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Specific security levels Paper media requirements P-1
12 mm strips or maximum particle surface area of 2.000 mm 2 6 mm strips or maximum particle surface area of 800 mm 2 2 mm strips or maximum particle surface area of 320 mm 2
P-2 P-3 P-4 P-5 P-6 P-7
Maximum cross cut particle surface area 160 mm 2 with a maximum strip width of 6 mm = 6 × 25 mm Maximum cross cut particle surface area 30 mm 2 with a maximum strip width of 2 mm = 2 × 15 mm Maximum cross cut particle surface area 10 mm 2 with a maximum strip width of 1 mm = 1 × 10 mm Maximum cross cut particle surface area 5 mm 2 with a maximum strip width of 1 mm = 1 × 5 mm
Table 1. Requirements for machines and processes shredding documents (DIN 66399).
practices suggests shredding paper only when necessary 20 , especially since destruction also increases the bulk density of the paper, reducing its transportation efficiency. The office waste problem is particularly significant because of the high amount generated. For example, Japan has a paper collection rate of around 81.6% 21 , which is higher than that of other countries. However, this high collection rate is mainly constituted by a high recy- cling rate for paper grades such as cardboard and newspapers. The collection rate for office paper and shredded paper remains low (less than 60%) 21 because office paper, on which confidential information is often printed, is generally disposed of. In U.S. offices, 50% of business waste is composed of paper. Offices use approximately 12.1 trillion sheets of paper per year, and paper accounts for 25% of landfill waste and 33% of municipal waste. It was found that each tonne of recycled paper allows for 64% energy savings, 58% water savings, and 60 pounds less air pollution 22 . Security issues aside, one should consider how to efficiently destroy documents while still allow- ing fibres to be efficiently used in further processing, which will enable the above savings; this paper attempts to address this issue. Paper destruction categories are assigned based on the standard German Deutsches Institut für Normung (DIN) classification for paper shredding machines. DIN 66,399 classifications, in which ‘P’ refers to ‘Paper-Based’ material, are based on the size and type of particle (Table 1). The aim of this study is to examine the effect of the surface area of shredded particles on paper properties. The study therefore estimates the extent to which waste paper can be shredded while still producing a high-quality product. Pulp samples with different initial particle sizes treated under constant papermaking conditions were used for this purpose. Ǥ Industrial air-dried and bleached kraft pine pulp in the form of sheets (Arctic Paper Kostrzyn S. A.) was used in this study. In order to keep all other parameters constant, samples of the pulp were cut manually into squares of different areas (1–400 mm 2 ) to reduce and diversify the fibre length. Hand-cut samples were compared with strips from shredding machines (destroyed in accordance with DIN 66399). The following shredders were used for the tests: Kobra 240.1 S2 ES (for strips with P-3 specific security levels), HSM Shredstar S5 (for strips with P-4 specific security levels), HSM Securio C18 (for strips with P-5 specific security levels), and HSM Securio B26 (for strips with P-6 and P-7 specific security levels). All cutting processes in the shredders were performed without the addition of oil. Ǥ Sheets of paper from the cut samples were produced under laboratory conditions from rewetted pulp samples (22.5 g dry weight samples were soaked in water for 24 h) that were subjected to disintegration using a laboratory JAC SHPD28D propel- ler pulp disintegrator (Danex, Katowice, Poland) for 23.000 revolutions, according to ISO 5263-1 (2004). The disintegrated pulps were concentrated to a dry weight content of 10% and refined in a JAC PFID12X PFI mill (Danex, Katowice, Poland) under standard conditions [ISO 5264-2 (2011)]. All the samples were refined for a constant time of 120 s. After the model pulp recycling processes, including refining, the following properties of the pulps were evaluated: • Schopper-Riegler freeness parameter (SR) was measured using a Schopper–Riegler apparatus (Danex, Kato- wice, Poland) in accordance with PN-EN ISO 5267-1 (2002); • The water retention value (WRV) was determined according to ISO 23714 (2014); • The dimensions of the fibre parameters were measured according to ISO 16065-2 (2016) using a Morfi Com- pact Black Edition apparatus (Techpap, Grenoble, France). In the next step, sheets of paper were formed in a Rapid-Koethen apparatus in accordance with PN-EN ISO 5269-2 (2007). Each paper sheet had a basis weight of 80 g/m 2 (according to ISO 536:2012). Only sheets with basis weights between 79 and 81 g/m 2 were used for further investigation. The sheets were conditioned for 24 h at a relative humidity of 50 ± 2% and a temperature of 23 ± 1°C [ISO 187 (1990)] before determining their properties. The properties of the paper sheets were examined as follows. A ZwickRoell Z005 TN ProLine tensile testing machine (Zwick-Roell, Ulm, Germany) was used to measure the mechanical properties of the paper in accordance with PN-EN ISO 1924-2 (2010). The roughness and air permeability were measured using a Bendtsen apparatus (Messmer Buchel, Veenendaal, The Netherlands).
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(2021) 11:17528 |
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