Oxidized Lignin Surface Sizing Agent for Paper
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional surface sizing agents using lignin struggle to penetrate deeply into paper surfaces due to high molecular weight and viscosity, leading to reduced hydrophobic effects and increased complexity in the paper production process, especially when high temperatures are required for activation.
Innovation Solution
A surface sizing agent containing 0.1 to 50% lignosulfonate and 0.1 to 50% lignin, combined with hydroxylated polymers and hydrophobic materials, is developed, allowing for deeper penetration and improved solubility at a weakly basic pH, enabling direct application without pH adjustment and reducing dust development during processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If lignin with high average molar mass is used as surface sizing agent, then the paper strength is increased, but the penetration into paper surface is reduced and viscosity increases
Solution Approach 1:
The lignin molecule is segmented into smaller units through oxidative depolymerization, reducing the average molar mass from high molecular weight to a range of 500-5000 Da. This segmentation allows the lignin to penetrate paper surfaces more effectively while maintaining sufficient strength properties through controlled molecular weight reduction.
Solution Approach 2:
The average molar mass parameter of lignin is changed from high (conventional) to a specific range of 500-5000 Da through oxidative treatment. This parameter change optimizes both penetration capability and paper strength, resolving the contradiction between these two properties.
2Reliability
If high temperature treatment is applied to activate lignin surface, then the surface activation is achieved, but the process complexity and cost increase due to requiring separate plant transfer
Solution Approach 1:
The activation temperature parameter is changed from conventional high temperatures (240°C) to a lower range (60-80°C) through the use of peroxide-based oxidation. This parameter change enables surface activation to be performed directly in the paper machine, eliminating the need for separate high-temperature treatment plants and reducing process complexity.
Solution Approach 2:
Peroxide-based oxidizing agents are introduced as intermediaries to enable lignin surface activation at lower temperatures. These intermediaries facilitate the chemical modification of lignin without requiring extreme thermal conditions, thus allowing the process to be integrated into the existing paper machine workflow.
3Reliability
If lignin is dissolved and applied with glycerin for surface hydrophobic treatment, then the hydrophobic effect is improved, but the surface remains wet due to glycerin's hygroscopic nature
Solution Approach 1:
Glycerin is extracted (removed) from the surface treatment composition. The invention achieves hydrophobic surface treatment using only oxidized lignin dissolved in water, eliminating the hygroscopic glycerin component that caused surface wetness while maintaining the desired hydrophobic effect through lignin's inherent properties.
Solution Approach 2:
The invention replaces the glycerin-lignin mixture with a simpler water-soluble oxidized lignin solution. This disposable-like simplification removes the problematic hygroscopic component while retaining the essential hydrophobic functionality through the modified lignin structure.
4Quantity of substance
If alkaline earth metals are added in large amounts to open lignin cluster surface area, then the solubility is improved, but the penetration of starch into paper surface is reduced
Solution Approach 1:
Alkaline earth metals are extracted (removed) from the treatment composition. The invention achieves both high solubility and good starch penetration by using peroxide-based oxidation alone, eliminating the need for salting-in with alkaline earth metals and their associated negative effects on starch penetration.
Solution Approach 2:
Peroxide-based oxidizing agents serve as intermediaries to achieve lignin solubilization without requiring alkaline earth metals. This intermediary approach provides the necessary solubility enhancement while avoiding the harmful effect of large hydrodynamic radius that prevents starch penetration.
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 agent achieves a more durable, homogeneous, and hydrophobic paper surface with enhanced air permeability and printability, reducing the need for additional synthetic sizing agents and minimizing undissolved lignin particles, thus improving the overall paper production efficiency and surface properties.
Implementation Method 1
through oxidative processes with oxidizing agents such as oxygen, air or hydrogen peroxide as well as high temperature treatments of alkaline lignin at over 160° C. molecular chains, especially of hemicelluloses and to a certain extent also of lignin are depolymerized
Implementation Method 2
lignin can penetrate better into the outer layers of the paper surface the lower its molecular weight or its average molar mass or its hydrodynamic radius
Implementation Method 3
The alkalisation of lignin with alkaline earth metals is also not new and is known to those skilled in the art as the 'salting-in' effect (according to Roberts et al. 1996). Such a large amount of alkaline earth metals, i.e., salting-in, naturally leads to an opening of the specific surface of the lignin cluster
Implementation Method 4
in the course of the separation of lignin from black liquor, for example, the molecular structure of the lignin is present in condensed form during precipitation with sulphuric acid
Data Source
AI summary
Surface sizing agents for paper and/or cardboard contain lignin and lignin sulfonates and at least one further surface-finishing substance, wherein it contains 0.1 to 50% by weight, preferably 5 to 20% by weight of a lignosulfonate source, 0.1 to 50% by weight, preferably 5 to 25% by weight of lignin, in particular kraft lignin and at least one further surface-finishing substance selected from the group of hydroxylated polymers, such as starch, PVOH, natural or synthetic hydrophobic materials, such as tall oil, tall oil soap or refined products thereof or hydrophobic materials, such as synthetic or natural waxes, styrenes, butadiene, acrylates, alkyl ketene dimer and oils thereof, such as AnKD, alkenyl succinic acid anhydride and the remainder water as a solvent and/or suspending agent, as well as processes for the production and use of the surface sizing agent.