Content:

Palltrusion

the Process for the Preparation of Raw Materials
in the Wood Plastic Composite Industry

Production of Wood Plastic Composite (WPC) Products is booming. To achieve the best possible process parameters and to get the highest output for the production of WPC products the treatment of the individual raw materials is very important. The preparation of raw materials and the Palltrusion process are the key factors for a successful production of high quality products.

Different production processes in the WPC industry

There are three (3) major production processes involved in manufacturing of WPC parts with using granules made of thermoplastic and natural fibers. These granules (Pallwood ® ) are produced on the Palltruder ® Installation.

The Thermofix ® process is using Pallwood ® regularly scattered and with a nearly no-pressure process fed in the intererior of the installation between two conveyor belts and heated up. Sheet thickness’ of 1-20 mm can be produced.

The Extrusion process uses Pallwood ® as infeed material as well. Hollow profiles for almost any shape can be produced at any lengths.

The Injection Moulding process produces smaller parts like caps but even more complicated parts can be produced out of Pallwood ® .

Palltrusion

The Palltruder ® was developed to produce continuously dry, homogeneous granules (the Pallwood ® ) with a high bulk density made out of thermoplastics, natural raw materials and, if necessary, additives.

A dosing system allows the adjustment of the Wood Plastic Additive ratio. The type of plastic, the type of wood flour and its moisture content (not exceed 8 %) are the limiting factors for the ratio. The produced Pallwood ® itself has a humidity below 1 % and is well suited for high quality parts produced in the further processes.

Palltrusion Process

The feed materials are continuously dosed by a gravimetrical dosing system into the Palltruder ® .

With frictional heat and mechanical pressing power the material mixture is evenly sintered and pressed through the holes of a special die.
Steam released during the pulltrusion process, resulting from water in the wood fibers, is discharged via a vacuum exhaust system.
The palltruded material is pneumatically discharged and conveyed to a Granulator to achieve a homogenous and even granule.
Depending on the requirement the Pallwood ® can be conveyed into a intermediate silo in front of the production machine.

 Palltruder®

Throughput capacity depends on feed materials, humidity and mixing proportion. Palltruder ® with capacities between 200 and 2.000 kg/h are available.

The Palltrusion is an important preparation step in order to produce a perfect feed material for the further Production processes. The agglomerate is homogeneous, free flowing and with high bulk density. It is dry, therefore a 20 – 50 % higher capacity on the extruder can be achieved. Preparation using friction heat only leads to minimum thermal degradation of the Pallwood ® .

Besides the Palltruder ® Pallmann supplies all machinery and installations for the preparation of wood and plastic, as well as the size reduction machines for the recycling of production waste.

During the K- Show 2004 on booth A 22 in hall 9 Pallmann will present the new Palltruder model for capacities up to 2.000 kg/h, equipped with a Colortronic gravimetrical dosing unit.

PLAST-AGGLOMERATOR PFV"N"

The PALLMANN Plast-Agglomerator is the machine for job. All thermoplastics such as polyethylene, polypropylene, polystyrene, polyamide, polyester, PVC, ABS etc. as well as mixtures (i.e. plastic-coated paper, wood-plastic mixtures, plastic powder mixtures. Plastics with organic or inorganic components etc.) can be continuously processed all in one system. Contrary to other processes such as extrusion, the thermoplastics in the Plast-Agglomerator are not heated to the melting point and are thereby only exposed to a minimum of heat thermo degradable damage. The advantages of this system are obvious.

The newest generation

In the newest generation of the Plast-Agglomerator, a wet agglomerating system is available. It allows the customer to process precut thermoplastic waste in a moist to wet condition to an agglomerate. The initial moisture content of the feed material can be between 30-40 %. The advantage is that a thermal drying process is not required after agglomeration, whit an achievable remaining moisture content of less than 1% in the end product. The customer achieves a first-class agglomerate with high bulk density which allows the feeding to an extruder without the use of a stuffing box. The Plast-Agglomerator, type PFV is available in different sizes with throughput capacities of about 60 to over 3000 kg/h. The system concept is adjusted to fit the specific requirements of the product to be processed. The PALLMANN Plast-Agglomerator system fulfills the various requirements and particulars of today's and future recycling tasks.

The new generation of the disc mill type "PKM"

• Pulverization of rigid PVC (i.e. pipe and profile    granules
• Pulverization of PE for rotomolding
• Pulverization of PE for textile and metal coating
• Pulverization of EVA for textile coating
• Pulverization of PP for fiber manufacture
• Pulverization of compounds for floor coverings
• Pulverization of caoutchouc for bitumen and asphalt

• Quality powders with best possible flow properties and high bulk density
• High throughput capacity at low specific power consumption
• Fully automatic, continuous operation
• Low demands on operating personnel
• Know-how and experience based on the installation of more than 600    pulverizing systems.

The new series PKM was designed for throughput capacities of 100 - 1000 kg/h. It is available with grinding disc diameters from 300 - 800 mm. A PKM 600 in the new design is available at PALLMANN's research and development center in Zweibrücken to perform test runs for the customer.