Patent ID: 8858849

Claim:
A method for gas impregnation of an intermittently fed thermoplastic material sheet, comprising: providing a pressure vessel having at least two outer pressure chambers sandwiching a central pressure chamber, wherein the central pressure chamber is separated from each of the two outer pressure chambers by respective interior sealable pass-through slots, wherein each of the interior sealable pass-through slots is defined by a rectangular opening having a pair of adjacently positioned confronting static seals for sealably engaging the intermittently fed thermoplastic material sheet, and wherein each of the two outer and central pressure chambers are separably pressurable to selected first, second, and third pressures, respectively; pressurizing each of the two outer and central pressure chambers to the selected first, second, and third pressures; and intermittently feeding the thermoplastic material sheet through each of the two outer and central pressure chambers by way of the interior sealable pass-through slots.