All-round Application of TPU in Sports Shoes: Upper, Midsole, Outsole

TPU has good processing properties such as injection, extrusion, calendering, blow molding, and molding. It is used in the three major shoemaking projects of soles, uppers, and fitting, and is favored by the majority of shoemakers. As can be seen from the picture below, TPU covers almost the entire range of shoe manufacturing processes.

Category	Shoe Parts	Segmentation Application	Function
Sole components	Sole	Outsole	Wear-resistant, anti-slip
		Midsole	Rebound, shock absorption
		Bottom component & filler	Rebound, shock absorption, balance
Upper assembly components	Upper	Fabric inner membrane	Waterproof and breathable
		Melt-spun spandex	Rebounds, fits and protects
		TPU synthetic leather	Protection and decoration
	Shoe decoration	Printed film	Decoration
		Injection molding	Decoration
	Shoelace	Extrusion assembly	Connection
Shoe body fit	Adhesive	Hot melt adhesive film	Connection
		TPU solvent glue	Connection

The application of TPU in sports shoes is mainly divided into three parts: upper, midsole and outsole.

1. Upper: TPU yarn, leather

Breathable flyknit uppers and waterproof leather uppers are common sneaker uppers. Among them, fly knitting means that the entire upper is woven in one piece. It can be woven with TPU yarn. It is soft and extremely durable. It has high wear resistance and is easy to perform hot pressing 3D shaping, solid shape, etc.

In addition to yarn-woven uppers, TPU can also be made into synthetic leather and used in shoe uppers, decorative sheets, etc.

2. Shoe midsole: ETPU

Shoe midsoles are the most popular and mature component of TPU sports shoes. A common process is to make TPU into foam particles through a supercritical kettle foaming process, and combine it with water vapor or microwave molding to obtain ETPU shoe midsoles. Compared with traditional EVA midsoles, E-TPU shoe materials have excellent resilience, extremely low compression permanent deformation, and a good wearing feel.

Then TPU insoles are also prepared through the foaming process. They are first foamed into sheets and then cut. Currently, there are still very few applications.

3. Shoe outsole: wear-resistant, anti-slip TPU

TPU can be used to obtain shoe outsoles through injection molding, which has the characteristics of wear resistance and high strength. In addition, the anti-slip effect is also one of the important indicators for judging the performance of TPU shoe outsoles.

In addition to the uppers, midsoles, and outsoles above, TPU's applications in sports shoes include anti-torsion sheets, heel sheaths, hot melt adhesives, films, and more.

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