Most outsole of leather shoes is natural rubber or synthetic rubber.
(1) Natural rubber: Its softness and elasticity are excellent, especially when exercising. However, it is not wear-resistant, slippery, and has a short service life, which is mostly used for indoor sports shoes.
(2) Synthetic rubber is divided into several categories:
- Wear-resistant rubber: It has good wear resistance and toughness, and has a long life.
- Environmentally friendly rubber: This material basically contains 10% recycled rubber for environmental protection.
- Air rubber: There is air in the rubber, for shock absorption, but not wear-resistant.
- Sticky Rubber: It's flexible and very slip-resistant.
- Hard Rubber: It is the most comprehensive, tough, non-slip and wear-resistant.
- Carbonized rubber: It is tough and wear-resistant, and is mostly used in running shoes.
(3) Plastic outsole: The raw material is industrial glue, which is rare in daily life, and is characterized by soft and non-slip.
The most commonly used materials for leather shoe midsole are rubber, EVA, PU and MD.
- Rubber: The softness we just said is not bad, but it is too heavy.
- EVA: vinyl acetate copolymer, which is a polymer material. It is very light and has good elasticity and flexibility, but it absorbs water easily and gets dirty easily.
- PU: This material is fine except that it is not called "leather". It has high density, high hardness, and good wear resistance and elasticity.
- PHYLON: Nowadays, most of them are PHYLON midsole, which are light and elastic, and have excellent cushioning performance, also known as "secondary foaming".
The insole is a form of "package midsole", but the difference is that the insole structure is wrapped in the outsole of the shoe.
The inner side of the rubber outsole is covered with a midsole. This midsole is also called "MD midsole", which is a type of EVA one-time foaming.
At present, the technology of shoemaking is becoming more and more advanced. Rubber, PVC, etc. can also be foamed during processing, and the greatly reduced specific gravity can also replace part of PU, and the combined bottom is generally a rubber combination.