Centexbel-VKC offers a plastic processing platform focused on material compounding, processing and on surface modification.

Compounding

Compounding consists of preparing plastic formulations by mixing and/or blending polymers and additives in a molten state, these blends are automatically dosed with fixed setpoints usually through feeders/hoppers.

Compounding is usually done by extrusion. The hopper feeds the begin of the screw which will gradually transport the resins towards the die. The screw itself is confined in a barrel that has different zones that can be heated according to the resins properties.
 
Co-kneaders and twin screws (co- and counter rotating) as well internal mixers are the most commonly used compounders in the plastic industry.
HAAKE™ MiniCTW Micro-Conical Twin Screw Compounder

HAAKE™ MiniCTW Micro-Conical Twin Screw Compounder

The ThermoFisher™ HAAKE™ miniCTW (or mini-compounder) is very appropriate to compound and extrude small quantities. This conical double-screw compounder enables us to test a large spectrum of different materials and to screen a large number of processing conditions or product combinations in an affordable and quick manner. Ideal for tests with nanomaterials or engineered biopolymers.

The optional Force Feeder system enables a continuous material throughput. This screw-feeder is air-cooled to prevent clogging.

In addition to a continuous extrusion mode, the minicompounder allows a backflow mode through a recycle configuration, resulting in a optimised blend. The use of pellets involves that the material dosing is approached from a statistic distribution. However, this is solved by using powders or by partly mixing the blends beforehand.

The co-rotating and counter-rotating configurations guarantee an optimised blending. The heat regulation is limited to one single temperature for the entire barrel and cannot be divided into different zones.

The mini-compounder is computer assisted enabling the online follow-up and graphic display (in function of time) of temperature, screw speed and couple. It is also possible to add an event at a certain point of time.

Temperature can be set between ambient temperature and 300°C, with a heat output of 800W. The screw speed can be set between 10 to 360 rpm - max. couple of 5Nm.

Although it is possible to preset many parameters (temperature, screw speed and couple) it is not straightforward to upscale the process. However, by applying optimised process parameters, it is possible to produce blends with an extremely fine dispersion.

Yarn extrusion

The minicompounder is used for yarn extrusion pilot tests by means of the Force Feeder  for a continuous material throughput or by means of the blackflow system for an optimal blend.

The extruded filament is aircooled over a conveyor belt. The preset speed determines the yarn thickness.

ISO - Plastic test samples

The HAAKE miniCTW can be connected to the Thermo Scientific™ HAAKE™ miniJET. This apparatus is used to produce small test samples of 0,9 - 1,3 g. The mechanical properties of these test samples (ISO-dimensions) are then tested.

Leistritz compounder

Leistritz Masterbatch compounder

Injection moulding

The hydraulic injection moulding machines are available to analyse raw materials, to produce small test run series and to  test new moulds. 

Arburg Injection moulding machine

Arburg Allrounder 320 S 500 - 150

  • Possibility to fit Axxicon mold for the injection moulding of ISO test samples
  • Possibility to apply personal inserts 

Technical specifications of the Arburg Allrounder 320 S 500 - 150

  • Max. clamping force: 500 kN
  • Max. open  (at min. installation height): 350 mm
  • Min. installation height: 225 mm
  • Dimensions clamping platen: 498 x 498 mm
  • Bar spacing: 320 x 320 mm
  • Flange diameter: 125 mm
  • Max. ejector force: 30 kN
  • Max. ejection stroke: 125 mm
  • Srew diameter: 30 mm
  • L/D ratio: 20/1
  • Max. shot volume: 78 ccm
  • Max. Couple on screw: 360 Nm
  • Max. injection speed: 112 ccm/sec
  • Max. dosing speed: 65 m/min
  • Max. nozzle pressure: 50kN

 

Injection moulding ENGEL

ENGEL 1350/250 HL

The  ENGEL 1350/250 HL is designed without tiebars, guaranteeing a large freedom in mould design and rapid mould switches. 

Technical specifications of the ENGEL 1350/250 HL

  • Max. clamping force: 2500 kN
  • Max. open  (at min. installation height): 850 mm
  • Min. installation height: 350 mm
  • Dimensions clamping platen: 1050 x 650 mm
  • Flange diameter: 160 mm
  • Max. ejector force: 82 kN
  • Max. ejection stroke: 200 mm
  • Srew diameter: 60 mm
  • L/D ratio: 20/1
  • Max. shot volume: 735 ccm
  • Max. Couple on screw: 1481 bar
  • Max. injection speed: 407 ccm/sec
  • Max. dosing speed: 43 m/min
  • Max. nozzle pressure: 110 kN
     
Injection moulding KraussMaffei 125 –700 C2

KraussMaffei 125 –700 C2

Technical specifications of the KraussMaffei 125 –700 C2

  • Max. clamping force: 1250 kN
  • Max. open  (at min. installation heigth): 600 mm
  • Min. installation height: 300 mm
  • Dimensions clamping platen: 745 x 770 mm
  • Bar spacing: 470 x 470 mm
  • Flange diameter: 125 mm
  • Max. ejector force: 22 kN
  • Max. ejection stroke: 150 mm
  • Srew diameter: 50 mm
  • L/D ratio: 20/1
  • Max. shot volume: 377 ccm
  • Max. injection speed: 181 ccm/sec
  • Max. dosing speed: 40 m/min
  • Max. nozzle pressure: 84 kN
  • Compression ratio: 2.1 to 1

Surface modification

Some polymers contain apolar groups. Their surface is therefore low on energy and not easy to bond or wet. This results in poor adhesions of coating layers. To ensure proper bonding or coating a surface modification is necessary. This is done by oxidising the top layer and so introducing polar groups.

Corona treatment

A plastic film is passed over a metal roll, placed at approximately 1 to 2 mm underneath an electrode. An alternating current passes through the electrode at 20.000V. This leads to a continuous discharge to the plastic film that modifies the surface structure.

Atmospheric plasma

Plasma is a gas in which the gas molecules disintegrate into individual atoms, free radicals, electrons and photons. They bombard the plastic’s surface and lead to polar groups. In the case of atmospheric plasma, air is used instead of an inert gas.

Plasma surface treatment

Plasmatreat® Openair jet

Plasma technology is based on a simple physical principle. Matter changes its state when energy is supplied to it: solids becomes liquid, and liquids becomes gaseous. If even more energy is supplied to a gas, it is ionized and goes into the energy-rich plasma state, the fourth state of matter.

Method

A process gas such as air, nitrogen or mixed gases is guided through a jet in which a high voltage discharge turns it into Plasma.

This highly reactive plasma is electrical potential fire and will clean, activate or coat surfaces in order to create perfect adhesion or add functionalities (such as hydrophylic, Hydrophobic, anti corossion, ...)

Applications:

  • surface cleaning
  • plastic surface activation prior to bonding, printing, coating
  • plasma coating