MFC-Paper Laminate Drying on Heated Metal Belt Support
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Solution Overview
Problem
Existing methods for producing laminates with microfibrillated cellulose (MFC) layers on paper substrates face challenges such as poor barrier properties, adhesion issues, and difficulties in handling and drying, leading to inefficiencies and environmental impacts due to non-renewable materials.
Innovation Solution
A method involving the use of a metal belt support to cast and dry a wet MFC layer on a paper substrate, utilizing non-contact drying equipment and heated metal belt support to achieve efficient water removal and strong adhesion, eliminating the need for adhesives and reducing environmental impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a free-standing MFC film is produced by wet laid technique and laminated using adhesive layers, then the MFC layer can be formed on paper substrate, but film additives are removed during dewatering and adhesive increases non-renewable components
Solution Approach 1:
The patent extracts the MFC layer formation process from the conventional wet laid technique with dewatering wire. Instead of using a dewatering wire that removes additives, the invention uses a porous support that allows water and additives to pass through while retaining the MFC layer on the paper substrate, thereby preventing additive loss.
Solution Approach 2:
The patent introduces a porous support as an intermediary between the MFC suspension and the paper substrate. This porous support mediates the dewatering process by allowing water and additives to pass through while supporting the MFC layer formation, eliminating the need for adhesive layers and preventing additive removal.
2Reliability
If very fine MFC is used to improve barrier properties, then oxygen barrier properties are enhanced, but MFC passes through or clogs the wire during dewatering
Solution Approach 1:
The patent removes the dewatering wire from the process entirely and replaces it with a porous support. This extraction allows very fine MFC to be used without the problem of passing through or clogging a wire, as the porous support has controlled pore sizes that retain fine MFC while allowing water passage.
Solution Approach 2:
The patent uses a porous support with controlled pore structure to replace the solid dewatering wire. The porous material allows water to pass through while retaining very fine MFC particles, enabling the use of fine MFC for improved barrier properties without manufacturing difficulties.
3Strength
If adhesive layers are used to laminate MFC film to paper substrate, then strong adhesion is achieved, but the amount of non-renewable and non-recyclable components increases
Solution Approach 1:
The patent extracts the adhesive layer from the lamination process by using a porous support that enables direct bonding between the MFC layer and paper substrate. The porous support facilitates water removal and close contact between layers, allowing adhesion without additional adhesive materials.
Solution Approach 2:
The porous support acts as a temporary intermediary during the lamination process, enabling the MFC layer to bond directly to the paper substrate through controlled dewatering and close contact, eliminating the need for adhesive mediators while achieving strong adhesion.
4Ease of operation
If MFC suspension with low solids content is used, then the suspension is easy to handle, but high water content transfers to paper substrate making coating process difficult
Solution Approach 1:
The porous support serves as an intermediary that manages water transfer during coating. It allows controlled dewatering of the MFC suspension, preventing excessive water from transferring to the paper substrate while maintaining suspension flowability for easy handling.
Solution Approach 2:
The porous support with controlled pore structure enables selective water removal from the MFC suspension during coating, maintaining the suspension's ease of handling while preventing water overload on the paper substrate that would complicate the coating process.
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 enables the production of laminates with improved oxygen barrier properties and strong adhesion between the paper substrate and MFC layer, enhancing material efficiency and reducing environmental footprint.
Implementation Method 1
heated metal belt support to achieve efficient water removal
Implementation Method 2
forming a wet MFC layer by casting said MFC suspension on a casting surface of a metal belt support; joining said paper substrate web with said wet MFC layer
Implementation Method 3
at least one drying step which comprises subjecting said laminate structure to drying by at least one non-contact drying device
Data Source
AI summary
The present invention relates to a method for producing a laminate (8) comprising a paper substrate and a microfibrillated cellulose (MFC) layer. An MFC suspension comprising 25-90 weight-% of MFC and 10-50 weight-% of a filler component is provided. The suspension has a dry content of 2.5-50 weight-%. A wet MFC layer (1) is formed by casting the suspension on a metal belt support (2). A paper substrate having a Gurley Hill air permeability value of less than 10000 s/100 ml is provided and joined with the wet MFC layer positioned on the metal belt support to form a laminate structure (7). The laminate structure positioned on the metal belt support is subjected to water removal to form the laminate. The water removal comprises at least one drying step which comprises drying by at least one non-contact drying device (9), wherein the metal belt support is heated during the at least one drying step. The invention relates also to a laminate and a packaging material comprising