Static-dissipative foam extrusion calibration with minimized expansion loss
View Patent ↗The disclosure relates to a calibrator including a first plate opposing a second plate, the first plate having a first foam-expansion surface adjacent to a first anti-static surface, the second plate having a second foam-expansion surface adjacent to a second anti-static surface, wherein the first foam-expansion surface and the second foam-expansion surface are aligned to form a foam-expansion region, and wherein the first anti-static surface and the second anti-static surface are aligned to form an anti-static region. The disclosure also relates to a method of producing a polyetherimide foam, the method including passing a liquid polymer mixture comprising a polyetherimide through the calibrator.
1. A calibrator comprising a first plate opposed to a second plate, the first plate comprising:
a first foam-expansion surface adjacent to
a first anti-static surface,
wherein the first foam-expansion surface comprises an unfilled fluoropolymer,
wherein the first anti-static surface comprises a carbon-filled fluoropolymer,
wherein the calibrator further comprises a first end proximal to a foam extrusion die and a second end distal to the foam extrusion die, wherein the first foam expansion surface is positioned at the first end and the first anti-static surface is positioned at the second end.
2. The calibrator according to claim 1 , the second plate comprising:
a second foam-expansion surface adjacent to
a second anti-static surface,
wherein the second foam-expansion surface comprises an unfilled fluoropolymer, and
wherein the second anti-static surface comprises a carbon-filled fluoropolymer.
3. The calibrator according to claim 2 ,
wherein the first foam-expansion surface and the second foam-expansion surface are aligned to form a foam-expansion region, and
wherein the first anti-static surface and the second anti-static surface are aligned to form an anti-static region.
4. The calibrator according to claim 3 , wherein the foam-expansion region imparts a friction coefficient of 0.05 or lower to a polymer mixture in contact with the first plate and the second plate.
5. The calibrator according to claim 4 , wherein a polymer mixture comprises a polyetherimide resin.
6. The calibrator according to claim 3 , wherein the anti-static region imparts a static dissipation factor oat least 0.003 to a polymer mixture in contact with the first plate and the second plate.
7. The calibrator according to claim 6 , wherein a polymer mixture comprises a polyetherimide resin.
8. The calibrator according to claim 3 ,
wherein a foam-expansion region is positioned at the first end, and
wherein an anti-static region is positioned at the second end.
9. The calibrator according to claim 8 , wherein the foam-expansion region has a length extending from the first end toward the second end, the length within a range of from 0.5 inches to 36 inches.
10. The calibrator according to claim 8 , wherein the foam-expansion region has a length extending from the first end toward the second end, the length being calibrated to allow a liquid polymer mixture to be ejected from the foam extrusion die to expand in a volume by at least 500%.
11. The calibrator plate according to claim 1 , wherein the unfilled fluoropolymer is polytetrafluoroethylene.
12. The calibrator plate according to claim 1 , wherein the carbon-filled fluoropolymer is carbon-filled polytetrafluoroethylene.
13. A calibrator comprising a first plate opposing a second plate,
the first plate comprising
a first foam-expansion surface adjacent to
a first anti-static surface,
the second plate having
a second foam-expansion surface adjacent to
a second anti-static surface,
wherein the first foam-expansion surface comprises an unfilled fluoropolymer,
wherein the first anti-static surface comprises a carbon-filled fluoropolymer
wherein the first foam-expansion surface and the second foam-expansion surface are aligned to form a foam-expansion region,
wherein the first anti-static surface and the second anti-static surface are aligned to form an anti-static region, and
wherein the calibrator comprises a first end proximal to a foam extrusion die and a second end distal to the foam extrusion die,
wherein the foam-expansion region is positioned at the first end,
wherein the anti-static region is positioned at the second end.
14. The calibrator according to claim 13 , wherein the foam-expansion region comprises an amount of polytetrafluoroethylene sufficient to impart a friction coefficient of 0.05 or lower to a polymer mixture in contact with the first plate and the second plate.
15. The calibrator according to claim 13 , wherein the anti-static region comprises an amount of carbon-filled polytetrafluoroethylene sufficient to impart a static dissipation coefficient of at least 0.003 to a polymer mixture in contact with the first plate and the second plate.
16. The calibrator according to claim 13 ,
wherein the foam-expansion region has a length extending from the first end toward the second end, the length being calibrated to allow a polymer mixture to be ejected from the foam extrusion die to expand in a volume by at least 500%.