The high quality and low grammage of spunlaid nonwovens make them suitable for a range of applications, which is why they currently rate as one of the most important trends in the growing market for nonwovens. Over 80% of such nonwovens are used for hygiene and medical sector products which means high standards for the production of spunlaid nonwovens in ever thinner, lighter and more efficient forms.
The international technical weaving company, GKD – GEBR. KUFFERATH AG, specialises in the spunlaid process from consulting and design to production and service. It believes the strongest growth in the technical textiles sector is with applications for hygiene and medical products, with a particularly high demand for spunlaid products.
Demographic development
The driving factor behind this trend is demographic development. At one end of the scale, increasing life expectancy leads to higher demand for products tailored to the needs of older people, for example regarding incontinence, wound healing and infection control.
At the other end, the growing world population and rising standards of living in many regions are reflected in an increasing demand for baby-care and cosmetic products. As a result, manufacturers must consistently optimize the efficiency and productivity of the single-stage spunlaid process.
GKD’s mesh construction and selection of materials optimize the efficiency and productivity of the spunlaid process. (source: GKD)
Whether for filter media for central filters and spin beams, quench screens and laydown belts,GKD's mesh constructions and selection of materials make an important contribution towards the integrated adaptation of spunlaid processes to the ever-increasing demands of the converting industry.
Optimized plain dutch weave meshes
In the polymer filtration stage, this contribution is primarily through optimised plain dutch weave meshes (ODW) made of stainless steel. Thanks to their special construction, these meshes combine precise filtration with low differential pressure and long service life. The slot-shaped pores on the mesh surface are smaller than the pores inside the mesh. Particles above the cut point are retained directly on the mesh surface. In this way, ODWs also reliably filter out poorly dispersed additives and solid particles. Gel-like impurities in the melt are crushed by the shearing forces that arise. Their precise separation rates, high dirt-holding capacity and low clogging tendency make ODWs suitable for deployment in several aggregates in the spunlaid process. In screen changers, for example, this mesh type is deployed as a multi-layer construction in process-specifically assembled filter discs or cartridges.
Optimized plain dutch weave meshes from GKD combine precise filtration with low differential pressure and long service life. (source: GKD)
When designing the mesh configuration, GKD makes use – if required – of its own in-house further development, the integrated simulation environment, Weavegeo. This enables the company to modulate the mesh configuration precisely to the requirements of the individual application and to simulate the specific process of polymer filtration. The knowledge and insights acquired through the simulation in the laboratory are then implemented on GKD's technical looms to produce customised products, cut to size and ready for use. In the central filter, screens consisting of five to six filter layers with separation rates of 10 to 40µm are used, covered with a protective mesh if the particular application requires this. In the spin beam, several layers of made-to-measure, phased meshes filter the flow of the melt and thus improve the service life of the spinneret.
Manufacturing these frame-mounted long filters or filter discs, which can be up to 6 m in size, calls for engineering expertise and precise selection of media to match the specific application so that the filter packet construction ensures the required level of process success is achieved. Here, too, thanks to quality control and automated cleaning of the mesh before cutting to size, GKD is able to guarantee the production reliability demanded by high-quality spunlaid products.
These are preconditions that are equally beneficial for rectifiers. These screens – arranged on one or both sides of the fibre flow, harden the still-hot continuous filaments by quenching them with cold air before the laydown section. For the construction of such quench screens, large-format honeycomb carrier plates are covered on both sides with specially pre-treated mesh and mounted in a frame. GKD’s high-precision meshes and coverings guarantee the flow homogeneity needed for trouble-free fibre flow.
With its electrostatically conductive laydown belts made of meshes from the Conducto® and Conductive® ranges, GKD is able to take on the fourth and final stage of the spunlaid process.
Due to the bronze wires or graphite filaments woven into their warp, and to their non-marking pin seams, these endless polyester belts substantially increase the safety of the integrated process flow, constantly conducting away, through their contact with the metallic rollers, any electrostatic charge caused by the process itself.
The electrostatically conductive laydown belts made of meshes from the Conductive range. (source: GKD)
In addition to the production reliability the belts provide throughout this feature, their efficiency is increased by their low fibre penetration, uniform card web formation, customised air permeability, nonwoven discharge and adhesion in the laydown section.
The combination of its integrated engineering and consultancy experience and its expertise in manufacturing has made GKD an important contributor to the spunlaid processes’ sector, offering a comprehensive service from a single source.
