EVA foam material and TPU material in the insole

The production of shoes can usually be divided into three major parts: the upper (Upper), the midsole (Midsole), and the outsole (Outsole). The midsole is the soul of the running shoe and the part where the insole is located. The role of the midsole is to provide stability, cushioning, and rebound, to absorb the impact generated by the movement, and to provide protection and a gentler feel for the feet during the movement. The role of the insole in the entire midsole is also significant. The different materials and designs of the insole can enhance the comfort of the shoe but also allows the shoe to have more functionality.

There are many materials used in the production of insoles. This article will mainly talk to you about EVA foam sheet material and TPU Foam material used in insoles production.

EVA foam material

One material that has revolutionized the shoe industry in the past 20 years is EVA. by foaming EVA, the sole can be made light enough to have some elasticity, and EVA resin can make the sole have proper cushioning. Since then, most casual and jogging shoes have used EVA as the sole material.

EVA foaming formula In the shoe industry, in-mold foaming generally refers to EVA particles in the foaming mold, through high temperature (160-180 degrees Celsius) and high pressure (more than 150KG/cm2) to make it foam. . In addition, there are traditional flat foam and injection foam.

EVA foam formula consists of a lubricant (stearic acid), bridging agent (DCP), foaming agent (AC series), foam accelerator (zinc oxide), filler (calcium carbonate), and EVA raw materials. To improve the physical properties of EVA products, a certain percentage of rubber (natural or artificial) is added, and the process is similar to the formulation without rubber.

TPU foam material

In addition to EVA foam, another essential material for shoe soles is TPU thermoplastic polyurethane elastomer. TPU material has better shock absorption and durability than EVA, but the material is heavier than EVA and can quickly turn yellow. In addition, it has the following three advantages.

1. Remarkable plasticity of the formulation, which can be produced from the softest to the hardest by adjusting the formulation.

2. It is exceptionally wear-resistant, two times more wear-resistant than the most wear-resistant natural rubber.

3. Can be made very transparent or any color products.

Because the previous TPU can not be made into microporous foam, it is mainly used for the outsole. The usual practice is to use foam EVA as the midsole and then stick a thin layer of TPU on the bottom to do the outsole so that the shoes are light and wear-resistant. But in recent years, BASF introduced a new foam technology, so TPU has the potential to fully challenge the application of EVA in the shoe material. This foam technology in the industry is also known as "popcorn" (E-TPU). It can make shoes as light as EVA. The key is to have excellent resilience, that is, to have better than EVA. Cushioning effect.

Global EVA production capacity distribution

With the development of the EVA resin industry, the global EVA resin production capacity has grown steadily, and the global EVA production capacity is mainly concentrated in Asia and North America. Among them, the EVA production capacity of the largest countries and regions mainly includes mainland China, the United States, Taiwan, South Korea, and Japan. Mainland China has surpassed the United States to become the world's largest EVA resin production area, with a capacity of 972,000 tons/year.

Foamwell, a professional insole manufacturer can customize EVA insole products and EVA foam sheet suppliers. We have a wealth of EVA channels and can provide high-quality, high-yield EVA foam sheet material.