DuPont™ Teflon® PTFE 640
fluoropolymer resin
Fine Powder Lubricated Extrusion Resin

Brand
Teflon® is a registered trademark of DuPont for its brand of fluoropolymer resins, which can only be licensed by DuPont for use in approved applica-tions. Customers who wish to use the Teflon® trademark in connection with DuPont Fine Powder products under license from DuPont should contact (86) 13662986968. Without a license, customers may not identify their product as containing Teflon®, but may refer to the resin as PTFE 640.

Description
DuPont™ Teflon® PTFE 640 is a white powder composed of agglomerate particles. Typical of all grades of Teflon® PTFE (polytetrafluoroethylene) fine powders, it can be lubricated and extruded by standard paste extrusion techniques.

Compared with other grades of PTFE fine powder, Teflon® PTFE 640 is a resin that has increased melt strength and low shrinkage. It is one of the most consistent and easy-to-process resins. It is most suitable for products with medium-to-high reduc-tion ratio extrusions.

Properly processed products made from neat Teflon® PTFE 640 provide the superior properties typical of the fluoropolymer resins: retention of properties after service at 260°C (500°F), useful properties at –240°C (–400°F), chemical inertness to nearly all industrial chemicals and solvents, and low friction and antistick surfaces. Dielectric properties are outstanding and stable with fre-quency and temperature. Products have moderate stiffness and high ultimate elongation.

In a flame situation, products of Teflon® PTFE 640 resist ignition and do not themselves promote flame spread. When ignited by flame from other sources, their contribution of heat is small and with very
little smoke.

Statements, or data, regarding behavior in a flame situation are not intended to reflect hazards presented by this or any other material when under actual fire conditions.

Teflon® PTFE 640 is ASTM D4895, Type I, Grade I, Class C.

Typical End Products
Applications for Teflon® PTFE 640 include high quality tubing and profiles, high performance wire and cable products, and film and tape fabricated products.

Table 1
Typical Property Data for DuPont™ Teflon® PTFE 640 Fluoropolymer Resin

Property		ASTM Test Method	Unit	Nominal Value
General	Bulk Density	D4895	g/L	475
	Average Particle Diameter	D4895	µm	400
	Standard Specific Gravity	D4895	-	2.17
	Rheometer Pressure*	D4895	MPa(psi)	34.5(5,000)
Typical properties are not suitable for specification purposes. *Reduction Ratio 1600:1

Processing
Teflon® PTFE 640 is prepared for extrusion by mixing with a liquid extrusion aid. The damp powder is compressed into a cylindrical preform slug and placed in the cylinder of a ram-type extruder. Under high pressure, the composition is forced through a finishing die to produce beading, tubing, or coatings. Dissimilar materials, such as metal wire or high-temperature fibers, can be coated by feeding them through the axis of the extruder barrel. After extrusion, the product is a low-density, but coherent, fibrous structure. Teflon® PTFE 640 is usually processed further, with heat, into a solid resin product, such as tubing.

Heat is applied in two steps, which may be per-formed in-line with extrusion or separately. The lubricant must be removed first, usually by heating within the range of 100–300°C (212–572°F). A sintering step follows to melt the virgin resin above its crystalline melting point of approximately 342°C (648°F) and produce a void-free, stress-free, and solid product of PTFE resin. When performed in-line, the heating steps determine the maximum line speed.

Reduction ratio (RR) is the ratio of cross section of preform to that of extrudate; it is an extrusion parameter affecting the selection of resin grade.

Typical finished product properties are shown in Table 2.

Table 2
Typical Property Data for Products Fabricated from DuPont™ Teflon® PTFE 640

Property	ASTM No.	Unit	Teflon® CFP 6000
Tensile Strength, 23℃ (73℉)	D1708	MPa (psi)	31.6 (4,600)
Elongation, 23℃ (73℉)	D1708	%	400
Stiffness	D747	MPa (psi)	595 (85,000)
Deformation Under Load, 6.9 MPa, 21℃, 24 h (1,000 psi, 70℉, 24 h)	D621	%	2.4
Hardness, Shore D	D2240	-	58
Dielectric Strength, 0.38 mm (15 mil)	D149	kV/mm (V/mil)	23.6 (600)
Dielectric Constant, 100 Hz to 60 MHz	D150	-	2.05
Power Factor, 100 Hz to 60 MHz	D150	-	<0.0002
Volume Resistivity	D257	ohm•cm	>1017
Water Absorption	D570	%	<0.01
Specific Gravity	D792	-	2.17
Chemical Resistance	-	-	Inert to almost all chemicals and solvents
Weather Resistance	-	-	Excellent
Colorability	-	-	Unlimited

Safety Precautions
WARNING!
VAPORS CAN BE LIBERATED THAT MAY BE HAZARDOUS IF INHALED.
Before using Teflon® PTFE 640, read the Material Safety Data Sheet and the detailed information in the “Guide to the Safe Handling of Fluoropolymer Resins, Latest Edition,” published by the Fluoro-polymers Division of The Society of the Plastics Industry—available from DuPont.

Open and use containers only in well-ventilated areas using local exhaust ventilation (LEV). Vapors and fumes liberated during hot processing, or from smoking tobacco or cigarettes contaminated with Teflon® PTFE 640, may cause flu-like symptoms (chills, fever, sore throat) that may not occur until several hours after exposure and pass within 36–48 hr. Vapors and fumes liberated during hot process-ing should be exhausted completely from the work area; contamination of tobacco with polymers should be avoided. Mixtures with some finely di-vided metals, such as magnesium or aluminum, can be flammable or explosive under some conditions.

Flammable liquid extrusion aids can cause fires in ovens and in mixing areas. Before using, obtain manufacturers’ recommendations.

Storage and Handling
Teflon® PTFE 640 is more resistant to damage than other PTFE fine powder products, but must be handled carefully to avoid shearing the powder prior to extrusion. Fibrillation by shearing is not reversible, and damaged particles can appear as defects in the finished product. As temperature is reduced, the powder becomes progressively less sensitive to mechanical damage or compaction in its containers. For this reason, DuPont stores and delivers Teflon® PTFE 640 at or below 7°C (45°F) to assure the resin is maintained below 13°C (56°F).

All processing steps prior to aging of the lubricated blend are facilitated at reduced temperature, but ambient dew point must be controlled to prevent condensation on the resin.

Storage and handling facilities should be clean. The high sintering temperature causes even very small foreign particles to become visible or to make defects in finished products. Keep resin drums closed and clean. Good housekeeping and careful handling are essential.

Packaging
Teflon® PTFE 640 is packaged in 25-kg (55-lb) plastic containers.

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