Non-absorbent, moisture-proof, and water-resistant EVA soles and footwear meet modern consumer needs.
As is well known, there is a growing emphasis on footwear comfort, and shoes featuring EVA soles cater perfectly to this demand. EVA soles are characterized by high toughness, resilience, and tensile strength. They offer excellent shock absorption, cushioning, and thermal insulation, as well as superior cold resistance and durability against exposure to the elements. Their closed-cell structure ensures sound insulation and makes them non-absorbent, moisture-proof, and water-resistant. They are resistant to chemical corrosion-including seawater, oil, acids, and alkalis-and are antibacterial, non-toxic, odorless, and pollution-free.
The material used for EVA soles is an ethylene-vinyl acetate copolymer, formed by the copolymerization of ethylene (E) and vinyl acetate (VA). Commonly abbreviated as EVA, the vinyl acetate content typically ranges from 5% to 40%. Compared to polyethylene, the introduction of vinyl acetate monomers into the molecular chain reduces crystallinity while enhancing flexibility, impact resistance, filler compatibility, and heat-sealing properties. Consequently, it is widely used in applications such as foamed shoe materials, functional greenhouse films, packaging films, hot-melt adhesives, wire and cable insulation, and toys.
EVA soles offer excellent softness, rubber-like elasticity, flexibility, and transparency. They maintain good surface gloss at 0°C and exhibit excellent chemical stability, aging resistance, ozone resistance, and non-toxicity. They also demonstrate good compatibility with fillers, excellent colorability, and superior moldability.
Material properties are closely linked to vinyl acetate content, molecular weight, and melt index. When the melt index (MI) remains constant, increasing the vinyl acetate (VA) content improves elasticity, softness, solubility, and transparency. Conversely, when VA content decreases, properties shift closer to those of polyethylene: rigidity, wear resistance, and electrical insulation improve. For a fixed VA content, increasing the melt index lowers the softening point and improves processability and surface gloss, though it reduces overall strength. Conversely, as the MI decreases, molecular weight increases, and impact strength as well as environmental stress crack resistance improve. The polarity of the acetate group increases elasticity and viscosity, reduces crystallinity and electrical properties, and renders the material soluble in hydrocarbon solvents and oils.