PUR Foam Recycling Through Alcoholysis–Hydrolysis Separation
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Solution Overview
Problem
Existing methods for recycling polyurethane (PUR) materials, particularly end-of-life foam, face challenges in achieving high-quality recovery of polyol and diamine compounds without extensive purification, leading to inefficient and costly recycling processes.
Innovation Solution
A split-phase alcoholysis-hydrolysis method is employed using an alcoholising compound with a melting point below 200°C and a hydroxyl functionality of at least 2, allowing the mixture to separate into immiscible phases, with one phase containing high-quality recovered polyol and another phase containing diamine compounds, which can be reused for new PUR materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If conventional alcoholysis methods are used to recycle PUR materials, then polyol recovery is achieved, but extensive purification steps are required and process complexity increases
Solution Approach 1:
The invention divides the reaction mixture into two immiscible phases: an organic phase containing the recovered polyol and an aqueous phase containing diamine compounds. This phase segmentation allows automatic separation of products without requiring extensive purification steps, as each phase contains predominantly one type of product compound.
Solution Approach 2:
The invention introduces water as an intermediary substance that forms an immiscible aqueous phase with the organic polyol phase. This intermediary water phase acts as a separator and selective solvent, absorbing diamine compounds while leaving polyol in the organic phase, thereby enabling automatic product separation.
2Ease of manufacture
If physical recycling methods are used for PUR materials, then processing is simpler, but product quality is inferior due to thermoset character
Solution Approach 1:
The invention changes the chemical parameters of the PUR material through alcoholysis reaction, transforming the thermoset polyurethane into soluble polyol compounds and diamine compounds. This chemical parameter change enables the material to transition from an insoluble cross-linked structure to soluble individual molecules, allowing for high-quality recovery while maintaining process simplicity.
3Object-generated harmful factors
If incineration or landfill are used for EoL PUR foam, then waste disposal is achieved, but environmental pollution and economic loss occur
Solution Approach 1:
The invention recovers valuable polyol and diamine compounds from end-of-life PUR foam through alcoholysis, transforming waste material into reusable chemical constituents. Instead of discarding the foam through incineration or landfill, the process recovers the original building blocks (polyol and diamine) that can be reused to manufacture new PUR materials, thereby eliminating environmental pollution and economic loss associated with waste disposal.
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 enables the recovery of high-quality polyol and diamine compounds, facilitating their reuse in new PUR materials, creating a sustainable circular process with reduced waste production and minimal purification requirements.
Implementation Method 1
The most commonly used method in chemical depolymerisation of PUR materials is the alcoholysis method, sometimes referred to as glycolysis method, and involves mixing the PUR materials with one or more compounds containing at least two reactive hydroxyl groups, i.e. an alcoholising compound.
Implementation Method 2
allowing the mixture to separate into at least an upper phase and a lower phase, wherein the upper phase and the lower phase are immiscible phases
Implementation Method 3
subjecting the lower phase to at least one hydrolysis step, thereby forming a phase (B1) comprising the at least one diamine compound
Data Source
AI summary
A method for alcoholising and hydrolysing polyurethane (PUR) materials made from at least one polyol compound and at least one toluene diisocyanate based compound; wherein the method comprises the following steps: contacting the polyurethane material with at least one alcoholising compound, thereby forming a reaction mixture (M0) and allowing the polyurethane material and the alcoholising compound to react in said reaction mixture (M0), thereby forming a mixture (M); allowing the mixture (M) to separate into at least an upper phase and a lower phase, wherein phase (A) and phase (B) are two immiscible phases; subjecting phase (B) to at least one hydrolysis step, thereby forming a phase (B1); wherein the at least one alcoholising compound is characterized by a melting point of lower than 200° C.; wherein the at least one alcoholising compound is characterized by a hydroxyl functionality of at least 2; and with the proviso that the at least one alcoholising compound is not glycerol.