Introduction of PEBA Material And Its Shoe Material Application

Introduction of PEBA Material And Its Shoe Material Application

I. Introduction of PEBA Material

Nylon elastomer, also known as thermoplastic polyamide-based elastomer (TPAE), is a thermoplastic semi-crystalline copolymer composed of rigid polyamide hard segments and flexible polyether or polyester soft segments. Depending on the hard and soft components, there are various types of TPAE. Most nylon elastomers available in the market are polyetheramide block copolymers, abbreviated as PEBA.

The polyether soft segments in nylon elastomers provide excellent flexibility and high resilience, while the polyamide hard segments offer sufficient stiffness and outstanding low-temperature impact resistance. Compared to other thermoplastic elastomers like TPU, SBC, and TPEE, PEBA stands out for its good overall performance, processability, and lightweight nature. It also boasts flexibility, resilience, and low-temperature impact resistance.

Nylon elastomers are characterized by their ultra-light weight, high strength, flexibility, durability, high resilience, high impact resistance, low-temperature resistance, breathability, and permanent anti-static properties. These characteristics make them widely used in sports shoes, sporting goods, consumer electronics, waterproof apparel, and medical care.

II. PEBA Production Process

The production of PEBA involves the polycondensation of polyamide and polyether chain segments. The two primary methods for producing these copolymers are melt polycondensation and solution polycondensation.

In melt polycondensation, polyamide and polyether chains undergo polymerization at high temperatures. The final product is then cooled and formed into pellets. This method is favored for its cost-effectiveness and the excellent mechanical properties of the resulting material.

For example, PEBA materials can be synthesized through a two-step process. Firstly, dicarboxylate-capped polyamide blocks are prepared from lactams and amino acids, using a dibasic acid as the chain terminator. Then, the resulting zwitterionic polymers undergo polycondensation with polyether diols at high temperatures in a vacuum, catalyzed by a transition metal alkoxylate, as illustrated in the figure below.

Solution polycondensation involves dissolving the polyamide and polyether fragments in a common solvent prior to initiating the polymerization reaction. After the reaction, the resulting polymer is precipitated, filtered, and dried. While this method can produce PEBA materials with a broader range of properties, it is generally more expensive and time-consuming than melt polycondensation.

The synthesis of nylon elastomers has a high technical threshold, and there are relatively few global suppliers. Arkema, Evonik, and Ube Kogyo are among the main producers.

III. PEBA Foam Shoe Material Application

Nylon elastomers were initially used in shoe materials as rigid elastic plates, such as in shoe sole support components. In recent years, with the excellent resilience and ultra-low density of PEBA being harnessed through foaming, it has gained popularity as a foaming midsole material.

Due to the high cost of PEBA, it is commonly mixed with EVA, TPU, and other materials for foaming to reduce costs. From the perspective of sports brands' shoe models, PEBA can be applied in a manner similar to ETPU (supercritical foaming) for midsole manufacturing. This involves foaming bead granules and then molding them or foaming sheets and cutting them into midsoles, as well as employing a small-to-large process.

There are numerous cases of advanced technology and applications of nylon elastomers as foam midsoles. For instance, Nike's ZoomX technology, utilized in running shoes like the 4% and NEXT%, exemplifies such innovation.