1. INTRODUCTION

Picking a proper sewing yarn can improve the air filter bag’s performance. Engineered to deliver performance in stitches and seams, this kind of thread may fit a wide range of business due to its heat, corrosion and oxidation resistance, high tear resistance and the long length without knots. By working in high temperatures and corrosive gases in the dust filter, an adequate sewing yarn can increase the life of filter bags and improve the proximity efficiency. 

Sewing yarns that are engineered and designed to pass through a sewing machine rapidly, forming efficient stitches without breaking or becoming distorted during the use of the product. Generally, filter bags are manufactured with sewing yarn made from PTFE, Acryl, Aramid, Polyester, Polypropylene, Polyethylene.

To properly suit the needs of different fields, the products can be customized according to the client’s demands, DLTT can even provide professional advice on which option suits your working condition best. Feel free to reach us regarding recommendations or support through our website’s Contact section.

The PTFE thread has specially proven itself efficient in many applications. Beyond sewing ability, it will last for years under the most extreme conditions. PTFE sewing thread is mainly used for sewing filter bag with high temperature resistance. Depending on what you are looking to achieve, PTFE may or may not be the best fit for your application. 

PTFE is a polymer with a very low coefficient of friction and excellent chemical, temperature, and environmental resistant properties. PTFE can be manufactured as a fiber or thread for a broad range of applications including filtration, outdoor fabrics, electrical cables, and protective garments. 

DLTT offers PTFE yarns whose unique properties such as excellent thermal stability, exceptional corrosion resistance and anti-hydrolysis or oxygen reaction make it the best choice for a variety of applications.

Yarn: due to different yarn types, woven fabrics can have customized filtering performance. Yarns can be made either from short staple length fibers (spun yarns) or from filament fibers (filament yarns). To learn more, visit our technical Yarn page. 

Manufacturing: PTFE filaments are manufactured by the continuous formation process to ensure the stable performances of threads, using a paste extrusion process that guarantees uniform  distribution  of  diameter,  low shrinkage, and stable stretchability.   

Sewability: sewability of thread is a term used to describe a sewing thread’s performance. A thread with good sewability is uniform in diameter and has good surface finish. Longitudinal uniformity of thread contributes to uniform strength and reduced friction. By passing through the stitch efficiently, it minimises thread breakages, lowering the cost with rethreading machines and repairing stitches, and also improving the quality of the product.

Chemical proprieties: there are only a few chemicals that can affect PTFE fibers. Elementary alkali metals, such as sodium, can permanently damage the material. PTFE will repel most chemicals, this is what makes it a very effective filtration media. 

Uv resistance: unlike polyester and nylon, PTFE fibers do not degrade in the presence of UV light, maintaining their tensile properties indefinitely and making PTFE ideal for sewing outdoor fabrics. Although polyester is twice as strong as PTFE prior to UV light exposure, the strength retention advantages of PTFE can only be seen over an extended period time.

Breaking strength: the tension at which a thread breaks, expressed in grams or kilograms.

Breaking tenacity: the relative strength obtained by dividing the tensile strength by the thickness of the structure.

Elongation at break: the amount by which a thread is extended at its breaking point expressed as a percentage of its original length.

Elasticity: good elasticity enables the thread to recover its original length immediately after the tension has been released. The elasticity of sewing thread affects the strength and the finished quality of a stitched seam.

Heat-shrinkage: the amount by which a thread contracts under the action of washing or heating. Low shrinkage yarn used on fabric material with higher shrinkage reduces the chances of seam puckering.

Moisture regain: is the weight of moisture in an yarn or thread expressed as a percentage of weight of completely dry material.

Minimum loop strength: is the strength of the weakest loop in a series of loops tested in a continuous length of thread.

Thickness: yarn should be as fine as possible depending on the required strength of seam. Thicker threads have generally greater strength, given the same fibre content and yarn structure. On the other hand, threads tend to blend into the fabric surface and are less subject to abrasion. Finer yarns perform better with finer needles and produce less fabric distortion.

In an industrial environment, threads must be away from the fire to avoid the formation of harmful chemical gases. Firing the blend trash including  PTFE and conventional could result in the formation of poisonous gases and air pollution, which is prohibited. Additionally, the non-degradable  PTFE  materials  need  to  be  collected  and destroyed with correct and approved method. Therefore,  PTFE threads are ought to be used reasonably.Due to the high self -lubricating property, PTFE threads may detach  from  the  needle  pinhole,  forcing to interrupt the sewing operation. Hence, the sewing needles need to be covered with special silicone oil to avoid  the separation between threads and needles. 

Finishes are given to a thread for both improving sewability or achieving a specific functional requirement. Some finishes increases strength, abrasion resistance and lubrication of the thread. While some finishes also include bonding, non-wick, anti-fungal, fire retardant, water repellent and anti-static finishes.

Acryl: acryl yarn offers a affordable and durable option. It is easily washed, has good stitch definition and non-allergenic features.

Aramid: aramid offers high strength and fire retardant properties. The unique nature and manufacturing processes for producing aramid fibers are some reasons why it is much more expensive than other fibers. Aramid also has high tensile strength, high melting point and abrasion resistance. 

Polyester: Polyester yarn has high strength, tenacity and creep resistance. Because of its high melting point, this type of yarn withstands high temperature washing and drying. It is resistant to most chemicals, has good flame resistance, flame retardant properties. Polyester is less hydrophobic, which means that it requires additives or coating to prevent wicking. It is also susceptible to damage if exposed to highly alkaline chemicals. 

Polypropylene: about 25% less dense than most fabric, Polypropylene is more hydrophobic, which means it absorbs less water and therefore dries faster. This type of fabric retains more heat and it is inert to most chemicals. Polypropylene characteristics include a lower melting point, poor UV resistance and strength, requiring larger thread or yarn to meet strength targets. Its lower creep resistance inflicts in higher elongation. Polypropylene has poor abrasion resistance and it is not suitable for high speed sewing applications. 

Polyethylene: Due to its recyclability, polyethylene is an environmentally friendly fabric that is also suitable for drinking water and is long term reliable. Polyethylene is durable and tough, it is resistant to corrosion and has freeze-break features.

Fiberglass, Polyester, PTFE, PPS, Nomex, FMS and more.