WHAT IS HYDROLYSIS AND HOW WE PREVENT IT

THE CHALLENGE

One of the main technical challenges with polyurethane is overcoming an ageing deterioration known as ‘hydrolysis’. Hydrolysis is the chemical breakdown of the PU polymer and the resulting physical breakdown of the sole by the attack of water (usually in vapour form), occurring over a period of several years – even when the shoes are in store.

This process is accelerated by warmth and high humidity. It will, therefore, happen more quickly in tropical climates, but also in confined spaces (such as in lockers) if footwear is put away damp. In the most advanced state of hydrolysis, the sole will lose all its physical strength, thus cracking or crumbling.

2 TYPES OF PU

There are 2 types of PU. There is Polyether based PU and Polyester based PU. Polyether based PU has a high resistance against hydrolysis and low oil resistance. Polyester based PU has a low resistance against hydrolysis and high oil resistance.

Safety shoes are always using a polyester based PU. The PU used in Safety Jogger Footwear has been improved to increase the resistance against hydrolysis and therefor preforms better the an average Safety Shoes. The Safety Jogger PU lasts for 4 years in tropical conditions and 8 years in normal conditions. Compared to 1.5 year and 3 year for basic PU compounds used in many safety shoes on the market.