A shrewd selection of raw material characteristics and production processes is essential for the production of high-purity thermoplastic film.

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Mixing polymers for the production of thermoplastic film

The production of film intended for food, optical grade or medical applications requires virgin – i.e., low-impurity – raw materials. Nevertheless, it is often necessary – and sometimes required by regulations in force – to provide for the use of mixed virgin materials and low-impurity recycled plastic in plastic extrusion processes.

Mixing virgin raw materials and recycled plastic – why?

Two major reasons underlie the mixing of virgin and recycled raw materials for the production of high-purity film:

• Production characteristics must comply with environment protection regulations in force; in particular, it is necessary to minimize the production of new plastics. This means a percentage of recycled plastic must be used.
• Regardless high-purity film production would require an exclusive use of virgin polymers, the introduction of a small percentage of recycled plastics offers the chance to control raw material procurement costs, i.e., it offers an economic benefit.

Recycled material percentage

What is the optimized ratio in mixing virgin and recycled raw materials? When mixing virgin and recycled materials, mixing percentage sensibly varies and depends on the following:

• End applications
• End product intended use
• Required quality

High-quality thermoplastic film

In such a scenario, two key factors must be considered when selecting the recycled plastic material intended for a high-quality end product:

• Impurity level must be minimized – low impurity levels are essential for food and medical end applications.
• During extrusion cycle, a high-level filtration continuous screen changer is required. A remarkably high filtering capacity is essential whenever recycled raw materials are used, even if they have a low impurity content. Moreover, the screen changer must be continuous, i.e., it should offer an uninterrupted plastic film production.

Continuous screen changers offering high filtering capacity

Starting from a mix of virgin and low-impurity recycled raw materials, what is the filtering capacity suitable for plastic film production? Filtering capacity requirements mostly depend on end application purity level and should be suitable for end products.

Cofit manufactures continuous and self-cleaning screen changers suitable for the production of high-quality thermoplastic film – BOPP and BOPET film included – by screening mixed virgin and recycled plastics. Manual and continuous screen changers from Cofit AP series offer plastic material filtration levels exceeding 10 microns – such filtration levels comply with quality requirements set by food, optical grade, or medical application standards.

Cofit AP screen changers

Cofit AP screen changers are designed for high filtration continuous applications, relying upon unrivalled sturdiness and efficiency (they stand pressure levels exceeding 500 bars), besides zeroing operation interruptions due to standard maintenance interventions.

Interest in Cofit AP series is boosted by several AP characteristics such as low investments and management costs compared with other screenchangers – in particular, AP life cycle is significantly extended if compared with more complex screen changers. Have a look at AP technical data sheet.

Cofit deals with research, designing, manufacturing and distribution of continuous screen changers, either automatic or manual, intended for any sector and process material, in particular BOPP and BOPET film. Contact us to see how a continuous screen changer can optimize your plastic extrusion process.