The wood input has been reported as bone dry solid wood under bark. The species are specified, although in the datasets they are reported only as softwood or hardwood. 92% of the pulp wood used for the production of corrugated base papers by the companies returning the survey was certified and third party verified as being sourced from sustainable managed forests and delivered through a certified chain-of-custody system (PEFC or similar). A pulp yield (oven dry pulp/oven dry wood) of 54-56% is normal for Kraftliner. A high pulp yield of 80-85% is normal for Semi Chemical Fluting. The input of recovered paper has been reported as total weight including moisture and other materials (sand, metal objects, plastics, wood etc.). In European countries the water content of recovered paper is generally assumed to be about 10%. The total input of recovered paper is given. The content of other materials in the recovered paper is about 5%. These materials are eliminated from the pulp as rejects during the pulping. It is estimated that about a third of these rejects are materials that were associated with the previous use of the paper (for example, staples, paper clips, tags, adhesive labels, unrecovered fibres, etc). The remaining two thirds is material that is not in any way associated with the previous use of the paper (for example, foreign items such as textiles, plastic packaging, glass, sand and grit, etc). The main raw material inputs for corrugated board production are different grades of paper. The liners are used for the surface layers of the corrugated board, fluting is used for the corrugated layers. There are endless possibilities for the composition of corrugated board. The amount of the different grades of paper and glue used as input for the corrugated board production varies accordingly. These inputs should be considered when the LCA of a certain box is studied. An example is given in Figure 6. This should be kept in mind when considering the averages for paper consumption and the additives for corrugated board production in Table 4.
Chemicals and other non-fibre inputs
Data were collected for chemicals and other non-fibre inputs which may be used either within the process or as additives. Chemicals are given as dry weight. Some of the inputs have been reported grouped together according to their function in the mill. The functional additives, mainly starch, influence the properties of the paper, whilst process additives are used to guarantee that the process of paper production runs smoothly or to increase the production. Water treatment additives include additives used for all water treatment on the site, including the treatment of water for the power station, paper production and waste water treatment
if this is done internally. The different mills use a large variety of process and water treatment chemicals. Those that are commonly used and are above the cut-off criterion per mill are reported in the database. A very limited quantity of other additives, e.g. synthetic polymers (polyethylenamine, polyacrylamide, polyvinylamine) are being used. The main input for corrugated packaging is starch glue, containing starch and small amounts (less than 0.5 kg/tonne nsp) of caustic soda, borax, and wet strength agent. Only a few plants laminate
the board and/or add a protective coating. All reporting plants that print the board use the flexo printing technique. For box making cold glue and small amounts (< 0.1 kg/tonne nsp) of hot melt, tape (paper or plastic), plastic tear strip and stitch wire are used.
Data on cores and other packaging materials associated with paper reels and for packaging materials used around corrugated products was not collected and updated for 2021. Looking at previous data collections, the values showed little change over the years and other LCA studies show that the impacts of these packaging components are relatively small. Packaging for corrugated board products amounts to relatively small inputs of tape, wrappings of paper or plastic film, steel bands and pallets used as packaging of the saleable product. Pallets are also used in the logistic operations of the corrugated board industry. However, data on usage of pallets has not been collected. Previous iterations of the study have shown that the reported data on the use of pallets are confusing because of the complexity of the matter. Pallets can be returnable or one-way, only used internally in the plants and produced of wood, plastic or paper/ wood combinations. Previously some plants have reported their use in number of pallets while others have reported in kilogram pallet per tonne net saleable product, making it difficult to produce a meaningful figure.
Allocation to paper grades when a mill produces more than one paper grade
The basic data for raw material and chemical inputs are mainly based on recipes used for the production. When allocation was necessary, this was done according to mass production of the different papers.