Jun. 26, 2019
The Double Density Safety Shoe Sole Pu used in the preparation of polyurethane soles are mainly MDI and its liquefied modified MDI varieties (also known as liquefied MDI); it has the advantages of low vapor pressure and low hazard to the working environment and operators. At the same time, the reaction is easy to control, and the resulting microcellular polyurethane elastomer has good mechanical properties and excellent wear resistance and flexural resistance. The disadvantage is mainly due to the direct connection of the nitrogen atom of MDI to the aromatic ring structure, which is prone to yellowing during long-term use.
In the use of MDI, the hydrolyzed chlorine and acid value indicators of MDI should be strictly controlled. The higher of these two indexes will reduce the reaction rate of isocyanate and polyol, or reduce the catalytic efficiency of the basic catalyst, affecting normal production. Process performance. At present, the factory producing MDI in China is Yantai Fanghua Synthetic Leather Group Co., Ltd. (formerly Yantai Synthetic Leather Factory). The original designed production capacity is 10kt/a (MDI-PAPI co-production), which is gradually transformed and expanded. It has been raised to 15~20kt/a, which has changed the situation that China's MDI basic raw materials have long relied on imports, which has effectively promoted the development of polyurethane materials in China's footwear industry.