Nanofibrillated Cellulose Fibrous Substrate for Coating Base Paper
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Solution Overview
Problem
Current coating base papers face challenges in achieving high opacity and mechanical stability while minimizing pigment requirements, as existing methods result in agglomeration of pigments that reduce opacity and increase costs due to high titanium dioxide usage, and environmental concerns necessitate alternative solutions.
Innovation Solution
Incorporating 1 to 20 wt.% nanofibrillated cellulose (NFC) with a specific surface area of at least 125 m2/g into the cellulose fibers of the fibrous substrate material, which enhances pigment distribution and mechanical cohesion, allowing for reduced pigment content and improved opacity without compromising air permeability or strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the areal density of the paper is increased to reach higher opacity, then the opacity improves, but the cost increases due to higher pigment and filler consumption
Solution Approach 1:
The patent changes the physical-chemical parameters of the cellulose fibers by nanofibrillation, reducing their diameter to nanometer scale (1-100 nm) while increasing specific surface area to at least 125 m2/g. This parameter transformation allows achieving high opacity with reduced pigment content, as the nanofibrillated structure provides enhanced light scattering efficiency per unit mass compared to conventional fibers.
Solution Approach 2:
The patent creates a composite fibrous substrate combining nanofibrillated cellulose (NFC) with conventional cellulose fibers. The NFC component (1-50 wt%, preferably 5-20 wt%) forms a network that enhances light scattering and mechanical properties, allowing the system to achieve high opacity with reduced overall pigment requirements compared to 100% conventional fiber substrates.
2Illumination intensity
If the pigment content is increased to improve opacity, then the opacity improves, but the mechanical strength deteriorates due to agglomeration
Solution Approach 1:
The patent transforms the fiber diameter parameter from micrometer scale to nanometer scale (1-100 nm), creating nanofibrillated cellulose with vastly increased specific surface area (≥125 m2/g). This parameter change enables effective pigment dispersion at lower concentrations, preventing agglomeration while maintaining high opacity, thereby preserving mechanical strength.
Solution Approach 2:
The nanofibrillated cellulose acts as an intermediary between pigment particles and the fiber matrix. The extensive surface area of NFC provides numerous anchoring points for pigment particles, preventing their agglomeration and ensuring uniform distribution throughout the substrate, thus maintaining both opacity and mechanical integrity.
3Strength
If conventional cellulose fibers are used, then the mechanical stability is maintained, but the pigment distribution is poor leading to reduced opacity
Solution Approach 1:
The patent creates a composite system where nanofibrillated cellulose (1-50 wt%) is combined with conventional cellulose fibers. The NFC component provides superior pigment distribution and light scattering properties, while the conventional fibers maintain the bulk mechanical structure. This composite approach achieves both high opacity and mechanical stability synergistically.
Solution Approach 2:
The patent applies local quality enhancement by introducing nanofibrillated cellulose specifically to address pigment distribution and light scattering needs, while retaining conventional fibers for structural support. The NFC concentrates in regions requiring enhanced optical properties, creating local improvements without compromising overall mechanical stability.
4Illumination intensity
If nanofibrillated cellulose with high specific surface area is used to improve pigment distribution, then opacity improves, but the air permeability may deteriorate
Solution Approach 1:
The patent optimizes the nanofibrillation parameters to achieve a specific surface area of at least 125 m2/g while controlling fiber length and diameter. This parameter optimization balances light scattering efficiency with porosity maintenance, ensuring that the NFC network provides high opacity without excessively densifying the substrate structure to the point of blocking air permeability.
Solution Approach 2:
The patent utilizes the porous network structure inherent in nanofibrillated cellulose arrangements. The NFC forms a three-dimensional network with controlled porosity that allows air flow while providing extensive surface area for light scattering. The porous structure maintains breathability and air permeability even at high NFC loadings.
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 use of NFC in the fibrous substrate material achieves higher opacity with lower pigment content, reducing costs and environmental impact, while maintaining or improving mechanical stability and printability, and allowing for reduced dust formation and binder usage.
Implementation Method 1
The NFC has a specific surface (SSA) of at least 125 m2/g... achieves higher opacity with lower pigment content
Implementation Method 2
the addition of NFC in the process of forming strongly pigment-containing porous, absorptive coating base papers or prepregs allows for a significantly more homogeneous embedding of the pigment species within the fiber network
Data Source
AI summary
A fibrous substrate material for producing a porous coating base paper or prepreg comprises a planar impregnatable structure made of cellulose fibers, which contains at least one pigment species and optionally contains further additives conventional for paper. The cellulose fibers contain a proportion of 1 to 20 wt.-% of nanofibrillated cellulose (NFC). A method for producing the fibrous substrate material comprises the steps of:providing an aqueous suspension containing a cellulose containing material and an admixture of said pigment species and, optionally, further additives conventional for paper,sheet forming,drying.The cellulose containing material contains a proportion of 1 to 20 wt.-% of NFC with a specific surface (SSA) of at least 125 m2/g.