Kimfoot NG New Generation Footwear Systems

Slippers are an integral part of our daily life. The dictionary definition of the word "slipper" is described as 'felt placed under the foot to absorb perspiration'. This explanation actually reveals the purpose for which slippers have been used for many years. The first slippers were heelless, open-sided shoes that began to be worn in Europe in the 1400s. By the 1900s, members of the Ottoman palace had also begun wearing long-heeled slippers. In today's conditions, like many things, slippers have also undergone revision to become more modern and practically applicable. Polyurethane slipper soles have superior mechanical properties compared to alternative sole products (rubber, EVA, etc.). They are preferred because they are resistant to wear and have the potential to be produced in different shapes and colors. These choices are designed with properties that align with trends, comfort, durability, flexibility, and lightness. The internal structure of polyurethane soles is porous and sponge-like. For this reason, their specific gravity is quite low. Due to these properties, they can be easily used in thick or padded soles as well as thin soles. Polyurethane soles are widely used in the sole sector not only because of their lightness but also because of their high slip resistance. KIMfoot NG systems are three-component systems (polyester + catalyst + isocyanate) designed for summer and spring slipper soles as well as high-heel hard summer sole production. KIMfoot NG systems have established their market position with a wide product range such as density of 300-360 kg/m³ and hardness values in the range of 50-70 shA.

Chart 1. KIMfoot NG systems average density (kg/m³) – hardness (shA) data example

Polyurethane slipper sole manufacturers produce pressings at different densities, shapes, and hardness values using low-pressure casting machines. It is very important that these pressed soles do not shrink or lose their shape immediately after production or afterwards. We conduct our research and development work in our simulation center with low-pressure machines and necessary equipment, taking into account customer conditions.

The main outstanding features of KIMfoot NG systems are as follows;

• Wide ratio tolerance range, • High flex property (step count), • Capability to work in different hardness ranges, • Low and high density, • Increasing production efficiency with short mold opening times. Polyurethane is formed as a result of the reaction between an isocyanate group and a glycol group. The active group of the isocyanate component is -NCO while the active group of glycol is -OH. When the number of -NCO and -OH groups reacting is equal, the isocyanate/polyol ratio is stoichiometrically 1. This ratio is called index, and an NCO/OH ratio of 1 means an index of 100. An index of 100 is calculated in sole groups and is the only ratio. Working at the correct ratio is of great importance. Otherwise, various problems can be encountered in the final product. If NCO groups are excessive, a hard structure forms, and if NCO groups are insufficient, a soft, muddy structure forms. A distinguishing feature of the KIMfoot NG system is that even if this ratio is slightly high or low, it does not cause any problems in the product's working performance and in the final product. For example, in a NG system, the hardness values measured with a penetrometer immediately after completion of the polyurethane reaction at index 100 ratio and at ratios below and above index 100 under laboratory conditions are very close to each other. This provides defect coverage and ease of operation under process conditions. Chart-2

Chart 2. Hardness graph of a KIMfoot NG system according to ratio values

According to TS EN ISO 20344 standard, shoe soles should have a minimum of 30,000 steps. Although there is no such standard in slipper sole systems, the new-generation KIMfoot NG systems provide this standard. Additionally, because the product's flow in the mold, spreading, mold filling, skin formation, and mold opening time are short, its performance in series production is quite high. With KIMfoot NG systems, slipper sole production can be carried out without problems over a wide hardness and density range, and at the same time, it can be worked over a wide ratio range, which has drawn attention and continues to grow its market volume. Derya Tekin Head of Research and Development Footwear Systems Kimteks Poliüretan San. ve Tic. A.Ş.         Seçil Akıncı Head of Research and Development Footwear Systems Kimteks Poliüretan San. ve Tic. A.Ş.