Plastics and elastomers
Mixers, drying mixers, reactors, and evaporators for perfect process engineering solutions
Due to an ever increasing spectrum of applications, the plastics and elastomer industry has become an exciting challenge for AVA. In order to match containers and agitator geometries as well as peripheral speeds to the corresponding task, we employ our extensive process-relevant expertise and product database. In doing so, we concentrate specifically on the individual and specialist products and thereby create a tailor made solution for our customers.
The proven high reliability of AVA mixers and dryers is supported by means of our 24 hour service which guarantees the high availability of AVA machines.
AVA supplies horizontal mixing reactors as core production plant components for the manufacture of insulation boards and insulating materials made from rubber and cork granules, which can be batch or continuous depending on the application. In addition to the excellent moistening of the rubber and cork granules with the binding agent, a particular feature is the complete emptying and good cleaning characteristics of the machine.
For this purpose, AVA developed a special discharge flap, which serve to guarantee the complete emptying of the mixer in a very short space of time. In addition, the inner side of the mixing drum is equipped with a coating which prevents sticky granules and binding agent from adhering. This coating increases the availability of the mixer and therefore that of the entire production plant. The expectations of our customers were exceeded by far.
The mixer is coated completely with a special plastic for air and moisture hardening rubber adhesives. The centre of the drum can be opened completely for simple cleaning. The agitator can also be dismantled in just 15 minutes with this machine design, without the need for dismantling the bearing.
"Continuous stripers" for polymer powder manufacturing
Often in the production process for plastic powders, a solvent such as methanol or alcohol is used, which then has to be completely evaporated again at a later stage. Depending on the consistency of the product, evaporating the solvent is not always particularly easy and the drying process often finishes with residual moisture content in the range of 3% - 5%.
At this point, evaporation has to be supported by means of adding pre-heated nitrogen, dry-saturated steam or hot air, the so called “stripping” process, in order to achieve a residual moisture content of 0%. AVA supplies a “continuous stripper” especially for this problem formulation in an ATEX-conforming design, with a special agitator, which supports the flow of the plastic powder with the carrier medium, but also serves to guarantee heat transfer by means of a cylinder jacket.
Due to the geometry of the agitator, a high level of re-mixing is achieved and the retention time in the dryer is increased. This guarantees a constant temperature and humidity in the entire dryer as well as a homogenous and dry end product.
In order to increase the production output of extruders and injection moulders, the flow and processing characteristics of plastic granules has to be modified. Especially for polyamides (PA) and polystyrene (PS) this occurs by means of powdering (coating) with powder additives. In doing so, two different methods are employed. The pure dry mixing of plastic granules with the powder additives and the moistening of plastic granules with liquid binding agents / powder additives. With both methods it is necessary to create an extremely homogenous end-product with very high repeatability, in order to guarantee a sustained product quality, as any deviation in quality immediately shows up as a flaw in the surface during the subsequent processing in the extruder or the injection moulding machine.
The AVA horizontal mixers of type HTC (batch operation) and HTK (continuous operation) achieve best results in terms of homogeneity under high throughput performance. As the mixing and detention times in the mixers are very short, a fast moistening of all plastic granules with the binding agent and additives without product damage is vital. For this reason the machines are adapted to the corresponding customer’s requirements and are designed for gentle or turbulent mixing. This mixing optimisation enables AVA’s customer’s high quality requirements to be achieved superbly for both processes.
The high availability of the AVA mixers and the constant extremely good qualities of the intermediate and end products are the guaranteed advantages in daily operation for the benefit of our customers.
Superabsorbers (SAP, superabsorbent polymers) are plastics, which are able to absorb 1000 times their own weight in liquid. The main areas of application are baby nappies as well as products for female hygiene and incontinence care. The problem formulation for AVA was to improve the existing SAP product quality, to increase the throughput of the overall plant, and to enable several process stages to be undertaken in one machine. Due to the product changeover from batch operation to continuous operation with AVA mixers of type HTK, the throughput performance of the overall plant could be increased by more than 50%. Turbulent mixing with the adjustable AVA paddles enabled the addition and dispersing of liquid additives into the AVA mixer. The upstream process stage for moistening the SAP powder was thereby saved.
Thanks to this increase of capacity, the existing plant could be used by our customer to considerably reduce production costs, without having to replace the complete plant technology.
Deciding Facts – Plastics and Elastomers
- Horizontal or vertical, batch-wise or continuous - the optimal solution for your application
- Top mixing quality levels free from thermal load
- Short drying times thanks to optimal heat transfer
- Final moisture content in the ppm range after drying
- High machine availability
- Steel materials like 1.4301, 1.4404, 1.4571 or special materials such as 1.4462/1.4539 through to Hastelloy/alloy and titanium-grade materials
- Design according to ATEX directive 2014/34/EN
Requirements relating to products and processing operations are constantly on the rise. AVA has the necessary experience and expertise to provide you with innovative yet reliable mixing and processing technology.