More effective dryer fabrics thanks to SynStron

A new class of polyester monofilaments



Jiew Poh Liew

Challenge for polyester yarns


Heat and moisture – both are a challenge for polyester yarns of fabrics used in the dryer section. Thus Voith Paper developed the SynStron yarn, a polyester monofilament (PET) that ensures a longer service life of the dryer fabrics. This is achieved through higher strength and hydrolysis resistance.

SynStron: summary of advantages

  • Resistance to fibrillation
  • Higher seam loop strength
  • Greater abrasion resistance
  • Hydrolysis resistance
  • Cleaner running

SynStron yarns are used exclusively in dryer fabrics from Voith Paper (PrintTech-S and MultiTech-S). Since 2011 they are available worldwide.

The SynStron yarn was developed by Voith Paper at its R&D center that works exclusively on materials for use in paper machine fabrics. Thisexpertise brings successful products to customers. For example, a paper producer set a record life by using the new SynStron monofilament in a PrintTech-S Q2 dryer fabric from Voith Paper. The fabric ran in the third single-tier dryer group of a paper machine that produced offset and coating base paper at a speed of up to 1,300 m/min.


While the customer had previously changed standard polyester fabrics every 12 months, in contrast the dryer fabric with SynStron monofilaments achieved a fabric life of 446 days (15 months). This is equivalent to an increased life of 30%.

Tests on fabrics that have already run on paper machines include the measurement of remaining seam strength and air permeability. In the case of the fabric mentioned above, the seam strength remained high at 72% of its initial value. This confirms the performance capabilities of fabrics that are made from SynStron. In addition, a contaminant release additive within the monofilament resulted in the used fabric having 76% of the original air permeability. This provided effective performance of the sheet control system and optimal run of the paper web.

Seam strength profile


After being used by a customer for 446 days, the SynStron dryer fabric still had 72% of its original seam strength.

Laboratory test – seam loop load capacity


High resistance: SynStron can withstand a substantially larger amount of energy before a seam tear.

Wear test


In comparison to standard PET, SynStron achieved, on average, 56% higher abrasion resistance.

Laboratory test – hydrolysis resistance

Laborversuch – Hydrolysebeständigkeit

While standard PET filaments have already torn, after 63 hours in a laboratory test, SynStron still has 60% of its original tear strength.

Standard PET

Herkömmliches PET

SynStron Monofilament

SynStron Monofilament

The SynStron yarn filament is less prone to fibrillation. In contrast, the standard PET filament (left) has numerous small fibrils after a sudden break.

Higher resistance

Dryer fabrics made from standard PET monofilaments are normally removed from the machine due to damage, abrasion or degradation. Seam failure can occur due to fibrillation of the loops or binder yarns causing a tear in the seam. The SynStron monofilament is more resistant to fibrillation; this restricts the penetration of chemicals and moisture into the monofilament resulting in a stronger fabric and seam for higher potential life.

In addition, SynStron offers higher resistance to sudden increases in fabric tension. These increases are normally caused by cylinder wraps during tail threading or paper wads following a break, causing damage and removal of the fabric. A SynStron dryer fabric reduces the risk of damage by absorbing 160% more energy compared to a standard PET fabric.

Increased fabric life due to less abrasion

A Voith Paper laboratory test clearly showed the higher abrasion resistance of the SynStron yarn. The material achieved 56% higher wear resistance than standard PET yarns, leading to a longer potential life of the dryer fabric. Exposure to wear by adverse machine conditions is one of the reasons that dryer fabrics are prematurely removed from the machine. The SynStron fabric has greater resistance to the causes of wear, such as rough or contaminated roll surfaces, filling materials or contact with stabilizer seals. This helps to achieve cost savings for the paper producer.

Hydrolysis resistance improves tear strength

Heat and moisture in the dryer section are the most difficult environmental conditions imaginable for polyester. Their combined effect weakens standard PET and ultimately leads to failure of the material. Again, SynStron monofilaments out perform standard PET. In laboratory tests, degradation can be accelerated in order to simulate paper machine conditions over the life of a fabric. After 63 hours exposure to saturated steam at 140ºC, the standard material had degraded. In contrast, SynStron had retained 60% of its original tear strength to confirm its superiorperformance.