PPE

1ntroduction of common materials for soles of safety shoes

The sole materials of safety shoes generally include the following categories: Rubber (RU), thermoplastic rubber (TR), polyurethane (PU) or thermoplastic polyurethane (TPU)

1, polyurethane (PU)

the simplest shoes are made of single density polyurethane outsoles. Polyurethane sole must have two tasks: first, it must feel comfortable, and the sole is light; second, it is also a very important point, that is, safety issues, such as skid resistance. 1n fact, it’s difficult to combine these two functions. 1n most cases, only one of them can perform correctly. The density of polyurethane sole is about 0.8g/cm3, which is usually used in leisure shoe industry. The production of single density shoes is very simple and effective, but the products are still high-grade commercial shoes2. Polyurethane / polyurethane (PU / PU)

for more than 20 years, the shoe industry has been producing dual density polyurethane shoes with direct injection molding machines. The combination of dense polyurethane outsoles and lightweight work shoes

and comfortable insoles makes it possible for the shoes to combine the two characteristics. We can use the material with very compact structure to make the outsoles, so that they have stronger wear resistance, and are endowed with good anti-skid and anti grease properties. You can use a foam polyurethane system to make a mid sole, which makes shoes more comfortable and even lighter. Shoe production is different from single density shoe processing. 1n the first step, the dense insole needs to be injected into the closed mold. After a certain time of reaction, the upper part of the middle sole and the outer sole is injection molded, and through the adhesion of the sole and the upper, a simple shoe sample is successful. Most of the time, this kind of material combination is used in the safety footwear industry, because in this industry, both comfortable appearance and excellent characteristics are needed. But in casual shoes, there are many interesting designs using polyurethane / polyurethane material combinations. The density of compact outsoles is mainly 0.9g/cm3, while the density of insoles is mostly 0.45g/cm3. For safety shoes, the adhesion of the two layers exceeds the required standard, and the middle sole can be made with a thinner layer

3. Thermoplastic polyurethane (TPU)

this kind of material combination is not as good as the publicity, because the single density TPU sole will not make the shoes comfortable to wear, and the density of TPU is about 1g / cm3, which means that this kind of shoes can not produce good sound insulation effect on foot sound. 1n addition, it is often very difficult to bond TPU to the upper, so TPU outsoles are not often used

4. Thermoplastic polyurethane (TPU / TPU

due to the new development of material suppliers, this kind of shoes become more and more interesting. Thin TPU outsoles and blown TPU insoles will become a new material combination in the future. More or less, its principle has something in common with the combination of polyurethane / polyurethane production materials. The hardness of thermoplastic polyurethane covers a wide range. 1n the shoemaking industry, the shore hardness value ranges from 55A to nearly 85A. 1n fact, it has excellent anti-wear and anti-skid properties. Thermoplastic polyurethane gives the sole a good carving process. Blown TPU can now be poured, which means that manufacturers can skip the production material combination from TPU to TPU / TPU in a short time. Compared with polyurethane, thermoplastic polyurethane has great advantages in processing. Thermoplastic polyurethane can be packed in bags when it is fed, which is granular. 1t does not involve professional knowledge related to chemistry, and the operator does not have to adjust a large number of parameters for different machines when operating the machine

5. Thermoplastic polyurethane

may be the most commonly used material combination nowadays. Thermoplastic polyurethane / polyurethane has many advantages. First of all, the shoemaking process can be completed through a one-stop process. 1n this process, thermoplastic polyurethane is used to make shoe outsoles, and polyurethane is used to make shoe insoles. What is most interesting about the direct molding process at the bottom is the combination of the shoe sole made of compact thermoplastic polyurethane and the low weight shoe sole with self reactive polyurethane foam. The result of the combination is a composite sole with a very wearable outer sole and a comfortable mid sole. 1n addition to their outstanding physical properties, the shoe outsoles made of thermoplastic polyurethane can meet the needs of modern design. Transparent sole or colorful sole can be used in the direct molding process

6. Multi functional thermoplastic polyurethane

using the thermoplastic polyurethane injection molding process, the new DESMA process can produce three kinds of color sole, which makes designers and manufacturers extremely excited. This can achieve a process, three colors or functions. The colored material is injected into the path of the mold frame by a pair of injection molding equipment, and the injection amount is determined by the user. After hardening, the material is poured, thus forming an outsoles. Then, the middle sole of the shoe is injected to complete the production. All the operation steps are completed on the same machine, which is an integral part of the same whole process. 1t can not be sold without treatment. 1t not only saves processing, distribution and material steps, but also improves product quality and economy. With one process and multiple sole characteristics, DESMA process rapidly takes advantage of the uncertain characteristics of new products. Now, we can not only distinguish sole types according to color, but also different hardness, function, strength and characteristics. For example, these advantages enable manufacturers of safety shoes to provide shoes with special category support functions or convenient for users to walk

7. Rubber / polyurethane (Ru / PU)

so far, one of the best material combinations is that the outsoles are made of rubber and the insoles are made of polyurethane. The production process of the outsoles and insoles of the sole can be carried out step by step. Finally, they are bonded together with adhesive. 1n most cases, pretreatment is required, such as halogenation and / or polishing of the rubber surface. Another bonding method is to use non-woven wool between the two materials, using the mechanical bonding function of rubber and the bonding function of polyurethane to achieve the purpose of bonding. However, all of these processes involve a considerable amount of auxiliary equipment and a lot of logistics work. Many shoe manufacturers try to avoid this cost intensive investment and switch to other materials that are easy to process. Under normal circumstances, due to different physical and chemical properties, rubber and polyurethane will not bond. 1n addition, polyurethane is usually not processed under the expected conditions in this process. As a result, DESMA has developed into a process that does not use the above process steps. Today, it can use rubber / polyurethane material combination to make shoes without using any harmful glue through a one-stop process. Then, the polyurethane injection molding instrument can inject polyurethane into the rubber sole and add water-based adhesive at the same time. The two different materials achieve a perfect adhesion and meet the requirements of relevant safety shoe standards

8. Rubber / rubber (Ru / Ru)

one of the most commonly used processes for military shoes is the process of using rubber / rubber material combination. 1n this process, both the outer sole and the middle sole of shoes are made of rubber. The outsole and the thermoplastic polyurethane / thermoplastic polyurethane material combination process are just like the dense outsole, and the sole of the shoe is made of foam rubber. These shoes have excellent properties, such as high temperature resistance, or grease and fuel resistance. These materials, like polyurethane, do not support hydrolysis, but the situation is different in the military industry, where rubber / rubber military shoes are used. The same is true in the field of sports shoes. This material combination has many significant advantages, such as real, good anti-skid performance< China labor insurance net

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