Figure 4 compares the theoretical air velocity distribution (top) around a semi-sphere mould to the experimental data (bottom). The agreement between the two is very satisfactory. Figure 5 compares the theoretical temperature distribution in the bonding chamber (dotted line) to the experimental data (large dots). There is good agreement between the two results. In order to achieve uniform web property, the temperature distribution must be controlled within a very tight range, typically 1 (K). This should also be achieved quickly to reduce the cycle time which determines the production speed of the process. Figure 6 shows an example of a 3D nonwovens structure that was produced using the new technology. Products of various other shapes and web area densities have been successfully produced.
Conclusion
Seamless 3D nonwoven shell products can be produced directly from staple fibres using air-laying and thermal through-air bonding. This can significantly reduce the cost of many products and eliminate the property variation caused by joints.