Polyurethane

Definition and Overview

Polyurethane is a synthetic fiber with excellent stretch and recovery properties. Rather than using it alone as the main component of a textile, it is used in small amounts blended with polyester, nylon, cotton, rayon, and others to provide ease of movement and a good fit when worn.

Polyurethane elastic fiber for clothing 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.

Characteristics

Its defining feature is high extensibility and the tendency to return to its original shape when the force is released. When blended into a textile, it improves conformity to the body and helps reduce tightness at bending areas such as the knees and elbows.

On the other hand, heat, ultraviolet light, sweat, chlorine, sebum, and aging can reduce stretch and recovery. Not only the blend ratio, but also the companion material, knitting or weaving structure, and dyeing and finishing process affect the performance and hand of the textile.

• In woven fabrics, it is used to add stretch.
• In knits, it helps adjust rebound, that is, the force that returns the fabric after it has been stretched.
• While it improves fit, excessive stretching may deform the textile.

Main Applications

It is used in items that require conformity to body movement and moderate compression, such as cut-and-sewn garments, innerwear, leggings, pants, jersey items, sportswear, lingerie, and swimwear. Depending on the application, materials that stretch in the warp direction, weft direction, or both are selected.

It is also blended into shirting fabrics, denim-like materials, uniforms, and workwear to secure a range of motion. However, even with the same polyurethane blend, suitable items and seasons differ depending on textile thickness, structure, and the companion material used in the blend.

Selection and Handling Notes

When selecting, do not judge only by the blend ratio; actually check the required stretch direction, stretch rate, recovery, industry weight, thickness, and sheerness. For body-fitting applications, testing and wearing checks that assume whether the shape is maintained after repeated putting on and taking off are important.

For washing and storage, follow the care instructions on the product. In general, high-heat drying, high-heat ironing settings, prolonged direct sunlight, and chlorine bleach can all cause deterioration. For swimwear, rinse promptly after wearing so that chlorine and seawater are not left behind.

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

Differences from Similar Terms

Stretch is a broad term for the property of a textile to stretch or for the processing that gives it that property. Polyurethane is a representative fiber used to impart stretch, but because stretch can also come from the structure or finishing process, not all stretch materials contain polyurethane.

TPU stands for thermoplastic polyurethane, which refers to a polyurethane material that is easy to shape by heating. In clothing, it may be used for film, lamination, and printing, and its applications and processing form differ from those of ordinary polyurethane elastic fiber.

Frequently Asked Questions

Does a higher polyurethane blend ratio mean higher stretch?

The blend ratio affects stretch, but a higher ratio is not always easier to use. The way it stretches and returns varies depending on the structure, yarn usage, companion material, and textile density. Select it after checking the required range of motion, fit, and durability for the application.

Can polyurethane-blend textiles be machine washed at home?

Many products can be machine washed at home, but the specifications vary depending on the material composition and processing. High-temperature drying and high-temperature ironing can reduce elasticity, so always check the care label for each product and avoid excessive heat.

What is the difference between polyurethane and stretch?

Polyurethane is the name of a fiber blended in to provide stretch. Stretch is a general term for the property of a textile to stretch and also includes stretch created by the polyurethane blend, as well as by knit structures, woven structures, and processing.