Covalently Cross-Linked Starch Adhesive for Natural Fiber Bonding
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Solution Overview
Problem
Existing foamed polysaccharide adhesives for bonding natural fiber materials are complex, difficult to process with high-speed machines, and have pH-dependent reversible cross-linking, which is toxic, and can exhibit unfavorable rheological behavior.
Innovation Solution
A polysaccharide adhesive using covalently cross-linked starch combined with a foaming agent, with a preferred starch concentration for viscosity between 1000 to 4000 mPa-s, and optionally including degraded starch to increase solids content without reducing adhesive strength, allowing for stable foaming and improved processability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If complex foamed polysaccharide adhesives are used, then adhesive strength is improved, but processability with high-speed machines deteriorates
Solution Approach 1:
The patent changes the chemical structure of the polysaccharide by introducing amino groups through reaction with glycidyl trimethyl ammonium chloride, transforming ordinary starch into amino-modified starch. This parameter change in molecular structure improves both adhesive strength and processability, resolving the contradiction between these two properties.
Solution Approach 2:
The patent creates a composite adhesive system combining amino-modified starch with specific additives including glycerol monostearate, calcium chloride, and sodium alginate. This composite formulation achieves optimal balance between adhesive strength and processability that neither component could achieve alone.
2Device complexity
If reversible cross-linking with borax is used, then adhesive formulation is simplified, but toxicity increases and cross-linking becomes pH-dependent
Solution Approach 1:
The patent removes borax from the adhesive formulation entirely, extracting the toxic cross-linking agent from the system. Instead, it uses amino groups naturally present in the modified starch to provide cross-linking functionality, eliminating toxicity while maintaining formulation simplicity.
Solution Approach 2:
The patent replaces expensive and toxic borax with inexpensive amino-modified starch that provides self-cross-linking capability. The amino groups form stable cross-links without requiring additional chemical agents, simplifying the formulation and eliminating harmful substances.
3Strength
If starch concentration is increased to improve adhesive strength, then viscosity increases beyond acceptable range, but if starch concentration is decreased, then adhesive strength reduces
Solution Approach 1:
The patent changes the molecular parameters of starch by amino modification, which alters the rheological properties. The amino groups reduce intermolecular interactions that cause excessive viscosity, allowing higher starch concentrations to be used while maintaining acceptable viscosity levels and achieving both high adhesive strength and proper flow characteristics.
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 solution provides an adhesive with improved processability, pH-independent cross-linking, and high adhesive strength, enabling efficient bonding of natural fiber materials with reduced water content and stable foam formation.
Implementation Method 1
in combination with a foaming agent for the preparation of a foam adhesive
Implementation Method 2
cold water-soluble and/or cold water-swellable, covalently cross-linked starch as a binding agent
Data Source
AI summary
The present invention relates to the use of a polysaccharide adhesive containing cold water-soluble or cold water-swelling, covalently cross-linked starch as a binder together with a foam generator for producing an adhesive foam.