Lignin-Phenol-Formaldehyde Resin Viscosity Control
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Solution Overview
Problem
Existing methods for producing lignin-phenol-formaldehyde resins face issues with high viscosity due to lignin self-condensation and aggregate formation under neutral or alkaline conditions, limiting the reactivity of lignin with formaldehyde and requiring the use of harmful solvents like methanol.
Innovation Solution
Dissolving lignin in acidic conditions using phenol to prevent self-condensation, maintaining reactivity, and using a controlled pH and temperature to achieve a resin with controlled viscosity, eliminating the need for additional solvents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lignin is solubilised under neutral or alkaline conditions, then lignin solubility is improved, but self-condensation reactions occur increasing molecular weight and resin viscosity
Solution Approach 1:
The patent changes the pH parameter from neutral/alkaline to acidic conditions during lignin solubilisation. This parameter change prevents self-condensation reactions while maintaining lignin solubility, thereby controlling resin viscosity without sacrificing the ability to dissolve lignin.
2Quantity of substance
If lignin molecular weight increases due to self-condensation, then lignin solubility is improved, but reactivity towards formaldehyde decreases
Solution Approach 1:
The patent applies acidic conditions (pH parameter change) to solubilise lignin while preventing self-condensation. This maintains lignin at lower molecular weights, preserving its reactivity towards formaldehyde while achieving adequate solubility for resin formulation.
3Adaptability or versatility
If lignin content is increased in resin formulation, then sustainability is improved, but resin viscosity increases to undesirable levels
Solution Approach 1:
The patent uses acidic conditions during lignin solubilisation to prevent self-condensation and control molecular weight. This enables higher lignin content in the resin formulation to be achieved while maintaining acceptable viscosity levels, thus improving sustainability without compromising rheological properties.
4Object-affected harmful factors
If harmful solvents like methanol are used to reduce viscosity, then resin viscosity is controlled, but safety and environmental issues arise
Solution Approach 1:
The patent converts the potentially harmful self-condensation tendency of lignin into a benefit by using acidic conditions that control molecular weight growth. This eliminates the need for harmful viscosity-reducing solvents like methanol, as the controlled polymerisation under acidic conditions naturally produces resins with acceptable viscosity.
Solution Approach 2:
The patent extracts and eliminates the need for harmful external solvents by using acidic conditions to control lignin molecular weight during solubilisation. The process inherently controls viscosity through pH management, making additional solvent additives unnecessary.
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 lignin-phenol-formaldehyde resins with controlled viscosity and improved reactivity, suitable for various lignin types, reducing the need for separate viscosity-reducing solvents and enabling higher lignin content without performance loss, suitable for applications with low viscosity requirements.
Implementation Method 1
dissolution of a lignin material in a first fraction of phenol at a pH of 0.5-3.9, at a raised temperature
Implementation Method 2
dosing a first fraction of formaldehyde to provide a lignin-phenol-formaldehyde mixture and to result in a methylolation reaction
Implementation Method 3
forming a lignin-phenol-formaldehyde condensation mixture from the methylolated lignin-phenol mixture by adjusting the pH to ≥9.5 and agitating the mixture
Implementation Method 4
crosslinking the components of the condensation mixture resulting in a lignin-phenol-formaldehyde resin
Data Source
AI summary
The present invention relates to a method for solubilising a lignin material and controlling its molecular weight, in order to prevent the potential decrease in its reactivity, and thereby controlling the viscosity of both the lignin material and the obtained condensation product. The method thus comprises dissolving the lignin in acidic conditions using a first fraction of phenol, and then carrying out a methylolation in alkaline conditions, as well as a condensation and a crosslinking, in order to produce a final resin product.