PHYSICAL EXPANSION OF EXPANDED PE & PP FILM WITH “DIRECT GASING” TECHNOLOGY
01. IMPORTANT FACTS
* The production process of expanded film does not require a chemical reaction, does not use chlorofluorocarbon, does not introduce particular risks to the atmosphere.
* The Gas, although comes put in the atmosphere, does not cause problems to ozone.
* The finished product does not introduce toxicity or factors of risk for the human health and the atmosphere.
* Expanded PE & PP foam is totally recyclable.
02. FINISHED PRODUCTS
Polyethylene and Polypropylene foam (LDPE/LDPP) is a flexible gas-filled plastic polymer with a closed-cell non cross-linked molecular structure. In the last years these materials have obtained popularity in vary industries for them advantageous characteristics, for example, heat saving capacity or excellent shock absorbing properties. Due to this fact, polyethylene and polypropylene foam is a versatile insulator and packaging material.
03. BASIC ELEMENTS FOR PRODUCTION OF FOAM
The process of extrusion by direct injection of gas transforms plastic granules in expanded flexible film:
* Expanding gas: isobutane / normal butane gas;
* Raw materials: polyethylene PE / polypropylene PP granules with the eventual additives (completely incorporated into the finished product without emissions in the atmosphere).
* Electric power and Water.
04. EXTRUSION PROCESS STEPS
1. The plastic granules are inserted into the extruder to be fused.
2. The expanding gas is injected into extruder and is mixed to the plastic melt. The special shape of the extrusion screws allows to obtain the homogeneous mixing of the material with the gas. The high quality final products obtained with twin-screw system are not comparable with materials produced by other technologies.
3. Going out from the extruder and passing to the atmospheric pressure, the gas mixed with the plastic material reacts, expanding the melt and increasing the volume of the material. The produced film has to be stored in an opportunely ventilated area (for 3-10 days). Passed this storage time the material has released nearly totally the residual gas.
4. Recycling of rejected materials (first products after start-up, cut edges): with opportune systems of regeneration it can be put in the productive cycle like raw materials.
05. PROCESS OF THE GAS INJECTION
Gas tank ⇒ Gas distribution system ⇒ High pressure pump ⇒ Extruder
The 40% of the gas is ejected between the head of the extruder and the coil winder (in the production unit);
The remaining 60% is ejected during the storage time in warehouse.
Use of the gas for the production: min 5% – max 30%.
06. ESSENTIAL REQUIREMENT
Gas System must be installed and controlled totally by the client:
* Low pressure pumps,
* Connection between system tanks, pumps and machinery,
* Safety system with valves for the gas interception,
* Ventilation for the extraction of the gas from machinery and in warehouse,
* Pipes extraction of the gas in all critical points.
- The production process of expanded film by direct gasing has a range of advantages in terms of environment impact, expenses and quality of final product.
- Thanks to innovation Internal Research Centre, FAP continually develops new technologies, improves and generates solutions for PE/PP foam production.