PE PVC cling film extrusion line

PE PVC cling film extrusion line uses PVC resin powder as the main raw material, mixes various grades of additives, and produces PVC plastic wrap with self-adhesive properties by thoroughly stirring and plasticizing extrusion through an extruder.

 PE PVC cling film extrusion line Features

1. The specially designed PVC mold and extrusion molding process achieve stability and high product qualification rate during high-speed production.
2. The PE PVC cling film extrusion line embedded slitting unit cuts and rolls according to the different widths and lengths of the final product. The products produced do not need to be rewound twice.
3. The specially designed fixed-length cut-off roll changing device and contact roller unit make the film surface more flat and tidy at the end surface.

PE PVC cling film extrusion line Process Flows

Extruder —- Screen changer —– Melt pump —– T-die —— Calender —– Thickness Scanner —-Cooling Bracket —-Cutting Knife —- Haul-off —-Winder

The cling film is a kind of plastic packaging product of fresh-keeping food for daily use. The cling film has moderate oxygen permeability and moisture permeability adjusts the oxygen content and moisture content around the fresh-keeping products, and blocks the dust in the air, so as to prolong the fresh-keeping period of food.

The vast majority of cling films sold on the market, like commonly used plastic bags, use ethylene masterbatch as raw materials. According to different types of ethylene masterbatch, fresh-keeping films are divided into three categories.

• The first is polyethylene, which is mainly used for food packaging. This film is used for fruits and vegetables we usually buy, including semi-finished products purchased in supermarkets;
• The second is polyvinyl chloride, which can also be used for food packaging, but it has a certain impact on the safety of the human body;
• The third is polyvinylidene chloride, PVDC for short, which is mainly used for the packaging of some cooked food and other products.

Product difference between tape casting and film blowing

In terms of thickness: during tape casting production, the film material is in contact with the forming roll, cooling and forming is fast, the thickness control is easy, and the thickness distribution is better than that of film blowing.
Flatness: the gap between rollers is small in tape casting production, while the film bubble in the film blowing method is unstable. The flatness is better in tape casting production.
Transparency: casting production has a short cooling time and good transparency.
Production: the production output of the tape casting method is large.

China GWELL PE PVC cling film extrusion line Process conditions

GWELL as China Plastic Extruder Supplier,Due to the long and narrow flow channel and fast flow speed in tape casting production, the melt temperature range is usually controlled at 250 ℃ ~ 280 ℃, the temperature of tape casting cooling roll is controlled at 20 ℃ ~ 30 ℃, and the winding tension is low, usually within 10kg, so as to facilitate the migration of adhesive and reduce the internal stress of the finished film.

Viscous control

Good stickiness makes the outer packaging film and a layer of goods stick together to make the goods firm. There are two key methods to obtain stickiness: one is to add PIB or its masterbatch to the polymer; The other is mixing VLDPE.
PIB is a translucent viscous liquid. Special equipment is required for direct addition or transformation of equipment. Usually, PIB masterbatch is adopted. There is a process for PIB to move out, which usually takes three days. In addition, it is also affected by temperature. When the temperature is high, the viscosity is strong; It is not too sticky when the temperature is low, and the viscosity is greatly reduced after stretching.

Therefore, the finished film is best stored in a certain temperature range (the storage temperature is proposed to be 15 ℃ ~ 25 ℃). When VLDPE is mixed, the viscosity is slightly poor, but there are no special requirements for the equipment. The viscosity is relatively stable, not controlled by time, but also affected by temperature.
When the temperature is higher than 30 ℃, it is relatively sticky, and when the temperature is lower than 15 ℃, the viscosity is slightly poor. The amount of LLDPE in the adhesive layer can be adjusted to achieve the required viscosity. This method is often used in three-layer coextrusion.