Lignin-Containing Polyurethane Adhesives for Substrate Bonding
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Solution Overview
Problem
Current polyurethane adhesives often require additional surface treatment steps for improved adhesion, which are costly and pose safety and toxicological concerns, and are not universally applicable across different substrates and conditions.
Innovation Solution
A reactive polyurethane system comprising a hydrophobic polyol, a polyisocyanate, and a lignin compound, where lignin is used in solid form as an adhesion promoter and anti-sedimentation agent, eliminating the need for additional surface treatments and enhancing mechanical properties such as tensile strength and E-modulus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional surface treatment steps are performed to improve adhesion, then adhesion to substrate surfaces is improved, but process complexity and preparation costs increase
Solution Approach 1:
The polyol component is formulated to inherently provide adhesion promotion without requiring external surface treatment processes. The adhesive system serves itself by containing all necessary adhesion-promoting functionality within the composition, eliminating the need for separate surface preparation steps such as grinding, sanding, or chemical treatments.
Solution Approach 2:
The adhesive composition is designed to provide universal adhesion across multiple substrate types (metal, wood, concrete, plastics) through a single formulation. The polyol contains functional groups and additives that enable it to bond effectively to diverse surfaces without requiring substrate-specific treatment protocols, making the system multi-functional and universally applicable.
2Reliability
If additional surface treatment steps are performed to improve adhesion, then adhesion to substrate surfaces is improved, but safety and toxicological risks increase
Solution Approach 1:
The adhesive formulation achieves adhesion promotion through its intrinsic chemical composition rather than through harmful external treatments. The polyol contains safe, non-toxic adhesion-promoting agents that eliminate the need for hazardous surface preparation methods involving strong chemicals, solvents, or dust-generating mechanical treatments.
3Reliability
If lignin compound is added to polyurethane system, then adhesion promotion and mechanical properties are improved, but viscosity increases
Solution Approach 1:
The patent optimizes the concentration of lignin compound within a specific range (0.1-10 wt%, preferably 0.5-5 wt%) to achieve adhesion promotion while controlling viscosity increase. By carefully adjusting this parameter, the system maintains processability despite the presence of lignin, balancing performance enhancement with rheological constraints.
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 lignin-containing polyurethane system provides stable adhesives with improved mechanical properties and non-sag behavior, ensuring strong bonding across various substrates without the need for additional surface preparation, thus simplifying the adhesive bonding process and reducing costs.
Implementation Method 1
lignin is used in solid form as an adhesion promoter
Implementation Method 2
lignin is used in solid form as an adhesion promoter and anti-sedimentation agent
Data Source
AI summary
The present invention relates to generally relates to polyurethanes containing at least one lignin compound. In particular, the invention relates to a reactive polyurethane system comprising at least one polyol, at least one polyisocyanate and at least one lignin compound. In further aspects, the invention relates to a process for producing a polyurethane from a reactive system as disclosed, a polyurethane obtainable by such process, polyurethane adhesives, articles comprising cured polyurethane adhesives and a method for adhesive bonding.