EVA有哪些用途？(What are EVAs used for?)
EVA树脂是乙烯-醋酸乙烯共聚物，一般醋酸乙烯（VA）含量在5%～40%。与聚乙烯相比，EVA由于在分子链中引入了醋酸乙烯单体，从而降低了高结晶度，提高了柔韧性、抗冲击性、填料相溶性和热密封性能，被广泛应用于发泡鞋料、功能性棚膜、包装膜、热熔胶、电线电缆及玩具等领域。一般来说，EVA树脂的性能主要取决于分子链上醋酸乙烯的含量。
发泡鞋材
鞋材是我国EVA树脂最主要的应用领域。在鞋材使用的EVA树脂中，醋酸乙烯含量一般在15%～22%。由于EVA树脂共混发泡制品具有柔软、弹性好、耐化学腐蚀等性能，因此被广泛应用于中高档旅游鞋、登山鞋、拖鞋、凉鞋的鞋底和内饰材料中。另外，这种材料还用于隔音板、体操垫和密封材领域。
薄膜
EVA薄膜的主要用途是生产功能性棚膜。功能性棚膜具有较高的耐候、防雾滴和保温性能，由于聚乙烯不具有极性，即使添加一定量的防雾滴剂，其防雾滴性能也只能维持2个月左右；而添加一定量EVA树脂制成的棚膜，不仅具有较高的透光率，而且防雾滴性能也有较大提高，一般可超过4个月。另外，EVA还可用于生产包装膜、医用膜、层压膜、铸造膜等。
电线电缆
随着计算机及网络工程的不断发展，出于对机房安全的考虑，人们越来越多地使用无卤阻燃电缆和硅烷交联电缆。由于EVA树脂具有良好的填料包容性和可交联性，因此在无卤阻燃电缆、半导体屏蔽电缆和二步法硅烷交联电缆中使用较多。另外，EVA树脂还被应用于制作一些特殊电缆的护套。在电线电缆中使用的EVA 树脂，醋酸乙烯含量一般在12%～24%。
EVA resin is ethylene-vinyl acetate copolymer, generally vinyl acetate (VA) content is 5%~40%.Compared with polyethylene, EVA is widely used in foamed shoe materials, functional shed films, packaging films, hot melt adhesives, wires and cables and toys due to the introduction of vinyl acetate monomer in the molecular chain, thereby reducing high crystallinity, improving flexibility, impact resistance, filler compatibility and heat sealing performance.In general, the performance of EVA resin mainly depends on the content of vinyl acetate on the molecular chain.
Foamed shoe material:
Shoe material is the most important application field of EVA resin in China.In the EVA resin used in shoe materials, the content of vinyl acetate is generally 15%~22%.Because EVA resin blended foam products have softness, good elasticity, chemical corrosion resistance and other properties, they are widely used in the sole and interior materials of medium and high-end tourist shoes, hiking shoes, slippers and sandals.The material is also used in acoustic panels, gymnastics mats and sealants.
Membrane:
The main use of EVA film is the production of functional shed film.Functional shed film has high weather resistance, anti-fog droplet and heat preservation performance, because polyethylene does not have polarity, even if a certain amount of anti-fog drop agent is added, its anti-fog drop performance can only be maintained for about 2 months; The shed film made by adding a certain amount of EVA resin not only has a high light transmittance, but also greatly improves the anti-fog droplet performance, generally more than 4 months.In addition, EVA can also be used to produce packaging film, medical film, laminated film, casting film, etc.
Wire and cable:
With the continuous development of computer and network engineering, halogen-free flame retardant cables and silane cross-linked cables are increasingly used for the safety of computer rooms.Because EVA resin has good filler inclusiveness and crosslinkability, it is widely used in halogen-free flame retardant cables, semiconductor shielded cables and two-step silane crosslinked cables.In addition, EVA resin is also used to make some special cable sheaths. EVA resin used in wire and cable, vinyl acetate content is generally 12%~24%.