Sole material: rubber, PU, PVC, TPR, EVA, MODEL, injection film
Rubber: used in many sports shoe outsoles, divided into natural and synthetic, wear-resistant, good elasticity, more substantial, and high cost.
Advantages: excellent abrasion resistance, non-slip, elastic, not easy to break, superior softness, excellent elongation, stable shrinkage, good hardness, excellent flexibility.
Disadvantages: substantial, easy to spit cream (quality problem), not natural to destroy (environmental protection problem).
PU: high molecular polyurethane synthetic material, often used in the midsole of basketball and tennis shoes, but also directly used in the sole of casual shoes. It has excellent wear resistance and repeated bending performance, good tear strength and elasticity, excellent oil resistance, acid and alkali resistance, and low-temperature resistance. The waste PU bottom can be automatically degraded, which is beneficial to environmental protection. Thick-soled shoes are more suitable, but there are problems such as yellowing, hydrolysis, cracking, and easy opening—common materials for air cushion shoes and football shoes.
PVC: Synthetic resin, low-end to mid-end, less used due to ecological and environmental problems, air cushion shoes and football shoes are more common.
TPR: T: heat; P: plastic; R: rubber; injection moulded with TPR pellets after hot melting, commonly used for jogging, jogging, casual shoe midsoles, and outsoles.
Advantages: comfortable to shape and cheap;
Disadvantages: the material is heavy, not wear-resistant, the softness is weak, the folding resistance is not excellent, and the shock absorption ability is reduced.
EVA: (E vinyl, VA vinyl acetate): The more vinyl acetate, the better the elasticity; the fineness, uniformity and lightness. They are commonly used for jogging, jogging, casual shoes, foot training shoe midsoles.
Advantages: lightweight, good elasticity, good flexibility, not easy to wrinkle, with excellent colouring, suitable for various climates.
Disadvantages: easy to absorb water, not easy to destroy, unfavourable to environmental protection, and easy to dirty.
PHYLON (MD): It is a secondary high-pressure moulded product of EVA. It is the primary material for the midsole of jogging, tennis shoes, and basketball shoes in the world. It can also be used for the outsole of casual shoes.
Disadvantages: It is not easy to destroy and is not environmentally friendly. It is easy to wrinkle and shrink at high temperatures.
Injection film: also called TPU bracket, used for support, protection, decoration, anti-twist and shock absorption.
TPR has a high specific gravity, heaviness, general elasticity and general wear resistance. The rubber sole also has a more considerable specific gravity, but it is softer, very wear-resistant, has a firm grip, but has reduced elasticity. It is generally used in indoor football and casual shoes. The EVA bottom is very light and elastic, but the flexibility is reduced after wearing it for a long time, and it becomes a little more robust. The PU and MD bottoms are flexible and do not deform for a long time. They are more flexible and comfortable during exercise. The specific gravity is small and very light. Therefore, they are widely used (PU is denser than MD and has better shock absorption, but it is also relatively heavy). Generally, large negatives are made of rubber, which is wear-resistant and non-slip.
The materials of the outsole are generally natural rubber or synthetic rubber and reinforcing agents used. Because the outsole is located at the outermost bottom of the shoe, it should play a useful role in non-slip, wear-resistant, and anti-corrosion. The advantage of natural rubber is that it is very soft, elastic and kind, but the disadvantage is also apparent is that the wear resistance is not very good. To make up for the shortcomings of natural rubber, you need to use other synthetic rubbers to achieve better overall performance, such as adding BR to make the soles more wear-resistant.
Outsole technology: Non-Marking, which is the most common, meaning no traces, the soles will not leave marks when the floor is rubbed to stain the deck. It can be checked by kneading the sole on white paper. adiWEAR, which means super wear-resistant material, the standard DIN friction loss standard for rubber soles is within 80 cubic millimetres, while the DIN friction loss standard for super wear-resistant rubber is within 40 cubic millimetres. Generally, the bottom is not made of super wear-resistant rubber. Still, it is used for parts with considerable friction such as heels, forefoot, etc., and ordinary rubber is used in other places.
Most of the materials used in sports shoe midsoles are PHYLON midsoles and EVA midsoles. Both midsoles are made of EVA, but why is there a difference in terms? PHYLON originated in the United States. The earliest shoe midsoles were all called PHYLON. There was no difference between EVA midsoles and PHYLON midsoles. Later, with the continuous development of footwear products, some major brand footwear product development plants in Taiwan and South Korea At the source, the name of the midsole is more systematic, and we have what we now call EVA midsole. Let me talk about the difference between EVA midsole and PHYLON midsole.
At present, the most used shoe midsole is the PHYLON midsole. The most prominent feature of PHYLON is its lightness, good elasticity, and excellent cushioning performance. PHYLON is called secondary foam. The EVA midsole is also very light, but the cushioning performance and flexibility are far inferior to the PHYLON midsole, and the cost is much lower than the PHYLON. The EVA midsole is called a foam. The reason why they have the same properties, different names, and various performances is that PHYLON is a secondary foam, and EVA is a primary foam. Most basketball shoes use PHTLON midsoles, while jogging shoes use EVA midsoles.
Explanation of terms: (1) One-time foaming: the shoe midsole once formed by injecting/injecting the material into the mould and then heated by high temperature is called one-time foam midsole, that is, EVA shoe midsole. (2) Secondary foaming: After injecting the material into the mould, the midsole of the shoe is moulded by two high-temperature heating and firing, which is called the secondary foaming midsole, which is what we often call the PHYLON midsole.
On the whole, EVA is cheap, and it feels very soft at first. The first feeling is excellent, but after a long time, you may feel a footprint on the sole, and the performance has also significantly dropped. EVA makes PHYLON, but the process is much more complicated, and the cost is much more expensive. Performance is much better in all aspects.
It should be noted that this does not mean that EVA is worse than PHYLON. It can be said that the performance of PHYLON under the same process + material is better than EVA. Still, due to the difference in means and content, the performance of some EVA is better than the ordinary PHYLON midsole. In addition to PHYLON midsoles and EVA midsoles, PU midsoles are also very common. The most significant advantages of PU midsoles are better elasticity and toughness. The disadvantages are higher density and reduced resistance to yellowing and hydrolysis.
Midsole technology: adiPRENE: cushioning technology, deficient elasticity, used in the heel, it can absorb shock after the person falls on the ground, making the person lower on the field more smoothly without shaking. adiPRENE +: Highly flexible technology, contrary to the above. Used for the forefoot, when the sole strongly supports the ground, it can rebound immediately, so that people can start quickly.