Forming screens
AssigneeTredegar Film Products Corporation
InventorsPaul E. Thomas, Sean W. Bower
Life of this patent
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Abstract
Composite forming screens comprise a layer of hard rubber with a Shore D hardness of 12-90, preferably 33-90 and most preferably 46-60 and in preferred embodiments, comprise a support layer of plastic or metal bonded to the hard rubber to form a composite. The forming screens may be planar or cylindrical and are provided with a plurality of apertures or through holes and a pattern of fine scale structures. Methods of making the forming screens are also disclosed.
Claims24
A perforated forming screen for making apertured formed films, the perforated forming screen comprising:
- at least one thermoset rubber layer with a Shore D hardness of 12-90, the rubber layer having a plurality of perforations extending therethrough and a plurality of laser-engraved, fine scale structures formed on at least one surface of the thermoset rubber layer adjacent to the plurality of perforations, the laser-engraved, fine scale structures comprising a size and spacing of no greater than about 254 microns, and the rubber layer and plurality of laser-engraved, fine scale structures not being sensitive to heat of a molten polymer used to make the apertured formed film such that the rubber layer and the plurality of laser-engraved, fine scale structures are maintained and not degraded when subjected to the heat of the molten polymer during a direct cast process.
A perforated forming screen for making apertured formed films, the perforated forming screen comprising:
- a thermoset rubber outer layer having a Shore D hardness of 12-90, the thermoset rubber outer layer comprising a plurality of perforations extending therethrough and a plurality of laser-engraved, fine scale structures formed on an external surface of the thermoset rubber outer layer, the laser-engraved, fine scale structures comprising a size and spacing of no greater than about 254 microns, and the thermoset rubber outer layer and plurality of laser-engraved, fine scale structures not being sensitive to heat of a molten polymer used to make the apertured formed film such that the thermoset rubber outer layer and the plurality of laser-engraved, fine scale structures are maintained and not degraded when subjected to the heat of the molten polymer during a direct cast process;
- and
- an internal support layer bonded to an internal surface of the thermoset rubber outer layer.
A cylindrical, perforated forming screen for making apertured formed films, the perforated forming screen comprising:
- a thermoset rubber layer having a plurality of perforations extending therethrough and a plurality of laser-engraved, fine scale structures formed on an external surface of the thermoset rubber layer adjacent to the plurality of perforations, the thermoset rubber layer and plurality of laser-engraved, fine scale structures not being sensitive to heat of a molten polymer used to make the apertured formed film such that the thermoset rubber layer and the plurality of laser-engraved, fine scale structures are maintained and not degraded when subjected to the heat of the molten polymer during a direct cast process.
Dependencies are inferred from the claim text.