Anti-pilling Polyester Fibers

1.  Anti-pilling Properties and Molecular Weight

2.  Anti-pilling Fibers Status in the World

3.  A Technology Breakthrough by Glysil Chemicals Inc.

4.  The Amount of Glysil^® GS-6 in Polyester

5.  Analysis For Anti-pilling Polyester Fibers

1.  Anti-pilling Properties and Molecular Weight  

What is pilling? Pilling is a defect in fabric when fibers are rubbed or pulled out of yarns and entangled with intact fibers, forming soft, fuzzy balls on the fabric surface. 

Regular polyester fibers have intrinsic viscosity IV about 0.66 (Mw 16,500). Good spinning performance requires IV 0.52 (Mw 11,500) or higher.  Truly pilling free staple requires intrinsic viscosity IV 0.39 (Mw 7,500) or lower. 

2.  Anti-pilling Fibers Status in the World

In North America and Europe, anti-pilling staple has been commercially produced in DMT process more than 30 years and is the largest volume specialty polyester fiber product.  A hydrolyzable additive temporarily increases IV to 0.52 or higher for spinning. After spinning it hydrolyzes to IV 0.39 or lower in drawing or dyeing. 

Since 1980’s, most new polyester plants built were TPA process. The additive of DMT process hydrolyzes and forms rocks/sands in TPA process due to water byproduct.  A dilemma: the additive must be able to hydrolyze after spinning, but it must not hydrolyze in TPA polymerization process where there is byproduct water.  

3.  A Technology Breakthrough by Glysil Chemicals Inc.

Glysil Chemicals invented a new technology to produce anti-pilling fibers in TPA process, US, China, and Taiwan patents have been issued.  Glysil^® GS-6 is similar to the multifunctional additive used in DMT process for anti-pilling properties, but it does not form sands or rocks in TPA process.  Glysil^® GS-6 is a breakthrough for anti-pilling fibers: 

·     Glysil^® GS-6 Increases IV to 0.52 or higher for good spinning.

·     Does not hydrolyze in TPA polymerization process, no sand or rock formation.

·     After spinning it hydrolyzes to IV 0.39 or lower in drawing and dyeing.

·     Stay in the fibers after hydrolyzation, does not go into the water.

·     No permanent branching or crosslinks which affect spinning.

·     Ethylene glycol solution, miscible with water.

4.  The Amount of Glysil^® GS-6 in Polyester

Note:

(1) The amount of Glysil^® GS-6 in the table included both the active ingredient and EG solvent.  To obtain active ingredient in polymer, multiply the number in the table by 60%.

(2) Spinning IV is analyzed in lab but controlled by tortional oscillation viscometer (TOV).  Anti-pilling IV is analyzed in the lab but controlled by Glysil^® GS-6 additive. 

(3) Free fall yarn under spinneret should be sampled every 2-8 hours for IV analysis.  If the difference of the two IV is smaller than that desired, CP engineers should increase Glysil^® GS-6 input; if the difference is bigger than that desired, decrease Glysil^® GS-6 input.    

5.  Analysis For Anti-pilling Polyester Fibers

Polyester molecular weight is measured by intrinsic viscosity (IV).  Spinning IV (normal IV before hydrolysis) is important for spinning, which is the same as normal IV analysis familiar to most PET producers. Anti-pilling IV (IV after hydrolysis) is important for anti-pilling.   Anti-pilling IV analysis has the same procedures as normal IV, except that the solvent contains 150 ppm sulfuric acid H₂SO₄ (98%).  The H₂SO₄ containing solvent should be prepared in larger volume (1000 ml or more) for accuracy. The solvent can be hexafluoroisopropanol (HFIP), phenol/tetrachloroethane 3/2, phenol/tetrachloroethane 1/1, and phenol/o-dichlorobenzene 1/1. 

To test pilling resistance of knitting fabric, ICI pilling box is commonly used in Europe and Asia.  Atlas Random tumble pilling tester is often used in North America.  For non-woven and other fabrics, some producers also use Martindale abrasion and pilling tester or brush pilling tester. 

6.  Comparison Of Anti-pilling Staple With Cotton, Wool And PET Staple.