Influence of pulp type on the three-dimensional thermomechanical convertibility of paperboard

Laukala, Teija; Ovaska, Sami-Seppo; Tanninen, Panu; Pesonen, Antti; Jordan, Juha; Backfolk, Kaj

doi:10.1007/s10570-019-02294-3

Cited by 13 publications

(9 citation statements)

References 29 publications

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“…The dwell time values were evenly distributed according to a feasible range of the standard industry dwell times. The influence of forming parameters and conditions such as moisture and temperature in press forming was established by Östlund et al 10 and a more thorough description of the press-forming process can be found in paper by Laukala et al 11…”

Section: Methodsmentioning

confidence: 99%

Measurement of changes in torsional stiffness of press‐formed paperboard packages induced by heat load utilizing a developed measuring device

et al. 2021

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The press-forming process and the effects of parameter variation on the forming process have attracted great interest lately. The dimensional accuracy of the formed trays and the rigidity and stability of the packages are crucial factors for functionality in packaging lines, especially in fast operating machinery. The torsional stiffness of trays must be at a sufficient level to ensure the functionality in subsequent processes and logistics. The objective of this study was to develop and build a device for measuring the torsional stiffness of whole tray packages, to verify its functionality and to investigate the effect of heat load transferred to paperboard material on the torsional stiffness of the formed trays. The operation of the novel torsional stiffness tester was confirmed, and the tester was found to be suitable for measuring the thermal response of the sample materials and the effect of the fibre direction. Thus, the analysed material does not need to have a homogeneous stiffness property since the differences are noticeable in the measurement results. In addition, the results indicate that tray blanks should be die cut in the machine direction of the paperboard. The torsional stiffness of the tray packages increases, and the outer dimensions decrease as a function of the heat input. The first feature is desirable for packaging functionality and the second feature can be compensated by competent packaging design. To conclude, the use of higher mould temperatures is recommendable if the integrity of the package material is not compromised.

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Section: Methodsmentioning

confidence: 99%

Measurement of changes in torsional stiffness of press‐formed paperboard packages induced by heat load utilizing a developed measuring device

et al. 2021

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“…In the present case, the reference CTMP sheets had a 3D elongation of 2 mm, which in the system used corresponded to a value of 0.5%. For comparison, the system has previously yielded a 3D elongation of 2% for the 190 g/m 2 commercial three-ply board used to prepare pressed trays, and 1.2% for CTMP sheets with a fines content of 11.7% (Laukala et al 2019). The 3D elongation results for the handsheets are shown in Fig.…”

Section: D Elongation Tests and The Relationship Between 3d Elongation And Sheet Propertiesmentioning

confidence: 99%

“…This, alongside related apparent contradictions connected to possible pre-treatments, is illustrated in Table 1 on behalf of some of the properties measured from paperboard on routine. Laukala et al (2019) reported that the characteristics of fracture in press-forming (fixed blank mode) depended on the pulp type used and they found that with CTMP pulp, fracture typically occurred in areas with a locally high fine content, while regions beneath the surface fines that contained longer fibres were found to be relatively intact. Such a failure and rupture of the surface has been linked to the tensile failure of bonds (Page 1969;Seth 2005).…”

Section: Introductionmentioning

confidence: 99%

“…The characteristic behaviour of the bulky and stiff CTMP fibres supports the hypothesis that sheet failure in 3D may be especially due to weak interfibre bonding. Although CTMP has a lower extensibility than kraft pulp (Laukala et al 2019), CTMP offers the bulk and stiffness needed in many packaging applications, and has environmental benefits (such as a higher yield and chlorine-free bleaching) over kraft pulp, while simultaneously being less prone to taste-and smell-related issues than mechanical pulps. These factors make CTMP-based boards interesting for 3D formation, especially if ways can be found to enhance the extensibility.…”

Section: Introductionmentioning

confidence: 99%

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Three-dimensional thermomechanical converting of CTMP substrates: effect of bio-based strengthening agents and new mineral filling concept

et al. 2021

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The effects of bio-based strengthening agents and mineral filling procedure on the 3D elongation of chemi-thermomechanical pulp (CTMP) handsheets with and without mineral (PCC) filling have been investigated. The 3D elongation was measured using a press-forming machine equipped with a special converting tool. The strength of the handsheets was altered using either cationic starch or microfibrillated cellulose. Precipitated calcium carbonate (PCC) was added to the furnish either as a slurry or by precipitation of nano-sized PCC onto and into the CTMP fibre. The 3D elongation of unfilled sheets was increased by the dry-strengthening agents, but no evidence on the theorised positive effect of mineral fill on 3D elongation was seen in either filling method. The performance of the strengthening agent depended on whether the PCC was as slurry or as a precipitated PCC-CTMP. The starch was more effective with PCC-CTMP than when the PCC was added directly as a slurry to the furnish, whereas the opposite was observed with microfibrillated cellulose. The 3D elongation correlated positively with the tensile strength, bursting strength, tensile stiffness, elastic modulus and bending stiffness, even when the sheet composition was varied, but neither the strengthening agent nor the method of PCC addition affected the 3D elongation beyond what was expectable based on the tensile strength of the sheets. Finally, mechanisms affecting the properties that correlated with the 3D elongation are discussed.

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“…First, it is possible to improve the formability via the pulp, before the paper-making process begins. Low and high consistency refining [28] as well as the selection of the appropriate fibers [23,32,44] can contribute to making the sheet more extensible. The addition of polymer modifiers has been explored [66], as well as using water or heat during the forming process [35,65].…”

Section: Introductionmentioning

confidence: 99%

Micro-mechanical modeling of the paper compaction process

et al. 2021

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Double-roll compaction is a process to create extensible paper and paperboard suitable for replacing plastic in 3D forming applications. Understanding the macro- and micro-mechanisms governing the compaction process allows increasing the stretch potential while maintaining sufficient strength and bending stiffness. In this work, we approach the compaction process of paperboard with micro-mechanical methods featuring the unprecedented level of details otherwise inaccessible with currently available experimental tools. The loading scheme is based on experiments and continuum level simulations. The different levels of compaction and their continuous impact on the fibers’ geometry, void closures, and irreversible deformation of the fibers are thoroughly characterized. We find that the structural changes are concentrated in the fibers oriented within 30 degrees of the direction of compaction. The deformation accumulates primarily in the wall of the fibers in the form of irreversible strains. The spring-back effect beyond the compaction is negligible. For the first time, the role of normal and frictional fiber-to-fiber interactions in the compaction process is investigated and quantified. The frictional interaction between the fibers has a surprisingly low impact on the outcome of the compaction process, and the normal interaction between the fibers has a dominant response. The consequence of this finding is potentially limited impact of the surface modifications targeting the friction.

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Influence of pulp type on the three-dimensional thermomechanical convertibility of paperboard

Cited by 13 publications

References 29 publications

Measurement of changes in torsional stiffness of press‐formed paperboard packages induced by heat load utilizing a developed measuring device

Measurement of changes in torsional stiffness of press‐formed paperboard packages induced by heat load utilizing a developed measuring device

Three-dimensional thermomechanical converting of CTMP substrates: effect of bio-based strengthening agents and new mineral filling concept

Micro-mechanical modeling of the paper compaction process

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