side and end margins curve away from the sid

A container having a generally rectangular rim surrounding its opening is closed by a foil membrane that extends over the rim and is sealed to the rim by inductively heating it. The membrane does not correspond in configuration to the rim, but instead its side and end margins curve away from the sides and ends, respectively, of the container rim, so that the peripheral margin of the membrane is located closer to the container rim at the corners of the rim than at the sides or ends of the rim. The foil of the membrane is coated with a resin bonding material, and when the membrane is placed in a rapidly oscillating magnetic field, its foil is inductively heated throughout the entire area that overlies the rim, thereby rendering the bonding material plastic and establishing a uniform bond between the rim and membrane. In contrast, a membrane having the same generally rectangular configuration as the rim will bond to the sides and ends of the rim, but not to the corners without overheating the membrane, since a membrane of that configuration does not heat uniformly in an oscillating magnetic field.

대표청구항 ▼

A process for closing a container opening that is surrounded by a rim of generally polygonal configuration, said process comprising: placing a metal foil over the polygonal rim of the opening; the foil having a peripheral margin that is further from the rim of the polygonal opening than the corners

A process for closing a container opening that is surrounded by a rim of generally polygonal configuration, said process comprising: placing a metal foil over the polygonal rim of the opening; the foil having a peripheral margin that is further from the rim of the polygonal opening than the corners of the opening; interposing a bonding material between the metal foil and the rim of the container opening; and, while the foil is over the opening and the bonding material is between the foil and the rim; subjecting the foil to a rapidly oscillating magnetic field and at the same time producing relative physical movement between the field and the foil, the field being of sufficient intensity to inductively heat the foil enough to render the bonding material plastic, whereby the foil bonds to the rim.