Artificial turf has been widely used for more than 50 years because of its superior performance compared with natural turf. One day in April 1966, Houston space dome stadium, known as "the eighth wonder of the world", quietly waited for the start of the baseball league. But what may not even be known to the spectators queuing up for admission was that they witnessed a historic moment: the world's first artificial turf, the Astro lawn, was laid on the baseball field before the game began.
The reason why artificial turf is also known as Astro lawn is because the American Astro company was the first to invent artificial lawn. Artificial turf without watering and fertilization, low maintenance cost, less affected by climate and weather, long-term durability and good visual appearance, soon swept the world.
However, at that time, the texture of artificial turf was not as flexible and elastic as that of natural turf. The huge friction force caused injuries to athletes frequently, and even gave rise to a special disease - Astro toe. As a result, the newly rising artificial lawn has been neglected. In 1988, the British Football Association banned the use of artificial turf in official competitions. Since then, FIFA has also banned the use of artificial turf.
Later, with the application of new materials such as polyethylene (PE) and polypropylene (PP) and new technologies, the performance of artificial turf has been greatly improved. In 2003, plastic surgeon bill Bashir said in a research report that in the long run, artificial turf is safer than natural turf, because natural turf growth is inconsistent, and constant wear will slow down the softness, thus increasing the possibility of ankle or other injuries.
With the improvement of performance and the improvement of people's understanding, artificial turf is again popular. In particular, since July 1, 2003, the artificial turf which has passed the inspection of FIFA has been allowed to carry out formal football matches, and the artificial turf has been more and more used in all kinds of competitions. For example, in the 2018 World Cup in Russia, artificial turf has been widely used.
PE and PP are the main raw materials
From the point of view of chemical composition, the raw materials of artificial turf are mainly PE and PP, and PVC and polyamide can also be used. The artificial turf with PE as raw material has softer hand feel, closer appearance and sports performance to natural grass, which is widely accepted by users, and is the most widely used artificial grass fiber raw material in the market; the artificial turf grass fiber with PP as raw material is relatively hard, which is generally suitable for tennis court, playground, runway or decoration, and its wear resistance is slightly worse than polyethylene;
The artificial turf made of nylon is the earliest raw material of artificial grass fiber, which belongs to the first generation of artificial grass fiber. The grass silk is soft and the feet feel comfortable.
From the aspect of material structure, the artificial turf is composed of three layers of materials. The foundation layer is composed of compacted soil layer, gravel layer and asphalt or concrete layer. The foundation layer is required to be solid, non deformation, smooth and impermeable surface, that is, general concrete site. Due to the large area of hockey field, the foundation layer must be well treated during construction to prevent subsidence. If concrete layer is laid, expansion joint shall be cut out after concrete solidification to prevent thermal expansion deformation and cracks.
The foundation layer is a buffer layer, usually composed of rubber or foam plastics. The rubber has moderate elasticity and the thickness is 3 ~ 5mm. The cost of foam plastics is low, but the elasticity is poor, the thickness is 5~10 mm, too thick, the lawn is too soft, and it is easy to sag. The buffer layer should be firmly adhered to the base layer, generally with white latex or universal adhesive.
The third layer, also the surface layer, is the turf layer. According to the surface shape, there are fluffy turf, annular curly nylon silk turf, leafy polypropylene fiber turf, permeable turf made of nylon wire, etc. This layer must also be glued to rubber or foam plastics. During construction, it must be fully glued, pressed and glued in turn, without wrinkling.
With the development of the market, man-made grass in materials, technology, construction and other aspects have undergone great changes, these changes are to make artificial grass closer to natural grass in sports performance. It can be divided into six stages: the first stage is mainly made of nylon material, which is similar to carpet and has poor elasticity, so it has no protection for athletes and is easy to be injured; the second stage is mainly made of PP material and filled with quartz sand particles with high hardness; the third stage is mainly made of PE material, filled with quartz sand and filled with rubber particles, which has the elasticity of natural grass and greatly improves the sports performance; In the fourth stage, with FIFA certification as the standard, it pays attention to the system engineering construction such as foundation and construction. In this stage, in addition to the mesh products, there are also straight and curved products. The materials include PE and PP mixing, PE and nylon mixing, and the sports performance is further strengthened; In the fifth stage, monofilament grass is mainly used. In addition to the pursuit of sports performance, it also pursues a more ideal appearance and pays more attention to the construction of the system; the sixth stage is mainly composed of curly grass, which is specially developed for gate course and golf.
