The optical properties of plastic film sheet are especially important in flexible packaging and agricultural production application, which can be characterized by haze, clarity and gloss.
The main factors affecting the optical properties of thin plastic film sheet as below,
1. Think plastic film sheet processing technology
The molding process of the thin plastic film sheet affects the optical properties. Compared with the casting method, the blown film method has faster cooling and higher efficiency, with less crystal particles are and better optical properties.
The optical properties of thin plastic film sheet will be widely improved after MDO (machine direction stretching).
2. The cooling efficiency
The cooling method and cooling efficiency of think plastic film will affect the optical properties too. For example, after adopting IBC internal cooling, the internal haze of the blown plastic film will be lower as the crystals on the inner surface of the film bubble tube have no time to grow.
3. The resin parameter
The lower the density of the resin, the lower crystallinity and internal haze; low melt index and high extensional viscosity will result in higher extrusion haze
4. The additive
Some inorganic additives such as anti-blocking agents have obvious negative effects on optical properties.
5. The processing and die temperature
The increase of the processing temperature and die temperature will widely improve the extrusion haze. However, high temperature will low down the cooling efficiency, and thereby prolonging the crystal growth time and increasing the internal haze.