1. What is polyurethane (PU)?
Polyurethane is the abbreviation of polyurethane. It is a polymer compound containing many repeating amino groups on the polymer backbone, and is formed by a chemical reaction between isocyanate and polyol compound.
2. What kind of sole uses polyurethane?
Polyurethane for shoe soles is a microporous elastomer between rubber and plastic. It is a microporous elastic structure with open cells. The cell diameter is 0.01~0.1mm, and the free foaming density is 0.25~0.35, (molding density 0.3~1) , Usually 1~2mm self-skinning, with superior resilience and great energy absorption capacity. Polyurethane is widely used in the soles of men’s and women’s leather shoes and safety shoes. The sole of Chining safety shoes is made of thermoplastic foamed polyurethane material (PU for short), which is lightweight, high wear resistance, high elasticity, plus the use of imported additives/high-end technology, and is resistant to hydrolysis, medium and low concentrations of acids, alkalis, and organic Excellent properties such as solvent and anti-aging!
3. Why is polyurethane an ideal material for the soles of safety shoes?
1. Polyurethane sole has the characteristics of lightness, warmth, oil resistance, flex resistance, and abrasion resistance. It is more than 6 times more wear-resistant than rubber. Its density and hardness can be adjusted in a wide range according to the requirements of use. It can be made into two-color (dual-density). ) Double-layer sole, the bottom is a micro-foamed high wear-resistant working surface, and the inner sole is a comfortable elastic foam.
2. Extremely light, with a specific gravity of only 0.3-0.8, which is much lighter than commonly used sole materials. It is more suitable for thick-soled shoes that require impact resistance and perforation resistance. 45% of safety shoes (labor protection shoes) in the world use polyurethane (PU) soles .
3. Lower mold requirements, convenient production and investment savings (the pressure on the mold during foaming is small, only 0.14~0.2Mpa).
4. The molding method is simple, and it can produce both soles and continuous shoes. The variety and output are flexible and suitable for modern industrial production.
4.the production process of polyurethane soles?
The raw materials of components A and B are completely melted in the raw material preheating oven. Add C (catalyst) and color paste to the A material as required, and add them to the original liquid tank of the sole forming machine. Adjust according to the formula requirements and the pouring volume. The two components (A1, A2 and B) are metering pump speeds. The two groups of raw liquids are mixed evenly at high speed in the mixing device and chemically reacted. The mixture is poured into the shoe mold (the size of the shoe mold cavity is adjusted by the computer The pouring time set by the programmable controller). After capping, the shoe mold is sent to the circular production line drying tunnel for heating and curing (the two-color sole must be cured and then poured a second time), and the cured PU sole is demoulded and trimmed , Finishing and inspection is the finished product. After the shoe mold is sprayed with release agent, it is sent for pouring. The speed of the production line can be adjusted according to the maturation requirements of the original liquid during the entire production cycle.