Within SUW – The International Development Group for Corrugated Board, high class corrugated board research has been conducted since 1968. During the last decade one research focus has been on the heat and moisture transfer in the corrugator. Simulation programs for the single facer and for the double backer were written. Consequences of different operating strategies for the heating table were evaluated. It was shown that for double board, a decreasing temperature along the heating table gives a higher temperature of the middle glue line. Mechanisms for heat transport through the corrugated board paper layers have also been investigated. It was shown that moisture transports a considerable amount of heat through the board. Right now a project is on-going where the levelling out of temperature and moisture in the corrugated stack after corrugated board production will be simulated.SUW´s other research focus, also on-going for a decade, is dealing with the gluability of corrugated board. Still the gluing process in corrugated board production is performed with a starch-water solution. Important gluing parameters like the glue solid content, gluing temperature, gluing time, paper properties and the chemical glue content were investigated. In this project, also the cause of gluing defects was evaluated. For the first time, ”brittle bonding”, a gluing defect in the corrugator, could be simulated. Some results from these simulations will be shown.
Corrugated board is the dominant transport packaging material. All corrugated board blanks have to pass converting machines in order to produce packaging. The corrugated board converting process should be precise to avoid waste and machine stops. There are standards existing that state tolerances for the corrugated board converting process. These tolerances can be set for corrugated board properties like warp and dimensions or tolerances to be achieved for the ready packaging. The standards are issued among others by FEFCO, GIFCO, VDW, and SUW (The International Development Group of Corrugated Board), but also by some large brand owners. A comparison of tolerances mentioned in the most important standards was conducted. Further actual tolerances of corrugated board and corrugated board packages converted in several corrugated board plants and used at the brand owners were investigated. At corrugated board plants and brand owners the ambient temperature and humidity were measured. Also the temperature and humidity in the corrugated board stacks and the warp of the sheets were investigated. The runnability in the converting machines was evaluated by machine drivers. Some of these results will be shown. Furthermore thickness, folding strength of creases and misalignment, fishtailing, gap of manufactures joint and width and length of folded blanks of slotted boxes were determined. The results indicate that stricter tolerances for corrugated board are possible. The results of the plant trials will be used to propose a new SUW standard with new tolerance levels e.g. for warp and dimensions of the corrugated board sheets and packages. The new tolerances will be discussed within the corrugated board branch, converting machine suppliers and users of corrugated board. New stricter tolerances for corrugated board packaging in the converting process contribute to a better competitiveness of this renewable and sustainable packaging material in the future.
For the first time in the Bioeconomy research program at RISE, corrugatedboard has an own research area. Research is building around the main driving forcesin the corrugated board value chain like e-commerce, improved box performance anddigital printing. The main weakness of corrugated board, its moisture sensitivity, isalso addressed.These main driving forces and weaknesses of corrugated board are mirrored in thethemes of this large research program area:Fibre sorption and deformation mechanismsFundamental knowledge on the mechanisms behind moisture sorption and deformation on fibre level is developed to increase moisture and creep resistance throughmodification of paper materials. State of the art methods for characterization ofthe fibre ultra- and nano-structure such as Fourier transform infra-red spectroscopy(FTIR), small angle X-ray scattering (SAXS), and wide angle X-ray scattering (WAXS)give new insights on mechanisms and clarify effects of moisture as well as chemicalmodifications.Papermaking for improved base sheetsConcepts that are explored are fibre-based strength additives produced with novelrefining techniques, and modified ZD-profiles in the sheet for better mechanical properties.Box mechanicsMechanical performance of structures such as corrugated board boxes can be predicted through physically based mathematical modelling by taking the behaviour ofthe constituent materials as well as the geometry into account. Appropriate materialmodels for the corrugated board are identified and finite element models for simulation of corrugated board packaging performance are developed.Tool for inkjet printability on corrugatedThere is a genuine need for improved inkjet printability on corrugated materials thanksto rapid development in e-commerce as well as digitalization along the corrugatedvalue chain. Effective measurement methods and knowledge around ink-substrateinteractions are developed to enable board producers and converters to have effective product development and predictable printability on not only liners but also oncorrugated materials.
The ModelPACK Project by Inventia is part of FP6, the EU's Framework Program for research and technological development. This software tool predicts the structural properties of the corrugated board and the performance of the end product, allowing for optimization of the fiber used. The system also provides accurate predictions concerning the performance of the finished box. The company offers training in the use of ModelPACK and in the importance of material properties for optimal packaging performance. It also characterizes papers, boards and boxes to expand the database used with the tool. The company creates customer specific models or data structures for an optimization of packaging design.
The "water-free bonding of corrugated board" concept focuses on thedevelopment, waste management and market potential of a new corrugated board production method. It has earlier been shown that by integrating PLA into paper, certain mechanical properties of corrugated board papers can be enhanced. These enhanced papers have been used for producing corrugated board. Corrugated board is usually produced by gluing the corrugated board paper layers with a starch suspension. This process is reducing the mechanical paper strength and is also energy consuming, as the water added by the starch suspension in the process has to be evaporated. In this study, two new water-free joining techniques for corrugated board have been investigated: PLA-welding, which melts the inherent PLA of the paper to create a bond and using PLA as an adhesive. Both techniques have shown promising results and are recommended for further investigation, however, replacing starch glue with PLA seems to be a solution closer to the market. For the material to fit in a future circular economy it is important that the waste is managed in a way that is sustainable for the environment and the society. Repulp ability testing in combination with literature studies indicate that the new material would be possible to recycle, and that the new material could function in every step described in the EU Waste Framework Directive.
In the Research program “Improving corrugated board performance” at RISE several case studies on transport packaging in e-commerce were conducted. Field tests with ecommerce packages with mixed products and laboratory tests with the same products were compared. Laboratory transport tests have been carried out using the standard ISTA 6 Amazon – Over boxing. The field study was carried out through sending packages between two cities in Sweden. All packaging were equipped with field data recorders during each trial, which captured the data relevant to compare transport simulation and the real environment during the e-commerce logistics. A comparison between Amazon testing and reality was made. Similarities between the field studies and laboratory tests are identified. When comparing the results with this and other studies, it was concluded that the ISTA 6 Amazon Ship-in-own-container (SIOC) and ISTA 6 Amazon Over boxing (OB) are demanding tests and this especially concerning the drop tests.