Polyurethane Depolymerization Using Tertiary Alcohols for Monomer Recovery
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Solution Overview
Problem
Existing methods for recycling polyurethane into its original monomers, such as polyols and amines, face challenges in achieving high yields and facile separation, particularly due to the incorporation of amines which alter foam composition and properties, and require additional steps for purification.
Innovation Solution
A method involving suspending polyurethane in a C4-C12 tertiary or C3-C10 secondary alcohol at temperatures between 150°C to 400°C to depolymerize it into polyols and amines, followed by separation using methods like aqueous-organic extraction or precipitation as salts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If glycolysis is used to recycle polyurethane into polyol and amines, then the original monomers are obtained, but additional purification steps are required to separate amines from water and other impurities
Solution Approach 1:
The patent introduces an organic solvent as an intermediary substance that facilitates the extraction and separation of amines from the reaction mixture. The solvent acts as a mediator between the aqueous phase containing amines and the organic phase, enabling efficient transfer and isolation of amine monomers without requiring complex multi-step purification procedures
Solution Approach 2:
The patent employs extraction techniques to separate amines from the glycolysis reaction mixture. By using appropriate solvents and separation methods, the amines are extracted from water and other impurities, achieving high purity recovery while simplifying the overall purification process
2Adaptability or versatility
If amines are incorporated into foam composition during recycling, then polyurethane can be reformulated, but the foam properties are altered and quality is reduced
Solution Approach 1:
The patent applies the principle of discarding and recovering by separating amines from the glycolysis reaction mixture and recovering them as pure monomers. This allows the amines to be isolated and then used in controlled amounts during foam formulation, enabling recyclers to adjust amine content precisely to maintain foam quality while still utilizing the recovered monomers
Solution Approach 2:
The patent utilizes parameter changes by controlling the amount and type of amine added during foam formulation. By adjusting amine concentration, selection, and timing of addition, the foam properties can be optimized to match original quality specifications while incorporating recycled content
3Productivity
If mechanical rebinding is used to recycle PU scrap, then material can be reused as filler, but the product quality is lower and product line is narrow
Solution Approach 1:
The patent applies the copying principle by recovering the original monomers (polyol and amines) that can be used to synthesize new polyurethane polymers with identical properties to the original material. This creates a chemical copy of the virgin material, enabling the production of high-quality products across the full product line rather than limited filler applications
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
Facilitates high-yield production of pristine polyol and amine monomers with minimal impurities, enabling the reuse of polyurethane in high-quality recycled products.
Implementation Method 1
heating the polyurethane suspension to a temperature in the range of 150° C. to 400° C. to provide said mixture comprising polyol(s) and amine(s)
Data Source
AI summary
The present invention relates to a method for production of a mixture comprising polyol(s) and amine(s) from a polyurethane, said method comprising the steps of: a) providing a starting material comprising the polyurethane, b) suspending the starting material comprising the polyurethane in a suspending agent comprising an alcohol to provide a polyurethane suspension, c) heating the polyurethane suspension to a temperature in the range of 150° C. to 400° C. to provide said mixture comprising polyol(s) and amine(s), wherein said alcohol is a C4-C8 tertiary alcohol. Another aspect involves the use of an alcohol selected from the group consisting of a C4-C12 tertiary alcohol and a C3-C10 secondary alcohol for catalysing the conversion of a polyurethane to provide polyol(s) and amine(s).