TEFLON® Brand fibers are relatively simple to process using standard textile processes. The key items to focus on prior to any processing steps are: Quick Links Bleaching Bonding Calendaring Carding for Felt Heat Settings Knitting Preshrinking Transfer Rails Weaving 1) To assure proper temperature and humidity control in the room where you process the yarn to control static electric charge. The ideal conditions for processing are 70% relative humidity at a temperature of 70° Fahrenheit or 21° Celsius or higher. 2) Yarn conditioning: If the yarn has been stored in a cold dry warehouse it should be brought into the processing room about 1 day before use. The box and any protective covering on the yarn should be opened so it can acclimate to the warmer more humid conditions to avoid static buildup on the yarn during use. 3) Proper position of the tube: For best results the yarn tube should be positioned horizontally not vertically. Pulling the yarn off the package vertically may cause sloughing of the yarn off the package and trapped yarn under the tube. The only consideration with a horizontal tube position is the distance from the end of the tube to the yarn takeoff eyelet. Ideally this distance should be 6 inches or less to control yarn whip. 4) Yarn Tension: Controlling yarn tension is a critical step for successful processing in all textile process whether knitting or weaving. The simplest approach is to use disk tensioning devices. These simple devices are usually adequate for knitting and warping yarns. However, yarn accumulators may be required for the fill yarn in high speed weaving. 5) Yarn twist: Because our yarns are multifilament in structure and we do not use an antistatic finish on our continuous filament yarns, you may find it necessary to twist our yarns to obtain the best results in your process.

Table IV Methods for Bleaching TEFLON® PTFE fluoropolymer fiber **   Method #1 Method #2 Resultant color Pure White Pure White Bleaching Medium Hot Mineral Acids Hot Air Time Required Several Minutes Approximately 48 hours Potential Hazards*** Toxic fumes and spattering acid Toxic Fumes Outline of Procedure 1. Immerse TEFLON® in concentrated(98%) sulfuric acid. 1. Place TEFLON® in a well ventalated oven at 450º (232ºC) and raise temperature to 580º (304ºC) at a uniform rate over a 24-hour period.     2. Raise temperature of bath to boiling point, approximately 600º (316ºC). 2. Maintain temperature at 580ºF (304ºC) until TEFLON® turns white.     3. Slowly add drops of concentrated nitric acid to bath until TEFLON® turns white.       4. Remove TEFLON® from bath and wash alternately with water, acetone, and ammonium hydroxide until completely free of acid.       5. Heat TEFLON® until all traces of ammonia are removed and the pH reaches 7.     ** Yarns should be bleached in skein form and fabrics in loose folds or sheet form to achieve maximum uniformity. *** CAUTION: Use adequate ventilation, protective clothing, suitable warning signs, and take other appropriate precautions when using either methods outlined above(see "Precautions for Handling and Use," page 7) Table V Typical properties of bleached vs. natural TEFLON® PTFE fluoropolymer fiber.     Bleached Yarn   Natural Yarn   Nominal denier (dtex) 250 (275) 500(550) 1500(1650) 200(220) 400(440) 1200(1330) Breaking tenacity, g/den 1.0 0.95 0.95 2.0 2.0 1.6 (cN/tex) (8.8) (8.4) (8.4) (18) (18) (14) Elongation at break, % 40 80 140 19 19 35 Heat shrinkage after 30 min, % in boiling water 1.0 1.0 2.0 2.5 2.5 2.5 in air at 350ºF (177ºC) 2.5 2.5 30 60 6.0 60 **Determined on an "Instron" tensile tester at 70ºF (21ºC), 65% R.H.

The bonding of fabrics containing TEFLON® fiber to supporting substrates or the incorporation of TEFLON® fiber floc into bulk resin formulations suitable for molding applications is desirable for certain end uses, especially for bearings. The non-adhesive nature of TEFLON® fiber presents an obstacle to the use of conventional adhesive and bonding procedures, but adequate bonding has been accomplished through the use of one or more of the following methods:

• incorporating the TEFLON® fiber into a com­pound woven or double-faced fabric in which one surface is composed of cotton, glass, or other easily-bonded synthetic fiber. and the other surface is totally or partially composed of TEFLON® fiber
• weaving the TEFLON® fiber in a fabric con­struction suitable for sanding or napping operations that produce raised fibers on the fabric surface and enhance the formation of a mechanical bond between the fabric and the adhesive
• treating the TEFLON® fabric or fiber with cer­tain alkali metal systems that increase the effective surface area of the fiber, rendering it more receptive to adhesive bonding

Many commercial resin systems are suitable for adhesion of fabrics containing TEFLON® fiber to supporting materials. Acceptable performance of the resulting structure will depend on many factors, including surface preparation of the substrate, curing conditions for the chosen resin. and the use environment. Review these require­ments with the resin manufacturer before making your final selection. 

It is possible to calendar fabrics made of TEFLON® brand fibers using pressure alone or pressure and heat.  If you elect to use heated rolls, please refer to the heat setting section for fabrics made of TEFLON® brand fibers and heat set the fabric prior to calendaring the fabric with the heated rolls.

 

 

TEFLON® brand staple fibers are designed to process on a wide variety of carding systems.  Our fibers have a proprietary finish which allows are fibers to be carded under a wide variety of environmental conditions without unnecessary concern for static electric build up.  Additionally, we produce fiber with a pronounced and uniform crimp allowing our fibers to be carded on modern high capacity cards.  The resultant webs produced are usually heavier than those for most other synthetic fibers and because of the fiber’s naturally low friction may require some modification to the card’s cross lapping conveyor belts’ angle of incline and location relative to the card’s doffing system.

 

 

Fabrics containing TEFLON® brand fiber are not dimensionally stable when exposed to elevated service temperatures (see Table III). Total shrinkage is a function of both temperature level and exposure time. Required stability can be provided by preshrinking the fabrics in a relaxed condition at temperatures in excess of those to be encountered in use. Adequate stability for service temperatures below 200°F (93°C) is assured by a conventional boil-off procedure. For service temperatures of 400 to 500°F (204 to 260°C), relaxed treatment for 1 minute at 600°F (316°C) is recommended. This treatment will result in a nominal strength loss of approximately 15% and yield residual shrinkage in service of from 2 to 4%. Lower residuals can be obtained by increasing the length of the treatment. but will also increase the amount of thermal degradation in the fiber.       TABLE III     Yarn Properties of TEFLON® PTFE fluoropolymer fiber After Exposure to High Temperatures** Air Temperature Exposure Time, Breaking Strength Elongation at Break Work-to-Break Heat O F (°C) Hours Retained, % Retained, % Retained, % Shrinkage, % 350 (177) 1 101 182 156 6.3   10 99 191 156 6.5   1000 94 210 178 11.1 550 (288) 1 85 385 267 22.6   10 91 427 300 20.2   1000 69 512 322 24.1 700 (371) 1 deteriorated; testing not possible   **Data were obtained at room temperature using specimens of 400-denier (440 dtex) natural TEFLON® yarn.

Knitting TEFLON® brand yarns is a relatively simple process. Our yarns will process like any other multifilament yarn.It is possible to circular and warp knit our products without major difficulty. The only consideration is if the use of a yarn with twist and tension is required or if tension alone will be suitable for your production. Our fiber do not use a finish and if your building is not temperature and humidity controlled you will likely achieve the best knitting results with a yarn with 3 to 4 turns per inch (118 to 167 turns per meter). Additionally, you will need to use a tensioning device on each TEFLON® yarn feed to achieve the optimum knitting performance with circular knits. As outlined above, simple disk tensioning devices should be adequate for most knitting applications.

Fabrics containing TEFLON® PTFE fluoropolymer fiber are not dimensionally stable when exposed to elevated service temperatures (see temperature exposure table). Total shrinkage is a function of both temperature level and exposure time. Required stability can be provided by preshrinking the fabrics in a relaxed condition at temperatures in excess of those to be encountered in use.

Adequate stability for service temperatures below 200°F (93°C) is assured by a conventional boil-off procedure. For service temperatures of 400 to 500°F (204 to 260°C), relaxed treatment for 1 minute at 600°F (316°C) is recommended. This treatment will result in a nominal strength loss of approximately 15% and yield residual shrinkage in service of from 2 to 4%. Lower residuals can be obtained by increasing the length of the treatment. but will also increase the amount of thermal degradation in the fiber.

Each cone or tube of TEFLON® filament yarn is produced with a transfer tail consisting of several windings of the starting thread anchored around the exposed base of the core. Knots tied during cone winding are faced across the top of the cone.

Weaving TEFLON® brand yarns is slightly more complicated that standard multifilament yarns. Sizing can not be used with TEFLON® yarns because of the inherent non-stick nature of our yarns. As a result yarns with twist are required to produce a warp regardless of room temperature and humidity. However, with the proper tension, fill yarns do not have to have twist unless it is desired for the particular fabric you are producing. Fill yarns will require yarn accumulators for high speed weaving.

In weaving, you are likely to notice what appears to be dust accumulation on the metal surfaces. This accumulation is ptfe polymer forming a thin film build up on the metal. In most cases this buildup will not interfere with the weaving operation; however, you may find it necessary to occasionally clean the loom to prevent any of these deposits being pulled into the fabric and causing a cosmetic defect.

Woven fabrics of TEFLON® brand fibers will provide the flattest, tightest ptfe fiber fabrics possible because of their natural ability to take on a round cross-section when twisted and flatten out in weaving. These result in fabrics that naturally carry high loads or provide the best air filtration currently commercially available.