Virgin Molding – GP-100
HaloPolymer PTFE grade GP-100 is a granular powder product designed for big billets production and general purpose compression molding. This fully fluorinated resin has excellent chemical stability, electrical and mechanical properties. GP-100resin offers improved handling and better productivity. Narrow particle size distribution value of this grade allows to eliminate voids formation in billets at reduced molding pressure.
| Product overview: | This virgin granular PTFE is best suited for production of big billets by compression molding. This material can be used for production of articles for chemical, mechanical, low-friction and electrical applications. |
| Typical applications: | Big billets, skived sheets, skived films. General purpose: pipes, tubes, spacers, O-rings, insulating tape, laboratory and chemical equipment. |
| Availability: | 25 kg cardbox with 2×12,5 kg polyethylene inserts. |
TYPICAL PROPERTIES OF PTFE GRADE GP-100
| Properties | Test Method | Units | Typical Value, GP-100 |
| ASTM Type/Grade | ASTM D4894 | – | II |
| Bulk density | ASTM D4894 | g/l | 520 |
| Average particle size (d50) | Internal, Laser Scatt. | µm | 100 |
| Mould shrinkage | ASTM D4894 | % | 2,5 |
| Std. specific gravity (SSG) | ASTM D4894 | g/cm3 | 2,16 |
| Melting points | DSC | °C (°F) | 342 (648) (Initial) |
| 327 (621) (Second) | |||
| Molding pressure | Internal | MPa (psi) | 20-25 (2900-3625) |
| Sintering temperature | Internal | °C (°F) | 360-370 (680-698) |
| Tensile strength | ASTM D4894 | MPa (psi) | 30 (4350) |
| Elongation at break | ASTM D4894 | % | 300 |
| Dielectric strength, | Internal | KV/mm | 120 |
| 0.100±0.005 mm | |||
| Thermal Instability Index | ASTM D4894 | – | 20 |
CERTIFICATION
| Certificate of conformity FDA 21 CFR 177.1380 & FDA 21 CFR 177.1550 | PTFE | Intertek Polychemlab | USA |
| Certificate of conformity Class VI acc. USP 35 <88> | PTFE | Pacific BioLabs | USA |
| Declaration of Compliance commission reg. (EU) 10/2011 | PTFE | SGS Multilab | EU |
PRODUCT DESCRIPTION
PTFE granular powder grade GP-100 is a product of suspension polymerization of TFE subjected to mechanical grinding. Grinding process allows narrow particle size distribution and uniformity of bulk density.
PROCESSING BASICS
Conventional plastics processing techniques are not suitable for PTFE resin processing due to its high melting temperature and very high melt viscosity.
Grade GP-100 fabrication includes mould pressing of PTFE powder at ambient temperature, preform sintering in several stages with the maximum temperature of 360-370° C and subsequent controlled cooling. Billets can be further processed into finished articles by machining or cutting.
STORAGE AND HANDLING
Bags with PTFE powder should be stored in a cold dry place. Recommended storage temperature range is 15-20 °C. Bags with powder stored below this range should be kept closed until warmed to room temperature. Optimal temperature range for PTFE compression moulding is 20-25°C. Below this temperature PTFE changes its crystalline structure with volume variation of 1-2%, causing formation of cracks in preforms.
Mechanical manipulations with PTFE powders should be reduced. At the temperature higher than 30°C PTFE tends to form clumps.
PTFE powders attract dust and moisture from ambience and should be processed at clean and dry conditions.
Sintering of PTFE is linked to an emission of toxic gaseous products. Therefore sintering process should be performed in a ventilated area. Air from the processing zone must be evacuated.
PRESSING
The pressing process of PTFE powder requires careful powder de- clumping. Uniform layer-by-layer mold filling is essential to avoid cracks formation in preform. The temperature of PTFE powder should be kept above 19° C.
Mold filled with PTFE powder is pressed into a solid preform with density of 1,80-2,00 kg/l.
Compression ratio parameter indicates volume compaction of powder during the pressing process. It is based on a preform/bulk density ratio. The rate of ram travel is adjusted to allow air to leave preform.
TYPICAL MOLDING PROPERTIES
| Properties | GP-100 |
| Bulk density, g/l | 520 |
| Compression ratio | ~4 |
| Molding pressure, MPa | 20-25 |
SINTERING
The preformed PTFE powder is sintered under a temperature program generally containing 7 temperature steps including:
PTFE, final cooling.
Annealing steps are also required for bigger billets sintering in order to reduce article distortion.
MACHINING
PTFE billets are machined in the same way that mild metals are. Sharp steel cutting tools are suitable for the machining process. PTFE billets designed for further skived films production are processed at elevated temperatures.
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