Paper Technology International 2020 - Journal - Page 59

PAPERTECHNOLOGYINTERNATIONAL
Figure 3: Comparing sticky measurements according to ISO 15 360 - 2/ TAPPI T277 to DIN SPEC 6745 for OCC samples – where
macro stickies > 150 µm are plotted for both measuring principles
•
•
Repeatability to determine sticky loads from a stock sample
(within a laboratory): 18.0% maximum deviation between two
results.
•
Note: For three different samples series (different sticky
loads) that were also used for the study in Chapter
2, the complete sample preparation process was
conducted three times each by different lab technicians.
The calculations for the repeatability was followed as
described in [5, 6].
Reproducibility (between laboratories) will be elaborated in
the near future in a joint project between PTS Heidenau and
Voith Paper.
Due to the increased accuracy of the NIR sticky
measurement according to DIN SPEC 6745, the number of
measurements to be performed, e.g., during a guarantee run, can
be reduced in the future. When conservatively halving the number
of repetitive measurements from 12 to six samples for NIR sticky
measurements according to DIN SPEC 6745, the total laboratory
effort is reduced from 22 hours to five hours only at increased
accuracy and reliability of the sticky measurement results.
Comparison between ISO 15 360 - 2/ TAPPI T277 and DIN SPEC
6745 sticky measurements
Since sticky measurements results according to ISO 15
360 - 2/ TAPPI T277 are well established in the paper industry,
comparing the results of sticky measurements that are made
according to the new DIN SPEC 6745 to the established ISO
15360 - 2/ TAPPI T277 may help the paper industry to better classify
the new measurement results. For this purpose, more than 70
comparing measurements were conducted, where for the same
stock samples, sticky values according to ISO 15 360 - 2/ TAPPI
T277 and DIN SPEC 6745 were determined in parallel.
The results summarized in Figure 3, where the sticky
measurement results according to DIN SPEC 6745 are plotted over
the sticky measurement results according to ISO 15 360 - 2/ TAPPI
T277, revealed that the sticky measurement results according to DIN
SPEC 6745 were higher than results according to ISO 15 360 - 2/
TAPPI T277 for samples taken from OCC plants in Europe. Due to
the high scatter of the sticky measurement results according to ISO
15 360 - 2/ TAPPI T277, the regressions coefficient of determination,
R², was low as expected. The findings summarized above, impact
the definition of sticky reductions as follows:
Figure 4: Sticky reduction for same process technology due to different measuring techniques – example for OCC samples
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