The use of polyurethane microcellular elastomers to make shoe soles began around 1960. The United Kingdom, Japan, Germany, Austria and other countries successively promoted the use of polyurethane foam materials in the shoe industry around 1967, because of its excellent performance in the shoe industry. By 1974, the soles made of polyurethane foam in Western European countries had developed to about 160 million pairs, accounting for about 20% of their total output.
In the footwear industry, thanks to the use of polyurethane foam, shoes are not only light and comfortable, but also extremely wear-resistant. In terms of production efficiency, it has also been greatly improved due to the unique processing technology, so that this material has developed rapidly in the shoe industry. At present, in the materials used in the footwear industry, polyurethane foam has accounted for 6% to 8% of all materials.
The sole characteristics of microcellular polyurethane elastomer are as follows:
01 Polyurethane microcellular elastomer is low density yet soft, comfortable and light to wear. The density of rubber and plastic soles such as ordinary rubber and PVC is usually 1.2~1.48g/cm3. Even if they are foamed, their density can only be around 0.8g/cm3. The density of polyurethane microcellular elastomer soles is below 0.6g/cm3.
02 Polyurethane soles have good dimensional stability and long durability. Practice has proved that the storage life of high-performance polyurethane soles is at least 10 years. A 7-day accelerated aging simulation test was carried out at 100% relative humidity at 70°C and 80°C (equivalent to 10 years of storage in an ordinary environment. The results showed that the properties of the polyurethane material did not change significantly within 7 days, while other materials prepared The outsole, under the same test conditions, has been completely destroyed.
03 The polyurethane sole has excellent wear resistance and fully meets the strict German industrial standards. According to the comparative experiments done by the British SA-TRA shoemaking research institute, the wear resistance of the polyurethane outsole is obviously better than that of the ordinary rubber outsole, while the dual-density polyurethane sole (with medium density midsole and high density The wear resistance of the outsole) is more significant.
04 Polyurethane shoes have excellent flex resistance. In the process of wearing and walking, the shoes have to withstand large flexing and bending. The flexural resistance of the urethane sole can exceed 250,000 times, which is much better than that of other material soles. The flexural resistance is even better.
05 The chemical resistance of polyurethane soles is better than that of other commonly used sole materials. For example, its resistance to petroleum and petroleum-based fuels is significantly better than that of general plastic and rubber materials; its alkali resistance is similar to that of ordinary rubber materials, but in terms of acid resistance, polyurethane soles It is worse than the rubber sole.
06 The shoes prepared by using the polyurethane microporous elastomer have good cushioning performance and have a good protective effect on human feet. Because of this, at present, most sports soles use polyurethane material as the material of choice.
Polyurethane soles have better temperature resistance. For example, the working environment of the iron and steel industry, machinery industry, etc. has a high temperature or there are often high-temperature iron filings, waste residues and other objects. Labor insurance work shoes working in such occasions must have high temperature resistance. Generally speaking, rubber materials have the best heat resistance, thermoplastic materials such as PVC are the worst, and polyurethane materials are in the middle. It can withstand high temperatures of 150 ° C for a limited time, but its thermal insulation performance is the best.
