Teflon PTFE 7A
fluoropolymer resin

Granular Compression Molding 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 applications. Customers who wish to use the Teflon® trademark in connection with DuPont PTFE 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 7A

Description
Teflon® PTFE 7A is a white powder with very small particle size. Its most unique feature is high bulk density.
The small particle size of Teflon® PTFE 7A helps to minimize voids even at relatively low molding pressure. High bulk density increases the size of moldings possible from a given mold or press opening.

Teflon® PTFE 7A is preferred for large moldings, such as billets, requiring optimum mechanical and electrical properties. It is also used in a mixture with fillers when they are added to modify the mechanical properties of moldings.

Properly processed products made from neat Teflon® PTFE 7A provide the superior properties typical of the fluoropolymer resins: retention of properties after service at 260℃ (500℉), useful properties at –240℃ (–400℉), chemical inertness to nearly all industrial chemicals and solvents, and low friction and antistick surfaces. Dielectric prop-erties are outstanding and stable with frequency and temperature. Molded products have moderate stiff-ness and high ultimate elongation.

In a flame situation, products of Teflon® PTFE 7A 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 pre-sented by this or any other material when under actual fire conditions.

Typical End Products
Many end products are fabricated from moldings of Teflon® PTFE 7A, including skived film and sheet, gaskets, packings, mechanical seals, bridge or pipeline bearing pads, shaft bearings, electrical insulators, piston rings, expansion bellows, dia-phragms, and chemical linings. The use of fillers provides a wide choice of modified mechanical properties.

FDA Compliance
Properly processed products (sintered at high temperatures common to the industry) made from Teflon® PTFE 7A resin can qualify for use in con-tact with food in compliance with FDA Regulation 21 CFR 177.1550.

Processing
Teflon® PTFE 7A usually is processed in two steps:preforming and sintering. The powder is first com-pacted into a preformed shape approximating that of the desired molding. A precise heating (sinter-ing) and cooling cycle is then used to consolidate the molding at temperatures above the crystalline melting point of the neat powder. The properties of a finished molding are dependent on preform pressure, sintering time and temperature, and cooling rate.

Teflon® PTFE 7A is used to make relatively large objects in molds that can be filled manually. Small-particle resins do not flow properly in automatic feeding systems. Refer to the typical property data in Table 1.

Table 1 Typical Property Data for Teflon® PTFE Fluoropolymer Resin Grade 7A*
Property		ASTM Test Method	Unit	Nominal Value
General	Average Bulk Density	D4894	g/L	460
	Average Mold Shrinkage	D4894	%	3.4
	(at preform pressure of 35 MPa [5,000 psi])
	Average Particle Size	D4894	μm	34
	Standard Specific Gravity	D4894	-	2.16
	Melting, Peak Temperature	D4894	-	-
	Initial	-	℃	342 ±10
			(℉)	(648 ±18)
	Second		℃	327 ±10
			(℉)	(621 ±18)
Mechanical	Tensile Strength	D4894	MPa (psi)	34.5 (5,000)
	Elongation at Break	D4894	%	375
*Teflon® PTFE 7A is ASTM D4894, Type II. Note: Typical properties are not suitable for specification purposes.

Safety Precautions
WARNING!
VAPORS CAN BE LIBERATED THAT MAY BE HAZARDOUS IF INHALED.
Before using Teflon® PTFE 7A, 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 7A, may cause flu-like symptoms (chills, fever, sore throat) that may not occur until several hours after exposure and that typically pass within about 24 hours. Vapors and fumes liberated during hot processing should be exhausted com-pletely from the work area; contamination of tobacco with polymers should be avoided.

Mixtures with some finely divided metals, such as magnesium or aluminum, can be flammable or explosive under some conditions.

Storage and Handling
Preforming is easiest when the resin is uniformly between 21–27℃ (70–80℉). As temperature declines below this range, the resin will be increas-ingly difficult to mold without cracks and problems with condensed moisture. Higher temperatures inhibit flow and promote lumping. Storage condi-tions should be set accordingly.

Cleanliness is a critical requirement for successful use of Teflon® PTFE 7A. The white resin and high sintering temperatures cause even very small for-eign particles to become visible in finished mold-ings. Keep resin drums closed and clean. Good housekeeping and careful handling are essential.

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