Paper Technology International 2020 - Journal - Page 57

PAPERTECHNOLOGYINTERNATIONAL
Reliable and simple determination of stickies applying NIR measurement – establishing a new standard for the paper industry.
Dr.-Ing. Linus Friedrich, Senior Manager R&D Technology & Digitalization, Voith Paper
Martin Fröbus, Engineer R&D Technology & Digitalization, Voith Paper
Sebastian Schuster, Product Manager OCC Systems, Voith Paper
Falk Albrecht, Head of Process Technology Fiber Systems, Voith Paper
INTRODUCTION:
Stickies are tacky contaminants within recycled pulp that impact the papermaking process negatively, causing web breaks at
the paper machine and resulting in production losses. Today’s laboratory sticky measurements are mainly conducted according to ISO
15360-2 [1], within which the measuring procedures according to TAPPI T277 [2] and INGEDE 4 [3] are summarized. These methods are
well established in the paper industry, require an extensive sample preparation and a variety of manual working steps.
Determining the sticky content of stock samples using the near-infrared (NIR) macro sticky measurement method provides
several advantages compared to the laboratory methods established in the paper industry. The accuracy of this measurement technique
is significantly higher, and the effort to prepare and evaluate samples is noticeably lower compared to today’s measuring techniques. To
standardize sample preparation and the measuring procedure, the technical rule DIN SPEC 6745 [4]: “Paper, board and pulps - Recycling
- Determination of stickies and non-tacky contaminants in recycled pulps and papers applying near-infrared measurement” was elaborated
and published in March 2020. Due to its technological and technical advantages, as well as the availability of a technical rule to prepare
samples and perform measurements using the NIR measurement technique, this new approach to measuring macro stickies has the
potential to supersede existing measurement techniques in the future as a new standard for the paper industry.
This paper presents Voith Paper’s experiences in performing sticky measurements according to DIN SPEC 6745, applying the NIR
measurement technique. The results of measurements made using a PTS NIR macro sticky measurement device, which was installed in
June 2020 at Voith Paper’s laboratory, will be discussed and compared to results of established measurement techniques.
State of the art – measuring stickies according to ISO 15 360-2
Measuring stickies according to ISO 15360-2 “Estimation
of Stickies and Plastics - Part 2: Image analysis method” [1] is
well established and proven within the paper industry. Two main
procedures for measuring stickies are described in ISO 15 360-2,
following the measuring procedure described in:
1. TAPPI T277 – “Macro stickies content in pulp: the “pickup” method” [2]
2. INGEDE 4 – “Analysis of macro stickies in pulps” [3]
The measuring procedures described in these norms are
generally similar; but, single process steps and equipment to be
used may vary such that measuring results will differ depending on
the procedure chosen.
Since sticky samples are evaluated at Voith Paper according
to TAPPI’s “pick-up method,” the sticky measuring procedure
according to ISO 15 360 - 2/ TAPPI T277 is shown in Figure 1. In
total, eight steps are needed to prepare the sticky sample and to
measure the white-colored stickies using a conventional scanner.
Typically, a laboratory technician needs 100 to 120 minutes to
evaluate a single stock sample.
Figure 1: Procedure to measure stickies according to ISO 15 360 - 2/ TAPPI T277
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