The product EVA resin is milky white translucent oblate granules, which are elastic and easy to burn. When EVA burns, it is easy to drip, smokeless; the burning flame, the bottom is blue, the top is yellow; when burning, it can smell acetic acid (distinguishing the obvious characteristics of EVA and PE). The EVA resin has a density of 0.925 to 0.980 g/cm.
The relative molecular mass of EVA has a significant impact on EVA performance. When the VA% phase of EVA resin
At the same time, the relative molecular mass is reduced, the melt flow rate of the resin is increased, the viscosity of the oxime is lowered, the thermal bonding initiation temperature of the film is lowered, the toughness, the stretchability, the stress crack resistance of the film are lowered, the processing property of EVA, the surface The gloss is improved; while the elongation at break of the film, the surface hardness is not affected.
If the relative molecular mass of the EVA resin, the melt flow rate is the same, VA% increases, the film is elastic, flexible (primary under cold conditions), compatibility, transparency, impact, stress cracking, weather resistance The surface glossiness, viscosity, weldability and heat sealability are improved, and the crystallinity of EVA is lowered, and the film strength, hardness, melting point, chemical resistance, and thermal deformation property associated therewith are also lowered. If VA% decreases, as the VA decreases, the performance of the EWA film gets closer to LDPE.
Compared with LDPE film, EVA film has the following characteristics: good toughness and elasticity, low heat sealing temperature, good low temperature impact resistance, large surface friction coefficient, good printing property, high frequency welding (power required is greater than PVC film) ), the film opening property at the time of extrusion blown film is inferior.
EVA has good molding processability, and the film can be formed by extrusion blown film method and extrusion cast film method.
However, different molding processes can also cause differences in film properties. The EVA film is produced by an extrusion blown film method, and the tubular film has poor opening properties, and the flexibility and transparency of the film are not as good as that of the extruded cast film. Adhesive layer.
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