Expert knowledge from A-Z


A calender is a system consisting of heated and polished rollers arranged in a successive sequence where material is passed through the gaps between the rollers. It is used for manufacturing (thicker) films made of plastic (PVC, PE, PS, etc.). Use: For blister packing (display packaging). Different effects can be achieved in calendering by changing the pressure, temperature and roller speed.

A substance that accelerates a certain reaction without being a part of the reaction or being depleted in the process.

Unwanted cavities in the interior of a film or on its surface, which are caused by an error in the manufacturing process.

Cellophane is a thin, transparent film made from regenerated cellulose. The material is also subject to variations because the base material is a renewable raw material. Only acrylic paint can seal cellophane film; it has good mechanical and visual properties, but a very low restoring force (unlike BOPP) and low transparency.

See cellulose/cellophane

Extrusion process (flat-sheet die technology): Composite film is produced using a flat-sheet die. Bonding agent layers are also co-extruded depending on which individual layers are combined (the layers do not mix together in this process); without bonding agents, it would only be possible to bond identical plastics as part of co-extrusion. Thicknesses: 20 - 2000 µm for co-extruded composites.

Simultaneous processing of two or more plastics using an extruder; merging melting plastics of the same type or different types before leaving the profile die. Granulate that is heated to the melting point is compressed by a flat-sheet die or ring-shaped die. If two or more films are pressed out of two or more dies simultaneously and then combined, this is considered co-extrusion.

Blend or co-polymerisation; combined polymerisation of various types of mono-polymers.

Cohesive forces are responsible for factors such as the toughness and the flow properties of the uncured adhesive during processing and for the firmness of the cured adhesive under strain.

At low temperatures, films tend to become brittle, resulting in what is also known as cullet

Combination of film layers by applying adhesive, which enables a cold seal.

Combining film layers by applying adhesive, which enables a cold seal (combination) of material such as film layers.

Combining films using mechanical pressure.

Composite films include various materials and consist of multiple layers. Materials are combined to achieve properties that cannot be achieved using individual films. Example: To improve low gas or water vapour permeability or the heat sealing capability. A wide variety of combinations is possible. It is also possible to combine film/paper or film/cardboard.

Two endless moving belts are joined using a (heated) sealing bar and the bag being sealed is pulled through.

The film web is subject to an electrical discharge and surface tension increases. In this process, a high-frequency high voltage creates a corona discharge between an electrode system and a counter electrode shaped as a roller. Also referred to as printing pretreatment.

Cast (stretched) polypropylene with better transparency than films like PE film while also having good mechanical properties.

QA testing for straight edges: Tested by unrolling approx. 5 m film and pulling on all four corners and folding them at the centre lengthwise. The two overlapping film edges should have an offset of no more than 5 mm.

The curvature of a film in the crosswise direction.

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