Home-Compostable Composite Foils With Biodegradable Polyurethane Adhesive
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Solution Overview
Problem
Existing composite foils designed for industrial composting conditions do not degrade rapidly enough under home composting conditions, which typically have lower temperatures, and achieving both stability and rapid biodegradability with minimal environmental impact is challenging.
Innovation Solution
Aqueous polyurethane dispersion adhesive composed of at least 60% diisocyanates, polyesterdiols, and bifunctional carboxylic acids, with a glass transition temperature below 20°C, ensuring rapid decomposition into CO2 and water within 360 days at home composting temperatures (25±5°C).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional adhesives are used to bond composite foils, then stable adhesive bonding is achieved, but rapid biodisintegratability under home composting conditions is lost
Solution Approach 1:
The patent modifies the chemical composition parameters of the polyurethane adhesive by incorporating specific ratios of aliphatic diisocyanates (20-80 wt%), aromatic diisocyanates (0-80 wt%), and polyesterdiols (20-80 wt%), along with controlled amounts of monofunctional compounds and water (5-50 wt%). These compositional changes enable the adhesive to maintain bond stability while achieving home compostability with over 90% decomposition within 360 days at 25±5°C.
Solution Approach 2:
The adhesive is formulated as a composite polyurethane dispersion combining multiple diisocyanate types (aliphatic and aromatic), polyesterdiols, and hydrophilic modifiers in specific proportions. This composite structure provides both the mechanical stability needed for adhesive bonding and the chemical degradability required for home composting, resolving the contradiction between durability and biodegradability.
2Strength
If polyurethane adhesive composition is optimized for stability, then adhesive strength is improved, but decomposition rate under home composting conditions decreases
Solution Approach 1:
The patent establishes specific parameter ranges for adhesive composition: aliphatic diisocyanates (20-80 wt%), aromatic diisocyanates (0-80 wt%), polyesterdiols (20-80 wt%), and water content (5-50 wt%). Within these ranges, the adhesive achieves both sufficient bonding strength and rapid decomposition (>90% within 360 days at home composting temperatures), optimizing both strength and decomposition rate simultaneously.
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 adhesive-bonded composite foils achieve over 90% biodegradation into CO2 and water within 360 days at home composting temperatures, meeting the requirements for rapid biodisintegratability and environmental safety.
Implementation Method 1
a film of the polyurethane adhesive decomposes at home compost conditions to more than 90% by weight into CO2 and water within 360 days
Data Source
AI summary
The use of an aqueous polyurethane dispersion adhesive is described for producing composite foils which are biodisintegratable at home compost conditions where at least two substrates are adhesive-bonded to one another with use of the polyurethane dispersion adhesive, where at least one of the substrates is a polymer foil which is biodisintegratable at home compost conditions. At least 60% by weight of the polyurethane is composed of diisocyanates, polyesterdiols, and at least one bifunctional carboxylic acid selected from dihydroxy carboxylic acids and diamino carboxylic acids, wherein the polyurethane has no melting point above 20° C. or wherein the polyurethane has a melting point above 20° C. with an enthalpy of fusion lower than 10 J/g, and wherein a film of the polyurethane adhesive is biodegradable at home compost conditions.