Paperboard Laminate With Moisture-Controlled MFC Film
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Solution Overview
Problem
Existing methods for producing laminates with paper or paperboard substrates and microfibrillated cellulose (MFC) films face challenges with the brittleness of MFC films, leading to web handling difficulties and runnability problems during lamination processes.
Innovation Solution
A method involving the production of a laminate with a paper or paperboard substrate and an MFC film, where the MFC film has a moisture content of 5-20 weight-% and a specific ratio of machine direction to cross-direction tensile indices, followed by an additional drying step to reduce the moisture content to less than 4 weight-%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If MFC film is produced with low moisture content to improve barrier properties and dimensional stability, then the film becomes brittle and web handling difficulties occur during lamination processes
Solution Approach 1:
The patent applies parameter changes by controlling the moisture content of the MFC film within a specific range (5-20 weight-%) rather than using extremely low moisture content. This optimized parameter range maintains dimensional stability while preventing excessive brittleness, enabling smooth web handling during lamination processes without requiring additional plasticizers or humectants.
2Reliability
If MFC film moisture content is reduced to maintain barrier properties, then runnability problems occur during lamination
Solution Approach 1:
The patent resolves this contradiction by changing the moisture content parameter to an optimized range (5-20 weight-%). This parameter optimization maintains the barrier properties of the MFC film while ensuring adequate runnability during lamination, eliminating the need for additional moisture addition steps or plasticizer additives.
3Reliability
If additional drying step is added to reduce moisture content below 4 weight-%, then final barrier properties are enhanced but process complexity increases
Solution Approach 1:
The patent applies preliminary action by controlling the moisture content during the film formation and lamination processes itself, maintaining it within the optimized range of 5-20 weight-%. This preliminary control eliminates the need for subsequent additional drying steps, thereby enhancing barrier properties while avoiding increased process complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method effectively reduces the brittleness of MFC films during web handling in lamination processes, promoting dimensional stability and maintaining a low moisture content in the laminate, thereby mitigating runnability issues and enhancing the lamination process.
Implementation Method 1
dewater it by vacuum, gravitation, capillary dewatering, press dewatering or a combination of these on the wire or membrane
Implementation Method 2
capillary dewatering
Implementation Method 3
followed by drying or liquid evaporation
Implementation Method 4
joining said first web and said second web using at least one adhesive layer provided between said first web and said second web
Data Source
AI summary
The present invention relates to a method for producing a laminate comprising a paper or paperboard substrate and a microfibrillated cellulose (MFC) film. A first web comprising a paper or paperboard substrate is provided. A second web of an MFC film is provided, wherein the MFC film has: a) a content of MFC of 50-100 weight-% based on total dry weight; b) a moisture content of 5-20 weight-%, c) a ratio of a machine direction tensile index and a cross direction tensile index of 0.8-1.4. The first web and the second web are joined using at least one adhesive layer provided between the webs so as to form the laminate. The MFC film of the laminate is further dried to a moisture content of less than 4 weight-%. The invention relates also to a laminate and a packaging material comprising the laminate.