What are PU injection safety shoes?

The injection method is a popular way to create a safety footwear, the sole is directly attached to the upper injected by a plastic material (usually PU), after the injection and during the cooling time, the upper and the outsole bind together very strongly.

What types of outsole used for injection safety shoes?

1.    PU Single density: the midsole and outsole are made of one density PU, It has a good resistance to chemical agents and hydrocarbons, but no resistance to strong acids. It can be produced by adding antistic agent, to achieve the antistatic performance requirements. This outsole also has the advantages of convenient in manufacture ,lower requirement of mould and low cost etc.

2.    PU/PU: is a double-density sole made of PU (the midsole and outsole are made of different density PU). It has some excellent benefits that single density doesn’t has. It can be made of two colors (outsole one color, midsole the other color),making the whole shoe look more better. Normally the outsole is made of low density, so it provides a high abrasion working surface and the midsole made of high density PU, so the soft PU midsole provides good impact absorption and wearing comfort. Whether you are standing, moving or walking, the main stressed area for single density outsole is the whole outsole; but for dual density outsole, the soft PU midsole can share the stress, folding capability of outsole is improved, so the shoes are durable.

3.    PU/TPU: the midsole is made of PU and outsole is made of TPU. The outsole (TPU) is made previously, in a separate process. The sole is attached to upper injected by PU material.TPU, thermoplastic polyurethane is a special type of polyurethane. It is particularly sturdy, abrasion-resistant and flexible. It can be made in all possible colors including translucent colors. It has higher resistance to the cold, but not very resistant to high temperatures. It is more durable than PU and the cost also higher than PU.

4.    PU/RUBBER: the midsole is made of PU and outsole is made of rubber. It’s process is same as PU/TPU, the outsole (rubber) is made previously, and attached to upper by PU. Rubber outsoles are exceptionally sturdy: temperature-resistant from -22 up to 572°F, hard to penetrate from sharp objects and resistant to fuel, oil, microbes and numerous chemicals. However, rubber is heavier than PU and TPU, and is less flexible when submitted to cold temperatures. Another great characteristic of the rubber outsoles is the very low hydrolysis，so its storage longevity is higher than the other materials. Rubber outsoles are also known for the great slip resistance, comparable to PU and TPU，of course the cost higher than PU.

This is a general overview of PU injection safety shoes, for more information about the safety shoes, please click HERE!