Ultra-Low Density PU System for Slippers

Ultra Low Density PU Slipper System The polyurethane system sector represents one of the most productive and dynamic fields within the chemical industry in terms of new product development. An examination of product lifecycles reveals rapid turnover in this sector. Continuously, systems with higher mechanical properties, greater softness, increased flexibility, and lower density are being developed and introduced to market in this field. The density changes in PU footwear systems provide one of the best examples of this trend. In the 1990s, shoe systems had a mold density of 600 kg/m³, which decreased to 450-600 kg/m³ in the 2000s and to the 350-500 kg/m³ range in the 2010s. Today, mold densities of 350-450 kg/m³ for insole systems and 250-300 kg/m³ for slipper systems have become nearly standard values. It is anticipated that slipper systems with mold densities of 200-250 kg/m³ will become widely adopted in the coming period. The leading benefits to be achieved in developing low-density footwear systems are listed below: • Lower cost (reduced raw material consumption), • Enhanced competitive position of PU against EVA and other materials, • Comfort and lightweight properties, • Design flexibility in footwear (reduced weight issues in larger sizes), • Reduced environmental impact (lower raw material consumption and waste generation). The motivation for developing low-density products has been further intensified by recent economic challenges, declining purchasing power, and rising raw material costs. For this reason, manufacturers in the footwear sector have been forced to seek alternatives, such as the use of lower-quality materials and inexpensive fillers, to cope with these difficulties. These methods negatively affect the lifespan of the final product, flexing endurance (step count, etc.), and mechanical and physical properties. Polyurethane system manufacturers have therefore accelerated their efforts to develop low-density systems that reduce production costs without compromising final product quality. Recent developments in the PU sector have facilitated the development of low-density slipper systems. Innovative resins and additives developed by Poleks Kimya have enabled the production of ultra low-density slipper systems. Additionally, the development of next-generation surfactants (silicone, etc.) that affect cell structure, openness and distribution, and next-generation catalysts that enable and accelerate PU reactions by global manufacturers have contributed to the advancement of low-density systems. Poleks Kimya is one of the leading system manufacturers in this field with its broad product family for footwear applications (FootPUR). This product family includes systems with varying density, flexibility, hardness, and reaction speed characteristics (more than 20 systems with different properties). Particularly notable in this product group are systems featuring low density, low hardness, and high flexibility properties. The Poleks Kimya R&D team successfully completed R&D activities, pilot production, and customer trials of the Ultra Low Density Slipper System during 2022. The ultra low-density slipper system developed by the Poleks Kimya R&D team has an average mold density 25% lower than standard products. In low-density slippers, dimensional stability, cell structure, skin quality, and mechanical properties become critical. The Poleks Kimya ultra low-density slipper system delivers results in physical properties at least as good as standard products (Table 1). The system features a wide processing ratio range, good flow in the mold, and rapid mold opening time. The product exhibits high flexibility, rapid rebound properties, dense internal cell structure, smooth skin feel, and low susceptibility to temperature variations. Additionally, this product is anticipated to be usable as a lightweight and comfortable midsole system in dual-density applications. Additionally, with minor modifications to the product, Poleks Kimya is able to develop systems with different properties (harder/softer, slower/faster, etc.) according to customer requirements.     Yücel Aktay - Chemical Engineer R&D and Technical Support Manager Poleks Kimya San. and Tic. A.Ş. Dr. Murat Baranak - Chemical Engineer R&D and Quality Control Manager Poleks Kimya San. and Tic. A.Ş. Cihat Mıhla - Chemical Engineer R&D and Technical Support Manager Poleks Kimya San. and Tic. A.Ş. Mesut Gürgen - Chemist Technical Support and Business Development Manager Poleks Kimya San. and Tic. A.Ş.