Polyurethane

Definition and Overview

Polyurethane is a synthetic fiber with excellent stretch and recovery. Rather than using it as the main component of a textile on its own, it is mixed in small amounts with polyester, nylon, cotton, rayon, and other fibers to improve ease of movement and fit in clothing.

Polyurethane elastic fiber for apparel is also called spandex or elastane depending on the country, region, and labeling standards. Although the name differs, it generally refers to the same type of fiber that provides stretch.

Features

Its defining characteristics are high stretch and the ability to return to its original shape when the force is released. When blended into a textile, it improves body conformity and helps reduce pulling at bent areas such as the knees and elbows.

On the other hand, heat, ultraviolet light, sweat, chlorine, sebum, and aging can reduce stretch and recovery. In addition to the blend ratio, the companion material, woven or knitted structure, and dyeing and finishing process also affect the performance and hand of the textile.

• In woven fabrics, it is used to add stretch.
• In knits, it helps adjust rebound, meaning the force that returns the fabric after it is stretched.
• While it improves fit, excessive stretching can cause deformation of the textile.

Main Applications

It is used in cut-and-sew items, innerwear, leggings, pants, jerseys, sportswear, lingerie, swimwear, and other products that require body movement followability and moderate compression. Depending on the application, materials that stretch in the warp direction, weft direction, or both are selected.

It is also blended into shirting materials, denim-look materials, uniforms, and workwear to secure ease of movement. However, even with the same polyurethane blend, suitable items and seasons differ depending on the textile thickness, structure, and blend partner.

Selection and Handling Notes

When selecting, do not judge by blend ratio alone; check the required stretch direction, stretch rate, recovery, fabric weight, thickness, and sheerness in actual samples. For close-fitting applications, it is important to test and confirm whether the shape is maintained even after repeated putting on and taking off.

Wash and store according to the product care label. In general, high-heat drying, high-heat ironing, long exposure to direct sunlight, and chlorine bleach may cause deterioration. For swimwear, rinse promptly after wearing so that chlorine and seawater do not remain.

In sewing, stitching while pulling the fabric can cause seam waviness and dimensional defects. Consider the stitching method, sewing thread, and needle that can follow stretch, and confirm the sewing conditions and seam stretch before mass production.

Differences from Similar Terms

Stretch is a broad term for a fabric's ability to stretch or the process of giving it that property. Polyurethane is a representative fiber used to provide stretch, but not all stretch materials contain polyurethane because stretch can also come from structure or processing.

TPU stands for thermoplastic polyurethane, a polyurethane material that can be shaped by heating. In apparel, it may be used in films, laminates, and prints, and its applications and processing form differ from those of ordinary polyurethane elastic fiber.

Frequently Asked Questions