Blended mesh is the answer

Innovative filter media are the trademark of GKD - Gebr. Kufferath AG, Düren, the internationally renowned technical mill for wire mesh made of metal, plastics or fibers. The medium-sized enterprise has decades of experience in making blends of the widest range of working materials, like plastic and stainless steel. With its fiber-wire composite, YMAX®,a mesh structure of monofilament stainless steel wires and metallic fibers, the filtration specialist managed two years ago for the first time to combine surface and depth filtration in a single media. Its core properties - high porosity, mechanical stability, flexibility, consistent distribution and stability of pores - make YMAX® filter media the best choice for applications like solid/liquid filtration in the range of 10 to 30 µm. Now, GKD is proud to present its latest filter media innovation, YTEX®, an extension of the YMAX®-family. YTEX® is also a multilayered blended mesh, but this time made of stainless steel and PTFE.

Recognizing the fact that classic textile or woven wire mesh contructions do not meet the full range of requirements for high-performance and robust filter media, GKD set itself the following task: to create a filter media capable of achieving constant and reproducable separation rates in the range < 25 µm which would combine antistatic properties, high mechanical stability, robustness, flexibility while maintaining great formability, high temperature resistance, and compatibility with sterilisation and backwashing as well as regeneration and a high degree of corrosion resistance.

Initial studies showed that the formability parameter in particular is optimally fulfilled by textile media. However, these media are limited in the degree to which their mechanical stability can be improved at high temperatures. Textile media also offer little potential for the achievement of the sort of antistatic properties required, for example, in the field of solvent filtration. On the other hand, achieving finer retention rates with classic wire mesh media is almost always associated with the necessity of compromises in terms of their normally high mechanical stability.

Innovation: antistatic properties through composite material
By combining metallic mono- and multifilaments, GKD developed the fiber-wire composite YMAX®, which in the meantime has proved itself with distinction in initial industrial applications. Now the filtration experts at GKD are working on the next stage, the further development of this mesh construction with the aim of integrating a textile media. To do this, they have picked up on a concept developed by GKD back in the 70s, Duofil®. Duofil® meshes are square mesh structures made of a combination of monofilament wires and rods of polyester and stainless steel or polyamid and stainless steel.
This combination of materials has very good antistatic properties which make for astounding improvements in performance, particularly in the field of gravitational draining. However, Duofil® meshes are not capable of achieving retention rates < 50 µm. In addition, so far the working materials used, polyester and polyamid, only have a limited resistance to the effects of temperature or chemicals. This led GKD to consider the use of high-performance textile fibers. Collaboration with the company Filtec/Düren produced a thread based on PTFE which meets the technical requirements for weaving and filtration.

Problem-solver for pharmaceutical process technology
The basic mechanical structure of the result of this research and development, the latest member of the YMAX®-family, YTEX®, is analogous to the structure of YMAX®, i.e. it consists of monofilament stainless steel wires. These ensure a very high degree of mechanical strength and robustness. The textile component integrated into this construction is EMMITEX® thread. The stainless steel wires thus have the dual function of providing the basic construction and a protective layer. This combination of the stainless steel surface's tensile strength and corrosion resistance with the flexibility of the textile material opens up a range of application perspectives for the new filter media. In addition to practically unlimited resistance to chemicals, the high-performance material EMMITEX®- PTFE also has a comparatively high tensile strength for a polymer material as well as very high resistance to temperatures of up to 260°C.

The combination of this working material with stainless steel gives YTEX® comprehensive antistatic properties and full backwash capability at retention rates of 20µm. This makes YTEX® an optimal choice especially for the pharmaceuticals industry, for example in nutsch- type pressure or centrifugal filtration. Because of its resistance to chemicals and its antistatic properties, the new blended mesh offers the solution to filtration tasks involving solvents, which has so far been a highly problematic area. Safety problems or limited throughflow properties due to static charging can be completely avoided by using YTEX®. The mechanical properties of the innovative filter media mean that is can also be used without difficulties in apparatus originally designed for purely textile media. Thanks to its high resistance to temperature, the filter media can be completely sterilised. And corresponding modifications can be made for highly corrosive applications. By using stainless steels like Hastolloy C22/C276 for the metallic basic construction, even large-scale applications like nutsch-type pressure filters can be achieved at relatively low costs with YTEX®.

This latest addition to the blended-mesh product family YMAX® is once again convincing evidence of GKD's great innovative strength. Pioneer weaving technology and consistent further development of raw materials has now produced the multilayered mesh structure YTEX®, made of stainless steel monofilaments and PTFE fibers, which represents a considerable extension to the range of available filter media, especially for pharmaceutical processes.