What are the characteristics of eva materials? Now the common loading tools such as school bags, computer bags and emergency bags in our lives have been made of eva materials. When it comes to eva materials, most people may not have heard of them, and may not know much about them. Nalintai will introduce eva materials and their features to you:
EVA is Ethylene – Vinyl acetate (ethylene acetate) ester copolymer. It is produced by the copolymerization of ethylene (E) and ethylene acetate (VA). Its English name is Ethylene Vinyl
Acetate, or EVA for short, or E/VAC. The content of ethylene acetate (VA) in general is between 5% and 40%. Compared with polyethylene, EVA reduces crystallinity and improves flexibility, impact resistance, filler phase solubility and thermal sealing performance due to the introduction of ethylene acetate monomer in the molecular chain.
Generally speaking, the performance of EVA resin is mainly determined by the content of ethylene acetate on the molecular chain. Due to the adjustable component ratio to meet different application needs, ethylene acetate (VA
The higher the content is, the higher the transparency, softness and toughness will be.
Polymerization methods are high-pressure bulk polymerization (for plastics), solution polymerization (PVC processing AIDS), emulsion polymerization (adhesive), suspension polymerization. Emulsion polymerization was used when the content of vinyl acetate (VA) was higher than 30%, and high pressure bulk polymerization was used when the content of vinyl acetate was lower.
EVA resin is characterized by good softness, rubber-like elasticity, good flexibility at -50℃, good transparency and surface gloss, good chemical stability, aging resistance and ozone resistance, and no toxicity. Good mixing with filler, good coloring and molding processing.
It is closely related to ethylene acetate content, molecular weight and melting index. When the melt index (MI) is fixed and the content of ethylene acetate (VAC) is increased, the elasticity, softness, compatibility, transparency and so on are also improved. When the VAC content is reduced, the performance is close to that of polyethylene, with increased rigidity, wear resistance and electrical insulation.
When the content of VAC is constant and the melt index increases, the softening point will decrease, the machinability and surface gloss will improve but the strength will decrease; otherwise, the molecular weight will increase with the decrease of MI, and the impact performance and environmental stress cracking resistance will improve. The polarity of acetate increases elasticity and viscosity, decreases crystallinity and electrical properties, and dissolves in hydrocarbon solvents and oils.
The characteristics of EVA and PEVA are:
1. Biodegradable: No harm to the environment when discarded or burned.
2. The price is close to PVC: the price of EVA is more expensive than that of toxic PVC, but it is cheaper than that of PVC without phthalates.
3. Light weight: the density of EVA ranges from 0.91 to 0.93, while PVC is 1.32.
4. No odor: EVA does not contain ammonia or other organic odor.
5, free of heavy metals: in accordance with the relevant international toy regulations (EN-71 Part 3 and ASTM-F963).
6, no phthalates: suitable for children’s toys and will not produce plasticizer release risk.
7, high transparency, softness and toughness: a wide range of applications.
8, super low temperature resistance (-70C) : suitable for icing environment.
9, water, salt and other substances: keep stable in most applications.
10, high heat adhesion: can be firmly attached to nylon, polyester, canvas and other cloth.
11, low fitting temperature: can accelerate the production speed.
12, silk screen printing and offset printing: can be used for multi-pattern products (but must use EVA ink).
From the above introduction of the characteristics of eva materials, it can be seen that eva materials are more durable and better than traditional materials in many aspects. It is believed that the market of eva materials will be more extensive in the future. Want to know more knowledge can click on the site to view.