Recycled Polyol via Acid Extraction
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Solution Overview
Problem
Existing methods for recycling polyurethane waste require extensive pre-sorting of materials, leading to inefficient and costly processes that result in polyols unsuitable for various applications due to high acid numbers and other impurities.
Innovation Solution
A two-step process involving reaction with dicarboxylic acid or anhydride and polyetherols, followed by reaction with short-chain diols or triols, produces a polyol mixture directly from unsorted polyurethane waste, minimizing pre-sorting requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If polyurethane waste is recycled using conventional alcoholysis or glycolysis processes, then polyol can be produced, but the polyol has high acid numbers and requires extensive pre-sorting of materials
Solution Approach 1:
The patent extracts and removes carboxylic acid groups from the polyol molecule through reaction with carboxylic acid anhydrides. This chemical extraction eliminates the harmful acid groups that cause high acid numbers in conventional recycled polyols, thereby improving polyol quality without requiring extensive pre-sorting of the polyurethane waste
Solution Approach 2:
The patent changes the chemical parameters of the polyol by reacting it with carboxylic acid anhydrides at controlled temperatures (100-200°C). This parameter change transforms the high-acid polyol into a low-acid or acid-free polyol, achieving high manufacturing precision without complex pre-sorting procedures
2Manufacturing precision
If polyurethane waste is sorted extensively before recycling, then polyol quality improves, but process efficiency and productivity decrease
Solution Approach 1:
The patent converts the harmful high-acid property of recycled polyol into a benefit by using the acid groups as reaction sites for further modification. The carboxylic acid anhydrides react with these acid groups to produce water or carboxylic acid byproducts, transforming the quality defect into a controlled chemical reaction that improves polyol quality while maintaining high productivity
3Reliability
If superstoichiometric amounts of hydroxyl groups are used in alcoholysis, then polyurethane cleavage is achieved, but material consumption and cost increase
Solution Approach 1:
The patent introduces carboxylic acid anhydrides as intermediary substances that mediate between the polyol and the desired low-acid product. These anhydrides react with the carboxylic acid groups in a controlled manner, providing an efficient pathway to remove acid groups without requiring excessive amounts of hydroxyl-containing reagents, thus reducing material consumption while maintaining reliable conversion
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 process yields high-quality, isocyanate-reactive polyols suitable for producing both rigid and flexible foams, with adjustable properties and reduced impurities, enabling cost-effective recycling without extensive material sorting.
Implementation Method 1
the polyurethane waste is first reacted with a reaction mixture containing at least one dicarboxylic acid or a dicarboxylic acid derivative, in particular a dicarboxylic anhydride and at least one polyetherol
Implementation Method 2
at temperatures of 170°C to 210°C to form a dispersion
Implementation Method 3
the dispersion obtained under a) is reacted with at least one short-chain diol and/or one short-chain triol at temperatures of 180°C to 230°C to form an isocyanate-reactive polyol dispersion
Data Source
AI summary
The invention relates to a polyol displaying specific product properties which allow it be identified accessibly as a recycled polyol, particularly as a recycled polyol obtained from a new specific recycling process.