Ultra Low Density PU Slipper System

PU system sector is among the most productive and dynamic fields in terms of new product development in the chemical sectors. If the lives of the products of this sector are examined, the fast life cycle of the products can be seen.

In this field, the products having higher mechanical properties, which are softer, more
flexible and less denser systems are developed and introduced into the market.

The density change in PU footwear systems could be the best example for this subject. In 1990’s the moulded density of shoe soles is 600 kg/m3, it dropped to 450-600 kg/m3 in 2000’s and then dropped to 350-500 kg/ m3 in 2010’s.

Nowadays the shoe soles’ moulded density is 350-450 kg/m3 while the slipper soles’ moulded density is 250-300 kg/m3 as standard values. In near future, it is foreseen that 200-250 kg/m3 moulded density slipper systems will be commonly used.

The prominent benefits of developing low density footwear systems are as below:
• Low cost (lower consumption of raw materials),
• The increased competitiveness of PU against EVA and other polymers,
• Comfort and lightness,
• Flexibility in shoe design (elimination of weight problem for big shoes),
• Environmental impact reduction (decrease in raw material consumption and wastes).

The motivation for developing the low density products increased while the economic
problems, reduction in purchasing power and escalation of raw material prices appeared in the recent years.

Therefore the producers in the footwear sector are seeking for the low quality raw
material and / or low cost filler material to deal with those difficulties. However, these solutions adversely affect the usage life, flexibility and mechanical / physical properties of the product.

PU system houses accelerated their studies for the low density products aiming at reducing
the cost of footwear manufacturers without any degradation in the final product quality.

In the recent years, the advancements in PU sector made the development of low
density slipper systems easier. The novel resins and additives developed by Poleks Kimya made the ultra low density slipper systems possible.

Besides, the developments of new generation surface active materials (silicones etc.) which affect the cell structure and openness and new generation catalysts which adjust the PU reaction rate by the global producers, contributed to the development of low density systems.

Poleks Kimya, with the vast product range for footwear (FootPUR) is one of the prominent system houses in this field. In this product family, there are systems of different density, hardness, flexibility and reaction rate (more than 20 products with different properties).

Especially low density, low hardness and high flexibility systems come to the front in this product range. Poleks Kimya R&D team has completed the R&D studies for the ultra low density slipper system and has successfully completed the pilot production of the system
and customer trials.

The ultra low density slipper system developed by Poleks Kimya R&D team has 25% lower moulded density comparing to standard products. Dimensional stability, cell structure, skin quality and mechanical properties become critical in low density slippers. Poleks Kimya ultra low density slipper system gives good results as much as standard slipper systems (Table 1).

The system has a wide range of working ratio, good flowability in the mould and fast demoulding time. The product has high flexibility, fast rebound, fine cell structure, smooth skin and little hot / cold temperature sensitivity.

Besides, this product can be used as a light and comfortable middle-sole system in the double density systems.

However, Poleks Kimya can develop systems of different properties (harder / softer or faster / slower reaction rate etc.) depending on the customers’ demands by making small changes on the product.

Yücel Aktay – Kimya Yüksek Mühendisi
R&D and Technical Support Specialist
Poleks Kimya San. ve Tic. A.Ş.

Dr. Murat Baranak – Kimya Mühendisi
R&D and Quality Control Manager
Poleks Kimya San. ve Tic. A.Ş.

Cihat Mıhla – Kimya Mühendisi
R&D and Technical Support Specialist
Poleks Kimya San. ve Tic. A.Ş.

Mesut Gürgen – Kimyager
Technical Support and Business
Development Executive