Lignin Emulsion Water-Resistant Paper Sizing
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Solution Overview
Problem
Current papermaking methods using oil-based chemicals like alkenyl succinic anhydride (ASA) and alkyl ketene dimer (AKD) for water resistance face issues with repulpability and biodegradability, and the use of starch from the food industry is not sustainable, while traditional sizing methods fail to provide adequate moisture and water resistance.
Innovation Solution
A method involving a lignin emulsion with a surface tension of 35-60 N/m, comprising a mixture of lignin dispersion in an aqueous medium with a concentration of at least 50 g/l and a carboxylic acid with a carbon chain length of at least 12 carbon atoms, added to a fibrous web during the semi-wet phase of the papermaking process, to enhance moisture and water resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oil-based chemicals (ASA or AKD) are used as sizing agents to achieve water resistance, then moisture and water resistance is improved, but repulpability and biodegradability deteriorate
Solution Approach 1:
The invention changes the chemical composition parameters by replacing oil-based sizing agents with a water-based composition containing lignin, carboxylic acid, and their reaction product. This parameter change maintains water resistance functionality while eliminating the harmful effects of oil-based chemicals on biodegradability and repulpability
Solution Approach 2:
The invention uses readily available, inexpensive materials (lignin and carboxylic acid) that can be easily degraded and repulped, replacing expensive and persistent oil-based chemicals. The water-based composition is designed to be environmentally friendly and sustainable
2Strength
If starch from food industry is used to improve strength, then strength is improved, but sustainability deteriorates
Solution Approach 1:
The invention replaces food industry starch with lignin, a waste product from papermaking that is abundant, inexpensive, and sustainable. The lignin-based composition provides strength improvement without compromising sustainability, as lignin is a renewable resource that does not compete with food production
3Ease of manufacture
If traditional sizing methods are used, then ease of manufacture is maintained, but moisture and water resistance is insufficient
Solution Approach 1:
The invention performs preliminary action by pre-reacting lignin with carboxylic acid to form a reaction product with enhanced water resistance properties. This pre-prepared composition is then easily applied to the paper during the papermaking process, combining manufacturing simplicity with improved moisture and water resistance
Solution Approach 2:
The invention creates a composite material system combining lignin, carboxylic acid, and their reaction product to achieve synergistic effects. This composite composition provides superior moisture and water resistance compared to traditional sizing methods while remaining easy to manufacture
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 process results in a paper with improved resistance to aqueous penetration, maintaining strength in moist conditions and providing better moisture and water resistance compared to traditional methods, while being more sustainable and stable, with increased compressive strength and reduced water absorption.
Implementation Method 1
a lignin emulsion with a surface tension of 35-60 N/m comprising a mixture of a lignin dispersion in an aqueous medium
Implementation Method 2
at least one carboxylic acid having a carbon chain length of at least 12 carbon atoms
Data Source
AI summary
The present disclosure relates to the field of papermaking, especially to the manufacture of paper with improved moisture- and water-resistance. The present disclosure also relates to a paper with improved moisture- and water-resistance obtained by the process as well as compositions useful in the process of making moisture- and water-resistant paper.