Paperboard Laminates with MFC Film for Stable Web Handling
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Solution Overview
Problem
Existing methods for producing laminates with microfibrillated cellulose (MFC) films face challenges such as brittleness leading to web handling difficulties, runnability problems, and web breaks during lamination processes, which are exacerbated by low moisture content and the use of humectants, causing delamination issues.
Innovation Solution
A method involving an MFC film with a moisture content of 5-20 weight-%, a specific tensile index ratio of 0.8-1.4, and an additional drying step to reduce moisture to less than 4 weight-% before lamination, mitigating brittleness and promoting dimensional stability, thereby enhancing web handling and lamination process efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If MFC film moisture content is reduced to improve dimensional stability and barrier properties, then brittleness increases causing web handling difficulties and runnability problems
Solution Approach 1:
The patent applies preliminary action by pre-conditioning the MFC film with a specific moisture content (5-20%) and tensile index ratio (0.8-1.4) before the lamination process. This preliminary preparation ensures the film has optimal mechanical properties for web handling during production, while subsequent drying to <4% moisture content provides the required dimensional stability in the final product.
2Reliability
If MFC film moisture content is reduced to enhance barrier properties, then brittleness increases leading to web breaks during lamination
Solution Approach 1:
The patent applies parameter changes by controlling the moisture content at different stages: maintaining 5-20% moisture during web handling to prevent brittleness, then reducing to <4% moisture before lamination to ensure barrier properties. The tensile index ratio is also controlled at 0.8-1.4 to balance mechanical properties throughout the process.
3Ease of operation
If humectants are added to reduce brittleness, then delamination issues occur during lamination
Solution Approach 1:
The patent applies the extraction principle by removing humectants from the MFC film formulation entirely. Instead of using humectants to maintain flexibility, the patent achieves web handling stability through controlled moisture content (5-20%) and optimized tensile index ratio (0.8-1.4), eliminating the source of delamination problems while maintaining lamination stability.
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
The method effectively reduces brittleness and web handling issues, ensuring stable lamination with MFC films by maintaining a low moisture content and appropriate tensile properties, while maintaining barrier properties and dimensional stability.
Implementation Method 1
further drying said MFC film of said second web to a moisture content of less than 4 weight-%
Implementation Method 2
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 MFC film is further dried to a moisture content of less than 4 weight-%. The first web and the second web are joined, after the further drying, using at least one adhesive layer provided between the webs so as to form the laminate. The MFC film has a moisture content of less than 4 weight-% at the joining. The invention relates also to a laminate and a packaging material comprising the laminate.