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Compounding of shear-sensitive soft PVC

IKO decides in favor of a Coperion Kombiplast

IKO produces the necessary soft PVC compound for the manufacture of its high-quality, multilayer roofing membranes on a two-stage Kombiplast extruder – Model KP 62 Mv PLUS/200.
IKO produces the necessary soft PVC compound for the manufacture of its high-quality, multilayer roofing membranes on a two-stage Kombiplast extruder – model KP 62 Mv PLUS/200.

IKO PLC, whose headquarters are in Wigan/UK, has for the first time decided in favor of one of our compounding systems: a Kombiplast KP 62 Mv PLUS/200. At IKO Polymeric's production facility in Chesterfield/UK, the new extrusion system is being used for the plasticizing and compounding of soft PVC destined for the production of multilayer roofing membranes for the waterproofing of flat roofs. IKO PLC is a member company of the international IKO Group, which specializes in high-quality roofing systems for both private and commercial buildings.

The Kombiplast has been developed specially for the gentle compounding of temperature and shear sensitive polymers such as PVC, cable and other special-purpose compounds. Operating in two stages, the Kombiplast consists of a ZSK twin screw extruder, into which the starting materials are metered via a ZS-B side feeder and then plasticized, mixed and homogenized. The downstream ES-A single screw discharge unit gently builds up enough melt pressure for the subsequent pelletizing in the EGR eccentric pelletizer. IKO’s Kombiplast KP 62 Mv PLUS/200 features a screw diameter of 200 mm. Andrew Salmon, General Manager at IKO's site in Chesterfield, says: “Whilst Coperion guaranteed us a throughput as high as 2,400 kg/hour, we can in fact operate the machine at up to 2,700 kg/hour with no loss of process stability while maintaining exactly the same high quality of compound.”

What is particularly special about IKO's new compounding line is that it is being operated without the cold mixer that is frequently required upstream when compounding soft PVC, as the preheated pre-blend must normally be cooled down again prior to plastification. With the Kombiplast, IKO can meter the hot pre-blend straight into the extruder, thus maintaining high energy efficiency and, by the same token, keeping down the production costs.

After only a few months' practical experience with the new compounding system, Andrew Salmon can already say: “As our products must not show any fluctuations in color whatsoever, the extrusion system we were looking for obviously had to produce a particularly high quality of product. Many users advised us to invest in a Kombiplast from Coperion, especially as it is also distinguished by its gentle product handling. Today we are pleased to say that we made absolutely the right decision.”

Your contact:
Daniel Nagl, Phone: +49 (0)711 897 2502, e-Mail

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Coperion and Muhr have entered into an exclusive cooperation

High rate and high filling efficiency railcar loading systems

Railcar loading spreader unit
Railcar loading spreader unit

Coperion has been awarded a contract for the supply of high rate and high filling efficiency railcar loading systems for polyethylene pellets. Four loading stations will load railcars with a loading capacity of up to 400 t/h in 20 minutes or less to a filling efficiency of ≥95%.

The loading efficiency and capacity will be achieved with proven product spreading technology developed and patented by Erhard Muhr mbH from Brannenburg, Germany. Coperion and Muhr have entered into an exclusive cooperation for the development, marketing and implementation of railcar loading technology for polymer pellets.

The Muhr technology utilizes a novel spreader blade form that uses recoil forces to gently accelerate the pellets propelling them into the far corners of the railcar compartments. Extensive railcar loading tests in Coperion’s technical center including the new blade form have proven the high rate and filling efficiency as well as the gentle handling of the product characterized by a comparatively low spreader rotation speed.

Each of the four loading stations will be equipped with four individual loader sets each comprising a horizontal positioner, telescopic loader and the spreader. All four loader sets will operate simultaneously filling all 4 railcar compartments together.

Each loading station is equipped with fit for trade railcar scales to monitor the filling process, record the actual net product weight and to prevent overloading the railcar when filling with heavier products.

The intelligent control system from Coperion featuring frequency regulated spreader motor drives and I/P regulated feeder slide valves is fully interfaced with the railcar scales and automatically adapts the filling process to the individual product characteristics. It also regulates the filling of the larger outer and smaller inner railcar compartments proportionately, ensuring that the outer compartment filling process is completed before that of the inner compartments, satisfying the railroad railcar balance requirements.

The spreader unit has been optimized, effectively minimizing the number of parts and consequently maximizing operational reliability. The horizontal positioner is pneumatically operated, further reducing maintenance and moving parts. The telescopic loader benefits from decades of Muhr development resulting in an operator friendly, reliable and safe design.

This railcar loading technology satisfies the highest demands of the polymer producing industry, once again confirming Coperion’s place as the most reliable partner for the whole polymer producing process chain. Coperion and Muhr have complimented their companies expertise and market presence and are now ideally prepared to serve the surge of shale gas development project requirements.

Your contact:
Malcolm Cartwright, Tel.: +49 (0) 751 408 546, e-Mail

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Selection of the appropriate feeding system

Feeding of calcium carbonate in plastics compounding

Fig. 1: Loss-in-weight feeders dispense dry bulk materials into the process at a constant weight per unit of time
Fig 2.: To prevent flooding with free-flowing grades of CaCO3, twin-screw feeders are recommended

Calcium carbonate (CaCO3) is one of the most popular mineral fillers used in the plastics industry. It is widely available around the world, easy to grind or reduce to a specific particle size, and compatible with a wide range of polymer resins. Plus it’s economical.

As an additive in plastic compounds, CaCO3 helps to decrease the surface energy and provide opacity and surface gloss, which improves the surface finish of the finished product. In addition, when the particle size is carefully controlled, CaCO3 helps to increase both the impact strength and flexural modulus (stiffness) of the end product.

The selection of the appropriate feeding system for calcium carbonate is determined by two main variables: the characteristics of the mineral filler (for instance, the particle size and shape, gas permeability, bulk density and angle of repose) and the required feed rate.

Loss-in-weight (LIW) feeders, such as the one shown in Fig. 1, provide total containment of the raw material and dust and optimal feed rate performance to assure overall end product quality. LIW feeders are available in a variety of configurations, so that the hopper size, feeding device and weighbridge can be tailored to the specific material characteristics, flow properties and flow rates for the material to be fed.

Volumetric vs. gravimetric feeding
Most feeders may be categorized as volumetric or gravimetric. Volumetric feeders operate by delivering a certain volume of material per unit time and are typically the feeding solution with the lowest capital cost. However, volumetric screw feeders cannot detect or adjust to variations in a material’s bulk density during operation. As a result, these feeders are typically most effective with relatively free-flowing materials that have consistent bulk density, such as pellets, and in applications where a guaranteed feeding accuracy is not crucial to the operation.

During gravimetric feeding, dry bulk material is fed into a process at a constant weight per unit of time. Gravimetric feeding provides better monitoring of the feeding process by providing a feedback loop that measures weight and speed. This helps to determine the actual weight of material being fed on a second-to-second basis.

Hopper selection
Once the size and type of feeder is established, a hopper of the appropriate shape and size must be selected to contain the right amount of filler required for the continuous plastics-compounding operation. Hoppers are available in cylindrical, asymmetrical and symmetrical shapes, and in sizes ranging from one liter to several hundred liters.

A feeder hopper is sized based upon the refill requirements of the feeder and the physical space available at the site. A general rule-of-thumb for calculating the appropriate size is 12 hopper refills per hour, with the maximum fill level in the hopper at 80% of the hopper volume.

Precipitated calcium carbonate tends to compact in hoppers and may cause the formation of flow-stopping ratholes and bridges. Flow-aid devices that work by inducing particle-particle vibrations - such as Coperion K-Tron’s ActiFlow® - should be considered to ensure predictable flow by preventing the formation of highly dense material zones inside the hopper. In addition, this approach can help to reduce headroom requirements and eliminate cleaning concerns because there is no need to use mechanical agitators inside the hopper. For extremely cohesive materials alternative mechanical agitators are available.

Feeding devices
Feeding devices vary depending on the bulk material to be fed: single screw or Bulk Solids Pump™ (a patented product by Coperion K-Tron) for free-flowing powders and granulates, twin-screw feeders for difficult powders (Fig. 2), vibratory trays for fibers and friable materials.

While a single-screw feeder may work with free-flowing grades of CaCO3, a twin-screw feeder is generally recommended to achieve a reliable result. A variety of screw designs are available according to the flow rate and characteristics of the mineral filler.

Conclusion
Because calcium carbonate is so widely used in plastics-compounding operations, it is important to appreciate how much the success of the overall operation depends on its feeding solution. The correct design of feeding systems for calcium carbonate is not a trivial proposition. There are a number of variables that affect the flow of this often difficult powder, and the return on investment of a plastics-compounding plant is directly impacted by the proper selection of the feeding system.

Your contact:
Jim Foley, Tel.: +1 856 256 3250, e-Mail

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We look forward to seeing you there

Trade shows and presentations in spring 2015

Right at the beginning of 2015 Coperion will be represented at many trade shows and conferences. Visit us at our booths or at one of the conferences. We look forward to your visit!

Trade shows

Arabplast 2015

Dubai / UAE
Jan 10 - 13, 2015
Hall 5, Booth no. 5D104

INTERPLASTICA 2015

Moscow, Russia
Jan 27 - 30, 2015
Hall FO, Booth no. FOD43

Plastindia 2015

Gandhinagar, Gujarat / India
Feb 05 - 10, 2015
Hall 8, Booth no. 8-D10

NPE 2015

Orlando, FL / U.S.A.
Mar 23 - 27, 2015
West Hall, Booth no. W-1329

Follow this link to find an overview of all trade shows Coperion will be attending:
www.coperion.com/en/news/events/

Conferences

SPE Polyolefins Conference 2015
Feb 22 - 25, 2015
Houston, TX / USA
Processing of Bimodal Polyethylene with ZSK Technology
Frank Lechner, Head of Process Technology Compounding & Extrusion, Coperion GmbH, Germany

Compounding World Congress 2015
Apr 21 - 23, 2015
Cologne, Germany
Compounding of Highly Filled Polymers with the Co-rotating Twin Screw Extruder
Frank Lechner, Head of Process Technology Compounding & Extrusion, Coperion GmbH, Germany

Follow this link to find the programme of the conference:
Compounding World Congress 2015

Follow this link to find an overview of all conferences where Coperion will be giving presentations:
www.coperion.com/en/news/conferencedates/

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