Foam Formed Fibrous Web with Microfibrillated Cellulose
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Solution Overview
Problem
The foam forming process in paper production results in high porosity and reduced strength properties, such as tensile strength and elastic modulus, making it unsuitable for printing and packaging papers and boards, while microfibrillated cellulose (MFC) incorporation leads to densification and increased drying energy requirements.
Innovation Solution
Incorporating microfibrillated cellulose with a pulp of greater fibre length into a foam formed with a surfactant and water, and then dewatering and drying the mixture on a forming fabric to produce a fibrous web with enhanced strength and bulk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If foam forming process is used to produce fibrous web, then bulk and porosity are increased, but tensile strength and elastic modulus are reduced
Solution Approach 1:
The patent uses a composite material system combining long fibres (providing bulk and structure) with microfibrillated cellulose (MFC, providing bonding strength). This composite approach allows the web to simultaneously achieve high bulk from the foam-formed long fibre network and high tensile strength from the MFC bonding bridges, resolving the contradiction between bulk and strength that plagues conventional foam forming.
2Volume of stationary object
If foam forming process is used to produce fibrous web, then bulk is increased, but elastic modulus is reduced
Solution Approach 1:
The composite of long fibres and MFC creates a structure where long fibres provide the bulky framework while MFC provides the stiff bonding connections. This resolves the contradiction by decoupling the bulk-providing function (long fibres in foam) from the stiffness-providing function (MFC bonds), allowing both high bulk and high elastic modulus to coexist.
3Manufacturing precision
If microfibrillated cellulose is incorporated into pulp suspension, then web formation is improved, but drying energy requirement increases
Solution Approach 1:
The patent replaces the conventional water-based dewatering process with foam forming, where air (gas) is used as the carrier phase instead of water (liquid). This fundamental phase change allows dewatering to occur during foam formation itself, rather than requiring separate high-energy drying steps, thus reducing drying energy while maintaining good web formation through the MFC-long fibre composite.
4Stability of the object's composition
If surfactant is used in foaming process, then foam stability is improved, but tensile strength is reduced
Solution Approach 1:
The patent extracts or removes the harmful effect of surfactants on tensile strength by using minimal surfactant quantities and rapidly replacing water with air during foam formation. This minimizes the time and extent of surfactant-fibre interaction, thereby preserving fibre bonding capacity while maintaining sufficient foam stability for web formation.
Solution Approach 2:
The patent changes the physical state parameter from liquid (water-based suspension) to gas (foam), which fundamentally alters the interaction between surfactant and fibres. In the foam phase, surfactant concentration at fibre surfaces is reduced, minimizing its negative impact on hydrogen bonding while maintaining foam stability through controlled air incorporation.
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 achieves a fibrous web with increased strength and bulk, suitable for various paper and board grades, while maintaining low density and improving print quality, and reduces energy consumption and refining costs.
Implementation Method 1
a foam of water and a surfactant
Implementation Method 2
to be discharged onto the forming fabric of a papermaking machine... with an air content of at least 65 %
Implementation Method 3
discharged onto the forming fabric of a papermaking machine
Data Source
Figure 1
AI summary
The invention relates to a fibrous web product such as paper, and a method for the preparation of such fibrous web. According to the method microfibrillated cellulose (MFC) together with a pulp of a greater fibre length, such as chemithermomechanical pulp (CTMP), are mixed with a foam of water and a sur- factant, the foam is supplied to a forming fabric of a paper or board machine, dewatered by suction of air through the forming fabric, and dried to the final web product. The method brings a high bulk in combination with a high Scott bond value, to provide improved wet and dry tensile strength for the paper and board products.