In-Line Drying of Glass Fibres by High Frequency Infrared Radiation
Topic(s) : Material science
Co-authors :
Pascal SZARKO (GERMANY), Deniz YESILYURT (GERMANY), Heiko WETTENGL , Thomas GRIESAbstract :
Glass fibres are among the most widely used reinforcing fibres in the light-weight construction sector, as they are characterised by an outstanding com-bination of high mechanical strength and low production cost.
During the production of glass fibres, a size is applied on their surface. The size fulfils the task of combining the single filaments into a roving and opti-mising the processability of the fibres by preventing static charging and im-proving the wettability of the fibres with the polymer matrix, as well as in-creasing their adhesion to it.
The size consists mostly of water, which remains as a liquid on the glass fibres during and after the winding process. Due to the high velocities on the glass fibre winder (several hundreds to thousands m∙min-1), the liquid size is getting pushed from the inner into the outer layers of the bobbin by the cen-trifugal force. This causes a gradient of the size content on the fibre surface - leading to quality issues that result into scrap waste of roughly 5% of the overall production.
Also, the water is removed in a downstream process using convection fur-naces. This process I both, time and energy intensive and resembles roughly 15% of the overall energy consumption of the glass fibre production.
A novel approach follows the idea of an in-line drying by high frequency in-frared light (peak wavelength: 1300 nm) of the glass fibres, replacing con-vection by radiation as heat transfer mechanism. The emitter is placed at the winder, facing the glass fibres on the cake/bobbin, to ensure the glass fibres repeated maximum contact time with the radiation. The radiation is absorbed by the glass fibres itself and not the water in the fibre size. This allows better transmission of the radiation through steamy atmospheres with high humid-ity, like they occur at glass fibre spinning lines.
This novel approach allows the production of glass fibres with smaller eco-logical impact than by currently standards, minimizing the overall down-stream energy demand of the process and avoiding production wastes. At the same time production costs are lowered.
Experimental data show that a complete drying of the glass fibres is already possible, without additional drying in convection ovens. At the same time the quality of the glass fibre (tensile strength) and the size (wetting, adhesion to matrix) is maintained by the new process. An Improvement of the infrared emitter to the winder geometries, as well as optimizing the composition fibre size is currently carried out to make the process even more efficient. Also, in-line measurement techniques for the residual moisture content of the glass fibres are developed, for instant tracking of the drying progress.
During the production of glass fibres, a size is applied on their surface. The size fulfils the task of combining the single filaments into a roving and opti-mising the processability of the fibres by preventing static charging and im-proving the wettability of the fibres with the polymer matrix, as well as in-creasing their adhesion to it.
The size consists mostly of water, which remains as a liquid on the glass fibres during and after the winding process. Due to the high velocities on the glass fibre winder (several hundreds to thousands m∙min-1), the liquid size is getting pushed from the inner into the outer layers of the bobbin by the cen-trifugal force. This causes a gradient of the size content on the fibre surface - leading to quality issues that result into scrap waste of roughly 5% of the overall production.
Also, the water is removed in a downstream process using convection fur-naces. This process I both, time and energy intensive and resembles roughly 15% of the overall energy consumption of the glass fibre production.
A novel approach follows the idea of an in-line drying by high frequency in-frared light (peak wavelength: 1300 nm) of the glass fibres, replacing con-vection by radiation as heat transfer mechanism. The emitter is placed at the winder, facing the glass fibres on the cake/bobbin, to ensure the glass fibres repeated maximum contact time with the radiation. The radiation is absorbed by the glass fibres itself and not the water in the fibre size. This allows better transmission of the radiation through steamy atmospheres with high humid-ity, like they occur at glass fibre spinning lines.
This novel approach allows the production of glass fibres with smaller eco-logical impact than by currently standards, minimizing the overall down-stream energy demand of the process and avoiding production wastes. At the same time production costs are lowered.
Experimental data show that a complete drying of the glass fibres is already possible, without additional drying in convection ovens. At the same time the quality of the glass fibre (tensile strength) and the size (wetting, adhesion to matrix) is maintained by the new process. An Improvement of the infrared emitter to the winder geometries, as well as optimizing the composition fibre size is currently carried out to make the process even more efficient. Also, in-line measurement techniques for the residual moisture content of the glass fibres are developed, for instant tracking of the drying progress.