In cooperation of partners representing the textile finishing industry and textile machinery industry assisted by textile institutes sensor systems were developed to control:
- H2O2 concentration in the bleaching process,
- relaxation behaviour of textiles during heat-setting and
- relaxation behaviour during stabilization of mercerized cellulosic textiles.
For the H2O2 sensor-system the voltammetric technique was chosen. The evaluation of the oxidation signal and working with a special prepared glassy-carbon electrode turned out the most successful method measuring the high concentration of H2O2 in a bleaching bath.
Using this system, a compensation of pH-value and temperature is needed. The automatic control system being implemented into the bleaching process on production line delivers reproducible and reliable results.
The registration of accurate relaxation tensions in dimensional controlled continuous processes requires the adaption of sensor-systems stable in relation to outstanding environmental conditions. In a stenter frame the most outstanding conditions are the high temperature (250 C). The sensor-system developed using piezo load sensors gives indication that the system is sensitive enough to register the small changes in tension as a function of time at a given temperature. The results are of innovative and commercial interest. The aspect is seen in the quite advanced form of registering tension of the individual fabric being still under process conditions. A patent has been taken out for the sensor system.
The registration of accurate relaxation tensions in the dimensional controlled stabilization-step of mercerizing machine 'Dimensa' requires a sensor system with an outstanding stability to high concentration sodium hydroxide solution at elevated temperatures. Suitable sensors meeting this requirements are not available at the time. Therefore, the change in tension during processing was measured by a robust indirect measuring system a so called 'Messbolzen-System'.
From the analysis of the loads measured at the different positions of the stenter frame it can be concluded that the load measured at the end of the extension field gives information about an average tension of the fabric in process. This tension is also in a very good agreement with the textile properties like dyeability and dimensional stability.