Multilayer Fibrous Web Z-Direction Strength via Defibration
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Solution Overview
Problem
Conventional methods for producing multi-layer fibrous webs, such as paper or cardboard, result in limited z-direction strength and high density with small volume, due to two-dimensional fiber alignment.
Innovation Solution
A method involving defibration and separation of a first fibrous material layer at a specific moisture content to form a porous layer with strong z-direction orientation, combined with couching with a second layer, achieving high volume and low density, and optionally adding further layers with controlled conveyor belt speeds and additives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional layer or sheet formation is used, then the production process is simple, but the z-direction strength is insufficient
Solution Approach 1:
The patent applies preliminary action by defibrating and separating the fibrous material layer before couching with the second layer. This pre-treatment creates individual fibers and fiber groups that can orient in the z-direction during the couching process, thereby achieving z-direction strength without requiring complex post-processing equipment
Solution Approach 2:
The patent transitions from two-dimensional (x/y plane) fiber alignment to three-dimensional alignment by introducing z-direction orientation through the defibration and couching process. The fibers are no longer confined to the plane of the web but are oriented perpendicular to it, adding a new dimensional component to the fiber arrangement
2Volume of moving object
If conventional layer formation is used, then the production cost is low, but the volume is small and density is high
Solution Approach 1:
The patent creates a porous fibrous structure through defibration and separation, which increases the web volume by introducing void spaces between fibers. This porous structure reduces the density (mass per unit volume) while maintaining the same mass of fibrous material, effectively achieving higher volume with lower density
3Strength
If defibration and separation is applied, then the z-direction strength is improved, but the process complexity increases
Solution Approach 1:
The defibration and separation steps are performed as preliminary actions before the couching operation. By preparing the fibrous material in advance (creating individual fibers and fiber groups), the subsequent couching process naturally achieves z-direction orientation without requiring additional complex equipment or post-processing steps
Solution Approach 2:
The patent changes the physical state and configuration parameters of the fibrous material through defibration and separation. The fibrous layer transitions from a compact mat structure to separated individual fibers and fiber groups, fundamentally altering the material's physical characteristics to enable z-direction orientation
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 produces a multi-layer fibrous web with enhanced z-direction strength, high rigidity, and good thermal insulation properties while reducing density, enabling cost-effective production.
Implementation Method 1
defibration and/or separation of the first fiber material layer at a moisture content of between 95 and 40% by weight to form individual fibers and/or fiber groups
Implementation Method 2
applying a first fibrous material suspension to a first permeable or non-permeable conveyor belt to form a first fibrous material layer
Data Source
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AI summary
The present invention relates to a method for producing a multilayer fibrous web (10), in particular a paper or cardboard web, comprising at least a first and a second fibrous layer (12, 14), wherein the method comprises at least the following steps: applying a first fibrous suspension (16) to a first permeable or non-permeable conveyor belt (18) to form a first fibrous layer (12); defibrating and/or singulating the first fibrous layer (12) at a moisture content between 95 and 40 wt.% to form individual fibers and/or fiber groups (28); forming a porous fibrous layer (36) by means of the individual fibers and/or fiber groups (28) of the first fibrous layer (12); and couching the porous fibrous layer (36) with the second fibrous layer to form the multilayer fibrous web (10).The invention further relates to a device for producing a multilayer fibrous web (10), in particular a paper or cardboard web, comprising at least a first and a second fibrous layer (12, 14), wherein the device (20) has at least one fiberizing device (48) for fiberizing and/or separating the first fibrous layer (12) into individual fibers and/or fiber groups (28) at a moisture content between 95 and 40 wt.%.