EPTFE gasket tape is a sealing material supplied as a continuous, white, 100% PTFE gasket tape. Due to its excellent flexibility, compression resilience, and very easy installation, it is widely used in chemicals, pharmaceuticals, petrochemicals, food & beverage, electronics, power generation, metallurgy, and marine industries.
In current practice, many soft ePTFE gasket tapes are made from 100% PTFE only. Such types of ePTFE gasket tapes tend to have lower strength, weaker corrosion resistance, and are prone to aging.
Another approach is to first produce an ePTFE sheet with improved anti-creep properties and then fabricate ePTFE gaskets from that sheet. However, these ePTFE sheets often show insufficient elasticity and strength.
This disclosure provides a ePTFE gasket tape with high strength, good corrosion resistance, excellent flexibility, and strong compression-rebound. The tape features a low coefficient of friction, reliable sealing, no hydrolysis, and no hardening, and can be used from -300 °C to +310 °C. A convenient preparation method is also provided; tapes made by this method exhibit excellent softness.
Composition (by parts by weight)
The PTFE gasket tape is composed of the following ingredients :
PTFE
FKM fluoroelastomer (fluororubber)
Phenolic-epoxy resin
Vulcanizing agent (composed of 2 parts PDM vulcanizing agent + 1 part sulfur + 1 part silica; parts by weight)
Reinforcing agent: silica (SiO₂)
Manufacturing Method
Step A — Mixing
Weigh PTFE, fluoroelastomer, phenolic-epoxy resin, vulcanizing agent, and reinforcing agent. Mix uniformly:
First mix at 60 r/min for 6 min
Then mix at 250 r/min for 20 min
Step B — Molding & Curing
Primary press: 355 °C, 18–20 MPa, press 15 min, then hold (dwell) 2 h.
Secondary press: 250 °C, 15 MPa, press 10 min.
Cool in air to ambient.
This process yields the finished PTFE gasket tape.
Advantages
High strength and good corrosion resistance
Excellent flexibility with strong compression set recovery
Low friction and tight sealing performance
Non-hydrolyzing, non-hardening during service
Wide temperature capability: -300 °C to +310 °C
Process benefits: the two-stage mixing speeds improve blend uniformity; controlled temperature/pressure molding promotes tighter molecular bonding among ingredients, enhancing anti-fracture performance.
Detailed Examples (Implementation)
Example 1
Formulation (parts by weight):
PTFE 80, FKM 40, phenolic-epoxy 20, vulcanizing agent 10, reinforcing agent 5.
Mixing: 60 r/min for 6 min → 250 r/min for 20 min.
Molding: 355 °C @ 18–20 MPa, press 15 min + dwell 2 h → 250 °C @ 15 MPa, press 10 min → air cool.
Vulcanizing agent: 2 parts PDM + 1 part sulfur + 1 part silica.
Reinforcing agent: silica.
Performance indices:
Compression rebound: 30 %
Tensile strength: 18 MPa
Elongation at break: 180 %
Service temperature: -180 °C to +200 °C
Example 2
Formulation (parts by weight):
PTFE 100, FKM 50, phenolic-epoxy 25, vulcanizing agent 10, reinforcing agent 5.
Mixing: 60 r/min for 6 min → 250 r/min for 20 min.
Molding: 355 °C @ 18–20 MPa, press 15 min + dwell 2 h → 250 °C @ 15 MPa, press 10 min → air cool.
Vulcanizing agent: 2 parts PDM + 1 part sulfur + 1 part silica.
Reinforcing agent: silica.
Performance indices:
Compression rebound: 45 %
Tensile strength: 24 MPa
Elongation at break: 230 %
Service temperature: -300 °C to +310 °C
Example 3
Formulation (parts by weight):
PTFE 100, FKM 60, phenolic-epoxy 30, vulcanizing agent 15, reinforcing agent 15.
Mixing: 60 r/min for 6 min → 250 r/min for 20 min.
Molding: 355 °C @ 18–20 MPa, press 15 min + dwell 2 h → 250 °C @ 15 MPa, press 10 min → air cool.
Vulcanizing agent: 2 parts PDM + 1 part sulfur + 1 part silica.
Reinforcing agent: silica.
Performance indices:
Compression rebound: 15 %
Tensile strength: 16 MPa
Elongation at break: 120 %
Service temperature: -250 °C to +280 °C
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